Quantum-chemical study of degradation during stretching of small-molecule analogs of cis-and trans-polyisoprene segments by their end atoms

A change in the electronic structure and the influence of force on the deformation of molecules of cis-and trans-3-methylhex-3-ene under their stretching by application of a harmonic potential to the end carbon atoms was studied via the semiempirical quantum-chemical method PM3. The maximum force at which the molecule breaks was estimated; it was shown that this value is slightly dependent on the double bond configuration. With the use of molecular dynamics simulation, it was revealed that the local temperature of a molecule can rise to 1000 K during the degradation process.     

Additional of functional vinylzinc reagents to nitrones: synthesis of (E)-N-allylhydroxylamines and their rearrangement into (E)-O-allylhydroxylamines

The vinylzinc reagents derived from hydrozirconation of alkynes and transmetallation add readily to nitrones to yield pure (E)-N-allylhydroxylamines; some of these rearrange into O-allylhydroxylamines.     

On the reduction of 1-aryl-2-oxo-1,2,3,6-tetra-hydro[1,4]diazepino[6,5-<Emphasis Type="Italic">b</Emphasis>]indole 4-oxides

Electrochemical reduction of 1-aryl-2-oxo-1,2,3,6-tetrahydro[1,4]diazepino[6,5-b]indole 4-oxides, 2-oxo-1-phenyl-1,2,3,6-tetrahydro[1,4]diazepino[6,5-b]indole, and 2-oxo-1-phenyl-1,2,3,4,5,6-hexahydro[1,4]diazepino[6,5-b]indole was studied. The results obtained were compared with previous data for the reduction of 4-oxides with formamidinesulfinic acid.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2715–2718, December, 2004.     

锂辉石—石灰石烧结中煤粉代替重油作燃料的研究和实践

目前世界锂工业原料以锂辉石为主。我国锂辉石储量居世界首位，主要分布于新疆、四川、湖南等地，其中又以四川的储量占全国第一。锂的主要基础化合物ＬｉＯＨＨ２Ｏ系用锂辉石－石灰石烧结法而得，烧结燃料是影响ＬｉＯＨＨ２Ｏ产品价格的重要因素之一。过去国内外均采用...     

Reactions of unsaturated aldehydes with cyclopentadiene in solvents of various polarities

The rate constants of cycloaddition of cyclopentadiene to unsaturated aldehydes in different solvents cannot be correlated with a single parameter, in particular, the Brownstein parameter. The data set can be fitted only by multiparameter equations in which the decisive factor increasing the reaction rate is the capability of a solvent for electrophilic solvation. The same parameter also governs the ratio of the endo and exo isomers of the addition product.     

Chemically enhanced alpha-energy spectroscopy in liquids

Summary The determination of transuranic (TRU) content in nuclear wastes, reactor materials, process solutions, and various other matrices is required in support of material assessment, environmental restoration, and waste processing activities. We have found that direct measurement of TRU is possible using surface passivated ion implanted planar silicon diode detectors. The performance and durability of modern silicon diodes enables direct detection of alpha-particles, with retention of some spectral information, through small air gaps or under direct contact with liquid or solid samples. We will present results on the performance of silicon diode detectors for the determination of TRU in liquids.     

A time dependent density functional theory study of alpha-84 phycocyanobilin chromophore in C-phycocyanin

The optical characteristics of absorption and circular dichroism (CD) spectroscopy of an alpha-subunit of C-phycocyanin (C-PC) were investigated by using time dependent density functional theory (TDDFT) combined with the polarizable continuum model (PCM). When the protonation of alpha-84 phycocyanobilin (PCB) and its interaction with the protein moiety in C-PC have been taken into account, satisfactory assignment of the absorption and CD spectra of alpha-84 PCB can be achieved. The TDDFT-PCM calculations conclude that in the visible absorption region the main peak arises from the pi electron excitation of the pyrrole rings and the shoulder peak comes from the charge transfer from Asp87 (a nearby amino acid residue) to PCBH(+).     

