Inclusive production of vector mesons in π+ p interactions at 250 GeV/c

We report on a study of ρ⁰, ρ⁺, ω, \(\bar K^{*0} (892)\) andK ^*0 (892) inclusive production in π⁺ p interactions at 250 GeV/c, for ρ⁺, \(\bar K^{*0} (892)\) for the first time in a π⁺ p experiment. The data are compared withK ⁺ p data in the same experiment, with results of other experiments and with quark-parton models. Interesting differences are found between ρ^+,0 and ω production.     

光学双稳性临界点的相变行为

本文详细地讨论了光学双稳性(OB)的临界现象。理论分析主要以忽略量子涨落的Fokker-Plank方程的静态解为基础。结果发现,OB的临界现象可以纳入Landau二级相变理论的框架,并且有关临界指数之间的关系也服从标度律。 关键词：     

Recent Progress in the Preparation of Functional Methacrylate Polymers

Application of anionic polymerization and group transfer polymerization to the synthesis of methacrylate polymers with one or two functional endgroups and with functional groups in the side chain is described. Success in the preparation of end-functional polymers depends largely on the absence of chain transfer and chain termination reactions. The higher stability of living chains in group transfer polymerization at temperatures as high as 100°C makes it the preferred route to functional polymers.     

Lead Structures for New Antibacterials: Stereocontrolled Synthesis of a Bioactive Muraymycin Analogue

Naturally occurring muraymycin nucleoside antibiotics represent a promising class of novel antibacterial agents. The structural complexity suggests the investigation of simplified analogues as potential lead structures, which can then be further optimized towards highly potent antimicrobials. Herein we report studies on muraymycin‐derived potential lead structures lacking an aminoribose motif found in most naturally occurring muraymycins. We have identified a 5′‐defunctionalized motif to be ideal in terms of stability and chemical accessibility and have synthesized a full‐length muraymycin analogue based on this structure using a novel fully stereocontrolled route. The obtained 5′‐deoxy analogue of the natural product muraymycin C4 showed good inhibitory properties towards the bacterial target protein MraY, sufficient pharmacokinetic stability and no cytotoxicity against human cells, thus making it a promising lead for antibacterial drug development.     

Polylactones 27. Anionic polymerization of L-lactide. Variation of endgroups and synthesis of block copolymers with poly(ethylene oxide)

L-Lactide was polymerized in toluene with various alkoxide initiators. These initiators were prepared in situ from potassium t.-butoxide and primary or secondary alcohols such as tetradecanol, diethylene glycol butyl ether, menthol or testosteron. All these alcohols were incorporated as ester endgroups into the polylactide chain. However ¹H-NMR spectroscopy proves the existence of more OH-endgroup than ester endgroups. This finding and 10–20% racemization observed for all anionic polymerizations suggest that chain-transfer reactions with the monomer via deprotonation take place. When poly(ethylene glycol) monomethyl ether in combination with KOtBu was used as initiator, twoblock copolymers were obtained. With poly(ethylene glycol) A-B-A-triblock copolymers could be synthesized. The quantitative reaction of the poly(ethylene glycol)s with L-lactide could be proven by both ¹H NMR spectroscopy and gelpermeation chromatography. DSC-measurements show that depending on their lengths either the polylactide or the poly(ethylene oxide)blocks can crystallize. Due to partial racemization the melting temperatures (T_m) of the poly(L-lactide) blocks did not exceed 155°C.     

氮氧自由基研究XVII:水溶液中哌啶氮氧自由基的电化学行为和自衰变动力学研究

循环伏安法研究表明,2,2,6,6-四甲基-4-羟基哌啶-1-氧自由基和2,2,6,6-四甲基-4-氧哌啶-1-氧自由基,在水溶液中的单电子氧化电极反应的可逆性随介质酸性,扫描速度和自由基浓度增加而增加,表明电极氧化产物可进一步发生化学反应.