98 results on '"Seok-Hong Min"'
Search Results
2. Properties and filtration performance of microporous metal membranes fabricated by rolling process
- Author
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Jiyeong Park, Seok-Hong Min, Won-Hee Lee, No-Suk Park, Hyung-Soo Kim, and Jong-Oh Kim
- Subjects
metal mesh ,metal powder ,metal wire ,porous metal membrane ,rolling ,sintering ,Water supply for domestic and industrial purposes ,TD201-500 - Abstract
We evaluated the filtration performance of microporous metal membranes fabricated by the rolling process. Metal wire meshes were rolled with thickness reduction ratios of 10, 20, and 30%. The pore size of the metal wire mesh membrane decreased with increasing rolling ratio, whereas the removal efficiency of the suspended solids and turbidity showed a very slight increase compared to that of an unrolled mesh membrane. The metal powder was dispersed on the surface of the rolled metal wire mesh membrane and bound with polyvinyl alcohol, then dried at 100°C for 1 h, and finally sintered at 1,000°C for 3 h. The mean pore size, suspended solids, and turbidity of the metal powder membrane at a rolling ratio of 30% were approximately 0.7 μm, 84% and 83%, respectively. Therefore, microporous metal membranes successfully fabricated by the rolling process were also sufficiently permeable filters.
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- 2017
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3. Spark Plasma Sintering Behavior of Nb-Mo-Si Alloy Powders Fabricated by Hydrogenation-Dehydrogenation Method
- Author
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Sung Yong Lee, Ki Beom Park, Jang-Won Kang, Yanghoo Kim, Hyun-Su Kang, Tae Kwon Ha, Seok-Hong Min, and Hyung-Ki Park
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nb-mo-si alloy ,nb silicide-based composite ,powder ,spark plasma sintering ,sintering behavior ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
In this study, the sintering behaviors of Nb-6Mo-20Si-3Cr (at percentage) in situ composite powders were studied. The Nb alloy powder was fabricated by a hydrogenation-dehydrogenation method, and both the alloy ingot and powders consisted of two phases: An Nb metal phase and the α-Nb5Si3 phase. Consolidation of the alloy powders was performed at 1500, 1600, and 1700 °C using spark plasma sintering, and the microstructures and phases formed at various sintering temperatures were analyzed. Micropores were observed in the compact sintered at 1500 °C due to the lack of complete densification at that temperature. The densification was completed at 1600 °C and the microstructure was slightly coarsened at 1700 °C compared to the microstructure of the compact sintered at 1600 °C. The microstructures prepared by the powder metallurgy method were finer than the microstructure of the ingot prepared by the casting method. The phase formation behavior varied according to the sintering temperature. Specifically, the α-Nb5Si3 phase, which is a stable structure of the Nb5Si3 phase at a low temperature, was transformed to the β-Nb5Si3 phase (which is stable at a high temperature) with an increasing sintering temperature.
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- 2019
- Full Text
- View/download PDF
4. AAV-Mediated Clarin-1 Expression in the Mouse Retina: Implications for USH3A Gene Therapy.
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Astra Dinculescu, Rachel M Stupay, Wen-Tao Deng, Frank M Dyka, Seok-Hong Min, Sanford L Boye, Vince A Chiodo, Carolina E Abrahan, Ping Zhu, Qiuhong Li, Enrica Strettoi, Elena Novelli, Kerstin Nagel-Wolfrum, Uwe Wolfrum, W Clay Smith, and William W Hauswirth
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Medicine ,Science - Abstract
Usher syndrome type III (USH3A) is an autosomal recessive disorder caused by mutations in clarin-1 (CLRN1) gene, leading to progressive retinal degeneration and sensorineural deafness. Efforts to develop therapies for preventing photoreceptor cell loss are hampered by the lack of a retinal phenotype in the existing USH3 mouse models and by conflicting reports regarding the endogenous retinal localization of clarin-1, a transmembrane protein of unknown function. In this study, we used an AAV-based approach to express CLRN1 in the mouse retina in order to determine the pattern of its subcellular localization in different cell types. We found that all major classes of retinal cells express AAV-delivered CLRN1 driven by the ubiquitous, constitutive small chicken β-actin promoter, which has important implications for the design of future USH3 gene therapy studies. Within photoreceptor cells, AAV-expressed CLRN1 is mainly localized at the inner segment region and outer plexiform layer, similar to the endogenous expression of other usher proteins. Subretinal delivery using a full strength viral titer led to significant loss of retinal function as evidenced by ERG analysis, suggesting that there is a critical limit for CLRN1 expression in photoreceptor cells. Taken together, these results suggest that CLRN1 expression is potentially supported by a variety of retinal cells, and the right combination of AAV vector dose, promoter, and delivery method needs to be selected to develop safe therapies for USH3 disorder.
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- 2016
- Full Text
- View/download PDF
5. Pure copper nanoparticles prepared by coating-assisted vapor phase synthesis without agglomeration
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Yong-Su Jo, Hye-Min Park, Gwang-Hwa Jin, Bhabani Sankar Swain, Seok-Hong Min, Young Keun Kim, and Seung-Min Yang
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General Chemical Engineering ,General Chemistry - Abstract
Modern electronic devices, such as smartphones and electric vehicles, require multilayer ceramic capacitors (MLCCs), which comprise highly pure Cu terminations and Ni electrodes. Vapor-phase synthesis (VPS) is a promising method for synthesizing nanoparticles (NPs) with high purity and crystallinity. However, the agglomeration of the NPs occurs during their synthesis, which degrades the performance of the MLCC electrodes owing to several factors, including electrical shorts and low packing density. This paper proposes a coating-assisted VPS to inhibit agglomeration using potassium chloride (KCl) as the coating agent. The agglomeration ratio of the Cu NPs synthesized by in-flight coating with KCl at 950 °C significantly decreased from 48.20% to 3.80%, compared to without KCl coating. Furthermore, X-ray fluorescence and X-ray diffraction analyses confirmed that the KCl coating agent and residual copper chloride were removed by washing with ammonium hydroxide.
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- 2022
6. Chemical Vapor Synthesis of Nonagglomerated Nickel Nanoparticles by In-Flight Coating
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Hui-Jung Lee, Hye-Min Park, Seok-Hong Min, Jin-Seung Jung, Yong-Su Jo, Young Keun Kim, Seung-Min Yang, and Tae-Wook Na
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Materials science ,Scanning electron microscope ,General Chemical Engineering ,Nanoparticle ,chemistry.chemical_element ,General Chemistry ,engineering.material ,equipment and supplies ,Article ,Nickel ,Crystallinity ,Chemistry ,Coating ,Distilled water ,chemistry ,Chemical engineering ,Agglomerate ,engineering ,Ceramic capacitor ,QD1-999 - Abstract
Nickel (Ni) nanoparticles (NPs) prepared through vapor-phase synthesis (VPS) are preferred for multilayer ceramic capacitor electrodes due to their high purity and crystallinity advantages. Agglomerated Ni NPs are usually generated using VPS but are undesirable because they cause various problems such as low packing density and electrical shorts. This study proposes the use of coating-assisted chemical vapor synthesis (CVS) for agglomerate inhibition using NaCl or KCl as a coating agent. We have found that the agglomeration ratio, 34.40%, for conventional CVS, can be reduced to 4.80% in the proposed method by in-flight coating with KCl at 900 °C by image analysis using field-emission scanning electron microscopy. Furthermore, the X-ray diffraction and X-ray fluorescence analyses confirm that the NaCl and KCl coating agent can be removed by washing with distilled water. We believe that this coating process can be used to inhibit the formation of agglomerates during the CVS of Ni NPs.
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- 2021
7. Sulfur-Mediated Synthesis of Spherical Nickel Nanoparticles in a Chemical Vapor Reactor
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Yong-Su Jo, Mansurbek Abdullaev, Gwang-Hwa Jin, Bhabani Sankar Swain, Byongpil Lee, Hyung-Sub Eom, Seok-Hong Min, Seok Ki Kim, Young Keun Kim, and Seung-Min Yang
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General Chemical Engineering ,General Chemistry - Abstract
In this study, we investigated the effect of the sulfur content in the NiCl
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- 2022
8. Synthesis of Nb-Mo-Si based in situ composite powder by a hydrogenation-dehydrogenation reaction
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Hyung-Ki Park, Sung Yong Lee, Won-Hyuk Lee, Seok-Hong Min, Ki Beom Park, and Tae Kwon Ha
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Materials science ,Hydrogen ,Mechanical Engineering ,Alloy ,chemistry.chemical_element ,02 engineering and technology ,Vacuum arc ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Lattice constant ,Chemical engineering ,chemistry ,Mechanics of Materials ,Silicide ,engineering ,General Materials Science ,Dehydrogenation ,Ingot ,0210 nano-technology ,Solid solution - Abstract
Nb-Mo-Si based in situ composite powders were fabricated by a hydrogenation-dehydrogenation reaction. The Nb-6Mo-20Si-3Cr alloy ingot was prepared by vacuum arc melting and was composed of a metal solid solution phase and a (Nb, Mo)5Si3 silicide phase. For hydrogenation, the ingot was annealed under a hydrogen atmosphere and the hydrogenated ingot could be easily pulverized by milling due to its brittle nature. As a result of absorbing hydrogen, the hydrogenated powder had a higher hydrogen concentration and lattice parameter than the ingot. The powder was annealed under a vacuum atmosphere for dehydrogenation and the hydrogen concentration and lattice parameter decreased to the same value as those of the ingot. By applying the hydrogenation-dehydrogenation method, Nb-6Mo-20Si-3Cr alloy powder could be successfully fabricated.
- Published
- 2019
9. Corrosion behaviors of friction welded dissimilar aluminum alloys
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Kwangsuk Park, Sori Won, Seok-Hong Min, Kuk Hyun Song, Jong Min Park, Tae Kwon Ha, Hyo Kyu Kim, and Bosung Seo
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010302 applied physics ,Materials science ,Passivation ,Mechanical Engineering ,Metallurgy ,chemistry.chemical_element ,02 engineering and technology ,Welding ,Electrolyte ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,law.invention ,Corrosion ,Cathodic protection ,Galvanic corrosion ,chemistry ,Mechanics of Materials ,law ,Aluminium ,0103 physical sciences ,General Materials Science ,Nyquist plot ,0210 nano-technology - Abstract
Corrosion behaviors of the friction welded dissimilar aluminum alloys were investigated to understand how galvanic effect plays a role in altering corrosion properties of the dissimilar weld. From the fact that the weld had the similar OCP value to that of AA2017, it can be inferred that the corrosion characteristics of the weld is under the control of the AA2017 part in the weld and as a result, only the AA2017 part in the weld had experienced severe corrosion, leaving AA6063 under cathodic protection. Intense corrosion occurring near the interface implies that the area near the interface is placed under the effect of galvanic corrosion and there was the effective distance where the galvanic effect exerts an impact due to the increase in the resistance of the electrolyte with the distance from the interface. The disappearance of Warburg diffusion plot in Nyquist plots for the weld seemed to be the breakdown of the passivation layer related to the formation of the micro-galvanic cell, which in turn presented the shrinkage in the capacitance response, indicating that charge reactions in the form of corrosion occurred.
