Gelling behavior of MgAl2O4 slurries with a common dispersant

MgAl₂O₄ transparent ceramics were shaped by a commonly used polyacrylic acid (PAA), which acted as both dispersant and gelling agent. The spinel slurries were prepared by ball-milling MgAl₂O₄ powder, PAA, and water in an attrition mill. The gelling of slurries happened at room temperature in air atmosphere without any other organic additive. The gelling mechanism was the formation of chelates between Mg²⁺ and carboxyl groups (-COO⁻) of PAA. The frequency-based testing method was applied to investigate the gelling process of the as-prepared slurry. In addition, a novel in situ characterization method based on a modified indentation testing was invented to better understand the strengthening of the wet green body with time and to guide when demolding could be carried out. After sintering, transparent MgAl₂O₄ ceramics with high in-line transmittance were resulted.     

Electron transfer mediator PCN secreted by aerobic marine Pseudomonas aeruginosa accelerates microbiologically influenced corrosion of TC4 titanium alloy

Titanium alloys possess excellent corrosion resistance in marine environments,thus the possibility of their corrosion caused by marine microorganisms is neglected.In this work,microbiologically influenced corrosion (MIC) of TC4 titanium alloy caused by marine Pseudomonas aeruginosa was investigated through electrochemical and surface characterizations during a 14-day immersion test.Results revealed that the unstable surface caused by P.aeruginosa resulted in exposure of Ti2O3 and severe pitting corrosion with maximum pit depth of 5.7 μm after 14 days of incubation.Phenazine-1-carboxy[ate (PCN),secreted by P.aeruginosa,promoted extracellular electron transfer (EET) and accelerated corrosion.Deletion of the phzH gene,which codes for the enzyme that catalyzes PCN production,from the P.aeruginosa genome,resulted in significantly decreased rates of corrosion.These results demonstrate that TC4 titanium alloy is not immune to marine MIC,and EET contributes to the corrosion of TC4 titanium alloy caused by P.aeruginosa.     

井工转露天采区顶板厚度不足诱发滑坡问题研究

井工转露天开采是安全生产遇到的新问题。以紫金山金铜矿为背景，利用数值模拟法系 统研究了井 工转露天开采工况下顶板厚度从 68 m 逐渐减小至 44 m 时顶板的安全性，界定出顶板最小安 全厚度为 45 m。同时 系统研究了顶板厚度变化对上部边坡应力场的影响特点，得出随着顶板变薄坡脚处塑性破坏区 增大，导致边坡稳 定性变小的规律，并通过边坡稳定性分析计算验证其正确性。因此在井工转露天开采过程中， 为了确保安全生产 需要确保顶板有足够的厚度，避免作业设备和工作人员坠入老井采区及滑坡灾害发生。     

基于(→H)边值关系的面电流定义的重构

本文从场强(→H)边值关系的推演及面电流应用两个方面,揭示面电流的物理本质:将分布在媒质表面邻域内的体电流等效为二维平面上的电流,引入面电流密度(→JS)表征电荷在二维面空间上的运动特点.同时,由场强(→E)的边值关系以及微分形式的欧姆定律可知由于不同媒质电导率间的差异,媒质分界面处电流密度的切向分量将发生突变.然而切向电流密度的突变并不会导致面电流的产生.     

红岩自卸车自锁自检远程监控系统设计

介绍了目前常用的自卸车举升安全防护系统,结合企业现状进行优化,确定改造方案,设计出一种"自锁自检远程监控系统",实现了远程实时监控功能。     

Fabrication of Co doped MoS2 nanosheets with enlarged interlayer spacing as efficient and pH-Universal bifunctional electrocatalyst for overall water splitting

Exploring inexpensive and active bifunctional electrocatalysts to produce hydrogen and oxygen from water at all pHs is highly desirable. Herein, we report a facile one-step method to prepare vertically aligned Co doped MoS₂ nanosheets with extended interlayer distance on carbon cloth (Co–MoS₂@CC) for full hydrolysis in both alkaline and acidic medium. Co–MoS₂@CC exhibits long-term durability with overpotentials of 56.6 mV and 130 mV for hydrogen generation and 242 mV and 201 mV for oxygen production at 10 mA cm^?2 in basic and acidic conditions, respectively. Moreover, we achieve low voltages of 1.585 V and 1.55 V in basic and acidic conditions respectively for the overall water splitting. We assume that such excellent property of Co–MoS₂@CC may be ascribed to the uncovering of more active sites and high porosity resulted from Co doping, which boosts the conductivity and thus reduces MoS₂ hydrogen adsorption free energy in HER, as well as benefits to catalytic active sites in OER. This one-step doping approach opens up new ways to regulate the intrinsic catalytic activity to catalyze total hydrolysis at all PHs.     

某福利院一起肠炎沙门菌食源性疾病的调查分析

目的 对某福利院一起肠炎沙门菌食源性疾病进行调查和溯源,为研究相关食源性疾病提供参考。方法采用流行病学、食品卫生学和脉冲场凝胶电泳(PFGE)同源性分析等方法,分析本次食源性疾病事件。结果 确认本次事件中病例23名,患病率5.65%(23/407)；现场采集病例肛拭子15份和厨房工作人员肛拭子3份、留样菜品3份、水果2份以及冰棒1份,其中从11份病例肛拭子中检出肠炎沙门菌,PFGE结果显示11株肠炎沙门菌的DNA条带图谱相似性为96.4%,聚类分析为同一型,结合流行病学调查,初步判断菌株来自同一克隆系。结论 综合流行病学、食品卫生学和实验室检测结果,确定为一起肠炎沙门菌引起的食源性疾病,福利院应加强对特殊人群的饮食安全管理,制定相应的食源性疾病突发事件应急处理预案,防止此类事故再发生。     

芳烃抽提装置工艺节能优化

通过对芳烃抽提装置工艺节能优化改造,缩短了装置开工时间,减少了公共能源的使用,提高了整体经济效益.     

ZrO2陶瓷相变稳定化的研究进展

氧化锆(ZrO2)陶瓷材料具有质地轻、耐腐蚀、耐高温、力学性能优异等特点,应用非常广泛,一直受到许多研究者的广泛关注.综述了近年来国内外ZrO2陶瓷相变及稳定化研究现状,总结了添加稳定剂对ZrO2陶瓷性能的影响,探讨了ZrO2陶瓷的制备方法及工艺、掺杂改性、相变增韧等方面的研究现状,并展望了ZrO2陶瓷相变稳定化的未来研究方向.