Versuche zur enantiomerenreinen Synthese des Chatancins, 1. Mitt. Synthese von (1R,2S,6S,7R,8S,3′S)-2-(4′-Benzyloxy-3′-methylbutoyl)-7-hydroxy-8-isopropyl-1-methylbicyclo [4.4.0]decan-4-on

Summary Our first target on the way towards the synthesis of enantiomerically pure chatancin is the preparation of the title compound. The cycloadduct of 5,5-dimethoxy-1,2,3,4-tetrachlorocyclopentadiene and thymoquinone is stereo- and regioselectively reduced to the tricyclic ketoalcohol4, which by nucleophilic cyclisation and reductive removal of the keto group as well as the chlorine atoms yielded a tetracyclic dimethoxyketal. Acidic hydrolysis freed the keto group, which now was treated with a chiral lithium alkyl compound derived from methyl (R)-2-methyl-3-hydroxypropionate in few steps. The resulting stereomeric tertiary alkohols were fragmented and the decalinones thus obtained separated. X-ray analysis permitted the determination of the absolute configuration of these decalinone derivatives.

     

On the semisimplicity conjecture and Galois representations

The semisimplicity conjecture says that for any smooth projective scheme over a finite field , the Frobenius correspondence acts semisimply on , where is an algebraic closure of . Based on the works of Deligne and Laumon, we reduce this conjecture to a problem about the Galois representations of function fields. This reduction was also achieved by Laumon a few years ago (unpublished).

     

C3+与Ne碰撞过程纯电离绝对截面的测量和研究

介绍了离子-原子碰撞过程中双微分绝对截面的计算方法.利用符合技术测量了中能区C³⁺+Ne碰撞系统的纯电离微分绝对截面. 将实验结果与多体经典蒙特卡罗方法计算结果进行对比后发现，纯电离截面随入射能量变化的趋势基本一致，对理论与实验产生差异的原因作了分析. 对多重电离的电离机制分析表明：高价态的反冲离子主要来自于俄歇贡献；随着入射能量的升高，电子-电子间的库仑作用也逐渐显现. 此实验方法可以用于相同实验装置上的各种反应出射道的绝对截面测量，入射离子种类及入射离子能量范围将得到拓展. 关键词： 离子-原子碰撞 绝对截面 纯电离     

关于三项纯指数Diophantine方程ax+by=cz

设a、b、c是互素的正整数.本文证明了:当a b2l-1=c2,b≡5(mod 12),c是适合c≡-1(mod b2l)的奇素数,其中l是正整数时,方程ax by=cz仅有正整数解(x,y,z)=(1,2l-1,2).     

无序复杂系统中的序--2021年诺贝尔物理学奖解读

本文首先简要介绍了什么是玻璃和自旋玻璃,然后回顾了自旋玻璃理论的发展,特别是帕里西对自旋玻璃理论的贡献及该理论在其它领域的应用.最后简要介绍了帕里西在界面随机生长和随机共振方面的重要贡献.     

我国丝绸之路经济带的金融效率研究

我国丝绸之路经济带作为连接中国与亚太经济圈、中国与欧洲经济圈的桥梁,其沿线城市的金融经济发展起着非常重要的纽带作用.利用DEA模型对该经济带的金融效率进行评估,计算并分析了沿线九大城市金融发展的技术效率、纯技术效率和规模效率,将该经济带城市分为三个层次,结合该经济带的发展情况,给出相应的政策建议.     

The mechanism of producing energy-polarization entangled photon pairs in the cavity-quantum electrodynamics scheme

We investigate theoretically two photon entanglement processes in a photonic-crystal cavity embedding a quantum dot in the strong-coupling regime. The model proposed by Johne et al. (Johne R, Gippius N A, Pavlovic G, Solnyshkov D D, Shelykh I A and Malpuech G 2008 Phys. Rev. Lett. 100 240404), and by Robert et al. (Robert J, Gippius N A and Malpuech G 2009 Phys. Rev. B 79 155317) is modified by considering irreversible dissipation and incoherent continuous pumping for the quantum dot, which is necessary to connect the realistic experiment. The dynamics of the system is analysed by employing the Born–Markov master equation, through which the spectra for the system are computed as a function of various parameters. By means of this analysis the photon-reabsorption process in the strong-coupling regime is first observed and analysed from the perspective of radiation spectrum and the optimal parameters for observing energy-entangled photon pairs are identified.     

Model‐free multivariate curve resolution combined with model‐based kinetics: algorithm and applications

Multivariate curve resolution techniques are powerful tools to extract from sequences of spectra of a chemical reaction system the number of independent chemical components, their associated spectra, and the concentration profiles in time. Usually, these solutions are not unique because of the so‐called rotational ambiguity. In the present work, we reduce the non‐uniqueness by enforcing the consistency of the computed concentration profiles with a given kinetic model. Traditionally, the kinetic modeling is realized in a separate step, which follows the multivariate curve resolution procedure. In contrast to this, we consider a hybrid approach that combines the model‐free curve resolution technique with the model‐based kinetic modeling in an overall optimization. For a two‐component model problem, the range of possible solutions is analyzed, and its reduction to a single, unique solution by means of the hybrid kinetic modeling is shown. The algorithm reduces the rotational ambiguity and improves the quality of the kinetic fitting. Numerical results are also presented for a multi‐component catalytic reaction system that obeys the Michaelis–Menten kinetics. Copyright © 2012 John Wiley & Sons, Ltd.