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Alternating differential scanning calorimetric (ADSC) studies have been carried out on bulk Ge17Te83-xTlx glasses over a wide range of compositions (0 ≤ x ≤ 13), to estimate the thermal parameters and also to understand the effect of thallium addition on the non-isothermal crystallization process. It is found that glass transition temperature (Tg) decreases with increasing thallium concentration, indicating decrease in network connectivity with thallium addition. The decrease in Tg is large in the composition range 0 ≤ x ≤ 6 and much less for compositions x ≥ 7. The observed composition dependence of Tg is similar to the variation in switching voltages with composition and is in close agreement with the variation in the average bond energy. Further, two crystallization temperatures (Tc1 and Tc2) have been observed in Ge17Te83-xTlx glasses, in the composition range 2 ≤ x ≤ 10, which indicates that glasses in this range are phase separated. As these glasses are tellurium rich, it is probable that the regions formed by Te- chains crystallize first and the rest of the matrix crystallizes later. The change in enthalpy due to non-reversing part of the heat flow is very small and fairly constant over the entire range of glasses studied. This indicates that structural re-organization is easy in this system which agrees well with the memory type electrical switching observed in these samples.

Gd2O3 nanoparticles synthesized by solution combustion method were used to prepare PVA-Gd2O3 nanocomposite films of varying concentrations (2 wt%–6 wt% of filler) by solution casting method. Being a rare earth oxide, gadolinium oxide was expected to exhibit good photoluminescence and the nanocomposite was expected to be flexible as well. The Gd2O3 nanoparticles prepared were found to be in cubic phase with an average size of 19 nm. Raman spectra showed the incorporation of Gd2O3 into the polymer matrix. Scanning electron microscope images revealed that the particles were porous in nature, agglomerated and distributed evenly on the surface of the film in the form of clusters. The UV–Visible absorption spectra gave direct optical energy band gap value in the range 5.78–4.86 eV. Both band gap as well as the Urbach energy are seen to decrease with increasing concentration of the dopant. Four prominent photoluminescence peaks were observed in all the three composite films in the UV region (318 nm), deep blue region (396 nm), blue region (477 nm) and green region (553 nm). The color purity of the films using CIE coordinates was found to be the highest, 82.81%, in the 2 wt% film making this film a promising material for blue OLED’s and blue flexible screens.

Nanoparticles of Gd2O3 and Sm2O3 were prepared by solution combustion method. Nanocomposite films of PVA-Gd2O3 and PVA-Sm2O3 were prepared by solution casting method. These were characterized by XRD to give the nanocrystallite size as 19nm and 30nm respectively and to confirm the formation of a composite while TEM gave nano-particle size as 26nm and 37nm respectively. Both nanocomposites showed good photoluminescence. Impedance measurements showed that the conductivity decreased in the nanocomposites compared to PVA and that Correlated Barrier Hopping was the probable mechanism for conduction in both nanocomposite films. The fitting of the electric modulus to KWW equation indicated a non-Debye type of relaxation in both these films. The relaxation time decreased with increasing temperature in both nanocomposites.

Nanocomposite films of CeO2 doped polyvinyl alcohol (PVA) of varying concentrations were prepared by a solution casting technique using nanoparticles synthesized by a solution combustion method. Energy Dispersive X-ray (EDX) confirmed the presence of constituent elements in the composite films. The characterization by X-ray Diffraction (XRD) gave the structure of the CeO2 nanoparticles as cubic fluorite and the size of the nanoparticles in the composites as 6.5–44 nm. Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM) show homogenous dispersion of nanoparticles with increasing size and some agglomeration for concentrations upto 12.5 wt% while the 25 wt% film is radically different showing a tape-like structure in SEM images and a string of beads-like formation of nanoparticles in the HRTEM images. Raman spectra exhibit shifts as well as new bands in the composites confirming structural change and formation of a new material. The UV-Visible spectrum of the composites exhibit a red shift in the optical band gap with respect to pure PVA and both red and blue shift with respect to nano CeO2 depending on the concentration of the filler. Good absorption in the UV (2.5 wt% and 25 wt%) and visible range (12.5 wt% and 25 wt%) suggest possible use in filters and solar cells. Photoluminescence studies reveal three emission peaks corresponding to the UV region and blue–green regions of the visible range. The maximum PL intensity, nearly equal to that of nano CeO2, was observed for 2.5 wt% films suggesting that this concentration is most suitable for optoelectronic applications.

