Characterization of gelatin nanofiber prepared from gelatin-formic acid solution

Gelatin, well known as a biocompatible polymer, was dissolved in formic acid and gelatin nanofiber was successfully prepared by the electrospinning using gelatin-formic acid dope solution. Stability of the dope solution was evaluated by measuring viscosity change with time. Even though the viscosity dropped markedly after 5 h, the spinnability and morphology of gelatin nanofiber were not affected at all. The parameters, such as electric field, spinning distance, and concentration of dope solution, were examined for studying the effects on electrospinnability and morphology (size, size distribution, uniformity, bead formation, etc.) of gelatin nanofiber web. The gelatin nanofibers, in the mean size of 70-170 nm, could be prepared by controlling the dope concentration under proper conditions. The electrospun gelatin nanofiber exhibited a mixture of α-helical and random coil conformation, which was amorphous structure with very low crystallinity. The structural transformation, from a helical (α-helix and triple-helix) to random coil conformation, might occur when formic acid was used for the dissolution of gelatin in electrospinning.     

The effects of Te and misch metal additions on the microstructure and properties of rapidly solidified Ag−Sn−In alloy for electrical contact applications

High wear resistance with a stable contact resistance is a prerequisite for electrical contact applications. Although Ag−CdO has been widely used as an electrical contact material, there are intrinsic problems of forming large Cd oxide particles and environmental regulations against using Cd. Newly developed Ag−SnO₂ alloys are considered good candidates to replace Ag−CdO alloys due to their stable and fine oxide formation capabilities. In addition, further improvements in performance are expected in Ag−SnO₂ alloys by alloy modification and/or solidification processing to produce finer and stable oxide dispersions through internal oxidation. The effect of the addition of Te and misch metal, which function as oxide forming elements, on Ag−Sn−In ternary alloy was investigated. Up to 0.5 wt.% of Te and misch metals were added and rapidly solidified to maximize their effect on fine oxide formation in an Ag matrix. Resulting microstructural changes and properties were evaluated through electron microscopy, spectroscopy, and hardness measurements. The role of Te addition was to provide nucleation sites for complex oxides such as In₂TeO₆ phase and to ensure fine and well dispersed SnO₂ oxide particles. A rapid increase in size was observed for both grain and oxide particles when Te content exceeded 0.3 wt.%. Misch metal addition, on the other hand, had a pronounced effect on grain size reduction of the Ag matrix, and was interpreted as a consequence of decreasing the latent heat of solidification. Maximum hardness was achieved at 0.3 wt.% misch metal addition. In both cases, hardness decreased rapidly at 0.5 wt.% addition and was attributed to the large grain size of the matrix, and also large oxide particles aggregated in the matrix grains.     

Effect of deformation induced transformation of ɛ-martensite on ductility enhancement in a Fe-12 Mn steel at cryogenic temperatures

Metastable ?-martensite (?-Ms) formed during a prior heat treatment of Fe-12Mn steel has been reported to transform into α-Ms during subsequent inelastic deformation. This deformation induced phase transformation (DIPT) from ?-Ms to α-Ms has been investigated in the present study within the framework of kinetics relation proposed based upon an internal variable theory of inelastic deformation. The ?-Ms phase was found to become more stable at lower temperatures to provide more prolonged DIPT from ?-Ms to α-Ms during an inelastic deformation at cryogenic temperatures, contrary to the case of austenite phase in various transformation induced plasticity steels being more stable at higher temperatures. This reversed stability-temperature relationship in Fe-12Mn steel appeared to provide a significant ductility enhancement at lower temperatures as well as significant strengthening effect.     

Rapid synthesis of Pt-based alloy/carbon nanotube catalysts for a direct methanol fuel cell using flash light irradiation

We synthesized Pt, Pt–Ru alloy and Pt–Ru–Mo alloy nanoparticles on the multi-walled carbon nanotubes (MWCNTs) using flash light irradiation and characterized these catalysts. Pt₁₀₀, Pt₅₀-Ru₅₀ alloy and Pt₄₃-Ru₄₃-Mo₁₄ alloy are coated onto MWCNTs followed by flash light irradiation to facilitate the formation of nanoparticle-alloys. The fabricated pure Pt and Pt-based alloy nanoparticle/MWCNTs were characterized by X-ray diffraction (XRD), raman spectroscopy and scanning electron microscopy (SEM). Cyclic voltammetry (CV) studies and electrochemical impedance spectroscopy (EIS) results revealed that the Pt₄₃-Ru₄₃-Mo₁₄/MWCNT catalyst has higher activity and stability with regard to methanol electro-oxidation than the Pt₁₀₀/MWCNT and Pt₅₀-Ru₅₀/MWCNT catalysts.     

