Non-catalytic approach to the synthesis of partially reduced 'S' shaped dioxathia- and oxadithiahelicenes through base induced inter- and intramolecular C-C bond formation

An efficient and convenient route for the construction of helical 'S' shaped dioxathia- and oxadithiahelicenes with oxygen and sulfur atoms located in the middle of the outer helix has been developed through base induced inter- and intramolecular C-C bond formation from the reaction of 4-sec-amino-2-oxo-2,5-dihydrothiochromeno[4,3-b]pyran-3-carbonitriles with 3,4-dihydro-2H-benzo[b]oxepin-5(2H)-ones, 3,4-dihydrobenzo[b]thiepin-5(2H)-one and thiochroman-4-ones separately. Quantum chemical calculations have also been carried out to explore the geometries and electronic structures of newly synthesized compounds to envisage the pathway for interconversion of both atropisomers. The determination of helicity parameters and configurational stability demonstrate that the energy barrier is strongly dependent on the nature of hetero-atoms present.     

Proanthocyanidins Modulate Rumen Enzyme Activities and Protein Utilization In Vitro

This study investigated the principal leaf protein (rubisco) solubilization and in vitro ruminal enzyme activity in relation to the molecular structure of proanthocyanidins extracted from leaves of Anogeissus pendula and Eugenia jambolana. Six proanthocyanidin fractions were extracted by 50% (v/v) methanol–water followed by 70% (v/v) acetone–water and then distilled water from leaves of A. pendula (AP) and E. jambolana (EJ) to yield EJ–70, EJ–50, EJ–DW, AP–70, AP–50 and AP–DW. Fractions were examined for their molecular structure and their effects on sheep ruminal enzymes and solubilization of rubisco in vitro. All fractions significantly (p < 0.05) inhibited the activity of ruminal glutamic oxaloacetic transaminase and glutamic pyruvic transaminase. The fractions AP–50 and EJ–50 significantly inhibited the activity of the R-cellulase enzyme. Most of the fractions inhibited R-glutamate dehydrogenase activity (p < 0.05) by increasing its concentration, while protease activity decreased by up to 58% with increasing incubation time and concentration. The solubilization of rubisco was observed to be comparatively higher in A. pendula (16.60 ± 1.97%) and E. jambolana (15.03 ± 1.06%) than that of wheat straw (8.95 ± 0.95%) and berseem hay (3.04 ± 0.08%). A significant (p < 0.05) increase in protein solubilization was observed when wheat straw and berseem hay were supplemented with A. pendula and E. jambolana leaves at different proportions. The efficiency of microbial protein was significantly (p < 0.05) greater with the supplementation of leaves of A. pendula in comparison to E. jambolana. The overall conclusion is that the proanthocyanidins obtained from E. jambolana exhibited greater inhibitory activities on rumen enzymes, whereas A. pendula recorded higher protein solubilization. Thus, PAs from A. pendula and E. jambolana appear to have the potential to manipulate rumen enzyme activities for efficient utilization of protein and fiber in ruminants.     

Development and validation of an ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method for the simultaneous determination of selected flavonoids in Ginkgo biloba

A rapid and sensitive ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method was developed and validated for the simultaneous determination of 13 flavonoids in leaf, stem, and fruit extracts of male and female trees of Ginkgo biloba to investigate gender‐ and age‐related variations of flavonoids content. Chromatographic separation was accomplished on an Acquity UPLC BEH C₁₈ column (50 mm × 2.1 mm id, 1.7 μm) in 5 min. Quantitation was performed using negative electrospray ionization mass spectrometry in multiple reaction monitoring mode. The calibration curves of all analytes showed a good linear relationship (r² ≥ 0.9977) over the concentration range of 1–1000 ng/mL. The precision evaluated by an intra‐ and interday study showed RSD ≤ 1.98% and good accuracy with overall recovery in the range from 97.90 to 101.09% (RSD ≤ 1.67%) for all analytes. The method sensitivity expressed as the limit of quantitation was typically 0.25–3.57 ng/mL. The results showed that the total content of 13 flavonoids was higher in the leaf extract of an old male Ginkgo tree compared to young female Ginkgo trees.     

