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关键词： 微课   物理化学   教学改革  

摘要： 微课作为近年来一种新型的授课模式,已经成为教育领域较为热门的研究话题,微课以其短小精悍的特点受到众多教育工作者的欢迎。本文主要针对物理化学传统教学模式中存在的内容繁琐、学时不足,教学方法陈旧,实验数据处理落后等问题,分析在物理化学课程教学过程中应用微课的意义,并探究了具体的实施方法,希望为今后的物理化学教学改革提供一些意见和参考。

关键词： Physicochemical properties   Lactobacillus plantarum   Potato starch   Fermentation  

摘要： This study investigated the effect of fermentation by Lactobacillus plantarum CGMCC 14177 strain on phys-icochemical properties and morphological characteristics of potato starch. The maximum total amylase and alpha-amylase production of L. plantarum CGMCC 14177 were 286.8 and 208.1 U/g, respectively. Fermented granules clearly exhibited pocked and dimpled surfaces. The granule properties changed to have a 1.9% in-crease in relative crystallinity. Overall the starch changed to have slight increases in onset and peak temper-ature, but resulted decreases of conclusion temperature and enthalpy. Fermentation decreased peak viscosity and breakdown value, while increased trough viscosity, final viscosity, and setback. Further anal-ysis showed that fermentation increased the gel hardness and chewiness of the potato starch, but made lit-tle differences in the springiness, cohesiveness and resilience. Collectively, these results provide insight on how Lactobacillus strains can be used to modify the physicochemical properties of potato starch in ways that extend its use in industrial applications. (C) 2020 Elsevier B.V. All rights reserved.

关键词： 教学改革   物理化学   创新型人才  

摘要： 现阶段社会的发展对创新型人才的需求比较大,因此在教育中也更加重视对学生创新能力的培养,更加重视对创新型人才的打造。物理和化学课程是工科教学中的重点内容,具有较强的逻辑性和理论性,将创新意识融入其教学过程之中的教育改革的必要,通过对物理化学教学方式、教学内容的改革创新,能够拓展学生的创新思维,提升学生的创新能力,对于学生后续的学习发展具有重要意义。基于对创新型人才的培养,文章对物理化学的教学改革进行分析。

关键词： Galactomannan   Intrinsic viscosity   Solubility   Rheological behavior   Intermolecular entanglement  

摘要： Gleditsia sinensis, fenugreek and guar galactomannans (referred to as GSG, FG, and GG) were extracted from their gums and investigated using various techniques. Mannose to galactose ratios were 3.55, 1.11, and 1.65, respectively. The intrinsic viscosity of GSG was very close to that of GG, while that of FG was the lowest one. This was attributed to the influence of high galactose substitution of FG on the mannan backbone, which induced a lower chain dimension due to intermolecular entanglement. High degrees of substitution and high temperatures contributed to improving the solubility of galactomannan. Rheological behavior indicated that GG had the highest apparent viscosity, yet the power-law model could well -fitted the flow curves of GSG and FG, but not GG. Through morphological observations, the extracted galactomannans exhibited rod-like structure in deionized water and showed fibrous filament network structure after dehydration by freeze-drying. The thermal behavior was greatly influenced by the degree of side groups and Mw of galactomannans. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Non-conventional starches   Morphology   Pasting property  

摘要： In this study, starches were isolated from different non-conventional sources (acorn, black wheat, buckwheat, coix seed, jiaoyu, kuzhu, longya lily, and naked oat) cultivated in China, and their morphological, physico-chemical, and functional properties were analyzed. Among isolated starches, significant differences (p < 0.05) were observed in morphology, pasting, crystallinity, physico-chemical, and functional properties. After a compar-ison with commercial corn starch, all these isolated starches presented promising and unique characteristics. The XRD profile of isolated starches presented A-type (naked oat, buckwheat, coix seed, and black wheat), B-type (longya lily, acorn and jiaoyu) and C-type (kuzhu) polymorphic structures. SEM analysis revealed that the starches isolated from different sources showed distinct shapes exclusively globular, elliptic, and polygonal shapes. The high viscosity of jiaoyu and kuzhu starch pastes can be utilized to have an advantage in instant soups and sauces. Hence, the present study will improve the scientific basis on starches from different non -conventional sources, facilitate their utilization in a variety of applications. (C) 2020 Elsevier B.V. All rights reserved.

关键词： 物理化学   热力学   平衡态   稳定条件   化学平衡  

摘要： 化学平衡的移动规律是物理化学中重要的知识点之一。平衡稳定条件在经典热力学中占有重要的地位,但很少用于处理化学平衡问题。根据热力学原理,推导了简单的均匀隔离系统的平衡稳定条件,并将其用于分析温度和总压力对化学平衡移动的影响,结论为改变温度和总压力,使化学平衡朝着稳定平衡的方向移动。这种分析方法非常简单,也加深了我们对稳定平衡的理解。同时,也指出了该方法的局限性。

关键词： Polyaniline   Copolymerization   Poly(aniline-3-nitroaniline)   Physicochemical properties   Processability  

