• 한국식품과학회지
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• 제27권3호
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• pp.420-427
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• 1995

저분자 chitosan이 김치의 보존성에 미치는 영향을 조사하기 위해 분자량이 다른 4종류의 저분자 chitosan을 양념을 첨가하지 않은 배추김치의 모델 시스템(소금 농도 2%)에 0.5%씩 첨가하고 $20^{\circ}C$에서 발효시키면서 김치의 특성 변화를 살펴보았다. 동일 발효기간내에서 대조군이 chitosan 첨가군들에 비해 pH는 낮고 총산함량은 높았으며 환원당 함량은 발효 6일까지 대조군이 chitosan 첨가군들에 비해 더 낮은 경향이었다. 유기산 중 malic acid 함량은 발효 4일까지 대조군이 chitosan 첨가군들에 비해 낮은 경향을 보였으며, succinic acid 함량은 발효 2일째에 그리고 lactic acid와 acetic acid 함량은 발효 4일째에 대조군이 chitosan 첨가군들에 비해 높은 경향을 나타냈을 뿐 나머지 발효기간에서는 큰 차이를 보이지 않았다. 또한 propionic acid 함량은 발효 6일 이후에 미량으로 나타났으며, 대조군이 chitosan 첨가군들에 비해 높은 경향을 보여주었다. 총균수, Leuconostoc속 미생물 수, Lactobacillus plantarum의 수는 전 발효기간 동안 대조군이 chitosan 첨가군들에 비해 더 많았으며 특히 chitosan 첨가군들은 대조군과 비교했을때 Leuconostoc속 미생물보다 산패균인 Lactobacillus plantarum의 생육을 훨씬 크게 억제시켰다. Leuconostoc속 미생물 수에 있어서 분자량이 적은 chitosan 첨가군들이 분자량이 큰 chitosan 첨가군들에 비해 적은 경향이었으며 Lactobacillus plantarum의 수는 chitosan 첨가군들간에 큰 차이를 보이지 않았다. 관능검사로 조사한 신맛과 군덕내는 대조군이 chitosan 첨가군들에 비해 강했으며, 경도는 큰 차이를 보이지 않았으나 대조군이 더 약하게 평가되었다. 또한 이취는 전 실험군에서 모두 약하게 평가되어 이취는 chitosan에 의해 큰 영향을 받지 않는 것으로 나타났다.

• 원예과학기술지
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• 제30권2호
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• pp.137-143
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• 2012

Chinese cabbage plant was grown hydroponically for 4 weeks in order to examine the temporal relationship of calcium concentration of the nutrient solution with calcium content in the leaf tissue and susceptibility of the tissue to soft rot disease by $Pectobacterium$ $carotovorum$ ssp. $carotovorum$ (Pcc). Calcium concentration from 0.5 to 32.0 mM was maintained for 1 week using Hoagland & Arnon solution. The calcium content of the leaf was proportionally increased to the concentration of the nutrient in the solution (r = 0.912). In contrast, the severity of soft rot symptom in the young leaves was inversely related with the amount of calcium supplied to the nutrient solution (r = 0.899). Water-soluble chitosan, prepared by hollow fiber filtration (> 100 kDa) was applied into the nutrient solution from 0.0 to 5,000 ppm. The chitosan of 10 ppm was the most effective to promote calcium uptake of the leaf, showing 155% of the control. The same chitosan solution prohibited most soft rot development of the leaf by Pcc, exhibiting only 53% of the control. Among different molecular weight fractions, chitosan fraction obtained from 30-100 kDa molecular weight cut-off promoted calcium uptake the most up to 163% of the control, and reduced the development of soft rot disease recording merely 36% of the control of the leaf tissue. The results obtained in the present study suggest that large scale production of water-soluble chitosan with an optimum molecular weight and its commercial application to Chinese cabbage production will be important to improve yield and quality of the crop.

