• Ocean and Polar Research
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• 제25권1호
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• pp.21-30
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• 2003

Seasonal fluctuations of physico-chemical and biological aspects of the environment were studied in Vladivostok harbour (Golden Horn Bay, the East Sea/Sea of Japan). The benthic community structure was described with a focus on size-spectra (bacteria, meio- and macrofauna) related with the chemical environment and chemical fluxes in sediment and to reveal their possible ecological role in the process of bioremediation of the environment. Samples from two sites with different concentrations of heavy metals (Fe, Zn, Cu, Pb, Mn, Cr, Ni Cd, Co) and petroleum hydrocarbon were assessed by a number of methods. These included plate counts of culturable bacteria, observation through a scanning electron (SEM) and transmission electron microscope (TEM). These approaches were complemented with microscopic assessments of the diversity of the benthic community. The specific communities had a limited number of species, tolerant to abnormally high levels of toxic compounds. The dominant species were presented by several sho.1-lived small polychaetes (Capitella capitata) and nematodes (Oncholaimium ramosum). The highest population density was recorded in microbenthos, in various diatoms, various physiological groups of bacteria which participate in biomineralization: marine heterotrophic bacteria, which oxidized oil, black oil in addition to groups resistant to heavy metals. They have the entire set of mechanisms for neutralizing the negative effect of those compounds, forming the detrital food web and biogeochemical circulation of material in sediments, which results in the biological self-recycling of sea basins. Macro- and meiobenthic organisms were more sensitive to a greater extent of $H_2S$ and petroleum hydrocarbons than to metal content, but the within-site rankings were the same as those achieved for microbiological analyses.

• 한국환경과학회지
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• 제27권9호
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• pp.763-770
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• 2018

Bioremediation in situ is heavily dependent on the oxygenic environment which would privide the dwelling microorganism with sufficient oxygen. The situation could be easily resolved with supply of an Oxygen Releasing Compound (ORC). In this paper we prepared that sort of material out of oyster shell powder (mostly calcium carbonate) that prevails every shore areas of the country. We used two different oxidizing methods in the first step of the whole manufacturing process-conventional heating in a furnace and an ultrasound generator to obtain calcium oxide. Then that calcium oxide was further oxidized into calcium peroxide which may release oxygen under a moisturized condition. The oxygen releasing experiments were run to test the performance of our products, and to determine the gas kinetics during the experiments. Interestingly, calcium peroxide derived from ultrasound treatment was much more energy-effective as ORC than that from furnace heating although the heat derived process was better than that of ultrasound in terms of oxygen content and its releasing rate. We also found that most of the data collected from the gas releasing experiments fairly supported an ordinary $1^{st}$ order kinetics to oxygen concentration, which shaped a sharp discharge of oxygen at the very early moment of each test.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.166-172
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• 2013

본 연구는 압연공정에서 발생하는 폐수 중에 함유되어있는 난분해성 COD 물질을 $80{\mu}m$ 두께의 극세사 형태로 제조된 Cu-Zn 금속합금의 산화 작용으로 인하여 발생하는 OH 라디칼을 이용하여 처리하는 방법에 관한 기초 연구이다. OH 라디칼은 유기화합물(RH) 속에 포함된 수소를 수소추출반응(H Abstraction) 또는 탄소와 탄소(C-C)의 불포화 결합에 첨가됨으로써 빠르고 비 선택적인 반응을 수행하는 것으로 알려진 것처럼 난 분해성 유기화합물의 처리에 효과적인 것으로 나타났다. 금속합금 반응 물질은 극세사 형태로 표면적이 넓어서 1회 처리만으로도 수용액의 pH를 평형에 도달하게 하여서 반응 효율성이 높은 것으로 나타났다. COD처리 효율은 중성 pH에 가까운 pH 7, pH 6에서 최고치를 보였으며 산성분위기인 pH 5이하 및 알칼리성 분위기인 pH 8이상에서는 낮은 효율을 보였다. 실제 압연 폐수의 응집 침전을 이용한 COD 처리에서도 redox 반응장치의 유무에 따라 2배 이상의 처리효율의 차이를 보였다.

