Synthesis,Physicochemical and Optical Characterization of Novel Fluorescing Complex: <Emphasis Type="Italic">o</Emphasis>-Phenylenediamine—Benzoin

The complex of o-phenylenediamine (o-PDA) and benzoin (BN) was synthesized adopting solid state reaction by mixing of their melt together followed by chilling. The phase diagram study shows the formation of a complex in 1:1 molar ratio with congruent melting point and two eutectics lying on either side of complex. The formation of complex was confirmed using the FTIR, NMR, mass spectroscopy, powder XRD and DSC studies. The optical properties of the parent component, their complex and few other compositions nearby the complex were studied using absorption and laser luminescence techniques. The significantly higher green/yellow emission was noted with newly synthesized complex as compared to that of their parents as well as other compositions of o- PDA and BN.     

Plasmonic modulator utilizing three parallel metal-dielectric-metal waveguide directional coupler and elasto-optic effects

We report, for the first time, on the design of a plasmonic modulator working on the principle of the elasto-optic effects in a directional coupling structure, utilizing three parallel metal-dielectric-metal waveguides. We propose to achieve the active switching of the power propagation using the elasto-optic effect and optimize the extinction ratio of the optical modulation. The device is characterized and numerically analyzed using the finite-element-method at the wavelengths of 1.55 μm. For the modulator length of 2.33 μm, the extinction ratio of the modulation is nearly 14 dB, and the calculated attenuation loss is 4.5 dB. The calculated driving voltage is 4.8 V for the given modulator. The effect of the applied voltage on the modulation is also analyzed.     

Correlation of sp and sp fraction of carbon with electrical, optical and nano-mechanical properties of argon-diluted diamond-like carbon films

In the present work the correlation of electrical, optical and nano-mechanical properties of argon-diluted diamond-like carbon (Ar-DLC) thin films with sp³ and sp² fractions of carbon have been explored. These Ar-DLC thin films have been deposited, under varying C₂H₂ gas pressures from 25 to 75 mTorr, by radio frequency-plasma enhanced chemical vapor deposition technique. X-ray photoelectron spectroscopy studies are performed to estimate the sp³ and sp² fractions of carbon by deconvoluting C 1s core level spectra. Various electrical, optical and nano-mechanical parameters such as conductivity, I-V characteristics, optical band gap, stress, hardness, elastic modulus, plastic resistance parameter, elastic recovery and plastic deformation energy have been estimated and then correlated with calculated sp³ and sp² fractions of carbon and sp³/sp² ratios. Observed tremendous electrical, optical and nano-mechanical properties in Ar-DLC films deposited under high base pressure conditions made it a cost effective material for not only hard and protective coating applications but also for electronic and optoelectronic applications.     

Study of structural and dielectric behaviour on carbon nano tube dispersed {xPVF: (1 − x)CH3COONH4} electrolyte

In the present work, improvement in ion transport property of polyvinyl formal (PVF)-based nanocomposite polymer electrolytes has been studied upon dispersal of multiwall carbon nanotube (MWCNT) filler. Nanocomposite polymer electrolyte (NCPE) films of xPVF: (1 ? x)CH₃COONH₄ (ammonium acetate) were prepared by solution cast technique. The formation of nanocomposite has been ascertained by X-ray diffraction (XRD) pattern, which also shows that doping of salt increases amorphousness through polymer salt complexation. Changes in surface morphology have been observed in optical microscopy and Scanning Electron Microscopic (SEM) images. Variation of dielectric constant, dielectric loss, tangent loss and modulus spectra with the change in frequency and temperature were studied with the aid of impedance spectroscopy.     

