Impedimetric genosensor for miRNA-34a detection in cell lysates using polypyrrole

Journal of Solid State Electrochemistry - This work reports the development of simple, practical, cost effective and label free genosensor prepared by electropolymerization of polypyrrole on pencil...     

Half-metallic ferromagnetism in cubic perovskite type NdInO3

ABSTRACT

Based on the full-potential linearised augmented plane wave plus local orbitals (FP-L/APW?+?lo) method within the density functional theory (DFT), the structural, electronic, and magnetic calculations of the cubic oxide perovskite NdInO₃ compound have been done under the generalised gradient approximation (GGA). The exchange and correlation (XC) potential is defined as GGA framework in the analyses of structural properties, while both GGA and GGA?+?U (U is the Hubbard correlation term) approximations are taken to treat the electronic and magnetic properties. It is found that ferromagnetic (FM) configuration is reported as the most stable ground state of the cubic NdInO₃ material; however, the equilibrium lattice parameters such as lattice constant (a₀ ), bulk modulus (B₀ ), its first-pressure derivative (B’), and the minimum of total energy (E₀ ) are given in paramagnetic (PM), ferromagnetic (FM), and anti-ferromagnetic (AFM) states. The spin-polarized electronic structure calculations (band structure and density of states) of the cubic oxide perovskite NdInO₃ compound verify the half-metallic feature due to the spin-up case which has the metallic nature, whereas the spin-down case presents the semiconducting character. Moreover, the magnetic properties show the integer value of the total magnetic moment for the studied compound (3μ_B ), where it is manly contributed by Nd atoms with apparition of weak local magnetic moments in non magnetic In and O sites.     

A new reformulation-linearization technique for bilinear programming problems

This paper is concerned with the development of an algorithm for general bilinear programming problems. Such problems find numerous applications in economics and game theory, location theory, nonlinear multi-commodity network flows, dynamic assignment and production, and various risk management problems. The proposed approach develops a new Reformulation-Linearization Technique (RLT) for this problem, and imbeds it within a provably convergent branch-and-bound algorithm. The method first reformulates the problem by constructing a set of nonnegative variable factors using the problem constraints, and suitably multiplies combinations of these factors with the original problem constraints to generate additional valid nonlinear constraints. The resulting nonlinear program is subsequently linearized by defining a new set of variables, one for each nonlinear term. This RLT process yields a linear programming problem whose optimal value provides a tight lower bound on the optimal value to the bilinear programming problem. Various implementation schemes and constraint generation procedures are investigated for the purpose of further tightening the resulting linearization. The lower bound thus produced theoretically dominates, and practically is far tighter, than that obtained by using convex envelopes over hyper-rectangles. In fact, for some special cases, this process is shown to yield an exact linear programming representation. For the associated branch-and-bound algorithm, various admissible branching schemes are discussed, including one in which branching is performed by partitioning the intervals for only one set of variables x or y, whichever are fewer in number. Computational experience is provided to demonstrate the viability of the algorithm. For a large number of test problems from the literature, the initial bounding linear program itself solves the underlying bilinear programming problem.This paper was presented at the II. IIASA Workshop on Global Optimization, Sopron (Hungary), December 9–14, 1990.     

The Relationship between the Relative Solvating Power of Electrolytes and Shuttling Effect of Lithium Polysulfides in Lithium–Sulfur Batteries

Relative solvating power, that is, the ratio of the coordination ratios between a solvent and the reference solvent, was used to probe the quantitative structure–activity relationship of electrolyte solvents and the lithium polysulfide (LiPS) dissolution in lithium–sulfur batteries. Internally referenced diffusion‐ordered nuclear magnetic resonance spectroscopy (IR‐DOSY) was used to determine the diffusion coefficient and coordination ratio, from which the relative solvating power can be easily measured. The higher the relative solvating power of an ethereal solvent, the more severe will be the LiPS dissolution and the lower the coulombic efficiency of the lithium–sulfur battery. A linear relationship was established between the logarithm of relative solvating power of a solvent and the degree of LiPS dissolution, rendering relative solvating power an important parameter in choosing the electrolyte solvent for lithium–sulfur batteries.     

