• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.145-151
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• 2021

This study aimed to investigate the efficient conduct of HA coating on Ti Gr4 for the practical use of medical device. Ti Gr4 alloy specimens measuring 𝜱 25mm × 1mm were sprayed with hydroxyapatite using thermal spray according to ASTM F1185-88. The surface was evaluated at #120, #400, #1,000 sandpaper and barrel finishing. Each coating properties was analyzed using SEM, UTS 20,000psi cap. and in vitro cytotoxicity. Surface morphology consists of well molten particles with very little resolidified or unmolten areas. The average Ca/P ratio is 1.74 which is in good agreement with theoretical value of 1.67. The average roughness Ra is very representative of roughness of specimen. The coatings are dense and well adhered to the substrate. The average bond strength was 61.74 MPa with a standard deviation of 4.06 which indicates fairly reliable results for ASTM 633 type tests. Variations in results from jig design, epoxy used, crosshead speeds etc. in vitro cytotoxicity result had a Grade 3. The results of the study are expected to be helpful in osseointegration and plasma-spray HA coated Ti Gr4 are more satisfactory in HA coating thickness elevation which is preferable to any other system.

• Journal of the Korea Convergence Society
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• v.12 no.7
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• pp.125-131
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• 2021

Blue light with strong energy is required for light-curing resin treatment, which is being used more frequently in dentistry. To reduce the risk of exposure to scattered light, we tried to use colored lenses. The tips for light curing machine and a commercially available yellow-type blue-light blocking lens and a yellow lens colored with yellow dye, which are expected to be effective in blocking blue light, were placed in a UV-Vis spectrometer device, and transmission and blocking of blue light were tested respectively. As a result, the average blue light blocking rate of the light curing machine tips was 99.49%, and the C lens with the highest color density among commercially available lenses showed a high blue light blocking rate of 99.54%. In the case of lenses tinted with yellow, the yellow tinted C lens with the highest tint concentration showed 87.57% of blue light blocking rate. It is judged that the side effects related to the eyes caused by blue light can be reduced if a yellow-type commercially available or colored lens is worn along with a light curing machine tip during resin treatment.

• Journal of Food Hygiene and Safety
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• v.31 no.3
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• pp.186-193
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• 2016

An analytical method was developed for the determination of oxathiapiprolin in agricultural commodities. Oxathiapiprolin is a new oomycide (fungicide of piperidinyl thiazole isoxazoline class) which controls downy mildew in cucurbits caused by Pseudoperonospora cubensis (oomycete plant pathogen). Agricultural commodities were extracted with acetonitrile and partitioned with dichloromethane to remove the interference, adjusting pH between 9 and 10 by 1 N sodium hydroxide. After purification by silica SPE cartridge to clean up the interference of organic compounds, they were finally quantified by HPLC-UVD (high performance liquid chromatograph ultraviolet detector) using a wavelength at 260 nm and confirmed by LC-MS (liquid chromatograph mass spectrometer) in electro-spray ionization positive ion mode. The standard calibration curve was linear with coefficients of determination ($r^2$) 1.00 over the calibration ranges (0.025-2.5 mg/L). Recoveries were ranged between 86.7 to 112.7%, with relative standard deviations less than 10% at three concentration levels (LOQ, 10LOQ, and 50LOQ) performing five replicates. The overall results were determined and estimated according to the CODEX guidelines (CAC/GL40). The proposed method for determination of oxathiapiprolin residues in agricultural commodities can be used as an official method.