Thermal stability of composite phase change material microcapsules incorporated with silver nano-particles

This paper reports a study on the thermal stability of phase change material microcapsules that are incorporated with silver nano-particles (Ag-NPs). The novel microcapsules were fabricated by the technique of in situ polymerization, with aminoplast as the wall and phase change material bromo-hexadecane (PCM BrC16) as the core. Thermal gravimetry (TG) analysis was applied to measure the thermal stability of these microcapsules and surface morphology of the microcapsules was observed by means of scanning electron microscopy (SEM) after an application of curing treatment at 130 °C. Comparing with conventional phase change material microcapsules (PCMMs), nano-composite phase change material microcapsules (NCPCMMs) have higher thermal stability. This can be attributed to nano-composite structure of the microcapsules, in which metal Ag-NPs distributed on the surface to increase wall toughness and strength. The possible reinforcement mechanisms of the nano-composite structure are explored.     

合成气合成异丁醇的研究进展

异丁醇作为基本有机化工原料,在工业生产中有广泛的应用。由合成气直接合成异丁醇作为一种新的工艺思路对世界各国科学家都有强大的吸引力。该文章讨论了合成气合成异丁醇反应过程中的动力学、热力学以及反应机理,并分析了合成过程中所需催化剂的研究现状,对合成气直接合成异丁醇的工艺开发和催化剂的制备有指导意义。     

一种间接-直接蒸发冷却系统的应用分析

本文介绍了一种间接-直接蒸发冷却系统变风量送风的原理,以美国科罗拉多州的丹佛市为例,进行了空气处理过程的分析,并对丹佛市的一幢建筑应用这种间接-直接蒸发冷却变风量系统,进行了能耗分析。     

基于Petri网的办公自动化工作流建模

基于Petri网的建模方法具有坚实的数学基础和直观的图形表示,是对工作流建模和分析的理想工具。通过对办公自动化系统中的发文管理实例的描述,提出了一个基于Petri网办公自动化工作流模型,并对该模型进行了正确性验证,提高了办公自动化系统的实用和高效性。     

V2O5熔体的微量氧化还原研究

将700、800、1100℃三种温度下的V2O5熔体制得V2O5溶胶,在非晶玻璃基片上将V2O5溶胶制成V2O5凝胶薄膜试样。通过对V205凝胶薄膜试样的电阻随温度的变化测试和电子能谱（ESCA）和X射线衍射分析发现V2O5凝胶薄膜中有四价钒的存在,本文从V2O5熔体的微量氧化还原和晶体结构的角度分析讨论了微量氧化还原影响钒离子价态变化的机理。     

Effect of synthesized temperature on microstructure, infrared emissivity and dielectric property of Fe-doped ZnO powder

Fe-doped ZnO powder has been synthesized by coprecipitation method under different synthesized temperature, using zinc nitrate as the staring material, urea as the precipitator, and ferric nitrate as the doping source, respectively. The prepared powders have been characterized by XRD and SEM. Results show that when the synthesized temperature is below 700 °C the prepared powders are ZnO(Fe) solid solution powders and the ZnFe₂O₄ impurity phase appeared for the Fe-doped ZnO powder synthesized at 700 °C. The electric permittivities in the frequency range of 8.2–12.4 GHz and average infrared emissivity at the waveband range of 8–14 μm of prepared powders have been determined. The real part and imaginary part of electric permittivities of prepared powders have increased firstly and then decreased with increasing synthesized temperature. The average infrared emissivity has presented the opposite changing trend.     

含半椭圆表面裂纹焊接接头断裂参量的试验研究

本文研究了半椭圆形表面裂纹最深点三维J积分的直接测试技术,并在此基础上,通过对高匹配焊接接头表面裂纹试样断裂力学参量J积分的试验测试,探讨了接头强度匹配对焊接表面裂纹扩展驱动力的影响。试验表明本文所采用的手段对于焊接表面裂纹断裂参量的测试是适用的,且结果也充分反映出焊接接头的力学性能不均匀性的影响作用。     

包装废聚乙烯改性沥青路用性能研究

以回收的包装废弃聚乙烯作为改性剂,对普通道路沥青进行改性,并通过沥青混凝土马歇尔试验实验、车辙实验、抗弯强度试验等,对改性后沥青的路用性能进行了研究,结果表明:包装废聚乙烯改性沥青的稳定性、抗弯强度提高、抗车辙能力增强,沥青路用性能得到明显改善.     

乙酸与乙醇在硫酸氢钠催化下合成乙酸乙酯的动力学研究

文章以硫酸氢钠为催化剂,考察了不同温度(35~75℃)与催化剂用量(2~5 g)下乙酸与乙醇反应合成乙酸乙酯的反应速率,得到反应速率方程。实验结果表明:硫酸氢钠催化合成乙酸乙酯的反应为二级可逆反应,反应速率常数与温度及催化剂浓度的关系可表为Arrhenius方程形式的函数,应活化能为52.24 kJ/mol,指前因子则与催化剂的浓度有关。     

Epitaxial layers of CuInSe2

Epitaxial layers of CuInSe₂ and related mixed crystals were grown on different substrates by liquid phase epitaxy and molecular beam epitaxy but mainly by flash evaporation. The geometrical foundations and experimental results are discussed. The type of epitaxy (one-dimensional, multiple orientation or unique) the epitaxial temperature range and particularly the epitaxial relationships are described.