Development of centrifugal casting high speed steel rolls

The present study aims at developing the high speed steel (HSS) as roll materials to replace the traditional roll materials such as the alloy cast iron and powder metallurgical (PM) hard alloy. The HSS roll billet was formed by centrifugal casting, and the billet was rough machined after soften annealing heat treatment, then it was quenched and tempered to get suitable hardness and toughness. After that the HSS roll was finish machined to the final dimension of φ285 mm in the outer diameter, φ160 mm in the inner diameter and 120 mm in width and its surface hardness was tested. Finally the HSS roll was used in high speed wire rod mill. The test results show that a high and homogeneous hardness can obtain on the work surface of HSS rolls, the surface hardness is 63-65HRC and its variation is smaller than 2HRC. The impact toughness of this kind of HSS is about 16 J/cm2. The results of on-line service investigation in high speed wire rod mill indicate that the HSS rolls have excellent wear resistance, the steel rolling quantity per mm of HSS rolls is 3120 t, the service life-span of HSS rolls is 4 times longer than that of high chromium cast iron rolls and it is close to that of the PM hard alloy rolls. The manufacturing burden of HSS rolls is obviously lower than that of the PM hard alloy rolls, it is only 25% of that of the PM hard alloy rolls.     

Design of process parameters for direct squeeze casting

On the basis of the analysis of solidification interval and temperature distribution of components manufactured by the squeeze casting method, formulas for calculating the solidification interval and compaction pressure were deduced according to the principal request that the compaction pressure should be equal to or greater than the plastic deformation resistance of the forming component when solidification ended. The solidification interval was proven to be associated with many factors, such as weight of the component, specific heat of the alloy, latent heat, pouring temperature, component temperature at the end of solidification and heat-transfer coefficients. The compaction pressure was related to the strain rate, deformation temperature, and dimension of the de- forming component. The solidification interval and compaction pressure calculated by the formulas deduced in this article were adopted in the production of 45 steel bidirectional chapiter valves, and components with excellent oerformance were manufactured.     

All Set and Intelligent Bargaining Control Model

1Introduction Thevigorousdevelopmentofneweconomyaffectstheworld onvariousfieldandE businessisthetypicalresultofthis economywave.Comparedwithtraditionalbusinessmode,newonerealizesnon distancecommunicationofE2Cand E2Emakingfulluseofinternetallovertheworld.Thenon distancecommunicationbringsunlimitedbenefitsto companies.Atthesametimewenoticethatpeopleshould combineE businesswithcomputersciencesufficientlytaking advantageoftherelationshipbetweenthem,inadditionto movingtheoldcommonbusinesstointer…     

The oxidative and adsorptive effectiveness of hydrous manganese dioxide for arsenite removal

This study focuses on the effectiveness of hydrous manganese dioxides (δMnO2) removing arsenite (As(Ⅲ)) from aqueous solution. Effects of such factors as permanganate oxidation, pH, humic acid and Ca2 on As removal and possible mechanisms involved in have been investigated. Permanganate oxidation increases As removal to a certain extent; the higher pH results in the formation of more easily adsorbed As species, contributing to higher As removal; humic acid occupies adsorbing sites and decreases ζ potential of δMnO2, therefore inhibiting As removal; Ca2 facilitates As adsorption on δMnO2, mainly through increasing ζ potential and decreasing repulsive forces between As and surface sites. δMnO2 exhibits oxidative and adsorptive potential for As(Ⅲ), and may be employed as adsorbents or filter coating for As removal in water treatment process.     

