熔炼低品位电子废料中铜的湿法冶金选择性回收

比较从低品位电工电子废料中选择性回收铜的3种湿法冶金方法。首先将废料熔炼成Cu?Zn?Sn?Ag合金,并采用SEM?EDS和XRD进行表征。对合金进行阳极溶解,首先采用氨溶液和硫酸溶液对合金进行电沉积或在氨?硫酸铵溶液中浸出,然后进行电沉积铜。实现了各种金属分离,Pb、Ag 和Sn等沉积在阳极泥中,而铜则转移至电解液中并在阴极上还原析出。最佳的处理条件为在硫酸溶液中浸出,获得的最终产品为高纯Cu(99%),电流效率为90%。采用氨浸出可使Cu离子富集在电解液中,利于后续的电沉积,但是自发溶解的速率较低。在氨?硫酸铵溶液中进行阳极溶解不利于各种金属在阳极泥、电解液和阴极沉积物进行分离。     

基于光学相干层析气冲印压技术研究角膜生物力学特性

结合频域光学相干断层层析术(SDOCT)以及空气脉冲印压技术(OCT气冲印压系统)研究了角膜的生物力学特性。采用热成型硅胶模拟角膜形态设计制作了8种不同硬度的角膜仿体,通过联接吊瓶和压力传感器控制并设定角膜仿体的前房压力。运用快速气脉冲作用于角膜,同时用OCT记录角膜整个动态形变过程,测得了角膜仿体形变参数——最大压陷深度(DA),并分析得到了反映角膜生物力学特性的硬度系数。结果显示:角膜仿体中央的实际厚度为(504.12±17.04)μm,不同硬度硅胶的角膜仿体的杨氏模量为90~1 400kPa,同一角膜仿体的杨氏模量值与模拟前房眼内压成正相关。同一眼内压下3次重复性实验表明OCT系统测量参数DA具有很高的重复性(ICC=0.992 6);不同观察者A和B的一致性实验表明,DA具有很好的一致性(差值均值为1.1μm)。不同眼压下所得仿体角膜的硬度系数与传统的拉伸实验测得的该仿体的杨氏模量具有明显的相关性(r=0.99,P0.001)。得到的测试结果表明,OCT气冲印压系统可以用来检测角膜生物力学特性,系统测量结果精确可靠。     

Subarachnoid neurocysticercosis with occlusion of the major intracranial arteries: case report

Cysticercosis is the most common parasitic disease affecting the central nervous system. Stroke is a recognized complication of neurocysticercosis, occurring in 2 to 12% of cases, mostly in the form of small lacunar infarcts. We report a case of hemiparesis and aphasia in a 51-year-old Hispanic woman, which was secondary to complete occlusion of the left internal carotid and bilateral anterior cerebral arteries. Magnetic resonance imaging demonstrated the presence of enhancing subarachnoid material surrounding these occluded cerebral arteries, providing antemortem, noninvasive documentation of the inflammatory meningeal cysticercotic reaction that was presumably responsible for the occlusive arteritis causing the cerebral infarction. This represents the third reported case of internal carotid artery occlusion and the first reported case of anterior cerebral artery occlusion secondary to neurocysticercosis.     

The fracture and fatigue behaviour of nano-modified epoxy polymers

The introduction of nano-silica particles into an epoxy polymer has increased both the initial toughness, as measured by the fracture toughness, K_Ic, and also significantly improved the cyclic-fatigue behaviour of the epoxy polymer. Thus, the significant increases recorded in the values of the range of applied stress-intensity factor at threshold, ΔK_th, from the cyclic-fatigue tests for the nano-silica modified materials are very noteworthy, since these increases are accompanied by significant improvements being recorded in the initial toughness.     

Textural and Structural Properties of Mesoporous Silica Synthesized Under Refluxing Conditions

Mesoporous silica with pore sizes of 3–6 nm has been synthesized under refluxing and autogenous pressure conditions of hydrothermal synthesis from precursor gels having different alkaline pH. The mesoporous silica prepared is characterized by powder X-ray diffraction, nitrogen adsorption-desorption measurement and scanning electron microscopy. Thermal stability has been tested by XRD analysis of mesoporous silica after thermal treatment at 823 K, 6 h; 1023 K, 1 h and 1223 K, 1 h. The results indicate that the mesoporous silica prepared under refluxing condition from precursor gel of pH 11 has large surface area (ca.1103 m² g^{− 1}) and pore volume (ca. 0.868 cm³ g^{− 1}) and is thermally stable at 1223 K. The surface area, pore volumes and pore wall thickness increase as the pH of the precursor gel is increased for refluxing condition of synthesis. The comparison of textural properties revealed that the refluxing condition is advantageous over autogenous pressure condition for obtaining mesoporous silica with higher surface area (852 m² g^{− 1}), pore volume (0.894 cm³ g^{− 1}) and pore diameter > 4 nm with wall thickness of 1.59 nm, when synthesized from precursor gel of pH 9.2. The ²⁹Si NMR spectra showed that a great part of the Si atoms exists as silanol groups. The mesoporous silica made at the lower pH (9.2) under refluxing conditions have more condensed framework. In calcined mesoporous silica, the proportion of partly condensed silica (Q³) is higher than fully condensed silica (Q⁴).