• The Journal of Advanced Prosthodontics
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• 제1권2호
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• pp.91-96
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• 2009

STATEMENT OF PROBLEM. The aim of this study was to study the effects of various surface treatments to a titanium surface on the expression of Runx2 in vitro. MATERIAL AND METHODS. Human Osteosarcoma TE-85 cells were cultured on machined, sandblasted, or anodic oxidized cpTi discs. At various times of incubation, the cells were collected and then processed for the analysis of mRNA expression of Runx2 using reverse transcription-PCR. RESULTS. The expression pattern of Runx2 mRNA was differed according to the types of surface treatment. When the cells were cultured on the untreated control culture plates, the gene expression of Runx2 was not increased during the experiments. In the case of that the cells were cultured on the machined cpTI discs, the expression level was intermediate at the first day, but increased constitutively to day 5. In cells on sandblasted cpTi discs, the expression level was highest in the first day sample and the level was maintained to 5 days. In cells on anodized cpTi discs, the expression level increased rapidly to 3 days, but decreased slightly in the 5-th day sample. CONCLUSION. Different surface treatments may contribute to the regulation of osteoblast function by influencing the level of gene expression of key osteogenic factors.

• 대한치과보철학회지
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• 제45권6호
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• pp.795-804
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• 2007

Statement of problem. Nano-scale calcium-phosphate coating on the anodizing titanium surface using ion beam-assisted deposition (IBAD) has been recently introduced to improve the early osseointegration. However, not much is known about their surface characteristics that have influence on tissue-implant interaction. Purpose. This study was aimed to investigate microtopography, surface roughness, surface composition, and wettability of the titanium surface modified by the anodic oxidation and calcium phosphate coating using IBAD. Material and methods. Commercially pure titanium disks were used as substrates. The experiment was composed of four groups. Group MA surfaces represented machined surface. Group AN was anodized surface. Group CaP/AN was anodic oxidized and calcium phosphate coated surfaces. Group SLA surfaces were sandblasted and acid etched surfaces. The prepared titanium discs were examined as follows. The surface morphology of the discs was examined using SEM. The surface roughness was measured by a confocal laser scanning microscope. Phase components were analyzed using thin-film x-ray diffraction. Wettability analyses were performed by contact angle measurement with distilled water, formamide, bromonaphtalene and surface free energy calculation. Results. (1) The four groups showed specific microtopography respectively. Anodized and calcium phosphate coated specimens showed multiple micropores and tiny homogeneously distributed crystalline particles. (2) The order of surface roughness values were, from the lowest to the highest, machined group, anodized group, anodized and calcium phosphate deposited group, and sandblasted and acid etched group. (3) Anodized and calcium phosphate deposited group was found to have titanium and titanium anatase oxides and exhibited calcium phosphorous crystalline structures. (4) Surface wettability was increased in the order of calcium phosphate deposited group, machined group, anodized group, sandblasted and acid etched group. Conclusion. After ion beam-assisted deposition on anodized titanium, the microporous structure remained on the surface and many small calcium phosphorous crystals were formed on the porous surface. Nanoscale calcium phosphorous deposition induced roughness on the microporous surface but hydrophobicity was increased.

• Advances in environmental research
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• 제1권1호
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• pp.37-55
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• 2012

Here we show that perchlorate reduction during pitting corrosion of zero-valent titanium (ZVT) is likely caused by dissolved titanium species, especially Ti(II). Several possible mechanisms were suggested based on the literature and were evaluated based on experimental observations. Direct reduction of perchlorate on the bare metal of the ZVT electrode was thermodynamically infeasible due to the high anodic potential that was applied. Other potential mechanisms were considered such as reduction by small ZVT metal particles released from the electrode and direct reduction on the oxide layer of the electrode where potential was sufficiently reduced by a high ohmic potential drop. However, these mechanisms were not supported by experimental results. The most likely mechanism for perchlorate reduction was that during pitting corrosion, in which ZVT is partially oxidized to form dissolved ions such as Ti(II), which diffuse from the electrode surface and react with perchlorate in solution. This mechanism is supported by measurements of the dissolution valence and the molar ratio of ZVT consumed to perchlorate reduced (${\Delta}Ti(0)/{\Delta}ClO_4{^-}$). The results shown in this study demonstrate that ZVT undergoing pitting corrosion has the capability to chemically reduce perchlorate by producing dissolved Ti(II) and therefore, it has the potential to be applied in treatment systems. On the other hand, the results of this research imply that the application of ZVT undergoing pitting corrosion in treatment systems may not be feasible now due to several factors, including material and electricity costs and possible chloride oxidation.

