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The structural investigation of the a-Si:H material, deposited at different pressures by PECVD process, has been carried out to analyze the signatures of diffused intermediate sort of crystalline phases within the amorphous silicon matrix. Raman characterization along with the Photoluminescence (PL) and spectroscopic ellipsometry studies were carried out to understand the microstructuree of these films. From Raman analysis the material was found to have indistinguishable crystalline phase, which can also be named as “intermediate amorphous phase” (a phase defined between amorphous and ultra nano-crystalline silicon) with crystalline volume fractions as 56 % and 62 % for 0.23 Torr and 0.53 Torr respectively. Here the contribution of ultra nano-crystallites results in higher crystalline fraction, which is not visibly revealed from the Raman spectra due to its sub nano-crystallite characteristics. For the film deposited at 0.53 Torr stable photo-conductance in conjunction with high photo-response under 10 hour light soaking has been observed, which is as expected due to high crystalline volume fraction. The presence of these phases might be the possible reason for the distinct device characteristics though having nearly the similar electrical properties (photo-response ~10 4 ). These studies will help to make improvement in the individual layer properties, other than the interface effect, in the fabrication of efficient p-i-n solar cells. Copyright © 2016 VBRI Press

Gallstones (GS) are formed as a result of impaired metabolic regulation and can be reflected in serum parameters. This study was focused on classifying GS based on spectral microanalysis and identifying the possible role of serum hepatic parameters on GS of different compositions. The study included a total of 126 GS from 80 consecutive patients who underwent cholecystectomy for GS diseases in a single center. The composition and microstructure of GS were analyzed using Fourier-transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS). The serum hepatic parameters were studied in order to establish a possible etiologic relationship with GS composition. In the study group, the incidence of GS was higher in females 62 (77.5%) compared with males 18 (22.5%). The mean age was 42.81 ± 13.01 and 43.78 ± 14.4 years for female and male patients, respectively. Based on composition, the GS were assigned to four major groups: cholesterol, pigment, phosphate, and mixed stones. Mixed composition stones totally represented the majority 53 (66.3%), followed by pure cholesterol 23 (28.8%), pigment stones 2 (2.5%), and phosphate stones 2 (2.5%), respectively. Elemental composition revealed the presence of carbon (C), oxygen (O), calcium (Ca), and phosphorus (P) to be major elements along with traces of sodium (Na), magnesium (Mg), aluminum (Al), iron (Fe), copper (Cu), bromine (Br), manganese (Mn), and zinc (Zn). Among serum parameters, total bilirubin, direct bilirubin, indirect bilirubin, serum glutamic-oxaloacetic transaminase, and total protein were higher in patients with pigment GS than cholesterol GS. Characterization of GS indicates that different types of stones have different characteristics in terms of microstructure, elemental composition, and distribution. Serum hepatic function test profiles showed an association with the compositions of GS.

A series of novel 1,2,4-thiadiazole derivatives bearing 1,2,4-oxadiazole is synthesized. Structures of the synthesized compounds are confirmed by 1H and 13C NMR, and mass spectra. All products are evaluated for their anticancer activity towards human cancer cell lines: MCF-7 (breast), A549 (lung), Colo-205 (colon), and A2780 (ovarian), and demonstrate good to moderate anticancer activity. Four synthesized compounds are characterised by potent activity.

In this project work, aluminium oxide/zirconia (30% Al2O3 + 70% ZrO2) and aluminium oxide/chromium (30% Al2O3 + 70%Cr) were coated through atmospheric plasma spray technique (APS) over cast iron as a base material, and some of its mechanical properties were studied experimentally. The hardness, wear and SEM and EDX of Al2O3/ZrO2, Al2O3/Cr coated and non-coated cast iron were taken, and the results were compared. Hardness, SEM and EDX results show that the chromium is better fused with cast iron than zirconium.

Present work discusses the structural modifications in intrinsic layer of hydrogenated amorphous silicon (a-Si:H) deposited using Pulsed Wave Plasma Enhanced Chemical Vapor Deposition (PW-PECVD) technique which highlights the crystallite formation within the boundaries of nano crystallite silicon thin films. These investigations were carried out for the films deposited under the variation of applied pulsed power from 10 W to 60 W. The resultant film phases were generalized as sub-nano crystalline silicon phases. The evolution of such phases has been effectively probed using various spectroscopic and structural characterization techniques including Raman spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), and Field Emission Scanning Electron Microscopy (FESEM). The observed sub-nano crystalline volume fraction varies from ~ 28–46%. This marks the modification in crystallite growth from the partial nucleation to coalescence phase. From this the importance of pulsed wave PECVD (PW-PECVD) has been discussed in terms of high growth rates as well as the extended transition zones with the formation of sub-nano crystallite structures. The study found to be specific for understanding the sub-nano crystalline phases in the film silicon having high photo-stability and photo-response like in µc/nc-Si:H (micro/nano crystalline silicon) and a-Si:H respectively.