Concentration dependent dielectric and electrical properties of PVA-Gd2O3 nanocomposite films over a wide range of frequencies (100Hz-1 MHz) and temperatures (303 K–423 K) is reported here. TEM of the Gd2O3 nanoparticles showed that they could be indexed to the cubic phase. The frequency variation of the dielectric permittivity and dielectric loss could be explained by the Maxwell Wagner Sillar’s model. The dielectric permittivity decreased in the composite films contrary to observations in other similar systems. The complex impedance showed Arrhenius behavior and the activation energies decreased monotonically with increasing concentration. However the resistivity of the nanocomposite films shows an increase with concentration, the 4 wt% film showing the highest resistivity which indicates other contributions to conductivity. The Nyquist plot could be fitted to a simple parallel RC circuit showing the presence of long range conduction in these samples. The relaxation times varied from 10−4 to 10−6s and indicated a non-Debye type of relaxation. The master curve showed good overlap indicating that the same relaxation processes were active at all temperatures. The ac conductivity obeys Jonscher’s law and the exponent shows a monotonic decrease with temperature. This indicates that Correlated Barrier Hopping is the probable mechanism for conduction in these samples.

This paper have been discussed on Empowerment of Women in India covering variety of problems and issues, micro, macro and regional levels, and almost all general aspects of related to women empowerment have been studies by social sciences. Micro-nance has emerged as a powerful tool for women empowerment in the new economy. In India, micronance distribution is mainly dominated by Self Help Groups (SHGs). It aims at providing a cost effective mechanism for providing nancial services to the poor section of the society. As apparent from the preceding detailed discussion on the existing literature on the empowerment of women at different levels in India, attempts made so far suffer discerningly although with the following signicant limitations: (i) All the studies reveals a predominant bias of being macro level studies. Such studies by their very nature do not touch the core of reality, since it is not possible to know from the inner base of the mountain, the problem. The correct approach necessary is to dissect the problem into small pieces and then make an intensive effort to assess the reality; (ii) in the present development context in India; rapid changes are taking place on the economic scene, which bring in their trail, far reaching changes in the social, cultural, and political aspects of life. Therefore, even though a number of micro-studies existing, initiating of a new study in this area would have undiluted importance as such an attempt is bound to throw up several new facts in any empirical exercise having a bearing on policy issues. Thus, on its own, the necessity of a new micro study remains evergreen.

The variation of normalized electrical resistivity in the system of glasses Ge15Te85-xSnx with (1

The variation of electrical resistivity in the system of glasses Ge17Te83-xTlx, with (1

Graphical abstract: - Highlights: • ZnO nanoparticles were prepared by solution combustion method. • PVA–ZnO nanocomposites were synthesized by solution casting method. • Doped and undoped films were characterized using different techniques. • Red shift in optical band gap was observed in Nanocomposite films with respect to nano ZnO. • Photoluminescence intensity was found to be optimum for PVA–10 mol% ZnO nanocomposite film. - Abstract: Nanocomposites of poly vinyl alcohol (PVA) and ZnO have been synthesized using the solution casting technique for different concentrations of nano ZnO powder prepared by low temperature solution combustion method. The formation of polymer nanocomposite and changes in the structural and micro structural properties of the materials were investigated by X-ray diffraction, Energy dispersive X ray spectroscopy and optical microscopy techniques (FTIR and UV–Visible). The surface morphology of PVA–ZnO nanocomposite films were elucidated using Scanning Electron Microscopy. The optical absorption spectrum of nano ZnO shows blue shift in the optical band gap energy with respect to characteristic bulk ZnO at room temperature, whereas PVA–ZnO hybrid films show red shift with respect to nano ZnO. The photoluminescence studies show that the intensity of the blue emission (470 nm) varies with change in concentration of ZnO withmore » an optimum intensity observed at 10 mol% of ZnO.« less

