Recovery and partial purification of thermophilic β-xylosidase derived from recombinant Bacillus megaterium MS941 by aqueous two-phase system

A polymer–salt-based aqueous two-phase system (ATPS) was developed for the effective extraction and purification of extracellular β-xylosidase from the fermentation broth of recombinant Bacillus megaterium MS941. The effect of molecular weight (MW) of polyethylene glycol (PEG), tie-line length (TLL), volume ratio (V_R), crude loading and pH on the recovery performance was evaluated. Under the optimal extraction conditions, β-xylosidase was successfully purified up to 23-fold with a recovery yield of 99% in the bottom salt-rich phase at PEG 4,000/potassium phosphate ATPS comprising TLL of 41.8, V_R of 2.3, crude loading (C_L) of 30% (w/w) at pH 6.     

Wide and multi-band reconfigurable Vivaldi antenna with slot-line feed

This paper presents a Vivaldi antenna. The antenna incorporates a slot-line feed, and is designed to operate in a wideband mode, along with four narrowband modes. The wideband mode extends from 1 to 3 GHz. A series of PIN diode switches is employed to reconfigure between the five different operating modes. Wideband-to-multiband reconfigurations are achieved by adjusting the antenna loading internally, and also by the incorporation of band-stop filters. To obtain the wideband mode, wideband matches load is used. On the other hand, to obtain the narrowband modes, two rectangular slits with narrowband matches load are used. The proposed Vivaldi antenna provides wideband operation. It is also supports operation within the LTE, GSM (L-band), GPS, and WiMAX bands.     

Synthesis and Characterization of Anti-fungus,Anti-corrosion and Self-cleaning Hybrid Nanocomposite Coatings Based on Sol–Gel Process

Anti-corrosion, anti-fungus, and self-cleaning properties of coatings containing ZnO–TiO₂, SiO₂–TiO₂ and SiO₂/TiO₂/ZnO nanoparticles synthesized based on sol–gel precursors using tetra methoxysilane, 3-glycidoxypropyl trimethoxysilane, tetra (n-butyl orthotitanate) and zinc acetate dihydrate were investigated by FESEM, EDAX and TEM analyses. Results indicated uniform dispersion of inorganic nanoparticles in the range of 20–40 nm in size. Anti-corrosion property of the hybrid coating was characterized by EIS measurements and parametrically analyzed in an equivalent circuit when the coating was exposed to salt solution. Results showed that, ZnO and TiO₂ nanoparticles enhance anti-corrosion property of the hybrid coatings. Anti-fungus and anti-bacterial properties of the coatings were determined by diameter of inhibition zone and inhabitation of bacterial growth, respectively. The coating containing ZnO and TiO₂ nanoparticles showed anti-fungus and anti-bacterial properties which were related to their photocatalytic properties. Degradation of methylene blue in aqueous solution was determined by UV–Visible tests which indicated self-cleaning property of the coatings containing ZnO and TiO₂ nanoparticles.     

Selective properties of polyester and cotton/polyester fabrics gamma radiation grafted with different binary mixtures of vinyl monomers

Radiation graft copolymerization of individual and comonomer mixtures of vinyl monomers onto polyester and cotton/polyester fabrics by the mutual method has been investigated. The effect of factors that may affect the grafting yield, such as solvent composition, comonomer mixture composition and radiation dose, have been examined. Suitable conditions that gives the highest graft yield without altering the original properties of the substrates are reported briefly. An attempt was made to determine the graft yield fraction from each monomer in the final graft copolymer in the case of grafting comonomer mixtures by using elemental analysis of nitrogen. Moreover, the results of elemental analysis were used to determine the reactivity ratios of the vinyl monomers. Some selective properties of the graft copolymers of polyester and cotton/polyester with the individual and comonomer mixtures have been investigated. The studied properties are the dye affinity for various dyestuffs and the mechanical properties in terms of tensile strength, elongation at break and Young's modulus. In general and regardless of the system used, grafting improves the dyeability of polyester and cotton/polyester with basic, vat, acid and disperse dyes. Also, it was found that improvement in dyeing and mechanical properties depends essentially on the composition of the graft copolymer and not on the composition of the feed comonomer solution or the total graft yield. © 1999 Society of Chemical Industry     

Optimal per cent by weight of elements in diagnostic quality radiation shielding materials

By increasing the usage of radiation in all aspects of lives, the human body is becoming more exposed to ionising radiation. The purpose of this study is to find the optimal radiation shielding materials to protect humans from the radiation hazards of radiation. Some elements and compounds such as Ag, Bi, Pb, W, BaSO(4) were chosen on the basis of their attenuation coefficients and other characteristics to produce optimised radiation shielding compounds. Multi-objective non-dominated sorting genetic algorithm-II was used to optimise the weight fraction of the elements in compounds based on the dose equivalent rate, shield weight and cost. Consequently, sets of suitable compounds were obtained depending on various applications for energy 0.06 and 0.15 MeV. In addition, optimised lead free compounds were obtained. The results presented in a series of graphs should enable radiation shield designers to choose an appropriate combination according to their requirements.     

