教学课程资源库 更多>>

关键词： 物理化学实验   教学探索   DFT计算  

摘要： 文章以乙酸乙酯皂化反应为例,对密度泛函理论(DFT)应用于物理化学综合性实验教学进行了研究。基于DMol3软件进行了结构建模和构型优化,采用LST/QST方法计算了反应活化能和反应路径,预测并验证了反应的活性位点,为皂化反应的作用机理提供了理论依据。该综合实验灵活运用了物理化学、结构化学和有机化学等多学科的知识点,有助于学生全面认识化学反应过程的微观作用机理,提高了他们的学习兴趣和创新能力,为通过学科交叉提升实验教学水平提供了新思路。

关键词： 课程思政   物理化学   立德树人  

摘要： 目前全国高校都在推进课程思政建设,强调要坚持把立德树人作为中心环节,把思想政治工作贯穿教育教学全过程。该文以物理化学课程为例,从不同方面对物理化学课程中的思政元素进行了挖掘,实现了专业知识教育与思想政治教育的有机统一,使学生在专业课程教育中树立正确的价值观,成为新时代的接班人。

关键词： 质子化离子液体   水分影响   黏度   电导率   离子性  

摘要： 通过Brønsted酸碱中和反应,合成了由碱正己胺(hexylamine,Hexam)与酸双三氟甲基磺酰亚胺[bis(trifluoromethylsulfonyl)imide,HTf_(2)N]形成的质子化离子液体(protic ionic liquids,PILs),简称为HHexam(Tf_(2)N)型PILs,其疏水性较强,但仍溶解少量水,其中饱和水含量可达6.33%(w_(0)=[H_(2)O]/[PIL]=1.44)。PILs中水分含量的多少对其物理化学性质影响较大,因此本研究在温度T=303.15~353.15K的范围内、不同含水量(w_(0)=0.12、0.23、0.47、0.74、1.0、1.28)条件下,测定了HHexam(Tf_(2)N)的密度、黏度及电导率。结果显示,在相同温度条件下,随着水分含量的增加,其密度和黏度值均降低,电导率升高。在相同含水量条件下,随着温度的升高,其密度值呈直线下降,黏度均呈指数下降趋势,电导率均呈指数上升趋势,并且lnη、lnσ与1000/T之间基本呈线性关系,基本符合Arrhenius方程。在w_(0)=0.12~1.28范围内,HHexam(Tf_(2)N)的Walden线均在ΔW=0.5~1.0内,离子性较好,并且随着水分含量的增加,其Walden线靠近KCl理想线,即离子化程度增大。另外,当漏极电压为-0.6V时,由HHexam(Tf_(2)N)制备的聚(3,4-亚乙二氧基噻吩)有机电化学晶体管(PEDOT OECT)的最大跨导(2.79mS)为水溶液获得的PEDOT:PSS OECT最大跨导(0.832mS)的3.4倍。

关键词： Heat-moisture treatment   Amylose inclusion complexes   Stearic acid  

摘要： Starch modification has been extensively studied to alter its physicochemical properties based on human needs. Lowering the digestion rate of starch is one of the interests in food science research, since when it is nutritionally improved, it can reduce the risk of human chronic diseases. In this study, heat-moisture treatment (HMT) followed by inclusion complexation with stearic acid at various temperatures and times was applied to improve the functional properties of starch. Thermal analysis suggested the formation of type I and type II complexes after complexation at 90 degrees C, indicated by a endothermal peak at 107 and 122 degrees C, respectively, while native starch after complexation only resulted in type I complexes. The formation of crystalline complexes was also confirmed by XRD showing peaks at 20 - 13.1 degrees and 20.1 degrees. Furthermore, the modified starch displayed a higher pasting temperature, considerably less swelling and significantly lower viscosity behavior. This implied that the starch granules were thermally and mechanically more stable. The granular appearance of the modified starch was confirmed with light microscopy that presented more intact granules and less ruptured granules, even after heating to 90 degrees C. This study offers a way to upgrade the nutritional properties of starch. (C) 2021 The Authors. Published by Elsevier B.V.

关键词： 物理化学   高品质RDX   DNAN   2,4-二硝基苯甲醚   溶解度   反复熔融  

摘要： 为研究高品质RDX在2,4-二硝基苯甲醚(DNAN)中的溶解及反复熔融特性,采用高效液相色谱法研究了高品质RDX在DNAN中的溶解度及影响因素;通过工艺试验研究了DNAN/高品质RDX熔铸炸药在反复熔融后的不可逆增稠特性;运用热台显微装置研究了高品质RDX在DNAN中的溶解及析出过程,并与普通RDX(3类)进行了对比。结果表明,随着高品质RDX粒度的增大,其在DNAN中的溶解度逐渐减小,呈近似线性关系;高品质RDX在DNAN中的溶解度随温度升高而增大,115℃时高品质RDX(d50=470μm)在DNAN中的最大溶解度达到8.87g/100g,在不同温度下溶解度均小于普通RDX;DNAN/高品质RDX配方在反复熔融后的不可逆增稠程度小于DNAN/普通RDX配方;高品质RDX在DNAN中的溶解首先从晶粒的不规则外沿和晶体凹陷区域开始,溶解速率受颗粒尺寸及不规则程度影响,且明显慢于普通RDX;析出存在两种方式且析出后形状呈不规则变化。

