• Korean Journal of Food Science and Technology
• /
• v.40 no.4
• /
• pp.470-473
• /
• 2008

This study examined the enzymatic digestion, average molecular weight distribution and structural changes of Bombyx mori silk gland fibroin using gel penneation chromatography and nuclear magnetic resonance methods. The pure-separation of calcium chloride-treated fibroin hydrolysates was carried out by gel filtration chromatography. Also, the effects of fibroin's enzymatic hydrolysis were investigated using an edible enzyme. The average molecular weight of three hydrolysate samples (silk gland fibroin (SF), SF-calcium chloride (SFC), and SFC-enzyme) were measured to compare their characteristics. The molecular weights of SF, SFC, and SFC-enzyme were approximately 108,000, 65,000, and 1,000 Da, respectively. Finally, we determined the structural characteristic changes of the different enzymatically digested samples by $^{13}C$ nuclear magnetic resonance methods. For the enzymatically digested fibroin, the glycine $^{13}C^{\alpha}$ resonance indicated that the amino acid was dramatically changed and/or separated out; however, this was not shown for the normal Bombyx mori silk gland fibroin.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10a
• /
• pp.263-266
• /
• 1996

A method to determine an optimal temperature trajectory that guarantees polymer products having controlled molecular weight distribution and desired values of molecular weight is presented. The coordinate transformation method and the optimal control theory are applied to a batch PMMA polymerization system to calculate the optimal temperature trajectory. Coordinate transformation method converts the original fixed-end-point, free-end-time problem to a free-end-point, fixed-end-time problem. The idea is that by making the reactor temperature track the optimal temperature trajectory one may be able to produce polymer products having the prespecified physical property in a minimum time. The on-line control experiments with the PID control algorithm have been conducted to establish the validity of the scheme proposed in this study. The experimental results show that prespecified polymer product could be obtained with tracking the calculated optimal temperature trajectory.

• Polymer(Korea)
• /
• v.24 no.4
• /
• pp.469-476
• /
• 2000

The miscibility between acrylic copolymers and tackifier resins influenced on adhesion properties of PSA. PSA with high molecular weight and narrow molecular weight distribution of acrylic copolymers showed systemical modification of adhesion properties of PSA by tackifier resins only in case of miscible system. It is concluded that the investigation of the miscibility between two Components is very important to adhesion properties of PSA.

• Macromolecular Research
• /
• v.11 no.6
• /
• pp.514-517
• /
• 2003

In the solution polymerizations of methyl methacrylate with (${\alpha}$-diimine)nickel(II)/methylaluminoxane (MAO), we observed effects of the position of two methyl substituents in the ligand on both the activities of the catalysts and the polymer microstructure. ${\alpha}$-Diimine nickel(II) catalysts gave syndiotactic-rich poly(methyl methacrylate) with high molecular weight and narrow molecular weight distribution.

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2005.06a
• /
• pp.259-262
• /
• 2005

This study aims to identify the relationship between characteristics of aqueous organic matter and chlorination by-products formation potential according to temporal effect of Juam reservoir in Sun-Choen. The molecular weight distribution and chemical composition of precursors and their relationship with disinfection by-products(DBPs) were investigated. Most of the organic matters was responsible for the major DBP precursors in the raw water are small compounds with a molecular weight less than IKDa, Aromatic contents determined by SUVA correlated well with DBPs, THMs, and HAAs formation. Especially, THMFP/DOC showed better correlation with SUVA than HAAFP/DOC and DBPFP/DOC with SUVA in Juam reservoir. Therefore, effective removal of small molecules or hydrophobic organic matter prior to disinfection process will significantly reduce the DBP concentration in the finished water.

