二元液体中动力学不均匀性与脆性的关系(英文)

过冷液体和玻璃有着复杂的结构和动力学性质.目前我们对他的研究是很不够的.当液体的温度远低于它的熔点时,它呈现非指数的驰豫行为.大量的实验和分子动力学模拟的研究表明这种非指数的驰豫行为是由动力学不均匀性引起的.计算机模拟已经提供了一些过冷液体的动力学不均匀性的相关信息.而Agell认为,液体可以粘度随温度的变化分为强,弱液体两种.脆性表示的是随着玻璃态的接近液体性质(如黏度)的改变速度.在这篇文章中我们通过模拟了三种不同二元Lennard-Jones液体,计算了它们的非高斯参数,脆性系数等一些参数,研究动了力学不均匀性和脆性的关系.得出了系统的脆性系数越小他的结构就越稳定,动力学不均匀性就越强的结论.     

非线性多滞量延迟微分方程的指数稳定性

收稿研究了一类带多个小滞量的非线性延迟微分方程的指数稳定性,证明了在适当条件下,上述延迟微分方程可保留相应常微分方程的指数稳定性.所获稳定性判据修正和扩展了已有延迟微分方程的相关结果.在文末,数值例子进一步阐明了其稳定性理论.     

常压电喷雾离子化的机理及应用

作为最有前景的分析仪器之一,质谱技术已在药物、食品、环境、人类健康、国家安全及相关领域展现出广阔的应用前景。不同种类的分析物具有多种特征,这为直接离子化及质谱分析增加了难度。常压敞开式离子源是近年来新兴的一种离子源,这类离子源具有无需复杂的样品前处理、操作方便、快速、非破坏性、灵敏度及特异性好、能实现实时原位、高通量分析等特点。本文综述了基于电喷雾离子化(ESI)原理的各种离子源的电离机理、特征及应用,展望了常压敞开式离子源的发展趋势。     

积分问题中分段估值的解题方法

细致分析和研究积分不等式、积分值序列的极限、含参变量积分的极限等若干方面诸多问题的解决过程,提炼出其中蕴含的一类解题方法--分段估值法.     

一类具有逐段常变量微分方程的渐近概周期解

利用差分方程的渐近概周期序列解，讨论了一类具有逐段常变量微分方程的渐近概周期解的存在性．     

华沙圈上连续映射的distality与等度连续性

设W为华沙圈,f:W→W为连续映射.本文得到了f为distal的一个刻画并且讨论了f的distality与等度连续性的关系.证明了:(i)f是distal的当且仅当f为恒等映射.(ii)如果f为满射,则f是distal的当且仅当f为等度连续的.     

第29届奥运会中外男篮技术成绩统计分析

本文对第29届奥运会中国男篮同相遇对手的技术成绩指标,进行了相关性、偏相关、回归分析等多元统计分析,通过回归方程找出影响总得分的主要因素,利用多因变量的线性模型对29届中国队与对手整体上进行比较,并对中国队在28、29两届上进行了整体的比较。结果显示:29届奥运会上中国队和对手在整体水平上有一定的差异;和28届相比,中国队前后差异不大,说明中国男篮进步幅度不是太大。     

Microwave synthesis of gibberellin acid 3 magnetic molecularly imprinted polymer beads for the trace analysis of gibberellin acids in plant samples by liquid chromatography-mass spectrometry detection

In this study, novel GA3 magnetic molecularly imprinted polymer (mag-MIP) beads were synthesized by a microwave irradiation method, and the beads were applied for the trace analysis of gibberellin acids (GAs) in plant samples including rice and cucumber coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS). The microwave synthetic procedure was optimized in detail. In particular, the interaction between GA3 and functional monomers was further studied for the selection of the optimal functional monomers during synthesis. It can be seen that the interaction between GA3 and acrylamide (AM) finally selected was stronger than that between GA3 and other functional monomers. GA3 mag-MIP beads were characterized by a series of physical tests. GA3 mag-MIP beads had a porous and homogeneous surface morphology with stable chemical, thermal and magnetic properties. Moreover, GA3 mag-MIP beads demonstrated selective and specific absorption behavior for the target compounds during unsaturated extraction, which resulted in a higher extraction capacity (～708.4 pmol for GA3) and selectivity than GA3 mag-non-imprinted polymer beads. Finally, an analytical method of GA3 mag-AM-MIP bead extraction coupled with HPLC-MS detection was established and applied for the determination of trace GA1, GA3, GA4 and GA7 in rice and cucumber samples. It was satisfactory that GA4 could be actually found to be 121.5 ± 1.4 μg kg(-1) in real rice samples by this novel analytical method. The recoveries of spiked rice and cucumber samples were found to be 76.0-109.1% and 79.9-93.6% with RSDs of 2.8-8.8% and 3.1-7.7% (n = 3), respectively. The proposed method is efficient and applicable for the trace analysis of GAs in complicated plant samples.