尾年金分布的存在性和结构

本文主要是在年金分布的基础上, 推广、定义并研究了一类$r$尾年金分布的存在性和结构, 给出了这类分布的存在性条件, 证明了在一定条件下, $r$尾年金分布是年金分布与某一特殊$r$尾年金分布的混合.     

电极用纳米Ag2O的电化学性能研究Ⅲ.电极的循环伏安行为

研究了3种具有不同组成的氧化银（Ⅰ）电极在2种不同扫描条件下的循环伏安（CV）行为,发现在较慢扫速（0.5mV/s)条件下,不同组成电极的峰形相差较大。各电极的峰电流值都呈现出明显的差异,即具有合适配比的混配电极展示出良好的循环可逆性能,而纯纳米粒子组成的电极接受电荷的能力明显较强。对于各极峰位的偏移及峰电流的涨消做了对比解析,表明最佳混配电极中的电活性粒子具有合理的分布,电极极化小,活性物质利用率高,因而能够展示出良好的电化学性能。     

Facile Desulfurization of Thioamides and Thioureas with Tetrabutylammonium Periodate under Mild Conditions

Summary. Thioamides and thioureas were reacted with tetrabutylammonium periodate at room temperature to afford the corresponding amides and ureas, respectively, under aprotic conditions.     

阴离子Gemini表面活性剂和阳离子传统表面活性剂混合体系双水相中囊泡形貌的转变

通过电子显微镜观察了阴离子gemini表面活性剂C₁₁- p-PhCNa和阳离子传统表面活性剂DTAB混合体系双水相中囊泡形貌随体系组成和浓度的转变。结果表明,双水相较浓的一相中形成了多层囊泡,囊泡的大小和壁厚随相的组成和浓度而改变,两组分等电荷混合有利于形成较大且壁较厚的囊泡。分析表明, gemini表面活性剂在聚集体中采取的反式构象可能是其容易形成厚壁多层囊泡的重要原因,C₁₁- p-PhCNa联接链上的苯氧基与DTA⁺之间的p-阳离子相互作用以及两组分相反电性头基之间的静电吸引使囊泡壁的多层结构更加稳定。     

C12-s-C12•2Br和C12En混合水溶液的胶团化行为

季铵盐二聚表面活性剂C12 s C12•2Br（s=2、3、4、6）和非离子表面活性剂C12E10或C12E23在水溶液中生成混合胶团.其临界胶团总浓度cmcT值介于二元复配体系中各组分的临界胶团浓度和之间.当添加少量非离子型表面活性剂（在水溶液中的摩尔分数α2=0.1）时,混合胶团中C12E10或C12E23的摩尔分数均已超过0.35;随着溶液中非离子型表面活性剂含量的增大,混合胶团中逐渐以C12E10或C12E23成分为主.     

Advanced solvent signal suppression for the acquisition of 1D and 2D NMR spectra of Scotch Whisky

A simple and robust solvent suppression technique that enables acquisition of high‐quality 1D ¹H nuclear magnetic resonance (NMR) spectra of alcoholic beverages on cryoprobe instruments was developed and applied to acquire NMR spectra of Scotch Whisky. The method uses 3 channels to suppress signals of water and ethanol, including those of ¹³C satellites of ethanol. It is executed in automation allowing high throughput investigations of alcoholic beverages. On the basis of the well‐established 1D nuclear Overhauser spectroscopy (NOESY) solvent suppression technique, this method suppresses the solvent at the beginning of the pulse sequence, producing pure phase signals minimally affected by the relaxation. The developed solvent suppression procedure was integrated into several homocorrelated and heterocorrelated 2D NMR experiments, including 2D correlation spectroscopy (COSY), 2D total correlation spectroscopy (TOCSY), 2D band‐selective TOCSY, 2D J‐resolved spectroscopy, 2D ¹H, ¹³C heteronuclear single‐quantum correlation spectroscopy (HSQC), 2D ¹H, ¹³C HSQC‐TOCSY, and 2D ¹H, ¹³C heteronuclear multiple‐bond correlation spectroscopy (HMBC). A 1D chemical‐shift‐selective TOCSY experiments was also modified. The wealth of information obtained by these experiments will assist in NMR structure elucidation of Scotch Whisky congeners and generally the composition of alcoholic beverages at the molecular level.     

碳水混合物相互作用势及混合法则的实验研究和理论探索

 利用二级轻气炮加载技术研究了碳水混合物的冲击压缩特性。研究发现：冲击压力p低于19.0 GPa时,石墨与水混合物冲击压缩特性明显不同于金刚石与水混合物的冲击压缩特性;p大于23 GPa后,它们的特性十分接近;当p为52.9 GPa时,石墨与水混合物表现出反常的冲击压缩特性,压力增加而体积出现膨胀,这与高压下碳与水发生化学反应产生气体相关。还对碳水混合物的相互作用势及混合法则的选取进行了讨论。     

Solvation Phenomena of Potassium Thiocyanate in Methanol–Water Mixtures

This paper reports the results of a variety of experiments carried out for understanding the solvation behavior of potassium thiocyanate in methanol–water mixtures. Electrical conductivity, speed of sound, viscosity, and FT-Raman spectra of potassium thiocyanate solutions in 5 and 10% methanol–water (w/w) mixtures were measured as functions of concentration and temperature. The conductivity and structural relaxation time suggest the ion–solvent and solvent-separated ion–ion associations increase as the salt concentration increases in the mixtures. The Raman band shifts due to the C–O stretching mode of methanol for the solvent mixtures reveal the formation of methanol–water complexes. The significant changes in the Raman bands for the C–N, C–S and O–H stretching modes indicate the presence of SCN⁻−solvent interactions through the N-end, “free” SCN⁻ and the solvent-shared ion pairs as potassium thiocyanate is added to the methanol–water mixtures. The relative changes corresponding to H–O–H bending and C–O stretching frequencies indicate that K⁺ is preferentially solvated by water in these solvent mixtures. The appearance and increase of the intensity of a broad band at ≈940 cm⁻¹ upon salt addition was attributed to the SCN⁻–H₂O–K⁺ solvent-shared ion pairs. No Raman spectral evidence for K⁺(H₂O)_n species was observed. The preferential solvation of K⁺ and SCN⁻ in the methanol−water mixtures was verified by the application of the Kirkwood−Buff theory of solutions. This theory confirms that K⁺ is strongly preferentially solvated by water, whereas SCN⁻ is preferentially solvated by the methanol component.