• Journal of the Korean Chemical Society
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• v.31 no.1
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• pp.45-54
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• 1987

Dowex 1-X8 resin ion exchanged with calcon carboxylic acid (CCA-Dowex 1-X8) and 2-methyl-8-hydroxyquinoline(MHQ) impregnated-Amberlite XAD-4 resin (MHQ-XAD-4) were examined for the separation and preconcentration of ferric ion from the various matrices. The stabilities of these resins were investigated, and their capacities on ferric ion were also measured. The effect of pH on the adsorption of ferric ion and matrix ions, such as Al(Ⅲ) and Ca(Ⅱ), was investigated to determine the optimun pH ranges. Separation and preconcentration of iron in aluminium foil and mineral water samples were studied by elution method with these resin columns. The recovered ions by 10ml of 2F nitric acid was determined by flame atomic spectrophotometry. SP-Sephadex C-25 column was used to separate ferrous and ferric ion in mineral water by stepwise elution with ferrozine and 1 % ascorbic acid-ferrozine solution. The concentrated and separated each ion could be determined spectrophotometrically at the analytical wavelenth of Fe(Ⅱ)-ferrozine complex (562nm).

• Journal of the Korean Chemical Society
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• v.29 no.6
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• pp.615-622
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• 1985

The chemical species formed by uranium and vanadium and their equilibria have been investigated in the various concentrations of oxalic and acetic acids by the ion exchange chromatography and UV-Vis spectrophotometry. Uranyl and vanadyl ions seem to be form the complex as $UO_2(C_2O_4)_2=$, $UO_2(C_2O_4)_3^{4-}$ and $VO_2(C_2O_4)-2^{3-}$ respectively in the concentration range of 0.005∼0.05M oxalic acid concentration. In the case of acetic acid the equilibria of $UO_2^{2+}+3Ac^-=UO_2(Ac)_3^-$ and $VO_2^++2Ac^-=VO_2(Ac)_2^-$ were existed individually according to the increase of acetic acid concentration.

• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.692-697
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• 1995

The chemical compositions and possible structure for the complex of B15C5 with Nd(Ⅲ) have been determined by NMR spectrophotometry in acetone-d6. On the stepwise additions of Nd(Ⅲ) to B15C5 solution of constant concentration, all the resonances shifted to downfield and the mole ratio of B15C5 to Nd(Ⅲ) was found to be 1 : 1. From the line broadening of proton peaks of NMR spectra, it was found that oxygen atoms in B15C5 interact with Nd(Ⅲ) ion. And in IR spectra of Nd(Ⅲ)-B15C5 complex, the band of asymmetric C-C-O stretching vibration shifted to a lower frequency region upon complexation. We have proposed the possible structure of the Nd(Ⅲ)-B15C5 coordinated with the five ether oxygen atoms and with the three bidentate nitrato groups.

• Journal of the Korean Chemical Society
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• v.39 no.6
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• pp.440-445
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• 1995

The chemical compositions and stability constants, thermodynamic parameters for the neodymium(Ⅲ) complexes of substituted benzo-1,4,7,10,13-pentaoxacyclopentadecane(B15C5) have been determined by spectrophotometry and conductometry in methanol solution at various temperatures. As substituents, CH3, Br, CHO, NO2, and 3,4-(NO2)2 were used. In methanol solution the ratios of neodymium(Ⅲ) to the ligands in the complexes are 1 : 1. The stability constants were increased in order of B15C5-3,4-(NO2)2 < B15C5-NO2 < B15C5-CHO < B15C5-Br < B15C5 < B15C5-CH3. This observation can be explained in terms of the substituent effect. The order of stability constants was dimethylsulfoxide < acetone < acetonitrile in solution and the magnitudes were found to be inversely proportional to the solvents donicities. These results could be understood in terms of solvent basicity, ligand basicity, solvation of the cation, and entropy changes of complex formation.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.919-924
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• 1992

The kinetics of the hydrolysis of N-benzylidenebenzenesulfonamide derivatives have been investigated by ultraviolet spectrophotometry in $H_2O$ at $25^{\circ}C$. A rate equation which can be applied over a wide pH range was obtained. The substituent effect on the hydrolysis of N-benzylidenebenzenesulfonamide derivatives were studied and rate of hydrolysis is known to be accelerated by electron withdrowing group. Final product of the hydrolysis was benzenesulfonamide and benzaldehyde. Base on the rate equation, substituent effect, general base effect and final products, hydrolysis of N-benzylidenebenzenesulfonamide derivatives seemed to be initiated by the hydronium ion at the pH 0.2${\sim}$2.5 and proceeded by the neutral $H_2O$ molecule at pH 3.0${\sim}$8.0 but proceeded by the hydroxide ion at above pH 8.5.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1459-1462
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• 2009

Two new flavone glycosides, giraldiin A and B, together with three known compounds, annulatin, myricetin 3-O-$\alpha$- L-rhamnopyranoside and gallic acid, were isolated from the ethanol extract of the root of Pteroxygonum giraldii Damm. et Diels. The structures of giraldiin A and B are designated as 3'-($\alpha$-L-arabinopyranosyloxy)-4',5,5',7- tetrahydroxy-3-methoxyflavone and 4'-($\beta$-D-glucopyranosyloxy)-5,5',7-trihydroxy-2',3-dimethoxyflavone, respectively, on the basis of detailed spectroscopic analyses. The free radical scavenging activity of giraldiin A was evaluated by decolouring spectrophotometry of pentamethine cyanine dye (Cy5) with $Fe^{2+}-H_2O_2$ Fenton radical generating system. The results indicated the hydroxyl free radical scavenging activity of giraldiin A (E$D_{50}$ = 23.7 nmol/mL) is higher than that of some known antioxidants such as rutin, puerarin, daidzein and 2,6-di-tertbutyl-4-methylphenol.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.10.1-10.6
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• 2018

