• Journal of Conservation Science
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• v.32 no.2
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• pp.249-259
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• 2016

Effect of the flame retardants on Dancheong is studied in the present work. Two kinds of flame retardants were applied on Dancheong specimens and compared with control groups on which distilled water was applied instead of the flame retardants. The flame retardants enhanced the hygroscopic property of the surface of Dancheong. Furthermore, the added flame retardants reacted with oyster shell white($CaCO_3$) and lead red($Pb_3O_4$), producing new chemical compounds like Calcium phosphate tribasic and Lead Phosphates which make the painted layer of Dancheong dissolving and whitening over certain period of time. When applied in excessive amount and exposed in repetitive wet and dry condition, especially, they aggravate the surface problems significantly. These results will provide a good reference on the study of the discoloring/whitening effect of Dancheong layers at many traditional wooden building in Korea.

• Applied Biological Chemistry
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• v.24 no.2
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• pp.105-111
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• 1981

Growth responses of Brevibadterium ammoniagenes BA 17-2, which had been obtained by the treatment of several mutagens in our previous report, were investigated to select the preliminary optimal concentrations of phosphate, $Mg^{++}$, $Mn^{++}$ and thiamine for the production of 5'-XMP aminase. In this experiment it was shown that the concentration of phosphate in the medium has an important effect on the growth of microorganism. Using the medium containing 0.2% of $MgSO_4{\cdot}7H_2O$, 3mg/l of $MnSO_4{\cdot}H_2O$and $1\;mg/l$ of thiamine-HCl, the maximum cell mass was obtained at the concentration of 0.4% of $KH_2PO_4$ and $K_2HPO_4$, respectively. Above the concentration of these phosphates, cell growth was inhibited as the phosphate concentration increased to 1%, but the inhibition was overcome by the addition of 1% of $MgSO_4{\cdot}7H_2O$ and 3mg/l of thiamine-HCl. The 5'-XMP aminase activity was also influenced by the concentration of phosphate, $Mg^{++}$, $Mn^{++}$, and thiamine. In addition, the optimal culture pH and temperature for the enzyme activity were found to be 6.8 and $32^{\circ}C$, respectively.

• The Korean Journal of Pharmacology
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• v.18 no.1
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• pp.55-63
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• 1982

Lipid peroxidation is the reaction of oxidative deterioration of polyunsaturated lipids and this peroxidation involves the direct reaction of oxygen and lipid to form free radical intermediates, which can lead to autocatalysis. As results of the extensive studies on the lipid peroxidation by many authors, the relationship between lipid peroxidation and the drug metabolizing system as well as the actions of free radicals on the peroxidation was reasonably well known. For a long time, the mechanism of hepatotoxicity of $CCl_4$ was not clearly understood. However, it is now quite well established that $CCl_4$ is activated in vivo to a free radical which is a highly reactive molecule. Therefore, lipid peroxidation which induces the reduction of cytochrome P-450 and aminopyrine demethylase activity is known as decisive event of $CCl_4$ hepatotoxicity. On the other hand, it was also reported that singlet molecular oxygen produces lipid peroxidation in liver microsomes. In this study the effects of benzoyl peroxide on the lipid peroxidation and drug-metabolizing enzyme were examined. Benzoyl peroxide mixed with starch and phosphates etc. is usually used as a food additive for flour bleaching and maturing purpose because of its oxidative property. Albino rats were used for the experimental animals. Benzoyl peroxide was suspended in soybean oil and sesame oil and administered intraperitoneally or orally. TBA value and aminopyrine demethylase activity were determined in liver microsomal fraction and serum. The results were summerized as following. 1) Body weights of animals administered benzoyl peroxide suspension were decreased while that of oil administered group were increased. 2) The activity of aminopyrine demethylase was generally decreased in animals administered oil suspension of benzoyl peroxide. Furthermore, the marked reduction of the enzyme activity was observed in animals administered benzoyl peroxide intraperitoneally. 3) Generally, microsomal TBA values as well as serum TBA were significantly elevated in benzoyl peroxide group in comparison with the control group. However, the more remarkable increase of serum TBA than microsomal TBA was observed in animals administered orally for 6 days. 4) Specifically, the changing pattern of TBA value was notable in serum rather than in liver microsome by intraperitoneal administration of benzoyl peroxide.

• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.32-37
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• 2000

A series of transition metal complexes of 3,6-bis(6'-methyl-2'-pyridyl)pyridazine ($L^{1}$) and 3,6-bis(2'-pyridyl)pyridazine ($L^{2}$) as artificial nuclease, $1{\sim}8$ were synthesized. After determining of X-ray crystal structure, hydrolysis rate constants of phosphates, as DNA model compound and biological activities were confirmed. $L^{2}$-Zn(II) complex, 8 was shown the best hydrolysis rate constant. The $L^{2}$-Ni(II) complex, 5 and $L^{2}$-Co(II) complex, 6 showed the highest herbicidal activity against SCP (Scriptus Juncoids) with excellent tolerance to rice, ORY (Oryzae sativa L.). And the $L^{1}$-Co(II) complex, 2, $L^{1}$-Zn(II) complex, 4 and ligand ($L^{1}$ amp; $L^{2}$) displayed above 90% fungicidal activity against MAG (Magnaporthe grisea).

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.468-474
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• 1986

The emulsifying properties of soy protein isolate were measured at various conditions, and the relationships between the emulsifying properties and solubility, viscosity, hydrophobicity, protein adsorption, the tension at water-oil interface were investigated. The emulsifying properties are minimum at the isoelectric point(pI), and the effect of pH parallels its effect on protein solubility. The emulsifying activity is increasing up to $50^{\circ}C$ and then is somewhat decreasing above that temperature, while the emulsion stability is continuously decreasing. Except for phosphates, the salts cause the decrease of the emulsifying properties. The hydrophobicity is increasing as the temperature increases and decreasing somewhat as pH gets lower. However, it is increasing substantially at pH below the pI. The maximum protein adsorption at the water-oil interface is 0.78, 0.47, and $0.33mg/m^2$ at pH 2, 7, and 4, respectively. The tension at water-oil interface is 19.76 dyne/cm in the absence of soy protein, whereas it is decreasing to 11.45-18.08 dyne/cm in the presence of the protein.

• Journal of Nutrition and Health
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• v.45 no.2
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• pp.113-120
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• 2012

In our previous studies, dietary supplements of silk protein, sericin, and fibroin, were beneficial for improving epidermal levels of ceramides, which are the major lipids for maintaining the epidermal barrier. In this study, we investigated the dietary effects of silk protein on epidermal levels of free sphingoid bases and their phosphates such as $C_{18}$ sphingosine (So), $C_{18}$ sphinganine (Sa), $C_{18}$ sphingosine-1-phosphate (S1P), and $C_{18}$ sphinganine-1-phosphate (Sa1P), which are either synthetic substrate or degradative metabolites of ceramides. Forty-five male NC/Nga mice, an animal model of atopic dermatitis (AD), were divided into three groups: group CA was an atopic control and fed a control diet, group S was fed a 1% sericin diet, and group F was fed a 1% fibroin diet. Fifteen male BALB/c mice served as group C (control group) and were fed the control diet. All mice were fed with diets and water $ad$ $libitum$ for 10 weeks. Sa in group CA was lower than that in group C, but So in group CA was similar to that in group C. So and Sa were higher in groups S and F than those in group CA; So level was even higher than that in group C, and Sa level was similar to that of group C. The So/Sa ratio in group CA, which is reported to increase in AD, was significantly higher than that of group C. The So/Sa ratio was lower in groups S and F than that in group CA, and decreased further in group F. However, S1P and Sa1P in groups S and F were similar to those in group CA. Taken together, we demonstrated that silk protein, sericin and fibroin dietary supplements, increased So and Sa levels, and decreased the So/Sa ratio.

• The Korean Journal of Physiology
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• v.23 no.1
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• pp.13-21
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• 1989

