First-principles calculations of structural,electronic, and thermodynamic properties of ZnO_(1-x)S_x alloys

In this study the pseudo-potential method is used to investigate the structural, electronic, and thermodynamic proper- ties of ZnOl_xSx semiconductor materials. The results show that the electronic properties are found to be improved when calculated by using LDA ~ U functional as compared with local density approximation （LDA）. At various concentrations the ground-state properties are determined for bulk materials ZnO, ZnS, and their tertiary alloys in cubic zinc-blende phase. From the results, a minor difference is observed between the lattice parameters from Vegard＇s law and other calculated results, which may be due to the large mismatch between lattice parameters of binary compounds ZnO and ZnS. A small deviation in the bulk modulus from linear concentration dependence is also observed for each of these alloys. The ther- modynamic properties, including the phonon contribution to Helmholtz free energy △F, phonon contribution to internal energy △E, and specific iheat at constant-volume Cv, are calculated within quasi-harmonic approximation based on the calculated phonon dispersion relations.     

Wavy channel thin film transistor architecture for area efficient,high performance and low power displays

We demonstrate a new thin film transistor (TFT) architecture that allows expansion of the device width using continuous fin features – termed as wavy channel (WC) architecture. This architecture allows expansion of transistor width in a direction perpendicular to the substrate, thus not consuming extra chip area, achieving area efficiency. The devices have shown for a 13% increase in the device width resulting in a maximum 2.5× increase in ‘ON’ current value of the WCTFT, when compared to planar devices consuming the same chip area, while using atomic layer deposition based zinc oxide (ZnO) as the channel material. The WCTFT devices also maintain similar ‘OFF’ current value, ～100 pA, when compared to planar devices, thus not compromising on power consumption for performance which usually happens with larger width devices. This work offers an interesting opportunity to use WCTFTs as backplane circuitry for large‐area high‐resolution display applications. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Microbial Transformations of (+)-Isomenthol by Fusarium lini and Rhizopus stolonifer

Microbial transformation of (+)-isomenthol (1) by various strains of fungi was investigated. Fusarium lini has successfully converted compound 1 into a new metabolite, 5α-hydroxyisomenthol (2), and a known metabolite, 1α-hydroxyisomenthol (3), whereas incubation with Rhizopus stolonifer only yielded metabolite 3. The transformed metabolites were structurally characterized on the basis of their spectral data.     

pH Induced Partitioning and Interactions of Ciprofloxacin Hydrochloride with Anionic Surfactant Sodium Dodecyl Sulfate Using Ultraviolet and Fourier Transformed Infrared Spectroscopy Study

Ultraviolet (UV) and Fourier transformed infrared (FTIR) spectra of ciprofloxacin hydrochloride (Cpf) were studied under different pH conditions. The effect of aqueous, strong acidic, (pH 0.5–1.0) and a basic (pH 9.2) conditions on spectral behavior of Cpf was investigated in aqueous as well as in micellar environment of sodium dodecyl sulfate (SDS). Cpf shows partitioning from aqueous to micellar phase in a strong acidic as well as in a basic environment. Cpf shows no partitioning or binding to micelle in aqueous phase. Conductivity studies show that critical micelle concentration of SDS is increased with increasing concentration of Cpf. Different sites are responsible for binding under different pH conditions.     

Photophysical Investigations of Carmoisine Interacting with Conventional Cationic Surfactants Under Different pH Conditions

The present study describes the extent of interactions of an efficient food dye, Carmoisine (CAR), with conventional cationic surfactants, hexadecyltrimethylammonium bromide, and ethylhexadecyldimethylammonium bromide (EHDAB). The study was carried out by quantifying the spectral changes of CAR as a function of premicellar to postmicellar surfactant concentrations at various pH conditions. The quantification of CAR molecules entrapped by cationic micellar systems has been estimated with the help of mathematical models. Binding parameters of each surfactant were calculated using differential spectroscopic method. The enhanced solubilization of dye by switching the pH was observed. In support of the electrostatic forces, the larger and more hydrophobic head group favors the promising solubilization of CAR in the outer region of the micellar interior. These findings extend the proficiency of dye molecule as a reporter for sensing electrostatic environment in lipidic membranes and related organized assemblies.     

Easy preparation of 1,4,5-trisubstituted 5-(2-alkoxy-1,2-dioxoethyl)-1,2,3-triazoles by chemoselective trapping of copper(I)–carbon bond with alkoxalyl chloride

We found that alkoxalyl chloride (ClCOCO₂R) did not carry out an acylation on 1-copper(I) alkyne in solvent without additives, but chemoselectively on 5-copper(I) 1,2,3-triazole (an intermediate in cycloaddition of 1-copper(I) alkyne and azide). Thus, a one-pot preparation of 1,4,5-trisubstituted 5-(2-alkoxy-1,2-dioxoethyl)-1,2,3-triazole was achieved by simply stirring the mixture of 1-copper(I) alkyne, azide, and alkoxalyl chloride at room temperature for 4 h.     