• The Journal of Advanced Prosthodontics
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• 제1권1호
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• pp.10-18
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• 2009

STATEMENT OF PROBLEM. Despite an improved bone reactions of Mg-incorporated implants in the animals, little yet has been carried out by the experimental investigations in functional loading conditions. PURPOSE. This study investigated the clinical and histologic parameters of osseointegrated Mg-incorporated implants in early loading conditions. MATERIAL AND METHODS. A total of 36 solid screw implants(diameter 3.75 mm, length 10 mm) were placed in the mandibles of 6 beagle dogs. Test groups included 18 Mg-incorporated implants. Turned titanium implants served as control. Gold crowns were inserted 4 weeks after implant placement and the dogs were immediately put on a food diet. Implants were observed for 10 weeks after loading. Radiographic assessments and stability tests were performed at the time of fixture installation, $2^{nd}$ stage surgery, 4 weeks after loading, and 10 weeks after loading. Histological observations and morphometrical measurements were also performed. RESULTS. Of 36 implants, 33 displayed no discernible mobility, corresponding to successful clinical function. There was no statistically significant difference between test implants and controls in marginal bone levels(P=.46) and RFA values. The mean BIC % in the Mg-implants was $54.5{\pm}8.4%$. The mean BIC % in the turned implant was $45.3{\pm}12.2%$. These differences between the Mg-implant and control implant were statistically significant(P=.005). CONCLUSIONS. The anodized, Mg-incorporated implant demonstrated significantly more bone-to-implant contact(BIC) in early loading conditions. CLINICAL IMPLICATIONS. The results of this study in beagle dogs suggest the possibility of achieving predictable stability of early loaded free-standing dental implants with Mg-incorporated surface.

• 한국식품과학회지
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• 제44권4호
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• pp.472-477
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• 2012

CNT 센서는 산가와의 연계성이 $R^2$>0.96으로 산가의 화학적 측정방법을 대체할 수 있는 유지의 산패도 측정기기로서 적합할 것으로 기대된다. 현재 유탕유의 품질에 대한 국내 법적 기준은 산가와 과산화물가를 기준으로 하고 있지만 일부 유럽국가의 기준인 polar-compounds 25%내외의 규정에 비하여 유지의 상태를 판별하는 데에 변화요구 가능성이 있어 국내규정에 대한 검토가 필요하다. 실험결과에서 산가와 CNT센서, 산가와 polar-compounds간의 높은 연관성을 확인하였으므로, CNT센서를 산가 뿐만 아니라, polar-compounds 측정법을 대신할 수 있는 장치로서 개발도 가능할 것이다. 다만, 식용오일마다 구성성분과 함량이 다르므로 보다 정밀한 유지의 산패도 측정이 가능하기 위해서는 식용유지의 종류별로 데이터베이스를 구축하는 것이 필요하다.

• E2M - 전기 전자와 첨단 소재
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• 제9권1호
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• pp.30-37
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• 1996

Previously, crystallization of a-Si:H films on glass substrates were limited to anneal temperature below 600.deg. C, over 10 hours to avoid glass shrinkage. Our study indicates that the crystallization is strongly influenced by anneal temperature and weakly affected by anneal duration time. Because of the high temperature process and nonconducting substrate requirements for poly-Si TFTs, the employed substrates were limited to quartz, sapphire, and oxidized Si wafer. We report on poly-Si TFT's using high temperature anneal on a Si:H/Mo structures. The metal Mo substrate was stable enough to allow 1000.deg. C anneal. A novel TFT fabrication was achieved by using part of the Mo substrate as drain and source ohmic contact electrode. The as-grown a-Si:H TFT was compared to anneal treated poly-Si TFT'S. Defect induced trap states of TFT's were examined using the thermally stimulated current (TSC) method. In some case, the poly-Si grain boundaries were passivated by hydrogen. A-SI:H and poly-Si TFT characteristics were investigated using an inverted staggered type TFT. The poly -Si films were achieved by various anneal techniques; isothermal, RTA, and excimer laser anneal. The TFT on as grown a-Si:H exhibited a low field effect mobility, transconductance, and high gate threshold voltage. Some films were annealed at temperatures from 200 to >$1000^{\circ}C$ The TFT on poly-Si showed an improved $I_on$$I_off$ ratio of $10_6$, reduced gate threshold voltage, and increased field effect mobility by three orders. Inverter operation was examined to verify logic circuit application using the poly Si TFTs.

• 한국재료학회지
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• 제15권11호
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• pp.711-716
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• 2005

The effects of change in the component of bonding materials in carbon nanotube cathode (CNT-cathode) on field enhancement and field emission characteristics were investigated. The field enhancement factor$\beta$ was dependent on the electrical conductivity of the bonding materials. The use of frit glass as a bonding material showed a higher field enhancement factor and better field emission characteristics than an Ag paste. The reason for why the frit glass showed better field emission characteristics can be summarized as follows. First, a frit glass improves the real aspect ratio of CNTs compared to an Ag paste. Second, the number of CNTs in CNT-cathodes is considerably reduced because the CNTs were extensively oxidized during $390^{\circ}C$ heat treatment in air atmosphere in the case of Ag paste.