Phosphonitrilic Chloride - A Reagent for Bischler-Napieralski Reaction

Using (NPCl²)³ as a reagent for Bischler-Napieralski ring closure, various β-aryl amides were converted to 3,4-dihydroisoquino line derivatives.     

Magnetohydrodynamic effects on natural convection flow of a nanofluid in the presence of heat source due to solar energy

The objective of the present work is to investigate theoretically the MHD convective flow and heat transfer of an incompressible viscous nanofluid past a porous vertical stretching sheet in the presence of variable stream condition due to solar radiation (incident radiation). The governing equations are derived using the usual boundary-layer and Boussinesq approximations and accounting for the presence of an applied magnetic field and incident radiation flux. The absorbed radiation acts as a distributed source which initiates buoyancy-driven flow and convection in the absorbed layer. The partial differential equations governing the problem under consideration are transformed by a special form of Lie symmetry group transformations viz. one-parameter group of transformation into a system of ordinary differential equations which are solved numerically using Runge Kutta Gill based shooting method. The conclusion is drawn that the flow field and temperature are significantly influenced by radiation, heat source and magnetic field.     

High pressure studies on the electrical resistivity of Ge–Te–Tl glasses

The variation of electrical resistivity in the system of glasses Ge₁₇Te_83?xTl_x, with (1≤x≤13), has been studied as a function of high pressure for pressures up to 10 GPa. It is found that the normalized electrical resistivity decreases continuously with the increase in pressure and shows a sudden drop at a particular pressure (transition pressure), indicating the presence of a transition from semiconductor to near-metallic at these pressures which are in the range 3.0–5.0 GPa. This transition pressure is seen to decrease with the increase in the percentage content of thallium due to increasing metallicity of the thallium. The transition is reversible under application of pressure and X-ray diffraction of samples recovered after pressurization show that they remain amorphous after undergoing a pressurization decompression cycle.     

One-step preparation of sulfonated carbon and subsequent preparation of hybrid material with polyaniline salt: a promising supercapacitor electrode material

The present trend to increase the energy density of electrochemical supercapacitor is to hybrid the electrochemical double layer capacitance electrode materials of carbon with loading or encapsulation of transition metal oxide or conductive polymeric pseudocapacitor materials as the binary or ternary hybrid electrochemical active materials. In this work, we selected polyaniline salt-sulfonated carbon hybrid (PANI-SA?C _SA ) as a cheaper electrode material for supercapacitor electrode. Sulfonated carbon (C _SA ) was prepared from hydrothermal carbonization of furaldehyde and p-toluenesulfonic acid. Polyaniline-sulfate salt containing sulfonated carbon was prepared by chemical oxidative polymerization of aniline using ammonium persulfate in presence of sulfuric acid and sulfonated carbon via aqueous, emulsion and interfacial polymerization pathways. Formation of hybrid material was confirmed from scanning electron microscopy. Among the hybrid prepared with three different polymerization pathways, hybrid prepared by aqueous polymerization pathway showed better electrochemical performance. The specific capacitance of the hybrid prepared via aqueous polymerization was 600 F g^?1, which is higher than that of the pristine PANI-SA (350 F g^?1) and C _SA (30 F g^?1). Hybrid material was subjected for 8000 charge-discharge cycles and at 8000 cycles; it showed 88% retention of its original specific capacitance value of 485 F g^?1 with coulombic efficiency (97–100%). These results showed that C _SA micro spheres prevent the degradation of PANI-SA chains during charge/discharge cycles. Specific capacitance, cycle life, low solution resistance, low charge transfer resistance and high phase angle value of PANI-SA?C _SA supercapacitor cell indicates a higher performance supercapacitor system.

