• Journal of Microbiology and Biotechnology
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• 제21권2호
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• pp.147-153
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• 2011

Bacillus species have been involved in metal association as biosorbents, but there is not a clear understanding of this chelating property. In order to evaluate this metal chelating capacity, cultures and spores from Grampositive bacteria of species either able or unable to produce surface layer proteins (S-layers) were analyzed for their capacity of copper biosorption. Only those endowed of S-layers, like Bacillus sphaericus and B. thuringiensis, showed a significant biosorption capacity. This capacity (nearly 50%) was retained after heating of cultures, thus supporting that structural elements of the envelopes are responsible for such activity. Purified S-layers from two Bacillus sphaericus strains had the ability to biosorb copper. Copper biosorption parameters were determined for strain B. sphaericus 2362, and after analyses by means of the Langmuir model, the affinity and capacity were shown to be comparable to other bacterial biosorbents. A competitive effect of $Ca^{2+}$ and $Zn^{2+}$, but not of $Cd^{2+}$, was also observed, thus indicating that other cations may be biosorbed by this protein. Spores that have been shown to be proficient for copper biosorption were further analyzed for the presence of S-layer content. The retention of S-layers by these spores was clearly observed, and after extensive treatment to eliminate the S-layers, the biosorption capacity of these spores was significantly reduced. For the first time, a direct correlation between S-layer protein content and metal biosorption capacity is shown. This capacity is linked to the retention of S-layer proteins attached to Bacillus spores and cells.

• 펄프종이기술
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• 제47권4호
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• pp.81-87
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• 2015

Soda-AQ pulp made from sugarcane bagasse (SCB) were bleached in element chlorine free (ECF) sequence. To reduce chlorine dioxide use, final peroxide bleaching was introduced. Prior to peroxide bleaching, different chelating chemicals were applied for comparative analysis in ISO brightness and viscosity. When using equal total chlorine dioxide usage (4.5%), bleached SCB pulp using chelate and hydrogen peroxide (DEDQP) was reached 86.8% (DTPA), 86.4% (EDTA) ISO brightness, whereas bleached pulp using only hydrogen peroxide (DEDP) reached at 81.2% ISO brightness. Viscosity of DEDQP bleached pulp was 25.6 cPs (DTPA), 25.2 cPs (EDTA), And DEDP bleached pulp was shown 18.0 cPs viscosity. Decreasing of transition metal by chelate process led to improvements in final brightness along with higher viscosity. Due to EDTA is 5-7 times cheaper than DTPA, EDTA is recommended as chelating chemical prior to peroxide bleaching.

• 한국식생활문화학회지
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• 제30권6호
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• pp.790-796
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• 2015

The objective of this study was to investigate the physicochemical properties and antioxidant activities of seven (A, B, C, D, E, F, G) commercial ketchups marketed in Korea. The 70% ethanol extracts were prepared and evaluated for total phenolic content, DPPH and ABTS radical scavenging activities, and metal chelating effect. pH ranged from 3.64 to 3.94, and soluble solid and reducing sugar contents of samples were 2.21~3.51oBrix and 4.78~13.45%, respectively. Salinity of samples was in the range of 1.79 to 3.21%, and sample G showed the lowest salinity. The lightness, redness, and yellowness of the Hunter color system of samples were 15.42~19.94, 18.55~23.98, and 20.87~24.34, respectively. The phenolic contents ranged from 1.37 to 2.60 mg GAE (gallic acid equivalents)/g, with samples F and G exhibiting the highest contents. Antioxidant activity determined based on DPPH and ABTS radical scavenging activities, and metal chelating effects were 45.10~90.87, 55.35~92.53, and 71.10~92.20%, respectively, at a concentration of 200 mg/mL. Samples A and G showed higher antioxidant activity than other samples. There were positive correlations between phenolic contents and antioxidant activity, suggesting that phenolic compounds are the major contributors to antioxidant activity.

• Membrane and Water Treatment
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• 제9권3호
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• pp.137-146
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• 2018

Soil washing is one of the most frequently used remediation technologies for heavy metal-contaminated soils. Inorganic and organic acids and chelating agents that can enhance the removal of heavy metals from contaminated soils have been employed as soil washing agents. However, the toxicity, low removal efficiency and high cost of these chemicals limit their use. Given that humic substance (HS) can effectively chelate heavy metals, the development of an eco-friendly, performance-efficient and cost-effective soil washing agent using a nano-scale chelator composed of HS was examined in this study. Copper (Cu) and lead (Pb) were selected as target heavy metals. In soil washing experiments, HS concentration, pH, soil:washing solution ratio and extraction time were evaluated with regard to washing efficiency and the chelation effect. The highest removal rates by soil washing (69% for Cu and 56% for Pb) were achieved at an HS concentration of 1,000 mg/L and soil:washing solution ratio of 1:25. Washing with HS was found to be effective when the pH value was higher than 8, which can be attributed to the increased chelation effect between HS and heavy metals at the high pH range. In contrast, the washing efficiency decreased markedly in the low pH range due to HS precipitation. The chelation capacities for Cu and Pb in the aqueous phase were determined to be 0.547mmol-Cu/g-HS and 0.192mmol-Pb/g-HS, respectively.