Bulk Ge(17)Te83_,JI glasses (05x.5_13), have been found to exhibit memory type electrical switching. The switching voltages (also known as threshold voltage V-th) of Ge17Te83-xTlx glasses are found to decrease with increasing thallium content. The rate of decrease of Vtry is greater at lower concentrations and \textbackslashid, falls at a slower rate for higher thallium concentrations (x 6). The addition of thallium to the Ge-Te network fragments the covalent network and introduces ionic nature to it; the reduction in network connectivity leads to the decrease in switching voltages with thallium content. The decrease in the glass transition temperatures of Ge17Te83-xTlx glasses with increasing thallium concentration supports the idea of decrease in network connectivity with TI addition. The more metallic nature of TI also contributes to the observed reduction in the switching voltages of Ge17Te83-xTlx glasses with TI content. Further, there is an interesting correlation seen between the threshold voltage V-th and the average bond energy, as a function of TI content. In addition, the switching voltages of Ge17Te83-xTlx glasses have been found to decrease with sample thickness almost linearly. The set-reset studies indicate that the Ge17Te83-xTl2 sample can be switched for more than 10 cycles, whereas other glasses could not be reset beyond two switching cycles. (C) 2010 Elsevier B.V. All rights reserved.

The temperature variation of the nuclear quadrupole resonance frequency in the two compounds 3,4-dichloro nitrobenzene and 4-chloro 2 nitrophenol were analyzed in the light of the Kushida and Brown models. The internal torsional frequencies at each temperature was calculated using Bayer’s model with Tatsuzaki correction under a two-mode approximation to obtain the temperature variation of the torsional frequencies in both compounds. The torsional frequencies are seen to lie between 25 cm i1 and 85 cm i1 in the first compound and between 30 cm i1 and 42 cm i1 in the case of the second compound. The temperature dependence of the torsional frequencies is linear above 150 K in the first compound and is linear throughout the range 77 K to 350 K in the second. The smaller temperature dependence in the second compound may be the eect of hydrogen bonding in this compound. PACS numbers: 76.60 Gv

The temperature dependent 35Cl NQR data of 2,5-dichloro aniline was analysed using a two-mode approximation to yield the internal torsional frequencies in this compound. The torsional frequencies lie in the range 28-70 cm-1 and their temperature dependence is non-linear. The two modes obtained lie close to each other and the lower frequency mode obtained around 30 cm-1 agrees closely with the results obtained in similar compounds 2,6-dichloro aniline and 3,4-dichloro aniline. This mode can be identified with motion around an axis perpendicular to the ring.

The variation of resistivity in an amorphous As30Te70−x Si x system of glasses with high pressure has been studied for pressures up to 8 GPa. It is found that the electrical resistivity and the conduction activation energy decrease continuously with increase in pressure, and samples become metallic in the pressure range 1.0–2.0 GPa. Temperature variation studies carried out at a pressure of 0.92 GPa show that the activation energies lie in the range 0.16–0.18 eV. Studies on the composition/average co-ordination number ⟨ r⟩ dependence of normalized electrical resistivity at different pressures indicate that rigidity percolation is extended, the onset of the intermediate phase is around ⟨ r⟩=2.44, and completion at ⟨ r⟩=2.56, respectively, while the chemical threshold is at ⟨ r⟩=2.67. These results compare favorably with those obtained from electrical switching and differential scanning calorimetric studies.

The temperature variation of the nuclear quadrupole resonance frequencies in 3,4-dichloro-aniline and 2,6-dichloro-aniline were fitted to three different models available in literature, namely the Kushida model, the Brown model, and a fourth order polynomial. Brown's model with T0 = 205 K gave the best fit in the case of both compounds indicating that the temperature dependence of the torsional frequencies cannot be neglected in these compounds. The internal torsional frequencies were evaluated from the nuclear quadrupole resonance data by using a two-mode approximation in a temperature range of 77-300 K for the above two compounds. The torsional frequencies lie in a range of 30-60 cm -1 in both compounds and agree closely with the Raman lines obtained in 2,6-dichloro-aniline. The lower frequency mode around 37 cm-1 may be associated with the motion around an axis perpendicular to the benzene ring which is present in both compounds.

