Facile synthesis of monodispersed Pd nanocatalysts decorated on graphene oxide for reduction of nitroaromatics in aqueous solution

Research on Chemical Intermediates - We synthesized the reproducible heterogeneous catalyst of graphene oxide (GO)-supported palladium nanoparticles (NPs) via a simple and green process. The...     

Synthesis of magnetic nanoparticle‐based molecularly imprinted polymer as a selective sorbent for efficient extraction of ezetimibe from biological samples

In the present study, a novel and efficient adsorbent constructed of molecularly imprinted polymer on the surface of modified magnetic nanoparticles with oleic acid (MNPs) was applied for the selective extraction of ezetimibe. The magnetic molecularly imprinted polymer (MMIP) was polymerized at the surface of modified MNPs using methacrylic acid as functional monomer, ezetimibe as template and ethylene glycol dimethacrylate as cross‐linker. The resulting MMIP showed high adsorption capacity, good selectivity and fast kinetic binding for the template molecule. It was characterized by Fourier transform infrared analysis, scanning electron microscopy and transmission electron microscopy methods. The maximum adsorption capacity of MMIP was obtained as 137.1 mg g^?1 and it took about 20 min to achieve the equilibrium state. The adsorption model of the adsorbent was fitted with the Freundlich and Langmuir isotherm equations. The assay exhibited a linear range of 0.003–20.000 mg L^?1 for ezetimibe with a correlation coefficient of 0.995. The relative standard deviations for the recoveries were <5.2. The method was also examined for the analysis of ezetimibe in the biological samples.     

New transition metal complexes of 9,10‐phenanthrenequinone p‐toluyl hydrazone Schiff base: Synthesis,spectroscopy, DNA and HSA interactions,antimicrobial, DFT and docking studies

The new complexes of Cu (II) and Ni (II) of a tridentate Schiff base ligand derived from 9,10‐phenanthrenequinone and p‐toluic hydrazide have been synthesized and characterized by elemental analysis, electrical conductometry, FT‐IR, Mass, NMR and UV–Vis. The DFT calculations were carried out at B3LYP/6‐31G*(d) level for the determination of the optimized structure of the ligand and its complexes. The as‐synthesized compounds were screened for their antimicrobial activity. Also, their binding behavior with fish salmon‐DNA (FS‐DNA) and human serum albumin (HSA) were studied by different kinds of spectroscopic and molecular modeling techniques. The fluorescence data at different temperatures were applied in order to estimate the thermodynamics parameters of interactions of ligand and its complexes with DNA and HSA. The results showed that the as‐made compounds could bind to FS‐DNA and HSA via the groove binding as the major binding mode. According to molecular docking calculation and competitive binding experiments, these compounds bind to the minor groove of DNA and hydrophobic residues located in the subdomain IB of HSA. In addition, the molecular docking results kept in good consistence with experimental data.     

Production of <Superscript>122</Superscript>Sb for the study of environmental pollution

This article presents, ¹²²Sb (T _1/2 = 2.723 days, I _β- = 97.59%) was produced via the ^natSn(p,xn) nuclear process at the AMIRS (Cyclone-30, IBA, Belgium). The electrodeposition experiments were carried out by potassium stannate trihydrate (K₂Sn(OH)₆) and potassium hydroxide. The optimum conditions of the electrodeposition of tin were as follows: 40 g/L ^natSn, 20 g/L KOH, 115 g/L K₂Sn(OH)₆, DC current density of 5 A/dm² with a bath temperature of 75 °C. The electroplated Tin-target was irradiated with 26.5 MeV protons at current of 180 μA for 20 min. Solvent extraction of no-carrier-added ¹²²Sb from irradiated Tin-natural target hydrochloric solution was investigated using di-n-butyl ether (C₈H₁₈O). Yields of about 3.61 MBq/μAh were experimentally obtained.     

