Improved supercapacitive performance of low pore size and highly stable nanostructured NiCo2O4 electrodes

Journal of Solid State Electrochemistry - The nanostructured nickel cobaltite has been synthesized by a cost-effective facile hydrothermal method and demonstrated excellent electrochemical...     

Studies of Cu‐doped ZnS thin films prepared by sputtering technique

Radio frequency magnetron sputtering technique has been used to deposit Cu‐doped ZnS thin films on glass and n‐type Si(100) substrates at room temperature. Crystalline structure, surface morphology, and elemental oxidation states have been studied by X‐ray diffraction, field emission scanning electron microscopy, atomic force microscopy, and X‐ray photoelectron spectroscopy. Ultraviolet–visible spectroscopy has been employed to measure the transmittance, reflectance, and absorbance properties of coated films. The deposited thin films crystallize in zinc blende or sphalerite phases as proved by X‐ray diffraction analysis. The intensity of diffraction peaks decreases with increasing the dopant concentrations. The predominant diffraction peak related to (111) plane of ZnS is observed at 28.52° along with other peaks. The peak positions are shifted to higher angles with an increase of Cu concentrations. X‐ray photoelectron spectroscopy studies show that Cu is present in +1 oxidation state. Transmittance, reflectance, and absorbance properties of the deposited films have a slight variation with dopant concentrations. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of oxygen partial pressure on the structural and optical properties of dc reactive magnetron sputtered molybdenum oxide films

Molybdenum oxide films (MoO₃) were deposited on glass and crystalline silicon substrates by sputtering of molybdenum target under various oxygen partial pressures in the range 8 × 10⁻⁵–8 × 10⁻⁴ mbar and at a fixed substrate temperature of 473 K employing dc magnetron sputtering technique. The influence of oxygen partial pressure on the composition stoichiometry, chemical binding configuration, crystallographic structure and electrical and optical properties was systematically studied. X-ray photoelectron spectra of the films formed at 8 × 10⁻⁵ mbar showed the presence of Mo⁶⁺ and Mo⁵⁺ oxidation states of MoO₃ and MoO_3−x. The films deposited at oxygen partial pressure of 2 × 10⁻⁴ mbar showed Mo⁶⁺ oxidation state indicating the films were nearly stoichiometric. It was also confirmed by the Fourier transform infrared spectroscopic studies. X-ray diffraction studies revealed that the films formed at oxygen partial pressure of 2 × 10⁻⁴ mbar showed the presence of (0 k 0) reflections indicated the layered structure of α-phase MoO₃. The electrical conductivity of the films decreased from 3.6 × 10⁻⁵ to 1.6 × 10⁻⁶ Ω⁻¹ cm⁻¹, the optical band gap of the films increased from 2.93 to 3.26 eV and the refractive index increased from 2.02 to 2.13 with the increase of oxygen partial pressure from 8 × 10⁻⁵ to 8 × 10⁻⁴ mbar, respectively.     

Multiparticle rapidity clustering in 200 GeV/cπ−p interactions

A study of multiparticle rapidity clustering is made using a generalized rapidity-gap method. The data for events with ?6 charged particles are compared to what would be expected from uncorrelated particle production. We find clear evidence for cluster production. The data are consistent with ～ 20% of all charged particles being produced in clusters of two charged particles; clusters of higher multiplicity are not required.     

Design and evolution of copper apatite catalysts for N-arylation of heterocycles with chloro- and fluoroarenes

We report the preparation of recyclable heterogeneous catalysts, copper-exchanged fluorapatite, and copper-exchanged tert-butoxyapatite by incorporating basic species F-/tBuO- in apatite in situ by coprecipitation and subsequent exchange with Cu(II). These basic copper catalysts catalyzed N-arylation of imidazoles and other heterocycles with chloroarenes and electron-poor fluoroarenes in good to excellent yields. Synthesis and characterization of some of the intermediates of the catalytic cycle gave some insight into the mechanism of the very important organic transformation. The necessity of basic sites for the activation of C-Cl and C-F bonds in the N-arylation of heterocycles with haloarenes is well-established.     

