• 한국광물학회지
• /
• 제23권2호
• /
• pp.107-115
• /
• 2010

한국원자력연구원 지하처분연구시설의 지하심부에 생존하는 미생물을 이용하여 용존우라늄의 제거 및 광물화에 대한 실험을 실시하였다. 미생물은 철환원박테리아와 황산염환원박테리아로 구분하여 개별적으로 실험을 실시하였으며, 실험 후 X-선 회절분석 및 주사전자현미경을 이용하여 생성광물을 확인하였고 용액상의 농도 변화는 유도결합플라즈마분석기를 이용하여 분석하였다. 철환원박테리아에서는 우라늄과 철이온이 공존할 때, 우라늄보다는 철이온이 선택적으로 환원과정에 참여하였으며, 결과적으로 우라늄의 환원 및 제거가 거의 이루어지지 못하였다. 하지만, 망간이 포함된 조건에서는 상당량의 우라늄 제거 효과가 나타났다. 황산염환원박테리아에서는 철과 망간이 공존할 때, 철이 선택적으로 황과 결합하여 맥키나와이트(FeS)라는 황화광물을 형성하였으며, 망간으로 구성된 황화광물은 만들어지지 않았다. 하지만, 망간이 공존하는 경우에 우라늄의 제거는 훨씬 효과적이었는데, 이는 황화광물에 불순물로 포함된 망간이 우라늄의 흡착 및 포획에 큰 영향을 미치기 때문인 것으로 판단된다.

• 대한수의학회지
• /
• 제36권4호
• /
• pp.809-819
• /
• 1996

This study was conducted to identify the effects of caffeine or combinations of caffeine and iron or vitamin E on the lipid and protein components in the MDBK(Mardin-Darby Bovine Kidney) cells. For the In vitro test, MDBK cells in ${\alpha}$-MEM(Minimum Essential Medium) were divided into 4 treatment groups according to drug types and dosages as follows; the control(group A), group B was treated with 0.3mM caffeine, group C was treated with 0.3mM caffeine and 0.3mM ferric chloride, group D was treated with 0.3mM caffeine and 0.3mM vitamin E. Those groups were further divided into 5 subgroups according to the time lapsed(control, 4hrs, 8hrs, 24hrs and 48hrs lapsed group). The concentrations of the carbonyl group and malondialdehyde(MDA) and the patterns of the SDS-PAGE(Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis) and fatty acid compositions were analyzed to determine the oxidative damages and metabolic changes on the lipid and protein components in the MDBK cells. The results obtained from this study were summarized as follows; 1. The concentrations of carbonyl group and malondialdehyde in MDBK cells of group C were significantly higher(p<0.01) in comparison to the control, and increased according to the time lapsed. But the results of groups B and D were little different in comparison to the group C. 2. As the analytical results of fatty acid compositions in MDBK cells, the proportions of palmitoleic acid and linoleic acid in groups B, C and D were lower in comparison to the control, while the proportion of arachidonic acid in groups B, C and D were significantly higher(p<0.01) in comparison to the control. 3. In order to determine the oxidative damages to the protein in MDBK cells, the patterns of the SDS-PAGE were examined and the patterns of SDS-PAGE in groups C and D were significantly different between 43kd and 200kd of molecular weight.

• 한국환경과학회지
• /
• 제28권10호
• /
• pp.851-861
• /
• 2019

In this study, we performed a sediment elution experiment to evaluate water quality in terms of phosphorus, as influenced by the dissolved oxygen consumed by sediments. Three separate model column treatments, namely, raw, calcined, and sonicated oyster shell powders, were used in this experiment. Essential phosphorus fractions were examined to verify their roles in nutrient release from sediment based on correlation analyses. When treated with calcined or sonicated oyster shell powder, the sediment-water interface became "less anaerobic," thereby producing conditions conducive to partial oxidation and activities of aerobic bacteria. Sediment Oxygen Demand (SOD) was found to be closely correlated with the growth of algae, which confirmed an intermittent input of organic biomass at the sediment surface. SOD was positively correlated with exchangeable and loosely adsorbed phosphorus and organic phosphorus, owing to the accumulation of unbound algal biomass-derived phosphates in sediment, whereas it was negatively correlated with ferric iron-bound phosphorus or calcium fluorapatite-bound phosphorus, which were present in the form of "insoluble" complexes, thereby facilitating the free migration of sulfate-reducing bacteria or limiting the release from complexes, depending on applied local conditions. PCR-denaturing gradient gel electrophoresis revealed that iron-reducing bacteria were the dominant species in control and non-calcined oyster shell columns, whereas certain sulfur-oxidizing bacteria were identified in the column treated with calcined oyster powder.

