No abstract

In order to reveal mechanisms for the electrospinning of proteins, this study focuses on the polymer chain conformation, which is considered to be a critical factor for successful electrospinning. Poly(gamma-benzyl-L-glutamate) (PBLG) is employed and the relationships between the chain conformations of the pre-spun PBLG molecules and the morphologies of the post-spun PBLG fibers are investigated. By combining viscosity measurements, and circular dichroism and FT-IR spectroscopies, chain conformations of the pre- and post-spun PBLG are characterized. The chain conformations of the pre-spun PBLG changes from an alpha-helix to a random coil upon changing the solvent ratios of dichloromethane (CH(2)Cl(2)) and trifluoroacetic acid (CF(3)COOH) from 100:0 to 0:100. In an alpha-helix conformation, the morphology of PBLG fibers is relatively thick, while that of the random coil is thin and homogenous. The mean fiber diameters decrease when the chain conformations change from an alpha-helix to a random coil. FT-IR spectroscopy and wide-angle X-ray diffraction measurements reveal that electrospinning predominantly induces an alpha-helical conformation in post-spun PBLG fibers, and more highly crystallized fibers are generated as the alpha-helical content in the pre-spun solution increases.

Purified squid ink was used as a natural dye in TiO 2 nanocomposite films for the fabrication of dye-sensitized solar cells (DSSCs). The squid ink extract was purified by the reaction over a proteolytic enzyme and coated onto composites of TiO 2 nanotubes/ nanoparticles. The resulting cells were compared with reference DSSCs in which N719 was used as a standard dye. Analysis revealed that the sub-500-nm eumelanine-based spherical nanoparticles were well adsorbed on the surface of the TiO 2 nanotubes/ nanoparticles, and the cells demonstrated efficiencies of 0.72 and 0.86%, respectively. The mechanisms over photosensitization induced by the purified ink particles are elucidated.

No abstract

The microstructural properties of thin-film silicon grown by plasma enhanced chemical vapour deposition from silane diluted with hydrogen have been studied in terms of gas-phase physics and chemistry. It is identified that the film microstructure is highly dependent on the hydrogen atom flux to silicon deposition flux ratio. A transition from amorphous to microcrystalline film growth takes place at a particular flux ratio. In microcrystalline film growth, the crystalline orientation changes from 1 1 0 to 1 1 1 , depending on the hydrogen atom flux. The film crystallinity increases with the hydrogen atom flux, and then the defect density and post-deposition oxidation are increased.