- Published
- 2018
10. High spatial density nanocrystal formation using thin layer of amorphous Si0.7Ge0.3 deposited on SiO2
- Author
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Tae-Sik Yoon, Jang-Yeon Kwon, Dong-Hoon Lee, Ki-Bum Kim, Seok-Hong Min, Dong-Hyuk Chae, Dae Hwan Kim, Jong Duk Lee, Byung-Gook Park, and Hwack Joo Lee
- Subjects
Amorphous semiconductors -- Research ,Electronic structure -- Research ,Flash memory -- Research ,Physics - Abstract
A new study uses the agglomeration and partial oxidation of thin amorphous Si0.7Ge0.3 layer deposited on SiO2 to make nanocrystals with a high spatial density and small size.
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- 2000
11. Atmosphere Gas Carburizing for Improved Wear Resistance of Pure Titanium Fabricated by Additive Manufacturing
- Author
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Seok-Hong Min, Hyung Guin Kim, Chang-Woo Lee, Kyung-Hwan Jung, Hyo Kyu Kim, Hyung-Ki Park, Byung-Soo Lee, and Tae Kwon Ha
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0209 industrial biotechnology ,Materials science ,Mechanical Engineering ,Metallurgy ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Carburizing ,Atmosphere ,Wear resistance ,020901 industrial engineering & automation ,chemistry ,Mechanics of Materials ,General Materials Science ,0210 nano-technology ,Titanium - Published
- 2017
12. Recrystallization Behavior of Aluminum Plates Depending on Their Purities
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Hyung-Ki Park, Tae Kwon Ha, Hyun-Woo Lee, and Seok-Hong Min
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010302 applied physics ,Materials science ,Annealing (metallurgy) ,Kinetics ,Metallurgy ,Analytical chemistry ,Recrystallization (metallurgy) ,02 engineering and technology ,Activation energy ,021001 nanoscience & nanotechnology ,01 natural sciences ,Isothermal process ,0103 physical sciences ,General Materials Science ,Grain boundary migration ,0210 nano-technology ,Grain orientation ,Electron backscatter diffraction - Abstract
Recrystallization behavior has been investigated for commercial purity AA1050 (99.5wt%Al) and high purity 3N Al (99.9wt% Al). Samples were cold rolled with 90% of thickness reduction and were annealed isothermally at 290, 315, and 350oC for various times until complete recrystallization was achieved. Hardness measurement and Electron Backscatter Diffraction(EBSD) analyses, combined with Grain Orientation Spread(GOS), were employed to investigate the recrystallization behavior. EBSD analysis combined with GOS were distinctly revealed to be a more useful method to determine the recrystallization fraction and to characterize the recrystallization kinetics. As the annealing temperature increased, recrystallization in AA1050 accelerated more than that process did in Al 3N. Both AA1050 and Al 3N showed the same temperature dependence of the n value of the Johnson-Mehl-Avrami-Kolmogorov equation(JMAK equation), i.e., n values increased as annealing temperature increased. Activation energy of recrystallization in AA1050 is about 176 kJ/mol, which is comparable with the activation energy of grain boundary migration in cold-rolled AA1050. This value is somewhat higher than the activation energy of recrystallization in Al 3N.
- Published
- 2016
13. Spark Plasma Sintering Behavior of Nb-Mo-Si Alloy Powders Fabricated by Hydrogenation-Dehydrogenation Method
- Author
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Hyung-Ki Park, Sung Yong Lee, Seok-Hong Min, Ki Beom Park, Yanghoo Kim, Tae Kwon Ha, Jang-Won Kang, and Hyun-Su Kang
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Materials science ,Alloy ,Composite number ,nb-mo-si alloy ,Sintering ,Spark plasma sintering ,engineering.material ,powder ,lcsh:Technology ,Article ,sintering behavior ,Powder metallurgy ,General Materials Science ,Dehydrogenation ,nb silicide-based composite ,Ingot ,lcsh:Microscopy ,lcsh:QC120-168.85 ,lcsh:QH201-278.5 ,lcsh:T ,Metallurgy ,Microstructure ,lcsh:TA1-2040 ,engineering ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:TK1-9971 ,spark plasma sintering - Abstract
In this study, the sintering behaviors of Nb-6Mo-20Si-3Cr (at percentage) in situ composite powders were studied. The Nb alloy powder was fabricated by a hydrogenation-dehydrogenation method, and both the alloy ingot and powders consisted of two phases: An Nb metal phase and the α-Nb5Si3 phase. Consolidation of the alloy powders was performed at 1500, 1600, and 1700 °C using spark plasma sintering, and the microstructures and phases formed at various sintering temperatures were analyzed. Micropores were observed in the compact sintered at 1500 °C due to the lack of complete densification at that temperature. The densification was completed at 1600 °C and the microstructure was slightly coarsened at 1700 °C compared to the microstructure of the compact sintered at 1600 °C. The microstructures prepared by the powder metallurgy method were finer than the microstructure of the ingot prepared by the casting method. The phase formation behavior varied according to the sintering temperature. Specifically, the α-Nb5Si3 phase, which is a stable structure of the Nb5Si3 phase at a low temperature, was transformed to the β-Nb5Si3 phase (which is stable at a high temperature) with an increasing sintering temperature.
- Published
- 2019
14. Recrystallization Behavior of Aluminum Thin Foils with Various Purity
- Author
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Tae Kwon Ha, Hyun Woo Lee, and Seok Hong Min
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Materials science ,Annealing (metallurgy) ,Mechanical Engineering ,Metallurgy ,Alloy ,chemistry.chemical_element ,Recrystallization (metallurgy) ,engineering.material ,Condensed Matter Physics ,chemistry ,Mechanics of Materials ,Aluminium ,engineering ,General Materials Science - Abstract
Recrystallization kinetics of aluminum with various purities from 99.5 to 99.999(5N) has been investigated in this study. Aluminum plates of 10 mm thickness with various purities were solution-treated at 400oC for 24 hrs and then rolled into sheets of 50 μm thickness at room temperature. Cold rolling was conducted on samples with various purities from 99.9 to 99.999 including commercial AA 1050 Al alloy and high purity through about 20 passes to obtain thin foils of 50 μm thickness. Accumulative rolling was employed when sample thickness reached at 1 mm and thin foils were successfully obtained for all samples. Hardness was measured just after cold rolling at room temperature as a function of time up to 1hr to elucidated recrystallization behavior. For aluminum with 99.999% purity, recrystallization occurred after 200 s and finished at 360 s. Recrystallization kinetics of aluminum at high temperatures from 100 to 350oC were investigated by measure hardness after annealing thin foils for various time intervals ranging from 1 s to 24 hrs. For high purity sample with 99.999% purity, recrystallization finished just after 1 s even at the relatively low temperature of 100oC, while recrystallization of commercial AA 1050 (2N) alloy finished after 360 s at 350oC.
- Published
- 2016
15. Effect of Boron Addition on Microstructure and Mechanical Properties of AZ84 Mg Alloy
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Ju Hyun Won, Seok Hong Min, and Tae Kwon Ha
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Supersaturation ,Materials science ,Mechanical Engineering ,Metallurgy ,Alloy ,chemistry.chemical_element ,engineering.material ,Condensed Matter Physics ,Compression (physics) ,Microstructure ,Matrix (chemical analysis) ,chemistry ,Mechanics of Materials ,Phase (matter) ,engineering ,General Materials Science ,Boron ,Solid solution - Abstract
Effect of B addition on the microstructure and mechanical properties of AZ84 Mg alloy was investigated in this study. Through calculation of phase equilibria of AZ84 Mg alloy, carried out by using FactSage® and FTLite database, solution treatment temperature was decided as temperature of 330oC, where supersaturated solid solution can be obtained. Solid solution treatment of AZ84 Mg alloy was successfully conducted at 330oC and supersaturated microstructure with all almost all phases resolved into matrix was obtained. After solution treatment, hot rolling was successfully conducted by reduction of 60%. Compression and tension tests were carried out at room temperature on the samples in as-cast, solution treated, hot-rolled and subsequently recrystallized states. After solid solution treatment, each alloy was soaked at temperatures of 180 and 200oC for time intervals from 1 min to 48 hrs and hardness of each condition was measured by micro-Vickers method. Peak aging conditions were deduced as at the temperature of 200 oC for 10 hrs for ZA84 Mg alloy. By addition of boron, aging kinetics was expedited and strength was enhanced.
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- 2016
16. Orientation Dependence of the Hardness and Strength of Mg and Mg Alloys
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Seok Hong Min, Tae Kwon Ha, and Kyung-Nam Kim
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Materials science ,Mg alloys ,General Materials Science ,Composite material ,Orientation (graph theory) - Published
- 2016
17. Orientation Dependence of Flow Behavior of Mg Single Crystal
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Seok Hong Min, Tae Kwon Ha, and Ji Chan Kim
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Diffraction ,Materials science ,Magnesium ,Mechanical Engineering ,chemistry.chemical_element ,Electron ,Condensed Matter Physics ,Crystallography ,Compressive strength ,chemistry ,Mechanics of Materials ,Orientation (geometry) ,General Materials Science ,Compression (geology) ,Composite material ,Single crystal ,Electron backscatter diffraction - Abstract
Single crystals of pure magnesium were fabricated in this study by employing the modified Bridgman method. To determine the exact orientation of crystals, electron back scattered diffraction (EBSD) method was employed in this study. Dimensions of single crystals were 10 mm in diameter and 120 mm in length. Single crystals with near basal, pyramidal, and near prismatic orientations were obtained, on which hardness and compression tests were conducted. It has been revealed that hardness and the strength strongly depended on the orientation. While the hardness of pyramidal orientation was highest and that of near prismatic orientation was lowest, the compressive strength along near prismatic orientation appeared to be highest and that along prismatic orientation was lowest.