关键词： Silver-kaolinite nanocomposite   Pyro-fabrication   Antimicrobial nanoagent   Antimicrobial resistance   Silver nanocrystallization   Surface charge  

摘要： The present research aims to enhance the antimicrobial activity of kaolinite surfaces by a one-step cost-effective and energy-efficient dry thermal reaction, producing an antibacterial and antifungal silver-kaolinite (Ag-Kao) nanocomposite agent. Pharmaceutical grade kaolin powder samples, with variable kaolinite structural order-disorder degree, were homogeneously mixed with silver nitrate in a proportion 1:4 AgNO3:kaolin (w/w) and sintered at 400 degrees C for 30 min. The composition, microstructure, microtexture and surface characteristics of the pyro-fabricated nanocomposites were characterized by XRD/XRF diffractometry, differential scanning calorimetry DSC, FT-IR spectroscopy, TEM/EDX, zeta potential (mV) measured within the 2-12 pH range, and BET method. Physicochemical stability was evaluated by silver dissociation testing under close-neutral and acidic conditions with Ag content assay using ICP-OES. The resulting Ag-Kao nanocomposites exhibited bulk silver contents ranging from 9.29% to 13.32% with high physicochemical stability in both neutral and acidic mediums (Ag dissociation rate <0.5% in 5 days). Ag nanocrystals exhibited particle sizes ranging from 5 to 30 nm, which were embedded and reinforced within the kaolinite matrix. The sizes of the Ag nanocrystals and their distribution patterns on the edges and faces of kaolinite platelets were controlled by the structural order-disorder degree. Highly ordered kaolinites (Hinckley Index, HI > 1) produced platelet edge-clustered silver nanocrystals due to the abundance of the dangling hydroxyls on platelet edges, while the highly disordered kaolinite (HI < 1) provided homogeneous platelet basal-doped silver nanocrystals due to the presence of some residual charges by exposed basal hydroxyl groups with interplatelet silver diffusivity. At pH 2, the magnitude of the positive surface charge was influenced by the silver nanocrystal size. Nanocomposites with the smallest silver nanocrystals (10-5 nm) exhibited the

关键词： 物理化学   研究生   化学反应动力学   科研前沿  

摘要： 针对研究生物理化学教学中较抽象的过渡态理论知识点,探讨前沿科研成果对经典过渡态理论的发展,培养学生的创新兴趣、多元化思维及科研素质。通过实例教学,使知识点内容具体化,全面提高学生的综合能力和独立思考能力。

关键词： Liquid hydrocarbon fuel   Physicochemical properties   Composition   Molecular structure   Fuel properties correlation  

摘要： The development of advanced air transportation has raised new demands for high-performance liquid hydrocarbon ***,the measurement of fuel properties is time-consuming,cost-intensive,and limited to the operating *** physicochemical properties of aerospace fuels are directly infl uenced by chemical ***,a thorough investigation should be conducted on the inherent relationship between fuel properties and composition for the design and synthesis of high-grade fuels and the prediction of fuel properties in the *** work summarized the eff ects of fuel composition and hydrocarbon molecular structure on the fuel physicochemical properties,including density,net heat of combustion(NHOC),low-temperature fl uidity(viscosity and freezing point),fl ash point,and thermal-oxidative *** correlations and predictions of fuel properties from chemical composition were ***,we correlated the fuel properties with hydrogen/carbon molar ratios(n H/C)and molecular weight(M).The results from the least-square method implicate that the coupling of H/C molar ratio and M is suitable for the estimation of density,NHOC,viscosity and eff ectiveness for the design,manufacture,and evaluation of aviation hydrocarbon fuels.

关键词： 肺癌   固体燃料   扫描电镜   能量色散X射线光谱仪   P(X)值  

摘要： 在云南宣威肺癌高发区采集了固体燃料(煤炭、木材)燃烧排放的大气颗粒物样品,利用扫描电镜(scanning electron microscopy,SEM)、能量色散X射线光谱仪(energy dispersive X-ray spectroscopy,EDX)对796个颗粒物进行了分析.根据颗粒物的显微特征和化学元素组成,将其分为矿物颗粒物、飞灰、烟尘集合体和未识别颗粒物4类.采用P(X)值法将矿物颗粒物进一步分为富Si、富S、富Ca、富Fe、富Ti、富Al、富Na和其他8种不同类型,其中富Si、富Ca、富Fe、富S分别占燃煤颗粒物和生物质颗粒物的44.47%,20.49%,8.85%,1.22%和55.91%,17.27%,6.36%,2.27%.化学元素分析结果显示:颗粒物中Al,Fe,Ca,Mg等地壳元素的质量浓度较高,重金属化学元素的质量浓度较低;煤炭燃烧排放的颗粒物的化学元素分析结果与单颗粒分析结果之间存在较好的正相关关系(R2=0.63).

关键词： 物理化学   电化学   竞争反应  

摘要： 提出电解时电极上竞争反应分析的策略,能使电极上竞争反应的分析更具操作性、普适性及简洁性,有利于竞争反应次序的确定和外加电压及离子残余浓度的计算,为电解和电镀等工业的应用提供理论依据,且能激发学生学习物理化学中电化学知识的热情。