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关键词： 物理化学   雨课堂   翻转课堂   教学探索  

摘要： 笔者结合自身多年一线教学经验,借助于雨课堂智慧教学工具,在物理化学教学中引入了翻转课堂教学模式,深入分析了翻转课堂实施过程中可能遇到的问题,并提出了相应的解决方式方法。该教学模式在物理化学教学中具有一定的推广意义。

关键词： 5LIO-1-Cm-3   2-HOPO   色谱法   高压液相   平衡溶解度   表观脂水分配系数   解离常数   稳定性   成药性  

摘要： 目的 通过测定羟基吡啶酮类化合物5LIO-1-Cm-3,2-HOPO在不同介质中的平衡溶解度、表观脂水分配系数(log D)、解离常数(p K_(a))以及稳定性,评价该化合物的物理化学性质对其成药性的影响。方法 建立HPLC检测方法并测定5LIO-1-Cm-3,2-HOPO在不同介质中的平衡溶解度;采用摇瓶法测定其在水及不同pH溶液中的log D;利用电位滴定法测定其p K_(a)并考察温度、湿度和光照3个因素对其稳定性的影响。结果 5LIO-1-Cm-3,2-HOPO的平衡溶解度在50-2500μg/ml之间;log D值介于-1--0.5之间;p K_(a1)和p K_(a2)分别为8.53±0.07和9.14±0.08;在各种影响因素下稳定性均良好。结论 5LIO-1-Cm-3,2-HOPO为低溶解性、亲水性分子药物,呈弱酸性,化学性质稳定,在胃肠道环境下能吸收进入血液,但吸收可能不理想,通过制剂学技术有望提升其成药前景。

关键词： 煤变质作用   煤化作用   石墨化作用   构造物理化学条件   演化机制  

摘要： 煤是对温度和压力等地质因素十分敏感的有机岩,各种构造-热事件控制下的物理化学条件,是促进煤岩演化的根本动力。本文对煤变质作用过程的研究现状进行了综述,着重讨论了煤岩在高煤阶-石墨演化阶段的控制因素、演化过程和演化机制。煤变质作用包括煤化作用阶段和石墨化作用阶段,共同构成一个连续的有机质演化过程,总体趋势是分子结构有序化、化学成分单一化,最终演变为以碳元素为主、三维有序结构的石墨。温度和压力(应力)是控制煤变质作用两大因素,在不同的演化阶段,这两大因素所起的作用和演变机理都有所差异。在低、中煤阶演化阶段,温度是煤化学结构演化的主要控制因素,为化学键断裂提供活化能,应力缩聚和应力降解则对煤化学结构演化具有催化作用。高煤阶-石墨化阶段的主要机制是导致基本结构单元BSUs之间相互联结使短程有序化范围增大的拼叠作用,构造应力在其中起到关键作用,BSUs定向和面网间距不断减小,促进大分子物理结构演化。加强煤变质作用的高级阶段-石墨演化过程的研究,将丰富和深化对煤-石墨物理化学结构完整演化序列的认识。煤系石墨成矿机制的高温高压模拟实验,则为煤变质作用构造物理化学条件研究提供了可行的技术手段。

关键词： 化学教学   物理化学   新时代   创新   生态文明   经济建设  

摘要： 物理化学主要研究化学变化的基本规律,新时代教育背景下的物理化学教学改革是新时代中国特色社会主义的重要内容。为适应新时代的思想和理论的发展,物理化学教学在教学理念的创新、教学融入生态文明建设、教学知识实践化、经济持续健康发展等方面进行改革,以有效改善生态环境,促进广泛形成绿色低碳发展,为新时代教育背景下的物理化学教学发展提供支撑。

关键词： oil-in-water nanoemulsion   D-Optimal mixture design   physicochemical properties   rheology study   pseudoplastic behavior  

摘要： Ananas comosus (A. comosus) is one of the many commercial crops in Asian countries well-known for its medicinal characteristics, and widely popular in the food industry. Nonetheless, large quantities of the antioxidant rich pineapple peels (PP) are discarded or used as animal fodder, thus the full potential of the PP for nanocosmeceutical applications remain untapped. This study assessed the use of D-optimal mixture design for optimizing droplet size and polydispersity index (PDI) of PP extract nanoemulsion (AcPEN), for four different independent variables (olive oil, grapeseed oil, Tween 80, water). The identified best formulation indicated satisfactory agreement, with the percentage prediction error (PPE) for the actual and predicted values being less than 10%. The optimized AcPEN (OPT-AcPEN) was organoleptically characterized and the Transmission Electron Micrograph corroborated the minimum droplet size and PDI of OPT-AcPEN being <200 nm and < 0.25, respectively. The OPT-AcPEN was stable under different storage conditions for up to 90 days, and the corresponding repeated centrifugation and freeze-thaw tests retaining the recommended pH of between 4 - 6 for topical skin application. Pertinently, the shear thinning and pseudoplastic behavior seen from the rheology results implied the suitability of OPT-AcPEN as a topical cosmeceutical nanoemulsion and could meet user's requirements.