- Published
- 2016
18. Cross-layer Design of Joint Routing and Scheduling for Maximizing Network Capacity of IEEE 802.11s based Multi-Channel SmartGrid NAN Networks
- Author
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Jae-Yong Lee, Byung-Chul Kim, Seok Hong Min, and Bong Gyu Kim
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Wireless mesh network ,Computer science ,business.industry ,Distributed computing ,020206 networking & telecommunications ,02 engineering and technology ,Scheduling (computing) ,Smart grid ,Convex optimization ,0202 electrical engineering, electronic engineering, information engineering ,Link layer ,business ,Efficient energy use ,IEEE 802.11s ,Computer network ,Data transmission - Abstract
The goal of the SmartGrid is to maximize energy efficiency by exchanging bi-directional real-time power information with the help of ICT(Information and Communication Technology). In this paper, we propose a “JRS-MS” (Joint Routing and Scheduling for Multi-channel SmartGrid) algorithm that uses numerical modeling methods in IEEE 802.11s based STDMA multi-channel SmartGrid NAN networks. The proposed algorithm controls the amount of data transmission adaptively at the link layer and finds a high data-rate path which has the least interference between traffic flows in multi-channel SmartGrid NAN networks. The proposed algorithm improve transmission performance by enhancing network utilization. By comparing the results of performance analysis between the proposed algorithm and the JRS-SG algorithm [11] in the previous paper, we showed that the JRS-MS algorithm can improve transmission performance by maximally utilizing given network resources when the number of flows are increasing in the multi-hop NAN wireless mesh networks.
- Published
- 2016
19. Maintaining ocular safety with light exposure, focusing on devices for optogenetic stimulation
- Author
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Boyuan Yan, Sheila Nirenberg, Maksim Vakulenko, William W. Hauswirth, and Seok-Hong Min
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0301 basic medicine ,Retinal degeneration ,Light ,Photic Stimulation ,Computer science ,Stimulation ,Stimulus (physiology) ,Optogenetics ,Article ,Retina ,Cornea ,03 medical and health sciences ,chemistry.chemical_compound ,Optics ,medicine ,Animals ,Humans ,Rats, Long-Evans ,Eye Proteins ,business.industry ,Retinal Degeneration ,Retinal ,medicine.disease ,Sensory Systems ,Rats ,Visual Prosthesis ,Ophthalmology ,030104 developmental biology ,chemistry ,Visual prosthesis ,Visual angle ,business ,Neuroscience - Abstract
Optogenetics methods are rapidly being developed as therapeutic tools for treating neurological diseases, in particular, retinal degenerative diseases. A critical component of the development is testing the safety of the light stimulation used to activate the optogenetic proteins. While the stimulation needs to be sufficient to produce neural responses in the targeted retinal cell class, it also needs to be below photochemical and photothermal limits known to cause ocular damage. The maximal permissible exposure is determined by a variety of factors, including wavelength, exposure duration, visual angle, pupil size, pulse width, pulse pattern, and repetition frequency. In this paper, we develop utilities to systematically and efficiently assess the contributions of these parameters in relation to the limits, following directly from the 2014 American National Standards Institute (ANSI). We also provide an array of stimulus protocols that fall within the bounds of both safety and effectiveness. Additional verification of safety is provided with a case study in rats using one of these protocols.
- Published
- 2016
20. Properties and filtration performance of microporous metal membranes fabricated by rolling process
- Author
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Jong-Oh Kim, J.K. Park, Hyung-Soo Kim, Seok-Hong Min, No-Suk Park, and Won-Hee Lee
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Materials science ,Filtration and Separation ,02 engineering and technology ,metal wire ,01 natural sciences ,Polyvinyl alcohol ,law.invention ,Metal ,chemistry.chemical_compound ,lcsh:Water supply for domestic and industrial purposes ,law ,0103 physical sciences ,Composite material ,Turbidity ,Filtration ,Water Science and Technology ,010302 applied physics ,sintering ,lcsh:TD201-500 ,Suspended solids ,metal powder ,metal mesh ,Microporous material ,021001 nanoscience & nanotechnology ,Membrane ,chemistry ,visual_art ,visual_art.visual_art_medium ,Metal powder ,rolling ,0210 nano-technology ,porous metal membrane - Abstract
We evaluated the filtration performance of microporous metal membranes fabricated by the rolling process. Metal wire meshes were rolled with thickness reduction ratios of 10, 20, and 30%. The pore size of the metal wire mesh membrane decreased with increasing rolling ratio, whereas the removal efficiency of the suspended solids and turbidity showed a very slight increase compared to that of an unrolled mesh membrane. The metal powder was dispersed on the surface of the rolled metal wire mesh membrane and bound with polyvinyl alcohol, then dried at 100°C for 1 h, and finally sintered at 1,000°C for 3 h. The mean pore size, suspended solids, and turbidity of the metal powder membrane at a rolling ratio of 30% were approximately 0.7 μm, 84% and 83%, respectively. Therefore, microporous metal membranes successfully fabricated by the rolling process were also sufficiently permeable filters.
- Published
- 2016
21. Co-Expression of Wild-Type and Mutant S163R C1QTNF5 in Retinal Pigment Epithelium
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Astra, Dinculescu, Frank M, Dyka, Seok-Hong, Min, Rachel M, Stupay, Marcus J, Hooper, W Clay, Smith, and William W, Hauswirth
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Genetic Vectors ,Mutation, Missense ,Cell Polarity ,Retinal Pigment Epithelium ,Dependovirus ,Protein Aggregation, Pathological ,Recombinant Proteins ,Mice, Inbred C57BL ,Macular Degeneration ,Mice ,Electroretinography ,Animals ,Humans ,Point Mutation ,Collagen ,Injections, Intraocular ,Genes, Dominant ,Subcellular Fractions - Abstract
The pathogenic mutation S163R in C1QTNF5 causes a disorder known as autosomal dominant late-onset retinal degeneration (L-ORD), characterized by the presence of thick extracellular sub-RPE deposits, similar histopathologically to those found in AMD patients. We have previously shown that the S163R C1QTNF5 mutant forms globular aggregates within the RPE in vivo following its AAV-mediated expression in the RPE and exhibits a reversely polarized distribution, being routed toward the basal rather than apical RPE. We show here that when both wild-type and mutant S163R C1QTNF5 are simultaneously delivered subretinally to mouse RPE cells, the mutant impairs the wild-type protein secretion from the RPE, and both proteins are dispersed toward the basal and lateral RPE membrane. This result has mechanistic and therapeutic implications for L-ORD disorder.
- Published
- 2018
22. Co-Expression of Wild-Type and Mutant S163R C1QTNF5 in Retinal Pigment Epithelium
- Author
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Astra Dinculescu, Frank M. Dyka, William W. Hauswirth, Seok-Hong Min, Marcus Hooper, W. Clay Smith, and Rachel M Stupay
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0301 basic medicine ,Retinal degeneration ,Retinal pigment epithelium ,medicine.diagnostic_test ,Chemistry ,Mutant ,Wild type ,medicine.disease ,eye diseases ,Cell biology ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,medicine.anatomical_structure ,Secretory protein ,Cell polarity ,030221 ophthalmology & optometry ,medicine ,Extracellular ,sense organs ,Electroretinography - Abstract
The pathogenic mutation S163R in C1QTNF5 causes a disorder known as autosomal dominant late-onset retinal degeneration (L-ORD), characterized by the presence of thick extracellular sub-RPE deposits, similar histopathologically to those found in AMD patients. We have previously shown that the S163R C1QTNF5 mutant forms globular aggregates within the RPE in vivo following its AAV-mediated expression in the RPE and exhibits a reversely polarized distribution, being routed toward the basal rather than apical RPE. We show here that when both wild-type and mutant S163R C1QTNF5 are simultaneously delivered subretinally to mouse RPE cells, the mutant impairs the wild-type protein secretion from the RPE, and both proteins are dispersed toward the basal and lateral RPE membrane. This result has mechanistic and therapeutic implications for L-ORD disorder.
- Published
- 2018
23. Gene Therapy Fully Restores Vision to the All-Cone Nrl−/−Gucy2e−/− Mouse Model of Leber Congenital Amaurosis-1
- Author
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Qing Ruan, K. Tyler McCullough, Elena V. Olshevskaya, Seok Hong Min, Shreyasi Choudhury, William W. Hauswirth, Jim Peterson, Xi-Qin Ding, Shannon E. Boye, Igor V. Peshenko, Zhonghong Zhang, Sanford L. Boye, and Alexander M. Dizhoor
- Subjects
Opsin ,genetic structures ,Genetic enhancement ,Genetic Vectors ,Leber Congenital Amaurosis ,Receptors, Cell Surface ,Biology ,Retinal Cone Photoreceptor Cells ,chemistry.chemical_compound ,Genetics ,medicine ,Animals ,Eye Proteins ,Molecular Biology ,Vision, Ocular ,Research Articles ,Mice, Knockout ,Retina ,Opsins ,Guanylate cyclase activity ,Retinal ,Genetic Therapy ,Dependovirus ,Molecular biology ,Mice, Inbred C57BL ,Disease Models, Animal ,Basic-Leucine Zipper Transcription Factors ,Treatment Outcome ,medicine.anatomical_structure ,chemistry ,Guanylate Cyclase ,Molecular Medicine ,GUCY2D ,sense organs ,Injections, Intraocular ,Cyclase activity - Abstract
Mutations in GUCY2D are the cause of Leber congenital amaurosis type 1 (LCA1). GUCY2D encodes retinal guanylate cyclase-1 (retGC1), a protein expressed exclusively in outer segments of photoreceptors and essential for timely recovery from photoexcitation. Recent clinical data show that, despite a high degree of visual disturbance stemming from a loss of cone function, LCA1 patients retain normal photoreceptor architecture, except for foveal cone outer segment abnormalities and, in some patients, foveal cone loss. These results point to the cone-rich central retina as a target for GUCY2D replacement. LCA1 gene replacement studies thus far have been conducted in rod-dominant models (mouse) or with vectors and organisms lacking clinical translatability. Here we investigate gene replacement in the Nrl(-/-) Gucy2e(-/-) mouse, an all-cone model deficient in retGC1. We show that AAV-retGC1 treatment fully restores cone function, cone-mediated visual behavior, and guanylate cyclase activity, and preserves cones in treated Nrl(-/-) Gucy2e(-/-) mice over the long-term. A novel finding was that retinal function could be restored to levels above that in Nrl(-/-) controls, contrasting results in other models of retGC1 deficiency. We attribute this to increased cyclase activity in treated Nrl(-/-) Gucy2e(-/-) mice relative to Nrl(-/-) controls. Thus, Nrl(-/-) Gucy2e(-/-) mice possess an expanded dynamic range in ERG response to gene replacement relative to other models. Lastly, we show that a candidate clinical vector, AAV5-GRK1-GUCY2D, when delivered to adult Nrl(-/-) Gucy2e(-/-) mice, restores retinal function that persists for at least 6 months. Our results provide strong support for clinical application of a gene therapy targeted to the cone-rich, central retina of LCA1 patients.
