• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2489-2493
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• 2012

A new fluorescent system (acridine/RTIL hybrid gel) confined in the 3D micro-structure of a poly(lactic acid) membrane were prepared from 1-butyl-3-methylimidazolium-based ionic liquids ([bmim]X (X = $SbF_6$, $NTf_2$, Cl); RTILs), poly(lactic acid) (PLA), and acridine via the sol-gel route. SEM images showed that, in the presence of [bmim]$SbF_6$ and [bmim]$NTf_2$, 3D-ly paticulated structures were created inside the PLA membranes and acridine/RTIL hybrid gels were confined in gabs of particulates. However, the use of [bmim]Cl induced the formation of a 3D-ly porous structure containing the hybrid gel of acridine/[bmimCl in the micropores. The three fluorescent systems exhibited different fluorescence behaviors (fluorescence maximum and intensity) depending on the C2-H acidity scale of the RTILs (or their anion type). Acridine gels hybridized with [bmim]$SbF_6$ and [bmim]$NTf_2$ showed blue fluorescence with relative high intensity, whereas the hybrid gel with [bmim]Cl exhibited almost no fluorescence under dry conditions. However, the acridine/[bmim]Cl hybrid system in the micro-porous PLA membrane started to emit fluorescent light under humid conditions and showed a possible response, indicating that it could be applied as a humidity sensor.

• 한국세라믹학회지
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• 제44권3호
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• pp.162-168
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• 2007

Silica wet gels were prepared ken water glass ($29\;wt%\;SiO_{2}$) by using Amberlite as a ion exchange resin. After washing in distilled water, the wet gels were further aged in a solution of TEOS/EtOH to strengthen of 3-dimensional network structure. As increase TEOS content in aging solution, BET surface area and porosity of the ambient dried silica aerogels were significantly decreased, and average pore diameter was also decreased 30 nm to -10 nm. Also, higher density and compressive strength were obtained in case of higher TEOS content. This is due to precipitation of $SiO_{2}$ nano particles by TEOS. Hence, TEOS addition plays an important role of both strengthening and stiffness of silica wet gel network. By adding over 30 vol% TEOS, a crack-free monolithic silica aerogel tiles were obtained and its density, compressive strength, and thermal conductivity were shown $0.232g/cm^{3}$, 7.3 MPa, and 0.029 W/mk, respectivly.

• 대한수의학회지
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• 제33권1호
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• pp.87-91
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• 1993

The morphological hetergeneity of lipopolysaccharides(LPSs) and variation in the O-side chain lengths of LPSs of Salmonella pullorum, which was serially subcultured on the brain heart infusion agar containing $100{\mu}g/m{\ell}$ of acridine orange, was analyzed in Sephadex G-50 column chromatography and silver-stained polyacrylamide gels. The biochemical differences in LPS W and LPS A0150 were identified. Increases in the contents of O-polysaccharides of LPS A0150 than those of LPS W were reflected in the profiles of chromatography and silver-stained polyacrylamide gels. In summary, LPS molecules of S pullorum A0150 appeared to be enriched in the molecules with long O-polysaccharide chains than those of LPS W.

• Journal of Pharmaceutical Investigation
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• 제25권2호
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• pp.129-136
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• 1995

In order to reduce the systemic side effects and the gastrointestinal irritation of indomethacin following its oral administration, the drug was formulated as a transdermal gel using poloxamer 407. In vitro diffusion cells fitted with excised rat skins were used to evaluate the effects of formulation variables on skin permeation of indomethacin from poloxamer gels. The formulation variables were the concentrations of indomethacin, poloxamer 407 and ethanol, and the gel pH. The increase of the drug amount in the gel from 0.5% to 2.0% induced a direct but nonlinear increase in the skin permeation rate of indomethacin. The increase of poloxamer concentration from 17.5% to 25% in the gel resulted in a decrease of skin permeation rate of indomethacin, which was due to a reduction in the amount of free drug molecules available for permeation through skin by entrapping more drug molecules within the micelles formed by poloxamer. The increase of ethanol concentration from 10% to 20% in the gel resulted in a linear increase of permeation rate of indomethacin through skin, possibly due to the penetration enhancing effect of ethanol. The skin permeation of indomethacin was substantially influenced by the gel pH, exhibiting a maximum at pH 4.

