Su-Yeon Im

Photoelectric, stoichiometric and structural properties of n-ZnO film on p-Si

Abstract n-ZnO/p-Si heterojunction photodiodes have been fabricated by sputter deposition of n-ZnO films on p-Si substrates. Substrate temperatures of 300, 400, 500 and 600°C were used for the n-ZnO film deposition using various Ar/O2 ratios from 1:1 to 6:1. All the diodes, except for one obtained at a high substrate temperature of 600°C, show strong rectifying behavior as characterized by current–voltage (I–V) measurement in a dark room. Photoelectric effects from the diodes have been observed under illumination using monochromatic red light with a wavelength of 670 nm. High levels of photocurrent or responsivity were obtained under reverse bias conditions when the stoichiometry of n-ZnO films was improved by optimizing the process conditions, such as the substrate temperature and Ar/O2 ratio. The n-ZnO/p-Si structure prepared at 300°C was found to be unsuitable because photoelectric effects were not apparent from this structure. A heterojunction diode with n-ZnO deposited at 600°C was also found to be unsuitable because the dark leakage current was too high, even though the diode showed photoelectric effects.

Effect of non-thermal plasma on loading of tetracycline combined with plga into titania nanotube

Summary form only given. Titania nanotube (TNT) is a tube shaped thin film that is fabricated by process known as the anodization and it has been known to exhibit excellent biocompatibility and high surface-to-volume ratio, which makes it ideal structure as a carrier for drugs. However, drug loading on TNT has been limited by narrow diameter of TNT and to overcome this problem, the present study attempted to determine whether plasma treatment of inner TNT surface enhances its hydrophilicity and resultant drug carrying properties.

The effect of calcium aluminate bone cement incorporating LiF-maleic acid on the bone regeneration of 1-wall intrabony defects in beagle dogs

This study evaluated periodontal repair and biomaterial reaction following implantation of a newly fabricated calcium aluminate bony cement incorporating LiF-maleic acid on the regeneration of 1-wall intrabony defects in the beagle dogs. The surgical control group received a flap operation only, while the experimental group was treated with calcium aluminate bony cement incorporating LiF-maleic acid. The subjects were sacrificed 12 weeks after surgery and a comparative histologic analysis was done. In the experimental group, the grafted calcium aluminate cement was not absorbed and fibrous connective tissue was epithelized around the particles of the grafted bony cement. Because of certain favorable properties, such as its easy manipulation and its ability to maintain the morphology of the defect site by acting as a scaffold, the newly developed cement is suitable for us as a graft material, and could be used very effectively in alveolar augmentation. However, further study needs to be conducted before it can be used as a bone graft material for periodontal tissue regeneration.

The Effects of Calcium Aluminate Cement According to Particle Sizes on Calvarial Bone Defects in Rats

This present study was carried out to find out the effects of calcium aluminate cement(CaO·Al203, CAC), which has been developed with biocompatibility and mechanical properties, in biological environments. Two different particle sizes of CAC - 3.5 µm vs. 212-250 µm which is recommended in periodontal bone grafting procedures – were filled in 8mm calvarial defects in Sprague-Dawley rats. The specimens were examined histologically, especially the bone-cement interface and the response of surrounding tissues. The result of this study shows that when calvarial defects in white rats are filled with 212-250 µm calcium aluminate cement, the materials proved to be bio-compatible in growth and healing on the surrounding tissues. When further researches on direct bone adhesion and bone regeneration ability are fulfilled, CAC is expected to be applied to various fields of periodontology in the future.