• Journal of Electrochemical Science and Technology
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• 제10권1호
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• pp.29-36
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• 2019

Corrosion inhibition by synthesised ligand, 2-acetylpyridine 4-ethyl-3-thiosemicarbazone (HAcETSc) and its tin(IV) complex, dichlorobutyltin(IV) 2-acetylpyridine 4-ethyl-3-thiosemicarbazone ($Sn(HAcETSc)BuCl_2$) on mild steel in 1 M hydrochloric acid (HCl) was studied using weight loss measurement, potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The inhibition efficiency increases by increasing the inhibitor concentrations. The polarisation study showed that both synthesised compounds were mixed type inhibitors. The electrochemical impedance study showed that the presence of inhibitors caused the charge transfer resistance to increase as the concentration of inhibitors increased. The adsorption of these compounds on mild steel surface was found to obey Langmuir's adsorption isotherm with the free energy of adsorption ${\Delta}G{^o}_{ads}$ of -3.7 kJ/mol and -7.7 kJ/mol for ligand and complex respectively, indicating physisorption interaction between the inhibitors and 1 M HCl solution.

• 분석과학
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• 제20권4호
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• pp.355-360
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• 2007

The title complex, $(C_3H_{12}N_2)[\{Cd(H_2O)(C_6H_5O_7)\}_2]{\cdot}6H_2O$, I, has been prepared and its structure characterized by FT-IR, EDS, elemental analysis, ICP-AES, and X-ray single crystallography. It is triclinic system, $P{\bar{1}}$ space group with a = 10.236(2), b = 11.318(2), c = $13.198(2){\AA}$, ${\alpha}=77.95(1)^{\circ}$, ${\beta}=68.10(1)^{\circ}$, ${\gamma}=78.12(1)^{\circ}$, V = $1373.5(3){\AA}^3$, Z = 2. Complex I has constituted by protonated 1,3-diaminopropane cations, citrate coordinated cadmium(II) anions, and free water molecules. The central cadmium atoms have a capped trigonal prism geometry by seven coordination with six oxygen atoms of three different citrate ligands and one water molecule. Citrate ligands are bridged to three different cadmium atoms. Each cadmium atom is linked by carboxylate and hydroxyl groups of citrate ligand to construct an one-dimensional ladder-type assembly structure. The polymeric crystal structure is stabilized by three-dimensional networks of the intermolecular O-H${\cdots}$O and N-H${\cdots}$O hydrogen-bonding interaction.

• Tuberculosis and Respiratory Diseases
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• 제50권5호
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• pp.549-556
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• 2001

연구배경 : 세포성장에 관여하는 여러 growth factor중 IGF-I은 IGF-IR와 결합하여 세포증식을 유발하는 mitogen으로 알려져 있다. 대부분의 정상세포 및 암세포는 IGFBPs을 분비하는데 이들은 IGF-I과 결합하여 IGF-I의 세포증식 효과를 증가 혹은 억제시킨다. 마우스 폐암세포주 (3LL)에서 IGF-I이 세포성장에 미치는 효과를 보고, 3LL 세포에서 분비되는 IGFBP을 추출 확인하고, IGFBPs이 세포 성정에 미치는 영향을 관찰하였다. 방 법 : 마우스 폐암세포주 (3LL)를 이용하여, IGF-I을 투여하여 세포성장을 MTT assay로 측정하였고, 3LL에서 분비되는 IGFBP을 추출하여 Western ligand blot 및 western immunoblot으로 확인하였다. 또한 분비된 IGFBP이 세포성장에 미치는 영향을 보기위해, anti-IGFBP antibody을 첨가하여 이의 기능을 억제하여 세포성장에 관한 기능을 관찰하였다. 결 과 : IGF-I은 serum free media에서 3LL 세포성장을 증가시켰다. 3LL 세포는 IGFBP-4를 생성하는 것을 확인하였고, anti-IGFBP-4 antibody를 첨가시 세포성장이 증가된 소견이 관찰되어 IGFBP-4는 세포증식을 억제하는 기능을 가지고 있음을 간접적으로 알 수 있었다. 결 론 : 이상의 실험 결과로 3LL 마우스 폐암세포에서 IGF-I은 세포성장을 증가시키며, 3LL에서 생성된 IGFBP-4는 세포증식을 억제하는 기능을 가지고 있다는 것을 관찰하였다. 향후 IGF-I과 IGFBPs이 암 성장에 미치는 기전과 임상적 적용에 대한 연구가 필요하리라 생각된다.

• BMB Reports
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• 제44권3호
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• pp.170-175
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• 2011

We identified a bovine $B_{12}$ trafficking chaperone bCblC in Bos taurus that showed 88% amino acid sequence identity with a human homologue. The protein bCblC was purified from E. coli by over-expression of the encoding gene. bCblC bound cyanocobalamin (CNCbl), methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl) in the base-off states and eliminated the upper axial ligands forming aquo/hydroxocobalamin ($OH_2$/OHCbl) under aerobic conditions. A transition of $OH_2$/OHCbl was induced upon binding to bCblC. Interestingly, bCblC-bound $OH_2$/OHCbl did not react with reduced glutathione (GSH), while the reaction of free$OH_2$/OHCbl with GSH resulted in the formation of glutathionylcobalamin (GSCbl) and glutathione disulfide (GSSG). Furthermore we found that bCblC eliminates the GSH ligand of GSCbl forming $OH_2$/OHCbl. The results demonstrated that bCblC is a $B_{12}$ trafficking chaperone that binds cobalamins and protects $OH_2$/OHCbl from GSH, which could be oxidized to GSSG by free $OH_2$/OHCbl.

