Spectral and photochemical characteristics of CdSe nanoparticles stabilized in polymer-containing media

The optical characteristics of CdSe nanoparticles, produced in aqueous solutions and polymer films in the reaction of cadmium chloride and sodium selenosulfate, were studied. The main parameters that make it possible to vary the forbidden band width were identified. The absorption, photoluminescence, Raman, and nonstationary decolorization spectra of CdSe nanoparticles of various sizes were analyzed. It was demonstrated that under the conditions of pulsed irradiation the CdSe nanoparticles are capable of accumulating excess electrons and inducing redox transformations in components of the solution (oxygen, methylviologen, and sulfite ions). __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 3, pp. 150–155, May–June, 2006.     

划痕试验法对特殊薄膜系结合力的检测与评价

简要介绍了划痕试验法测量表面薄膜与基体结合力的测试原理和实验方法，讨论了影响临界载荷Lc测量值准确性的主要因素，通过对薄膜系的分类以及大量实际测量数据的总结和分析，认为被测薄膜以及基体的物理化学特性对临界载荷的测量具有重要的影响，单纯从声发射信号的变化来确定临界载荷的方法有可能存在较大误差，分析和讨论了某些特殊薄膜系的声发射信号与其实际临界载荷值之间存在较大偏差的现象和原因，并提出了针对不同膜系，合理利用声发射曲线，摩擦力斜率以及显微观测来正确判定临界载荷的必要性。     

GEOENVIRONMENTAL CHARACTERS OF YELLOW (HUANGHE) RIVER SUSPENDED LOAD

Three important characters of the suspended load of the Yellow (Huanghe) River are discussed, i.e. its temporal fluctuation as a function of solar activity, its uneven spatial distribution along the main course and the inevitability of these phenomena as a natural earth process rather than a result of disturbed ecological system caused by human activity. Implications of this understanding with regard to the control of the Yellow River are also discussed.     

FFC-1离子交换纤维物理化学性能的研究

利用扫描电镜、热失重-红外、元素分析、低温氮吸附等技术和化学手段对聚羧酸基FFC-1离子交换纤维的结构与性能特点等进行了系统研究．结果表明：FFC-1离子交换纤维为含适量酰肼类交联键的聚羧酸(钠)型离子交换材料，外比表面积大和传质距离短是其反应动力学性能优异的主要原因，FFC-1纤维具有良好的化学与热稳定性。在5mol/L硫酸、硝酸、盐酸和2mol／L氢氧化钠溶液中浸泡，交换容量未见明显降低。但过氧化氢溶液对其功能基有明显破坏，CO2为FFC-1纤维在高温区间(300℃～350℃)的主要分解产物。     

不同粒径炭黑混合对复合型导电材料PTC性能的影响

研究了炭黑分散效果对具有PTC效应的高密度聚乙烯／炭黑导电复合材料性能的影响。实验结果表明，由不同粒度和比表面积的两种炭黑混合后填充的复合材料同由导电性能较好的乙炔炭黑填充复合材料比较，前者具有较低的渗滤阀值、较高的临界温度、优良的PTC特性以及电阻稳定性好的特点．     

Ga^3＋的新萃取体系的界面特性和胶团化作用研究

研究了Ｇａ~（３＋）协萃体系（Ｇａ~（３＋）－Ｄ_２ＥＨＰＡ－Ｈ_２ＭＰＡ－正十二烷－Ｈ_２ＳＯ_４）的界面吸附和胶团形成热力学，发现该萃取体系中［Ｈ_２ＭＰＡ］影响Ｄ_２ＥＨＰＡ和Ｈ_２ＭＰＡ的界面吸附性质。在中、高［Ｈ_２ＭＰＡ］范围内Ｄ_２ＥＨＰＡ与Ｈ_２ＭＰＡ的界面吸附行为相反，Ｄ_２ＥＨＰＡ的存在也影响Ｈ_２ＭＰＡ的界面吸附行为。研究了界面张力与各因素关系的数学模型，并获得某些胶团形成和界面吸附特性的物化参数。     

