• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.335-335
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• 2006

Polyacrylonitrile (PAN) was deposited as an adherent film on Cu-substrate by the cathodic electropolymerization. This work is an attempt to compare the molecular weight and the fractured surface of PAN prepared by CV and chronoamperometry. The molecular weight and increase weight of PAN measured the according to AN-concentration, scan rate, and cycle number (or time) using CV and chronoamperometry. The morphology of PAN was characterized by SEM image. Mechanism and optimal conditions for electropolymerization of acrylonitrile on Cu-substrate were investigated and discussed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.543-551
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• 2021

Changes in gluten surface hydrophobicity, which play an important role in the functional characteristics of protein, were measured according to various protein concentrations, pH levels, electrolytes concentrations, and alginate molecular weights using 8-anilino-1-naphthalene sulfonic acid (ANS) as a fluorescent probe. Gluten surface hydrophobicity decreased as gluten concentration increased, reaching a maximum pH of 7.0. The effects of alginate molecular weights and alginate concentration on the surface hydrophobicity, emulsifying activity index (EAI), and emulsion stability index (ESI) of gluten-sodium alginate dispersion (GAD) were measured. Gluten surface hydrophobicity rapidly increased the asl NaCl concentration of gluten solution up to 300 mM and showed no significant increase above 300 mM. However, gluten surface hydrophobicity notably decreased until the concentration of CaCl₂ and MgCl₂ reached 30 mM, indicating no significant variations above 30 mM. GAD surface hydrophobicity increased as the concentration and molecular weight of sodium alginate increased, however, gluten concentration increased as the GAD surface hydrophobicity decreased. The EAI and ESI of GAD increased as both molecular weight and concentration of sodium alginate increased.

• Analytical Science and Technology
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• v.12 no.4
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• pp.306-311
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• 1999

Changes of silk protein compositions of average molecular weight (Mw) and free amino acid composition to different solubility conditions were studied by SDS-polyacrylamide electropholesis, gel permeation chromatography (GPC), and free amino acid analysis method. We can not detected average molecular weight distribution of different hydrochloric acid (HCl) conditions as SDS-polyacrylamide method, but as using GPC method, molecular weight distribution of 2N-HCl, 1N-HCl and 0.5N-HCl (3 hrs at $110^{\circ}C$ treated) are confirmed Mw 800, 1,500 and 3,700, respectively. The average molecular weight of calcium chroride and calcium chloride-enzyme treated samples are shown Mw 46,800 and 12,500, respectively. The degree of hydrolysis and the composition of the free amino acid in the fibroin hydrolysates effected significantly composition of free amino acids of the fibroin powder. The increase of the degree of hydrolysis and ratio of free amino acids and oligopeptides were found to be directly related to the concentration of hydrochloric acid and treatment of enzyme, resulting in the increase of water solubility.

• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.769-779
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• 2020

This study investigates the selective fractionation of lignin with uniform structures and lower molecular weight. Lignin solubilization was first performed using a solution of acetic acid (AA) and hydrogen peroxide (HP) (4:1, (v/v)) to form peracetic acid (PAA), which is a strong oxidant. After the PAA-induced solubilization that occurred at 80℃, totally soluble lignin was extracted by ethyl acetate (EA) and divided into organic- and water-soluble fractions. The EA fraction was then fractionated by open-column using three solutions (chloroform-ethyl acetate, methanol, and water) sequentially. With an increase in the solvent polarity during the fractionation step, the molecular weight of the lignin-derived compounds in the fraction increased. Remarkably, some lignin fractions did not have aromatic structures. These fractions were identified as carboxylic acid-containing polymers like poly-carboxylates. These results conclude that the selective production of lignin-derived polymers with specific molecular weight and structural characteristics could be possible through open-column fractionation.

• Macromolecular Research
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• v.10 no.2
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• pp.85-90
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• 2002

Poly (ethylene oxide)/polylatide/poly(ethylene oxide) (PEO/PL/PEO) tri-block copolymers, which each block is connected by ester bond, were synthesized by coupling reaction of PL with PEO in the presence of pyridine. PL/PEO/PL tri-block copolymer was synthesized by ring opening polymerization of L-lactide initiated by PEO in the presence of stannous octoate. Degradation behavior of the copolymers was investigated in a pH 7.4 phosphate buffer saline (PBS) at 37$\pm$1 $^{\circ}C$. Gel permeation chromatography (GPC) and $^1$H-nuclear magnetic resonance (NMR) were used to monitor the change of mass loss, molecular weight and composition of copolymers. In hydrolytic degradation, the PEO/PL/PEO tri-block copolymer with high PEO contents affected the increase of its mass loss, and resulted in the decrease of its molecular weight as well as PEO composition. However, when PL/PEO/PL and PEO/PL/PEO tri-block copolymers had similar PEO contents, PEO/PL/PEO decreased faster in molecular weight and PEO composition than PL/PEO/PL.

