• Microbiology and Biotechnology Letters
• /
• v.26 no.4
• /
• pp.338-344
• /
• 1998

New type of chitosan derivatives, chitosan-g-MAP, were synthesized by graft copolymerization of mono (2-methacryloyl oxyethyl) acid phosphate (MAP) into chitosan, in order to solubilize chitosan in water. Ceric ammonium nitrate was used as an initiator for graft copolymerization. The optimal conditions for graft copolymerization were determined on the basis of reaction temperature, time, and the concentration of initiator and monomer. The reaction conditions for the highest percentage of grafting were as follows: an initiator concentration, 3.5${\times}$10$\^$-3/ M; monomer concentration, 0.19 M; and reaction temperature, 40$^{\circ}C$ The reaction rate reached the maximum value after 4 hrs of reaction. Antifungal activity was tested against Candida albicans, Trichophyton rubrum and Trichophyton violaceum by using chitosan-g-MAP and two other chitosan samples which have degree of deacetylation of 70% (DA-7) and 90% (DA-90). Their antifungal activities were investigated in weak acidic range. Maximum antifungal activity of them was observed at pH 5.75. Chitosan-g-MAP inhibited thoroughly the growth of Candida albicans and Trichophyton violaceum. Howerver, DA-70 and DA-90 showed higher antifungal activities on Trichophyton rubrum than that of chitosan-g-MAP.

• Korean Journal of Food Science and Technology
• /
• v.28 no.2
• /
• pp.292-297
• /
• 1996

In this study, biochemical changes of muscle protein in squid Sikhae prepared at various temperatures and moisture content were investigated. The pH values in squid Sikhae decreased rapidly with increase in titratable acidity during fermentation at high temperature and moisture content. Growth rate of lactic acid bacteria increased rapidly during fermentation at high temperature and moisture content. Changes in muscle protein subunit were analyzed by SDS-PAGE; myosin heavy chain component disappeared completely during preparation of squid Sikhae and actin component decreased slowly during fermentation. Therefore, it was suggested that myosin heavy chain component in squid muscle protein was autolyzed at the incipient for-mentation time and actin component was degraded by acidic protease in muscle and protease produced from microorganisms during fermentation.

• Journal of the Korean Chemical Society
• /
• v.44 no.6
• /
• pp.556-562
• /
• 2000

The determination of chlorite ion by flow injection analysis(FIA) with iodometric UV detection were investigated. Under rather acidic condition, chlorite ion react with iodide ion to form iodine and itself is reduced to chloride ion. The chlorite ion was determined indirectly by measuring absorbance of yellow colored iodine at 370 nm. The lengths of the mixing coil and the reaction coil, the pH of the acid stream, the concentration of the iodide ion, the injection loop volume, temperature, and flowrate were optimized as parameters for selectively determining a sort of inorganic disinfection by-product, chlorite ion by using FIA-UV detection setup. Masking agents for removing oxidants or interferences from the prepared water were tested. Independent calibration curve presented linear range of 0.002-0.2 mg/L for chlorite ion with a correlation coefficient of 0.999 or better. The limit of detection(LOD) was 0.18 ${\mu}g/L$ for chlorite ion.

• Journal of the Korean Chemical Society
• /
• v.53 no.2
• /
• pp.152-158
• /
• 2009

Spectrophotometric investigation of the interaction of Cefpodoxime proxetil (CFP) with $Ca^{2+},\;Mg^{2+},\;Mn^{2+},\;Fe^{3+},\;Co^{2+},\;Ni^{2+},\;Cu^{2+}$ and $Zn^{2+}$ in acidic medium showed the formation of 1:1 complex. The absorption spectrum of pure drug exhibits two prominent peaks at 270 and 345 nm. Its spectra scanned at several pH exhibited two isosbestic points (305 and 330 nm) indicating the presence of zwitterionic condition of drug in solution phase. The fluorescence emission spectra of CFP in presence of different concentrations of metal ions showed enhancement in fluorescence intensity which is ascribed to chelating enhancement fluorescence effect (CHEF). The stoichiometry of the complexes was determined by Job’s and Benesi-Hildebrand method. The stability of the complexes follow the order $Ca^{2+}\;<\;Mg^{2+}\;<\;Co^{2+}\;<\;Ni^{2+}\;<\;Zn^{2+}\;<\;Mn^{2+}\;<\;Cu^{2+}\;<\;Fe^{3+}$.

• The Korean Journal of Ecology
• /
• v.22 no.1
• /
• pp.21-29
• /
• 1999

This study was carried out to clarify the syntaxonomy of the pine forest in Youngdong region by the phytosociological methods. As a result of the investigation of 62 quadrats, Pinus densiflora forest was classified into four subassociations: Typical subassociation, Quercus mongolica subassociation, Rhododendron mucronulatum subassociation, Rhus chinensis subassociation. Many differences in ecological characteristics such as species composition, stratum structure, vegetation coverage and of diameter at breast height(DBH) of class distribution were found among the communities. Soil properties of the pine forest on the study area was relatively poor compared with other pine forests, especially, soil pH was strongly acidic with 4.87. Soil conditions among the subassociations appeared different. Future succession of pine forest by the similarity index of communities was proposed. Estimated degree of green naturality for Typical subassociation and Q. mongolica subassociation correspond to 7th grade, and R. mucronulatum subassociation, 8-1st grade, and R. chinensis subassociation, 8-2nd grade.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.30 no.6
• /
• pp.1147-1151
• /
• 2001

