Cu/Li Ratio on the Microstructure Evolution and Corrosion Behaviors of Al–xCu–yLi–Mg Alloys

The microstructure evolution and the corrosion feature of Al–x Cu– y Li–Mg alloys( x : y = 0.44, 1.65 and 4.2) were systematically investigated under the same artificial aging conditions. The relationships between types of precipitates and mechanical performance, as well as electrochemical behaviors, were discussed. Our results show that different types of precipitates can be obtained in alloys with different Cu/Li mass ratios, which significantly influences the mechanical performance of the alloys and substantial corrosion behaviors. Specifically, the analogous corrosion evolution in the aging Al– x Cu– y Li–Mg alloys was first ascertained to be derived from the growth mechanism of the precipitates at the grain boundary(GB). Moreover, a small number of GB precipitates can be obtained in the aged alloy with the lowest Cu/Li mass ratio, thereby resulting in the largest intergranular corrosion resistance. A higher proportion of the GB T_1 phase in the continuous precipitates induces higher corrosion sensitivity in alloy with a high Cu/Li mass ratio.     

高效液相色谱-四极杆飞行时间质谱联用仪测定小鼠钩吻素子中毒模型的研究

目的通过动物急性钩吻素子染毒实验,建立一种测定小鼠钩吻素子的高效液相色谱-四极杆飞行时间质谱联用方法。方法小鼠经钩吻浸泡药酒染毒后取材,其血液、胃液、尿液通过1%甲酸乙腈沉淀蛋白后,进行上机分析。采用5 mmol/L乙酸铵-0.1%甲酸(A)和乙腈(B)作为流动相进行梯度洗脱,质谱正离子化信号采用母离子模式和子离子模式对钩吻素子进行监测。结果该实验结果显示1 h取材的动物样本,经过分析,胃液与尿液的差异性更大,且胃内容物钩吻素子含量较高。结论应急采样中,优先提供胃液物进行检验,其次到尿液。     

个性化浏览中网页推荐的结构模型

1 前言随着互联网建设的不断发展,网站和网页数目都已经很难用Lawrence在Science和Nature给出的结论来估算。每个在网上冲浪的人都有体会,迷失在Internet浩瀚的资料中是多么容易。世界上最大的搜索引擎Google已经宣称搜索并索引了2,073,418,204张网页,在这近21亿索引并分类的网页中搜索,用户同样会迷失在层层链接之中。     

P2P信息检索及其优化策略

本文研究对等计算（P2P）环境中语义丰富的信息检索及其优化策略，提出了P2P信息检索系统（PIRS），实现了P2P环境中语义丰富的信息检索，定义了一套评价PIRS效率的指标体系；明确了决定PIRS效率的关键因素并提出相应的解决策略，包括：基于向量空间模型的节点数据分类管理策略、基于节点聚类的系统数据管理策略以及自适应查询路由策略，并用实验结果验证了这些策略的有效性。     

山西某磁选铁精矿浮选脱硫试验

山西某磁选铁精矿铁品位为65.16%，S含量高达2.62%，主要铁矿物为磁铁矿，占总铁的92.23%；含硫矿物主要为磁黄铁矿和黄铁矿，分别占总硫的53.72%和45.67%，硫在粗粒级（+100目）和细粒级（-325目）的含量相对较高，超过70%的硫分布在-200目粒级。为降低该铁精矿中的硫含量，进行了反浮选脱硫试验。结果表明，试样采用1粗1精-粗选与精选尾矿合并扫选，扫选精矿返回粗选的闭路浮选流程处理，在粗选+精选丁基黄药用量为400+100 g/t、H106用量为950+450 g/t、松醇油用量为50+20 g/t的情况下，可获得铁品位为66.59%、含硫0.29%、铁回收率为91.40%的铁精矿和硫品位为22.13%、含铁52.75%、硫回收率为90.07%的硫精矿。     

Residual-stress relaxation mechanism and model description of 5052H32 Al alloy spun ellipsoidal heads during annealing treatment

