• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3307-3311
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• 2013

A new fiber optical sensor was developed for the determination of 2,4-dichlorophenol (DCP). The sensor was based on DCP oxidation by oxygen with the catalysis of iron(III) tetrasulfophthalocyanine (Fe(III)PcTs). The optical oxygen sensing film with $Ru(bpy)_3Cl_2$ as the fluorescence indicator was used to determine the consumption of oxygen in solution. A lock-in amplifier was used for detecting the lifetime of the oxygen sensing film by measuring the phase delay change of the sensor head. The different variables affecting the sensor performance were evaluated and optimized. Under the optimal conditions (i.e. pH 6.0, $25^{\circ}C$, Fe(III)PcTs concentration of 0.62 mg/mL), the linear detection range and response time of the sensor are $1.0{\times}10^{-6}-9.0{\times}10^{-6}$ mol/L and 250 s, respectively. The sensor displays high selectivity, good repeatability and stability, and can be used as an effective tool in analyzing DCP concentration in practical samples.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.5
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• pp.201-206
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• 2004

In order to investigate the optimum conditions for the effective ozone formation in a dielectric barrier discharge, measurements of ozone concentration were carried out for various conditions such as the gap length, the dielectric material and the operating gas. It was found that the optimum discharge conditions differed exceedingly in the types of operating gases and dielectric materials. In dry air, dielectric material with low dielectric constant and thermal conductivity, which might contribute to the restriction of the gas temperature rise in the discharge region, proved effective in obtaining both high ozone yield and concentration. The optimum gap length was considered to be in the range of 600-800 mm. In oxygen, using a quartz glass disk as a dielectric material, the required condition to obtain the high ozone yield and concentration was expanded.

• Journal of Korean Society on Water Environment
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• v.37 no.1
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• pp.1-9
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• 2021

The depletion of dissolved oxygen (DO) in urban streams has a profound effect on the aquatic ecosystem; however, the change in DO by resuspension of sediments and the cause have not been sufficiently investigated. In this study, the physicochemical properties (particle size, and the content of organic and heavy metals) of the sediments of an urban stream (Anyang Stream) and the characteristics of water quality changes (DO, dissolved organic carbon (DOC), dissolved nitrogen (DN), sediment oxygen demand (SOD), and adenosine triphosphate (ATP)) by sediment resuspension were investigated. The sediment content of fine particles (< 0.2 mm) increased from 36.7% to 52.7% from the upstream to the downstream, and the contents of heavy metals and organic matter of the sediment were also higher towards the downstream. The depletion of DO by resuspension was observed in the sediment at the downstream sites (P8, P9), where the fine particle content was high, and biological SOD (BSOD) was more than 88% compared to the total SOD. The increase in BSOD coincided with the increase in ATP. It was also confirmed that the depletion of DO could increase the amount of heavy metals (such as Fe, Mn, and Pb) released from the sediment. Based on the above results, it can be concluded that resuspension of sediments induces rapid water quality changes and may cause accidents, such as fish mortality, during rainfall, and such a water quality effect can be more pronounced in sediments with a high content of fine particles and organic matter and high biological activity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.1
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• pp.52-58
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• 1991

Mass mortality of Halocynthia roretzi has been occurred in culturing grounds of southern coast of Korea during the long period of summer drought and the unusal high water temperature in 1988. Especially Halocynthia roretzi was damaged severely in 2 years group. Therefore we verified these phenomena by observing the environmental factors of culturing grounds and by evaluating oxygen consumption rate in indoor experiment. In culturing grounds, the mortality rate was high in Namhae Mizo area where water temperature was the highest and the lowest in dissolved oxygen concentration as low as 3.76m/l in field observation. In indoor experiment, the higher the water temperature, the more mortality was occurred and the salinity above 30 had no effect on its mortality. In oxygen consumption rate experiment, the smaller needs more oxygen than larger one, i. e., oxygen demand per unit weight was higher in 2 years group than that of 3 years. The theoretical and the actual minimum oxygen demands(MOB) for preventing asphixation was 3.7ml/kg/h at $20^{\circ}C$ and 6.3ml/kg/h gat $25^{\circ}C$, But actual MOD was 4.3ml/kg/h at $25^{\circ}C$ in indoor experiment. It seemed that mass mortality of Halocynthia roretzi in summer was caused by metabolism disorder due to insufficient oxygen level influenced by the high water temperature and the high density of Halocynthia roretzi, which results in the paucity of oxygen especially in 2 years groups.