In the present investigation three distinct silicon thin films designated as (i) amorphous silicon, a-Si:H (ii) mixed structure consisting of small crystallites of silicon embedded in amorphous matrix, a-Si:H/nc-Si:H & (iii) mixed structure of larger crystallites embedded in amorphous matrix, a-Si:H/μc-Si:H has been chosen to perform the study of morphology, optical and electrical characteristics. These films were deposited using 60 MHz assisted VHF (very high frequency) plasma enhanced chemical vapor deposition (PECVD) process at different argon dilution (fAr) of 10%, 60% and 80%, respectively in silane gas. The micro-structure of these films was studied using Raman spectroscopy (RS), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Well arranged network of micro/nanocrystalline silicon films with well oriented crystallographic lattice planes have been obtained at high argon dilution. The average grain size estimated using Raman spectroscopy was about 2–4 nm. HRTEM confirms the existence of small and large sized crystallites embedded in amorphous matrix. FESEM and AFM microscopy exhibits the change in morphology from amorphous to varied size crystallites in amorphous silicon matrix with increasing argon dilution. The electrical and optical properties are well correlated with the amorphous and crystalline distribution in these silicon films.

In this study, we revisited the significance of the p/i interface for hydrogenated amorphous silicon (a-Si:H) solar cells. Initially, intrinsic and extrinsic (p and n type) a-Si:H layers were grown in a low pressure regime (0.5–0.1 Torr) using the conventional RF plasma-enhanced chemical vapor deposition process and their opto-electronic properties were optimized for the fabrication of p–i–n a-Si:H solar cells. Subsequently, we obtained new insights in terms of the activation energy and band gap at the p/i interface in these solar cells. The absorber layers deposited at pressures of 0.23 Torr and 0.53 Torr had the highest photosensitivity with a band absorption edge at ~700 nm. Furthermore, the photosensitivity was shown to be correlated with the estimated diffusion length, which effectively defined the carrier transport within the solar cell layers. Moreover, the cell efficiency increased from 1.53% to 5.56% due to the improved p/i interface as well as the higher photosensitivity of the intrinsic/absorber layer.

Investigation of carrier transport in hydrogenated amorphous silicon (a-Si:H) thin films deposited at various pressures (0.03 - 0.53 Torr) using 27.12 MHz assisted high frequency Plasma Enhanced Chemical vapor Deposition (PECVD) process is presented. From results of Steady State Photocarrier Grating (SSPG) the carrier diffusion length was found to vary from 0.098 - 0.189 μm. Moreover a direct influence of ambipolar diffusion length was observed with the transport mechanism for deposition pressure in the range (0.13 - 0.53 Torr). There was a correlation observed for photosensitivity and microstructure parameter with mobility lifetime (μ τ) product and diffusion length of carriers. Diffusion length and μ τ product were observed to be maximum (0.189 μm and 0.471 x 10 −8 cm 2 V −1) for the film having high photosensitivity (7.2x10 3) deposited at a rate ∼1.39 A/s at 0.53 Torr deposition pressure. In addition to electrical transport properties, the effect of deposition pressure on structural and optical properties was also studied using various characterization tools such as Raman, UV-Vis and infrared spectroscopy.

In this work, through modeling we propose how the choice of the TCO material, its texturing and optimization of band gap of a-Si:H layers help to increase the efficiency of a-Si:H solar cells. While selecting plane and textured indium tin oxide (ITO) and zinc oxide (ZnO) as TCOs, the solar cell parameters and performance are examined as a function of band gap of different a-Si:H layers. The optimum band gap values of 2.1 eV, 1.9 eV and 1.85 eV are obtained for p, i and n-layers of a-Si:H with maximum efficiencies of ~ 15.5 % and 17.7 % using plane ITO and ZnO contacts respectively. Interestingly, the conversion efficiency is further increased to ~ 16.3 % and 18.6 % when textured ITO and textured ZnO are used as TCOs. Moreover the higher efficiencies with ZnO-based contact than ITO-based contact can be explained due to slightly higher drift velocity of holes nearer to the junction and little improved optical properties which may also attributes to the enhanced trapping of the light. These results are very encouraging and may help in developing a-Si:H based solar cell technology for thin films.

