• Archives of Pharmacal Research
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• 제29권12호
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• pp.1171-1178
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• 2006

This study examined the effects of flavors, which are usually added to improve the appeal of pharmaceutical agents, on the viscosity and gelling point of 18% (w/w) aqueous poloxamer 407 solutions. Monoterpenes, esters, alcohols, aldehyde ketones and lactone type flavors were examined. The concentrations of flavor ranged from 0.1 to 1.0%(w/w). After adding a flavor to the aqueous poloxamer 407 solution, the viscosity of the solution was measured using a Brookfield viscometer, and the gelling point was determined from the viscosity vs. temperature plot. The gelling point of the aqueous poloxamer 407 solution decreased with increasing concentration of flavors except for coumarin, vanillin and ethylvanillin. Thermal analysis with DSC showed an interaction between the flavors and poloxamer 407. These results suggest that the flavors bind to the hydrophilic end chains of poloxamer 407, which increases the viscosity, causing gelation at lower temperatures.

• Applied Biological Chemistry
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• 제38권2호
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• pp.147-150
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• 1995

에탄올처리 찰가자미껍질 젤라틴의 젤라틴농도, pH, 정치온도 및 시간과 같은 겔화조건에 대한 물리적 특성 및 색조의 변화를 측정하였다. 젤라틴의 농도가 증가할수록 겔강도, 녹는점과 같은 물리적 특성은 증가하였고, 일정농도에서의 이러한 값들은 에탄올처리한 젤라틴이 무처리한 젤라틴에 비하여 컸다. 젤라틴 졸의 pH가 에탄올처리한 젤라틴의 경우 6.0일 때, 무처리한 젤라틴의 경우 5.0일 때, 겔강도, 졸화온도 및 겔화온도가 가장 높았고, 이를 벗어난 $pH\;5.0{\sim}7.0$의 범위에서는 서서히 감소하였으며, pH 5.0이하 및 pH 9.0이상에서는 급격히 감소하였다. 젤라틴 졸을 겔화시키기 위하여 정치시키는 온도의 경우 낮을수록, 정치시키는 시간의 경우 길어질수록 겔강도 및 졸화온도는 높았다. 겔화조건을 동일하게 하였을 때 에탄올처리한 젤라틴이 무처리한 젤라틴보다 물리적 특성값이 높게 나타났다.

• Korea-Australia Rheology Journal
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• 제11권4호
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• pp.275-278
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• 1999

Soft polymeric materials have gained importance in recent years, namely in food, pharmaceuticals, photographic media, adhesives, vibration dampeners and superabsorbers (to name a few), but also as inter-mediates for selforganization of molecules or supramolecules into long range order. Many of these soft materials are close to their gel point, i.e. they are liquids just before reaching their gel point or they are solids which have barely passed the gel point. New rheological methods need to be developed for the understanding of these soft materials; the typical liquid properties (viscosity) and typical solid properties (modulus) are not applicable since they diverge at the gel point. This will be discussed in the following. Fortunately, chemical gelation experiments with model polymers has given insight into the behavior at the gel point (Winter and Mours, 1997). This knowledge of the critical gel provides us with a reference state when working with soft polymeric materials. Chemical gels will serve as model materials for the exploration of physical gels. A novel method for detecting the gel point has been proposed: the instant of liquid-to-solid transition(gel point) is marked by the crossover of the normalized dynamic moduli G'/cos($n_c$$\pi$/2) and G"/sin($n_c$$\pi$/2).>/2).

• 한국식품과학회지
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• 제20권4호
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• pp.594-599
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• 1988

냉동 저장온도에서 비동결 상태로 액란을 저장할 수 있는 방법을 연구하기 위하여 cryoprotectants를 첨가하거나 papain으로 처리하여 $-15^{\circ}C$에서 저장하면서 품질변화를 조사한 결과는 다음과 같다. Cryoprotectants로는 제품의 향미를 고려하여 fructose와 glucose를 45 : 55로 혼합하여 사용하는 것이 좋고, whole egg나 난황을 $-15^{\circ}C$에서 비동결 상태로 저장하는데 필요한 cryoprotectants의 농도는 각각 70.3%와 45.2%이었다. 그리고 액란에 cryoprotectants를 첨가하여 저장하면 gel화를 효과적으로 방지할수 있었으며, gel화가 발생한 액란에서는 consistency의 증가, 단백질 침전도의 증가 및 미세구조의 파괴를 볼수 있었다. 액란에 0.15%.papain을 처리한 후 냉동온도에서 저장하면 액란의 gel화를 상당히 방지할 수 있었다.

