Pyrrolidinium-based ionic liquids as electrolytes for lithium batteries: A Computational Study

Electrochemical windows (ECWs) of the cyclic ammonium based ionic liquids formed by the combination of two common pyrrolidinium cations—N,N-butylmethyl pyrrolidinum(P_yr14) and N,N-hexylmethyl pyrrolidinium(P_yr16) and five anions—dicyanamide, trifluoroacetate, fluoromethane sulfonate, bis((trifluoromethylsulfonyl)imide, and bis(fluorosulfonyl)imide were investigated. The ECW of each ionic liquid was obtained from the oxidation and reduction potentials of these ionic liquids with respect to a Li⁺/Li reference electrode by using thermodynamic cycle method. The work reveals that the ECWs of these ionic liquids are solely decided by the HOMO energy of pairing anions. The ECWs were also computed using HOMO-LUMO method employing Møller-Plesset perturbation theory to the second order and M06L methods with a basis set of 6-31 + G(d, p). The ECW computed using M06L functional with an extended basis set of 6-311++G(d, p) showed better agreement with experimental values suggesting accurate computation of ECW is possible at lower computational cost.     

Stevioside Attenuates Insulin Resistance in Skeletal Muscle by Facilitating IR/IRS-1/Akt/GLUT 4 Signaling Pathways: An In Vivo and In Silico Approach

Type-2 diabetes mellitus (T2DM), the leading global health burden of this century majorly develops due to obesity and hyperglycemia-induced oxidative stress in skeletal muscles. Hence, developing novel drugs that ameliorate these pathological events is an immediate priority. The study was designed to analyze the possible role of Stevioside, a characteristic sugar from leaves of Stevia rebaudiana (Bertoni) on insulin signaling molecules in gastrocnemius muscle of obesity and hyperglycemia-induced T2DM rats. Adult male Wistar rats rendered diabetic by administration of high fat diet (HFD) and sucrose for 60 days were orally administered with SIT (20 mg/kg/day) for 45 days. Various parameters were estimated including fasting blood glucose (FBG), serum lipid profile, oxidative stress markers, antioxidant enzymes and expression of insulin signaling molecules in diabetic gastrocnemius muscle. Stevioside treatment improved glucose and insulin tolerances in diabetic rats and restored their elevated levels of FBG, serum insulin and lipid profile to normalcy. In diabetic gastrocnemius muscles, Setvioside normalized the altered levels of lipid peroxidase (LPO), hydrogen peroxide (H₂O₂) and hydroxyl radical (OH*), antioxidant enzymes (CAT, SOD, GPx and GSH) and molecules of insulin signaling including insulin receptor (IR), insulin receptor substrate-1 (IRS-1) and Akt mRNA levels. Furthermore, Stevioside enhanced glucose uptake (GU) and oxidation in diabetic muscles by augmenting glucose transporter 4 (GLUT 4) synthesis very effectively in a similar way to metformin. Results of molecular docking analysis evidenced the higher binding affinity with IRS-1 and GLUT 4. Stevioside effectively inhibits oxidative stress and promotes glucose uptake in diabetic gastrocnemius muscles by activating IR/IRS-1/Akt/GLUT 4 pathway. The results of the in silico investigation matched those of the in vivo study. Hence, Stevioside could be considered as a promising phytomedicine to treat T2DM.     

Novel Triterpenoids from Cassia fistula Stem Bark Depreciates STZ-Induced Detrimental Changes in IRS-1/Akt-Mediated Insulin Signaling Mechanisms in Type-1 Diabetic Rats