- Published
- 2015
24. Intravitreal delivery of a novel AAV vector targets ON bipolar cells and restores visual function in a mouse model of complete congenital stationary night blindness
- Author
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Seok Hong Min, Ronald G. Gregg, Miranda L. Scalabrino, Charles N. de Leeuw, Neal S. Peachey, Maureen A. McCall, Elizabeth M. Simpson, Kathryn M. Fransen, Sanford L. Boye, Shannon E. Boye, Frank M. Dyka, Qing Ruan, and Jennifer M. Noel
- Subjects
Retinal Bipolar Cells ,genetic structures ,Transgene ,Genetic Vectors ,Biology ,Gene delivery ,Transfection ,Retina ,Mice ,Night Blindness ,Myopia ,Genetics ,medicine ,Animals ,Humans ,Transgenes ,Promoter Regions, Genetic ,Molecular Biology ,Vision, Ocular ,Genetics (clinical) ,TRPM1 ,medicine.diagnostic_test ,Eye Diseases, Hereditary ,Genetic Diseases, X-Linked ,Articles ,General Medicine ,Dependovirus ,Cell biology ,Mice, Inbred C57BL ,Disease Models, Animal ,medicine.anatomical_structure ,Intravitreal Injections ,Mutation ,Proteoglycans ,sense organs ,Muller glia ,Erg ,Nyctalopin ,Electroretinography - Abstract
Adeno-associated virus (AAV) effectively targets therapeutic genes to photoreceptors, pigment epithelia, Müller glia and ganglion cells of the retina. To date, no one has shown the ability to correct, with gene replacement, an inherent defect in bipolar cells (BCs), the excitatory interneurons of the retina. Targeting BCs with gene replacement has been difficult primarily due to the relative inaccessibility of BCs to standard AAV vectors. This approach would be useful for restoration of vision in patients with complete congenital stationary night blindness (CSNB1), where signaling through the ON BCs is eliminated due to mutations in their G-protein-coupled cascade genes. For example, the majority of CSNB1 patients carry a mutation in nyctalopin (NYX), which encodes a protein essential for proper localization of the TRPM1 cation channel required for ON BC light-evoked depolarization. As a group, CSNB1 patients have a normal electroretinogram (ERG) a-wave, indicative of photoreceptor function, but lack a b-wave due to defects in ON BC signaling. Despite retinal dysfunction, the retinas of CSNB1 patients do not degenerate. The Nyx(nob) mouse model of CSNB1 faithfully mimics this phenotype. Here, we show that intravitreally injected, rationally designed AAV2(quadY-F+T-V) containing a novel 'Ple155' promoter drives either GFP or YFP_Nyx in postnatal Nyx(nob) mice. In treated Nyx(nob) retina, robust and targeted Nyx transgene expression in ON BCs partially restored the ERG b-wave and, at the cellular level, signaling in ON BCs. Our results support the potential for gene delivery to BCs and gene replacement therapy in human CSNB1.
- Published
- 2015
25. Kinetics of the Ni/Ta-Interlayer/Ge Reactions Studied by In Situ Transmission Electron Microscopy
- Author
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Jae-Wook Lee, Jee-Hwan Bae, Tae-Hoon Kim, Hyoungsub Kim, Seok-Hong Min, Keesam Shin, Je-Hyun Lee, Jung-il Song, and Cheol-Woong Yang
- Subjects
General Materials Science - Published
- 2015
26. Effect of C Content on the Microstructure and Physical Properties of Fe-36Ni Invar Alloy
- Author
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Seok Hong Min and Tae Kwon Ha
- Subjects
Materials science ,Thermodynamic equilibrium ,Precipitation (chemistry) ,Mechanical Engineering ,Metallurgy ,Condensed Matter Physics ,Microstructure ,Thermal expansion ,Carbide ,Mechanics of Materials ,Phase (matter) ,Ultimate tensile strength ,Invar alloy ,General Materials Science - Abstract
Thermodynamic equilibrium of Fe-36Ni-base Invar alloy containing C contents from 0.25 to 0.38 weight per cent during solidification has been investigated in this study. From the thermodynamic simulation using ThermoCalc®, it has been revealed that equilibrium phases which can be formed are two kinds of MC-type precipitates, i.e. (Nb, Mo, V)C and MoC, and M2C carbides. The MoC carbide was expected to be formed at relatively lower temperature below 770oC. Microstructure observation revealed the coarse precipitates in the as-cast ingots, which was Mo-rich non-equilibrium phase and could be resolved by the successive heat treatment. With increasing C contents from 0.25 to 0.38 wt.%, tensile strength of Invar alloy increased from 950 to 1100MPa after hot rolling and thermal expansion coefficient showed a trivial increase. Hot-rolled Invar alloy was successfully drawn at room temperature from 6 to 4 mm in diameter, which dramatically decreased thermal expansion coefficient.
- Published
- 2014
27. Preparation of spherical WTaMoNbV refractory high entropy alloy powder by inductively-coupled thermal plasma
- Author
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Jang-Won Kang, Tae Kwon Ha, Jong-Min Park, Sung Yong Lee, Seok-Hong Min, Won-hyuk Lee, and Hyung-Ki Park
- Subjects
Materials science ,Mechanical Engineering ,Alloy ,Irregular shape ,02 engineering and technology ,Plasma ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Brittleness ,Mechanics of Materials ,Thermal ,engineering ,General Materials Science ,Composite material ,Ingot ,0210 nano-technology ,Refractory (planetary science) - Abstract
Spherical WTaMoNbV refractory high entropy alloy powders were fabricated by milling and spheroidizing using inductively-coupled thermal plasma. The WTaMoNbV alloy is brittle at room temperature; therefore, the alloy ingot could be pulverized by jaw-crushing and ball-milling, and the fabricated powders had an irregular shape. After sieving using meshes ranging in size from 25 to 63 μm, the powders were spheroidized using inductively-coupled thermal plasma. Using this process, spherical WTaMoNbV high entropy alloy powders with d50 of 45.1 μm could be fabricated successfully.
- Published
- 2019
28. TCP Fairness Improvement Scheme using Adaptive Contention Window in Wireless Mesh Networks
- Author
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Seok Hong Min, Byung-Chul Kim, Jong Sung Lee, Hyung Suk Choi, In Sik Jang, Jae-Yong Lee, and Bong Gyu Kim
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Router ,Wireless mesh network ,business.industry ,Computer science ,Node (networking) ,Distributed computing ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Mesh networking ,Shared mesh ,Distributed coordination function ,Computer Science::Performance ,Default gateway ,Computer Science::Networking and Internet Architecture ,Switched mesh ,business ,Computer network - Abstract
Wireless Mesh Networks(WMNs) is generally composed of radio nodes in the mesh topology. WMNs consists of mesh client, mesh router and gateway connected to a wired network. Each client and router relay messages to the gateway for communication. WMNs is widely used recently in many areas can provide extended coverage based on multi-hop communication and ubiquitous communication at any time and any location. However the competition and collision between each node to transmit data is inevitable when the same channel is used for transmission. The transmission opportunities and the throughput of nodes located far from gateway decrease more if the communication channel is accessed based on competitive CSMA/CA scheme using DCF(Distributed Coordination Function) provided by IEEE 802.11 MAC. In this paper, we improve the performance of the TCP fairness and throughput of the nodes with more than 2 hops by applying various algorithms for controlling contention window values. Also, we evaluate the performance using ns-2 simulator, According to the results, proposed scheme can enhance the fairness characteristic of each node irrespective of data to the gateway.
- Published
- 2013
29. A Reservation-based HWMP Routing Protocol Design Supporting E2E Bandwidth in TICN Combat Wireless Network
- Author
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Seok Hong Min, Hyung Suk Choi, Bong Gyu Kim, Jae-Yong Lee, Jong Sung Lee, Byung-Chul Kim, and Whoi Jin Jung
- Subjects
Routing protocol ,Engineering ,business.industry ,Wireless network ,Resource Reservation Protocol ,computer.internet_protocol ,Quality of service ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Reservation ,Time division multiple access ,Bandwidth (computing) ,business ,computer ,Communication channel ,Computer network - Abstract
In tactical environment, tactical wireless networks are generally comprised of Tactical MANETs(T-MANETs) or Tactical WMNs(T-WMNs). The most important services in tactical network are voice and low rate data such as command control and situation awareness. These data should be forwarded via multi-hop in tactical wireless networks. Urgent and mission-critical data should be protected in this environment, so QoS(Quality of Service) must be guaranteed for specific type of traffic for satisfying the requirement of a user. In IEEE 802.11s, TDMA-based MAC protocol, MCCA(MCF Controlled Channel Access), has a function of resource reservation. But 802.11s protocol can not guarantee the end-to-end QoS, because it only supports reservation with neighbors. In this paper, we propose the routing protocol, R-HWMP(Reservation-based HWMP) which has the resource reservation to support the end-to-end QoS. The proposed protocol can reserve the channel slots and find optimal path in T-WMNs. We analyzed the performance of the proposed protocol and showed that end-to-end QoS is guaranteed using NS-2 simulation.
