• Archives of Pharmacal Research
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• 제29권9호
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• pp.795-799
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• 2006

Peptides, although high efficacy and specificity in their physiological function, usually have low therapeutical activities due to their poor bioavailability when administrated orally. Nanoparticles have been regarded as a useful vector for targeted drug delivery system because they can protect drug from being degraded quickly and pass the gastrointestinal barriers. Here we described a novel oral N-trimethyl chitosan nanoparticles formulation containing thymopentin (Tp5-TMC-NP). N-trimethyl chitosan (TMC) was synthesized and then used to prepare Tp5-TMC-NP by ionotropic gelation. A three-factor, five-level CCD (Central Composite Design) design was used in the optimization procedure, with HPLC as the analyzing method. The resulting Tp5-TMC-NP had a regular spherical surface and a narrow particle size range with a mean diameter of 110.6 nm. The average entrapment efficiency was 78.8%. The lyophilized Tp5-TMC-NP formulation was stable in $4^{\circ}C\;or\;-20^{\circ}C$ after storage of 3 months without obvious changes in morphology, particle size, pH and entrapment ratio. The results of the flow cytometer determination showed that the ratio of $CD4^+/CD8^+$ of Wistar female rat given Tp5-TMC-NP (ig) was 2.59 time that of the group given Tp5 (ig).

• 폴리머
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• 제25권3호
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• pp.375-384
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• 2001

불포화 폴리에스테르(unsaturated polyester: UP)의 희석제로 많이 사용되는 스티렌 단량체 (SM)대신에 단일 중합체의 유리전이온도가 낮은 비닐 아세테이트(VAc), 메틸 아크릴레이트(MA)를 SM과 혼합하여 사용하였을 때 혼합초성에 따른 UP의 기계적 물성 변화를 조사하였다. SM/MA 혼합계는 MA함량 증가에 따라 전체적으로 강인성의 향상이 나타난 반면, SM/VAc 혼합계의 경우에는 VAc 단량체치 함량 증가에 마른 강인성의 향상을 기대하기가 힘든 것으로 나타났다. 이러한 현상은 전체 계의 유리전이온도의 저하 효과와 상분리에 의한 응력 완화 효과에 미치는 각 단량체의 영향이 서로 다르기 때문인 것으로 해석되었다.

• 한국세라믹학회지
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• 제52권6호
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• pp.449-454
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• 2015

The fabrication process of zirconia gel-casting was studied to obtain dense zirconia on a large scale or with complicated shapes. As an experimental parameter, two different particle sizes ($0.1{\mu}m$ and $0.7{\mu}m$) of zirconia powder were applied to the gel-casting process. The viscosity behavior of slurries incorporating 40 vol% of zirconia powder was examined as a function of the dispersant content and the solid load to determine the optimum dispersion conditions. In addition, the gelation time with an initiator, the de-binding behavior, and the main factors affecting densification were examined. The densification of the gel-casted zirconia green body depended on the mixing ratio between the monomer and the dimer and on the zirconia particle size. A green body with a small particle size of $0.1{\mu}m$ showed less densification, with a relative density of 93%. This may be due to the excess number of bubbles created through interactions between the larger particle surface and polymer additives during the ball-milling process.

• Journal of the Korean Wood Science and Technology
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• 제26권1호
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• pp.29-37
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• 1998

Alkali-soluble extracts were prepared from medium-sized barks of Radiata pine(Pinus radiata). There are difficulties in the production of extracts with uniform quality and in the preparation of adhesives with suitable viscosity. Ultrafiltration using an Amicon cell was subjected to fractionate extracts according to molecular sizes in order to overcome the above problem. The filtration efficiency was studied by using thin channel filtration systems. Adhesive manufacturing was also examined. Removal of particles greater than 0.45m from the extracts increased both filtration speed (flux) and yields of solids in the filtrates. Ultrafiltration with PM 10 membrane was very effective to fractionate and concentrate the extracts. Stiasny precipitates from the filtrates obtained by PM 10 membrane were very lower than that(83%) of the retentates. This ultrafiltration method was efficient for obtaining high yield purified phenolic compounds(mainly polyflavanoids) and thus important for preparing wood adhesives from barks. The extracts were shown excessive high viscosities at the concentrations required for adhesive formulation, but this high viscosity and short gelation time was reduced by lowering pH of the extracts and addition of urea. The highest bonding strength of plywoods(340g/$m^2$ of adhesive spreads) was achieved with adhesive formulated by 100parts of mixed alkali extracts and urea(70/30,w/w), 10parts of p-formaldehyde and 3.5parts of wheat flour at pH 6, and by hot pressing at the conditions of 12kg/$cm^2$ at $120^{\circ}C$ for 10 minutes.