• 분석과학
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• 제10권4호
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• pp.282-290
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• 1997

XAD-16-[4-(2-thiazolylao)]orcinol (TAO)형 킬레이트 수지에 대한 U(VI), Tb(IV), Zr(IV), Cu(II), Pb(II), Ni(II), Zd(II), Cd(II) 및 Mn(II) 이온의 흡착 및 탈착 특성을 용리법으로 조사하였다. 각 금속이온의 총괄용량과 pH 변화에 따르는 혼합 금속이온의 분리능 및 금속이온의 최적 흡착 조건을 조사하기 위하여 금속이온의 흡착에 미치는 흐름속도, 완충용액의 농도에 대한 영향을 검토하였다. 킬레이트 수지에 의한 금속이온의 총괄 흡착 용량은 각각 0.35nmol U(VI)/g resin, 0.49nmol Th(VI)/g resin, 0.41nmol Cu(II)/g resin 및 0.31nmol Zr(IV)/g resin이었다. 그리고 pH 5.0에서 돌파점 용량과 총괄 용량으로부터 얻은 금속이온의 용리순서는 Th(IV)>Cu(II)>U(VI)>Zr(IV)>Pb(II)>Ni(II)>Zn(II)>Mn(II)>Cd(II)이었다. 흐름속도 0.28mL/min 및 pH 2~5범위에서 혼합 금속이온을 분리한 결과 pH가 증가함에 따라 이들 이온의 군분리가 가능하였다. 한편, $HNO_3$, HCl, $HClO_4$, $H_2SO_4$ 및 $Na_2CO_3$ 등의 탈착제에 의한 탈착특성을 조사한 결과 2M $HNO_3$는 Zr(IV)을 제외한 대부분의 금속이온들은에 대하여 높은 탈착효율을 나타냈으며, 1M $H_2SO_4$ 용액을 사용하면 Zr(IV)의 탈착 및 회수가 가능하였다. 또한 킬레이트 수지를 이용하여 미량의 U(VI) 이온이 함유된 인공 해수 시료를 용리시키고 회수한 결과 94%이상의 높은 회수율을 나타내었다. 아울러 XAD-16-TAO 킬레이트 수지는 희토류 금속의 혼합시료를 2M $HNO_3$ 용액으로 용리시키면 U(VI)의 선택적인 분리, 농축 및 회수에 유용함을 알 수 있었다.

• 분석과학
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• 제13권3호
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• pp.323-331
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• 2000

표면적과 다공성이 큰 Amberlite XAD-16 수지와 2-(2-thiazolylazo)-p-cresol(TAC) 및 4-(2-thiazolylazo)-orcinol(TAO)를 작용기로 하여 합성한 두가지 킬레이트수지인 XAD-16-TAC 및 XAD-16-TAO를 이용하여 Th(IV), U(VI) 및 Zr(IV)의 흡착특성을 뱃치법으로 조사하였다. 혼합 금속 이온 용액의 pH를 2-6으로 조절하고 24시간 진탕시킨 결과 최적 흡착 pH가 5-6범위이었으며, 가리움제로 NTA, CDTA 및 $NH_4F$를 택하여 혼합 금속 이온의 가리움효과를 조사한 결과 XAD-16-TAC 킬레이트 수지에서 혼합 금속 중 Zr(IV) 이온을, 그리고 XAD-16-TAO 수지로 Th(IV)이온을 분리하는데 $NH_4F$의 효과가 가장 우수한것으로 나타났다. 한편, $HNO_3$를 탈착제로 사용하여 농도를 0.1-2M로 변화시켜 금속이온의 탈착율을 조사한 결과 두가지 킬레이트 수지는 비슷한 경향을 나타내어 2 M에서는 Zr(IV)이온을 제외한 금속이온이 100% 탈착되었다. 그리고 Zr(IV), Th(IV) 및 U(VI)의 혼합금속용액에서 XAD-16-TAC 수지는 Zr(IV)을, XAD-16-TAO 수지는 Th(IV)을 선택적으로 분리할 수 있었다.

• 약학회지
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• 제50권4호
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• pp.228-233
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• 2006

Matrix metalloproteinase-2 is known to be involved in pathological processes such as tumor invasion or rheumatoid arthritis. A soil microorganism producing siderophore under low iron stress $(up\;to\;5\;{\mu}m\;of\;iron)$ was identified as Burkholderia sp. Hydroxamate type siderophore produced by Burkholderia sp. CAS-5 was partially purified. MMP inhibitory activity of siderophore was confirmed by gelatin zymography. The $Zn^{2+}-chelating$ activity of siderophore correlated with the inhibition of MMP-2 activity.

