Experimental study on the permeability and self-healing capacity of geosynthetic clay liners in heavy metal solutions

Geosynthetic clay liners (GCLs), which have a very low permeability to water and a considerably high self-healing capacity, are widely used in liner systems of landfills. In this study, a series of experimental tests were carried out under complex conditions on typical commercial GCLs from China. In particular, the effects of pH values and lead ions (Pb²⁺) were tested in addition to other factors. The swelling properties of natural bentonite encapsulated between geotextile components in the GCLs were tested first. The swelling capacity was reduced rapidly at pH values < 3 and concentrations of Pb²⁺ >40 mM. Permeability tests on GCLs with different concentrations of lead ions were then performed by using the self-developed multi-link flexible wall permeameter, and data showed that increases in lead ion concentrations greatly improved the permeability. Finally, self-healing capacity tests were conducted on needle-punched GCLs under different levels of damage. Results showed that the GCLs have a good self-healing capacity with small diameter damage holes (2 mm, close to three times the original aperture), but with a damage aperture larger than 15% of the sample area, the self-healing capacity could not prevent leakage; hence, in certain situations it will be necessary to repair the damage to meet the anti-seepage requirement.     

A new Pd-oxide-Al/sub 0.3/Ga/sub 0.7/As MOS hydrogen sensor

A new and interesting Pd-oxide-Al/sub 0.3/Ga/sub 0.7/As MOS hydrogen sensor has been fabricated and studied. The steady-state and transient responses with different hydrogen concentrations has been measured at various temperatures. Based on the large Schottky barrier height and presence of oxide layer, the studied device exhibits a high hydrogen detection sensitivity and wide temperature operating regime. The studied device exhibits the low-leakage current and obvious current changes when exposed to hydrogen-contained gas. Even at room temperature, a very high hydrogen detection sensitivity of 155.9 is obtained when a 9090 ppm H/sub 2//air gas is introduced. Furthermore, when exposed to hydrogen-contained gas at 95/spl deg/C, both the forward and reverse currents are substantially increased with increased hydrogen concentration. In other words, the studied device can be used as a hydrogen sensor under the applied bidirectional bias. Under the applied voltage of 0.35 V and 9090 ppm H/sub 2//air hydrogen ambient, a fast adsorption response time about 10 s is found. The transient and steady-state characteristics of hydrogen adsorption are also investigated.     

A novel InP/InGaAs TEBT for ultralow current operations

A novel InP/InGaAs tunneling emitter bipolar transistor (TEBT) is fabricated and demonstrated. The studied device exhibits a very small collector-emitter offset voltage of 40 mV and an extremely wide operation regime. The operation region is larger than 11 decades in magnitude of collector current (10/sup -12/ to 10/sup -1/A). A current gain of 3 is obtained even if the device is operated at an ultralow collector current of 3.9 /spl times/ 10/sup -12/A (1.56 /spl times/ 10/sup -7/A/cm/sup 2/). Furthermore, the common-emitter breakdown voltage of the studied device is higher than 2 V. Consequently, the studied device shows a promise for low supply voltage, and low-power consumption circuit applications.     

A Relational Model of Workplace Victimization: Social Roles and Patterns of Victimization in Dyadic Relationships.

This article proposes a model of the ways in which dyadic interactions between employees who occupy 1 of 4 archetypal social roles in organizations can lead to either episodic or institutionalized patterns of victimization. The model shows how the occurrence of victimization involving these 4 role types is influenced by organizational variables such as power differences, culture, and access to social capital. The model integrates behavioral and social structural antecedents of victimization to develop a relational perspective on the dynamics of harmful behavior in the workplace. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

椰子油甲酯化法合成烷基醇酰胺

以国产椰子油为原料,在碱性催化剂作用下先甲酯化再缩合制备烷基醇酰胺,通过多次平行实验,确立了最佳反应条件:甲酯化反应的油醇比(mol)为1:5,催化剂氢氧化钾用量为剂油比(w)0.07:1,反应时间1小时;缩合反应的酯胺比(mol)为1:1.15,催化剂氢氧化钾用量为剂酯比(w)0.01:1,反应温度100～110℃,反应压力40～50mmHg,反应时间3.5小时.     

„Patriot“

Ohne Zusammenfassung     

OC-48、OC-192芯片和系统设计师面临挑战

当今，从事OC-48、OC-192技术的设计师在设计基于因特网协议(IP协议)的下一代系统时，因系统含有诸如ASIC、网络处理器(NP)、高速跟踪器等元件，以及分组SONET物理层(PoS-PHY)接口规范等的演变，而一直面临挑战。抖动和扭斜失真等现象的存在给诸如系统分组接口第4层(SPI-4)和通用交换接口(CSIX)等总线结构本已拥挤的时序容限，以及四元数据率静态RAM传送表访问时间带来极大混乱。再加上诸如低压差分信号(LVDS)、高速收发逻辑和短线串行终端逻辑等超低电压峰-峰信号技术的引入，使数据出错的可能性变得异常之高。而利用仿真技…     

SIMULATION STUDIES OF THE REMOVAL OF WATER FROM ETHANOL BY A CATALYTIC DISTILLATION PROCESS

A new approach based on catalytic distillation (CD) technology was proposed to remove water from ethanol. Isobutylene was introduced to react with water in the CD column. The commercial software simulation tool Aspen Plus was used to investigate the effects of key design factors such as operating pressure and temperature, reactant ratios, reflux and distillate to feed ratios, number of separation and reaction stages, and feed and reaction zone location. It was found that the CD technology offers potential advantages of reduced energy consumption and reduced capital cost over traditional approaches for the removal of water from ethanol.