Background: The objective of this study was to evaluate the changes in gene expression after incubation of cells with proteins released from different silk mat layers. Methods: A silk cocoon from Bombyx mori was separated into four layers of equal thickness. The layers were numbered from 1 to 4 (from the inner to the outer layer). The proteins were released by sonication of a silk mat layer in normal saline. The concentration of proteins was determined by spectrophotometry. They were incubated with RAW264.7 cells, and changes in the expression of genes were evaluated by cDNA microarray analysis and quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Results: Layer 1 and 4 groups had higher protein concentrations compared to those in layer 2 and 3 groups. The genes associated with inflammation and angiogenesis showed significantly higher expression in layer 1 and 4 groups. The results of qRT-PCR were in agreement with those of the cDNA microarray analysis. Conclusions: The silk mat from the middle portion of the silkworm cocoon yielded a lower protein release and caused an insignificant change in the expression of genes that are associated with inflammation and angiogenesis.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.1
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• pp.53-62
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• 1990

This experiment was performed to clarify the effects of /sup 60/Co gamma irradiation on secretory function, amylase activity and contents of nucleic acids of parotid gland in rat. Experimental animals were divided into 6th hours, 3rd, 7th, 14th and 28th days after irradiation and control. The experimental animals are singly irradiated with 20Gy (2,000rad) through protective lead block. Secretory function of parotid gland was evaluted by uptake and clearance of /sup 99m/TcO₄. /sup 99m/TcO₄. 0.2μ ci/gm, was injected into peritonium in uptake groups. Rats were sacrified with cervical dislocation after 30 minutes and gland was excised. In the clearance group. pilocarpine nitrate (8㎎/㎏) was intraperitoneally injected at 30 minutes after /sup 99m/TcO₄ injection and rats were sacrified 30 minutes after pilocarpine injection. Radioactivity of excised parotid gland was measured by using of gamma counter and stimulation-secretion coefficients, uptake radioactivity divided by clearance radioactivity, was calculated. Amylase activity and contents of DNA and RNA were determined by spectrophotometry. The results obtained were as follows: 1. In the uptake test, the radioactivity of /sup 99m/TcO₄ per unit weight increase in experimental group except 6th hours group, compared with control groups and showed a peak at 3rd days after irradiation. 2. In the clearance test, the radioactivity of /sup 99m/cO₄per unit weight rose to a peak at 3rd days after irradiation and gradually recovered thereafter. 3. Stimulation-secretion coefficient of parotid gland decreased at 6th hours, 3rd and 7th days after irradiation, and gradually increased. 4. Amylase activity of parotid gland decreased in 3rd and 7th days group, and especially lowest in 3rd days after irradiation. 5. The contents of DNA showed no definite difference in all the experimental groups, but RNA was seemed to decrease with time after irradiation.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.328-334
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• 1984

A series of phenyl N-benzenesulfonylchloroformimidate derivatives (p-H, p-Cl, p-CH3 & p-OCH3) were prepared and the hydrolysis of these compounds were studied kinetically at various pH by UV spectrophotometry in 1 ; 4 dioxane-water at $25^{\circ}C$. Hammett ${\rho}$ values measured at pH 5.0 (${\rho}$ = -0.45) and pH 10.0 (${\rho}$ = 0.40) indicate that the reaction proceeds via an azocarbonium ion intermediate in the acidic medium, whereas, it involves direct attack by hydroxide ion on the azomethine carbon atom occurs under the basic medium. The formation of stabilized azocarbonium ion species at pH 5.0 is also consistent with the large solvent effect(m = 1.3-1.5 & n = 5.0-5.5). On the basis of these findings, we may concluded that the hydrolysis of phenyl N-benzenesulfonylchloroformimidate derivatives proceeds by $SN_1$ below pH 8.0, however, above pH 10.0, the hydrolysis proceeds through $SN_2$ and in the range of pH 8.0-10.0, these two reactions occur competitively.

• Journal of the Korean Chemical Society
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• v.17 no.4
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• pp.269-274
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• 1973

The rate constants of the hydrolysis of ${\alpha}$-Cyano-${\beta}$-piperonylacrylic acid were determined by Ultraviolet spectrophotometry at various pH and a rate equation which can be applied over wide pH range was obtained. The reaction mechanism of hydrolysis of ${\alpha}$-Cyano-${\beta}$-piperonylic acid and especially the catalytic contribution of hydroxide ion which not studied carefully before in acidic media, can be fully explained by the rate equation obtained. The rate equation reveals that; below pH 4.0, the reaction is initiated by the addition of water molecule to ${\alpha}$-Cyano-${\beta}$-piperonyl acrylic acid. At pH $5.0{\sim}7.5$, ${\alpha}$-Cyano-${\beta}$-piperonylacrylic acid compete with ${\alpha}$-Cyano-${\beta}$-piperonyl acrylate ion in adding of water. At pH 8.0, water is the only nucleophile for ${\alpha}$-Cyano-${\beta}$-piperonylacrylate ion, however, above pH 12.0, hydroxide ion is an addendum and the accepter is ${\alpha}$-Cyano-${\beta}$-piperonylacrylate ion.