• Macromolecular Research
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• v.12 no.6
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• pp.608-614
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• 2004

Isotactic polypropylene (PP) surfaces were modified with argon and oxygen plasmas using a radio­frequency (RF) glow discharge at 240 mTorr and 40 W. The changes in topography and surface structure were investigated by atomic force microscopy (AFM) in conjunction with specular reflectance of infrared (IR) microspectroscopy. Under our operating conditions, the AFM image analysis revealed that longer plasma treatment resulted in significant ablation on the PP surface, regardless of the kind of plasma employed, but the topography was dependent on the nature of the gases. Specular reflectance IR spectroscopic analysis indicated that the constant removal of surface material was an important ablative aspect when using either plasma, but the nature of the ablative behavior and the resultant aging effects were clearly dependent on the choice of plasma. The use of argon plasma resulted in a negligible aging effect; in contrast, the use of oxygen plasma caused a noticeable aging effect, which was due to reactions of trapped or isolated radicals with oxygen in air, and was partly responsible for the increased surface area caused by ablation. The use of oxygen plasma is believed to be an advantageous approach to modifying polymeric materials with functionalized surfaces, e.g., for surface grafting of unsaturated monomers and incorporating oxygen-containing groups onto PP.

• Journal of Veterinary Clinics
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• v.27 no.4
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• pp.411-414
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• 2010

Rabbit's cornea is the most common thing that used for researches in ophthalmology, so many experimentations have done. The purpose of this study was to survey the corneal pachymetry, tonometry and specular microscopy in New Zealand white rabbits. Three months old male rabbits ($2.9{\pm}0.2\;kg$) were examined with contact the specular microscope to evaluate the endothelial cell density, coefficiency of variation and the percentage of hexagonal cells in the central cornea. For the pachymetry, ultrasonic pachymeter was used for central cornea in each twenty rabbits, and tonometry was performed forty rabbit's eyes to evaluate the intraocular pressure. Corneal endothelial cell density in New Zealand white rabbit was $3304{\pm}354\;cell/mm^2$. Coefficiency of variation was $45.8{\pm}2$ and the percentage of hexagonal cells in the central cornea was $44.4{\pm}11%$. The pachymetry of cornea was $346.1{\pm}21\;{\mu}m$ and tonometry of eye was $14.3{\pm}2\;mmHg$. It is considered that normal New Zealand white rabbit's pachymetry, specular microscopy and tonometry were useful basic data of rabbit's cornea for research and clinic in veterinary ophthalmology.

• Macromolecular Research
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• v.12 no.1
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• pp.134-140
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• 2004

Semi-crystalline poly(ethylene terephthalate) (PET) film surfaces were modified with argon and oxygen plasmas by radio-frequency (RF) glow discharge at 240 mTorr/40 W; the changes in topography and surface structure were investigated by atomic force microscopy (AFM) in conjunction with specular reflectance of infrared microspectroscopy (IMS). Under our operating conditions, analysis of the AFM images revealed that longer plasma treatment results in significant ablation on the film surface with increasing roughness, regardless of the kind of plasma used. The basic topographies, however, were different depending upon the kind of gas used. The specular reflectance analysis showed that the ablative mechanisms of the argon and oxygen plasma treatments are entirely different with one another. For the Ar-plasma-treated PET surface, no observable difference in the chemical structure was observed before and after plasma treatment. On the other hand, the oxygen-plasma-treated PET surface displays a significant decrease in the number of aliphatic C-H groups. We conclude that a constant removal of material from the PET surface occurs when using the Ar-plasma, whereas preferential etching of aliphatic C-H groups, with respect to, e.g. , carbonyl and ether groups, occurs upon oxygen plasma.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.19.2-19.2
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• 2011

The $(Sr_{0.75},\;La_{0.25})TiO_3$ (SLTO) ultra-thin films with various thicknesses have been grown on Ti-O terminated $SrTiO_3$(100) substrate using Laser-Molecular Beam Epitaxy (Laser MBE). By monitoring the in-situ specular spot intensity oscillation of reflection high energy electron diffraction (RHEED), we controlled the layer-by-layer film growth. The film structure and topography were verified by atomic force microscopy (AFM) and high resolution thin film x-ray diffraction by the synchrotron x-ray radiation. We have also investigated the electronic band structure using x-ray absorption spectroscopy (XAS). The ultra thin SLTO film exhibits thickness driven metal-insulator transition around 8 unit cell thickness when the film thickness progressively reduced to 2 unit cell. The SLTO thin films with an insulating character showed band splitting in Ti $L_3-L_2$ edge XAS spectrum which is attributed to Ti 3d band splitting. This narrow d band splitting could drive the metal-insulator transition along with Anderson Localization. In optical conductivity, we have found the spectral weight transfer from coherent part to incoherent part when the film thickness was reduced. This result indicates the possibility of enhanced electron correlation in ultra thin films.