Reversible Redox Chemistry of Azo Compounds for Sodium‐Ion Batteries

Sustainable sodium‐ion batteries (SSIBs) using renewable organic electrodes are promising alternatives to lithium‐ion batteries for the large‐scale renewable energy storage. However, the lack of high‐performance anode material impedes the development of SSIBs. Herein, we report a new type of organic anode material based on azo group for SSIBs. Azobenzene‐4,4′‐dicarboxylic acid sodium salt is used as a model to investigate the electrochemical behaviors and reaction mechanism of azo compound. It exhibits a reversible capacity of 170 mAh g^?1 at 0.2C. When current density is increased to 20C, the reversible capacities of 98 mAh g^?1 can be retained for 2000 cycles, demonstrating excellent cycling stability and high rate capability. The detailed characterizations reveal that azo group acts as an electrochemical active site to reversibly bond with Na⁺. The reversible redox chemistry between azo compound and Na ions offer opportunities for developing long‐cycle‐life and high‐rate SSIBs.     

Synthesis and ionic conductivity of mixed substituted polysiloxanes with oligoethyleneoxy and cyclic carbonate substituents

New comb polysiloxanes with mixed substituents were synthesized by hydrosilylation of PMHS with 4-allyloxymethyl-[1,3]dioxolan-2-one and tri(ethylene glycol) allyl methyl ether (AMPEO₃). The effect of the incorporation of carbonate groups on ionic transport, viscosity and thermal properties has been investigated. When doped with lithium bis(trifluorosulfonyl) imide, LiTFSI, the mixed substituted polysiloxane polymers with varying carbonate content all exhibited conductivity higher than those for the polysiloxanes with pure carbonate or pure oligoethyleneoxy substituents. The maximum ambient conductivity in this series was 1.62× 10⁻⁴ S/cm, occurring for the polymer containing 8.5% polar carbonate groups at a doping level of EO/LiTFSI = 15. The impedance measurement results showed that polymers containing larger amounts of carbonate groups exhibited lower conductivity, probably because of their increased viscosity and higher glass transition temperature. The conduction mechanism for these new comb polymers obeys free volume theory, as indicated by conductivity data fit to the VTF equation. We dedicate this paper to Professor Dick Jones, polysilane pioneer and valued friend.     

Carbon Paste Electrode Bulk-Modified with the Conducting Polymer Poly(1,8-Diaminonaphthalene): Application to Lead Determination

Carbon paste electrodes modified with conducting polymers for sensitive and selective determination of lead are presented. A novel method for generating a reproducible polymer-coated electrode surface is developed. We prove that 1,8-diaminonaphthalene (1,8-DAN) mixed with a carbon paste electrode leads to a conducting polymer in acidic medium while, in the same medium, this polymer is known to be non-conducting on platinum electrode. The electrode behaviour of poly(1,8-DAN), electropolymerised into carbon paste, was investigated by cyclic voltammetry in the presence of the ferri-ferrocyanide couple.A carbon paste electrode modified with poly(1,8-DAN) was used to determine Pb²⁺ in aqueous solutions. Pb²⁺ ions were firstly complexed and then electrochemically deposited by a potential step to –0.9V. The accumulated lead after reduction was anodically stripped by differential pulse voltammetry. Different parameters, such as pH of the solution, preconcentration time, and electropolymerisation procedures were studied.For a preconcentration time of ten minutes, the calibration graph was linear from 40 to 2070ngmL^–1 with r²=0.998. The detection limit was found to be 30ngmL^–1, and the relative standard deviation was 6%.     

Synthesis,biological evaluation,theoretical investigations,docking study and ADME parameters of some 1,4-bisphenylhydrazone derivatives as potent antioxidant agents and acetylcholinesterase inhibitors

Molecular Diversity - Five 1,4-bisphenylhydrazone derivatives (1–5) were successfully synthesized and evaluated for their antioxidant and acetylcholinesterase inhibitory activities. The...     

(E)‐4,4′‐Bis(1,3‐benzoxazol‐2‐yl)stilbene at 150 and 375 K

The title compound, a chromophore of formula C₂₈H₁₈N₂O₂, crystallizes with the molecule lying on an inversion centre to give one‐half of a crystallographically independent molecule in the asymmetric unit. The molecule is almost planar, with slight deviation of the benzene rings from the mean molecular plane. The structure is characterized by a herringbone packing arrangement arising from C—H...π and π–π intermolecular interactions. The benzoxazole group is disordered between two orientations, with occupancy factors of 0.669 (10) and 0.331 (10) at 150 K [0.712 (7) and 0.288 (7) at 375 K].