Production of Glycolipid Biosurfactant from Sponge-Associated Marine Actinobacterium <Emphasis Type="Italic">Brachybacterium paraconglomeratum</Emphasis> MSA21

Potential biosurfactant producers and economic production processes are major considerations for commercialization of biosurfactants. The present study was aimed at exploring marine Actinobacteria for the production of biosurfactants using industrial and agro-industrial wastes under solid state culture (SSC). A biosurfactant producer, Brachybacterium paraconglomeratum MSA21 was isolated from a marine sponge. The strain MSA21 effectively utilized tannery pre-treated effluent as the substrate for the production of a biosurfactant under SSC. The critical control factors influence the production of biosurfactant includes glucose, yeast extract, copper sulfate and inoculum size. The glucose and yeast extract interactively increase the production maxima over a stable area. The surface active compound was characterized as a glycolipid derivative with a hydrophilic part of methyl-2-oxopropyl furan and a hydrophobic dodecanoic acid, methyl ester. The MSA21 biosurfactant displayed antibiotic activity. The domain ketosynthase in MSA21 showed that the polyketide synthase gene might be involved in the synthesis of antimicrobial compounds. The strain B. paraconglomeratum MSA21 could be used for the production of a biosurfactant as a green alternative to replace chemical surfactants.     

Effect of the solvent on growth of titania nanotubes prepared by anodization of Ti in HCl

The effect of the solvent on the anodic growth of titania nanotubes in HCl dissolved in water, ethylene glycol and 2-propanol was studied. These nanotubes grow with locally rapid breakdown of the passive TiO₂ film forming a forest of nanotubes-bearing microtowers with the background of passive TiO₂ Film. These bundles of assembled-groups of titania nanotubes look like Pillars corals. The low relative permittivity of the 2-propanol led to lowering of dissociation of HCl and hence lowering the activity of H⁺ and Cl⁻ ions which in turn led to suppress of dissolution of titania and increasing the growth rate of the titania nanotubes. The X-ray diffraction pattern showed that the titania nanotubes after annealing change to the crystalline anatase phase. The anodic films showed characteristic coloration with intensity and color that changes (qualitatively) with time of anodization.     

Application of a Synthetic Ferredoxin-Inspired [4Fe4S]-Peptide Maquette as the Redox Partner for an [FeFe]-Hydrogenase

‘Bacterial-type’ ferredoxins host a cubane [4Fe4S]^2+/+ cluster that enables these proteins to mediate electron transfer and facilitate a broad range of biological processes. Peptide maquettes based on the conserved cluster-forming motif have previously been reported and used to model the ferredoxins. Herein we explore the integration of a [4Fe4S]-peptide maquette into a H₂-powered electron transport chain. While routinely formed under anaerobic conditions, we illustrate by electron paramagnetic resonance (EPR) analysis that these maquettes can be reconstituted under aerobic conditions by using photoactivated NADH to reduce the cluster at 240 K. Attempts to tune the redox properties of the iron-sulfur cluster by introducing an Fe-coordinating selenocysteine residue were also explored. To demonstrate the integration of these artificial metalloproteins into a semi-synthetic electron transport chain, we utilize a ferredoxin-inspired [4Fe4S]-peptide maquette as the redox partner in the hydrogenase-mediated oxidation of H₂.     

Developing Outstanding Bifunctional Electrocatalysts for Rechargeable Zn-Air Batteries Using High-Purity Spinel-Type ZnCo2Se4 Nanoparticles

Zinc-air batteries are gaining popularity as viable energy sources for green energy storage technologies. The cost and performance of Zn-air batteries are mostly determined by the air electrodes in combination with an oxygen electrocatalyst. This research aims at the particular innovations and challenges relating to air electrodes and related materials. Here, a nanocomposite of ZnCo₂Se₄@rGO that exhibits excellent electrocatalytic activity for the oxygen reduction reaction, ORR (E_1/2 = 0.802 V), and oxygen evolution reaction, OER (η₁₀ = 298 mV@10 mA cm⁻²) is synthesized. In addition, a rechargeable zinc-air battery with ZnCo₂Se₄@rGO as the cathode showed a high open circuit voltage (OCV) of 1.38 V, a peak power density of 210.4 mW cm⁻², and outstanding long-term cycling stability. The electronic structure and oxygen reduction/evolution reaction mechanism of the catalysts ZnCo₂Se₄ and Co₃Se₄ are further investigated using density functional theory calculations. Finally, a perspective for designing, preparing, and assembling air electrodes is suggested for the future developments of high-performance Zn-air batteries.     

A Proxy Signature Based Efficient and Robust Handover AKA Protocol for LTE/LTE-A Networks

Wireless Personal Communications - An efficient and robust handover is one of the essential requirements of several applications in LTE/LTE-A network. These applications are reliable only after a...     