Here, we identified the mechanisms of action of antidiabetic activity of novel compounds isolated from Cassia fistula stem bark in STZ-diabetic animals. Novel triterpenoid compounds (C1, C2 and C3) were treated to STZ-administered diabetic animals at a concentration of 20mg/kg body weight orally for 60 days to assess their effects on plasma glucose, plasma insulin/C-peptide, serum lipid markers and the enzymes of carbohydrate metabolism, glucose oxidation and insulin signaling molecules. Oral administration of novel triterpenoid compounds to STZ-diabetic animals significantly decreased (p < 0.05) the plasma glucose concentration on the 7th, 15th, 30th, 45th and 60th daysin a duration-dependent manner (p < 0.05). Plasma insulin (p < 0.0001)/C-peptide (p < 0.0006), tissue glycogen (p < 0.0034), glycogen phosphorylase (p < 0.005), glucose 6-phosphatase (p < 0.0001) and lipid markers were significantly increased (p < 0.0001) in diabetic rats, whereas glucokinase (p < 0.0047), glycogen synthase (p < 0.003), glucose oxidation (p < 0.001), GLUT4 mRNA (p < 0.0463), GLUT4 protein (p < 0.0475) and the insulin-signaling molecules IR mRNA (p < 0.0195), IR protein (p < 0.0001), IRS-1 mRNA (p < 0.0478), p-IRS-1^Tyr612 (p < 0.0185), Akt mRNA (p < 0.0394), p–Akt^Ser473 (p < 0.0162), GLUT4 mRNA (p < 0.0463) and GLUT4 (p < 0.0475) were decreased in the gastrocnemius muscle. In silico analysis of C1–C3 with IRK and PPAR-γ protein coincided with in vivo findings. C1–C3 possessed promising antidiabetic activity by regulating insulin signaling mechanisms and carbohydrate metabolic enzymes.     

Energy‐induced polymorphic changes in poly(vinylidene fluoride): How ultrasonication results in polymer with predominantly γ phase

Self‐polarized poly(vinylidene fluoride) (PVDF) films were prepared via solution crystallization technique wherein the polymorphism of the films was controlled from α phase (>85%) to γ phase (>90%) by varying the time of ultrasonication. On increasing ultrasonication time up to 60 min, γ phase crystallites were found to be self‐aligned in the matrix while an equal proportion of α and γ phases coexist in the PVDF films ultrasonicated for 120 min. The phase conversion as well as inversion was evident from Fourier transform infrared, X‐ray diffraction, and differential scanning calorimetry analyses. Microscopic images of films ultrasonicated for 60 min showed a scrolled lamellar morphology while those sonicated for 120 min showed mixture of scrolled lamellar and spherulitic morphology. With the help of computational studies, it is explained that a large amount of energy is required for transforming trans‐gauche‐trans‐gauche into trans‐trans‐trans‐gauche conformation which is provided by ultrasonication. The mechanism of γ phase formation is proposed based on the experimental and theoretical approaches. Our studies show that just by tuning the time of ultrasonication, PVDF films with various morphologies can be processed; either one with predominantly electroactive γ phase with superior electrical properties or one with equal proportion of α and γ phases with superior mechanical properties. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 40–50     

Characterization of metal chelate methacrylate monolithic disk for purification of polyclonal and monoclonal immunoglobulin G

Dynamic binding capacity (DBC) of commercial metal-chelate methacrylate monolith-convective interaction media (CIM) was performed with commercial human immunoglobulin G (IgG) (Cohn fraction II, III). Monoliths are an attractive stationary phase for purification of large biomolecules because they exhibit very low back pressure even at high flow rates and flow-unaffected binding properties. Adsorption of IgG onto CIM-IDA disk immobilized with Cu²⁺, Ni²⁺ and Zn²⁺ were studied with Tris-acetate (TA), phosphate-acetate (PA) and MMA (MES, MOPS and acetate) buffer systems at different flow rates. Adsorption and elution of IgG varied with different buffers and adsorption of IgG was maximum with MMA buffer. Adsorption of human IgG from Cohn fractions (II, III) was high when Cu²⁺ was used as ligand. CIM-IDA disk showed dynamic binding capacity in the range of 14–16 mg/ml with Cu²⁺ and 7–9 mg/ml with Ni²⁺ for human IgG with MMA buffer. In the case of CIM-IDA-Zn²⁺ column, the binding capacity was only about 0.5 mg/ml of support. Different desorption strategies like lowering of pH and increasing of competitive agent were also studied to achieve maximum recovery. Chromatographic runs with human serum and mouse ascites fluid were also carried out with metal chelate methacrylate monolithic disk and the results indicate the potential of this technique for polyclonal human IgG and monoclonal IgG purification from complex biological samples.     