GeO2/ZnWO4@CNT nanocomposite as a novel anode material for lithium-ion battery

Journal of Solid State Electrochemistry - Single-walled carbon nanotube (SWCNT) wrapped GeO2/ZnWO4 nanocomposite was prepared by single-step solvothermal method. In this work, GeO2/ZnWO4...     

A wavelet-based variational multiscale method for the LES of incompressible flows in a high-order DG-FEM framework

This work focuses upon the development of a wavelet-based variant of the variational multiscale method (VMS) for accurate and efficient large eddy simulation (LES) called wavelet-based VMS-LES (WMS-LES). This approach has been incorporated within the framework of a high-order incompressible flow solver based upon the pressure-stabilized discontinuous Galerkin finite element method (DG-FEM). The VMS approach is designed to produce an a priori scale separation of the governing equations, in a manner which makes no assumptions on either the boundary conditions or the mesh uniformity. Using second-generation wavelets (SGWs) elementwise for scale separation ensures, on one hand, the preservation of the computational compactness of the DG-FEM scheme and, on the other hand, the ability to achieve scale separation in wavenumber space. The optimal space-frequency localization property of the SGW provides an improvement over the commonly used Legendre polynomials. The suitability of the elementwise SGW scale-separation operation as a tool for error indication has been demonstrated in an h-adaptive computation of the reentrant corner test case. Finally, the DG-FEM solver and the WMS-LES method have been assessed through simulations upon the three-dimensional Taylor-Green vortex test case. Our results indicate that the WMS-LES approach exhibits a distinct improvement over the monolevel LES approach. This effect is not produced by a change in the magnitude of the subgrid dissipation but rather by the redistribution of the subgrid dissipation in wavenumber space.     

Quality control assessment of polyherbal formulation based on a quantitative determination multimarker approach by ultra high performance liquid chromatography with tandem mass spectrometry using polarity switching combined with multivariate analysis

An ultra high performance liquid chromatography with electrospray ionization tandem mass spectrometry method has been developed and validated for the simultaneous quantification of 28 major bioactive compounds in Mentat tablet, a complex Indian herbal medicine used in the treatment of neurological disorder and improvement of mental health. Multiple‐reaction monitoring scanning was employed for quantification in positive and negative ion switching mode. The analysis was accomplished on Waters ACQUITY UPLC BEH C₁₈ column with linear gradient elution of water/formic acid (0.1%) and acetonitrile/formic acid (0.1%) at a flow rate of 0.3 mL/min. The proposed method was validated with acceptable linearity (r², 0.9984–0.9999), precision (RSD, 0.22–2.11%), stability (RSD, 0.16–1.78%), and recovery (RSD ≤ 3.74%), under optimum conditions. The limits of quantitation ranged from 0.28 to 3.88 ng/mL. The method was successfully applied for simultaneous determination of 28 compounds in 20 batches of Mentat tablet. Hierarchical cluster analysis and principal component analysis were performed to evaluate the similarity and variation of the 20 samples based on the characteristics of 28 bioactive compounds. Results indicated that this method is rapid, sensitive, and reliable to show the quality of the Mentat tablet's composition, hence may be used for quality control of polyherbal formulations having similar markers/raw herbs.     

