Hydrothermal synthesis of MnO2 nanowires: structural characterizations,optical and magnetic properties

In this paper, 1D single-crystalline MnO₂ nanowires have been successfully synthesized by hydrothermal method using KMnO₄ and (NH₄)₂S₂O₈ as raw materials. X-ray diffraction patterns and high-resolution TEM images reveal pure tetragonal MnO₂ phase with diameters of 15–20 nm. Photoluminescence studies exhibited a strong ultraviolet (UV) emission band at 380 nm, blue emission at 452 nm and an extra weak defect-related green emission at 542 nm. UV–visible spectrophotometery was used to determine the absorption behavior of nanostructured MnO₂ and a direct optical band gap of 2.5 eV was acquired by Davis–Mott model. The magnetic properties of the products have been evaluated using vibrating sample magnetometer, which showed that MnO₂ nanowires exhibited a superparamagnetic behavior at room temperature. The magnetization versus temperature curve of the as-obtained MnO₂ nanowires shows that antiferromagnetic transition temperature is 99 K.     

Investigations of Viscous Dissipation in Stagnation Point Flow Past a Stretchable Riga Wall: Modern Analysis of Heat Transport

This article scrutinizes the features of viscous dissipation in the stagnation point flow past through a linearly stretched Riga wall by implementing Cattaneo-Christov heat flux model. Viscous dissipation is carried out in Cattaneo-Christov diffusion analysis for the first time in this letter. As a result of Cattaneo-Christov model, some extra terms of viscous dissipation are appeared in the energy equation. These extra terms of viscous dissipation are missing in the literature. On the utilization of suitable transformations, the equations governing the problem are reduced under the boundary layer approximation into the non-linear and dimensionless ordinary differential equations. Convergent approach is utilized to solve the dimensionless governing equations. The solution thus acquired is used to highlight the effects of emerging parameters on velocity distribution and fluid's temperature through the graphs. Features of the drag force (or skin friction co-efficient) are graphically interpreted. It is noticed that the presence of modified Hartman number helps to reduce the fluid's temperature but enhances the velocity profile. Further an enlargement in the value of thermal time relaxation parameter helps to decrease the temperature distribution.     

Microwave Irradiation and Glutamic Acid-Assisted Phytotreatment of Tannery and Surgical Industrial Wastewater by Sorghum

We investigated how different doses of microwave irradiation (MR) affect seed germination in Sorghum, including the level of remediation against textile and surgical wastewater (WW) by modulating biochemical and morpho-physiological mechanisms under glutamic acid (GA) application. The experiment was conducted to determine the impact of foliar-applied GA on Sorghum under wastewater conditions. Plants were treated with or without microwave irradiation (30 s, 2.45 GHz), GA (5 and 10 mM), and wastewater (0, 25, 50, and 100). Growth and photosynthetic pigments were significantly decreased in plants only treated with various concentrations of WW. GA significantly improved the plant growth characteristics both in MR-treated and -untreated plants compared with respective controls. HMs stress increased electrolyte leakage (EL), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) content; however, the GA chelation significantly improved the antioxidant enzymes activities such as ascorbate oxidase (APX), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) both in MR-treated and -untreated plants under WW stress compared with respective controls. The results suggested that the MR-treated plants accumulate higher levels of HMs under GA addition in comparison to the WW-only-treated and MR-untreated plants. The maximum increase in Cd accumulation was observed in the range of 14–629% in the roots, 15–2964% in the stems, and 26–4020% in the leaves; the accumulation of Cu was 18–2757% in the roots, 15–4506% in the stems, and 23–4605% in the leaves; and the accumulation of Pb was 13–4122% in the roots, 21–3588% in the stems, and 21–4990% in the leaves under 10 mM GA and MR-treated plants. These findings confirmed that MR-treated sorghum plants had a higher capacity for HMs uptake under GA and could be used as a potential candidate for wastewater treatment.     

High performance LCD for augmented reality and virtual reality displays

For augmented reality and virtual reality displays, high-resolution density, high luminance, and fast response time are critically needed. High-resolution density helps eliminate the screen-door effect; high luminance and fast response time enable low duty ratio operation, which plays a key role for suppressing image blurs. By using a low viscosity material and new diamond-shaped electrode configuration, we demonstrate a fringe field switching liquid crystal display, abbreviated as d-FFS LCD, with high transmittance, fast grey-to-grey response time, low operation voltage, wide viewing angle, and indistinguishable colour shift and gamma shift. We also investigate the rubbing angle (α) effects on transmittance and response time. When α = 0°, the virtual wall effect is strong, resulting in fast response time but compromised transmittance. When α ≥ 1.2°, the virtual walls disappear, as a result, the transmittance increases dramatically, but the trade-off is in slower response time.     

