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关键词： Pyroxene   Carbonation   Fracturing   Fracture mechanics   Zeolite   Augite   Diopside  

摘要： The weathering of primary silicates, and their carbonation in particular, is key for the geochemical cycling of elements, strongly affecting the C cycle and the long-term regulation of the Earth's climate. The knowledge on the controlling factors and mechanisms of aqueous carbonation of primary silicates is however still far from complete. This precludes a better understanding of their chemical weathering in nature and is a strong handicap to implement effective Carbon Capture and Storage (CCS) strategies. Here, dissolution-carbonation reactions of two abundant Ca-Mg pyroxenes, augite and diopside, have been investigated in experiments conducted at hydrothermal conditions, in the presence/absence of different carbonate sources (NaHCO3 and Na2CO3). We show that the main reaction products are low-magnesium calcite and amorphous silica. A higher conversion of augite (similar to 38 wt%) than diopside (similar to 15 wt%) was achieved. The presence of abundant Fe and Al (and minor Na) in the former pyroxene strongly enhances the release of cations to the solution, and contributes to the formation of abundant secondary crystalline and amorphous silicates as well as carbonates (Na-phillipsite and magnesium silicate hydrate, MSH, as well as calcite). In particular, Na-phillipsite nucleates in etch pits exerting a crystallization pressure similar to 100 MPa exceeding the tensile strength of augite (i.e, failure under tension due to breaking of inter-atomic bonds as well as opening and propagation of subcritical fractures or flaws) and causing extensive fracturing. This takes place via an interface-coupled dissolutionprecipitation mechanism, despite the bulk system being undersaturated with respect to this phase. Limited reactioninduced fracturing was also observed following MSH precipitation within diopside crystals. Reaction-induced fracturing increases exposed reactive surface area and creates channels for solution flow, thereby contributing to the progress of the reaction

关键词： 自学能力   教学方式   微课  

摘要： 自学能力是一个人在成长及社会中生存必须具备的能力,也是衡量一个大学生从学校走向社会后有无发展潜力的重要标准,大学生自学能力的培养越来越受重视。文章在重视学生自主学习能力理念的基础上,对物理化学以及物理化学实验课程的教学方式进行了尝试改进,并取得了一定的效果,希望能为师范院校的教学改革提供有益参考。

关键词： Ether-PFAS   ADONA   EEA-NH4   GENX   HFPO-DA  

摘要： Perfluoropolyethers, also known as ether-PFAS, are linear or branched alkyl ether polymers, where the substituent hydrogens on the carbon atoms in the chain have been fully replaced by fluorine atoms. Some of these molecules may have a carboxylate functional group attached to one of the terminal carbon atoms to form an ether-PFAS carboxylate. Perfluoropolyethers are used as processing aids in the manufacture of various types of perfluorinated polymeric materials which are used in a variety of consumer applications. Although the physicochemical and toxicological properties of certain perfluoropolyether compounds have been extensively studied, data are relatively sparse for some members of this class of compounds. Moreover, the physicochemical, toxicokinetic, and toxicological properties of ether-PFAS as a class have not been elucidated in previous comprehensive review articles. This article reviews the nomenclature and uses of ether-PFAS and compares the physicochemical properties, toxicokinetic characteristics, apical effects in toxicological studies, and doseresponse profiles across four specific ether-PFAS compounds. This comparison, including a description of identified data gaps should help to inform the design of studies to further elucidate the characteristics of etherPFAS and to propose potential read-across assessment strategies for members of this class.

关键词： 线上教学   实验教学   教学模式   混合式教学   化学实验  

摘要： 当突发性事件导致不能正常进行线下教学时,为保证"停课不停教、停课不停学",各高校积极开展线上教学工作,各种类型的课程教学纷纷转战网络平台。鉴于实验类课程与理论课程的不同性,本文以《物理化学实验》线上教学为例,对实验类课程线上教学模式进行思考和分析,提出线上教学的优缺点,并对存在的问题提出改进措施,以期提高实验教学效果,为线上实验教学模式的改革和发展提供参考。

关键词： Gelatinization   Molecular weight   X-ray diffraction  

摘要： This study aimed to determine and correlate the physicochemical, thermal, pasting, digestibility and molecular characteristics of native starches, such as mashua (Tropaeolum tuberosum R. and P.), oca (Oxalis tuberosa Mol.), and olluco (Ullucus tuberosus C.), which were extracted via successive washing and sedimentation. The morphology of native starches was determined by scanning electron microscopy, granule size distribution, thermal properties, pasting properties, X-ray diffraction (XRD), amylopectin chain-length distribution and amylose and amylopectin molecular weights. Mashua starch was smaller in size than oca and olluco starches. Moreover, the granules of mashua starch were round in shape, whereas those of oca and olluco starches were ellipsoidal in shape. The B XRD spectra showed similar profiles for the three Andean tuber starches. Mashua and olluco starches exhibited the lowest gelatinization temperatures and enthalpy values, and olluco amylopectin exhibited a longer chain length than mashua and oca starches. The resistant starch of gelatinized and ungelatinized samples exhibited a positive and strong correlation with the molecular properties of amylose and amylopectin, gelatinization enthalpy and molecular order. (c) 2021 Elsevier B.V. All rights reserved.

