• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.716-723
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• 1995

The fucoidan purified from Korean brown seaweed, Ecklonia stolonifera was characterized on molecular structure and blood anticoagulant activities. Extraction was conducted at $100^{\circ}C$ with water and repeated twice. The crude fucodian was 151.1g out of 20.0 kg of Ecklonia stolonifera. The Fucoidan-1, which was purified from crude fucoidan using calcium chloride and cetyl pyridium chloride (CPC), was 35.2% against crude fucoidan. Fucoidan-5 was obtained approximately 28.1% from Fucoidan-1 through DEAE-Toyopearl 650 M ion-exchange column chromatography and showed one band by cellulose acetate electrophoresis. The molecular weight of Fucoidan-5 was estimated to be about 21,000∼23,000 dalton by Sephacryl S-300 gel filtration chromatography. Fucoidan-5 consists of 35.7% of fucose and 4.3% of galactose and the molar ratio of fucose and sulfate was about one to one. IR spectrum of Fucoidan-5 showed absorption at $1240\;cm^{-1}\;and\;850\;cm^{-1}$ and specific rotation value, $[\alpha]$, was $[\alpha]$. These results suggests that the sulfate maybe bind at $C_{4}$ carbon on ${\alpha}-L-fucose$. Gas chromatograph of methyl alditol acetate revealed that Fucoidan-5 is a fucose containing sulfated polysaccharide with $({\alpha}l-2)\;or\;({\alpha}l-2)$ glycosidic linkage. Anti-thrombin activity of the Fucoidan-5 was estimated as 1.4 time stronger than heparin. From above results, the purification methods using CPC and ion exchange chromatography is effective tools for obtaining highly purified fucoidan from Gompi, Ecklonia stolonifera.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.39-42
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• 1999

Perfluoropolymers represent the ultimate resistance to hostile chemical environments and high service temperature, attributed to the presence of fluorine in the polymer backbone, i.e. to the high bond energy of C-F and C-C bonds of fluorocarbons. Copolymers of Tetrafluoroethylene (TEE) and 2, 2, 4Trifluoro-5Trifluorometoxy- 1, 3Dioxole (TTD), commercially known as HYFLON AD, are amorphous perfluoropolymers with glass transition temperature (Tg)higher than room temperature, showing a thermal decomposition temperature exceeding 40$0^{\circ}C$. These polymer systems are highly soluble in fluorinated solvents, with low solution viscosities. This property allows the preparation of self-supported and composite membranes with desired membrane thickness. Symmetric and asymmetric perfluoropolymer membranes, made with HYFLON AD, have been prepared and evaluated. Porous and not porous symmetric membranes have been obtained by solvent evaporation with various processing conditions. Asymmetric membranes have been prepared by th wet phase inversion method. Measure of contact angle to distilled water have been carried out. Figure 1 compares experimental results with those of other commercial membranes. Contact angles of about 120$^{\circ}$for our amorphous perfluoropolymer membranes demonstrate that they posses a high hydrophobic character. Measure of contact angles to hexandecane have been also carried out to evaluate the organophobic character. Rsults are reported in Figure 2. The observed strong organophobicity leads to excellent fouling resistance and inertness. Porous membranes with pore size between 30 and 80 nanometers have shown no permeation to water at pressures as high as 10 bars. However high permeation to gases, such as O2, N2 and CO2, and no selectivities were observed. Considering the porous structure of the membrane, this behavior was expected. In consideration of the above properties, possible useful uses in th field of gas- liquid separations are envisaged for these membranes. A particularly promising application is in the field of membrane contactors, equipments in which membranes are used to improve mass transfer coefficients in respect to traditional extraction and absorption processes. Gas permeation properties have been evaluated for asymmetric membranes and composite symmetric ones. Experimental permselectivity values, obtained at different pressure differences, to various single gases are reported in Tab. 1, 2 and 3. Experimental data have been compared with literature data obtained with membranes made with different amorphous perfluoropolymer systems, such as copolymers of Perfluoro2, 2dimethyl dioxole (PDD) and Tetrafluorethylene, commercialized by the Du Pont Company with the trade name of Teflon AF. An interesting linear relationship between permeability and the glass transition temperature of the polymer constituting the membrane has been observed. Results are descussed in terms of polymer chain structure, which affects the presence of voids at molecular scale and their size distribution. Molecular Dyanmics studies are in progress in order to support the understanding of these results. A modified Theodoru- Suter method provided by the Amorphous Cell module of InsightII/Discover was used to determine the chain packing. A completely amorphous polymer box of about 3.5 nm was considered. Last but not least the use of amorphous perfluoropolymer membranes appears to be ideal when separation processes have to be performed in hostile environments, i.e. high temperatures and aggressive non-aqueous media, such as chemicals and solvents. In these cases Hyflon AD membranes can exploit the outstanding resistance of perfluoropolymers.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.313-331
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• 2022