- Published
- 2013
30. Implementation of Virtualization Techniques and its Performance Evaluation for the Independent Operation of OpenFlow-based Future Internet Testbed
- Author
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Seok Hong Min, Won Taek Hong, Seung Ju Kim, Jae-Yong Lee, Byung-Chul Kim, and Jong Uk Kong
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OpenFlow ,Network architecture ,business.industry ,Computer science ,Quality of service ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Testbed ,Network virtualization ,Admission control ,Virtualization ,computer.software_genre ,The Internet ,business ,computer ,Computer network - Abstract
Recently, world-wide research activities on new network architectures and protocols are being actively progressed. Furthermore, research activities on testbed and related technologies for supporting those activities are being actively performed. In domestic study, research on the OpenFlow protocol based future Internet testbed implementation and research on its virtualization for supporting independent research experiments are being performed at the same time. The network virtualization is a technology which maximizes the testbed utilization without interfering each other for the individual research when many researchers share the testbed. In this paper, we implemented a Enhanced FlowVisor by extending basic FlowVisor by adding QoS functions which are admission control and minimum bandwidth guarantee. On the testbed, we performed a real-time video streaming experiment for verifying the performance of the Enhnaced FlowVisor on the OpenFlow protocol based future internet testbed. The result shows that the Enhanced FlowVisor can provide reliable and stable QoS to the individual researches without disturbing each other traffic on virtualized networks of the future Internet testbed.
- Published
- 2013
31. Effect Of Aging Treatment On Mechanical Properties Of Non-Flammable Az91D Mg Alloy
- Author
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Ju Hyun Won, Hyun Woo Lee, Seok Hong Min, and Tae Kwon Ha
- Abstract
Microstructure and mechanical properties of AZ91D Mg alloys for nonflammable use, containing Ca and Y, were investigated in this study. Solid solution treatment of AZ91D Mg alloy with Ca and Y was successfully conducted at 420oC and supersaturated microstructure with almost all beta phases resolved into matrix was obtained. After solid solution treatment, the alloy was annealed at temperatures of 180 and 200oC for time intervals from 1 min to 48 hrs and hardness of each condition was measured by micro-Vickers method. Peak aging conditions were deduced from the results as at the temperature of 200oC for 10 hrs. Hot rolling was also carried out at 400oC by the reduction ratio of 0.6 through 5 passes followed by recrystallization treatment. Tensile and compressive properties were measured at room temperature on the specimens of each process, i.e. as-cast, solution treatment, hot rolling, and recrystallization.
- Published
- 2016
- Full Text
- View/download PDF
32. Novel Properties of Tyrosine-mutant AAV2 Vectors in the Mouse Retina
- Author
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Seok-Hong Min, Alfred S. Lewin, Li Zhong, Antonette Bennett, Hilda Petrs-Silva, William W. Hauswirth, Giridhara R. Jayandharan, Mavis Agbandje-McKenna, Jijing Pang, Andy W. Neeley, Arun Srivastava, Astra Dinculescu, Qiuhong Li, Wen-Tao Deng, Lakshmanan Govindasamy, Baozheng Li, and Vince A. Chiodo
- Subjects
viruses ,Transgene ,Genetic Vectors ,Mutant ,Biology ,Retina ,Virus ,Mice ,Transduction (genetics) ,Drug Discovery ,medicine ,Genetics ,Animals ,Point Mutation ,Tyrosine ,Molecular Biology ,Pharmacology ,Point mutation ,Dependovirus ,Molecular biology ,Mice, Inbred C57BL ,medicine.anatomical_structure ,Capsid ,Mutation ,Mutagenesis, Site-Directed ,Molecular Medicine ,Original Article - Abstract
Vectors based on adeno-associated virus serotype 2 (AAV2) have been used extensively in many gene-delivery applications, including several successful clinical trials for one type of Leber congenital amaurosis in the retina. Many studies have focused on improving AAV2 transduction efficiency and cellular specificity by genetically engineering its capsid. We have previously shown that vectors-containing single-point mutations of capsid surface tyrosines in serotypes AAV2, AAV8, and AAV9 displayed significantly increased transduction efficiency in the retina compared with their wild-type counterparts. In the present study, we evaluated the transduction characteristics of AAV2 vectors containing combinations of multiple tyrosine to phenylalanine mutations in seven highly conserved surface-exposed capsid tyrosine residues following subretinal or intravitreal delivery in adult mice. The multiply mutated vectors exhibited different in vivo transduction properties, with some having a unique ability of transgene expression in all retinal layers. Such novel vectors may be useful in developing valuable new therapeutic strategies for the treatment of many genetic diseases.
- Published
- 2011
- Full Text
- View/download PDF
33. Functional interchangeability of rod and cone transducin α-subunits
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Jijing Pang, Jie Li, Sanford L. Boye, Astra Dinculescu, Vince A. Chiodo, Vladimir J. Kefalov, Seok-Hong Min, Jianwen Liu, Wen-Tao Deng, Bo Chang, Keisuke Sakurai, and William W. Hauswirth
- Subjects
genetic structures ,Protein subunit ,Biology ,Retinal Cone Photoreceptor Cells ,Mice ,Retinal Rod Photoreceptor Cells ,Heterotrimeric G protein ,Electroretinography ,medicine ,Animals ,Eye Proteins ,Mice, Knockout ,Multidisciplinary ,medicine.diagnostic_test ,Anatomy ,Heterotrimeric G-protein complex ,Biological Sciences ,Heterotrimeric GTP-Binding Proteins ,Mice, Mutant Strains ,Recombinant Proteins ,Protein Subunits ,Biophysics ,Evoked Potentials, Visual ,sense organs ,Transducin ,Photic Stimulation ,Visual phototransduction - Abstract
Rod and cone photoreceptors use similar but distinct sets of phototransduction proteins to achieve different functional properties, suitable for their role as dim and bright light receptors, respectively. For example, rod and cone visual pigments couple to distinct variants of the heterotrimeric G protein transducin. However, the role of the structural differences between rod and cone transducin α subunits (Tα) in determining the functional differences between rods and cones is unknown. To address this question, we studied the translocation and signaling properties of rod Tα expressed in cones and cone Tα expressed in rods in three mouse strains: rod Tα knockout, cone Tα GNAT2 cpfl3 mutant, and rod and cone Tα double mutant rd17 mouse. Surprisingly, although the rod/cone Tα are only 79% identical, exogenously expressed rod or cone Tα localized and translocated identically to endogenous Tα in each photoreceptor type. Moreover, exogenously expressed rod or cone Tα rescued electroretinogram responses (ERGs) in mice lacking functional cone or rod Tα, respectively. Ex vivo transretinal ERG and single-cell recordings from rd17 retinas treated with rod or cone Tα showed comparable rod sensitivity and response kinetics. These results demonstrate that cone Tα forms a functional heterotrimeric G protein complex in rods and that rod and cone Tα couple equally well to the rod phototransduction cascade. Thus, rod and cone transducin α-subunits are functionally interchangeable and their signaling properties do not contribute to the intrinsic light sensitivity differences between rods and cones. Additionally, the technology used here could be adapted for any such homologue swap desired.
- Published
- 2009
34. High-efficiency Transduction of the Mouse Retina by Tyrosine-mutant AAV Serotype Vectors
- Author
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Li Zhong, Arun Srivastava, Jijing Pang, Sergei Zolotukhin, William W. Hauswirth, Hilda Petrs-Silva, Astra Dinculescu, Vince A. Chiodo, Qiuhong Li, Seok-Hong Min, and Alfred S. Lewin
- Subjects
viruses ,Transgene ,Genetic Vectors ,Mutant ,Biology ,Gene delivery ,Retina ,Injections ,Mice ,03 medical and health sciences ,Transduction (genetics) ,0302 clinical medicine ,Drug Discovery ,Genetics ,Animals ,Transgenes ,Tyrosine ,Molecular Biology ,030304 developmental biology ,Ganglion Cysts ,Pharmacology ,0303 health sciences ,Point mutation ,Original Articles ,Dependovirus ,Virology ,3. Good health ,Mice, Inbred C57BL ,Capsid ,Mutation ,Molecular Medicine ,Phosphorylation ,030217 neurology & neurosurgery - Abstract
Vectors derived from adeno-associated viruses (AAVs) have become important gene delivery tools for the treatment of many inherited ocular diseases in well-characterized animal models. Previous studies have determined that the viral capsid plays an essential role in the cellular tropism and efficiency of transgene expression. Recently, it was shown that phosphorylation of surface-exposed tyrosine residues from AAV2 capsid targets the viral particles for ubiquitination and proteasome- mediated degradation, and mutations of these tyrosine residues lead to highly efficient vector transduction in vitro and in vivo. Because the tyrosine residues are highly conserved in other AAV serotypes, in this study we evaluated the intraocular transduction characteristics of vectors containing point mutations in surface- exposed capsid tyrosine residues in AAV serotypes 2, 8, and 9. Several of these novel AAV mutants were found to display a strong and widespread transgene expression in many retinal cells after subretinal or intravitreal delivery compared with their wild-type counterparts. For the first time, we show efficient transduction of the ganglion cell layer by AAV serotype 8 or 9 mutant vectors, thus providing additional tools besides AAV2 for targeting these cells. These enhanced AAV vectors have a great potential for future therapeutic applications for retinal degenerations and ocular neovascular diseases.
- Published
- 2009
35. In2O3 Thin Films Prepared on TiAlN Substrates Using a Triethylindium and Oxygen Mixture
- Author
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Wan In Lee, Seung Yong Choi, Jae-Ho Choi, Won Seung Cho, Sun Keun Hwang, Hyoun Woo Kim, Sang Eon Park, Seong Gyoon Kim, Dong Ik Kim, Tae Gyung Ko, Jung Hoon Joo, Byung Hak Choe, and Seok Hong Min
- Subjects
Photoluminescence ,Materials science ,Metallurgy ,Oxide ,chemistry.chemical_element ,Substrate (electronics) ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Amorphous solid ,chemistry.chemical_compound ,Carbon film ,chemistry ,Chemical engineering ,General Materials Science ,Crystallite ,Thin film ,Indium - Abstract
This paper reports the fabrication of indium oxide (In2O3) films using a triethylindium and oxygen mixture. The deposition has been carried out on TiAlN substrates (200-350°C). We have established the correlation between the substrate temperature and the structural properties. The films deposited at 300-350°C were polycrystalline, whereas those deposited at 200°C was close to amorphous. XRD analysis and SEM images indicated that the films grown at 350°C had grained structures with the (222) preferred orientation. The room-temperature photoluminescence spectra of the In2O3 films exhibited a visible light emission.
