• Microbiology and Biotechnology Letters
• /
• v.34 no.4
• /
• pp.338-341
• /
• 2006

The growth characteristics of sulfur-oxidizing bacteria, Acidithiobacillus thiooxidans AZ11, MET, and TAS were investigated in mineral salt media supplemented with elemental sulfur of 1$\sim$50 g $L^{-1}$. The sulfur oxidation rates of A. thiooxidans. MET and TAS increased highly with increasing sulfur concentration up to 10 g L$^{-1}$, but the rates increased slowly in sulfur concentration over 10 g L$^{-1}$. A. thiooxidans AZ11 showed the parallel increase of sulfur oxidation rate until sulfur concentration increased up to 40 g L$^{-1}$. The maximum sulfur oxidation rates (V$_{max}$) of AZl1, MET and TAS were 1.88, 1.38 and 0.43 g S L$^{-1}$ d$^{-1}$, respectively. The maximum specific growth rates (${\mu}_{max}$) of AZ11, MET, and TAS were 0.33 d$^{-1}$, 0.30 d$^{-1}$ and 0.45 d$^{-1}$, respectively. Although MET and TAS couldn't grow at sulfate concentration of 40 g L$^{-1}$, AZ11 could grow in the presence of 58 g L$^{-1}$ sulfate, the final oxidation product of elemental sulfur.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.152-152
• /
• 2013

Mechanism of energy conversion from chemical to electrical during exothermic catalytic reactions at the metal surfaces has been a fascinating and crucial subject in heterogeneous catalysis. A metal-semiconductor Schottky nanodiode is novel device for direct detection of chemically induced hot electrons which have sufficient energy to surmount the Schottky barrier. We measured a continuous chemicurrent during the hydrogen oxidation under of 760 Torr of O2 and 6 Torr of H2 by using Pt/Si and Pt/TiO2 nanodiodes at reaction temperatures and compared the chemicurrent with the reaction turnover rate. The thermoelectric current was measured by carrying out an experiment under O2 condition for elimination of the background current. Gas chromatograph and source meter were used for measurement of the chemical turnover rate and the chemicurrent, respectively. The correlation between the chemicurrent and the chemical turnover rate under hydrogen oxidation implies how hot electrons generated on the metal surface affect hydrogen oxidation.

• Journal of Power System Engineering
• /
• v.10 no.3
• /
• pp.51-57
• /
• 2006

The effect of grain size on corrosion resistance and high temperature oxidation behavior was studied in 22Cr-15Ni-5W super austenitic stainless steels for desulfurization equipment as a heat power station. In the high temperature oxidation test, oxidation rate was increased as the temperature increased from $600^{\circ}C\;to\;800^{\circ}C$. In vapor, oxidation rate was faster than that in air. Because the vapor was inhibited nucleation of $Cr_2O_3$ film. And the high temperature oxidation resistance at $600^{\circ}C{\sim}800^{\circ}C$ was excellent from all specimens and specimen of the smallest grain size was the most excellent. Because increasing of diffusion course through the grain-boundary was promoted nucleation and growth of $Cr_2O_3$ film. In the test temperature at $600^{\circ}C{\sim}800^{\circ}C$, Cr rich round particle oxide was formed in air, whereas Fe rich needle type oxide was developed in vapor.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.11
• /
• pp.3544-3550
• /
• 2012

Cetrizine dihydrochloride (CTZH) is widely used as an anti-allergic drug. Sodium N-bromo-p-toluenesulfonamide or bromamine-T (BAT) is the bromine analogue of chloramine-T (CAT) and is found to be a better oxidizing agent than CAT. In the present research, the kinetics of oxidation of CTZH with BAT in acid and alkaline media was studied at 313 K. The experimental rate laws obtained are: -d[BAT]/dt=$k[BAT][CTZH]^{0.80}[H^+]^{-0.48}$ in acid medium and -d[BAT]/dt=$k[BAT][CTZH]^{0.48}[OH^-]^{0.52}[PTS]^{-0.40}$ in alkaline medium where PTS is p-toluenesulfonamide. Activation parameters and reaction constants were evaluated. The solvent isotope effect was studied using $D_2O$. The dielectric effect is positive. The stoichiometry of the reaction was found to be 1:1 and the oxidation products were identified as 4-chlorobenzophenone and (2-piperazin-1-yl-ethoxy)-acetic acid in both media. The rate of oxidation of CTZH is faster in acid medium. Suitable mechanisms and related rate laws have been worked out.

• Journal of Korean Physical Therapy Science
• /
• v.8 no.2
• /
• pp.1039-1045
• /
• 2001

The aim of this study is to show the results which we analyse the interrelation among the physiological variable elements. We survey thirty fat women who don't do exercise regularly and are thirties. in order to offer basic data for setting the optimal exercise intensity through the efficient fat oxidation. We use RAMP II protocol of the Ever Green Hospital. The results are followings: 1. When the optimal exercise intensity for fat oxidation is done, there's a meaningful relation among the fat oxidation, $O_2$ max, and respiratory change. 2. When the optimal exercise intensity for fat oxidation is done, there's no meaningful relation statistically in $O_2$ max, heart rate, respiratory change, and caloric rate. 3. When the optimal exercise intensity for fat oxidation is done, there's a meaningful difference among three groups in %$VO_2$ max. However, there's a meaningful difference between group C and group A. B, and there's no meaningful difference between group B and group A.

