• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.469-481
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• 2006

Among the etiologic factors of enamel corrosion, daily intake has been considered with a profound interest, especially the intake of acidic drinks. It is thought that the rapid consumption of acidic drinks will not only results in the affection to the teeth but also to the surface of the tooth-colored restorative materials. Therefore, the puopose of this study is to examine the alterations occurred in the surface of the tooth-colored materials according to the exposed time, with 3 most common acidic drinks in contact with daily life. Resin-modified glass-ionomer, polyacid-modified composite resin, composite resin were immersed on 0.9% NaCl, Coke, orange juice, sports beverages as 4 groups in each. The surface hardness and the surface roughness of specimens were measured with following methods: before immersion, 1 day after immersion, 1-,2-,3-,4- weeks after immersion. Results were as follows. 1. Tooth-colored restorative materials, with the exception of composite resin, showed statistically significant changes in surface hardness and roughness when immersed on acidic drinks(p<0.05). 2. The degree of change in surface hardness and roughness occurred as follows, in order of severity from greatest to least resin-modified glass-ionomer, polyacid-modified composite resin, composite resin 3. Sports beverages resulted in greater alterations to surfaces than Coke and orange juice. 4. In the SEM image of the groups immersed in acidic drinks, resin-modified glass-ionomer and polyacid-modified composite resin showed loss of filer. Severe cracks were observed, especially on the resin-modified glass-ionomer.

• Journal of Pharmaceutical Investigation
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• v.27 no.4
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• pp.313-321
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• 1997

Ion exchange resin complexes of famotidine have been prepared by the reaction of famotidine solution with activated ion exchange resins. Complex formation efficiency between famotidine and ion exchange resin was about $80{\sim}90%$ in average, calculated by HPLC determination. Drug release characteristics from the resin complexes were evaluated by the modified percolation method. Famotidine release was dependent on the type of ion exchange resins. In the case of weakly acidic resin complexes, the cumulative released amount of famotidine was more than 90% for 1hr in pH 1.2 buffer solution. However, in the case of strongly acidic resin complexes, it was less than 5% for 3hr in the same medium. Strongly acidic resins revealed some advantages over weakly, acidic resins for overcoming instability of famotidine in gastric juice. In addition, strongly acidic resin complexes showed controlled release of famotidine in pH 6.8 buffer solution, showing the result of about 60 to 70% of drug release for 5hr. After oral administrations of famotidine-resin complexes to rats as dose of 40 mg equivalent/kg, the pharmacokinetic parameters of famotidine were obtained by model independent analysis and compared with those of famotidine solution or suspension. $C_{max}$ of famotidine-resin complex was lower than that of famotidine solution or suspension. MRT, MAT, and MDT of the complexes were greater than those of famotidine solution or suspension. From these results, it was expected that famotidine was released slowly from the complexes and absorbed continuously into systemic circulation. It was recognized that drug release from the complexes was the rate-limiting step in drug absorption, since there were close correlations between in vitro drug release and in vivo pharmacokinetic parameters.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.263-269
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• 2002

This study was conducted to know the removal characteristics of ammonia nitrogen by commercially available cation exchange resins. Eight acidic cation exchange resins were investigated in batch reactors. Among them, the most effective resin for ammonia removal in solution was PK228, which was a strong acidic resin of $Na^{+}$ type. PK228 was compared with activated carbon and natural zeolite. The effects of cation exchange capacity, ammonia concentration, resin amount, temperature and pH on ammonia removal by PK228 were investigated in batch reactor, and the effect of effluent velocity in continuous column reactor. Strong acidic resins of porous type were more effective than week acidic resins or gel type resins for ammonia removal in solution. PK228 was more effective than activated carbon and natural zeolite for ammonia removal in batch reactor. With increasing initial ammonia concentration, the amount of ammonia removed by PK228 increased, but the proportion of removed ammonia to initial ammonia concentration decreased. The effect or temperature on ammonia removal by PK228 was very slight. The ammonia removal to acidic solution was more effective than that at basic solution. With decreasing effluent velocity of solution through column, breakthrough point extended, and ammonia removal capacity increased.d.

