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关键词： 瓦尔特·能斯特   物理化学   德国科学  

摘要： 19世纪末德国的科学逐渐兴起,这段时间涌现出一批具有新思想的科学家,其中的代表人物之一就是德国物理化学家瓦尔特·能斯特。能斯特是德国著名的物理学家、物理化学家,他一生在多所大学和研究所从事研究和教学工作,为物理、化学等学科的发展做出了贡献。通过研读瓦尔特·能斯特的传记等材料,结合19—20世纪德国科学发展的情况,研究他的成长经历和科研经历,论述他与德国科学发展之间的联系,并剖析他成功的因素。

关键词： 焦化场地   污染特征   修复技术   环境风险  

摘要： 一直以来,焦化行业在我国能源和化工领域占据十分重要的地位,但焦化过程中产生大量焦化污染场地。随着环保意识的加强,国家逐步对焦化场地进行调查与修复。本文重点探讨了我国焦化场地的污染特征、修复技术原理与特点,并探讨了各修复技术对焦化污染土壤的修复效果。

关键词： Polycyclic aromatic hydrocarbons   Biomass combustion   Air pollution   Carcinogenicity   Aerosol size distribution  

摘要： Transboundary haze from biomass burning is one of the most important air pollutions in Southeast *** most recent serious haze episode occurred in *** Thailand was affected by the haze during September to October when the particulate matter concentration hit a record *** investigated physical and chemical characteristics of aerosols,including concentration and aerosol size distribution down to sub-micron sizes during haze episodes in 2013 and 2015 and,for reference,an insignificant haze period in *** highest total suspended particulates and PM 10 levels in Hat Yai city were 340.1 and 322.5μg/m^*** mass fractions were nanoparticles(<100 nm)3.1%-14.8%and fine particles(<1μm)54.6%-59.1%.Polycyclic aromatic hydrocarbon size distributions in haze periods peaked at 0.75μm and the concentrations are 2-30 times higher than the normal *** molecular weight(4-6 ring)PAHs during the haze episode contribute to about 56.7%-88.0%for *** average values of benzo(a)pyrene toxic equivalency quotient were 3.34±2.54ng/m^3 in the 2015 haze period but only 0.89±0.17 ng/m^3 in *** is clear that particles smaller than 1μm,were highly *** contributed 19.4%-26.0%of total BaP-TEQ,whereas the mass fraction is 13.1%-14.8%.Thus the nanoparticles were more carcinogenic and can cause greater health effect than larger *** fraction of BaP-TEQ for nanoparticles during 2017 non-haze period was nearly the same,while the mass fraction was *** indicates that nanoparticles are the significant source of carcinogenic aerosols both during haze and non-haze periods.

关键词： 物理化学   高聚物黏结炸药   PBX   micro-CT   热损伤   聚二甲基硅氧烷   PDMS   孔隙率  

摘要： 为研究环四亚甲基四硝胺(HMX)基高聚物黏结炸药(PBX)在高强度热载荷(室温~200℃,10h)作用下的热损伤行为,使用微米计算机断层扫描技术(micro-CT)定量表征了试验前后HMX基PBX的内部微米级孔隙变化,结合样品尺寸、质量、真密度和微观形貌的变化分析了热载荷对HMX基PBX的损伤情况。结果表明,在160℃时,样品体积、质量和真密度无显著变化;经过180℃处理后,样品发生了不可逆的体积膨胀,质量未发生变化,真密度降低8.76%;200℃处理后,由于质量降低、体积膨胀,样品表面出现孔隙和裂纹导致样品真密度降低9.92%;根据细观观测和统计计算,样品孔隙率随试验温度升高呈现先升高后降低的趋势,在180℃时最高为7.81%,200℃时又呈现下降趋势;180℃时HMX晶粒发生相变,产生的大量微裂纹和颗粒之间脱粘增大了PBX的孔隙率;200℃时,HMX颗粒细化填充部分空隙,导致孔隙率较180℃时降低,但黏结剂未发生熔化,对孔隙率的变化影响不大。

关键词： Pyrodextrin   Glycosidic linkage structure   Digestibility   NMR  

摘要： Glycosidic linkage structure, physical-chemical properties and in vitro digestibility of pyrodextrins prepared using different reaction conditions were characterized. Intensification of reaction condition promoted starch hydrolysis and transglucosidation until the solubility of pyrodextrin reached 100%. New branch points were formed including alpha-1,2, beta-1,2, beta-1,4, beta-1,6 and alpha-1,6 linkages. Majority of the branch points was alpha-1,6 and beta-1,6 linkages which in together accounted for more than 70% of the total branches. The degree of branching increased at intensified reaction conditions and plateaued at approximately 24%. Exhaustively hydrolyzing pyrodextrin by alpha-amylase and amyloglucosidase significantly decreased the degree of alpha-1,4 but not alpha-1,6 linkages. The retained alpha-1,4 and alpha-1,6 linkages were probably protected from enzyme hydrolysis by the non-starch linkages due to steric hindrance. The resistant starch content was positively correlated with the degree of branching of pyrodextrin. The decreased in vitro digestibility of pyrodextrin was attributed to the formation of new glycosidic linkages.