Natural or native abiotic molecular hydrogen (H₂) is a major component in natural gas, however yet its importance in the global energy sector's usage as clean and renewable energy is underestimated. Here we review the occurrence and geological settings of native hydrogen to demonstrate the much widesprease H₂ occurrence in nature by comparison with previous estimations. Three main types of source rocks have been identified: (1) ultramafic rocks; (2) cratons comprising iron (Fe²⁺)-rich rocks; and (3) uranium-rich rocks. The rocks are closely associated with Precambrian crystalline basement and serpentinized ultramafic rocks from ophiolite and peridotite either at mid-ocean ridges or within continental margin(Zgonnik, 2020). Inorganic geological processes producing H₂ in the source rocks include (a) the reduction of water during the oxidation of Fe²⁺ in minerals (e.g., olivine), (b) water splitting due to radioactive decay, (c) degassing of magma at low pressure, and (d) the reaction of water with surface radicals during mechanical breaking (e.g., fault) of silicate rocks. Native hydrogen are found as a free gas (51%), fluid inclusions in various rock types (29%), and dissolved gas in underground water (20%) (Zgonnik, 2020). Although research on H₂ has not yet been carried out in Korea, the potential H₂ reservoirs in the Gyeongsang Basin are highly probable based on geological and geochemical characteristics including occurrence of ultramafic rocks, inter-bedded basaltic layers and iron-copper deposits within thick sedimentary basin and igneous activities at an active continental margin during the Permian-Paleogene. The native hydrogen is expected to be clean and renewable energy source in the near future. Therefore it is clear that the origin and exploration of the native hydrogen, not yet been revealed by an integrated studies of rock-fluid interaction studies, are a field of special interest, regardless of the presence of economic native hydrogen reservoirs in Korea.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.388-393
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• 2013

It has been well documented that Bacillus vallismortis strain EXTN-1, a beneficial rhizosphere bacterium, could enhance plant growth and induce systemic resistance to diverse pathogens in plants. However, the molecular mechanisms for how the EXTN-1 promote plant growth and induce resistances to diverse pathogens. Here, we show that 3-Hydroxy-2-butanone, a volatile organic compound (VOCs) emitted from the EXTN1, is a key factor for the bacteria-mediated beneficial effects on plant growth and defense systems. We found that the presence of volatile signals of EXTN-1 resulted in growth promotion of tobacco seedlings. The identification and analysis of EXTN-1-secreted volatile signals by solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) indicated that a 3-hydroxy-2-butanone could provide not only the plant growth promotion, but also higher resistance against Pectobacterium carotovorum SCC1. These results suggest that a volatile compound released from EXTN-1 enhances the plant growth promotion and immunity of plants.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.77-77
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• 2016

