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关键词： Zirconia  

摘要： This work represents the influence of various solgel parameters on the physico-chemical properties of sulfuric acid chelated zirconia aerogels dried at ambient pressure. The solgel parameters such as concentrations of precursor, chelating agent and catalyst are found to be the dominant factors which influence the physical, chemical and textural properties of the aerogels. Therefore, the influence of concentration of Zr precursor, ZrPr:H2SO4 molar ratio and ZrPr:H2O molar ratio on these properties of zirconia aerogels is studied. Zirconia lacogels are formed by the hydrolysis and condensation of zirconium n-propoxide in n-propanol chelated with sulfuric acid (18.4 M) and catalyzed with deionized water. Aerogels are obtained by subsequent solvent exchange, silylation, washing and ambient pressure drying. The physico-chemical properties of as synthesized zirconia aerogels are carried out using FESEM, EDS, BET analysis and FTIR spectroscopy. The good quality zirconia aerogels are obtained using the molar ratio of ZrPr:PrOH:H2SO4:H2O:HMDZ::1:2.93:1.18:1.77:0.59. They possess the density of 0.54g cm-3, BET surface area of 328 m2 g-1 and micropore volume of 0.028 cm3 g-1. These aerogels can be applied as heterogeneous catalysts in many fields. © 2020 Wiley-VCH GmbH

关键词： Corn starch-amino acid complex   Digestibility   Physicochemical properties  

摘要： Amino acids are the structural units (monomers) that make up proteins and play many critical roles in human diets with or without food processing. In this study, corn starch (CS) mixed with Lys, Ser, Ala, or Asp were subjected to heat moisture treatment (HMT) or annealing (ANN). We evaluated the morphological properties, swelling power, pasting properties, thermal properties, crystallinity structure, and in vitro digestibility of CS and CS-AA complexes. HMT increased the gelatinization temperatures and retarded the retrogradation for CS with or without Ms, while ANN had little impact on gelatinization temperature and promoted the recrystallization. Generally, HMT samples were more enzyme resistant than the ANN samples. For the uncooked samples, the addition of Ser, Ala, and Asp decreased rapidly digestible starch (RDS) and slowly digestible starch (SDS) contents, but increased resistant starch (RS) content. Compared with the control (CS without M), CS-AA complexes had lower contents of RDS following HMT. Under ANN, CS-AAs had higher content of RDS compared with the control. In all groups (physically mixed, HMT, and ANN) with cooked samples, the addition of different Ms decreased the contents of RDS and increased RS contents to varying degrees. (C) 2020 Elsevier B.V. All rights reserved.

关键词： 大学生   物理化学实验报告   科学写作能力   评价工具  

摘要： 科学写作能力的培养已被国内外科学教育研究者广泛关注。实验报告作为科学写作的典型形式之一,其撰写质量在教学环节中却时常被忽视。本研究提出实验报告写作能力应包含完整性、规范性、科学性等3个维度。基于物理化学课程实验任务,设计了一个信效度良好的物理化学实验报告写作能力评价工具。

关键词： 物理化学   固体推进剂   粘接界面   剪应力   海洋环境   损伤分布  

摘要： 为研究海洋环境对立式贮存值班状态固体推进剂粘接界面损伤分布的影响,监测了某型固体火箭发动机值班条件下的振动载荷并进行数据处理;开展在温差/重力载荷和温差/实测振动载荷联合作用下固体发动机燃烧室的模拟计算,提取了两种载荷历程下的粘接界面剪应力—时间历程,并获取剪应力沿界面分布规律;结合推进剂粘接界面剪应力拉伸破坏试验、剪应力幅值往复拉伸破坏试验所得的本构方程结果,近似计算界面累积损伤分布。模拟计算结果表明,两种载荷历程剪应力沿界面路径分布规律相近,前人工脱粘结构附近界面应力较其他位置大;随贮存时间增加,蠕变损伤和疲劳损伤呈线性增加趋势;贮存期间对应的剪应力水平下,界面各位置损伤相差不大,最大相差20%左右;忽略蠕变与疲劳作用对界面损伤的交互影响,发动机值班半年时,累积损伤为5.79%。