- Published
- 2007
36. Catalytic Behavior of Nickel Particles Embedded in Three-dimensional Mesoporous SBA15
- Author
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Byoung-Il An, Daniel Kim, Sung-Han Lee, Seok-Hong Min, Jin-Kwon Lee, and Jin-Seung Jung
- Subjects
Materials science ,Catalyst support ,Inorganic chemistry ,Oxide ,Sintering ,chemistry.chemical_element ,General Chemistry ,Catalysis ,Nickel ,chemistry.chemical_compound ,chemistry ,Mesoporous material ,Dispersion (chemistry) ,Syngas - Abstract
The CO2 reforming of CH4 has received increasing attention from both an environmental and an industrial perspective because the reaction can convert greenhouse gases into synthesis gas with a low H2/CO ratio. It has been known that nickel catalyst is highly active for the CO2 reforming of CH4, but it is easily deactivated due to coke formation and metal sintering during the reaction. To develop nickel catalyst resistant to the formation of coke, various materials such as metal oxides, mixed metal oxides, and zeolite have been examined as supports until now. Metal oxide supports are mostly used as fine powder to give large surface area. However, fine powder may be a disadvantage of its application as support because fine particles trend to agglomerate into large particles at high temperatures. In recent, several investigators have shown that mesoporous MCM41 or SBA15 compounds can be applied as catalyst support with high loading and dispersion without destroying the support pore hexagonal structure. SBA15 compounds are more favorable to the application as catalyst support because they have mesopores with sizes of 46-300 A and high surface area of ~800 m/g. Moreover, the recent discovery of ordered large-pore mesoporous SBA15 compound with three dimensional mesoporous networks has extended the applications of mesoporous SBA compound in catalysis and separation because it has the advantage in the diffusion and transport of large molecules compared to one-dimensional mesopore structures. This paper reports the application of mesoporous SBA15 in high temperature catalysis. The SBA15 compound with three-dimensional mesoporous networks was prepared and nickel particles were embedded within the SBA15(3D). The Ni/SBA15(3D) was examined as catalyst for the CO2 reforming of CH4 and its catalytic results were compared with those of Ni/SiO2 and Ni/γ-Al2O3 catalysts.
- Published
- 2007
37. Capsid Mutated Adeno-Associated Virus Delivered to the Anterior Chamber Results in Efficient Transduction of Trabecular Meshwork in Mouse and Rat
- Author
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Herbert A. Reitsamer, Zhonghong Zhang, Barbara Bogner, William W. Hauswirth, Jim Peterson, Sanford L. Boye, Shannon E. Boye, Seok Hong Min, and Qing Ruan
- Subjects
Pathology ,medicine.medical_specialty ,Corneal endothelium ,Anterior Chamber ,Genetic Vectors ,Green Fluorescent Proteins ,Glaucoma ,lcsh:Medicine ,Biology ,medicine.disease_cause ,Injections ,Rats, Sprague-Dawley ,Transduction (genetics) ,Capsid ,Trabecular Meshwork ,Transduction, Genetic ,Cornea ,medicine ,Animals ,lcsh:Science ,Adeno-associated virus ,Retina ,Multidisciplinary ,lcsh:R ,Dependovirus ,medicine.disease ,Epithelium ,Cell biology ,Mice, Inbred C57BL ,medicine.anatomical_structure ,Mutation ,lcsh:Q ,Trabecular meshwork ,sense organs ,Research Article - Abstract
Background Adeno associated virus (AAV) is well known for its ability to deliver transgenes to retina and to mediate improvements in animal models and patients with inherited retinal disease. Although the field is less advanced, there is growing interest in AAV’s ability to target cells of the anterior segment. The purpose of our study was to fully articulate a reliable and reproducible method for injecting the anterior chamber (AC) of mice and rats and to investigate the transduction profiles of AAV2- and AAV8-based capsid mutants containing self-complementary (sc) genomes in the anterior segment of the eye. Methodology/Principle Findings AC injections were performed in C57BL/6 mice and Sprague Dawley rats. The cornea was punctured anterior of the iridocorneal angle. To seal the puncture site and to prevent reflux an air bubble was created in the AC. scAAVs expressing GFP were injected and transduction was evaluated by immunohistochemistry. Both parent serotype and capsid modifications affected expression. scAAV2- based vectors mediated efficient GFP-signal in the corneal endothelium, ciliary non-pigmented epithelium (NPE), iris and chamber angle including trabecular meshwork, with scAAV2(Y444F) and scAAV2(triple) being the most efficient. Conclusions/Significance This is the first study to semi quantitatively evaluate transduction of anterior segment tissues following injection of capsid-mutated AAV vectors. scAAV2- based vectors transduced corneal endothelium, ciliary NPE, iris and trabecular meshwork more effectively than scAAV8-based vectors. Mutagenesis of surface-exposed tyrosine residues greatly enhanced transduction efficiency of scAAV2 in these tissues. The number of Y-F mutations was not directly proportional to transduction efficiency, however, suggesting that proteosomal avoidance alone may not be sufficient. These results are applicable to the development of targeted, gene-based strategies to investigate pathological processes of the anterior segment and may be applied toward the development of gene-based therapies for glaucoma and acquired or inherited corneal anomalies.
- Published
- 2015
38. Interface and microstructure evolutions in synthetic ferrimagnet-based spin valves upon exposure to postdeposition annealing
- Author
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Young Keun Kim, Park, Gun-Hyung, Seok-Hong Min, Seong-Rae Lee, Jeong Yun Won, and Se Ahn Song
- Subjects
Iron compounds -- Magnetic properties ,Iron compounds -- Electric properties ,Cobalt -- Magnetic properties ,Cobalt -- Electric properties ,Manganese -- Magnetic properties ,Manganese -- Electric properties ,Iridium -- Magnetic properties ,Iridium -- Electric properties ,Magnetoresistance -- Research ,Physics - Abstract
The difference in magnetoresistance (MR) property degradation behavior of bottom (B)- and top (T)- synthetic ferrimagnet-based spin-valve (SV) on annealing is examined. The deposition sequence and the grain boundary area were the two major factors for the differences in interfacial energies of IrMn/CoFe and the B-SV featuring less grain boundaries and nonabrupt IrMn/CoFe interface showed better thermal stability.
- Published
- 2003
39. Comparison of the agglomeration behavior of Au and Cu films sputter deposited on silicon dioxide
- Author
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Jang-Yeon Kwon, Tae-Sik Yoon, Ki-Bum Kim, and Seok-Hong Min
- Subjects
Copper -- Properties ,Magnetrons -- Research ,Gold -- Properties ,Physics - Abstract
The agglomeration behavior of Cu and Au films each with a thickness of 5 and 50 nm, deposited on thermally grown SiO2 by dc magnetron sputtering, are investigated with scanning electron microscopy. Kinetics of agglomeration of the Au films are described with an Avrami-type equation.
- Published
- 2003
40. Gene Therapy Restores Vision-Dependent Behavior as Well as Retinal Structure and Function in a Mouse Model of RPE65 Leber Congenital Amaurosis
- Author
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Thomas C. Foster, Qiuhong Li, Jijing Pang, Steven Nusinowitz, Shalesh Kaushal, Huashi Li, William W. Hauswirth, Vince A. Chiodo, Jie Li, Bo Chang, Ritu Malhotra, Asha Rani, Jacqueline T. Teusner, J. Hugh McDowell, Seok-Hong Min, Thomas J. Doyle, Syed Mohammed Noorwez, and Ashok Kumar
- Subjects
cis-trans-Isomerases ,Rhodopsin ,medicine.medical_specialty ,genetic structures ,Genetic enhancement ,Genetic Vectors ,Morris water navigation task ,Optic Atrophy, Hereditary, Leber ,Retina ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Internal medicine ,Drug Discovery ,medicine ,Genetics ,Animals ,Eye Proteins ,Molecular Biology ,Vision, Ocular ,030304 developmental biology ,Pharmacology ,0303 health sciences ,Behavior, Animal ,biology ,Esters ,Retinal ,Genetic Therapy ,Anatomy ,Dependovirus ,eye diseases ,Mice, Inbred C57BL ,Disease Models, Animal ,Endocrinology ,RPE65 ,chemistry ,Cis-trans-Isomerases ,030221 ophthalmology & optometry ,biology.protein ,Molecular Medicine ,sense organs ,Carrier Proteins ,Erg ,Visual phototransduction - Abstract
Retinal pigment epithelium-specific protein 65 kDa (RPE65) is a protein responsible for isomerization of all-trans-retinaldehyde to its photoactive 11-cis-retinaldehyde and is essential for the visual cycle. RPE65 mutations can cause severe, early onset retinal diseases such as Leber congenital amaurosis (LCA). A naturally occurring rodent model of LCA with a recessive nonsense Rpe65 mutation, the rd12 mouse, displays a profoundly diminished rod electroretinogram (ERG), an absence of 11-cis-retinaldehyde and rhodopsin, an overaccumulation of retinyl esters in retinal pigmented epithelial (RPE) cells, and photoreceptor degeneration. rd12 mice were injected subretinally at postnatal day 14 with rAAV5-CBA-hRPE65 vector. RPE65 expression was found over large areas of RPE soon after treatment. This led to improved rhodopsin levels with ERG signals restored to near normal. Retinyl ester levels were maintained at near normal, and fundus and retinal morphology remained normal. All parameters of restored retinal health remained stable for at least 7 months. The Morris water maze behavioral test was modified to test rod function under very dim light; rd12 mice treated in one eye performed similar to normally sighted C57BL/6J mice, while untreated rd12 mice performed very poorly, demonstrating that gene therapy can restore normal vision-dependent behavior in a congenitally blind animal.
- Published
- 2006
- Full Text
- View/download PDF
41. Single and Multiple-Step Dip-Coating of Colloidal Maghemite (?-Fe2O3) Nanoparticles onto Si, Si3N4, and SiO2 Substrates
- Author
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Jihun Oh, Seok-Hong Min, Taeghwan Hyeon, Sang-Hyun Park, Ki-Bum Kim, Viena Kim, Byung Gil Jung, Tae-Sik Yoon, and Jongnam Park
- Subjects
Materials science ,Silicon dioxide ,Substrate (chemistry) ,Maghemite ,Nanoparticle ,Nanotechnology ,engineering.material ,Condensed Matter Physics ,Dip-coating ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Colloid ,chemistry.chemical_compound ,Adsorption ,Chemical engineering ,chemistry ,Electrochemistry ,engineering ,Particle - Abstract
The adsorption behavior of colloidal maghemite (γ-Fe 2 O 3 ) nanoparticles, passivated by oleic acid and dispersed in octane solution, onto three different substrates (Si, Si 3 N 4 . and SiO 2 ) is investigated. The average nanoparticle size is 10 nm, with a size variation (σ) less than 5 %. The adsorption of particles is strongly dependent on both the type of substrate and the particle concentration in solution. By a single-dipping process, we have obtained a maximum coverage of 0.45 on a Si substrate, but much less on other substrates (0.19 on Si 3 N 4 and 0.14 on SiO 2 ). The particle coverage was drastically increased by the multiple-adsorption process, where the process of dipping and drying was repeated multiple times. With this process, we can obtain a maximum particle coverage of about 0.76 on a Si substrate and 0.61 on a thermally grown SiO 2 substrate.
