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991.
Ultrathin Co3S4 Nanosheets that Synergistically Engineer Spin States and Exposed Polyhedra that Promote Water Oxidation under Neutral Conditions 下载免费PDF全文
Youwen Liu Dr. Chong Xiao Mengjie Lyu Dr. Yue Lin Weizheng Cai Pengcheng Huang Prof. Wei Tong Prof. Youming Zou Prof. Yi Xie 《Angewandte Chemie (International ed. in English)》2015,54(38):11231-11235
Development of efficient and affordable electrocatalysts in neutral solutions is paramount importance for the renewable energy. Herein, we report that the oxygen evolution reaction (OER) performance of Co3S4 under neutral conditions can be enhanced by exposed octahedral planes and self‐adapted spin states in atomically thin nanosheets. A HAADF image clearly confirmed that the active octahedra with Jahn–Teller distortions were exposed exclusively. Most importantly, in the atomically thin nanosheets, the spin states of Co3+ in the octahedral self‐adapt from low‐spin to high‐spin states. As a result, the synergistic effect endow the Co3S4 nanosheets with superior OER performance, with exceptional low onset overpotentials of circa 0.31 V in neutral solutions, which is state‐of‐the‐art among inorganic non‐noble metal compounds. 相似文献
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Tian Lan Huichang Bi Suowen Xu Kang Le Zhiyong Xie Yiwei Liu Heqing Huang 《Biomedical chromatography : BMC》2010,24(10):1075-1083
Sphingosine kinase (SphK) is a key enzyme in modulating the levels of sphingosine 1‐phosphate (S1P) as well as an important enzyme in numerous biological responses. Using C17‐sphingosine as a substrate, we established a rapid, sensitive and highly efficient method for determination of SphK activity by analyzing the product C17‐sphingosine 1‐phosphate (C17‐S1P) using liquid chromatography–tandem mass spectrometry. The standard curve for C17‐S1P was linear over a wide range (10–1000 ng/mL) with correlation coefficient (r2) greater than 0.999. The lower limit of quantification for C17‐S1P was 10 ng/mL. The Km values for C17‐sphingosine and ATP were determined to be 28.17 and 188.5 mM, respectively. More importantly, the SphK activity dramatically increased in cultured HEK 293 cells expressing wild‐type SphK1 as well as cells treated with tumor necrosis factor‐a, a sphingosine kinase activator. In contrast, the SphK activity decreased in cultured HEK 293 cells treated with dimethylsphngosine, a sphingosine kinase inhibitor. In conclusion, this method was sensitive and rapid in the determination of SphK acitivity, providing striking utilities in exploring the sphingosine kinase signaling pathway and screening active compounds targeting SphK activity. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Al-doped MnO2 as electrode materials for supercapacitor were synthesized by high-energy ball milling. The morphologies and structures of
prepared MnO2 were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electrochemical
investigation indicated that doped MnO2 presented preferable electrochemical performances than un-doped MnO2, but there were obvious capacitance decline in the first several dozen of cycles for all doped MnO2 samples. The Al0.05/Mn0.95O2 electrode, especially, showed the largest capacitance among all prepared MnO2 samples. Excellent conductivity of Al in doped MnO2 was considered to be responsible for enhanced electrochemical performances of doped MnO2. 相似文献
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The application of focused ion beam (FIB) machining in several technologies aimed at microstructure fabrication is presented. These emergent applications include the production of micromilling tools for machining of metals and the production of microsurgical tools. An example of the use of microsurgical manipulators in a circulatory system measurement is presented. The steps needed to transform the laboratory fabrication of these tools and manipulators into a routine FIB production process are discussed. The ion milling of three-dimensional cavities by the exact solution of a mathematical model of the FIB deflection is demonstrated. A good agreement between the model calculation and the ion beam control has been obtained for parabolic and cosine cross-section features with planes of symmetry. 相似文献
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Mei symmetry and Mei conserved quantity of nonholonomic systems with unilateral Chetaev type in Nielsen style 下载免费PDF全文
This paper studies the Mei symmetry and Mei conserved quantity for nonholonomic systems of unilateral Chetaev type in Nielsen style. The differential equations of motion of the system above are established. The definition and the criteria of Mei symmetry, loosely Mei symmetry, strictly Mei symmetry for the system are given in this paper. The existence condition and the expression of Mei conserved quantity are deduced directly by using Mei symmetry. An example is given to illustrate the application of the results. 相似文献