Simple design of an aligned transparent biofilm by magnetic particles and its cellular study

The aim of this study was to produce aligned biodegradable films. In this study, we used magnetic microparticles and strong magnetic field for orientation of gelatin gels. The samples were evaluated by microscopic analyses and cell culture assays with Schwann cells. Results of structural analyses showed a good arrangement and orientation of films under strong magnetic field with movement of magnetite particles. Cellular experiments showed a good cell adhesion and orientation on the designed films compared with those on unmodified ones. This aligned guide appears to have the right organization for testing in vivo nerve tissue engineering studies. Copyright © 2016 John Wiley & Sons, Ltd.     

Treated carbon felt as electrode material in vanadium redox flow batteries: a study of the use of carbon nanotubes as electrocatalyst

Electrodes for large-scale usage in vanadium redox flow battery are usually fabricated without any electrocatalyst due to the lack of good, viable options. The best performance is achieved of carbon-based materials. Recently, some researchers have been reported regarding the use of carbon nanotube as the electrocatalyst in the vanadium redox flow batteries. However, these researches have been carried out without making any comparison between the performance of the traditional method and the carbon nanotube electrocatalyst. In the present study, the loading of multi-walled carbon nanotube, the acid–heat treatment, and their combination were used to modify the carbon felt electrode to be applied in the vanadium redox flow battery. The obtained results showed better electrochemical properties for acid–heat-treated carbon felt electrode compared to the carbon nanotube-loaded one. The best electrode was obtained for using in a vanadium redox flow battery in terms of electrochemical and surface properties after applying a combination of two modification strategies. Applying this proposed method in modification of the carbon felt electrode increased its hydrophilicity more than 17 times and its capability to absorb VOSO₄ solution more than eight times. Also, the charge transfer resistance of a modified electrode, by the combination of the carbon nanotube and the acid–heat treatment, significantly decreased in both positive and negative poles of vanadium redox flow battery. Consequently, the exchange current density enhanced more than 100- and 175-fold in positive and negative poles, respectively, in comparison with carbon felt electrode.     

Comments on “On the Indefinite Quadratic Fractional Optimization with Two Quadratic Constraints”

In this note, with reference to a paper by the same authors, we add an extra assumption, correct the statement of Lemma 2.1 and subsequently correct the proof of this lemma.     

Novel Co/graphene oxide and Co/nanoporous graphene catalysts for Fischer–Tropsch reaction

For the first time, nanoporous graphene and graphene oxide sheets have been synthesized and used as supports for preparation of Co/graphene-based catalysts to evaluate their efficiency in Fischer–Tropsch synthesis and for comparison with the performance of Co/Al₂O₃ to study the effects of the carbon supports on the reaction. Outstanding results were obtained compared with the alumina counterpart. Application of nanoporous graphene yielded heavier hydrocarbons compared with the Co/Al₂O₃ catalyst, possibly due to the high surface area and intrinsic properties of the carbon nanostructures as effective hydrogen carriers. Use of graphene oxide and nanoporous graphene supports also resulted in high CO₂ selectivity. However, the graphene-supported catalysts displayed lower C₁–C₄ hydrocarbon selectivity compared with the Al₂O₃ catalyst.     

3-Naphthylindoles as new promising candidate antioxidant,antibacterial, and antibiofilm agents

Research on Chemical Intermediates - Indole derivatives have attracted significant attention in organic synthesis and bioactivity research owing to their substantial biological activity. In the...     

Coordination compounds of 4,5,6,7-tetrahydro-1H-indazole with Cu(II), Co(II) and Ag(I): structural,antimicrobial, antioxidant and enzyme inhibition studies

