Stability constants and complexation capacities of complexes formed between heavy metals and extracellular polymers from activated sludge

Conditional stability constants and complexation capacities of extracellular polymers extracted from activated sludge with copper, nickel, cadmium and cobalt have been determined at high and low free metal concentrations using gel complexometry. The results compare favourably with those for other bacterial extracellular polymers, but less well with those for competing metal-binding ligands present in sewage. The affinity of extracellular polymers for metals has been discussed in terms of their contribution to metal removal during the biological phase of wastewater treatment.     

西安地区用静力触探预估钻孔灌注桩极限承载力的研究

根据西安地区某些工程中的钻孔灌注桩试桩资料以及勘察报告,分析了由静力触探法预估钻孔灌注桩极限承载力标准值时应考虑的因素,通过对该地区的分析,建立由静力触探法预估钻孔灌注桩的竖向极限承载力标准值的经验公式。工程验证结果表明,计算值与实测值比较吻合。     

An Experimental Investigation into the Feed Rate Capacity of Rotary Valve and Blow Tank Feeders

Industry widely uses rotary valves and blow tanks for the pneumatic conveying of products, each having their pros and cons depending on the specific application. This article shows the differing results obtained when low-velocity conveying a product through a common pipeline using both a drop-through rotary valve and a bottom-discharge blow tank feeder. A number of issues arise in the rotary valve system, the main one being rotary valve air leakage. A blow tank system, on the other hand, does not leak, as it is an enclosed system. The experimental results show dramatic differences in product throughput. Further exploration leads to a novel modification being made to the rotary valve system in an attempt to increase its capacity. The result of this modification shows a slight increase in output tonnage, but still significantly less than that obtained from the blow tank.     

Antioxidant capacities of α-tocopherol,trolox, ascorbic acid,and ascorbyl palmitate in riboflavin photosensitized oil-in-water emulsions

Antioxidant capacities of α-tocopherol, trolox, ascorbic acid, and ascorbyl palmitate at 0.01, 0.1, and 1.0 mM in riboflavin photosensitized oil-in-water (O/W) emulsions were determined using headspace oxygen depletion, lipid hydroperoxide, and headspace volatile analyses. After 32 h visible light irradiation, headspace oxygen in O/W emulsions without adding antioxidants, with 1.0 mM α-tocopherol, trolox, ascorbic acid, and ascorbyl palmitate decreased to 18.50%, 18.85%, 16.01%, 17.92%, and 19.88%, respectively, whereas those samples in the dark were 20.74%. Trolox and ascorbic acid acted as prooxidants while their lipophilic counterparts, α-tocopherol and ascorbyl palmitate, respectively showed antioxidant properties. Similar antioxidative or prooxidative properties of the tested compounds can be observed in the results of lipid hydroperoxides and headspace volatiles. However, the prooxidant and antioxidant properties of the tested compounds were not clearly shown at 0.01 and 0.1 mM concentration. Both the type and concentration of antioxidants influenced the antioxidant capacities in riboflavin photosensitized O/W emulsions.     

酪蛋白磷酸肽的质量评价方法研究

对来自8种不同公司的酪蛋白磷酸肽(CPP)产品的含量、体外结合钙离子的能力(即持钙能力)用不同的测定方法进行了测定和比较,采用氮磷比(N/P)、钡乙醇沉淀法测定样品含量,用pH滴定法和钙离子选择电极法测定了8种样品的体外持钙能力。研究结果表明:当酪蛋白磷酸肽含量较低时选用N/P和钡乙醇沉淀法测定结果偏差较大,应选用高效液相色谱法(HPLC);pH滴定法和钙离子选择电极法两种方法都能在一定程度上反映样品体外持钙能力的大小,但用pH滴定法测定的结果更符合产品含量的测定结果。本文为CPP开发过程中的质量评价提供了一定的依据。     

