等离子体电解氧化技术及机理研究进展

等离子体电解氧化技术(PEO)是一种在轻金属表面原位生长陶瓷膜的技术,在材料领域有着广阔的应用前景。本文从PEO技术的作用过程、机理、诊断技术,PEO陶瓷膜性能和影响因素,应用及局限性等方面,概述了PEO技术在国内外的研究进展,并提出了未来的发展方向。     

一种新型轮胎硫化机中心机构工作性能的模拟研究

中心机构是轮胎定型硫化机的重要部件,目前现有轮胎定型硫化机的进水口和出水口平行设置在中心机构的底部,当过热水充满整个胶囊后开始在胶囊里进行循环时,位于中心机构底部位置的过热水不能充分地与顶端的液体进行热量置换就流出胶囊,造成轮胎胎侧上下两端温差较大,整个胶囊内的热交换效率低下,轮胎硫化不均匀。因此,本文提出一种新型轮盼定型硫化机中心机构,并且详细阐述其作用机理,利用FLUENT模拟软件与现有的轮胎定型硫化机中心机构的工作性能进行比较,以更好地说明其能够明显改善轮胎的硫化效果。     

Lead desorption from modified spent grain

Lead-loaded modified spent grain regenerated by desorption process was investigated. HCl, H₂SO₄, H₃PO₄, NaOH, NaCl and ultrapure water were chosen as desorption agents to treat lead-loaded modified spent grain for 30 min. The structures and components of regenerated modified spent grain before and after adsorbing Pb(II) were investigated using scanning electron microscopy(SEM), energy-dispersive analysis of X-ray(EDAX) and Fourier transform infrared spectrometry(FTIR). The results indicate that lead-loaded modified spent grain treated in 0.1 mol/L HCl exhibits higher elution efficiency (86.44%) as compared with other agents. The enrichment of carboxyl and hydroxyl groups susceptible to combine with Pb(II) are observed in the regenerated modified spent grain, which may result in high re-absorption efficiency of Pb(II). Moreover, C—Cl, N—H, C—N and O—H (polysaccharides) also play an crucial role in Pb(II) binding to regenerated modified spent grain.     

Influence of pH and ionic strength on Cu(II) biosorption by aerobic granular sludge and biosorption mechanism

BACKGROUND: To elucidate the process and mechanism of Cu(II) biosorption onto aerobic granules, the influence of pH and ionic strength (IS) on the Cu(II) biosorption capacity and biosorption mechanism was studied. RESULTS: The biosorption of Cu(II) onto aerobic granules under different conditions of pH (3, 4 and 5), IS (0, 0.1 and 0.5 mol L^?1) and Cu(II) concentration (25–250 mg L^?1) was investigated. The correlation coefficients of the pseudo‐second‐order kinetic model were , while those of the Langmuir and Freundlich models were and respectively. The biosorption of Cu(II) increased with increasing pH, while the effect of IS on the biosorption was complicated, which could be explained by the competition among different metallic ions, colloidal chemistry theory or Derjaguin, Landau, verwey and Overbeek (DLVO) theory. About 70% of the solid phase Cu(II) was exchanged by Na(I), Ca(II) and Mg(II) released from the aerobic granules at pH 4 and 5. The results revealed that ion exchange is the most important biosorption mechanism but that other mechanisms also play a part. CONCLUSION: The sorption performance can be optimised by adjusting the pH and IS. Aerobic granules can be used as an alternative effective, economical and practical biosorbent for heavy metal removal. Copyright © 2008 Society of Chemical Industry     

A kinetic study on the autoxidation of sunflowerseed oil

Unhydrogenated and hydrogenated sunflowerseed oils were exposed to the autoxidation process by sunlight under atmospheric conditions. Experiments were carried out in equal-sized glass, PET (polyethylene terephthalate) polymer, and metal (covered by tin) containers. The reaction time was 30 d, and the reaction course was observed by determining weight changes and peroxide values (PV) of the oil samples at the same time within 2-d intervals. The logarithm of the PV was plotted against time, and straight lines were obtained from the 4th or 6th d. The autoxidation reaction constants were obtained for each oil in each container. When comparing the reaction constants, the unhydrogenated oils autoxidize easily, and the autoxidation reaction occurs faster in sunlight in glass than in the PET polymer container and much faster than in the darkness of the metal container.     

Formation and characterization of iron oxide nanoparticles loaded on self-organized TiO2 nanotubes

The iron oxide nanoparticles were loaded onto self-organized TiO₂ nanotube layers grown by anodization of Ti in fluoride containing electrolytes. The nanoparticles were obtained by electrodepositing method in glycerol/water/FeCl₃·6H₂O electrolytes at room temperature. The X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) measurements showed that the nanoparticles consisted of iron nanocrystalline (Fe) and magnetite (Fe₃O₄). The hematite (α-Fe₂O₃) structure was obtained by annealing in air at 450 °C. The growth mechanism of the nanoparticles and their morphology were also described. Furthermore, the nanoparticles exhibited good ferromagnetic properties at room temperature.     

稀土稳定剂的应用性能及其作用机理

介绍了稀土稳定剂的应用性能及其热稳定作用机理。     

High-temperature oxidation of titanium carbide in oxygen

The kinetics of titanium carbide oxidation in oxygen over the temperature range of 600–1200°C and oxygen pressure from 0.1 to 740 Torr have been studied with a vacuum microbalance. Layer-by-layer x-ray analysis, petrography, metallography, and gas chromatography have been used to analyze the oxidation products. A paralinear nature of the oxidation of material was established, and the rate constants of the process were calculated for the corresponding parabolic and linear portions of the kinetic curves. It was shown that a gaseous product, CO₂, formed, as well as a solid product, TiO₂ (rutile), both stoichiometric and nonstoichiometric. The lower oxides, Ti₃O₅, Ti₂O₃, TiO, were noted in the scale at temperatures from 700 to 800° and low oxygen pressures, their relative quantity rising with decreasing pressure. Based on x-ray analysis and microhardness measurements, it was concluded that titanium oxicarbides formed in the TiC, directly adjacent to the scale. A possible oxidation mechanism of titanium carbide is proposed.     

进一步扩大高校办学自主权深化学科专业管理体制改革

学科专业结构合理化程度直接关系到高等教育办学质量和办学效益，以往人们在研究学科专业结构时，过多强调了学科专业的布局，各学科专业招生规模比例和资源配置等问题，但对制度层面上如何保证学科专业主动适应经济社会发展需要及高等教育自身发展逻辑要求重视不够。本文着重探讨了建立学科专业自主调节的体制和机制。     

纤维增强水泥基复合材料的研究进展

综述了纤维增强水泥基复合材料(fiber reinforced cementitious composites,FRCC)目前在国内外的研究进展.简要介绍了FRCC的概念及其基本性能,详细介绍了超高性能FRCC的国内外研究进展,重点介绍了FRCC的纤维间距、复合材料以及多重裂缝等理论的研究情况以及FRCC工程应用情况,在此基础上,提出了当前FRCC研究中存在的问题和今后需要进一步研究的方向.