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关键词： 物理化学   微观形貌   含能热塑性弹性体   ETPE   发射药   RDX/BAMO-AMMO  

摘要： 为研究含能热塑性弹性体(ETPE)发射药微观形貌与性能的关联性,采用电子扫描电镜(SEM)对RDX/BAMO-AMMO基含能热塑性弹性体(ETPE)发射药微观形貌进行了观测,分析了工艺方法、1,5-二叠氮-3-硝基氮杂戊烷(DIANP)增塑剂含量对发射药微观形貌的影响,讨论了发射药低温冲击断面和中止燃烧熄火表面的微观形貌特征,并从发射药微观形貌角度提出了改善燃烧性能和力学性能的技术途径。结果表明,RDX/BAMO-AMMO基发射药属于高含量固体颗粒填充高分子聚合物的双相共混体系,连续相为BAMO-AMMO黏结剂基体,分散相为RDX颗粒,RDX颗粒和BAMO-AMMO黏结剂基体可形成良好的黏结界面;原生孔洞是发射药药体的主要缺陷,其低温冲击破坏主要是黏结剂基体之间的脆性断裂,而非RDX颗粒与BAMO-AMMO基体的脱黏;RDX/BAMO-AMMO基发射药燃烧过程具有明显的RDX颗粒爆燃特性,RDX颗粒爆燃及药体孔洞缺陷容易导致发射药非平行层燃烧,通过选用无溶剂成型工艺和添加DIANP增塑剂的技术途径可减少药体孔洞缺陷,药体密度由1.45g/cm^3增至1.63g/cm^3,有益于改善RDX/BAMO-AMMO基发射药的力学强度和燃烧稳定性。

关键词： 物理化学   线上教学   教学改革  

摘要： 面对突如其来的疫情,本教学团队教师通过选择合适的授课平台、适合网课的授课片段、引入合适的思政内容和丰富的绪论知识等等,使学生能够更直接的和教师“面对面”探讨课程内容。学生返校后,通过线下串讲课程内容,使同学们将网课内容在脑海里“放映”出来,更有针对性的复习,最终都取得了良好的成绩。本文对线上授课的优点和不足进行了总结,以期对今后继续进行线上线下授课给以指导。

关键词： 混合式学习   冶金物理化学   教学改革  

摘要： 冶金物理化学是冶金工程专业重要的基础课。在混合式教学中,教师可以利用“互联网+”先进信息技术实现以学生为中心的教学,同时充分发挥自身的引导和启发作用。为了提高教学质量和效果,本文探讨了如何将线上线下相结合的混合式教学引入冶金物理化学教学实践,尝试探索一种有效的混合式教学模式。

关键词： Chemical stability  

摘要： Multiple O-1/W/O(2)nanoemulsions and O-1/W nanoemulsions fortified with CLA or CoQ(10)were produced using extra virgin olive or olive pomace oil and were also incorporated with polyphenols extracted from olive kernel to enhance their kinetic and chemical stability. They were prepared using a high-speed ultrasonic homogenizer. Specifically, nanoemulsions with 6 wt% lipid phase and 6 wt% non-ionic emulsifier (Tween 40) were produced and they demonstrated a droplet diameter >200 nm and high encapsulation stability during 30 days of storage at 4 degrees C or 25 degrees C. The incorporation of CLA or CoQ(10)and polyphenolic compounds facilitated the homogenization of emulsions, reducing the droplet size and enhancing their chemical stability, and their bioactive retention values were >79%. O-1/W/O(2)nanoemulsions were produced using a mixture of non-ionic emulsifiers (Span 20 and Tween 40) and the O-1/W enriched nanoemulsion as the dispersed phase. All multiple emulsions showed a bimodal droplet size distribution and Newtonian behavior while polyphenols facilitated their homogenization. Both vegetable oils resulted in samples with high kinetic and chemical stability;the bioactive retention values were found to be >80% at the end of 30 days of storage at 4 degrees C or 25 degrees C. Extra virgin olive oil resulted in more stable nanoemulsions in regards to kinetic and chemical stability at 4 degrees C, showing limited creaming and sedimentation boundary. Multiple nanoemulsions with the lowest initial droplet size presented the lowest droplet diameter growth and phase separation and the highest retention values. By comparing O-1/W nanoemulsions and O-1/W/O(2)nanoemulsions, we noted that the reduction in the total phenolic content and antioxidant activity during storage was higher in the O-1/W type. However, both delivery systems protected CLA and CoQ(10)presenting high retention during storage. FTIR spectra before and after ultrasonic homogenization indicated that the soni

关键词： 征订工作   物理化学学报   学术刊物   中国化学会   交叉学科   工程学院   人物专访   学报编辑部  

摘要： 2021年全国报刊杂志征订工作已经开始,敬请向贵单位推荐订阅2021年《物理化学学报》。《物理化学学报》是由中国科学技术协会主管,中国化学会和北京大学共同主办,北京大学化学与分子工程学院学报编辑部编辑出版的学术刊物。设有“亮点”、“当期推荐”、“通讯”、“展望”、“专论”、“综述”、“论文”、“人物专访”等栏目,报导物理化学学科及交叉学科的基础研究及应用研究的创新成果。

