Decolorization of two synthetic dyes using the purified laccase of Paraconiothyrium variabile immobilized on porous silica beads

BACKGROUND: Decolorization of hazardous synthetic dyes using laccases in both free and immobilized form has gained attention during the last decades. The present study was designed to prepare immobilized laccase (purified from Paraconiothyrium variabile) on porous silica beads followed by evaluation of both free and immobilized laccases for decolorization of two synthetic dyes of Acid Blue 25 and Acid Orange 7. Effects of laccase concentration, pH and temperature alteration, and presence of 1-hydroxybenzotriazole (HBT) as laccase mediator on decolorization pattern were also studied. In addition, the kinetic parameters (K( m ) and V( max )) of the free and immobilized laccases for each synthetic dye were calculated. RESULTS: Immobilized laccase represented higher temperature and pH stability compare to free one. 39% and 35% of Acid Blue 25 and Acid Orange 7 was decolorized, respectively after 65 min incubation in presence of the free laccase. In the case of immobilized laccase decolorization percent was found to be 76% and 64% for Acid Blue 25 and Acid Orange 7, respectively at the same time. Increasing of laccase activity enhanced decolorization percent using free and immobilized laccases. Relative decolorization of both applied dyes was increased after treatment by laccase-HBT system. After nine cycles of decolorization by immobilized laccase, 26% and 31% of relative activity were lost in the case of Acid Blue 25 and Acid Orange 7, respectively. CONCLUSIONS: To sum up, the present investigation introduced the immobilized laccase of P. variabile on porous beads as an efficient biocatalyst for decolorization of synthetic dyes

Prioritizing livestock grazing right buyouts to safeguard Asiatic cheetahs from extinction

The article processing charge was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 491192747 and the Open Access Publication Fund of Humboldt-Universität zu Berlin.Livestock husbandry exerts major pressures on wildlife across the world. Large carnivores are particularly at risk because they are often killed by pastoralists as a preventive or precautionary response to livestock depredation. Minimizing the overlap between pastures and carnivore habitat can thus be a conservation strategy, but it remains often unclear which pastures should be targeted to maximize conservation benefits given a limited budget. We addressed this question for the last viable population of the Asiatic cheetah (Acinonyx jubatus venaticus) in northeastern Iran. By combining species distribution modeling with a spatial prioritization framework, we aimed to identify where grazing right buyouts should take place to reduce cheetah killing by herders and their dogs. We assessed the Asiatic cheetah habitat using species distribution models, highlighting large, contiguous areas that overlap with livestock pastures (5792 km2, equaling 72% of the total predicted suitable habitat). Subsequently, we used data on the number and distribution of livestock (~47,000 animals in 80 pastures) and applied a spatial prioritization method to identify pastures for grazing right buyouts for a range of budget scenarios (US$100,000–600,000). Pastures selected had a high level of irreplaceability and were generally stable across budget scenarios. Our results provide a novel approach to minimize encounter rates between cheetah and livestock, and thus the mortality risk, for one of the world's most endangered felids and highlight the potential of spatial prioritization as a tool to devise urgent conservation actions.Peer Reviewe

A review on nanocomposite hydrogels and their biomedical applications

In order to improve the drawbacks related to hydrogels, nanocomposite hydrogels were developed by incorporating different types of nanoparticles or nanostructures in the hydrogel network. This review categorizes nanocomposite hydrogels based on the type of their nanoparticle into four groups of carbon-, polymeric-, inorganic- and metallic-based nanocomposite hydrogels. Each type has specific properties that make them appropriate for a special purpose. This is mainly attributed to the improvement of interactions between nanoparticles and polymeric chains and to the enhancement of desirable properties for target applications. The focus of this paper is on biomedical applications of nanocomposite hydrogels and the most recent approaches made to fulfill their current limitations

Effects of Neutralization and Crosslinking Agents on the Morphology of Chitosan Electrospun Scaffolds

