Internal energy content of n-butylbenzene, bromobenzene, iodobenzene and aniline molecular ions generated by two-photon ionization at 266 nm. A photodissociation study

A technique to investigate photodissociation kinetics on a nanosecond time scale has been devised for molecular ions generated by multiphoton ionization (MPI) using mass-analyzed ion kinetic energy spectrometry. The branching ratio or rate constant has been determined for the photodissociation of the n-butylbenzene, bromobenzene, iodobenzene, and aniline molecular ions generated by MPI at 266 nm. The ion internal energies have been estimated by comparing the measured kinetic data with the previous energy dependence data. The analysis has shown that only those molecular ions generated by two-photon ionization contribute to the photodissociation signals. Around half of the available energy has been found to remain as molecular ion internal energy in the two-photon ionization process. Copyright 1999 John Wiley & Sons, Ltd.     

Photolyse d'α-alcoxycyclanones

The photolysis of α-alkoxycyclohexanones and α-alkoxycyclopentanones in ethanol involves NII elimination of an alkoxy group. The proportion of cyclanone is higher when starting from α-alkoxycyclohexanones, and esters are isolated in low yields. No ester, but aldehydes are obtained from α-alkoxycyclopentanones. By photolysis of 2-methoxy norbornanone, only epimerisation is detected. Oxetanols are formed with satisfactory yields only from aromatic ketones such as α-methoxy tetralone or α-methoxyindanone. Mechanistic aspects, including the nature of the excited states, are discussed.     

Photolyse de cetones conjuguees heterosubstituees lineaires

Photoenolization of α-alkoxy or α-dialkylamino mesityl oxides is preferred to hydrogen abstraction next of heteroatom. Alkylideneoxetanol and isoquinoline derivatives are the products of the photolysis of α-methoxy and α-dialkylaminochalcone, respectively. The differences in the photoreactivity of these molecules are discussed and the conformational control on the Hγ abstraction process by the excited carbonyl function in these conjugated enones is analyzed.     

边坡大距离整体滑移的模拟研究

边坡整体滑移模拟是迄今未被解决的一个课题。文章通过构制一个专门的滑面单元, 采用数值模拟的原理实现了对粘滑类边坡失稳的大距离滑移模拟; 采用分析模拟法实现了对脆性滑移类边坡失稳滑移的模拟, 并开发了相应的软件。     

The neuroblast and angioblast chemotaxic factor SDF-1 (CXCL12) expression is briefly up regulated by reactive astrocytes in brain following neonatal hypoxic-ischemic injury

Background  

Stromal cell-derived factor 1 (SDF-1 or CXCL12) is chemotaxic for CXCR4 expressing bone marrow-derived cells. It functions in brain embryonic development and in response to ischemic injury in helping guide neuroblast migration and vasculogenesis. In experimental adult stroke models SDF-1 is expressed perivascularly in the injured region up to 30 days after the injury, suggesting it could be a therapeutic target for tissue repair strategies. We hypothesized that SDF-1 would be expressed in similar temporal and spatial patterns following hypoxic-ischemic (HI) injury in neonatal brain.     

Dehalogenation of α -haloketones and vic-dibromides with nickel boride

α-Haloketones and $\text{vic}$-dibromides are converted to the corresponding ketones and alkenes respectively with nickel boride generated $\text{in situ}$ from sodium borohydride and nickel chloride.