• Carbon letters
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• v.13 no.3
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• pp.133-138
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• 2012

According to kinetic mechanisms, liquid phase polymerization and solid phase polymerization are different in acrylonitrile (AN) polymerization, and so the relationship between the contribution ratio and molecular weight distribution (MWD) was obtained through theoretic analysis. The precipitation homopolymerization of AN was carried out in a mixture solution of dimethyl sulfoxide (DMSO) and water at $50{\sim}65^{\circ}C$ using ${\alpha}$,${\alpha}^{\prime}$-azobisisobutyronitrile as an initiator. The contribution ratio decreased and approached 0; the MWD also decreased and approached 2 with the increase of the $H_2O$/DMSO ratio from 10/90 to 90/10. The experimental data were found to coincide well with the theoretical equation derived from the mechanisms.

• Advances in Traditional Medicine
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• v.1 no.1
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• pp.71-81
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• 2000

High molecular weight water-insoluble chitosan alone has been previously shown to exhibit in vitro stimulatory effect on macrophages nitric oxide (NO) production. However, high molecular weight water-soluble chitosan (WSC) had no effect on NO production by itself. When WSC was used in combination with recombinant $interferon-{\gamma}\;(Rifn-{\gamma})$, there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of WSC on NO synthesis was shown at 24 h after treatment with $rIFN-{\gamma}$. The increased production of NO from $rIFN-{\gamma}$ plus WSC-stimulated RAW 264.7 macrophages was decreased by the treatment with $N^G$ $monomethyl-_L-arginine$. The increase in NO synthesis was reflected, as an increased amounts of inducible NO synthase (iNOS) protein. Synergy between $rIFN-{\gamma}$ and WSC was mainly dependent on WSC-induced nuclear $factor-_KB$ activation. The present results indicate that WSC may provide various activities such as anti-microbial, anti-tumoral, and anti-viral. In addition, since NO has emerged as an important intracellular and intercellular regulatory molecule having functions as diverse as vasodilation, neural communication, cell growth regulation and host defense, it is tempting to hypothesize that this WSC is involved in the local control of the various fundamental processes such as cardiagra, cardiac infarction, impotence etc.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.65-71
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• 2002

Characteristics of corona discharge of the different types of the plasma reactors which are cone-hole and cone-plate is investigated experimentally. The discharge starts at lower voltage for the cathode corona than the anode corona and spark occurs at higher voltage for the cathode corona. And the cathode corona makes more stable discharge than the anode corona. The effect of the base gas in corona discharge for different O$_2$/N$_2$ concentrations is related with the gas molecular weight. The discharge for the smaller molecular weight gas occurs easier than for the high molecular weight gas. The discharge current decreases with the increase of oxygen concentration and it increases more sharply for anode corona than for cathode corona as discharge voltage increases after corona onset voltage. NO-NO$_2$ conversion increases with the energy density of corona discharge and the addition of O$_2$ in a base N$_2$ gas.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.89-95
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• 1998

The aim of this study is to elucidate the anti-microbial activity and anti-oxidative activity of water-soluble chitosan with a molecular weight of 5,000-200,000. Water-soluble chitosans have demonstrated a regular anti-microbial activity on the tested strians by the paper disk method. In the MIC (Minimum Inhibitory Concentration) test, CC-01 (MW=5,000) with the lower MW showed the higher MIC value than the higher MW chitosan. The MW of chitosan increase, the MIC decreases. MICs of 4 chitosans(CC-02∼CC-05) against S. aureusTCC 65389, E coli ATCC 8739, p. aeruginosa, ATCC 9027 and C. albicans ,ATCC 10231 were 7.0-39.O$\mu\textrm{m}$, whereas MICs of chitosans against A. niger were over 2.OmM. Formula containing chitosan showed higher anti-microbial activities than the formula made with the chemical preservatives(Methylparaben 0.2％ and Imidazolidinyl Urea 0.3％). Among 5 water-soluble chitosans, CC-03(MW=92,163) showed the most potent anti-oxidative activity (IC$\sub$50/ : 0.2mM). In conclusion, the water-soluble low molecular weight chitosan could be served as natural preservatives and antioxidant in cosmetics.

• Macromolecular Research
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• v.12 no.1
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• pp.112-118
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• 2004

With the goal of enhancing the creep resistance of ultra-high molecular weight polyethylene (UHMWPE), we performed gamma irradiation and post-irradiation annealing at a low temperature, and investigated the crystalline structures and mechanical properties of the samples. Electron spin resonance spectra reveal that most of the residual radicals are stabilized by annealing at 100$^{\circ}C$ for 72 h under vacuum. Both the melting temperature and crystallinity increase after increasing the dose and by post-irradiation annealing. When irradiated with the same dose, the quenched sample having a higher amorphous fraction exhibits a lower swell ratio than does the slow-cooled sample. The measured tensile properties correlate well to the crystalline structure of the irradiated and annealed samples. For enhancing creep resistance, high crystallinity appears to be more critical than a high degree of crosslinking.