We investigated stabilities of blue pigment extracted from Gardenia jasminoides at various conditions to check its applicability for beverages. Gardenia blue pigment with maximum absorption at 587 nm was obtained from the reaction of glycine and genipin (aglycone of geniposide). The blue pigment was found to be relatively unstable at acidic pH but very stable at alkaline conditions with half-life values of 102 days and 126 days at PH 9.0 and PH 11.0, respectively. The pigment also showed high thermal stability with half-life value of 55, 18, and 2 days at 50, 70, and 9$0^{\circ}C$, respectively. The addition of inorganic ions, sugars, and amino acids to model beverage containing this blue pigment increased retention rate at room temperature while addition of vitamin C decreased the stability. The sensory evaluation of the model beverage showed that inorganic ions and amino acids increased overall acceptability, indicating that the blue pigments of Gardenia jasminoides can be used as a natural colorant for leverage.

• Korean Journal of Food Science and Technology
• /
• v.37 no.4
• /
• pp.656-659
• /
• 2005

Hot water extracts of Angelica keiskei aerial parts were solvent-fractionated with ethyl acetate (EtOAc) and buffers (5% $NaHCO_3$, pH 8.0; 1.0 N HCl, pH 3.0) to obtain EtOAc-soluble acidic and neutral fractions. EtOAc-soluble neutral fraction was purified by Sephadex LH-20 column chromatography and reverse phase HPLC. Assay for purification of antioxidative compounds was performed by spraying DPPH solution on thin layer chromatography. Two isolated substances were identified as pseudoisopsoralen and 8-methoxypsoralen(xanthotoxin) by FAB-MS and NMR analyses.

• Journal of Technologic Dentistry
• /
• v.34 no.3
• /
• pp.237-245
• /
• 2012

Purpose: This study was conducted to evaluate the corrosion resistance of metal ions of alloys and use the results as the dental health data. These were performed by examining the corrosion levels of Co-Cr alloys for the full and removable partial denture metal frameworks and porcelain-fused-to-metal crown, among the dental casting nonprecious alloys. Methods: The alloy specimens (N = 10) were manufactured in $15mm{\times}10mm{\times}1.2mm$ and stored in two types of corrosive solutions at $37^{\circ}C$ for seven days. The metal ions were quantitatively analyzed using the Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: Of the three Co-Cr alloys, the Co ion concentration of the porcelain-fused-to-metal alloy was 1.512 ${\mu}g/cm^2$, which indicated the highest metal ion dissolution. The metal corrosion was higher in the more acidic pH 2.2 solution compared with the pH 4.4 solution. In all three Co-Cr alloys, Co ion dissolution was predominant in the two corrosive solutions. Conclusion: The corrosion resistance of the three Co-Cr alloys was high, indicating a good biocompatibility.

• Korean Journal of Microbiology
• /
• v.53 no.4
• /
• pp.304-308
• /
• 2017

Researchers have comparatively fewer opportunities to conduct experiments on foot-and-mouth disease virus (FMDV), owing to the limited availability of biosafety level 3 facilities. Bovine rhinovirus (BRV) and human rhinovirus (HRV), which are genetically closely related to FMDV, have been evaluated in this study as model viruses for FMDV. To discover whether BRV and HRV have similar physicochemical properties as FMDV, virus susceptibility tests have been performed in different physical (pH and heat) and chemical (acidic/alkaline solutions and commercial disinfectants) conditions in vitro. Our data revealed that the physicochemical characteristics of BRV and HRV were nearly similar to those of FMDV.

• Archives of Pharmacal Research
• /
• v.20 no.6
• /
• pp.560-565
• /
• 1997

The physicochemical properties of melatonin (MT) in propylene glycol (PG) and 2-hydroxypropyl-.betha.-cyclodextrin $(2-HP{\beta}CD)$ vehicles were characterized. MT was endothermally decomposed as determined by differential scanning calorimetry (DSC). Melting point and heat of fusion obtained were $116.9{\pm}0.24^{\circ}C $.and $7249{\pm}217 cal/mol$., respectively. MT as received from a manufacture was very pure, at least 99.9%. The solubility of MT in PG solution increased slowly until reaching 40% PG and then steeply increased. Solubility of MT increased linearly as concentration of $2-HP{\beta}CD$ without PG INCREASED$(R^2=0.993)$. MT solubility in the mixtures of pg and $2-HP{\beta}CD$ also increased linearly but was less than the sum of its solubility in $2-HP{\beta}CD$ and PG individually. The MT solubility was low in water, simulated gastric or intestinal fluid but the highest in the mixture of PG(40v/v%) and $2-HP{\beta}CD$ (30w/v%) although efficiency of MT solubilization in $2-HP{\beta}CD$ decreased as the concentration of PG increased. MT was degraded in a fashion of the first order kinetics $(r^2>0.90)$. MT was unstable in strong acidic solution (HCl-NaCl buffer, pH 1.4) but relatively stable in other pH values of 4-10 at $70^{\circ}C$. In HCl-NaCl buffer, MT in 10% PG was more quickly degraded and then slowed dpwm at a higher concentration. However, the degradation rate constant of MT in 2-HP.betha.CD was not changed significantly when compared to the water. The current studies can be applied to the dosage formulations for the purpose of enhancing percutaneous absorption or bioavailability of MT.