微生物固定化修复技术在氮污染地表水中的应用

地表水中氮污染日益严重,由于氮污染地表水的特殊性,常规修复方法难以发挥高效作用。鉴于微生物固定化修复技术的诸多优点以及在含氮废水中的应用,本文阐述了微生物固定化技术修复氮污染地表水的可行性,并探讨了该技术需要解决的问题及发展趋势。     

竖井SVE修复有机污染土壤的数值模拟分析

采用Galerkin三角形有限单元法对复合地表边界的竖井土壤气相抽提（SVE）稳态流动问题进行了数值模拟分析，模拟结果显示：气相压力沿径向梯度迅速下降，抽提流量与土壤通透系数及真空度呈现高度相关的正比例关系，且地表隔绝覆盖层对流场影响很大.通过与野外实测真空度数据的对比验证，表明该二维轴径向流动模型能较好应用于现场条件，明显优于一维模型.再采用一个稳定的交替方向有限差分（ADI）解出传质微分方程，从而实现多维情况下竖井SVE修复的完整模拟过程.4组不同条件下为期60d的SVE修复过程的计算机模拟显示，土壤通透系数是决定修复效果的关键因素.在流场及传质方面建立的数值模拟分析对SVE的工程设计及预测可提供初步指导.     

一种瓷器修复用新型仿釉基料的耐黄变性能分析

目前,耐黄变性能是评价仿釉基料性能的最关键参数,直接关系到瓷器类文物修复后的保存时效。近几年市场上出现一种名为“瓷器修复专用仿制釉”的进口材料,因其透明度高、固化快、釉质感强,已逐渐被瓷器修复工作者接纳,但目前未见主成分分析与耐黄变性能研究,无法确定其最佳使用范围。基于此,对该仿釉基料展开微观形貌及主成分分析,同时选择瓷器类文物修复中较常用的星皇漆（羟基丙烯酸共聚物）、紫荆花漆（硝基清漆）,在不同人工加速老化条件下,通过对色差值ΔE的分析,对比研究该仿釉基料的耐黄变性能。结果表明：相较于常用的仿釉基料,该仿釉基料表现出较好的耐黄变性能,适用于修复后的瓷器类文物在博物馆内陈列展览。     

膨润土在环境污染治理方面的研究进展

综述了国内外有关膨润土在环境污染治理方面的研究进展，膨润土及其改性产物（活化膨润土，有机膨胀润土，交联膨润土，有机交联膨润土）由于具有良好的吸附性能，在环境污染治理方面得到了越来越广泛的应用。在对含有机污染物，重金属的废水处理中，膨润土是一种高效吸附剂，欧美国家在土壤和地下水污染的防止和修复方面取得了较大的进展，近年来，有关膨润土用于放射性废物处置的理论研究活跃。     

高锰酸盐复合药剂强化混凝处理高有机物含量的地表水

用高锰酸盐复合药剂强化混凝处理,对受高浓度有机物放心水污染的地表水进行了试验研究,结果表明,仅用硫酸亚铁氯化法混凝处理时,原水CODMn浓度增加使混凝效果变差,混凝曲线的最佳药量范围变窄,处理后水质难以达到要求,高锰酸盐复合药剂有显著强化混凝效能,其强化混凝效果与投加方式有关,高锰酸盐复合药 硫酸亚铁混凝剂之后投加的混凝效果最好,投加主锰酸盐复合经剂强化处理使混凝曲线向下移动且向两极张开,拓宽了最佳混凝剂投量范围,提高了系统了抗干扰或抗冲击性,高锰酸盐复合药剂最佳投量与原水CODMn之间符合双矩形双曲线方程y=4\854x/(25.527 x).     

固定化脱氮菌在低污染水处理中的应用研究

随着水体氮素污染日趋严重,脱氮技术的改进及强化方法成为研究热点。固定化微生物技术因具有微生物密度大、处理效率高、反应速度快、适应能力强等优点而备受关注。综述了不同固定化载体及方法对生物脱氮的强化效果,分析了固定化作用对微生物的影响,总结了固定化技术脱氮应用的最新研究进展,并对该领域今后的发展进行探讨。     

Production of optically pure L-alanine by immobilized Pseudomonas sp. BA2 cells

The conditions for immobilizing the new L -aminoacylase-producing bacterial strain, Pseudomonas sp. BA2, by entrapment in κ-carrageenan gel, were investigated. The optimal gel concentration and cell load were determined. The addition of CoCl₂ and N-acetyl-L -alanine to the immobilizing matrix enhanced L -aminoacylase activity. The enzymatic properties of immobilized Pseudomonas sp. BA2 were investigated. Enzyme activity in immobilized cells was optimal at a pH of 6·5 using 0·15 mol dm⁻³ Tris–maleate buffer at 45°C. The presence of 0·7 mmol dm⁻³ CoCl₂ in the enzymatic reaction mixture improved L -aminoacylase activity. The immobilized cell preparation was used for the production of L -alanine from N-acetyl-DL -alanine in a batch reactor. Conversions of 100% were obtained using substrate concentrations ranging from 20 to 200 mmol dm⁻³. The reactor production was 0·74 mol h⁻¹ g cell⁻¹ dm⁻³ which is noticeably higher than that previously reported in the literature. © 1998 Society of Chemical Industry     

