Tellurium-rich Bi2Te3 thin films are deposited by electron-beam evaporation technique at 300 K. These as-deposited thin films are further annealed at 100 degrees C, 200 degrees C and 300 degrees C for 1 h at a pressure of 3 x 10(-4) Pa. X-ray diffraction (XRD) patterns of as-deposited films distinctly show Te phase along with Bi2Te3. Peak intensity ratio suggests the polycrystalline nature of as-deposited Bi2Te3 films. On vacuum annealing Te-rich Bi2Te3 films exhibit improved crystallinity with a c-axis preferred orientation. In addition, structural features related to Te and Bi2Te3 composition change with Te fraction diminishing on annealing at 300 degrees C. From Raman spectral studies, the presence of distinct Te-rich regions, predominantly within the interlayers of Bi2Te3, are discerned. Te becomes structurally integrated within the quintuples of Bi2Te3 lattice as intergrown layers. Disordered planar structures, mostly concentrated on crystallite surfaces result from Te accumulations as evidenced in high-resolution transmission electron microscopy lattice images and energy dispersive X-ray spectroscopy mapping. These are consistent with the observations from XRD and Raman studies further confirming Te-rich Bi2Te3 characteristics. Electrical properties of Te-rich Bi2Te3 thin films exhibit n-type semiconductor behaviour. Seebeck coefficient for as-deposited film is similar to 32 mu V/K, which increases to similar to 97 mu V/K on 200 degrees C annealing. Resistivity increases from 1.39 x 10(-4) Omega cm to 18.76 x 10(-4) Omega cm and power factor changes from 7.4 x 10(-4) W/K(2)m to 27.17 x 10(-4) W/K(2)m going through a maximum at 200 degrees C upon systematic annealing. Terich Bi2Te3 thin films annealed at 200 degrees C exhibit high power factor (similar to 29 x 10(-4) W/K(2)m) for a wide range of temperature gradients ( Delta T from 30 degrees C to 165 degrees C).

The effect of variant high boiling point solvent combinations in the synthesis and photo-sensing characteristics of tin disulfide (SnS2) thin nanosheets were investigated.

The effect of microbe combination with TiO 2 on photocatalytic degradation of Rhodamine B was investigated. The self-assembled TiO 2 spheres were synthesized by the solvothermal method for preparation of hybrid TiO 2 /Paint Sludge Extracted Microbe (PSEM) composite. The structure of as-synthesized TiO 2 was analyzed by the powder X-ray diffraction method, and phase purity was verified with Raman analysis. Spherical morphology and self-assembled nature of TiO 2 was confirmed by field emission scanning electron microscopy (FE-SEM). PSEM extracted from Paint sludge and was used to synthesize TiO 2 /PSEM hybrid composite. The dispersion of TiO 2 self-assembled spheres on the walls of PSEM was confirmed with FE-SEM micrographs. TiO 2 /PSEM composite (94%) showed enhanced photocatalytic dye degradation when compared with as-synthesized TiO 2 (85%).

A simple, biocompatible and an enzyme-free sensing platform was developed for detection of paraoxon. The surface of a glassy carbon electrode was modified with an electrodeposition of stearic acid/nanosilver composite at -0.7 V for 40 s. The paraoxon undergoes electro-reduction at -550 mV on the modified electrode, and the limits of detection (LOD) was calculated as 0.1 nM (S/N = 3) using differential pulse voltammetry which is lower than that of the existing materials reported. The high stability observed with the modified electrode for prolonging period indicated that the sensitivity of the electrode remains active for several runs of the analysis. The developed analytical strategy was implemented for onion and paddy grain samples and good recovery rates were observed. Also, it was applied for analyzing the purity of the commercial paraoxon sample. The reliability of the developed strategy was confirmed by comparing the results of electrochemical approach with that of HPLC technique.