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Graphical abstract Synthesis of hybrid of sulfonated carbon with polyaniline sulfate salt and its supercapacitor performance Ravi Bolagam, Palaniappan Srinivasan,^* Rajender Boddula

     

Finite element approximation of nonlocal parabolic problem

In this article, we present a finite element scheme combined with backward Euler method to solve a nonlocal parabolic problem. An important issue in the numerical solution of nonlocal problems while using Newton's method is related to its structure. In fact differently from the local case where the Jacobian matrix is sparse and banded, in the nonlocal case the Jacobian matrix is dense and computations are much more onerous compared to that for differential equations. In order to avoid this difficulty, we use the technique given by Gudi (SIAM J Numer Anal 50 (2012), 657–668) for elliptic nonlocal problem of Kirchhoff type. We discuss the well‐posedness of the weak formulation at continuous as well as at discrete levels. We also derive a priori error estimates for semidiscrete and fully discrete formulations in L² and H¹ norms. Results based on the usual finite element method are provided to confirm the theoretical estimates. © 2016 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 786–813, 2017     

Structural Stability Among Hybrid Antimicrobial Peptide Cecropin A(1–8)–Magainin 2(1–12) and Its Analogues: A Computational Approach

Cecropin A–Magainin 2 (CA–MA) hybrid antimicrobial peptide (AMP), a combination of two naturally occurring AMPs, cecropin A and magainin 2 is preferred widely in biotechnological, nano and pharmaceutical applications. It exhibits a strong antibacterial activity with a characteristic reduced cytotoxic effect towards mammalian cells. In this study, three AMP structures native CA–MA hybrid and its tryptophan substitutes CA–MA L2 and CA–MA A2 was computationally studied to analyze their structural stability and functionality. Computational analysis like, intra-molecular interactions (25), relative stability (3.22) and instability index (?14.28) showed an increase in structural stability of native CA–MA hybrid. Additionally, the generated peptide ensembles showed a RMSD (3.98 Å), RMSF (0.202 Å), radius of gyration (11.98 Å), ovality (3.33) and hydrophobicity (69.7%) supporting native CA–MA along with hydrogen bond strength (?4.212 kcal/mol) and distribution comparatively. The distribution of secondary structure in native CA–MA hybrid showed the sequential maintenance of stable helical content along with helical stability (52.25%) and computed free energy (?1.74 kcal/mol) in membrane mimicking environment proving its functional activity comparatively. This study aids in designing stable AMP biodrugs with low cytotoxicity in future, the result can be potentially extended to other AMPs to assist in their exploitation as peptide and nano drugs.     

First Synthesis of Bis(di(indolyl)aryl)methanes From Bis(salicylaldehydes)

In this article, a simple method for the synthesis of bis(di(indolyl)aryl)methanes is described. The iodine‐catalyzed (5 mol %) reaction of indoles with various bis(salicylaldehyde) derivatives affords the bis(di(indolyl)aryl)methanes in excellent yields. The reaction works well under mild reaction condition with shorter reaction time.     

Kinetics and optimisation of process parameters for electrochemical generation of uranous ions in nitric acid–hydrazine media

For the quantitative generation of uranous from uranyl ions in the presence of hydrazine in nitric acid medium, electrochemical reduction was carried out in divided and undivided cells. The influence of process conditions, viz. current density, concentration of nitric acid and hydrazine was studied for 50, 100 and 150 g/l of U(VI) solutions. The performance of the cathodes (titanium and platinum) was evaluated by calculating the conversion efficiencies in the reduction process using these electrodes for the reduction of 100 g/l U(VI) at 6 mA/cm² as the cathodic current density. Batch mode experiments using Ti cathode revealed the reduction reaction of U(VI) to follow zero order kinetics and the simultaneous reduction of nitric acid to follow first order kinetics. From the temperature dependence, the activation energy for the reduction of U(VI) was determined to be 4.05 kJ/mol. The chemical stability of U(IV) in nitric acid–hydrazine medium, under ambient conditions of temperature and pressure was established from the amount of U(VI) produced from U(IV) by aerial oxidation over a period of 16 weeks.