Saccharification of alginate by using exolytic oligoalginate lyase from marine bacterium Sphingomonas sp. MJ-3

Alginate is a linear polysaccharide that is abundant in algal biomass. A novel recombinant exolytic oligoalginate lyase from a marine bacterium, Sphingomonas sp. MJ-3, was used for the saccharification of alginate into alginate monosaccharides in order to use alginate monosaccharides as renewable carbon source. The optimal heterologous expression condition for the MJ-3 oligoalginate lyase was determined, and the effects of saccharification reaction conditions were evaluated. Unsaturated monosaccharides up to 3.3 mg/ml were successfully prepared from 1% (w/v) alginate by using the recombinant oligoalginate lyase of Sphingomonas sp. MJ-3.     

Immobilization of laccase on carbon nanomaterials

Laccase from Trametes versicolor was readily immobilized on carbon nanomaterials including multiwalled carbon nanotubes (MWNTs), carboxylated multiwalled carbon nanotubes (MWNT-COOHs), and graphene oxides (GOs), by physical adsorption without using coupling agents. The immobilized amount of laccase strongly depends on the pH of the aqueous buffers of the immobilization mixture. As the pH of the aqueous buffer for immobilization increases, the immobilized amount of laccase decreases. The activity of the immobilized laccase on the three carbon nanomaterials exhibits a bell-shaped dependence on the pH of the immobilization solution with maximum activity at pH 6 or 7. When the immobilization solution becomes acidic or basic, the activity of the immobilized laccase declines significantly. The amount and the activity of immobilized laccase were maximum for graphene oxides as substrate material for immobilization.     

Halogen plasma erosion resistance of rare earth oxide films deposited on plasma sprayed alumina coating by aerosol deposition

Dense yttria, erbia and dysprosia films with thicknesses of 44.8 ± 1.7, 51.6 ± 0.9 and 36.8 ± 3.1 μm, respectively, were deposited on plasma sprayed alumina coating by aerosol deposition (AD). The rare earth oxide films remarkably enhanced the erosion resistance of the plasma sprayed alumina coating upon exposure to the halogen gas plasma. The enhanced plasma erosion resistances were related to their low surface porosity as well as the low vapor pressures of the rare earth fluorides and chlorides compared with those of corresponding aluminum halogenides. Electrical breakdown voltages of the samples with yttria, erbia and dysprosia films on the plasma sprayed alumina coating were 5.5, 6.2 and 5.3 kV, respectively, at room temperature and 4.0, 4.2 and 3.9 kV, respectively, at 573 K. The breakdown voltages at RT and 573 K were more than double that of the plasma sprayed alumina coating without the AD films.     

Microstructural evolution of YSZ electrolyte aerosol-deposited on porous NiO-YSZ

Dense, crack-free, ～7.5 μm thick, 8 mol% yttria stabilized zirconia (YSZ) film was aerosol deposited on porous NiO-YSZ anode substrates at room temperature without additional high-temperature sintering. The films’ microstructures and gas permeability were observed after annealing at various temperatures. The dense, gas-tight film that was observed up to 1000 °C became porous at higher temperatures probably due to structural instability related to oxygen non-stoichiometry. A cell using such film as electrolyte showed an open cell voltage of 1.10 V and a maximum power density of 0.51 W/cm² at 750 °C.     

Improvement on sulfate resistance of blended cement with high alumina slag

This paper is focused on the effect of limestone and calcium sulfate content on sulfate resistance of ground granulated blast furnace slag (GGBS) blended cement. Sulfate resistance was evaluated using ASTM C 1012, and a variety of mechanisms of the sulfate resistance of GGBS blended cement were revealed by the analyses of hydration products and sulfate ion ingress. Although GGBS suppresses sulfate ion ingress, it is probable that alumina in GGBS tends to form ettringite with externally supplied sulfate ions. Addition of limestone and increase in calcium sulfate content allow both monocarboaluminate and ettringite to form prior to immersion in sulfate solution. These hydration products remain in the hardened cement matrix and act to suppress further formation of ettringite with external sulfate ions during immersion in sulfate solution. GGBS blended cement with a suitable amount of limestone powder and a controlled content of calcium sulfate exhibits markedly long term sulfate resistance.     

