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With recent breakthroughs in camera and image processing technologies single-particle electron cryo-microscopy(CryoEM) has suddenly gained the attention of structural biologists as a powerful tool able to solve the atomic structures of biological complexes and assemblies. Compared with x-ray crystallography, Cryo EM can be applied to partially flexible structures in solution and without the necessity of crystallization, which is especially important for large complexes and assemblies. This review briefly explains several key bottlenecks for atomic resolution Cryo EM, and describes the corresponding solutions for these bottlenecks based on the recent technical advancements. The review also aims to provide an overview about the technical differences between its applications in biology and those in material science. 相似文献
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The crystal structure of the minor phase, named superstructure II, existing in multiferroic compound BiMnO3 has been studied by electron diffraction and high-resolution transmission electron microscopy. Domains of major and minor phases coexisting in BiMnO3 were observed in high-resolution electron microscope images. The unit cell of minor phase was determined to be triclinic with the size 4×4×4 times as large as the distorted perovskite subcell. The [111] and [101] projected structure maps of the minor phase have been derived from the corresponding images by means of the image processing. A possible rough three-dimensional (3D) structure model was proposed based on the 3D structural information extracted from the two projected structure maps. Since there is no inversion centre in the proposed model, the minor phase may contribute to the ferroelectric property of BiMnO3. 相似文献
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The program package VEC (Visual computing in Electron
Crystallography) has been revised such that (i) a program
converting one-line symbols to two-line symbols of (3+1)-dimensional
superspace groups has been incorporated into VEC so that the
latter can interpret both kinds of symbols; (ii) a bug in
calculating structure factors of one-dimensionally incommensurate
modulated crystals has been fixed. The correction has been verified
by successfully matching the experimental electron microscopy image
of an incommensurate crystal with a series of simulated images. The
precompiled revised version of VEC and relevant materials are
available on the Web at http://cryst.iphy.ac.cn. 相似文献
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2020年1月25日大年初一,注定不是一个寻常的日子,中午打开手机看到了李老师去世的消息,来的突然,顿感悲痛。回想与李老师相处的点点滴滴,她的音容笑貌似乎仍在眼前,只能感叹时间过得太快……我于2005年9月入学中国科学院物理研究所,成为李老师的博士研究生。之所以成为李老师的学生,一是出于对电子显微学的喜爱,二是希望能做一些理论方面的工作。 相似文献
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数表问题历来是竞赛的热点.这类问题题型新颖,信息性强,往往与数列整合在一起,可以较好地考查学生的观察问题、处理数据、阅读理解、获取信息、归纳推理等能力.本文谈谈如何求解这类题的一些方法.1利用特殊数列沟通纵横联系数表中的横与列都可以看作数列.如果题目已知某项或某列是等差或等比数列,应沟通数表中各数的纵横联系,利用特殊数列的通项公式、求和公式等来求解.例1(南充市2004年高三模拟题)n2个正数排成n行n列(如表1),其中每行数都成等差数列,每列数都成等比数列,且所有公比相同.已知a24=1,a42=18,a43=136,求∑k=n1akk.a11a12a13a14… 相似文献
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利用脉冲高能量密度等离子体技术在室温条件下在45#钢基材表面沉积了高硬度耐腐蚀(Ti, Al)N薄膜. 利用扫描电子显微镜、X射线衍射、X射线光电子能谱、俄歇电子能谱分析了薄膜的显微组织.利用纳米压痕仪测试了薄膜的纳米硬度.测试了薄膜在05mol/L H2SO4水溶液中的耐蚀性. 测试结果表明:薄膜主要组成相为(Ti, Al)N,同时含有少量的AlN,薄膜的纳米硬度高达26 GPa,薄膜具有良好的耐蚀性,与1Cr18Ni9Ti奥氏体不锈钢相比,耐蚀性提高了一个数量级.
关键词:
脉冲高能量密度等离子体
薄膜
纳米硬度
耐蚀性 相似文献
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一氧化碳释放剂(CORM)为CO在人体的精准输送提供了便利。为提高CORM的稳定性,以[Fe(CO)4I2]为前驱体,通过与二齿膦配体dppe、dppp、PNP(dppe=1,2-双(二苯基膦酰)乙烷,dppp=1,3-双(二苯基膦酰)丙烷,PNP=N-环己基-N-(二苯基膦酰)-1,1-二苯基膦胺(Ph2PN(cyclohexyl)PPh2)的配位取代反应制得了二齿膦二羰基铁化合物1~3,并利用FT-IR、UV-Vis、NMR、元素分析、单晶X射线衍射(化合物2、3)进行表征。通过红外光谱法研究了化合物1~3的降解释放CO性能,以评估其作为CORM的潜能。在二甲亚砜溶剂中、黑暗条件下这些化合物表现出良好稳定性;但在可见光(红光、绿光、蓝光)照射下,均可降解释放CO,其降解速率与光源的能量和化合物的结构有关。此外,在蓝光和绿光照射下,发现化合物1和2可从顺式构型向反式构型发生转化,而红光下因能量不足未见构型转化。 相似文献
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