金属-有机框架材料孔结构的初步理论评估

金属-有机框架材料在气体吸附/分离方面具有广泛的应用, 因而引起国内外学者的广泛关注。本文以6种代表性的MOFs为例简单介绍了利用理论工具研究MOFs孔结构的方法。     

基于四氟对苯二甲酸为配体的两个锌(Ⅱ)的配合物的合成、晶体结构和荧光性质

本文以四氟对苯二甲酸(H2tfbdc)和2,2′-联吡啶(bpy)为配体,合成了2个锌(Ⅱ)的配合物[Zn2(bpy)4(Htfbdc)2(tfbdc)](1)and[Zn(bpy)(H2O)2(tfbdc)](2)。并用元素分析、红外光谱、X-射线单晶衍射结构分析、热重分析等对其进行了表征。化合物1和2均属于三斜晶系,空间群为P1。配合物1和2中的锌(Ⅱ)离子分别位于畸变的八面体和畸变的三角双锥构型中。配合物1为双核结构,它们通过分子间氢键进一步形成一个二维的结构;配合物2是一个单核的两性离子,两性离子间通过氢键形成一个三维的空间网状超分子结构。考察了两种配合物的固体荧光性质。     

AD95陶瓷的层裂强度及冲击压缩损伤机理研究

采用激光位移干涉测试技术测量了AD95 陶瓷在一维应变冲击压缩下的自由面或样品/窗口界面粒子速度剖面, 确定了层裂强度及其与加载应力的变化关系, 在此基础上讨论了冲击压缩损伤程度与加载应力的关系. 研究结果表明: AD95陶瓷发生冲击压缩损伤的阈值应力约为3.7 GPa, 小于其雨贡纽弹性极限(HEL, 约5.47 GPa); 小于阈值应力不发生冲击压缩损伤, 层裂强度随加载应力的增加逐渐增大; 大于阈值应力冲击压缩损伤快速发展, 层裂强度迅速降低; 在HEL附近层裂强度降低到零, 丧失了抗拉能力, 表明材料发生了严重的冲击压缩损伤.     

双(N 氧化吡啶 2-甲醛)缩1,2-丙二胺镍配合物的合成和晶体结构

合成所得双(N-氧化吡啶-2-甲醛)缩1,2-丙二胺的镍(II)配合物[Ni(piopn)(H_2O)_2](ClO_4)_2的晶体属空间群C_s~4-C_c, 晶胞参数a=0.7397(3) nm, b=1.3187(7) nm, c=2.5502(14) nm, β=102.18(4)°. 用分子轨道理论的近似方法分析了该配合物的电子结构和分子轨道, 探讨了分子的结构特征与红外光谱的关系.     

一维棒状ZnO的制备及电化学嵌锂性能研究

目前,商业化锂离子电池一般采用石墨作为负极材料,因其电位与金属锂电极的电位很接近,所以当电池反复循环和过充时,石墨表面易析出金属锂,会因形成枝晶而短路。在温度过高时还容易引起热失控。同时,锂离子电池的容量在很大程度上取决于负极的锂嵌入量,而且石墨材料容量相对较低     

Enhanced <Emphasis Type="SmallCaps">l</Emphasis><Emphasis Type="Italic">-</Emphasis>(+)-Lactic Acid Production by an Adapted Strain of <Emphasis Type="Italic">Rhizopus oryzae</Emphasis> using Corncob Hydrolysate

Corncob is an economic feedstock and more than 20 million tons of corncobs are produced annually in China. Abundant xylose can be potentially converted from the large amount of hemicellulosic materials in corncobs, which makes the crop residue an attractive alternative substrate for a value-added production of a variety of bioproducts. Lactic acid can be used as a precursor for poly-lactic acid production. Although current industrial lactic acid is produced by lactic acid bacteria using enriched medium, production by Rhizopus oryzae is preferred due to its exclusive formation of the l-isomer and a simple nutrition requirement by the fungus. Production of l-(+)-lactic acid by R. oryzae using xylose has been reported; however, its yield and conversion rate are poor compared with that of using glucose. In this study, we report an adapted R. oryzae strain HZS6 that significantly improved efficiency of substrate utilization and enhanced production of l-(+)-lactic acid from corncob hydrolysate. It increased l-(+)-lactic acid final concentration, yield, and volumetric productivity more than twofold compared with its parental strain. The optimized growth and fermentation conditions for Strain HZS6 were defined.     

标准圆筒试验技术与数据处理方法研究

 对标准圆筒试验技术与数据处理方法进行了深入研究,在狭缝扫描实验中建立了新型、高效的照明技术、底片判读方法以及数据处理方法,得到了精度高、信息丰富的圆筒壁质点上的位移、速度、加速度和比动能结果。同时,通过VISAR技术直接测量了圆筒外表面径向膨胀速度-时间曲线,进而积分得到位移-时间曲线,与狭缝扫描结果相互印证和补充,进一步提高了测试可靠性。     

磁性蛋白质微胶囊的声化学法构筑

通过声化学法制备了具有生物相容性的磁性蛋白质微胶囊, 利用高强度超声波辐照含有油酸改性磁性的Fe₃O₄纳米粒子的油相与蛋白质水溶液的两相界面, 只需几分钟即可得到磁性蛋白质微胶囊. 这种制备蛋白质微胶囊的方法快速简便, 高效环保, 可将分散于油相的疏水性药物直接装载, 不破坏药物. 在药物靶向传输等领域具有应用性.     

L－苏糖酸镍的制备及其理化性质

L-苏糖酸作为金属离子的载体 ,可使金属离子易与氨基酸或蛋白质结合而被动物吸收和利用 [1] 。镍是人体必需微量元素之一 ,它参与金属特异酶的各种功能 ,形成活性中心 ,通过形成络合物参与底物与酶的结合 ,通过抑制或促进其它金属元素的作用控制酶活性。目前已知镍有促进红细胞的再生 ,刺激生血机能作用 ,它还可能是胰岛素分子中的辅酶成分 ,与增强胰岛素效应、降低血糖水平有关 [2 ]。因此 ,研究镍 ( )与 L -苏糖酸的化合作用很有必要。文献 [3,4]报道了 Fe2 +、Zn2 +、K+、Na+、Mg2 +和 Cr3+与L-苏糖酸所形成的化合物的制备方法。而…     

Quasi-topological electromagnetism:Dark energy,dyonic black holes,stable photon spheres and hidden electromagnetic duality

We introduce the quasi-topological electromagnetism which is defined to be the squared norm of the topological 4-form F ∧ F. A salient property is that its energy-momentum tensor is of the isotropic perfect fluid with the pressure being precisely the opposite to its energy density. It can thus provide a model for dark energy. We study its application in both black hole physics and cosmology.The quasi-topological term has no effect on the purely electric or magnetic Reissner-Nordstr o¨m black holes, the dyonic solution is however completely modified. We find that the dyonic black holes can have four real horizons. For suitable parameters, the black hole can admit as many as three photon spheres, with one being stable. Another intriguing property is that although the quasitopological term breaks the electromagnetic duality, the symmetry emerges in the on-shell action in the Wheeler-De Witt patch. In cosmology, we demonstrate that the quasi-topological term alone is equivalent to a cosmological constant, but the model provides a mechanism for the dark energy to couple with other types of matter. We present a concrete example of the quasi-topological electromagnetism coupled to a scalar field that admits the standard FLRW cosmological solutions.