Microstructural Analysis of Liquid-Phase-Sintered β-Silicon Carbide

The microstructures of fine-grained β-SiC materials with α-SiC seeds annealed either with or without uniaxial pressure at 1900°C for 4 h in an argon atmosphere were investigated using analytical electron microscopy and high-resolution electron microscopy (HREM). An applied annealing pressure can greatly retard phase transformation and grain growth. The material annealed with pressure consisted of fine grains with β-SiC as a major phase. In contrast, the microstructure in the material annealed without pressure consisted of elongated grains with half α-SiC. Energy-dispersive X-ray analysis showed no differences in the amount of segregation of aluminum and oxygen atoms at grain boundaries, but did show a significant difference in the segregation of yttrium atoms at grain boundaries along SiC grains for the two materials. The increased segregation of yttrium ions at grain boundaries caused by the applied pressure might be the reason for the retarded phase transformation and grain growth. HREM showed a thin secondary phase of 1 nm at the grain boundary interface for both materials. The development of a composite grain consisting of a mixture of β/α polytypes during annealing was a feature common to both materials. The possible mechanisms for grain growth and phase transformation are discussed.     

立方形纳米碳酸钙的工业制备

介绍了工业制备高品质立方形纳米碳酸钙普遍适用的工艺路线及化学原理，提出了新的碳化反应模型、速率方程和晶体形貌控制理论，并讨论了生产过程中影响碳酸钙粒径的各种因素。     

Cu2O/Cu Cermet as a Candidate Inert Anode for Al Production

Cu₂O/ x Cu ( x =0–25 wt%) cermets were evaluated as a novel partially inert anode for aluminum (Al) production. The physical and mechanical properties, including the compressive strength, flexural strength, thermal expansion coefficient, thermal conductivity, and dc electrical conductivity were tested at room temperature and at temperatures up to 950°C. The coefficient of thermal expansion, compressive strength, flexural strength, thermal conductivity, and electrical conductivity of Cu₂O/Cu cermets increased with increasing Cu content. High-temperature electrical conductivity measurements showed that with increasing temperature, the electrical conductivity increased when the Cu content was below the percolation threshold, while it decreased when the Cu content was above the percolation threshold. A relatively stable CuAlO₂ layer formed on the cermet surface during electrochemical testing, and the corrosion rate of this anode was estimated to be about 1.8–1.9 cm/year in Al production.     

3-氨基-4-氯苯甲酸十六酯的合成

以3-氨基-4-氯苯甲酸和正十六醇为原料，二甲苯为溶剂，对甲苯磺酸为催化剂酯化合成3-氨基-4-氯苯甲酸十六酯。采用傅里叶红外光谱（FTIR）、核磁共振光谱（NMR）的方法对产品的结构进行表征。考察了醇酸摩尔比、催化剂加量、反应物浓度对酯化率的影响。结果表明：醇酸摩尔比1.2:1，催化剂用量为总质量5%，反应物浓度65%，反应时间7 h，酯化率达96.20%，单程收率为73.91%。研究确立了产物提纯、提高单程收率和滤液去除催化剂后回收、重复使用的最佳系统工艺路线，单程收率提至78.90%，总收率为82.62%，产品的纯度高于使用标准。     

低温快烧无铅精陶釉的研制

采用高温熔融法制备了适用精陶的低温无铅熔块，并应用热膨胀分析仪、SEM等方法研究了精陶釉的光泽度、热稳定性、热膨胀系数等性能。结果表明：采用Li2O，SrO，B2O3等复合熔剂，可以制备出光泽度高，热稳定好，坯釉膨胀系数匹配，结合良好，适于低温快烧工艺的无铅精陶釉。     

GRM-2SD120棉线缠绕机

介绍了GRM－2SD120棉线缠绕机的结构原理，重点介绍了该机的锭子部分，口型部分，锭子盘，中胶部分，传动原理，电气原理及主要技术参数。     

强震区土石坝筑坝材料动力特性试验研究(投稿研究生论坛)

土石坝筑坝材料的动力特性是进行坝工设计和动力评价的基础。以西部强震区某土石坝工程为研究对象,采用室内动三轴试验,对其坝壳料、心墙料和坝基断层料进行动力特性试验研究,并以Hardin-Drnevich模型为基础,确定筑坝材料的动弹模、阻尼比等特性参数,试验表明：在动应变在10-6 ～ 10-5 范围内,动模量与围压、固结比成正相关;随动模量的增大,相关性降低;动应变和振级的拟合指数模型则表明不同围压、固结比的心墙料的应变-振级曲线趋势一致,坝壳料较为离散;试验中固结围压对粗骨料阻尼比-应变曲线的影响较固结比大,可为强震区土石坝的动力稳定评价提供可靠的理论依据。     

微孔发泡塑料制备方法研究进展

综述了微孔发泡塑料制备方法的研究现状，分别介绍了几种常见的制备方法。提出了塑料微孔发泡技术中亟待解决的问题，并对微孔发泡塑料的研究及应用前景进行了展望。     

Change of short-term memory effect in acute ischemic ventricular myocardium: A computational study

The ionic mechanism of change in short-term memory (STM) during acute myocardial ischemia has not been well understood. In this paper, an advanced guinea pig ventricular model developed by Luo and Rudy was used to investigate STM property of ischemic ventricular myocardium. STM response was calculated by testing the time to reach steady-state action potential duration (APD) after an abrupt shortening of basic cycling length (BCL) in the pacing protocol. Electrical restitution curves (RCs), which can simultaneously visualize multiple aspects of APD restitution and STM, were obtained from dynamic and local S1S2 restitution portrait (RP), which consist of a longer interval stimulus (S1) and a shorter interval stimulus (S2). The angle between dynamic RC and local S1S2 RC reflects the amount of STM. Our results indicated that compared with control (normal) condition, time constant of STM response in the ischemic condition decreased significantly. Meanwhile the angle which reflects STM amount is less in ischemic model than that in control model. By tracking the effect of ischemia on intracellular ion concentration and membrane currents, we declared that changes in membrane currents caused by ischemia exert subtle influences on STM; it is only the decline of intracellular calcium concentration that give rise to the most decrement of STM.     

序批式生物膜法处理城市生活垃圾厌氧消化液脱氮的影响因素

探讨了序批式生物膜法处理有机生活垃圾厌氧消化液脱氮的影响因素,如温度、有机负荷、pH值和DO等,选择了最佳的运行条件.当控制DO在3.5～5.0 mg·L-1、pH值7.2～8.0、温度25℃左右时,反应器中有机物和氨氮的去除效果较好.