• 폴리머
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• 제32권6호
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• pp.566-572
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• 2008

메탈로센 [(TMDS)$Cp_2$]$ZrCl_2$, 촉매 1과 Exxon 촉매인 [$(n-Bu)_2Cp_2$]$ZrCl_2$, 촉매 2를 사용하여 폴리에틸렌 왁스를 제조하였다. 분자량을 조절하기 위하여 수소를 연쇄이동제로 사용하였다. 실험결과 수소의 주입량이 증가할수록 중합활성의 감소 생성된 폴리에틸렌 왁스의 분자량과 분자량 분포의 감소 그리고 폴리에틸렌 왁스의 융점 저하가 관찰되었다. 수소의 주입으로 폴리에틸렌의 분자량은 1500, 융점은 60 $^\circ$C까지 조절이 가능하였다. 수소의 양을 조절함으로써 메탈로센을 통해 분자량분포가 좁고 융점이 낮은 고품질의 폴리에틸렌 왁스의 제조가 가능하였다. 본 연구실에서 개발된 촉매 1은 알려진 가장 우수한 메탈로센인 촉매 2와 폴리에틸렌 왁스 제조에서 경쟁이 가능한 유사한 특성을 보였다.

• 한국식품영양과학회지
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• 제36권4호
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• pp.503-513
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• 2007

The obese population has been increasing worldwide and obesity has become one of the socioeconomic problems. Obesity raises more concerns as more studies regarding its direct and indirect relativity to several diseases such as type II diabetes, hypertension, etc. are published. Since leptin, an important signal in the chronic control of food intake and energy expenditure, was discovered in 1994, there has been a great accumulation of knowledge on fighting obesity by facilitating pharmacological and nutritional strategies on the molecular level of the body weight control system. In particular, evidences are accumulating that particular food components affect our physiological function and gene expressions which are associated with body weight control. In this study, we review the four mechanisms for weight control and antiobesity functional agents such as HCA, L-carnitine, CLA, chitosan, calcium supplements capsaicin contained in red pepper, and oriental herbal mixture. We also describe about the efficacy and working mechanism of these functional agents on the basis of antiobesity mechanisms.

• Biomolecules & Therapeutics
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• 제18권1호
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• pp.111-121
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• 2010

In order to investigate the preliminary repeat oral dose toxicity and to determine the highest dosage for further 4-week repeated dose toxicity test, Low Molecular Weight Fucoidan (LMF) has been showed various pharmacological effects, was orally administered to female and male rats, once a day for 14 days at dose levels of 2,000, 1,000, 500 and 0 (vehicle control) mg/kg (body weights) in a volume of 10 ml/kg. The mortality and changes on the body weights, clinical signs, hematology, serum biochemistry and gross observations were monitored with organ weight and histopathology of principle organs. As the results of 14-day repeated oral treatment of LMF, no LMF treatment related mortalities were detected up to 2,000 mg/kg in both male and female rats, respectively. In addition, no noticeable changes on the body weight and clinical signs were detected except for significant decreases on the body weights and gains restricted to male 2,000 mg/kg treated groups as compared with male vehicle control. No meaningful changes on the organ weights, hematological, serum biochemistrical, gross and histopathological findings were observed. Therefore the highest dosage in the 4-week repeated dose toxicity test is suggested as 2,000 mg/kg in both female and male rats, respectively.

• Asian-Australasian Journal of Animal Sciences
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• 제18권12호
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• pp.1775-1779
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• 2005

Seventy-two crossbred gilts of approximately 33 kg initial weight were used in this study. The gilts were randomly assigned into three groups. The three dietary treatments were basal diet only (control group), basal diet+10 mg/kg lead, and basal diet+10 mg/kg lead+0.5% particulate montmorillonite (PM). The results showed that the addition of lead to the diet decreased significantly the body weight and feed efficiency, but PM could restore body weight and feed efficiency of gilts compared to the Pb exposure group. There were no significant differences in weights of ovaries and uteri with addition of either lead or PM to the diet. Supplementing the lead in the diet of gilts also significantly increased the concentration of lead in blood, decreased circulating lutenizing hormone (LH) and estradiol (E$_2$) levels in serum, the addition of PM to the diet effectively adsorbed and lowered lead concentration in the blood. These data suggested that lead disrupts the signals between the hypothalamus and pituitary gland in gilts, and possibly suppressed the secretion of relative growth hormone and sex hormone. On the other hand, PM may ameliorate Pb toxicity in pigs.