• Journal of Pharmaceutical Investigation
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• v.18 no.3
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• pp.133-137
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• 1988

In vitro studies were performed on the interaction of indomethacin with cholestyramine, a hypocholesterolemic substance. Cholestyramine showed a marked affinity for indomethacin among tested acidic drugs and the intensity of adsorption was dependent on pH, temperature and sodium chloride. Moreover, the combination of indomethacin with some acidic drugs that formed complexes with cholestyramine, considerably inhibited the adsorption of indomethacin on the resin.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1324-1328
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• 2003

The simultaneous determination of anions ($SO_4 ^{2-},\;Cl^-,\;and\;NO_3^-$) and cations ($Na^+,\;NH^{4+},\;K^+,\;Mg^{2+},\;and\;Ca^{2+}$) in natural water obtained by Nakdong River waters system in Korea were performed by ion-exclusion/cationexchange chromatography with conductimetric detection. The stationary phase was a polymethacrylate-based weakly acidic cation-exchange resin column in the $H^+$-form and a weak-acid eluent. When using only a 1.4 mM sulfosalicylic acid/6 mM 18-crown-6 ether as an eluent, good resolution of both anions and cations, minimum time required for the separation, and satisfactory detection sensitivity were obtained in a reasonable time. The method was successfully applied to the simultaneous determination of anions and cations in natural waters.

• Corrosion Science and Technology
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• v.7 no.5
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• pp.269-273
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• 2008

It is known that the fluoric resin has the most outstanding properties in the extremely acidic environment of high temperature. However, this resin is the thermal hardening type that needs long time heat treatments above $250^{\circ}C$. It's impossible to use in situ in the extremely acidic environment such as a huge FGD ductworks or industrial chemical tanks. Furthermore, even the natural hardening type fluoric coatings which can be hardened less than $120^{\circ}C$ can not be applied to the highly acidic environmental plants because of its chemical resistance. In this study, new fluoric coatings that has excellent thermal resistance, chemical resistance and corrosion resistance has been developed in order to solve above problems and to be applied to the large plant structures in the field. These newly developed coatings are organic and inorganic composite type that have fluoric rubber(100 wt%), fluoric resin(5~50 wt%), oxalates(5~30 wt%), inorganic fillers mixed with plate-type and bulk-type solids(20~150 wt%), hardeners(0.5~5 wt%), and hardening hasteners(0.1~3 wt%). The best chemical and physical properties of these coatings are acquired by variation of adhesive reinforcement agents, dispersants, leveling agents. Mixing ratios of plate-type and bulk-type inorganic fillers influence the thermal properties, abrasive resistance and chemical infiltration properties of coatings. The mixing control is also very important to have homogeneous surface and removing inner voids of coatings.

• Bulletin of the Korean Chemical Society
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• v.18 no.11
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• pp.1208-1210
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• 1997

• Journal of environmental and Sanitary engineering
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• v.23 no.1
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• pp.67-72
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• 2008

Ion exchange performance to remove Ammonium in water was studied using commercially available strong acidic cationic exchange resin of $Na^+$ type in the batch and continuous column reactors. The performance was tested using the effluent concentration histories for continuous column or equilibrium concentrations for batch reactor as a function of time until resins were exhausted or reached ionic equilibrium between resin and solution. The results shoed that cationic exchange resin used in this study was more effective than activated carbon or zeolite for ammonium removal. Ammonium removal with the ion exchange resin temperature to be high qualitative recording minuteness but increases about seasonal change of temperature was judged with the public law where the adaptability is excellent. When the pH comes to be high at 11 degree, the ammonium was not effectively removed.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.539-546
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• 2017

In this study, an outstanding anion exchange chemical filter was prepared for acidic gas removal. Commercial anion exchange resin was attached to polyurethane (PU) foam by using different types of pressure sensitive adhesive (PSA). The water and chemical resistance and also adhesive elongation were investigated. Also, the behavior of HCl and HF adsorption was evaluated as functions of the initial concentration and flow rate. ATE-701, AT-4000C and HCA-1000 showed 900, 1,500% and 2,400% of the elongation, respectively. It was confirmed that the desorption ratio of HCA-1000 was less than 6% and had excellent durability in water and chemical resistance tests. The adsorption occurred faster as the concentration and flow rate of HCl and HF increased. But 100% adsorption equilibrium occurred after 110 minutes, regardless of the concentration and flow rate. In addition, SEM morphology showed that the adhesive was uniformly dispersed, while the porous structure of the ion exchange resin was maintained, and the chemical filter exhibited excellent durability for the adsorption/desorption process.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.218-224
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• 1999

Continuous ion exchange characteristics of the synthetic coolant contained Ni, Co and Ag ions of low concentration in acidic-oxidizing conditions have been studied to suggest the guideline for the optimum operation of mixed-bed demincralizer during the shutdown period of a pressurized water reactor (PWR). In the effect of the form of cation resins on the removal capacity of metal ions, the performance of a $H^+$-form resin was about 6% higher than that of a $Li^+$-form resin. Mixed-bed of cation and anion resins in comparison with nonmixed-bed of them, had no affected on the removal capacity of metal ions but very slightly increased the slope of breakthrough curves of metal ions. In the effect related to acidic-oxidizing conditions of the coolant, the addition of boric acid very slightly decreased the slope of breakthrough curves of metal ions, while the addition of hydrogen peroxide slightly decreased the removal capacity of metal ions.