Optimization of pullulan production using Ca‐alginate‐immobilized Aureobasidium pullulans by response surface methodology

BACKGROUND: The production of pullulan from synthetic medium by Aureobasidium pullulans P56 immobilized in Ca‐alginate beads was investigated using batch and repeated batch fermentation systems. RESULTS: The highest pullulan concentration (19.52 ± 0.37 g dm^?3) was obtained with 2.0‐2.4 mm beads prepared from 2% sodium alginate solution. Pullulan production was mainly accomplished by immobilized fungal cells since leaked cells in the fermentation medium comprised 17.4% of the total fungal population at the end of fermentation. The pullulan proportion was 84.5% of the total polysaccharide in the fermentation medium. Response surface methodology was used to investigate the effects of three fermentation parameters (initial pH, agitation speed and incubation time) on the concentration of pullulan. Results of the statistical analysis showed that the fit of the model was good in all cases. The maximum pullulan concentration of 21.07 ± 0.48 g dm^?3 was obtained at the optimum concentrations of process variables (pH 7.31, agitation speed 191.5 rpm, incubation time 101.2 h). The gel beads produced pullulan under the optimized conditions for six consecutive batch fermentations without marked activity loss and deformation. CONCLUSION: The results of this study suggest that the immobilization of A. pullulans cells in Ca‐alginate gel beads is suitable for batch and repeated batch production of pullulan. Copyright © 2007 Society of Chemical Industry     

The role of surface tension on the residual water content of fabrics

Cotton has been shown to hold up to 80% of its initial weight in water due to strong capillary forces after washing. According to the LaPlace equation for capillary rise, the rise is proportional to the surface tension of the air-liquid interface. The use of a tailored rinse additive has the potential to alter the surface tension of solutions significantly, thus leading to a lower capillary rise. This lower rise can be related to the residual water content in fabrics. The reduction of surface tension lowers the force required to displace liquid inside the capillaries formed by fabric fibers. If the amount of residual water in fabrics can be significantly lowered, the drying time of the fabrics would be decreased as well. We have shown that by reducing the surface tension of solutions, the residual moisture content of fabrics also decreases.     

金属表面处理工艺水洗过程研究

水洗是金属表面处理工艺中不可缺少的组成部分,其过程质量好坏直接影响到产品的表面质量。本文主要对金属表面处理工艺中水洗过程的质量要求、水洗方法、水洗水的循环再利用等进行了研究,并例举了一些应用实例,希望对金属表面处理工艺用水及供排水管理有一定的参考价值。     

A surface acoustic wave sensor study of polyimide thin film surface treatments - effect on water uptake

The effects of surface treatments on the water uptake in thin (1 μm) polyimide (PI) films were studied using a surface acoustic wave (SAW) sensor, X-ray photoelectron spectroscopy (XPS), external reflectance infrared (ERIR) spectroscopy, and contact angle measurements. Surface modification of PI films can affect film properties such as water uptake and adhesion. These properties, in turn, affect the performance and reliability of the devices in which these films are used. The ability to nondestructively study the results of various surface modification techniques in situ, prior to deposition of a metal layer for example, would be of particular benefit in the fabrication process. The results of this work indicate that the SAW sensor can measure extremely small amounts (< 0.003 μg) of water uptake in thin (1.2 μm) PI films. Also, that the water uptake of PI films, as measured by the SAW sensor, is particularly sensitive to sputter cleaning, sputtering/ KOH, and Teflon AF surface treatment. The SAW, XPS, ERIR, and contact angle studies of the Teflon AF treated PI indicate that the concentration of Teflon AF is very high in the surface region of the PI and decreases into the bulk of the film. This work suggests utility of the SAW sensor as a nondestructive and in situ method for monitoring the surface properties of thin polymers in process control applications.     

固定化假丝酵母99-125脂肪酶催化酯化脂肪酸低碳醇酯反应条件的研究

以硅藻土和纺织品为载体 ,采用吸附法制备固定化脂肪酶 ,研究了固定化假丝酵母 99 1 2 5脂肪酶在有机溶剂中催化脂肪酸低碳醇酯酯化合成过程中 ,有机溶剂性质、脂肪酸与低碳醇的结构、pH值、反应温度和体系含水量、低碳醇的抑制作用等因素对酯化过程的影响。试验结果表明 :底物低碳醇需要采用流加方式加入体系 ,石油醚是最适宜的有机溶剂 ,脂肪酸与醇的碳链越长 ,越易于酯化 ;固定化脂肪酶对直链醇的选择性优于支链醇。以石油醚为有机溶剂 ,在反应温度为 40℃、pH值为 7时 ,硬脂酸与甲醇的酯化率达 95 % ;反应后期应除去体系中的水以避免酶失活。固定化酶间歇催化油酸与甲醇的酯化时 ,重复使用 1 5次 (每次 2 4h) ,其操作半衰期约为 360h。