Alginate hydrogel as a promising scaffold for dental-derived stem cells: an in vitro study

The objectives of this study were to: (1) develop an injectable and biodegradable scaffold based on oxidized alginate microbeads encapsulating periodontal ligament (PDLSCs) and gingival mesenchymal stem cells (GMSCs); and (2) investigate the stem cell viability, and osteogenic differentiation of the stem cells in vitro. Stem cells were encapsulated using alginate hydrogel. The stem cell viability, proliferation and differentiation to adipogenic and osteogenic tissues were studied. To investigate the expression of both adipogenesis and ontogenesis related genes, the RNA was extracted and RT-PCR was performed. The degradation behavior of hydrogel based on oxidized sodium alginate with different degrees of oxidation was studied in PBS at 37?°C as a function of time by monitoring the changes in weight loss. The swelling kinetics of alginate hydrogel was also investigated. The results showed that alginate is a promising candidate as a non-toxic scaffold for PDLSCs and GMSCs. It also has the ability to direct the differentiation of these stem cells to osteogenic and adipogenic tissues as compared to the control group in vitro. The encapsulated stem cells remained viable in vitro and both osteo-differentiated and adipo-differentiated after 4?weeks of culturing in the induction media. It was found that the degradation profile and swelling kinetics of alginate hydrogel strongly depends on the degree of oxidation showing its tunable chemistry and degradation rate. These findings demonstrate for the first time that immobilization of PDLSCs and GMSCs in the alginate microspheres provides a promising strategy for bone tissue engineering.     

Fabrication of bimetallic Cu/Pt nanoparticles modified glassy carbon electrode and its catalytic activity toward hydrogen evolution reaction

The film of poly(8-hydroxyquinoline) was formed by cyclic voltammetery method on the surface of glassy carbon electrode and poly(8-hydroxyquinoline) modified glassy carbon electrode, p(8-HQ)MGCE, was prepared. Cu²⁺ ion was adsorbed on the polymer matrix due to complexation with 8-hydroxyquinoline units Copper nanoparticles were deposited onto p(8-HQ)MGCE by applying potential and prepared copper nanoparticles galvanic replaced with platinum to fabricate poly(8-hydroxyquinoline)–Pt/Cu composite on the surface of GCE. Stripping voltammetery of Cu in aqueous 0.1 M KSCN + Britton–Robinson buffer, pH = 2.0, solution was used to quantify the copper present on the electrode surface. The amount of platinum was estimated from the electrooxidation peak of Pt in aqueous 0.1 M H₂SO₄ solution. The nature of Cu/Pt–p(8-HQ) on the surface of GCE was characterized by scanning electron microscopy. Cu/Pt–p(8-HQ) modified GCE can be used as a convenient conducting substrate for electrocatalytic hydrogen evolution reaction (HER). The effects of different parameters such as number of cycles, replacement time, scan rate of potential, and etc were investigated to obtaining optimum condition for HER.     

Prediction of the thickness loss and recovery of cut-pile carpets imposed to UV exposure and wear using polynomial regression method

Ultraviolet radiation which exists in environment around can be regarded as a major source of textile materials. In this study, the effect of UV exposure on the cut-pile carpet was investigated. A UV chamber was used to expose different levels of accelerated UV radiation on the samples of the machine-woven pile carpet. Wear test were then carried out on all samples using a Hexapod tumbler machine. The short-term static loading was applied to the carpets and the thickness loss percent (TL) and recovery percent (RP) of the samples at different times after load removal was measured using standard methods. Factorial experimental design and response surface method were applied for to create polynomial regression models and predict each of the thickness loss and recovery percent of carpet samples. The model is capable to determine the contribution of different variables. The results of the modeling revealed a desirable fit. The adjusted R² values were also high and significant. The ANOVA test indicated that the presented models were valid at 5% significant level.