• Journal of the Korean Chemical Society
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• v.31 no.2
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• pp.178-183
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• 1987

The kinetics of the reaction of $[Mo_3O_4(H_2O)_9]^{4+}$ with $VO_2^+$have been studied at $25^{\circ}C$ by spectrophotometric method. With$VO_2^+$ in excess, the $[Mo_3O_4(H_2O)_9]^{4+}$ reaction can be expressed as $Mo^{IV}_3+6V^V{\rightleftarrows}3Mo^{IV}+6V^IV}$. Observed rate constants for the reaction are dependent on [$H^+$] and [$VO_2^+$]. Mechanism for the redox of $[Mo_3O_4(H_2O)_9]^{4+}$and $VO_2^+$ is proposed and discussed.

• The Journal of Korean Medicine
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• v.22 no.4
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• pp.58-68
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• 2001

Objectives : This study was designed to investigate the protective mechanisms of Samul-tang (SMT) on $H_2O_2$-induced toxicity in H9c2 cardiomyoblast cells. Methods : The cultured cells were pretreated with SMT and exposed to $H_2O_2$. The cell damage was assessed by using MTT assay. Also, we used Hoechst staining, Western blotting analysis. Results : SMT significantly reduced both $H_2O_2$-induced cell death and chromatin fragmentation. The decrease of Bcl2 expression by $H_2O_2$ was inhibited by SMT. In addition, the increase of Bax expression was also inhibited by SMT. In particular, Fas expression, which is generally recognized as cell death inducing signal by Fas/FasL interaction, was markedly decreased by $H_2O_2$ in a time-dependent manner, whereas this decrease was completely prevented by SMT. The cotreatment of SMT and $H_2O_2$ in H9c2 cells also induced the phosphorylation of ERK in a time-dependent manner. Moreover, PD098059, a specific inhibitor of ERKl/2, attenuated the protective effect of SMT on $H_2O_2$-induced toxicity in H9c2 cardiomyoblast cells. Furthermore, the protective effect of SMT was significantly blocked by treatment of SB203580, a specific inhibitor of p38. Conclusions : Taken together, this study suggests that the protective effects of the water extract of SMT against oxidative damages may be mediated by the modulation of Bel2 and Bax expression via the regulation of ERK and p38 signaling pathway.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.105-114
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• 2007

The most advanced oxidation processes (AOPs) are based on reactivity of strong and non-selective oxidants such as hydroxyl radical (${\cdot}OH$). Decomposition of typical DNAPL chlorinated compounds (TCE, PCE) using various advanced oxidation processes ($UV/Fe^{3+}$-chelating agent/$H_2O_2$ process, $UV/H_2O_2$ process) was approached to develop appropriate methods treating chlorinated compound (TCE, PCE) for further field application. $UV/H_2O_2$ oxidation system was most efficient for degrading TCE and PCE at neutral pH and the system could remove 99.92% of TCE after 150 min reaction time at pH 6($[H_2O_2]$ = 147 mM, UVdose = 17.4 kwh/L) and degrade 99.99% of PCE within 120 min ($[H_2O_2]$ = 29.4 mM, UVdose = 52.2 kwh/L). Whereas, $UV/Fe^{3+}$-chelating agent/$H_2O_2$ system removed TCE and PCE ca. > 90% (UVdose = 34.8 kwh/L, $[Fe^{3+}]$ = 0.1 mM, [Oxalate] = 0.6 mM, $[H_2O_2]$ = 147 mM) and 98% after 6hrs (UVdose = 17.4 kwh/L, $[Fe^{3+}]$ = 0.1 mM, [Oxalate] = 0.6 mM, $[H_2O_2]$ = 29.4 mM), respectively. We improved the reproduction system with addition of UV light to modified Fenton reaction by increasing reduction rate of $Fe^{3+}$ to $Fe^{2+}$. We expect that the system save the treatment time and improve the removal efficiencies. Moreover, we expect the activity of low molecular organic compounds such as acetate or oxalate be effective for maintaining pH condition as neutral. This oxidation system could be an economical, environmental friendly, and practical treatment process since the organic compounds and iron minerals exist in nature soil conditions.

