浅谈青年教师参与胶体与界面化学教学改革的几点体会

本文分别从加强基础理论教学、理论联系实际、提高综合素质和营造和谐教学氛围四个方面,就青年教师参与胶体与界面化学课教学改革进行了分析,并提出了今后努力的方向。     

Fate and transport of elemental copper (Cu0) nanoparticles through saturated porous media in the presence of organic materials

Column experiments were performed to assess the fate and transport of nanoscale elemental copper (Cu⁰) particles in saturated quartz sands. Both effluent concentrations and retention profiles were measured over a broad range of physicochemical conditions, which included pH, ionic strength, the presence of natural organic matter (humic and fulvic acids) and an organic buffer (Trizma). At neutral pHs, Cu⁰ nanoparticles were positively charged and essentially immobile in porous media. The presence of natural organic matter, trizma buffer, and high pH decreased the attachment efficiency facilitating elemental copper transport through sand columns. Experimental results suggested the presence of both favourable and unfavourable nanoparticle interactions causes significant deviation from classical colloid filtration theory.     

Fullerene nanoparticles exhibit greater retention in freshwater sediment than in model porous media

Increasing production and use of fullerene-based nanomaterials underscore the need to determine their mobility in environmental transport pathways and potential ecological exposures. This study investigated the transport of two fullerenes (i.e., aqu/C₆₀ and water-soluble C₆₀ pyrrolidine tris-acid [C₆₀ PTA]) in columns packed with model porous media (Iota quartz and Ottawa sand) and a sediment from Call’s creek under saturated and unsaturated steady-state flows. The fullerenes had the least retention in Iota quartz, and the greatest retention in the sediment at near neutral pH, correlating with the degree of grain surface chemical heterogeneity (e.g., amorphous Al hydroxides concentration increasing in the order of Iota quartz < Ottawa sand < sediment). Surface roughness was elucidated as another important factor responsible for the greatest fullerene retention in the sediment. In accordance with the XDLVO energy calculations, C₆₀ PTA was less retained than aqu/C₆₀ at near neutral pH, due to its greater hydrophilicity measured by tolune-water partition coefficient, as well as smaller particle sizes revealed by atomic force microscopy. Fullerene retention exhibited a strong dependency on solution pH that could be explained partly by the pH-dependent surface charge of fullerenes and grain surface, and partly by increased hydrophobicity of C₆₀ PTA when solution pH approaches its isoelectric point (IEP). Finally, fullerene retention was enhanced in unsaturated media, implying that fullerenes may be more attenuated in the vadose zone than in groundwater.     

淀粉的老化机理及抗老化研究

对谷物淀粉的理化特性进行了研究,分析了淀粉的老化机理及老化模型.根据淀粉的特性,选用酶制剂、乳化剂和胶体等作为抗老化剂用于谷物食品保鲜,能有效延长食品的货架期.     

CRITERIA FOR SUPERSATURATION IN GAS LIQUID REACTIONS INVOLVING TWO VOLATILE PRODUCTS

Supersaturation criteria has been developed for gas absorption accompanied by chemical reaction resulting in the formation of two volatile products.     

胶体蓄电池电解质及其灌装性能的研究

本文介绍了胶体蓄电池的制作,探讨了当硫酸浓度一定时,硅酸钠浓度与胶凝时间的关系,当硅酸钠浓度一定时,硫酸浓度与胶凝时间的关系。通过反复实验筛选出了性能较好的缓凝剂,使灌装的蓄电池有更好的性能。     

Evaluation of data from the literature on the transport and survival of Escherichia coli and thermotolerant coliforms in aquifers under saturated conditions

Escherichia coli and thermotolerant coliforms are of major importance as indicators of fecal contamination of water. Due to its negative surface charge and relatively low die-off or inactivation rate coefficient, E. coli is able to travel long distances underground and is therefore also a useful indicator of fecal contamination of groundwater. In this review, the major processes known to determine the underground transport of E. coli (attachment, straining and inactivation) are evaluated. The single collector contact efficiency (SCCE), eta0, one of two parameters commonly used to assess the importance of attachment, can be quantified for E. coli using classical colloid filtration theory. The sticking efficiency, alpha, the second parameter frequently used in determining attachment, varies widely (from 0.003 to almost 1) and mainly depends on charge differences between the surface of the collector and E. coli. Straining can be quantified from geometrical considerations; it is proposed to employ a so-called straining correction parameter, alpha(str). Sticking efficiencies determined from field experiments were lower than those determined under laboratory conditions. We hypothesize that this is due to preferential flow mechanisms, E. coli population heterogeneity, and/or the presence of organic and inorganic compounds in wastewater possibly affecting bacterial attachment characteristics. Of equal importance is the inactivation or die-off of E. coli that is affected by factors like type of bacterial strain, temperature, predation, antagonism, light, soil type, pH, toxic substances, and dissolved oxygen. Modeling transport of E. coli can be separated into three steps: (1) attachment rate coefficients and straining rate coefficients can be calculated from Darcy flow velocity fields or pore water flow velocity fields, calculated SCCE fields, realistic sticking efficiency values and straining correction parameters, (2) together with the inactivation rate coefficient, total rate coefficient fields can be generated, and (3) used as input for modeling the transport of E. coli in existing contaminant transport codes. Areas of future research are manifold and include the effects of typical wastewater characteristics, including high concentrations of organic compounds, on the transport of E. coli and thermotolerant coliforms, and the upscaling of experiments to represent typical field conditions, possibly including preferential flow mechanisms and the aspect of population heterogeneity of E. coli.     

AFM characterization of the structure of Au-colloid monolayers and their chemical etching

Modification of a glass support with triethoxy propylaminosilane yields an active interface for the assembly of Au colloids. The colloids are imaged by AFM using a low applied load (0.5–0.7 nN). The lateral Au-colloid dimensions, 33±3 nm, deviate from the particle dimensions determined by TEM (19±2 nm) and absorption spectroscopy (15 nm). This deviation is attributed to the intrinsic curvature of the AFM tip. Application of higher loads on the tip (3 nN) results in the sweeping of Au colloids from the monolayer. The Au colloid monolayer is etched in the presence of CN⁻. The etching proceeds by the initial coincidental etching of Au particles followed by the kinetically favored etching of particles at the edges of the etched domains. This provides means for the micro machining and the chemical manipulation of Au colloids of controlled spatial arrangement.     

磁处理的防垢除垢试验和机理探讨

通过中试研究表明,磁处理能使循环冷却水的水质达标,炭钢A3和炭达96.5%和97.4%.对磁处理防垢除垢的机理进行探讨,认为磁处理防垢除垢的实质是同晶异构现象生成同晶异构体,使碳酸钙生成能量较高的胶体碳酸钙、球霰石和霰石,不易结垢,并通过水溶液传递能量,老垢脱落,并用此机理解释了磁处理的"记忆"效应.     

胶体电解质在铅蓄电池中应用的研究

本文简要的介绍胶体电解质的制作原理及有关特性,当以此作为铅蓄电池的电解质时,电池的工作原理及其优越性。