微波辐射对硫酸钙结晶生长的影响

在相同的结晶条件下,采用微波加热与传统加热所形成的硫酸钙晶体形貌有明显差异。通过蒙特卡罗模拟对此现象进行了分析和解释,模拟结果显示,微波辐射影响了硫酸钙晶体的生长过程,从而影响了硫酸钙晶体形貌。     

微波作用下氯化钠水溶液介电特性变化机理

实验研究发现,微波作用下的恒温氯化钠水溶液随着微波功率的增加,其复介电系数的虚部会发生明显变化从理论上分析表明,在微波场中极化水分子转动能级被激发将会引起质子定向移动和团簇氢键完好的概率变化而影响氯化钠水溶液电导率,进而造成其复介电系数虚部的明显变化。此现象应归属于微波的非热效应。     

微波加热体的水量热法测温装置

探讨了在材料的微波加热与合成过程中,如何精确地测量加热体内温度。在分析了微波加热过程中常用的几种温度测量技术后,认为目前几种在线的温度测量技术对于固态微波加热体内部的温度测量都存在着一定的缺陷。在此基础上,结合微波加热过程的一些特点,采用了一种离线型的、测量微波加热体平均温度的方法,即微波加热体的水量热测温方法。温度测量方法的原理是热传递和能量守恒,经实验验证,该温度测量装置的测量结果具有较高的可靠性。并且测量结果可以作对于微波加热体温度场理论计算结果准确性与精确性进行验证的重要依据之一。     

微波促进膜分离过程的研究进展

降低或消除“温度极化”和“浓度极化”是改善膜分离性能的重要途径。微波已经被用于促进各种膜分离过程,例如,气体分离,超滤,渗透蒸发等。微波促进膜分离过程是基于微波热产生特殊的推动力来促进质量传递过程,因此,微波加热可望通过“球体”加热方式降低传质过程中的极化现象。综述了微波促进膜分离过程的研究现状,展望了微波集成的膜分离过程的发展趋势。     

微波作用下的固相有机反应的初步研究

介绍了微波作用下的固相有机合成反应的优越性,并进行了一定的研究探讨———Beckmann重排和Fries重排反应的无溶剂合成。     

热风和微波结合干燥荔枝加工工艺研究

本试验对以荔枝鲜果为原料,通过热风干燥和微波干燥相结合制作荔枝干果的加工工艺进行了研究。研究结果表明,荔枝鲜果经预处理后,用70℃的热风干燥至50％的水分含量,再以240g/kW的微波处理量进行干燥,所得荔枝干果品质最佳。采用PA＆PE复合包装袋加脱氧剂的包装方法,其保质效果最好,贮藏期在9个月以上。     

荆芥挥发油提取方法的研究

水蒸气蒸馏法和溶剂提取法是提取荆芥挥发油的传统方法,随着科技的发展必然被新的方法所取代。超临界流体萃取和微波提取法通过与水蒸气蒸馏法比较,表现出提取速率更快、提取率更高的优良特性。研究新提取方法对于改进荆芥挥发油的生产工艺,提高生产效率有重要意义。     

微波辅助提取藜蒿黄酮的研究

进行了微波辅助提取藜蒿总黄酮的实验。分别采用单因素法和正交实验法探讨了各因素的影响。结果得到微波辅助萃取藜蒿总黄酮的最佳工艺条件为：固液比为1g：25mL,溶剂乙醇浓度为20％,微波功率为320W,辐射时间60s,溶液pH为10,此时藜蒿总黄酮提取率最高,约为0．870％。     

Direct ink writing of bismuth molybdate microwave dielectric ceramics

Additive manufacturing via direct ink writing and microwave dielectric characterisation of commercially produced low sintering temperature bismuth molybdenum oxide ceramics, have been both performed for the first time, following a powder-to-product holistic approach. We demonstrated that direct ink writing is an excellent candidate for producing dielectric substrates to be used for wireless telecommunication applications operating at microwave (MW) frequencies, with great repeatability and properties comparable to ceramics fabricated via conventional processing routes. The optimum density (relative density of ρ_r ≈ 93%) of the 3D printed test samples was obtained by sintering at 660 °C for 2 h, resulting in a relative permittivity ε_r = 35.7, dielectric loss tanδ = 0.0004 and microwave quality factor Q × f = 14,928 GHz. Sintering at higher temperatures promoted a porosity increase due to mismatching grain growth mechanisms and phase decomposition, that collectively hindered the test samples’ microwave dielectric performance in terms of achievable relative permittivity (ε_r) and dielectric loss (tanδ).     

pH dependent morphology and texture evolution of ZnO nanoparticles fabricated by microwave-assisted chemical synthesis and their photocatalytic dye degradation activities

ZnO nanostructures are well-known photocatalysts for the degradation of toxic organic dyes and their morphology, size, and other physicochemical properties play important roles in their photocatalytic performance. To study the effect of size, morphology, and synthesis conditions in photocatalytic performance, we synthesized ZnO nanoparticles of different morphologies through a simple microwave-assisted chemical process at different pH values of the reaction mixture. Different pH values of the reaction mixture produced ZnO nanoparticles of different morphologies and sizes. The nature of the pH controlling agent and final pH of the reaction mixture were seen to have considerable effects on the lattice parameters and microstrain of the ZnO nanocrystals, along with their photocatalytic performance. We observed that while the ZnO nanostructures synthesized at very high pH values of the reaction mixture have a high specific surface area, their photocatalytic activity is higher when they are synthesized at acidic pH or pH near the isoelectric point of ZnO. The results demonstrate that the photocatalytic activity of ZnO nanostructures not only depends on their size or specific surface area but also strongly depends on the concentration of catalytic sites at their surface.