Caged mitochondrial uncouplers that are released in response to hydrogen peroxide

Caged versions of the most common mitochondrial uncouplers (proton translocators) have been prepared that sense the reactive oxygen species (ROS) hydrogen peroxide to release the uncouplers 2,4-dinitrophenol (DNP) and carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) from caged states with second order rate constants of 10 (±0.8) M⁻¹ s⁻¹ and 64.8 (±0.6) M⁻¹ s⁻¹, respectively. The trigger mechanism involves conversion of an arylboronate into a phenol followed by fragmentation. Hydrogen peroxide-activated uncouplers may be useful for studying the biological process of ageing.     

Synthesis and Structure of R- ( )-CamphorDerived N-Propionyl Sultam

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与闪电过程有关的NII离子能级寿命的理论计算

用相对论多组态DiracFock方法,系统地计算了与闪电过程有关的NII离子2p2,2s2p3,2p3s,2p3p,2p3d组态能级之间的辐射跃迁概率,并由此推算出这些组态的35个能级的寿命.计算中考虑了相对论效应、电子关联、延迟效应等重要贡献.与已有的理论计算比较,目前计算的结果更接近最新实验值.据此,进一步给出了2p3d3F能级寿命新的理论预言值     

随机发展方程小扰动大偏差原理的统一方法

设X^ε=|X^ε(t);0≤t≤1|(ε>0)是由随机发展方程 dX^ε(t)=^ε(1/2)σ(X^ε(t))dB(t)+b(X^ε(t),ν(t))dt控制的随机过程,其中ν(t)是与Brown运动B(·)独立的随机过程。讨论了|(X^ε,ν(·));ε>0|的大偏差性质;在特殊情形下,给出了精确的速率函数,解决了Eizenberg和Freidlin所提的一个问题。此外,还得到一个一般性大偏差定理。     

3种菊花茶中6种微量元素的初级形态及溶出特性研究

按照传统的花茶饮用方法对杭白菊茶、野菊花茶、贡菊茶3种菊花茶中钙、镁、铁、锰、铜、锌6种元素进行浸取;用0.45μm微孔滤膜分离浸取液中的可溶态和悬浮态;采用电感耦合等离子体原子发射光谱法对此3种菊花茶中微量元素的初级形态进行了测定。结果显示：菊花茶中6种元素的提取率在12.4%—80.4%之间,可溶态在水浸液中的比率在74.3%—96.5%之间。     

Influence of relaxation effects on probabilities of the 2s2p35S2－2s22p2 3P1，2 intercombination transitions in NII

Transition probabilities of the 2s2p^3 {}^5S_2－2s^22p^2 {}^3P_{1,2} intercombination transitions in NII have been calculated by using a large-scale multiconfiguration Dirac－Fock method. In the calculation the most important effects of relativity, correlation, and relaxation are considered. From the calculated transition probabilities, the lifetime of the 2s2p^3 {}^5S_2 metastable state is derived. The result is in excellent agreement with the latest experimental result. In the meantime the influence of anomalously strong relaxation effects on probabilities of the 2s2p^3 {}^5S_2－2s^22p^2 {}^3P_{1,2} lines in NII have been found.     

ICP-AES分析铁基样品

采用标准和样品基体匹配的分析条件(1?溶液),有效克服ICP-AES分析时样品中铁基体的光谱干扰,相对标准偏差均小于5%,准确度及精确度均达到满意结果。     

Steric effects in 31P NMR spectra: ‘Gamma’ shielding in aliphatic phosphorus compounds

An examination of published ³¹P NMR spectral data for aliphatic phosphorus compounds has revealed that chain lengthening and branching effects on the chemical shift can be interpreted in terms similar to those used for ¹³C and ¹⁵N shifts. For six families of phosphorus compounds, a β-carbon substituent was shown to deshield phosphorus, while a γ-carbon caused shielding. The effects are additive, and good agreement was obtained between ³¹P shifts calculated with the appropriate constants and the experimental values. Shielding by γ-carbon is indicative of the operation of a steric influence on ³¹P chemical shifts, not heretofore articulated. The γ-effect is also useful in explaining the unusually large shielding found in six-membered cyclic phosphines.     

Effects of some phosphorus substituents on the carbon-13 chemical shifts of alkyl chains

The carbon-13 NMR spectra of 16 aliphatic phosphorus compounds with -PCl₂, -P(OCH₃)₂, -P(CH₃)₂ or -PS(CH₃)₂ groups were determined and interpreted on the basis of the usual α, β-deshielding and γ-shielding effects. The α-effects of all the groups were quite large (15 to 30 ppm), though the β-effects were small (0 to 3 ppm). The γ-effects were also small (0·2 to 1·6 ppm), but of significance in suggesting reduced steric compression relative to that found for methyl and most of the common organic functional groups. This may be attributed to the greater length of the C? P bond. The phosphorus-31 NMR spectra of these compounds also show the existence of interaction with γ-carbons by exhibiting small additive upfield shifts.