Large Field Enhancement of Nanocoral Structures on Porous Si Synthesized from Rice Husks.

Silicon (Si) is a highly abundant, environmentally benign, and durable material and is the most popular semiconductor material; and it is used for the field enhancement of dielectric materials. Porous Si (PSi) exhibits high functionality due to its specific structure. However, the field enhancement of PSi has not been clarified sufficiently. Herein, we present the field enhancement of PSi by the fluorescence intensity enhancement of a dye molecule. The raw material used for producing PSi was rice husk, a biomass material. A nanocoral structure, consisting of spheroidal structures on the surface of PSi, was observed when PSi was subjected to chemical processes and pulsed laser melting, and it demonstrated large field enhancement with an enhancement factor (EF) of up to 545. Confocal microscopy was used for EF mapping of samples before and after laser melting, and the maps were superimposed on nanoscale scanning electron microscope images to highlight the EF effect as a function of microstructure. Nanocoral Si with high EF values were also evaluated by analyzing the porosity from gas adsorption measurements. Nanocoral Si was responsible for the high EF, according to thermodynamic calculations and agreement between experimental and calculation results as determined by Mie scattering theory.

Molecular tumorigenesis of the skin.

Skin tumors are supposed to develop through accumulations of genetic and/or epigenetic events in normal cells of the skin. Among them, we focus on common skin tumors, including benign, seborrheic keratosis, and malignant, squamous cell carcinoma and melanoma. Many important molecules have been detected on the molecular tumorigenesis of each of them to date, and some drugs targeted for their molecules have been already developed. We review updates on the molecular tumorigenesis of these tumors with our current works.