Potential of biohydrogen generation using the delignified lignocellulosic biomass by a newly identified thermostable laccase from Trichoderma asperellum strain BPLMBT1

Delignification of plant-based biomass is one of the most important steps to determine the commercial success of bioavailability, and enzymatic delignification mediated via laccases could significantly improve the yield in an eco-friendly and precise manner. In this study, an extracellular laccase is newly identified and characterized from Trichoderma asperellum strain BPLMBT1. The purified laccase with specific activity of 51.0 U/mg, possesses a molecular mass of 65.0 kDa with absorbance peaks of 610–630 and 330 nm in the UV–Vis spectrum indicating the presence of the inclusive types I and III copper catalytic centers. The wide thermal and pH stability of this laccase, with optimal temperature of 80 °C and 3.0, are demonstrated by biochemical characterization and kinetics determination. In addition, the delignification of sweet sorghum stover biomass by the purified laccase resulting in an optimal lignin removal of 76.93% reveals its potential of utilizing delignified biomass for biohydrogen production 402.01 mL of biohydrogen was achieved after 84 h of anaerobic fermentation, which is 3.26-fold higher than the control without enzymatic pretreatment. The overall outcomes demonstrate an efficient way to utilize the thermostable laccase for biofuels conversion from lignocellulosic biomass.     

An optical tool for quantitative assessment of phycocyanin pigment concentration in cyanobacterial blooms within inland and marine environments

Quantitative assessment of the pigment phycocyanin (PC) in cyanobacterial blooms is essential to assess their abundance and distribution and consequently aid their management in many recreational waters within inland and coastal environments. In contrast to the open-ocean waters, these water bodies are very complex with a pronounced heterogeneity of their optical properties, and hence accurate retrieval of the water-leaving radiances and PC concentration from satellite observations is notoriously difficult with existing algorithms. In the present study, a new inversion algorithm is developed as a rapid cyanobacteria bloom assessment method and its retrievals of PC are compared with in-situ and satellite observations and those from a previously reported inversion algorithm. The new algorithm estimates PC concentration on the basis of the unique absorption feature of phycocyanin at 620 nm which is isolated from the total pigment absorption by taking advantage of the well-recognized absorption and reflectance features in the red and near-infrared (NIR) wavelengths (less impacted by the influences of the overlapping absorption signatures of the mixture constituents and pigment packaging). The by-products of this work include chl-a concentration and predictions from reflectance data to monitor the cyanobacterial component and non-cyanobacterial component of the phytoplankton assemblage and to evaluate PC:Chl-a pigment weight ratios for specific water types. Initial validation of the algorithm was performed using in-situ field data in turbid productive waters dominated by phycocyanin and other pigments, yielding coefficients of determination and slope close to unity and mean errors less than a few percent. These results suggest that the algorithm could be used as a rapid assessment tool for the remote-sensing assessment of the spatial distribution and relative abundance of cyanobacterial blooms in many regional water bodies.     

深水砂体成因研究新进展

在深水重力流研究中,传统浊流理论正受到砂质块体搬运和底流再改造砂体概念的冲击.陆架边缘沉积物滑塌是重力流驱动沉积过程最普遍的诱因,块体搬运过程(包含滑动、滑塌以及碎屑流)由于具有较高沉积物浓度(体积分数为25％～100％),表现为弹性和塑性特征.浊流因具有较低的沉积物浓度(体积分数为1％～23％)表现为黏性流动,不属于块体搬运的范畴.除重力流外,底流也是重要的深海搬运沉积方式.4种最常见的底流分别为:温盐流、风力驱动底流、深海潮汐及斜压流,牵引构造可用来区分这4种底流形成的再改造砂体,其中内波和内潮汐引起的斜压流再改造砂体的特征仍需深入研究.仅通过地震剖面与地质体形态无法识别块体搬运和底流再改造砂体类型,岩心和露头观察是唯一能鉴别其沉积相特征的方法.短期事件,如地震、海啸、热带风暴等,可能只持续几小时或者几天,却是沉积物滑塌的重要触发机制,比长达数千年低水位沉积期更为重要.图10参61     

Effect of heat input and weld chemistry on mechanical and microstructural aspects of double side welded austenitic stainless steel 321 grade using tungsten inert gas arc welding process

Stainless steel 321 is a stabilized austenitic grade that prevents the formation of chromium carbides at the grain boundaries and subsequently reduces the risk of corrosion attack at the weld surface by forming titanium carbide. It is primarily used in industries such as pressure vessels, boilers, nuclear reactors, carburetors and car exhaust systems. In order to assess the effect of gas tungsten arc welding process parameters on weld penetration, the proposed Taguchi L₉ orthogonal matrix has been selected with two factors and three levels for welding austenitic stainless steel 321 by adjusting the welding current and welding speed. Bead-on-plate experiments were performed on base metal of 6 mm thick plate by changing the process parameters, and corresponding weld bead measurement and macrostructure images are examined. Maximum depth of penetration −3.3017 mm is achieved with a heat input −1.4058 kJ/mm, i. e., welding current-220 A and welding speed-120 mm/min. Double-side arc welding technique is used to obtain full penetration on 6 mm thick plate. The quality of the weldment was assessed using non-destructive radiography inspection. Mechanical integrity and microstructural characteristics of the weldments were studied using tensile (transverse and longitudinal), bend, impact, microhardness, optical microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction analysis, ferrite number measurement and scanning electron microscope. The results reveal that the double side-tungsten inert gas weldment have better mechanical properties. It is corroborated from the weld metal microstructure that it contains γ-austenite, δ-ferrite and titanium carbides (intermetallic compounds). X-ray diffraction analysis and energy dispersive x-ray spectroscopy plots confirm the increase in the ferrite phase in weld metal. The ferrite measurement results show that the ferrite volume in the base metal and weld metal is 1.2 percent and 6.1 percent respectively. In addition, the higher δ-ferrite volume in the weldment helps in attaining superior mechanical integrity. Fractography shows that the failure mode of the weld metal and the base metal is ductile.