岩体动力变形破坏的层次特性(英文)

岩体具有复杂的内部结构,内部结构对于岩土的力学性质具有决定性的影响.文章从岩体结构层次的角度研究了岩体的动力变形与破坏过程,在松弛模型的框架内研究了变形破坏的空间尺度与应变率之间的关系.讨论了裂纹传播速度与荷载强度之间的关系,研究了岩体变形破坏的层次特性.最后从岩体结构层次角度研究了岩体的破坏准则.研究表明:岩体的动力变形与破坏具有层次特性,这一层次特性依赖于外载的空间与时间特性、岩体的结构层次和岩体变形与破坏过程速度的有限性.时间准则与极限变形准则可以较好地描述岩体的动力破坏.     

我们生活在一碗汤面里吗?——光和电子的统一与起源

光和物质的起源是物理学中一个非常基本的问题,对该问题的探究贯穿了整个物理学的发展史.文章首先从最早的光微粒说和波动理论讲起,详细介绍了为什么光的波动学说可以成功地解释光的折射和干涉现象.然后以光的横波特性为基础,论述了是否存在可以承载光传播的媒介物质.通过对电荷和磁场的研究,人们认识到光是一种电磁波.最后从凝聚态物理学的演生原理出发,作者论述了弦网液体中的弦密度波对应于电磁波,弦的端点对应于电子,进而给出了光和电子起源的统一解释.     

Synthesis,crystal structure,spectral and electrochemical characterization,DNA binding and free radical scavenging studies of ferrocene-based thioureas

Abstract

Thioureas are important building blocks in medicinal chemistry; ferrocenes as highly hydrophobic moieties induce very interesting qualities in medicinal compounds. In this article, we have synthesized four ferrocene incorporated N,N′-disubstituted benzoyl thioureas (3a–3d) with general formula C₅H₅-Fe-C₅H₄C₆H₄Cl-NH-CS-NH-CO-C₆H₄(H/CH₃). Molecular structures of these compounds were characterized in solid and solution phases. In solution molecular structures were established by ¹H and ¹³C NMR and cyclic voltammetry. In the solid state their structures were characterized by elemental analyses and FTIR spectroscopy. Two of the compounds (3a and 3d) had also been structurally determined by single crystal X-ray diffraction analysis. The electrochemical characterization showed a reversible process with one electron transfer from Fe(II) to Fe(III). The single crystal analysis showed strong intermolecular non-covalent interactions in these compounds. Molecular structures of these compounds were also studied by density functional theory (DFT) calculation . DFT studies showed good correlation between calculated parameters and experimental results of solution phase and solid state characterizations. Compounds 3a–3d were evaluated for DNA interaction and antioxidant activity. These compounds interact with DNA via electrostatic forces and liberate significant binding constants and energies. Antioxidant potential –CSNH and –CONH groups induce same level of free radical scavenging ability in these compounds.     

激励小尺度模式在湍流圆管射流中的应用

采用非涡黏性的激励小尺度（Stimulated Small Scale)模式对空间发展的轴对称湍流圆管射流进行了大涡模拟。以雷诺数为10000的流动为例,考证了激励小尺度模式在自由剪切流模拟中的可行性,描述了湍流强度、雷诺应力和湍流耗散量的变化,同时与标准的Smagorinsky涡黏性模式的计算结果进行了比较。数值结果显示,激励小尺度模式能够更为合理地描述湍流的耗散特性和能量传输特性,从而较为准确地展示出空间发展射流中由于流动不稳定而出现的旋涡产生、发展、破碎及合并等过程。     

Synthesis and Structural Characterization of a New Cadmium(Ⅱ) Complex Bridged by Endo-norbornene-cis-5,6-dicarboxylic Acid