• 한국축산식품학회지
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• 제18권1호
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• pp.9-18
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• 1998

This study was performed to obtain a large quantity of $\alpha$-lactalbumin ($\alpha$-LA) from milk by an improved separation and purification method. Functional properties-solubility viscosity, emulsifying activity, foamability surface hydrophobicity and gelation-of the purified $\alpha$-LA were investigated, $\alpha$-LA was purified in a large quantity by DEAE-Sephacel chromatography using 0.15M NaCl in 20mM Tris-HCl buffer(pH 7.2), as an eluent. The yield and purity of the purified $\alpha$-LA were 23.6%, 92.5%, respect-ively. The solubility viscosity and emulsifying activity of the purified $\alpha$-LA were 92.2$\pm$2% 3.46$\pm$0.19 cP and 345$\pm$5.0m^2$-/g respecively. The foamability of $\alpha$ -LA was 762 after 5min whipping which was lower than that of WPC and showed decreasing tendency with whipping time. The relative surface hydrophobicity of the $\alpha$-LA was formed when a 10% $\alpha$-LA solution containing 100mM NaCl and 20 mM $CaCl_2$ was heated at 92$^{\circ}C$for 40min. The $\alpha$-LA gel showed 31.5 as hardness and showed low springiness and cohesiveness.

• Macromolecular Research
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• 제16권3호
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• pp.189-193
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• 2008

Thermal cross-linking method of poly(vinyl alcohol) (PVA) using poly(acrylic acid) (PAA) was carried out on PVA/PAA hydrogels. The level of gelation was measured in the PVA/PAA hydrogels with various PAA contents. The swelling behavior at various pHs showed that the swelling kinetics and water contents of the PVA/PAA hydrogels reached equilibrium after 30 h, and the time to reach the equilibrium state decreased with increasing PAA content in the hydrogel. The water content increased with increasing pH of the buffer solution. The permeation and release of the drug were tested using indomethacin as a model drug. The permeated and released amounts of the drug increased with decreasing the PAA content because of the low free volume in the hydrogel due to the higher cross-linking density. The kinetic profile of drug release at various pHs showed that all samples reached the equilibrium state within the 5 h.

• Journal of the Korean Wood Science and Technology
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• 제47권2호
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• pp.221-228
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• 2019

This study reports the performance of urea-formaldehyde (UF) resins prepared at two different low formaldehyde/urea (F/U) mole ratios with different numbers of urea addition during synthesis. The second or third urea was added during the synthesis of UF resins to obtain two different low molar ratios of 0.7 and 1.0, respectively. The molecular weights, cure kinetics, and adhesion performance of these resins were characterized by the gel permeation chromatography, differential scanning calorimetry, and tensile shear strength of plywood, respectively. When the number of urea additions and F/U molar ratio increased, the gelation time decreased, whereas the viscosity and molecular weight increased. Further, the UF resins prepared with the second urea and 1.0 molar ratio resulted in greater activation energy than those with third urea and 0.7 molar ratio. Tensile shear strength and formaldehyde emission (FE) of the plywood that bonded with these resins increased when the number of urea additions and molar ratio increased. These results suggest that the UF resins prepared with 0.7 molar ratio and third urea addition provide lower adhesion performance and FE than those resins with 1.0 mole ratio and the second urea addition.

• 자원리싸이클링
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• 제5권3호
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• pp.56-64
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• 1996

탄산칼슘의 다형 제어를 목적으로 합성 음료, 의약품 등으로서도 폭넓게 이용되고 있는 ${C_2}{H_4}{OH}$계에서 수산화칼슘을 현탁시키고 감미제, 의약품 등의 용도로서도 이용되고 있는 에틸렌글리콜을 첨가하면서 탄산칼슘 생성 및 탄산칼슘 다형결정화 특성에 대해 연구하였다. 세라믹 bubble plate를 부착 제작한 반응기를 사용하여 $CO_2$gas와 반응 진행시 전기전도도의 연속 측정을 통해 변화시점에서 일부 현탁액을 분리 분말화하여 X선 회절 및 전자현미경을 통해 중가 생성물과 이들이 각각 Vaterite, Aragonite, Calcite로 전이됨을 확인하였다. ${C_2}{H_4}{OH}$에 대한 에틸렌글리콜 첨가를 10 vol%로 하여 500ml의 반응 현탁액에 10~50g의 수산화칼슘 첨가 변화에 따른 생성물을 조사하였다. 결정화단계에서 수산화칼슘 10g 첨가시를 제외하고는 모든 조건에서 겔화(gelation)가 일어나며 그 생성 유지시간은 수산화칼슘 양이 많아질수록 짧아짐을 관찰할 수 있었다. 상온 상압하에서 생성되기 어려웠던 Vaterite가 $Ca(OH)_2$의 30g 첨가반응계에서 구형으로 생성됨을 확인할 수 있었다. 이는 칼슘계, 흡착제 등의 가능성을 부여한 복합재료로서의 Vaterite 합성을 상온 상압화에서${C_2}{H_4}{OH}$ 계에서 다형제어 할 수 있음을 보여주었다. 탄산칼슘의 동질이상중 Vaterite는 준안정상이고 분말화 과정에서 이미 Calcite로 전이되기 쉬우나 G5 glass filter와 vacuum drier를 사용하여 안정적인 구형의 Vaterite을 확인할 수 있었다.