关键词： Tremella fuciformis   Glucuronoxylomannan   Chain conformation   Wormlike cylinder model   Rheological properties   Moisture absorption and retention capacity  

摘要： Based on its potential bioactivities and sustainable source, polysaccharide (glucuronoxylomannan) from fruit bodies of Tremella fuciformis (TFP) aroused attention in food, pharmaceutical and cosmetic industry. The present study aimed at revealing its chain conformational and physicochemical properties. By using HPSEC-MALLS-Visc-RI measurement, worm-like cylinder model calculation and AFM observation, we manifested that TFP existed as flexible chains in 0.15 M NaCl (pH 7.4) solution, with the persistence length of 9.20 nm and chain diameter of 0.97 nm. Meanwhile, TFP solution exhibited shear-thinning behavior with C* at 5.3 mg mL(-1), owning the feature of entangled polysaccharide. TFP solution changed from liquid-like to solid-like behavior as frequency increases, and the crossover points shifted to lower frequencies with concentration increasing. Besides, the strong moisture retention ability of TFP was evaluated. These characteristics indicated that TFP could be utilized to design microstructure system and applied as stabilizer or moisture holding ingredient in food, pharmaceutical and cosmetic system.

关键词： “物理化学”   教学改革   迁移  

摘要： 为培养新时代高素质化学化工类人才,提高教育教学水平,以“物理化学”课程为研究对象,基于工程教育专业认证标准对工科院校教育质量提出的新要求,采用迁移和具象的教学思维改革传统的教学方式,以具体案例分析为授课手段,引导学生采用浸入式学习方法,可有效提高学生学习的主观能动性,增强学生将理论知识应用于解决实际生产问题的能力。通过对“物理化学”课程教学改革,可全面提高大学生综合素质,为培养企业所需的应用型人才打下坚实的基础。

关键词： 网课   物理化学   实验  

摘要： 随着网络普及,涌现了多种教学模式,在线教育方式多样。物理化学实验课程作为化学、材料化学等专业基础课程,是基于理论原理的实践课程,开展线上教学,需要进行量身定制的相关应对方法。本文从教学可能存在困难与解决对策为本课程教学提供一定指导,从而更好的为授课提供支持。

关键词： 物理化学   雨课堂   教学  

摘要： 物理化学课程知识点繁杂,传统课堂教学无法把握学生的学习情况,难以提高其学习积极性。教师可以在课前利用“雨课堂”详细掌握学生预习情况,有针对性做好备课工作;课堂教学过程中增加互动环节,突出学生的主体性;课后利用“雨课堂”推送复习重难点,督促并辅助学生做好课程复习巩固。

关键词： Hyaluronic acid   Diisocyanate   Crosslinking   Biocompatibility   Immunomodulation  

摘要： Here, we synthesise a new isocyanate-based crosslinker with the aim of obtaining novel tailored gels. The newly crosslinked hyaluronic acid (HA) gels were analysed in terms of rheological properties, chemical structure, swelling, biocompatibility and immunological response. Results show that the synthesised di-isocyanate out-performs other more conventional di-isocyanates due to its alkyl-based which has been shown to be slower to degrade by hydrolysis than aryl isocyanates. The alkyl-based isocyanate reacts readily with hydroxyl groups on the HA to form stable carbamate crosslinkages. Importantly and uniquely, a centrally located disulphide bond allows versatility with respect to reversible crosslinking and this allows potentially controlled layer-by-layer deposition of the HA for tailored pharmaceutical applications.

关键词： 物理化学   人文精神   工科专业   教学改革  

摘要： 物理化学是诸多工科专业的专业必修课,一直面临着内容抽象、公式繁多,难学易忘等困局。在工科物理化学课程中引入了化学史介绍、科学家介绍相关学科间关系和科研素养的启发等部分,可以活跃课堂教学气氛,激发学生学习兴趣,以培养学生良好的科学素养和人文精神。