Environmental Friendly Synthesis of Novel Isatin Ketal and Isatin Schiff Base Derivatives Using Michael Addition Reaction under Solvent‐Free Conditions

An efficient and simple procedure for the synthesis of novel isatin derivatives is described. Michael addition of aniline Schiff bases of isatin or p‐toluidine Schiff bases of isatin to fumaric esters affords the Michael adduct compounds in good to high yields in the presence of K₂CO₃ and tetrabutylammonium bromide (TBAB) under solvent‐free conditions. Repeating of this reaction about spiro[1,3‐dioxolane‐2,3′‐indol]‐2′(1′H)‐one, as a Michael donor, in the presence of 1,4‐diazabicyclo[2.2.2]octane (DABCO) gives Michael adducts in remarkable yields under the same conditions.     

Forced oscillations and stability analysis of a nonlinear micro-rotating shaft incorporating a non-classical theory

In this paper, the stability and bifurcation analysis of symmetrical and asymmetrical micro-rotating shafts are investigated when the rotational speed is in the vicinity of the critical speed. With the help of Hamilton’s principle, nonlinear equations of motion are derived based on non-classical theories such as the strain gradient theory. In the dynamic modeling, the geometric nonlinearities due to strains, and strain gradients are considered. The bifurcations and steady state solution are compared between the classical theory and the non-classical theories. It is observed that using a non-classical theory has considerable effect in the steady-state response and bifurcations of the system. As a result, under the classical theory, the symmetrical shaft becomes completely stable in the least damping coefficient, while the asymmetrical shaft becomes completely stable in the highest damping coefficient. Under the modified strain gradient theory, the symmetrical shaft becomes completely stable in the least total eccentricity, and under the classical theory the asymmetrical shaft becomes completely stable in the highest total eccentricity. Also, it is shown that by increasing the ratio of the radius of gyration per length scale parameter, the results of the non-classical theory approach those of the classical theory.     

A modified simplex partition algorithm to test copositivity

Journal of Global Optimization - A real symmetric matrix A is copositive if $$x^\top Ax\ge 0$$ for all $$x\ge 0$$ . As A is copositive if and only if it is copositive on the standard simplex,...     

Vibrational analysis of carbon nanotubes using molecular mechanics and artificial neural network

This paper presents the molecular mechanics based finite element modeling of carbon nanotubes (CNTs) and their applications as mass sensors. The beam element with elastic behavior is considered as the bond between the carbon atoms and its properties are obtained using equating continuum and molecular characteristics. The first five natural frequencies of CNTs in cantilever and doubly clamped boundary conditions (BCs) and their corresponding mode shapes are studied in detail. Furthermore, a multilayer perceptron neural network is used to predict the fundamental vibration frequencies of the CNTs with different diameters and lengths. In addition, variations of the natural frequencies of the CNTs with distorted cross sections are investigated. Moreover, the effects of some attached masses with various values on the first three natural frequencies of a considered CNT are studied here.     

Optical solitons in $$$$-dimensions under anti-cubic law of nonlinearity by analytical methods

The present study emphasis to look for new closed form exact solitary wave solutions for the \((n+1)\)-dimensional nonlinear Schrödinger equation using the extended trial equation method (ETEM) and the \(\exp (-\Omega (\eta ))\)-expansion method (EEM) with the help of symbolic computation package maple. As a consequence, the ETEM and EEM are successfully employed and acquired some new exact solitary wave solutions in terms of exponential based functions, hyperbolic based functions, trigonometric based functions and rational based functions. All solutions have been verified back into its corresponding equation with the aid of maple package program. Finally, we believe that the executed method is robust and efficient than other methods and the obtained solutions in this paper can help us to understand the variation of solitary waves in the field of nonlinear optic.     

A Petrov–Galerkin RBF method for diffusion equation on the unit sphere

This paper concerns a numerical solution for the diffusion equation on the unit sphere. The given method is based on the spherical basis function approximation and the Petrov–Galerkin test discretization. The method is meshless because spherical triangulation is not required neither for approximation nor for numerical integration. This feature is achieved through the spherical basis function approximation and the use of local weak forms instead of a global variational formulation. The local Petrov–Galerkin formulation allows to compute the integrals on small independent spherical caps without any dependence on a connected background mesh. Experimental results show the accuracy and the efficiency of the new method.