Thin films synthesized by plasma processes have been widely applied in a variety of industrial sectors. The structure control of thin film is one of prime factor in most of these applications. It is well known that the structure of this film is closely associated with plasma parameters and species of plasma which are electrons, ions, radical and neutrals in plasma processes. However the precise control of structure by plasma process is still limited due to inherent complexity, reproducibility and control problems in practical implementation of plasma processing. Therefore the study on the fundamental physical properties that govern the plasmas becomes more crucial for molecular scale control of film structure and corresponding properties for new generation nano scale film materials development and application. The thin films are formed through nucleation and growth stages during thin film depostion. Such stages involve adsorption, surface diffusion, chemical binding and other atomic processes at surfaces. This requires identification, determination and quantification of the surface activity of the species in the plasma. Specifically, the ions and neutrals have kinetic energies ranging from ~ thermal up to tens of eV, which are generated by electron impact of the polyatomic precursor, gas phase reaction, and interactions with the substrate and reactor walls. The present work highlights these aspects for the controlled and low-temperature plasma enhanced chemical vapour disposition (PECVD) of Si-based films like crystalline Si (c-Si), Si-quantum dot, and sputtered crystalline C by the design and control of radicals, plasmas and the deposition energy. Additionally, there is growing demand on the low-temperature deposition process with low hydrogen content by PECVD. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to ultra high frequency (UHF) and in the range of microwave. In this sense, the necessity of dedicated experimental studies, diagnostics and computer modelling of process plasmas to quantify the effect of the unique chemistry and structure of the growing film by radical and plasma control is realized. Different low-temperature PECVD processes using RF, UHF, and RF/UHF hybrid plasmas along with magnetron sputtering plasmas are investigated using numerous diagnostics and film analysis tools. The broad outlook of this work also outlines some of the 'Grand Scientific Challenges' to which significant contributions from plasma nanoscience-related research can be foreseen.

• Journal of Marine Bioscience and Biotechnology
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• v.7 no.1
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• pp.1-10
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• 2015

Bio diesel has advantages to reduce GHG(Greenhouse Gas) compare with the fossil fuel by using oil comes from plant/animal sources and even waste such as used cook oil. The diversity of energy feeds brings the positive effects to secure the national energy mix. In this circumstance, micro-algae is one of the prospective source, though some technical barriers. We analyzed the bio diesel which was derived from Dunaliella tertiolecta LB999 through the BD100 quality specifications designated by the law. From that result, it is revealed that the oxidation stability is one of the properties to be improved. In order to find the reason for low oxidation stability, we analyzed the oxidation tendency of each FAME components through some methods(EN 14111, EN14112, EN16091). In this study, we could find the higher double bond FAME portion, the more oxidative property(C18:1${\ll}C18:3$) in bio diesel and main unsaturated FAME group is acted as the key component deciding the bio diesel's oxidation stability. It is proved experimentally that C18:3 FAME are oxidized easily under the modified accelerated oxidation test. We also figure out low molecular weight hydrocarbon and FAME were founded as a result of thermal degradation. Some alcohol and aldehydes were also made by FAME oxidation. In conclusion, it is necessary to find the way to improve the micro-algal bio diesel's oxidation stability.

• Journal of the Korean Wood Science and Technology
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• v.34 no.6
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• pp.36-43
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• 2006

Using fluidized bed type fast pyrolysis system (capacity 400 g/h) bio-oils were produced from beech (Fagus sylvatica) and softwood mixture (spruce and larch, 50:50). The pyrolysis was performed for 1~2 s at the temperature of $470{\pm}5^{\circ}C$. Pyrolysis products consisted of liquid form of bio-oil, char and gases. In beech wood bio-oil was formed to ca. 60% based on dry biomass weight and the yield of bio-oil was 49% in soft wood mixture. The moisture contents in both bio-oils were ranged between 17% and 22% and the bio-oil's density was measured to $1.2kg/{\ell}$. Bio-oils were composed of 45% carbon, 47% oxygen, 7% hydrogen and lower than 1% nitrogen,which was very similar to those of original biomass. In comparison with oils from fossil resources, oxygen content was very high in bio-oils, while no sulfur was found. More than 90 low molecular weight components, classified to aromatic and non aromatic compounds, were identified in bio-oils by gas chromatographic analysis, which amounted to 31~33% based on the dry weight of bio-oils.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.424-429
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• 1999

