Preparation and characterization of poly(vinyl alcohol)‐poly(vinyl pyrrolidone) blend: A biomaterial with latent medical applications

Aqueous solutions of poly(vinyl alcohol) and poly(vinyl pyrrolidone) are blended and films are produced by casting method with the further intention of being used as bio‐materials with latent medical application. Glutaraldehyde, 4,4′‐diazido‐2,2′‐stilbenedisulfonic acid disodium salt tetra‐hydrate are used as crosslinker agents, whereas lactic acid is the plasticizer in the blend. The obtained films are characterized by differential scanning calorimetry (DSC), mechanical properties, swelling and solubility behavior. DSC measurements show that the blends exhibit a single glass transition temperature indicating that they are miscible, even in the presence of the plasticizer and crosslinker agents. By the combination of all mentioned additives, a relevant enhancement of the swelling is observed, accompanied by a stabilization of the solubility during the tested time. Finally, mechanical properties show an appropriate performance in the studied parameters. As a consequence, the obtained films could be suitable for use as medium or long‐term implants. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Chitosan–silver nanocomposites: New functional biomaterial for health-care applications

Chitosan–silver nanocomposites (CS-HDA-AgNCs) was prepared using chitosan, biogenic silver nanocomposites, and crosslinker, hexamethylene 1,6-di(amino carboxysulfonate) (HDA). The film is flexible and transparent. Its physical, mechanical, thermal, hydrophilicity, and swelling properties were improved by HDA (2.5%). The antimicrobial activity of CS-HDA-AgNCs were not displayed any remarkable zone of inhibition but showed toxic effect in the presence of normal 3T3 fibroblasts and cancer HeLa cells. It decreases to ca. 5–7% for both cell lines. In conclusion, it can be mentioned that the CS-HDA-AgNCs, a kind of new functional biomaterial, could be useful for health-care applications.     

An Improved Method for Load Taxonomy Using Sample Shifting Technique and Signature Analysis

This paper illustrates an improved method of classification of electrical appliances, particularly for domestic loads, to construct load taxonomy on the basis of their signature analysis. Each electrical load is characterized by its own distinct signature and hence load signature analysis is useful in monitoring the health of the equipment, power quality, in determining individual energy usage etc. type of services. On the other hand, load taxonomy classifies these loads in several clusters on the basis of some features extracted from their signatures. In traditional methods of construction of load taxonomy, different signature patterns based on power metrics, V-I trajectories, Eigen vectors, etc. In this proposed method, with the adoption of sample shifting technique the required number of feature extraction is reduced to a lower value to find out various signature patterns than those are required in traditional load taxonomies. Moreover, a better taxonomy, having well separated groups of loads is achieved with lower number of extracted features.     

Science and Technology of High Dielectric Constant Thin Films and Materials Integration for Application to High Frequency Devices

Thin films of Ba_1?x Sr _x Ti_1+y O_3+z (BST), were fabricated using both by RF-magnetron sputtering and MOCVD to demonstrate application to high frequency devices. Precise control of composition and microstructure is critical for the production of (Ba _x Sr_1?x )Ti_1+y O_3+z (BST) dielectric thin films with the large dependence of permittivity on electric field, low losses, and high electrical breakdown fields that are required for successful integration of BST into tunable high frequency devices. Here we review results on composition-microstructure-electrical property relationships of polycrystalline BST films produced by magnetron sputter deposition that are appropriate for microwave devices such as phase shifters. BST films with a multilayer structure were also developed with different Ti-elemental ratio in each layer to minimize losses and leakage current. Interfacial contamination from C and H species was studied and implications on electrical properties are highlighted. Finally, York's group at the University of California-Santa Barbara successfully integrated our BST films onto phase shifter arrays. The results show potential of BST films in such applications. Results from initial work on the integration of Cu-electrodes with BST films are also presented.     

