• 대한화장품학회지
• /
• 제24권3호
• /
• pp.89-95
• /
• 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
• /
• 제13권5호
• /
• pp.391-396
• /
• 2005

The polymerization of methyl methacrylate (MMA) was carried out using CuBr/bidentate phosphorus ligand catalyst systems. MMA polymerization with CuBr/phosphine-phosphinidene (PP) exhibited high conversion ($\~80\%$) in 5 h at $90^{\circ}C$ along with a linear increase of ln($[M]_0/[M]$) versus time, indicating constant concentration of the propagating radicals during the polymerization. The molecular weight of the prepared PMMA tended to increase with conversion, suggesting the living polymerization characteristic of the system. On the other hand, a large difference between the measured and theoretical molecular weight and a broad molecular weight distribution were observed, implicating possible incomplete control over the polymerization. This may have been caused by the low deactivation rate constant ($\kappa_{deact}$) of the system. The low $\kappa_{deact}$, would result in irreversible generation of radicals instead of reversible activation/deactivation process of ATRP. Polymerizations performed at different ligand to CuBr ratios and different monomer to initiator ratios did not afford better control over the polymerization, suggesting that the controllability of CuBr/phosphorus ligand system for ATRP is inherently limited.

• 대한기관식도과학회:학술대회논문집
• /
• 대한기관식도과학회 1993년도 제27차 학술대회 초록집
• /
• pp.88-88
• /
• 1993

현재 악성종양의 조직학적 진단에 면역조직화학반응의 검토가 많이 사용되는데 정상상피가 암으로의 진행시 점막상피세포의 주구성 단백성분에 있는 cytokeratin의 발현성에 변화가 일어난다고 알려져 있다. 이 cytokeratin은 현재 19종의 subclass가 알려져 있는데 각 subclass에 대응하는 항체를 이용하여 후두암세포의 기원을 알고 암조직의 분화도를 판정하고자 본 연구를 시행하였다. 연구방법은 정상성대조직 5예, 성대에 국한된 편평세포암 22예를 monoclonal anti-ck Ab와 polyclonal anti-ck Ab를 사용, Avidin-Biotin Peroxidase Complex method로 면역조직화학적 염색을 시행하였다. 그결과 정상후두상피에서 저분자량의 keratin은 표층을 제외한 심층부에서 양성반응을 보였다. 후두의 편평세포암은 상피성종양이며, 저분자량의 항ck 항체는 저분화암에서 양성반응을 보이고 고분자량의 항ck항체는 고분화암에서 양성반응을 보였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2006년도 춘계학술대회
• /
• pp.485-488
• /
• 2006

In order to investigate the possibility of waste mushroom logs as biomass resource chemical and physical characteristics of normal woods and waste mushroom logs such as crystallinity value, energy consumption, total sugar yield after hydrolysis chemical compounds and molecular weight distribution after acid hydrolysis, were examined. In the results, crystallinity of waste mushroom logs which were three year passed after the inoculation was decreased drastically from 49% to 33% during the cultivation. Lignin contents as chemical compounds of normal woods and waste mushroom logs were 21.07% and 18.78%, respectively. By the results of measurement of energy consumption, the size reduction of normal woods required a significantly higher energy than that of waste mushroom logs. In the hydrolysis, total sugar yield by enzyme and acid hydrolysis were high in waste mushroom logs(53% 57.5%) than in normal woods(42.9%, 47.17%). According to the molecular weight distribution using GPC, low molecular weight compounds were distributed in waste mushroom logs. Based on these results, waste mushroom logs have enough potential as material for developing alternative energy because of easily conversion to sugar by various hydrolysis methods and requirement of low energy consumption during size reduction.

• 식품저장과 가공산업
• /
• 제6권2호
• /
• pp.11-13
• /
• 2007

This study relates to low and medium molecular weight isoflavone-${\beta}$-D-glucan produced by submerged liquid culture of Agaricus blazei, a method of producing the isoflavone-B-D-glucan using autolysis enzyme of Agaricus blazei mycelia, and use of the isoflavone-B-D-glucan for anti-cancer and immunoenhancing effect. In acordance with one aspect of the present study, it deals with a method of producing isoflavone-${\beta}$-D-glucan, which comprises the followings; 1) culturing and separating mushroom mycelia, 2) producing low-medium molecular weight isoflavone-${\beta}$-D-glucan from high molecular weight one. The cytotoxicity on human cnacer cell line (Caco-2, MCF-7), the expression of Cyclin D, Bcl-2, Bax protein, p21 protein, p53 protein in MCF-7 cells assessed by SDS-PAGE and immunoblotting, and other immuno related factor such as TNF-a and IL-1B activities were examined. Structural identification of isoflavone-${\beta}$-D-glucan which shoed cytotoxicity against cancer cell and immunoenhancing effects was carried by separation with DEAE-cellulose column chromatography, TLC, HPLC, IR, NMR, Clinical test for the cancer patients (n=119) for 6 month was carried out, and immunoenhancing factors(NK cell number, ratio of T4/T8) were checked. We concluded the identified isoflavone-${\beta}$-D-glucan has immuno enhancing effects and could be useful for cancer chemoprevention.

