Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

High-performance and small-sized heat exchangers have been demanded due to the miniaturization and higher output of electronic devices, lasers, and energy harvesting/storage systems. Graphene nanosheet suspension has attracted attention as a next-generation nanofluid because of its high thermal conductivity and low pressure drop, while being dispersed stably without any additives. Graphene-based nanofluids have been mostly investigated using graphene oxide, and there are a few studies on pure graphene because of the limitation in mass production and stabilization at high concentrations of graphene. In this study, we prepared a 10 wt. % high-concentration few-layer graphene suspension by pulverizing graphite particles. Scanning electron microscopy, atomic force microscopy, and Raman spectra confirmed the few-layer graphene is formed in the suspension. The thermal conductivity of the suspension increased with concentration and suddenly jumped at a specific concentration. Furthermore, a significant improvement in thermal conductivity of >40% compared to base liquid was confirmed at 10 wt. % graphene content. A similar trend was observed for electrical resistance; 10 wt. % graphene suspension showed 62% lower resistance than that of 1 wt. %. These results suggest the percolation of graphene in a liquid, which has not been observed for graphene-based materials in previous research.

DOI： 10.1063/5.0210446

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Anodic electrochemical exfoliation of graphite in a simple two-electrode configuration using inexpensive and industrially available sulfuric acid is an excellent process for the mass production of graphene oxide. In this study, the effects of the structure of the graphite sheet, voltage and current, and electrolyte concentration on the structure of the exfoliated products and their potential use as a catalyst support were investigated. The results showed that graphite structure is a factor affecting the uniformity of the electrolytic reaction, that voltage/current is an important factor that can determine whether expansion or exfoliation of the graphite anode is preferentially caused, and that electrolyte concentration is an important factor determining the atomistic structure of the exfoliated products. In addition, they showed excellent ability as catalyst supports for a molecular metal complex showing heterogeneous electrocatalytic hydrogen production. Of note is that the catalytic currents are dependent on the structure such as size, defects, and oxidation degree of exfoliated products.

DOI： 10.1016/j.electacta.2024.143893

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DOI： 10.3390/coatings14030248

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

In this work, we systematically investigated the magnetically responsive behavior of a photonic crystal consisting of graphene oxide nanosheets and water, leading to the switching of its structural color by applying a magnetic field.

DOI： 10.1039/d3nr06114k

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Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s41467-024-44706-4

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Herein, we have engineered graphene oxide through pH change and freeze drying to get three-dimensional alkaline graphene oxide, and the resulting solid electrolyte exhibited efficient anion conductivity behavior.

DOI： 10.1039/d4ya00059e

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society on Water Environment  

DOI： 10.2965/jwet.23-071

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Publishing type：Research paper (scientific journal)   Publisher：The Carbon Society of Japan  

DOI： 10.7209/carbon.020405

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Language：Japanese   Publisher：岡山歯学会  

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

Graphene shows promise as an alternative material for strain sensors, due to its excellent properties, which can overcome the limitations of conventional metal ones. However, current graphene-based strain sensors were fabricated from chemically reduced graphene oxide (rGO) and suffered from low linearity and large hysteresis in sensor response as well as high initial resistance. These issues should be caused by functional groups and defects remaining on the rGO. Herein, highly crystalline rGO is employed for the fabrication of the strain sensor. The porous rGO sponge with low defect density is prepared in bulk scale via the ethanol-associated thermal process at ultra-high temperature. The obtained rGO sensor exhibits improved linearity, low initial resistance, and very small hysteresis owing to the high crystallinity of the rGO. Composite of rGO with nano-diamond, which has a role as nanospacer to separate the rGO layers, is found to be very effective to enhance the sensitivity.

DOI： 10.35848/1347-4065/ad0cdb

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ad0cdb/pdf

Publishing type：Research paper (scientific journal)   Publisher：MYU K.K.  

DOI： 10.18494/sam4473

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Language：English   Publishing type：Research paper (scientific journal)  

Practical applications like very thin stress-strain sensors require high strength, stretchability, and conductivity, simultaneously. One of the approaches is improving the toughness of the stress-strain sensing materials. Polymeric materials with movable cross-links in which the polymer chain penetrates the cavity of cyclodextrin (CD) demonstrate enhanced strength and stretchability, simultaneously. We designed two approaches that utilize elastomer nanocomposites with movable cross-links and carbon filler (ketjenblack, KB). One approach is mixing SC (a single movable cross-network material), a linear polymer (poly(ethyl acrylate), PEA), and KB to obtain their composite. The electrical resistance increases proportionally with tensile strain, leading to the application of this composite as a stress-strain sensor. The responses of this material are stable for over 100 loading and unloading cycles. The other approach is a composite made with KB and a movable cross-network elastomer for knitting dissimilar polymers (KP), where movable cross-links connect the CD-modified polystyrene (PSCD) and PEA. The obtained composite acts as a highly sensitive stress-strain sensor that exhibits an exponential increase in resistance with increasing tensile strain due to the polymer dethreading from the CD rings. The designed preparations of highly repeatable or highly responsive stress-strain sensors with good mechanical properties can help broaden their application in electrical devices.

DOI： 10.1021/acspolymersau.3c00010

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Language：English   Publishing type：Research paper (scientific journal)  

This work reports the synthesis of high surface area reduced graphene oxides using L-ascorbic acid as a reducing agent by precisely controlling the interaction between graphene oxide and L-ascorbic acid. Based on the structural characterization, such as textural properties (specific surface area, pore structure), crystallinity, and carbon chemical state, we identified that the temperature and reaction time are critical parameters to control the stacking degree of the final reduced product. Besides, by performing a time course analysis of the reaction, we identified the side products of the reducing agent by LC-MS and verified the reduction mechanism. Following our results, we proposed an optimum condition for producing a graphene derivative adsorbent with a high surface area. This graphene derivative was tested in an aqueous solution with organic and inorganic pollutants such as methylene blue, methyl orange, and cadmium.

DOI： 10.1002/cplu.202300328

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.20710/dojo.94.4_245

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

Graphene-oxide (GO) nanosheets, which are oxidized derivatives of graphene, are regarded as promising building blocks for functional soft materials. Especially, thermoresponsive GO nanosheets have been widely employed to develop smart membranes/surfaces, hydrogel actuators, recyclable systems, and biomedical applications. However, current synthetic strategies to generate such thermoresponsive GO nanosheets have exclusively relied on the covalent or non-covalent modification of their surfaces with thermoresponsive polymers, such as poly(N-isopropylacrylamide). To impart a thermoresponsive ability to GO nanosheets themselves, we focused on the countercations of the carboxy and acidic hydroxy groups on the GO nanosheets. In this study, we established a general and reliable method to synthesize GO nanosheets with target countercations and systematically investigated their effects on thermoresponsive behaviors of GO nanosheets. As a result, we discovered that GO nanosheets with Bu4N+ countercations became thermoresponsive in water without the use of any thermoresponsive polymers, inducing a reversible sol-gel transition via their self-assembly and disassembly processes. Owing to the sol-gel transition capability, the resultant dispersion can be used as a direct writing ink for constructing a three-dimensionally designable gel architecture of the GO nanosheets. Our concept of "countercation engineering" can become a new strategy for imparting a stimuli-responsive ability to various charged nanomaterials for the development of next-generation smart materials.

DOI： 10.1021/acsami.3c07820

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Language：English   Publishing type：Research paper (scientific journal)  

Covalent functionalization of graphene oxide (GO) with boron dipyrromethenes (BODIPYs) was achieved through a facile synthesis, affording two different GO-BODIPY conjugates where the main difference lies in the nature of the spacer and the type of bonds between the two components. The use of a long but flexible spacer afforded strong electronic GO-BODIPY interactions in the ground state. This drastically altered the light absorption of the BODIPY structure and impeded its selective excitation. In contrast, the utilisation of a short, but rigid spacer based on boronic esters resulted in a perpendicular geometry of the phenyl boronic acid BODIPY (PBA-BODIPY) with respect to the GO plane, which enables only minor electronic GO-BODIPY interactions in the ground state. In this case, selective excitation of PBA-BODIPY was easily achieved, allowing to investigate the excited state interactions. A quantitative ultrafast energy transfer from PBA-BODIPY to GO was observed. Furthermore, due to the reversible dynamic nature of the covalent GO-PBA-BODIPY linkage, some PBA-BODIPY is free in solution and, hence, not quenched from GO. This resulted in a weak, but detectable fluorescence from the PBA-BODIPY that will allow to exploit GO-PBA-BODIPY for slow release and imaging purposes.

DOI： 10.1002/chem.202300266

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsaenm.3c00103

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Language：English   Publishing type：Research paper (scientific journal)  

Peritumoral brain invasion is the main target to cure glioblastoma. Chemoradiotherapy and targeted therapies fail to combat peritumoral relapse. Brain inaccessibility and tumor heterogeneity explain this failure, combined with overlooking the peritumor microenvironment. Reduce graphene oxide (rGO) provides a unique opportunity to modulate the local brain microenvironment. Multimodal graphene impacts are reported on glioblastoma cells in vitro but fail when translated in vivo because of low diffusion. This issue is solved by developing a new rGO formulation involving ultramixing during the functionalization with polyethyleneimine (PEI) leading to the formation of highly water-stable rGO-PEI. Wide mice brain diffusion and biocompatibility are demonstrated. Using an invasive GL261 model, an anti-invasive effect is observed. A major unexpected modification of the peritumoral area is also observed with the neutralization of gliosis. In vitro, mechanistic investigations are performed using primary astrocytes and cytokine array. The result suggests that direct contact of rGO-PEIUT neutralizes astrogliosis, decreasing several proinflammatory cytokines that would explain a bystander tumor anti-invasive effect. rGO also significantly downregulates several proinvasive/protumoral cytokines at the tumor cell level. The results open the way to a new microenvironment anti-invasive nanotherapy using a new graphene nanomaterial that is optimized for in vivo brain delivery.

DOI： 10.1002/smll.202208227

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Polymer properties can be tuned by the addition of filler materials such as carbon-base materials and inorganic materials. In recent years, 2D filers as additives for polymers have extensively been studied. Among them, functionalized hexagonal boron nitride (FBN) improves polymers’ physical properties. In this study, we prepared 27 types of FBNs by using different ball milling parameters in the presence of amine molecules. Ball mill conditions, such as the ratios of h-BN and the amine, rotation speeds, and treatment times of ball milling, were investigated, and then, the FBNs were covalently bonded with polyimide (PI) in all specimens. An optimum FBN-PI composite showed tensile strength and tensile modulus of 151.1 MPa and 3.8 GPa, respectively. Finally, we found that the tensile strength and modulus were increased to 159.2 MPa and 3.9 GPa by addition of a small amount of graphene oxide (GO) that were combined with FBN and PI. The ball milling and covalent bonding approach efficiently developed high-performance BN-polymer composite films.

DOI： 10.1016/j.flatc.2023.100489

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Language：English   Publishing type：Research paper (scientific journal)  

The rational design of a stable and catalytic carbon cathode is crucial for the development of rechargeable lithium-oxygen (LiO2 ) batteries. An edge-site-free and topological-defect-rich graphene-based material is proposed as a pure carbon cathode that drastically improves LiO2 battery performance, even in the absence of extra catalysts and mediators. The proposed graphene-based material is synthesized using the advanced template technique coupled with high-temperature annealing at 1800 °C. The material possesses an edge-site-free framework and mesoporosity, which is crucial to achieve excellent electrochemical stability and an ultra-large capacity (>6700 mAh g-1 ). Moreover, both experimental and theoretical structural characterization demonstrates the presence of a significant number of topological defects, which are non-hexagonal carbon rings in the graphene framework. In situ isotopic electrochemical mass spectrometry and theoretical calculations reveal the unique catalysis of topological defects in the formation of amorphous Li2 O2 , which may be decomposed at low potential (∼ 3.6 V versus Li/Li+ ) and leads to improved cycle performance. Furthermore, a flexible electrode sheet that excludes organic binders exhibits an extremely long lifetime of up to 307 cycles (>1535 h), in the absence of solid or soluble catalysts. These findings may be used to design robust carbon cathodes for LiO2 batteries.

DOI： 10.1002/advs.202300268

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Wound infection is inevitable in most patients suffering from extensive burns or chronic ulcers, and there is an urgent demand for the production of bactericidal dressings to be used as grafts to restore skin functionalities. In this context, the present study explores the fabrication of plasma-derived fibrin hydrogels containing bactericidal hybrids based on graphene oxide (GO). The hydrogels were fully characterized regarding gelation kinetics, mechanical properties, and internal hydrogel structures by disruptive cryo scanning electron microscopies (cryo-SEMs). The gelation kinetic experiments revealed an acceleration of the gel formation when GO was added to the hydrogels in a concentration of up to 0.2 mg/mL. The cryo-SEM studies showed up a decrease of the pore size when GO was added to the network, which agreed with a faster area contraction and a higher compression modulus of the hydrogels that contained GO, pointing out the critical structural role of the nanomaterial. Afterward, to study the bactericidal ability of the gels, GO was used as a carrier, loading streptomycin (STREP) on its surface. The loading content of the drug to form the hybrid (GO/STREP) resulted in 50.2% ± 4.7%, and the presence of the antibiotic was also demonstrated by Raman spectroscopy, Z-potential studies, and thermogravimetric analyses. The fibrin-derived hydrogels containing GO/STREP showed a dose-response behavior according to the bactericidal hybrid concentration and allowed a sustained release of the antibiotic at a programmed rate, leading to drug delivery over a prolonged period of time.

DOI： 10.1021/acsmaterialslett.2c01044

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Language：English   Publishing type：Research paper (scientific journal)  

In this work, the mechanisms of radical generation on different functionalized graphene oxide (GO) conjugates under near-infrared (NIR) light irradiation are investigated. The GO conjugates are designed to understand how chemical functionalization can influence the generation of radicals. Both pristine and functionalized GO are irradiated by a NIR laser, and the production of different reactive oxygen species (ROS) is investigated using fluorimetry and electron paramagnetic resonance to describe the type of radicals present on the surface of GO. The mechanism of ROS formation involves a charge transfer from the material to the oxygen present in the media, via the production of superoxide and singlet oxygen. Cytotoxicity and effects of ROS generation are then evaluated using breast cancer cells, evidencing a concentration dependent cell death associated to the heat and ROS. The study provides new hints to understand the photogeneration of radicals on the surface of GO upon near infrared irradiation, as well as, to assess the impact on these radicals in the context of a combined drug delivery system and phototherapeutic approach. These discoveries open the way for a better control of phototherapy-based treatments employing graphene-based materials.

DOI： 10.1002/smll.202207229

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Dynamic nuclear polarizing (DNP) technique in nuclear magnetic resonance (NMR) is a powerful tool for a microanalysis. Nevertheless, it has not been applied to analyses of carbon materials such as graphene oxide (GO) and amorphous carbon effectively because of the electroconductivity and microwave absorption of the carbon, which attenuate the enhancement effect of DNP. For this study, we applied DNP-NMR to analyses of surface functional groups on GO and sucrose-derived carbon to evaluate the method. The 1H–13C cross-polarization magic-angle spinning (CP/MAS) DNP-NMR of a GO sample with AMUPol (polarizing agent) showed 2.2-times-enhanced peaks of 13C in epoxide, bonding to hydroxyl group, and in the graphene plane. Signal enhancement was raised by AMUPol radicals neighboring the surface functional groups and the graphene planes on GO particles, although attenuation by temperature rise must be considered. Furthermore, additional new peaks assigned to CH3 group on the GO particle surface were highly enhanced and were observed clearly only by the accumulations of 64 scans. For sucrose-derived carbon, DNP-NMR clearly revealed the –OH group on the carbon surface or carbon edge by heat treatment, which was not possible using conventional CP/MAS experiments. Cross Effect was found to be dominant in signal enhancements of the functional groups on GO and sucrose-derived carbon samples, except for the CH3 groups on GO. The CH3 enhancement is ascribed mainly to the Overhauser effect or solid effect.

DOI： 10.1016/j.carbon.2023.02.010

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Nanostructured 3D silica-based materials can be designed using a low-dimensional template. Various composites composed of graphene oxide (GO) and silica have been investigated. However, to improve the performance of GO/silica nanostructure (GSN), the exploitation of the assembly method and the effect of combining GO and silica on the hybrid structure need to be elucidated. In this study, novel mesoporous GSNs were developed using two self-assembly methods: particle attaching-induced self-assembly (PAISA) and polymerization- and evaporation-induced self-assembly (PEISA). The synthesized GSNs obtained using each method were analyzed to determine the effect of combining silica with GO in each method on the porosity of GSNs. The former method introduced silica nanoparticles into GO, and aligned pores similar to the particle size were formed. In the latter method, synthesized GSN had broad mesopores, and a higher surface area derived from the silica particles randomly formed inside/outside GO layers. Both GSNs have specific surface areas close to that of the introduced silica, suggesting that the porosity of GSNs can be controlled by selecting the appropriate silica structure and its synthesis. Furthermore, GSN had a higher pore volume than silica itself, suggesting the formation of a hierarchical structure by introducing GO.

DOI： 10.1246/bcsj.20220279

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Language：English   Publishing type：Research paper (scientific journal)  

We herein report an organic transistor functionalized with a phenylboronic acid derivative and graphene oxide for the quantification of plasma glucose levels, which has been achieved by the minimization of interferent effects derived from physical protein adsorption on the detection electrode.

DOI： 10.1039/d2cc07009j

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Language：English   Publishing type：Research paper (scientific journal)  

Bottom-up electrochemical synthesis of atomically thin materials is desirable yet challenging, especially for non-vanderWaals (non–vdW) materials. Thicknesses below a few nanometers have not been reported yet, posing the question how thin can non-vdW materials be electrochemically synthesized. This is important as materials with (sub-)unit–cell thickness often show remarkably different properties compared to their bulk form or thin films of several nanometers thickness. Here, a straightforward electrochemical method utilizing the angstrom-confinement of laminar reduced graphene oxide (rGO) nanochannels is introduced to obtain a centimeter-scale network of atomically thin (<4.3 Å) 2D-transition metal oxides (2D-TMO). The angstrom-confinement provides a thickness limitation, forcing sub-unit–cell growth of 2D-TMO with oxygen and metal vacancies. It is showcased that Cr2O3, a material without significant catalytic activity for the oxygen evolution reaction (OER) in bulk form, can be activated as a high-performing catalyst if synthesized in the 2D sub-unit–cell form. This method displays the high activity of sub-unit–cell form while retaining the stability of bulk form, promising to yield unexplored fundamental science and applications. It is shown that while retaining the advantages of bottom-up electrochemical synthesis, like simplicity, high yield, and mild conditions, the thickness of TMO can be limited to sub-unit–cell dimensions.