• Archives of Pharmacal Research
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• 제19권4호
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• pp.269-274
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• 1996

The binding interactions between human serum albumin (HSA) and the edible food dyes amaranth, tartrazine and sunset yellow have been studied. Intrinsic association constants and the free energy changes associated with dye-protein binding at physiological pH for amaranth and tartrazine, and at two different pH values for sunset yellow have been calculated from ultrafiltration data. The temperature dependence $(20-40^{\circ}C)$ of the intrinsic association constants at pH 7.4 for amaranth-HSA and tartrazine-HSA mixtures have been measured, from which a plot of the van't Hoff isochore exhibits a marked change in slope around $30^{\circ}C$ indicating a possible change in protein conformation. The number of dye binding sites on HSA is reported for all the above conditions. HSA-ligand binding enthalpies have been used in conjunction with the N-B transitional binding enthalpy for HSA, to calculate the enthalpy for the N-B transition when ligands are bound with the protein.

• 한국환경과학회지
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• 제8권2호
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• pp.205-209
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• 1999

Iron hydroxides are good adsorbents for uncomplexed metals, some metal-ligand complexes and many metal oxyanions. However, their adsorption properties of these precipitations are not fully exploited in wastewater treatment operations because of difficulties associated with their separation from the aqueous phase. This study describes experiments in which iron hydroxides were coated onto the surface of ordinary adsorbents(Sea sand) that are very resistant to acids, The coated adsorbents were used in adsorption of oxyanionic metals. The process was successful in removing some anions such as $SeO_3(-II)$ over a wide range of metal concentrations and sorption of oxyanionic metals increased with decreasing pH. Formation of two surface complexes for oxyanionic metals adsorption on iron hydroxides comprise (1) complexation of the free anion by a positively charged surface site, and (2) protonation of the adsorbed anion (or alternatively adsorption of a protonated form from solution) The coated adsorbents are inexpensive to prepare and could serve as the basis of a useful oxyanionic metal removal.

• 한국자기공명학회논문지
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• 제21권1호
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• pp.26-30
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• 2017

Dynamic properties of proteins can present key information on protein-ligand and protein-protein interaction. Despite their usefulness, the properties of protein dynamics have not been obtained easily due to protein stability and short-term measurement. Here, it is shown that combined method for analysis of dynamical properties. It utilizes predicted order parameter and NMR relaxation data such as $T_1$, $T_2$, and heteronuclear NOE. The suggested method could be used to know the flexibility of protein roughly without precise dynamical parameters such as order parameters through model-free analysis.

• 한국자기공명학회논문지
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• 제21권4호
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• pp.135-138
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• 2017

Titanium phenoxide and titanium carboxylate derivatives were prepared by ligand exchange of titanium tetraisopropoxide with the corresponding phenol and carboxylic acids. The substitution reactions were analyzed by NMR focused in the liberation of isopropylalcohol. The chemical shift of secondary proton of isopropyl group shifted to upfield after liberation; from 4.47 ppm at titanium-bound to 4.1~4.3 ppm at free alcohol state in $CDCl_3$. The substitution reaction of titanium tetraisopropoxide with carboxylic acid was applied to form dye-Ti complex for dye-sensitized solar cell.

• 한국표면공학회지
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• 제25권4호
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• pp.173-180
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• 1992

The effects of the stabilizing additives such as NaCN, 2-MBT and Thiourea on bath decom-position, plating rate and surface morphology have been studied. Bath stability was increased in the order of an additive-free bath, and NaCN-, 2-MBT-, and Thiourea-stabilized baths. The sta-bilizing effects may be attributed to the stability of Cu(II) -complexes. The plating rate is the re-verse order of the bath stability. Accelerative effect of 2-MBT in proper quantity(0.3mg/$\ell$) may be explained by visualizing it absorbed through benzene ring or sulfur atom on portions of the sub-strates. The strong bond of the complexing part of the molecule to nearby chelated copper ions would tend to accelerate plating by making it easier for the Cu2+ -ligand bond to be broken. Sur-face morphologies of copper deposits depend on the bath additives. Electroless copper deposits from the 2-MBT stabilized baths are finer than the deposits from the NaCN- and Thiourea- stabi-lized baths due to the strong adsorption on the substrates.

• 대한화학회지
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• 제55권6호
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• pp.912-918
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• 2011

Tetraaza Schiff base macrocyclic ligands, $L^1$,$L^2$ and their transition metal chelates have been synthesized and characterized by elemental analyses, IR, electronic, EPR and $^1H$ NMR spectra, TGA and magnetic measurements. The molar conductance of one milli-molar solution of the complexes measured in DMF indicates that the divalent metal complexes are nonelectrolyte while those of trivalent metal ion, are 1:1 electrolytic in the same solvent. The reduction of Racah parameter from the free ion value confirms the presence of considerable covalence of metal ligand sigma bond in the Co(II) and Mn(II) complexes. The EPR spectra of Cu(II) complexes at room temperature shows axial symmetry indicating a $d_x{^2}_{-y}{^2}$ ground state with significant covalent character. The thermal analysis suggests that the complexes do not contain water molecules because only the metal is left as residue.