• Toxicological Research
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• 제22권1호
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• pp.47-54
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• 2006

One of the main attractions of treatment with herbal medicine is its apparent lack of side effects compared with the drug therapies used in allopathic medicine. However, evidence from various countries suggest that Asian herbal medicine carry a significant risk of contamination with toxic heavy metals at levels that may seriously threaten health. The aims of this study were to analyze and compare concentrations of heavy metals in urine and hair from 184 patients taking herbal medicines in the form of decoctions and/or pills in comparison to 101 control subjects taking either Western or no medications. Levels of metal concentrations exceeding WHO reference values were observed in a number of hair and urine samples for all subjects. After adjusting for potential confounders, taking decoctions or pills was associated with higher levels of some metals (such as Cu, Pb in urine), as well a higher odds ratio of exceeding the upper limit of reference ranges for Pb, Hg in hair. In contrast, taking decoctions or pills was associated with lower levels of some metals (such as Cu in urine and Cd, Cu, Hg, Pb in hair), suggesting that some herbal medicines may have a chelating effect on heavy metals in the body. Overall, the results obtained in the study show a mixed picture and suggest that heavy metals contamination in herbs is sometimes present, but may also be counteracted by the potential for some herbal medicines to act as chelating agents. Further study must be followed to obtain more concrete evidence.

• 대한화학회지
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• 제53권2호
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• pp.152-158
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• 2009

산성 용액에서 $Ca^{2+},\;Mg^{2+},\;Mn^{2+},\;Fe^{3+},\;Co^{2+},\;Ni^{2+},\;Cu^{2+}$ 및 $Zn^{2+}$와 Cefpodoxime proxetil (CFP)의 상 호작용을 분광학적으로 조사한 결과 1:1 착물이 형성됨을 알 수 있다. 순수한 약품의 흡수스펙트럼은 270과 345 nm에서 두 개의 현저한 봉오리를 보였다. 여러 pH에서 스펙트럼은 두 개의 isosbestic 점(305 과 330 nm)을 나타내었다. 이는 용액상에서 약품의 쯔비터 이온이 존재함을 의미한다. 다른 농도의 금 속이온에서 CFP의 형광방출 스펙트럼은 chelating enhancement fluorescence(CHEF)효과에 의해 형광강 도가 증가함을 알 수 있었다. 착체의 화학량론은 Job’'s 와 Benesi-Hildebrand 방법에 의해 결정되었다. 착 체의 안정도는 다음 순서와 같다. $Ca^{2+}\;<\;Mg^{2+}\;<\;Co^{2+}\;<\;Ni^{2+}\;<\;Zn^{2+}\;<\;Mn^{2+}\;<\;Cu^{2+}\;<\;Fe^{3+}$.

• 분석과학
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• 제17권3호
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• pp.199-210
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• 2004

Amberite XAD-16 다공성 수지에 4,5-dihydroxynaphthalene-2,7-disulfonic acid (chromotropic acid, CTA)를 화학적으로 결합시켜 XAD-16-CTA형 새로운 킬레이트 수지를 합성하고, 적외선분광법과 원소분석법으로 확인하였다. 이 킬레이트 수지에 대한 금속마감 산업과 관련 있는 9개 금속이온을 포함하는 Cr(III) 및 Cr(VI) 이온들의 흡착 및 탈착 특성을 뱃치법과 용리법으로 조사하였다. XAD-16-CTA 킬레이트수지는 1~5 M의 HCl, $HNO_3$ 및 NaOH 등의 산과 염기 용액에서 매우 안정하였다. pH 2에서 Cr(VI) 이온과 Cr(III) 이온이 공존하는 혼합용액으로부터 Cr(VI) 이온만을 선택적으로 분리할 수 있음을 확인하였으며, Cr(VI)의 최대 흡착용량은 1.2 mmol/g 이었다. 또한 Cr(VI) 이온의 흡착에 미치는 공존 음이온의 영향을 검토한 결과 음이온인 $F^-$, $SO{_4}^{2-}$, $CN^-$, $CH_3COO^-$, $NO{_3}^-$ 이온은 흡착율을 감소시켰으며, $PO{_4}^{3-}$와 $Cl^-$는 흡착에 큰 영향을 미치지 않았다. pH 2에서 킬레이트 수지에 의한 돌파점용량과 총괄용량으로부터 얻은 금속이온의 용리순서는 Cr(VI)>Sn(II)>Fe(III)>Cu(II)>Cd(II)${\simeq}Pb(II){\simeq}Cr(III){\simeq}Mn(II){\simeq}Ni(II){\simeq}Al(III)$이었다. 한편 $HNO_3$, HCl 및 $H_2SO_4$ 등의 탈착제에 의한 Cr(VI) 이온의 탈착특성을 조사한 결과 3 M HCl에서 높은 탈착효율을 나타내었다. 결과적으로, XAD-16-CTA 킬레이트 수지는 여러 가지 금속이온이 혼합된 금속마감산업 인공폐액 중 Cr(VI) 이온의 선택적 분리, 농축 및 회수에 매우 유용함을 알 수 있었다.