Roles of TNF-alpha and IgE in the late phase of contact hypersensitivity induced by trimellitic anhydride

Trimellitic anhydride (TMA) is widely used industrially to make epoxy and alkyd resins, plasticizers and surfactants. The purpose of this study was to investigate whether contact hypersensitivity (CHS) is induced by repeated TMA challenge and the role of TNF-alpha and IgE in the TMA-induced CHS. The repetition of the challenge enlarged the extent of an early and a late phase of CHS in TNF-alpha+/+ (B6129SF2/J) and Balb/c mice. In the late phase of TMA-induced CHS, the peak of ear swelling responses by single challenge showed at 24 h after challenge, but the peak was observed at 8 h after repeated challenge. In the TNF-alpha knockout TNF-alpha-/- (B6;129S-Tnftm1Gk1) mice, the repetition of the TMA challenges enlarged the extent of the late phase of CHS, but less than those in TNF-alpha+/+ mice. Injection of anti-TNF-alpha antibody into the peritoneal cavity of Balb/c mice significantly decreased the extent of the late phase of CHS. Subcutaneous injection of anti-IgE antibody into Balb/c mice also decreased the extent of the late phase of CHS in dose-dependent manner. Histologically, infiltration of polymorphonuclear leukocytes and eosinophils was more pronounced in repeatedly TMA-challenged TNF-alpha+/+ and Balb/c mice than in the TNF-alpha-/- mice and anti-TNF-alpha or anti-IgE antibodies treated Balb/c mice. These results indicate that mice sensitized by TMA could possibly offer a useful model to study the mechanism of CHS, and TNF-alpha and IgE may act as potential modulators in the late phase of TMA-induced CHS. Neutralization of TNF-alpha and IgE by anti-TNF-alpha or anti-IgE antibodies may provide therapeutic tools for the treatment of TMA-induced CHS.     

Effects of structural factors on the pi-dimerization and/or disproportionation of the cation radical of extended TTF containing thiophene-based pi-conjugated spacers

The electrochemical and chemical oxidation of extended TTF 4 and 5 are analysed by cyclic voltammetry, Visible/NIR and ESR spectroscopies, and the X-ray structures of the new salts 5 x BF(4)(CH(2)Cl(2)) and 4 x ClO(4)(THF)(1/2) are presented. The effects of structural factors on the pi-dimerization or the disproportionation reaction of the cation radical are shown. The oxidation of compound 4 presents the successive formation of stable cation radical and dication species both in dichloromethane (DCM) and in a CH(3)CN/THF mixture. In contrast, for compound 5, the stability of the oxidation states strongly depends on the nature of the solvent. In DCM, the oxidation of 5 proceeds by two close one-electron transfers while in CH(3)CN/THF the dication is directly formed via a two-electron process. The X-ray structures of the two salts reveal the formation of pi-dimers of cation radical. While the dimer (5(2))(2+) is due mainly to pi-pi interactions between the conjugating spacer, the multiplication of the sulfur atoms in compound 4 contributes to stabilize the dimer by the combined effects of S-S and pi-pi interactions. Visible/NIR and ESR experiments confirm the higher tendency of 4(+)(.) to dimerize with the occurrence of dimer and monomer in solution, while for 5(+)(.) only the monomer is detected in DCM. On the other hand, by dissolution of 5 x BF(4)(CH(2)Cl(2)) in CH(3)CN, only the neutral and the dicationic states of compounds 5 are observed owing to the disproportionation reaction.     

巯基化合物的电位分析法研究

本文对用直接电位法测试巯基化合物的可行性进行了研究。发现由硫化银，硫化汞等金属难溶盐制成的膜电极对６－巯基嘌呤，高胱氨酸，１，４－二巯基苏糖经合物可产生响应，其斜率为３０－１１０ｍＶ／ｐＣ，电极响应时间，则为十几秒至十几分钏，测试结果具有较好的重现性。因此，该方法可望得到应用。文中还对有关响应机理进行了探讨。