In present article the influence of thickness and band gap of microcrystalline silicon emitter layer, amorphous silicon front and back intrinsic layers and p-type crystalline silicon (c-Si) wafer thickness on the performance of TCO/μc-Si:H(n)/a-Si:H(i)/c-Si(p)/a-Si:H(i)/μc-Si:H(p+)/Ag Heterojunction with thin intrinsic layer (HIT) solar cell along with other structural possibilities were investigated through computer simulations using AFORS-HET software. These simulations revealed the importance of inclusion of intrinsic a-Si:H thin layer in improving the performance of solar cell with the help of interface passivation. Also microcrystalline BSF can raise the conversion efficiency more than 4% compared to HIT solar cell having no BSF layer. Highest stable efficiency of 24.12% for p-type substrate based HITBSF (HIT with back surface field) solar cells was observed. Furthermore the effect of textured transparent conductive oxide (TCO) on solar cells was investigated where the enhanced light trapping was observed with the use of textured TCO surface which raised the performance of solar cells. These optimizations may help in fabricating μc-Si emitter and BSF based HIT solar cells with stable efficiencies compared to possibly degraded efficiencies as in case of a-Si:H based HIT solar cell structures studied so far.

Roccellatol, a new (2′R,3′S)-erythrityl-2,6-dihydroxy-4-methylbenzoate was isolated along with nine known compounds from the fruticose lichen, Roccella montagnei Bel. em. D.D. Awasthi. The structure of the new compound was elucidated by detailed spectroscopic analysis (1H, 13C, DEPT and HRMS). The present isolation of roccellatol (10) assumes significance as the esters of p-orcellinic acid are rare in lichens. Interestingly, among the known compounds, (+)-montagnetol (9) was now isolated in very large quantity (4.66%).

Hydrogenated microcrystalline silicon (μc-Si:H) has superior properties than hydrogenated amorphous silicon (a-Si:H) but its photo conversion efficiency is lower than a-Si:H. This may be due to lack of understanding of basic structural parameters of μc-Si:H solar cells. Optimization of basic structural parameters such as band gap, thickness of p-, i- and n-layers, acceptor concentration ( N a ) and donor concentration ( N d ) can help improving efficiency of μc-Si:H solar cells. We report the optimization of these structural parameters using AFORS-HET simulation software and the optimized values of band gap of p-, i- and n-layers are found to be 1.5 eV, 1.4 eV and 1.5 eV and their thicknesses are found to be 5 nm, 2000 nm and 20 nm, respectively. The optimization of values of N a and N d are also performed and highest efficiency of ∼17% is realized at N a and N d of 10 20 cm −3 . This study will be useful to solve the issues associated with existing μc-Si:H solar cell technology and may help fabricating high efficiency μc-Si:H solar cells.

Hydrogenated Silicon (Si:H) thin films were deposited by very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) technique from silane (SiH 4 ) diluted in various argon (Ar) concentration ( f ar ). The effect of argon concentration (53–95%) on the growth and properties of Si:H films was investigated. Device quality amorphous silicon films were grown at f ar = 53% and 63% showed photosensitivity of five orders of magnitude. Nucleation of crystallites were started at f ar = 82% whereas mixed-phase of amorphous (a-Si:H) and ultra nanocrystalline silicon thin film (ultra nc-Si:H) was grown at 87% of f ar . The nucleation and growth of crystallites were clearly observed in the AFM images. Raman spectra showed the splitting and blue shift of TO mode for the films grown at f ar = 82% and 87%, respectively. The variation in the hydrogen bonding configuration of these Si:H films were observed by FTIR measurement. The difference in the temperature dependent dark conductivity during heating and cooling runs decreases as the fraction of clustered Si–H bond increases in the films.

Hydrogenated silicon thin films deposited by VHF PECVD process for various silane flow rates have been investigated. The silane flow rate was varied from 5 sccm to 30 sccm, maintaining all other parameters constant. The electrical, structural and optical properties of these films were systematically studied as a function of silane flow rate. These films were characterized by Raman spectroscopy, Scanning Electron Microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy and UV–visible (UV–Vis) spectroscopy. Different crystalline volume fraction (22%–60%) and band gap (∼1.58 eV–∼1.96 eV) were achieved for silicon thin films by varying the silane concentration. A transition from amorphous to nanocrystalline silicon has been confirmed by Raman and FTIR analysis. The film grown at this transition region shows the high conductivity in the order of 10−4 Ω−1 cm−1.

