ACS Catalysis
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2017
·
IF 10.614
Chaofeng Zhang,Hongji Li,Jianmin Lu,Xiaochen Zhang,Katherine E. MacArthur,Marc Heggen,Feng Wang
For lignin valorization, simultaneously achieving the efficient cleavage of ether bonds and restraining the condensation of the formed fragments represents a challenge thus far. Herein, we report a two-step oxidation–hydrogenation strategy to achieve this goal. In the oxidation step, the O2/NaNO2/DDQ/NHPI system selectively oxidizes CαH–OH to Cα═O within the β-O-4 structure. In the subsequent hydrogenation step, the α-O-4 and the preoxidized β-O-4 structures are further hydrogenated over a NiMo sulfide catalyst, leading to the cleavage of Cβ–OPh and Cα–OPh bonds. Besides the transformation of lignin model compounds, the yield of phenolic monomers from birch wood is up to 32% by using this two-step strategy. The preoxidation of CαH–OH to Cα═O not only weakens the Cβ–OPh ether bond but also avoids the condensation reactions caused by the presence of Cα+ from dehydroxylation of CαH–OH. Furthermore, the NiMo sulfide prefers to catalyze the hydrogenative cleavage of the Cβ–OPh bond connecting with a Cα═O rather than catalyze the hydrogenation of Cα═O back to the original CαH–OH, which further ensures and utilizes the advantages of preoxidation.
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高影响因子
ENERGY
·
2016
·
IF 4.292
Xiao Cheng,Rong Chen,Xun Zhu,Qiang Liao,Liang An,Dingding Ye,Xuefeng He,Shuzhe Li,Lin Li
The development of highly efficient photocatalytic reactor is of importance to improve the performance of the photocatalytic reduction of CO 2 . In this work, an optofluidic planar microreactor is designed and fabricated for the photocatalytic reduction of CO 2 with liquid water in alkaline environment . Such design offers several advantages of large surface-area-to-volume ratio, enhanced mass and photon transfer and more uniform light distribution. The performance of the developed planar microreactor is evaluated by measuring the methanol concentration to estimate the methanol yield under various operating parameters, including the liquid flow rate , light intensity, catalyst loading and NaOH concentration. It is shown that increasing the liquid flow rate firstly improves and then decreases the methanol concentration while the methanol yield continuously increases as the liquid flow rate increases. The increase of the light intensity and NaOH concentration increases both the methanol concentration and yield. Increasing the catalyst loading firstly improves the performance and then results in the reduction of the performance. A maximum methanol yield of 454.6 μmole/g-cat·h is achieved under a liquid flow rate of 50 μL/min, 0.2 M NaOH, and the light intensity of 8 mW/cm 2 .
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高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2016
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IF 2.567
Yu Liu,Weidong Chi,Donglin Zhao,Hui Liu,Yu Deng
The molecular-cage method is a convenient and universal way of synthesizing nanoparticles in aqueous phase. In this paper, hydroxyapatite (HA) and zirconium hydroxide nanoparticles are made by the molecular-cage method with a hydroxyl-rich solute. The structure, morphology, and particle size of the product were analyzed by differential scanning calorimetry and scanning electron microscopy. The chemical structures of the particles are not affected by the molecular-cage effect. The sizes of the nanoparticles and the concentration of the solute have a corresponding relationship in a limited range. The higher the concentration of the solute, the smaller the nanoparticles. Besides, HA nanoparticles are also made by the molecular-cage method in a water/ethanol mixture.
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高影响因子
RSC Advances
·
2016
·Vol. 6
·期 76
·71963-71969
·
IF 3.289
Yimeng Zhang,Pengyao Xing,Minmin Yang,Yajie Wang,Bo Wang,Aiyou Hao,Mingfang Ma
Anthracen-9-ylmethyl octadecylcarbamate (A-9-YMOC) contains an anthracen headgroup, an imide group, and a long alkyl chain, which could show π–π stacking, hydrogen-bonding, and van der Waals interactions, respectively. The capability of A-9-YMOC to form well-ordered micro/nanostructures in different solvents was explored. And the influence of solvents with various polarities that can modulate the self-assembly behavior, including H-bond-forming solvents, π-stacking-forming solvents or van der Waals-type solvents was studied. In addition, different supramolecular architectures, including nanofibers and nanoflowers were observed during the solvent-polarity-tuned process, which were found to have different molecular arrangements. This work may provide a facile method to manipulate the morphology and properties of self-assembled low-molecular-weight organic building blocks.