Bi-rich Bi2Te3 thin films are prepared at 300 K using e-beam evaporation technique. A source power of 45 W for e-beam is used. Post deposition, these as-deposited Bi-rich Bi2Te3 (Bi-BT-AD) films are annealed at 100 degrees C (Bi-BT100), 200 degrees C (Bi-BT-200) and 300 degrees C (Bi-BT-300) for 1 h under a pressure of 3 x 10(-4) Pa. X-ray diffraction measurements reveal the presence of Bi phase together with crystalline Bi2Te3 indicating the possible presence of Bi-rich Bi2Te3 phase in the Bi-BT-AD film. The broad peaks from Bi2Te3 (015) plane indicate nanocrystalline nature of particles. With annealing, no change in diffraction pattern is observed for Bi-BT-100. However, Bi-BT200 and Bi-BT-300 films show the emergence of x-ray reflection from unknown phases around 20 - 20 degrees and 47 degrees. This indicates Bi related secondary phase segregation and the thermodynamic instability for the presence of Bi in Bi2Te3 lattice. From Raman studies it is discerned that Bi secondary phase coexists along with the Bi-rich Bi2Te3 nanocrystalline grains. On vacuum annealing Bi-rich Bi2Te3 phase in thin films prevails as evidenced from the ptype electrical characteristics, while excess Bi disappears and converts into an unknown minor phase. The resistivity of all the annealed films are - 0.9 x 10(-4) Qcm. The Seebeck coefficients also do not show any change and remain around 33 to 36 mu V/K. Thermoelectric properties of Bi-BT-100 exhibit high power factors when measured at different AT with a maximum of - 17.5 x 10(-4) W/K(2)m for AT = 100 degrees C. Thus, unlike the nearstoichiometric thin films, Bi-rich thin films require low temperature annealing (similar to 100 degrees C) to achieve optimized parameters. Bi-rich Bi2Te3 thin films also show higher power factor compared to the near-stoichiometric thin films. Thus, favourable thermoelectric properties can be achieved at 300 K for temperature sensitive device fabrication using Bi-rich Bi2Te3 thin films.

Cadmium Sulphide (CdS) nanoparticles were incorporated in PEO matrix. No capping agent was used other than the polymer to reduce the size of the CdS particles. The optical properties of the CdS:PEO nanocomposites were analysed and the transmittance of the solid films was found to be above 80%. The structural analysis of the nanocomposites was carried out using Transmission Electron microscope (TEM) and Atomic force microscope (AFM) and the particle size variation for different concentrations of CdS:PEO nanocomposites and the size distribution of CdS particles incorporated in the polymer matrix was analysed. The thermal properties of CdS:PEO nanocomposites were analysed using Differential scanning Calorimetry (DSC). The melting point shift of PEO matrix and the thermal stability of the matrix after incorporating CdS were found.

Cadmium Sulphide nanoparticles were reinforced in PEO matrix and their functional group was analysed. FTIR-ATR spectroscopic studies were carried out for different concentrations of CdS: PEO nanocomposites. The results revealed the complexion of CdS with PEO in the matrix. The nature of bonding between CdS and PEO was analysed with the help of relative intensity ratio of prominent peaks from FTIR. Also the strongest C-O-C stretching ether group absorption of PEO with composites was analysed to ensure the bonding nature of PEO with CdS.

The optimisation of DC plasma process towards maximising the fabric's hydrophilicity using Design-Expert 7.0.0 software has been reported in this paper. Out of various designs available, the Box-Behnken design was adopted for this purpose. The process parameters considered for optimisation were pressure of the gas (commercial grade air) used to produce plasma, DC current and the time for which the fabric was exposed to the plasma. These were keyed in as the three input parameters and the corresponding measure of hydrophilicity was fed as the response. Analysis of Variance (ANOVA) of the model and an associated discussion on the basis of Langmuir probe analysis, Physical analysis and ATR-FTIR analysis has been reported. The response predicted by the model was in good agreement with that obtained through experiment.