PREPARATION AND ELECTROCHEMICAL CHARACTERISTICS OF POLYMER ELECTROLYTE MEMBRANES BASED ON SAN/PVDF-HFP BLENDS

A copolymer of poly(acrylonitrile-co-styrene) (SAN) was synthesized via an emulsion polymerization method. Novel polymer electrolyte membranes cast from the blends of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), SAN and fumed silica (SiO2) are microporous and can be used in polymer lithium-ion batteries. The membrane shows excellent characteristics such as high ionic conductivity and good mechanical strength when the mass ratio between SAN and PVDF-HFP and SiO2 is 3.5/31.5/5. The ionic conductivity of the membrane soaked in a liquid electrolyte of 1 mol/L LiPF6/EC/DMC/DEC is 4.9×10-3 S cm-1 at 25℃. The membrane is electrochemical stable up to 5.5 V versus Li /Li in the liquid electrolyte. The influences of SiO2 content on the porosity and mechanical strength of the membranes were studied. Polymer lithium-ion batteries based on the membranes were assembled and their performances were also studied.     

Influence of SMA content on the electro-optical properties of polymer-dispersed liquid crystal prepared by monodisperse poly(MMA-co-SMA)/LC microcapsules

Monodisperse poly(methyl methacrylate) (PMMA) particles containing various concentrations of stearyl methacrylate (SMA) were prepared, and a liquid crystal (LC) was swollen into the particles using a solute co-diffusion method (SCM). Phase separation behaviors between the polymer and LC were monitored by utilizing an optical and a polarized microscope (OM/POM). The monodisperse LC microcapsules were then applied to a polymer-dispersed liquid crystal (PDLC), and the electro-optical properties were investigated. As a result, the threshold and driving voltages were improved when the SMA content increased. The long alkyl chains of SMA in the capsules should exist at the interface of the LC and polymer resulting in an enhancement of phase separation between the polymer and LC, which largely influences the electro-optical properties of PDLC.     

Effects of type and number of impellers and liquid viscosity on the power characteristics of mechanically agitated gas—liquid systems

Effect of the type and number of high-speed impellers installed on a common shaft on the power characteristics was investigated in water and glucose solutions of different concentration. Different configurations of the Rushton or Smith turbines, pitched blade turbines, propeller, and A 315 impeller were tested. Measurements of power consumption were carried out within the transitional and turbulent regime of the fluid flow using the strain gauge method. Baffled agitated vessels with inner diameter of 0.288 m and 0.634 m were used for the experiments. Liquid height in the vessels was equal to the vessel diameter or it was twice higher. The relative power consumption was compared for different configurations of the impellers. Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May 2006.     

Flammability studies of 3-methyl pyridine/water system

In industrial processes, information on the safety property of chemicals is essentially crucial for safe handling during unit operations. Ensuring the safe use of combustible or flammable substances in processes is unlikely without detailed investigations of their flammability characteristics and related hazards. We studied 3-methyl pyridine (3-picoline), e.g., flammability limits (LFL/UFL), maximum explosion pressure (P _max), maximum explosion pressure rise (dP/dt)_max, minimum oxygen concentration (MOC), vapor deflagration index (K _g), and characterized the influence of inert steam (H₂O) on critical parameters for 3-picoline/water mixtures at 270°C, 1 atm, various oxygen concentrations, and vapor mixing ratios (100/0, 30/70, 10/90 and 5/95 vol.%) with a 20-L-Apparatus in simulated conditions, respectively. The results showed that the flammability characteristics of 3-picoline_(aq) all increased with the oxygen concentration. However, as the composition of inert steam increased, the flammability parameters and the degree of fire and explosion hazards were significantly reduced, instead. This study elucidated the flammability properties of 3-picoline mixed with inert steam. The conclusions could be applied to proactively prevent the relevant processes from incurring fire and explosion accidents.