Nanostructured ceria powder was synthesized by a thermochemical process and investigated its applicability for an oxygen gas sensor. An amorphous precursor powders prepared by spray drying a cerium-nitrate solution were transformed successfully into nanostructured ceria by heat-treatment in air atmosphere. The powders were a loose agglomerated structure with extremely fine particles about 15 nm in size, resulting in a very high specific surface area . The oxygen sensitivity and the response time measured at sintered sample at was about -0.25 and very short, i.e., seconds, respectively.

Ru-C nano-composite films were prepared by MOCVD, and their microstructures and their electrode properties for oxygen gas sensors were investigated. Deposited films contained Ru particles of 5-20 nm in diameter dispersed in amorphous C matrix. The AC conductivities associating to the interface charge transfer between Ru-C composite electrode and YSZ electrolyte were 100-1000 times higher than that of conventional paste-Pt electrodes. The emf values of the oxygen gas concentration cell constructed from the nano-composite electrodes and YSZ electrolyte showed the Nernstian theoretical values at low temperatures around 500 K. The response time of the concentration cell was 900 s at 500 K.

WC-TiC-TaC binderless cemented carbide was oxidized under low partial pressure of oxygen (50ppm) at 873K for 1 to 20 h. Surface roughness was measured using atomic force microscope, and effect of TiC amount on oxidation behavior of the carbide was investigated. WC phase was oxidized more easily than WC-TiC-TaC solid solution phase. With an increase in TiC amount, WC-TiC-TaC phase increased and the oxidation resistance of the carbide increased.

본 연구의 목적은 21%농도의 산소와 비교하여 30%의 고농도 산소 흡입이 사이클 등속 운동 중에 심박동률(heart rate)과 혈중 산소 포화도(SPO2)에 미치는 영향을 분석하는 것이다. 21%와 30% 농도의 산소를 각각 8liter/min의 양으로 일정하게 공급할 수 있는 산소 공급 장치를 이용하였다. 신체 건강한 10명의 남자 대학생(25.2±2.2세)이 21%와 30%의 두 종류의 산소 농도를 대상으로 각각 두 번의 실험에 참여하였다. 실험은 안정(2분), 20±1km/h의 사이클 등속 운동(10분), 회복(6분)의 세 구간(총 18분)으로 구성되어 있고, 21%또는 30%의 산소는 등속 운동과 회복 구간에만 공급되었다. 21%에 비해 30%산소를 흡입했을 때 사이클 등속 운동과 회복 기간 중에 심박동률은 감소하였고, 혈중 산소 포화도는 .차이가 없었다. 21%와 30% 두 그룹 사이에 동일한 운동부하가 주어졌기 때문에 혈중 산소 포화도는 차이가 없는 것으로 판단되고, 30%의 고농도 산소 흡입으로 동일운동 부하에 필요한 산소 요구량이 원활히 공급되고 있기 때문에 심박동률은 감소한 것으로 판단된다.

In this study, dietary Rhus verniciflua Stockes were feeded on the porks and Hanwoo beef to determinate sanitation effects. this experiment was performed to measure oxygen contents and total flavor compounds of pork and beef inoculated Pseudomonas aeruginosa in headspace with SPME-GC. The headspace oxygen contents in Hanwoo beef were no difference on the diet supplementation ratio of Rhus verniciflua Stokes during storage at 5℃. Headspace oxygen contents of teratment dieted for 5 and 6months were higher than that of treatment dieted for 3 and 4months. No remarkable difference was observed in headspace oxygen contents in pork between control and treatment during storage at 0℃. Oxygen contents in pork of treatment diet containing 4% Rhus verniciflua Stokes was higher than that of treatment were lower than that of control on Hanwoo beef. Flavor compounds were the lowest in diet supplemented 6% of Rhus verniciflua Stokes during 4 months. Flavor compounds of pork is no change at 0℃. The longer storage periods It had the more increasing total flavor compounds and Rhus verniciflua Stokes supplement ratio had no effects on change of total flavor compounds. Such as this experiment, Flavor compounds and oxygen contents in headspace could be analyzed by SPME-GC method promptly and easily in accordance with, it is expected to apply SPME-GC method to evaluation of food quality.