关键词： Amylopectin   Fine structure   Potato starch  

摘要： The aim of this study was to explore the relationship between the structural and functional properties of starch isolated from Atlantic potatoes at different stages of growth without the effect of varieties and growth environment. The molecular size and chain-length distribution of amylopectin significantly varied with growth. The M-w and M-n of amylopectin ranged from 2.976 x 10(7) to 4.512 x 10(7) g/mol and 1.275 x 10(7) to 2.295 x 10(7) g/mol, respectively, suggested that the polydispersity varied with growth. The average chain length of amylopectin during potato growth showed small but significant changes and ranged from DP 23.59 to 24.73. Overall, A(fp) chains, A(crystal) chains, and B1 chains increased with growth, and B2 and B3 chains decreased with growth. There was wide variation in starch pasting, gelatinization, retrogradation, in vitro starch digestibility, swelling power, solubility, and gel stability properties. Specifically, potato starch harvested at the earliest time had the highest resistant starch content. The variation trend of swelling power and solubility was similar, reached highest value at 42 days, were 20.38 g/g and 8.83%, respectively. Correlation analysis revealed that the physicochemical properties were significantly affected by amylopectin fine structure. The results of this study enhance our understanding of the structure-function relationship of potato starch. (C) 2021 Elsevier B.V. All rights reserved.

关键词： 问题诱导   互动教学   人才培养  

摘要： 课堂教学是教学工作的重要组成部分,也是提高教学质量、促进教育改革和发展的重要因素;课堂教学模式和实施策略直接影响到其教学质量的优劣。物理化学是化工类专业基础理论课,为了克服传统教学方法的不足,激发学生对自然的兴趣,发挥教师与学生互动优势,本文开展了"问题诱导"的教学方式和研讨互动教学方法初探,提高学生对物理化学基础理论的兴趣,并激发学生的创新求实精神,在实践中取得了良好的教学效果。

关键词： Simonkolleite   Breast cancer   Cytotoxicity   Nanocomposite   Zinc oxide   Synergism  

摘要： Zinc Oxide (ZnO) and simonkolleite (SM) have been extensively studied separately in several technological applications. However, the cytotoxicity of SM has not yet been investigated, nor has the synergism between SM and ZnO. In this work, we investigated both the synergism of SM with ZnO in the physico-chemical properties and cytotoxicity in breast cancer cells. The physical characterization confirmed that with the increase of the annealing temperature, the transformation of SM into ZnO occurs and further investigated how photocatalytic performance and cytotoxicity were changed. The photocatalytic performance of ZnO was the highest (80%) in contrast to SM and the SM/ZnO nanocomposite (NCT), had no photocatalytic activity. Cytotoxicity was investigated using the MCF-10A, MCF-7, and MDA-MB-231 tumor cell lines. SM resulted in a high incidence of cell death at a high concentration and induced the production of reactive oxygen species at a low concentration. ZnO and NCT were observed to have the expected effect regarding cytotoxicity, and the induction of reactive oxygen species was much higher than with SM. The biological ROS results were in excellent agreement with the photocatalytic performance, demonstrating that the mechanism of the antitumor effect of SM does not occur predominantly via ROS. Therefore, in this work, we demonstrate how the physico-chemical and biological properties are changed due to the synergism of SM and ZnO.

关键词： Emulsion gelatin-based gel   Rheological property   Thermogravimetric analysis  

摘要： The current work aimed to prepare emulsion gels based on European eel skin gelatin (ESG). The results revealed that the ESG exhibited interesting antioxidant and functional properties in a dose-dependent manner. The ESG has a gel strength of 354.86 g and high gelling and melting temperatures of about 33 and 43 degrees C, respectively. Hence, based on its interesting gelling ability, the ESG-based gel was employed to stabilize European eel oil (EO) emulsions. In this context, two emulsions were prepared by homogenization or homogenization followed by sonication at EO:ESG weight ratios of 1:2 and 1:4. The physicochemical, textural, structural and thermal properties of emulsion gelatin-based gels (EGGs) were evaluated. The EGGs had a rigid and a cohesive gel network, according to the textural and microstructural analysis. Structural and thermogravimetric analyses showed the effective entrapment of EO in the ESG gel network. (c) 2021 Elsevier B.V. All rights reserved.