Chitosan, a natural polymer derived from chitin by deacetylation process of chitin, has gained an enormous interest in tissue engineering due to its unique features such as antibacterial activity and wound healing properties. Electrospinning of acidified chitosan solution is one of the most widely-used approaches in fabrication of 3D scaffolds. Although there are some reports addressing morphology tailoring of the chitosan nanofibers through solution electrospinning, there is no comparative report concerning the neutralization and stabilization conditions of chitosan electrospun fibers. Therefore, this article compares the effects of different neutralizing agents such as aqueous solutions of sodium carbonate (Na2CO3) and potassium carbonate (K2CO3), and crosslinking reagents including glutaraldehyde (GA) and genipin on morphology of electrospun chitosan fibers. After neutralization and stabilization processes, Fourier transform infrared spectroscopy (FTIR) was employed to investigate the morphology of fibers. Furthermore, the influence of the aforementioned parameters on stability of fibers was probed using scanning electron microscopy. SEM images illustrated that the scaffold resulting from electrospinning of 4 wt% chitosan solution in a mixture of trifluoroacetic acid (TFA) and dichloromethane (DCM) possessed a well-formed nanofibrous structure. Afterwards, different methods for neutralization and stabilization of the electrospun chitosan nanofiber mats were performed. In this respect, aqueous solutions of both Na2CO3 and K2CO3 salts (1M) were employed as neutralization agents and GA and genipin were used as two different crosslinking agents. Based on SEM analysis, the chitosan fibers, crosslinked with genipin, showed better morphology than a scaffold which was crosslinked with glutaraldehyd

Effect of Solution Surface Tension on Morphology of PLGA and Gelatin Electrospun Fibers

Based on specifc applications of electrospinning technology in tissue engineering there is a need for more crucial advances to be made in electrospinning of biocompatible polymer systems. In this study we investigated the effect of surface tension of different solvent systems on the morphology of electrospun nanofbers of gelatin and PLGA. At first the best solvent system was established to optimize nanofber formation of the polymers. The overall approach of this research was to prepare several solutions of identical concentrations with different solvent systems for electospinning into nanofbes. Finally, the changes in electrospun fbe

Evaluation of Adhesion Properties of Acrylic/Silicone Pressure Sensitive Adhesives Blends

In this study the blends of acrylic/silicone pressure sensitive adhesive (PSA) were prepared, and their adhesion properties and surface morphology were evaluated. For this purpose appropriate amounts of acrylic (10- 90%w/w) were added to silicone PSA to obtain visually homogeneous solution. The resulting solution was evenly applied on a polyethylene terephthalate (PET) film with final specific thicknesses (35, 65 and 110 μm) by using a film applicator. The morphological analysis was performed through scanning electron microscopy (SEM) and by the study of thermal analysis using the differential mechanical thermal analysis (DMTA) behavior of the blends, and it was found that all acrylic/silicone blends were incompatible and showed two different glass transition temperatures. By addition of silicone from 10 to 50% to acrylic/silicone blends the continuous phase is acrylic and the dispersed phase is silicone. Equally by increasing the percentage of silicone in the blends the continuous and dispersed phases were interchanged. By study of surface analysis and peel strength results it was found that surface properties are the main factors to determine peel strength values. Viscoelastic studies of the blends were shown that tack values and G" showed the same changing trend

Improved ductility of hot extruded Mg-0.5Zn-0.5Zr-1RE alloy by Li addition

Mechanical properties of lean Mg-xLi-1RE-0.5Zn-0.5Zr alloys after hot working by the extrusion process were systematically investigated. By increasing Li content, the coarsening of the dynamic recrystallization (DRX) grain size (D) was recorded. This was ascribed to the decrease of the solidus temperature (TSolidus) by increasing Li content, and hence, the increase of the homologous temperature during hot deformation (T/TSolidus). As a result, the tensile yield stress (TYS), ultimate tensile strength (UTS), compressive yield stress (CYS), and ultimate compressive strength (UCS) decreased by increasing Li content. Accordingly, the Hall-Petch relationships of TYS = 145.8 + 69/√D and CYS = 69.3 + 100/√D were proposed, where TYS, CYS, and D are expressed in MPa, MPa, and μm, respectively. However, total elongation in the tension test and fracture strain in the compression test were significantly improved and the crystallographic texture intensity decreased by increasing the Li content. These improvements were found to be quite beneficial for overcoming and breaking the strength–ductility trade-off. The mechanical behavior of these alloys was compared to other competitive alloys for lightweight applications