• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.42-46
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• 2003

This research was carried out for searching the treatment conditions of organic acid and heating to prepare oligomers from the carrageenan. The applied treatments were autoclaving, micraowaving, and ultrasonicating with acetate, citrate, lactate, malate, and succinate. Among several physical depolymerization methods, auo-claving treatment was the most effective for hydrolyzing the carrageenan to low molecular compounds such as oligosaccharides. Citrate or malate was the most effective catalyst in hydrolyzing carrageenan to some oligo-saccharides among 5~7 different organic acids. An acceptable autoclaving condition for hydrolyzing carrageenan to oligosaccharides was to treat for 120 min at 110~12$0^{\circ}C$. The maximum depolymerization ratio produced by autoclaving was about 23.0%. The depolymerized carrageenan prepared by autoclaving at 12$0^{\circ}C$ had oligo-saccharides of 5~7 species.

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.257-265
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• 1995

Free amino acids were isolated from milk and their absolute amounts were determined by reversed phase high performance liquid chromatography after derivatization with dansyl chloride. The determination of D- and L-amino acids was based on achiral separation on a C18 column. It was found that milk contained totally 41.00 mg DL-amino acids in 100 mL milk. The level of D-amino acids to L-amino acids was determined by a column-switching system combining an achiral reversed phase separation and chiral chelate additive. The chiral separation was carried out with addition of the chiral Cu(N-benzyl-L-proline)2 chelate to the mobile phase in reversed phase liquid chromatography. It was found that the determination of 16 different amino acids is feasible in the milk sample with a C18 column separation and 12 D-amino acids out of the 16 amino acids can be determined via the column-switching system with chiral separation. 2.05% of D-glutamic acid and 2.93% of D-alanine were found in milk.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.35-48
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• 2004

This paper provides a comprehensive overview of geochemical approaches for investigating and assessing heavy metal contamination in abandoned mine sites. Major sources of contaminants at the abandoned mine sites are mine water, waste rocks, tailings, and chemicals used in beneficiation and mineral processing. Soil, sediment, surface and ground water, and ecological system can be contaminated by heavy metals, which are transported due to erosion of mine waste piles, discharge of acid mine drainage and processed water, and dispersion of dust from waste rocks and tailings. The abandoned mine sites should be characterized using various methods including chemical analysis, mineralogical analysis, acid generation prediction tests, leaching/extraction tests, and field tests. Potential and practical environmental impacts from the abandoned mines should be assessed based on the site characterization.

• Microbiology and Biotechnology Letters
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• v.29 no.4
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• pp.248-252
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• 2001

Recombinant Human serum albumin (rHSA) was purified to near homogeneity from H, polymorpha using heat treatment, ultrafiltratipn and Phenyl Sepharose CL-4B and Mono Q column chro - matographies with a recovery yield of 60% The molecular weight of the purified rHSA was estimated to be about 65,000 Da by denaturing SDS-PAGE The N terminal amino acid sequence of the purified HSA determined by Edman degradation was turned out to be Asp- Ala- His- Lys- Ser- Glu- Ala, suggesting that the rHSA expressed in H, polymorpha was efficiently secreted and correctly processed at the cleavage site of secretion signal sequence. The purified human albumin showed the pI value identical to that of authentic human serum albumin.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.849-856
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• 1992

We prepared a simple, economic and versatile preparative system for an enantiomeric separation. Hydrophobic amino acid enantiomers were resolved in the preparative scale by a centrifugal liquid chromatography on the N-hexadecyl-L-proline coated reversed phase. The factors controlling the retention and resolution of racemic amino acids such as the concentration of Cu(Ⅱ), pH of the eluent, the type and content of organic modifier, and rpm of CLC were examined. Several mg of hydrophobic amino acid enantiomers were separated preparatively. To separate all of different amino acid enantiomers, various coating material will be investigated.

• Journal of the Korean Chemical Society
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• v.18 no.1
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• pp.31-39
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• 1974

Solutions of $Mn^{++}, Co^{++} and Zn^{++}$ were mixed with various dibasic organic acids in the presence of cation exchange resin at room temperature. The distribution ratios of the metal ions between resin and solution were measured, using radioactive metal ions as tracer. From the observed variation of the distribution ratios with acid anion concentrations, it was concluded that $Mn^{++}, Co^{++}$ and $Zn^{++}$ formed one-to-one complexes with succinate, malonate, o-phthalate and tartrate ions in aqueous, 20 % ethanol-water and 20 % acetone-water solutions. The results of the present investigation indicated that the relative stabilities of the complexes increased in the order: $Mn^{++} < Co^{++} < Zn^{++} complexes, Succinate < malonate < o-phthalate < tartrate complexes, Aqueous < mixed solvent systems.$

• Economic and Environmental Geology
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• v.53 no.1
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• pp.99-110
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• 2020