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高影响因子
RSC Advances
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2017
·Vol. 7
·期 37
·22722-22727
·
IF 3.108
Jing-Xiao Wang,De-Wei Ni,Shao-Ming Dong,Guang Yang,Yan-Feng Gao,Yan-Mei Kan,Xiao-Wu Chen,Yan-Peng Cao,Xiang-Yu Zhang
Nanocrystallized zirconium carbide (ZrC) powder was synthesized by an aqueous solution-based process using zirconium acetate and sucrose as starting reagents. Polyvinyl pyrrolidone (PVP) was used to combine the reactants to form a suitable precursor for ZrC. Through such a novel aqueous solution-based process, fine-scale mixing of the reactants is achieved in an environmentally friendly manner. The formed precursor can be converted to ZrC by carbothermal reduction reaction at 1600–1650 °C. Thanks to a limited amount of residual free carbon, the as-synthesized ZrC powder had an ultra-fine particle size (50–100 nm) and a low oxygen content less than 1.0 wt%. The conversion mechanisms from as-synthesized pre-ceramic precursor to ZrC powder were investigated systematically and revealed by means of FTIR, TG-DSC, XRD, Raman, SEM and TEM.
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高影响因子
MICROCHIMICA ACTA
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2016
·Vol. 183
·期 5
·1651-1657
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IF 4.831
Rao Hanbing,Ge Hongwei,Lu Zhiwei,Liu Wei,Chen Ziqi,Zhang Zhaoyi,Wang Xianxiang,Zou Ping,Wang Yanying,He Hua,Zeng Xianying
We report that copper nanoclusters (CuNCs) represent a viable fluorescent probe for ascorbic acid. The CuNCs were stabilized by tannic acid and characterized by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis, time-correlated single photon counting and fluorescence spectroscopy. It is found that the fluorescence of CuNCs (at excitation/emission peaks of 355/430 nm) is quenched by ferric ion due to electron-transfer between CuNCs and Fe(III) ions. If ascorbic acid is added, Fe(III) is reduced to Fe(II) and quenching is suppressed. The process is completed within 5 min. Under optimal conditions, a linear relation exists between fluorescence recovery and the concentration of ascorbic acid in the 0.5 μM to 10 μM concentration range. The detection limit is 0.11 μM. The method was applied to the determination of ascorbic acid in (spiked) fruit and vegetables and gave recoveries ranging from 89 to 110 %.
The fluorescence of tannic acid stabilized copper nanoclusters (TA-CuNCs) is quenched by Fe 3+ . Upon addition of ascorbic acid (AA), the redox reaction between Fe 3+ and ascorbic acid converts Fe 3+ to Fe 2+ , and this results in a dramatic fluorescence enhancement of the probe.
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高影响因子
NEW JOURNAL OF CHEMISTRY
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2016
·Vol. 40
·期 4
·3635-3641
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IF 3.277
Yue Wan,Yi Fan Zheng,Hao Yong Yin,Xu Chun Song
In this article, the direct electrochemical behavior of nitrite at a Au nanoparticles (AuNPs)/carbon paper (CP) electrode made using a rapid electrochemical deposition method was investigated. The morphology of the AuNPs on the CP surface was characterized by scanning electron microscopy (SEM). The existence of the Au element was verified by energy dispersive spectroscopy (EDS). The crystal structure of the AuNPs was verified by X-ray diffraction (XRD). Cyclic voltammetry (CV) was applied to evaluate the electrochemical behavior of nitrite oxidation. Under the optimum conditions, the AuNPs/CP electrode exhibited a very strong response to nitrite; the oxidation peak current linearly increased with increasing nitrite in the ranges of 1 μM to 30 μM and 40 μM to 100 μM with correlation coefficients of 0.99883 and 0.99789, and a low detection limit of 0.093 μM. The suggested sensor demonstrated high sensitivity, good reproducibility and good recovery.