This study was conducted to investigate the characteristics of polysaccharides isolated from the fruit body and cultured mycelia of Phellinus linteus IY001. All fractions were extracted by hot water, followed by ethanol precipitation (F-THE and M-HE) or ultrafiltration (M-HU) (F-TH, F-THE; fruit body, M-HE, M-HU; cultured mycelia). Among these fractions, F-TH fraction was obtained at the highest yields of 6.83% and yield of F-THE was at the level 2.79%. The carbohydrates of these fractions was found to be a heteroglucan composed of glucose, galactose, mannose, fructose, ribose and xylose by analysis of gas chromatography. The total carbohydrate contents of M-HE and M-HU fractions were 99.2%, and 86.0% respectively. The glucose content of M-HE, M-HU and F-THE ranged from 54 to 84.8% of the total monosaccharide. Amino acid pattern showed that all fractions contained a large amount of aspartic acid, glycine, glutamic acid, alanine. Serine and threonine were found to be involved in the linkage, O-linked type. These fractions, except F. TH, contained polysaccharides with the molecular weights of 12 kD and showed the characteristics of IR absorption for ${\beta}-glucosides$ at $890\;cm^{-1}$.

• Korean Journal of Microbiology
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• v.28 no.2
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• pp.91-97
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• 1990

Complementary DNA (cDNA) coding for human cytoplasmic superoxide dismutase (SOD1) (superoxide: superoxide oxidoreductase E.C.1.15.1.1) was isolated from human liver cDNA library of $\lambda$gt11 by in situ plaque hybridization. The insery cDNA gas the 5' untranslational region (UTR) and 3'UTR of SOD1 gene. Polymerase Chain Reaction (PCR) method was used fro subcloning of SOD1 structural gene. Using synthetic sense strand primer (24mer) containing a start codon and antisense strand primer (24mer), SOD1 structural gene was selectively amplified. Amplified DNA was directly cloned into the HincII site of pUC19 plasmid. Insery cDNA was subcloned into M13 mp19 and sequenced by dideowy chain termination method with Sequenase. The nucleotide sequence of insert cDNA had an open reading frame (ORF) coding for 153 amino acid residues. The structural gene of cytoplasmic SOD was placed under the control of bacteriophage $\lambda P_{L}$ regulatory sequences, generating a highly efficient expression plasmid. The production of human SOD1 in E. coli cells was about 7% of total cellular proteins and recombinant human SOD1 possessed its own enzymatic acitivity.

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.199-208
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• 1994

Analytical methods for the determination of the derivatives of the herbicide (${\pm}$)-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) by capillary column gas chromatography with mass spectrometer (GC-MS) and electron-capture detection (GC-ECD) were studied. A successful procedure was introduced for the ester preparation using $H_2SO_4$, as the catalyst and the alcohol 2,2,2-trichloroethanol (TCE) or 2,2,2-trifluoroethanol (TFE). The identificaiton and elucidation of MCPP by GC-MS spectrometry following the esterification with diazomethane, $BF_3$/methanol, $H_2SO_4$/methanol, TCE, TFE, or pentafluorobenzyl bromide (PFB) were carried out. A comparison of the response-sensitivities among those MCPP esters was made with GC-ECD. Although the methylation product of MCPP was confirmed by GC-MS, its low sensitivity to the ECD limited the detection of MCPP. TCE, TFE, and PFB derivatization methods resulted in a high rate of MCPP esterifications and very sensitive ECD molecular responses. Based on efficiency, convenience, worker safety, and least sample contamination, TFE esterificaiton was considered as the superior method for MCPP analysis to the other methods of derivatization. An accurate method is described for quantifying MCPP in soil leachates by GC-ECD at very low concentrations without the requirement of a complicated clean-up process. As a result, MCPP residues at concentrations of less than $0.1{\mu}g$ in 100ml soil leachate were detected.