• 한국식품과학회지
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• 제7권3호
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• pp.109-114
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• 1975

국내산 한천원조(寒天原藻)로서 남해(南海), 완도(莞島), 여수(麗水)지역에서 수집한 꼬시레기에 대하여 전처리(前處理)방법에 따른 한천의 수율(收率)과 품질특성(品質特性)을 분석한 결과는 다음과 같다. 원조(原藻)의 전처리(前處理)과정에서 고온(高溫)알칼리 처리는 알칼리의 농도가 높을수록 수율(收率)이 증가하였으나 처리시간은 한시간이 최적(最適)이었다. 산(酸)처리에서는 산(酸)농도가 높을수록 또 처리시간이 길수록 수율(收率)이 증가하였다. 상온(常溫)알칼리 처리에서는 알칼리의 농도가 높을수록 또 처리시간이 길수록 수율(收率)이 약간씩 감소하였다. 한천(寒天)제품의 품질특성(品質特性)을 보면 전처리과정에 의하여 전질소, 조회분은 크게 감소하였다. 한천(寒天)제품의 제리강도(强度), 젤화능력(化能力), 젤화온도(化溫度), 점도(粘度)는 고온(高溫)에서 원조(原藻)의 알칼리처리조건이 강할수록 증가하는 경향이 있었으며 유황함량과 제리강도(强度)는 고도(高度)의 부(負)의 상관(相關)관계를 나타내었다. 원조(原藻)의 상온(常溫)알칼리처리는 처리조건에 따라 한천의 품질향상(品質向上)에 있어서 큰 차이가 없었으며 고온(高溫)알칼리처리와 유사한 효과(效果)를 나타내지 못하였다.

• 한국식품과학회지
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• 제53권4호
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• pp.479-485
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• 2021

감초 추출물의 항산화 안정성을 증진시키기 위하여 키토산의 ionic gelation 특성을 이용한 감초 추출물을 함유한 키토산/TPP 나노캡슐을 제조하였다. 먼저 반응표면분석을 통해서 감초 추출물의 항산화활성을 최대로 할 수 있는 추출조건을 최적화하였다. 감초의 최적 추출조건은 83.01% 에탄올 농도에서 32.6분 동안 추출하는 것으로 결정되었으며, 최적 조건에서 제조된 감초 추출물의 총 플라보노이드 함량과 항산화 활성은 각각 20.47 ㎍ RE/mg과 22.32%/mg로 관측되어 예측값과 모두 표준편차 범위 내에 있음을 확인하였다. 다양한 감초 추출물과 키토산 농도에서 나노캡슐을 제조한 결과, 약 280-370 nm 범위의 캡슐크기를 나타냈으며 0.3 이하의 PDI를 나타내어 전반적으로 균일한 나노캡슐이 형성 되는 것으로 확인되었다. 포집효율 및 함유효율을 고려하여 감초 추출물과 키토산 농도를 각각 0.8과 2.0 mg/mL로 결정하였다. 지방과산화 억제능을 통한 APF 측정 결과, 나노캡슐화되지 않은 감초추출물은 반응 후에 급격히 상승되어 반응 4시간에 가장 높은 APF를 나타낸 후 급격히 감소된 반면, 감초 추출물 나노캡슐은 초반에는 약한 APF를 나타내다가 꾸준히 증가한 후 유지되어 반응 6시간 이후에는 모든 농도에서 유리 감초 추출물보다 유의적으로 높은 항산화 활성을 나타냈다. 따라서 감초 추출물은 키토산 나노캡슐화에 의해서 산화 안정성이 향상됨으로써 항산화 활성의 유지기간이 증진됨을 확인하였다. 본 연구를 통해서 키토산 나노캡슐화는 감초추출물의 항산화 안정성 증대에 효과적으로 활용될 수 있을 것으로 판단된다.