Effective mass of kaons in hyperon-rich matter

By including the scalar isovector meson delta, we extend the relativistic mean field model and the one-boson exchange model of changing K-meson in the framework of Schaffner's relativistic mean field model. We re-consider the coupling constants for the interactions between the meson and the baryon and the interactions of the K meson with different mesons as well in various parameter sets. Using our model, we discuss the effective masses of K mesons in the hyperon-rich nuclear matter. We find that the density modification of the K meson mass in the strange nuclear matter is smaller than that in the pure nuclear matter. The influence of the scalar isovector meson 6 on the effective mass of kaon is rather evident. But the extent of the influence is different in different parameter sets.

Migration of neutral solutes by double stepwise gradient elution in capillary electrochromatography

Characteristics of electroosmotic flow (EOF) and the migration of neutral solutes under double stepwise gradient elution in capillary electrochromatography were studied systematically. EOF velocity proved to be the function of operation time changing with the introduction of the second mobile phase. Accordingly, the retention of components also changed. The migration of neutral solutes was studied under the following three situations; A, components eluted when the column was filled only with the first kind of mobile phase; B, solutes eluted still in the first kind of mobile phase while at that time two kinds of mobile phase coexisted in the column and C, samples eluted in the second kind of mobile phase. Equations to describe the retention times of components under these three kinds of conditions were deduced and applied to predict the retention times of 12 aromatic compounds. Relative errors between experimental and calculated values were below 5.0%, which proved the reliability of the equations. In addition, parameters that might affect the retention time of solutes, such as the transferring time of mobile phase vials, the capacity factors of components and EOF velocities two steps were studied systematically (C) 2001 Elsevier Science B.V. All rights reserved.

论窖灌农业中水窖的配置模式与窖水高效利用技术

针对黄土高原蓬勃发展的窖灌农业 ,提出3种水窖配置模式 :峁顶光头式 ;路旁葡萄串式和场、院、凹地单点式。为了高效利用水窖集蓄的雨水资源 ,文中推荐自压微灌、外动力加压微灌、坑灌和水肥穴灌等4种窖水高效利用技术。

Evaluation of flavonoids binding to DNA duplexes by electrospray ionization mass spectrometry

In this study, electrospray ionization mass spectrometry (ESI-MS) was used to investigate the binding interactions of ten flavonoid aglycones and ten flavonoid glycosides with DNA duplexes. Relative binding affinities of the flavonoids toward DNA duplexes were estimated based on the fraction of bound DNA. The results revealed that the 4'-OH group of flavonoid aglycones was essential for their DNA-binding properties. Flavonoid glycosides with sugar chain linked on ring A or ring B showed enhanced binding toward the duplexes over their aglycone counterparts, whereas glycosylation of the flavonol quercetin on ring C exhibited a less pronounced effect.

Theoretical investigation of small lathanum carbide clusters

LaC2+, LaC22+, LaC3 and LaC3- clusters have been studied using B3LYP density functional method. Four isomers with C-2v, C-s, C-infinity v and D-infinity h symmetry were presented for LaC2+ and LaC22+. Meanwhile, two spin states, namely, singlet and triplet for LaC2+, doublet and quartet for LaC22+ were considered The results indicated that ring isomers with C-2v and C-s symmetry are the most stable for La-C2(+) at both spin states and for LaC22+ at quartet state. Whereas for LaC22+ at doublet state, linear isomer with C-infinity v symmetry is energetically favored, For LaC3 and LaC3- clusters,, three isomers have been presented for each cluster, that is, two ring isomers with C-2v symmetry ( in one of them, La forms two single bonds with two carbons, and in another, La forms a double bond with carbon), and one linear isomer with C-infinity v symmetry. The results revealed that the ring isomer in which La forms two single bonds with carbons is the lowest in energy.

Electrochemical studies of lipophilic ion transport through BLM. The influence of sterols on its transport

Cyclic voltammetry was employed to study the influence of sterols on the lipophilic ion transport through the BLM. The mole fraction of the sterols (cholesterol, oxidized cholesterol). as referred to total lipid, was varied in a range of 0-0.8. Data demonstrate that a thin-layer model is suitable to this BLM system. By this model, the number of charges transported per lipophilic ion, the concentration of the ion in the membrane bulk phase and the aqueous/membrane phase partition coefficient could be calculated. These parameters proved that sterols had an obvious influence on the lipophilic ion transport. Cholesterol had a stronger influence on the ion transport than oxidized cholesterol. Its incorporation into egg lecithin membranes increased the partition coefficient beta of the ion up to more than 3-fold. Yet, oxidized cholesterol incorporated into egg lecithin membranes only increased the beta up to less than 2-fold, and the beta had no great variation at different oxidized cholesterol mole fractions. The higher beta obtained was partly due to the trace amount of solvent existing in the core of the lipid bilayers. At the different sterol mole fractions, combining the change of beta with the change of peak current, we also concluded that sterols had somewhat inhibiting effect on the ion transport at the higher sterols mole fraction (>0.4). These results are explained in terms of the possible change of dipole potential of the membrane produced by sterols and the decrease of the membrane fluidity caused by the condensation effect of sterols and the thinning effect caused by sterols. The substituting group (in the oxidized cholesterol) had some inhibiting effects on the ion transport at higher mole fractions (oxidized cholesterol mole fraction >0.4).

