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Antioxidant parameters, such as total glutathione, glutathione S-transferase, glutathione peroxidase, glutathione reductase, glyoxalases, catalase, and some heavy metals such as, lead, cadmium and chromium were examined in hepatopancreas of both sexes of Procambarus clarkii collected seasonally from Lake Trasimeno, from winter 2002-2003 to autumn 2003. Heavy metals content in hepatopancreas in males and females of P. clarkii was low and did not vary through the sampling periods and between sexes. On the contrary, crayfish exhibited sex-dependent differences in levels of some enzyme activities and of total glutathione, and no apparent relationship was found between contaminant burdens and antioxidant indexes in hepatopancreas. Because measured metal concentrations were low, other factors, presumably, were involved in antioxidant variations in P. clarkii and these latter seemed to be affected more by biological and environmental factors, other than those related to pollutants body burdens.

Semiconductor manufacturing is a complex multistage manufacturing process, and wafer fabs use complex processes involving billions of dollars worth of equipment to produce integrated circuits. The level of complexities associated with an integrated circuit is increasing in terms of feature size and number of devices. Companies use several performance metrics such as defectiveness, yield, and cycle time to improve manufacturing performance. Maintaining high yield through reliable and accurate quality control measures is one of the key performance criteria used by companies. The intent of this paper is to provide a review of the literature dealing with critical aspects of yield modelling. A review of many topics from simple probabilistic yield models to the incorporation of critical features such as spatial defects and radial yield losses will be provided. We will also assess empirical techniques used to model variations associated with complex interrelated wafer manufacturing processes. We emphasize that yield modelling should not be considered in isolation and system-wide aspects are necessary for integrated yield modelling and analysis. [ABSTRACT FROM AUTHOR]

Presents a study which measured the thermal conductivity of heavily doped low-pressure chemical vapor deposited polycrystalline silicon films. Fabrication process for the bridges; Theoretical considerations; Experimental details.

A class of 'lab-on-a-chip' devices use external air pressure for pumping discrete drops in a microchannel network. External air connectors can be cumbersome and are real-estate intensive. We have developed an on-chip technique to generate pressures required for metering and pumping of nanoliter-volume discrete drops. This is achieved by heating of trapped air in a pressure-generating chamber. The pressure-generating chamber is connected to the point of pressure application in the liquid-conveying microchannel through an air-delivery channel. The trapped air volume on the order of 100 nL is heated by resistive metal heaters by tens of degrees celcius to generate air pressures on the order of 7.5 kN/[m.sup.2]. The rate of discrete drop pumping is electronically controlled in the microchannel device by controlling the rate of air heating. Flow rates on the order of 20 nL/s are obtained in the microchannel (300 [micro]m x 30 [micro]m) by heating the air chamber at the rate of ~6 [degrees] C/s. In this paper, we describe the design, fabrication, and operation of this new technique of generating on-chip air pressure, used for metering and pumping nanoliter discrete drops in microchannels.

A monolithic capillary electrophoresis system with integrated on-chip fluorescence detector has been microfabricated on a silicon substrate. Photodiodes in the silicon substrate measure fluorescence emitted from eluting molecules. The device incorporates an on-chip thin-film interference filter that prevents excitation light from inhibiting the fluorescence detection. A transparent AZO conducting ground plane is also used to prevent the high electric fields used for the separation from interfering with the photodiode response. Separations of DNA restriction fragments have been performed in these devices with femtogram detection limits using SYBR Green I intercalating dye.

The identification of parameters that dictate the magnitude of rotor power losses in radial magnetic bearings is very important for many applications. Low loss performance of magnetic bearings in aerospace equipment such as jet engines and flywheel energy storage systems is especially critical. Two basic magnetic bearing designs are employed in industrial practice today: the homopolar design, where the flux paths are of a mixed radial/axial orientation, and the heteropolar design, where the flux paths are primarily radial in nature. The stator geometry and flux path of a specific bearing can have a significant effect on the rotor losses. This paper describes the detailed measurement of rotor losses for experimentally comparable homopolar and heteropolar designs. The two test bearing configurations are identical except for geometric features that determine the direction of the flux path. Both test bearing designs have the same air gap length, tip clearance ratio, surface area under the poles, and bias flux levels. An experimental test apparatus was used where run down tests were performed on a test rotor with both bearing designs to measure power losses. Numerous test runs where made for each bearing configuration by running multiple levels of flux density. The components of the overall measured power loss, due to hysteresis, eddy currents, and windage, were determined based on theoretical expressions for power loss. It was found that the homopolar bearing had significantly lower power losses than the heteropolar bearing.