• 대한화장품학회지
• /
• 제41권4호
• /
• pp.383-389
• /
• 2015

본 연구는 은행 열매 오일의 멜라닌 생성 억제 효과를 확인한 것이다. 은행나무 열매 오일은 DPPH assay와 FRAP assay를 사용하여 라디컬 소거능을 시험하였다. 결과적으로 은행나무 열매 오일은 DMSO를 용매로 0.06% 녹였을 때, DPPH assay에서 9.96% 소거활성을 나타내었고 FRAP는 1.33 mM의 ferric sulfate ($FeSO_4$)를 생성하였다. 은행 열매 오일은 tyrosinase inhibition assay에서 37.72%의 억제력을 가졌고 B16/F10 세포에 멜라닌 생합성 실험을 통해 확인하였다. 은행 오일 0.06%에서 ${\alpha}$-MSH 처리 구에 비해 48.02%의 멜라닌 생성을 억제하였다. Tyrosinase, tyrosinase related protein-1 (TRP-1), tyrosinase related protein-2 (TRP-2), microphthalmia-associated transcription factor (MITF)의 유전자 발현 수준은 control군에 비해 0.04%와 0.06% 농도 군이 크게 감소하였다. 결과적으로 은행 열매 오일 추출물이 멜라닌 생성을 억제하는 효과가 있는 것으로 확인되었다.

• 한국환경과학회지
• /
• 제30권3호
• /
• pp.195-206
• /
• 2021

Contaminated marine sediment is a secondary pollution source in the coastal areas, which can result in increased nutrients concentrations in the overlying water. We analyzed the nutrients release characteristics into overlying water from sediments and the interaction among benthic circulation of nitrogen, phosphorus, iron, and sulfur were investigated in a preset sediment/water column. Profiles of pH, ORP, sulfur, iron, nitrogen, phosphorus pools were determined in the sediment and three different layers of overlying water. Variety types of sulfur in the sediments plays a significant role on nutrients transfer into overlying water. Dissimilatory nitrate reduction and various sulfur species interaction are predominantly embodied by the enhancing effects of sulfide on nitrogen reduction. Contaminant sediment take on high organic matter, which is decomposed by bacteria, as a result promote bacterial sulfate reduction and generate sulfide in the sediment. The sulfur and iron interactions had also influence on phosphorus cycling and released from sediment into overlying water may ensue over the dissolution of ferric iron intercede by iron-reducing bacteria. The nutrients release rate was calculated followed by release rate equation. The results showed that the sediments released large-scale quantity of ammonium nitrogen and phosphate, which are main inner source of overlying water pollution. A mechanical migration of key nutrients such as ammonia and inorganic phosphate was depicted numerically with Fick's diffusion law, which showed a fair agreement to most of the experimental data.

• 한국광물학회:학술대회논문집
• /
• 한국광물학회.한국암석학회 2001년도 공동학술발표회 논문집
• /
• pp.38-39
• /
• 2001