• Korean Chemical Engineering Research
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• 제55권5호
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• pp.690-697
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• 2017

본 연구에서는 방수시트재를 위한 아스팔트의 styrene-butadiene-styrene (SBS)와 styrene-isoprene-styrene (SIS)에 의한 개질에 있어서 자가치유성을 가지는 개질아스팔트 방수시트재의 연화점(softening point), 침입도(penetration), 저온굴곡저항성능(low temperature flexibility), 점도(viscosity) 및 부착성능(adhesion) 등의 물성을 관찰하고, 반응표면분석법(response surface methodology, RSM)을 활용하여 아스팔트 질량 대비 SBS와 SIS의 적정조성을 도출하고 자가치유성을 가지는 개질아스팔트 방수시트재의 물성을 최적화하였다. 고온에서 측정이 수행되는 연화점과 점도는 SBS 또는 SIS의 함량이 증가함에 따라서 유의하게 값이 증가하였다. 그러나 함량 대비 연화점과 점도 증가분은 SBS 경우가 SIS보다 커짐이 관찰되었다. 이러한 원인은 SBS와 SIS의 열적거동의 차이 때문인데, SBS는 고온에서 점도 상승을 동반하는 겔화(gelation)가 되어 가교도가 커지나 SIS는 점도감소를 초래하는 폴리이소프렌 블록의 사슬분리(chain scission) 때문에 사슬꼬임(chain entanglement)이 상대적으로 적어지기 때문이다. 반면에 SIS-SBS 개질아스팔트는 상온에서 측정되는 침입도, 부착성능 및 저온굴곡성능에 대하여, 아스팔트 63 g을 기본으로 SIS 4~5 g과 SBS 8.5 g의 조성에서 최소 탄성거동을 나타내어 최대 침입도 및 최대 부착성능과 최저 저온굴곡성능 값을 보였다.

• 한국식품과학회지
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• 제17권6호
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• pp.500-505
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• 1985

농축우유에 냉동보호물질을 첨가하여 $-15^{\circ}C$에서 비동결 상태로 저장할 수 있는 방법을 개발하여, $-15^{\circ}C$에서 저장하면서 저장중 품질변화를 평가한 결과는 다음과 같다. 농축우유를 $-15^{\circ}C$에서 비동결 상태로 저장하는데 적합한 복합냉동보호물질은 설탕 17.74%, glucose, 8.87% fructose 8.87%, glycerol 2%, HMP 0.25%, NaCl 0.25%, ascorbic acid 0.02%로 구성되었으며, 고형분 38%인 농축우유에 냉동보호물질 38%를 첨가하는 것이 적당하였다. 저장중의 품질변화중 관능적 품질과 이용성에 가장 심각한 영향을 주는 것은 단백질 변성에 의한 gel화현상 이었다. Gel화현상은 대조구에서 3주저장 후부터 발생하였으나 냉동보호물질을 첨가한 처리구에서는 전 저장기간동안 발생하지 않았다. 우유 단백질의 저장중 변성현상을 뒷받침하는 단백질 침전량을 조사한 결과 control에서 3주 후부터 현저하게 나타났으며, 처리구에서는 저장기간동안 나타나지 않아TEk. 저장중 농축우유의 색깔변화나 과산화물가의 변화는 경미했으며, 대조구과 처리구간에 유의성있는 차이가 없었다. 이상의 결과를 종합해 보면 농축우유에 냉동보호물질을 첨가하여 냉동저장온도에서 비동결상태로 저장하면 통상적인 냉동저장방법과 같은 품질보존 효과를 얻을 수 있을 뿐만 아니라, 보통 냉동저장시에 발생하는 우유단백질의 변성에서 오는 gel화현상을 효과적으로 방지할 수 있어 저장 후 제품의 품질과 이용성을 증진 시킬 수 있었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.66-69
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• 2001