关键词： 砂岩   溶蚀速率   质量变化率   pH   动力学模型  

摘要： 目的研究受酸腐蚀砂岩的物理化学性质,建立酸岩反应动力学模型,为酸性环境下的工程耐久性评价提供参考.方法通过室内长期加速腐蚀试验,监测不同浸泡时段岩样的质量变化和浸泡溶液的pH值及Na+、K+、Mg2+、Ca2+等阳离子浓度的变化.结果反应初期(0~90 d)阳离子的溶蚀速率较高,随着腐蚀时间的延长,化学反应速率降低,阳离子的溶蚀速率延缓,反应后期溶蚀速率又逐渐增大;随着腐蚀时间的延长,烘干岩样的质量损失率不断增大,而湿岩样的质量增长率呈先增大而后减小的趋势;各阶段硫酸溶液pH值总体呈增大趋势.结论受酸腐蚀岩样质量、浸泡溶液pH值以及阳离子浓度的变化具有明显的阶段性劣化特征;反应由扩散和化学反应共同作用,其中化学反应为烘干岩样主导作用,扩散作用为湿岩样前期主导作用,后期化学反应和内扩散共同主导;酸岩反应动力学模型较准确地表达了硫酸溶液腐蚀下岩样质量与时间的变化关系.

关键词： 课程思政   育人效果   以学生为中心   物理化学   教学策略   培养方案   专业课教学   专业知识  

摘要： “两点双线”教学策略在“物理化学”课程教学中的运用,强调教师以学生为中心,从培养方案和教学大纲入手,确定课程思政目标,在教学过程中将专业知识(外线)和课程思政建设(内线)相结合,重构知识内容,以情境素材为依托,找到内线和外线的映射点和融入点,达到“润物细无声”的育人效果。

关键词： CO2 atmosphere   Char physicochemical structure   Reactivity   Pressurized drop tube furnace  

摘要： The effects of the total pressure (0.1-1.3 MPa) and the CO2 partial pressure (0-0.45 MPa) on the physical structural properties, chemical structural properties and reactivity of Shenhua coal pressurized char at 1273 K were investigated in a pressurized drop tube furnace (PDTF). There were reverse-direction effects on char yield between total pressure and CO2 partial pressure for char preparation. Porosity characteristics were performed using an ASAP2020 instrument. It was found that same-direction increment effects on BET surface and porosity between total pressure and CO2 partial pressure for char preparation. Carbon structure and surface structure were performed by Raman and XPS methods. The results showed that both total pressure and CO partial pressure can promote the transformation of small aromatic structures to large aromatic structures and increase the graphitization degree of the char. With increasing total pressure and CO2 partial pressure, the unstable N-5 content decreased, while the N-6 and N-Q content increased. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： XRF   SEM   Stone waste   Stone slurry   Construction material  

摘要： The use of sandstone as a building material has increased around the world and sandstone quarrying and its wastes pose a potential threat to human health and the environment. More than 50% of the excavated stone is wasted in the form of scrap stone and waste slurry during sandstone quarrying and processing. Sandstone wastes can adversely change native soil properties and should be reused as construction material. The present study aimed to characterise wastes generated during sandstone quarrying and processing, assess their impact on the soil environment and explore their reuse potential. The results of this study show that fine slurry waste has physicochemical properties between sand and sandy loam while the properties of the slurry solids and scrap stone are similar to those of sandstone. Fine stone waste on intrusion into soil reduced the hydraulic conductivity and porosity of soil potentially reducing its productivity. The liquid stone slurry contained metals like Mn, Ni and As at concentrations higher than drinking water standards. These metals may contaminate water sources and affect human health. Therefore, the use of stone wastes as aggregate for road and building construction would be beneficial and would reduce their adverse impacts on the environment.

关键词： aging   artificial reservoir   eutrophic   limnological   marginally hypertrophic   physico-chemical  

摘要： The physico-chemical limnology and trophic status of the Tugwi-Mukosi reservoir were assessed seven months after impoundment. Water temperature, conductivity, pH, dissolved oxygen, transparency, nitrates, total nitrogen, orthophosphates, total phosphorus and metals (K, Na, Ca, Mg, Cu, Cd, Cr, Ni, Hg, Mn, Zn, Pb, Fe and As) were measured at five sites distributed across the Tugwi-Mukosi reservoir in July 2017. The reservoir was turbid after impoundment and had low water clarity. The trophic state of the reservoir ranged from eutrophic to marginally hypertrophic with high total phosphorus and total nitrogen concentrations. All measured physico-chemical water variables did not differ significantly between the lake sites with the exception of conductivity, ammonia and total phosphorus. Potassium, Na, Ca and Mg were high in the reservoir, whereas other heavy metals recorded low concentrations. Iron was relatively high with an average concentration of 0.24 mg l(-1). The average Ca:K, Ca:Na and Ca:Mg ratios in the reservoir were 3.8, 1.1 and 3.2, respectively. The high Ca:Mg of 3.2 might favour the establishment of snails. Eutrophication of the Tugwi-Mukosi Reservoir should be abated through coordinated management of the reservoir and the terrestrial environment in the catchment to ensure that the water quality is able to support lake biodiversity and confer ecosystem services to human livelihoods around the reservoir.