均相钕系催化剂合成窄相对分子质量分布的高顺式-1，4-聚丁二烯

考察了由Nd（vers）3（简称Nd）、Al（i—Bu）2H（简称Al）和Al（i—Bu）2Cl（简称Cl）组成的均相催化剂体系在5L釜中于70℃聚合丁二烯的反应规律，并在2m^3装置上进行了放大试验。结果表明，该均相钕系催化剂具有高的稳定性；Al／Nd（摩尔比）是影响相对分子质量分布的重要因素，当Al／Nd低于20时，产物的相对分子质量分布在3．00以下；改变Nd／Bd（摩尔比）或使用不同组成的Al，可改变聚合产物的门尼黏度，但对相对分子质量分布无明显影响。在2m^3装置上，采用均相钕系催化剂可以得到收率大于90％、相对分子质量分布小于3.00和顺式-1，4-结构摩尔分数大于97．0％的聚丁二烯

Absolute phase control of spectra effects in a two-level medium driven by two-color ultrashort laser pulses

Using a omega-3 omega combination scenario, we investigate the absolute phase control of the spectra effects for ultrashort laser pulses propagating in a two-level medium. It is found that the higher spectral components can be controlled by the absolute phases. In particular, different absolute phase combinations can lead to the buildup or split of the even harmonics. (c) 2006 Elsevier B.V. All rights reserved.

ANODIC-OXIDATION OF HYDRAZINE ON GLASSY-CARBON ELECTRODES IN ACETONITRILE

The anodic oxidation kinetics of hydrazine on glassy carbon electrodes in acetonitrile were examined by cyclic voltammetry, a rotating ring-disc electrode technique and chronoamperometry. The experimental results of the rotating ring-disc electrode prove that hydrazine is oxidized to HN=NH, which cannot be oxidized further in acetonitrile. Hydrazine molecules are adsorbed on the electrode surface. One-third of the adsorbed hydrazine molecules are oxidized to HN=NH and the other two thirds act as proton acceptors. A possible mechanism of hydrazine oxidation is proposed.