Protein adsorption capability of zinc ferrite nanoparticles formed by a low-temperature solution-based process

We report successful synthesis of zinc ferrite nanoparticles (ZFs) by a facile low-temperature (90 °C) solution-based process from ferric nitrate nonahydrate and zinc nitrate hexahydrate precursors in presence of hydrazine hydrate. X-ray diffraction analysis and transmission electron microscopy confirmed the presence of ZFs, which were further characterized by Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric measurements for identification of characteristic chemical bond vibrations and thermal weight loss behavior, respectively. Measurements of magnetic properties at room temperature revealed that the sample showed quite high saturation magnetization (22.0 emu/g at ~19,200 G), implying the presence of less impurities/surface defects in the ZFs. The material also showed zero coercivity as a soft-magnetic material. The protein adsorption performance of the ZFs was checked using bovine serum albumin (BSA) as model protein. Excellent protein adsorption capacity of 210 mg/g (close to the value of 218.81 mg/g calculated using the Langmuir model) for BSA concentration of 0.3 mg/mL was obtained at optimized solution pH of 5. This simple process could be adopted for synthesis of different magnetic nanomaterials for use in biomedical applications.     

Biologically sustainable rubber resin and rubber‐filler promoter: a precursor study

Enthused by the ever growing demand for sustainable and green based materials in responding to applications based on macromolecules, an attempt was made in seeking a bio‐resin (Terpene). Herein, we report the functionalization of bio‐resin with natural rubber (NR) to produce new sustainable and greener functional polymer. Bio‐resin functionalized NR was prepared by melt mixing using di(2‐tert butyl peroxy isopropyl) benzene initiator. Structure elucidation of the bio‐resin functionalized NR was established by proton nuclear magnetic resonance and Fourier transform infrared spectroscopy, respectively. Bio‐resin functionalized NR facilitates the augmented interaction with highly dispersible silica. Amended state of highly dispersible silica dispersion has been achieved in the absence of toxic process oil, expensive silane coupling agent and conventionally used zinc oxide. Remarkable improvement in overall properties corroborated with various meticulous characterization including nanoindentation, rheological, physico‐mechanical and small angle X‐ray scattering using Becauge model, etc. The dynamic mechanical properties of the greener polymer demonstrated low rolling resistance coupled with high traction. More decisively, the macromolecule system toned up sparingly in the presence of the bio‐resin. Our contribution facilitates a novel avenue to develop sustainable high‐performance elastomeric macromolecule. Copyright © 2017 John Wiley & Sons, Ltd.     

Dirhenium(III,III) trithiocarbamato complexes: experimental and theoretical investigation

The green colored trithiocarbamato complexes of dirhenium(III,III) of type [Re₂(μ-η²-SL_R)₂(η²-L_R)₃][ReO₄] (4(L_R)), where L_R represents the dithiocarbamato ligands [L_R?=?S₂CNEt₂, 4(L_Et) and S₂CN(CH₂)₄, 4(L_Pyr)], have been synthesized in moderate yield by reacting Re₂(μ-O₂CCH₃)₄Cl₂ (1) and sodium salt of diethyldithiocarbamate or pyrrolidinedithiocarbamate in boiling ethanol under nitrogen atmosphere. The spectral (IR, UV–vis, NMR) and electrochemical properties of the complexes are reported. The identity of complex 4(L_Et) has been established by single-crystal X-ray structure determination. The density functional theory (DFT) calculations rationalized the electronic structure of complexes 4(L_R) in comparison with dithiocarbamato complexes of dirhenium(II,II) and dirhenium(III,II). The absorption spectra of the 4(L_R) complexes are scrutinized by the time-dependent DFT analysis.

     

A Reusable Efficient Green Catalyst of 2D Cu-MOF for the Click and Knoevenagel Reaction

[Cu(CPA)(BDC)]_n (CPA = 4-(Chloro-phenyl)-pyridin-4-ylmethylene-amine; BDC = 1,4-benzenedicarboxylate) has been synthesized and structurally characterized by single crystal X-Ray diffraction measurement. The structural studies establish the copper (II) containing 2D sheet with (4,4) square grid structure. The square grid lengths are 10.775 and 10.769 Å. Thermal stability is assessed by TGA, and subsequent PXRD data establish the crystallinity. The surface morphology is evaluated by FE-SEM. The N₂ adsorption−desorption analysis demonstrates the mesoporous feature (∼6.95 nm) of the Cu-MOF. This porous grid serves as heterogeneous green catalyst with superficial recyclability and thermal stability and facilitates organic transformations efficiently such as, Click and Knoevenagel reactions in the aqueous methanolic medium.     