The variation in the electrical resistivity of the chalcogenide glasses Ge 15Te85-xInx has been studied as a function of high pressure for pressures up to 8.5GPa. All the samples studied undergo a semi-conductor to metallic transition in a continuous manner at pressures between 1.5-2.5GPa. The transition pressure at which the samples turn metallic increases with increase in percentage of Indium. This increase is a direct consequence of the increase in network rigidity with the addition of Indium. At a constant pressure of 0.5GPa, the normalized resistivity shows some signature of the existence of the intermediate phase. Samples recovered after a pressure cycle remain amorphous suggesting that the semi-conductor to metallic transition arises from a reduction of the band gap due to pressure or the movement of the Fermi level into the conduction or valence band.

The dielectric properties of polyvinyl alcohol (PVA) - zinc oxide (ZnO) hybrid nanocomposite films for different concentrations of nano ZnO (5 mol%-20 mol%) have been studied at ambient temperature in the frequency range 10 Hz-10 MHz. These studies indicate that the dielectric constant is maximum for 10 mol% ZnO-PVA hybrid film. An unusual low intensity loss peak is observed around 2.5-5 MHz in all the samples and this peak is more pronounced in the 10 mol% ZnO film. Impedance and modulus spectroscopy have been used to understand the dielectric and conductivity behaviour of these samples. These samples exhibit high bulk resistance and the Cole-Cole plot shows only the onset of the semicircles at room temperature. AC conductivity is found to obey Jonscher's power law and the enhancement in the conductivity is found to be highest for 10 mol% ZnO doped PVA nanocomposite film suggesting its suitability for use in sensing applications. The gas sensing performance of the hybrid films for detection of various gases such as NO2, H2S, NH3, LPG, and C2H5OH was studied and compared with that of pure PVA film. It was found that the hybrid sensor can complement the drawbacks of pure PVA as porous surface morphology and surface area of interface of nano-ZnO plays a vital role in sensing applications. At ambient temperature, 100 ppm concentration of both NO2 gas and H2S gas exhibit maximum response of 7.1% and 4.1% respectively for the 10 mol% hybrid sensor, whereas at 50 ppm concentration of H2S gas the 20 mol% ZnO-PVA sensor was found to be more sensitive with a reasonable response of 7%.

Photo-thermal Deflection (PTD) technique is used to investigate the thermal diffusivity (alpha) of Ge17Te83 - xTlx (0

Dielectric and conductivity behaviors of nano ZnO doped polyvinyl alcohol (PVA) composites for various concentrations of dopant were investigated using impedance spectroscopy for a wide range of temperatures (303 K–423 K) and frequencies (5 Hz–30 MHZ). The dielectric properties of host polymer matrix have been improved by the addition of nano ZnO and are found to be highly temperature dependent. Anomalous dielectric behavior was observed in the frequency range of 2.5 MHz–5 MHz. Increase in dielectric permittivity and dielectric loss was observed with respect to temperature. The Cole-Cole plot could be modeled by low resistance regions in a high resistance matrix and the lowest resistance was observed for the 10 mol. % films. The imaginary part of the electric modulus showed asymmetric peaks with the relaxation following Debye nature below and non-Debye nature above the peaks. The ac conductivity is found to obey Jonscher's power law, whereas the variation of dc conductivity with temperature was found to f...

Optimal labeling schemes lead to efficient experimental protocols for quantum-information processing by nuclear magnetic resonance (NMR). A systematic approach to finding optimal labeling schemes for a given computation is described here. The scheme is described for both quadrupolar systems and spin- ½ systems. Using the technique of transition selective pulses, one of the optimal labeling schemes has been applied to experimentally implement a quantum full adder in a four-qubit system by NMR.