It is a global trend to consider contaminated low-permeability zones as one of the primary management targets for the remediation of DNAPL contaminated sites. In addition, studies on the persistence caused by back diffusion of DNAPLs from low-permeability zones have been actively conducted worldwide. On the other hand, the studies for domestic groundwater contamination with the low-permeability zones are insufficient. Therefore, this study introduces the forward and back diffusions of DNAPL through low-permeability zones and suggests the importance of them by reviewing representative previous studies, especially on back diffusion and plume persistence. We proposed six diffusion scenarios and analytical solutions based on various boundary conditions of low-permeability zones. FI (forward diffusion into infinite domain) and BI (back diffusion form infinite domain) scenarios illustrate forward and back diffusion in which the depths of a low-permeability layer are assumed to be infinite. FFN (forward diffusion into finite domain with no flux boundary) and BFN (back diffusion from finite domain with no flux boundary) scenarios describe forward and back diffusion for a finite domain of a low-permeability layer with no flux boundary at the bottom. When the bottom of a low-permeability layer is considered as flux boundary, forward and back diffusion scenarios correspond to FFF (forward diffusion into finite domain with flux boundary) and BFF (back diffusion from finite domain with flux boundary). The scenarios and analytical solutions in this study may contribute to the determination of an efficient remediation method based on site characteristics such as a thickness of low-permeability zones or duration of contamination exposure.

• Analytical Science and Technology
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• v.15 no.4
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• pp.373-380
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• 2002

Humic and fulvic acids present in soil of different depth were extracted and their characteristics were analyzed as a basic study to evaluate the effect of humic substances on the behaviour of radioactive elements deposited on soil. Molecular size distribution of the humic and fulvic acids was measured by stirred cell ultrafiltration technique and the structural informations were obtained from their UV-Vis., IR and synchronous fluorescence (SyF) spectral analysis. Main molecular size ranges of the soil 1) humic and fulvic acids were 30~100 kDa (46~56%) and 10~30 kDa (33~43%) respectively, and their overall molecular sizes were found to became smaller with increasing the soil depth. Absorptivities measured at 280 nm in the UV-Visible spectra of humic acids were 1.4~1.5 times higher than those of fulvic acids, and increased with increasing the soil depth. SyF spectral data showed two distinct peak components having maximum peak positions of 428 nm (type I) and 498 nm (type II) for the soil humic and fulvic acids. From the analysis of the peak components, it was found that humic molecules are mainly made up of aromatic compounds corresponding to longer wavelength (type II), and the molecular components increased with increasing the soil depth. Analysis of IR spectral data indicated that the humic molecules contain a higher relative concentration of carboxylic groups than those of fulvic molecules, and the carboxylic group contents are seen to increase as the soil depth increase.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.630-631
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• 2000

Sugar esters are produced by transesterification of fatty acids and sugars in organic solvent media. Chromatographic separation of sugar esters and fatty acids was investigated. $C_{18}$ column($3.9{\times}300mm$) was used in the chromatography experiment. The effect of flow rate, column temperature, and sample loading on the charateristics of chromatogram was studied. Sugar esters and fatty acids tested in this study was successfully separated with a high resolution.

• Korean Journal of Soil Science and Fertilizer
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• v.3 no.1
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• pp.55-59
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• 1970

In an effort to determine the bio-synthesis in the soybean as investigate to the variance of each substance: Glutamic acid, Aspartic acid and its amides during the growth of younger soybean plants. 1. The variance-curve of Gultamic acid and Aspartic acid as the acidic amino acids in the cotyledons was appeared the peak the first half period at Glutamic acid and the latter half at Aspartic acid in the growth of soybeans, and was received the symmetrical impression centering around the stage of adult leaf-development. But, in the embryonic organ, it appears the peak at both part, in the developmental stage of adult leaf and also appears near phenomena of increase and decrease in the variation-curve of metabolites. 2. It's amides-Gultamine and Asparagine-appears the peak at the developmental stage of adult leaf in the both cotyledons and embryonic organ, and rapid increase in the cotyledons were very impressed compare with the decrease at fallen stage of cotyledons in the embryonic organs. 3. In the relation of variance at Glutamic acid and Aspartic acid, both substance were discovered the fact of translocation from cotyledon to embryonic organ, and Glutamic acid could supposed that bear the charges of outrider substance in other amino acid as the Glutamic acid-self and major basic function for receiving the ammonia as the nitrogen contain constituent of plant. In the case of Glutamine, formation-mechanism of ammonia which develops due to its hydrolysis in the latter period of soybean growth, suggested that was forfeit its function till instance of fallen cotyledons. 4. In the relation the Aspartie acid and Asparagine, Aspartic acid which begins to decrease from seed-state was supposed that bear sufficiently the charge of outrider substance in the formation of Asparagine other than translocated to embryonic organ from cotyledon. And, formation-theory of Aspartic acid which suppose as formational substance from Kreb's cycle were recognized from latter period of soybean growth, and then, rapid accumulation of Asparagine's amounts were supposed that adapt to two theory: Theory which consider to transformation as Asparagine state for pressing to less than noxious weight the concentration of ammonia developing from the cells, and was formate and accumulate as ammonia or carbohydrates containing excess in the cotyledons.