Effects of piracetam on the performance of rats in a delayed match-to-position task

The growing use of antibody-based separation methods has paralleled the expansion of immunochemical detection methods in moving beyond the clinical diagnostic field to applications in environmental monitoring. In recent years high-performance immunoaffinity chromatography, which began as a separation technique in biochemical and clinical research, has been adapted for separating and quantifying environmental pollutants. Bioaffinity offers a selective biological basis for separation that can be incorporated into a modular analytical process for more efficient environmental analysis. The use of immunoaffinity chromatography for separation complements the use of immunoassay for detection. A widely used immunochemical detection method for environmental analyses is enzyme immunoassay. The objective of this paper is to review the status of bioaffinity-based analytical procedures for environmental applications and human exposure assessment studies. Environmental methods based on bioaffinity range from mature immunoassays to emerging techniques such as immunosensors and immunoaffinity chromatography procedures for small molecules.     

Spin injection in n-type resonant tunneling diodes

We have studied the polarized resolved photoluminescence of n-type GaAs/AlAs/GaAlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. Under resonant tunneling conditions, we have observed two emission lines attributed to neutral (X) and negatively charged excitons (X⁻). We have observed a voltage-controlled circular polarization degree from the quantum well emission for both lines, with values up to −88% at 15 T at low voltages which are ascribed to an efficient spin injection from the 2D gases formed at the accumulation layers.     

Approximation of the Crank-Nicholson method by the iterated dynamic-theta method

Choptuik's iterated Crank-Nicholson method has become a popular algorithm for solving partial differential equations in computational physics. We generalize Choptuik's explicit iteration approach to implicit finite difference schemes, by the introduction of a novel method with an iteration step dependent parameter and analyze its stability and computational efficiency.     

Feasibility of a one–step process for desizing,scouring, bleaching and mercerisating cotton fabrics

In this study the desizing, scouring, bleaching and slack mercerising of cotton fabric by a one–step process at different sodium hydroxide concentrations, impregnation temperatures and curing times were examined. The results indicate that when the fabrics are mercerised at lower temperature, the strength retention and colour strength are enhanced. When the sodium hydroxide concentration is increased, these properties also increase. When cotton fabrics are mercerised for 3 min at 40C and cured for 30 s at 120C, their physical properties are similar to those obtained using a conventional two–step approach.     

Pheromone regulated production of inositol-(1, 4, 5)-trisphosphate in the mammalian vomeronasal organ

Social behaviors of most mammals are profoundly affected by chemical signals, pheromones, exchanged between conspecifics. Pheromones interact with dendritic microvilli of bipolar neurons in the vomeronasal organ (VNO). To investigate vomeronasal signal transduction pathways, microvillar membranes from porcine VNO were prepared. Incubation of such membranes from prepubertal females with boar seminal fluid or urine results in an increase in production of inositol-(1, 4, 5)-trisphosphate (IP3). The dose response for IP3 production is biphasic with a GTP-dependent component at low stimulus concentrations and a nonspecific increase in IP3 at higher stimulus concentrations. The GTP-dependent stimulation is mimicked by GTPgammaS and blocked by GDPbetaS. Furthermore, the GTP-dependent component of the stimulation of IP3 production is sex specific and tissue dependent. Studies with monospecific antibodies reveal a G alpha(q/11)-related protein in vomeronasal neurons, concentrated at their microvilli. Our observations indicate that pheromones in boar secretions act on vomeronasal neurons in the female VNO via a receptor mediated, G protein-dependent increase in IP3. These observations set the stage for further investigations on the regulation of stimulus-excitation coupling in vomeronasal neurons. The pheromone-induced IP3 response also provides an assay for future purification of mammalian reproductive pheromones.