Degradation of 4,6-dinitro-o-cresol from water by anodic oxidation with a boron-doped diamond electrode

Anodic oxidation of 4,6-dinitro-o-cresol (DNOC) has been studied in a cell of 100 ml with a boron-doped diamond anode and a graphite cathode, both of 3-cm² area. Solutions containing up to approximately 240 mg l⁻¹ of compound in the pH range 2.0-12.0 have been treated at 100, 300 and 450 mA between 15 and 50 °C. Total mineralization is always achieved due to the great amount of hydroxyl radical (OH) produced as oxidant on the anode surface. Total organic carbon is more rapidly removed in acid medium, being the optimum pH 3.0. The degradation rate increases when temperature, current and DNOC concentration increase. However, at 100 mA depollution becomes more effective from 71 mg l⁻¹ of initial pollutant. A pseudo first-order kinetics for DNOC decay is always found by reversed-phase chromatography, with a rate constant practically independent of pH, as expected if the same electroactive species is oxidized in all media. Ion-exclusion chromatography allowed the detection of oxalic acid as the ultimate carboxylic acid. The mineralization process leads to the complete release of NO₃⁻ ions from the destruction of nitroderivative intermediates. These products are oxidized simultaneously with accumulated oxalic acid up to the end of electrolyses. Comparative treatment of the same solutions with a Pt anode yields a quite poor depollution because of the generation of much lower amounts of reactive OH on its surface.     

高坝下游水体中溶解气体过饱和问题研究

提出高坝下游水垫塘中总溶解气体(TDG)饱和度的计算与下游河道水体TDG饱和度的计算应采用不同的方法;并利用高速射流实验,及自行设计的产生TDG过饱和的实验装置,进一步分析了高坝下游水体中TDG过饱和的成因,找到了影响大坝下游TDG释放速率的主要因素.指出由于水垫塘中气泡被带入水体深处,使得水体存在溶解度梯度,溶解度沿着水深方向增加,深处水体能溶解更多的气体,在水流的紊动掺混下,高浓度的溶解气体被带入到较浅水深处,造成部分水体TDG过饱和.在没有掺气的条件下,过饱和溶解气体释放速率随着紊动强度的增大而增大,随着水深的增加而减少.     

智能流量定量控制仪的研究

本文论述了作者对流量定量控制仪的研究成果,提出了一种新的定量控制方法－－总脉冲数计数法,它具有极小的控制误差。文中定量分析了进行温度补偿时温度测量的精度要求,还介绍了作者所研制的智能注量控制仪的工作原理。     

锅炉水总碱度监控系统

以高速高性能单片机C8051F020为核心，采用智能复合控制策略，设计并实现了一种对锅炉水总碱度进行间接测量和智能控制的计算机监控系统，改善了传统检测方法的不足，可实现对锅炉水碱度进行在线监测。介绍了碱度检测原理、碱度控制原理、监控系统的硬件电路设计和软件编程，并给出了应用实例。实际使用结果验证了所提出方法的有效性。     

魔芋飞粉蛋白酶解物对酿酒酵母生长的影响

以魔芋飞粉蛋白酶解物为研究对象,利用静态激光光散射测定其分子量后,考察了其对酿酒酵母菌落大小、出芽率、菌体数量及代谢产物影响.实验结果表明添加6218u蛋白酶解物对酿酒酵母生长有明显的促进作用,培养液中还原糖转化率得以提高,乙醇含量明显增大.     

