• Journal of the Korean institute of surface engineering
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• v.55 no.4
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• pp.215-221
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• 2022

In the present work, copper oxide thin films were formed by heat-treatment method with different temperatures and atmosphere, e.g., at 200 ~ 400 ℃; in air and Ar atmosphere. The morphological, electrical and optical properties of the thermally fabricated Cu oxide films were analyzed by SEM, XRD, and UV-VIS spectrometer. Thereafter, photoelectrochemical properties of the thermal copper oxide films were analyzed under solar light (AM 1.5, 100 mW/cm²). Conclusively, the highest photocurrent was obtained with Cu₂O formed under the optimum annealing condition at 300 ℃ in air atmosphere. In addition, EIS results of Cu oxide formed in air atmosphere showed relatively low resistance and long electron life-time compared with Cu Oxide fabricated in Ar atmosphere at the same temperature. This is because heat-treatment in Ar atmosphere could not form Cu₂O due to lack of oxygen, and thermally formed CuO at high temperature suppressed stability and conductivity of the Cu oxide.

• Journal of Adhesion and Interface
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• v.19 no.3
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• pp.101-105
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• 2018

With the rapidly growing of the population and industrization of cities, the clean and affordable water resources have gained immense interest because of remaining about 780 million people still lack access to it. However, present wastewater treatment systems have been faced with various issues, such as low processing efficiency, high operational costs and the requirement of a large area for manufacturing. It is therefore urgently required to develop an inexpensive and efficient wastewater treatment system. As the one of these efforts, we suggested and successfully demonstrated the wastewater treatment system using and electrochemical method via a dimensionally stable anode (DSA) based on rutile type $RuO_2$. Our system achieved biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) removal efficiently at the respective rates of 52.0%, 77.8%, and 65.6% from household wastewater. In addition, we were able to remove BOD, COD, total nitrogen (TN), and total phosphorus (TP) from animal husbandry wastewater at rates of 92.9%, 75.6%, 35.1%, and 100%, respectively, thereby achieving dramatic reductions. Considering the excellent removal efficiency and the small size of this device, electrochemical wastewater treatment using a DSA coated in rutile $RuO_2$ presents a promising option for the treatment of both household and animal husbandry wastewater.

• Elastomers and Composites
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• v.34 no.4
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• pp.315-320
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• 1999

Surface modification of silicone rubber by low temperature plasma process was investigated to improve quality of silicone EVD tube by reducing tackiness and hydrophobicity. Treatment with nonpolymer-forming plasmas and thin film deposition with polymer-forming plasmas were tried. Tackiness could significantly be reduced, especially by thin film deposition. As a result, the tube became slippery and less vulnerable to contamination in laboratory environment. Inner as well as outer surface of the tube could be changed to be hydrophilic if the plasma contained oxygen. As a result, initial hydrodynamic resistance was reduced. The surface modification did not give any bad influence on mechanical properties of the silicone tube in most cases. Rather, some properties such as Young's modulus, ultimate tensile strength and elongation at break were improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2189-2198
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• 2014

Paraquat (PQ) is a very effective and widely used herbicide that was commercially introduced in 1962. In this study, instead of using antioxidants like in the past, to inhibit the formation of PQ-induced ROS, we attempted to reduce the oxygen concentration by using non-lethal hypoxia therapy. Therefore, we studied the toxicity of PQ in vivo, analyzed the major effects of ROS on the targeted lung tissue and compared the results with the gross histological changes after the cell protective effect of non-lethal hypoxia therapy. In vivo studies demonstrated that low-concentration oxygen therapy (i.e., 10-12% oxygen) in rats administered with PQ was associated with a higher survival rate than in rats that received only PQ. In vivo non-lethal hypoxia treatment showed better survival and less lung tissue damage. Using a hypoxic/anaerobic incubator with integrated multifaceted molecular analysis, including MDA assay, glutathione assay, and SOD assay, we established an optimal, significantly reduced in vivo non-lethal hypoxia treatment by exploiting the PQ-induced cytotoxicity responses.

• Textile Coloration and Finishing
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• v.27 no.1
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• pp.18-26
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• 2015

para-aramid fibers were treated by atmosphere air plasma to improve the interfacial adhesion. The wettability of plasma-treated aramid fiber was observed by means of dynamic contact angle surface free energy measurement. Surface roughness were investigated with the help of scanning electron microscopy and atomic force microscopy. The tensile test of aramid fiber roving was carried out to determine the effect of plasma surface treatments on the mechanical properties of the fibers. A pull-out force test was carried out to observe the interfacial adhesion effect with matrix material. It was found that surface modification and a chemical component ratio of the aramid fibers improved wettability and adhesion characterization. After oxygen plasma, it was indicated that modified the surface roughness of aramid fiber increased mechanical interlocking between the fiber surface and vinylester resin. Consequently the oxygen plasma treatment is able to improve fiber-matrix adhesion through excited functional group and etching effect on fiber surface.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.4
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• pp.165-170
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• 2008