- Published
- 2004
42. 620. Use of Transgenic Mice to Quantify Transduction Efficiency and Specificity of Novel AAV Vectors in Retina
- Author
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Jim Peterson, Shannon E. Boye, Miranda L. Scalabrino, Shreyasi Choudhury, Sanford L. Boye, Seok-Hong Min, and K. Tyler McCullough
- Subjects
Pharmacology ,Genetically modified mouse ,viruses ,Transgene ,Gene delivery ,Biology ,Molecular biology ,Green fluorescent protein ,Transduction (genetics) ,In vivo ,Drug Discovery ,Genetics ,Molecular Medicine ,mCherry ,Molecular Biology ,Nyctalopin - Abstract
Modifications to surface-exposed residues of recombinant Adeno-associated virus (AAV), incorporation of novel regulatory elements into the vector cassette, alternative injection routes, and combinations thereof are being explored as strategies to enhance gene delivery to retina. We previously showed that intravitreal injection of a novel AAV capsid was capable of transducing all neuronal layers of the retina, including photoreceptors (PRs). We also demonstrated that this capsid, when combined with a novel promoter (“Ple155”) was capable of driving therapeutic nyctalopin (Nyx) expression exclusively in ON bipolar cells (ON BCs) and partially restoring retinal function to a mouse model of complete Congenital Stationary Night Blindness (CSNB1) following early (postnatal day 2) treatment. In order to achieve more efficient transduction of PRs and ON BCs, further modifications will be required. Methods with which to quantify relative transduction efficiencies of novel variants in vivo are warranted. The purpose of this study was to develop robust methods for quantifying transduction efficiency or transgene expression in PRs and ON BCs, respectively by rAAVs in vivo. Specifically, we sought to develop methods that don't require time consuming subjective analysis. To do so, we employed two transgenic mouse models: Nrl-GFP and Grm6-GFP mice which have constitutively fluorescent rod PRs and ON BCs, respectively. Adult mice (~postnatal day 30) were injected either subretinally (SR) or intravitreally (Ivt) with rAAVs containing the mCherry transgene. Fundoscopy was performed at 1 month post injection. Immediately thereafter, retinas were dissociated and evaluated by FACS for GFP and mCherry fluorescence, the overlap of which indicated targeted transduction of either ON BCs or rods, depending on mouse model. A subset of retinas was also evaluated with immunohistochemistry. In agreement with previous experiments, Ivt and SR delivered AAV2(quadY-F+T-V) and AAV2(4pMut) transduced a relatively large percentage of retina, including PRs. However, ON BC transduction was minimal, with ~6% transduced by Ivt AAV2(quadY-F+T-V)-CBA-mCherry delivery. AAV2 weakly transduced retina via both delivery routes. AAV2(4pMut)ΔHS, which lacks canonical HSPG binding residues, failed to transduce retina by Ivt injection, but efficiently transduced rods (75%) following SR delivery, indicative of significant ‘lateral spread’ from the injection bleb. Incorporation of the ON BC-specific promoter (“Ple155”) used in the CSNB1 gene replacement study abolished non-ON BC retinal expression. Experiments are ongoing to assess the extent to which rAAVs containing Ple155 can increase expression efficiency in ON BCs relative to CBA, and to determine whether the addition of other transcriptional and post transcriptional regulatory elements can further increase rAAV-mediated expression in these cells. In summary, we have developed a method for quantifying transduction of PRs and ON BCs by novel rAAVs in vivo. As the AAV vector toolkit expands, such a method will be highly useful for scoring relative performance of novel vectors. We also conclude that while the ubiquitous CBA promoter effectively drives transgene expression in PRs, it drives relatively poor transgene expression in ON BCs and caution that CBA should not be considered as a default universal promoter for retinal expression.
- Published
- 2016
43. Molecular Markers of Endometrial Epithelial Cell Mitogenesis Mediated by the Sp/Krüppel-Like Factor BTEB1
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Xue-Lian Zhang, Ge Zhao, Frank J. Michel, Frank A. Simmen, Rosalia C. M. Simmen, and Seok Hong Min
- Subjects
Chromosomal Proteins, Non-Histone ,Cellular homeostasis ,Endometrium ,Transactivation ,Genes, Reporter ,Transcription (biology) ,Tumor Cells, Cultured ,Insulin-Like Growth Factor I ,Promoter Regions, Genetic ,Oncogene Proteins ,Microfilament Proteins ,General Medicine ,Cell cycle ,Neoplasm Proteins ,DNA-Binding Proteins ,Gene Expression Regulation, Neoplastic ,Multigene Family ,Female ,Mitogen-Activated Protein Kinases ,Cell Division ,Signal Transduction ,Cyclin-Dependent Kinase Inhibitor p21 ,Transcriptional Activation ,DNA, Complementary ,Recombinant Fusion Proteins ,Kruppel-Like Transcription Factors ,Repressor ,Biology ,Cyclins ,Proto-Oncogene Proteins ,Genetics ,Animals ,Humans ,Molecular Biology ,Gene ,Gene Expression Profiling ,Carcinoma ,JNK Mitogen-Activated Protein Kinases ,Receptor Protein-Tyrosine Kinases ,RNA ,Epithelial Cells ,Promoter ,Cell Biology ,Axl Receptor Tyrosine Kinase ,Molecular biology ,Endometrial Neoplasms ,Rats ,Insulin-Like Growth Factor Binding Protein 2 ,Trans-Activators ,Biomarkers ,Transcription Factors - Abstract
Basic transcription element binding (BTEB1) protein is one of at least 20 Sp/KLF family members that function as transcriptional activators or repressors by binding to GC/GT-rich sequences within target genes to influence cellular homeostasis in mammals. Previously, we demonstrated that increased expression of BTEB1 in a human endometrial epithelial cell line Hec-1-A resulted in serum dependent-enhanced proliferation, which was accompanied by heightened expression of cell cycle- and growth-associated genes. In the present study, we examined the mechanism underlying the altered proliferative potential associated with BTEB1 by the identification of additional BTEB1 downstream gene targets and by the demonstration of BTEB1 transactivation of promoters for a number of growth-associated genes. Using mRNA differential display in the analysis of RNA populations from Hec-1-A sublines with high (4S, 9S) and low (2As, 3As) BTEB1 cellular content, we identified 10 distinct differentially expressed transcripts, nine of which had higher levels in S than in As sublines. The expression levels of two of these cDNAs, Axl receptor tyrosine kinase and mitosin, whose encoded products are implicated in cellular proliferation, were modestly induced by serum, albeit in a BTEB1-independent manner. Moreover, insulin-like growth factor-I, a mitogen present in serum, had no significant effect on their expression in either subline. In transient reporter assays, the basal activities of the Axl gene promoter and those for two other growth-regulatory genes, namely p21(WAF1) and IGFBP-2, were increased by serum and were significantly higher in 4S than in 2As lines. However, while BTEB1 and its ubiquitous family member Sp1 increased basal p21(WAF1) and IGFBP-2 transcription when added as expression constructs in the parental Hec-1-A cell line, only Sp1 activated Axl transcription, despite the presence in all three gene promoters of GC-enriched regions that presumably can bind BTEB1 and Sp1 with similar affinities. To elucidate intracellular signaling pathways that might involve BTEB1, inhibitors of specific kinase-dependent transducers were used in transient transfection assays involving the IGFBP-2 gene promoter in 4S and 2As sublines. While inhibitors of the MAPK, PI-3K, and PKA pathways elicited similar effects on the IGFBP-2 gene promoter activity, irrespective of cellular BTEB1 content, that for JNK had a more pronounced effect on Hec-1-A sublines exhibiting higher BTEB1 expression levels. Taken together, the results suggest that BTEB1 mediates the expression of growth-associated genes through direct and indirect transactivation mechanisms, one of which may involve the participation of a JNK family member.
