Increased riboflavin production from activated bleaching earth by a mutant strain of Ashbya gossypii

The production of riboflavin from vegetable oil was increased using a mutant strain of Ashbya gossypii. This mutant was generated by treating the wild-type strain with N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). Riboflavin production was 10-fold higher in the mutant compared to the wild-type strain. The specific intracellular catalase activity after 3 d of culture was 6-fold higher in the mutant than in the wild-type strain. For the mutant, riboflavin production in the presence of 40 mM hydrogen peroxide was 16% less than that in the absence of hydrogen peroxide, whereas it was 56% less for the wild-type strain. The isocitrate lyase (ICL) activity of the mutant was 0.26 mU/mg of protein during the active riboflavin production phase, which was 2.6-fold higher than the wild-type strain. These data indicate that the mutant utilizes the carbon flux from the TCA cycle to the glyoxylate cycle more efficiently than the wild-type strain, resulting in enhanced riboflavin production. This novel mutant has the potential to be of use for industrial-scale riboflavin production from waste-activated bleaching earth (ABE), thereby transforming a useless material into a valuable bioproduct.     

Rice α-globulin decreases serum cholesterol concentrations in rats fed a hypercholesterolemic diet and ameliorates atherosclerotic lesions in apolipoprotein E-deficient mice

The hypocholesterolemic and antiatherogenic effects of rice α-globulin remain unclear. We investigated the hypocholesterolemic effect of rice α-globulin in rats fed a hypercholesterolemic diet. The rats were divided into 4 groups and were orally administrated the following three proteins or a vehicle for 4 weeks: rice protein, rice α-globulin, or soy β-conglycinin at a dose of 100 mg/kg body weight or carboxymethylcellulose to the control rats. In the rice α-globulin group, serum cholesterol concentrations were 28% lower than the control group and fecal neutral steroid excretion was increased by 30%. The hypocholesterolemic effect of rice α-globulin was equal to soy β-conglycinin in SD rats fed the hypercholesterolemic diet. However, the serum cholesterol concentrations in the rice protein group did not change compared to the control group. To investigate the antiatherogenic effects of rice α-globulin, male apolipoprotein E-deficient mice were orally administered the same dose of rice α-globulin for 9 weeks. The en face lesion area in the aorta was 46% lower than in the control group. In conclusion, administration of rice α-globulin improves hypercholesterolemia in rats fed a hypercholesterolemic diet by increasing the fecal excretion of neutral sterols, and inhibits atherosclerosis development in apolipoprotein E-deficient mice. The anti-atherosclerotic effect exerts by mechanism(s) other than the regulation of serum MCP-1 and NO concentrations.     

Improvement in the yield of lipophilized lysozyme by the combination with Maillard-type glycosylation

Hen egg white lysozyme was modified using the Maillard-type glycosylation method prior to the lipophilization with palmitic acid. The yield of lipophilized lysozyme significantly increased by the pre-glycosylation of the protein. The lipophilized lysozyme derivative was separated into two main fractions with different level of glycosylation. All fractions showed a strong antimicrobial activity against Gram-negative bacteria, Escherichia coli. The lipophilization of the lysozyme combined with glycosylation is a promising method for potential industrial applications of the lysozyme due to the enhanced antimicrobial activity and the improved yield.     

Effect of Surface Concentration of Lu on Oxygen Permeation of Polycrystalline Alumina at High Temperatures

The effect of Lu surface concentration on oxygen permeation in polycrystalline α‐alumina wafers was determined at 1773 K under limited oxygen potential gradients (Δ), where the two surfaces of the wafer were deliberately subjected to different oxygen partial pressures [ (I) ?  (II)]. When oxygen permeation occurred mainly by oxygen GB diffusion under a Δ generated by a combination of low values, the Lu‐coating on the (I) [ (II)] surface decreased [increased] the oxygen permeability constants. When Δ was the result of a combination of high values, where oxygen permeation proceeded mainly by aluminum GB diffusion, the oxygen permeability constants were decreased only by the Lu‐coating on the (I) surface. The analysis of mass transfer parameters, such as the chemical potentials, GB diffusion coefficients, and fluxes of aluminum and oxygen in the wafers, suggested that ambient oxygen molecules were effectively attracted toward Lu‐coated surfaces exposed to low‐ environments, leading to a change in oxygen permeability.     

