Accelerating the electron transfer of choline oxidase using ionic-liquid/NH2-MWCNTs nano-composite

A nano-composite consisting of amine functionalized multi-walled carbon nanotubes and a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) was prepared and used for modification of glassy carbon electrode. By immobilizing choline oxidase (ChOx) on the modified electrode, the enzyme direct electron transfer has been achieved. The modified electrode exhibited a pair of well-defined cyclic voltammetric peaks at a formal potential of ?0.395?V versus Ag/AgCl in 0.2?M phosphate buffer solution at pH 7.0. This peak was characteristic of ChOx-FAD/FADH₂ redox couple. The electrochemical parameters such as charge transfer coefficient (??) and apparent heterogeneous electron transfer rate constant (k _s) were estimated to be 0.36 and 2.74?s^?1, respectively. When the enzyme electrode was examined for the detection of choline, a relatively high sensitivity (2.59???A?mM^?1) was obtained. Under the optimized experimental conditions, choline was detected in the concentration range from 6.9?×?10^?3 to 6.7?×?10^?1?mM with a detection limit of 2.7???M. The peak currents of ChOx were reasonably stable and retained 90% of its initial current after a period of 2?months.     

Balanced fuzzy particle swarm optimization

In the present study an extension of particle swarm optimization (PSO) algorithm which is in conformity with actual nature is introduced for solving combinatorial optimization problems. Development of this algorithm is essentially based on balanced fuzzy sets theory. The classical fuzzy sets theory cannot distinguish differences between positive and negative information of membership functions, while in the new method both kinds of information “positive and negative” about membership function are equally important. The balanced fuzzy particle swarm optimization algorithm is used for fundamental optimization problem entitled traveling salesman problem (TSP). For convergence inspecting of new algorithm, method was used for TSP problems. Convergence curves were represented fast convergence in restricted and low iterations for balanced fuzzy particle swarm optimization algorithm (BF-PSO) comparison with fuzzy particle swarm optimization algorithm (F-PSO).     

Cyclopalladated complexes of 2-phenylaniline and their catalytic activity in Suzuki and Heck reactions under mild conditions

A series of palladium complexes bearing monodentate and bidentate ligands were applied in the Suzuki reaction of aryl halides and the Heck reaction of styrene with phenylboronic acid. The complexes were found to be effective catalysts for these reactions affording the cross-coupled products in moderate to excellent yields.     

Hydrazine trapping ability of Si12C12 fullerene-like nanoclusters: a DFT study

Structural Chemistry - In this study, the nondissociative hydrazine (N2H4) adsorption on the surface of Si12C12 nanoclusters have been investigated using density functional theory at...     

Axisymmetric stagnation flow obliquely impinging on a moving circular cylinder with uniform transpiration

Laminar stagnation flow, axisymmetrically yet obliquely impinging on a moving circular cylinder, is formulated as an exact solution of the Navier–Stokes equations. Axial velocity is time‐dependent, whereas the surface transpiration is uniform and steady. The impinging free stream is steady with a strain rate k?. The governing parameters are the stagnation‐flow Reynolds number Re=k?a²/2ν, and the dimensionless transpiration S=U₀/k?a. An exact solution is obtained by reducing the Navier–Stokes equations to a system of differential equations governed by Reynolds number and the dimensionless wall transpiration rate, S. The system of Boundary Value Problems is then solved by the shooting method and by deploying a finite difference scheme as a semi‐similar solution. The results are presented for velocity similarity functions, axial shear stress and stream functions for a variety of cases. Shear stresses in all cases increase with the increase in Reynolds number and suction rate. The effect of different parameters on the deflection of viscous stagnation circle is also determined. Copyright © 2010 John Wiley & Sons, Ltd.     

Mechanism of deleading of silicate glass by 0.5 N HNO3

Mechanism of removal of lead from silicate glass containing 68.5 wt% PbO by 0.5 N HNO₃ was investigated by incorporation of the chemical-analyses/weight-loss data into shrinking-core model (SCM) and minimization of the difference. Scanning electron microscopy (SEM), emission spectrometry with inductively coupled plasma (ICP), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS) were used to determine the compositional changes of the lead-silicate glass (LSG) samples. Dual inter-diffusion chemical reaction mechanisms having respective activation energies of 83.49 and 47.80 kJ/mol dominated the deleading process.     

Design,synthesis, biological evaluation,and docking study of new acridine-9-carboxamide linked to 1,2,3-triazole derivatives as antidiabetic agents targeting α-glucosidase

A new series of acridine-9-carboxamide-1,2,3-triazole derivatives 7a-m were designed, synthesized, and evaluated as novel α-glucosidase inhibitors. Acridine-9-carboxamide-1,2,3-triazole scaffold has been designed by combination of effective moieties from potent α-glucosidase inhibitors. Most of the synthesized compounds were more potent than standard inhibitor acarbose. Among the title compounds, the most potent compounds were compounds 7j , 7k , and 7a with IC₅₀ values of 120.2 ± 1.0, 151.1 ± 1.4, and 157.6 ± 1.6 μM, respectively (IC₅₀ value of acarbose = 750.0 ± 10.0 μM). Docking study of the most potent compounds demonstrated that these compounds formed stable complexes with α-glucosidase active site. Anti-α-amylase assay of compounds 7j , 7k , and 7a was performed and no activity was observed. in vitro cytotoxicity assay of the latter compounds revealed that these compounds were not cytotoxic toward human normal (HDF) and cancer (MCF-7) cell lines. ADME and toxicity prediction of compounds 7j , 7k , and 7a were also performed.     

One-pot synthesis of spiro-acridine/indoline and indoline derivatives using (MWCNTs)-COOH/La2O3 hybrid as an effective catalyst

Spiro-acridine/indoline and indoline derivatives were synthesized by the three-component reaction of isatin, dimedone, and amines or amino acids in the presence of acid-functionalized multiwalled carbon nanotubes/La₂O₃ (MWCNTs)-COOH/La₂O₃ hybrid (5 mol%) as a highly efficient catalyst in ethanol. The assigned structure was further established by CHN analysis, NMR, and FTIR spectra. (MWCNTs)-COOH/La₂O₃ was fabricated by the reaction of functionalized (MWCNTs)-COOH and La(NO₃)₃.6H₂O in acetic acid. Synthesis of La₂O₃ nanoparticles and their conjugation on the surface of MWCNT have been confirmed by FTIR, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy.     

Analytical and experimental analyses of nonlinear vibrations in a rotary inverted pendulum

Nonlinear Dynamics - We consider a 2-layer quasi-geostrophic ocean model where the upper layer is forced by a steady Kolmogorov wind stress in a periodic channel domain, which allows to...