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关键词： 物理化学   在线开放课程   建设   应用  

摘要： 介绍了南京大学物理化学在线开放课程的建设工作及特点,结合疫情期间进行物理化学线上教学的实践经验,讨论了物理化学在线开放课程的应用,为物理化学课程的线上教学提供参考。

关键词： Banana starch   pectin   heat-moisture treatment   LOS-plot   digestibility   physicochemical properties  

摘要： Interaction of pectin with starch modified by heat-moisture treatment (HMT) was evaluated. HMT preserved the presence of starch fractions with k(1) and k(2) (digestion rate constants at rapid and slow phase, respectively) being 4.5 and 0.42 x 10(-2) min(-1). Compared to the native starch, HMT starch had lower k(1) and k(2) probably due to the change in crystalline type. HMT increased total digestible starch from 1.02% in native to 27.23% in HMT starch. The decrease in k(1) and/or k(2) with the increase in pectin might be linked to the effect of viscosity or pectin-amylase interaction, while the decrease in digestible starch at rapid phase (C-1 infinity) could be attributed to pectin-starch interaction. Pectin affected significantly water absorption capacity, syneresis, cohesiveness and gumminess of HMT starch but did not alter those of native starch. The effect of HMT on functional, textural and pasting properties was more remarkable than the effect of pectin.

关键词： Chlorophyll-a   Nutrients   Dissolved silica   Dam   Hydrologic alterations  

摘要： Periodically hydrologic alterations driven by seasonal change and water storage capacity management strongly modify physicochemical properties and chlorophyll-a(Chl-a)and their interactions in dam-induced ***,the extent and magnitude of these changes still remain *** study aimed to determine the effects of periodically hydrologic alterations on physicochemical variables and Chl-a in the dam-induced urban Hanfeng Lake,upstream of Three Gorges *** in Chl-a and 13 physicochemical variables were recorded monthly in the lake from January 2013 to December ***-a was neither seasonal nor inter-annual differences while a few physical variables such as flow velocity(V)exhibited significantly seasonal variabilities,and chemical variables like total nitrogen(TN),nitrate-nitrogen(NO3-N),total phosphorus(TP),dissolved silica(DSi)were markedly inter-annual *** TN:TP(40:1)and lower NO3-N:DSi(0.8:1)relative to balanced stoichiometric ratios suggested changes in composition of phytoplankton communities and potentially increased proportion of diatom in Hanfeng ***-a was predicable by combination of dissolved oxygen(DO),TN and DSi in dry season,and by V alone in wet *** the whole study period,Chl-a was solely negatively correlated with TN:TP,indicating decline in N concentration and increase in P could therefore increase *** results highlight pronounced decoupling of linkages between Chl-a and physicochemical variables affected by periodically hydrologic alterations in dam-induced aquatic systems.

关键词： 物理化学   在线教学   科研促进教学  

摘要： 物理化学是兼具基础性和前沿性的专业基础课程。在在线教学实践中,充分利用各种网络资源,在在线教学系统中通过课程视频、课程资料、课程讨论等方式引入多种与课程相关的科技资讯,与课程教学和考试命题融合,达到丰富课程内容、激发学生学习兴趣的目的。通过疫情期间的教学实践,取得了较好的教学效果,并为今后开展线上线下混合教学的新模式奠定了基础。

关键词： 物理化学   综合性实验   酸碱中和反应   原电池设计  

摘要： 基于物理化学电化学理论,由本科生将酸碱中和反应设计为原电池并予以实现。通过项目实施,有效增强学生对物理化学课程的学习兴趣,加深其对电化学理论知识的理解,使学生建立起对科学研究的直观认识,提升学生科学研究素养,开阔学术视野,强化将理论知识应用于实际的能力,为创新物理化学课程教学模式做出积极的探索。

关键词： Chitosan films   Succinic acid   Neutralization   Amide bonds  

摘要： In this work, chitosan-succinic acid membranes were prepared by casting method and the physicochemical and mechanical properties of non-neutralized and neutralized with NaOH films were compared. Mechanical strength, flexibility, thermal stability and water-vapor permeability of chitosan membranes are significantly improved after neutralization. These improvements could be partly ascribed to the use of a dicarboxylic acid, which decreases the spacing between chitosan chains as a consequence of ionic crosslinking. Moreover, the addition of the strong base to the hydrogel promotes the formation of amide bonds, as suggested by FTIR analysis and demonstrated by acid-base titration. The favorable features of chitosan-succinic acid films as well as the possibility to easily incorporate drugs, enzymes, essential oils or other additives in the hydrogel, make such membranes suitable for many applications.

