对DEPT实验技术的一点改进

将DEPT -1 3 5实验的 1 3 5° -脉冲分成一个 90°脉冲和一个 4 5°脉冲 ,通过相位循环 ,设计了两个新的DEPT实验分别称为DEPT-90 -4 5和DEPT -90 +4 5。DEPT -90 -4 5谱中只有 -CH3的吸收峰。DEPT -90 +4 5谱中没有 >CH -的吸收峰 ,其 -CH3为正信号 ,-CH2 -为负信号。实验结果显示 ,对比DEPT -90谱 ,这两个新的DEPT谱中完全没有所选基团之外的残余干扰信号 ,而且DEPT -90 -4 5谱比DEPT-90 +4 5谱更好。     

反BIRD在NMR谱编辑中的应用

建议了一个新的双线性旋转去偶序列 ,称为反BIRD (inverse -BIRD) ,其去偶作用与碳连质子的数目有关。将反BIRD结合到INEPT实验中 ,得到了INEPT -iBIRD实验技术 ,它可用于核磁共振碳谱的编辑与简化     

Prey-predator systems with intertwined basins of attraction

In this article, we show the existence of intertwined basins of attraction for a class of prey-predator systems, which improves the extant results by deleting some crucial and hard testing conditions.     

The α-limit sets of a unimodal map without homtervals

Let f:I→I be a unimodal map on I without homtervals. We characterize the α-limit set of each point in I by considering the consecutive renormalization process of f.     

Preliminary Investigation of Sintered Plates Bonded or End-Capped with Phenyl for Planar Electrochromatography

JPC – Journal of Planar Chromatography – Modern TLC - Two new types of reversed-phase sintered plate have been prepared used in planar electrochromatography (PEC). One was bonded with...     

Copper‐catalyzed one‐pot synthesis of propargylamines via C?H activation in PEG

An efficient and convenient three‐component A³ coupling reaction of aldehyde, amine and alkyne via C? H activation with CuI alone as the catalyst in PEG is developed, providing a wide range of propargylamines with yields ranging from moderate to excellent. Additionally, the catalyst system was recovered and reused several times without evident loss in activity. Copyright © 2010 John Wiley & Sons, Ltd.     

Optically active core/shell nanoparticles prepared using self‐assembled polymer micelle as reactive nanoreactor

This article reports on optically active core/shell nanoparticles constituted by chiral helical polymers and prepared by a novel approach: using self‐assembled polymer micelles as reactive nanoreactors. Such core/shell nanoparticles were composed of optically active helical‐substituted polyacetylene as the core and thermosensitive poly(N‐isopropylacrylamide) as the shell. The synthetic procedure is divided into three major steps: (1) synthesis of amphiphilic diblock copolymer bearing polymerizable C[tbond]C bonds via atom transfer radical polymerization, followed by (2) self‐assembly of the diblock copolymer to form polymer micelles; and (3) catalytic emulsion polymerization of substituted acetylene monomer conducted using the polymer micelles as reactive nanoreactors leading to the core/shell nanoparticles. The core/shell nanoparticles simultaneously exhibited remarkable optical activity and thermosensitivity. The facile, versatile synthesis methodology opens new approach toward preparing novel multifunctional core/shell nanoparticles.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A general solution for static piezothermoelastic problems of crystal class 6mm solids

In this paper, a general solution for three-dimensional static piezothermoelastic problems of crystal class 6mm solids is presented. The general solution involves four piezoelastic potential functions and a piezothermoelastic potential function, of which four piezoelastic potential functions are governed by weighted harmonic differential equations. Compared with the general solution given by Ashida et al., in which seven potential functions are introduced, the general solution proposed in the present paper is more rigorously derived. Moreover, it has a simple form and is convenient for application. As an illustrative example, the problem of a pyroelectric half-space subjected to axisymmetric heating is studied. Numerical results of displacements stresses, electric potential and electric displacements are obtained for a cadmium selenide half-space. Thermally induced displacements and stress distribution are compared with those obtained for the same material without piezoelectric and pyroelectric effects. Project supported by the National Natural Science Foundation of China (19872060).     

Thermal and pH‐sensitive gold nanoparticles from H‐shaped block copolymers of (PNIPAM/PDMAEMA)‐b‐PEG‐b‐(PNIPAM/PDMAEMA)

Well‐defined H‐shaped pentablock copolymers composed of poly(N‐isopropylacrylamide) (PNIPAM), poly(N,N‐dimethylaminoethylacrylamide) (PDMAEMA), and poly(ethylene glycol) (PEG) with the chain architecture of (A/B)‐b‐C‐b‐(A/B) were synthesized by the combination of single‐electron‐transfer living radical polymerization, atom‐transfer radical polymerization, and click chemistry. Single‐electron‐transfer living radical polymerization of NIPAM using α,ω azide‐capped PEG macroinitiator resulted in PNIPAM‐b‐PEG‐b‐PNIPAM with azide groups at the block joints. Atom‐transfer radical polymerization of DMAEMA initiated by propargyl 2‐chloropropionate gave out α‐capped alkyne‐PDMAEMA. The H‐shaped copolymers were finally obtained by the click reaction between PNIPAM‐b‐PEG‐b‐PNIPAM and alkyne‐PDMAEMA. These copolymers were used to prepare stable colloidal gold nanoparticles (GNPs) in aqueous solution without any external reducing agent. The formation of GNPs was affected by the length of PDMAEMA block, the feed ratio of the copolymer to HAuCl₄, and the pH value. The surface plasmon absorbance of these obtained GNPs also exhibited pH and thermal dependence because of the existence of PNIAPM and PDAMEMA blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010