碱性体系下修饰纤维素酶米氏常数的测定

用四种修饰纤维素酶Cell-MAL(5,10,20 K)和Cell-SPA 5 K和天然纤维素酶在p H=13.63,T=45℃反应时间为1 h的7%(wt)Na OH/12%(wt)尿素溶液中降解羧甲基纤维素。得到四种修饰纤维素酶的活性均比天然纤维素酶的活性高。其中Cell-MAL 5 K的活性最高。然后浓度分别为1/100、1/300、1/500和1/700的7%(wt)Na OH/12%(wt)尿素水溶液中分别测定了天然纤维素酶和四种修饰纤维素酶的米氏常数分别为2.853、1.735、1.777、4.622和10.01 mg/L。     

芬顿+改良活性炭深度处理垃圾渗滤液的应用

主要研究了芬顿+改良活性炭深度处理垃圾渗滤液在实际工程中的应用。考察了初始运行的处理效果,CODCr、SS、色度均能达标,UV254(反映腐殖酸类物质的量)的去除效果表较明显。对吸附剂的实际吸附能力进行了考察,一级吸附在运行110天时才出现吸附效率明显降低,二级吸附在一级吸附能力下降时可以保证较高的去除率(70%以上)。该工艺深度处理中晚期垃圾渗滤液药剂费和活性炭更换费之和为21.27元/吨水,可以满足渗滤液处理的经济性要求。     

A MODIFIED EFFECTIVE CAPACITANCE METHOD FOR SOLIDIFICATION MODELLING USING LINEAR TETRAHEDRAL FINITE ELEMENTS

In this paper a new formulation for modelling solidification is discussed. The formulation has similar features to both the apparent and effective heat capacitance methods used for solidification problems where conduction predominates over other heat transfer mechanisms. The main feature of the new method is that a modified form of effective heat capacitance is calculated from the solution of non-linear equations that describe the energy loss for linear tetrahedral finite elements. This approach ensures that the predicted temperature field corresponds exactly with the energy loss and so providing an extremely stable formulation. The method is tested against a range of problems including some with non-linear liquid fractions. The predictions are compared against known analytical solutions and the method is shown to provide reasonable accuracy even for relatively large time-steps. A comparison is made between the method and the well-known temporal and spatial approximations of apparent heat capacitance, and effective capacitance. Accuracy is maintained over a greater variation in time-step and mesh density with comparable computational requirements. In addition, the method lends itself to the use of relatively simple bisection techniques for the solution of the non-linear finite element equations. Also demonstrated is the method's innate ability to predict energy loss to a high degree of accuracy for large time steps.     

改性柚子皮降滤失剂的合成与评价研究

天然材料因其易降解、环境友好、来源丰富和价格低廉等优势,成为环保型钻井液处理剂研发的重要方向。在天然柚子皮的基础上,通过化学合成引入酰胺基和磺酸基,形成了一种可满足高温地层绿色、安全、高效钻进的改性柚子皮降滤失剂,并对其抗温性、抑制性和抗盐抗钙性能进行了评价。柚子皮富含植物酚和聚糖等活性成分,改性后的柚子皮抗温能力强,在150 ℃的滤失量降低率超过70%;滚动回收实验结果表明,在加量为0.3%的情况下,其抑制效果优于KCl;抗污染实验表明,改性柚子皮降滤失剂抗盐抗钙效果好,0.3%的加量下,在淡水基浆、盐水基浆、饱和盐水基浆中均能使滤失量保持在10 mL以下,在CaCl₂含量为3%时,滤失量降低率达到82.22%。改性后的柚子皮具有良好的降滤失性能,为环境友好型钻井液处理剂的开发提供了新的技术思路。     

A new approach to the Noack volatility test

This paper reports on the method and preliminary results of a significant modification of the Noack volatility test. This modification permits collection and examination of the volatile products as well as of the residue. The analysis of such volatiles by chromatography and spectroscopy revealed surprising information that is especially relevant in the face of increasingly difficult automotive and heavy duty engine emission limitations. The data also showed very close agreement with the Unified Test Method for the Noack Volatility Test now covered by CEC L-40-T-87. Important to operators, the authors' modified Noack apparatus avoids the use of the toxic Wood's Metal of the earlier Noack apparatus.     

大米淀粉制备及其综合利用研究进展

大米淀粉以其独特物理化学性质广泛用于食品、纺织等行业,该文综述近年来大米淀粉制备及其性质和应用研究概况。     

基于 LoRa 的森林消防协同定位算法

为解决野外火场救援消防员定位安全问题,提出一种基于远距离无线电(LoRa) 技术的森林消防协同定位算法。针对 野外救援存在的非视距(NLOS) 问题,提出一种修正协方差矩阵的扩展卡尔曼滤波协同定位算法,利用LoRa协同网络内部移 动节点之间的测距信息辅助定位,建立系统方程并根据当前时刻的状态滤波值二次更新误差协方差修正偏离误差;其次提出 改进的动态中值滤波算法,采用动态窗口筛选处理定位扰动数据,二次优化定位轨迹曲线。仿真实验结果表明,所提算法极 大地协同了整个网络资源,在室外多NLOS, 通信质量差的环境下定位精度可达0.49 m, 为森林消防安全解救提供了一种可 靠的解决方案。     

Effect of Vacuum and Modified Atmosphere Packaging on the Shelf-life of Liquid-smoked Swordfish (Xiphias gladius) Slices

ABSTRACT: Swordfish fillets, dry-salted and treated with liquid smoke, were sliced and packed in vacuum conditions and under modified atmosphere (MA) (5% O₂,45% CO₂, 50% N₂) and stored at chilled temperature (4°C) to determine the effect of different packaging on shelf-life. Sensory attributes, total volatile basic nitrogen (TVB-N), pH, lipid oxidation by thiobarbituric acid test, and microbiological counts were monitored during 45 d of storage. The TVB-N increased to levels recommended by European regulation at the time of sensory rejection, resulting as the most reliable parameter of quality decay. Lipid oxidation was low and microbial counts could not be correlated with quality decay. Sensory rejection (at least 50% of the assessors scoring =5 in a scale from 1 to 9) was sooner for MA-packed samples (12d) than for vacuum-packed ones (42d).     

改性双马来酰亚胺树脂的固化工艺研究

本文用ＤＳＣ法研究改性双马来酰亚胺树脂的固化动力学参数和固化工艺,固化度和红外光谱确定了后处理工艺。研究所得的固化工艺条件中１４０℃／ｈ、１９０℃／２ｈ,２４０℃／４ｈ能达到完全固化。