A polynuclear complex [Cd(endc)(H2O)]n·nH2O (endc = endo-norbomene-cis5,6-dicarboxylate anion) has been synthesized by the hydrothermal reaction of cadmium nitrate tetrahydrate with endo-norbomene-cis-5,6-dicarboxylic acid in 1:1 molar ratio,and structurally characterized by single-crystal X-ray diffraction.It crystallizes in monoclinic,space group P21/c with a = 1.16471(7),b = 0.95334(7),c = 0.91109(9) nm,Z = 4,V= 1.01035(14)nm3,Dc.= 2.160 g/cm3,μ= 2.172 mm-1,F(000) = 648,R =0.0302 and wR = 0.0752.According to structural analysis,each Cd(Ⅱ) ion is coordinated to six O atoms from three endc anions and one water molecule,giving a distorted octahedral geometry.Two- dimensional layer arrangement of the title complex is constructed from the bridging nature of endc.It is worth notice that adjacent two-dimensional layers are joined together to form a three-dimensional supramolecular framework via intermolecular hydrogen bonding interactions.     

第一讲信息的产生与获得(上)

信息是物质运动本身的属性．通过大自然发出的信息理解宇宙，发现自然规律，是科学永恒的主题．现代信息科学技术使人们能够超越感觉器官和神经系统的生理极限，以前所未有的方式获取自然的信息．文章回溯了人类获取自然信息的历史过程及其不同发展阶段的科学内涵与技术特征，阐述了信息对科学发展的决定性意义，概括地介绍了人类探寻科学信息的某些前沿活动，讨论了它们对探索者的启示．     

Preparation and Optical Properties of SiO<Subscript>2</Subscript> Sol–Gel Made Glass Colored with Carminic Acid

SiO₂ based films and bulk samples, containing dispersed carminic acid molecules, were prepared using the traditional sol–gel process. The precursor material was a mixture of water, TEOS, ethanol and carminic acid, the components were added at ratios known to provide material with good structure. The carminic acid in powder form was introduced in the solution. Films and bulk samples with intense red color were obtained. The optical absorption and emission spectra of this material contain a number of visible and UV bands corresponding to transitions between discrete electronic energy levels. It is found that optical and thermal stability of the coloration produced by the carminic acid is enhanced when the acid molecules are embedded into the SiO₂ matrix, especially in bulk samples. The energy spectrum of the carminic molecule was obtained from a quantum mechanical model based on the modified FEMO approach. This model provides a good agreement with the experiment without any adjustable parameters.     

Activity of carboxypeptidase a bound to a modified cellulosic matrix

Carboxypeptidase A immobilized on acid chloride of oxidized cellulose showed the following features: (a) as indicated by the linearity of reaction kinetics, the immobilized enzyme action is not diffusion controlled; (b) greater flow rates are achievable with less clogging during continual usage since the enzyme is attached to a porous screen; (c) ease of handling; and (d) no apparent electrostatic interaction with the support material that is uncharged. The immobilized enzyme retained 60% of the original activity. The half-life of free enzyme was only 20 min, whereas for immobilized enzyme it was enhanced up to 2 h 48 min. It could be recovered and repeatedly used.     

SYNTHESIS AND CHARACTERIZATION OF BIS-[2-[[(2-ALKOXYPHENYL)IMINO]METHYL]-PHENOLATO-O,N,O]NICKEL(II)COMPLEXES AND THEIR NORBORNENE POLYMERIZATION

A series of salicylaldimines,synthesized in high yield via microwave-assisted condensation of salicylaldehyde and 2-alkoxyaniline were allowed to react with nickel chloride to form six-coordinated nickel complexes.These nickel complexes were carefully characterized,and the solid structure of la was elucidated by X-Ray diffraction.Activated with MAO,the nickel complexes showed good activity for homopolymerization of norbornene.Reaction parameters,such as the ratio of nickel precursor to MAO,monomer concentration,reaction time and the reaction temperature,as well as the nature of the ligands were found to have significant effects on the catalytic activity and some properties of the resulting polynorbornene.