• 분석과학
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• 제20권3호
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• pp.193-197
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• 2007

본 연구에서는 금속침적처리에 의한 입상활성탄의 페놀흡착에 관하여 고찰하였다. 금속침적 용액으로는 질산코발트와 질산아연용액을 사용하였다. 77K에서의 질소 흡탈착 특성을 통한 비표면적 및 포어 구조를 측정하였다. 페놀 흡착량 및 흡착속도는 분광광도계를 이용하여 측정하였다. 요오드흡착 용량은 금속 침적 처리되지 않은 활성탄보다 코발트 금속이 침적된 코발트침적 활성탄이 크게 흡착됨을 알 수 있다. 코발트 침적 활성탄은 중기공이 발달되었고, 이것은 메틸렌블루와 같은 고분자 물질의 흡착에 다른 흡착제보다 효과적이다. 페놀 흡착용량은 금속 침적활성탄의 금속 침적에 따른 비표면적 감소에도 불구하고 Co-GAC>Zn-GAC>R-GAC 순서로 측정되었다.

• 대한약침학회지
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• 제14권2호
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• pp.5-14
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• 2011

Objectives: Fibrinolytic enzyme preparations were isolated from the snake venom of Macrovipera lebetica turanica in this study. Methods: The purity of the preparations was determined using SDS-PAGE and the enzymic characteristics of the purified fibrinolytic enzyme were determined. Results: 1. All of the two preparations with fibrinolytic activity obtained from the snake venom of M. l. turanicat contained the major polypeptide with the molecular weight of 27,500. One of the preparation showed purified fibrinolytic enzyme. 2. The purified fibrinolytic enzyme hydrolyzed ${\alpha}$-chain of fibrinogen faster than ${\beta}$-chain but not ${\gamma}$-chain. 3. The fibrinolytic activity was inhibited completely by EDTA, EGTA, 1,10-phenanthroline, and dithiothreitol. 4. The fibrinolytic activity was inhibited completely by calcium chloride, iron(III) chloride, mercuric chloride, and cobalt (II) chloride. 5. The fibrinolysis zone formed after addition of zinc sulfate was smaller but clearer than the control. Conclusions: These results suggested that the fibrinolytic enzyme purifed from the snake venom of M. l turanica was a metalloprotease containing dithiol group.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1654-1658
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• 2014

High value-added aromatic aldehydes (e.g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide ($H_2O_2$) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin ($Co(TPPS_4)$) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without $Co(TPPS_4)$. Moreover, a possible mechanism of HFBO oxidation using $Co(TPPS_4)/H_2O_2$ was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under $Co(TPPS_4)/H_2O_2$ system.

• The Korean Journal of Physiology and Pharmacology
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• 제20권1호
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• pp.53-62
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• 2016

Mesenchymal stem cells (MSCs) in the bone marrow and other somatic tissues reside in an environment with relative low oxygen tension. Cobalt chloride ($CoCl_2$) can mimic hypoxic conditions through transcriptional changes of some genes including hypoxia-inducible factor-$1{\alpha}$ (HIF-$1{\alpha}$) and vascular endothelial growth factor (VEGF). This study evaluated the potential role of $CoCl_2$ preconditioning on multi-lineage differentiation of C3H/10T1/2, a murine MSC line to understand its possible molecular mechanisms in vitro. $CoCl_2$ treatment of MSCs markedly increased HIF-$1{\alpha}$ and VEGF mRNA, and protein expression of HIF-$1{\alpha}$. Temporary preconditioning of MSCs with $CoCl_2$ induced up-regulation of osteogenic markers including alkaline phosphatase, osteocalcin, and type I collagen during osteogenic differentiation, followed by enhanced mineralization. $CoCl_2$ also increased chondrogenic markers including aggrecan, sox9, and type II collagen, and promoted chondrocyte differentiation. $CoCl_2$ suppressed the expression of adipogenic markers including $PPAR{\gamma}$, aP2, and $C/EBP{\alpha}$, and inhibited adipogenesis. Temporary preconditioning with $CoCl_2$ could affect the multi-lineage differentiation of MSCs.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1137-1142
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• 2004