Impact of Stone-Wales and lattice vacancy defects on the electro-thermal transport of the free standing structure of metallic ZGNR

We report the effect of topological as well as lattice vacancy defects on the electro-thermal transport properties of the metallic zigzag graphene nano ribbons at their ballistic limit. We employ the density function theory–Non equilibrium green’s function combination to calculate the transmission details. We then present an elaborated study considering the variation in the electrical current and the heat current transport with the change in temperature as well as the voltage gradient across the nano ribbons. The comparative analysis shows, that in the case of topological defects, such as the Stone-Wales defect, the electrical current transport is minimum. Besides, for the voltage gradient of 0.5 Volt and the temperature gradient of 300 K, the heat current transport reduces by \({\sim }62\,\%\) and \({\sim }50\,\%\) for the cases of Stones-Wales defect and lattice vacancy defect respectively, compared to that of the perfect one.     

Experience with return voltage measurements for assessing insulation conditions in service-aged transformers

This paper describes the investigation of the insulation condition of a number of power and distribution type transformers of different manufacturing dates and with different operating histories. Return voltage measurements were conducted for these transformers. Effects of moisture and aging on the oil-paper insulation of these transformers were investigated and results are presented in this paper. Moisture in oil samples at known temperature was measured for these transformers. Previously accelerated aging experiments were performed on paper wrapped insulated conductors in different environments over a temperature range of 115 to 145/spl deg/C. Results from the measurements on transformers are compared with those of the accelerated aged samples and are described in this paper.     

Negative bias temperature instability in strain-engineered p-MOSFETs: a simulation study

Negative Bias Temperature Instability (NBTI) in p-MOSFETs is a serious reliability concern for digital and analog CMOS circuit applications. Strain in the channel region affects negative bias temperature instabilities, low frequency noise, radiation hardness, gate oxide quality and hot carrier performance. The understanding of these phenomena in strain-engineered p-MOSFETs from fundamental physics is essential. In this paper, technology CAD (TCAD) has been used to study the effects of strain on the negative bias temperature instabilities in p-MOSFETs. A quasi two dimensional (quasi-2D) physics-based Coulomb scattering mobility model for strained-Si has been developed and implemented in Synopsys Sentaurus Device tool for device simulation to understand NBTI in strain-engineered p-MOSFETs.     

Impact of channel length,gate insulator thickness,gate insulator material,and temperature on the performance of nanoscale FETs

Aggressive technology scaling as per Moore’s law has led to elevated power dissipation levels owing to an exponential increase in subthreshold leakage power. Short channel effects (SCEs) due to channel length reduction, gate insulator thickness change, application of high-k gate insulator, and temperature change in a double-gate metal–oxide–semiconductor field-effect transistor (DG MOSFET) and carbon nanotube field-effect transistor (CNTFET) were investigated in this work. Computational simulations were performed to investigate SCEs, viz. the threshold voltage (V_th) roll-off, subthreshold swing (SS), and I_on/I_off ratio, in the DG MOSFET and CNTFET while reducing the channel length. The CNTFET showed better performance than the DG MOSFET, including near-zero SCEs due to its pure ballistic transport mechanism. We also examined the threshold voltage (V_th), subthreshold swing (SS), and I_on/I_off ratio of the DG MOSFET and CNTFET with varying gate insulator thickness, gate insulator material, and temperature. Finally, we handpicked almost similar parameters for both the CNTFET and DG MOSFET and carried out performance analysis based on the simulation results. Comparative analysis of the results showed that the CNTFET provides 47.8 times more I_on/I_off ratio than the DG MOSFET. Its better control over the threshold voltage, near-zero SCEs, high on-current, low leakage power consumption, and ability to operate at high temperature make the CNTFET a viable option for use in enhanced switching applications and low-voltage digital applications in nanoelectronics.     

Small-signal model for the single-electron transistor: part I

A simple small-signal model of the single-electron transistor is presented. The terminal voltage variations are considered to be sufficiently small to result in small current variations that can be expressed using linearized relations. The derivation of such relations and the development of an equivalent circuit to represent them are presented. Two-port analysis of the small-signal circuit of the single-electron transistor is proposed and explained using various parameters such as impedance parameters, admittance parameters, and hybrid parameters. The variation of the magnitude of these parameters is plotted with respect to frequency. The transconductance and drain resistances and their frequency variation are also discussed. The effect of parasitic capacitance on the proposed small-signal model is also analyzed.     

Online algorithms for searching and exploration in the plane

In this paper, we survey online algorithms in computational geometry that have been designed for mobile robots for searching a target and for exploring a region in the plane.