Differential pulse polarographic determination of procymidone in formulations and wine

The dicarboximide fungicide procymidone was studied systematically by using direct current polarography, cyclic voltammetry, differential pulse polarography (DPP), controlled potential electrolysis, and millicoulometry in the universal buffer medium with dimethylformamide as the solvent. Procymidone exhibited a single well-defined polarographic wave in the pH range 2.0-6.0, leading to the formation of the hydroxy compound. The overall reduction process was diffusion-controlled and adsorption-free. The variation of half-wave potential with pH, the concentration of the analyte, and other experimental conditions are described. The reduction mechanism proposed is an overall 4-electron process, in which the dicarboximide group is reduced. DPP was used to determine procymidone in agricultural formulations and wine at the optimum conditions found; a detection limit of 2.4 x 10(-9) M was estimated. The results obtained by the proposed method were also compared with those obtained by other methods.     

Thermal and viscoelastic properties of polyurethane-imide/clay hybrid coatings

This paper reports the synthesis and characterization of polyurethane (PU)-imide/clay hybrid coatings based on two types of polyester (PE) polyols (PE-1 and PE-2). PE-1 was prepared from neopentyl glycol (NPG), adipic acid (AA) and isophathalic acid (IPA), whereas PE-2 contains NPG, AA, IPA and TMP (trimethylol propane) with the same hydroxyl value 280 as PE-1. Cetyl trimethyl ammonium bromide (CTAB) modified montmorillonite (K10) was used as the organoclay for the synthesis of the hybrid coatings. The organoclay particles (3 wt%) were well-dispersed into the PE matrix by ultrasonication method. Then the isocyanate terminated PU prepolymers were synthesized by the reaction of polyester polyols with hard segments such as 2,4-toluene diisocyanate (TDI) or isophorone diisocyanate (IPDI) in different NCO/OH ratios e.g., 1.6:1, 2:1 and 3:1, respectively. Finally the thermally stable imide rings were incorporated into the PU backbone by complete reaction of excess NCO content present in the PU prepolymer with pyromellitic dianhydride (PMDA). The thermogravimetric analysis (TGA) shows a higher thermal stability for the PU-imide hybrid coatings with respect to the corresponding PU-imide films. A higher NCO/OH ratio has resulted in higher thermal stability. The activation energies of degradation were calculated by the Broido and Coats-Redfern methods, respectively. The dynamic mechanical thermal analysis (DMTA) results show an enhancement in the glass transition temperature value (T_g) for the clay containing hybrid coatings. The surface analysis by angle resolved X-ray photoelectron spectroscopy (AR-XPS) showed an enrichment of the soft segment towards the surface, and an enhancement in the hard segment composition in the hybrid coatings, resulted in phase mixing.     

Differential pulse polarographic determination of dicrotophos, crotoxyphos and chlorfenvinphos in grains and soils

A simple, sensitive and rapid differential pulse polarographic method has been developed for the quantitative determination of organophosphorus pesticides such as dicrotophos, crotoxyphos and chlorfenvinphos in agricultural formulations in universal buffers of a pH range 2.0-12.0. The sample is treated with ethanol to facilitate the dissolution of these pesticides. Both standard addition and calibration methods can be used for the analyses. The lower detection limits are 1.25x10(-9), 1.05x10(-9) and 1.0x10(-9) M, respectively. The method can be applied successfully to determination of these pesticides in grains and soil.     

Spectrophotometric methods for the determination of prazosin hydrochloride in tablets

Four simple and sensitive methods for the assay of prazosin hydrochloride (PRH) are developed. These methods are based on the formation of coloured species by treating it either with excess N-bromosuccinimide (NBS) and determining the unconsumed NBS with p-N-methyl aminophenol sulphate (metol)-sulphanilamide (SA) reagent (method A, lambda(max) 520 nm): with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of eerie ammonium sulphate (CAS) (method B, lambda(max) 620 nm) or with acidic dyes such as orange-II (O-II) (method C, lambda(max) 490 nm) and alizarin violet 3B (AV-3B) (method D, lambda(max) 570 nm) under the specified experimental conditions. Regression analysis of Beer's law plot showed good correlation in the concentration range of 1.0-10.0, 2.5-25.0, 1.0-17.5 and 2.5-30.0 mug ml for methods A, B, C and D respectively.