Synthesis,Biochemistry, and Computational Studies of Brominated Thienyl Chalcones: A New Class of Reversible MAO‐B Inhibitors

A series of (2E)‐1‐(5‐bromothiophen‐2‐yl)‐3‐(para‐substituted phenyl)prop‐2‐en‐1‐ones ( TB1 – TB11 ) was synthesized and tested for inhibitory activity toward human monoamine oxidase (hMAO). All compounds were found to be competitive, selective, and reversible toward hMAO‐B except (2E)‐1‐(5‐bromothiophen‐2‐yl)‐3‐(4‐nitrophenyl)prop‐2‐en‐1‐one ( TB7 ) and (2E)‐1‐(5‐bromothiophen‐2‐yl)‐3‐(4‐chlorophenyl)prop‐2‐en‐1‐one ( TB8 ), which were selective inhibitors of hMAO‐A. The most potent compound, (2E)‐1‐(5‐bromothiophen‐2‐yl)‐3‐[4‐(dimethylamino)phenyl]prop‐2‐en‐1‐one ( TB5 ), showed the best inhibitory activity and higher selectivity toward hMAO‐B, with K_i and SI values of 0.11±0.01 μm and 13.18, respectively. PAMPA assays for all compounds were carried out in order to evaluate the capacity of the compounds to cross the blood–brain barrier. Moreover, the most potent MAO‐B inhibitor, TB5 , was found to be nontoxic at 5 and 25 μm , with 95.75 and 84.59 % viability among cells, respectively. Molecular docking simulations were carried out to understand the crucial interactions responsible for selectivity and potency.     

An Efficient Encoder Architecture Design for Cognitive Radio Networks

Wireless Personal Communications - Interference formation between received symbols in Cognitive Radio (CR) network system is the main problem which reduces the performance of the CR networks. In...     

Changes in free volume and gas permeation properties of poly(vinyl alcohol) nanocomposite membranes modified using cage-structured polyhedral oligomeric silsesquioxane

The present work reports the effect of various organically functionalized polyhedral oligomeric silsesquioxane (POSS) particles on the gas transport properties (N₂, O₂, and CO₂ molecules) in poly(vinyl alcohol) (PVA) membranes. The incorporation of polyethylene glycol-POSS (PEG-POSS), octa-tetramethylammonium-POSS (Octa-TMA-POSS) and m-POSS (Octa-TMA-POSS molecule was modified using cetyltrimethyl ammonium bromide) led to the enhancement in CO₂ separation performance of PVA, among which, PEG-POSS exhibited highest CO₂ separation due to the dipole-quadrupolar interaction of CO₂ with ethylene oxide group in POSS. Octa-TMA-POSS and m-POSS reduced the O₂ and N₂ permeability of the PVA membrane due to the reduction in the number of permeating pathways as compared to pure PVA. Free volume of the membranes was evaluated by positron annihilation lifetime spectroscopic (PALS) and coincidence Doppler broadening measurements. PALS confirms the increase in polymer free volume in PVA/POSS system due to the presence of rigid and spherical POSS molecule, which could enter in the polymer chain and provide viable pathway for molecular transport. Maxwel–Wagner–Sillar and Higuchi models were applied for the theoretical prediction of permeability of the fabricated membranes.     

Evolutionary multi-objective optimization of artificial neural network for classification of autism spectrum disorder screening

Evolutionary computing algorithms are computational intelligent systems that are used in a wide range of research applications, primarily for optimization. In this paper, an artificial neural network (ANN), a machine learning technique, is used to classify the data. The weights associated with each neuron and the architecture of the neural network always bias the output of the network model. With prior knowledge or trial and error techniques, different metrics or objectives can be used to optimise these weights. The optimization of weights using multiple objectives refers to a "multi-objective optimization problem." In this paper, an evolutionary cultural algorithm is used to optimise weights in ANN, and the results are reported with improved accuracy. Three benchmark datasets for autism screening data are used, trained, and tested for model accuracy in the classification: toddlers (1054,19), children (292,21), and adults (704,21).With the support of the domain expert, real-time data were collected from parents and caregivers and totalled over 1000 records, with a moderate difference in attributes based on CARS-2 (Childhood Autism Rating Scale, 2nd Edition) for ASD screening. In this paper, the proposed model is compared using a curve-fitting mathematical technique. The proposed model is trained and tested, and the results showed that it outperformed other algorithms in terms of precision, accuracy, sensitivity, and specificity.