Hydrothermal Synthesis of Nanocrystalline Cerium(IV) Oxide Powders

Nanocrystalline cerium(IV) oxide (CeO₂) powders were prepared by heating solutions of cerium(IV) salts in the presence of urea under hydrothermal conditions at 120° to 180°C. The effects of the concentration of urea and hydrothermal treatment temperature on the morphology and crystallite size of the synthesized particles were investigated. The synthesized particles were angular, ultrafine CeO₂, with a cubic fluorite structure. Their crystallite size decreased from 20 to 10 nm with increasing urea concentration from 2 times to 8 times that of the Ce⁴⁺ ion. The size only slightly changed by calcining at temperatures below 600°C.     

Novel Poly(N‐isopropylacrylamide)‐graft‐poly(vinylidene fluoride) Copolymers for Temperature‐Sensitive Microfiltration Membranes

In the present work, we report on the synthesis and characterization of poly(vinylidene fluoride) (PVDF) with N‐isopropylacrylamide (NIPAAM) polymer side chains from molecular graft copolymerization in solution. The copolymer can be readily cast into temperature‐sensitive microfiltration (MF) membranes by the phase inversion technique. The copolymer approach to membrane fabrication allows a much better control of the physicochemical nature of the membrane pores through the variation in graft concentration, membrane casting temperature and concentration of the membrane casting solution.

     

Crystal Phase and Orientation Control in Integrated Ferroelectric CaBi4Ti4O15 Using a Tailored Liquid of Alkoxides

We used a Ca–Bi–Ti complex alkoxide, in which metal–oxygen bonding was confirmed by spectroscopic analysis, to deposit CaBi₄Ti₄O₁₅ (CBTi144) thin films in various configurations. The phase transition of non-ferroelectric pyrochlore to ferroelectric perovskite in the complex-alkoxy-derived CBTi144 thin films was found to depend on the Pt bottom electrodes. Matching of the atomic arrangement to the Ca–Bi–Ti–O thin films was predominant rather than the strain and crystallinity of the bottom electrode. The thin films crystallized at 650°C on (111)-oriented Pt showed random orientation and ferroelectric P – V hysteresis loops. The endurance property was excellent against a number of switchings. For this reason, CBTi144 thin films would be expected to be excellent for application to ferroelectric random access memories (FeRAM). Polar-axis-oriented CBTi144 films were fabricated on Pt foils using the complex metal alkoxide solution. The 500-nm-thick film had a columnar structure comprising well-developed grains. The a / b -axis orientation of the ferroelectric films is considered to be associated with the preferred orientation of Pt foil. The film showed improved ferro- and piezoelectric properties. The P _r, E _c, and d ₃₃ values were enhanced to become twice those of CBTi144 thin films with random orientation. These polar-axis-oriented CBTi144 films are eminently useful in devices as Pb-free piezoelectric materials.     

Photocatalytic O2 evolution under visible light irradiation on BiVO4 in aqueous AgNO3 solution

BiVO₄ with a 2.3 eV band gap showed an activity for O₂ evolution from aqueous solutions containing Ag⁺ as an electron scavenger under visible light irradiation (λ > 520 nm). The quantum yield was 0.5% at 450 nm. This revised version was published online in July 2006 with corrections to the Cover Date.     

Structure and Photocatalytic Activity of Iron Oxide Nanotubes Prepared from Ferritin

We report structure and photocatalytic activity of solid nanotubes comprising iron oxide (hematite, α-Fe₂O₃) nanoparticles. The initial precursor cylinders were prepared by alternating layer-by-layer assembly of poly-l-arginine (PLA) and iron-storage protein ferritin in a track-etched polycarbonate membrane (pore diameter: 400 nm) with subsequent dissolution of the template. The obtained (PLA/ferritin)₃ nanotubes (outer diameter: 410 ± 14 nm) were calcinated at 500 or 700 °C under air, yielding iron oxide nanotubes. After the calcination, the cylindrical hollow structure completely remained, but its diameter, wall thickness, and maximum length were significantly diminished. SEM measurements revealed that the nanotubes prepared at 500 °C consist of uniform hematite nanoparticles with ca. 5 nm diameter and the nanotubes calcinated at 700 °C are composed of ca. 20 nm hematite nanoparticles. These nanotubes showed efficient photocatalytic activity for degradation of 4-chlorophenol; higher catalytic activity was observed in the reaction with 5 nm hematite nanoparticle nanotubes.