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。     

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.     

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.     

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，...     

蛋白质在固定Zn2+金属螯合亲和色谱中的变性热力学

在15~85℃宽温度范围,研究了蛋白质在固定Zn2 金属螯合色谱系统中的热行为和变性热力学。实验结果表明,蛋白质在色谱过程都有一个固定的热转变温度:核糖核酸酶(RNase)、α-胰凝乳蛋白酶原A(α-Chy)的热转变温度约为55℃,细胞色素C(Cyt-C)和溶菌酶(Lys)约为65℃;,热转变温度的出现标志蛋白质构象发生变化;利用Van′tHoff作图测定了蛋白质在色谱系统热变性时的标准焓变ΔH°和标准熵变ΔS°,提出用标准熵变ΔS°和自由能变ΔG°判断蛋白质构象变化;利用ΔH°-ΔS°的线性关系估算了蛋白质热变性时的补偿温度,鉴定了蛋白质各变体在金属螯合色谱中保留机理的同一性,RNase、Cyt-C、Lys和α-Chy的补偿温度分别为55℃、65.8℃、65.2℃和54.8℃;根据蛋白质热变性时的补偿温度和构象变化熵变Δ(ΔS°)的大小,讨论了蛋白质在阳离子交换色谱和固定Zn的金属螯合色谱体系中的热稳定性。实验证明,在IDA裸柱引入Zn2 后蛋白质在色谱系统中的热稳定性减小,平均补偿温度从65.3℃降低到59.7℃,而构象变化熵变的绝对值大幅度升高。     

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.     

Temperature and metal composition dependence of lateral photovoltaic effect in Al-Alq3/SiO2/Si structures

A series of Al=-（Alq3）l-x granular films is prepared on Si wafer with native oxide layer using co-evaporation technique. Large lateral photovoltaic effect （LPE） is observed, with an optimal LPV sensitivity of 75 mV/mm in x=0.35 sample. The dependence of LPE on temperature and A1 composition is investigated, and the possible mechanism is discussed.     

Ultra-broadband piezoelectric energy harvesting via bistable multi-hardening and multi-softening

Nonlinear Dynamics - An electromechanical coupled distributed parameter model is derived for a broadband piezoelectric energy harvester with nonlinear magnetic interaction and...     

Controlled Synthesis of Ni-Doped MoS2 Hybrid Electrode for Synergistically Enhanced Water-Splitting Process

The development of high-efficiency, low-cost, and earth-abundant electrocatalysts for overall water splitting remains a challenge. In this work, Ni-modified MoS₂ hybrid catalysts are grown on carbon cloth (Ni-Mo-S@CC) through a one-step hydrothermal treatment. The optimized Ni-Mo-S@CC catalyst shows excellent hydrogen evolution reaction (HER) activity with a low overpotential of 168 mV at a current density of 10 mA cm⁻² in 1.0 m KOH, which is lower than those of Ni-Mo-S@CC (1:1), Ni-Mo-S@CC (3:1), and pure MoS₂. Significantly, the Ni-Mo-S@CC hybrid catalyst also displays outstanding oxygen evolution reaction (OER) activity with a low overpotential of 320 mV at a current density of 10 mA cm⁻², and remarkable long-term stability for 30 h at a constant current density of 10 mA cm⁻². Experimental results and theoretical analysis based on density functional theory demonstrate that the excellent electrocatalytic performance can be attributed mainly to the remarkable conductivity, abundant active sites, and synergistic effect of the Ni-doped MoS₂. This work sheds light on a unique strategy for the design of high-performance and stable electrocatalysts for water-splitting electrolyzers.