• Tuberculosis and Respiratory Diseases
• /
• 제38권3호
• /
• pp.228-235
• /
• 1991

Pulmonary surfactant is a lipoprotein complex composed primarily of phospholipid and lungspecific apoproteins that reduces surface tension in the alveolus and maintains alveolar stability at low lung volume. Three families of lung-specific apoproteins have been described: SP-A, a glycoprotein with a reduced molecular weight of 28~36 KDa. SP-B a hydrophobic protein with a nonreduced molecular weight of 18 KDa, and SP-C a hydrophobic protein with a non-reduced molecular weight of 5~8 KDa. Surfactant proteins have important roles in regulating surfactant metabolism as well as in determining its physical properties. The synthesis of the active surfactant peptides appears to be modulated by system with considerable complexity, including numerous levels of regulation such as cell-specific, hormonal and developmental controls. Endotoxin appears to alter surfactant protein mRNAs differentially. It is hoped that the elucidation of the factors controlling the synthesis and metabolism of the surfactant proteins will aid in understanding the pathogenesis of hyaline membrane disease and offer new avenues for the therapy and diagnosis of ther pulmonary disorders as well.

• 공업화학
• /
• 제33권6호
• /
• pp.661-665
• /
• 2022

In this study, 2,5-dichlorobenzophenone was synthesized as a monomer using 1,4-dichlorbenzene, and subsequently, copolymers of benzoyl-p-phenylene and p-phenylene were prepared. The average molecular weight was improved using the low-molecular-weight polymer cutting method. The average molecular weight and glass transition temperature of the synthesized polymers were estimated. The as-prepared polymer was used as a hard coating material, and the coating was conducted on a poly(methyl methacrylate) plate. Furthermore, physical properties of the coatings, such as pencil hardness, adhesive strength, and abrasion resistance, were estimated. As the amount of p-phenylene in the copolymer increased, pencil hardness and abrasion resistance improved. The amount of p-phenylene in the copolymer can be increased to 30 mol% in order to increase the hardness of the coating, and the adhesive strength was insufficient for the copolymers with p-phenylene ratio greater than 35 mol%.

• Environmental Engineering Research
• /
• 제12권5호
• /
• pp.224-230
• /
• 2007

The objectives of this study were to evaluate the change of molecular weight (MW) profiles in natural organic matter (NOM) through various treatment processes (coagulation, granular activated carbon (GAC), and ozonation) using high performance size exclusion chromatography based on ultraviolet absorbance and dissolved organic detection (HPSEC-UVA-DOC). In addition, relationships between MW profiles and disinfection by-production (DBP) formation were evaluated. Each treatment process results in significant different effects on NOM profiles. Coagulation is effective to remove high molecular weight NOM, while GAC is effective to remove low molecular weight NOM. Ozonation removes only a small portion of NOM, while it induces a significant reduction of UV absorbance due to breakdown of the aromatic groups. All treated waters are chlorinated, and chlorination DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs) are measured under formation potential conditions. Both THM and HAA formation potentials were significantly reduced through the coagulation process. GAC was more effective to reduce THM formation compared to HAA formation reduction, while ozonation showed significant HAA reduction compared to THM reduction.

• 한국세라믹학회지
• /
• 제42권8호
• /
• pp.593-598
• /
• 2005

Polycarbosilane was synthesized by the Kumada rearrangement of polydimethylsilane in the presence of zeolite (ZSM-5) as a catalyst at $350^{\circ}C$. The prepared polycarbosilane had very low molecular weight ($M_w=500$), so that it was not suitable to fabricate SiC fiber by melt spinning. Further polymerization of PCS was conducted around $400^{\circ}C$ to obtain spinnable polycarbosilane. After polymerization, the polycarbosilanes were isolated by distillation according to the molecular weight distributions. The PCS with a controlled molecular weight distribution was spun into continuous polycarbosilane green fibers. The PCS green fiber was successfully transformed into silicon oxycarbide fiber. The room temperature strength of the SiC fiber was around 1.5 - 1.8 GPa. The oxidation behavior and the tensile strength after oxidation were also evaluated.

• 한국의류산업학회지
• /
• 제5권5호
• /
• pp.520-528
• /
• 2003

Chitosan was depolymerized by oxidizing agent, hydrogen peroxide ($H_2O_2$) and general properties of resulting low molecular weight chitosan(LMWC) were studied. Effect of amount of $H_2O_2$, ratio of $H_2O_2$/chitosan, and reaction temperature were investigated in preparing LMWC. In addition, the reduction of molecular weight of prepared LMWC were measured after a certain time passage. Pre-swelling treatment of starting chitosan affected uniform and mild reaction of depolymerization and increased the solubility of resulting LMWC. Prepared LMWC (Mw 100,000) showed a decrease in Mw by 25-35%. Prepared LMWC(Mw 60,000-70,000) showed a decrease in Mw by 10-15% after 7 months. Therefore, this depolymerizing process can be concluded desirable in terms of stability. In addition, yellowing of pre-swelling treated chitosan upon time passage was insignificant compared with that of untreated chitosan. Therefore, pre-swelling treatment of chitosan before depolymerization would be beneficial in terms of stability of physical state.