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861.
本文将元素变量(φ*和nWS)和MAEAM相结合,从原子尺度上对10种fcc金属Cu,Ag,Au,Ni,Pd,Pt,Rh,Al,Ir和Pb的38个不同晶面的表面能进行模拟计算及各向异性分析. 结果表明,fcc金属的密排面(111)的表面能最小,则该晶粒取向优先生长,与实验结果和第一原理的LMTO-ASA计算结果一致;各个晶面的表面能均随着其他晶面与(111)晶面的夹角cosθ(hkl)的增长而呈线性
关键词:
FCC金属
MAEAM
表面能
表面偏析 相似文献
862.
1分区均匀介质静电场求解方法的回顾分区均匀介质静电场的求解是电磁学课程中比较有难度和有特色的内容.有两种情形的分区均匀介质静电场问题可以解析求解:一种是介质-介质界面与撤去电介质时的电场线平行;另一种是介质-介质界面与撤去电介质时的电场线垂直.它是唯一性定理应用的一个生动的实例,并且涉及到静 相似文献
863.
古代玻璃样品表面因素对便携式X射线荧光定量分析的影响 总被引:2,自引:0,他引:2
便携式X射线荧光光谱分析技术(PXRF)是一种表面分析技术,样品表面状况对定量分析结果有很大的影响.本文采用PXRF对新疆、广西、江苏等地出土的Na2O-CaO-SiO2,K2O-SiO2和PbO-BaO-SiO2体系古代玻璃的风化表面与内部进行了定量分析,指出了主要助熔剂的含量在不同部位的变化.另外,还研究了样品与参... 相似文献
864.
865.
Element characteristics of nephrite minerals were determined by glow discharge mass spectrometry (GD‐MS) through surface adherence method. To solve the conductivity problem of non‐conductive nephrite samples, high purity indium pin (>99.9999%) was used as discharge host. During the preparation procedure, a small piece of nephrite sample was ground into powder (about 200 meshes), and then the sample powder was coated on the surface of indium pin to form a rod sample. Typical elements of nephrite minerals were analyzed by GD‐MS, and the relative standard deviations showed that the stability and reproducibility of this method were good. Meanwhile, four nephrite samples from two different deposits were further studied by this method. The GD‐MS results of major elements and trace elements revealed that typical elements of the nephrite minerals from same deposit were similar, and those from different deposits exhibited significant difference. In addition, results of external‐beam proton induced X‐ray emission (PIXE) were consistent with the result of GD‐MS determination. The present approach had been proven to be simple, efficient to perform the rapid screening and multi‐element semi‐quantitative analysis of nephrite samples. 相似文献
866.
Azomethine ylide formed from glycine methyl ester and cinnamaldehyde adds to N-phenylmaleimide to form pyrrolidine derivative, further treatment of which with cinnamaldehyde and N-phenylmaleimide affords the second [2 + 3] cycloaddition adduct, a pyrrolizine derivative with two styrenyl groups at the 3,5-positions. Addition of ICl to the pyrrolizine derivative results in the 6-exo-trig cyclization of the styrenyl groups to form a cycl[3.2.2]azine derivative. The reactions are highly stereoselective affording 11 chiral carbons in three steps. The structure of the cycl[3.2.2]azine derivative was determined by single-crystal X-ray analysis. 相似文献
867.
Single?Clayered graphene, emerging as a true two?Cdimensional nanomaterial, has tremendous potential for electrochemical catalysis and biosensing as a novel electrode material. Considering the excellent properties of graphene, such as large surface?Cto?Cvolume ratio, high conductivity and electron mobility at room temperature, low energy dynamics of electrons with atomic thickness, robust mechanical and flexibility, we give a general view of recent advances in electrochemical sensors based on graphene. We are highlighting here important applications of graphene and graphene nanocomposites, and the assay strategies in electrochemical sensors for DNA, proteins, neurotransmitters, phytohormones, pollutants, metal ions, gases, hydrogen peroxide, and in medical, enzymatic and immunosensors. Graphical Abstract
Graphene, a recent star carbon nanomaterial with lots of excellent properties, has caused increasing interests on the development of new-types graphene-based electrochemical sensors including DNA and protein sensor, enzyme based sensor, immunosensor, neurotransmitter sensor, medicine sensor, phytohormone sensor, pollutants sensor, metals ion sensor, gas sensor, and H2O2 sensor 相似文献
868.
Xiuyun Yang Yanyan ChengFei Zhao Yunhui LiYuanli Ding Yongjiu LiangFengjiao Gan Dewen Dong 《Tetrahedron》2011,67(43):8343-8347
A facile and efficient synthesis of fully substituted pyridin-2(1H)-ones has been developed by the reaction of readily available α-oxoketene-S,S-acetals with malononitrile in the presence of sodium methoxide in methanol under reflux. 相似文献
869.
Microfluidic systems could, in principle, enable high-throughput breeding and screening of microbial strains for industrial applications, but parallel and scalable culture and detection chips are needed before complete microbial selection systems can be integrated and tested. Here we demonstrate a scalable multi-channel chip that is capable of bacterial suspension culture. The key invention is a multi-layered chip design, which enables a single set of control channels to function as serial peristaltic pumps to drive parallel culture chamber loops. Such design leads to scalability of the culture chip. We demonstrate that E. coli growth in the chip is equivalent or superior to conventional suspension culture on shaking beds. The chip could also be used for suspension culture of other microbes such as Bacillus subtilis, Pseudomonas stutzeri, and Zymomonas mobilis, indicating its general applicability for bacterial suspension culture. 相似文献
870.
Yige?WangEmail author Yu?Feng Hongsheng?Zhao Quanying?Gan Xiaoyan?Yu 《Journal of Sol-Gel Science and Technology》2011,58(3):711-715
In this work, we report the luminescent organic–inorganic hybrid materials prepared by hydrolysis and condensation of sylilated
β-diketone under acid conditions in the presence of carboxyl-functionalized ionic liquid in which Eu3+ ions are coordinated to the oxygen atoms of carboxylate groups from the ionic liquids. The obtained materials were characterized
with FT-IR, TG and photoluminescence spectroscopy. FT-IR spectra imply that Eu3+ ions are still coordinated to the ionic liquid in the hybrid materials. Excitation and emission spectra demonstrate that
the energy transfer occurs from the β-diketone molecules covalently bonded with silica to Eu3+ ions. The Eu3+ (5D0) quantum efficiency value of the hybrid materials has been estimated based on the emission spectrum and the value of lifetime.
A large value of ratio (16.44) between the intensities of the 5D0→7F2 and 5D0→7F1 transition and high value of 5D0 quantum efficiency (51.01%) are obtained. 相似文献