• Journal of Korea Foundry Society
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• v.35 no.4
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• pp.75-79
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• 2015

Commercial Zr-based amorphous alloy was recycled and oxygen was introduced during the recycling process. The oxygen content can have a great effect on the glass forming ability and the mechanical properties of the alloy. Therefore, it was closely examined. The initial oxygen content in the raw material was 1,244 ppm. It was increased to 3,789 ppm in the alloy after ten recycling processes. As the recycling processes were repeated, the oxygen content increased. Specifically, after four recycling processes, it increased sharply as compared to that after three recycling processes. After ten recycling processes, the glass transition temperature (Tg) increased from 613 K to 634 K and the crystallization temperature (Tx) increased from 696 K to 706 K. On the other hand, the super-cooled liquid region (${\Delta}T=Tx-Tg$) decreased slightly from 83 K to 72 K while the reduced glass transition temperature (Trg = Tg/Tm) was 0.63, remaining constant even when the oxygen content was increased. These results indicated that the increased oxygen content deteriorated the glass forming ability. The bending strength as determined in a three-point bending test showed a sharp decrease from 3,055 to 2,062 MPa as the oxygen content was increased from 1,244 ppm to 3,789 ppm; the extension was also decreased from 3.02 to 1.74 mm. These findings meant that the alloy became brittle.

• Journal of the Korean Society of Tobacco Science
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• v.18 no.1
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• pp.49-53
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• 1996

This experiment was carried out to study the effect of oxygen on chemical composition and physical properties of tobacco leaves during flue-curing. The results obtained were as follows: Starch content decreased and sucrose content increased with increasing oxygen supply during curing. Glucose and fructose of the cured leaves showed high content at the 5-10% oxygen supply. Amino-N and nitrate-N increased with increasing oxygen supply. Total nitrogen and NH4-N showed the lowest value at the 5-10% and 10-15% oxygen supply in the cutters and leaf, respectively. Chlorophyll and chlorogenic acid increased, and total volatile base decreased with increasing oxygen supply. The activity of α-amylase increased at the latter period of flue-curing, and the maximum activity point were delayed 12 hours with increasing oxygen supply. Shatter index of cured leaves decreased with increasing oxygen supply. It was desirable to supply oxygen during flue-curing for the improvement of chemical and physical properties such as starch, total sugar, chlorogenic acid, and shatter index of cured leaves.

• Korean Journal of Materials Research
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• v.21 no.11
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• pp.617-622
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• 2011

The effect of oxygen on the shape memory characteristics in Ti-18Nb-6Zr-XO (X = 0-1.5 at%) biomedical alloys was investigated by tensile tests. The alloys were fabricated by an arc melting method at Ar atmosphere. The ingots were cold-rolled to 0.45 mm with a reduction up to 95% in thickness. After severe cold-rolling, the plate was solution-treated at 1173 K for 1.8 ks. The fracture stress of the solution-treated specimens increased from 450 Mpa to 880 MPa with an increasing oxygen content up to 1.5%. The fracture stress increased by 287MPa with 1 at% increase of oxygen content. The critical stress for slip increased from 430 MPa to 695 MPa with an increasing oxygen content up to 1.5 at%. The maximum recovery strain of 4.1% was obtained in the Ti-18Nb-6Zr-0.5O (at%) alloy. The martensitic transformation temperature decreased by 140 K with a 1.0 at% increase in O content, which is lower than that of Ti-22Nb-(0-2.0)O (at%) by 20 K. This may have been caused by the effect of the addition of Zr. This study confirmed that addition of oxygen to the Ti-Nb-Zr alloy increases the critical stress for slip due to solid solution hardening without being detrimental to the maximum recovery strain.

• Carbon letters
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• v.1 no.1
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• pp.17-21
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• 2000

Catalytic reduction and oxidation of NO over polyacrylonitrile based activated carbon fibers (PAN-ACF) under various conditions were carried out to develop removal process of NO from the flue gas. The effect of temperature, oxygen concentration and the moisture content for the reduction of NO with ammonia as a reducing agent was investigated. The reduction of NO increased with the oxygen concentration, but decreased with the increased temperature. The moisture content in the flue gas affects the reduction of NO as the inhibition of the adsorption of the other components and the reaction on the surface of ACE For the oxidation of NO to $NO_2$ over PAN-ACF without using a reducing gas, it showed the temperature and the oxygen concentration of the flue gas are the important factors for the NO conversion in which the conversion increased with oxygen concentration and decreased with the temperature increase and might be the alternative option for the selective catalytic reduction process.

• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.229-233
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• 1993

The effects of differential partial pressures of oxygen during sputtering on the magnetic and recording characteristics of magneto-optical disks were investigated. Different flows of oxygen were deliberately introduced into the sputtering chamber to have a variety of partial pressures of oxygen during sputtering. A residual gas analyzer was employed to monitor the oxygen peak before, during, and after sputtering and to estimate the reacted oxygen amount. Most of the oxygen introduced into the chamaber was reacted during sputtering. As the partial pressure of oxygen increased, the oxygen content of the TbFeCoCr film increased also. The oxygen appeared to be bound as Tb-O, effectively decreasing the magnetically active Tb content of the film The coercivity decreased but the squareness of the Kerr hysteresis loops was still excellent. The perpendicular anisotropy was not significantly affected by oxygen amount. The carrier-to-noise ratio, includi!1g the write power sensitivity and bias field sensitivity did not change too much with oxygen content in the film The disks sputtered with oxygen showed better bias field sensitivity with lower write power threshold than the disk sputtered without oxygen, due to high demagnetization during domain formation. No significant degradation of coercivity for the disk sputtered oxygen was observed during an accelerated aging test.

