Fabrication and characterization of poly‐γ‐glutamic acid nanofiber

Poly‐γ‐glutamic acid (γ‐PGA) is a natural polymer that is widely recognized as a component in the viscous filaments of fermented soybean (natto). γ‐PGA is known for its superior biodegradability, biocompatibility and water retention characteristics. Crosslinked γ‐PGA is commonly used as a hydrogel, but it is not used in the fiber form because it is soluble in water. In this study, we demonstrate the use of γ‐PGA‐Na for production of water insoluble γ‐PGA nanofibers by electrospinning. This result was accomplished using an aqueous solvent containing 10 wt % of an oxazoline component polymer as the crosslinking agent and by heat treatment. The crosslinking reaction was evaluated by solid‐state NMR. The nanofiber webs showed a high level of moisture absorption capability while retaining their fibrous shape. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Strengthening of Porous Alumina by Pulse Electric Current Sintering and Nanocomposite Processing

Porous Al₂O₃ and SiC–dispersed-Al₂O₃ (Al₂O₃/SiC) nanocomposites with improved mechanical properties were fabricated using pulse electric current sintering (PECS). Microstructures with fine grains and enhanced neck growth, as well as high fracture strength, could be achieved via PECS of Al₂O₃. The incorporation of fine SiC particles into an Al₂O₃ matrix significantly increased the fracture strength of porous Al₂O₃. Based on microstructural observations, it was revealed that the refinement of Al₂O₃ grains and neck growth occurred by PECS and nanocomposite processing.     

Extraction of lanthanide ions from aqueous solution by bis(2-ethylhexyl)phosphoric acid with room-temperature ionic liquids

Extractions of five kinds of lanthanide metal ions by bis(2-ethylhexyl)phosphoric acid (DEHPA) with [1-Cn-3-methylimidazolium][PF₆](Cn = C₂, C₄) or [1-butyl-4-methylpyridinium][PF₆] were carried out under various DEHPA and HNO₃ concentrations from 0 to 1 M and under different temperature conditions from 298 to 333 K. These results were compared with those using the conventional organic solvent, hexane, in terms of their distribution coefficient values. Under all of the conditions in this study, the ionic liquid system shows more than three times greater extractability for lanthanide compared to when hexane was used. The distribution coefficient of lanthanide ions decreased as the length of the alkyl chain increased from the ethyl to the butyl. In addition, the imidazolium cation generally shows a higher distribution coefficient compared to the pyridinium cation in an ionic liquid. The concentration ratio of lanthanides and DEHPA resulted in an extraction affinity transition for lanthanides. Also evaluated in this study were issues related to the selectivity associated with the lanthanide mixture and the dependency of the ionic radius during lanthanide extraction.     

Automated single nucleotide polymorphism typing using bead array in capillary tube

A low-cost and simple on-site technique for genotyping single nucleotide polymorphisms (SNPs) was developed. The technique is based on allele-specific primer PCR and the recently developed bead arrays in a single tip technique. The performance of the method was verified by genotyping four SNPs that correlate with cardiovascular diseases.     

Mutants of the nematode Caenorhabditis elegans that are defective specifically in their attraction to cycloheximide

The nematode Caenorhabditis elegans exhibits chemotaxis toward a wide variety of chemicals including water-soluble molecules and volatile organic compounds. We have previously discovered that C. elegans wild-type strain N2 is strongly attracted by cycloheximide which has long been known as a bitter tastant for humans and other mammals. We describe here the isolation and initial characterization of the first mutants which were defective specifically in their attraction to cycloheximide. In our screenings, we selected two mutants that were defective in chemotaxis to cycloheximide but normal in their attraction to NH4Cl and histidine. These mutants also avoided quinine hydrochloride, CuSO4 and high concentrations of NaCl similar to the wild-type strain N2. Furthermore, no observable defect was detected in their attraction to volatile odorants such as isoamyl alcohol and diacetyl. Dye-filling experiments suggested that they have no morphological defect in the sensory endings of the amphid neurons.     

Cloning, sequencing and expression of an alpha-L-arabinofuranosidase from Aspergillus sojae

The arabinofuranosidase gene was cloned from the cDNA of Aspergillus sojae. It was found to contain an open reading frame composed of 984 base pairs (bp) and to encode 328 amino acid residues (aa). The cDNA sequence suggested that the mature enzyme is preceded by a 26-aa signal sequence and the molecular mass was predicted to be 32,749 Da. The A. sojae arabinofuranosidase consists of a single catalytic domain; it does not have a specific substrate-binding domain such as the xylan-binding domain reported in an arabinofuranosidase from Streptomyces lividans (Vincent, P. et al.: Biochem. J., 322, 845-852, 1997). The deduced amino acid sequence of the catalytic domain of the mature enzyme exhibits extensive identity with the catalytic domains of Streptomyces coelicolor (74%), Aspergillus niger (75%), S. lividans (74%), and Aspergillus tubingensis (75%), which are enzymes that belong to family 62 of the glycosyl hydrolases. The cloned AFdase gene was expressed in Escherichia coli BL21 (DE3) pLysS as a cellulose-binding domain tag fusion protein. The specific activity of the purified recombinant enzyme was 18.6 units/mg protein, which is one-fourth that of the enzyme purified from a solid-state culture of A. sojae.     

Sensory evaluation of beef patties and sausages containing lipids with various component fatty acids

Sensory scores of beef patties and emulsion-type sausages containing varying levels of lipids with various component fatty acids were investigated. Sensory scores of beef patties containing solid fat were relatively constant at every fat level examined. However, scores of beef patties containing liquid oil decreased with increasing level of added oil. In the case of sausages, on the other hand, sensory evaluation scores markedly decreased with increasing the level of solid fat, while no significant change was observed in panel scores when liquid oil was mixed into sausages. Even 10% level of added lipids satisfactorily gave preferable acceptability to beef patties and sausages.     

Hydrogenation and dehydrogenation processes of palladium thin films measured in situ by spectroscopic ellipsometry

The hydrogenation and dehydrogenation switching processes of Pd thin films were analyzed by measuring in situ in real time the variation in ellipsometric Ψ and Δ during hydrogenation and dehydrogenation using spectroscopic ellipsometry. The hydrogenation proceeded from the film surface and a mixture layer of metal and hydride was formed at the surface. With time elapse, the thickness of the mixture layer increased rapidly. After the whole Pd metal layer transformed to the mixture layer, the concentration of hydride in the mixture layer increased. Finally, the concentration reached 1; the whole Pd in the mixture layer was hydrogenated, and the hydrogenation of Pd was complete. On the other hand, the dehydrogenation proceeded in a way completely opposite to the hydrogenation process; the concentration of hydride in the mixture layer decreased, Pd metal layer was formed at the interface between the film and the substrate, and the whole layer returned to Pd metal. The dehydrogenation proceeds much faster than hydrogenation.