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991.
Ji-Dong Lou 《合成通讯》2013,43(11-12):1841-1845
A new reagent, chromic acid adsorbed on kieselguhr, suitable for the oxidation of primary alcohols to the corresponding aldehydes is described. 相似文献
992.
New one‐pot three‐component reactions employing aldehydes, triphenylphosphite, and N‐[(phenylamino)carbonyl]glycine ethyl ester in refluxing xylene readily afford N‐phenyl α‐aminophosphonates in low to moderate yields. 相似文献
993.
A 3D structured composite of carbon nanofibers@MnO2 on copper foil is reported here as a binder free anode of lithium ion batteries, with high capacity, fast charge/discharge rate and good stability. Carbon nanofiber yarns were synthesized directly over copper foil through a floating catalyst method. The growth of carbon nanofiber yarns was significantly enhanced by mechanical polishing of the copper foils, which can be attributed to the increased surface roughness and surface area of the copper foils. MnO2 was then grown over carbon nanofibers through spontaneous reduction of potassium permanganate by the carbon nanofibers. The obtained composites of carbon nanofibers@MnO2 over copper foil were tested as an anode in lithium ion batteries and they show superior electrochemical performance. The initial reversible capacity of carbon nanofibers@MnO2 reaches up to around 998 mAh g-1 at a rate of 60 mmA g-1 based on the mass of carbon nanofibers and MnO2 . The carbon nanofibers@MnO2 electrodes could deliver a capacity of 630 mAh g-1 at the beginning and maintain a capacity of 440 mmAh g-1 after 105 cycles at a rate of 600 mA g-1 . The high initial capacity can be attributed to the presence of porous carbon nanofiber yarns which have good electrical conductivity and the MnO2 thin film which makes the entire materials electrochemically active. The high cyclic stability of carbon nanofibers@MnO2 can be ascribed to the MnO2 thin film which can accommodate the volume expansion and shrinking during charge and discharge and the good contact of carbon nanofibers with MnO2 and copper foil. 相似文献
994.
995.
A dispersive liquid–liquid microextraction procedure coupled with GC‐MS is described for preconcentration and determination of banned aromatic amines from textile samples. Experimental conditions affecting the microextraction procedure were optimized. A mixture of 30 μL chlorobenzene (extraction solvent) and 800 μL ACN (disperser solvent), 5 min extraction time, and 5 mL aqueous sample volume were chosen for the best extraction efficiency by the proposed procedure. Satisfactory linearity (with correlation coefficients >0.9962) and repeatability (<9.78%) were obtained for all 20 aromatic amines; detection limits attained were much lower than the standardized liquid–liquid method. The proposed method has advantages of being quicker and easier to operate, and lower consumption of organic solvent. 相似文献
996.
Fengliu Lou Haitao Zhou Fride Vullum-Bruer Trung Dung Tran De Chen 《Journal of Energy Chemistry》2013,22(1):78-86
A 3D structured composite of carbon nanofibers@MnO2 on copper foil is reported here as a binder free anode of lithium ion batteries, with high capacity, fast charge/discharge rate and good stability. Carbon nanofiber yarns were synthesized directly over copper foil through a floating catalyst method. The growth of carbon nanofiber yarns was significantly enhanced by mechanical polishing of the copper foils, which can be attributed to the increased surface roughness and surface area of the copper foils. MnO2 was then grown over carbon nanofibers through spontaneous reduction of potassium permanganate by the carbon nanofibers. The obtained composites of carbon nanofibers@MnO2 over copper foil were tested as an anode in lithium ion batteries and they show superior electrochemical performance. The initial reversible capacity of carbon nanofibers@MnO2 reaches up to around 998 mAh·g?1 at a rate of 60 mmA·g?1 based on the mass of carbon nanofibers and MnO2. The carbon nanofibers@MnO2 electrodes could deliver a capacity of 630 mAh·g?1 at the beginning and maintain a capacity of 440 mmAh·g?1 after 105 cycles at a rate of 600 mA·g?1. The high initial capacity can be attributed to the presence of porous carbon nanofiber yarns which have good electrical conductivity and the MnO2 thin film which makes the entire materials electrochemically active. The high cyclic stability of carbon nanofibers@MnO2 can be ascribed to the MnO2 thin film which can accommodate the volume expansion and shrinking during charge and discharge and the good contact of carbon nanofibers with MnO2 and copper foil. 相似文献
997.
Weiren Cheng Xue Feng Lu Deyan Luan Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2020,59(41):18234-18239
Developing noble‐metal‐free bifunctional oxygen electrocatalysts is of great significance for energy conversion and storage systems. Herein, we have developed a transformation method for growing NiMn‐based bimetal–organic framework (NiMn‐MOF) nanosheets on multi‐channel carbon fibers (MCCF) as a bifunctional oxygen electrocatalyst. Owing to the desired components and architecture, the MCCF/NiMn‐MOFs manifest comparable electrocatalytic performance towards oxygen reduction reaction (ORR) with the commercial Pt/C electrocatalyst and superior performance towards oxygen evolution reaction (OER) to the benchmark RuO2 electrocatalyst. X‐ray absorption fine structure (XAFS) spectroscopy and density functional theory (DFT) calculations reveal that the strong synergetic effect of adjacent Ni and Mn nodes within MCCF/NiMn‐MOFs effectively promotes the thermodynamic formation of key *O and *OOH intermediates over active NiO6 centers towards fast ORR and OER kinetics. 相似文献
998.
Xiao-Yu Liu Xiao-Ling Wang Tao Shen Dong-Mei Ren Hong-Xiang Lou 《Natural product research》2020,34(15):2179-2185
AbstractOne new pentanortriterpenoid, 23,24,25,26,27-pentanorlanost-7,9(11)-dien-3β,22-diol (1), one new triterpenoid, lanost-8-en-3β,22S,23S-triol (2), together with the known triterpenoid, 23,24,25,26,27-pentanorlanost-8-en-3β,22-diol (3), were obtained from culture of the fungus Diplodia cupressi associated with the moss Polytrichum commune. The structures of the new compounds were elucidated by extensive spectroscopic techniques including HR-ESIMS and 1?D and 2?D NMR experiments. The cytotoxicity of these compounds against human cancer cell lines (A549, Hep G2, Hepa 1c1c7, and Hela) was evaluated and compound 2 exhibited weak inhibitory activity with IC50 value of 35.0?±?2.3?μM against the proliferation of the Hepa 1c1c7 cells. 相似文献
999.
1000.
Xue Feng Lu Bao Yu Xia Shuang‐Quan Zang Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2020,59(12):4634-4650
In view of the clean and sustainable energy, metal–organic frameworks (MOFs) based materials, including pristine MOFs, MOF composites, and their derivatives are emerging as unique electrocatalysts for oxygen reduction reaction (ORR). Thanks to their tunable compositions and diverse structures, efficient MOF‐based materials provide new opportunities to accelerate the sluggish ORR at the cathode in fuel cells and metal–air batteries. This Minireview first provides some introduction of ORR and MOFs, followed by the classification of MOF‐based electrocatalysts towards ORR. Recent breakthroughs in engineering MOF‐based ORR electrocatalysts are highlighted with an emphasis on synthesis strategy, component, morphology, structure, electrocatalytic performance, and reaction mechanism. Finally, some current challenges and future perspectives for MOF‐based ORR electrocatalysts are also discussed. 相似文献