Optical and energy storage materials based on semiconductors are of great interest today. The present report explains the semiconductor nanocomposite centered on highly transparent Poly(methyl methacrylate) (PMMA) matrix and Cadmium Sulphide (CdS) nano particles. The solid films of CdS:PMMA composite was prepared using simple and cost effective solution casting technique. The surface morphology and the presence of CdS particles in PMMA matrix was analysed using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectra (EDX). The size of the particles was analysed using Atomic Force Microscopy (AFM) and Transmission Electron Microscope (TEM) and they revealed the presence of nano sized particles. The narrow size distribution of particles was identified from TEM and AFM analysis. The transmittance of the CdS:PMMA nanocomposite solid films was found to be above 90%. The blue and green emission of CdS:PMMA nanocomposite solid films were observed from Photoluminescence (PL) spectra.

Gadolinium doped barium cerate (BCG) electrolytes Ce0.8Gd0.2O1.9 + xBaO (x = 0.1 and 0.4) were prepared by wet chemical method for the use in solid oxide fuel cells operating at intermediate temperatures (600 degrees C to 800 degrees C). The as-prepared powder sample was calcined at 900 degrees C. The calcination temperature was identified using differential scanning calorimetry (DSC) analysis. The orthorhombic perovskite phase formation was confirmed by XRD analysis. From TEM results, the particle size was found to be about 32 nm which is in a good agreement with XRD results. BCG nanoparticles were formed at lower sintering temperature due to using microwave furnace. By reducing the sintering temperature of solid electrolyte through microwave technique, the percentage of barium loss was successfully reduced and the prepared electrolyte can be a good choice for solid oxide fuel cells operating at intermediate temperatures.

Structural, thermal, electrical and electrochemical behaviour of polymer blend electrolytes comprising polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) as host polymers and Mg(ClO4)2 as dopant salt have been investigated. The changes in the structural properties on the incorporation of dopant in the blends were investigated by XRD and FTIR analyses. Thermal properties of pure PVA–PVP blend and their complexes were examined by DSC to measure how the thermal transitions of the prepared films were affected by different concentration of Mg(ClO4)2. The ionic conductivity and dielectric behaviour were explored using A.C. impedance spectroscopy. The trend of ionic conductivity increases almost proportionally to the content of magnesium salt and can be related to an increase of amorphous phase at high level of dopant salt. The electrochemical stability of the optimum conducting blend polymer electrolyte is found to be ∼3.5 V. The Mg2+ transference number for the sample with optimized conductivity was found to be 0.31.

Solid oxide fuel cells (SOFCs) have attracted a great deal of consideration among the promising fuel cell systems for energy conversion. In SOFC, electrolyte plays a vital role to increase the energy conversion efficiency. The main hurdle is its higher operating temperature (1000 degrees C) which results in design limitation and higher fabrication cost. In this work, Gadolinium Doped barium cerate (BCG) composite electrolyte was successfully synthesized to operate at intermediate temperature (600-800 degrees C) by co-precipitation technique. The structure of BCG was identified as orthorhombic perovskite and the crystallite size was found to be around 30 nm. From TEM, the particle size was found to be 32nm and is in good agreement with XRD results. Further, the particles sizes were found to be uniform in size and shape. From the above results it is understood that the obtained particle is a single crystallite which indicates the absence of agglomeration. The formations of BCG nanoparticles were resulted in reduced sintering temperature of the electrolyte. By lowering the sintering temperature, the barium loss was successfully reduced in order to get the required orthorhombic perovskite phase. The lower activation energy was found for BCG composite electrolyte, which can acts as a best electrolyte for at intermediate temperature applications.

In the present investigation Samarium doped barium cerate electrolyte powder of (1-x)Ce(0.2)Sm0(.2)O(2-delta) - xBaCe(0.8)Sm(0.2)O(3-delta) (where x = 0.1 mol fraction) stoichiometry formula is successfully synthesized through wet chemical route. A SDC-BCS nanocomposite electrolyte is premeditated with respect to its thermal, structural, morphological properties and conductivity performance. The crystal structure and microstructure of the SDC-BCS composite is investigated from XRD and SEM analysis. TG analysis reveals that the calcination temperature (900 degrees C) of the as prepared powder sample. The crystal structure of as prepared SDC-BCS composite powder is identified as cubic perovskite with orthorhombic distortions occurred at 900 degrees C. From TEM analysis, the particle size is found to be around 32 nm. SEM analysis reveals that the existence of dual phase microstructure in the composite at 1400 degrees C. The preparation of dense SDC-BCS nanocomposite with the development of dual phase microstructure is achieved for the better ionic conductivity in SDC-BCS nanocomposites for SOFC application. (C) 2017 Elsevier B.V. All rights reserved.

