Electric Conductivity

We study theI-Vcharacteristic of mesoscopic systems or quantum dot (QD) attached to a pair of superconducting leads. Interaction effects in the QD are considered through the charging energy of the QD; that is, the treatment of current transport under a voltage bias is performed within a coupled Poisson nonequilibrium Green function (PNEGF) formalism. We derive the expression for the current in full generality but consider only the regime where transport occurs only via a single particle current. We show for this case and for various charging energies valuesU0and associated capacitances of the QD the effect on theI-Vcharacteristic. Also the influence of the coupling constants on theI-Vcharacteristic is investigated. Our approach puts forward a novel interpretation of experiments in the strong Coulomb regime.

Evaluation of soybean [Glycine max (L.) Merrill] seeds vigor and its relation with field seedling emergence can provide secure indicatives of seed physiological potential. The present research studied the relationship between the electrical conductivity test and the seedling emergence of soybean in field and laboratory. The field experiment was sown in November 26th, December 3td and 10th, 2000. Laboratory tests were performed using levels of water potential in the substrate (soil) -0.03; -0.2; -0.4; and -0.6 MPa. Fourteen seed lots, seven of 'Embrapa 48' and seven of 'BRS 133' soybean cultivars were used. Laboratory tests comprised seed water content determination, before and after the accelerated aging; germination and vigor tests (accelerated aging and electrical conductivity). Germination and seedling emergence decreased as the substrate water potential was reduced, indicating a relationship among the germination, water potential and seed vigor. For the 'Embr...

Transparent conducting ZnO:F was deposited as thin films on soda lime glass substrates by atmospheric pressure chemical vapor deposition (CVD) deposition at substrate temperatures of 480–500 °C. The precursors diethylzinc, tetramethylethylenediamine and benzoyl fluoride were dissolved in xylene. The solution was nebulized ultrasonically and then flash vaporized by a carrier gas of nitrogen preheated to 150 °C. Ethanol was vaporized separately, and these vapors were then mixed to form a homogeneous vapor mixture. Good reproducibility was achieved using this new CVD method. Uniform thicknesses were obtained by moving the heated glass substrates through the deposition zone. The best electrical and optical properties were obtained when the precursor solution was aged for more than a week before use. The films were polycrystalline and highly oriented with the c-axis perpendicular to the substrate. The electrical resistivity of the films was as low as 5 × 10−4 Ωcm. The mobility was about ...

Rapid advances in biosensors have recently been reported. This has been possible due to rapid growth in the development of new biomaterials such as conducting polymers, copolymers and sol gels etc and the reported improvements in sensing techniques. Biosensors are miniaturized devices employing biochemical molecular recognition as the basis for a selective analysis. The response generated as a result of biochemical reaction is detected by a transducer to give a signal (optical/electrical/thermal) that can be used with or without amplification for the estimation of the concentration of an analyte in a given test sample. Among the various biosensors, electrochemical sensors, especially amperometric biosensors presently hold a leading position.Due to specificity, portability, simplicity, high sensitivity, potential ability for real-time and on-site analysis coupled with the speed and low cost, biosensors have been projected to have applications in food analysis, environment control, clinical detection, drug and agriculture industries etc. Besides this, biosensors offer exciting opportunities for numerous decentralized clinical applications, ranging from emergency room screening, home self testing and alternative site testing, continuous and real-time in vivo monitoring. New generation of biosensors combining new bioreceptors with the ever-growing number of transducers is emerging. The present paper highlights some of the recent advances in the area of biosensors contributed by our laboratory.