渣油中总硫及硫化物分析测定方法研究进展

渣油中硫化物的存在对石油加工和油品性能产生诸多不利影响。综述了渣油中总硫、硫醚硫和噻吩硫的测定方法及其应用,并对各种方法优缺点进行了分析讨论。对渣油中硫化物组成和结构进行定量和定性分析,将对进一步研究和选择合理的渣油深加工方案提供理论依据和数据支持。     

AGING CHARACTERIZATION OF ADVANCED POLYMER SYSTEMS

Aging of three advanced polymer systems used as adhesives in the aerospace industry is characterized by Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR-FTIR), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS).Since significant changes in mechanical properties were observed for AF191, FM®73, and FM®5 bonded joints, the purpose of this work was to identify whether there is any chemical and physical degradation for the adhesives used in these joints. Each of the adhesives has been evaluated after exposing to Hot/Wet and Hot/Dry environments for 5000 h. They were also thermally cycled in conditions that represent subsonic and supersonic cruise. Hot/wet exposures demonstrated a greater amount of possible degradation than hot/dry or thermally cycled exposures. The hot/wet aging condition resulted in more pronounced O-H, C-H, and N-H infrared absorptions, reduced glass transition temperature of adhesives, and reduced tensile and fracture properties of corresponding bonded systems. Overall, these adhesives were chemically very stable under the environments to which they were exposed, even though some of the joints showed reduced fracture toughness due to the exposure. Additional work is needed to understand the mechanism causing the change in joint properties when exposed to these environments.     

Selective Inhibition of Heparan Sulphate and Not Chondroitin Sulphate Biosynthesis by a Small,Soluble Competitive Inhibitor

The glycosaminoglycan, heparan sulphate (HS), orchestrates many developmental processes. Yet its biological role has not yet fully been elucidated. Small molecule chemical inhibitors can be used to perturb HS function and these compounds provide cheap alternatives to genetic manipulation methods. However, existing chemical inhibition methods for HS also interfere with chondroitin sulphate (CS), complicating data interpretation of HS function. Herein, a simple method for the selective inhibition of HS biosynthesis is described. Using endogenous metabolic sugar pathways, Ac₄GalNAz produces UDP-GlcNAz, which can target HS synthesis. Cell treatment with Ac₄GalNAz resulted in defective chain elongation of the polymer and decreased HS expression. Conversely, no adverse effect on CS production was observed. The inhibition was transient and dose-dependent, affording rescue of HS expression after removal of the unnatural azido sugar. The utility of inhibition is demonstrated in cell culture and in whole organisms, demonstrating that this small molecule can be used as a tool for HS inhibition in biological systems.     

Pilot Studies of Ozonation for Inactivation of Artemia salina Nauplii in Ballast Water

A pilot-plant study was conducted in the Republic of Croatia to determine the applicability of ozonation for inactivation of non-indigenous species and to provide necessary information regarding use of ozone as a ballast water treatment option. Nauplii of the brine shrimp Artemia salina were used as model organisms to investigate the efficacy of ozonation at three different ozone dosages (2.4, 3.7 and 10.9 mg L^?1). Mortality of Artemia nauplii at 98.6%, was achieved after 3 h of exposure in ozone-treated water with the highest ozone dosage. Our results indicated that ozonation is a promising treatment for controlling non-indigenous and potentially invasive species; however, to draw more general conclusions, several species with higher level of resistance to ozone are required and will be studied in the future.     

Folding rate prediction based on neural network model

One of the most important challenges in biology is to understand the relationship between the folded structure of a protein and its primary amino acid sequence. A related and challenging task is to understand the relationship between sequences and folding rates of proteins. Previous studies found that one of contact order (CO), long-range order (LRO), and total contact distance (TCD) has a significant correlation with folding rate of protein. Although the predicted results from TCD can provide better results, the deviation is also large for some proteins. In this paper, we adopt back-propagation neural network to study the relationship between folding rate and protein structure. In our model, the input nodes are CO, LRO, and TCD, and the output node is folding rate. The number of nodes in the hidden layer is seven. Our results show that the relative errors for the predicted results are even lower than other methods in the literature. We also observe a best excellent correlation between the folding rate and contact parameters (including CO, LRO, and TCD), and find that the folding rate depends on CO, LRO and TCD simultaneously. This means that CO, LRO and TCD are similarly important in folding rate of protein. Some comparisons are made with other methods.