• 한국재료학회지
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• 제12권8호
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• pp.650-655
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• 2002

$SiO_2$ gels containing dispersed fine Te metal particles have been prepared by the sol- gel method using a starting solution containing Tetraethoxy Silane (Si($OC_2$ $H_{5}$ )$_4$), $H_2$O, Ethylalchol ($C_2$$H_{5}$OH), Nitric Acid ($HNO_3$) and Tellurium Tetracholoride ($TeCl_4$) in a several molar ratio. Gelling time of sols was about 3 days and viscosity of solution was very low about 2~3 cP for 3 days. Heat-treatments of the gel have been performed at 500, 700, 900, 1100 and $1300^{\circ}C$ for 1 hour, respectively. We have investigated TG-DTA, X-ray diffraction patterns and SEM of heat-treatmented gels. The size of Te fine particles dispersed in $SiO_2$ gel was about 0.8~1 $\mu\textrm{m}$ and the shape was almost quadrangle.

• Macromolecular Research
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• 제10권2호
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• pp.115-121
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• 2002

Synthesis of polymers with controlled thermosensitive properties was carried out by conventional radical copolymerization of N-isopropylacrylamide (NIPAAm) with N-vinylpyrrolidone (NVP) taken as a hydrophilic comonomer. Lower activity of NVP rather than NIPAAm was revealed by gravimetric and $^1$H NMR analysis. Thermosensitive properties of the copolymers were investigated. It was found that aqueous solutions of the copolymers undergo thermo-induced phase transition and become opaque, precipitate or gel with heating. After formation of the gels their significant contraction was observed at storage. Swelling degree and amount of expelled water were measured in dependence on the copolymer composition, temperature and ionic strength of environment medium and concentration of the solution. It was determined that in collapsed state gels exhibit quite high water content. According to physico-chemical properties of the copolymers observed they could be suitable for biomedical application as an injectable implant material.

• 한국수산과학회지
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• 제36권3호
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• pp.198-203
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• 2003

Heat-induced surimi gels were prepared using various concentration of ATC as a additives and calcium agent. Regardless of various concentration of ATC, there were no difference the moisture $(80.4-81.2\%)\;and\;crude\;ash\;(1.4-1.\5%)$ contents. The pH of heat-induced surimi gels were decreased 7.16 to 7.04 depend on increasing ATC concentration. The whiteness, breaking force and gel strength of $0.09\%$surimi gel were improved significantly difference (p<0.05). Sensory evaluation on texture and whiteness were also similar to determination by color and texture meters. In mineral content of heat-induced surimi gel calcium content was increased 26 to 54 mg/100g depend on increasing ATC concentration, while phosphorus content was not change. The optimal concentration of ATC for preparation of high quality heat-induced surimi gel was $0.09\%$. The shelf-life of heat-induced surimi gel did not extend by addition of $0.09\%$ ATC.

• 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).

• 한국세라믹학회지
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• 제45권5호
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• pp.303-308
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• 2008

Mullite precursors were synthesized with aluminosilicate gels from mixture of aluminum nitrate and sodium orthosilicate by the geopolymer technique at ambient temperature. Then, the gel was heat-treated in air up to $1200^{\circ}C$ at intervals of $100^{\circ}C$. Raw and heat-treated gels were characterized by TG-DTA, XRD, FTIR, $^{29}Si$ MAS-NMR, TEM. The result to examine the crystallization of behavior though DTA, the synthesized precursors were crystallized in the temperature range from $950^{\circ}C$ to $1050^{\circ}C$. The XRD results showed that the gel compositions were begun to crystallize at various temperature. Also, it was found that the precursors of M-4 begun to crystallize at about $950^{\circ}C$. The M-4 XRD peaks were characterized better than $M-1{\sim}M-3$ at $1000^{\circ}C$. The formation temperature of mullite in this study is much lower than that of previous sol-gel methods, which crystallized at up of $1200^{\circ}C$. TEM investigations revealed that the sample with 10 nm particle size was obtained via heat-treated at $1000^{\circ}C$ for M-4.

• 공업화학
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• 제5권6호
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• pp.1009-1015
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• 1994

분산중합으로 합성한 폴리스티렌 seed를 사용하여 seed 중합방법으로 단분산성인 다공성 스티렌-디비닐벤젠(St-DVB) 겔과 아크릴로니트릴-에틸렌 디메타크릴레이트(AN-EDMA) 겔을 제조하였다. 합성한 St-DVB 겔과 AN-EDMA 겔은 HPLC용 충진제로 적합한 좁은 입도분포와 다공성을 갖고 있으며, 이들 겔을 충진한 GPC 또는 HPLC용 column은 비교적 높은 효율을 나타내었다, 또한 AN-EDMA 겔을 아미드옥심화한 AAN-EDMA 겔에 대한 $Cu^{2+}$, $Cd^{2+}$ 및 ${UO_2}^{2+}$ 이온의 흡착특성을 시험하였다.