Bioprocess for Hyperactive Thermotolerant Aspergillus fumigatus Phytase and its Application in Dephytinization of Wheat Flour

Catalysis Letters - In the present study, statistically optimized production of thermotolerant Aspergillus fumigatus phytase was carried out in batch fermentation (1-L). An enhancement in phytase...     

Damage accumulation in plasma-sprayed zirconia under cyclic loading

The stiffness and hysteretic response due to mechanical and thermo-mechanical cycling have been studied in plasma-sprayed yttria-stabilized zirconia (YSZ). Mechanical cycling of free-standing cantilevers of YSZ shows that the progressive decrease in stiffness is accompanied by monotonic increase in hysteretic energy dissipation per cycle and a permanent ratcheting displacement of ∼20 nm/cycle. Below a critical stress, it varies from coating to coating, ratcheting accompanied by a slow decrease in stiffness does not lead to failure even after ∼1000 cycles. In contrast, at higher stresses, the rates of ratcheting and decrease in stiffness increase rapidly, leading to the nucleation of macrocracks that lead to fracture failure. Prior thermal cycling of coatings on Inconel substrate up to 700°C, which induced an estimated cyclic thermal stress of ∼35 MPa, led to a pronounced reduction in stiffness and mechanical cycling life. During bending, damage accumulates in the tension side of the cantilever and the volume going through the compression cycle remains relatively undamaged.     

One step synthesis and characterization of copper doped sulfated titania and its enhanced photocatalytic activity in visible light by degradation of methyl orange

This paper reports on the synthesis of copper doped sulfated titania nano-crystalline powders with varying(2.0%–10.0%, by mass) by single step sol gel method. The synthesized photo catalyst has been characterized by employing various techniques like X-ray Diffraction(XRD), Ultraviolet–Visible Diffuse Reflection Spectroscopy(UV–Vis DRS), X-ray Photoelectron Spectroscopy(XPS), Scanning Electron Microscopy(SEM), Energy Dispersive Spectrometry(EDS), Fourier Transform Infrared Spectroscopic Studies(FT-IR), and Transmission Electron Microscopy(TEM). From the XRD and TEM results, all the samples were reported in anatase phase with reduction in particle size in the range of 7 to 12 nm. SEM indicated the change in morphology of the particles. The presence of copper in titania lattice was evidenced by XPS. From UV–Vis DRS and FT-IR studies indicated that prominent absorption shift is observed towards visible region(red shift), the entry of Cu2+into Ti O2 lattice as a substitutional dopant and SO42-ions were covalently bonded with Ti4 +on the surface of the copper doped titania respectively.The photocatalytic activity studies were investigated by considering methyl orange(MO) as dye pollutant in the presence of the visible light. The effect of various parameters like effect of dosage of the catalyst, dopant concentration, p H of the solution, and concentration of the dye was studied in detail.     

Kinetics and mechanism of styrene‐acrylonitrile copolymerization in micro‐emulsion

Stable and transparent poly(styrene‐acrylonitrile) latexes were produced by the polymerization of styrene‐acrylonitrile in ternary o/w micro‐emulsions containing sodium dodecyl sulfate as an anionic surfactant. Kinetics of copolymerization was studied at different temperatures using different concentrations of potassium persulfate and hydrogen peroxide/ascorbic acid. The suitability of existing model for homopolymerization was examined for styrene‐acrylonitrile copolymerization after appropriate modification. The latexes were characterized for particle size and number of particles by dynamic light scattering and TEM. The isolated products were characterized by ¹H and ¹³C NMR as well as by thermal analysis. The overall size of particles was found to be between 15 and 20 nm. © 2000 Society of Chemical Industry