Single crystals of zinc tris thiourea sulphate (ZTS) and sodium chloride (NaCl) doped zinc tris thiourea sulphate, a semiorganic nonlinear optical material were successfully grown from aqueous solution by the slow evaporation technique at room temperature. The structural, optical and thermal properties of grown crystals were studied. Structural analysis was carried out by X-ray diffractometer and observed that the grown crystals belong to orthorhombic system. Fourier transform infrared spectrum was obtained to confirm the functional groups. Thermal behaviour of the grown crystals was investigated by TGA and DSC. Second harmonic generation (SHG) efficiency measurements of Pure and NaCl doped ZTS single crystals were carried out by Kurtz powder technique. The UV–visible spectrum showed that the material possessed wide transparency in the entire visible region. The Vicker’s microhardness number was found to increase with the increased sodium chloride substitution.

An investigation of the effect of power on the deposition of nanocrystalline silicon thin films were carried out using a gaseous mixture of silane and hydrogen in the 60MHz assisted VHF plasma enhanced chemical vapor deposition (PECVD) technique. The power was varied from 10 to 50 watt maintaining all other parameters constant. Corresponding layer properties w.r.t. material microstructure, optical, hydrogen content and electrical transport are studied in detail. The structural properties have been studied by Raman spectroscopy and x-ray diffraction (XRD). The presence of nano-sized crystals and their morphology have been investigated using atomic force microscopy (AFM). The role of bonded hydrogen content in the films have been studied from the results of Fourier transform infrared spectroscopy. It was observed from the results that with increase in power, crystalline volume fraction increases and crystallite size changes from 4 to 9 nm. The optical band gap varies from 1.7 to 2.1eV due to quantum confine...

The asymmetric unit of the title salt, C4H12N22+·2C6H6NO3S−, consists of half a piperazindiium dication, located about an inversion centre, and a 4-aminobenzenesulfonate anion. The piperazine ring adopts a chair conformation. In the crystal, the cations and anions are linkedviaN—H...O and C—H...O hydrogen bonds, forming a three-dimensional framework. Within the framework there are C—H...π interactions and the N—H...O hydrogen bonds result in the formation ofR44(22) andR34(13) ring motifs.

Palladium-catalyzed synthetic methodology has been developed for the synthesis of 2-aminobenzenesulfonic acids from benzothiazoles in good to excellent yields using chloramine-B in alkaline (pH 12) acetonitrile/water (1:1) at 80 °C.

Eight mollusc species and sediment samples collected from three different stations along Tamilnadu coast, Bay of Bengal, India were analysed for the levels of petroleum hydrocarbons to elucidate the status of the petroleum residues in mollusc meant for human consumption. The concentrations of petroleum hydrocarbons in sediments along Tamilnadu coast varied from 5.04-25.5 microg/g dw (dry weight). High concentration of petroleum hydrocarbons in the sediment of Uppanar estuary (25.5 +/- 1.45 microg/g dw) was perhaps land and marine based anthropogenic sources of this region. The petroleum hydrocarbon residues in eight mollusc species collected from Uppanar, Vellar and Coleroon estuaries varied between 2.44-6.04 microg/g ww (wet weight). Although the concentration of petroleum hydrocarbons in sediment of the Uppanar region was markedly higher than the background, the petroleum hydrocarbon residues in mollusc collected from Uppanar estuary did not suggest bioaccumulation. The results signified that industrial growth has affected the aquatic environments and regular monitoring will help to adopt stringent pollution control measures for better management of the aquatic region.

The aim of the present study was to evaluate the distribution of petroleum hydrocarbons in ten commercial fish species and water samples in three estuaries along Tamilnadu coast, Bay of Bengal, India. Fish and water samples collected from Tamilnadu coast, India, were extracted and analyzed for petroleum hydrocarbons by ultraviolet fluorescence (UVF) spectroscopy. The petroleum hydrocarbon concentration (PHC) in coastal waters and fish species varied between 2.28 and 14.02 μg/l and 0.52 and 2.05 μg/g, respectively. The highest PHC concentration was obtained in Uppanar estuarine waters (14.02 ± 0.83) and the lowest was observed in Vellar estuarine waters (2.28 ± 0.25). Among the ten fish species, Sardinella longiceps have high PHC concentration from all the locations. This study suggests that S. longiceps can be used as a good biological indicator for petroleum hydrocarbon pollution in water. The concentration of petroleum hydrocarbons in coastal waters along Tamilnadu coast is markedly higher than that in the background, but there is no evidence for its increase in fish of this region. From a public health point, petroleum hydrocarbon residue levels in all fish samples analyzed in this study are considerably lower than the hazardous levels. At present, as Tamilnadu coastal area is in a rapid development stage of new harbour, chemical industries, power plants, oil exploration and other large-scale industries, further assessment of petroleum hydrocarbons and the various hydrodynamic conditions acting in the region are to be studied in detail and continuous pollution monitoring studies should be conducted for improving the aquatic environment. The results will also be useful for pollution monitoring program along the coastal region and also to check the levels of petroleum hydrocarbons.

