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941.
942.
Zhenhua Gu Kongzhai Li Hua Wang Yonggang Wei Dongxia Yan Tianqiang Qiao 《Kinetics and Catalysis》2013,54(3):326-333
A series of mixed oxides Ce1 ? x Fe x O2 was prepared by a hydrothermal method. XRD and Raman spectra were measured to study the structure of the prepared materials. The temperature-programmed reduction was undertaken to estimate reducibility of the oxides. Syngas generation from methane using these materials as oxygen carriers/catalysts via a chemical-looping procedure was investigated in detail. This procedure includes catalytic oxidation and decomposition of methane to produce H2-rich gas at the first step followed by the production of the CO-rich gas by oxidizing the carbon deposited on deactivated catalysts. The results showed that all iron ions were incorporated into the ceria lattice with the formation of oxygen vacancies in the Ce0.9Fe0.1O2 sample, while isolated Fe2O3 particles were distributed on the surface of the Ce0.8Fe0.2O2 sample. TPR measurements and the analysis of the two-step chemical-looping reactions indicated a strong interaction between the Ce and Fe species which accounts for an increased activity of the mixed oxides in the syngas generation compared to that of individual oxides. Among the several samples, the Ce0.8Fe0.2O2 catalyst showed the highest activity for methane partial oxidation due to the synergetic effects caused by the interaction of surface iron entities and Ce-Fe solid solution. In addition, selective oxidation of carbon by oxygen to CO can also be found over this material since gaseous products are formed at the carbon oxidation step with the selectivity to CO reaching 91.2%. Evidence is presented that syngas can be feasibly produced from methane with high selectivity via the chemical-looping procedure over the CeO2-Fe2O3 mixed oxides. 相似文献
943.
Zhongke Yan Jianwei Zhao Lirong Qin Fan Mu Ping Wang Xining Feng 《Mikrochimica acta》2013,180(1-2):145-150
Granular nanowires with a diameter of about 60 nm were fabricated from cuprous oxide (Cu2O) by an electrochemical method using anodic aluminium oxide as the template. A non-enzymatic sensor for hydrogen peroxide (H2O2) was then developed on the basis of a gold electrode modified with Cu2O nanowires and Nafion. The resulting sensor enables the determination of H2O2 with a sensitivity of 745 μA?mM?1?cm?2, over a wide linear range (0.25 μM to 5.0 mM), and with a low detection limit (0.12 μM). The results demonstrate that the use of such granular nanowires provides a promising tool for the design of non-enzymatic chemical sensors. Figure
A non-enzymatic sensor for hydrogen peroxide (H2O2) was developed on the basis of a gold electrode modified with Cu2O nanowires and Nafion. The resulting sensor enables the determination of H2O2 with a sensitivity of 745 μA mM?1 cm?2, over a wide linear range (0.25 μM to 5.0 mM), and with a low detection limit (0.12 μM). The results demonstrate that the use of such granular nanowires provides a promising tool for the design of non-enzymatic chemical sensors 相似文献
944.
Abstract A series of novel Mahkoside A derivatives was synthesized, and their in vitro cytotoxic activities were evaluated against the human cancer cell line Ec‐9706. A Preliminary structure–activity relationship study showed compounds 7 and 8 have obvious cytotoxic activities (IC50: 30.0 and 12.5 µg · mL?1, respectively). 相似文献
945.
The three-component reactions of 4-dimethylamino- or 4-methoxypyridine with acetylenedicarboxylates and arylidene cyanoacetates showed very interesting molecular diversity. The polysubstituted 1,8,9,9a-tetrahydro-4H-1,4-ethanoquinolizines, 2H-pyran-2,3-dicarboxylates, and buta-1,3-diene-1,2,4-tricarboxylates derivatives can be formed in high yields and with good diastereoselectivity depending on the substrates and reaction conditions. 相似文献
946.