     

Confinement effects at nanoscale in natural rubber composites: Influence on macroscopic properties

The study of molecular level interactions in elastomer composites has got very scant attention even though a large number of studies are going on in this topic. This work embodies the understanding of confinement effects in natural rubber (NR)/ ZnO composites from micro to nano length scales, and their influence on macroscopic properties of the composites. The interactions between fillers and matrix are characterized from the Donth's approach, which allows estimating the cooperativity size N_α at the glass transition, N_α being directly related to the filler-matrix interactions. The improved properties of NR-nano ZnO composites can be attributed to microstructural and morphological changes due to nano ZnO in the NR matrix. A correlation between N_α, the constrained volume C_v and the thickness of immobilized polymer chains χ_m at the glass transition has also been established. Thus, this work proves that the Donth's approach is a powerful probe to estimate the enhance of mechanical properties in nanocomposites from calorimetric investigations.     

Free volume defects and transport properties of mechanically stable polyhedral oligomeric silsesquioxane embedded poly(vinyl alcohol)‐poly(ethylene oxide) blend membranes

Polymer membrane based gas transport and pervaporation processes are fast growing areas in separation technology and have received wide attention as areas of ‘clean technology’. Mechanically stable novel polyhedral oligomeric silsesquioxane (POSS) embedded poly(vinyl alcohol) (PVA)/poly(ethylene oxide) (PEO) blend membranes were prepared by solution blending followed by casting. The addition of carboxymethyl cellulose enhanced the interfacial activities of the PVA and PEO blends. The peripheral organic substituent on POSS plays a key role in achieving compatibility with polymers whereas the rigid Si–O–Si core of POSS imparts high mechanical strength. Compared to PVA membrane, poly(ethylene glycol) and octa(tetramethylammonium) functionalized POSS embedded PVA/PEO membranes exhibit 680% and 580% enhancement in Young's modulus as well as 130% and 140% improvement in tensile strength respectively. The Einstein, Kerner and Frankel–Acrivos models were applied to compare the experimental and theoretical Young's modulus of PVA‐PEO/POSS membranes. The presence of an ethylene oxide tail on POSS as well as PEO in the blend membrane enhances the CO₂ affinity of the membrane. The presence of a hydrophilic functional group on the POSS improves the hydrophilicity of the membrane and produces more binding sites for water molecules in the membrane during the pervaporation separation of a tetrahydrofuran–water azeotropic mixture. The transport properties of the membrane are further elucidated by means of free volume defect analysis carried out by positron annihilation lifetime spectroscopy and coincidence Doppler broadening spectroscopy. © 2019 Society of Chemical Industry     

Capillary electrophoretic screening for the inhibition of homocysteine thiolactone-induced protein oligomerization

We report the first demonstration of rapid electrophoretic monitoring of homocysteine thiolactone-induced protein oligomerization (HTPO), a unique type of post-translational protein modification that may have clinical significance as an indicator of cardiovascular and neurovascular diseases. HTPO of the model protein bovine cytochrome c was initiated in vitro. The relative monomer and aggregate levels of the resultant protein mixtures were determined following separation using capillaries coated with the cationic polymer, poly(diallyldimethylammonium chloride). UV detection provided adequate sensitivity for the monitoring of higher order species, which exist at relatively low concentrations in the protein reaction mixture as compared to the monomeric species. Separations performed under standard injection conditions were optimized on the basis of applied voltage and sample denaturation conditions. Separations performed using short-end injection allowed for more rapid analyses, typically in less than 70 s. Relative errors for run-to-run migration times were less than 0.5%. This novel oligomeric system provides a rapid and straightforward in vitro method to screen therapeutic agents for their ability to inhibit HTPO. Changes in peak area for monomer and aggregate species were used to assess HTPO inhibition as a function of pyridoxal 5-phosphate (PLP) concentration. PLP was shown to effectively inhibit HTPO in vitro. Rapid analysis times of approximately 1.5 min were achieved for inhibition screening.     

Carbon black distribution driven by its concentration and its effect on physico-mechanical properties of styrene butadiene rubber and butadiene rubber miscible rubber blends

This paper discusses the influence of partitioning of carbon black (CB) with its increasing concentration (i.e., 10, 20, 30, 40, and 50 phr) on physical and static mechanical properties of Styrene Butadiene Rubber (SBR)/Butadiene Rubber (BR) rubber–rubber blends (RRB's) in 70SBR:30BR blend ratio. Partitioning of CB towards BR in CB-filled SBR/BR RRB's is quantitatively determined via dynamic mechanical analysis (DMA). DMA confirmed increased partitioning of CB towards BR phase with increasing CB. DMA data on the partitioning of CB towards BR were in good agreement with nuclear magnetic spectra obtained by solid-state nuclear magnetic resonance spectroscopy (SS-NMR spectroscopy). Curing properties, relative density, hardness, tensile test, tear test, and transmission electron microscopy (TEM) on CB filled SBR/BR RRB's were carried out to determine the effect of increasing concentration of CB on physical, mechanical, and dispersion characteristics in comparison to neat SBR/BR RRB's.