DOI： 10.1002/adma.202301506

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INTRODUCTION: The antibacterial activity of graphene oxide (GO) has been widely explored and tested against various pathogenic bacterial strains. Although antimicrobial activity of GO against planktonic bacterial cells was demonstrated, its bacteriostatic and bactericidal effect alone is not sufficient to damage sedentary and well protected bacterial cells inside biofilms. Thus, to be utilized as an effective antibacterial agent, it is necessary to improve the antibacterial activity of GO either by integration with other nanomaterials or by attachment of antimicrobial agents. In this study, antimicrobial peptide polymyxin B (PMB) was adsorbed onto the surface of pristine GO and GO functionalized with triethylene glycol. METHODS: The antibacterial effects of the resulting materials were examined by evaluating minimum inhibitory concentration, minimum bactericidal concentration, time kill assay, live/dead viability staining and scanning electron microscopy. RESULTS AND DISCUSSION: PMB adsorption significantly enhanced the bacteriostatic and bactericidal activity of GO against both planktonic cells and bacterial cells in biofilms. Furthermore, the coatings of PMB-adsorbed GO applied to catheter tubes strongly mitigated biofilm formation, by preventing bacterial adhesion and killing the bacterial cells that managed to attach. The presented results suggest that antibacterial peptide absorption can significantly enhance the antibacterial activity of GO and the resulting material can be effectively used not only against planktonic bacteria but also against infectious biofilms.

DOI： 10.3389/fcimb.2023.1209563

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DOI： 10.1021/acsanm.3c01600

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DOI： 10.1246/bcsj.20230059

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DOI： 10.2965/JWET.23-040

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Language：English   Publishing type：Research paper (scientific journal)  

Nanoscale graphene-based materials (GBMs) enable targeting subcellular structures of the nervous system, a feature crucial for the successful engineering of alternative nanocarriers to deliver drugs and to treat neurodisorders. Among GBMs, graphene oxide (GO) nanoflakes, showing good dispersibility in water solution and being rich of functionalizable oxygen groups, are ideal core structures for carrying biological active molecules to the brain, such as the neuropeptide Y (NPY). In addition, when unconjugated, these nanomaterials have been reported to modulate neuronal function per se. Although some GBM-based nanocarriers have been tested both in vitro and in vivo, a thorough characterization of covalent binding impact on the biological properties of the carried molecule and/or of the nanomaterial is still missing. Here, a copper(I)-catalyzed alkyne-azide cycloaddition strategy was employed to synthesize the GO-NPY complex. By investigating through electrophysiology the impact of these conjugates on the activity of hippocampal neurons, we show that the covalent modification of the nanomaterial, while making GO an inert platform for the vectorized delivery, enhances the duration of NPY pharmacological activity. These findings support the future use of GO for the development of smart platforms for nervous system drug delivery.

DOI： 10.1021/acsanm.2c03409

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The failure of endodontic treatment is directly associated with microbial infection in the root canal or periapical areas. An endodontic sealer that is both bactericidal and biocompatible is essential for the success of root canal treatments. This is one of the vital issues yet to be solved in clinical dental practice. This in vitro study assessed the effectiveness of graphene oxide (GO) composites GO-CaF2 and GO-Ag-CaF2 as endodontic sealer materials. Dentin slices were coated with either the GO-based composites or commonly used root canal sealers (non-eugenol zinc oxide sealer). The coated slices were treated in 0.9% NaCl, phosphate-buffered saline (PBS), and simulated body fluid (SBF) at 37˚C for 24 hours to compare their sealing effect on the dentin surface. In addition, the radiopacity of these composites was examined to assess whether they complied with the requirements of a sealer for good radiographic visualization. Scanning electron microscopy showed the significant sealing capability of the composites as coating materials. Radiographic images confirmed their radiopacity. Mineral deposition indicated their bioactivity, especially of GO-Ag-CaF2, and thus it is potential for regenerative application. They were both previously shown to be bactericidal to oral microbes and cytocompatible with host cells. With such a unique assemblage of critical properties, these GO-based composites show promise as endodontic sealers for protection against reinfection in root canal treatment and enhanced success in endodontic treatment overall.

DOI： 10.18926/AMO/64122

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Language：Japanese   Publisher：岡山歯学会  

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsmaterialslett.2c00805

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Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

Toward macroscopic applications of graphene, it is desirable to preserve the superior properties of single-layer graphene in bulk scale. However, the AB-stacking structure is thermodynamically favored for multilayer graphene and causes strong interlayer interactions, resulting in property degradation. A promising approach to prevent the strong interlayer interaction is the staking order reduction of graphene, where the graphene layers are rotated in-plane to form a randomly stacking structure. In this study, we propose a strategy to effectively decrease the stacking order of multilayer graphene by incorporating nanospacers, cellulose nanofibers, or nano-diamonds (NDs) in the formation process of porous graphene sponges. We conducted an ultrahigh temperature treatment at 1500 °C with ethanol vapor for the reduction and structural repair of graphene oxide sponges with different concentrations of the nanospacers. Raman spectroscopy indicated an obvious increase in the random-stacking fraction of graphene by adding the nanospacers. The x-ray diffraction (XRD) analysis revealed that a small amount of the nanospacers induced a remarkable decrease in ordered graphene crystalline size in the stacking direction. It was also confirmed that a layer-number increase during the thermal treatment was suppressed by the nanospacers. The increase in the random-stacking fraction is attributed to the efficient formation of randomly rotated graphene through the ethanol-mediated structural restoration of relatively thin layers induced by the nanospacers. This stacking-order-reduced graphene with bulk scale is expected to be used in macroscopic applications, such as electrode materials and wearable devices.

DOI： 10.1063/5.0103826

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The improvement of bioactivity, biocompatibility, and corrosion resistance of metal substrates are the common goals in biomaterials research. Graphene oxide (GO) for its outstanding chemical and mechanical properties has attracted researchers. Relatively, Hydroxyapatite (HA) has been employed as a biocompatible coating material to improve bone fixation property, durability, and osteointegration of an implant. Therefore, in this study, a composite of GO and HA (GO-HA) was coated on medical grade stainless steel (MS 316L) substrate by anodic electrochemical deposition to improve mechanical peeling resistance, corrosion resistance, and bioactivity. The coating's morphology and ability to cover the substrate surface were analyzed by SEM-EDS, XPS, and the surface roughness by AFM. The coating's structural properties were analyzed with Raman spectroscopy. The investigation of corrosion inhibition involved open circuit potential, EIS, and Voltammetry analysis. The standard salt test, an American Society for Testing and Materials (ASTM) G48A for stainless steel substrate, has also been studied. The bioactivity of the coated substrates was investigated in simulated body fluid (SBF). Significant enhancement of corrosion potential as well as bioactivity of the coated substrates has been achieved. GO-HA coating onto MS 316L was strongly adherent, uniform, and able to provide optimum surface roughness. Hence, the combination of the improved surface properties and bioactivity indicates that GO-HA coating can be utilized to overcome apposite limitations of bare MS 316L surface in clinical settings.

DOI： 10.1016/j.mtsust.2022.100193

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We report the electrochemical oxidation of graphite sheets using BF4 salts, and direct electrochemical reduction of its product to prepare two-dimensional carbon materials efficiently. Electrochemical oxidation enables the synthesis of graphene oxide (GO) under milder conditions than those required for chemical oxidation, e.g., a strong oxidant in concentrated acid. In this work, graphite sheet was electrochemically oxidized with BF4 salt electrolyte solution, and its product was electrochemically reduced in PBS. In the present method, the use of BF4 salt allows the successful electrochemical synthesis of high-quality, uniform GO without the use of an acid. Furthermore, the non-destructive nature of the method provides a GO product that can be subjected to electrochemical reduction to form reduced GO. Thus, the method provides facile access to high-quality two-dimensional carbon materials in a manner that has the potential for mass production.

DOI： 10.1016/j.electacta.2022.141087

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We developed a multitimescale time-resolved electron diffraction setup by electrically synchronizing a nanosecond laser with our table-top picosecond time-resolved electron diffractometer. The setup covers the photoinduced structural dynamics of target materials at timescales ranging from picoseconds to submilliseconds. Using this setup, we sequentially observed the ultraviolet (UV) photoinduced bond dissociation, radical formation, and relaxation dynamics of the oxygen atoms in the epoxy functional group on the basal plane of graphene oxide (GO). The results show that oxygen radicals formed via UV photoexcitation on the basal plane of GO in several tens of picoseconds and then relaxed back to the initial state on the microsecond timescale. The results of first-principles calculations also support the formation of oxygen radicals in the excited state on an early timescale. These results are essential for the further discussion of the reactivities on the basal plane of GO, such as catalytic reactions and antibacterial and antiviral activities. The results also suggest that the multitimescale time-resolved electron diffraction system is a promising tool for laboratory-based molecular dynamics studies of materials and chemical systems.

DOI： 10.1021/acs.jpca.2c04075

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGERNATURE  

Graphene is an allotrope of carbon consisting of a single-atom-thick honeycomb lattice nanostructure. Among the various preparation methods for graphene, the liquid-phase exfoliation of graphite is mass-producible and cost-effective. To facilitate the exfoliation of graphite in organic solvents, polymers can be employed as dispersants. We synthesized polymer dispersants with various monomer ratios and molecular weights and investigated the efficient acquisition of graphene from graphite. Graphene with a uniform thickness was obtained when graphite was exfoliated using an optimized polymer dispersant. The optimized polymer enabled a high yield and concentration of graphene using liquid-phase exfoliation.

DOI： 10.1038/s41428-022-00684-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The regulation of intracellular ions' overload to interrupt normal bioprocesses and cause cell death has been developed as an efficient strategy (named as ion-interference therapy/IIT) to treat cancer. In this study, we design a multifunctional nanoplatform (called BSArGO@ZIF-8 NSs) by in situ growth of metal organic framework nanoparticles (ZIF-8 NPs) onto the graphene oxide (GO) surface, subsequently reduced by ascorbic acid and modified by bovine serum albumin. This nanocomplex causes the intracellular overload of Zn2+, an increase of reactive oxygen species (ROS), and exerts a broad-spectrum lethality to different kinds of cancer cells. BSArGO@ZIF-8 NSs can promote cell apoptosis by initiating bim (a pro-apoptotic protein)-mediated mitochondrial apoptotic events, up-regulating PUMA/ NOXA expression, and down-regulating the level of Bid/p53AIP1. Meanwhile, Zn2+ excess triggers cellular dysfunction and mitochondria damage by activating the autophagy signaling pathways and disturbing the intracellular environmental homeo-stasis. Combined with the photothermal effect of reduced GO (rGO), BSArGO@ZIF-8 NSs mediated ion-interference and photothermal combined therapy leads to effective apoptosis and inhibits cell proliferation and angiogenesis, bringing a higher efficacy in tumor suppression in vivo. This designed Zn-based multifunctional nanoplatform will allow promoting further the development of IIT and the corresponding combined cancer therapy strategy.

DOI： 10.1021/acsnano.2c05532

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI  

Graphene oxide (GO) is one of the most studied nanomaterials in many fields, including the biomedical field. Most of the nanomaterials developed for drug delivery and phototherapies are based on noncovalent approaches that lead to an unspecific release of physisorbed molecules in complex biological environments. Therefore, preparing covalently functionalized GO using straightforward and versatile methods is highly valuable. Phototherapies, including photothermal therapy (PTT) and photodynamic therapy (PDT), have shown great potential as effective therapeutic approaches against cancer. To overcome the limits of a single method, the combination of PTT and PDT can lead to a combined effect with a higher therapeutic efficiency. In this work, we prepare a folic acid (FA) and chlorin e6 (Ce6) double-functionalized GO for combined targeted PTT/PDT. This conjugate can penetrate rapidly into cancer cells and macrophages. A combined effect of PTT and PDT is observed, leading to a higher killing efficiency toward different types of cells involved in cancer and other diseases. Our work provides a simple protocol to prepare multifunctional platforms for the treatment of various diseases.

DOI： 10.3390/pharmaceutics14071365

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

Semiconducting nanomaterials with 3D network structures exhibit various fascinating properties such as electrical conduction, high permeability, and large surface areas, which are beneficial for adsorption, separation, and sensing applications. However, research on these materials is substantially restricted by the limited trans-scalability of their structural design and tunability of electrical conductivity. To overcome this challenge, a pyrolyzed cellulose nanofiber paper (CNP) semiconductor with a 3D network structure is proposed. Its nano-micro-macro trans-scale structural design is achieved by a combination of iodine-mediated morphology-retaining pyrolysis with spatially controlled drying of a cellulose nanofiber dispersion and paper-crafting techniques, such as microembossing, origami, and kirigami. The electrical conduction of this semiconductor is widely and systematically tuned, via the temperature-controlled progressive pyrolysis of CNP, from insulating (10(12) Omega cm) to quasimetallic (10(-2) Omega cm), which considerably exceeds that attained in other previously reported nanomaterials with 3D networks. The pyrolyzed CNP semiconductor provides not only the tailorable functionality for applications ranging from water-vapor-selective sensors to enzymatic biofuel cell electrodes but also the designability of macroscopic device configurations for stretchable and wearable applications. This study provides a pathway to realize structurally and functionally designable semiconducting nanomaterials and all-nanocellulose semiconducting technology for diverse electronics.

DOI： 10.1021/acsnano.1c10728

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Graphene oxide (GO)-based hydrogel composed of magnesium oxide (MgO) and povidone-iodine (PVP-I) is synthesized. GO in the hydrogel plays two roles; gelator by self-assembling and carrier for MgO and PVP-L MgO particles act as cross-linking initiators and fillers that increase the cohesion and adhesion strengths of the hydrogels. Besides, MgO promotes antibacterial activities and regulates cellular activities over the lifetime of the hydrogel. In addition, PVP-I slowly releases free iodine from the hydrogel, exhibiting germicidal activity over time. A combination of GO, MgO, and PVP-I in the hydrogel exhibit improved electrical conductivity, fluid uptake ability, water retention capacity, water vapor transmission rate, and integrity value. Furthermore, the hydrogel has shown antimicrobial properties against Staphylococcus aureus. These findings are unique and indicate that GO-based hydrogel could be a promising material for biomedical application, especially for the treatment of pathological and surgical wounds.

DOI： 10.1246/bcsj.20220017

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The size of graphene oxide (GO) flakes may change the chemical composition on the surface, thereby altering its intrinsic properties. The current work explored the variations of surface moieties with four different sizes: 0.3, 0.7, 20, and 42 mu m(2), which were obtained with morphological integrity under controlled fabrication technique. On the basis of comprehensive analyses, slight variations in the composition of each chemical moiety were observed. At the same time, slight fluctuations were found for both edge-to-basal plane (E/B) and carbon-to-oxygen (C/O) ratios with increasing flake size.

DOI： 10.1021/acs.iecr.2c00748

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The addition of two-dimensional (2D) materials into polymers can improve their mechanical properties. In particular, graphene oxide (GO) and hexagonal boron nitride (h-BN) are expected to be potential nanoplatelet additives for polymers. Interactions between such nanoplatelets and polymers are effective in improving the above properties. However, no report has investigated the effect of using two types of nanoplatelets that have good interaction with polymers. In this study, we fabricated polyimide (PI) films that contain two types of nanoplatelets, amine-functionalized h-BN (BN<INF>NH<INF>2</INF></INF>) and GO. We have elucidated that the critical ratio and the content of BN<INF>NH<INF>2</INF></INF> and GO within PI govern the films' mechanical properties. When the BN<INF>NH<INF>2</INF></INF>/GO weight ratio was 52 : 1 and their content was 1 wt% in the PI film, the tensile modulus and tensile strength were increased by 155.2 MPa and 4.2 GPa compared with the pristine PI film.

DOI： 10.1039/d2na00078d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A redox-active molecule is grafted on graphene oxide (GO) via successive reactions. In the first step, GO is modified with diamine, which acts as a linker for the redox-active molecule. In the second step, the redox-active molecule is attached to the amino group of the linker by amide bond formation. Through these processes GO is partially reduced, enhancing its electrochemical properties. The structure of the functionalized GO is characterized by XPS, TGA, FTIR, and CV, and applied for electrodes in supercapacitors (SCs). The distance and direction of the redox-active molecule on the electrode affect the SC performance; ethylene diamine is the most promising linker to efficiently transfer electrons from the redox-active molecule to the electrode surface.

DOI： 10.1039/d1dt03197j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

Magnesium oxide (MgO) has high thermal conductivity while keeping insulation; thus, MgO is attractive material as a filler for thermosetting or thermoplastic resins. However, MgO readily hydrates with water or moisture. Thus, the surface of MgO is coated with organic or inorganic substances. We focused on graphene oxide (GO) as a surface coating agent. It has a 2-dimensional thin sheet structure, oxygen functional groups on the surface, and negative zeta-potential. Typically, GO has been used as a support material for metal nanoparticles. In this research, GO was coated on MgO micro-crystal surface to improve the surface character of MgO. The negatively charged GO and the positively charged MgO were combined with strong interaction. 0.5 wt% GO coated MgO showed excellent moisture resistance compared to organic substances coating. Coating of MgO with GO or reduced GO (rGO) is effective to overcome the weaknesses of MgO. Due to the hydrophilicity and high thermal conductivity of rGO, MgO/rGO composite can be a filler for high moisture resistance and thermal conductivity.

DOI： 10.1016/j.apsusc.2021.151483

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Multilayered films prepared from graphene oxide (GO) subjected to a single oxidation process (1GO) can actuate in response to moisture, whereas those prepared from GO subjected to two oxidation processes (2GO) lose this ability. To elucidate the origin of this difference, the structures and properties of various multilayered films and their contents were analyzed. According to atomic force microscopy images, the lateral size of the GO monolayer in 2GO (2.0 +/- 0.4 mu m) was smaller than that in 1GO (3.2 +/- 0.4 mu m), although this size difference did not affect actuation. Scanning electron microscopy images of the cross sections of both films showed fine multilayered structures and X-ray diffraction measurements showed the moisture sensitive reversible change in the interlayer distances for both films. Both films adsorbed 30 wt% moisture in 60 s with different water contents at the bottom moist sides and top air sides of the films. Nanoindentation experiments showed hardness values (1GO: 156 +/- 67 MPa; 2GO: 189 +/- 97 MPa) and elastic modulus values (1GO: 4.7 +/- 1.7 GPa; 2GO: 5.8 +/- 3.2 GPa) typical of GO, with no substantial difference between the films. On the contrary, the 1GO film bent when subjected to a weight equal to its own weight, whereas the 2GO film did not. Such differences in the macroscopic hardness of GO films can affect their moisture-induced actuation ability.

