The Substituent Effects of tert-Butyl Radical Addition to 2-Substituted Allyl Chlorides

The relative rates for the addition reactions of tert-butyl radical to 2-substituted ally chlorides I have een determined. The correlation of log k/k₀, vs. σ_m gives a ρ mvalue of 3.59 with correlation coefficient of 0.930. When the substituent CH₂Cl is excluded, correlation coefficient raises to 0.990 and ρ value becomes 3.39. The large p value and the deviation of relative rate of substituent CH₂C1 are discussed.     

Study of cryostructurization of polymer systems

Summary A possibility of obtaining insoluble gels with the help of freezing-thawing procedures was demonstrated on an example of aqueous solutions of a thiol-containing poly(acryl amide) derivative. The gel formation was proved to occur as a result of oxidation of free SH groups of polymer chains by water-dissolved air oxygen.     

Difference in Conversions Between Dimethyl Sulfide and Methanethiol in a Cold Plasma Environment

This study compared the conversion of two malodorous substances, dimethyl sulfide (CH₃SCH₃, DMS) and methanethiol (CH₃SH) in a cold plasma reactor. The DMS and CH₃SH were successfully destroyed at room temperature. DMS decomposed less than CH₃SH at the same conditions. In oxygen-free condition, CS₂ and hydrocarbons were the major products, while SO₂ and CO_x were main compounds in oxygen-rich environments. The DMS/Ar plasma yielded more hydrocarbons and less CS₂ than that of CH₃SH/Ar plasma. In the CH₃SH/O₂/Ar plasma, rapid formation of SO and CO resulted in the yields much more amounts of SO₂ and CO₂ than those in the DMS/O₂/Ar plasma; and remained only a trace of total hydrocarbons, CH₂O, CH₃OH, CS₂, and OCS. The major differences between the reaction mechanisms of DMS and CH₃SH were also proposed and discussed.     

新型四次谐波混频电路

本文介绍了一种适用于高次谐波混频的电路原理图,基于空闲频率相位抵消理论,该混频电路结构可以避免复杂的空闲频率回收电路设计,同时能获得很高的端口隔离度。基于该结构,设计了新型的Ka波段四次谐波混频器,该混频器在38.4 GHz测得最小变频损耗 8.3 dB,在34-39 GHz 变频损耗小于10.3dB, LO-IF、RF-LO、 RF-IF 端口隔离度分别优于30.7 dB、 22.9dB、46.5dB。     

Simultaneous determination of YM928, a novel noncompetitive AMPA receptor antagonist, and its demethylated metabolite in rat, dog and monkey plasma by high-performance liquid chromatography with ultraviolet detection

A specific HPLC method for the simultaneous determination of YM928, a novel noncompetitive AMPA receptor antagonist, and its demethylated metabolite (YM-58875) in rat, dog and monkey plasma was developed and validated. The method utilized multiple-step liquid-liquid extraction followed by a reversed-phase HPLC with UV detection at 275 nm. No interfering peaks were observed at the retention times of YM928, YM-58875 or internal standard. The validated quantitation range was 5-5000 ng/mL for both YM928 and YM-58875 when 1 mL of the plasma sample was used. The intra- and inter-day precision was less than 5.3 and 2.5% for YM928, and 3.7 and 2.3% for YM-58875, respectively. The intra- and inter-day accuracies were -8.7-5.3% and 0.7-1.9% for YM928, and -10.0-6.1% and 1.3-3.4% for YM-58875, respectively. The mean recoveries in the extraction process were 52.7-62.8%. The utility of this analytical method was demonstrated by the investigation of the pharmacokinetics of the unchanged drug and its metabolite in preclinical studies.     

Design and synthesis of a potential SH2 domain inhibitor bearing a stereodiversified 1,4-cis-enediol scaffold

Synthesis of a potential Src family SH2 domain inhibitor incorporating a 1,4-cis-enediol scaffold is reported. The synthetic route offers straightforward and highly selective access to the enediol and its associated chiral centers. Key steps include stereocontrolled syn-aldol coupling, amide alkynylation, and asymmetric ketone reduction.     

折线型裂纹对SH波的动力响应

利用Fourier积分变换方法,得出了无限平面中用裂纹位错密度函数表示的单裂纹散射场.根据无穷积分的性质,把单裂纹的散射场分解为奇异部分和有界部分.利用单裂纹的散射场建立了折线裂纹在SH波作用下的Cauchy型奇异积分方程.根据折线裂纹散射场和所得的积分方程讨论了裂纹在折点处的奇性应力及折点处的奇性应力指数.利用所得的奇性应力定义了折点处的应力强度因子.对所得Cauchy型奇积分方程的数值求解,可得裂纹端点和折点处的动应力强度因子.     

Rate Coefficients of the Reactions of Fluorine Atoms with H2S and SH over the Temperature Range 220–960 K

Reaction F + H₂S→SH + HF (1) is an effective source of SH radicals and an important intermediate in atmospheric and combustion chemistry. We employed a discharge-flow, modulated molecular beam mass spectrometry technique to determine the rate coefficient of this reaction and that of the secondary one, F + SH→S + HF (2), at a total pressure of 2 Torr and in a wide temperature range 220–960 K. The rate coefficient of Reaction (1) was determined directly by monitoring consumption of F atoms under pseudo-first-order conditions in an excess of H₂S. The rate coefficient of Reaction (2) was determined via monitoring the maximum concentration of the product of Reaction (1), SH radical, as a function of [H₂S]. Both rate coefficients were found to be virtually independent of temperature in the entire temperature range of the study: k₁ = (1.86 ± 0.28) × 10⁻¹⁰ and k₂ = (2.0 ± 0.40) × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹. The kinetic data from the present study are compared with previous room temperature measurements.