Gas chromatographic and mass spectrometric characterization of isomeric alkylthiophenes (C20) and their occurrence in deep sea sediments

Six isomeric C₂₀ alkylthiophenes were synthesized in order to prove the occurrence of such compounds in various deep sea sediments. As expected from the analogy with the corresponding saturated hydrocarbons, 2- and 3-heptadecylthiophene have considerably longer relative retention times than the isomeric isoprenoid compounds, i.e. 2- and 3-(4,8,12-trimethyltridecyl)thiophene and 3- and 4-methyl-2-(3,7,11-trimethyldodecyl)thiophene. Covats retention indices for all compounds were determined by isothermal analysis at 190°C on two different silicone-coated capillary columns. The mass spectra of the monoalkylated thiophenes show a base peak at m/z 98 corresponding to a Mcafferty rearrangement product in the case of the 3-substituted isomers, whereas a simple benzylic cleavage dominates in the mass spectra of 2-alkylthiophenes. 4-Methyl-2-(3,7,11-trimethylodecy)thiophene is an exception from this simple rule because also shows the McLafferty rearrangement as dominant fragmentation. Two of the isoprenoid thiophenes are prominent compounds in various deep sea sediments.     

Classification of oxide glasses: A polarizability approach

A classification of binary oxide glasses has been proposed taking into account the values obtained on their refractive index-based oxide ion polarizability α_O2−(n₀), optical basicity Λ(n₀), metallization criterion M(n₀), interaction parameter A(n₀), and ion's effective charges as well as O1s and metal binding energies determined by XPS. Four groups of oxide glasses have been established: glasses formed by two glass-forming acidic oxides; glasses formed by glass-forming acidic oxide and modifier's basic oxide; glasses formed by glass-forming acidic and conditional glass-forming basic oxide; glasses formed by two basic oxides. The role of electronic ion polarizability in chemical bonding of oxide glasses has been also estimated. Good agreement has been found with the previous results concerning classification of simple oxides. The results obtained probably provide good basis for prediction of type of bonding in oxide glasses on the basis of refractive index as well as for prediction of new nonlinear optical materials.     

线型碳链LiC_(2n)Li的结构和电子光谱的密度泛函理论研究

应用密度泛函理论,在B3LYP/6 31G(d)水平上优化得到了线型簇合物LiC2nLi(n=1 ~10,D∞h)的基态平衡几何构型,并计算了它们的谐振动频率.利用含时密度泛函理论,计算了簇合物LiC2nLi的X1∑ +g→11∑ +u跃迁的垂直激发能,以及相应的振子强度.基于计算结果,建立了跃迁能和体系大小n的解析关系式. 同时也计算了体系的第一绝热电离能,讨论了体系的电离能与体系大小n的关系.     

蒙旦树脂化学组成的研究

采用阴离子交换色谱和硅胶－氧化铝柱色谱对云南寻甸蒙旦树脂（ＸＤＳＺ）、潦浒蒙旦树脂（ＬＨＳＺ）、昭通蒙旦树脂（ＺＴＳＺ）和吉林舒兰蒙旦树脂（ＳＬＳＺ）进行了族组分的分离。树脂游离酸，树脂结合酸，树脂烃和树脂醇在各树脂中的百分含量分别为ＸＤＳＺ１１．８６，８．７６，１２．３０，４５．９９；ＬＨＳＺ１５．８９，１３．９１，４．９０，４５．９９；ＳＬＳＺ２５．４６，８．０７，１７．４０，３６．２２；ＺＴ     

Effect of Ce<Superscript>3+</Superscript> on spectral characteristic of D1/D2/Cytb559 complex from spinach

It was studied by spectroscopy that PSII reaction center complex consisting of three polypeptides, D₁, D₂ and Cytb559, were purified from PSII particle of CeCl₃ treated spinach. The results of the experiment show that Ce³⁺ could improve the growth of spinach, and accelerate electron transport of PSII particles. Of chl-a of UV-Vis spectrum of D1/D2/Cytb559 complex, Soret band was blue-shifted by 3 nm and Q band by 2 nm, respectively, and the fluorescence emission peak was blue-shifted by 5 nm in CeCl₃-treated spinach compared with the one in control. By the extended X-ray absorption fine structure (EXAFS) spectroscopy methods, it has been found that Ce³⁺ is coordinated with 8 nitrogen atoms in the first coordination shell with Ce-N bond length of 0.253 nm, and Ce³⁺ with 6 oxygen atoms in the second coordination shell with Ce-O bond length of 0.32 nm. However, the secondary structure of D1/D2/Cytb559 complex by circular dichroism (CD) spectroscopy has no significant change after CeCl₃ treated. It might be that Ce³⁺ binds to porphyrin rings of chlorophyll and oxygen of amino acid residue of polypeptide in D1/D2/Cytb559 complex, and then accelerates the primary reaction of PSII, intensifies function of P680⁺ primary electron donor of D1/D2/Cytb559, but there is little change in conformation of PSII reaction center complex.     

Topological and fractal properties of turbulent passive scalar fluctuations at small scales

Corrections of Batchelor's spectral law –1 of passive scalar-fluctuations are obtained by taking into account the topological instabilities of small-scale vortex sheets: –4/3 for supercritical and –5/4 for subcritical regimes. The corresponding fractal dimensions of the scalar interface areD =8/3 for supercritical andD =11/4 for subcritical regimes. Good agreement with experimental data is established.     

Absence of absolutely continuous spectrum of Floquet operators

The spectrum of the Floquet operator associated with time-periodic perturbations of discrete Hamiltonians is considered. If the gap between successive eigenvalues _j of the unperturbed Hamiltonian grows as _j - _j-1 j and the multiplicity of _j grows asj with >0 asj tends to infinity, then the corresponding Floquet operator possesses no absolutely continuous spectrum provided the perturbation is smooth enough.     

偏最小二乘法在原子吸收光谱分析中的应用——钴和铟的同时测定

本文用偏最小二乘法（ＰＬＳ）校正了火焰原子吸收分析Ｉｎ２５２．１３７ｎｍ对Ｃｏ２５２．１３６ｎｍ的吸收线重叠干扰,对混合样中Ｃｏ和Ｉｎ的含量进行了测定,结果令人满意。     

Effect of aryl ligands on the chemical hardness of arylmercury cations

¹⁹F NMR spectroscopy was used to study the exchange reactions involving 4-fluorothiophenoxides, 4-nitrophenoxides, chlorides, and acetates of arylmercury and triphenylphosphinegold. The analysis of the data on equilibrium constants allows one to obtain information on the comparative chemical hardness of ArHg⁺ and Ph₃PAu⁺ cations. The increase in the electron-donating ability of aryl ligands enhances the chemical hardness of ArHg⁺ cations, their influence being best described by ⁰ constants of substituted phenyl groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1255–1260, May, 1996.