• Journal of Microbiology
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• v.33 no.4
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• pp.339-343
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• 1995

We isolated a 10 kb Bam HI fragment originated from the chromosome of a $H_2O$$^2$-resistant mutant strain of Streptomyces coelicolor, which confer $H_2O$$^2$-resistance to S. lividance upon transformation. Among various subclones ot 10kb Bam HI fragment tested for their $H_2O$$^2$-resistant phenotype in S. lividans, a subclone containing 5.2 kb Bam HI-BglII fragment was found to be responsible for $H_2O$$^2$-resistance. The plasmid containing this 5.2 kb fragment was then transformed into S. coellicolor A3(2) at early and tested for their phenotype of $H_2O$$^2$-resistance and the change in various enzymes whose activity can be stained in the gel. We found out that the 5.2 kb insert DNA conferred $H_2O$$^2$-resisstance in S. coelicolor A3(2) at early phase of cell growth. The presence of this DNA also resulted in higher level of peroxidase compared with the wild type cell containing parental vector (pIJ702) only. Esterase activity was also higher in this clone. However, alcohol dehydrogenase activity decreased compared with the wild type. These results suggest that the presence of a gene in 5.2 kb BamHI-BglII DNA fragment causes multiple changes in S. coelicolor related to its response against hydrogen peroxide. The result also implies that not only peroxidase but also esterase may function in the defencse meahsnism agianst $H_2O$$^2$-.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.292-296
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• 2024

In this study, Iron (III) oxide-hydroxide (δ-FeOOH) was successfully synthesized using hydrogen peroxide (H₂O₂) as an oxidizing agent. The synthesis of δ-FeOOH was carried out by controlling the amount of H₂O₂, and pure δ-FeOOH was successfully synthesized in ranges from 0.2 mL to 0.6 mL of H₂O₂. The size of the synthesized δ-FeOOH particles was compared by controlling the amount of oxidant H₂O₂. The average particle size of the synthesized pure δ-FeOOH particles increased from 875.1 nm to 897.2 nm as the amount of H₂O₂ was increased. The optical properties of δ-FeOOH synthesized under these specific conditions were investigated. All δ-FeOOH showed a similar trend of increasing and decreasing light absorption from 800 nm to 400 nm, although there was a slight difference in the amount of light absorption, with the largest amount of light absorption at 410 nm. The band gap energy of δ-FeOOH through the Tauc plot method was about 2.1~2.2 eV when H₂O₂ was 0.2~1.4mL. With a sufficient small particle size, simple control of that particle size, and a small band gap energy enough to absorb light in the visible spectrum, δ-FeOOH could be useful in a variety of applications, including photoelectrochemistry and battery electrodes.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.103-111
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• 2000

Ozonation and advanced oxidation($H_2O_2/O_3$) process were investigated under various experimental conditions to improve the efficiency of biological filter used for the treatment of recycled wastewater from aquaculture. Ammonia removal followed the first-order reaction whose reaction rate constant(k) was $2.0{\times}10^{-2}min^{-1}$ in ozonation. The ammonia removal rate increased according as the bicarbonate alkalinity is increased. About 46% $NH_3$ was oxidized by ozone at 200 mg/L as $CaCO_3$. When alkalinity existed in wastewater, ammonia removal rate by advanced oxidation was very low due to the inhibition effect of bicarbonate. However, when initial pH was adjusted to about 8.2 by 0.1 N KOH, ammonia removal rate was improved higher than that by ozonation. Especially. ammonia removal rate was the highest at $H_2O_2/O_3$ of 0.25 and about 90% of ammonia was removed in 30 min at this ratio as pH was maintained over 9. In the case of wastewater containing ammonia and organic constituents, ammonia removal efficiency by both ozonation and advanced oxidation decreased seriously because organic constituents consumed the oxidant faster than ammonia. In addition the optimal $H_2O_2/O_3$ ratio was changed. Like ammonia removal, DOC(dissolved organic carbon) increased for first 10 min and then decreased slowly because the particulate organic constituents were oxidized rapidly and then produce DOC. Even when the ammonia concentration by twice, oxidation of DOC was not retarded.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.8-13
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• 2010

Bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE) were obtained by a polymerization reaction of epichlorohydrin (ECH) with bisphenol A (BPA) or bisphenol F (BPF). These compounds are commonly used as monomers or additives such as a polymerization stabilizer and a hydrochloric acid scavenger of epoxy resin, polyvinyl chloride (PVC)-containing organosols and polyester lacquers, that are applied to the internal surface of most canned foods to impart chemical resistance. The unreacted BADGE, BFDGE and their reaction products migrating from epoxy resin, PVC-containing organosol and/or polyester lacquer-based food packaging materials into the foods have recently become an issue of great concern because of increased customer demand for safety. This study was conducted to develop a rapid and sensitive simultaneous analysis method based on HPLC/FLD and HPLC/APCI-mass and to evaluate the concentration of BADGE, BFDGE and their metabolites, BADGE $H_2O$, BADGE $2H_2O$, BADGE HCl, BADGE 2HCl, BADGE HCl $H_2O$, BFDGE $H_2O$, BFDGE $2H_2O$, BFDGE HCl, BFDGE 2HCl and BFDGE HCl $H_2O$ for 133 canned food samples. The method provided a linearity of 0.9997-0.9999, a limit of detection of $0.01-0.13\;{\mu}g/mL$, a limit of quantitation of $0.03-0.44\;{\mu}g/mL$ and a recovery (%) of 85.64-118.18. The number of samples containing BADGE, BFDGE or their metabolites were: 28/133 (21.1%), with levels of 0.400-0.888 mg/kg being observed for aqueous foods (19/133) and 0.093-0.506 mg/kg being observed for oily foods (9/133).

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1177-1181
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• 2014

A 2D grid-like (4, 4)-connected topology coordination polymer, $[Co(BTA)_2(H_2O)_2]_n$ (1), where HBTA = 2-(1H-benzotriazol-1-yl)acetic acid, has been synthesized by hydrothermal method and characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and surface photovoltage spectroscopy (SPS). X-ray diffraction analyses indicated that 1 displays octahedral metal centers with secondary building units (SBUs) [$Co(BTA)_2(H_2O)_2$] bridged by the $BTA^-$ ligands. In the crystal, the 2D supramolecular architecture is further supported by $O-H{\cdots}O$, $O-H{\cdots}N$, $C-H{\cdots}O$ hydrogen bonds and ${\pi}{\cdots}{\pi}$ stacking interactions. The SPS of polymer 1 indicates that there are positive response bands in the range of 300-600 nm showing photo-electric conversion properties. There are good relationships between SPS and UV-Vis spectra.

• Molecules and Cells
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• v.39 no.1
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• pp.31-39
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• 2016

The peroxiredoxins (Prxs) constitute a very large and highly conserved family of thiol-based peroxidases that has been discovered only very recently. We consider here these enzymes through the angle of their discovery, and of some features of their molecular and physiological functions, focusing on complex phenotypes of the gene mutations of the 2-Cys Prxs subtype in yeast. As scavengers of the low levels of $H_2O_2$ and as $H_2O_2$ receptors and transducers, 2-Cys Prxs have been highly instrumental to understand the biological impact of $H_2O_2$, and in particular its signaling function. 2-Cys Prxs can also become potent chaperone holdases, and unveiling the in vivo relevance of this function, which is still not established, should further increase our knowledge of the biological impact and toxicity of $H_2O_2$. The diverse molecular functions of 2-Cys Prx explain the often-hard task of relating them to peroxiredoxin genes phenotypes, which underscores the pleiotropic physiological role of these enzymes and complex biologic impact of $H_2O_2$.

• Membrane Journal
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• v.4 no.3
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• pp.152-162
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• 1994

The photodegradation efficiency of formic acid on $TiO_2$ photocatalytic membranes was investigated. A new titania membrane reactors for purification of water combining microfiltration with photocatalytic degradation of organic compounds were developed. Titania membrane tubes(average pore size of $0.2\mu m$) were prepared by the slip casting, and porous thin films of $TiO_2$ were formed on the tube surface by the sol-gel process to increase the surface area, and consequently to increase photodegradation efficiency of organic compounds. The UV light with the wavelength of 365 nm was used as a light source for photocatalytic reactions. The photodegradation efficiency of the organic compounds was strongly dependent on the flux of the solution, the microstructure of the membrane (sol pH), and the amount of $O_2$ supplied. The effects of the primary oxidant such as $H_2O_2$ and dopants such as $Nb_2O_5$ on the photodegradation efficiency were also investigated. The results showed that more than 80% of formic acid could be degraded using membrane coated with a $TiO_2$ sol of pH 1.45. The photodegradation efficiency could be improved by about 20% when adding $H_2O_2$ in feed solution or doping $TiO_2$ membranes with $Fe_2O_3$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.3
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• pp.122-126
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• 2012