阳离子交换型聚合物AQ薄膜修饰碳纤维电极及伏安行为

本文成功地制备了Eastman-AQ-55D聚合物修饰碳纤维电极,用循环伏安法探讨了一些实验参数的影响,并对Ru(NH_3)_6~(3+)、甲基紫精进行了分析,结果表明,AQ-55D修饰的微电极稳定性好,修饰方法简单,灵敏度和选择性都有一定的提高,Ru(NH_3)_6~(3+)、甲基紫精的峰电流与浓度在1.2×10~(-6)～1.2×10~(-5)mol/L、1.7×10~(-6)～1.4×10~(-5)mol/L范围内呈线性关系,其相关系数分别为0.999、0.998.利用此电极测定了几种离子在膜中的扩散系数.

RESEARCHES ON CHEMICALLY MODIFIED ELECTRODES - ELECTROCHEMISTRY OF 1-12 PHOSPHOMOLYBDIC HETEROPOLY ANION FILM MODIFIED ELECTRODE

A monolayer of 1:12 phosphomolybdic anion (PMo_(12)) was modified electrochemically on a glassy carbon electrode and its electrochemical behavior was studied with cyclic voltammetry (CV). It is shown that PMo_(12) film is adsoibed strongly on the surface of glassy carbon electrodes, H~+ ions in the solution plays an important role in the electrochemical processes of PMo_(12) film modified electrodes, whereas other anions, such as Cl~-, NO_3~-, SO_4~(2-), ClO_4~- and PO_4~(3-) etc., do not take par...

化学修饰电极的研究——1:12磷钼杂多阴离子薄膜修饰电极的电化学性质

自从化学修饰电极问世以来,在电极反应过程、电极效应以及扩展修饰薄膜类型方面进展较快。目前研究较多的是聚合物薄膜修饰电极,由于结构和化学性能的特点,对无机物修饰电极的研究也已引起重视。杂多酸具有很好的氧化还原性能,而且可通过改变化学组成的方法使杂多酸的氧化还原电位在很宽范围内变动。杂多酸可发生多电子还原反应形成“杂多蓝”,所以杂多酸或其盐类修饰在电极上有可能发生电催化和电色效应。目前杂多酸修饰电极的报道甚少。本文研

Purification and characterization of agarases from a marine bacterium Vibrio sp. F-6

Marine bacterium Vibrio sp. F-6, utilizing agarose as a carbon source to produce agarases, was isolated from seawater samples taken from Qingdao, China. Two agarases (AG-a and AG-b) were purified to a homogeneity from the cultural supernatant of Vibrio sp. F-6 through ammonium sulfate precipitation, Q-Sepharose FF chromatography, and Sephacryl S-100 gel filtration. Molecular weights of agarases were estimated to be 54.0 kDa (AG-a) and 34.5 kDa (AG-b) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH values for AG-a and AG-b were about 7.0 and 9.0, respectively. AG-a was stable in the pH range of 4.0-9.0 and AG-b was stable in the pH range of 4.0-10.0. The optimum temperatures of AG-a and AG-b were 40 and 55 degrees C, respectively. AG-a was stable at temperature below 50 degrees C. AG-b was stable at temperature below 60 degrees C. Zn2+, Mg2+ or Ca2+ increased AG-a activity, while Mn2+, Cu2+ or Ca2+ increased AG-b activity. However, Ag+, Hg2+, Fe3+, EDTA and SDS inhibited AG-a and AG-b activities. The main hydrolysates of agarose by AG-a were neoagarotetraose and neoagarohexaose. The main hydrolysates of agarose by AG-b were neoagarooctaose and neoagarohexaose. When the mixture of AG-a and AG-b were used, agarose was mainly degraded into neoagarobiose.

长江口附近海域环流及大黄鱼鱼卵、仔鱼输运和扩散的数值模拟

本文利用数值方法对长江口及其附近海区的环流场以及大黄鱼鱼卵、 仔鱼的输运和扩散现象进行了模拟。环流场的模拟使用的是POM模式。在σ坐标系下，建立了一个三维斜压诊断模式，考虑了海底地形、台湾暖流、东海沿岸流、长江径流等因系的影响。由于实际工作的需要，本文选择了小区域、细网格。通过数值模拟，本文得到一个与实际较相符的流场，其特征主要有：长江冲淡水转向，台湾暖流沿深水槽运动，杭州湾表层水的北进南出现象等。通过数值实验现地形、风场、长江径流等因系对流场的影响较大。在环流模拟的基础上，本文将鱼卵、仔鱼“放置”在计算得到的表层流场中，通过求解对流扩散方程，模拟了大大黄鱼鱼卵、仔鱼的输运和扩散过程。发现鱼卵、仔鱼主要沿流场中高速流动区的主轴方向被动漂移。在强流区鱼卵、仔鱼的扩散效应远不如被动漂移明显，而在弱流区，其扩散范围相对较大。

相关风险因子对高原鼠兔摄食行为的影响

研究了捕食风险环境中集群和洞口距离对高原鼠兔摄食行为的影响。结果表明 ,集群数量的增加不仅降低了警觉行为 ,同时也减少了摄食行为 ,在高风险环境中 ,集群为1时的取食行为强度最大 ,低风险环境中，为0时最大。警觉行为主要出现在距洞口 2m的范围内 ,其行为强度与洞口距离呈负相关 ,当洞口距离大于3m时，风险处理区的高原鼠兔几乎无警觉行为出现 ,且该处理区的取食区域几乎压缩在洞口旁。研究结果表明 ,在捕食风险环境中 ,高原鼠兔摄食行为与集群和洞口距离之间具有复杂的关系 ,其行为决策反映了降低风险与摄取食物间的权衡 ,行为目标是在降低捕食风险的同时尽可能地取食食物。