The Uniqueness of Market Economy in China

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Anti-TOSO antibody treatment promotes T cell activation-induced cell death （AICD） in vitro and in vivo

T cell activation-induced cell death （AICD）, that involves the induction of Fas-mediated apoptosis, is very important for the maintenance of immune homeosta- sis. TOSO was firstly described as an inhibitor of Fas- mediated apoptosis and overexpressed in chronic lymphocytic leukemia. Recently, TOSO was identified as IgM FcR. In this study, we produced anti-TOSO monoclonal antibody （mAb） that could block the binding of IgM to TOSO and found that T cell apoptosis is negatively cor- related with TOSO expression during T cell activation. Treatment of activated T cells with anti-TOSO blocking mAb promoted T cell AICD in in vitro AICD model, and treatment of xenogeneic-GVHD mice with the antibody also increased the sensitivity of activated T cells to Fas- induced apoptosis, which was accompanied by reduction of c-FLIPL expression and up-regulation of AP-1 complex. In summary, our data indicate the anti-apoptotic effect of TOSO in T cell AICD and open up new therapeutic prospects for the treatment of hematologic malignancies and immune disorders.     

A new anti-hypoxia functional agent ―a Schizophyllum commune fermented broth and its possible biochemical mechanisms

In order to overcome hypoxia induced sickness,a stable source of anti-hypoxia functional agents, Schizophyllum commune fermented broth has been developed in this study. Animal experiments were conducted to examine its anti-hypoxia activities and possible mechanisms involved. The acute hypoxic experiment showed that Schizophyllum commune fermented broth could significantly prolong the survival time of mice. The underlying mechanisms were associated with improved energy metabolism based on a study carried out in rats exposed to a low pressure chamber simulating the low pressure environment of 8 000 m altitude. It was concluded that the Schizophyllum commune fermented broth was an effective anti-hypoxia functional agent and could be greatly bene- ficial to those living and working at high altitudes,such as people who reside in the reconstruction regions of Yushu.     

Recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation: process optimization and mineralogical study

Currently, the majority of copper tailings are not effectively developed. Worldwide, large amounts of copper tailings generated from copper production are continuously dumped, posing a potential environmental threat. Herein, the recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation was conducted; process optimization was carried out, and the corresponding mineralogy was investigated. The reduction time, reduction temperature, reducing agent (coal), calcium chloride additive, grinding time, and magnetic field intensity were examined for process optimization. Mineralogical analyses of the sample, reduced pellets, and magnetic concentrate under various conditions were performed by X-ray diffraction, optical microscopy, and scanning electron microscopy-energy-dispersive X-ray spectrometry to elucidate the iron reduction and growth mechanisms. The results indicated that the optimum parameters of iron recovery include a reduction temperature of 1150℃, a reduction time of 120 min, a coal dosage of 25%, a calcium chloride dosage of 2.5%, a magnetic field intensity of 100 mT, and a grinding time of 1 min. Under these conditions, the iron grade in the magnetic concentrate was greater than 90%, with an iron recovery ratio greater than 95%.     

Reduction mechanisms of pyrite cinder-carbon composite pellets

The non-isothermal reduction mechanisms of pyrite cinder-carbon composite pellets were studied at laboratory scale under argon (Ar) atmosphere. The composite pellets as well as the specimens of separate layers containing pyrite cinder and coal were tested. The degree of reduction was measured by mass loss. The microstructures of the reduced composite pellets were characterized by scanning electron microscopy (SEM). It is found that the reduction processes of the composite pellets may be divided into four stages:reduction via CO and H₂ from volatiles in coal at 673-973 K, reduction via H₂ and C produced by cracking of hydrocarbon at 973-1123 K, direct reduction by carbon via gaseous intermediates at 1123-1323 K, and direct reduction by carbon at above 1323 K. Corresponding to the four stages, the apparent activation energies (E) for the reduction of the composite pellets are 86.26, 78.54, 72.01, and 203.65 kJ·mol-1, respectively.     

纳米材料的环境行为与生物毒性

随着纳米科技迅猛发展, 越来越多的人开始关注并研究纳米材料的环境行为和生物毒性. 本文概括地介绍了纳米材料的排放途径和可能发生的环境行为, 重点分析了纳米材料与环境中共存物质的复合行为; 综述了碳纳米材料、金属及氧化物纳米材料、量子点等对细胞、细菌、水生生物、陆生生物等的毒性效应, 阐述了当前对纳米材料致毒机理的有关争论; 最后, 展望了纳米材料环境行为和生物毒性领域的研究方向.