Antibacterial Activity and Fibroblast Cell Viability of Zirconia Coated with Glass Ceramic Containing Ag and NaF Nanoparticles.

The aim of this study was to evaluate the antibacterial activity against Streptococcus mutans and fibroblast viability of zirconia coated with glass ceramic powder containing Ag and F nanoparticles. Specimens were divided into eight groups depending on the glass ceramic powders: 5, 10, 15, 20 wt% of NaF and Ag, respectively. Adhesion of Streptococcus mutans on glass-coated zirconia surface was evaluated by antimicrobial test. Fibroblast viability was examined by WST-8 assay. In result, the bacterial activity was reduced by 11.8%, 15.4% in Ag 10 wt% and 20 wt% groups. When 5~15 wt% of NaF was added, bacterial counts decreased to 4.2~65.4%, and when 20 wt% of NaF was added, the number of bacteria increased by 29.4%. Regardless of Ag and NaF content, all zirconia specimens showed cell viability above 70%. Within the limitations of this study, zirconia coated with glass ceramics powder containing Ag and NaF was found to reduce the adhesion of Streptococcus mutans but had no influence on osteoblast activation.

Effect of Molar Concentration of NH4OH on Photocatalytic Activity in Preparation of Nanosized TiO2 Powder from Spent Titanium Chip by Sol-Gel Method.

The TiO2 powder was prepared from the spent titanium chips by applying the sol-gel method. The spent titanium chip was dissolved in HCl solution, and then NH4OH solution was added. The molar concentration of NH4OH solution was 2 M, 4 M, 8 M, and 10 M. Obtained TiO2 powders were calcined at 200 degrees C, 400 degrees C, and 600 degrees C. The prepared TiO2 powder was characterized using a particle size analysis, BET surface area, and XRD analysis. The crystal structure of the TiO2 powder was rutile type and anatase. The highest BET surface area of TiO2 powder was 432.8 m2/g. The photocatalytic property of the TiO2 powder was evaluated as decomposition rate of methylene blue(MB) by using a liquid phase stirred reactor. UV source was a UV-A, and concentration of MB in most experiments was 8 ppm. The concentration of MB was measured by absorbance at 664 nm using UV spectroscopy. Photocatalytic efficiency of prepared TiO2 powder depended highly on concentration of NH4OH solution. The TiO2 powder prepared with 8 M-NH4OH solution showed the highest efficiency, the decomposition efficiency at decomposition time of 2 hr and MB concentration of pH 8 was 98%.

Hybrid and Etch-Less Electrooptic Waveguide Modulator Based on Photo-Bleaching and Strain Induced Optical Waveguide Technique in Polymer.

A hybrid and etchless electrooptic (EO) polymer waveguide modulator based on both a photo-bleaching-induced optical waveguide (PBOW) and a strain-induced optical waveguide (SIOW) is described. The SIOW is defined by a metal strip line stressor deposited on top of the upper cladding that introduces the refractive index change within the core region. The PBOW technique is used to form an optical waveguide which is based on a photo-bleaching process, known as a photo-oxidation that is an irreversible decomposition of EO material, resulting in a permanent decrease in index of refraction. It is shown that this proposed fabrication idea combining two etchless techniques can be applicable to a wide range of polymer photonic integrated circuits. Preliminary results obtained from fabricated devices reveal that their half-wave voltage are ranging from 8 V to 10 V, their extinction ratio exhibits more than 15 dB, and the fiber-to-waveguide-to-lens loss is estimated to be ~9.5 dB for TM polarization at 1.55/m wavelength in the active interaction of ~1.5 cm long.

Catalytic Activity of Nanosized CuO-ZnO Supported on Titanium Chips in Hydrogenation of Carbon Dioxide to Methyl Alcohol.

In this study, titanium chips (TC) generated from industrial facilities was utilized as TiO2 support for hydrogenation of carbon dioxide (CO2) to methyl alcohol (CH3OH) over Cu-based catalysts. Nano-sized CuO and ZnO catalysts were deposited on TiO2 support using a co-precipitation (CP) method (CuO-ZnO/TiO2), where the thermal treatment of TC and the particle size of TiC2 are optimized on CO2 conversion under different reaction temperature and contact time. Direct hydrogenation of CO2 to CH3OH over CuO-ZnO/TiO2 catalysts was achieved and the maximum selectivity (22%) and yield (18.2%) of CH3OH were obtained in the range of reaction temperature 210-240 degrees C under the 30 bar. The selectivity was readily increased by increasing the flow rate, which does not affect much to the CO2 conversion and CH3OH yield.

Preparation of Nanosized TiO2 Powder from Spent Titanium Chip by Sol-Gel Method.

The TiO2 powder was prepared from the spent titanium chips by applying the sol-gel method with neutralization by NaOH solution. The prepared TiO2 powder was characterized using a particle size analysis, BET surface area, and XRD analysis. The crystal structure of the TiO2 powder was rutile type, and the powder was obtained to be nanosized. BET surface area of TiO2 powder was 118 m2/g, average particle size was 266.5 nm. The photocatalytic property of the TiO2 powder was evaluated as decomposition rate of methylene blue (MB) by using a liquid phase stirred reactor. Decomposition rate on TiO2 powder (P-25) was 1.5 times higher than that of the prepared TiO2 powder. Decomposition rate on the prepared TiO2 powder was linearly increased with increasing the amount of TiO2 powder, and approached to a specific value. MB concentration and decomposition rate was not correlated within the experimental range. The maximum value of decomposition rate at about pH 8 was 62%.

The Characteristics of an Antibacterial TiAgN Thin Film Coated by Physical Vapor Deposition Technique.

In this work, we found the characteristics of an antibacterial TiAgN thin film coated on the pure titanium specimen via the physical vapor deposition process (PVD). TiAgN thin films were coated using TiAg alloy targets by arc ion plating method. Changing the process parameters, the surface analysis of TiAgN thin film was observed by FE-SEM and the force of adhesion was measured with Scratch Tester. The proliferation of human gingival fibroblast (HGF) cells was examined by XTT test assay and the antibacterial properties were investigated by culturing Streptococus Mutans (KCTC 3065) using paper disk techniques. At the result of experiment, cytotoxic effects were not found and the antibacterial effects against Streptococus Mutans were appeared over 5 wt% TiAgN specimens.