This study was purposed to provide basic information on the correct application of a wheelchair's backrest angle by investigating the change in cardiopulmonary function according to backrest angle during propulsion. This study examined the effects of the wheelchair's backrest angle on the cardiopulmonary function by varying the angle to 0°, 10° and 20° and with a propulsion velocity of 60 m/min. The experimental parameters were respiration rate, oxygen consumption rate and oxygen consumption rate/kg which were measured by a portable wireless oxygen consumption meter (COSMED, K4b²). The results of the study were as follows: 1) There were no statistically significant differences in respiration rates due to changes in the wheelchair backrest angle (p>.05). 2) There were statistically significant differences in oxygen consumption rates due to changes in the wheelchair backrest angle (p<.05). 3) There were also statistically significant differences in the oxygen consumption rate/kg due to changes in the wheelchair backrest angle (p<.05). In conclusion, changes in the backrest angle of wheelchairs during propulsion influences oxygen consumption rates and heart rates, while respiration rates are not affected. Therefore, a training program for good seating and posture needs to be provided, and the wheelchair seating system should be equipped with the unadjustable-angle wheelchair to reduce the functional load on the cardiopulmonary system.

In the present study, the focus is on the effect of cobalt oxide powder in the carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fine TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under flowing argon atmosphere. Changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. Titanium-cobalt-oxygen based oxide powder desalted at had a mixture of . And the one desalted at had a mixture of . In the case of the former powder, the reduction of cobalt oxide powder in the titanium-cobalt-oxygen based oxide powder occurred at lower temperature than the latter one. However, the carbothermal reduction of titanium dioxide powder in the titanium-cobalt-oxygen based oxide powder with a mixture of occurred at higher temperature than the one with a mixture of . And also, the former powder showed a lower TiC formation ability than the latter one.

EGCG [(-)-epigallocatechin gallate], is a major component of green tea has been considered as a major antioxidant constituent. It has been considered as potential chemopreventive and chemotherapeutic agents. However, very little is known about the cellular actions by which EGCG mediates its therapeutic effects. Various aspects of antioxidant activity of EGCG were evaluated in this study. EGCG itself did not show significant cytotoxicity. Significant 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was observed in all ranges of concentration (0.8-100μ/mℓ used in this study. Protective effect of EGCG against hydrogen peroxide induced cell death was observed. Relatively high lipid peroxidation inhibitory activity were detected ( IC50was about 20μg/mℓ). EGCG also dose-dependently enhanced the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) in V79-4 cells. In concentrations of 100μ/mℓ of EGCG, activities of SOD, CAT and GPX were measured as 36.9 U/mg of protein, 22.9 U/mg of protein and 17.8 U/mg of protein, respectively. When these values were compared with those of the control groups (24.9 U/mg of protein, 14.9 U/mg of protein and 11.7 U/mg of protein), the relative increases were calculated as 48, 54 and 52%, respectively. Taken together, our findings suggest that EGCG can act as an antioxidant by scavenging radicals and enhancing antioxidant enzyme activities.

We investigate the spectral energy distributions (SEDs) of low mass-loss rate O-rich asymptotic giant branch (AGB) stars using the infrared observational data including the Infrared Space Observatory (ISO) data. Comparing the results of detailed radiative transfer model calculations with observations, we find that the dust formation temperature is much lower than 1000 K for standard dust shell models. We find that the superwind model with a density-enhanced region can be a possible alternative dust shell model for LMOA stars.

Isotopes of alkali and alkaline earth metals (AM and AEM) are the main contributors to the heat load and the radiotoxicity of spent fuel (SF) . These components are separated from the SF and dissolved in a molten LiCl in an electrolytic reduction process. A mass transfer model is developed to describe the diffusion behavior of Cs, Sr, and Ba in the SF into the molten salt. The model is an analytical solution of Fick's second law of diffusion for a cylinder which is the shape of a cathode in the electrolytic reduction process. And the model is also applied to depict the concentration profile of the oxygen ion which is produced by the electrolysis of LiO. The regressed diffusion coefficients of the model correlating the experimentally measured data are evaluated to be greater in the order of Ba, Cs, and Sr for the metal ions and the diffusion of the oxygen ion is slower than the metal ions which implies that different mechanisms govern the diffusion of the metal ions and the oxygen ions in a molten LiCl.