Raman Scattering Study of Natural and Synthetic Compounds Containing Polyene Chains

Doklady Physics - The dependence of Raman spectra of the molecules containing polyene chains on the conjugation length, structure of side and end groups, and isomer type is analyzed theoretically.     

超级微波消解-电感耦合等离子体发射光谱（ICP-OES）法测定土壤中18种元素

为提高土壤多元素同时检测的效率,采用超级微波消解-电感耦合等离子体发射光谱法测定土壤中钾、钠、钙、镁、铜、铁、锰、锌、磷、硫、硼、砷、镉、铬、铅、钴、镓、锂等18种元素含量。比较了超级微波消解、常规微波消解和电热板消解的处理效果,采用超级微波消解法对样品进行前处理,并优化了消解条件。在最优条件下,各元素的检出限在0.05~20 mg/kg,加标回收率在86.2%~107.5%,RSD在0.1%~3.0%,方法准确度及精密度可以满足多元素同时测定的需求,且该方法具有简单、快速、成本低、用酸量少、重现性好等特点。     

二分图中关于Enomoto问题的结果

设k,n1和n2是3个正整数,G=（V1,V2;E）是一个二分图,使得｜V1｜=n1,｜V2｜=n2,其中n1≥2k＋1,n2≥2k＋1并且n1-n2≤1．如果对任意不相邻的x∈V1和y∈V2,都有d（x）＋d（y）≥2k＋2,则G包含k个相互独立的圈．以上结果部分地回答了Enomoto提出的关于二分图有独立圈的问题．     

Catalytic reactions of hydrocarbons promoted by coordination unsaturated Zr and Ti compounds: A density functional theory study

The paper is a review of a series of publications devoted to a number of homogeneous and heterogeneous catalytic reactions, their mechanisms, and energy characteristics. These reactions are promoted by coordination unsaturated compounds of Ti and Zr and proceed with cleavage and/or formation of C-C and C-H bonds in the hydrocarbon chain (polymerization reaction of ethylene, styrene, and butadiene-1,3, hydrogenolysis and hydroisomerization of linear and branched alkanes, and H/D isotope exchange in alkanes). A high-level quantum chemical method (DFT, PBE functional, gauss type TZ2p basis sets, the original PRIRODA program) was applied for the catalytic systems under the study. The nature and the structure of the active center, detailed mechanisms, and energy profile of the reaction of the substrate with a catalytic particle are considered. We compare our data with the results of both experimental and theoretical contributions from other authors.     

Regioselectivity of acid-catalyzed cyclization of 1-(3,4-dialkylaryl)-3-chloropropan-1-ones to indanones. Comparison of experimental data and results of computer simulation

The acid-catalyzed cyclization of 1-(3,4-dialkylaryl)-3-chloropropan-1-ones to dialkylindanones via the intermediate formation of (3,4-dialkylaryl)propenones was studied. This reaction affords isomeric products: 5,6-dialkylindan-1-ones and 4,5-dialkylindan-1-ones. The DFT quantum chemical calculation results correlate with the experimental data and suggest that the structural factors affect the ratio of products.     

利用四氯乙烷胺化反应合成联氢化嘧啶衍生物的研究

利用均四氯乙及二氯甲烷的胺化反应,合成了联氢化嘧啶衍生物1～5,4a,8b-反-4,5,8a,9a-四氮杂全氢芴(6)和8b,8c-顺-3a,4a,7a,8a-四氮杂环戊并全氢芴(7)。化合物(6)和(7)的顺反异构体在酸催化下开环,异构生成较稳定的6b和7a。     

Primary isotopic effect on the magnetic shielding of tin nuclei (117Sn and 119Sn)

The Kirkwood-Buff statistical mechanical theory of surface tension γ for monatomic fluids is extended to molecular fluids. A rigorous expression for γ is derived in terms of the angular pair distribution function f(z ₁ R ₁₂θ₁θ₂) of an equilibrium fluid-fluid system (liquid-gas, liquid-liquid, or gas-gas). The Fowler approximation is applied for the liquid-gas case, and a simple expression for γ is derived in terms of the bulk liquid angular pair correlation function g(R ₁₂θ₁θ₂). Thermodynamic perturbation theory for g(R ₁₂θ₁θ₂) is also used to calculate γ theoretically. The theoretical results are compared with experimental values.