• Bulletin of the Korean Chemical Society
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• v.15 no.9
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• pp.724-729
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• 1994

The effect of oxygen for the HF chemical laser performance has been theoretically investigated. Due to the inhibition mechanism of $O_2$ in $H_2$/$F_2$ chain reaction, the rate for the formation of HF is reduced by the addition of $O_2$. As the concentration of $O_2$ in the reaction mixture increases, the pulse power and temperature of the system becomes lower, while total output energy does not change significantly. But addition of $O_2$ makes the system easy to be controlled and the composition of $H_2$+$F_2$ can be high at constant total pressure. With this system, it is possible to obtain higher output energy than oxygen free environment.

• Bulletin of the Korean Chemical Society
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• v.22 no.4
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• pp.362-366
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• 2001

To show the effects of metallothionein (MT) on the activity of enzymes involved in the removal of reactive oxygen species, MT has been added to the assay systems of superoxide dismutase (SOD), catalase and peroxidase. We have used assay systems of SOD based on NADPH oxidation and nitrite formation from hydroxylammonium chloride as an assay of superoxide breakdown rate. The two assay systems showed different results at the high concentration of MT. MT showed the scavenging of superoxide in the SOD assay system in the presence and absence of SOD. MT added to the SOD assay system behaved as an activator of SOD, but apo-MT behaved as an inhibitor. When MT was added to the assay system in the presence of a fixed amount of SOD, the breakdown rate of superoxide increased. The effects of MT on the decomposition of hydrogen peroxide and the activity of catalase and peroxidase decomposing hydrogen peroxide were evaluated. MT decreased the activities of catalase and peroxidase. We have concluded that the function of MT as an antioxidant might effect the level of superoxide scavenging and not the level of hydrogen peroxide.

• Clinical and Experimental Reproductive Medicine
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• v.23 no.3
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• pp.351-355
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• 1996

Objective: To analyze the direct effect of nitre oxide, generated from sodium nitroprusside, on sperm motility and reactive oxygen species. Design: Human sperm samples were treated to allow swim-up and washing. And the samples were devided into four aliquots. Each aliquot was incubated with either concentration at 0, 100nM, $10{\mu}M$, 1mM of nitroprusside. Intervention: Samples were measured chemiluminosence for reactive oxygen species of each aliquot with concentrations at 0, 100nM, $10{\mu}M$, 1mM of nitroprusside at allowing swim-up and washing of sperm. Main Outcome Measures: Percent motion parameters and viability were asse-ssed at 0, 3, 6, 12, 24 hours incubation. Results: The percent viablity was lower slightly in control group (50.2%) than that in sperm treated with 100nM of nitroprusside(57.5%) at 24 hours after incubation, while was reduced significantly in sperm with concentra-tion of $10{\mu}M(42.1%)$ and 1mM(21.3%)of nitroprusside at 6 hours after incubation. And the sperm treated with 1mM of nitroprusside was immotile totally at 6 hours after incubation. The straight line$(35.3{\pm}5.6%)$, the rapid forward$(37.2{\pm}6.4%)$ and the weak curvilinear velocity$(9.6{\pm}2.4%)$were more favorable comparing with those ($32.4{\pm}4.2%$, $30.0{\pm}7.8%$ and $18.0{\pm}4.6%$ respectively) in control group at 3 hours after incubation, but reduced significantly in sperm treated with $10{\mu}M$ and 1mM of nitroprusside. The levels of reactive oxygen species in control(700 c.p.m.) is lower significantly than that in each experimental groups of sperm treated with nitroprusside. And the levels of reactive oxygen species were 2200 c.p.m. in 100nM, 6200c.p.m. in $1{\mu}M$ and 12800c.p.m. in 1mM respectively. Conclusion: These results suggested that the concentration of 100nM of nitroprusside on sperm is beneficial to the maintanance of viablity and motile velocity, but detriment in high concentration of $10{\mu}M$ or 1mM of nitroprusside.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.12
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• pp.46-53
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• 1997