The seasonal changes in pH, Fe, Al and SO$_4$$\^$2-/ contents of acid drainage released from coal mine dumps play a major role in precipitation of metal hydroxides in the Taebaek coal field area, southeastern Korea. Precipitates in the creeks underwent a cycle of the color change showing white, reddish brown and brownish yellow, which depends on geochemical factors of the creek waters. White precipitates consist of Al-sulfate (basaluminite and hydrobasaluminite) and reddish brown ones are composed of ferrihydrite and brownish yellow ones are of schwertmannite. Goethite coprecipitates with ferrihydrite and schwertmannite. Ferrihydrite formed at higher values than pH 5.3 and schwertmannite precipitated below pH 4.3, and goethite formed at the intermediate pH range between the two minerals. With the pH being increased from acid to intermediate regions, Fe is present both as schwertmannite and goethite. From the present observation, the most favorable pH that basauluminte can precipitate is in the range of pH 4.45-5.95. SEM examination of precipitates at stream bottom shows that they basically consist of agglomerates of spheroid and rod-shape bacteria. Bacteria species are remarkably different among bottom precipitates and, to a less extent, there are slightly different chemical compositions even within the same bacteria. The speciation and calculation of the mineral saturation index were made using MINTEQA2. In waters associated with yellowish brown precipitates mainly composed of schwertmannite, So$_4$ species is mostly free So$_4$$\^$2-/ ion with less AlSo$_4$$\^$+/, CaSo$\sub$(aq)/, and MgSo$\sub$4(aq)/. Ferrous iron is present mostly as free Fe$\^$2+/, and FeSo$\sub$4(aq)/ and ferric iron exists predominantly as Fe(OH)$_2$$\^$+/, with less FeSo$\sub$4(aq)/, Fe(OH)$_2$$\^$-/, FeSo$_4$$\^$-/ and Fe$\^$3+/, respectively Al exists as free Al$\^$3+/, AlOH$_2$$\^$-/, (AlSo$_4$)$\^$+/, and Al(So$_4$)$\^$2-/. Fe is generally saturated with respect to hematite, magnetite, and goethite, with nearly saturation with lepidocrocite. Aluminum and sulfate are supersaturated with respect to predominant alunite and less jubanite, and they approach a saturation state with respect to diaspore, gibbsite, boehmite and gypsum. In the case of waters associated with whitish precipitates mainly composed of basaluminite, Al is present as predominant Al$\^$3+/ and Al(SO$_4$)$\^$+/, with less Al(OH)$\^$2+/, Al(OH)$_2$$\^$+/ and Al(SO$_4$)$\^$2-/. According to calculation for the mineral saturation, aluminum and sulfate are greatly supersaturated with respect to basaluminite and alunite. Diaspore is flirty well supersaturated while jubanite, gibbsite, and boehmite are already supersaturated, and gypsum approaches its saturation state. The observation that the only mineral phase we can easily detect in the whitish precipitate is basaluminite suggests that growth rate of alunite is much slower than that of basaluminite. Neutralization of acid mine drainage due to the dilution caused by the dilution effect due to mixing of unpolluted waters prevails over the buffering effect by the dissolution of carbonate or aluminosilicates. The main factors to affect color change are variations in aqueous geochemistry, which are controlled by dilution effect due to rainfall, water mixng from adjacent creeks, and the extent to which water-rock interaction takes place with seasons. pH, Fe, Al and SO$_4$ contents of the creek water are the most important factors leading to color changes in the precipitates. A geochemical cycle showing color variations in the precipitates provides the potential control on acid mine drainage and can be applied as a reclamation tool in a temperate region with four seasons.