A subsurface containment system which is constructed by pumping a gelling liquid (Colloidal Silica) into the unsaturated medium is investigated by developing a mathematical model and conducting numerical simulations. The proposed model is verified by comparing experimentally and numerically determined hydraulic conductivities of gel-treated soil columns at different Colloidal Silica (CS) injection volumes. The numerical experiments indicate that an impermeable gel layer is formed within the time period twice the gel-point. At the Same normalized time, the CS solutions with lower NaCl concentrations result ill further migration and poor Performance in plugging the pore space.

• 한국세라믹학회지
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• 제36권7호
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• pp.773-781
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• 1999

A new technique to fabricate complex-shaped mullite has been developed through gelcasting without organic binder. The suspension of a commercial mullite powder and boehmite-SiO2 sol as binder was elecrtrosterically stabilized. Ammonium polymetharylyate was employed as a dispersant for the electrosteric stabilization. Complex-shaped bodies were made through casting and gelation at room temperature. The green bodies were dried at a temperature of 30$^{\circ}C$ and relative humidity of 98% without crack development. The dried bodies were then pressureless-sintered at 1650$^{\circ}C$ for 2 h to get a relative density of 98% The Vickers hardness and 4-point flexural strength of sintered parts were 11.0 GPa and 150MPa respectively which are similar to those of commercially available sintered mullite.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권2호
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• pp.132-136
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• 2004

The LAL (Limulus amebocyte lysate) test for the detection and quantification of endotoxin is based on the gelation reaction between endotoxin and LAL from a blood extract of Limulus polyphemus. The test is labor intensive, requiring dedicated personnel, a relatively long reaction time (approximately 1 h), relatively large volumes of samples and reagents and the detection of the end-point is rather subjective. To solve these problems, a miniaturized LOC (lab-on-a-chip) prototype, 62mm (L) ${\times}$ 18 mm (W), was fabricated using PDMS (polydimethylsiloxane) bonded to glass. Using this prototype, in which 2mm (W) ${\times}$ 44.3mm (L) ${\times}$ 100 $\mu\textrm{m}$ (D) microfluidic channel was constructed, turbidometric and chromogenic assay detection methods were compared, and the chromogenic method was found the most suitable for a small volume assay. In this assay, the kinetic-point method was more accurate than the end-point method. The PDMS chip thickness was found to be minimized to around 2 mm to allow sufficient light transmittance, which necessitated the use of a glass slide bonding for chip rigidity. Due to this miniaturization, the test time was reduced from 1 h to less than 10 min, and the sample volume could be reduced from 100 to ca. 4.4 ${\mu}$L. In summation, this study suggested that the LOC using the LAL test principle could be an alternative as a semi-automated and reliable method for the detection of endotoxin.

• Environmental Engineering Research
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• 제22권3호
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• pp.255-265
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• 2017

Polyelectrolytes are commonly used as flocculants in drinking water treatment. However the growing concerns about their toxicity have motivated the search for biocompatible flocculants. Here, we show that gelatin, a natural amphoteric polyelectrolyte, can be effectively adsorbed on clay surfaces and can potentially be a suitable substitute for existing flocculants. The adsorption of gelatin from its aqueous solution onto the mineral clay surfaces at different conditions was systematically investigated using the design of experiments methodology. The gelatin adsorption was found to vary considerately with pH variation showed a maximum adsorption at its isoelectric point. The amount of adsorbed gelation increased with increasing pH from 3 to 5, attained a maximum at pH 5 and then decreased with increasing pH from 5 to 11. Similarly, the amount of adsorbed gelatin showed decreasing trends around salt concentration of 0.05 M and temperature $35^{\circ}C$. On the other hand, the adsorption was continuously increased with time and polymer concentration in the range of 0.1-0.9 mg/dL. Finally, the jar tests confirmed the ability of gelatin for using a natural flocculant for water treatment.