左消半群M与幂单半群B的Schǔzenberger积

本文讨论了每个元都有幂等元作为右单位元的左消半群与幂单半群N的Schuzenberger积M◇N的ρ类，证明了这种半群M与N的Schuzenberger积M◇N的ρ类是右E一半适合半群和弱E-headged半群．     

2+1维de-Sitter时空中光线的轨迹

通过求解2+1维de-Sitter时空中零测地线方程得到光线的轨迹方程,对轨迹方程进行分析发现其不存在封闭的轨迹解.     

Comparison of shear banding in BMGs due to thermal-softening and free volume creation

This paper reports a comparative study of shear banding in BMGs resulting from thermal softening and free volume creation. Firstly, the effects of thermal softening and free volume creation on shear instability are discussed. It is known that thermal softening governs thermal shear banding, hence it is essentially energy related. However, compound free volume creation is the key factor to the other instability, though void-induced softening seems to be the counterpart of thermal softening. So, the driving force for shear instability owing to free volume creation is very different from the thermally assisted one. In particular, long wave perturbations are always unstable owing to compound free volume creation. Therefore, the shear instability resulting from coupled compound free volume creation and thermal softening may start more like that due to free volume creation. Also, the compound free volume creation implies a specific and intrinsic characteristic growth time of shear instability. Finally, the mature shear band width is governed by the corresponding diffusions (thermal or void diffusion) within the band. As a rough guide, the dimensionless numbers: Thermal softening related number B, Deborah number (denoting the relation of instability growth rate owing to compound free volume and loading time) and Lewis number (denoting the competition of different diffusions) show us their relative importance of thermal softening and free volume creation in shear banding. All these results are of particular significance in understanding the mechanism of shear banding in bulk metallic glasses (BMGs). Supported by the Chinese Academy of Sciences under the project “Multi-Scale Complex System” (Grant No. KJCX-SW-L08), the National Natural Science Foundation of China (Grant Nos. 10725211 and 10721202), and the Doctorial Start-up Fund of Hunan University of Science and Technology (Grant No. E50840)     

Growth and micromagnetic simulation of magnetite nanoparticles

Magnetite nanoparticles with different sizes and different assemblies were synthesized via hydrothermal method.Micromagnetic simulation shows the magnetite nanocubes with different sizes have different energy states,which determines the assembly mode.Magnetite nanocubes with the side length of 30-60 nm tended to be dispersed while both nanochains and dispersed nanoparticles were found to grow for the nanocubes with the side length less than 30 nm,which can be explained in the fact that the above two assembl...     

光栅减反层太阳能电池光电转换效率的研究

运用时域有限差分方法,研究了光栅减反层结构对太阳能电池光电转换效率及储能效果的影响.具体从光栅形状、高度以及光栅表面金属薄膜厚度出发.结果表明经光栅减反层优化表面结构的太阳能电池的光电转换效率显著增大,储能效果大大得到提升.尤其是三角形光栅太阳能电池.随着镀层厚度的增加,储能效果增加,但当薄膜厚度过厚时,储能效果反而降低.     

酸性络蓝K双波长信号系数光度法测定钙镁

基于在氢氧化钠溶液中,钙、镁均与酸性络蓝K(ACBK)形成暗红色配合物,提出了测定钙和镁的双波长信号系数光度法.该法不仅消除了钙、镁之间的吸收干扰,且消除了一定量的共存离子的干扰.利用褪色法与生色法的吸光度之和作为信号吸光度,使方法的灵敏度大为提高.测定钙、镁总量时,分别用钙、镁吸收曲线正峰与负峰上的等吸收波长470.5 nm(λPa)及559.5 nm(λNa)处测定吸光度APa和ANa,求得总量的信号系数fs为2.439.于λPa470.5 nm处测得任一浓度钙、镁试液的吸光度APa′,其信号吸光度As=fsAλPa′.测定镁时,以试剂ACBK褪色对钙配合物生色的完全相消干扰的波长539 nm(Pa)作为测定波长,负峰波长583 nm为Na.按相同方法测得镁的信号系数fs为4.148.     

