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.     

Characteristics of the breakup and fragmentation of an electrohydrodynamic melt jet

In this study, the breakup of a melt jet into a viscous medium is investigated in the presence of an intense electric field. Fragmentation of the melt jet occurs due to both hydrodynamic and electrohydrodynamic (EHD) forces within two kinds of silicone oil of different viscosities. The size and shape characteristics of the produced particles have been studied using SEM images, and the particle size distributions were found to exhibit considerable variations when a voltage was applied and when both the viscosity and temperature of the base fluid were changed. The morphologies of the particles were also affected by the same parameters. For instance, by applying EHD force, significant enhancements in size reduction and increased roundness of the particles occurred. The breakup process of the melt jet was found to be dominant by hydrodynamic or electrohydrodynamic instabilities, depending on the situation. Governing mechanisms (instability) in the cases of pure hydrodynamic and electrohydrodynamic fragmentations are discussed.     

Metal ion adsorption from wastewater by g-C3N4 modified with hydroxyapatite: a case study from Sarcheshmeh Acid Mine Drainage

Research on Chemical Intermediates - Hydroxyapatite (Hap) modified graphitic carbon nitride (g-C3N4) powders (Hap/g-C3N4) were prepared and characterized. The sorption activities of g-C3N4 and...     

On Indefinite Quadratic Optimization over the Intersection of Balls and Linear Constraints

Journal of Optimization Theory and Applications - In this paper, we study the minimization of an indefinite quadratic function over the intersection of balls and linear inequality constraints...     

Membrane protected conductive polymer as micro‐SPE device for the determination of triazine herbicides in aquatic media

A micro‐SPE technique was developed by fabricating a rather small package including a polypropylene membrane shield containing the appropriate sorbent. The package was used for the extraction of some triazine herbicides from aqueous samples. Solvent desorption was subsequently performed in a microvial and an aliquot of extractant was injected into GC‐MS. Various sorbents including aniline‐ortho‐phenylene diamine copolymer, newly synthesized, polypyrrole, multiwall carbon nanotube, C18 and charcoal were examined as extracting media. Among them, conductive polymers exhibited better performance. Influential parameters including extraction and desorption time, desorption solvent and the ionic strength were optimized. The developed method proved to be rather convenient and offers sufficient sensitivity and good reproducibility. The detection limits of the method under optimized conditions were in the range of 0.01–0.04 ng/mL. The RSDs at a concentration level of 0.1 ng/mL were obtained between 4.5 and 9.3% (n=5). The calibration curves of analytes showed linearity in the range of 0.05–10 ng/mL. The developed method was successfully applied to the extraction of selected triazines from real water samples. The whole procedure showed to be conveniently applicable and quite easy to manipulate.     

Synthesis,characterization and application of pH-sensitive CoFe2O4/reduced graphene oxide (RGO) nanocomposite in a circulated photocatalytic reactor for Reactive Red 141 removal of wastewaters

Research on Chemical Intermediates - In the present study, CoFe2O4/reduced graphene oxide nanocomposite (CoFe2O4/RGO) has been synthesized, characterized and applied as a photocatalyst for Reactive...     

Numerical Investigation of Effect of Driving Voltage Pulse on Low Pressure 90%Ar–10%Cl<Subscript>2</Subscript> Dielectric Barrier Discharge

An one-dimensional fluid model is used to study the physico-chemical properties of a 90%Ar–10%Cl₂ plasma produced in dielectric barrier discharges under different driving voltages. The spatio-temporal characteristics of the discharge are obtained by applying a sinusoidal voltage with different amplitudes and frequencies from 350 to 1200 V and 10 to 19 kHz, respectively. As the voltage amplitude increases the plasma electronegativity and plasma radiations are increased and their radiations move toward the cathode vicinity. With decreasing frequency, the plasma radiations move toward the anode vicinity and the plasma electronegativity and its radiations are enhanced. At low voltage amplitudes, plasma most radiates VUV photons while UV radiations take place at higher voltage amplitudes.     

Establishment of Aromatic Pairs at the Surface of Chondroitinase ABC I: the Effect on Activity and Stability

Removal of chondroitin sulfate glycosaminoglycan (GAG) chains with chondroitinase ABC I (chABC I) in CNS injury models promotes both saxon regeneration and plasticity. It has been suggested that direct interaction between an aromatic pair appears to contribute about ??1.3 kcal/mol to the stability of a folded protein, so introducing an aromatic pair by point mutation might increase the enzyme activity and thermal stability as in the case of mesophilic xylanase, although using this approach destabilized T4 lysozyme. In this study, we used site-directed mutagenesis to investigate the effect of new aromatic pairs on activity and stability of chABC I. We replaced Ile295, Ser581, and Gly730 adjacent to pre-existing aromatic residues with Tyr to obtain new aromatic pairs, i.e., Tyr295/His372, Tyr576/Tyr581, and Tyr623/Tyr730. Results showed that K_m values of S581Y and G730Y variants decreased relative to wild-type enzyme while their catalytic efficiency (k_cat/K_m) increased but I295Y variant was inactive. Also, long-term and thermal stability of the active mutants was decreased. Fluorescence and circular dichroism studies showed that these mutations resulted in a more flexible enzyme structures: a finding which was confirmed by thermal and limited proteolytic studies. In conclusion, the activity of chABC I can be improved by introducing appropriate aromatic pairs at the enzyme surface. This approach did not provide any promising results regarding the enzyme stability.     

Numerical investigation of conduction pumping of dielectric liquid film using flush-mounted electrodes

Electrohydrodynamic conduction pumping of dielectric liquid films using flush-mounted electrodes is investigated numerically. Two major factors consisting of the ion mobility difference and electrodes’ configuration can affect the conduction pumps. The relative importance of these factors on the hydrodynamic behavior has been studied at different configurations of flush-mounted electrodes for conduction pumping of various dielectric liquids with different electrical properties. Furthermore, the effect of heterocharge layer structure on the hydrodynamic behavior of conduction pump has been studied. The electrical behavior and flow patterns of dielectric liquids with real measured mobilities are compared with the experimental results, and new features of conduction pumping are found. The numerical results indicate that in the various operating conditions, the flow direction is dictated by the dominant factor.