DOI： 10.1039/d1ra07773b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing Ltd  

Boron dipyrromethene derivates (BODIPYs) are promising photosensitisers (PSs) for cancer treatment using photodynamic therapy (PDT). This study investigates the functionalisation of graphene oxide (GO) with a BODIPY derivate for glutathione (GSH) depletion and PDT. The functionalisation of GO with a 3,5-dichloro-8-(4-boronophenyl) BODIPY via a diol derivatisation with the phenyl boronic acid moiety at the meso position of the BODIPY core, allowed to preserve the intrinsic properties of GO. We demonstrated that both chlorine atoms were substituted by GSH in the presence of glutathione transferase (GST), inducing a relevant bathochromic shift in the absorption/emission features and thus generating the active PS. Ex vitro assessment using cell lysates containing cytoplasmatic GST revealed the intracellular catalytic mechanism for the nucleophilic substitution of the GO-BODIPY adduct with GSH. Confocal microscopy studies showed important differences in the cellular uptake of free BODIPY and GO-BODIPY and revealed the coexistence of GO-BODIPY, GO-BODIPY-GS, and GO-BODIPY-GS(2) species inside vesicles and in the cytoplasm of the cells after 24 h of incubation. In vitro biocompatibility and safety of GO and GO-BODIPY were evaluated in 2D and 3D models of prostate adenocarcinoma cells (PC-3), where no toxicity was observed up to 100 mu g ml(-1) of GO/GO-BODIPY in all treated groups 24 h post-treatment (cell viability > 90%). Only a slight decrease to 80% at 100 mu g ml(-1) was observed after 48 h of incubation. We demonstrated the efficacy of a GO adduct containing an alpha-chlorine-substituted BODIPY for the simultaneous depletion of intracellular GSH and the photogeneration of reactive oxygen species using a halogen white light source (5.4 mW cm(-2)) with a maximum in the range of 500-800 nm, which significantly reduced cell viability (<50%) after irradiation. Our study provides a new vision on how to apply BODIPY derivates and potentiate the toxicity of PDT in prostate and other types of cancer.

DOI： 10.1088/2053-1583/ac4572

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Fullerene-based microporous polymers synthesized by polyesterification of fullerenol possess excellent stability against solvents and exposed C₆₀ surfaces confirmed by enhanced hydrogen spillover.

DOI： 10.1039/d2cc00728b

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Plant biomass could be a viable alternative renewable resource, but the moisture content must be reduced to use it as fuel. Mechanical compression alone is generally insufficient for dehydration, necessitating the addition of thermal drying. This study develops a unique mechanical rolling compression method with high dehydration ability. The squeezed liquid was analyzed using 1H nuclear magnetic resonance (1H NMR), UV–Vis, and FT-IR indicating much water-soluble lignin. Cedar board, woody biomass, compressed more effectively than cedar chips, implying that mechanical rolling compression along vessels such as straw was important. Alpinia zerumbet, herbaceous biomass, was compressed in the same way, and the squeezed liquid contained water-soluble lignin. Pellets made from plant residues were evaluated by combustion test. The squeezed liquid with water-soluble liquid revealed a basic antiviral effect for influenza and the porcine epidemic diarrhea virus. Our developed, novel, rolling plant compression method has the potential to alter fossil fuels.

DOI： 10.1007/s10163-022-01531-5

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Confined space provides a reaction platform with altered reaction rate and selectivity compared with a homogeneous solution. In this work, porous phenolic pillar[5]arene crystals were used as a reaction space to promote and perturb equilibrium between lactones and their corresponding polyesters. Immersion of porous pillar[5]arene crystals in liquid lactones induced ring-opening polymerization of δ-valerolactone and ϵ-caprolactone at room temperature because the phenolic hydroxy groups have catalytic activity via hydrogen bonds and the pillar[5]arene cavities prefer linear guests. After the reaction, pillar[5]arene and polyesters formed pseudo-polyrotaxanes.

DOI： 10.1002/anie.202212874

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DOI： 10.3303/CET2297054

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE RESEARCH  

Carbon materials with controlled pore sizes at the nanometer level have been obtained by template methods, chemical vapor desorption, and extraction of metals from carbides. However, to produce porous carbons with controlled pore sizes at the Ångstrom-level, syntheses that are simple, versatile, and reproducible are desired. Here, we report a synthetic method to prepare porous carbon materials with pore sizes that can be precisely controlled at the Ångstrom-level. Heating first induces thermal polymerization of selected three-dimensional aromatic molecules as the carbon sources, further heating results in extremely high carbonization yields (>86%). The porous carbon obtained from a tetrabiphenylmethane structure has a larger pore size (4.40 Å) than those from a spirobifluorene (4.07 Å) or a tetraphenylmethane precursor (4.05 Å). The porous carbon obtained from tetraphenylmethane is applied as an anode material for sodium-ion battery.

DOI： 10.1038/s42004-021-00515-0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Since the strong interlayer interaction of AB-stacked graphene in bulk form degrades the superior property of single-layer graphene, formation of randomly stacked graphene is required to apply the high performances of graphene to macroscopic devices. However, conventional methods to obtain bulk-scale graphene suffer from a low crystallinity and/or the formation of a thermodynamically stable AB-stacked structure. This study develops a novel approach to produce bulk-scale graphene with a high crystallinity and high fractions of random stacking by utilizing the porous morphology of a graphene oxide sponge and an ultrahigh temperature treatment of 1500-1800 degrees C with ethanol vapor. Raman spectroscopy indicates that the obtained bulk-scale graphene sponge possesses a high crystallinity and a high fraction of random stacking of 80%. The large difference in the random-stacking ratio between the sponge and the aggregate samples confirms the importance of accessibility of ethanol-derived species into the internal area. By investigating the effect of treatment temperature, a higher random-stacking ratio is obtained at 1500 degrees C. Moreover, the AB-stacking fraction was reduced to less than 10% by introducing cellulose nanofiber as a spacer to prevent direct stacking of graphene. The proposed method is effective for large-scale production of high-performance bulk-scale graphene. (C) 2021 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbon.2021.09.034

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Layer stacking of two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides, is critical for controlling their physical and transport properties. By exploiting a specific stacking order, the electronic band structures of such 2D materials can be tuned, from which unusual and exotic properties may emerge. Graphene oxide (GO) undergoes layer stacking along with its photo- and thermal-induced reduction process; however, the underlying mechanism and dynamics during its layer stacking have not been revealed. In this study, we demonstrate time-resolved electron diffraction for monitoring the structural dynamics during the layer stacking of GO induced by ultraviolet photoexcitation. The experimental results accompanied by the density functional theory calculations reveal that AB stacking of graphitic domains of GO layers coincides within ∼40 ps with photoinduced removal of the epoxy-oxygen from the basal plane of GO via the strong interactions between the GO layers.

DOI： 10.1016/j.carbon.2021.07.058

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER ADVANCED TECHNOLOGY  

Glucose level measurement is essential for the point-of-care diagnosis, primarily for persons with diabetes. A disposable electrochemical glucose sensor is constructed using flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) and redox mediator for electron transfer from the enzyme to the electrode surface. Ideally, a suitable mediator should have high water solubility, high kinetic constant, high stability, and redox potential between −0.2 and 0.1 V vs. Ag|AgCl|sat. KCl. We designed and synthesized two new quinone-based water-soluble mediators: quinoline-5,8-dione (QD) and isoquinoline-5,8-dione (IQD). The formal potentials for both QD and IQD at pH 7.0 were −0.07 V vs. Ag|AgCl|sat. KCl. The logarithms of the electron exchange rate constants (k2/(M−1 s−1)) between QD/IQD and FAD-GDH were 7.7 ± 0.1 and 7.4 ± 0.1 for QD and IQD, respectively, which are the highest value among the water-soluble mediators for FAD-GDH reported to date. Disposable amperometric glucose sensors were fabricated by dropping FAD-GDH and QD or IQD onto a test strip. The sensor achieved a linear response up to glucose concentrations of 55.5 mM. The linear response was obtained even when the mediator loading was low (0.5 nmol/strip); loading was only 0.2 mol% of glucose. The results proved that the response current was primarily controlled by glucose diffusion. In addition, the sensor using QD exhibited high stability over 3 months at room temperature.

DOI： 10.1016/j.bios.2021.113357

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Iminodiacetic acid (IDA) is a tridentate ligand, which can capture metal ions by forming two fused five-membered chelate rings. In this study, we fixed IDA moieties onto a two-dimensional nanocarbon, graphene oxide (GO), to obtain materials with high and selective adsorption of metal ions. The synthesis conditions for the GO-IDA composites were optimized, then their structures were characterized by infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and CHN elemental analysis. In addition, the heavy-metal removal efficiency and selectivity of the GO-IDA composites with different length alkyl linkers between the GO and IDA were investigated. An aqueous solution containing 10 metal ions (Al, As, B, Cd, Cr, Cu, Mn, Pb, Se, and Zn) was used as a model for contaminated water at pH 7, and the interactions of the ions with GO-IDA were in the order of Cu > Pb > As > B > Zn > Al approximate to Se. The interaction between Cu and GO-IDA was confirmed by XPS and extended X-ray absorption fine structure (EXAFS), which showed that Cu was coordinated to IDA.

DOI： 10.1039/d1na00435b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

The covalent double functionalization of graphene oxide (GO) is an effective approach to tune the properties of graphene-like materials. The first step is the ring-opening reaction of epoxides by amines, followed by the second step consisting on the nucleophilic addition reaction of GO hydroxyl groups to an α,β-unsaturated carbonyl compound. The benefit of doubly functionalized GO is to possess different functions, confirmed by measuring proton conductivity and supercapacitor performance. The proton conductivity can be improved by introducing sulfonic acid and redox-active functional groups on GO, while the capacitance for supercapacitor can be increased by introducing two distinct redox-active molecules. The current study evidences that a double functionalization allow to design a multifunctional GO platform as an electrolyte membrane for fuel cells and/or an electrode material for supercapacitors.

DOI： 10.1016/j.apmt.2021.101120

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Two-dimensional (2D) materials are generally expected to have superior lithium-ion (LIBs) performances compare with their bulk counterpart as they display superior specific surface area. In this context, the development of 2D maghemite would be of great interest owing to its high theoretical specific capacity, natural abundance, and relatively low cost and toxicity; however, maghemite do not have a layered crystalline structure. Herein, to overcome this hindrance, gamma-Fe2O3 has been enclosed within a 2D carbon matrix via a simple and facile synthesis strategy based on the complexation of ethylene glycol with aqueous iron species by hydrolysis and condensation reactions followed by its carbonization. As obtained 2D carbon gamma-Fe2O3 nanosheet composite (C-EG-Fe) is composed of 41.3 wt.% carbon and 10.2 wt.% Fe. When used as anode materials in LIBs, C-EG-Fe demonstrated the enhanced initial discharge capacity of 1589 mAh g(-1) at 100 mA g(-1), and outstanding ultralong cycling performance with the significant stable capacity of 700 mAh g(-1) and 230 mAh g(-1) at the higher current rate of 0.5 A g(-1) and 10 A g(-1) for more than 300 and 6000 cycles, respectively. These results enable a promising avenue to design the large-scale production of 2D C-EG-Fe sheets-based nanostructured anode materials for next-generation LIBs for largescale energy storage applications. (C) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jiec.2021.05.045

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A series of polycyclic aromatics, naphthalene, phenanthrene, perylene, pyrene, 1-pyrenebutyric acid N-hydroxysuccinimide ester (pyrene NHS) and coronene, were immobilized via pi stacking on carbon nanotube (CNT) electrodes and electro-oxidized in aqueous solutions. The obtained quinones were characterized and evaluated for the mediated electron transfer with FAD dependent glucose dehydrogenase during catalytic glucose oxidation.

DOI： 10.1039/d1cc02958d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

At a metal-ferroelectric junction, it has been considered that the electric polarization of the ferroelectric material can affect the electronic structure of the neighboring metal. Here, we demonstrate that the valence state of Pd can be shifted to the unstable high value of 4+ by the electric field of electric polarization in ferroelectric BaTiO3. Study of the absorption fine structure of both hard and soft x rays revealed the existence of Pd4+ states on the surface of Pd oxide nanoparticles. The positions of Pd and oxygen atoms are shifted in opposite directions by the electric field due to the electric polarization of ferroelectric BaTiO3. The atomic displacement of Pd and O forms a zigzag structure, in which the coordination number of Pd atoms is changed from four to six, producing a quadrivalent state. This report presents experimental evidence that ferroelectric polarization can control the electronic states of neighboring metal atoms, and we suggest that using the ferroelectric support effect may produce a new type of catalyst.

DOI： 10.1063/5.0066289

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

In this research, we aimed to establish a guideline for designing electron mediators suitable for biofuel cells. A redox potential simulator was fabricated by combining density functional theory calculation and experiment, allowing us to select molecules with appropriate redox potentials efficiently. Previously, mediators have been developed depending on the trials and errors; thus, our strategy will speed up the development of biofuel cells with outstanding performances.

DOI： 10.1088/2515-7655/abebc8

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Despite the great progress achieved, lithium-sulfur (Li-S) batteries still suffer unsatisfactory performance at high sulfur loading (>5 mg cm−2), which results from the impeded kinetics in charge transfer and polysulfides conversion with increasing electrode thickness. Herein, we have constructed a high-sulfur-loading monolithic cathode by in-situ reducing graphene oxide (GO) in the aqueous solution with dispersed sulfur-filled N,P dual-doped carbon nanocages (NPCNC). The Li-S battery with the areal sulfur loading of 6 mg cm−2 exhibits a high areal capacity of 6.7 mAh cm−2 and a retention of 4.2 mAh cm−2 after 250 cycles. The excellent performance is attributed to the synergism of the facilitated charge transfer and alleviated polysulfide diffusion by the reduced GO-framed 3D network, and the suppressed shuttle and polarization effects by the confinement and electrocatalysis of NPCNC. In addition, the monolithic sulfur electrode is free from binder, conductive agent and current collector, much beneficial to gravimetric performance. This study demonstrates an efficient strategy to increase the areal performance of Li-S batteries.

DOI： 10.1016/j.flatc.2021.100253

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Based on the specific tumor microenvironment, characterized by an overproduction of H2O2 and a high glutathione (GSH) concentration, the cascade reactions of nanomaterials, capable of mediating GSH depletion and reactive oxygen species (ROS) generation, have become a popular strategy to increase cancer therapy efficiency. In this study, we exploited reduced graphene oxide (rGO), one of the most promising graphene-based materials, in combination with manganese dioxide nanoparticles (MnO2 NPs) to design a multifunctional nanoplatform (rGO@MnO2) for efficient photothermal/chemodynamic combined therapies. MnO2 NPs were anchored onto the surface of rGO nanosheets (rGO NSs). MnO2 NPs oxidize intracellular GSH, and the generated Mn2+ ions converted H2O2 into HO[rad] by Fenton reaction. Meanwhile, rGO NSs mediated photothermal therapy (PTT) could further kill cancer cells. High temperature caused by photothermal conversion increased Fenton reaction rate, which enhanced the efficiency of MnO2 NPs mediated chemodynamic therapy (CDT). Importantly, thanks to the enhanced cell uptake of MnO2 NPs favored by the delivery properties of rGO, rGO@MnO2 possessed higher lethality to cancer cells. The decrease in the nanomaterials’ effective dose would further improve biosecurity and reduce cost. Therefore, rGO@MnO2 have great potential in cancer therapy by exploiting the synergistic effect of PTT and photothermal/delivery effect enhanced CDT.

DOI： 10.1016/j.carbon.2021.03.065

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Pollution of wastewater with heavy metal-ions represents one of the most severe environmental problems associated with societal development. To overcome this issue, the design of new, highly efficient systems capable of removing such toxic species, hence to purify water, is of paramount importance for public health and environmental protection. In this work, novel sorption hybrid materials were developed to enable high-performance adsorption of heavy metal ions. Towards this end, graphene oxide (GO) exhibiting various C/O ratios has been functionalized with ad hoc receptors, i.e. terpyridine ligands. The maximum adsorption capacity of highly oxidized/terpyridine hybrids towards Ni(ii), Zn(ii) and Co(ii) was achieved at pH = 6 and 25 °C reaching values of 462, 421 and 336 mg g-1, respectively, being the highest reported in the literature for pristine GO and GO-based sorbents. Moreover, the uptake experiments showed that heavy metal ion adsorption on GO-Tpy and GOh-Tpy is strongly dependent on pH in the range from 2 to 10, as a result of the modulation of interactions at the supramolecular level. Moreover, the ionic strength was found to be independent of heavy metal ion adsorption on GO-Tpy and GOh-Tpy. Under ambient conditions, adsorption capacity values increase with the degree of oxidation of GO because dipolar oxygen units can both interact with heavy-metal ions via dipole-dipole and/or ionic interactions and enable bonding of more covalently anchored terpyridine units. Both adsorption isotherms and kinetics studies revealed that the uptake of the heavy metal ions occurs at a monolayer coverage, mostly controlled by the strong surface complexation with the oxygen of GO and nitrogen-containing groups of terpyridine. Furthermore, selectivity of the hybrid was confirmed by selective sorption of the above heavy metal ions from mixtures involving alkali (Na(i), K(i)) and alkaline Earth (Mg(ii), Ca(ii)) metal ions due to the chelating properties of the terpyridine subunits, as demonstrated with municipal drinking (tap) water samples. Our findings provide unambiguous evidence for the potential of chemical tailoring of GO-based materials with N-heterocyclic ligands as sorbent materials for highly efficient wastewater purification.

DOI： 10.1039/d1nr02255e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER ADVANCED TECHNOLOGY  

Wearable devices that generate power using sweat have garnered much attention in the field of skin electronics. These devices require high performance with a small volume and low production rate of sweat by living organisms. Here we demonstrate a high-power biofuel cell bracelet based on the lactate in human sweat. The biofuel cell was developed by using a lactate oxidase/osmium-based mediator/carbon nanotube fiber for lactate oxidation and a bilirubin oxidase/carbon nanotube fiber for oxygen reduction; the fibers were woven into a hydrophilic supportive textile for sweat storage. The storage textile was sandwiched between a hydrophobic textile for sweat absorption from the skin and a hydrophilic textile for water evaporation to improve sweat collection. The performance of the layered cell was 74 μW at 0.39 V in 20 mM artificial sweat lactate, and its performance was maintained at over 80% for 12 h. Furthermore, we demonstrated a series-connection between anode/cathode fibers by tying them up to wrap the bracelet-type biofuel cell on the wrist. The booster six-cell bracelet generated power at 2.0 V that is sufficient for operating digital wrist watches.

DOI： 10.1016/j.bios.2021.113107

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Understanding the biodegradability of graphene materials by the action of oxidative enzymes secreted by immune cells is essential for developing applicable biomedical products based on these materials. Herein, we demonstrate the biodegradation of graphene oxide (GO) by recombinant eosinophil peroxidase (EPO) enzyme extracted from human eosinophils in the presence of a low concentration of hydrogen peroxide and NaBr. We compared the degradation capability of the enzyme on three different GO samples containing different degrees of oxygen functional groups on their graphenic lattices. EPO succeeded in degrading the three tested GO samples within 90 h treatment. Raman spectroscopy and transmission electron microscopy analyses provided clear-cut evidence for the biodegradation of GO by EPO catalysis. Our results provide more insight into a better understanding of the biodegradation of graphene materials, helping the design of future biomedical products based on these carbon nanomaterials.

