Molecular dynamics of CO in few-cycle laser fields

We experimentally study the ionization, fragmentation and Coulomb explosion of CO using 6 fs laser pulses. Different from previous observations in tens or hundreds of femtoseconds laser pulses, strong charge asymmetric dissociation and CO²⁺ are observed in the current intense few-cycle laser field.     

Fluorescence-quenching of Tryptophan Ion-18-crown-6 Complex——A Different Observation from Its Neutral Counterpart

It is well-known that primary amines form inclusive complexes with crown ethers. This kind of noncova-lently inclusive complexes,exemplified tryptophan complex with 18-crown-6,was studied by combination of two experimental methods,fluorimetry and mass spectrometry,with theoretical calculation. Fluorescence intensity of tryptophan in the absence and the presence of 18-crown-6 in aqueous HAc-NaAc buffer solution at pH=3.73 has been studied by fluorometry. The fluorescence intensity decreases significantly wit...     

联二烯丁基硫醚衍生物合成呋喃的反应

本文报道以联二烯丁基硫醚为起始物的呋喃衍生物的合成方法.实验结果表明,β-联二烯丁基硫醚醇在氢化钠的作用下以很高的收率环化生成一个苯硫基离去的呋喃产物,β-联二烯丁基硫醚醛与外加亲核试剂作用后能得到多一个取代的类似呋喃产物,而β-联二烯丁基硫醚酮在P2O5的促进下也能环化生成呋喃衍生物.     

The role of central ion in chiral recognition by taking phenylalanine as an example

Chiral recognition of phenylalanine (Phe) was achieved in the gas phase by electrospray ionization Q-TOF tandem mass spectrometry. In this method, two central ions, i.e. proton and divalent copper, were used and chiral crown ether, (+)-2,3,11,12-tetracarboxylic acid-18-crown-6 (18-C-6-TCA), was used as a chiral host. Dimeric complexes were readily formed by electrospray ionization of a methanol/water (50/50, V/V) solution containing central ions, Phe and 18-C-6-TCA. The dimeric complex included proton-bound (18-C-6-TCA)(Phe)H+ and copper-bound deprotonated [Cu²⁺(18-C-6-TCA)(Phe)-H]⁺ ions were mass selected and then collided with Ar in the CID experiments. The chiral recognition capability of these complexes was evaluated using the relative abundance of daughter ion to parent ion. A higher degree of chiral recognition ability was observed with Cu²⁺ compared to that of H⁺. Different central ions exhibited distinctive dissociation pathways and unique chiral recognition characteristics. The chiral recognition mechanism was also discussed in detail with the help of the structure of copper-bound complex predicted by theoretical calculation.     

Effect of gating currents of ion channels on the collective spiking activity of coupled Hodgkin-Huxley neurons

Based on the coupled stochastic Hodgkin-Huxley neurons, we numerically studied the effect of gating currents of ion channels, as well as coupling and the number of neurons, on the collective spiking rate and regularity in the coupled system. It was found, for a given coupling strength and with a relatively large number of neurons, when gating currents are applied, the collective spiking regularity decreases; meanwhile, the collective spiking rate increases, indicating that gating currents can aggravate the desynchronization of the spikings of all neurons. However, gating currents caused hardly any effect in the spiking of any individual neuron of the coupled system. This result, different from the reduction of the spiking rate by gating currents in a single neuron, provides a new insight into the effect of gating currents on the global information processing and signal transduction in real neural systems. Supported by the Science Foundation of Ludong University (Grant Nos. 23140301, L20072805)     

GPC-多检测联用技术测定聚己内酯分子量及其分布

介绍一种用于生物可降解高分子材料聚已内酯(PCL)及其改性高分子的分子量和分子量分布测定的GPC-示差折光(RI)-示差黏度(DV)-直角光散射(RALLS)多检测联用技术.叙述了该方法的实验原理,并对测试过程中的有关技术及实验结果进行了讨论.该方法可准确测定聚己内酯(PCL)及其改性高分子的分子量及其分布、特性黏度分布、Mark-Houwink方程系数以及高分子尺寸等重要参数.通过对窄分布PS标样验证,分子量测定结果的相对误差在1%之内.     

随机环境中具有随机控制函数的受控分枝过程

对随机环境中具有随机控制函数的受控分枝过程进行了更为详尽的概率描述和直观解释;证明了此过程是时齐马氏链和随机环境中的马氏链,并对其概率母函数及矩量进行了讨论。     

Stochastic comparison and preservation of positive correlations for Lévy-type processes

The stochastic comparison and preservation of positive correlations for Levy-type processes on R^d are studied under the condition that Levy measure v satisfies f{0〈｜z｜≤1）｜z｜｜v（x, dz） - v（x, d（-z））｜ 〈 ∞, x∈ R^d, while the sufficient conditions and necessary ones for them are obtained. In some cases the conditions for stochastic comparison are not only sufficient but also necessary.     

关于有能力限制的指派问题的一点注记

首先讨论了有能力限制的不平衡指派问题的转化和最优性,并提出了采用最小费用最大流的方法求解该问题.     

上三角无穷维Hamilton算子点谱的对称性

In this paper, by using characterization of the point spectrum of the upper triangular infinite dimensional Hamiltonian operator H, a necessary and sufficient condition is obtained on the symmetry of σP（A） and σ1/P（-A^＊） with respect to the imaginary axis. Then the symmetry of the point spectrum of H is given, and several examples are presented to illustrate the results.