The best objective function for seeded batch crystallization

Although many researchers have optimized the operation of seeded batch crystallization, there remains little understanding of the effect of the choice of objective function on the optimization and no consensus on which objective function is best. In this work, different objective functions for seeded batch crystallization are compared by calculating the supersaturation trajectory that minimizes each objective function and then comparing the results of each trajectory. We show that some objective functions lead to trajectories that cause excessive nucleated mass and should be avoided. We conclude that the best objective function in most cases is to minimize the nucleated mass. This also corresponds to maximizing the growth of seeds, and leads to a product with a large volume mean size. We also show that the width of the product crystal size distribution can be controlled much more effectively by manipulating seed properties than by adjusting the supersaturation trajectory. © 2012 American Institute of Chemical Engineers AIChE J, 59: 390–398, 2013     

Acrylonitrile-based copolymer membranes containing reactive groups: Surface modification by the immobilization of biomacromolecules

Asymmetric membranes fabricated from poly(acrylonitrile-co-maleic acid) (PANCMA) were immobilized with heparin and/or insulin to improve their surface properties. These biomacromolecule-immobilized PANCMA membranes were prepared by the amination of the membrane surface with ethylenediamine, followed by the reaction of the amino groups with heparin and/or insulin in the presence of 1-ethyl-3-(3-dimethyl amidopropyl) carbodiimide. The surface-modified membranes were analyzed by X-ray photoelectron spectroscopy to confirm the immobilization of the biomacromolecules. Morphological changes on the membrane surface and in the cross section were characterized by scanning electron microscopy. The surface hydrophilicity and hemocompatibility of the studied membranes were evaluated on the basis of water contact angle, platelets adhesion and cell attachment measurements. It was found that, after the immobilization of the biomacromolecules, the water contact angle and the amount of adhered platelets and macrophages on the membrane decreased significantly when compared with the nascent ones, indicating the improvement of surface hydrophilicity. Furthermore, the heparin immobilized membrane showed the best hemocompatibility among the corresponding membranes studied.     

基于质子交换膜燃料电池的冷热电联产系统研究进展

将质子交换膜燃料电池应用于冷热电联产系统中,可有效提高系统效率,实现冷热电供能的可持续发展。本文介绍了基于质子交换膜燃料电池的冷热电联产系统的数学建模、运行策略、能源管理、多维评价、系统优化理论与应用等方面的研究进展。根据现有研究,从能源禀赋、供需整合与多尺度建模、多能互补供能、系统评价体系、系统集成优化多方面指明未来该系统的研究可从多尺度建模、源网荷储深度融合、完善系统评价体系以及系统优化与实时调控等方面进行,为得到更为全面高效稳定的质子交换膜燃料电池冷热电联供系统提供新思路。     

Highly efficient photocatalytic degradation of methylene blue using carbonaceous WO<Subscript>3</Subscript>/TiO<Subscript>2</Subscript> composites

Recent improvements in the performance of photocatalysts made it possible to tackle pollution through environment friendly methods. This study investigates the modification of the photocatalytic activity of TiO₂ by employing WO₃ and conductive polymers, namely, polyaniline (Pani) and polypyrrole (Ppy). Basing on our previous improvement of TiO₂ using a conductive polymer and activated carbon (AC), this study determines the activated carbon forms of TiO₂. The prepared composites are characterized using X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis, Brunauer–Emmet–Teller, and UV–Vis spectroscopy. The specific surface area of the mesoporous composites is as follows: WO₃/TiO₂·AC (Pani) > WO₃/TiO₂·AC (Ppy) > WO₃/TiO₂·Pani > WO₃/TiO₂·Ppy (127 > 98 > 68 > 44 m² g^?1), which exhibited a similar trend to the photocatalytic performances (100 > 95 > 91 > 72 % conversion rate). This result could be attributed to higher porosity, surge of charge separation, and photo-responding range extension induced by the synergistic effect of WO₃, conducting polymers, and TiO₂ in the samples.     

微乳法制备Pd-Cu双金属催化剂

选择Cu为助剂,采用微乳法分别优选具有较好稳定性的Cu和Pd微乳液体系,并将Cu和Pd依次负载于Al_2O_3载体上,经干燥、活化和还原制备了Pd-Cu/Al_2O_3催化剂。采用原位IR、CO化学吸附和HRTEM等对催化剂进行表征,结果表明,与常规溶液负载法制备的Pd-Ag/Al_2O_3催化剂相比,采用微乳法降低了催化剂表面酸性,提高了活性组分Pd分散度,Pd粒径分布更为均匀。在750 mL加氢反应器中,采用C_2后加氢原料对催化剂性能进行评价,结果表明,与常规溶液负载法相比,微乳法制备的催化剂在反应温度低4℃条件下,乙炔转化率相当,选择性高9.9个百分点,绿油生成量较低。微乳法制备Pd-Cu双金属催化剂具有良好的工业应用前景。     

硝酸羟胺HAN基液体发射药主要组份分析研究

硝酸羟胺基液体发射药是我国80年代末才开始研究的火炮“新能源”分析方法尚未确定.本文采用丙酮为“转换剂”成功地用酸碱滴定法测定了原料和成品中的硝酸羟胺HAN;采用“非水滴定法”测定了原料硝酸三乙醇胺TEAK的含量;并对液体药中TEAR之含量进行“电位滴定”方法的尝试,初步建立了“液体药组份分析方法”,保证了科研任务顺利完成.     

改性沸石去除中低放废水中痕量放射性核素的研究

研究了天然沸石的改性及其去除模拟中低放废水中痕量放射性核素的性能.将预处理好的天然沸石在浓度为0.25 mol/L的NaCl溶液中浸泡并在25℃、转速为200 r/min下恒温振荡24h,洗净烘干后得到钠型改性沸石.研究了吸附时间、溶液pH、沸石投加量和竞争离子对沸石吸附Co2+的影响,得到了最佳吸附条件:Co2+起始...     

双溴封端三氟氯乙烯调聚物的研制

选择二溴四氟乙烷为调聚剂,以三氟氯乙烯为调聚单体,尝试了3种不同方法试图合成双溴封端的三氟氯乙烯均聚调聚物,通过实验比较了3种方法的优缺点,同时通过凝胶渗透色谱、元素分析以及核磁共振等手段对调聚物的分子量、端基类型及其结构形式进行了表征。结果表明本文的合成方法简单易行,可以合成不同分子量的双溴封端调聚物。     

直流三端子输电特性的研究

在使用他励式电力换流器的并列式直流多端子送电系统中，根据电力系统的需要，有时对支线换流站进行从整流到逆变，或者与之相反的切换，为了对支线换流站的电压极性进行切换必须使支线换流站与直流系统一时脱离，这样极为不便，为了解决这一问题，如果在需进行上述切换的支线换流站设置双向电力换流器，在进行由整流到逆变，或与之相反的切换时，则不必使支线换流站与直流系统相脱离，只需用正弦波电流跟随控制方式，改变基准电流的     

中压汽包法兰断裂失效原因分析及改进措施

本文针对中压汽包法兰断裂失效原因进行分析，指出汽包上两个法兰同时断裂的原因在于安全阀排汽管路设计上的失误，并提出对安全阀排汽系统的改进措施。