DOI： 10.1039/c9fd00094a

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High-density and highly porous graphene-based pellets that exhibit an anomalous gas densification property have been fabricated by using zeolite-templated carbon (ZTC) as the major component and reduced graphene oxide (rGO) as a pure carbon binder. The unique structure of each ZTC particle consists of double-sided graphene fragments connected in a periodic, three-dimensional framework. The graphene-like sheets of rGO strongly connect the ZTC particles upon hot-pressingviathe generation of a large amount of unpaired electron spins, yielding monolithic pellets with exceptional mechanical toughness. The uniaxial pressing applied to the isotropic ordered framework of ZTC during pelletization leads to unique anisotropic structures. The so-obtained pellets represent a high density packing of graphene nanofragments with high volumetric surface area that exhibits high volumetric H2storage at room temperature.

DOI： 10.1039/d0ta11625d

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To enhanced photocatalytic activity and stability of titania (TiO ) coatings, graphene oxide (GO) forms on the surface of TiO coatings is fabricated by electrophoretic deposition (EPD). The results show the effect of EPD time on the formed hydroxyl groups from GO is significant, especially the controllable amount of GO by adjusting EPD time. The change in surface morphology of the GO on TiO coatings is obvious, showing an increased amount of GO. Owing to the effect of charge transfer between TiO and GO, the TiO /GO composites coatings exhibit excellent and stable photocatalytic activity. Notably, the cycle result of the sample after ultrasonic cleaning every 10 min reveal that the combination of TiO and GO is satisfactory. 2 2 2 2 2 2

DOI： 10.1016/j.matlet.2020.129258

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Language：English   Publisher：CHEMICAL SOC JAPAN  

Oxidation of graphite is widely recognized as a promising method for large-scale production of graphene-like materials. Chemical oxidation of graphite has been developed for more than 100 years, while electrochemical oxidation has attracted attention over the last 10 years as a simple, safe, and controllable production method for graphene. This review summarizes the electrochemical production of graphene analogs focusing on the electrochemical conditions and form of starting graphite that affect the properties of the products. Electrochemical treatment of graphite by direct current has been applied to various graphite, such as HOPG, graphite rod, graphite foil, and powdered graphite, and generates deeply oxidized graphene materials. On the other hand, treatments with alternative current generate low oxygen content products. Therefore, the electrochemical treatment of graphite provides an option for the controlled production of graphene-like materials.

DOI： 10.1246/cl.200780

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We report the band structure of Ba-deficient BaTiO3 as a p-type semiconductor, studied by a combination of light reflectance and photoelectron yield spectroscopy. Two acceptor levels were observed at the tail of a valence band. As the quantity of Ba vacancies increased, the density of state of the two acceptor levels also increased. The levels of the conduction band minimum and the valence band maximum shifted far away from the vacuum level, but the bandgap seems to be independent of Ba deficient concentration. For classical semiconductors such as Si and GaAs, the observation of impurity levels is restricted to low temperatures (∼20 K) owing to their narrow bandgaps. Oxide semiconductors have now been demonstrated with wide bandgaps and acceptor levels, at normal operating temperatures, which could lead to new device designs in the future.

DOI： 10.1063/5.0033761

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ConspectusMolecular assemblies have been widely applied to functional soft materials in a variety of fields. Liquid crystal is one of the representative molecular soft materials in which weak intermolecular interactions induce its dynamic molecular behavior under external stimuli, such as electric and magnetic fields, photoirradiation, and thermal treatment. It is important to understand molecular behavior and motion in the liquid-crystalline (LC) states at the picosecond level for further functionalization of liquid crystals and molecular assembled materials. For investigation of assembled structures of the materials on the nanometer scale, X-ray diffraction (XRD) measurements have been a powerful tool. Despite the dynamic nature of the assembled materials, however, time resolution of XRD is limited to millisecond due to the response speed of the detector, which hampered real-time observation of the dynamics of the molecular assembly. For further understanding of the dynamic behavior of functional molecules and improvement of performance for their applications, the insights of faster dynamics on the micro-, nano-, pico-, and even femtosecond time scales are required. In this context, the interdisciplinary approaches of the emerging fields of materials chemistry and ultrafast science will open up new aspects of molecular science and technology. These approaches may lead to more effective design of new functional materials, which enables us to control molecular behaviors and motions.The development of ultrashort pulsed X-ray and electron sources has resulted in the visualization of the key structural dynamics on the femto-to picosecond time scale not only in isolated molecules but also in assembled molecules, such as in the LC, crystal, and amorphous phases. We focus on ultrafast phenomena in molecular assemblies induced by photoexcitation. Ultrafast time-resolved electron diffraction measurements are sensitive to the molecular periodicity under photoexcitation, and thus the methodologies directly provide the ultrafast photoinduced molecular dynamic arrangements.In this Account, we describe ultrafast structural dynamics of molecules in the LC phases observed by time-resolved electron diffraction measurements. Photoinduced conformational changes of LC molecules is shown as the example, which is the first observation of LC molecule using time-resolved electron diffraction. It is important to understand the correlation between the conformational or configurational changes induced in a photoirradiated single molecule and the oriented collective motions of molecular assemblies induced by intermolecular interaction. We also show observation of collective motions of azobenzene LC molecules. The collective motions are initiated from photoreaction in a single molecule and are subsequently amplified by the steric interaction with its neighboring molecules.One remaining challenge is to create the platform of materials and sample preparations for time-resolved electron diffraction experiments, which can only be achieved by the interdisciplinary fusion of the fields of materials chemistry and ultrafast science. Time-resolved electron diffraction is a powerful tool for structural investigation of molecular materials with a dynamic nature, whose adaptability goes beyond that of more complex assemblies of carbon nanomaterials. This methodology will extend the possibility to investigate motions of a variety of molecular self-assemblies on a larger scale, for example, to understand responses of biomolecular assemblies and intermolecular chemical reactions.

DOI： 10.1021/acs.accounts.0c00576

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Although the green production of H through water splitting has prompted the search for solar energy harvesting materials, this still remains an ongoing challenge in the field. We report here a novel and cost-effective photocatalytic system, Co and Ni assisted CdS-NRs/g-C N nanohybrid, with the potential to significantly accelerate the solar-assisted water-splitting reaction. In this system, the co-catalysts (Co and Ni) are selectively incorporated as redox mediators to impart electrons and holes away from CdS-NRs/g-C N . As a result, an excellent H production rate of 11376 μmol g h , turnover number (TON) of 1945 (after 24 h), and external quantum yield (EQY) of 4.4% were obtained at 420 nm and under mild reaction conditions. In addition, when the reaction media was tested in the absence of co-catalysts, a notable decrease in activity was observed indicating the promising role of Ni and Co as cocatalysts. The process of redox shuttle proceeds without adding sacrificial reagents, and relies entirely on the employed cocatalysts to competently separate the oxidation and reduction steps. It is anticipated that this unique cocatalysts-supported nanohybrid can create a synergistic effect between the cocatalysts and the CdS-NRs/g-C N heterojunction, providing more active sites to the catalytic system for the subsequent water splitting redox reaction. The experimental results reveal that the selective and optimum use of dual cocatalysts can be a promising approach to trigger both the production of H and improve the stability of the photocatalytic system for overall water splitting. 2 3 4 3 4 2 3 4 2 −1 −1

DOI： 10.1016/j.matchemphys.2020.124140

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Graphene oxide (GO) is currently developed for biomedical applications as a promising nanoplatform for drug delivery, phototherapy, and biosensing. As a consequence, its safety and cytotoxicity issues have attracted extensive attention. It has been demonstrated that GO causes an increase of intracellular oxidative stress, likely leading to its cytotoxicity and inhibition of cell proliferation. Being one of the main reductive intracellular substances, glutathione (GSH) is vital in the regulation of the oxidative stress level to maintain normal cellular functions. In this study, we found that GSH could be oxidized to GSSG by GO, leading to the formation of reduced GO (rGO). GSH depletion affects the intracellular reductive/oxidative balance, provoking the increase of the reactive oxygen species level, sequentially inhibiting cell viability and proliferation. Therefore, the reaction between GO and GSH provides a new perspective to explain the origin of GO cytotoxicity.

DOI： 10.1021/acsami.0c17523

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The rapid repair of graphene oxide (GO) was demonstrated using a microwave cavity resonator that separates pure electric and magnetic fields from microwaves. Reduced graphene oxide (rGO), a high-quality graphene-like material, was obtained using our method. Raman spectroscopy of rGO after microwave treatment revealed that the D band intensity decreased as the temperature increased, while the G and G′ band intensities increased with increasing temperature. Furthermore, the cavity resonator provided better defect repair and oxygen removal from GO than conventional heating, and the microwave magnetic field yielded better quality rGO than the microwave electric field. Microwave heating removed surface impurities and repaired defects in GO more effectively than conventional heating, while suppressing graphitisation. These findings provide guidelines for the microwave-assisted reduction of GO for the fast and large-scale production of graphene.

DOI： 10.1016/j.carbon.2020.08.044

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In this study, porous boron nitride (p-BN) with hexagonal phase boron nitride (h-BN) pore walls was synthesized using high-temperature calcination. Negligible variation in pore-wall structure can be observed in powder X-ray diffraction (XRD) profiles and infrared (IR) spectra. However, a highly stable p-BN with a stable pore structure even at 973 K under the oxidative conditions is obtained when synthesized at higher than 1573 K under nitrogen gas flow. For p-BN, this stability is obtained by generating h-BN microcrystals. Nitrogen adsorption-desorption isotherms at 77 K provide type-IV features and typical adsorption-desorption hysteresis, which suggests micropore and mesopore formation. Moreover, adsorption-desorption isotherms of Ar at 87 K are measured and compared with those of nitrogen. The relative adsorbed amount of nitrogen (i.e., the amount of nitrogen normalized by that of Ar at each relative pressure or adsorption potential value) on p-BN is considerably larger than that on microporous carbon at low-pressure regions, which suggests the existence of strong adsorption sites on the p-BN surface. In fact, the relative number of adsorbed nitrogen molecules to that of Ar on p-BN is, at most, 150%-200% larger than that on microporous carbon for the same adsorption potential state. Furthermore, additional adsorption enhancement to nitrogen between P/P0 = 10-5 and 10-3 can be observed for p-BN treated at 1673 K, which suggests the uniformly adsorbed layer formation of nitrogen molecules in the vicinity of a basal planar surface. Thus, unlike typical nanoporous sp2 carbons, p-BN materials have the potential to enhance adsorption for certain gas species because of their unique surface state.

DOI： 10.1039/d0ra08437a

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For the application to portable devices and storage of renewable energies, high-performance lithium-ion batteries are in great demand. To this end, the development of high-performance electrode materials has been actively investigated. However, even if new materials exhibit high performance in a simple evaluation, namely half-cell tests, it is often impossible to obtain satisfactory performance with an actual battery (full cell). In this study, the structure of graphene analogs is modified in various ways to change crystallinity, disorder, oxygen content, electrical conductivity, and specific surface area. These graphene analogs are evaluated as negative electrodes for lithium-ion batteries, and we found reduced graphene oxide prepared by combination of chemical reduction and thermal treatment was the optimum. In addition, a full cell is fabricated by combining it with LiCoO modified with BaTiO , which is applicable to high-speed charge–discharge cathode material developed in our previous research. In general, pre-lithiation is performed for the anode when assembling full cells. In this study, we optimized a "direct pre-lithiation" method in which the electrode and lithium foil were in direct contact before assembling a full cell, and created a lithium-ion battery with an output of 293 Wh kg at 8,658 W kg . 2 3 −1 −1

DOI： 10.1016/j.electacta.2020.137257

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The electrochemical reduction of aryldiazonium salts is a versatile and direct route to obtain robust covalently modified electrodes. We report here a comparative study of Azure A modified carbon nanotube electrodes prepared by diazonium electrografting and by physical adsorption for bioelectrocatalytic glucose oxidation with fungal FAD-glucose dehydrogenase from Aspergillus sp. The electrografted and adsorbed electrodes exhibited different reversible electroactivity consistent with polymer-type and monomer-type phenothiazine surface assemblies, respectively. The electrografted Azure A electrodes exhibited superior mediated bioelectrocatalysis compared to the adsorbed Azure A electrodes. A more than 10-fold higher catalytic current up to 2 mA cm at 0.2 V vs. Ag/AgCl together with a similarly low onset potential of −0.05 V vs. Ag/AgCl was observed at the electrografted electrodes. Faster estimated electron transfer kinetics and a +200 mV potential shift for the polymer-type redox couple vs. the adsorbed monomer-type couple underlines the favourable driving force for mediated electron transfer with the buried FAD active site for the diazonium-derived bioelectrode. −2

DOI： 10.1002/celc.202000953

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

This study examines the synthesis and electrochemical performance of three-dimensional graphene for Li-ion batteries and Na-ion batteries. The in situ formation of iron hydroxide nanoparticles (Fe(OH)x NPs) of various weights on the surface of graphene oxide, followed by thermal treatment at elevated temperature and washing using hydrochloric acid, furnished 3D graphene. The characterization studies confirmed the prevention of graphene layer stacking by over 90% compared with thermal treatment without Fe(OH)x. The electrochemical performance of the 3D graphene was evaluated as a counter electrode for lithium metal and sodium metal in a half-cell configuration. This material showed good performances with a charging capacity of 507 mA h g-1 at 372 mA g-1 in Li-ion batteries and 252 mA h g-1 at 100 mA g-1 in Na-ion batteries, which is 1.4 and 1.9 times higher, respectively, than the graphene prepared without Fe(OH)x templates.

DOI： 10.1039/d0nr05682k

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The chemical state of Pd supported on reduced graphene oxide (rGO) changed dynamically and sensitively between Pd0 and Pd2+ by switching atmosphere between H2 and O2. In contrast, Pd supported on graphene oxide (GO) did not show such dynamic redox properties. The catalytic activity in dehydrogenation and hydrogenation reactions also depended on the oxygen content of GO.

DOI： 10.1246/CL.200529

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER ADVANCED TECHNOLOGY  

To realize direct power generation from biofuels in natural organisms, we demonstrate a needle-type biofuel cell (BFC) using enzyme/mediator/carbon nanotube (CNT) composite fibers with the structure Osmium-based polymer/CNT/glucose oxidase/Os-based polymer/CNT. The composite fibers performed a high current density (10 mA/cm ) in 5 mM artificial blood glucose. Owing to their hydrophilicity, they also provided sufficient ionic conductivity between the needle-type anode and the gas-diffusion cathode. When the tip of the anodic needle was inserted into natural specimens of grape, kiwifruit, and apple, the assembled BFC generated powers of 55, 44, and 33 μW from glucose, respectively. In addition, the power generated from the blood glucose in mouse heart was 16.3 μW at 0.29 V. The lifetime of the BFC was improved by coating an anti-fouling polymer 2-methacryloyloxyethyl phosphorylcholine (MPC) on the anodic electrode, and sealing the cathodic hydrogel chamber with medical tape to minimize the water evaporation without compromising the oxygen permeability. 2

DOI： 10.1016/j.bios.2020.112287

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We aimed to develop the bottom-up synthesis of nanocarbons with specific functions from molecules without any leaving group, halogen atom and boronic acid, by employing a metal catalyst under solution plasma irradiation. Pyridine was used as a source of carbon. In the presence of a Pd catalyst, the plasma treatment enabled the synthesis of N-doped carbons with a pyridinic configuration, which worked as an active catalytic site for the oxygen reduction reaction.

DOI： 10.1039/d0na00327a

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Graphene oxide (GO) is one of the most popular materials applied in different research areas thanks to its unique properties. The application of GO requires well-designed protocols to introduce different functionalities on its surface, exploiting the oxygenated groups already present. Due to the complex and unstable chemical environment on the GO surface, it is recommended to perform the functionalization under mild conditions. The carboxylation of GO is a widely used method to introduce additional carboxylic acids, which could be further modified through amidation or esterification reactions. The strategy already reported in the literature requires harsh conditions (excess amount of sodium hydroxide). GO is readily reduced under basic conditions, but the reduction of GO during the carboxylation is barely studied. In this work, we performed the carboxylation using chloroacetic acid with different amounts of sodium hydroxide and characterized the functionalized GO with various techniques. The carboxylated GO was exploited to develop a double functionalization approach combining an epoxide ring opening reaction and an amidation. The results showed that strong basic conditions were necessary to derivatize GO. Nevertheless, these conditions resulted in a partial reduction of GO and some functionalities on GO were removed during the reaction, thus reducing the total efficiency of the functionalization in comparison to an epoxide ring opening reaction, indicating that carboxylation is not an efficient approach for the functionalization of GO. This journal is

DOI： 10.1039/d0na00561d

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A three-step reaction furnished a composite of graphene and a conductive polymer. In the first step, graphene oxide was modified with a diamine, which acted as a linker for polymer attachment. In the second step, an initiating site was attached to the free amine of the linker. Finally, a polymer was grown from the initiation site, and graphene oxide was reduced during polymer growth. The method does not require any catalyst, acid, or reducing agent, furnishing the graphene-polymer composite in a straightforward procedure. Various instrumental techniques, including step-by-step AFM analysis, were used to characterize the structure of the products in each step and confirm the covalent functionalization among graphene oxide, cross-linker, and polymer. The average surface height was sequentially increased after each step, indicating the success of the sequential reactions. The graphene-polymer composite showed excellent electrochemical performance and stability compared with a composite prepared by physical mixing of graphene and polymer.

DOI： 10.1039/d0ta05489e

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Graphene oxide (GO) is a water soluble carbon material in general, suitable for applications in electronics, the environment, and biomedicine. GO is produced by oxidation of abundantly available graphite, turning black graphite into water-dispersible single layers of functionalized graphene-related materials. Therefore, oxidation gives chemicals access to the complete surface area of GO. These fundamentals have led to a rich chemistry of GO. Here, we review the progress made in controlling the synthesis of GO, introduce the current structural models used to explain the phenomena and present versatile strategies to functionalize the surface of GO. Finally, an outlook is given for future directions.

DOI： 10.1039/d0nr02164d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Carbon-rich materials, which contain over 90% carbon, have been mainly synthesized by the carbonization of organic compounds. However, in many cases, their original molecular and ordered structures are decomposed by the carbonization process, which results in a failure to retain their original three-dimensional (3D) ordering at the angstrom level. Recently, we successfully produced carbon-rich materials that are able to retain their 3D ordering at the angstrom level even after the calcination of organic porous pillar[6]arene supramolecular assemblies and cyclic porphyrin dimer assemblies. Other new pathways to prepare carbon-rich materials with 3D ordering at the angstrom level are the controlled polymerization of designed monomers and redox reaction of graph. Electrocatalytic application using these materials is described.