Marginal-restraint mandrel-free spinning is an advanced technology for manufacturing ellipsoidal heads with large diameter-thickness ratios. Nevertheless, the spinning-induced residual stress, which greatly influences the in-service performance of spun heads, should be removed. In this study, the effects of annealing on the residual-stress relaxation behavior of 5052H32 aluminum alloy spun heads were investigated. It is found that the residual stress first rapidly decreases and then remains steady with the increase in annealing time at the tested annealing temperatures. The relaxation of the residual stress becomes increasingly obvious with the increase in annealing temperature. When the annealing temperature is less than 220℃, there are no obvious changes in grain size. Moreover, the spinning-induced dislocations are consumed by the static recovery behavior, which decreases the residual stress during annealing. When the annealing temperature is approximately 300℃, the broken grains transform into equiaxed grains. In addition, static recrystallization and recovery behaviors occur simultaneously to promote the relaxation of the residual stress. Considering the different stress relaxation mechanisms, a model based on the Zener-Wert-Avrami equation was established to predict the residual-stress relaxation behavior. Finally, the optimized annealing temperature and time were approximately 300℃ and 30 min, respectively.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-021-00367-w     

Effects of spinning parameters on microstructures of ellipsoidal heads during marginal-restraint mandrel-free spinning

Marginal-restraint mandrel-free spinning is an advanced technology for manufacturing ellipsoidal heads with large diameter-thickness ratios. The effects of spinning parameters on the forming accuracy of ellipsoidal heads have been studied, and optimized spinning parameters have been obtained. The microstructure evolution of a workpiece is usually very complicated in the spinning process. In this work, the influence of spinning parameters on the microstructures of two-pass spun ellipsoidal heads is studied. It is found that the forming angle and feed rate of the first pass, angle between passes, and feed rate of the second pass significantly affect the microstructures. Meanwhile, the evolution rule of the microstructures near the inner and outer surfaces of the spun parts is almost consistent. A large forming angle, large angle between passes, or large feed rate of the second pass are beneficial to obtain uniform microstructures. A small or large feed rate of the first pass reduces the microstructure uniformity. To improve the microstructure uniformity between the inner and outer surfaces, the optimized spinning parameters are determined.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00322-1     

某选矿厂选别工艺流程优化

针对某选矿厂赤铁矿中含有大量磁铁矿的生产现状，通过进行相关试验研究，提出了将原阶段磨矿、粗细分级、重选-强磁-阴离子反浮选选别流程中的强磁-阴离子反浮选流程改为磨矿-分级-淘洗精选流程的建议。试验结果表明：采用磨矿-分级-淘洗精选流程可以获得良好的经济效益和社会效益。     

Mechanical and microstructural properties of soy protein – high amylose corn starch extrudates in relation to physiochemical changes of starch during extrusion

Mechanical and microstructural properties of expanded extrudates prepared from blends of high amylose corn (Zeamays L. ssp. Mays) starch (HACS) and soy protein concentrate (SPC) were studied in relation to the physicochemical changes in starch. Effects of screw speed (230 and 330 rpm) and SPC level (10%, 20%, 30% and 50%) on expansion and mechanical properties were determined. Compared with 230 rpm, screw speed at 330 rpm resulted in increased specific mechanical energy, expansion ratio, water absorption and water solubility indices and decreased bulk density and piece density. Varying screw speeds did not significantly affect the mechanical strength of extrudates or starch molecular weight distribution. Bulk and piece densities, and water absorption index (WAI) only slightly increased or exhibited no significant trends as SPC level increased to 20%. A substantial increase in bulk and piece densities and decrease in expansion ratio and WAI were observed as SPC level increased from 20% to 30%. The trends were either reversed or moderated as SPC increased to 50%. These results in combination with average crushing force and water solubility index data provided a significant insight into the interactions between HACS and SPC during extrusion processing. As compared to an earlier baseline study by our research group on normal corn starch – SPC extrudates, results from the current study indicated that the expansion of extrudate containing HACS alone was lower than that of extrudates containing normal corn starch. However, expansion of the HACS–SPC blends was not significantly impacted at 10–20% SPC levels, whereas the expansion of normal corn starch was significantly reduced.