Electron irradiation effects on 4-amino-5-mercapto-3-[1-(4-isobutylphenyl)ethyl]-1,2,4-triazole single crystal

In this paper, we report the electron irradiation effects on the properties of an organic NLO single crystal of 4-amino-5-mercapto-3-[1-(4-isobutylphenyl)ethyl]-1,2,4-triazole. The crystal was irradiated with electron beam of different doses and was characterized by powder XRD, UV-Vis, FTIR, DSC, microhardness and SHG measurements. In XRD, the peaks are shifted due to irradiation. The SHG efficiency has been found to enhance rapidly with irradiation. The investigation of the influence of electron irradiation on the surface morphology of the grown crystal reveals the formation of craters on the surface. The laser damage threshold remains constant as the dose rate increases whereas refractive index increases after irradiation.     

Facile preparation of a cellulose microfibers–exfoliated graphite composite: a robust sensor for determining dopamine in biological samples

A simple and robust dopamine (DA) sensor was developed using a cellulose microfibers (CMF)–exfoliated graphite composite-modified screen-printed carbon electrode (SPCE) for the first time. The graphite-CMF composite was prepared by sonication of pristine graphite in CMF solution and was characterized by high-resolution scanning electron microscopy, Fourier transform, infrared, and Raman spectroscopy. The cyclic voltammetry results reveal that the graphite-CMF composite modified SPCE has superior electrocatalytic activity against oxidation of dopamine than SPCE modified with pristine graphite and CMF. The presence of large edge plane defects on exfoliated graphite and abundant oxygen functional groups of CMF enhance electrocatalytic activity and decrease potential to oxidize DA. Differential pulse voltammetry was used to quantify DA using the graphite-CMF composite-modified SPCE and demonstrated a linear response for DA detection in the range of 0.06–134.5 µM. The sensor shows a detection limit at 10 nM with an appropriate sensitivity and displays appropriate recovery of DA in human serum samples with good repeatability. Sensor selectivity is demonstrated in the presence of 50-fold concentrations of potentially active interfering compounds including ascorbic acid, uric acid, and dihydroxybenzene isomers.     

Studies in molecular structure,symmetry and conformation VII. Crystal structure of 4,4′-diaminodiphenylsulphide

The crystal structure of 4,4-diaminodiphenylsulphide, C₁₂H₁₂N₂S, has been determined by three-dimensional X-ray methods. The crystals are orthorhombic, with space-groupP2₁2₁2₁,a = 9·874(6),b = 19·445(9),c = 5·876(6) andZ= 4. The structure was solved by the heavy-atom method and refined by full-matrix least squares to anR value of 0·074. The molecules are held together by hydrogen bonds of the N-H N type, and form chains parallel to theb axis.Contribution No. 354 from the Centre of Advanced Study in Physics, University of Madras-600025, India.     

Crystal and molecular structure ofl-3-(2-acetamido-2-ethoxycarbonyl)ethylindole

l-3-(2-Acetamido-2-ethoxycarbonyl)ethylindole is monoclinic:a = 11.469(8),b = 8.088(6),c = 8.457(6) Å, = 106.45(7) °,Z = 2,P2₁. The structure has been solved by direct methods with CuK three-dimensional photographic data, and refined by full-matrix least squares toR = 0.097 for 1390 observed reflections. The structure is stabilized by intermolecular N-H...O hydrogen bonds. The indole ring of the molecule is planar within experimental error.Contribution No. 440 from the Department of Crystallography and Biophysics, University of Madras, Guindy Campus Madras-600025, India.     

Preparation and characterization of MgB2 superconductor

The MgB₂ superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties. The upper critical field, irreversibility line and critical current density have been determined using magnetization data. The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition. The surface analysis using X-ray photoelectron spectroscopy shows that MgB₂ is sensitive to atmospheric degradation.