Crystallography of the past and in the future

ABSTRACT

This paper is partly a summary of the book ‘From a grain of salt to the ribosome’ [1 OlovssonI, LiljasA, LidinS. From a grain of salt to the ribosome. Singapore: World Scientific; 2014; ISBN 978-9814623117.[Crossref] , [Google Scholar]], with extension on some points. Sometimes the developments in science may be very rapid and not fully appreciated at all corners of the scientific society. Harry Clary Jones was a well-known chemist at Johns Hopkins University at the turn of the previous century. He had, in his earlier days, spent time in the laboratories of Wilhelm Ostwald in Leipzig, Svante Arrhenius in Stockholm and Jacobus van’t Hoff in Amsterdam. He wrote many papers and twelve books. In 1913 he claimed in a book [2 JonesHC. A new era in chemistry – some of the more important developments in chemistry during the last quarter of a century. New York : D van Nostrand; 1913. [Google Scholar]]:

We do not know the formula of rock salt, or of ice; and we have no reliable means of finding out these simplest matters about solids. Our ignorance of solids is very nearly complete.

It is evident that he was unaware of the very recent developments and the revolution in chemistry that had just taken place with the birth of X-ray crystallography.     

Changes in the properties and composition of cementite in the process of graphitization

Metal Science and Heat Treatment -     

我国台湾电子废物回收利用的法律及实施

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压缩机铸件结构和铸造工艺计算机辅助设计

将计算机辅助设计引入压缩机铸件结构设计及工艺编制中,能够节省时间、提高效率、避免错误。探讨了SolidWorks和Excel等软件在压缩机铸件起模分析、壁厚分析、浇注系统设计等方面的应用。     

关于大学教学问题的理论探讨

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Changes in the potential energy upon the formation of vacancies in the volume and in the cores of crystallite-conjugation regions in cubic polycrystalline metals

Changes in the potential energy of atoms that constitute the nearest neighborhood of vacancies formed in the bulk of d transition and precious cubic metals have been determined. These changes agree with the available first-principles calculations of changes in the potential energy of atoms of the nearest neighborhood of vacancies. In the cores of crystallite-conjugation regions (CCRs) of bcc polycrystalline d transition metals, the formation of vacancies is accompanied by positive changes in the potential energy of atoms of their nearest neighborhood. The absolute magnitudes of these changes are several times less than the changes in the potential energy of atoms of the nearest neighborhood of vacancies in the bulk of these metals, in accordance with the relationship between the enthalpies of formation of vacancies in these regions of polycrystals. The changes in the potential energy of atoms of the nearest neighborhood of vacancies formed in the cores of CCRs of fcc polycrystalline metals are negative because of the split structure of vacancies in the CCR cores of such metals.     

RE与RP技术在模具行业中的应用

介绍了RE与RP两种技术及其特点,在此基础上分析了RE与RP在模具行业中的各种应用情况。     

热核聚变反应堆关键结构件的连接技术进展

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高等教育质量观的发展与中国的选择

高等教育质量20世纪80年代以来备受关注的问题。高等教育质量观的发展经历了合规定性、合需要性、合创新性等三个阶段。高等教育质量的标准，包括适应性、多样性、发展性三个方面。在当前中国高等教育规模扩大、实现大众化的进程中，要全力以赴地提高高等教育质量，通过高等教育自身的多样化改革适应社会的需要。     

Changes in the vibrational energies and interatomic spacings upon the formation of vacancies in the volumes and in the cores of crystallite-conjugation regions of polycrystalline transition metals with cubic lattices

