• Journal of Photoscience
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• 제10권3호
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• pp.231-236
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• 2003

TiO$_2$ has been used as photocatalyst since two and half decades ago. The efficiency in its photocatalytic reactions has been improved by increasing the surface area of the photocatalyst by supporting fine TiO$_2$ particles on some porous materials. In this work, heteropolytungstic acid (HPA) - encapsulated into the titanium exchanged SBA-15 mesoporous materials (TiSBA-15) were prepared and characterized. Also their photocatalytic effects on decomposition of phenol were investigated and the photodecomposition rates of the phenol were observed to be increased by 2.5 8 fold, as compared to those observed in the presence of HPA-encapsulated SBA-15 or TiSBA-15 without HPA.

• Journal of Environmental Health Sciences
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• 제14권1호
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• pp.11-22
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• 1988

Calcium oxide, lithium oxide and titanium oxide were investigated as additives of zinc oxide for the removal of hydrogen sulfide at high temperature. This experiment was performed in the range of 1.0-2.0 vol.% H$_2$S concentration at 623-873 K reaction temperature, using a thermogravimetric analyzer. A pore blocking model was found to fit the reaction rate and the kinetics data were sucessfully expressed by this model. The reactions between additive sorbents and hydrogen sulfide were first order with respect to hydrogen sulfide concentration in a gaseous mixture with nitrogen. Among the used sorbents, ZnO-CaO 0.5 at.% and ZnO-TiO$_2$ 2.0 at.% sorbents had the best additive effects on the sulfidation reaction between additive sorbents and hydrogen sulfide, whereas the ZnO-Li$_2$O sorbents were ineffective.

• Current Photovoltaic Research
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• 제3권3호
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• pp.91-96
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• 2015

Optical modeling and characterization of transparent dye-sensitized solar cells (DSC) are presented to design and estimate DSC devices numerically. In order to model the inhomogeneous active layer of DSC, the porous structure of titanium oxide ($TiO_2$) and dye mixture, we prepared films consisting of layer by layer of the DSC's basic materials sequentially, and characterized the optical parameters of the films with the effective refractive index, which was extracted from the transmittance and reflectance measurements in ultra violet to near infra-red range. By using the effective refractive index, we made the optical model for DSC, and demonstrated that the optical model based on effective refractive index can be used to design and evaluate the performance of transparent-type DSC modules.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.440-441
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• 2006

Several titanate powders ($Al_2TiO_5,\;SrTiO_3$, etc.) were synthesized by an ethylene glycol solution route. Titanium isopropoxide and nitrate salts were dissolved in stoichiometric proportions in liquid-type ethylene glycol without any precipitation. The parent precursor sols were dried to porous gels, and then the gels were calcined and crystallized. All synthesized titanate powders had stable crystallization behavior at low temperature and high specific surface area after a simple ball-milling process. A three-component PZT $(Pb(Zr_{0.52}{\cdot}Ti_{0.48})O_3)$ powder was also synthesized successfully by the ethylene glycol method. In this study, the characteristics of the multi-component titanate powders by the ethylene glycol method are examined.

• Journal of dental hygiene science
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• 제16권1호
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• pp.70-76
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• 2016

The objective of this study was to fabricate hydroxyapatite (HA) containing titania layer by HA blasting and anodization method to obtain advantages of both methods and evaluated biocompatibility. To fabricate the HA containing titania layer on titanium, HA blasting treatment was performed followed by microarc oxidation (MAO) using the electrolyte solution of 0.04 M ${\beta}$-glycerol phosphate disodium salt n-hydrate and 0.4 M calcium acetate n-hydrate on the condition of various applied voltages (100, 150, 200, 250 V) for 3 minutes. The experimental group was divided according to the surface treatment procedure: SM (simple machined polishing treatment), HA, MAO, HA+MAO 100, HA+MAO 150, HA+MAO 200, HA+MAO 250. The wettability of surface was observed by contact angle measurement. Biocompatibility was evaluated by cell adhesion, and cell differentiation including alkaline phosphatase activity and calcium concentration with MC3T3-E1 cells. The porous titanium oxide containing HA was formed at 150 and 200 V. These surfaces had a more hydrophilic characteristic. Biocompatibility was demonstrated that HA titania composite layer on titanium showed enhanced cell adhesion, and cell differentiation. Therefore, these results suggested that HA containing titania layer on titanium was improved biological properties that could be applied as material for dental implant system.

• Archives of Plastic Surgery
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• 제35권4호
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• pp.431-438
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• 2008

Purpose: The common deformity after the correction of unilateral cleft lip nasal deformity is nasal asymmetry, and it is caused by the hypoplasia of the pyriform aperture. To correct this, many procedures have been applied, but still many problems are present. Authors performed the inlay and onlay insertion of porous high density polyethylene sheet(1 mm thickness $Medpor{(R)}$ sheet) in the hypoplastic pyriform margin of cleft side and obtained satisfactory results. Methods: 11 cases were performed and the mean follow up period was 15.1 months. Their mean age was 23.6 years. Under general anesthesia, bilateral pyriform margin was exposed. $Medpor{(R)}$ sheets in "match stick" like shaped were inlay inserted, and kidney shaped were onlay inserted fixating with two 6 mm titanium screws. After the surgery, the results was evaluated by photogrammetric analysis. On the basal view, the distance from the subalare and labiale superius' to the transverse baseline connecting the both cheilions was measured from the cleft side and the non-cleft side. Then, the postoperative symmetry was assessed by obtaining the cleft side against the non-cleft side as proportion index, defined as lateral and medial upper lip contour index. Results: There were 2 infections. The cause was because the inserted implant was too long and thus protruded to the base of nasal cavity. The lateral upper lip contour index was from 95.49 to 103.27, and medial upper lip contour index was from 90.92 to 100.49, it was statistically increased, and thus the symmetry was improved. However clinically mild depression remained at nostril floor. Conclusion: Authors performed porous high density polyethylene sheet inlay and onlay insertion for the hypoplasia of the pyriform margin in unilateral cleft lip nasal deformity. It was found that depressed pyriform margin and upper lip were corrected effectively except for the nostril floor, for which an additional soft tissue augmentation would be necessary. The inlay insertion has risk of protrusion, thus the guideline of the use of artificial prosthesis should be observed strictly.