UV-Visible Spectrometric Study and Micellar Enhanced Ultrafiltration of Alizarin Red S Dye

Ultraviolet spectrometric study of alizarin red S (ARS) showed the substantial change in dye spectra by cationic CTAB as compared to anionic SDS and nonionic TX-100 surfactant. High spectral change by CTAB confirms the anionic nature of ARS dye and thus ARS-CTAB complex formation takes place due to electrostatic force of attraction. A little spectral change by SDS is the result of similarly charged repulsive forces that overcome weak hydrophobic-hydrophobic interaction between dye and surfactant micelles. TX-100 exhibited moderate spectral effect responsive to weak hydrophobic-hydrophobic interaction alone. MEUF study of ARS dye justified the spectral changes and dye rejection percentage (R) decreases in the following order: cationic > nonionic > anionic surfactant. Permeate flux (J) slightly decreases in presence of CTAB and it remains virtually constant for both SDS and TX-100. Addition of copper salt (i.e., CuCl₂) in dye-CTAB complex solution, favors rejection (%) removing dye and copper simultaneously via micellar enhanced ultrafiltration.     

FI-spectrophotometric determination of uranium after preconcentration on an anion exchange resin

An economical, fast, sensitive and selective method for the determination of uranium (VI) from sulfate media based on the flow injection on-line preconcentration in a minicolumn having amberlite IRA-402 (strong anion exchange) resin is described. Uranium (VI) was selectively adsorbed on the resin as uranyl trisulfate complex from aqueous solution of pH 2 in the minicolumn (2.56 mm i.d. and 7.5 cm in length) at a flow rate of 10 ml min^?1. The adsorbed uranyl trisulfate complex was eluted by HClO₄ (0.1 mol l^?1, 6.5 ml min^?1) and mixed with arsenazo-III (0.05 %, 6.5 ml min^?1), and passed through the flow through cell of spectrophotometer where its absorbance was measured at 653 nm. Various parameters affecting adsorption and elution of the uranium complex were optimized. For data analyses peak absorbance was used. For 60 and 180 s preconcentration time, enrichment factors (EF) 20 and 40, sampling frequency (SF) 45 and 18 h^?1; and detection limits (DL) (3σ) 14.2 and 8.6 μg l^?1 were obtained, respectively. To enhance the sensitivity of the system, two minicolumns (described above) were used for simultaneous preconcentration and elution purpose. For 60 and 180 s preconcentration time, EF 30 and 50, SF 42 and 17 h^?1 and DL (3σ) 4.4 and 3.44 μg l^?1 were obtained, respectively. The effect of various anions and cations was studied for single column manifold. High selectivity of this method was observed. All the anions and cations studied did not interfere up to 330 times higher mass ratio to 300 μg l^?1 U (VI) except Th(IV) which was tolerated up to 133 times by the addition of washing step in the manifold. The method based on single column manifold was applied on the spiked tap water, biological sample CRM (IAEA-V4) and synthetic leach liquor solution and good recovery was obtained. The method based on dual column manifold was validated on lake sediment SL-1 (CRM) and the results obtained were in good agreement at 95 % confidence level with the given value.     

Historical variations of Bera Lake (Malaysia) sediments geochemistry using radioisotopes and sediment quality indices

The Bera Lake basin is a lacustrine mire system and the largest natural lake in Peninsular Malaysia. Three cores were collected from the lake sediments in order to assess sediment quality and ecological risks for aquatic life and human health. An index analysis approach (C _f , C _d , E _r , and IR) and fallout ²¹⁰Pb and ¹³⁷Cs radioisotopes were applied to assess the impacts of environmental evolutionary changes. Sediment chronology was determined using the Constant Rate of Supply model with the resultant ages verified by ¹³⁷Cs horizons. Although the general contamination factors indicate low risk conditions in Bera Lake the risks associated with individual layers ranged from moderate to considerable. Five deforestation phases can be identified in the dated sediment cores with distinct variations in heavy metal influxes since 1972. These phases are in excellent agreement with the dates of land clearance and development projects undertaken over the past four decades. This study has highlighted the capability of contamination factors and chronological methods in environmental evolutionary studies where catchments have experienced extensive land use changes. The destiny of heavy metal influxes into a lake can also be revealed using this methodology.