This report presents the results of the novel fabrication of 4H-SiC pillars with nanopores using ICP-RIE dry etching. Cl 2 /Ar gas plasma with various mass flow rates was used in this etching process to produce SiC nanopillars without using patterned etch mask. Cylindrical pillars of 300 nm diameter and 500 nm height with smooth side walls were etched on SiC wafer. The etching condition for the optimized fabrication of SiC nanopillars is presented in this report. Each nanopillar has been produced with a nanosize pore at the center along its length and up to the middle of the cylindrical nanopillar; it is a unique feature has not ever been reported in case of SiC. Inclusion of oxygen was found influence the formation of nanopillars by the effect of SiO 2 micro masking. The formation of self assembled SiO 2 layer and its micro masking effect in the fabrication of this unique nanostructure has been investigated using TEM, STEM and EDAX measurements.

Pyridinium chlorochromate (PCC) mediated oxidative cyclisation of sterically crowded γ,δ-unsaturated alcohols (primary, secondary, allylic, benzylic as well as tertiary) is described.

Fractionation of extracts of the edible mushroom, Volvariella volvacea , led to the isolation of two heterocyclic carboxylic acids, namely pyridine-3-carboxylic acid [nicotinic acid, ( 5 )] and pyrazole-3(5)-carboxylic acid ( 6 ) and the four steroidal metabolites ergosterol ( 1 ), 5-dihydroergosterol ( 2 ), ergosterol peroxide ( 3 ), cerevisterol ( 4 ). Significantly, compound ( 6 ) was identified for the first time, to our knowledge, in the mushroom kingdom and is of taxonomic significance. Compounds ( 2–4 ) were isolated for the first time from the Volvariella genus. In view of the structural similarity of compound ( 6 ) to pyrazole-3-carboxylic acids, which act as agonists for nicotinic acid receptors, the levels of compounds ( 5 ) and ( 6 ) were estimated for the first time using HPTLC in V. volvacea and two other edible mushrooms, namely Agaricus bisporus and Calocybe indica . Significant levels of compound ( 5 ) were found in C. indica , and compound ( 6 ) was found in abundance in A. bisporus . Correlations are suggested between the occurrence of these compounds in mushrooms and consumption as well as beneficial health effects of this food.

A sensitive and selective method for the solvent extraction, separation, transportation and microgram determination of zirconium(IV) with dibenzo-18-crown-6 is described. Zirconium(IV) is extracted with dibenzo-18-crown-6 from 0.1 M HCl and separated from hafnium. The extraction mechanism of zirconium from HCl media was investigated. The influence of the crown ether concentration, diverse ions and temperature on the distribution constant of zirconium have been examined. The extraction equilibrium constant (log βK′Zr) and distribution constant (Kex) were 16.50±0.05 and 108.5±0.10×10−13, respectively, in the dichloromethane. The values of enthalpy and standard energy were also obtained and the kinetics of zirconium transport is discussed. The system obeys Beer's law in the range of 0.15–3.60 ppm of zirconium(IV). The molar absorptivity is 3.0×104 l mol−1 cm−1 at 283 nm. The mixed zirconium-crown thiocynate extracted complex having the maximum absorbance at 450 nm with the molar absorptivity 1×104 l mol−1 cm−1. The zirconium-dibenzo-18-crown-6 complex extract in dichloromethane was directly inserted into plasma for ICP-AES measurement, which increases the sensitivity by about 30-folds. The zirconium is determined in presence of hafnium. The method is applied to trace determination of zirconium(lV) in standard samples and seawater samples.

Background: Plumbago rosea is used in traditional systems of medicine for the preparation of formulations used for treating inflammations, cough, bronchitis, and gastrointestinal disorders, and also in conjunction with cancer chemotherapy. In the present study, the cytotoxic and anti-proliferative effects of plumbagin, and the ethanolic root extract of P. rosea (ETPR) was evaluated on SK-MEL 28 melanoma cell lines and human lymphocytes. Materials and Methods: MTT and apoptotic assays were used for the evaluation of cytotoxic and anti-proliferative effects, respectively. In addition, the effect of Plumbagin and ETPR in down regulation of BCL-2 expression is investigated using RT-PCR analysis. Results: Both plumbagin and ETPR dose-dependently decreased the cell viability more potently in melanoma cell lines. P. rosea extract demonstrated significant synergy in inhibiting BCL-2 expression than plumbagin. Moreover plumbagin showed more toxicity in human lymphocytes. Conclusion: Plumbagin has anti-cancer potential, but the side effects limits its use; yet plumbagin, in combination with other ingredients in Plumbago rosea extract, displays significant synergy leading to a stronger anticancer effect with significantly less toxicity.

