• Journal of Pharmaceutical Investigation
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• v.6 no.1
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• pp.26-32
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• 1976

Dicalcium phosphate dihydrate (DCPD) is the most widely-used dentifrice abrasive in non-therapeutic tooth-paste requiring, low abrasive level, high stability and excellent compatibility with other formulation ingredients. One of the difficulties encountered in the use of this material in tooth-paste is that unless storage of the product is maintained at a relative low temperature there is a distinct tendency to lose water of crystallization. Another difficulty which has been encountered is that there is a tendency for the product to become lumpy. Various means have been proposed for increasing the stability and overcoming the lumping tendency, most of which means comprise the addition of stabilizing agent. But there is not any report about the relationships between the mechanism of dehydration, physical properties, structure and manufacturing condition. In this experiment, DCPD were manufactured by methods of Moss' patent, its two varied and J.P.VIII, these were studied by means of stability test, IR spectra, and DTA. According to the manufacturing conditions, DCPD has different physical properties and structures, i. e., monoclinic system of low drying temperature, triclinic system of high drying temperature. Dehydration of DCPD may be supposed one step debydration at about $100^{\circ}$ and it finaly converts to ${\gamma}-pyrophosphate$ at about $465^{\circ}$ and if the drying temperature is high it becomes DCP anhydrous. DCPD made by Moss' patent is thought of the best polishing agent of tooth-paste.

• Conservation Science in Museum
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• v.21
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• pp.29-40
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• 2019

An experimental study was conducted to test the applicability of natural hydraulic lime (NHL) as a reinforcing agent for the supporting layers of mural paintings in ancient tombs.Drawing upon preceding studies on mural paintings inancient tombs, samples of reinforcing agents for various conditions were prepared using NHL products, and pseudo-samples of the supporting layers of mural paintings were also produced. The samples were cured for 7, 28, and 84 days in a high-humidity condition similar to that of the mural-tomb environment. Physical properties such as dimensional stability and compressive strength were measured for each curing period.The results indicated that the NHL samples had a rapid curing speed and a low contraction ratio and are therefore suitable as reinforcing agents, whereas they showed a poor match in terms of strength compared to the supporting layer,and also low whiteness. The dimensional stability and compressive strength testsrevealedthat an NHL product mixed with a pseudo-sample of a supporting layer provided desirable conditions for reinforcing agent. The findings suggested that different conditions for curing time and strength should be considered for each supporting layer prior to applying NHL as a reinforcing agent for damaged mural paintings in ancient tombs.

• Journal of the Korean Ceramic Society
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• v.35 no.5
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• pp.421-428
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• 1998

The effect of silane coupling agents on the water stability of HAC/PVA based MDF cement composites which were modified with urethane and epoxy resin were studied as a function of the functional groups and addition amount of silane coupling agent. According to the composition of polymer matrix the silanes with different functional groups showed the different effectiveness. In case of the only PVA matrix the silane with vinyl functional group was more effective than other silanes. When the epoxy resin was added the silane of epoxy-methodxy group enhanced the flexural strength of dry and wet state more than other. In case of urethane-added MDF cement the silane of diamine group was effective and enhanced the water sta-bility fo MDF cement composite more and more as the addition amount of silane increased, Especially in case of warm-presed composite the effect of silane was enhanced By addition of 2wt% of silane with 야-amine group the flexural strength of urethane-added composites were enhanced by 20% more in dry state 40-70% in wet state in accord with the porosity analysis. The flexural strength of the poxy resin-added MDF cement composite was increased by addition of 1wt% and 2wt% silane of epoxy-methoxy group However the addition of 4wt% of silane decreased the flexural strength of dry and wet state by formation of closed pore in the polymer matrix.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.46 no.1
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• pp.31-42
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• 2020

Horse fat is known to be an effective ingredient in Asia, and the horse fat itself, which is mixed with other ingredients at the additive level, is often sold as a finished product. In this case, physical properties of the horse fat raw material are important. Many horse fats produced in Korea (Jeju) have low temperature stability, so if not stored at low temperatures, segregation may occur. In the case of Japanese horse fat, it is partially hydrogenated or is used the solid phase as the horse fat by separating the liquid phase and the solid phase that is harder and more stable than the horse fat of Jeju. In this study, the physical properties were tested to improve the temperature stability even without the partial hydrogenation process of Jeju horse fat. Various oil gelling agents were used in the study. Results confirmed that the physical properties of the hydroxystearic acid added Jeju horse fat were improved. In addition, stability evaluations at temperatures of 25 ℃, 40 ℃, 45 ℃ and flow behavior evaluations at temperatures of 25 ℃, 30 ℃, 40 ℃ were performed for Jeju horse fat with hydroxystearic acid, 100% Jeju horse fat, and 100% Japanese horse fat. Results showed that the Jeju horse fat improved in flow behavior by adding hydroxystearic acid similar to that of Japanese horse fat. In addition, when the crystal state was observed under a microscope, the thermal stability was improved by decreasing the size of the needle-type crystals with the addition of hydroxystearic acid. Jeju horse fat containing hydroxystearic acid was found to have no physical problems even when stored at room temperature for a long time.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.497-501
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• 2015