Grafting maleic anhydride onto EVA and effect on the physical and rheological properties of PETG/EVA-g-MAH blends

Maleic anhydride (MAH) was grafted onto ethylene vinyl acetate copolymer (EVA) in the internal mixer in the presence of dicumyl peroxide (DCP), and a prepared reactive compatibilizer, MAH-g-EVA, was blended with Poly (ethylene glycol-co-cyclohexane-1,4-dimethanol terephthalate) (PETG). The gel content determination and element analysis (EA) was performed to confirm the grafting reaction. It was found that grafting reaction of MAH on to EVA could compete with crosslinking reaction of DCP during the modification process. In addition, the introduction of small amount of MAH showed a great effect on reducing gel content by decreasing crosslink reaction. As MAH content increased, grafted MAH concentration increased, whereas the grafting yield decreased. It was also confirmed that MAH-g-EVA acted as a reactive compatibilizer in the blend with PETG, and enhanced compatibility by reacting with the hydroxyl end groups, OH, of PETG. Addition of EVA in the blend leads a plastic deformation of PETG, and MAH had a great effect on enhancing interfacial adhesion resulting in significant increasing of % strain; however, improved compatibility could not be changed much in low strain tensile strength and Young's modulus. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Photoluminescence and LED application of β-SiAlON:Eu2+ green phosphor

We successfully prepared β-SiAlON:Eu²⁺ phosphors with composition of Eu_xSi_6?zAl_zO_yN_8?y (y = z ? 2x, x = 0.018, z = 0.23) by gas-pressured synthesis for application to LED. The crystal phase, microstructure, PL emission and thermal quenching properties were investigated in detail. The β-SiAlON:Eu²⁺ phosphors absorbed broad UV–vis spectral region, and showed a single intense broadband emission near 538 nm. The Stokes shift and zero-phonon line were calculated mathematically, and also estimated from the spectral data. The β-SiAlON:Eu²⁺ green phosphor showed superior thermal quenching properties compared to commercial silicate (SrBaSiO₄:Eu²⁺) green phosphor. The white light-emitting diode (LED) using the prepared β-SiAlON:Eu²⁺ green phosphor exhibited high color gamut, and good optical stability in high working temperature.     

Effect of electrode and substrate on the fatigue behavior of PZT thick films fabricated by aerosol deposition

10 μm-thick lead zirconate titanate (PZT) films with identical LaNiO₃ (LNO) top and bottom electrodes were fabricated on silicon and yttria-stabilized zirconia (YSZ) substrates by aerosol deposition (AD). A Pt electrode was also made for comparison. The dielectric, ferroelectric and fatigue behaviors at different fields were investigated. The PZT films on YSZ/LNO showed the highest dielectric and ferroelectric properties and good fatigue behavior under various fields. PZT films with a Pt electrode also showed good fatigue behavior up to 10⁸ cycles as thicker film can minimize the effect of defect entrapment near the interface.     

Decorating surface charge of graphite nanoplate using an electrostatic coupling agent for 3-dimensional polymer nanocomposite

Here, we report a facile approach to electrostatically couple the surface charges of graphite nanoplate (GNP) fillers and poly(methyl methacrylate) (PMMA) polymer particles using ethylene maleic anhydride (EMA) copolymer as an electrostatic coupling agent. Our strategy involved switching the intrinsic repulsive electrostatic interactions between the directly exfoliated GNPs fillers and the PMMA particles to attractive electrostatic surface interactions for preparing core(PMMA)-shell (GNP) precursor in order to optimizing 3-dimensionally dispersed polymer nanocomposite. As a result, the electrical conductivity of the composites dramatically increased by a factor of 16.7 in the EMA-coupled GNP/PMMA composites compared with that of the EMA-free GNP/PMMA composites. In addition, the percolation threshold was also notably reduced from 0.32 to 0.159 vol% after electrostatic coupling of the GNPs fillers and PMMA particles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48390.