关键词： 熔盐   电解   KF   初晶温度   电导率   溶解性能  

摘要： 基于步冷曲线法、CCVC法和观察法,研究了KF含量对电解质体系初晶温度、电导率、氧化铝溶解性能和阴极电解膨胀率的影响。结果表明:初晶温度随KF含量的增加而降低,平均每增加1%的KF,初晶温度降低1.83℃左右;电导率随过热度增加而增大,过热度每增加1℃,电导率平均增大0.009 S/cm;相同过热度下,KF每减小1%,电导率平均升高0.033 S/cm;相同过热度下,KF含量对氧化铝溶解速度的影响较小;阴极炭块的电解膨胀率随KF含量的增加而增大。本工作旨在研究KF含量对铝电解质物理化学性质的影响,为铝电解工业选择适宜的电解质成分提供理论依据。

关键词： Bioindicator   Acidification   Eutrophication   Brownification   Turbidity   Citizen science  

摘要： Increasing anthropogenic pressures have affected the status of surface freshwater ecosystems. Eutrophication, water browning, acidification, and several other processes may be channelled through the food web. In this study, we evaluate the role of hydrology impacting anthropogenic pressures, flows from urban, farmland and ditched forest areas, and how they explain the physico-chemical quality of lakes and ponds in the boreal biome of Finland. We study the long-term effect around 445 waterfowl survey sites that had physico-chemical measurements (total phosphorus, total nitrogen, pH, water clarity and colour) produced by Finnish environmental authorities done in years 1986-2020. Furthermore, we investigate whether a long-term national-level citizen science study focusing on rather robust visible habitat structures measured by the volunteers can reveal physicochemical water quality using data from >270 lakes where the waterfowl habitat survey and physico-chemical measurements could be spatio-temporally matched. Farmland occurrence around the lakes was positively associated with pH, colour and nutrient concentrations but negatively associated with water clarity. Furthermore, ditch length was positively associated with nitrogen concentration and water colour, while being negatively associated with pH and water clarity. Overall, the studied lakes showed a negative trend in nutrients and clarity but a positive trend in pH and colour. As expected, nutrient concentration increased and clarity decreased along the gradient from oligotrophic to eutrophic lake habitat classifications, which suggests that the citizen science classification seem to reflect the subsurface physico-chemical status of the lakes. We conclude that farming and forest ditching practices in particular seem to associate with the state of the study lakes and that the ecological impacts of intensified turbidity and brownification in wetland ecosystems should be studied further in the future. Sustainable impro

关键词： Casein   whey protein   crystallinity   caking   surface composition   glass transition  

摘要： Physicochemical characteristics of whey protein concentrate (WPC35, 35% protein), whey protein isolate, sodium, and calcium caseinate powders were studied by storing them at 25, 35, and 45 degrees C and 11, 44, and 85% relative humidity (RH) for 21 days. Monolayer moisture content (M-o) in these powders increased with increasing protein content. The glass transition temperature (T-g) of all of these powders decreased with increasing RH at all storage temperatures. Lactose crystallization occurred in WPC35 at 85% RH at all temperatures and 44% RH and 45 degrees C, and this caused caking. Caking was also observed in whey protein concentrate and isolate, and sodium and calcium caseinate powders at 85% RH and 45 degrees C, despite having low (0.2-1.5%, w/w) lactose content. Surface fat content was higher in powders stored at higher temperatures and RH. All powders developed browning, which was especially pronounced at 85% RH. These findings help better understand the temperature and humidity dependent behavior of whey protein and casein powders during storage.

关键词： 化学教学   人工智能   物理化学   教育改革  

摘要： 人工智能技术与物理化学课程结合能为教学准备和课堂教学提供丰富形象的资源,建立更加有效的教学评价模式,有利于物理化学知识的共享,提升学生学习物理化学的兴趣,加深对物理化学知识的理解。

关键词： 课程思政   新工科   物理化学   教学改革  

摘要： 以“物理化学”课程为例,在教学过程中融入思政元素,在传授专业知识的同时,培养学生坚忍不拔的性格、严谨的科学态度,引导学生形成正确的价值观、人生观和世界观,实现思政教育与专业教育相结合的全方位培养人才的目标。