The properties of Al-doped ZnO (AZO) films were investigated as a function of $H_2/(Ar+H_2)$ gas ratio using an AZO (2 wt% $Al_2O_3$) ceramic target in a radio frequency (RF) magnetron sputtering system. The deposition process was done at $200^{\circ}C$ and in $2{\times}10^{-2}$ Torr working pressure and with various ratios of $H_2/(Ar+H_2)$ gas. During the AZO film deposition process, partial $H_2$ gas affected the AZO film characteristics. The electron resistivity (${\sim}9.21{\times}10^{-4}\;{\Omega}cm$) was lowest and mobility (${\sim}17.8\;cm^2/Vs$) was highest in AZO films when the $H_2/(Ar+H_2)$ gas ratio was 2.5 %. When the $H_2/(Ar+H_2)$ gas ratio was increased above 2.5 %, the electron resistivity increased and mobility decreased with increasing $H_2/(Ar+H_2)$ gas ratio in AZO films. The carrier concentration increased with increasing $H_2/(Ar+H_2)$ gas ratio from 0 % to 7.5 %. This phenomenon was explained by reaction of hydrogen and oxygen and additional formation of oxygen vacancy. The average optical transmission in the visible light wavelength region over 90 % and an orientation of the deposition was [002] orientation for AZO films grown with all $H_2/(Ar+H_2)$ gas ratios.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.239-239
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• 2011

최근에 감지막의 pH 감지특성을 평가하기 위해 electrolyte insulator semiconductor (EIS) 구조가 유용하게 이용되고 있다. EIS는 CMOS공정과 호환이 가능하고 구조가 간단하며 pH 변화에 반응속도가 빠르다는 장점을 가지고 있다. EIS 구조를 갖는 pH 센서의 동작 메커니즘은 pH 용액의 수소이온이 감지막의 표면에서 표면전위를 변화시키는 것에 기인한다. pH 감지막으로는 높은 유전율과 안정성이 뛰어난 high-k 물질이 많이 연구되고 있다. 그 중 high-k 물질인 ZrO2은 낮은 열전도도, 산성에서 알칼리성 영역까지의 넓은 화학안정성을 가지며 낮은 열 팽창성, 높은 유전상수 등 우수한 특성을 가지고 있다. 본 실험은 SiO2/ZrO2를 적층한 EIS 소자를 제작하여 열처리에 따른 전기적 특성과 pH 감지 특성을 평가해 보았다. EIS 적층막으로 사용된 SiO2는 실리콘과 high-k 감지막 사이의 계면상태를 양호하게 유지시키기 위한 완충막으로 성장되었다. 후속열처리는 rapid thermal annealing (RTA) 시스템을 이용하여 750$^{\circ}C$, 850$^{\circ}C$, 950$^{\circ}C$로 H2/N2 분위기에서 30초 동안 실시하였다. RTA 열처리 온도가 증가할수록 높은 pH 감지특성이 보였으며 hysteresis 현상과 drift 효과와 같은 non ideal 효과에 강한 immunity가 있는 것을 확인하였다. 결론적으로 SiO2/ZrO2 적층구조를 갖는 EIS는 RTA 950$^{\circ}C$ 열처리를 실시하였을 때 우수한 EIS pH 센서를 제작할 수 있을 것으로 기대된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1057-1061
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• 2007

In this study, we investigated the properties of ZnO thin films prepared by layer-by-layer method in RF magnetron sputtering system using AlAs and ZnO targets. Effects of $H_2O_2$ dip prior to thermal treatment were studied as well. Either n-type or p-type films were observed in our study depending on the annealing conditions. It thus indicates the feasibility of arbitrarily modifying the conductivity type. At the same time, it also implies the thermal instabilities of the film properties. Property measurements after stressing the films up to 144 hours showed that thermal variations of properties nay be suppressed by pre-treatment in 30% $H_2O_2$ for 1 min.