Isolation and characterization of two soil derived yeasts for bioethanol production on Cassava starch

Two ethanol-producing yeast strains, CHY1011 and CHFY0901 were isolated from soil in South Korea using an enrichment technique in a yeast peptone dextrose medium supplemented with 5% (w v^?1) ethanol at 30 °C. The phenotypic and physiological characteristics, as well as molecular phylogenetic analysis based on the D1/D2 domains of the large subunit (26S) rRNA gene and the internally transcribed spacer (ITS) 1 + 2 regions suggested that they were novel strains of Saccharomyces cerevisiae. During shaking flask cultivation, the highest ethanol productivity and theoretical yield of S. cerevisiae CHY1011 in YPD media containing 9.5% total sugars was 1.06 ± 0.02 g l^?1 h^?1 and 95.5 ± 1.2%, respectively, while those for S. cerevisiae CHFY0901 were 0.97 ± 0.03 g l^?1 h^?1 and 91.81 ± 2.2%, respectively. Simultaneous saccharification and fermentation for ethanol production was carried out using liquefied cassava (Manihot esculenta) starch in a 5 l lab-scale jar fermenter at 32 °C for 66 h with an agitation speed of 2 Hz. Under these conditions, S. cerevisiae CHY1011 and CHFY0901 yielded a final ethanol concentration of 89.1 ± 0.87 g l^?1 and 83.8 ± 1.11 g l^?1, a maximum ethanol productivity of 2.10 ± 0.02 g l^?1 h^?1 and 1.88 ± 0.01 g l^?1 h^?1, and a theoretical yield of 93.5 ± 1.4% and 91.3 ± 1.1%, respectively. These results suggest that S. cerevisiae CHY1011 and CHFY0901 have potential use in industrial bioethanol fermentation processes.     

Muddy water animation with different details

Muddy water is an example of suspension, which is a mixture containing particles that separate into distinct layers if left undisturbed. When stirred, however, the mud substance flows like a liquid and again begins settling out. Mud is composed of various sized particles, and they produce different effects when it is blended with water. This paper classifies the mud particles into three types and proposes different simulation methods for the types. The experimental results demonstrate that the proposed methods effectively produce visually plausible muddy water effects. Copyright © 2015 John Wiley & Sons, Ltd.     

Acceleration effect of sericin on shear-induced β-transition of silk fibroin

Although silk sericin (SS) occupies 25% of silk protein, its importance has often been overlooked in the natural silk spinning process and in the formation of the crystalline structure of silk fibroin (SF). In this study, we elucidated the role of SS in the crystallization process of SF under shear using SF/SS blend solutions. In order to apply shear stress to the blend solution, a rotating glass rod was inserted into a glass tube filled with the solution and the shear rate was determined to be in the range of 598–724 s⁻¹. After shearing, SF aggregates were formed and the amount of the aggregates increased with shearing time. Additionally, it was observed that the aggregate formation and β-sheet transition of SF were enhanced when a proper amount of SS was in the blend solution. Consequently, the SS considerably contributes to the structural transition of SF under shear. The SS can improve the shear-induced β-sheet transition and crystallization of SF.     

Effects of hydrolyzed Chlorella vulgaris by malted barley on the immunomodulatory response in ICR mice and in Molt‐4 cells

BACKGROUND: Chlorella vulgaris is a unicellular and microscopic algae that is currently used in a variety of forms of tablets, capsules and liquid as a biological response modifier. The aim of this study was to investigate the effects of hydrolyzed Chlorella vulgaris by malted barley for its potential reduction of the immobility time in ICR mice and on the cytokine regulation in human T cell line, Molt‐4. RESULTS: After a forced swimming test, the changes in aspects of blood biochemical parameters due to the administration of hydrolyzed Chlorella vulgaris by malted barley were examined. The effect of hydrolyzed Chlorella vulgaris by the malted barley‐treated group for 14 days on the immobility time was significantly reduced in comparison with that of the control group (P < 0.01). The plasma level of blood urea nitrogen was significantly decreased in hydrolyzed Chlorella vulgaris by malted barley‐treated group compared with the control group (P < 0.05). In addition, hydrolyzed Chlorella vulgaris by malted barley increased interferon‐γ and interlukin‐2 levels in Molt‐4 cells. CONCLUSION: These results indicate that hydrolyzed Chlorella vulgaris by malted barley is useful for immune function improvements, enhanced physical stamina, and as a candidate for an anti‐fatigue or antidepressant agent. Copyright © 2010 Society of Chemical Industry