Nanocrystalline thin films of a V-VI compound Bi2Te3 are fabricated with uniform thickness by e-beam evaporation at room temperature. The as-deposited films are stoichiometric, monophasic, highly strained and polycrystalline. We studied the effect of vacuum annealing (at a pressure of ~3×10−6mbar) on composition, structure, optical and electrical properties of these films. It is observed that, as the annealing temperature increases (from 100°C to 300°C), the crystallites grow with a preferential orientation along (110) planes with slight increase in the crystallite size from ~14nm to 30nm. This is associated with the breaking of quintuple layers and rearrangement of crystallographic planes in the crystallites with Te rich surface emerging on vacuum annealing as evidenced from the XRD, Raman and high-resolution TEM studies. The direct bandgap (0.116eV) of as-deposited Bi2Te3 changes from 0.092eV to 0.113eV on annealing at 100°C to 300°C, respectively. Interestingly, we observe a gradual change from a semiconductor to metallic behavior on annealing the samples from 100°C to 300°C. Such a transition from negative temperature coefficient (NTC) to positive temperature coefficient (PTC) is seen mainly due to the percolation of Te - rich crystallite surfaces, which evolve as the annealing temperature increases. While the films annealed at 200°C and 250°C shows a broad semiconductor to metallic transition at ~150K and 200K respectively, the thin films annealed at 300°C are found to exhibit complete metallic behavior below room temperature. The electrical property and Seebeck coefficient studies with power factors in the range of ~4 to 12×10−4W/K2m for films annealed above 200°C suggest that the vacuum annealed Bi2Te3 thin films are favorable for thermoelectric applications.

Polymer electrolytes comprising polyvinyl pyrrolidone (PVP) as host polymer and Mg(ClO4)2 as dopant salt have been prepared by solution casting technique using double-distilled water as solvent. The changes in the structural properties on the incorporation of dopant were investigated by XRD and FTIR analysis. The ionic conductivity and dielectric behavior were explored using AC impedance spectroscopy. The ionic conductivity increases with increasing dopant concentration. The conductivity enhancement with the increasing salt concentration is correlated with the increase in amorphous nature of the electrolytes. The frequency dependence of electrical conductivity obeys the universal Jonscher power law. The electrical modulus representation shows a loss feature in the imaginary component. The distribution of relaxation times was indicated by a deformed arc form of the Argand plot. The relative dielectric constant (ε r ) decreases with increase in frequency in the low frequency region whereas a frequency-independent behavior is observed in the high frequency region. The total ionic transference number studies have confirmed that the mobile charge carriers are ions. Results obtained by cyclic voltammetry on SS/60 mol% PVP/40 mol% Mg(ClO4)2 SPE/SS symmetrical cell show evidence for reversibility.

ABSTRACT Magnesium ion-conducting solid polymer electrolytes consisting of polyvinyl alcohol with magnesium perchlorate (Mg(ClO4)2) as electrolytic salt have been developed and their experimental investigations are reported. The solid polymer electrolytes have been prepared by well-known solution casting method using double-distilled water as a solvent. The highest room temperature conductivity of the order of 10−4 S cm−1 was obtained for the solid polymer electrolyte with the composition 80 mol% polyvinyl alcohol:20 mol% Mg(ClO4)2. The pattern of the temperature-dependent conductivity shows Arrhenius behavior. The Fourier transform infrared spectroscopy analysis confirms the complex formation of the polymer with the salt. The X-ray diffraction results reveal that the crystalline phase of polymer host has completely changed on the addition of dopant. Differential scanning calorimetry studies show a decrease in melting temperature of the polyvinyl alcohol with the increasing dopant concentration. The real part of dielectric permittivity shows a strong dispersion at lower frequencies, which implies the space charge effects arising from the electrodes. The loss tangent spectrum reveals that the jumping probability per unit time decreases with the increasing salt concentration. The total ionic transference number measured has been found to be in the range of 0.92–0.94 for all the polymer electrolyte systems. The result reveals that the conducting species are predominantly ions. The solid polymer electrolyte with highest conductivity showed an electrochemical stability of 2 V. The results obtained by cyclic voltammetry on stainless steel/solid polymer electrolyte/stainless steel, Mg/solid polymer electrolyte/Mg symmetrical cells show evidence for reversibility. GRAPHICAL ABSTRACT

