Doping effect of viologen on rectification, charge transport processes and photovoltaic properties of furazano (3,4-b)piperazine thin film device

The electrical and photoelectrical properties of a sandwich junction device based on allyl viologen (AV)-doped furazano (3,4-b)piperazine (FP) having structure ln/AV : FP/ITO have been reported. A significant enhancement in the rectification, dark conductivity and photovoltaic response has been observed in AV-doped FP devices compared with undoped FP devices. The present communication deals with the charge transport mechanism and photogeneration process in ITO/AV doped FP/ln Schottky devices. The J–V characteristics recorded in the dark show a rectification effect due to the formation of a barrier at the AV-doped FP/ln interface. Impedance spectroscopy has been used to study the charge transport mechanism for AV-doped FP and its interface with ln. The bulk and junction resistance along with capacitance were determined by analyzing their contribution at an individual level. Doping imparts an improvement in photoresponse of FP as well as an abundance of photoexcited species at the interface. © 2001 Kluwer Academic Publishers     

Polyoxometalate impregnated carbon systems for the in situ degradation of sulphur mustard

Kinetics of in situ degradation bis-(2-chloroethyl) sulphide (sulphur mustard, HD) on polyoxometalate impregnated carbon systems such as 11-molybdo-1-vanadophosphoric acid (V₁/C), phosphotungstic acid (PTA/C), sodium phosphotungstic acid (PTANa/C), phosphomolybdic acid (PMoA/C), sodium phosphomolybdic acid (PMoANa/C) and silicotungstic acid (SiTA/C) have been studied. These carbons were characterized for micropore volume and surface area by N₂ Brunauer, Emmett and Teller (BET) equation. For degradation studies the solution of HD in chloroform was prepared and taken for the uniform adsorption on the carbon systems using incipient volume. Degradation kinetics was monitored by gas chromatograph equipped with flame ionization detector (GC/FID) and found to be following the pseudo first order kinetics. The values of kinetic rate constant and half-life were calculated. V₁/C system showed the fastest degradation of HD. Hemimustard, thiodiglycol, 1,4-oxathiane, sulphoxide and vinyl-2-chloroethyl sulphide were found to be the degradation products with V₁/C system which indicated the oxidative, hydrolytic and dehydrohalogenation reactions, responsible for HD degradation. Effect of moisture was also studied on most reactive system, i.e., V₁/C. The study indicated that V₁/C can be used as a promising adsorbent system for the degradation of HD.     

Feeding responses ofChilo partellus (Swinhoe) (Lepidoptera: Pyralidae) larvae to sorghum plant phenolics and their analogs

Phagostimulatory responses of third-instar larvae ofChilo Partellus to phenolic components identified in an ethyl acetate extract of the leaf whorls of 3-week-old plants ofSorghum bicolor cultivar IS 18363 were studied in no-choice bioassays. The major components in the extract were identified as 4-hydroxybenzaldehyde and 4-hydroxybenzoic acid, with 4-hydroxy-3-methoxycinnamic acid, 3,4-dihydroxycinnamic acid, and 4-hydroxycinnamic acid present in minor amounts. All but 4-hydroxycinnamic acid were stimulatory at the doses tested. 4-Hydroxybenzaldehyde was more stimulatory than other potential biogenetic analogs. Hydroxybenzoic acids generally elicited greater feeding response than cinnamic acids, and the pattern of oxygen substitution in the benzene ring was related to bioactivity.     

Detection of micron size phantom of biological cell using concentric square ring metamaterial at microwave frequency

ABSTRACT

This paper presents simulation studies and theoretical analysis of sensing property of concentric square ring metamaterial biological materials. Phantom of dielectric cell having dimension 100 µm long and 25 µm in radius is considered. Sensor is designed using periodic arrays of split ring resonators and wires having negative permittivity and permeability at 16.694 GHz. Transmission parameters are extracted using CST MWS software. Change in resonance is observed on placing phantom close to the sensor due to the change in capacitance and inductance. Designed sensor can sense single phantom cell with 133 MHz of shift in resonance. Study shows that sensor has good sensitivity for detecting micron size dielectric objects.     

Qualitative Evolution of Asymmetric Raman Line-Shape for NanoStructures

A qualitative evolution of an asymmetric Raman line-shape function from a Lorentzian line-shape is discussed here for application in low dimensional semiconductors. The step-by-step evolution reported here is based on the phonon confinement model which is successfully used in literature to explain the asymmetric Raman line-shape from semiconductor nanostructures. Physical significance of different terms in the theoretical asymmetric Raman line-shape has been explained here. Better understanding of theoretical reasoning behind each term allows one to use the theoretical Raman line-shape without going into the details of theory from first principle. This will enable one to empirically derive a theoretical Raman line-shape function for any material if information about its phonon dispersion relation, size dependence, etc., is known.     

Auto-configuration of Physical Cell ID in LTE femtocellular systems using Self Organizing Networks

The commercial success of cellular networks, combined with advances in digital electronics, signal processing, and telecommunications research have lead to the design of next generation 4G-based long term evolution (LTE) wireless systems. The key essence of these emerging, LTE cellular systems lie in deployment of multiple femtocells for improved coverage and higher data rates. However, the arbitrary deployment of a wide number of femtocells makes the configuration, management and planning of LTE systems quite complex and challenging. In order to support dynamic and efficient network configuration, every cell needs to be assigned a particular Physical Cell ID (PCID). In this paper we show that the dynamic, optimal PCID allocation problem in LTE systems is NP-complete. Subsequently we provide a near-optimal solution using Self-Organizing Networks which models the problem using new merge operations and explores the search space using a suitable randomized algorithmic approach. We also discuss two feasible options for dynamic auto-configuration of the system and analyze the algorithm to prove its convergence. Simulation results point out that our proposed near-optimal solution dynamically achieves ～85?90 % of global optimal auto-configuration in computationally feasible time.