In the present study, we aimed to identify the synergistic effects of concurrent treatment of low concentrations of cilostazol and probucol to inhibit the oxidative stress with suppression of inflammatory markers in the cultured human coronary artery endothelial cells (HCAECs). Combination of cilostazol (0.3${\sim}3{\mu}$M) with probucol (0.03${\sim}0.3{\mu}$M) significantly suppressed TNF-${\alpha}$-stimulated NAD(P)H-dependent superoxide, lipopolysaccharide (LPS)-induced intracellular reactive oxygen species (ROS) production and TNF-${\alpha}$ release in comparison with probucol or cilostazol alone. The combination of cilostazol (0.3${\sim}3{\mu}$M) with probucol (0.1${\sim}0.3{\mu}$M) inhibited the expression of vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1) more significantly than did the monotherapy with either probucol or cilostazol. In line with these results, combination therapy significantly suppressed monocyte adhesion to endothelial cells. Taken together, it is suggested that the synergistic effectiveness of the combination therapy with cilostazol and probucol may provide a beneficial therapeutic window in preventing atherosclerosis and protecting from cerebral ischemic injury.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.345-349
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• 1996

The wetting property of polymer surfaces is very important for practical applications. Plasma source ion implantation technique was used to improve the wetting properties of polymer surfaces. Poly(ethylene terephtalate) and other polymer sheets were mounted on the target stage and an RF plasma was generated by means of an antenna located inside the vacuum chamber. High voltage pulses of up to -10kV, 10 $\mu$sec, and up to 1 kHz were applied to the stage. The samples were implanted for 5 minutes with using Ar, $N_2,O_2,CH_4,CF_4$ and their mixture as source gases. A contact angle meter was used to measure the water contact angles of the implanted samples and of the samples stored in ambient conditions after implantation. The modified surfaces were analysed with Time-Of-Flight Mass Spectrometer (TOF-SIMS) and Auger Electron Spectroscopy (AES). The oxygen-implanted samples showed extremely low water contact angles of $3^{\circ}C$ compared to $79^{\circ}C$ of unimplanted ones. Furthermore, the modified surfaces were relatively stable with respect to aging in ambient conditions, which is one of the major concerns of the other surface treatment techniques. From TOF-SIMS analysis it was found that oxygen-containing functional groups had been formed on the implanted surfaces. On the other hand, the $CF_4$-implanted samples turned out to be more hydro-phobic than unimplanted ones, giving water contact angles exceeding $100^{\circ}C$ . The experiment showed that plasma source ion implantation is a very promising technique for polymer surface modification especially for large area treatment.

• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.96-110
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• 2024

Polymer electrolyte membrane fuel cells (PEMFCs) are green energy conversion devices, for which commercial markets have been established, owing to their application in fuel cell vehicles (FCVs). Development of cathode electrocatalysts, replacing commercial Pt/C, plays a crucial role in factors such as cost reduction, high performance, and durability in FCVs. PtNi octahedral catalysts are promising for oxygen reduction reactions owing to their significantly higher mass activity (10-15 times) than that of Pt/C; however, their application in membrane electrode assemblies (MEAs) is challenged by their low stability. To overcome this durability issue, various approaches, such as third-metal doping, composition control, halide treatment, formation of a Pt layer, annealing treatment, and size control, have been explored and have shown promising improvements in stability in rotating disk electrode (RDE) testing. In this review, we aimed to compare the features of each strategy in terms of enhancing stability by introducing a stability improvement factor for a direct and reasonable comparison. The limitations of each strategy for enhancing stability of PtNi octahedral are also described. This review can serve as a valuable guide for the development of strategies to enhance the durability of octahedral PtNi.

• Journal of Mushroom
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• v.11 no.4
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• pp.292-296
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• 2013

Recently, Pleurotus eryngii, King oyster mushroom is the main export item in South Korea mushroom industry. For appropriate transportation to Europe and USA markets, it is necessary to elucidate suitable conditions of storage and treatment of post-harvest during long time shipping. Whole mushrooms were packed with polypropylene anti-fog film (30 um) without trimming. The range of package weight and oxygen permeability of film were 200 g~400 g and 2000~5000 $cc/m^2$, 24 h,atm, respectively. The weight loss ratio was increased with increasing storage time. There were no big differences in weight loss ratio according to package weight and oxygen permeability of film at low temperature storage($4^{\circ}C$). In case of package weight is 400 g and oxygen permeability of film is 3000 $cc/m^2$, 24 h, atm. As a results of freshness, the optimum packing weight and oxygen permeability of film of P. eryngii were 400 g and below 2,000 $cc/m^2$, 24 h, atm, respectively.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.230-234
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• 2007

Oxygen is required for many important aerobic cellular reactions, it may undergo electrontransfer reactions, which generate highly reactive membrane-toxic intermediates (reactive oxygen species, ROS), such as hydrogen peroxide, singlet oxygen, superoxide radical, hydroxyl radical, hydroperoxyl radical, hydroxy ion. Various mechanisms are available to protect cells against damage caused by oxidative free radicals, including scavenging enzyme systems such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). This antioxidant defense system is a very complex and finely tuned system consisting of enzymes capable of detoxifying oxygen radicals as well as low molecular weight antioxidants. In addition, repair and turnover processes help to minimize subcellular damage resulting from free radical attack. $H_2O_2$,one of the major ROS, is produced at a high rate as a product of normal aerobic metabolism. The primary cellular enzymatic defense systems against $H_2O_2$ are the glutathione redox cycle and catalase. From Northern blot analysis of total RNAs from cultured cell with $H_2O_2$ treatment, various results were obtained. Expression of Cu/Zn SOD decreased when cell passage increased, but the level of the Cu/Zn SOD was scarcely expressed in 35 passage.