Coordination behavior of 4,5,6,7-tetrahydro-1H-indazole (H-Ind) with Cu(II), Co(II), and Ag(I) was studied. The ligand affords complexes bearing different geometries depending upon the metal and anion present in the starting salts. Five compounds with different structural perspectives, trans-[CuCl₂(H-Ind)₄] (1), trans-[CuBr₂(H-Ind)₄] (2), trans-[Cu(CH₃COO)₂(H-Ind)₂] (3), trans-[CoCl₂(H-Ind)₄] (4), and [Ag(H-Ind)₂]NO₃ (5), were obtained. The ligand adopts tetrahydro-1H-indazole isomeric form in Cu(II) and Co(II) complexes and with Ag(I) ion the same ligand adopts tetrahydro-2H-indazole form. In the case of sterically demanding acetate counter ion in contrast to Cl or Br, the Cu(II) ion accepts two equivalents of the ligand and four-coordinated square planar complex was obtained. With AgNO₃, the expected complex was obtained. The yield of reactions was >80% and all complexes were obtained as crystalline material from the reaction mixtures. Their structures were determined by X-ray diffraction and all complexes were tested for antibacterial (Enterobacter sakazkii, Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniea), antifungal (Aspergillus flavus, Aspergillus fumegatus, Aspergillus nigar, Fusarium oxysporium), and antioxidant (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH)) activities. The same were also tested as inhibitors against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) .     

Ni(II) and V(IV) Schiff base complexes derived from 2,2′-dimethylpropandiamine: the crystal structure,electrochemical properties and catalytic activities in oxidation of sulfides

Tetradentate Schiff base (H₂L) derived from 2,2′-dimethylpropandiamine and its nickel(II) and oxo-vanadium(IV) complexes (NiL, VOL) have been prepared and characterized. The crystal structure of NiL has been determined. The reported structure contains two molecules of the complex revealing slightly different conformation and the coordination sphere around nickel is distorted square planar. The electrochemical properties of the Ni and oxo-vanadium Schiff base complexes were investigated in CH₃CN by cyclic voltammetry. The catalytic activities of the complexes were studied in the oxidation of sulfides in ethanol. Under the optimized reaction conditions, in the presence of NiL, 89% and VOL, 100% conversion of methyl phenyl sulfide with 100% selectivity for sulfoxide were obtained.     

Innovative amphiphilic cellulose nanobiostructures: Physicochemical,spectroscopic, morphological,and hydrophilic/lipophilic properties

The amphiphilic character of cellulosic copolymers offers the opportunity to employ their derivatives as novel bio-friendly stable amphiphilic agents. It can be speculated that the synthesized nanobiostructures with hydrophilic and hydrophobic segments will have micellar features. Our investigations, for the first time, demonstrate that the amphiphilic nature of the synthesized macromolecules based on hydrophobic cellulose triacetate (CTA) and hydroxyl terminated oligomeric species of CTA (HCTA) by using hydrophilic polyethylene glycol (PEG) with M_n 600 and 2000 D as CTA-g-PEG, 600; CTA-g-PEG, 2000; HCTA-b-PEG, 600; and HCTA-b-PEG, 2000. The characteristic features of the copolymers were determined by XRD, differential scanning calorimeter, ¹H NMR, FTIR, GPC, dynamic light scattering measurements, and transmission electron microscopy. In addition, their critical micelle concentrations were evaluated. The obtained results indicated that the hydrophobic blocks make a significant influence on the micellar characteristics of the surfactants. A comparison of the micellar behavior of a hydrophobic species, like pyrene, incorporated in the synthesized systems indicated that the incorporation content of the surfactants is influenced by the hydrophobic and hydrophilic chain lengths. Therefore, it is possible to design the diversity of the surfactants based on various hydrophilic/lipophilic balance.     

A New Practical Route to ZSM‐5 Nanoparticles and Optimization of Synthetic Parameters through D‐optimal Design of Experiments

A D‐optimal experimental design with three levels of SiO₂/Al₂O₃, template/SiO₂, H₂O/SiO₂, Na₂O/SiO₂ and TPABr/TPAOH ratio parameters has been used to optimize the experimental parameters by an analysis of variances (ANOVA). The effects of these ratios in the initial synthetic mixture on the size of the ZSM‐5 zeolite nanoparticles have been studied. XRD and FE‐SEM analyses were used to characterize synthetic samples. Fischer test results showed that H₂O/SiO₂ and TPABr/TPAOH ratios are the most and least effective parameters, respectively, in the range studied. The most important two‐way interaction variables were the interaction of template/SiO₂ and TPABr/TPAOH molar ratios. The average particle size was in the 34–79 nm range. Furthermore, a mathematical model for the synthesis of ZSM‐5 zeolite nanoparticles was derived using experimental results. The optimized gel composition is as follows: SiO₂/Al₂O₃₌91.20, template/SiO₂₌0.16, H₂O/SiO₂₌40.42, Na₂O/SiO₂₌0.0147 and TPABr/TPAOH=0.