In the present work, comparison is made between ITO indium tin oxide) and ZnO (zinc oxide) as TCO layer for the amorphous silicon (a-Si:H) solar cell applications using AFORS-HET simulation software. In order to improve the efficiency of a-Si:H solar cell optimization of band gap of p layer was done along with suggesting the effective light trapping measures which can be adopted in this regard. The optimized value of band gap for p layer 2.1 eV was found for obtaining maximum efficiencies of 14.91 % with ITO and 17.02 % with ZnO as front contact. The further study explored the use of textured TCO surfaces instead of the plane surfaces. The use of textured surfaces of ITO and ZnO enhanced the efficiencies to 15.85 % and 18.10 % respectively at optimized values of the band gap of p, i, and n layers. Hence the overall investigation of a-Si:H solar cells with the idea of maximizing the light trapping using plane as well as textured surfaces of TCO coatings suggests the possibilities for fabrication of efficient a-Si:H solar cells. Our simulation results reveals ZnO as suitable TCO material in order to enhance the efficiencies of solar cell compared to ITO.

Hydrogenated amorphous silicon based devices lacks behind in their fruitful applications as it suffers from major drawback i.e. light induced degradation or S–W effect. Various theories or literature have been discussed so far, but exact mechanism is still an open challenge in research community. We report on light-induced structural changes in amorphous and micro/nano crystalline silicon by performing light soaking experiments for nearly 8 h. Under vacuum accompanied with the effect of annealing on these films. The electrical, structural and optical properties were analyzed with the use of dark and photo conductivity measurements, Raman spectroscopy, Scanning electron microscopy (SEM) and Photoluminescence studies. Using Raman spectroscopy, we estimated the bond distortion w.r.t degradation percentage in samples. We observed that crystallinity as well as particle size are responsible for increase or decrease in degradation of photoconductivity. Having 72.25 % crystallinity highly stable microcrystalline silicon films showed 1.44 % photo-degradation.

Thermotropic main chain liquid crystalline polyurethanes were prepared from 4-{[4-(6-hydroxyhexyloxy)phenylimino]methyl}benzoic acid 4-{[4-(6-hydroxyhexyloxy)phenylimino]methyl}phenyl ester (mesogenic diol) and 1,6-hexamethylene di-isocyanate. The effects of partial replacement of the mesogenic diol by 20-50 mol% of poly(tetramethylene oxide)glycol (PTMG) of varying molecular mass (M n =650, 1000, 2000) on the liquid crystalline properties were studied. Structural characterization was carried out by FTIR spectroscopy and the molecular mass distribution was determined by GPC. Differential scanning calorimetry and hot stage polarizing optical microscopy were used to study the mesomorphic properties. It was observed that the partial replacement of the mesogenic diol by PTMG of varying molecular masses influenced the phase transitions and the occurrence of mesophase textures. When the molecular mass of PTMG was enhanced, a higher content of mesogenic agent was needed to obtain liquid crystalline properties.

A method for the spectrophotometric determination of yttrium using dibenzo-18-crown-6 is described. Yttrium forms a colourless complex with dibenzo-18-crown-6, [Y(OH)3 [L], which is extracted in dichloromethane, λmax 280 nm, molar absorptivity 1.35×104 l mol−1 cm−1. The extract is directly inserted in the plasma for ICP–AES measurement of yttrium which enhances the sensitivity to several fold with the detection limit 1 ng ml−1. The over all formation (β2K′) and distribution (Ke) constants calculated are 19.20±0.05 and 8.05±0.05×10−9, respectively. The colour was developed with xylenol orange having the λmax 555 nm with the molar absorptivity 5.48×103 l mol−1 cm−1. The system obeys Beers law in the range 0.81–16.2 μg ml−1 of yttrium. The yttrium is separated and determined in the presence of 90Sr. To check the validity of the proposed method the yttrium was determined in standard rock samples.

We report the growth of powder formation in Argon (Ar) diluted Silane (SiH4) plasma using 27.12 MHz assisted Plasma Enhanced Chemical Vapor Deposition process with the approach of plasma diagnosis. The appearance of powder during processing contaminates the process chamber which further can alter the film properties; hence plasma diagnosis was vital towards detecting this variation. This work presents for the first time a diagnosis of powder in the plasma using Impedance Analyser (V/I probe) at various concentrations of Argon dilution (10%–90%), chamber pressure (0.3 Torr–0.6 Torr), and applied power (4 W–20 W). Efforts were made to understand the different phases of powder formation (i.e., chain and accumulation process, coalescence phase and α → γ′ transition (powder zone)) by monitoring and evaluating the plasma characteristics such as discharge voltage and current (Vrms and Irms), Impedance (Z), phase angle (ϕ), electron density (ne), bulk field (Eb), and sheath width (ds). From the results of plasma ...