• Nuclear Engineering and Technology
• /
• v.29 no.2
• /
• pp.93-98
• /
• 1997

Air-oxidation experiments on unirradiated and irradiated UO$_2$ were performed at temperature from 150 to 375$^{\circ}C$ for investigating the long-term storage behavior of spent PWR fuel. The rate of oxidation was monitored by a thermogravimetric analyzer(TGA) and an X-ray diffraction(XRD). The correlation between the onset-time for U$_3$O$_{8}$ formation and temperature was given as follows, logt(hr) = -12.89+7650/T(K), 423$_2$ pellet, the oxidation rate of irradiated UO$_2$ increase more rapidly at the initial stage and shows a lower saturation point at the later Stage. The Oxidation rate of high bumup UO$_2$ and gadolinia-doped UO$_2$(Gd$_2$O$_3$-UO$_2$) were observed to be much slower than that of unirradiated UO$_2$ pellets.s.

• Journal of Powder Materials
• /
• v.11 no.2
• /
• pp.111-117
• /
• 2004

The oxidation behavior of 91 WC-9Co hardmetal in weight percentage has been studied in the present work as a part of the development of recycling process. The morphological and compositional changes of the WC-Co hardmetal with oxidation time at 90$0^{\circ}C$ were analyzed by using surface observation and X-ray diffraction. respective]y. As the oxidation time increased, the WC-Co hardmetal was continuously expanded to form porous oxide mixtures of $CoWO_4$ and $WO_3$. The morphology of porous oxide mixture was basically dependent on initial shape of the WC-Co hardmetal. From thermo-gravimetric (TG) analysis, it was found that the oxidation rate was increased with increasing oxidation temperature and oxygen content in the flowing atmospheric gas. The fraction of oxidation versus time curves showed S-curve relationship at a given of oxidation temperature. These oxidation behaviors of the WC-Co hardmetal were discussed in terms of previously proposed kinetic models.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.735-738
• /
• 2000

This paper shows experimentally that oxide layer on the p-type Si-substrate can grow at low temperature(500$^{\circ}C$∼600$^{\circ}C$) using high pressure water vapor system. As the result of experiment, oxide layer growth rate is about 0.19${\AA}$/min at 500$^{\circ}C$, 0.43${\AA}$/min at 550$^{\circ}C$, 1.2${\AA}$/min at 600$^{\circ}C$ respectively. So, we know oxide layer growth follows reaction-controlled mechanism in given temperature range. Consequently, granting that oxide layer growth rate increases linearly to temperature over 600$^{\circ}C$, we can expect oxide growth rate is 5.2${\AA}$/min at 1000$^{\circ}C$. High pressure oxidation of silicon is particularly attractive for the thick oxidation of power MOSFET, because thermal oxide layers can grow at relatively low temperature in run times comparable to typical high-temperature, 1 atm conditions. For higher-temperature, high-pressure oxidation, the oxidation time is reduced significantly

• Journal of the Korean Society for Heat Treatment
• /
• v.18 no.2
• /
• pp.112-118
• /
• 2005

Study was focused on the effect of the cooling rate on the embrittlement behavior of Zircaloy-4 cladding simulated Loss Of Coolant Accident (LOCA) environment. Claddings were oxidized at given temperature and given time followed by various water quenching in the range of $0.6^{\circ}C$ and $100^{\circ}C$ per second. Cladding failed after water quenching above the threshold oxidation. Threshold oxidation was decreased as the cooling rate increased, which is due to the matensite structure formed during fast cooling rate.

• Journal of the Korean Chemical Society
• /
• v.24 no.3
• /
• pp.183-192
• /
• 1980

Oxidation reactions of carbon monoxide on $SnO_2$, Sb-doped $SnO_2$, and Pt catalyst were studied. The oxidation reaction was found to be first order with respect to both CO and O$_2$ on $SnO_2$ and Sb-doped $SnO_2$ catalysts, and to be of half order on Pt catalyst. A small addition of Sb to $SnO_2$ (depant composition: 0.05∼0.1 mol %) increased the rate of oxidation. On the contrary, a large addition decreased the rate. From the rate expression of oxidation on Pt catalyst, the inhibition effect of carbon monoxide on the rate of oxidation was deduced. The experimentally obtained activatio energies were 5.7 kcal for the Sb doped $SnO_2$ catalyst (dopant composion: 0.05 mole%), and 6.4 kcal for the Pt catalyst. A possible reaction mechanism was proposed from the experimentally obtained kinetic data.