• Journal of Dental Rehabilitation and Applied Science
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• 제28권3호
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• pp.319-326
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• 2012

For many years, ceramics have been used in fixed prosthodontics for achieving optimal esthetics. but, they have another use as well. Many studies today show ceramics can be used for biomaterials. In the beginning researchers made a start in the study of aluminium oxide and sapphire for biomaterial. The appearance of Zirconia began a new phase of research. Zirconia was introduced into implantology as an alternative to titanium, because of its white color, good mechanical properties and superior biocompatibility. But it is not easy to surface treatment in comparison with titanium. To overcome the limitation, interconnected porous bodies of zirconia were fabricated by sintering technique. And the technique of coating was developed. Therefore, some zirconia implants are currently available. It is thought that Research of biomaterials as a variety of puposes for the use of zirconia is looking very promising. The purpose of this paper reviews are to evaluation of zirconia as biomaterials.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.23-23
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• 2018

In this study, new titanium alloys were prepared by adding elements such as tantalum (Ta), zirconium (Zr) and the like to complement the biological, chemical and mechanical properties of titanium alloys. The Ti-40Ta-xZr ternary alloy was formed on the basis of Ti-40Ta alloy with the contents of Zr in the contents of 0, 3, 7 and 15 wt. %. Plasma electrolytic oxidation (PEO), which combines high-voltage sparks and electrochemical oxidation, is a novel method to form ceramic coatings on light metals such as Ti and its alloys. These oxide film produced by the electrochemical surface treatment is a thick and uniform porous form. It is also composed of hydroxyapatite and calcium phosphate-based phases, so it has the characteristics of bone inorganic, non-toxic and very high bioactivity and biocompatibility. Ti-40Ta-xZr alloys were homogenized in an Ar atmosphere at $1050^{\circ}C$ for 1 hour and then quenched in ice water. The electrochemical oxide film was applied by using a power supply of 280 V for 3 minutes in 0.15 M calcium acetate monohydrate ($Ca(CH_3COO)_2{\cdot}H_2O$) and 0.02 M calcium glycerophosphate ($C_3H_7CaO_6P$) electrolyte. A small amount of 0.0075M zinc acetate and magnesium acetate were added to the electrolyte to enhance the bioactivity. The mechanical properties of the coated surface of Ti-40Ta-xZr alloys were evaluated by Vickers hardness, roughness test, and elastic modulus using nano-indentation, and the surface wettability was evaluated by measuring the contact angle of the coated surface. In addition, cell activation and differentiation were examined by cell culture of HEK 293 (Human embryonic kidney 293) cell proliferation. Surface properties of the alloys were analyzed by scanning electron microscopy(FE-SEM), EDS, and X-ray diffraction analysis (XRD).

• Journal of Periodontal and Implant Science
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• 제36권3호
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• pp.717-729
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• 2006

The present study was performed to evaluate the effect of tetracycline-BCL on the change of implant surface microstructure according to application time. Implant with pure titanium machined surface, double coated $FBR^{(R)}$ surface and oxidized CellNest surface were utilized. Implant surface was rubbed with $50mg/m{\ell}$ tetracycline-BCL solution for ${\frac{1}{2}}$, 1, $1{\frac{1}{2}}$, 2 and $2{\frac{1}{2}}$min. respectively in the test group. Then, specimens were processed for scanning electron microscopic observation. The results of this study were as follows. 1. Both test and control group showed a few shallow grooves and ridges in pure titanium machined surface implants. There were not significant differences between two groups. 2. The double coated $FBR^{(R)}$ surfaces showed fine crystalline structures. The roughness of surfaces conditioned with tetracycline-BCL was lessened relative to the application time. 3. The oxidized CellNest surfaces showed the porous structures. The surface conditioning with tetracycline-BCI influenced on its micro-morphology. In conclusion, the detoxification of the affected implant surface with $50mg/m{\ell}$ tetracycline-BCL should be applied respectively with different time according to various implant surfaces.

• Korean Journal of Materials Research
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• 제19권3호
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• pp.142-150
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• 2009

In this paper, non-treated ACF (Activated Carbon Fiber) /$TiO_2$ and Zn-treated ACF/$TiO_2$ were prepared. The prepared composites were characterized in terms of their structural crystallinity, elemental identification and photocatalytic activity. XRD patterns of the composites showed that the non-treated ACF/$TiO_2$ composite contained only typical single and clear anatase forms while the Zn-treated ACF/$TiO_2$ contained a mixed anatase and rutile phase with a unique ZnO peak. SEM results show that the titanium complex particles are uniformly distributed on and around the fiber and that the titanium complex particles are more regularly distributed on and around the ACF surfaces upon an increase of the $ZnCl_2$ concentration. These EDX spectra show the presence of peaks from the C, O and Ti elements. Moreover, peaks of the Zn element were observed in the Zn-treated ACF/$TiO_2$ composites. The prominent photocatalytic activity of the Zn-treated ACF/$TiO_2$ can be attributed to the three different effects of photo-degradation: doping, absorptivity by an electron transfer, and adsorptivity of porous ACFs between the Zn-$TiO_2$ and Zn-ACF.