关键词： Schizophyllum commune   Schizophyllan   Extraction methods  

摘要： Water-soluble polysaccharides from Schizophyllum commune (SPGs) were extracted using different methods including hot-water extraction (HWE), ultrasound-assisted extraction (UE), microwave-assisted extraction (ME) and high pressure extraction (HPE). The physicochemical characteristics, antioxidant activity and hypoglycemic activity of four different SPGs were investigated. The results indicated that the polysaccharides yield (8.26%), uronic add content (3.0%), total polysaccharides content (67.96%) and molecular weight (52.7 kDa) of SPGs extracted by HWE were higher than those obtained by other methods. FT-IR spectra and conformation information of four SPGs were similar, however, the color characteristics, the monosaccharide species and molar ratios, the solubility and micro-structure of each SPGs were significantly different. Though the molecular weight (11.0 kDa) of UE-SPGs was lowest, it showed the highest antioxidant activity and hypoglycemic activity. It could be considered that the UE extraction method might be a good potential extraction technique for the SPGs with high bioactivities. (C) 2019 Elsevier B.V. All rights reserved.

关键词： 教学改革   能力培养   综合设计型实验   物理化学  

摘要： 物理化学实验在化学及其相关专业本科实验课程体系中占有重要地位。为满足能力培养需要,传统物理化学实验教学应当向综合设计型实验教学转变,实验教学内容应向生产实践和科学研究对化学提出的问题发展,课前、课中、课后相结合的教学设计用于引导学生自主学习并建立多元公正的全过程评价指标体系以评促学。这一改革发挥了教师的引导作用,学生的能动构建作用,有助于提升教学质量,培养学生的应用能力和创新能力。

关键词： 线上教学   物理化学   新冠肺炎   慕课  

摘要： 疫情期间,高等学校以停课不停教、停课不停学为行动指南,开展线上教学。慕课(MOOC)等网络教学平台免费提供的教育资源,使学生的学习内容优质化、学习途径多样化,实现了教育公平。《物理化学》课程具有公式多,概念抽象等特点,其线上教学可充分利用网络资源,得到更丰富的教学素材。以《物理化学》课程中偏摩尔量一节为例,利用泛雅网络教学平台,基于BOPPPS模式进行线上教学过程分析,阐述了线上教学的优势和缺陷,并提出解决方案,最后总结了特殊时期,教师通过课堂思政,宣传疫情带给师生的启示和力量。

关键词： Okra (Abelmoschus esculentus (L.) Moench)   Polysaccharide   Preparation   Characterization   Bioactivity  

摘要： In this study, three-phase partitioning (TPP) coupled with gradient ammonium sulfate ((NH4)(2)SO4) precipitation (GNP) method was first used to extract and separate bioactive polysaccharides (OPSs) from fresh okra pods. Results showed that OPS-50 obtained by GNP at a saturation of 50% (NH4)(2)SO4 after TPP presented higher precipitation yield, carbohydrate (86.82%) and uronic acid (22.34%) contents with same monosaccharide composition and different molar ratios compared with OPS-30 and OPS-40 obtained via GNP at saturations of 30% and 40% (NH4)(2)SO4, respectively. OPS-50 had lower weight-average molecular weight (3.65 x 10(6) g/mol), more flexible chain, and relatively looser surface structure compared with OPS-30, OPS-40, and the OPS obtained with TPP parallelized with decreased apparent viscosity and dynamic viscoelasticity. Furthermore, OPS-50 exhibited stronger DPPH radical-scavenging ability, antioxidant capacity, and alpha-amylase and alpha-glucosidase inhibitory activities in vitro than OPS, OPS-30, and OPS-40.

关键词： 网络化教学   网络平台   物理化学实验  

摘要： 随着物理化学实验网络化教学模式的不断完善,传统的物理化学实验教学模式渐渐出现一些问题.通过研究物理化学实验网络化教学课程的构建,提出日后物理化学实验网络化发展的预想,明确了发展方向.