An ab-initio study of structural,opto-electronic and thermoelectric aspects of zinc sulfide and zinc telluride

In this study, structural, electronic, optical and thermoelectric aspects of Zinc Sulfide (ZnS) and Zinc Telluride (ZnTe) have been explored in detail. These calculations have been done by utilizing FP-LAPW method via Density Functional Theory (DFT). In order to attain accurate band gaps, opto-electronic properties are evaluated with modified Becke Johnson potential (mBJ). From band structure plots, both ZnS and ZnTe reveals direct (Γ_v–Γ_C) band gap semiconductors in nature with bandgap value equal to 3.5 and 2.3 eV while in Density Of States (DOS) major influence is observed due to p states of S/Te and d state of Zn. Prominent variation of optical responses such as high values of imaginary dielectric constants 𝜀1 (ω) and n (ω) refractive index suggests that ZnS and ZnTe are applicant materials for future photonics and microelectronic devices. The thermoelectric aspects were explored by Boltz Trap code to determine electrical and thermal conductivities, Seebeck coefficients, power factors and figure of merit. The figure of merits is closer to 1 while compared with p-type ZnS and ZnTe, n-type ZnS and ZnTe has good thermoelectric properties, which are attributed to low thermal conductivity of the hole and larger effective mass. The goal of this research is to investigate not only the detailed physical aspects but also to provide an overview of its future applications in optoelectronics, displays, sensors and microelectronic industry.     

On sombor indices of tetraphenylethylene,terpyridine rosettes and QSPR analysis on fluorescence properties of several aromatic hetero-cyclic species

Aromatic heterocyclic compounds have received a lot of interest due to their various important medicinal and biological applications. The broad synthetic investigation and functional usefulness of heterocyclic molecules is driving a surge in research interest. They are found in more than 90% of innovative medications and bridge the gap between biology and chemistry, where so much scientific discovery and application happens. Heterocycles are also useful in a variety of domains, including pharmaceutical chemistry, biochemistry, and others. In this article, quantitative structure-property relationship (QSPR) models is developed using sombor indices to predict fluorescence properties of aromatic hetero-cyclic species based on their structural features. This allows researchers to estimate the fluorescence behavior of new molecules without performing experimental measurements. As an application, we have computed the sombor indices for self-assembled supramolecular graphs made of terpyridine (TPE) and tetraphenylethylene (TPY) molecules that are produced as rosette cycles. This form of rosettes graph is used in electrical sensors, light emitting diodes, bioimaging and photoelectric devices, and so on. Tetraphenylethylene can be used to make fluorescent probes for next-generation sensing applications with typical induced aggregative emission behavior.     

Heat transfer augmentation of a car radiator using nanofluids

The car radiator heat transfer enhancement by using TiO₂ and SiO₂ nanoparticles dispersed in water as a base fluid was studied experimentally. The test rig is setup as a car radiator with tubes and container. The range of Reynolds number and volume fraction are (250–1,750) and (1.0–2.5 %) respectively. Results showed that the heat transfer increases with increasing of nanofluid volume fraction. The experimental data is agreed with other investigator.     

Cationic Gallium(III) Halide Complexes: A New Generation of π-Lewis Acids

Ga-neration X: Well-defined neutral and cationic gallium(III) halide complexes have been synthesized and evaluated in catalysis. Both the (NHC)GaX(3) /AgSbF(6) catalytic mixture and isolated (NHC)GaX(2) (+) species function as exquisite π-Lewis acids in typical GaX(3) -catalyzed reactions. The cationic complexes are more active than GaX(3) and yet more resistant to hydrolysis, which allows lower catalytic loadings and faster reactions.     