• The korean journal of orthodontics
• /
• v.9 no.1
• /
• pp.9-14
• /
• 1979

The purpose of this study was to pursue the biosynthesis of proteins of human and bovine periodontal ligaments in vitro system. The excised periodontal ligaments from human and bovine were incubated in Krebs-glucose medium containing $^3H$-proline. After incubation the incubated periodontal ligaments were homogenized and the proteins were treated with 0.1%sodium dodecyl sulfate and $\beta$-mercaptoethanol. Separation of the protein fractions was performed with agarose gel column chromatography and SDS acrylamide gel electrophoresis. The results indicated as follow: 1. Only a small percentage of $^3H$-proline incorporated into proteins was hydroxylated to $^3H$-hydroxyproline. 2. The labeled proteins in periodontal ligaments showed a wide distribution of molecular weight. But only small amounts of labeled protein were found that were characteristics of the molecular weight of collagen. 3. In all of the combined fractions of gel filtration, the degree of hydroxylation was small.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.312-315
• /
• 2004

In this paper we investigated the behavior of low molecular weight silicone fluids in silicone rubber by W treatment with solvent-extraction and GPC. It was shown that LMW quantity which was extracted by solvent-extraction was decreased in UV treatment time. $200{\sim}450\;g/mol$ distribution of LMW silicone fluid was contributed to recovery. It was similar to result from corona discharge. Morphological analysis was investigated by scanning electron microscope(SEM) and X-ray diffraction (XRD). The behavior of LMW silicone fluids in silicone rubber which was contributed to recovery was discussed.

• Macromolecular Research
• /
• v.14 no.4
• /
• pp.424-429
• /
• 2006

The synthesis of a series of poly(POSS-NBE-b-MTD) copolymers was successfully accomplished, taking advantage of sequential, ring-opening, metathesis block copolymerization using $RuCl_2(=CHPh)(PCy_3)_2$ catalyst. By using cyclopentyl-POSS-norbornene (POSS-NBE) monomer as the first block in the block copolymer, living poly(POSS-NBE) with controlled molecular weight and narrow molecular weight distribution was produced. Then, poly(POSS-NBE-b-MTD) copolymers were successfully prepared, in which sequential monomer addition of methyltetracyclododecene (MTD) to the living poly(POSS-NBE) chain ends was utilized to achieve quantitative crossover efficiency. Characterization by $^1H$ NMR spectroscopy and GPC confirmed the high definition and structural integrity of the poly(PO$S-NBE-b-MTD) copolymers. Thermal properties-and morphologies of the POSS-containing block copolymer nanocomposites were also investigated by using thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and wide-angle X-ray scattering (WAXS).

• Journal of Sericultural and Entomological Science
• /
• v.42 no.2
• /
• pp.104-108
• /
• 2000

To hydrolyze insolule sericin the enzyme hydrolysis was used, and then obtained the results as given belows. When insoluble sericin was hydrolyzed by enzyme treatment, the solubility was best at pH 7, 60$\^{C}$ and was slightly increased both above 2 hours treatment and above 10% of enzyme concentration. As the results of electrophoresis, the distribution of molecular weight of sericin powder obtained by enzyme hydrolysis was very weak and showed in the wide range having no distinguishable band. Average degree of polymerzations (A.D.P.) of sericin hydrolyzed by enzyme were about 4.1∼6.3, average molecular weight were about 470∼730. The whiteness of the sericin powder obtained by enzyme hydrolysis was high and increased slightly with higher treatment concentration of enzyme. As the results of amino acid analysis, the amino acid analysis, the amino acid composition of the sericin powder from the enzyme treatment were similar to which located at near 230$\^{C}$ and 320$\^{C}$. The peak of near 230$\^{C}$ could not been found in the sericin powder obtained by enzyme hydrolysis.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.2
• /
• pp.501-504
• /
• 2014

A thermoresponsive polymer, poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), was successfully synthesized by atom transfer radical polymerization (ATRP). Different amounts of 1,3-propanesultone were used as quaternization agent to transit the PDMAEMA into partially modified poly(zwitterions), resulting in p[DMAEMA-co-3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate] (PDMAEMA-co-PDMAPS). Molecular weight, molecular weight distribution, and degree of quarternization were determined by gel permeation chromatography (GPC) and 1H NMR spectroscopy. The transmission spectra of the 1.0 wt % aqueous solutions of the resulting polymers at 650 nm were measured as a function of temperature. Results showed that the lower critical solution temperature (LCST) and the upper critical solution temperature (UCST) could be easily controlled by the different composition of dimethylamino and zwitterion groups. The effect of partial quaternization on thermoresponsive properties was also studied by dynamic light scattering (DLS) with the same aqueous concentration (1.0 wt %) as employed for turbidimetry studies. The LCST and UCST values measured by DLS correlated well with those determined by turbidimetry.