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关键词： 物理化学   课程思政   教学设计   教学实践   教学评价  

摘要： 推进专业课程与思政教育融合是落实高校立德树人的根本。物理化学作为化学类核心专业基础课程,对学生的培养起着至关重要的作用。依据课程思政内涵,结合物理化学课程教学目标,从学科发展史、科学家简介、经典理论和方法、学科交叉、科学发展前沿以及物理化学在生产生活中的应用等6个方面挖掘梳理课程蕴含的思政教育要点,并进行相应的教学设计。同时给出了课程思政教学实践模式和评价方法。

关键词： Gemini surfactant   Spacer group   Surface/interface properties   Electrolytes tolerance and thermal stability  

摘要： Three Gemini surfactants with the same hydrophobic chain but different spacer groups, including two cationic Gemini surfactants (CGS and CGS-O) and a zwitterionic Gemini surfactant (ZGS-S), were synthesized, and their chemical structures were characterized by FT-IR and H-1 NMR. The effect of spacer group on surface/interface activity, interfacial tension at the oil-water interface, wetting ability, electrolytes tolerance and thermal stability was determined. The results showed the structure of spacer group has a certain influence on the surface/interface activity. Among the three Gemini surfactants, ZGS-S has the strongest ability to reduce surface tension, followed by CGS-O. Three Gemini surfactants can reduce the oil-water interfacial tension to ultra-low value, but the time required to reach the minimum value is different, indicating that the surfactant molecules move at different adsorption rates from solution to the interface. This phenomenon is also confirmed by dynamic surface tension and dynamic contact angle tests. Compared with CGS, CGS-O molecules move slower in the solution, while the adsorption rate of ZGS-S on the interface surpasses that of CGS near the critical micelle concentration. Among the three Gemini surfactants, the electrolytes tolerance of ZGS-S is the strongest, while CGS-O is the lowest. The introduction of sulfate group in spacer group reduces the thermal stability of Gemini surfactant. (C) 2020 Elsevier B.V. All rights reserved.

关键词： 在线教学   数字化自主学习   物理化学   翻转课堂   混合式教学  

摘要： 基于新冠肺炎疫情的影响,学校的教学资源配制及课堂教学环节由线下转为线上,使在线教学成为主导授课方式。然而在实施过程中,师生双方都出现了诸多困扰与挑战,如教师对教学资源的建设和教学策略的选择、学生对新学习模式的适应和有效的自我管理等。为了保障物理化学课程的顺利开展和在线教学效果,建设了以超星泛雅(学习通)和异步SPOC为两翼的平台教学资源;采用轻中度翻转混合式教学模式实施在线教学,并采取多种策略引导学生积极参与教学活动。实施结果表明学生的数字化自主学习能力得到了明显提升,课堂效果明显。

关键词： 课程思政   HPS模式   物理化学  

摘要： 利用HPS教学模式,将思政元素融入到物理化学课程教学中。针对农业院校中物理化学课程理论性强、覆盖专业多、选课学生多的特点,提出了物理化学课程思政的实践原则,分析了实践效果,讨论了实践过程中存在的困难以及对应的解决办法。这些研究有利于充分发挥物理化学课程的育德育人功能,有利于培养学生的唯物主义历史观、爱国主义情操、正确的价值观及社会责任感,为农业大学化学课程思政教学实践提供一些参考和借鉴。

关键词： Liquid films  

摘要： It has been experimentally revealed that a quasi-liquid film that exists on the surface of dispersed ice particles and exhibits dissolving properties disappears after a long-term exposure of samples at a temperature close to -40 degrees C and arises again at -2, -5, and -10 degrees C. The energy of the film formation has been determined. The high value of this energy (approximately 210 kJ/mol) indicates a significant inertia of the film "revival" process. This should be taken into account when designing and carrying out experimental studies of water-containing systems at negative temperatures.

关键词： Arid   Airborne dust   Clay   Entrapment   Sand dunes   Stabilization  

摘要： Sand dune hills were stabilized by petroleum mulch and biological methods in southwest Iran. The present study aims to identify the effects of these landscapes on airborne dust entrapment in five regions, including uphill (UH), downhill (DH), and canopy tree positions after 54 years. These locations were at different distances from dust sources and prevailing winds. The results revealed that salinity in the study areas showed the following trend: canopy > UH > DH. Silt particles were entrapped in the corner 4 times greater than the inner areas. Moreover, silt deposition flux ranged from 54 gm(-2) yr(-1) (the minimum) in the inner site (Al-Baji) to 207.4 g m(-2) yr(-1) (the maximum) in the corner site (SG). Unlike silt, clay flux was maximal in both inner (124.4) and corner (123.4) locations due to the movement of fine materials in high elevations. The total deposition of materials (silt + clay) was maximal (330.8) and minimal (155.6 gm(-2) yr(-1)) in the corner and inner sites, respectively. The clay mineralogy indicated that these hills had two groups of minerals. Primary minerals, i.e. carbonates and silicates, were inherited from parent materials. Secondary minerals were identified in surface soil, and peaks in the subsurface were very weak. Wind sediments added these clays to the surfaces. The abundance of these clays showed the following trend: palygorskite > smectite > vermiculite. It was found that these areas do not disturb the atmosphere by dust and play an important role in air purification because the surface roughness of these hills was promoted by artificially planted trees.