A spectrophotometric and first derivative spectrophotometric method was developed in aquatic Tween 80 micellar solutions for selective determination of nickel without using any pre-separation step. 1-(2-Pyridylazo)-2-naphthol (PAN), as a sensitive chromogenic complexing agent formed a red-colored Ni(II)-PAN complex in Tween 80 media with satisfactory solubility and stability. Conditions such as pH, PAN concentration, type and concentration of micellizing agent were optimized. Molar absorptivity of Ni-PAN complex was found $4.62\;{\times}\;10^4L\;cm^{?1}\;mol^{?1}$ at 569 nm, under the optimum condition. Calibration graphs were derived by zero, first and second derivative spectrophotometry at maximum wavelengths of 569, 578 and 571 nm with linear ranges of 30-1800, 20-2500 and 30-2000 ng $mL^{?1}$ , respectively. Precision as standard deviation as well as accuracy as recovery percent were in the range of 1-20 ng $mL^{?1}$, and 93.3-103.3%, respectively, for the entire of the linear ranges. Spectrophotometric detection limit was 3 ng $mL^{?1}$ and effects of diverse ions on the first derivative determination of nickel were studied to investigate selectivity of the method. Interferences of cobalt and copper on the nickel determination were prevented using o-phenanthroline as masking agent. The recommended procedures were applied to the various synthetic and stainless steel alloys, tea leaves and human hair, with satisfactory results.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.68-72
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• 2007

A new PVC membrane potentiometric sensor that is highly selective to Hg2+ ions was prepared, using bis(2-hydroxybenzophenone) butane-2,3-dihydrazone (HBBD) as an excellent hexadendates neutral carrier. The sensor works satisfactorily in the concentration range of 1.0 × 10-6 to 1.0 × 10-1 mol L-1 (detection limit 4 × 10-7 mol L-1) with a Nernstian slope of 29.7 mV per decade. This electrode showed a fast response time (~8 s) and was used for at least 12 weeks without any divergence. The sensor exhibits good Hg2+ selectivity for a broad range of common alkali, alkaline earth, transition and heavy metal ions (lithium, sodium, potassium, magnesium, calcium, copper, nickel, cobalt, zinc, cadmium, lead and lanthanum). The electrode response is pH independent in the range of 1.5-4.0. Furthermore, the developed sensor was successfully used as an indicator electrode in the potentiometric titration of mercury ions with potassium iodide and the direct determination of mercury in some binary and ternary mixtures.

• 대한약침학회지
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• 제14권3호
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• pp.71-79
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• 2011

Objectives : This study was undertaken to identify fibrinolytic proteases from Gloydius blomhoffii siniticus venom and to characterize a major fibrinolytic protease purified from the venom. Methods : The venom was subjected to chromatography using columns of Q-Sepharose and Sephadex G-75. The molecular weights of fibrinolytic proteases showing fibrinolytic zone in fibrin plate assay were determined in SDS-PAGE (Sodium dodecyl sulfate-polyacrylamide gel electrophoresis) The effects of inhibitors and metal ions on fibrinolytic protease and the proteolysis patterns of fibrinogen, gelatin, and bovine serum albumin were investigated. Results : 1) The fibrinolytic fractions of the three peaks isolated from Gloydius blomhoffii siniticus venom contained two polypeptides of 46 and 59 kDa and three polypeptides of 32, 18, and 15 kDa and a major polypeptide of 54 kDa, respectively. 2) The fibrinolytic activity of the purified protease of 54 kDA was inhibited by metal chelators, such as EDTA, EGTA, and 1,10-phenanthroline, and disulfhydryl-reducing compounds, such as dithiothreitol and cysteine. 3) Calcium chloride promoted the fibrinolytic activity of the protease, but mercuric chloride and cobalt(II) chloride inhibited it. 4) The fibrinolytic protease cleaved preferentially A${\alpha}$-chain and slowly B${\beta}$-chain of fibrinogen. It also hydrolyzed gelatin but not bovine serum albumin. Conclusions : The Gloydius blomhoffii siniticus venom contained more than three fibrinolytic proteases. The major fibrinolytic protease was a metalloprotease which hydrolyzed both fibrinogen and gelatin, but not bovine serum albumin.

• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.961-965
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• 1997

1H NMR spectra of 3,3-dimethylpiperidine (1) at -70 to 30 ℃ exhibit gradual change from slow to rapid exchange between two alternate chair forms. The exchange rate constant was determined as a function of temperature by simulating the line shape of the signal from the two methyl groups using the modified Bloch equations. The resulting free energy of activation is ΔG* = 44.4±1.9 kJ mol-1 at 298 K. The 1H NMR spectrum of a D2O or dimethylsulfoxide-d6 (DMSO-d6) solution containing 1 and [SiW11CoⅡO39]6- exhibits separate signals for the free ligand and the complex, indicating that the ligand exchange is slow on the NMR time scale. In D2O the piperidine ring is frozen as a chair form even at room temperature with the cobalt ion bonded to the axial position of the nitrogen atom. When DMSO-d6 is added to the D2O solution, the NMR spectral change suggests that a rapid exchange occurs between the chair form and another conformer. It is proposed that the conformation of ^b1^b coordinated to [SiW11CoⅡO39]6- in DMSO-d6 is close to a twist form.

• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1036-1042
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• 1998

The preconcentration and determination of trace elements in water samples were studied by a solvent sublation utilizing dithizonate complexation. After metal dithizonates were formed, trace amounts of cadmium, cobalt, copper and lead were floated and extracted into small volume of a water-immiscible organic solvent on the surface of sample solution and determined in the solvent directly by GF-AAS. Several experimental conditions as formation condition of metal-dithizonate complexes, pH of solution, amount of dithizone, stirring time, the type and amount of surfactants, N2 bubbling rate and so on were optimized for the complete formation and effective flotation of the complexes. And also four kinds of light solvents were compared each other to extract the floated complexes, effectively. After the pH was adjusted to 4.0 with 5 M HNO3, 8.0 mL of 0.05% acetone solution of dithizone was added to 1.00 L water sample. The dithizonate complexes were flotated and extracted into the upper methyl isobutylketone (MIBK) layer by the addition of 2.0 mL 0.2% ethanolic sodium lauryl sulfate solution and with the aid of small nitrogen gas bubbles. And this solvent sublation method was applied to the analysis of real water samples and good results of more than 85% recoveries were obtained in spiked samples.

• 한국결정학회지
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• 제6권2호
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• pp.125-133
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• 1995

부분적으로 Co2+ 이온으로 치환된 제올라이트 X (Co41Na10Al92Si100O384)를 탈수한 구조를 21℃에서 입방공간군 Fd3(α=24.544(1)Å)을 사용하여 단결정 X-선 회절법으로 해석하고 정밀화하였다. 이 결정은 Co(NO3)2와 Co(O2CCH3)2의 농도가 각각 0.025M 되도록 만든 혼합 용액을 이용하여 흐름법으로 이온 교환하여 만들었다. 이 결정은 380℃에서 2×10-6 Torr 하에서 2일간 진공 탈수하였다. Full-matrix 최소자승법 정밀화 계산에서 I > 3σ(I)인 211개의 독립반사를 사용하여 최종 오차 인자를 R1=0.059, R2=0.046까지 정밀화시켰다. 이 구조에서 Co2+ 이온과 Na+ 이온은 서로 다른 4개의 결정학적 자리에 위치하고 있었다. 41개의 Co2+ 이온은 점유율이 높은 서로 다른 두 개의 자리에 위치하고 있었다. 16개의 Co2+ 이온은 이중 6-산소 고리 (D6R)의 중심에 위치하였고 (자리 I; Co-O = 2.21(1)Å, O-Co-O = 90.0(4)°), 25개의 Co2+ 이온은 큰 동공에 있는 자리 II에 위치하고 세 개의 산소로 만들어지는 평면에서 큰 동공쪽으로 약 0.09Å 들어간 자리에 위치하고 있었다. (Co-O = 2.05(1)Å, O-Co-O = 119.8(7)°). 10개의 Na+ 이온은 2개의 서로 다른 자리에 위치하고 있다. 7개의 Na+ 이온은 큰 동공에 있는 자리 II 위치하였다. (Na-O = 2.29(1)Å, O-Na-O = 102(1)°). 3개의 Na+ 이온은 큰 동공에 있는 자리 III에 위치하고 있었다. (Na-O = 2.59(10)Å, O-Na-O = 69.0(3)°). 7개의 Na+ 이온은 가장 가까운 산소 평면에서 큰 동공 쪽으로 약 1.02Å 들어간 자리에 위치하고 있었다. Co2+ 이온은 자리 I과 자리 II에 우선적으로 위치하고, Na+ 이온은 그 나머지 자리인 자리 II와 자리 III에 위치한다.