The changes in the vibrational energies and the signs of changes in the interatomic spacings upon the formation of vacancies in the bulk of metal and in the cores of the crystallite-conjugation regions (CCR) in polycrystalline transition metals with bcc and fcc lattices have been determined. The vibrational energy increases upon the formation of a vacancy in the bulk of metal because of a positive “relaxation” contribution to the change in the force constant of the atoms surrounding a vacancy. Positive “relaxation” contributions to the changes in the force constants and, correspondingly, an increase in the vibrational energy of the atoms surrounding a vacancy arise also upon the formation of “split” vacancies (S vacancies) in the cores of CCRs of polycrystalline transition metals with a face-centered cubic lattice. The positive “relaxation” contributions to the changes of the force constant of atoms in the region of localization of S vacancies are caused by a decrease in the interatomic spacings upon their formation, just as upon the formation of conventional vacancies in the bulk of metals. The vibrational energy of the nearest environment of the vacancies that are formed in the CCR cores in the polycrystalline d transition metals with a bcc lattice decreases because of a negative “relaxation” contribution to the change in the force constants. The cores of the high-angle CCRs in polycrystalline d transition metals with a bcc lattice are characterized by a negative internal pressure. Therefore, vacancies with positive relaxation volumes ν_BCC > 0 are formed in them, causing an increase in the interatomic distances in the nearest environment of such vacancies.     

细丝小马鞍型埋弧焊试验及其在汽包管座角焊缝上的应用

为了实现锅炉汽包骑坐式管座角焊缝的机械化、自动化,达到高效、高质量焊接的目的,从设备选型、焊材匹配试验、接头性能试验、工艺参数的确定等方面进行了系统的工艺试验工作。试样结果表明:选用合理的工艺参数,采用细丝马鞍形埋弧焊工艺方法焊接汽包骑座式管座角焊缝,与焊条电弧焊对比,可以较大幅度提高焊接效率,同时更利于保证焊接质量。     

仿形技术在模具设计制造中的应用研究

对RENSCAN200仿形软件在模具设计制造中应用的有关问题进行了研究 ,提出了若干原则和建议 ,并结合实例对软件的特点及使用中存在的问题进行了分析。     

水环境混凝土中钢筋腐蚀及其研究的现状与趋势

本文主要对混凝土中钢筋腐蚀的机理及其测量方法的研究现状进行论述。讨论了钢筋腐蚀与混凝土碳化这两种引起混凝土构件破坏的主要因素、基本机理与特征,简要介绍了各种环境因素,尤其是氯离子与碳化对钢筋腐蚀的影响,介绍了几种钢筋腐蚀的电化学原位快速无损检测方法,分析目前钢筋腐蚀研究存在的问题并提出今后发展方向。     

气缸运动建模及爬行现象判别

由于爬行现象的影响，气缸在低速驱动时不能保持平滑的运动状态，降低了气动系统的控制精度。本文对气动系统进行理论分析，建立系统的动力学方程，引入无量纲参数，并对爬行现象判别式进行理论推导。     

Diffusion of the elements of the Ib and IIb subgroups in silver

Data are given for the diffusion of the elements of the IB and IIB subgroups in single crystals of silver. With the exception of those for mercury in silver, the data indicate that the activation energies for diffusion of the atoms of a given subgroup in the same solvent are similar, but the frequency factors differ. From this, it is concluded that atomic size, provided solid solutions are formed, probably does not affect the activation energy. The relation of the present results to several of the more popular generalizations concerning diffusion is discussed.     

模具制造影响因素分析与对策

详细地分析了模具制造在机加工和电加工以及热处理等加工工艺过程中出现模块变形和裂纹等现象,针对性地提出了降低模块变形几率,防止裂纹产生的有效措施,对提高模具加工质量、延长模具寿命具有一定的现实意义。     

SINTAP标准和BS 7910标准中FAD图评定方法横坐标求解方法的比较及分析

在对结构进行安全评定时,现在国际上通用的两种评定标准为SINTAP标准和英国标准BS 7910.两标准中均包含了FAD(失效评定)图的评定方法,对该方法的横坐标求解进行了比较和分析.在SINTAP标准和标准BS 7910中,FAD图的横坐标均表征了结构趋向于塑性失效破坏的程度,秉承的思路是相同的,但是在具体的求解中两标准却又互不相同.同时,在标准BS 7910中,不同的评定级别,FAD图的横坐标求解也不相同.文中以一个评定的实例进一步加以说明,对于同一结构中的缺陷,由于两标准中考虑因素不同,因此求解得到的横坐标的结果也不相同,而且标准BS 7910中不同评定级别得到的结果也不同,即评定的保守度互不相同.     

厂房通风管道腐蚀原因分析与对策

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