• Toxicological Research
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• 제24권1호
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• pp.79-86
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• 2008

This study was conducted to obtain information of the oral dose toxicity of low molecular fucoidan (LMF) in male and female mice. In order to calculate 50% lethal dose ($LD_{50}$) and approximate lethal dose (LD), test material was once orally administered to male and female ICR mice at dose levels of 2000, 1000, 500, 250, 125 and 0 (vehicle control) mg/kg (body wt.). The mortality and the changes on body weight, clinical signs, gross observation and organ weight and histopathology of principle organs were monitored 14 days after LMF treatment. We could not find any mortalities, clinical signs, body weight changes and gross findings. In addition, significant changes in the organ weight and histopathology of principal organs were not observed except for some sporadic findings. The results obtained in this study suggest that LMF may not be toxic in mice and may be therefore safe for clinical use. The $LD_{50}$ and approximate LD in mice after single oral dose of LMF were considered over 2000 mg/kg in both female and male mice.

• Archives of Reconstructive Microsurgery
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• 제2권1호
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• pp.77-81
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• 1993

Free tissue transplantation is commonly performed with the brilliant achievement in microsurgery and anticoagulants and antithrombotic agents have been prescribed in the procedures. However, there is no clean-cut indication as to which agents would be more effective in every steps and final consequences. Low molecular weight heparins inhibiting coagulation in plateletrich plasma and acting on the vascular endothelium have antithrombotic and fibrinolysis action. The experiment with rat groin free flap transplantation after 6-hour ischemia and injection of the low molecular weight heparin was performed and the results between the injection and non-injection group were analysed as follows, 1. Both of the 24-hour groups, vessel patency was not proportional to color change of the groin flap. 2. On the second day after anastomois, heparin-injection group showed intact intima, patent lumen without thrombus, and mild granulomatous inflammation around the suture material and control group with doubtful patency revealed intimal loss and thrombus formation. 3. On the 5th, 7th, and 9th postoperative day, heparin group was patent in anastomosis and showed acute inflammatory cells. 4. The 7th-week period, heparin-injection group showed intact flap color, patent lumen with intact intima and persistent foreign body granuloma.

• 한국환경보건학회지
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• 제27권2호
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• pp.60-66
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• 2001

Natural organic matters(NOMs) are found everywhere such as soil, surface and ground waters and consist of both humic and nonhumic components, and their heterogeneith makes each source unique. This study was carried to evaluate the removal characteristics of NOMs by mixing coagulants and the variation of apparent molecular weight distribution(AMWD) in coagulation process. Ratio of optimum coagulants dosage for removal of DOC and turbidity by mixing coagulants was 1.83 mM F $e^{3+}$/mM $Al^{3+}$. DOC removal increased at lower pH. The pH6 control focused on the removal of organic matters could reduce the amount of coagulant consumption by 2 to 3 times based on the pH8.5 of natural water. The dissolved organic matters in the natural water from the mid-stream of Han River were composed of the low molecular weight(LMW,<1 K) of 59.7%, and the medium and high molecular weight(M.HMW, 1~30 K) of 40.3%, respectively. At pH6, the DOC removal efficiencies of LMW(<1 K) and M.HMW(1~30 K) in coagulation process were 27~35%, 62~72%, respectively. The fraction smaller than 1 K was not eliminated to a noticeable degree, while the fraction of 1~30 K was relatively well removed. In conclustion, mixing coagulants were fairly effective in the removal of natural organic matter.r.

• 환경위생공학
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• 제20권2호
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• pp.33-38
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• 2005

Chitosan is a dietary fiber because of a linear polysaccharide composed of $\beta-(1{\rightarrow}4)$-linked 2-amino-2-deoxy-D-glucopyranose. In this study, control release system of vitamin C has been estimated in chitosan molecular network as a vitamin C carrier of controlled release. The amount of released vitamin C were decreased in higher amount of chitosan concentration. Especially, vitamin C were slowly released from chitosan solution in dialysis membrane when compared with vitamin C solution alone in dialysis membrane. These result assumed that chitosan driving force is dependent on chitosan molecular weight and cationic property of amino group with anionic property of vitamin C.