DOI： 10.1039/d0sc02422h

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Organic transformations are usually catalyzed by metal-based catalysts. In contrast, metal-free catalysts have attracted considerable attention from the viewpoint of sustainability and safety. Among the studies in metal-free catalysis, graphene-based materials have been introduced in the reactions that are usually catalyzed by transition metal catalysts. This review covers the literature (up to the beginning of April 2020) on the use of graphene and its derivatives as carbocatalysts for C-C bond-forming reactions, which are one of the fundamental reactions in organic syntheses. Besides, mechanistic studies are included for the rational understanding of the catalysis. Graphene has significant potential in the field of metal-free catalysis because of the fine-tunable potential of the structure, high stability and durability, and no metal contamination, making it a next-generation candidate material in catalysis.

DOI： 10.1039/d0nr02984j

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Nanocarbons, especially two-dimensional carbons, have received considerable attention due to their unique structure and physical and chemical properties, which make them promising candidate materials for biomedical applications. In this study, we focus on graphene oxide (GO), which has many oxygenated functional groups and high affinity with water and biomaterials, and the synthesis of GO complexes with antibacterial agents, like cetylpyridinium chloride (CPC) and its derivatives. We found that the sustained release of CPCs from GO can be controlled by changing the terminal functional group of CPC. The prepared GO-CPC complexes were subjected to antibacterial tests against S. mutans. CPC with the carboxy group was degraded by the oxidizing property of GO, resulting in the loss of antibacterial properties. On the other hand, the other CPC derivatives were released from GO and showed antibacterial activities. Finally, we propose a new mechanism describing how GO and CPC form a functional complex, and how CPC is released from this complex. These findings will lead to pioneering the carbon-based functional antibacterial agents designed at the molecular level.

DOI： 10.1016/j.carbon.2019.11.094

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Efficient and selective methods for graphene functionalization are needed because they allow tuning of the graphene surface and electronic properties. To date, graphene has been functionalized using ionic bonds, π-πinteractions, and covalent bonds. Graphene derivatives based on these methods have been used in various applications, but a new functionalization strategy that improves the properties of graphene is still needed. Herein, a new concept for graphene functionalization using halogenated graphene has been developed, in which brominated graphene is successfully functionalized by heteroatom-containing molecules to form onium bonds, such as pyridinium or ammonium. The counterion bromide is replaced with other anions, such as sulfate, by treating with sulfuric acid while retaining the molecules, which demonstrates the durable properties of onium bonding. To emphasize the advantages of this strategy for graphene functionalization, the performance for energy-related applications, such as biofuel cells, supercapacitors, and Li-ion batteries, is evaluated after introducing redox-active moieties onto graphene through onium bonding. This new graphene functionalization concept will provide a new approach to the design of tailor-made materials with targeted functions.

DOI： 10.1021/acsami.9b21082

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Exfoliation of graphite through functionalization is a promising technique to produce two-dimensional (2D) nanocarbons on a large scale. Due to the high stability of graphite, a conventional functionalization of graphite has been performed in harsh conditions, such as in concentrated sulfuric acid. Therefore, environmental and safety have been problems for scaling up the operation. In contrast, the electrochemical functionalization of a graphite electrode has recently attracted considerable attention because it does not require oxidants or sulfuric acid. However, 2D carbons produced through the existing electrochemical method are generally lacking in quality, due to the non-uniform destruction of the intermediately functionalized graphite. This paper reports a method for the non-destructive functionalization of graphite using HBF diluted by water or methanol as an electrolyte. It is confirmed that the choice of solvents and electrochemical conditions enabled fine control over the functionalization degree and the type of functional groups on 2D carbons. Compared to chemically generated 2D carbons, the electrochemically generated 2D carbon exhibits similar or better physical and chemical properties when used in lithium-ion battery electrodes and water purification membranes. This electrochemical method is also applicable to a continuous flow system, thus promising the mass production of 2D carbons for future industrialization. 4

DOI： 10.1016/j.carbon.2019.10.085

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI  

Among the several methods of producing graphene, the liquid-phase exfoliation of graphite is attractive because of a simple and easy procedure, being expected for mass production. The dispersibility of graphene can be improved by adding a dispersant molecule that interacts with graphene, but the appropriate molecular design has not been proposed. In this study, we focused on aromatic compounds with alkyl chains as dispersing agents. We synthesized a series of alkyl aromatic compounds and evaluated their performance as a dispersant for graphene. The results suggest that the alkyl chain length and solubility in the solvent play a vital role in graphene dispersion.

DOI： 10.3390/pr8020238

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This in vitro study assessed the efficacy of functionalized graphene oxide (f-GO) nanocomposites on the decalcification of dentin, because dental caries of the root surface is becoming one of the new problems in aged society. Hydroxyapatite plates (HAP) and dentin slices were coated with f-GO nanocomposites by comparing them to silver diamine fluoride as a positive control, then treated with decalcification solutions such as ethylenediaminetetraacetic acid and citrate at 37°C for 24 h. Scanning electron microscopy (SEM) revealed significant protection of the surface morphology of HAP and dentin. On the other hand, a cariogenic Streptococcus mutans growth was inhibited by f-GO nanocomposites. In addition, cytotoxicity of them to epithelial cells was much less than that of povidone-iodine, which is commonly used for oral disinfectant. We synthesized 5 different f-GO nanocomposites such as GO–silver (Ag), GO-Ag–calcium fluoride (CaF ), GO-CaF , GO-zinc, and GO–tricalcium phosphate (Ca (PO ) ). They were standardized by evaluating under SEM, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry analysis (TGA), and Raman spectra after being synthesized in an aseptic technique. The abilities of GO-Ag, GO-Ag-CaF , and GO-CaF nanocomposites were most preventive for decalcification. In addition, GO-Ag and GO-Ag-CaF almost completely inhibited S. mutans growth. However, they did not exhibit cytotoxicity to epithelial cells except at the highest concentration (0.1 w/v%) of GO-Ag and GO-Ag-CaF . Furthermore, these f-GO nanocomposites exhibited less or no discoloration of dentin, although commonly used silver diamine fluoride causes discoloration of dentin to black. Thus, these f-GO nanocomposites are useful to protect dental caries on the tooth root that becomes a social problem in aged society. 2 2 3 4 2 2 2 2 2

DOI： 10.1177/0022034519894583

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

A method for the double functionalization of graphene oxide (GO) under mild alkaline conditions has been developed. Two functional groups were covalently linked to GO in two steps: the first group was attached by an epoxide ring-opening reaction and the second, bearing an amine function, was covalently conjugated to benzoquinone attached to the GO. The doubly functionalized GO was characterized by several techniques, confirming the sequential covalent modification of the GO surface with two different functional groups. This method is straightforward and the reaction conditions are mild, allowing preservation of the structure and properties of GO. This strategy could be exploited to prepare multifunctional GO conjugates with potential applications in many fields ranging from materials science to biomedicine.

DOI： 10.1002/anie.201913461

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The high sensitivity of graphene to the surface condition of the gate dielectric layer and its poor van der Waals adhesion with a flexible substrate result in interfacial sliding and fracturing of graphene at low strains, making the successful utilization of pristine graphene (PG) in flexible electronics challenging. Here, we report a facile method for the fabrication of flexible graphene field effect transistors (F-GFETs) using sandwiched fluorinated graphene (FG). The “FG-PG-FG” sandwich structure shows a high optical transparency (>94%) with an average carrier mobility above 340 cm /V·s, higher than that obtained when GO and Ion gel were used as gate dielectric materials on F-GFETs and a relatively low gate leakage current of ~160 pA. Furthermore, we observed a high mechanical stability, retaining >88% of the original current output against bending deformation of up to 6 mm and >77% after 200 bending cycles by applying a tensile strain of 1.56%, compared to the control sample. This improved performance is attributed to the fact that the sandwiched FG provides a good dielectric environment by tuning the C/F ratio, which tightly fixes the PG under strain. These findings provide a new route for the future development of graphene-based flexible electronics. 2

DOI： 10.1016/j.apsusc.2019.143839

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Abstract: We report here the formation of carbon–carbon bonds via carbon-hydrogen bond activation catalysed by multi-walled carbon nanotubes (mwcnts), the catalytic activity of which is influenced by nanocarbon morphology and structure. Control of nanocarbon defects and edges allows the realisation of a high-performance carbon-based catalyst that can replace its metal-based counterparts. Graphic Abstract: [Figure not available: see fulltext.].

DOI： 10.1007/s10562-019-02951-z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Polymer–graphene composites have attracted significant attention; however, their formation mechanisms are a focus of debate. This work tries to clarify how grafting occurs on graphene by electron spin resonance techniques. As a result, two pathways are found. One passes through the radicals formed by cleaving C-O bonds on graphene are transferred to monomers, then grafting and polymerization proceed. Another mechanism passes through the oxy-radicals, which react with monomers in solution and finally react with carbon radicals on graphene. Based on the mechanism, various types of polymer–graphene composites are prepared, and applied to electrical conductive sheets, basic catalysts, and acidic catalysts.

DOI： 10.1002/marc.202000577

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CELL PRESS  

Despite recent studies elucidating the molecular mechanisms underlying cortical patterning and map formation, very little is known about how the embryonic pallium expands ventrally to form the future cortex and the nature of the underlying force-generating events. We find that neurons born at embryonic day 10 (E10) in the mouse dorsal pallium ventrally stream until E13, thereby superficially spreading the preplate, and then constitute the subplate from E14. From E11 to E12, the preplate neurons migrate, exerting pulling and pushing forces at the process and the soma, respectively. At E13, they are morphologically heterogeneous, with similar to 40% possessing corticofugal axons, which are found to be in tension. Ablation of these E10-born neurons attenuates both deflection of radial glial fibers (by E13) and extension of the cortical plate (by E14), which should occur ventrally, and subsequently shrinks the postnatal neocortical map dorsally. Thus, the preplate stream physically primes neocortical expansion and arealization.

DOI： 10.1016/j.celrep.2019.09.075

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The selective hydrogenation of the nitro moiety is a difficult task in the presence of other reducible functional groups such as alkenes or alkynes. We show that the carbon-based (metal-free) catalyst can be used to selectively reduce substituted nitro groups using H2 as a reducing agent, providing a great potential to replace noble-metal catalysts and contributing to simple and greener strategies for organic synthesis.

DOI： 10.1021/acs.orglett.9b02432

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To increase the chances of finding new candidate molecules with medicinal properties, while expending less resource and effort, the present study used pooled substrates as starting materials. A bisindole compound that showed inhibitory activity was then isolated from the mixture, and the activity was improved by optimizing the substituents on the indole skeleton.

DOI： 10.1016/j.bmcl.2019.06.061

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

A particularly efficient redox mediator for electron transfer between FAD-dependent glucose dehydrogenase (FAD-GDH) and carbon nanotube (CNT) based electrodes can be obtained via electrosynthetic oxidation of pyrene in aqueous buffer solution. H-1-NMR spectroscopic studies reveal the formation of a 2 : 1 mixture of 1,6-pyrenedione and 1,8-pyrenedione at the electrode. The formed pyrenedione exhibits a well-defined surface-bound redox system at -0.1 V vs. SCE and provides excellent electron transfer kinetics with this enzyme. Furthermore, the pi-system of pyrenedione allows improved stacking behavior with the CNT walls, leading to enhanced stabilities compared to commonly used mediators like naphthoquinone. The electrosynthesis of pyrenedione for catalytic glucose oxidation is optimal at pH 2 using cyclic voltammetry or chronoamerometry. It is envisioned that the electrosynthetic methodology can be expanded to form different redox mediators for a series of enzymes.

DOI： 10.1002/celc.201901666

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A two-dimensional nanocarbon, graphene, has attracted substantial interest due to its excellent properties. The reduction of graphene oxide (GO) has been investigated for the mass production of graphene used in practical applications. Different reduction processes produce different properties in graphene, affecting the performance of the final materials or devices. Therefore, an understanding of the mechanisms of GO reduction is important for controlling the properties of functional two-dimensional systems. Here, we determined the average structure of reduced GO prepared via heating and photoexcitation and clearly distinguished their reduction mechanisms using ultrafast time-resolved electron diffraction, time-resolved infrared vibrational spectroscopy, and time-dependent density functional theory calculations. The oxygen atoms of epoxy groups are selectively removed from the basal plane of GO by photoexcitation (photon mode), in stark contrast to the behavior observed for the thermal reduction of hydroxyl and epoxy groups (thermal mode). The difference originates from the selective excitation of epoxy bonds via an electronic transition due to their antibonding character. This work will enable the preparation of the optimum GO for the intended applications and expands the application scope of two-dimensional systems.

DOI： 10.1021/acsnano.9b03060

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The design of multifunctional materials able to both selectively deliver a drug into cells in a targeted manner and display an enhanced propensity for biodegradation is an important goal. Here, graphene oxide (GO) is functionalized with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) known to interact with the formyl peptide receptor, which is expressed in different cancer cells, including cervical carcinoma cells. This study highlights the ability of GOfMLP for targeted drug delivery and cancer cell killing and the subsequent degradation capacity of the hybrid. Biodegradation is assessed via Raman spectroscopy and transmission electron microscopy. The results show that GOfMLP is susceptible to faster myeloperoxidase-mediated degradation. The hybrid material, but not GO, is capable of inducing neutrophil degranulation with subsequent degradation, being the first study showing inducible neutrophil degradation by the nanomaterial itself with no prior activation of the cells. In addition, confocal imaging and flow cytometry using HeLa cells demonstrate that GOfMLP is able to deliver the chemotherapeutic agent doxorubicin faster into cells, inducing higher levels of apoptosis, when compared to nonfunctionalized GO. The results reveal that GOfMLP is a promising carrier able to efficiently deliver anticancer drugs, being endowed with the ability to induce its own biodegradation.

DOI： 10.1002/adfm.201901761

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI  

Biomass has gained great attention as an alternative to fuel-derived chemicals. This report concerns new catalytic systems consisting of [IrCp*Cl-2](2) (Cp*: Pentamethylcyclopentadienyl) for the reduction of aldehyde and biogenetic alcohols as hydrogen sources. [IrCp*Cl-2](2) has been used as a transfer hydrogenation catalyst using fossil fuel-derived alcohols as hydrogen sources in the presence of a base. In contrast, our system does not require any base, and the reaction can proceed in water. Various types of biogenetic alcohols can be used as hydrogen sources, such as monosaccharides, oligosaccharides, and glycerol. Aromatic and aliphatic aldehydes, as well as ketones, were successfully reduced to the corresponding alcohols in the present system.

DOI： 10.3390/inorganics7090114

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Given the specificity of the structure and function of graphene oxide (GO), hybridization with a variety of compounds will further extend its applications. To that end, we examined a new method for introducing a polymer brush onto the GO surface. In this method, GO was surface-modified with 2-((3-((2-bromo-2-methylpropanoyl)oxy)propyl)thio)ethylamine hydrochloride, which is a newly synthesized compound that contains an initiating group for atom transfer radical polymerization (ATRP) and an amino group for reacting with the epoxy groups on the GO surface. The ATRP-initiator-functionalized GO was then used as a substrate for the surface-initiated ATRP of methyl methacrylate (MMA), which produced graft polymers of poly(MMA) (PMMA) with targeted molecular weights and narrow molecular weight distributions; the average graft density was similar to 0.06 chains/nm(2). Because of their high dispersibilities and structural anisotropies, the PMMA-brush-decorated GOs formed lyotropic liquid crystals in their suspensions. In addition, similar suspensions with relatively high hybrid concentrations exhibited structural color that depended on the concentration.

DOI： 10.1021/acs.langmuir.9b01747

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© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is the most commonly investigated conductive polymer due to its unique thermoelectric properties. Several post treatments using various acids have been reported to improve the thermoelectric properties of PEDOT:PSS. In most articles, however, only the role of acids on the structure and thermoelectric properties of PEDOT:PSS were reported. In this article, we report the major role of the pressure of nitrogen gas (N2) on the structure and thermoelectric properties of PEDOT:PSS after treatment with various acids at optimized temperatures. After treatment with acids followed by N2 gas-passing, electrical conductivity enhances significantly. Therefore, N2 gas-passing after acid treatments results in higher thermoelectric properties than other traditional acid treatment methods. The enhancement in electrical conductivity is attributed to the removal of insulating PSS and the conformational change of the PEDOT chain. Furthermore, the pressure of N2 is responsible for the additional conformation of PEDOT chain, favoring the linear orientation of the PEDOT structure and resulting in an improvement of the electrical conductivity.

DOI： 10.1007/s10854-019-01721-2

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© 2019 The Authors The electrochemical exfoliation of graphite has attracted considerable attention as a method for large-scale, rapid production of graphene and graphene oxide (GO). As exfoliation typically requires direct electrical contact, and is limited by the shape and/or size of the starting graphite, treatment of small graphite particles and powders, the typical form available commercially, is extremely difficult. In this study, GO nanosheets were successfully prepared from small graphite particles and powders by a bipolar electrochemical process. Graphite samples were placed between two platinum feeder electrodes, and a constant current was applied between the feeder electrodes using dilute sulfuric acid as the electrolyte. Optical microscopy, atomic force microscopy, X-ray diffractometry, Raman spectroscopy, and X-ray photoelectron spectroscopy were employed to examine the samples obtained after electrolysis. The results obtained from these analyses confirmed that anodic electrochemical exfoliation occurs in the graphite samples, and the exfoliated samples are basically highly crystalline GO nanosheets with a low degree of oxidation (C/O = 3.6–5.3). This simple electrochemical method is extremely useful for preparing large amounts of graphene and GO from small particles of graphite.

DOI： 10.1016/j.elecom.2019.06.001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Nano-confined spaces in nanoporous materials enable anomalous physicochemical phenomena. While most nanoporous materials including metal-organic frameworks are mechanically hard, graphene-based nanoporous materials possess significant elasticity and behave as nanosponges that enable the force-driven liquid-gas phase transition of guest molecules. In this work, we demonstrate force-driven liquid-gas phase transition mediated by nanosponges, which may be suitable in high-efficiency heat management. Compression and free-expansion of the nanosponge afford cooling upon evaporation and heating upon condensation, respectively, which are opposite to the force-driven solid-solid phase transition in shape-memory metals. The present mechanism can be applied to green refrigerants such as H2O and alcohols, and the available latent heat is at least as high as 192 kJ kg(-1). Cooling systems using such nanosponges can potentially achieve high coefficients of performance by decreasing the Young's modulus of the nanosponge.

DOI： 10.1038/s41467-019-10511-7

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The last decade has seen an increase in the application of graphene oxide (GO) in the biomedical field. GO has been successfully exploited for its ability to deliver many kinds of drugs into target cells. However, GO toxicity assessment is still controversial. Several studies have demonstrated that GO protein coating is crucial to alleviate the material's toxicity. Besides, coronation leads to the formation of big agglomerates, reducing the cellular uptake of the material and thus its therapeutic efficiency. In this work, we propose a simple and efficient method based on rapid (ultra-turrax, UT) mixing to control protein corona formation. Using the UT protocol, we were able to reduce GO agglomeration in the presence of proteins and obtain stable GO dispersions in cell culture media. By labelling GO with luminescent nanoparticles (quantum dots), we studied the GO internalization kinetic and efficiency. Comparing the "classic" and UT protocols, we found that the latter allows faster and more efficient internalization both in macrophages and HeLa cells without affecting cell viability. We believe that the use of UT protocol will be interesting and suitable for the preparation of next-generation GO-based drug-delivery platforms.