The TMA gas sensors are fabricated with the ZnO-based thin films grown by a RF magnetron sputtering method. The hall effect measurement and AES analysis are carried out to investigate the effects of the sputtering gases and dopants which effect on the electrical resistivity and sensitivity to TMA gas. We measure the cfhanges of the surface carrier concentration, haall electron mobility, electrical resistivity, surface condition, and depth profile of the films. The ZnO-based thin film sensors sputtered in oxygen, or added with dopants showed a high sruface carrier concentration, film sensors sputtered in oxygen and doped with 4.0 wt.% $Al_{2}$O$_{3}$, 1.0 wt.% TiO$_{2}$, and 0.2 wt% v$_{2}$O$_{5}$ showed the highest surface carrier concentration of 5.952 * 10$^{20}$ cm$^{-3}$ , hall electron mobility of 176.7 cm$^{2}$/V.s, lowest electrical resistivity of 6*10$^{-5}$ .ohm.cm and highest sensitivity of 12. These results were measured at a working temperature of 300.deg. C to 8 ppm TMA gas.

• Journal of Chest Surgery
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• v.16 no.3
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• pp.272-280
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• 1983

With respect to controversial opinions concerning the nitroglycerin effects on cardiac muscle the direct nitroglycerin actions were thoroughly studied in isolated papillary muscles, atrial preparations and coronary strips of rabbits. Isometric active tension of papillary muscles developed at $35^{\circ}C$ upon electric stimulation at a rate of 60/min, was not affected by nitroglycerin up to a concentration of 10mg/L Higher concentrations of nitroglycerin, however, reduced action tension progressively. This depression of mechanical activity is accompanied by a decrease in oxygen consumption as measured by means of a flow respirometer. Resting oxygen uptake, on the other hand, remained unchanged. Similarly active tension of spontaneously beating atrial preparations also declined at a nitroglycerin concentration of more than 10 mg/L, whereas the sinus frequency did not change up to 40 mg/L. In contrast, rabbit coronary strips are much more sensitive to nitroglycerin and relax in a range of 10-100 ug/L of nitroglycerin concentration. The results indicate that the pharmacologic effects of nitroglycerin in coronary disease are due to vascular actions, because the plasma levels of nitroglycerin attainable in human therapy are not sufficiently high to directly influence the myocardium.

• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.269-274
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• 2003

The electrical, optical and structural properties of ZnNiO thin _ films deposited on Si substrates using rf-magnetron sputtering method have been investigated before and after the thermal annealing processes. The crystallinity of the ZnNiO thin film become degraded with increasing the Ni contents. This is mainly because the lattice of the thin film was expanded due to the oxygen-deficient conditions. Concerning the electrical properties of the thin film, the carrier concentration increases ($6.81\times10^{14}\textrm{cm}^{-2}$) and Hall mobility decreases (36.3 $\textrm{cm}^2$/Vㆍs) with higher doping concentration of Ni. However, the carrier concentration and Hall mobility became low ($1.10\times10^{14}\textrm{cm}^2$ and high (209.6 $\textrm{cm}^2$/Vㆍs), respectively, after the thermal annealing process at $1000 ^{\circ}C$. We also observed a strong luminescene center peaking at 546 nm in photoluminescence spectra, which was caused by a deep level center in the ZnO band gap with oxygen deficient ZnNiO structure.