邻苯二酚紫退色光度法测定微量锰(Ⅱ)

在硫酸介质中．高锰酸根氧化邻苯二酚紫使其退色，退色程度在一定范围内与高锰酸根加入量成良好的线性关系。据此建立了一种测定微量锰（Ⅱ）的新方法。最大吸收波长λmax＝550nm，表观摩尔吸光系数ε＝4．2×104L·mol-1·cm－1·。锰（Ⅱ）量在0－0．8mg／L范围内符合比耳定律．方法应用于求和面粉中微量锰（Ⅱ）的测定，结果满意。     

Stereoselective nitrenium ion cyclizations: asymmetric synthesis of the (+)-Kishi lactam and an intermediate for the preparation of fasicularin

The asymmetric synthesis of the (+)-Kishi lactam and an intermediate for the preparation of the marine natural product fasicularin is reported. The keystone of this divergent synthesis is the diastereoselective azaspirocyclization of an N-methoxy γ-arylbutanoamide, which is believed to proceed through the intermediacy of an N-acylnitrenium ion.     

Antioxidant Activity of Graft Chitosan Derivatives

Graft chitosan derivatives (CMCTS‐g‐MAAS and CMCTS‐g‐AAS) were prepared by the graft copolymerization of methacrylic acid sodium (MAAS) and acrylic acid sodium (AAS) onto the etherification product of chitosan‐carboxymethyl chitosan (CMCTS). Their antioxidant activity was estimated as superoxide anion scavengers by chemiluminescence techniques. The derivatives with low grafting percentages have a relatively low 50% inhibition concentration (IC₅₀), which could be related to the fact that they have different contents of hydroxyl and amino groups in the polymer chains.

Superoxide radical scavenging activity of CMCTS‐g‐MAAS.     

血液-血管耦合特性与脉搏波传播特性的关系

脉搏波既不可简单地理解为可压缩血液流体中的压力纵波,也不可简单地理解为沿固体血管传播的涨缩位移横波,而是超乎普通想象的流-固耦合和纵波-横波耦合的复杂波。从分析耦合本构关系的新途径出发,本文中提出了一个流-固耦合/纵波-横波耦合的串联模型,可为解读“位数形势”中医脉诊提供更丰富的信息。结果表明,脉搏波耦合系统的等效体积压缩模量K_s以及相应的耦合系统脉搏波传播速度c_s主要依赖于两个无量纲参数：血液-血管模量比K_b(p)/E(p)和薄壁血管径厚比D(p)/h₀,它们因人而异、因人的不同脉搏位置而异。文中定量分析了它们对c_s的影响,显示人体的K_b/E值在10³数量级,从而c_s值在10⁰～10¹ m/s数量级,以适应人体生理生化反应。由临床有创测量,证实脉搏体积横波与脉搏压力纵波是相耦合地以相同速度传播;还显示脉搏波是在其波阵面上具有氧合生化反应的“生物波”。此外,还讨论了“脉压放大”现象与非线性本构关系和与血管分叉处加载增强反射之间的关系,并讨论了Lewis关于重搏波形成的假设。

     

Carrier dynamics in CsPbI3 perovskite microcrystals synthesized in solution phase

Carrier diffusion and recombination kinetics in all-inorganic CsPbI₃ perovskite microcrystals directly synthesized in solution phase are reported.     

Confined Ultrathin Pd‐Ce Nanowires with Outstanding Moisture and SO2 Tolerance in Methane Combustion

An efficient strategy (enhanced metal oxide interaction and core–shell confinement to inhibit the sintering of noble metal) is presented confined ultrathin Pd‐CeO_x nanowire (2.4 nm) catalysts for methane combustion, which enable CH₄ total oxidation at a low temperature of 350 °C, much lower than that of a commercial Pd/Al₂O₃ catalyst (425 °C). Importantly, unexpected stability was observed even under harsh conditions (800 °C, water vapor, and SO₂), owing to the confinement and shielding effect of the porous silica shell together with the promotion of CeO₂. Pd‐CeO_x solid solution nanowires (Pd‐Ce NW) as cores and porous silica as shells (Pd‐CeNW@SiO₂) were rationally prepared by a facile and direct self‐assembly strategy for the first time. This strategy is expected to inspire more active and stable catalysts for use under severe conditions (vehicle emissions control, reforming, and water–gas shift reaction).     

金属螯合亲和色谱中的疏水作用

通过考察盐溶盐和盐析盐浓度对蛋白质在IDA裸柱和金属螯合柱上保留行为的影响,详细研究了金属螯合色谱中的疏水作用,疏水作用的发生、形成的条件以及不同条件下对蛋白质保留值的贡献。实验结果表明,在高浓度和低浓度的盐溶盐以及低浓度盐析盐中,蛋白质在金属螯合柱上的保留主要受静电和配位作用控制,而疏水作用对蛋白质的保留影响很小。对弱亲和性的金属螯合柱以静电作用为主,其大小可用参数Q表征;对强亲和性的IDA-Cu（Ⅱ）柱以配位作用为主。仅在高浓度的盐析盐中,金属螯合柱才呈现较强的疏水作用,支配蛋白质保留。实验证明,金属螯合色谱中疏水作用主要来自固定相间隔臂中的疏水碳链和盐析盐对蛋白质的增疏作用,利用这种疏水作用有可能改善金属螯合色谱分离的选择性。     

沥青基球形活性炭对葡萄糖分子的吸附行为研究

考察了沥青基球形活性炭(PSAC)对葡萄糖分子的吸附行为,以探讨其治疗糖尿病的可能性.在不同吸附时间、不同活性炭用量及不同浓度等条件下,测定沥青基球形活性炭对葡萄糖分子的吸附量,根据Langmuir和Freundlich等温线方程对吸附等温线数据进行拟合,检验实验数据与方程的吻合度,确定方程参数.同时,研究了葡萄糖和α-淀粉酶在沥青基球形活性炭上的竞争吸附行为.结果表明,所选用沥青基球形活性炭对葡萄糖分子的吸附在5h内达到吸附平衡;葡萄糖的初始浓度为3g/时,平衡吸附量为71mg/g;平衡吸附量受葡萄糖分子空间构象的影响,且随葡萄糖浓度的升高而增加,吸附等温线数据与Langmuir方程吻合,说明该吸附为单分子层吸附.在葡萄糖分子和α-淀粉酶的共存环境下,沥青基球形活性炭对葡萄糖有较好的吸附选择性.     

不熔化沥青球在低速流化床中炭化和活化的初步研究

不熔化沥青球在低速流化床中炭化和活化的初步研究乔文明，王克温，凌立成，刘朗周承泽，王瑾，郑斌（中国科学院山西煤炭化学研究所，太原０３０００１）（上海太平洋化工（集团）公司焦化总厂，２００２４１）关键词低速流化床，活化，炭化，球形活性炭由于球形活性炭，...     

Sorption and desorption of radiostrontium on calcareous soil and its solid components

The effect of different solid components of calcareous soil on the retention of Sr was investigated by using batch technique and selective extraction method. The sorption and desorption isotherms of Sr on the untreated calcareous soil and the three treated soils were determined at 20°C, pH 7.8±0.2 and in the presence of 0.001 M CaCl₂. It was found that all isotherms are linear and that the sorption of Sr on the calcareous soil can be described by a reversible sorption process and the sorption mechanism is mainly ion exchange.