关键词： Alkylammonium salts   Physicochemical properties   Structure   Hydrogen bond   Ion-ion interaction  

摘要： In this paper, we mainly focus on protic ionic liquids (PILs) based on alkylammonium cations with the general formula R4NH4-n (n = 1-3, R = Me, Et, Pr, Bu). Protic ionic liquids, as other ILs, have a lot of useful properties, such as good thermal and electrochemical stability, a wide temperature range of liquid state, low flammability, and a simple synthesis procedure, which make them very attractive for a wide range of practical applications. We report the experimental data such as thermal properties (decomposition, melting, and glass transition temperatures), electric conductivity, viscosity of a series of alkylammonium-based PILs and consider their structural features associated with hydrogen bond formation. The effect of the structure/nature of cations and anions of 13 different acids on the above-mentioned properties and the structure of these PILs are discussed. Among the PILs considered, the best studied ones are the salts composed of anions of sulfuric, trifluoromethanesulfonic, and formic acids, and ethylammonium and triethylammonium cations. In this work, we analyze the properties of alkylammonium salts including both the ones investigated in our laboratory (the new data and results published earlier) and those presented in the literature. (C) 2020 Elsevier B.V. All rights reserved.

关键词： 北大教授   中国科学院学部   北京协和医学院   物理化学家   博士学位   麻省理工学院   理学学士学位   早期教育  

摘要： 2021年1月2日是我国著名物理化学家、化学教育家,中国科学院学部委员(院士),清华、北大教授黄子卿诞辰121周年纪念日。黄子卿(1900.1.2—1982.7.23),字碧帆,出生于广东省梅州市梅县区槐子岗村。1904年,在本村私塾受启蒙教育。他的外祖父和舅父古文造诣颇深,藏书甚丰,给了黄子卿很好的早期教育和深刻的影响。1915年,黄子卿考入长沙雅礼中学。该校有一个清末曾中探花的汪姓教师,任教文学与算术。他发现黄子卿在数学方面颇具天赋,建议他以学数理为宜。这对黄子卿以后献身科学事业起了很大影响。1919年,黄子卿中学毕业,考入清华留美预备班第7期,1921年6月结业。1922年9月,黄子卿入美国威斯康星大学,主修化学,1924年毕业,获理学学士学位。随即转入康奈尔大学,于1925年获理学硕士学位。同年9月入麻省理工学院化学系,攻读博士学位。后因公费到期,1927年12月结业回国。黄子卿回国后首先在北京协和医学院生物化学系作助教。在吴宪教授指导下做蛋白质变性研究。

关键词： Agar   Octenyl succinic anhydride   Characterization   Rheology  

摘要： A novel amphiphilic agar with high transparency and freeze-thaw stability was prepared using octenyl succinic anhydride (OSA). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed that the hydrophobic OS groups were successfully introduced in OSA-modified agar (OSAR) backbone. The OSAR showed higher emulsion stability and oil loading capacity than the native agar (NA). Compared with gel transparency (47.1 %), syneresis (42.1 %) of NA, OSAR exhibited high gel transparency (80 %) and low syneresis (3.3 %) when the degree of substitution (DS) was 0.06 and 0.12, respectively. Meanwhile, the OSAR showed a decreased interface tension and average molecular weight after modification. Thermogravimetric analysis indicated the thermal stability of OSAR was decreased, while texture profile analysis showed the springiness of the OSAR gel was enhanced. Dynamic rheology measurements revealed the OSAR with low gel strength displayed more liquid-like properties. Moreover, the OSAR exhibited lower turbidity and melting temperatures than the NA.

关键词： 物理化学家   徐光宪   伯克利   谢有畅   博士生导师   罗伦兹  

摘要： 谢有畅,物理化学家,长期从事物理化学、结构化学和固体表面化学的教学与研究工作。1934年出生于广州,1953年毕业于中山大学化学系,后被选入北京大学攻读物理化学专业研究生,师从徐光宪院士。1957年毕业后留校任教,担任唐有祺院士助教,长期在唐有祺老师指导下从事研究工作。1984-1985年在美国加州大学化学系和罗伦兹伯克利国家实验室担任客座教授。1985年被北京大学授予教授学衔并被教育部特别批准为博士生导师。