[PZnMo2W9O39]5− immobilized on ionic liquid-modified silica as a heterogeneous catalyst for epoxidation of olefins with hydrogen peroxide

The epoxidation of alkenes with hydrogen peroxide catalyzed by [PZnMo₂W₉O₃₉]^5-, ZnPOM, supported on ionic liquid-modified silica, Im-SiO₂, is reported. The immobilized catalyst, [ZnPOM@Im-SiO₂] was characterized by elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and UV–Vis spectroscopic methods. This new synthesized hybrid catalyst was applied for efficient epoxidation of various olefins with aqueous H₂O₂ in acetonitrile under reflux conditions. This solid catalyst can be easily recovered by simple filtration and reused several times without significant loss of its catalytic activity.     

The DFT investigations of the electron injection in hydrazone-based sensitizers

A brief review of popular polarizable potentials for water, including both those parameterized to fit experimental properties, typically of the liquid, or electronic structure calculations on small clusters, is presented. The recently developed POLIR potential, which was parameterized to reproduce both ab initio calculations on clusters and the experimental liquid IR spectrum, is discussed, and some new results for both clusters and the liquid phase are shown, indicating its transferable nature.     

Unsteady Couette flow of viscous fluid under a non-uniform magnetic field

The aim of this letter is to construct the analytic solution for unsteady Couette flow in the presence of an arbitrary non-uniform applied magnetic field. The flow is induced by a generalized velocity given to the lower plate. The perturbed eigenfunction expansion method is employed to develop a series solution for small magnetic field.     

Improvement of Ethanol Yield from Glycerol via Conversion of Pyruvate to Ethanol in Metabolically Engineered <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The conversion of low-priced glycerol to higher value products has been proposed as a way to improve the economic viability of the biofuels industry. In a previous study, the conversion of glycerol to ethanol in a metabolically engineered strain of Saccharomyces cerevisiae was accomplished by minimizing the synthesis of glycerol, the main by-product in ethanol fermentation processing. To further improve ethanol production, overexpression of the native genes involved in conversion of pyruvate to ethanol in S. cerevisiae was successfully accomplished. The overexpression of an alcohol dehydrogenase (adh1) and a pyruvate decarboxylase (pdc1) caused an increase in growth rate and glycerol consumption under fermentative conditions, which led to a slight increase of the final ethanol yield. The overall expression of the adh1 and pdc1 genes in the modified strains, combined with the lack of the fps1 and gpd2 genes, resulted in a 1.4-fold increase (about 5.4 g/L ethanol produced) in fps1Δgpd2Δ (pGcyaDak, pGupCas) (about 4.0 g/L ethanol produced). In summary, it is possible to improve the ethanol yield by overexpression of the genes involved in the conversion of pyruvate to ethanol in engineered S. cerevisiae using glycerol as substrate.     

Effect of doped fiber length on the stretch pulses of a mode-locked erbium-doped fiber laser

A passively self-starting mode-locked fiber ring laser is demonstrated using a highly concentrated Erbium doped fiber (EDF) with a saturable absorber. The effect of EDF length on the performance of the laser is investigated. Stable stretched pulses are obtained at wavelength region of 1560nm with a repetition rate ranging from 10.1 to 12.1 MHz and a pulse width stretching from 0.52 to 0.75 ps as the EDF length is reduced from 4.5 to 1.5 m. The repetition rate goes higher as the cavity length decreases when a shorter EDF is used but the pulse width reduces as the EDF length increases since the total group velocity dispersion (GVD) in the cavity is close to zero. The article is published in the original.     

High power dual-wavelength tunable fiber laser in linear and ring cavity configurations

We describe and compare the performances of two crucial configurations for a tunable dual-wavelength fiber laser, namely, the linear and ring configurations. The performances of these two cavities and the tunability in the dual-wavelength output varied from 0.8 to 11.9 nm are characterized. The ring cavity provides a better performance, achieving an average output power of 0.5 dBm, with a power fluctuation of only 1.1 dB and a signal-to-noise ratio (SNR) of 66 dB. Moreover, the ring cavity has minimal or no background amplified spontaneous emission (ASE).