DOI： 10.1021/acsami.8b18304

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Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.74.1.0_1645

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DOI： 10.1002/9783527823987.vol4_c2

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The tribological properties of oxidized wood-derived nanocarbons (oWNCs), which have the same surface chemical composition as graphene oxide (GO), were investigated as additives in water-based lubricants using a sintered tungsten carbide ball and a stainless steel flat plate with a reciprocating sliding configuration. WNCs were synthesized from four kinds of Japanese wood powder by metal-catalyzed carbonization, and were strongly oxidized by a modified Hummer's method. The four oWNCs have aggregated chain-like nanostructures and maintain graphitic layers. In addition, the four oWNCs were well-dispersed in water due to their high level of oxidation. The four oWNC aqueous dispersions improved lubrication. In particular, the aqueous dispersion of the oWNC derived from Japanese cedar (J. Cedar) wood powder showed a very low friction coefficient and formed a thick tribofilm on the plate surface. The most distinctive properties of the J. Cedar oWNC, compared to the other oWNCs, were the small primary and secondary particle sizes, which were much smaller than those of the other oWNCs. The small-sized J. Cedar oWNC may possibly enter the frictional interface, preventing direct contact between the ball and plate surfaces and forming a tribofilm.

DOI： 10.1016/j.diamond.2018.09.026

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Plant pathogenic bacteria cause huge yield losses in crops globally. Therefore, finding effective bactericides to these pathogens is an immediate challenge. In this study, we sought compounds that specifically inhibit the growth of Ralstonia solanacearum. As a result, we identified one promising compound, 1-(4-bromophenyl)-6-methoxy-2,3,4,9-tetrahydro-1H-β-carboline, which inhibited the growth of R. solanacearum (Rs1002) from a pilot library of 376 chemicals provided from RIKEN. We further obtained its structural analogues and assessed their ability to inhibit Rs1002 growth. Then we identified five compounds, named ralhibitins A to E, that specifically inhibit growth of Rs1002 at &gt
5 μg/ml final concentration. The most effective compounds, ralhibitins A, C, and E completely inhibited the growth of Rs1002 at 1.25 μg/ml. In addition, ralhibitins A to E inhibited growth of Xanthomonas oryzae pv. oryzae but not the other bacteria tested at a final concentration of 10 μg/ml. Whereas, ralhibitin E, besides inhibiting R. solanacearum and X. oryzae pv. oryzae, completely inhibited the growth of X. campestris pv. campestris and the Gram-positive bacterium Clavibacter michiganensis subsp. michiganensis at 10 μg/ml. Growth inhibition by these compounds was stable at pH 6–9 and after autoclaving. Because Rs1002 grew in the culture medium in which ralhibitins were incubated with the ralhibitin-insensitive bacteria, the unaffected bacteria may be able to inactivate the inhibitory effect of ralhibitins. These results suggest that ralhibitins might be potential lead compounds for the specific control of phytopathogenic bacteria.

DOI： 10.1016/j.micres.2018.06.005

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2018.2.0_747

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Transition metal catalyzed carbon-carbon bond formation reactions have become important transformations in organic synthesis. In this study, we have explored a general strategy of transition metal free carbocatalytic carbon-hydrogen (C-H) functionalization. A carbon-based catalyst bearing nitrogen functional groups can facilitate the C-H functionalization of unactivated arenes to obtain biaryl products. We propose the active sites on the catalyst by analyzing its chemical composition before and after reaction, in-situ FT-IR, in-situ electron spin resonance (ESR), and density function theory calculation. As a result, stable NH groups and radicals were found to be effective for the reaction, providing high recyclability of the catalyst. The present methodology offers a diverse substrate scope without any dry or inert conditions, thus opening the door for an alternative to the conventional metal-based coupling reactions. (C) 2018 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcat.2018.07.013

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Introduction: The tunneled cuffed catheter is used in hemodialysis patients for whom an arteriovenous fistula or arteriovenous graft is not suitable or for bridging usage of them. Accurate placement of a tunneled cuffed catheter is necessary for safe hemodialysis, but placement is sometimes difficult because of individual body differences. We developed a new device to support accurate placement of the tunneled cuffed catheter. In this study, we report our first clinical experience of the device.Methods: We made the device by expanded polytetrafluoroethylene with some special processes. The processes enable it to maintain plasticity and temporary shape in the autoclaved condition. The device is laid on the surface of the patient's body to mark the root of the catheter with a felt-tipped marker before catheterization. That enables us to know the accurate catheter root and tunneled cuffed catheter exit site on the body surface. Ten patients underwent tunneled cuffed catheter insertion according to the marking.Case description: The mean age was 71.3 +/- 12.8 years. The tunneled cuffed catheter was safely placed according to the marking in all patients, and all catheter tips were placed in the right atrium. The mean verification tip location difference before and after catheterization was 0.70 +/- 0.48 cm. This result indicated that the device could assist in inserting a catheter accurately within an error of 1.18 cm. The tunneled cuffed catheters were patent in all the cases, without replacement and complications until the end of bridging use or during the observation period.Conclusion: Our newly developed insertion support device enhances safety and prevents catheter waste during replacement.

DOI： 10.1177/1129729818771884

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A novel SnO2/graphene oxide (GO) nano-nano composite was prepared by a facile sol–gel process. X-Ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and nitrogen adsorption–desorption isotherms measurements confirmed the formation of a SnO2/GO nano-nano composite. The photoreaction of this SnO2/GO nano-nano composite was studied via the photodegradation of rhodamine B (RhB). Interestingly, the degradation mode of RhB in oxygen-saturated solution is photocatalytic reaction, but the degradation mode in argon-saturated solution is not photocatalytic reaction.

DOI： 10.1016/j.matchemphys.2018.03.046

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Several studies have demonstrated the ability of graphene oxide (GO) to efficiently adsorb small-interfering RNA (siRNA) on its surface and to transport it into cells. However, studies on whether and how siRNA interacts with GO are still inconclusive. In this context, understanding the interaction between GO and siRNA is fundamental to design new efficient gene silencing tools. In this work, the interactions between GO and siRNA molecules were systematically investigated. We focused on how the GO size, oxygenated groups present on the surface and chemical functionalization affect the double helix siRNA structure, using gel electrophoresis, UV-Vis spectroscopy, fluorescence resonance energy transfer (FRET) and circular dichroism (CD). We found that the siRNA secondary structure was clearly altered by the interaction with GO flakes. In addition, we were able to correlate the double strand damage with the size and the oxygenated groups present on the GO sheets. Finally, we demonstrated that GO functionalized with low molecular weight polyethyleneimine (PEI, 800 Da) is able to protect siRNA from structural modifications. We believed that this research effort will improve our understanding of the behavior of GO/siRNA complexes, and thus facilitate the design of appropriate bio/nanointerfaces and new efficient gene silencing systems.

DOI： 10.1039/c8nr00333e

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As a thermoelectric (TE) material suited to applications for recycling waste-heat into electricity through the Seebeck effect, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) is of great interest. Our research demonstrates a comprehensive study of different post-treatment methods with nitric acid (HNO3) to enhance the thermoelectric properties of PEDOT:PSS. The optimum conditions are obtained when PEDOT:PSS is treated with HNO3 for 10 min at room temperature followed by passing nitrogen gas (N-2) with a pressure of 0.2 MPa. Upon this treatment, PEDOT:PSS changes from semiconductor-like behaviour to metal-like behaviour, with a simultaneous enhancement in the electrical conductivity and Seebeck coefficient at elevated temperature, resulting in an increase in the thermoelectric power factor from 0.0818 to 94.3 W m(-1) K-2 at 150 degrees C. The improvement in the TE properties is ascribed to the combined effects of phase segregation and conformational change of the PEDOT due to the weakened coulombic attraction between PEDOT and PSS chains by nitric acid as well as the pressure of the N-2 gas as a mechanical means.

DOI： 10.1039/c8ra06094k

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TRANS TECH PUBLICATIONS LTD  

We have developed a combined approach of metaheuristic optimization algorithms (MOA), such as the genetic algorithm, with an ab-initio materials simulation engine. Concurrent run of the ab-initio calculations with each different parameter set selected by the MOA searches the optimum condition within a given input-parameter space. Using this methodology, the optimum dopant and its position/structure at a graphene edge are found to be a multiple N-atoms doping at graphitic sites, which predicts to lead to better charging/discharging performance when it is used as an anode material of Li-ion battery.

DOI： 10.4028/www.scientific.net/MSF.941.2356

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DOI： 10.1002/9783527823987.vol4_c2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Gene therapy has attracted tremendous attention as a promising method for the treatment of many diseases. Graphene oxide (GO), the oxidized form of graphene, is showing lot of potential in this field. Indeed, the polar GO oxygenated functional groups make this material highly hydrophilic, leading to a good dispersibility in water. Until now, the interaction of small interference RNA (siRNA) with graphene materials has not been elucidated. The main goal of this work was to develop a novel platform to complex siRNA molecules and to rationalize the supramolecular interactions between GO surface and the double strand RNA. Our study focused first on green and facile methods such as hydrothermal or vitamin C treatments to prepare graphene oxides at various percentage of oxygen. Epoxidation was also explored to reintroduce epoxide groups on reduced GO for further functionalization. Subsequently, we performed the covalent functionalization of GO with triethyleneglycoldiamine (TEG) and with low molecular weight polyethyleneimine (PEI) via the epoxy ring opening reaction. Finally, by gel electrophoresis, we were able to correlate the GO complexation ability with the graphene surface chemistry. In addition, ozonated GO functionalized with PEI showed a high complexing capacity for siRNA, proving to be a promising candidate for gene silencing. (C) 2017 The Authors. Published by Elsevier Ltd.

DOI： 10.1016/j.carbon.2017.07.016

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The effect of preparation method on the properties of Co supported beta-zeolite catalysts was examined in this study. Co-supported beta-zeolite catalysts (20wt.% Co as Ca3O4) were prepared by impregnation (IMP20), incipient wetness (IW20), physical mixing (PHY20) and precipitation (PCT20) methods and were characterized by various methods including N-2 adsorption (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H-2 thermal programmed reduction (H-2-TPR), and transmission electron microscopy (TEM). Fischer-Tropsch (FT) synthesis was carried out over these catalysts at 230 degrees C and 1 MPa in a fixed-bed flow-type reactor. XPS and H-2-TPR analyses suggest that the catalysts can be ranked in terms of metal-support interactions: PCT20&gt;IMP20 congruent to IW20&gt;PHY20. On the other hand, based on reducibility, the catalysts were ordered as follows: PHY20&gt;IMP20 congruent to IW20&gt;PCT20. The catalytic activity and product selectivity during FT synthesis were also found to depend on the catalyst preparation method. The catalyst prepared by the incipient wetness method exhibited the highest CO conversion with high liquid production, whereas the physically mixed catalyst showed the lowest CO conversion. All the catalysts produced gasoline-range liquid hydrocarbons (C-5 -C-11) mainly and the selectivity towards i-paraffins was more than 60% in the case of the catalyst prepared by precipitation. Furthermore, the composition of liquid products produced over catalysts prepared by the impregnation and incipient wetness methods were similar to each other. Thus, the results of the study clearly show that the physico-chemical properties of the catalysts as well as catalytic activities and product selectivity during the FT reaction strongly depend on the catalyst preparation method. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cattod.2017.01.017

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A reductive coupling reaction using two-dimensional nanocarbon, i.e., reduced graphene oxide (rGO), as a carbocatalyst and/or a reaction initiator was developed. The radical species on the rGO played an important role in the coupling reaction.

DOI： 10.1039/c7cc02337e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Continuous-flow nanocatalysis based on metal nanoparticle catalyst-anchored flow reactors has recently provided an excellent platform for effective chemical manufacturing. However, there has been limited progress in porous structure design and recycling systems for metal nanoparticle-anchored flow reactors to create more efficient and sustainable catalytic processes. In this study, traditional paper is used for a highly efficient, recyclable, and even renewable flow reactor by tailoring the ultrastructures of wood pulp. The "paper reactor" offers hierarchically interconnected micro-and nanoscale pores, which can act as convective-flow and rapid-diffusion channels, respectively, for efficient access of reactants to metal nanoparticle catalysts. In continuous-flow, aqueous, room-temperature catalytic reduction of 4-nitrophenol to 4-aminophenol, a gold nanoparticle (AuNP)-anchored paper reactor with hierarchical micro/nanopores provided higher reaction efficiency than state-of-the-art AuNP-anchored flow reactors. Inspired by traditional paper materials, successful recycling and renewal of AuNP-anchored paper reactors were also demonstrated while high reaction efficiency was maintained.

DOI： 10.1002/cssc.201700576

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We have used a cationic surfactant cetyltrimethylammonium bromide (C16TAB) to increase the interlayer spacing between laminates in graphene oxide (GO) membranes for higher water flux. The addition of C16TAB to the GO membrane increased the permeability without compromising the ability to completely reject sucrose molecules. Species larger than sucrose can still permeate through modified GO membranes nearly with same rate as in the case of pure GO membranes. We speculate that interaction of C16TAB surfactant with sucrose molecules could be responsible for the selective rejection of sucrose. The selective rejection of sucrose, which is a common draw in forward osmosis (FO) process, suggests that surfactant modified GO membranes have the potential to improve the efficiency of the FO process.

DOI： 10.1016/j.carbon.2017.01.102

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Graphite oxide (GO) and its constituent layers (i.e., graphene oxide) display a broad range of functional groups and, as such, have attracted significant attention for use in numerous applications. GO is commonly prepared using the "Hummers method" or a variant thereof in which graphite is treated with KMnO4 and various additives in H2SO4. Despite its omnipresence, the underlying chemistry of such oxidation reactions is not well understood and typically affords results that are irreproducible and, in some cases, unsafe. To overcome these limitations, the oxidation of graphite under Hummers-type conditions was monitored over time using in situ X-ray diffraction and in situ X-ray absorption near edge structure analyses with synchrotron radiation. In conjunction with other atomic absorption spectroscopy, UV vis spectroscopy and elemental analysis measurements, the underlying mechanism of the oxidation reaction was elucidated, and the reaction conditions were optimized. Ultimately, the methodology for reproducibly preparing GO on large scales using only graphite, H2SO4 and KMnO4 was developed and successfully adapted for use in continuous flow systems.

DOI： 10.1021/acs.chemmater.6b04807

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Single-walled carbon nanotubes (SWCNTs) are potentially strong optical absorbers with tunable absorption bands depending on their chiral indices (n, m). Their application for solar energy conversion is difficult because of the large binding energy (&gt; 100 meV) of electron-hole pairs, known as excitons, produced by optical absorption. Recent development of photovoltaic devices based on SWCNTs as light-absorbing components have shown that the creation of heterojunctions by pairing chirality-controlled SWCNTs with C-60 is the key for high power conversion efficiency. In contrast to thin film devices, photocatalytic reactions in a dispersion/solution system triggered by the photoexcitation of SWCNTs have never been reported due to the difficulty of the construction of a well-ordered surface on SWCNTs. Here, we show a clear-cut example of a SWCNT photocatalyst producing H-2 from water. Self-organization of a fullerodendron on the SWCNT core affords water-dispersible coaxial nanowires possessing SWCNT/C-60 heterojunctions, of which a dendron shell can act as support of a co-catalyst for H-2 evolution. Because the band offset between the LUMO levels of (8, 3) SWCNT and C-60 satisfactorily exceeds the exciton binding energy to allow efficient exciton dissociation, the (8, 3) SWCNT/fullerodendron coaxial photocatalyst shows H-2-evolving activity (QY = 0.015) upon 680-nm illumination, which is E-22 absorption of (8, 3) SWCNT.

DOI： 10.1038/srep43445

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Beilstein-Institut Zur Forderung der Chemischen Wissenschaften  

Discribed in this article is a versatile and practical method for the synthesis of C3-perfluoroalkyl-substituted phthalides in a one-pot manner. Upon treatment of KF or triethylamine, 2-cyanobenzaldehyde reacted with (perfluoroalkyl)trimethylsilanes via nucleophilic addition and subsequent intramolecular cyclization to give perfluoroalkylphthalides in good yields.

DOI： 10.3762/bjoc.14.12

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A highly efficient one-pot preparation of manganese/graphite oxide (MnOX/GO) composite from graphite and KMnO4 is described. Hummers preparation method of GO requires a stoichiometric amount of KMnO4, as a result, the method produces a large amount of reduced Mn species. The Mn residue generally is a waste, therefore, we envisioned converting it to value-added materials. A MnOX/GO composite was prepared in one-pot by treating the unpurified GO with aqueous KOH. The composite was characterized by XRD, XAFS, SEM and TEM. Among various applications of the MnO(X/)GO composite, we applied it as a recyclable catalyst for bromination of saturated hydrocarbons, one of the most basic but important chemical transformations. The MnOX/GO composite is expected to be an efficient catalyst because of the high surface area and high accessibility of substrates derived from the 2-dimensional sheet structure. When the reaction of a saturated hydrocarbon and Br-2 in the presence of catalytic MnOX/GO was performed under fluorescent light irradiation, a brominated product was formed in high yield in a short reaction time. GO could strongly bind with Mn to prevent elution to the liquid phase, enabling the high recyclability.

DOI： 10.1246/bcsj.20160346

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Reduction of graphene oxide (GO) by femtosecond laser pulse irradiation of an aqueous suspension was studied. Different laser parameters such as laser fluence and irradiation time were scanned to obtain the optimum reduced graphene oxide (rGO) with fewer defect sites and lower electrical resistivity. The fabricated rGO samples were characterized using several techniques such as X-ray diffraction, UV-Visible absorption spectrometry, Raman spectroscopy, X-ray photoelectron spectroscopy, and others. The XRD profiles of rGO revealed that the interplanar spacing between carbon layers significantly decreased to 3.51 , which is close to that of pristine graphite. Furthermore, the intensity ratio of D and G bands of rGO measured by Raman spectroscopy was more than 20 % smaller than that of GO, indicating the enhancement of sp(2) domains. It is noted that the defect sites and the disorder carbon double bond networks on the basal graphene plane were relatively decreased after reduction. In addition, the electrical resistivity of rGO significantly decreased to 3.3 Omega center dot cm under the optimum condition. From these results, femtosecond laser can be used as a suitable tool for GO reduction because it is a simple, controllable, and flexible method for getting highly reduced graphene oxide.