• Restorative Dentistry and Endodontics
• /
• 제21권1호
• /
• pp.19-34
• /
• 1996

It has been demonstrated that intracoronal bleaching of pulpless teeth may result in cervical root resorption. Several authors postulated that bleaching agents such as hydrogen peroxide penetrated through the dentinal tubules to damage the surrounding tissues that cause cervical root resorption. The purpose of this study was to suggest on in vitro model for direct determination of hydrogen peroxide penetration through CEJ during nonvital bleaching. In addition, this model permit the quantification of the amount of hydrogen peroxide penetrated during the procedure. Freshly extracted intact premolars, removed for orthodontic reasons were used. Root canal treatment was performed in each tooth. And then the outer surface and crown portion of the teeth was sealed with wax leaving the CEJ. The prepared teeth mounted on the wax laminates were placed in plastic assay tubes containing 1.5ml bidistilled water with their entire root, including the CEJ, submerged in the solution. The teeth were dividied into four groups. Thermo group : thermocatalytic bleaching with superoxol Walk group: walking bleaching with sodium perborate & superoxol Combi group : combination of thermocatalytic & walking bleaching Dw group : walking bleaching with sodium perborate & water The bleaching procedure was performed three times. The bleaching intervals were at 3 days. The hydrogen peroxide present in the assay system was added to ferrous ammonium sulfate resulting in ferric ion release. Upon the addition of potassium thiocyanate a ferrithiocyanate complex results, which absorbs light at the wavelength of 467nm. The radicular penetration of hydrogen peroxide in the four groups was assessed directly using spectrophotometer. The amount of hydrogen peroxide in the samples tested is determined by comparing them with a standard curve generated by known amounts of hydrogen peroxide. The results were obtained as follows : 1. In all experimental groups except the Dw group showed lower penetration amount in day 4 than day 1, there was statistical importance in the difference (P<0.05). 2. After 3rd treatment, Thermo group showed slightly increased value and narrow distribution. Walk group showed much more penetration amount and widely dispersed value. Value of Combi group showed wide distribution without regard to treatment time, but value of Dw group evenly distributed. 3. Thermo group, Walk group and Dw group showed a tendency of increasing penetration amount with increasing treatment times(P<0.01), but Combi group revealed no statistically important differences. 4. Combi group showed the highest degree of penetration. Walk group showed lower penetration than Combi group. Thermo group & Dw group showed lower than Walk group. 5. Cervical root permeability to hydrogen peroxide varied from 0 to 35 %.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2008년도 학술발표회 논문집
• /
• pp.859-863
• /
• 2008

축산폐수, 침출수 등의 고농도 폐수를 생물학적으로 처리할 경우 최종 방류수는 강한 색도를 띠며 고분자량의 유기물질을 다량 함유한다. 이는 생물학적으로 분해하기 어려운 유기성 복합체와 생화학적 반응에 의한 중간생성물로 색도를 띠는 천연유기물질(NOM)을 포함한다. 생물학적 처리수의 색도는 심미적인 불안감, 방류수역의 수질오염 및 공중보건상의 잠재적 위해성을 갖는다. 또한, 수자원 이용측면에서 정수처리공정에서의 약품투입량 증가와 특히, 소독부산물 생성이라는 잠재적 문제점이 뒤따른다. 따라서 이러한 문제점을 해소하기 위한 생물학적 2차 처리수의 후속처리가 요구되며, 실제로 난분해성 유기물과 색도를 제거하기 위한 흡착, 막 분리, 고급산화(AOP) 및 화학적 응집 등의 물리-화학적 공정에 대한 연구가 수행되어왔다. 특히, 화학적 응집은 무기응집제 또는 고분자중합체(Polymer)를 이용하여 콜로이드성 입자와 색도를 띠는 난분해성 유기물을 전기적 불안정화를 유도함으로서 흡착 및 응집과정을 통해 제거하는 공정으로 많은 연구자들에 의해 연구되어왔다. 그러나 난분해성 유기물과 색도제거는 대상원수의 성상과 화학적 특성 등에 따라 각각의 제거효율과 최적 운전조건이 상이하게 나타난다. 화학적 응집공정은 비교적 높은 제거효율을 보이지만, 운전 및 유지관리의 기술적 어려움, 경제적 비효율성 등으로 인하여 적용에 어려움을 겪고 있는 실정이다. 본 논문에서는 생물학적 혐기-호기성 공정에서 방류되는 축산폐수의 2차 처리수를 대상으로 화학적 응집에 의한 색도 및 난분해성 유기물의 제거거동을 고찰하였다. 대상 처리수의 $TCOD_{Cr}$ 농도는 평균 410 mg/L인 반면, $BOD_5$는 7-15 mg/L 범위로 난분해성 유기물을 다량 함유하고 있음을 알 수 있었다. 이에 황산알루미늄(Aluminium sulfate; $Al_2(SO_4){\cdot}14H_2O$)과 염화철(ferric chloride)의 무기응집제를 이용하여 자 테스트(jar test)를 수행한 결과, 동일한 응집제 주입량에서 염화철의 유기물 제거 효율이 높은 것으로 나타났다. 황산알루미늄과 염화철의 경우 각각의 응집제 주입율 5.85mM에서 89%, 7.03mM에서 97.5%의 최대 유기물 제거효율을 보여주었으며, 이 때 최종 pH는 4.0-5.6 범위이었다. 한편, 대상 원수 내의 콜로이드성 입자 또는 용존성 유기물의 작용기(functional group)는 일반적으로 음으로 하전 되어 있어 응집에 의해 잘 제거되지 않는 특성을 가지고 있다. 따라서 과량의 응집제를 주입하여 다가의 양이온성 금속염을 흡착시켜 전기적으로 중화시키고, 생성된 침전성 수화물 내에 포획 또는 여과시켜 제거하게 된다. 이 때, 금속염 수화종의 전하밀도가 응집효율에 영향을 주는 것으로 알려져 있는데, 다가의 양이온은 전기적 이중층(Double layer) 압축에 의한 불안정화를 향상시킬 수 있기 때문에다. 또한, 2가 금속염은 색도유발물질과 흡착하여 humate 또는 fulvate 등의 착화합물(complex)을 형성시켜 응집효율을 향상시킬 수 있다. 따라서 본 연구에서는 생물학적 2차 처리수의 화학적 응집처리에 있어서 알루미늄염 등의 다가이온 첨가가 응집에 미치는 영향을 관찰하고, 후속되는 플록형성 및 침전공정에 의한 제거효율을 비교, 평가함으로써 2차 처리수로부터 난분해성 유기물과 색도를 보다 효과적이고 경제적으로 제거할 수 있는 최적인자를 도출하고자 하였다.