Synthesis,crystal structures and spectroscopic properties of two Zn(II) Schiff’s base complexes of pyridoxal

Two mononuclear zinc(II) complexes, [ZnL¹H₂Cl]Cl·2H₂O (1·Cl·2H₂O) and [ZnL²HCl]·H₂O (2·H₂O) (L¹H₂ and L²H₂ are N,N′-bis(pyridoxylidene)ethylenediamine and N,N′-bis(pyridoxylidene)1,3-propanediamine, respectively) have been synthesized and characterized by elemental analysis, FT-IR, fluorescence spectroscopy, TG–DTA and single crystal X-ray diffraction studies. The Zn(II) ion in complex 1 have a square pyramidal geometry with appreciable distortion towards trigonal bipyramid, whereas in 2 it has a geometry which is near the midpoint of square pyramid and trigonal bipyramid. The zinc atom is coordinated by two imine nitrogens, two phenolic oxygens and one chloride ion. The Zn(II) complexes show emission at 462 nm when excited at their lowest energy absorption at 372 nm.     

Nested Cartesian grid method in incompressible viscous fluid flow

In this work, the local grid refinement procedure is focused by using a nested Cartesian grid formulation. The method is developed for simulating unsteady viscous incompressible flows with complex immersed boundaries. A finite-volume formulation based on globally second-order accurate central-difference schemes is adopted here in conjunction with a two-step fractional-step procedure. The key aspects that needed to be considered in developing such a nested grid solver are proper imposition of interface conditions on the nested-block boundaries, and accurate discretization of the governing equations in cells that are with block-interface as a control-surface. The interpolation procedure adopted in the study allows systematic development of a discretization scheme that preserves global second-order spatial accuracy of the underlying solver, and as a result high efficiency/accuracy nested grid discretization method is developed. Herein the proposed nested grid method has been widely tested through effective simulation of four different classes of unsteady incompressible viscous flows, thereby demonstrating its performance in the solution of various complex flow–structure interactions. The numerical examples include a lid-driven cavity flow and Pearson vortex problems, flow past a circular cylinder symmetrically installed in a channel, flow past an elliptic cylinder at an angle of attack, and flow past two tandem circular cylinders of unequal diameters. For the numerical simulations of flows past bluff bodies an immersed boundary (IB) method has been implemented in which the solid object is represented by a distributed body force in the Navier–Stokes equations. The main advantages of the implemented immersed boundary method are that the simulations could be performed on a regular Cartesian grid and applied to multiple nested-block (Cartesian) structured grids without any difficulty. Through the numerical experiments the strength of the solver in effectively/accurately simulating various complex flows past different forms of immersed boundaries is extensively demonstrated, in which the nested Cartesian grid method was suitably combined together with the fractional-step algorithm to speed up the solution procedure.     

Separation of NCA 88Zr from proton irradiated natY target: a novel approach using low cost bio-sorbent potato peel charcoal

Separation of no-carrier-added (NCA) ⁸⁸Zr from natural yttrium target irradiated with proton beam has been studied using nature-resourced material, potato peel, which is a commonly available domestic waste. Here, an attempt has been undertaken to exploit natural resource as separating agent. Good separation of NCA ⁸⁸Zr from bulk Yttrium target could be achieved at 0.01 M HCl concentration, when extraction was carried out using 20 mg potato peel charcoal—a natural bio-sorbent. ⁸⁸Zr was extracted in the solid phase leaving behind bulk Y in the aqueous phase.

     

Understanding the Reactivity and Selectivity of Fluxional Chiral DMAP-Catalyzed Kinetic Resolutions of Axially Chiral Biaryls

Fluxional chiral DMAP-catalyzed kinetic resolutions of axially chiral biaryls were examined using density functional theory. Computational analyses lead to a revised understanding of this reaction in which the interplay of numerous non-covalent interactions control the conformation and flexibility of the active catalyst, the preferred mechanism, and the stereoselectivity. Notably, while the DMAP catalyst itself is confirmed to be highly fluxional, electrostatically driven π⋅⋅⋅π⁺ interactions render the active, acylated form of the catalyst highly rigid, explaining its pronounced stereoselectivity.