Synthesis,evaluation and docking studies of some 4-thiazolone derivatives as effective lipoxygenase inhibitors

Some promising 4-thiazolone derivatives as lipoxygenase inhibitors were designed, synthesized, characterized and evaluated for anti-inflammatory activity and respective ulcerogenic liabilities. Compounds (1b, 1e, 3b, and 3e) exhibited considerable in vivo anti-inflammatory activity (57.61, 79.35, 75.00, and 79.35%) against carrageenan-induced rat paw edema model, whereas compounds (1e, 3b, and 3e) were found active against the arachidonic acid-induced paw edema model (55.38, 55.38, and 58.46%). The most potent compound (3e) exhibited lesser ulcerogenic liability compared to the standard diclofenac and zileuton. Further, the promising compounds (1e and 3e) were evaluated for in vitro lipoxygenase (LOX; IC₅₀?=?12.98 µM and IC₅₀?=?12.67 µM) and cyclooxygenase (COX) inhibition assay (COX-1; IC₅₀?>?50 µM and, COX-2; IC₅₀?>?50 µM). The enzyme kinetics of compound 3e was evaluated against LOX enzyme and supported by in silico molecular docking and molecular dynamics simulations studies. Overall, the results substantiated that 5-benzylidene-2-phenyl-4-thiazolones are promising pharmacophore for anti-inflammatory activity.     

Optimization of ultrasound assisted extraction of antioxidant compounds from marjoram (Origanum majorana L.) using response surface methodology

The present study optimized the ultrasound assisted extraction (UAE) conditions to maximize the antioxidant activity [Ferric ion Reducing Antioxidant Power (FRAP)], total phenol content (TP) and content of individual polyphenols of extracts from marjoram. Optimal conditions with regard to amplitude of sonication (24.4-61.0 μm) and extraction temperature (15-35 °C) and extraction time (5-15 min) were identified using response surface methodology (RSM). The results showed that the combined treatment conditions of 61 μm, 35 °C and 15 min were optimal for maximizing TP, FRAP, rosmarinic acid, luteolin-7-O-glucoside, apigenin-7-O-glucoside, caffeic acid, carnosic acid and carnosol values of the extracts. The predicted values from the developed quadratic polynomial equation were in close agreement with the actual experimental values with low average mean deviations (E%) ranging from 0.45% to 1.55%. The extraction yields of the optimal UAE were significantly (p < 0.05) higher than solid/liquid extracts. Predicted models were highly significant (p < 0.05) for all the parameters studied with high regression coefficients (R²) ranging from 0.58 to 0.989.     

Hydrodynamic radius and intrinsic viscosity of polystyrene in the crossover region from θ to good-solvent conditions

The radius of gyration R_g, the hydrodynamic radius R_h, and the intrinsic viscosity [η] have been measured for polystyrene in cyclohexane (at the θ temperature and 44.5°C), 2-butanone (at 30°C), and toluene (at 30°C) in the molecular weight range 2.38 × 10⁵ ≤ M_w ≤ 5.47 × 10⁶ to elucidate the excluded-volume effects on dynamical behavior in dilute polymer solutions in the crossover region from θ to good-solvent conditions. The results are compared with theoretical predictions of current thermal blob theories and the Pade approximant theory of Tanaka. It is found that the ratio of R_h/R_g decreases with an increase in the excluded-volume effect, following the prediction of the simple blob theory, but that its magnitude is about 15% higher than the theoretical value. Experimental variation of [η] with R_h and/or R_g lies in between predictions of the scaling law and the Pade approximant. The concentration dependence of the diffusion coefficient is also compared with predictions of current theories.     

Thermophysical and thermoacoustical properties of acetophenone with ethyl butyrate at temperatures of 303.15, 313.15, and 323.15 K

Densities, viscosities, and ultrasonic velocities of the binary mixtures of acetophenone with ethyl butyrate were measured over the entire mole fractions at 303.15, 313.15, and 323.15 K. From these experimental results, excess molar volume V ^E , viscosity deviation Δη, deviations in isentropic compressibility Δκ _s , excess intermolecular free length ΔL _f , and excess Gibbs free energy ΔG* ^E were calculated. The viscosity values were fit to the models of Krishnan–Laddha and McAllister. The thermophysical properties under study were fit to the Jouyban–Acree model. The excess values were correlated using Redlich–Kister polynomial equation to obtain their coefficients and standard deviations. It was found that in all cases, the data obtained fitted with the values correlated by the corresponding models very well. The results are interpreted in terms of molecular interactions occurring in the solution.