Ambient UVA‐Induced Expression of p53 and Apoptosis in Human Skin Melanoma A375 Cell Line by Quinine

This study aimed to analyze the phototoxic mechanism and photostability of quinine in human skin cell line A375 under ambient intensities of UVA (320–400 nm). Photosensitized quinine produced a photoproduct 6‐methoxy‐quinoline‐4‐ylmethyl‐oxonium identified through LC‐MS/MS. Generation of ¹O₂, O₂^??, and ^?OH was measured and further substantiated through their respective quenchers. Photosensitized Quinine (Q) caused degradation of 2‐deoxyguanosine, the most sensitive nucleotide to UV radiation. The intracellular ROS was increased in a concentration‐dependent manner. Significant reduction in metabolic status measured in terms of cell viability (54%) at 25 μg mL^?1 was observed through MTT assay. Results of MTT assay accord NRU assay. Single strand DNA breaks and apoptosis were increased significantly (P < 0.01) as observed through comet assay and EB/AO double staining. Photosensitized quinine caused cells to arrest in G₂ phase of cell cycle and induced apoptosis (5.08%) as revealed through FACS. Real‐Time PCR showed upregulation of p21 (4.56 folds) and p53 (2.811 folds) genes expression. Thus, our study suggests that generation of reactive oxygen species by quinine under ambient intensity of UVA may result into deleterious phototoxic effects among human population.     

Composition dependence of photoconductivity in amorphous thin films of Se70Te30−xSbx

Summary The present paper reports the composition dependence of steady-state and transient photoconductivity in amorphous thin films of Se₇₀Te_30-xSb_x, wherex is varied from 0 to 10. The results indicate that photoconductivity is highly composition dependent in this system and a discontinuity in various electrical parameters is observed at 4 at. % of Sb. This is explained in terms of increased disorder up to 4 at. % of Sb. However, at higher concentration of Sb, an ordered structure may be established due to the formation of microcrystalline phases as observed in X-ray diffraction patterns.     

Amorphous-to-crystalline transition in Ge22Se78−x Bi x system

Summary Crystallization kinetics is studied in glassy Ge₂₂Se_78−x Bi _x (0≤x≤10) using isothermal annealing at various temperatures between the glass transition and melting. D.c. conductivity is taken as a parameter to estimate the extent of crystallization (α). The activation energy of crystallization (ΔE) and the order parameter (n) are calculated by fitting the values of α in Avrami’s equations of isothermal transformation. The results indicate that ΔE is highly composition dependent and decreases as the Bi concentration increases.     

Four decades of nuclear tracks research in India

The science of solid state nuclear track detectors (SSNTDs)—“Trackology”—developed by R.L. Fleischer, P.B. Price and R.M. Walker in the early 1960s of the last century is an interesting and potentially useful concept with something to offer to almost all branches of science and technology. In fact nuclear tracks find applications wherever solid state damage occurs. Apart from the direct applications of far reaching consequences in nuclear physics, other areas as diverse as bio-medical sciences, cosmic rays and space physics, environmental research, geological sciences, material science, microanalysis, mine safety, nuclear technology, uranium prospecting, etc. have been greatly influenced by SSNTDs.

In this presentation, we attempt to provide an overview of the growth of nuclear tracks research in India over the last four decades and the contributions of various groups from Universities, Institutes, Nuclear Track Society of India and the Department of Atomic Energy in nurturing nuclear track research in the country. Finally, a summary of the significant contributions made by Indian scientists is also presented in this paper along with the overall impact it has made at the national and international level in many areas of basic and applied sciences such as cosmic rays and space physics, fusion–fission and particle evaporation, heavy ion ranges and energy-loss measurements, country-wide indoor radon–thoron survey, geochronology, environmental sciences, track-etch membranes and ion tracks technology, material science, physics and chemistry of fission, etc.     

Gamma effect on track properties of PADC detector

Effect of high gamma irradiation on track properties of PADC (Homalite) has been studied in the dose range of 10¹–10⁶ Gy. The properties like bulk-etch rates and track-etch rates of the detector are found to increase due to gamma exposure. Etching efficiency of the detector increases due to exposure and it is significant at the dose higher than 10³ Gy. Another track property, the critical angle, is also influenced by gamma exposure and is found to decrease with increasing dose. In all cases it is observed that the post-gamma exposure has greater effect than the pre-gamma exposure. The experimental results are presented and discussed in details.