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91.
External uniaxial stress effects on the radiation damage dynamics in a a-Fe b.c.c. structure are studied by means of the computer simulation method. Focused collision chains, defocused ones, and atom-atom collision cascades were simulated. The external uniaxial stresses affect the intervals between a vacancy and an interstitial atom produced due to a collision chain, i.e. changes a dynamical crowdion path. The external stresses change the number of stable point defects and their arrangement in the cascade development region if an atom-atom collision cascade develops in a stressed crystal. The studies of focused collision chains of energies close to the atom displacement threshold energies show that the latter can either increase or decrease due to the external stresses depending on the direction of the effect. 相似文献
92.
M. Sc. Matthias Müller Dr. Magnus R. Buchner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16257-16269
The interplay of metal ions with polysaccharides is important for the immune recognition in the lung. Due to the localization of beryllium associated diseases to the lung, it is likely that beryllium carbohydrate complexes play a vital role for the development of berylliosis. Herein, we present a detailed study on the interaction of Be2+ ions with fructose and glucose as well as simpler biomimetic ligands, which emulate binding motives of saccharides. Through NMR and IR spectroscopy as well as single-crystal X-ray diffraction, complemented by competition reactions we were able to determine a distinctive trend in the binding affinity of these ligands. This suggests that under physiological conditions beryllium ions are only bound irreversibly in glycoproteins or polysaccharides if a quasi ideal tetrahedral environment and κ4-coordination is provided by the respective biomolecule. Furthermore, Lewis acid induced conversions of the ligands and an extreme increase in the Brønstedt acidity of the present OH-groups imply that upon enclosure of Be2+, alterations may be induced by the metal ion in glycoproteins or polysaccharides. In addition the frequent formation of Be-O-heterocycles indicates that multinuclear beryllium compounds might be the actual trigger of berylliosis. This investigation on beryllium coordination chemistry was supplemented by binding studies of selected biomimetic ligands with Al3+, Zn2+, Mg2+, and Li+, which revealed that none of these beryllium related ions was tetrahedrally coordinated under the give conditions. Therefore, studies on the metabolization of beryllium compounds cannot be performed with other hard cations as a substitute for the hazardous Be2+. 相似文献
93.
邓柏权 《核聚变与等离子体物理》2013,33(2):107-112
在文献[1]中,计算了FEB-E 聚变堆PFC 材料内的氚滞留量、堆系统总的氚投料量、启动运行开始阶段的氚坑深度和氚坑时间大小。这里将讨论在ITER 的TBM 氚增殖包层内固体氚增殖剂中的氚如何高效率地被载氚气体带出并且以高效率地提取回收。本部分将进行创新的探索性研究并且提出某些减少氚滞留量和改善氚提取回收效率的新方案,例如:基于氘饱和的海绵效应;第一壁表面建立氘和铍的伴同沉积层;基于在低频外电场作用下载氚气分子和硅酸锂颗粒电极化旋转催化同位素交换速率的增强载氚气提取氚效率“SPB 方法”。 相似文献
94.
Reactions of the beryllium dihalide complexes [BeX2(OEt2)2] (X=Br or I) with N,N,N′,N′‐tetramethylethylenediamine (TMEDA), a series of diazabutadienes, or bis(diphenylphosphino)methylene (DPPM) have yielded the chelated complexes, [BeX2(TMEDA)], [BeX2{(RN=CH)2}] (R=tBu, mesityl (Mes), 2,6‐diethylphenyl (Dep) or 2,6‐diisopropylphenyl (Dip)), and the non‐chelated system, [BeI2(κ1‐P‐DPPM)2]. Reactions of lithium or potassium salts of a variety of β‐diketiminates have given both three‐coordinate complexes, [{HC(RCNAr)2}BeX] (R=H or Me; Ar=Mes, Dep or Dip; X=Br or I); and four‐coordinate systems, [{HC(MeCNPh)2}BeBr(OEt2)] and [{HC(MeCNDip)(MeCNC2H4NMe2}BeI]. Alkali metal salts of ketiminate, guanidinate, boryl/phosphinosilyl amide, or terphenyl ligands, lead to dimeric [{BeI{μ‐[(OCMe)(DipNCMe)]CH}}2], and monomeric [{iPr2NC(NMes)2}BeI(OEt2)], [κ2‐N,P‐{(HCNDip)2B}(PPh2SiMe2)NBeI(OEt2)] and [{C6H3Ph2‐2,6}BeBr(OEt2)], respectively. Compound [{HC(MeCNPh)2}BeBr(OEt2)] undergoes a Schlenk redistribution reaction in solution, affording the homoleptic complex, [{HC(MeCNPh)2}2Be]. The majority of the prepared complexes have been characterized by X‐ray crystallography and multi‐nuclear NMR spectroscopy. The structures and stability of the complexes are discussed, as is their potential for use as precursors in poorly developed low oxidation state beryllium chemistry. 相似文献
95.
Phonon frequencies in beryllium along the principal symmetry directions have been determined by means of the slow neutron
inelastic scattering technique. The data are analysed in terms of a six-neighbour force constant model and the force constants
are evaluated. It is concluded that strong tensor forces are present in beryllium and the importance of this finding to basic
theories of lattice dynamics is pointed out. 相似文献
96.
静电陀螺转子用铍材的基本要求 总被引:5,自引:0,他引:5
通过对静电陀螺仪空心转子的功能特性分析,确认铍材是用作空心转子材料的唯一选择。通过对目前国内外铍材的现状的分析,提出空心转子用铍材的主要技术要求,该要求也适用于实心小球铍材。 相似文献
97.
Carbon Monoxide Bonding With BeO and BeCO3: Surprisingly High CO Stretching Frequency of OCBeCO3 下载免费PDF全文
Prof. Mohua Chen Qingnan Zhang Prof. Mingfei Zhou Dr. Diego M. Andrada Prof. Gernot Frenking 《Angewandte Chemie (International ed. in English)》2015,54(1):124-128
The complexes OCBeCO3 and COBeCO3 have been isolated in a low‐temperature neon matrix. The more stable isomer OCBeCO3 has a very high C? O stretching mode of 2263 cm?1, which is blue‐shifted by 122 cm?1 with respect to free CO and 79 cm?1 higher than in OCBeO. Bonding analysis of the complexes shows that OCBeO has a stronger OC? BeY bond than OCBeCO3 because it encounters stronger π backdonation. The isomers COBeCO3 and COBeO exhibit red‐shifted C? O stretching modes with respect to free CO. The inverse change of C? O stretching frequency in OC? BeY and CO? BeY is explained with the reversed polarization of the σ and π bonds in CO. 相似文献
98.
Tiago F. T. Cerqueira Stephane Pailhes Regis Debord Valentina M. Giordano Romain Viennois Jingming Shi Silvana Botti Miguel A. L. Marques 《ChemInform》2016,47(34):no-no
High‐throughput DFT calculations are used to predict the thermodynamic stability of ternary type I Si clathrates. 相似文献
99.
The electronic and magnetic states of beryllium monoxide BeO with lattice vacancies were investigated by the PAW-VASP ab initio band structure method. In the presence of defects in the beryllium sublattice, vacancy-induced magnetic moments arise on the oxygen atoms, and the nonstoichiometric Be1?x O passes to the magnetic half-metal state. 相似文献
100.