• Membrane Journal
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• v.14 no.4
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• pp.312-319
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• 2004

The porous SiO$_2$-B$_2$O$_3$ membrane was prepared from Si(OC$_2$$H_5$)$_4$-($CH_3$O)$_3$B-C$_2$$H_5$OH-$H_2O$ system by sol-gel method. In order to investigate the characteristics of this membrane, we examined that using BET, IR spectrophotometer, X-ray diffractometer, SEM and TEM. At $700^{\circ}C$, the surface area of SiO$_2$-B$_2$O$_3$ membrane was 354.398 $m^2$/, the median pore diameter was 0.0048 ${\mu}{\textrm}{m}$, and the particle size of SiO$_2$-B$_2$O$_3$ membrane was 7 nm. The separation properties of the gas mixture ($H_2$/$N_2$) through the SiO$_2$-B$_2$O$_3$ membrane was studied as a function of pressure. The real separation factor($\alpha$) of SiO$_2$-B$_2$O$_3$ membrane for $H_2$/$N_2$ gas mixture was 4.68 at 155.15 cmHg and $25^{\circ}C$. The real separation factor($\alpha$), head separation factor($\beta$) and tail separation factor((equation omitted)) were increased as the pressure of permeation cell increased.

• Journal of Sensor Science and Technology
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• v.24 no.1
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• pp.41-46
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• 2015

In this work, pure hierarchical ZnO structure was prepared using a simple hydrothermal method, and Ag nanoparticles doped hierarchical ZnO structure was synthesized uniformly through photochemical route. The reduced graphene oxide (rGO) has been synthesized by typical Hummer's method and reduced by hydrazine. Prepared Ag/ZnO nanostructures are uniformly dispersed on the surface of rGO sheets using ultrasonication process. The synthesized samples were characterized by SEM, TEM, EDS, XRD and PL spectra. The average size of prepared ZnO microspheres was around $2{\sim}3{\mu}m$ and showed highly uniform. The average size of doped-Ag nanoparticles was 50 nm and decorated into ZnO/rGO network. The $C_2H_2$ gas sensing properties of as-prepared products were investigated using resistivity-type gas sensor. Ag/ZnO-rGO based sensors exhibited good performances for $C_2H_2$ gas in comparison with the Ag/ZnO. The $C_2H_2$ sensor based on Ag/ZnO-rGO had linear response property from 3~1000 ppm of $C_2H_2$ concentration at working temperature of $200^{\circ}C$. The response values with 100 ppm $C_2H_2$ at $200^{\circ}C$ were 22% and 78% for Ag/ZnO and Ag/ZnO-rGO, respectively. In additions, the sensor still shows high sensitivity and quick response/recovery to $C_2H_2$ under high relative humidity conditions. Moreover, the device shows excellent selectivity towards to $C_2H_2$ gas at optimal working temperature of $200^{\circ}C$.

• Industry Promotion Research
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• v.3 no.2
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• pp.1-8
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• 2018

In this study, the reaction mechanism of ethane and the reaction rate equation suitable for hydrocarbon reforming were studied. Through the reaction mechanism analysis, it was confirmed that three reactions (CO2 + H2, C2H6 + H2, C2H6 + H2O) proceed during the reforming reaction of ethane, each reaction rate (CO2+H2($r=3.42{\times}10-5molgcat.-1\;s-1$), C2H6+H2($r=3.18{\times}10-5mol\;gcat.-1s-1$), C2H6+H2O($r=1.84{\times}10-5mol\;gcat.-1s-1$)) was determined. It was confirmed that the C2H6 + H2O reaction was a rate determining step (RDS). And the reaction equation of this reaction can be expressed as r = kS * (KAKBPC2H6PH2O) / (1 + KAPC2H6 + KBPH2O) (KA = 2.052, KB = 6.384, $kS=0.189{\times}10-2$) through the Langmuir-Hinshelwood model. The obtained equation was compared with the derived power rate law without regard to the reaction mechanism and the power rate law was relatively similar fitting in the narrow concentration change region (about 2.5-4% of ethane, about 60-75% of water) It was confirmed that the LH model reaction equation based on the reaction mechanism shows a similar value to the experimental value in the wide concentration change region.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.317-322
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• 2016