不同结构单螺杆屏障混炼元件混合特性研究

运用有限元分析软件Polyflow对不同结构和不同螺杆转速下的修正Maddock混炼元件流场进行三维非等温数值模拟,得到了流场的压力、速度、温度和剪切速率的分布;利用粒子示踪法(PTA)对不同结构和不同螺杆转速的修正Maddock混炼元件流场内聚合物熔体所经历的混合过程进行模拟,并对结果进行了统计学分析;通过比较平均解聚功等参数对不同结构和不同螺杆转速下修正Maddock混炼元件的分散混合效果进行分析研究,并借助实验进行验证。结果表明,等腰反向型修正Maddock混炼元件对聚合物熔体的剪切作用和分散混合性能最好;适当提高螺杆转速可以有效地促进物料的分散混合。     

Evaluation of various additives on the preparation of rice husk ash (RHA)/CaO-based sorbent for flue gas desulfurization (FGD) at low temperature

This paper examines the effectiveness of 10 additives toward improving SO2 sorption capacities (SSC) of rice husk ash (RHA)/lime (CaO) sorbent. The additives examined are NaOH, CaCl2, LiCl, NaHCO3, NaBr, BaCl2, KOH, K2HPO4, FeCl3 and MgCl2. Most of the additives tested increased the SSC of RHA/CaO sorbent, whereby NaOH gave highest SSC (30mg SO2/g sorbent) at optimum concentration (0.25mol/l) compared to other additives examined. The SSC of RHA/CaO sorbent prepared with NaOH addition was also increases from 17.2 to 39.5mg SO2/g sorbent as the water vapor increases from 0% RH to 80% RH. This is probably due to the fact that most of additives tested act as deliquescent material, and its existence increases the amount of water collected on the surface of the sorbent, which played an important role in the reaction between the dry-type sorbent and SO2. Although most of the additives were shown to have positive effect on the SSC of the RHA/CaO sorbent, some were found to have negative or insignificant effect. Thus, this study demonstrates that proper selection of additives can improve the SSC of RHA/CaO sorbent significantly.     

Electrochemical properties of the Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3 alloy mixed with Ni powder

Composites of Mm_0.3Ml_0.7Ni_3.55Co_0.75Mn_0.4Al_0.3 alloy and Ni powders were mechanically synthesized and electrochemically tested in 6 M KOH electrolyte. In this work, the electrochemical properties of the alloys were greatly improved by mixing them with Ni, which plays a corrosion-resistance role in the alkali electrolyte and helps electron conduction. It has been shown that the numbers of activation cycles decreased compared with the alloys without Ni powder. All the alloys were activated after the second cycle. Improvements of the maximum discharge capacities were also found in this work. A maximum discharge capacity of 358 mAh g⁻¹ was measured in the Mm_0.3Ml_0.7Ni_3.55Co_0.75Mn_0.4Al_0.3 + 250 wt.% Ni composite. In addition to that, adding Ni was found to enhance the high-rate discharge ability of the alloys, which appear to be good candidates for the realization of MH battery electrodes.     

改性钛酸锂复合材料作为高倍率锂离子电池负极材料研究

使用简单的水解反应和低温热处理过程所制备的Li_4Ti_5O_(12)/C复合材料具有良好的倍率性能。在水解过程中引入表面活性剂溴化十六烷基三甲铵(CTAB),能够明显地改善锂离子电池负极材料Li_4Ti_5O_(12)/C的倍率性能。在0.5,1,2,5,10C的倍率条件下,电极材料的比容量分别达到162,154,121,80,60 m Ah/g。明显高于使用物理混合方法所制备的Li_4Ti_5O_(12)/C复合材料。同时使用CTAB所制备的Li_4Ti_5O_(12)/C复合材料,在高倍率条件下,还显示出了非常良好的循环稳定性,因为其拥有快速的Li+迁移速率(8.97×10-13cm2/s),较小的传荷电阻(Rct)35.2Ω和较小的体积电阻(Rs)6.8Ω。该方法具有实际的应用价值。