How Many Methanol Molecules Can Solvate a Glycine: a PBE1PBE Approach

Microsolvation of glycine in methanol clusters is explored by the use of DFT calculation method. The lowest energy conformations within 16.72 kJ·mol-1 of the glycine clustering with one to six methanol molecules, which are obtained at the B3LYP/6-31+G(d) level of theory, are reoptimized at PBE1PBE/6-311+G(d,p). The calculated results agree with our previous results with B3LYP (Chin. J. Chem. Phys. 22 (2009) 577) that the clusters of two forms (Z-and N-form) tend to be isoenergetic when the number of the solvate molecules reaches six. Furthermore, this result is in good agreement with the experiment of the tryptophan-methanol clusters, implying that the present treatments are reasonable and reliable. The results also indicate that nine methanol molecules are not enough to fully solvate a glycine molecule, and a tentative estimation is obtained that ten methanol molecules may fully solvate a glycine molecule, which consists with the experiment results.     

参加国家金标准物质定值测试工作的研究报告

近20年来,武警黄金指挥部测试中心参加了12个国家矿石金、12个国家痕量金分析标准物质定值测试工作.该文对取样量、样品均匀性检验、样品焙烧、分析方法的选取、样品稳定性检验等技术进行了总结,并对今后金标准物质的研制提出了建议.     

光电直读光谱法测定钢中不同形态铝

钢中铝存在形式主要有两种,一种以金属固溶体存在,另一种是化合态以非金属夹杂物形式存在。在湿法化学分析中,用无机酸溶样时,金属铝、铝的硫化物均被溶解,故称为酸溶铝,这些铝的存在形式在一定范围内有利于细化晶粒,提高钢的使用性     

大米中镉检测能力验证

镉是剧毒物质,常通过土壤或水被农作物(特别是水稻等)吸收。世界各国对大米中镉含量均有严格限制,我国粮食卫生标准GB 2715—2005中镉的限量为0,2 mg·kg~(-1)。近年来,国家大米监督抽查结果显示,我国南方部分省份的大米镉含量超标,据调查环境污染是造成大米中镉超标的主要原因。本工作通过对2008年国家认监委能力验证计划《大米     

A DFT Study on the Stable Structures and Dissociation Mechanism of C3O6 Cluster

Using geometrical optimization and DFT method at the B3LYP/6-31G (d) level, nineteen equilibrium geometries were identified, and three transition states of dissociation reaction of C3O6 clusters were also found. The vibrational frequencies and intrinsic reaction coordinate (IRC) verification at the same level were computed to verify the transitions. And then we calculated the dissociation energies and analyzed the dissociation channels. The computational results show that the dissociation energies of C3O6 isomers relative to three CO2 are between 1.509 × 103 and 10.61 × 103 kJ·kg-1, and the energy barriers of the reactions are 92.857, 131.138 and 185.793 kJ·mol-1. Both the high dissociation energies and high energy barriers show that C3O6 clusters studied in this paper are stable enough to be used as high-energy-density materials.     

用于质子交换膜燃料电池抗CO的Pt-CeO2/C催化剂的制备和表征

采用一步沉淀法,制备了纳米级Pt-CeO2/C电催化剂.透射电镜和X射线衍射表征结果表明,制备的催化剂Pt颗粒均匀分散于碳载体表面,其粒径主要分布于1.5～2.5 nm.将Pt-CeO2/C催化剂制备成质子交换膜燃料电池膜电极,经循环伏安和单电池极化曲线测试发现,Pt-CeO2/C催化剂性能与Pt/C催化剂的相当.一氧...     

Synthesis and Crystal Structure of（2E,6E）-2,6-bis（2,3-dimethoxybenzylidene）cyclohexanone

The new title compound (2E,6E)-2,6-bis(2,3-dimethoxybenzylidene)cyclohexanone (C 24 H 26 O 5,M r=394.45) has been synthesized,and its crystal structure was studied.The title compound crystallizes in the orthorhombic system,space group Pca2 1 with a=17.536(2),b=14.8515(16),c=8.0512(9),V=2096.8(4) 3,Z=4,D c=1.250 g/cm 3,λ=0.71073,μ=0.087 mm-1 and F(000)=840.The structure was solved by direct methods and refined to R=0.0533 and wR=0.1248 from 2727 observed reflections (I > 2σ(Ⅰ)).The title molecules are connected through hydrogen bonds to generate a 3-D supramolecule.The preliminary biological tests showed definitely biological activity for the title compound.     

《燃料化学学报》征稿简则

《燃料化学学报》是由中国科学院主管、中国化学会和中国科学院山西煤炭化学研究所主办。刊载国内外燃料化学基础研究及其相关领域的最新研究成果和进展,涵盖煤炭、石油、油页岩、天然气、生物质,以及与此相关的环境保护和应用催化等方面的内容。     

元素医学的不可替代性

广州南方医院诊断一个就诊病人,患者长时间拉稀、呕吐、头晕等,用各种检查手段,既不知病名,也找不到病因,无法治疗,只好介绍到广州市微量元素研究所来进行头发微量元素检测。结果发现该患者发锡(Sn)非常高,锡(Sn)中毒就是引起患者肠胃炎、发生腹泻、呕吐和头晕的原因。广州南方医院还诊断一个就诊病人,病人长时间全身发抖无力,到各大医院检查无果,南方医院用各种检     

对杂散光测试材料要求的探讨

从分光光度计杂散光测试原理出发,对我国目前在用的几种杂散光测试材料特性进行了分析。通过实验验证,指出了其中的不合理处,并提出了对杂散光测试材料特性的基本要求。 ,