Enthalpies of formation from B3LYP calculations

We have calculated the geometries, energies, and normal vibrations of 845 compounds containing the elements H, C, N, O, F, Al, Si, P, S, and Cl using hybrid density functional theory in order to investigate the accuracy of atom-additive schemes for predicting enthalpies of formation at 298 K. The results give a more realistic estimate of the accuracy of density functional calculations than some overoptimistic earlier correlations. We have also calculated atom-additive schemes for the zero-point energies and enthalpic corrections to the energies. Remarkably, it is not important to include the vibrational or rotational contributions, which can be estimated well within a purely Born-Oppenheimer regression model.     

压电免疫传感器用于B因子的测定

B因子是一种不耐热的球蛋白,它参与机体的防御,在炎症过程、细胞和组织损伤中均起重要作用.B因子的检测方法常用的有单扩散法、火箭电泳法和溶血法,前者灵敏度不高,重复性差;后两者操作较复杂^[1,2].     

ChemInform Abstract: B182‐: A Quasi‐Planar Bowl Member of the Wankel Motor Family.

Bowl‐like structured B₁₈^2‐ as the fifth member of the so‐called “Wankel motor” family is found.     

A new derivative of triterpene with anti-melanoma B16 activity from Conyza Canadensis

<正>A new derivative of triterpene named Erigeronol 1 was isolated from the EtOH extract of the aerial part of Conyza canadensis together with 15 known compounds for the first time from this plant.The structure of Erigeronol 1 was elucidated as 3-O-(hydroxyacetyl) -23,28-dihydroxy-β-amyrin by hydrolysis and spectroscopic analysis.Erigeronol 1 showed potent cytotoxic activity with IC_(50) value of 7.77±0.47μg/mL against melanoma B16 determined by the 3-(4,5-dimethylthiazo-2-yl)-2,5-diphenyltetrazolium bromide(MTT) method.     

丹酚酸B的热稳定性及其热分解动力学研究

用TG-DTG 方法研究了丹参的有效成分丹酚酸B 的热降解过程. 热重分析结果表明该物质的失重过程分两步进行. 笫一步为脱去吸附水, 其温度范围为305～373 K, 第二步为丹酚酸B 分子骨架大规模降解, 其温度范围在413～864 K. 用Friedman 和Ozawa-Flynn-Wall 两种方法分别计算出该药物降解过程中的三个阶段的活化能, 采用多步线性回归方法, 并参考常用的15 种热解机理函数, 确定了丹酚酸B 热降解过程最佳动力学模型为Fn-F2-F1.     

ChemInform Abstract: Proposed Boron Nanotubes.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

荧光光谱的罗丹明B校正原理

一般荧光光谱仪推荐的校正方法是罗丹明B法,但仪器说明书对该方法的原理没有介绍。本文通过研究不同浓度罗丹明B溶液的激发光谱、发射光谱和吸收光谱再结合理论分析阐明了罗丹明B浓溶液可作为量子计数器的原因及其校正光谱的原理。     

测定痕量硅的超高灵敏显色反应的研究

本文详细研究了在阿拉伯树胶存在下,硅钒钼蓝-罗丹明B水相光度法测定硅的新方法.四元络合物的最大吸收峰在595nm处,表观摩尔吸光系数为1.0×10~6·L·mol~(-1)·cm~(-1),Sandell灵敏度为2.25×10~(-5)μgSi/cm~2。硅含量在0～0.7μg/25mL范围内遵守比尔定律。方法用于水中痕量硅的测定,结果令人满意。     

Silica Monolith for the Removal of Pollutants from Gas and Aqueous Phases

This study focused on the application of mesoporous silica monoliths for the removal of organic pollutants. The physico-chemical textural and surface properties of the monoliths were investigated. The homogeneity of the textural properties along the entire length of the monoliths was assessed, as well as the reproducibility of the synthesis method. The adsorption properties of the monoliths for gaseous toluene, as a model of Volatile Organic Compounds (VOCs), were evaluated and compared to those of a reference meso-structured silica powder (MCM-41) of commercial origin. Silica monoliths adsorbed comparable amounts of toluene with respect to MCM-41, with better performances at low pressure. Finally, considering their potential application in water phase, the adsorption properties of monoliths toward Rhodamine B, selected as a model molecule of water soluble pollutants, were studied together with their stability in water. After 24 h of contact, the silica monoliths were able to adsorb up to the 70% of 1.5 × 10⁻² mM Rhodamine B in water solution.