• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집
• /
• pp.281-283
• /
• 2001

Bi$_2$Sr$_2$CuO$\_$x/(Bi-2201) thin films were fabricated layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to SrBi$_2$O$_4$ by in-situ anneal.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.119-121
• /
• 2002

$Bi_2Sr_2CuO_x$ thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method, 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.280-280
• /
• 2013

In green plants, energy generation is accomplished through light-harvesting photosystem, which utilize abundant visible light and multi-stepwise redox reaction to oxidize water and reduce NADP+, transferring electrons efficiently with active cofactors1. Inspired by natural photosynthesis, artificial solar water-splitting devices are being designed variously. However, the several approaches involving immobilization2, conjugation3, and surface modification4 still have limitations. We have made artificial photosynthesis templates by self-assembling tyrosine-based peptide to mimick photosystem II. Porphyrin sensitizer absorbing blue light strongly was conjugated with the templates and they were hybridized with cobalt oxide through the reduction of cobalt ions in an aqueous solution. The formation of hybrid templates was characterized using TEM, and their water oxidation performance was measured by fluorescence oxygen probe. Our results suggest that the bio-templated assembly of functional compounds has a great potential for artificial photosynthesis.

• Molecules and Cells
• /
• 제39권1호
• /
• pp.1-5
• /
• 2016

Peroxiredoxins (Prxs) are a very large and highly conserved family of peroxidases that reduce peroxides, with a conserved cysteine residue, designated the "peroxidatic" Cys ($C_P$) serving as the site of oxidation by peroxides (Hall et al., 2011; Rhee et al., 2012). Peroxides oxidize the $C_P$-SH to cysteine sulfenic acid ($C_P$-SOH), which then reacts with another cysteine residue, named the "resolving" Cys ($C_R$) to form a disulfide that is subsequently reduced by an appropriate electron donor to complete a catalytic cycle. This overview summarizes the status of studies on Prxs and relates the following 10 minireviews.

• Preventive Nutrition and Food Science
• /
• 제1권1호
• /
• pp.93-98
• /
• 1996

Lipopretein(a)[Lp(a)] is a macromolecular complex found in human plasma that combines structural elements composed of LDL and apo(a), and that is associated with premature coronary heart disease and stroke. In this study, various samples which consisted of normal and abnormal LDL and LP(a) were selected for compar-ison. The above samples were incubated with copper in order to oxidize and to compare atheroma formation, in vitro and free radical formation of Lp(a) was decreased compared to purified LDl. And LDL or Lp(a) from a 40 year old donor was higher in the free radical formation than that fro, a 20 years old donor. In order to investigate the macrophage foam cell formation, oxidized LDL of Lp(a) was incubated with human monocyte derived macrophage(HMDM). Oxidized samples enhanced on acceptability f foam cell formation by HMDM were compared to the control group. Also, structural change of LDL and Lp(a) against oxidation times were found from HPLC mapping.

• Bulletin of the Korean Chemical Society
• /
• 제22권7호
• /
• pp.748-752
• /
• 2001

Alkanethiols (CH3(CH2)n-1SH) based self-assembled monolayers (SAMs) on the clean copper surfaces have been examined for n = 4, 8, and 16. Using X-ray photoelectron spectroscopy (XPS) and contact angle analysis, it is found that alkanethiolate monolayers similar to those on gold are formed on clean copper surfaces. The monolayers are stable in air up to about 140 $^{\circ}C.$ Above 160 $^{\circ}C$ the monolayers begin to desorb through the oxidation reaction of the thiolate to sulfonate, with the alkyl chains remaining intact. Following this desorption step, the copper surface has begun to oxidize to CuO at about 180 $^{\circ}C$.