Spectroscopic observation of bipolaronic point defects in Ba(1-x)KxBiO3

An infrared-absorption band centered at 0.85 eV, which is below the big optical absorption at the charge-density-wave (CDW) gap energy of 1.85 eV, has been observed for semiconducting single crystalline Ba(1-x)KxBiO3. With substituting K for Ba, the spectral weight of the new band increases with x, while that of the CDW-gap excitation decreases. Since the impurity state with the K substitution is known to be nonmagnetic at low temperatures, Bi3+ the state with 6s2 electrons surrounded by the six Bi5+ ions forms a small bipolaron by losing a pair of electrons in the Rice-Sneddon model. The new band is assigned to a transition from the lower-Peierls band to a state of the bipolaronic point defect.     

Cobalt-catalyzed one-pot three-component coupling route to beta-acetamido carbonyl compounds: a general synthetic protocol for gamma-lactams

An efficient improved procedure for the synthesis of beta-acetamido carbonyl compounds is developed by a cobalt(II) chloride-catalyzed three-component coupling protocol. The procedure is also amenable to the synthesis of gamma-lactams by a three-component coupling reaction with use of 2-carbomethoxybenzaldehyde. The beta-acetamido carbonyl compounds derived from 2-carbomethoxybenzaldehyde are useful intermediates as they can be transformed to the corresponding gamma-lactams on treatment with base.     

Rapid preparative isolation of erythrocentaurin from Enicostemma littorale by medium‐pressure liquid chromatography,its estimation by high‐pressure thin‐layer chromatography,and its α‐amylase inhibitory activity

Erythrocentaurin is a relatively simple natural product present among the members of Gentianaceae. A preparative method for the isolation of erythrocentaurin from the ethyl acetate fraction of Enicostemma littorale using medium‐pressure liquid chromatography has been reported. The method consisted of a simple step gradient from 10 to 20% ethyl acetate in n‐hexane. Using a 70 × 460 mm Si60 column, this method is capable of processing 20 g of material in <3 h (purity ≈ 97%). The recovery of erythrocentaurin was 87.77%. Estimation of erythrocentaurin in extracts and fractions based on high‐pressure thin‐layer chromatography was carried out on silica gel 60 F₂₅₄ plates with toluene/ethyl acetate/formic acid (80:18:2 v/v/v) as the mobile phase. The densitometric analysis was performed at 230 nm. A well‐separated compact band of erythrocentaurin appeared at R_f 0.54 ± 0.04. The analytical method showed good linearity in the concentration range of 200–1500 ng/band with a correlation coefficient of 0.99417. The limits of detection and quantification were found to be ≈60 and ≈180 ng/band, respectively. Erythrocentaurin exhibited a concentration‐dependent α‐amylase inhibition (IC₅₀ 1.67 ± 0.28 mg/mL). The outcome of the study should be considered for pharmacokinetic and biotransformation studies involving E. littorale.     

Effect on photophysical properties of colloidal ZnS quantum dots by doping with cobalt, copper, and cobalt�Ccopper mixtures

Colloidal ZnS quantum dots (QDs) are prepared by passing H₂S gas through a solution of Zn(CH₃COO)₂ in acetonitrile. Photophysical properties are investigated using UV?CVisible and photoluminescence (PL) spectroscopy. The spectrum shows an absorption shoulder at 271 nm representing a band gap of 4.6 eV. The doping of ZnS QDs with Co, Cu, and a mixture of Co and Cu not only increased the band gap to 0.2 eV but also turns these otherwise colorless QDs to blue in color due to cobalt, and green due to Cu. The observed emission in the visible region suggests that the dopants may have induced additional excited states to the ZnS QDs. This absorbance in the visible region can be utilized in the optoelectronic applications.     

On（N,U）-Coherence of Modules and Rings

Let U be a flat right R-module and N an infinite cardinal number.A left R-module M is said to be (N,U)-coherent if every finitely generated submodule of every finitely generated M-projective module in σ[M] is (N,U)-finitely presented in σ[M].It is proved under some additional conditions that a left R-module M is (N,U)-coherent if and only if Л^Ni∈I U is M-flat as a right R-module if and only if the (N,U)-coherent dimension of M is equal to zero.We also give some characterizations of left (N,U)-coherent dimension of rings and show that the left N-coherent dimension of a ring R is the supremum of (N,U)-coherent dimensions of R for all flat right R-modules U.