DOI： 10.1007/s10853-016-0368-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oriental Scientific Publishing Company  

This research provides a new route to obtain gold nanoparticles (AuNPs) using an aqueous extract of air-dried Pseuderanthemum acuminatissimum Radlk leaves. The extract was used as a reducing agent in the formation of metallic gold from gold ions, and acted as a stabilizer of the obtained AuNPs in the reaction mixture. The formation of AuNPs in aqueous extract of P. acuminatissimum Radlk leaves was validated by change in color and the appearance of surface plasmone resonance (SPR) peak at 552 nm. The average size of the gold nanoparticles was 63 nm, and irregular shapes were observed in the reaction mixture. Fourier transform infrared spectroscopy (FT-IR) reveals the presence of organic compound containing hydroxyl functional groups in the air-dried P. acuminatissimum Radlk leaves, which predicted to be the most responsible for the reduction of gold ions to form metallic gold. The antibacterial properties of the gold nanoparticles were studied using Escherichia coli (ATCC 8739 TM∗) strain
the AuNPs significantly inhibited the growth of E. coli indicated by a slight increase in the size of the inhibition zone as the volume of added nanocolloid was increased. Therefore, the present study indicated the promising of green synthesis of AuNPs using biological agents and as a potential material to inhibit the bacterial growth.

DOI： 10.13005/ojc/330221

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry  

We propose herein initial results to develop optimum redox mediators by the combination of computational simulation and catalytic functionalization of the core structure of vitamin K3. We aim to correlate the calculated energy value of the LUMO of different vitamin K3 derivatives with their actual redox potential. For this, we optimized the catalytic alkylation of 1,4-naphthoquinones with a designed Ag(i)/GO catalyst and synthesized a series of molecules.

DOI： 10.1039/c7cc03910g

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DOI： 10.1007/s11664-017-5327-x

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DOI： 10.1155/2017/5702838

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Universiti Malaysia Pahang  

A study of the effectiveness of graphene oxides (GO) dispersed in water as a lubricant additive between tungsten carbide (WC) pin against stainless steel (SUS304) plate was carried out. A 0.1 wt.% GO was prepared and used as a lubricant under an applied load of 3 N for 20,000 friction cycles of reciprocating tribological testing. The results show that a GO dispersion with pH 3 provided the lowest friction coefficient, which was approximately 0.05. Worn areas on the wear track of the SUS304 flat plate and WC ball surface were also small. The increasing pH obviously affected the tribological properties, where the friction coefficient increased to approximately 0.10-0.20 in the steady state for pH 5, pH 7 and pH 9. Meanwhile, a GO dispersion with pH 10 was not able to provide good tribological properties for the tested materials. The observations on microscopic images revealed the formation of tribofilms on the wear tracks for low pH. The tribofilms caused reduction of the friction force and protected the plates from severe wear during the sliding tests.

DOI： 10.15282/ijame.13.1.2016.2.0262

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Oxidative C-H coupling reactions were conducted using graphene oxide (GO) as an oxidant. GO showed high selectivity compared with commonly used oxidants such as (diacetoxyiodo) benzene and 2,3-dichloro-5,6-dicyano-p-benzoquinone. A mechanistic study revealed that radical species contributed to the reaction. After the oxidative coupling reaction, GO was reduced to form a material that shows electron conductivity and high specific capacitance. Therefore, this system could concurrently achieve two important reactions: C-C bond formation via C-H transformation and production of functionalized graphene.

DOI： 10.1038/srep25824

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Indole readily undergoes nucleophilic substitution at the C3 site, and many indole derivatives have been functionalized using this property. Indole also forms indolium, which allows electrophilic addition in acidic conditions, but current examples have been limited to intramolecular reactions. C2 site-selective nucleophilic addition to indole derivatives using fluoroalcohol and a Lewis acid was developed.

DOI： 10.1021/acs.orglett.6b00629

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Graphene oxide (GO) is widely recognized as a promising material in a variety of fields, but its structure and composition has yet to be fully controlled. We have developed general strategies to control the oxidation degree of graphene-like materials via two methods: oxidation of graphite by KMnO4 in H2SO4 (oGO), and reduction of highly oxidized GO by hydrazine (rGO). Even though the oxygen content may be the same, oGO and rGO have different properties, for example the adsorption ability, oxidation ability, and electron conductivity. These differences in property arise from the difference in the underlying graphitic structure and the type of defect present. Our results can be used as a guideline for the production of tailor-made graphitic carbons. As an example, we show that rGO with 23.1 wt% oxygen showed the best performance as an electrode of an electric double-layer capacitor.

DOI： 10.1038/srep21715

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Metal nanoparticles were formed on graphene oxide by a deposition process with hydrosilane, giving thin layer metal graphene oxide (metal/GO) composites. The particle size and catalytic activity could be controlled by varying the hydrosilane amount. Hydrosilane prevented the aggregation of GO layers by surface functionalization via silane coupling reaction. The metal/GO composites were evaluated as catalysts in hydrosilane oxidation.

DOI： 10.1246/bcsj.20150331

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Metal-free oxidation of indoline using molecular oxygen as an oxidant was investigated. Among various carbon-based catalysts, we found that reduced graphene oxide (rGO) was the most active. Superoxide radical was formed in the course of the reaction. Although graphene oxide (GO) did not function as a catalyst, rGO could be recycled at least 5 times without any structural change.

DOI： 10.1246/cl.150905

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Language：Japanese   Publisher：THE CARBON SOCIETY OF JAPAN  

Oxidation of graphite produces graphite oxide and/or graphene oxide, both of which are abbreviated "GO". The preparation methods of these materials have been described by Brodie, Staudenmaier, and Hummers. Graphene oxide is widely recognized as a promising material in various fields, but its structure and composition has still not been fully controlled. In this article, general strategies to control the structure, particle size, and oxidation degree of graphene-like materials are introduced with emphasis on the oxidation of graphite by KMnO4 in H2SO4 (oGO) and the reduction of highly oxidized graphene oxide by hydrazine (rGO). Even though the oxygen content is the same, oGO and rGO have different properties, such as adsorption ability, oxidation ability, and electronic conductivity, because of differences in the persisting graphitic structure and defects. These results can be used as a guideline for the production of tailor-made GO. The current method of GO preparation is also discussed.

DOI： 10.7209/tanso.2016.15

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Other Link： https://jlc.jst.go.jp/DN/JLC/20021713420?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Recent progress in portable and wearable electronics has promoted a growing demand for high-performance and flexible energy-storage devices that are abundant and affordable. Because reduced graphene oxide (rGO), originating from inexpensive graphite, serves as a higher-performance energy-storage electrode than conventional activated carbons and carbon nanotubes, research and development of rGO/polymer composite electrodes for flexible supercapacitors have become a center of attraction. However, the fabrication of rGO-based flexible electrodes frequently requires a long time with high-temperature treatment or toxic chemical treatment, resulting in the lack of scalability and eco-friendliness. Here we show a fast, scalable, and environment-compatible route to fabricate a high-performance rGO/cellulose paper supercapacitor electrode. Single-layer graphene oxide (GO) sheets and recycled waste pulp fibers were successfully fabricated into a paper composite by a well-established scalable papermaking process, followed by a room-temperature, additive-free, and millisecond-timescale flash reduction process. The as-prepared rGO/paper electrode had a high specific capacitance, up to 212 F g(-1), for an all paper-based flexible supercapacitor, comparable to those of state-of-the-art rGO-based electrodes, while dramatically decreasing the reduction time of GO from the conventional hour timescale to milliseconds. This work will pave the way for green, flexible, and mass-producible energy-storage paper in future wearable electronics.

DOI： 10.1039/c5gc01949d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

Graphene oxide (GO) contains graphitic single-layered sheets, while oxidized wood-based nanocarbon (oWNC) is composed of graphitic nanoshells. Since both materials are thoroughly oxidized with many oxygen-containing functional groups, both GOs and oWNCs form stable dispersions in water. We found that lubrication by dispersions of GOs and oWNCs in water resulted in very low friction coefficients below 0.04 with only slight plate surface wear using a steel plate and tungsten carbide ball. After lubrication, thick tribofilms are formed on the sliding surfaces, which would decrease the friction. In this study, in order to clarify the tribological mechanisms that result in such low friction coefficients, we have performed tribological tests and analyzed the tribofilms formed by dispersions of GO in water using confocal laser scanning microscopy (CLSM) with an optical data storage system, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The GO tribofilm is composed of many carbons and some oxygen, derived from the disordered and aggregated GO sheets. The GO tribofilm have higher hardness and hydrophilic properties than the steel plates, which would provide low friction and wear. It is found that both the GO tribofilm and GOs are necessary to achieve the lowest possible coefficient of friction. It is likely that the oWNC tribofilm has similar friction and wear decreasing effects to that of the GO dispersion.

DOI： 10.2474/trol.11.235

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

Many reports recently show that some plant and animal extracts were useful to prepare some desired materials. In line with the statement, this report will present a bioresources candidate that can be used for green preparation of gold nanoparticles. The Scaevola fruteschen (Mill.) Krause was obtained from Enggano island, Bengkulu Province, Indonesia. The current research include synthesis, characterization and application study of the obtained nanoparticles in their original medium/reduction system as antibacterial agent of Escherichia coli. Besides that, the interaction study of the nanoparticles solution with Pb2+ ions was also studied. The results, shows that the present reduction system (aqueous extract of the plant leaves) successfully reduced gold (III) ions to gold metals as shown by new peak at 544 nm in spectrophotometry analysis. The average nanopartiles size was 96 nm based on Particles Size Analyzer (PSA) result. The stability study revealed that the nanoparticles solution was not stable in the persence of Pb(OAc)(2) at high concentration. The nanoparticles were effective enough toward E. coli as shown by inhibition zone that indicates the degree of sensitivity of bacteria to nanoparticles.

DOI： 10.1063/1.4941483

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Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.71.2.0_1279

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

One-pot synthesis of 2-arylphenols starting from 2-iodo-2-cyclohexen-1-one and arylboronic acids through sequential Suzuki-Miyaura coupling/dehydrogenative aromatization with Pd/C catalysis has been developed. A range of arylboronic acids serve as substrates, including those containing electron-donating or electron-withdrawing groups. Additionally, one-pot synthesis of di- or trisubstituted phenols bearing a phenyl group at the ortho position are also generated by using 2-iodo-2-cyclohexen-1-one derivatives as substrate. In the present method, commercially available and easily removable Pd/C was employed as a catalyst without any ligands. The operationally simple procedure and accessible conditions were used to provide modified phenols as the sole product in moderate to high yields.

DOI： 10.1002/ejoc.201500723

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Language：English   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：RJPBCS RESEARCH JOURNAL PHARMACEUTICAL, BIOLOGICAL & CHEMICAL SCIENCES  

Gold nanoparticles (AuNPs) were synthesized easily using bottom-up method in aqueous extract of air-dried P. obtusifulia R. Br. leaves without elevated temperature. The appearance of surface plasmon resonance (SPR) peak at 549.5 nm in UV-Vis spectrometry analysis give the early evidence of the AuNPs in the solution. The particles shape was in spherical form and the average size of obtaining amps is 90, 25 nm. The AuNPs was stable for several days and also sensitive toward Pb(OAc)(2) solution.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Hydrosilane enabled the formation of Pt nanoparticles and the silane functionalization of a carbon support material in one pot. The metal/Si-modified carbon composites are highly durable during catalytic methane oxidation.

DOI： 10.1039/c4cc10298c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Hydrosilane enabled the formation of Pt nanoparticles and the silane functionalization of a carbon support material in one pot. The metal/Si-modified carbon composites are highly durable during catalytic methane oxidation.

DOI： 10.1039/c4cc10298c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Multi-layer graphene oxide (MGO) has attracted considerable interest in conductive polymer composites. However, in most cases the optimal MGO content is determined using a complex procedure. Avoiding the complicated work of processing polymerized samples followed by testing various properties, here a facile strategy is proposed to directly identify the critical MGO content among formulations for epoxy composites with optimal thermal properties, simply by monitoring the "unusual" nonlinear MGO content-dependent cure behaviors, as well as the "unusual" pattern of double-peak curing curves. The formation mechanism of the double-peak pattern was explored, with emphasis on studying the epoxy/MGO reaction using a modified Shrinking Core Model. The optimal content determined in this work 2 wt% MGO) was verified by the thermal properties (thermal conductivity, structural thermal stability and coefficient of thermal expansion) of MGO/epoxy composites. Based on the inherent relationship between the effect of MGO percolating chains on the thermal polymerization behavior and the resulting thermal properties, this strategy can be easily extended to different kinds of conductive MGO/polymer composites.

DOI： 10.1039/c4ra15881d

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DOI： 10.3144/expresspolymlett.2015.57

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

High-performance lubricating additives are desired in order to improve the properties of lubricating fluids. Recently, carbon nanomaterials such as fullerenes, carbon nanotubes, and carbon onions have been studied as lubricating additives for water and lubricating oils. However, the costs of these carbon nanomaterials are too high for practical use. On the other hand, graphene oxide (GO) is a carbon nanomaterial that consists of single atom thick sheets that possess a large number of oxygen functional groups. Since GO is synthesized from graphite using a chemical liquid process, the cost of GO is significantly lower than other carbon nanomaterials. In this study, the application and tribological properties of GO monolayer sheets as additives in water and poly-alpha olefin (PAO) were investigated. The dependence of the friction coefficient of GO-water dispersions on GO concentration (0.01-1.0 mass %) was investigated. In particular, GO-water dispersions with a concentration of less than 0.1 mass % demonstrated low friction coefficients. In this study, GO was simply dispersed in PAO using surfactant and intermediary solvents without the need for drying treatments. We found that the use of anionic surfactants in the GO-PAO dispersions was better than cationic surfactants in terms of the degree of wear observed. Specifically, GO-PAO dispersions that used an anionic surfactant with a GO concentration of 4 mass % had the smallest wear in this study. Moreover, friction coefficients were not decreased by the addition of GO in PAO. Finally, we found that intermediary solvents did not affect lubrication.

DOI： 10.1299/mej.15-00323

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Reaction of several Vilsmeier reagents with 5-amino-2,3-dihydro[1]benzofuro[3,2-b]oxepin-4-carbonitrile gave tetracyclic 2-substituted 4-chloro-5,6-dihydro[1] benzofuro[3',2':2,3]oxepino[4,5-d]pyrimidines. The structure of one of these, the 4-chloro-2-phenyl derivative, was confirmed by X-ray crystallography. Treatment of the 4-chloro derivatives with simple amines as nucleophile afforded 2-substituted 4-amino derivatives. A pentacyclic compound was also obtained by dehydrative ring closure. These products were evaluated for antiplatelet activity, and some showed potency comparable with that of aspirin.

DOI： 10.1002/jhet.1539

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Application and tribological properties of graphene oxide (GO) monolayer sheets as additives in water-based lubricants were investigated. The lubricating fluids were applied to a sintered tungsten carbide ball and stainless steel flat plate. It was found that adding GO particles into water improved lubrication and provided a very low friction coefficient of approximately 0.05 with no obvious surface wear after 60,000 cycles of friction testing. GO adsorption occurred on the lubricated surfaces of both the ball and flat plate, suggesting GO sheets may behave as protective coatings. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbon.2013.08.045

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Pd nanoparticles supported on single layer graphene oxide (Pd-slGO) were prepared by gentle heating of palladium(II) acetate (Pd(OAc)(2)) and GO in ethanol that served as a mild reductant of the Pd precursor. Pd-slGO showed a high catalytic performance (TON and TOF = 237 000) in the Suzuki-Miyaura cross-coupling reaction.

DOI： 10.1039/c4nr00715h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry  

The interlayer distance of graphene oxide (GO) in a Pd/GO composite could be tuned using cationic surfactants. The distance becomes larger when a large surfactant is used. The catalytic activity in Heck reactions dramatically improved using the surfactant-modified Pd/GO catalyst. Substrate selectivity could also be improved by adjusting the size of the surfactant to increase accessibility of substrates to the active catalytic centre.

DOI： 10.1039/c4ra10512e

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Language：Japanese   Publisher：SOC SYNTHETIC ORGANIC CHEM JPN  

One of the important research topics in the synthesis of pharmaceuticals and fine chemicals is to convert homogeneous reactions to heterogeneous versions by immobilization of metal species on polymer or inorganic supports. The oxidation state of the metal species can affect the character and reactivity of the catalyst. Recently, chemists have gained excellent techniques to control particle size and oxidation state of metal species, which has led to the development of new heterogeneous catalysts for organic reactions.

DOI： 10.5059/yukigoseikyokaishi.71.1307

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

An efficient and user-friendly protocol has been realized for the Heck reaction of heteroaryl bromides by using a reusable nanocrystalline magnesium oxide-stabilized palladium(0) catalyst without the aid of additional ligands and base. Dimethylamine generated under in situ conditions by the decomposition of DMF serves as the base in this reaction. The catalyst was reused with consistent activity up to four cycles. © 2013 The Royal Society of Chemistry.

DOI： 10.1039/c3cy00404j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BEILSTEIN-INSTITUT  

The bromination of hydrocarbons with CBr4 as a bromine source, induced by light-emitting diode (LED) irradiation, has been developed. Monobromides were synthesized with high efficiency without the need for any additives, catalysts, heating, or inert conditions. Action and absorption spectra suggest that CBr4 absorbs light to give active species for the bromination. The generation of CHBr3 was confirmed by NMR spectroscopy and GC-MS spectrometry analysis, indicating that the present bromination involves the homolytic cleavage of a C-Br bond in CBr4 followed by radical abstraction of a hydrogen atom from a hydrocarbon.

DOI： 10.3762/bjoc.9.190

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

Aqueous rinds extract of Brucea javanica (L.) Merr has been used as the medium/reducing system for the formation of silver nanoparticles colloids. A solution of 0.01 N AgNO3 (1 ml) was added to the rind extracts (4 ml) at room temperature, and the formation of silver nanoparticles was observed using ultraviolet-visible spectrophotometer. The shape and size of the nanoparticles have been characterized using Transmission Electron Microscope (TEM) analysis. The experimental results show that the silver nanoparticles are formed easily in the extract at ambient temperature. The resulting nanoparticles were in the spherical form and the average size of the nanoparticles was about 38.00 +/- 14.00 nm. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2013.01.114

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The ethyl methyl imidazolium salts of amino acids, [emiml[AA], have been used as catalysts in the aza-Michael reaction. Furthermore, when chiral amino acids were used, a stereoselective reaction was achieved. The mechanism of the transformation was verified by the detection of a key intermediate by electrospray ionization mass spectroscopy (ESI-MS). (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2012.11.012

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Catalytic oxidative aromatization has been achieved using 2-cyclohexen-1-ones to obtain phenol derivatives in the presence of a catalytic amount of copper salt and aqueous HBr under molecular oxygen. The amount of HBr was successfully reduced to a catalytic quantity, and the other additive such as a ligand and an oxidant as well as inert conditions were unnecessary. Various mono-, di-, and trisubstituted phenols with substituents at the desired positions could be synthesized under cheap and simple conditions. An oxidative aromatization/bromination sequence was also demonstrated to obtain bromophenols with excess HBr.