• Membrane and Water Treatment
• /
• 제10권4호
• /
• pp.299-305
• /
• 2019

Managed aquifer recharge (MAR) systems are gaining interest as an alternative to conventional water resources. However, when the water recovered in MAR systems, dissolved iron and manganese species may easily oxidize and they cause well screen clogging or require abandonment of extraction wells. In this study, both oxic and anoxic conditions were analyzed to verify the feasibility of the membrane filtration performance under various solution chemistries. The fouling mechanisms of the metal ions under anoxic conditions were also investigated by employing synthetic wastewater. The fouled membranes were then further analyzed to verify the major causes of inorganic fouling through SEM and XPS. The newly suggested anoxic process refining existing membrane process is expected to provide more precious information about nanofiltration (NF) membrane fouling, especially for demonstrating the potential advantages to chemical-free drinking water production for indirect potable reuse.

• 반도체디스플레이기술학회지
• /
• 제20권2호
• /
• pp.34-42
• /
• 2021

Recent cleaning technologies of mask in extremely ultraviolet semiconductor processes were reviewed, focused on newly developed issues such as particle size determination or hydrocarbon and tin contaminations. In detail, critical particle size was defined and proposed for mask cleaning where nanosized particles and its various shapes would result in surface atomic ratio increase vigorously. A new cleaning model also was proposed with amphoteric behavior of electrolytically ionized water which had already shown excellent particle removing efficiency. Having its non-equilibrium and amphoteric properties, electrolyzed ion water seemed to oxidize contaminant surface selectively in nano-scale and then to lift up oxidized ones from mask surface very effectively. This assumption should be further investigated in future in junction with hydrogen bonding and cluster of water molecules.

• 대한환경공학회지
• /
• 제34권4호
• /
• pp.247-253
• /
• 2012

본 연구는 초음파 공정에서 주파수가 OH 라디칼 생성량에 미치는 영향을 알아보고 OH 라디칼의 생성량이 가장 많은 주파수를 이용하여 As(III) 산화 시 부피의 영향에 대해 알아보았다. 35, 300, 500 kHz 세 주파수의 초음파를 조사 시 생성되는 과산화수소를 측정하였을 때 300 kHz에서 과산화수소의 cavitation yield 가 가장 크게 나타났다. 주파수 300 kHz의 초음파를 이용하여 As(III) 용액을 4가지 부피(334, 690, 1,046, 1,401 mL)에 대해 산화시킨 결과, 부피가 증가할수록 반응 속도 상수는 감소하였다. 그러나 As(III)의 cavitation yield는 작은 부피에서는 시간이 지남에 따라 값이 감소하였으나 큰 부피에서는 시간이 지나도 값이 유지되거나 오히려 증가하는 결과를 보였다. 초음파 공정에서 As(III)를 산화시킬 때 짧은 시간 내에 일정 농도 이하가 되기 위해서는 반응 속도 상수 결과에 따라 작은 부피에서 산화시키는 것이 유리하다. 반면에 큰 부피에서 오랫동안 산화시킨다면 As(III)의 cavitation yield 결과에 따라 소비 에너지 대비 많은 양(mass)의 As(III)를 산화시킬 수 있기 때문에 출력밀도가 낮음에도 불구하고 적용 가능성이 높다는 것을 확인하였다.

• Journal of Mechanical Science and Technology
• /
• 제20권1호
• /
• pp.1-12
• /
• 2006

This work reviews the effects of catalyst formulation and exhaust gas composition on soot oxidation in CDPF (Catalytic Diesel Particulate Filter). DOC's (Diesel Oxidation Catalysts) have been loaded with Pt catalyst (Pt/$Al_{2}O_3$) for reduction of HC and CO. Recent CDPF's are coated with the Pt catalyst as well as additives like Mo, V, Ce, Co, Fe, La, Au, or Zr for the promotion of soot oxidation. Alkali (K, Na, Cs, Li) doping of metal catalyst tends to increase the activity of the catalysts in soot combustion. Effects of coexistence components are very important in the catalytic reaction of the soot. The soot oxidation rate of a few catalysts are improved by water vapor and NOx in the ambient. There are only a few reports available on the mechanism of the PM (particulate matter) oxidation on the catalysts. The mechanism of PM oxidation in the catalytic systems that meet new emission regulations of diesel engines has yet to be investigated. Future research will focus on catalysts that can not only oxidize PM at low temperature, but also reduce NOx, continuously self-cleaning diesel particulate filters, and selective catalysts for NOx reduction.