While PFOS sodium salt ($C_8F_{17}SO_3Na$) was not degraded by microorganisms for 28 days, the 4 alternatives were biodegraded at the rates of 21.6% for $C_{25}F_{17}H_{32}S_3O_{13}Na_3$, 20.5% for $C_{15}F_9H_{21}S_2O_8Na_2$, 15.8% for $C_{23}F_{18}H_{28}S_2O_8Na_2$ and 6.4% for $C_{17}F_9H_{25}S_2O_8Na_2$, respectively. The acute toxicity test using Daphnia magna was conducted for 48 hours, the half effective concentration ($EC_{50}$) of PFOS sodium salt ($C_8F_{17}SO_3Na$) was evaluated in 54.5 mg/L. While the 4 alternatives did not show any effect at 500.0 mg/L. The surface tension of the PFOS salt ($C_8F_{17}SO_3Na$) is 46.2 mN/m at a concentration of 500.0 mg/L. While the surface tension of the 4 alternatives was found to be superior to PFOS sodium salt ($C_8F_{17}SO_3Na$). The surface tension of $C_{23}F_{18}H_{28}S_2O_8Na_2$ (20.9 mN/m) has the lowest, followed by $C_{15}F_9H_{21}S_2O_8Na_2$ (23.4 mN/m), $C_{17}F_9H_{25}S_2O_8Na_2$ (27.3 mN/m), $C_{25}F_{17}H_{32}S_3O_{13}Na_3$ (28.2 mN/m). The four kinds of alternatives ($C_{15}F_9H_{21}S_2O_8Na_2$, $C_{17}F_9H_{25}S_2O_8Na_2$, $C_{23}F_{18}H_{28}S_2O_8Na_2$, $C_{25}F_{17}H_{32}S_3O_{13}Na_3$) were found to be superior to PFOS sodium salt ($C_8F_{17}SO_3Na$) in terms of biodegradation, Daphnia sp. acute toxicity and surface tension, and thus they were considered applicable as PFOS alternatives. Especially biodegradation rate of $C_{15}F_9H_{21}S_2O_8Na_2$, $C_{23}F_{18}H_{28}S_2O_8Na_2$ and $C_{25}F_{17}H_{32}S_3O_{13}Na_3$ was relatively high as 15.8~21.6%, and Daphnia sp. acute toxicity and surface tension were considerably superior (surface tension 39~55%) to PFOS sodium salt. Therefore, these alternatives are considered to be available as an alternative of PFOS.

• Korean Journal of Metals and Materials
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• v.48 no.12
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• pp.1084-1089
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• 2010

This study elucidates the formation mechanism of SnO plate observed during the precipitation reaction of a $SnCl_2$ aqueous solution. $Sn_{21}Cl_{16}(OH)_{14}O_6$ and $Sn_6O_4(OH)_4$ precipitates was formed at pH=3~5 and at pH=11, respectively. When the pH was in the range of 11.5~12.5, the $Sn_6O_4(OH)_4$ precipitates dissolved into $HSnO_2{^-}[Sn_6O_4(OH)_4+4OH^-={6HSnO_2{^-}+2H^+]$ and dissolved $HSnO_2{^-}$ ions reprecipitated to SnO plate $[HSnO_2{^-}+H^+=SnO+H_2O]$. The $Sn_6O_4(OH)_4$ precipitates completely transformed into SnO plate through a repeated process of dissolution-precipitation in the range of pH=11.5~12.5.

• Analytical Science and Technology
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• v.14 no.1
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• pp.15-20
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• 2001

Photocatalytic $TiO_2$ films were prepared by anodic oxidation at 180 V and their structural difference caused by oxidation conditions was studies. The microstructure of $TiO_2$ films in $H_2SO_4$ and $H_2SO_4/H_2O_2$ solution was mixed type of rutile and anatase. However, the $TiO_2$ layer formed in $H_2SO_4/H_3PO_4$ and $H_2SO_4/H_3PO_4/H_2O_2$ mixture was mostly anatase type. All $TiO_2$ films prepared by anodic oxidation exhibited photocatalytic properties. The photocatalytic degradation of aniline blue was first order reaction with similar rate constants at all oxidative conditions examined in this work.

• Korean Journal of Metals and Materials
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• v.50 no.10
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• pp.769-774
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• 2012

Mg-x wt% $Fe_2O_3-y$ wt% Ni samples were prepared by reactive mechanical grinding in a planetary ball mill, and their hydrogen-storage properties were investigated and compared. Activations of $Mg-5Fe_2O_3-5Ni$ was completed after one hydriding (under 12 bar $H_2$) - dehydriding (in vacuum) cycle at 593 K. At n = 2, $Mg-5Fe_2O_3-5Ni$ absorbed 3.43 wt% H for 5 min, 3.57 wt% H for 10 min, 3.76 wt% H for 20 min, and 3.98 wt% H for 60 min. Activated $Mg-10Fe_2O_3$ had the highest hydriding rate, absorbing 2.99 wt% H for 2.5 min, 4.86 wt% H for 10 min, and 5.54 wt% H for 60 min at 593 K under 12 bar $H_2$. Activated $Mg-10Fe_2O_3-5Ni$ had the highest dehydriding rate, desorbing 1.31 wt% H for 10 min, 2.91 wt% H for 30 min, and 3.83 wt% H for 60 min at 593 K under 1.0 bar $H_2$.