Jiaying Yan Yaqing FengXiao Peng Yuanchao LiNuonuo Zhang Xianggao LiBao Zhang 《Tetrahedron letters》2013
Four π-extended, β,β′ aromatic ring fused porphyrins including mono- and opp-dibenzoporphyrins bearing two carboxyl groups at only one fused benzo group were synthesized. The optical results by UV–vis spectroscopy indicate that when compared with the absorption spectra of monobenzoporphyrins, greater light-harvesting capabilities can be realized for opp-dibenzoporphyrins with two benzo group at the opposite β,β′ positions of the porphyrin. The photovoltaic properties of these π-extended porphyrins were examined for the first time and the highest conversion efficiency of 1.62% was realized for opp-dibenzoporphyrin 8a-sensitized solar cell, which is ∼60% higher than that of monobenzoporphyrin 4a based solar cell indicating the effect of an extra aromatic π conjugation on the light-harvesting capabilities of π-extended porphyrins. Subsequent DFT calculation results supported our results obtained in the optical and photovoltaic studies. 相似文献
947.
Li Wei Bin Zhang Yan Zhou Li Qiang Junyan Zhang 《Surface and interface analysis : SIA》2013,45(8):1233-1237
Fluorine‐doped hydrogenated carbon film was grown by chemical vapor deposition technique using CH4 and CF4 as feedstock, with a pulse DC‐bias power supply. The structure of as‐deposited film was characterized by transmission electron microscopy and Raman spectra. The results suggested that the film could be considered as composite thin film with curved graphitic structures embedded in amorphous carbon matrix. The mechanical properties and friction coefficient were tested by TI 950 TriboIndenter and UMT‐2 at humidity of 30%, respectively. The results showed that the film exhibited high hardness (~11.04 GPa), good elasticity recovery(~83%) and ultra‐low coefficient of friction (~0.01). Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
948.
Yaxiao Guo Feifei Xu Lei Meng Wei Tang Yan Xia Yangjie Wu Shusheng Zhang 《Electrophoresis》2013,34(9-10):1312-1318
A new trimethylamine amination polychloromethyl styrene nanolatex (TMAPL) and TMAPL coated capillary column (ccc‐TMAPL) were successfully prepared. The TMAPL coating was characterized with reversed steady EOF values of ca. ?16.8 × 10?5 cm2 V?1 s?1. It was applied to establish open‐tubular (OT) CEC and field‐amplified sample stacking (FASS) OT‐CEC methods for the determination of bromate in tap water. Compared to OT‐CEC, the LOD with FASS‐OT‐CEC was improved from 80 to 8 ng/mL. The developed FASS‐OT‐CEC method was practically used for the analysis of bromate in tap water samples with recoveries ranging from 93.6 to 103.5%. 相似文献
949.
Dong‐Jun Yu Jun Hu Yan Huang Hong‐Bin Shen Yong Qi Zhen‐Min Tang Jing‐Yu Yang 《Journal of computational chemistry》2013,34(11):974-985
Understanding the interactions between proteins and ligands is critical for protein function annotations and drug discovery. We report a new sequence‐based template‐free predictor (TargetATPsite) to identify the Adenosine‐5′‐triphosphate (ATP) binding sites with machine‐learning approaches. Two steps are implemented in TargetATPsite: binding residues and pockets predictions, respectively. To predict the binding residues, a novel image sparse representation technique is proposed to encode residue evolution information treated as the input features. An ensemble classifier constructed based on support vector machines (SVM) from multiple random under‐samplings is used as the prediction model, which is effective for dealing with imbalance phenomenon between the positive and negative training samples. Compared with the existing ATP‐specific sequence‐based predictors, TargetATPsite is featured by the second step of possessing the capability of further identifying the binding pockets from the predicted binding residues through a spatial clustering algorithm. Experimental results on three benchmark datasets demonstrate the efficacy of TargetATPsite. © 2013 Wiley Periodicals, Inc. 相似文献
950.
A water-soluble derivative of chitosan, carboxymethylchitosan (CMCH), was mixed with alkyltrimethylammoniumbromides (CmTAB) and was studied on the adsorption at air/water interface using equilibrium and dynamic surface tension method. The effects of surfactant and polymer concentrations, surfactant chain length, as well as pH of solution were investigated. Addition of the surfactants remarkably promotes the polymer adsorption. Increasing any one of surfactant concentration, surfactant chain length, and pH will facilitate the adsorption of the mixture whereas little effects of polymer concentration were observed. The results are explained in terms of the interaction between CMCH and CmTAB under different conditions. 相似文献