• 한국광물학회지
• /
• 제27권3호
• /
• pp.115-124
• /
• 2014

금-은 함유 황화광물 정광으로부터 Au와 Ag를 용출시키기 위하여 황화광물 정광을 건식과 습식으로 전처리하였다. 전처리한 황화광물에 대하여 광물학적 연구와 티오요소 용출실험을 수행하였다. 평균입도와 등전위는 정광시료에서 보다 건식 전-처리 시료에서 낮게 나타났고, 건식 전-처리 시료 보다 습식 전-처리 시료에서 더 낮게 나타났다. XRD 분석결과, 습식 전-처리 시료에서만 비정질의 특성이 나타났다. 정광시료에서, 최대의 Au, Ag 용출인자는 1.0 g의 티오요소, 1.0 M의 황산제2철, 2.0 M의 황산 농도에서 그리고 $60^{\circ}C$의 용출온도에서였다. Au, Ag용출률은 건식 전-처리 시료에서 보다 습식 전-처리 시료에서 언제나 많이 그리고 빠르게 나타났다. 따라서, 향후 적당한 미분쇄 첨가제와 시간으로 전처리를 수행하고 비-시안 용매를 적용한다면 친환경적으로 Au, Ag를 용출시킬 수 있을 것으로 기대된다.

• 대한환경공학회지
• /
• 제30권10호
• /
• pp.1047-1053
• /
• 2008

돈분폐수 처리수의 색도를 제거하기 위해 최적의 응집 조건에 대하여 평가하였다. 유출수의 용존 유기 탄소 농도는 227.3 mg/L, 색도는 2,430 CU, 탁도는 22.1 NTU, 그리고 UV$_{254}$는 3.7 cm$^{-1}$이었다. 유출수의 소수성 유기물은 55.3%, 반친수성 유기물은 17.4%, 그리고 친수성 유기물은 27.3%로 세분화하였다. 또한, 겉보기 분자량 분포는 0.5 K 이하, 0.5$\sim$1 K, 1$\sim$10 K, 10$\sim$30 K 및 30 K 이상은 각각 74.2%, 7.3%, 5.5%, 7.1% 및 5.9%이었다. 최적의 pH 및 응집제 주입량을 결정하기 위해 유동전류계를 사용하였다. 황산알루미늄과 염화 제 2철의 최적 응집제 주입량 및 pH는 각각 5.84 mM, pH는 5.3이며, 9.25 mM, pH는 5.0이었다. 최적의 응집 조건에서 황산알루미늄과 염화 제 2철은 각각 91.9%와 98.7%로 높은 색도 제거 효율을 얻었다. 생물학적 처리를 거친 돈분폐수는 화학적인 응집으로 색도제거에 좋은 성과를 보여주었다.