2-(2′-氨基苯基)苯并咪唑衍生物分子内质子转移理论研究:取代基效应

研究了2-(2′-氨基苯基)苯并咪唑(APBI)氨基中一个H被CH3(E-C),SiH3(E-OSi),NH2(E-N),COH(E-CO),NO2(E-NO2),CF3(E-F),CN(E-CN3),OMe(E-OMe),COCH3(E-CC),Ts(E-S),p-CH3C6H4CO(E-C=O)和p-CH3C6H4NHCO(E-NH)取代后,其基态及激发态分子内质子转移(ESIPT)性质的变化规律.结果表明各衍生物基态最稳定构型为烯醇式构型E,次稳定构型旋转异构体R,酮式构型K只有当取代基为E-CN3,E-F,E-NO2,E-N,E-OMe和E-S时才存在.基态各环的核独立化学位移(NICS)研究表明取代基的引入会影响APBI环电子离域性.所有APBI衍生物都能发生激发态分子内质子转移,当引入取代基为E-CN3,E-N或E-OMe时,所得的APBI衍生物S1态分子内质子转移是无能垒过程;引入取代基为E-C,E-C=O或E-OSi时,对APBI的ESIPT势能面基本无影响,而当取代基为E-CC,E-NH,E-CO,E-F,E-NO2和E-S时,使得S1态APBI的K*构型能量低于E*.     

Synthesis, characterization and DNA-binding studies of ruthenium(II) mixed-ligand complexes containing dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline

A novel ligand dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline (dpoq) and its complexes [Ru(bpy)₂(dpoq)]²⁺ and [Ru(phen)₂(dpoq)]²⁺ (bpy = 2,2′-bipyridine; phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, electrospray mass spectra and ¹H NMR. The interaction of Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by absorption spectroscopy, fluorescence spectroscopy, thermal denaturation and viscosity measurements. Results suggest that two Ru(II) complexes bind to DNA via an intercalative mode.     

碱(土)金属离子与2-(3′-羟基-2′-吡啶基)苯并噁唑阳离子-π复合物及其分子内质子转移过程的理论研究

采用密度泛函B3LYP方法,在6-311++G(d,p)基组水平上对碱(土)金属离子(Li+,Na+,K+,Be2+,Mg2+和Ca2+)与2-(3’-羟基-2’-吡啶基)苯并噁唑(HPyBO)的36种阳离子-π复合物的初始构型进行了几何全优化,并计算了其相互作用能.结果表明,碱(土)金属离子与HPyBO复合物有较强的阳离子-π相互作用,部分复合物甚至达到了化学键的强度.相对能量的变化表明碱(土)金属离子的作用能改变HPyBO分子内质子转移过程的能垒,甚至可以导致优势构型反转.当考虑水的溶剂效应后,各质子转移异构体的相对能量及质子转移的能垒均有一定程度的改变.另外,应用分子中的原子(AIM)方法对复合物分子内氢键的键临界点性质进行了分析.     

Investigation of the Interaction Between N-benzyl Piperidones and Bovine Serum Albumin by Spectroscopic Approaches

Fluorescence and ultraviolet spectroscopies were applied to investigate the interaction between five N-benzyl piperidones (NBP) and bovine serum albumin (BSA) under imitated physiological conditions. The experimental results show that these NBPs have a static fluorescence quenching effect on the endogenous fluorescence of BSA at the temperatures 302 and 310?K. According to the fluorescence quenching theory, the Stern?CVolmer quenching constant (K _SV), the binding constant (K _a), and the number of binding sites (n) were obtained. Also, the effect of substituents on the binding capacity between NBP and BSA is in the order: C₆H₅?<?4-CH₃OC₆H₄?<?4-CH₃C₆H₄?<?2,4-Cl₂C₆H₃?<?4-ClC₆H₄. The corresponding thermodynamic parameters (??G, ??H, and ??S) were obtained at two different temperatures and indicate that hydrogen bonding and van der Waals forces play main roles in stabilizing the BSA?CNBP complex. The binding distance between the tryptophan residue in BSA and NBP was found to be much <7?nm based on the F?rster theory of non-radiation energy transfer. The effect of NBP on the conformation of BSA was analyzed as well by synchronous fluorescence spectroscopy.