摘要： Polyaniline (PA), the versatile conducting polymer, owing to its tunable optoelectronic properties, facile preparation methodology and reversible redox behavior, has elicited much interest among current researchers, particularly in the fields of energy generation storage devices, protective coatings and electrochemical sensors. However, its commercialization has been much restricted due to low solution processability and thermal stability. Recent studies reveal that the above-mentioned challenges can effectively be addressed by copolymerization of PA with suitable components. In addition, the properties of copolymers could be modified and tuned by varying the monomer ratios. Thus, the present work is concerned with the fabrication of poly(aniline-co-3-nitroaniline) with varying compositions obtained by in situ oxidative copolymerization of aniline and 3-nitroaniline by altering the molar ratio of monomers. Optimization of the physicochemical properties such as UV-visible absorption, solubility, thermal stability, electrical conductivity and dielectric signatures, particle size and morphology was achieved by varying the composition of monomeric substituents in these copolymers. Smoother morphology of the copolymer films was revealed by morphological studies via AFM technique and supported by particle size distribution study. The physicochemical trends demonstrated that proper proportions of nitro (-NO2) group in the polymer chain are essential to achieve desired optimal physicochemical properties. Therefore, copolymers are ideally appropriate for multifaceted applications and would promote wider usage of conjugated polymers in various fields of organic-based optoelectronic as well as energy storage devices in the near future.

关键词： distiller liquid   soda ash   electrolyzer   ion-exchange membrane  

摘要： The production of soda ash by the Solvay method is accompanied by the formation of wastewater, much of which is the distiller liquid containing up to 100 g/L calcium chloride and up to 50 g/L sodium chloride. A highly efficient electrochemical method was proposed to treat the distiller liquid to form calcium hydroxide, sodium hydroxide, and hydrochloric acid. The proposed process consists of two stages. At the first stage, the distiller liquid is treated with alkali to produce calcium hydroxide and a filtrate containing sodium chloride. At the second stage, the filtrate is processed in a membrane electrolyzer to obtain solutions of sodium hydroxide and hydrochloric acid. It was shown that the process of treating the distiller liquid with alkali should be carried out at a CaCl2 : NaOH molar ratio of 1 : 1.25. The processing of the filtrate in the membrane electrolyzer makes it possible to obtain sodium hydroxide at a concentration of up to 4320 g/L and hydrochloric acid at a concentration of 148 g/L.

关键词： transglutaminase   kappa-casein   alpha(S)-casein   beta-casein   cross-linking  

摘要： The effects of microbial transglutaminase (MTGase) cross-linking on the physicochemical characteristics of individual caseins were investigated. MTGase was used to modify three major individual caseins, namely, kappa-casein (kappa-CN), alpha(S)-casein (alpha(S)-CN) and beta-casein (beta-CN). The SDS-PAGE analysis revealed that MTGase-induced cross-linking occurred during the reaction and that some components with high molecular weights (>130 kDa) were formed from the individual proteins kappa-CN, alpha(S)-CN and beta-CN. Scanning electron microscopy (SEM) and particle size analysis respectively demonstrated that the kappa-CN, alpha(S)-CN and beta-CN particle diameters and protein microstructures were larger and polymerized after MTGase cross-linking. The polymerized kappa-CN (similar to 749.9 nm) was smaller than that of beta-CN (similar to 7909.3 nm) and alpha(S)-CN (similar to 7909.3 nm). The enzyme kinetics results showed K-M values of 3.04 x 10(-6), 2.37 x 10(-4) and 8.90 x 10(-3)M for kappa-CN, alpha(S)-CN and beta-CN, respectively, and, furthermore, k(cat) values of 5.17 x 10(-4), 1.92 x 10(-3) and 4.76 x 10(-2) 1/s, for kappa-CN, alpha(S)-CN and beta-CN, respectively. Our results revealed that the cross-linking of beta-CN catalyzed by MTGase was faster than that of alpha(S)-CN or kappa-CN. Overall, the polymers that formed in the individual caseins in the presence of MTGase presented a higher molecular weight and larger particles.

关键词： amino acids   dry heating treatment   in vitro digestibility   normal cornstarch  

摘要： To improve processability and nutritional properties, normal cornstarch is modified by dry heating treatment (DHT) at different heating temperatures (70, 100, and 130 degrees C) for different heating times (0, 2, 12, 48 h) after mixing with various amino acid types (aspartic acid and lysine). The combination treatment effectively retards the starch digestibility. Among all samples, the rapidly digestible starch content of lysine-cornstarch mixture after being heated at 130 degrees C for 12 h is the lowest (14.1%), which decreases by 13% as compared to cornstarch. The gelatinization temperatures, gelatinization enthalpy, and relative crystallization of the combination treated cornstarch increases while no significant changes are observed in the X-ray diffraction and Fourier transform infrared spectroscopy of those starches. With increasing DHT temperature or prolonged DHT time, the viscosity of the heated aspartic acid-cornstarch mixture decreases, while that of the heated lysine-cornstarch mixture increases. Cluster analysis indicates that there are obvious differences between the samples with added aspartic acid and adding lysine. The combination treatment at 130 degrees C shows a more significant effect on the properties of AA-CS.