• Journal of The Korean Ophthalmological Society
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• v.59 no.11
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• pp.1077-1081
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• 2018

Purpose: We report two cases of corneal edema in patients who presented with bilateral blurry vision due to vaporized amines while working in a polyurethane processing plant. Case summary: A 28-year-old male presented with bilateral blurred vision. His work involved solidifying polyurethane liquid and he often found himself exposed to polyurethane heat and gas. Purpose: We report two cases of corneal edema in patients who presented with bilateral blurry vision due to vaporized amines while working in a polyurethane processing plant. Case summary: A 28-year-old male presented with bilateral blurred vision. His work involved solidifying polyurethane liquid and he often found himself exposed to polyurethane heat and gas. On examination, the patient's uncorrected visual acuity (UCVA) was 20/40 (right) and 30/50 (left). A slit lamp examination revealed subepithelial microbullae in both eyes. The central corneal thickness (CCT) was also increased in both eyes, measuring $698{\mu}m$ (right) and $672{\mu}m$ (left). After prescribing 0.5% moxifloxacin and, 1% fluorometholone eye drops for 3 days in both eyes, the UCVA recovered to 20/40 (right) and 20/20 (left). The CCT decreased to $644{\mu}m$ (right) and $651{\mu}m$ (left), and the microbullae improved significantly in the left eye. The second patient was a 34-year-old female who presented with bilateral decreased visual acuity while at work. She worked in a factory that produced car seat filling. Her UCVA was 20/25 (right) and 20/20 (left). The CCT by specular microscopy was $537{\mu}m$ (right) and $541{\mu}m$ (left). On slit lamp examination, both eyes demonstrated bilateral central subepithelial edema. The patient did not attend any follow-up outpatient appointments after the initial presentation. Conclusions: Exposure to vaporized amines such as polyurethane may causereversible corneal toxicityeven without direct contact. Further consideration should be given to ocular safety and protection from amine compounds in the industrial field.On examination, the patient's uncorrected visual acuity (UCVA) was 20/40 (right) and 30/50 (left). A slit lamp examination revealed subepithelial microbullae in both eyes. The central corneal thickness (CCT) was also increased in both eyes, measuring $698{\mu}m$ (right) and $672{\mu}m$ (left). After prescribing 0.5% moxifloxacin and, 1% fluorometholone eye drops for 3 days in both eyes, the UCVA recovered to 20/40 (right) and 20/20 (left). The CCT decreased to $644{\mu}m$ (right) and $651{\mu}m$ (left), and the microbullae improved significantly in the left eye. The second patient was a 34-year-old female who presented with bilateral decreased visual acuity while at work. She worked in a factory that produced car seat filling. Her UCVA was 20/25 (right) and 20/20 (left). The CCT by specular microscopy was $537{\mu}m$ (right) and $541{\mu}m$ (left). On slit lamp examination, both eyes demonstrated bilateral central subepithelial edema. The patient did not attend any follow-up outpatient appointments after the initial presentation. Conclusions: Exposure to vaporized amines such as polyurethane may causereversible corneal toxicityeven without direct contact. Further consideration should be given to ocular safety and protection from amine compounds in the industrial field.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.454-454
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• 2014

Silicon microwire array is one of the promising platforms as a means for developing highly efficient solar cells thanks to the enhanced light trapping efficiency. Among the various fabrication methods of microstructures, deep reactive ion etching (DRIE) process has been extensively used in fabrication of high aspect ratio microwire arrays. In this presentation, we show precisely controlled Si microwire arrays by tuning the DRIE process conditions. A periodic microdisk arrays were patterned on 4-inch Si wafer (p-type, $1{\sim}10{\Omega}cm$) using photolithography. After developing the pattern, 150-nm-thick Al was deposited and lifted-off to leave Al microdisk arrays on the starting Si wafer. Periodic Al microdisk arrays (diameter of $2{\mu}m$ and periodic distance of $2{\mu}m$) were used as an etch mask. A DRIE process (Tegal 200) is used for anisotropic deep silicon etching at room temperature. During the process, $SF_6$ and $C_4F_8$ gases were used for the etching and surface passivation, respectively. The length and shape of microwire arrays were controlled by etching time and $SF_6/C_4F_8$ ratio. By adjusting $SF_6/C_4F_8$ gas ratio, the shape of Si microwire can be controlled, resulting in the formation of tapered or vertical microwires. After DRIE process, the residual polymer and etching damage on the surface of the microwires were removed using piranha solution ($H_2SO_4:H_2O_2=4:1$) followed by thermal oxidation ($900^{\circ}C$, 40 min). The oxide layer formed through the thermal oxidation was etched by diluted hydrofluoric acid (1 wt% HF). The surface morphology of a Si microwire arrays was characterized by field-emission scanning electron microscopy (FE-SEM, Hitachi S-4800). Optical reflection measurements were performed over 300~1100 nm wavelengths using a UV-Vis/NIR spectrophotometer (Cary 5000, Agilent) in which a 60 mm integrating sphere (Labsphere) is equipped to account for total light (diffuse and specular) reflected from the samples. The total reflection by the microwire arrays sample was reduced from 20 % to 10 % of the incident light over the visible region when the length of the microwire was increased from $10{\mu}m$ to $30{\mu}m$.