• Bulletin of the Korean Chemical Society
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• v.22 no.2
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• pp.194-198
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• 2001

In order to look for polymeric materials applicable to the oxygen electrode membranes of biosensors, polyurethanes (PUs) were synthesized from poly(butylene succinate) diol (Mn 1150), poly(ethylene glycol) (Mn 200), and 4,4'-methylenebis(cyclohexyl isocyanate). The PUs (Mn 15000-100000) underwent the crystallization and melting transitions in the temperature range of 20-30 $^{\circ}C$ and 90-110 $^{\circ}C$, respectively. The oxygen permeability for the PU membranes prepared by the solution casting method could not be measured since oxygen simply leaked through the membranes with an audible noise. However, when the PUs were blended with carboxylated poly(vinyl chloride) (CPVC), the permeability could be measured. The oxygen permeability coefficient (Po2) of the PU/CPVC $(96}4)$ membranes (6.4 Barrer) was high enough for the application as the electrode membranes. The Po2 decreased dramatically when the CPVC content increased from 4 to 5 wt%, but decreased very slowly and approached to that of CPVC (~0.26 Barrer) when the CPVC content increased further. The scanning electron micrographs of the membranes revealed that the PU membranes were composed of large crystal grains with many pores, but the size of the PU crystal grains and pores decreased progressively with increasing the CPVC content.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.5
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• pp.753-758
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• 2016

Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg $O_2/g$ VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS's optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust's coarse particle size and bulking effect.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.2
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• pp.91-95
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• 2000

The effects of argon gas flow on the axial temperature gradient near the interface, the oxygen concentration, and the radial oxygen uniformity was investigated for 8-inch CZ silicon growth. As argon flow rate was increased, the temperature gradient was increased in the crystal near the crystavmelt interface and the oxygen content in the crystal was decreased. But the radial oxygen uniformity was deteriorated. It was found that argon flow is one of the important growing parameters to affect the quality of crystals such as oxygen content and uniformity.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.38-43
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• 2022

The effect of introducing oxygen functional groups by oxygen plasma treatment of activated carbon on adsorption properties of cesium ions was investigated. During the oxygen plasma treatment, the frequency, power, and oxygen gas flow rates were fixed at 100 kHz, 80 W, and 60 sccm, respectively, while the reaction time was varied. Under the experimental conditions, the amount of cesium ion adsorption increased as the content of oxygen groups on C-O-C and O=C-O bonds increased when the reaction time with oxygen gas was 10 minutes. However, when the reaction time increased to 15 minutes, the oxygen functional group content decreased resulting in the decrease of the adsorbed cesium ion amount. On the other hand, unlike the oxygen content of the surface-treated activated carbon, the specific surface area and pore properties were hardly affected by the oxygen plasma reaction time. As a result, the oxygen plasma-treated activated carbon improved the cesium ion removal rate by up to 97.3% compared to that of the untreated activated carbon. This is considered to be due to the content of oxygen groups on C-O-C and O=C-O bonds introduced on the surface of the activated carbon through oxygen plasma treatment.

• Toxicological Research
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• v.18 no.2
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• pp.159-165
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• 2002

Recently, we reported (korean J. Biomed. Lab. Sci., 6(4): 245-251, 2000) that cyclohexane (l.56 g/kg of body wt., i.p.) administration led to lung injury in rats. However the detailed mechanism remain to be elucidated. This study was designed to clarify the mechanism of lung damage induced by cyclohexane in rats. First, lung damage was assessed by quantifying bronchoalveolar lavage fluid (BAL) protein content as well us by histopathological examination. Second, activities of serum xanthine oxidase (XO), pulmonary XO and oxygen free radical scavenging enzymes. XO tope conversion (O/D + O, %) ratio and content of reduced glutathione (GSH) were determined. In the histopathological findings, the vasodilation, local edema and hemorrhage were demonstrated in alveoli of lung. And vascular lumens filled with lipid droplets, increased macrophages in luminal margin and increased fibroblast-like interstitial cells in interstitial space were observed in electron micrographs. The introperitoneal treatment of cyclohexane dramatically increased BAL protein by 21-fold compared with control. Cyclohexane administration to rats led to a significant rise of serum and pulmonary XO activities and O/D + O ratio by 47%,30% and 24%, respectively, compared witれ control. Furthermore, activities of pulmonary oxygen free radical scavenging enzymes such as superoxide dismutase, glutathione peroxidase and glutathione S-transferase, and GSH content were not found to be statistically different between control and cyclohexane-treated rats. These results indicate that intraperitoneal injection of cyclohexane to rats may induce the lipid embolism in pulmonary blood vessel and lead to the hypoxia with the ensuing of oxygen free radical generation, and which may be responsible for the pulmonary injury.