We determine the nature of coupled phonons in mixed crystal of Cs-0.9(NH4)(0.1)H2AsO4 using inelastic light scattering studies in the temperature range of 5 K to 300 K covering a spectral range of 60-1100 cm(-1). The phase transition in this system are marked by the splitting of phonon modes, appearance of new modes and anomalies in the frequency as well as linewidth of the phonon modes near transition temperature. In particular, we observed the splitting of symmetric (v(1)) and antisymmetric (v(3)) stretching vibrations associated with AsO4 tetrahedra below transition temperature (T-c(*) similar to 110 K) attributed to the lowering of site symmetry of AsO4 in orthorhombic phase below transition temperature. In addition, the step-up (hardening) and step-down (softening) of the AsO4 bending vibrations (v(4) (S9, S11) and v(2) (S6)) below transition temperature signals the rapid development of long range ferroelectric order and proton ordering. The lowest frequency phonon (S1) mode observed at similar to 92 cm(-1) shows anomalous blue shift (similar to 12 %) from 300 K to 5 K with no sharp transition near T-c(*) unlike other observed phonon modes signaling its potential coupling with the proton tunneling mode. (C) 2013 Author(s).

A cw nuclear quadrupole resonance spectrometer centered on the superregenerative oscillator and working in the range 20–40 MHz is described. Both automatic gain control and sideband suppression have been incorporated by using external quench waveforms of variable mark-to-space ratio. Extensive use of ICs in these circuits leads to ease of construction as well as increased reliability. The S/N obtained remains unaffected by the automatic gain control while the sideband suppression does give rise to a small degradation. The spectrum of $NaClO_3$ has been recorded. Review of Scientific Instruments is copyrighted by The American Institute of Physics.

The NMR spectra of oriented molecules increase in complexity with the number of coupled sins. It is shown that two-dimen-sional correlated spectroscopy provides a powerful technique for “filtering” the spectra of symmetric oriented molecules into their component irreducible representations, thereby considerably aiding the analysis of such spectra. This is demonstrated for two six-spin systems, acetone and benzene, oriented in the nematic phase.

The chlorine-35 NQR frequencies and their temperature variation in 2,4,6-, 2,3,6- and 2,3,4-trichloro anisoles have been studied and compared with the corresponding chlorophenols with a view to studying the effect of hydrogen bonding. The observed frequencies have been assigned to the various chlorines with the help of the additive model of the substituent effect. The temperature dependence has been analysed in terms of the Bayer—Kushida—Brown models. The torsional frequencies and their temperature dependence have been calculated numerically under a two mode approximation. A comparison of the trichloro anisoles with the corresponding trichloro phenols has shown that the resonance frequency decreases due to hydrogen bonding while the torsional frequencies are not affected.

Difference nuclear Overhauser effect (NOE) experiments on oriented acetone and 2,1, 3-benzoselenadiazole, containing $A_3A'_3$ and AA'BB' spin systems, respectively, show that in the case of the former, NOE transfer is restricted to within a given irreducible representation while in the case of the latter, transfer from symmetric to antisymmetric representation does occur. Two possible mechanisms of relaxation in such systems, the intramolecular dipole-dipole and the external random field, were investigated and it was seen that in general the dipole-dipole mechanism does not restrict NOE transfer to a given representation. However, special geometry could restrict NOE transfer to transitions of the same representation. On the other hand a fully correlated external random field does restrict NOE transfer to one representation. Detailed theoretical calculations of the NOE in AA'BB' show good fit with the experiment for $\omega {\tau}_m \sim 2.0.$

The temperature variation of the 3’Cl n.q.r. frequencies in 3,5- and 2,3- dichloroanisoles has been reported here. Both compounds show two lines each, and these have been assigned to the two chlorines in the same molecule with the help of the additive model for the substituent effect. The temperature dependence has been analysed in terms of Bayer-Kushida-Brown model.The torsional frequencies and their temperature dependence have been calculated numerically under a two-mode approximation. 0.n comparing the results in 3,5-dichloroanisole with those in 3,5-dichlorophenol it can be seen that they show similar behaviour owing to the absence of hydrogen bonding in both.