Series of novel thermotropic liquid crystalline compounds which serve as models for mesogenic diols have been synthesized. The mesogen molecules are constructed from 1,4-disubstituted benzene rings linked through ester and azomethine units. Based on the number of phenyl rings, a tetrad or pentad classification has been assigned to the core molecule. The structures of these compounds were established by FTIR and NMR spectroscopy, while the mesomorphic behaviour has been confirmed using polarizing optical microscopy and DSC. All the compounds of the homologues series are mesomorphic in nature. The lower members of the series are nematogenic, while the higher members exhibit both nematic and smectic character, with high melting behaviour and wide mesophase ranges.

Novel block copolymers of poly(ethy1ene glycol) (PEG) with various vinyl monomers namely acrylonitrile (AN), acrylamide(AAm), methyl methacrylate (MMA) and methacrylic acid (MAA) were synthesized using Ce4+-PEG and Mn3+- PEG redox system in aqueous acidic medium. The polymerization proceeded via a macroradical generation, which was substantiated by ESR spectroscopy. This macroradical acted as a redox macroinitiator for the block copolymerization of vinyl monomers. The formation of the block copolymers was confirmed by chemical test and fractional precipitation, as well as by FT-IR, 'H & 13C FT-NMR spectroscopy. The triblock nature of the block copolymers was established through the cleavage of the ether linkage of the PEG segments.

A new series of aromatic heterocyclic poly(aryl pyromellitimide-ether)s have been synthesized from various disodium metal bisphenolate salts with an N,N'-bis(p-nitrophenyl)pyromellitimide via aromatic nitro displacement solution polycondensation in dipolar aprotic solvent at elevated temperature. The reaction was rapid and free of side reactions, with good yield. The resultant polymers were characterized by intrinsic viscosity, infrared and 1 H-, 13 C-NMR spectroscopy. Thermal behavior of the synthesized polymers was evaluated by thermogravimetric analysis and correlated with their structures. The poly(tetraphenyl methane pyromellitimide-ether) showed better thermal stability than the other polymers.

The kinetics and mechanism of thermal polymerization of acrylonitrile initiated by Mn(III) pyrophosphate — poly(ethylene glycol) (PEG, molecular weight 6000) redox system in aqueous sulfuric acid medium was studied in the temperature range 30–60°C. The overall rates of polymerization and the disappearance of Mn3+ were determined. The polymerization was initiated by the organic free radical produced from the Mn3+-PEG reaction and the termination was by the metal ions. The rate of polymerization of acrylonitrile was found to be directly proportional to the square of the monomer concentration and first power of PEG concentration, and inversely proportional to the concentration of Mn3+. The rate of manganic ion disappearance was found to be directly proportional to manganic ion concentration and PEG concentration, and independent of the monomer concentration. Based on these observations, a plausible reaction scheme was suggested and suitable kinetic expressions were evaluated.

A 75-kDa protein secreted from mouse coagulating gland was purified to homogeneity by a series of isolation steps including ion exchange chromatography on a DEAE-Sephacel column and ion exchange high-performance liquid chromatography on a sulfopropyl column. It was identified to be Type IV transglutaminase (TG 4 ), based on the establishment of N-terminal sequences by automated Edman degradation together with partial sequences by MS analysis. Its cross-linking activity was tested on the reduced sample of mouse seminal secretion which contained seven major monomer proteins tentatively designated as SVS I–VII. The enzyme was able to cross-link any of SVS I–III but failed to cross-link the other SVS proteins with a M r value less than 14 kDa. SVS I and SVS III showed comparable substrate activity, but were much weaker than SVS II during the TG 4 catalysis.