- Published
- 2002
44. Microstructure And Aging Behavior Of Nonflammable Az91D Mg Alloy
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Seok Hong Min and Tae Kwon Ha
- Subjects
AZ91D ,nonflammable alloy ,phase equilibrium ,Mg alloy ,peak aging - Abstract
Phase equilibria of AZ91D Mg alloys for nonflammable use, containing Ca and Y, were carried out by using FactSage® and FTLite database, which revealed that solid solution treatment could be performed at temperatures from 400 to 450oC. Solid solution treatment of AZ91D Mg alloy without Ca and Y was successfully conducted at 420oC and supersaturated microstructure with all beta phase resolved into matrix was obtained. In the case of AZ91D Mg alloy with some Ca and Y; however, a little amount of intermetallic particles were observed after solid solution treatment. After solid solution treatment, each alloy was annealed at temperatures of 180 and 200oC for time intervals from 1 min to 48 hrs and hardness of each condition was measured by micro-Vickers method. Peak aging conditions were deduced as at the temperature of 200oC for 10 hrs., {"references":["B. L. Mordike and T. Ebert, Mater. Sci. Eng. A, vol. 302, p. 37, 2001.","X. Cui, H. Liu, J. Meng, and D. Zhang, Trans. Nonferr. Met. Soc. Of\nChina, vol. 20, p. 435, 2010.","F. Guo, P, Li, X. Gao, and J. Xu, J. Rare Earth, vol. 28, p. 948, 2010.","M. O. Pekguleryuz, and E. Baril, Mater. Trans., vol. 42, p. 1258, 2001.","B. R. Powell, A. A. Lou, V. Rezhets, J. J. Bommarito, and B. L. Tiwari,\nSAE Tech. Paper 2001-01-0422, Soc. Automotive Eng., p. 406, 2001.","G. Wu, F. Yu, H. Gao, C. Zhai, and Y. P. Zhu, Mater. Sci. Eng. A, vol.\n408, p. 255, 2005.","X. Q. Zheng, Q. D. Wang, Y. Z. Lu, W. J. Ding, C. Lu, Y. P. Zhu, C. Q.\nZhai, and X. P. Xu, Scripta Mater., vol. 43, p. 403, 2003.","B. S. You, W. W. Park, and L. S. Chung, Scripta Mater., vol. 42, p. 403,\n2002.","T. S. shih, J.-H. Wang, and K.-Z. Chong, Mater. Chem. & Phys., vol. 85,\np. 302, 2004."]}
- Published
- 2014
- Full Text
- View/download PDF
45. Tensile Behavior Of Spheroidizing Heat Treated High Carbon Steel
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Seok Hong Min and Tae Kwon Ha
- Subjects
tensile behavior ,pearlite ,SK85 ,cementite ,shperoidization ,High carbon steel - Abstract
Spheroidization heat treatment was conducted on the SK85 high carbon steel sheets with various initial microstructures obtained after cold rolling by various reduction ratios at a couple of annealing temperatures. On the high carbon steel sheet with fine pearlite microstructure, obtained by soaking at 800oC for 2hr in a box furnace and then annealing at 570oC for 5min in a salt bath furnace followed by water quenching, cold rolling was conducted by reduction ratios of 20, 30, and 40%. Heat treatment for spheroidization was carried out at 600 and 720oC for the various time intervals from 0.1 to 32 hrs. Area fraction of spheroidized cementite was measured with an image analyzer as a function of cold reduction ratios and duration times. Tensile tests were carried out at room temperature on the spheoidized high carbon steel., {"references":["Y.L. Tian and R.W. Kraft, Met. Trans. A, Vol. 18A, p. 1403, 1978.","E. Werner, Acta Metall., Vol. 37, p. 2047, 1989.","S.A. Hackney, Scripta Metall., Vol. 25, p. 799, 1991.","N. V. Luzginova, L. Zhao, and J. Sietsma, Metall. Mater. Trans. A, Vol. \n39A, p. 513,2008.","C. Chou, J. Mat. Sci., Vol. 21, p. 3339, 1989.","K. Aihara and S. Kanbara, The Sumitomo Search, Vol. 42, p. 1, 1990.","S. E. Nam and D. Y. Lee, J. Mat. Sci., Vol. 22, p. 2319, 1987."]}
- Published
- 2014
- Full Text
- View/download PDF
46. Gene Therapy in the Rd6 Mouse Model of Retinal Degeneration
- Author
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Qiuhong Li, William W. Hauswirth, Wen-Tao Deng, Seok-Hong Min, and Astra Dinculescu
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Retinal degeneration ,Gene therapy of the human retina ,Retinal pigment epithelium ,medicine.diagnostic_test ,Retinal ,Apical membrane ,Biology ,medicine.disease_cause ,medicine.disease ,Photoreceptor cell ,Cell biology ,chemistry.chemical_compound ,medicine.anatomical_structure ,chemistry ,medicine ,sense organs ,Adeno-associated virus ,Electroretinography - Abstract
The rd6 mouse is a natural model of an RPE-based (retinal pigment epithelium) autosomal recessive retinitis pigmentosa (RP) caused by mutations in the Mfrp (membrane-type frizzled related protein) gene. Previously, we showed that subretinal delivery of the wild-type mouse Mfrp mediated by a tyrosine-capsid mutant scAAV8 (Y733F) vector prevented photoreceptor cell death, and rescued retinal function as assessed by electroretinography. In this study, we describe the effect of gene therapy on the retinal structure and function in rd6 mice using a quadruple (Y272, 444, 500, 730F) tyrosine-capsid mutant scAAV2 viral vector delivered subretinally at postnatal day 14 (P14). We show that therapy is effective at slowing the photoreceptor degeneration, and in preventing the characteristic accumulation of abnormal phagocytic cells in the subretinal space. MFRP expression as driven by the ubiquitous chicken β-actin (smCBA) promoter in treated rd6 mice was found predominantly in the RPE apical membrane and the entire length of its microvilli, as well as in the photoreceptor inner segments, suggesting a potential interaction with actin filaments. In spite of preserving retinal morphology, the effects of gene therapy on retinal function were minimal, suggesting that the scAAV8 (Y733F) vector may be more efficient for the treatment of RP caused by Mfrp mutations.
- Published
- 2014
47. High spatial density nanocrystal formation using thin layer of amorphous Si0.7Ge0.3 deposited on SiO2
- Author
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Dae Hwan Kim, Jang Yeon Kwon, Dong Hyuk Chae, Seok Hong Min, Jong Duk Lee, Ki-Bum Kim, Dong Hoon Lee, Hwack Joo Lee, Byung-Gook Park, and Tae-Sik Yoon
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Materials science ,business.industry ,Alloy ,General Physics and Astronomy ,Coulomb blockade ,Nanotechnology ,Chemical vapor deposition ,engineering.material ,Amorphous solid ,Threshold voltage ,Nanocrystal ,engineering ,Optoelectronics ,Partial oxidation ,business ,Layer (electronics) - Abstract
The process to make nanocrystals with an average size 1012/cm2 was proposed using agglomeration and partial oxidation of thin amorphous Si0.7Ge0.3 layer deposited in between the SiO2 layers by low pressure chemical vapor deposition. The reason to use an amorphous layer is to make it possible to deposit a thin continuous layer with a thickness of less than 5 nm. Si0.7Ge0.3 alloy layer was used to control the spatial density of the nanocrystals by using selective oxidation of Si in Si0.7Ge0.3 alloy layer. The single electron memory, similar to a flash type memory device was fabricated using these Si0.7Ge0.3 nanocrystals. The Coulomb blockade effect could be clearly observed at room temperature with a threshold voltage shift of about 2.4 V, which demonstrated the formation of nanocrystals with a high spatial density.
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- 2000
48. Diffusion Barrier Properties of Metallorganic Chemical Vapor Deposited Tantalum Nitride Films Against Cu Metallization
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Sam‐Dong Kimd, Sung-Lae Cho, Seok-Hong Min, Ki-Bum Kim, and Hyun-Kook Shin
- Subjects
Auger electron spectroscopy ,Diffusion barrier ,Renewable Energy, Sustainability and the Environment ,Annealing (metallurgy) ,Tantalum ,Analytical chemistry ,chemistry.chemical_element ,Mineralogy ,Chemical vapor deposition ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Volumetric flow rate ,chemistry.chemical_compound ,chemistry ,Tantalum nitride ,Electrical resistivity and conductivity ,Materials Chemistry ,Electrochemistry - Abstract
TaN x films were deposited by chemical vapor deposition using a pentakis(diethylamido)tantalum (PDEAT) source with and without NH 3 at temperatures ranging from 300 to 375°C. It was observed that both the resistivity and carbon content of the film drastically decreased upon the addition of NH 3 . For example, the resistivity decreased from 60,000 to 12,000 μΩ cm, and the apparent carbon content obtained by Auger electron spectroscopy decreased from 30 to 1 atom % by the addition of 25 sccm NH 3 . The grain size initially increased with the addition of 5 sccm NH 3 in the source gas, but then decreased as the NH 3 flow rate was increased to more than 10 sccm. As-deposited TaN x film has a face-centered cubic structure irrespective of the amount of NH 3 . The density of the film increased from about 5.1 to 7.2 g cm -3 (bulk density of TaN: 16.3 g cm -3 ). Barrier failure results identified by the etch-pit test showed that a 50 nm thickness of the TaN x barrier deposited by a single source of PDEAT survived up to 500°C after 1 h annealing. The TaN x film deposited with 25 sccm NH 3 survived up to 550°C after 1 h annealing. However, the step coverage of the films deposited with NH 3 is drastically decreased, from more than 80% (NH 3 = 0 sccm) to less than 10% (NH 3 = 25 sccm). Thus, while the addition of NH 3 significantly improves both the resistivity and carbon content in the film, it deteriorates the step coverage of the film.
- Published
- 1999
49. A Comparative Study of Film Properties of Chemical Vapor Deposited TiN Films as Diffusion Barriers for Cu Metallization
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Seok-Hong Min, Ki-Bum Kim, Deuk‐Seok Chung, Soo-Hyun Kim, and Ki Chul Park
- Subjects
Materials science ,Diffusion barrier ,Renewable Energy, Sustainability and the Environment ,Metallurgy ,Thermal decomposition ,Analytical chemistry ,chemistry.chemical_element ,Condensed Matter Physics ,Microstructure ,Grain size ,Nanocrystalline material ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Materials Chemistry ,Electrochemistry ,Tin ,Sheet resistance ,Titanium - Abstract
The diffusion barrier properties of three different kinds of chemical vapor deposited (CVD) TiN films were compared against Cu. TiN(A) film (21 nm) was deposited by the thermal decomposition of a single source of tetrakis(dimethylamido)titanium at 400°C. TiN(B) film (19 nm) was prepared by in situ plasma treatment after every 8 nm growth of TiN(A) film. Finally, TiN(C) film (28 nm) was deposited by the reaction of with at 630°C. The densities of TiN(A), TiN(B), and TiN(C) films were 2.55, 4.04, and , respectively. Both TiN(A) and TiN(B) films showed nanocrystalline microstructure with equiaxed grains, the sizes of which were about 4 and 7 nm, respectively. TiN(C) film showed a columnar grain structure with an average grain size of about 14 nm. Sheet resistance measurements, X‐ray diffractometry analyses, and etch‐pit test results consistently demonstrated that the barrier performances of TiN(A) and TiN(B) were superior to those of TiN(C). The diffusion barrier properties of CVD TiN films were discussed in view of the density and microstructure of the film. © 1999 The Electrochemical Society. All rights reserved.
- Published
- 1999
50. Fabrication of gated diamond field emitter array using a selective diamond growth process
- Author
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Seungbum Ha, Ki-Bum Kim, Dae-Hwan Kang, Joohei Lee, Seok-Hong Min, and Il Han Kim
- Subjects
Fabrication ,Materials science ,Mordançage ,business.industry ,Field emitter array ,Metals and Alloys ,Nucleation ,Diamond ,Surfaces and Interfaces ,engineering.material ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Field electron emission ,Optics ,Triode ,law ,Materials Chemistry ,engineering ,Optoelectronics ,business ,Common emitter - Abstract
A novel processing sequence for the formation of gated diamond field emitter array (triode system) is proposed and the feasibility is tested by investigating the field emission property. The processing scheme is based on the selective deposition of diamond by using the well established nucleation enhanced process on substrate, so callled bias enhanced nucleation (BEN). The structure of substrate was patterned [SiO 2 /Mo(gate)SiO 2 (insulator)Si(100). Our preliminary results show that the diamond field emitter is turned on at around 87 V/μm with the current level of about several μA.
- Published
- 1999
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