关键词： Liposome   Gum Arabic   Sodium alginate   Curcumin   Physical stability  

摘要： Natural biopolymers such as food gums can be effective in improving the physical stability of colloidal particle dispersions. To improve the loading stability of curcumin in liposomes, liposomes with gum arabic (GA) or sodium alginate (SA) (0-2% w/v) were prepared and their physicochemical properties evaluated. Results showed that GA, which has a high surface activity, interacted more with the liposome surface resulting in smaller liposome size and polydispersity. However GA disrupted the internal lamellar structure of the liposomes at low concentrations, resulting in increased flocculation and was associated with poor retention of encapsulated curcumin. In contrast, SA formed a viscious continuous phase due to the gum network which reduced particle mobility and sedimentation, and increased curcumin retention, although this was associated with an increase in particle size and polydispersity index.

关键词： Sliced beef product   Gaseous ozonation   Oxidizing agent   Food safety   Listeria monocytogenes  

摘要： The treatment of beef with gaseous ozone (GO) was analyzed and the physicochemical characteristics (texture, lipid oxidation, surface color) and food safety (microbial growth of heterotrophic microflora and inoculated Listeria monocytogenes) were evaluated. Transient changes in ozone concentration within the chamber were mathematically modeled using a non stationary mass balance. Ozone pulses were applied and treatment intensities were evaluated in each case. GO treatment prolonged refrigerated storage of vacuum packed beef. Long periods of exposure to ozone (>10 min) negatively affected the red color and oxidative rancidity. The most effective treatments to control microbial flora were ozone pulses ranging between 5 and 10 min duration every 30 min for 5 h using 280 mg O-3 m(-3);these treatments allowed the reduction of more than 1 logarithmic cycle the counts of the natural flora in beef (lactic acid bacteria, mesophilic and enterobacteriaceae), maintaining oxidative stability and adequate physicochemical parameters. Additionally these low doses of GO decreased the counts of inoculated L. monocytogenes (10(2) CFU g tissue(-1)) to values below the detection limit for 16 days at 4 degrees C limiting its growth during refrigerated storage. The use of GO in beef products allows the control of microbial growth during refrigerated storage maintaining high quality parameters.

关键词： 3D printing   Particle size distribution   Carotenoids   Rheological property  

摘要： Carotenoids have many biological properties and their release from the matrix is most essential for human absorption. Particle size reduction of the matrix can lead to cell wall rupture, which promotes the release of carotenoids. However, changes of rheological property caused by particle size reduction are an important factor affecting 3D printing characteristics. The purpose of this study was to investigate the effect of particle size distribution on the carotenoids release, physicochemical properties and 3D printing characteristics of carrot pulp. The results showed that with the decrease of particle size, contents and release rates of carotenoids showed a trend of increase. Particle size reduction of carrot pulp increased apparent viscosity, G', G '', tan delta, 3D printing stability, cohesiveness and gumminess. Moreover, carrot pulp with smaller particle size showed higher printing performance, more uniform pore size distribution and more order microstructures. The study demonstrated that carotenoids release, physicochemical qualities and printing characteristics changed with different particle size distribution, and samples could be separated according to hierarchical clustering analysis of the index.

关键词： Dabaiyang tellurium-gold deposit   North China Craton   Ore-forming fluid   Physicochemical conditions   Mineral deposition mechanism  

摘要： The Dabaiyang deposit is a typical Te-Au deposit hosted in Archean metamorphic rock in the Zhangjiakou district, northern margin of the North China Craton. It is located close to the famous Dongping Te-Au deposit;however, few researches have performed on the Archean metamorphic rock hosted Te-Au deposits, which precludes the studies on enrichment processes and mechanisms of Te-Au deposits in the Zhangjiakou district. In this contribution, four mineralization stages have been recognized in the Dabaiyang deposit: (1) K-feldspar-quartz veins;(2) quartz-pyrite veins;(3) polymetallic sulfide-quartz veins;and (4) calcite and quartz veins. Metallic minerals in this deposit include pyrite, chalcopyrite, galena, sphalerite, bornite, altaite, hessite, petzite, tetradymite, tellurobismuthite, native gold and electrum, and most of them were precipitated in stage III. Petrography, fluid inclusion microthermometry, and laser Raman spectroscopy revealed that the ore-forming fluid was a medium temperature H2O-NaCl hydrothermal system. Fluid temperatures evolved from 264-337 degrees C to 233-323 degrees C to 209-268 degrees C to 130-245.C, and salinities varied from 1.2 to 10.3 wt% to 1.2-8.8 wt% to 4.3-10.5 wt% to 3.8-8.3 wt% NaCl equivalent. Ore-forming fluids yield H and O isotope compositions of 2.4% to 4.9% and 101.2% to 75.5%, respectively, and 3He/4He and 40Ar/36Ar ratios of 1.31-1.58 and 3489.0-21824.1, respectively. The hydrothermal fluids were derived initially from magmatic water (stage I), but more mixture of magmatic and meteoric water or heated meteoric water was added to the system (stages II and III), and significant water-rock exchange with the Sanggan metamorphic rock happened during evolution. Calculated physicochemical conditions of ore mineral formation shows that pH decreased, logfO(2) and logfS(2) did not change significantly from the early to the late stage;logfTe(2) and log alpha Au+(aq)/alpha Ag+( aq) values of stage III are 10.7 to 9.8 and 6.8, respectivel