The aim of this article is to assess Tamil Nadu pediatric computed tomography (CT) diagnostic reference levels (DRLs) by collecting radiation dose data for the most commonly performed CT examinations. This work was performed for thirty CT scanners installed in various parts of the Tamil Nadu region. The patient cohort was divided into two age groups: <1 year, and 1-5 years. CT dose indices were measured using a 10 cm3 pencil ion chamber with pediatric head and body polymethyl methacrylate phantoms. Dose data such as volumetric CT dose index (CTDIv) and dose length product (DLP) on a minimum of twenty average-sized pediatric patients in each category were recorded to calculate a mean site CTDIv and DLP value. The rounded 75th percentile was used to calculate a pediatric DRL for each hospital, and then region by compiling all results. Data were collected for 3600 pediatric patients. Pediatric CT DRL for two age groups: <1 year (CTDIv and DLP of head [20 mGy, 352 mGy.cm], chest [7 mGy, 120 mGy.cm] and abdomen [12 mGy, 252 mGy.cm]), and 1-5 years (CTDIv and DLP of head [38 mGy, 505 mGy.cm], chest [8 mGy, 132 mGy.cm] and abdomen [14 mGy, 270 mGy.cm]) for select procedures have been calculated. Proposed pediatric DRLs of CTDIv and DLP for head procedure were lower, and for chest and abdomen procedures were higher than European pediatric DRLs for both age groups.

Background: To suggest South India CT diagnostic reference levels (DRLs) by collecting radiation doses for the most commonly performed CT examinations. Materials and Methods: A pilot study investigated the most frequent CT examinations. 110 CT sites were asked to complete a survey booklet to allow the recording of CT parameters for each of 3 CT examinations during a 1 year time period. Dose data such Volumetric Computed Tomography Dose Index (CTDIv) and Dose length product (DLP) on a minimum of 50 average-sized patients in each category were recorded to calculate a mean site CTDIvol and DLP value. The rounded 75th percentile was used to calculate a DRL for each site and the region by compiling all results. Results are compared with international DRL data. Results: Data were collected for 16,500 patients. All equipment had multislice capability (2-256 slices). DRLs are proposed using CTDIvol (mGy) and DLP (mGy.cm) for CT head (47 and 1041 respectively), CT chest (10 and 445 respectively), and CT abdomen (12 and 550 respectively). These values are lower than current DRLs and comparable to other international studies. Wide variations in mean doses are noted across the region. Conclusion: Baseline figures for South India CT DRLs are provided on the most frequently performed CT examinations. It was noted that there was a wide variation in mean doses among the CT scanners used during diagnosis. The differences in CT doses between CT scanner departments as well as identical scanners suggest a large potential for optimization of examinations.

Cadmium Sulphide (CdS) nanoparticles were reinforced in Poly(ethylene Oxide) (PEO) and Poly(methyl methacrylate) (PMMA) matrices by in situ technique. The presence of CdS in PEO and PMMA matrix was confirmed using X-ray photoelectron spectroscopy (XPS). Fourier Transform Infrared spectroscopy (FTIR) analysis disclosed the co-ordination of CdS in the matrices. Thermal analysis of the nanocomposites was carried out using Differential Scanning calorimetric studies (DSC). The optical studies using UV–vis spectroscopy were carried out to find the band gap of the materials and the absorption onset. The CdS particle size in the matrices was found by Effective Mass Approximation (EMA) model using the band gap values and was confirmed by TEM studies. The surface trapped emissions of the nanocomposites were observed from the photoluminescence (PL) spectra. The distribution of CdS particles in the polymer matrices were presented by Atomic force microscopic studies (AFM).