甲醇荧光光谱的量子分析

通过量子近似计算研究了甲醇的荧光光谱.将甲醇分子近似看成双原子分子,甲基和羟基分别为原子实,氧原子未共享电子对看成价电子.利用数值计算的方法对双原子分子电子能级差进行估算,得到电子能级差为一个仅与分子线度相关的函数.然后把C-O键长作为分子线度代入前面得到的函数中,算出甲醇分子主跃迁能级差,并将所得结果与实验值进行对比,误差仅为2.2%,理论计算与实验结果吻合.     

GC–MS Investigation of the Transfer Behavior of Alkalescent Flavors in Moderate/Low-Tar Cigarettes

Experiments employing a technique involving solvent extraction and gas chromatography–mass spectrometry (GC–MS) analysis were conducted to investigate the distributions and transfer behavior of alkalescent flavors in moderate/low-tar cigarettes. In the current study, the transfer behavior of eleven flavors, including two alkalescent ketones, eight heterocyclic compounds, and perillartine, were evaluated by examining their retention ratios in tobacco (%r ₁), their ratios of immigration into the filter tip (%r ₂), their transfer ratios into the mainstream smoke (%r ₃), and their ratios of interception by the filter tip (%r ₄), which varied from 3.94 to 44.10, from 0 to 35.36, from 0 to 17.14, and from 7.36 to 50.53 %, respectively. The analytical results indicated that flavor transfer behavior is likely dependent on the molecular weight and boiling point of the flavor, the configuration of the cigarette, and/or other factors (e.g., intermolecular tension, chemical polarity, etc.), although no further studies of these aspects were performed as part of this work. These findings may lead to improvements in the flavoring procedure during the future development of novel cigarettes.     

Dynamic light scattering of a concentrated multicomponent spherical particle solution

The“measured”dunamic structure function of highly concentrated and smallspherical colloidal system with a narrow distribution of particle sizes can be expressed in termsof the sum of two independent modes due to collective diffusion and polydispersity fluctuationsrespectively.The“measured”static structure functions S~M(K) is derived,and applied to cal-culate the polydispersity distribution.The relationship between the moments of the gammaparticle size distribution and the moments determined by a dynamic light scattering measure-ment is developed for the case when the particles are small and spherical.     

Mm(NiMnTiCo)5贮氢合金的制备工艺、 电化学性能及相结构研究

用电化学测量、Ｘ射线衍射、透射电子显微镜和能谱分析等技术对不同工艺制备的Ｍｍ（ＮｉＭｎＴｉＣｏ）５贮氢合金的电化学性质和结构进行了详细研究。快淬技术如熔体喷带法可有效改善合金的循环稳定性，但却导致其活化速度和放电容量下降。合金在适当温度下回火可弥补以上不足。不同制备工艺造成合金电化学性能变化的原因在于相结构和显微组织的差别。     

在非水介质中制备聚电解质静电吸附自组装膜

静电吸附自组装是近年来得到广泛研究和应用的一种制备超薄膜的方法,具有操作简单,膜厚可控等很多优点,已经被广泛应用于制备各种功能薄膜材料[1~4].通常情况下,聚电解质的静电吸附自组装都是在水中进行的.一方面,聚电解质在水中可以很容易的实现电离;另一方面,以水做介质可以避免有机溶剂的污染,尤其对模仿各种生物环境非常有利.所以自1991年Decher首先报道该方法以来,绝大多数的聚电解质静电吸附自组装是以水为介质.但是,以水做介质也常常会遇到一些困难,尤其对于疏水性(包括非水溶性)聚电解质来说.在当前研究的许多热点领域中如导电、发…     

P204-P507-H2SO4体系萃取稀土元素的研究

对P204与P507混合萃取剂在硫酸介质中萃取分离Nd和Sm的行为进行了研究。重点考察了在硫酸介质中,P204添加一定量P507对稀土萃取能力、反萃性能以及Nd-Sm分离效果的影响。测定了不同比例的混合有机相在不同平衡酸度下的Nd,Sm分配比以及协同系数,并得到了相应条件下的Sm/Nd分离系数。试验结果表明,P204与P507混合体系在硫酸介质中萃取分离Nd,Sm时存在不同程度的正协同效应。     

A new proof of Euler's formula for ζ(2n)

We use the hyperbolic cotangent function to deduce another proof of Euler's formula for ζ(2n).     

Biosynthesis of Hybrid Neutral Lipids with Archaeal and Eukaryotic Characteristics in Engineered Saccharomyces cerevisiae

Discovery of the Asgard superphylum of archaea provides new evidence supporting the two-domain model of life: eukaryotes originated from an Asgard-related archaeon that engulfed a bacterial endosymbiont. However, how eukaryotes acquired bacterial-like membrane lipids with a sn-glycerol-3-phosphate (G3P) backbone instead of the archaeal-like sn-glycerol-1-phosphate (G1P) backbone remains unknown. In this study, we reconstituted archaeal lipid production in Saccharomyces cerevisiae by expressing unsaturated archaeol-synthesizing enzymes. Using Golden Gate cloning for pathway assembly, modular gene replacement was performed, revealing the potential biosynthesis of both G1P- and G3P-based unsaturated archaeol by uncultured Asgard archaea. Unexpectedly, hybrid neutral lipids containing both archaeal isoprenoids and eukaryotic fatty acids were observed in recombinant S. cerevisiae. The ability of yeast and archaeal diacylglycerol acyltransferases to synthesize such hybrid lipids was demonstrated.