D. C. Tiwari

Lipopolysaccharide alters the vaginal electrical resistance in cycling and pregnant mice.

Problem  Lipopolysaccharide (LPS) has been postulated to exert harmful biologic effects during pregnancy. The objective of present investigation is to measure the vaginal electrical resistance (VER) in LPS‐treated normal cycling and pregnant female mice.

Electrocatalytic sensing of omeprazole

A novel, simple, sensitive, and highly selective omeprazole sensor based on the synergistic effect of polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs) has been developed. The morphology and electroanalytical performance of the fabricated sensor were characterized by scanning electron microscopy, square-wave voltammetry, and cyclic voltammetry. The influence of various parameters such as pH, effect of scan rate, and loading of PANI-MWCNTs hybrid film onto glassy carbon electrode (GCE) on electroanalytical performance of the developed sensor was investigated. The modified electrode showed an excellent electrocatalytic activity toward the reduction of omeprazole resulting in a considerable improvement of the peak current as compared to the electrochemical activity at the bare glassy carbon electrode. The incorporation of PANI with MWCNTs increased the peak current and electrochemical reactivity of omeprazole in comparison to that at the MWCNTs and PANI film. PANI-MWCNTs composites are expected to be a promising material for biosensing applications.

ORIGINAL ARTICLE: Lipopolysaccharide Alters the Vaginal Electrical Resistance in Cycling and Pregnant Mice

Problem  Lipopolysaccharide (LPS) has been postulated to exert harmful biologic effects during pregnancy. The objective of present investigation is to measure the vaginal electrical resistance (VER) in LPS‐treated normal cycling and pregnant female mice.

Nonlinear coupled transmission line analysis for second harmonic generation in traveling-wave GaAs MESFET's

A coupled nonlinear transmission line analysis for second harmonic generation from a traveling-wave field-effect transistor is presented. In the formulation, three main nonlinearities, namely the Schottky-barrier capacitance, the transconductance and the draincon-ductance, are considered. The coupled nonlinear differential equations are solved under a weak-coupling approximation with the help of the Weierstrassian elliptical function. It is observed that the second harmonic gain is significant afterx/l ≃ 0.7(wherelis the transverse length of the transistor). After this value of x, the amplitude at second-harmonic level increases sharply and follows almost a square-law behavior. It is found that the output drain conductance emerges as a large contributor to harmonic generation. The possibility of an image gate as drain conductivity modulator or phase velocity synchronizer is proposed. It is confirmed that travelling-wave MESFETs can also be used as harmonic generators.

NONLINEAR ANALYSIS OF DISPERSION FROM DOUBLE PERIODIC SEMICONDUCTOR GRATING

We have derived the dispersion relation for double GaAs semiconductor grating, using nonlinear boundary condition approach. The grating medium is assumed to non-magnetic and it has sinusoidal undulation of angular frequency ω on both side of the film. In the limit when plasma wavevector kp is greater than k‖ wavevector of the wave, we obtained two branches in the dispersion curve which corresponds to electrostatic charge disposition on the two sides of grating. In the limiting case kp < k‖, the grating radiate the electromagnetic field in the vicinity area.

The nonlinear-boundary-condition approach for the study of surface-plasmon dispersion in semiconductor gratings

A new nonlinear-boundary-condition approach for deriving the dispersion relation on the surface of GaAs grating structures is presented. We have used the linear set of wave equations and introduced the grating nonlinearities through the boundary conditions only. We have observed that the presence of a grating splits the surface-plasmon modes into two parts and generates a band gap. This approach is simple and, in the limiting case, reduces to well known theoretical calculations. The dispersion relation is solved for thin-film and thick-film gratings, in the limit in which the dielectric constant is less than zero. The results thus obtained may be used for millimetre waves and are also applicable to the optical region.

Surface polaritons in grating composed of left-handed materials

In this work, we developed a unique mathematical model to solve dispersion relation for surface polaritons (SPs) in artificial composite materials grating. Here, we have taken two types of materials for analysis. In the first case, the grating composed of epsilon-negative (ENG) material and air interface. In second case, grating composed of left-handed materials (LHMs) and ENG medium interface is considered. The dispersion curves of both p and s polarized SPs modes are obtained analytically. In the case of ENG grating and air interface, polaritons dispersion curves exist for p-polarization only, whereas for LHM grating and ENG medium interface, the polaritons dispersion curves for both p and s polarization are observed.

Polypyrrole and its composites with various cation exchanged forms of zeolite X and their role in sensitive detection of carbon monoxide

Composites of polypyrrole and various cation exchanged forms of zeolite X were successfully synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and thermo-gravimetric analysis (TGA). The effects of cation type, zeolite content, cyclic interval, and CO concentration on CO interactions with PPy were investigated. The sensitivity of the synthesized composites was found to obey the following order: Na+-X/PPy > H+-X/PPy > Fe+-X/PPy > Cu+-X/PPy > PPy depending upon the ionic radius of the cation present in the zeolite–polymer composites and the electronegativity. The sensitivity of the Na-X/PPy composite increased from 25.49% to 50.06% as the zeolite content was increased from 10% to 60% (w/w%). This increase in the sensitivity on increasing the zeolite content is due to the increase in the surface area of the composite. The sensitivity of Na-X/PPy at 500 ppm for CO was found to be 56.02, 50.28, 44.79 and 38.66% during the 1st, 2nd, 3rd and 4th cyclic intervals, respectively.

PEDOT: PSS: rGO nanocomposite as a hole transport layer (HTLs) for P3HT:PCBM based organic solar cells

This paper reports the fabrication process of organic solar cell (OSCs) having structure ITO/PEDOT:PSS:rGO/P3HT:PCBM/Al. In this cell, poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) is ultrasonically mixed with thermally reduced graphene oxide (rGO), which was used as a hole transport layer (HTLs). In order to investigate structural, morphological and optical properties of nanocomposite, XRD, FE-SEM and UV-vis spectroscopy were carried out. We have observed, Jsc = 6.5mA/cm2, Voc = 212 mV, FF=0.31 and PCE of 0.43% from fabricated organic solar cell.This paper reports the fabrication process of organic solar cell (OSCs) having structure ITO/PEDOT:PSS:rGO/P3HT:PCBM/Al. In this cell, poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) is ultrasonically mixed with thermally reduced graphene oxide (rGO), which was used as a hole transport layer (HTLs). In order to investigate structural, morphological and optical properties of nanocomposite, XRD, FE-SEM and UV-vis spectroscopy were carried out. We have observed, Jsc = 6.5mA/cm2, Voc = 212 mV, FF=0.31 and PCE of 0.43% from fabricated organic solar cell.

Sol-gel derived ZnO as an electron transport layer (ETL) for inverted organic solar cells

In this work, we present the study of the fabrication process of the sol-gel derived zinc oxide (ZnO) as an electron transport layer (ETL.). The solution processed inverted bulk heterojunction organic solar cells based on a thin film blend of poly (3-hexylthiophene 2, 5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester is prepared. ZnO thin films are annealed at different temperature to optimize the solar cell performance and their characterization for their structural and optical properties are carried out. We have observed Voc=70mV, Jsc=1.33 µA/cm2 and FF=26% from the inverted heterojunction solar cell.