Inkjet printing is a widespread technology, offering advantages such as high-quality decoration, a continuous process, and the accurate direct reproduction of patterns or pictures. In inkjet printing technology, the dispersion stability of ceramic ink is one of the most important factors. In this study, the dispersion stability of blue $CoAl_2O_4$ ink for ceramic inkjet printing is systematically investigated. Blue $CoAl_2O_4$ pigment was synthesized by a solid-state reaction and then milled to less than 300nm in size. In order to investigate the influence of the viscosity on the dispersion stability, two types of $CoAl_2O_4$ ceramic inks (termed here Blue L and Blue H) were prepared using different volume ratios of ethylene glycol and ethanol. The Blue L and Blue H ink solutions contained cetyltrimethylammonium bromide(CTAB) as a dispersive agent. The viscosity, surface tension and jetting stability of the $CoAl_2O_4$ ceramic inks were analyzed using a rheometer, a surface tension meter and a dropwatcher. The dispersion stability of the $CoAl_2O_4$ ceramic ink was investigated by a multiple light-scattering method. Blue H, a ceramic ink with higher viscosity, showed much better dispersion stability than the Blue L ceramic ink.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.151-158
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• 2011

Bubbles within the foamed concrete manufactured by pre-foaming method is the main factor which affects the physical properties of foamed concrete such as density, strength, and porosity. Although many researches on foamed concrete have been continuously carried out, insufficient number of researches on the properties related to bubbles in the foamed concrete has been performed except for chemical application related researches. In order to make an optimal foamed concrete, study on the bubble properties must be pursued. In order to effectively implement bubbles in the manufacturing of foamed concrete, the bubble properties must be estimated. In this study, in order to determine the bubble properties, examination of the bubble properties according to types and foaming agent concentration was performed. An foaming agent used for this test were anionic surfactant, rosin, and protein system with the foaming agent concentration range of 0.05~13%. Test parameters considered in the study were foaming rate, foam volume, drainage solution volume, and bubble size. The study results showed that, regardless of foaming agent type, higher concentration of foaming agent showed an increase in the foaming rate. Also, the results showed that concentration of foaming agent affected bubble size, drainage solution volume change, and bubble distributions. With respect to the stability of the bubble, protein foaming agent was better than anion surfactant or rosin foaming agent. With respect to the bubble shape, anion surfactant and rosin formed bubbles had polygon shape where as protein formed bubbles had spherical shape.

• KSBB Journal
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• v.23 no.4
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• pp.340-344
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• 2008

Coprinus cinereus peroxidase (CiP) was often used as a catalyst for oxidative polymerization of a variety of phenol derivatives to produce a new class of polyphenols. Economical point of view, to know the mechanism of enzyme deactivation is significantly important because cost of enzyme is critically high. Hydrogen peroxide being used as oxidizing agent induced deactivation of peroxidase by destruction of heme structure. In the presence of hydrogen peroxide the stability of peroxidase was unexpectedly improved by adding organic solvent. Especially 2-propanol significantly improved enzyme stability among tested solvents. Radical scavenging by organic solvents may play a major role in protecting peroxidase from the oxidation of oxidizing radicals.

• Integrative Medicine Research
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• v.3 no.1
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• pp.25-33
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• 2014

Background: Green tea contains numerous polyphenols, which have health-promoting effects. The purpose of this study was to evaluate the effect of tannase-converted green tea extract (TGE) formulation on the physical stability and activities of skin-related enzymes. Methods: Physical stability was evaluated by measuring the pH, precipitation, and colors at $25{\pm}2^{\circ}C$ /ambient humidity and at $40{\pm}2^{\circ}C$ \70%${\pm}$5% relative humidity for 4 months. Activities of collagenase, elastase, and tyrosinase as skin-related enzymes were assessed on TGE formulation. Results: The concentrations of epigallocatechin-3-gallate and epicatechin-3-gallate in green tea extract were greatly decreased to the extent of negligible level when treated with tannase. The formulation containing 5% tannase-converted green tea extract showed relatively stable pH, precipitation, and color features for 16 weeks. When TGE was added to the formulation, there was a significant increase in the inhibition of elastase and tyrosinase activities (p<0.05) compared with the formulation containing 5% normal green tea extract. Conclusion: The TGE could be used in cosmetics as skin antiwrinkling or depigmenting agent.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.472-477
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• 2021

The crosslinking behavior of polyhedral oligomeric silsesquioxane (POSS) containing eight acrylate groups in a cage form in ethylene-propylene-diene rubber (EPDM) peroxide crosslinking, the effect on mechanical properties, and the thermal stability were investigated. An EPDM/POSS composite material was prepared by mixing 0 to 12 parts per hundreds of rubber (phr) of POSS per 100 phr of rubber by content and adding a peroxide crosslinking agent. As a result of crosslinking properties, it was found that the acrylate group of POSS was activated by peroxide and improved the peroxide crosslinking efficiency. Although the dispersion stability of POSS in EPDM/POSS composites was poor, the fracture strength, elongation and thermal stability were improved.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.12
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• pp.2019-2027
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• 2013

In this study, we tried to develop a coating agent for the fresh-cut fruits used in cakes. First, the coating agent mixing ratios of sugar, pectin, sodium alginate, carrageenan, xanthan gum, vitamin C, and purified water were selected to be 55, 2, 2, 0.04, 0.1, 0.05, and 40.81% (w/w), respectively. In a freeze-thaw stability of the coating agent, the viscosity remained constant for 3 cycles of freezing and thawing repetition process, but showed a slightly decreasing trend in the 4th repetition process (P<0.05). On the other hand, the sugar content, pH, and chromaticity remained constant even in the 4th repetition process. Pineapple coated with the coating agent had smaller weight loss, hardness changes, and total bacteria distribution compared to the uncoated pineapple (P<0.05). In the chromaticity, both of the two pineapples experienced browning with increasing storage duration, as L value decreases and b value increases. However, when the color difference was compared, the progress of browning for the uncoated pineapple was faster than the coated pineapple. Also, the progress of browning at $4^{\circ}C$ was found to be slower than the progress of browning at $25^{\circ}C$. Therefore, the storage stability of the fresh-cut fruits could be improved by coating the fresh-cut fruits for cakes with the coating agent and storing at a low temperature, which would contribute to extending the shelf-life of cakes.