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高影响因子
RSC Advances
·
2016
·Vol. 6
·期 25
·20867-20875
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IF 3.289
Yulan Tang,Sufang Liu,Rongbiao Pi,Zhiyi Cheng
A bi-enzyme immobilized microfluidic device was developed for the rapid enzyme inhibition assay by fluorescence detection. The micro-channels of the chip were activated by using an acidic hydrogen peroxide (H2O2) solution, followed by amination with a 3-aminopropyltriethoxysilane/methyltriethoxysilane (APTES/MTES) mixture, and then followed by glutaraldehyde grafting and subsequent covalent protein binding. The analysis was based on the oxidation of L-tyrosine to its tyrosine dimer in the presence of horseradish peroxidase (HRP) and H2O2, which has maximal excitation and emission wavelengths at 320 nm and 416 nm, respectively. H2O2 was an end product under the catalysis of acetylcholinesterase (AChE) and choline oxidase (ChO) immobilized on the inner surface of a microchip, using acetylcholine (ACh) as the enzyme substrate. Fluorescence of the dimer was directly proportional to the concentration of the H2O2 and partly reflected enzyme activity. Thus, AChE inhibition activity was indicated by a decrease in fluorescence signal detected by a microplate reader. The effects of flow velocities, reaction time and buffer systems (pH, types and concentration) on the reaction system were investigated. The utility of the developed microchip was demonstrated for AChE inhibition studies using donepezil as a model compound, which relied upon the generation of a uniform concentration of substrate and a microfluidically created concentration gradient of inhibitor using a single initial inhibitor concentration. The IC50 value of donepezil was determined and found to correlate well with that obtained in the microplate. Accordingly, the microchip can be applied to the screening of enzyme inhibitor and enzymatic reaction kinetics study, which may be useful for drug discovery and screening.
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高影响因子
ELECTROCHIMICA ACTA
·
2016
·
IF 4.803
Junfang Cheng,Ming Zhang,Yuexing Jiang,Lu Zou,Yingpeng Gong,Bo Chi,Jian Pu,Li Jian
Non-aqueous lithium air batteries with high energy density have been regarded to be the most attractive contender in the future energy storage techniques. Herein, the perovskite La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) nanoparticles are studied as the cathode catalyst for non-aqueous lithium air batteries. The results confirm that nanostructured LSCF exhibits admirable electrochemical activity and can effectively reduce the overpotential. Batteries with LSCF catalyst can increase the discharge capacity from 9678 mAh g −1 to 13979 mAh g −1 and improve the cycle stability from 10 cycles to 20 cycles at 200 mA g −1 . The study reveals that the formation and decomposition processes of Li 2 O 2 can be effectively promoted by the introduction of LSCF nanoparticles. The possible catalytic mechanism of LSCF in reducing overpotential is also proposed.
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高影响因子
Scientific Reports
·
2016
·Vol. 6
·期 1
·1-8
·
IF 5.228
Zhou Zhengnan,Li Weiping,He Tianrui,Qian Lei,Tan Guoxin,Ning Chengyun
To enhance the surface bioactivity of titanium (Ti) prostheses, an electroactive polyvinylidene fluoride (PVDF) film was prepared on a Ti substrate to provide a mimetic of the electrical microenvironment, which facilitated the performance of cell functions. The results of cell proliferation and differentiation assays indicated that polarization of the PVDF-Ti (PTi) altered its surface charge, thus inducing adhesion, proliferation and osteogenic differentiation of cells. The polarized PVDF-Ti (PPTi) may therefore find applications in bone regeneration.
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PubMed
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 5
·3003-3011
·
IF 3.108
Songlv Qin,Cheng Chen,Mingjun Cui,Afang Zhang,Haichao Zhao,Liping Wang
In this study, to achieve a compatible and good dispersion of graphene in polyimide matrix, we synthesized an aromatic diamine, aniline trimer, as a polymerizable graphene dispersant. Polyimide/graphene nanocomposites with 0.25–2% mass fraction of graphene were prepared by in situ condensation of pyromellitic dianhydride, 4,4′-oxydianiline, and aniline trimer (AT) functionalized graphene in DMAc, following subsequent thermal imidization at elevated temperatures. UV-vis and Raman spectroscopy verified the π–π interactions between AT and graphene. The microstructure analysis using XRD, SEM, and TEM were performed to investigate the morphology of graphene in the polyimide matrix. The thermal, mechanical, and tribological properties of polyimide/graphene nanocomposites were investigated by TGA, DMA, and friction and wear tests. In view of the ease of preparation and their superior physical properties over neat polyimide, PI/G composites prepared in this study showed promising applications as wear-resistant and self-lubricating materials.
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高影响因子
NEW CARBON MATERIALS
·
2016
·
IF 0.993
Li-le Liu,K P Annamalai,You-sheng Tao
A CuCo 2 S 4 /graphene composite was synthesized using a simple hydrothermal method. The sample was characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption and electrochemical tests. The composite had a hierarchical porous structure with micropores of 0.7-1.2 nm, mesopores of 2-10 nm and a total pore volume of 0.1 cm 3· g −1 , and the CuCo 2 S 4 had a nano-belt structure. As the electrode of a supercapacitor the composite showed a high specific capacitance of 665 F/g at 7.5 mV/s, and excellent rate capability and cycling stability.
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高影响因子
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