Extensive chromatographic screening of extracts of the fruits of the Indian Ayurvedic plant, Dendrophthoe falcata, resulted in the isolation of three new triterpenes, 3beta-acetoxy-1beta-(2-hydroxy-2-propoxy)-11alpha-hydroxy-olean-12-ene (1), 3beta-acetoxy-11alpha-ethoxy-1beta-hydroxy-olean-12-ene (2) and 3beta-acetoxy-1beta-hydroxy-11alpha-methoxy-olean-12-ene (3) along with nine known compounds, 3beta-acetoxy-1beta,11alpha-dihydroxy-olean-12-ene (4), 3beta-acetoxy-1beta,11alpha-dihydroxy-urs-12-ene (5), 3beta-acetoxy-urs-12-ene-11-one (6), 3beta-acetoxy-lup-20(29)-ene (7), 30-nor-lup-3beta-acetoxy-20-one (8), (20S)-3beta-acetoxy-lupan-29-oic acid (9), kaempferol-3-O-alpha-L-rhamnopyranoside (10), quercetin-3-O-alpha-L-rhamnopyranoside (11), and gallic acid (12). The structures of these compounds were determined using 1D and 2D NMR and high resolution electrospray mass spectrometry. These compounds were assayed for binding to estrogen receptors-alpha and beta and kaempferol-3-O-alpha-L-rhamnopyranoside (10) was found to be a ligand for both receptors with greater affinity for beta. The triterpenes (1-9) are reported for the first time in the genus Dendrophthoe and assumes taxonomic significance.

Dibenzo-18-crown-6 (DB18C6) is used for the liquid–liquid extraction, and recovery of titanium from paints, pigment, paper and pulp industries. The extraction mechanism of titanium(IV) from pH 4 medium with DB18C6 in dichloromethane was investigated. The DB18C6 concentration in organic phase, the concentration of titanium, the effect of pH and interference ions such as Mo 6+ , V 5+ , Nb 5+ , Ta 5+ , Zr 4+ , Fe 3+ , etc. in the aqueous phase and the temperature on the distribution coefficient for the Ti(IV) have been examined. The titanium was determined by spectrophotometric and inductively coupled plasma atomic emission spectroscopic (ICP-AES) method. Titanium forms a colourless complex with DB18C6 at pH 4.0 which is extracted with dichloromethane having molar absorptivity 1.53×10 4 l mol −1 cm −1 at 285 nm. It obeys Beer's law in the range of 0.16–3.84 ppm of titanium. The colour was developed with thiocyanate which has molar absorptivity 1.50×10 3 l mol −1 cm −1 at 425 nm. The extract is directly inserted in the plasma for ICP-AES measurement, which enhance the sensitivity several folds and the limits for estimation are 0.5–30 ng ml −1 . The overall formation (log β 2 K'e) and extraction ( K ex ) constants calculated are 18.61±0.02 and 1.03±0.03×10 −10 , respectively. The transportation of titanium has been discussed. The titanium is preconcentrated and determined in standard and environmental samples.

Organophosphate (OP) poisoning is very common form of poisoning in Indian population because of its availability and easy access. Intoxication occurs following the absorption of OP agents through gastrointestinal tract, skin and respiratory tract and rarely by intramuscular or intravenous route. The clinical features depend on the amount of the poison consumed, it's concentration, the route of administration and the time of instituting therapy. We are reporting a case of an intravenous monochrotophos poisoning, an unusual way of intoxication, which was managed in our ICU.

A reverse phase HPLC method with UV detection has been developed and validated in order to quantify plumbagin, the bioactive marker of the roots of P. indica and P. zeylanica. A quantitative HPTLC method was also developed using hexane: ethyl acetate (8:2) as the mobile phase. The plumbagin content in the roots were determined using both the methods. P. indica was found to contain significantly higher amount of plumbagin than P. zeylanica. The HPLC and HPTLC methods described here are simple, rapid, accurate and sensitive.

Extension de la theorie initialement developpee par Bansigir et Iyengar pour NaCl soumis a une deformation uniaxiale, au calcul de P 11 -P 12 dans les fluorures alcalins (CaF 2 , SrF 2 et BaF 2 )

A simple method to synthesize Gallium Nitride (GaN) powder using gallium trichloride (GaCl 3 ) and ethylene diamine tetra acetic acid (EDTA) as starting materials has been discussed in this article. GaN nanocrystals were synthesized by nitradation of Gallium-EDTA complex at different temperatures of 600 °C, 700 °C, 800 °C and 900 °C in ammonia (NH 3 ) atmosphere. X-ray diffraction analysis revealed the formation of single phase hexagonal GaN for the compound synthesized at temperature of 900 °C. However the other low temperature synthesis resulted mixed phases of β-Ga 2 O 3 , 2GaONO 3 .N 2 O 5 and GaN. Scanning electron microscopy images show that the particles were in the form of agglomerates. The average size of the particle was found to be ∼20 nm by transmission electron microscopy. Energy Dispersive X-ray diffraction analysis shows variation in elemental composition of synthesized compound with respect to temperature. The room temperature photoluminescence exhibits band-edge emission of GaN at 3.46 eV.