Molecular architecture of oligothiophene on a highly oriented pyrolytic graphite surface by employing hydrogen bondings

To achieve a controllable and predictable molecular architecture on a two-dimensional (2D) surface, a series of oligothiophenes with carboxylic groups and alkane chains were synthesized. The alkane chains and carboxylic groups, which can form hydrogen bonding, were intentionally designed in different positions of the oligothiophenes. The resulted molecular architectures by using the so-prepared oligothiophenes on a highly oriented pyrolytic graphite (HOPG) surface were investigated by scanning tunneling microscopy (STM) and density functional theory (DFT). It is found that the hydrogen bonding plays an essential role in the formation of the ordered assemblies. A controlled 2D molecular assembly could be fabricated by using hydrogen bondings.     

Yb（OTf）3-catalyzed synthesis of pyrroles under solvent-free conditions

A Yb(OTf)_3-catalyzed approach for the synthesis of pyrroles under solvent-free conditions was achieved,which could afford the desired products with yields ranged from moderate to excellent.     

Oxyphyllones A and B,novel sesquiterpenes with an unusual 4,5-secoeudesmane skeleton from Alpinia oxyphylla

Two novel 4,5-secoeudesmane sesquiterpenoids,oxyphyllones A(1) and B(2) were isolated from the fruits of Alpinia oxyphylla.Their structures were established by spectroscopic methods including 1D and 2D NMR spectra.These two compounds are the first example of naturally occurring sesquiterpenoids with a 4,5-secoeudesmane skeleton in the family of Zingiberaceae and oxyphyllone A(1) is the first 4,5-secoeudesmane type of 13-norsesquiterpenoid.Compounds 1 and 2 exhibited no cytotoxicities against three cancer...     

不变测度及其计算

用统计方法研究混沌动力系统时需要藉助不变测度理论．本文通过引进Ｆｒｏｂｅｎｉｕｓ－Ｐｅｒｏｎ算子，概述了一类绝对连续不变测度的存在条件与计算现状     

On Polynomial Maximum Entropy Method for Classical Moment Problem

The maximum entropy method for the Hausdorff moment problem suffers from ill conditioning as it uses monomial basis {1,$x$,$x^2$,···,$x^n$}. The maximum entropy method for the Chebyshev moment probelm was studied to overcome this drawback in [4]. In this paper we review and modify the maximum entropy method for the Hausdorff and Chebyshev moment problems studied in [4] and present the maximum entropy method for the Legendre moment problem. We also give the algorithms of converting the Hausdorff moments into the Chebyshev and Lengendre moments, respectively, and utilizing the corresponding maximum entropy method.