DOI： 10.1039/c3ra43071e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Palladium-supported graphene oxide has been successfully applied as a catalyst precursor for the selective reduction of alpha,beta-unsaturated carbonyl compounds. Pd nanoparticles were formed during the course of the reduction with only negligible leaching of the Pd species into the reaction mixture.

DOI： 10.1039/c3ra42150c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A method for the direct bromination of hydrocarbons with Br-2 using a ubiquitous and inexpensive catalyst is highly desirable. Herein, we report the selective mono-bromination of hydrocarbons in good yield using Li2MnO3 as a catalyst under irradiation with a fluorescent room light. This new catalyst can be recycled. The effect of light was investigated using action spectra, which revealed that the reaction occurred on the surface of the catalyst.

DOI： 10.1039/c2ra22197g

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Language：Japanese   Publisher：Japan Society of Powder and Powder Metallurgy  

In the natural aquatic environment, there are various types of biogenic manganese oxide (BMO) precipitates which are produced by manganese oxidizing microorganisms, at ambient temperature, atmosphere and neutral pH.BMO is a very interesting and useful functional material because of its unique property; hollow globule shape formed by nanosheets, large surface area and photocatalytic characteristics. In this study, thermally-processed BMO at 100 − 1000 °C was analyzed by XRD, XANES, SEM, TEM and nitrogen adsorption method to reveal the effects of heat-treatment on its crystal structure, Mn valence state, globule morphology, microstructure, pore size distribution and specific surface area. In the result, morphology of BMO is maintained below 800 °C, while nanosheets composing BMO were changed into nanoparticles at 600 °C. The crystal structure was transformed from birnessite into hausmannite (Mn₃O₄) at 600 °C. The specific surface area was increased by heat-treatment between 300 and 500 °C. In cases of artificial manganese oxides, such changes of crystal structure and specific surface area were not observed, and combustion of organic materials produced by microorganisms in BMO probably has a large effect on them.

DOI： 10.2497/jjspm.60.92

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INT UNION CRYSTALLOGRAPHY  

In the title compound, C14FH13ClN2O, the fused hydropyrimidine ring adopts an envelope conformation with one of the methylene C atoms at the flap. The three-membered ring is approximately perpendicular to the attached isoquinoline ring system, with a dihedral angle of 89.44(11)°. In the crystal, molecules are linked by a weak C-H⋯π interaction, forming a helical chain along the c axis.

DOI： 10.1107/S1600536812044261

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INT UNION CRYSTALLOGRAPHY  

The asymmetric unit of the title compound, C13H 9NO3, consists of two crystallographically independent molecules. In each molecule, the tetra-hydro-furan (THF) ring adopts an envelope conformation with one of the methyl-ene C atoms positioned at the flap. The dihedral angles between the mean plane of the THF and the benzofuran ring system are 70.85 (5) and 89.59 (6)°. In the crystal, molecules are stacked in a column along the a-axis direction through C - H⋯O hydrogen bonds, with columns further linked by C - H⋯N and C - H⋯O interactions.

DOI： 10.1107/S1600536812036835

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC PLANT BIOLOGISTS  

Plant activators are compounds, such as analogs of the defense hormone salicylic acid (SA), that protect plants from pathogens by activating the plant immune system. Although some plant activators have been widely used in agriculture, the molecular mechanisms of immune induction are largely unknown. Using a newly established high-throughput screening procedure that screens for compounds that specifically potentiate pathogen-activated cell death in Arabidopsis thaliana cultured suspension cells, we identified five compounds that prime the immune response. These compounds enhanced disease resistance against pathogenic Pseudomonas bacteria in Arabidopsis plants. Pretreatments increased the accumulation of endogenous SA, but reduced its metabolite, SA-O-beta-D-glucoside. Inducing compounds inhibited two SA glucosyltransferases (SAGTs) in vitro. Double knockout plants that lack both SAGTs consistently exhibited enhanced disease resistance. Our results demonstrate that manipulation of the active free SA pool via SA-inactivating enzymes can be a useful strategy for fortifying plant disease resistance and may identify useful crop protectants.

DOI： 10.1105/tpc.112.098343

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

New class of hybrid composite was synthesized via sol-gel process with the combination of poly(vinyl alcohol) (PVA), TEOS, 3-glycidyloxypropyltrimethoxysilane (GPTMS) reacted with the cross-linking agent glutaraldehyde. The composites demonstrated a maximum high proton conductivity of 1.7 x 10(-2) S cm(-1) at 140 degrees C and a relative humidity of 50% RH. The swelling ratio was calculated in dry and wet conditions, and the composites were found capable of swelling. The structural formation of the composites was studied by techniques such as FTIR, TGA and impedance spectroscopy, and it was concluded that these PVA-SiO2/GPTMS/GA composite membranes exhibited excellent thermal, mechanical and conductivity properties. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2012.04.023

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

1,3-Oxathiine frameworks can be prepared via the sequential addition and intramolecular cyclization of thiosalicylic acid onto alkynes. A substituent on the alkyne and the presence of a palladium catalyst can allow product regioselectivity control. This strategy is applicable to the synthesis of heterocycles comprising sulfur and oxygen atoms, namely 3,1-benzoxathiines, without any unwanted byproduct.

DOI： 10.1055/s-0032-1316563

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

An efficient method for the oxidation of benzylic and secondary aromatic alcohols into their corresponding aldehydes or ketones has been achieved by using ruthenium supported magnesium lanthanum mixed oxide as a heterogeneous catalyst in toluene, with molecular oxygen as the sole oxidant. This catalyst can also be operated in solvent free conditions at 393 K and reused for five cycles with consistent yield and selectivity. (C)2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2012.03.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Nanocrystalline ZnO was found to be a highly efficient heterogeneous catalyst for the guanylation of amines with various carbodiimides to afford N,N',N ''-trisubstituted guanidines in excellent yields. Structurally divergent aliphatic, aromatic, heterocyclic primary and secondary amines were converted to the corresponding N,N',N ''-trisubstituted guanidines using optimal conditions. The catalyst was easy to handle even under atmospheric conditions and can be easily recovered by centrifugation and reused for five cycles with consistent activity. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2012.05.044

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Hybrid materials of ultimately minimized metal particles, namely, isolated atoms or subnano-sized particles, on thermally exfoliated graphene oxide sheets were produced using cation-exchanged highly oxidized graphite as a precursor. Rh atoms on graphene sheets arrange with a regular spacing of 0.50 or 0.45 nm and form square or rectangular grid patterns, whereas isolated Pt atoms disperse on graphene sheets randomly.

DOI： 10.1246/cl.2012.680

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Pd-graphene, a composite of Pd nanoparticles and exfoliated graphene, was used as a catalyst in organic reactions. In the Suzuki-Miyaura cross-coupling reaction, Pd-graphene showed high reusability without aggregation of Pd nanoparticles. The intermediates of the reaction in the liquid phase, Ph-Pd-Br and Ph-Pd-OH, were detected by ESI-MS.

DOI： 10.1039/c2ra21185h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The catalytic bromination of non-activated aromatic compounds has been achieved using an Fe2O3/zeolite catalyst system. FeBr3 was identified as the catalytic species, formed in situ from HBr and Fe2O3. The catalyst was easy-to-handle and cost effective and could also be recycled. The reaction system was also amenable to the one-pot sequential bromination/C-C bond formation of benzene.

DOI： 10.1039/c2gc35821b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Nano- and micro-architectural manganese oxide produced by microorganisms catalyses the selective monobromination of hydrocarbons in excellent yield under irradiation of fluorescent room light. The knowledge gained from investigating natural materials will lead to unprecedented catalyst designing toward efficient organic reactions.

DOI： 10.1039/c2ra20896b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

The rhenium-catalyzed synthesis of cyclopentenone derivatives via double aldol condensation and successive Nazarov reaction is described. The cyclopentenones were converted to the corresponding cyclopentadienes using organolithium reagents. Cyclopentadienes with four different substituents could be synthesized by stepwise double aldol condensation using a ketone and two types of aldehydes, followed by treatment with an organolithium reagent.

DOI： 10.1055/s-0030-1260324

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Isobenzofuran can be prepared from o-phthalaldehyde using hydrosilane. The formed isobenzofuran Is trapped by an alkene via a Diels-Alder reaction. Further dehydration proceeds to furnish the conjugated aromatic compound. This multistep reaction was promoted by catalytic amounts of Sc(OTf)(3).

DOI： 10.1021/ol201479p

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The synthesis of unsymmetric functionalized pentacenes from 1,4-anthraquinones and functionalized isobenzofurans, which were prepared by transformation via C H bond activation, was successfully accomplished. Examples of the synthesis of pentacenes with functional groups at the 5-position are still rare. These obtained functionalized pentacenes are highly soluble in hexane, toluene, and THF.

DOI： 10.1021/ol102349r

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Treatment of olefins bearing a directing group with alpha,beta-unsaturated carbonyl compounds, alkynes, or aldehydes in the presence of a catalytic amount of a rhenium complex, [ReBr(CO)(3)(thf)](2) gave gamma,delta-unsaturated carbonyl compounds, dienes, and allyl silyl ethers, respectively. This reaction proceeds via C-H bond activation, insertion of unsaturated molecules into the formed rhenium-carbon bond, and then reductive elimination (or transmetalation in the case of aldehydes).

DOI： 10.1021/ol900962v

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A rhenium complex, [ReBr(CO)(3)(thf)](2), catalyzes the insertion of alpha,beta-unsaturated carboryl compounds into a C-H bond of aromatic compounds having nitrogen-containing directing groups. In this reaction, Re-2(CO)(10) call also be used as a catalyst. When imines are employed as the aromatic substrates, sequential cyclization proceeds and indene derivatives are obtained in good to excellent yields. This reactivity is ill contrast to those of ruthenium and rhodium complexes, which are usually used as catalysts in the insertion reactions of unsaturated molecules into a C-H bond. Investigations oil the reaction mechanism indicate that the rhenium catalyst promotes C-H bond activation of aromatic compounds, the insertion of alpha,beta-unsaturated carbonyl compounds into a Re-C bond, and intramolecular nucleophilic cyclization followed by reductive elimination and the elimination of an amine.

DOI： 10.1246/bcsj.81.1393

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Treatment of an a,p-unsaturated ketimine with an alpha,beta-unsaturated carbonyl compound in the presence of a rhenium complex, Re-2(CO)(10), gave a cyclopentadienyl-rhenium complex. This reaction proceeds via rhenium-catalyzed C-H bond activation of an olefinic C-H bond, insertion of an alpha,beta-unsaturated carbonyl compound into a Re-C bond of the alkenylrhenium intermediate, intramolecular nucleophilic cyclization, reductive elimination, elimination of aniline to give a cyclopentadiene derivative, followed by the formation of a cyclopentadienyl-rhenium complex from the cyclopentadiene derivative and the rhenium complex.

DOI： 10.1021/ja805921f

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

With the aid of a directing group, an imine moiety, heteroaromatic compounds add to acetylenes in the presence of a catalytic amount of [ReBr(CO)(3)(THF)](2) at the adjacent position of the directing group regioselectively to give hydroarylation of the acetylenes in good to excellent yields. Similarly, heteroaromatic compounds react with acrylates and isocyanates to give the corresponding hydroarylation products under rhenium catalysis. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2008.01.145

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INT UNION PURE APPLIED CHEMISTRY  

Rhenium complex, [ReBr(CO)(3)(thf)](2)-catalyzed reactions between aromatic imines and either acetylenes or alpha,beta-unsaturated carbonyl compounds gave indene derivatives in good to excellent yields. These reactions proceed via C-H bond activation, insertion of acetylenes or alpha,beta-unsaturated carbonyl compounds, intramolecular nucleophilic cyclization, and reductive elimination. Indene derivatives were also obtained from aromatic ketones and alpha,beta-unsaturated carbonyl compounds in the presence of catalytic amounts of the rhenium complex and p-anisidine. Sequential ruthenium-catalyzed hydroamination of aromatic acetylenes with anilines, and rhenium-catalyzed reactions of the formed aromatic ketimines with alpha,beta-unsaturated carbonyl compounds also provided indene derivatives.

DOI： 10.1351/pac200880051149

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Arhenium complex, [ReBr(CO)(3)(THF)](2), catalyzed reactions of aromatic ketimines and aldehydes with dienophiles, followed by dehydration, to give naphthalene derivatives in good to excellent yields. This reaction proceeds via C-H bond activation, insertion of an aldehyde, intramolecular nucleophilic cyclization, reductive elimination, elimination of aniline and Diels-Alder reaction. After dehydration, naphthalene derivatives were formed. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2007.05.083

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

DOI： 10.1002/ani3.200702256

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Language：Japanese   Publisher：THE CARBON SOCIETY OF JAPAN  

DOI： 10.7209/tanso.2017.156

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ja065643e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Formal [3+2] annulation of arylacetylenes and alpha,beta-unsaturated carbonyl compounds is achieved in a one-pot reaction by successive treatment of the acetylenes with aniline and a catalytic amount of Ru-3(CO)(12) and NH4PF6 and C-H bond activation catalyzed by [ReBr(CO)(3)(thf)](2). The result suggests that the second rhenium-catalyzed indene formation is not disturbed by the first catalyst system.

DOI： 10.1021/ol0611292

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

DOI： 10.1002/anie.200503627

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Language：Japanese  

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Language：English   Publishing type：Book review, literature introduction, etc.   Publisher：Elsevier Ltd  

A perfect molecular level separating unit for any kind of species to be filtered is on very high demand. In recent years, graphene oxide has emerged as an important material which can filter ions and molecules. This is an emerging field of research which has drawn extensive attention after the work by Nair et al. [1]. Following their work, various research groups started working in this area in last three years. Herein, we briefly review the recent development on graphene oxide membranes. This review is a summary of some very recent results and contributions made so far in this emerging research field. We have discussed recently developed mechanisms and models to understand the transport through GO based membranes. This review begins with a basic background on membrane technology followed by discussion related to developments of carbon materials based membrane technology. At the end we summarize advantages and disadvantages of membranes based on graphene oxide and discuss their future prospective.

DOI： 10.1016/j.apmt.2015.06.002

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DOI： 10.2474/trol.10.91

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Language：English   Publisher：The Japan Society of Mechanical Engineers  

The problems of oil lubricants in waste and maintenance management are crucial for cost and environment. Water with less harmful to environment is suitable as a candidate lubricant to replace oil lubricants. However, water is lack of viscosity, which leads to high friction and severe wear between the sliding materials. Graphene Oxide (GO) is single layer graphite with oxygen functional groups and easy to be dispersed in water. In this study, the effect of friction reduction by water dispersed GO has been evaluated with different sliding materials. The friction coefficients between SUS304 substrate vs. SUS304 ball and SUS304 substrate vs. tungsten carbide (WC) ball were approximately 0.05. Severe wear was apparent on the SUS304 ball surface slid in the GO dispersion; however, only small wear was observed on the WC ball surface after friction test in the GO dispersion.

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Applicant：オルガノ株式会社

Application no：特願2018-046785  Date applied：2018.3.14

Announcement no：特開2019-155292  Date announced：2019.9.19

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Applicant：日本ゼオン株式会社

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Announcement no：特開2018-172557  Date announced：2018.11.8

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Applicant：国立大学法人 岡山大学

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Applicant：国立大学法人 岡山大学

Application no：特願2016-145069  Date applied：2016.7.25

Announcement no：特開2018-016545  Date announced：2018.2.1

Patent/Registration no：特許第6464512号  Date registered：2019.1.18 

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Applicant：株式会社仁科マテリアル

Application no：特願2016-140953  Date applied：2016.7.17

Announcement no：特開2018-008920  Date announced：2018.1.18

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Applicant：株式会社日本触媒

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Announcement no：特開2017-160070  Date announced：2017.9.14

Patent/Registration no：特許第6592384号  Date registered：2019.9.27 

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Applicant：国立大学法人東北大学

Application no：特願2016-022476  Date applied：2016.2.9

Announcement no：特開2017-141335  Date announced：2017.8.17

Patent/Registration no：特許第6864877号  Date registered：2021.4.7 

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Applicant：株式会社ダイセル

Application no：特願2016-008543  Date applied：2016.1.20

Announcement no：特開2017-128472  Date announced：2017.7.27

Patent/Registration no：特許第6691782号  Date registered：2020.4.15 

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Applicant：国立大学法人北見工業大学

Application no：特願2015-249257  Date applied：2015.12.22

Announcement no：特開2017-114702  Date announced：2017.6.29

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Applicant：国立大学法人 岡山大学

Application no：特願2015-153716  Date applied：2015.8.3

Announcement no：特開2017-031106  Date announced：2017.2.9

Patent/Registration no：特許第6646295号  Date registered：2020.1.15 

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Applicant：株式会社仁科マテリアル

Application no：特願2015-047409  Date applied：2015.3.10

Announcement no：特開2016-166113  Date announced：2016.9.15

Patent/Registration no：特許第6476019号  Date registered：2019.2.8 

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Applicant：国立大学法人 岡山大学

Application no：特願2014-235013  Date applied：2014.11.19

Announcement no：特開2016-098279  Date announced：2016.5.30

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Applicant：国立大学法人 岡山大学

Application no：特願2014-199132  Date applied：2014.9.29

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Applicant：国立大学法人 岡山大学

Application no：特願2014-172774  Date applied：2014.8.27

Announcement no：特開2016-047875  Date announced：2016.4.7

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Applicant：国立大学法人大阪大学

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Announcement no：特開2015-221947  Date announced：2015.12.10

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Applicant：国立大学法人 岡山大学

Application no：JP2014063398  Date applied：2014.5.20

Publication no：WO2014-189065  Date published：20141127

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Applicant：国立大学法人 岡山大学

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Publication no：WO2014-136808  Date published：2014912

Patent/Registration no：特許第6263815号  Date registered：2018.1.5 

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Applicant：国立大学法人 岡山大学

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Publication no：WO2014-136807  Date published：2014912

Patent/Registration no：特許第6263814号  Date registered：2018.1.5 

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Applicant：仁科 勇太

Application no：特願2014-036086  Date applied：2014.2.26

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Applicant：国立大学法人 岡山大学

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Patent/Registration no：特許第6116016号  Date registered：2017.3.31 

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Applicant：国立大学法人 岡山大学

Application no：JP2013074937  Date applied：2013.9.13

Publication no：WO2014-042259  Date published：2014320

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Announcement no：特開2014-144892  Date announced：2014.8.14

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Applicant：国立大学法人 岡山大学

Application no：JP2012080866  Date applied：2012.11.29

Publication no：WO2013-081034  Date published：201366

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Applicant：国立大学法人 岡山大学

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Patent/Registration no：特許第5098064号  Date registered：2012.10.5 

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Applicant：国立大学法人 岡山大学

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Applicant：国立大学法人 岡山大学

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Patent/Registration no：特許第5863676号  Date registered：2016.1.8 

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Applicant：国立大学法人 岡山大学

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