The present study was designed to investigate i) the action of various nucleotides on membrane permeability of rat red blood cell and hepatocyte for $Na^{+}$ and $Rb^{+}$ ii) the characteristics of purinoceptors on these cell membranes. Blood from Sprague-Dawley rats was obtained by carotid arterial cannulation. Red blood cells were then washed 3 times with saline at $4{\circ}C$. Hepatic parenchymal cells were isolated from rat livers by using a modification of the Berry and Friend (1969) method. For the $Na^{+}$ influx studies, isolated RBC and hepatocyte were incubated in incubation medium containing $^{22}Na^{+}0.2\;{\mu}Ci/ml$ at $37^{\circ}C$. After various time intervals samples were removed from the incubation flask and washed out 3 times with ice-cold washing solutions. Cells were destroyed by adding Triton X-100 and TCA solution. After centrifugation, the supernatants were assayed for $^{22}Na^{+}$ by gamma counter. $^{86}Rb^{+}$ was used to simulate $K^{+}$ in these $K^{+}efflux$ studies. Isolated hepatocytes were incubated for 60 min in the loading solution containing $^{86}Rb^{+}\;10\;{\mu}Ci/ml$ at $37^{\circ}C$. After loading, the cells washed out 3 times by centrifugation with washing solution. The cells were incubated in buffer solution at $37^{\circ}C$. At intervals thereafter, samples were removed and centrifuged. The supernatants were analyzed for $^{86}Rb^{+}$ by liquid scintillation counter. The main results of the experiments were: 1) ATP and ATPP increased in both $^{22}Na^{+}$ influx and $^{86}Rb^{+}$ efflux in the red blood cell. Although ADP showed a tendency to increase in RBC membrane permeability for $^{22}Na^{+}$ and $^{86}Rb^{+}$, the changes were not significantly different from the control. 2) The Significant changes in $^{22}Na^{+}$ and $^{86}Rb^{+}$ flux by ATP were also demonstrated in hepatocyte. ATPP and ADP showed a tendency to increase in hepatocyte membrane permeability for both ions. 3) Other nucleoside triphosphates-ITP, GTP and CTP-did not change in membrane permeability for $^{22}Na^{+}$ and $^{86}Rb^{+}$ in RBC and hepatocyte. In conclusion, not only ATP but also ATPP activate purinoceptors and change in membrane permeability for $Na^{+}$ and $K^{+}$. In order to activate purinoceptors on the cell membrane, the nucleotides have to possess intact adenine moiety and three phosphates or more in its molecule.

• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.429-447
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• 1995

This study was designed to determine the most effective concentration of fluoride and levels of laser irradiation for the remineralization of decayed teeth. After irradiation with a pulsed Nd:YAG laser and the topical application of fluoride, phosphate and fluoride concentration in enamel were measured. And then the changes on surface enamel using an scanning electron microscope were observed. Samples by extraction healthy, permanent, mandibular bovine teeth with no caries were obtained. Among them 371 healthy samples were selected and artificial carious lesions were made. 20 samples were assigned to each experimental group. After irradiation with a pulsed Nd:YAG laser with total energy densities of 10J/$\textrm{cm}^2$, 20J/$\textrm{cm}^2$ for each group. On the teeth, 2% NaF, 1.9% NH4F, 1.6% TiF4 Elmex gel(amine fluoride) and 1.23% APF gel were applied. After pH circulatory procedures, concentrations of fluoride with and Ionalyzer (Orion Research, Model 901, USA) and phosphates with an Uv/V is spectrophotometer (Uvikon 860, Kontrom Co, Switzerland) were measured. By etching the teeth in layers and measuring fluoride concentrations, a profile of fluoride penetration according to depth could be developed. And also the changes on the surface of the enamel using an electron scanning microscope were observed. The comparative analysis yielded the following results : 1. Phosphate concentration was low in all groups compared with the control group except for teeth treated Elmex gel, irradiated with 10J/$\textrm{cm}^2$ and 30J/$\textrm{cm}^2$ energy densities. Teeth treated with APF gel and 30J/$\textrm{cm}^2$ irradiation gad the lowest phosphate concentration. 2. Among all groups, fluoride concentrations in tooth enamel were highest in APF gel and NaF groups irradiated at 30J/$\textrm{cm}^2$. The APF gel group had the highest fluoride concentrations across all energy densities. 3. In the APF gel group, and the NaF group, the greater the energy density of the laser, the higher the fluoride concentrations in the enamel. 4. In all groups, the concentration of fluoride in the enamel by depth tended to decrease with depth. 5. Under the scanning electron microscope, under the condition of irradiation with 20J/$\textrm{cm}^2$, enamel crack was detected for the first time. In the NH4F group, spherical deposits were found on the surface of the enamel, and in the TiF4 group the surface of enamel was covered with an irregular, thin membranous mass in places. In the APF gel and NaF groups irradiated with 10J/$\textrm{cm}^2$, spherical and irregular particles covered the teeth. When these groups were irradiated at 20J/cm2, they were covered with amorphous crystals. These results suggest that one could obtain more effective anticariogenic effects without damage to teeth when less than 20J/$\textrm{cm}^2$ energy densities and APF gel are used.

• Journal of the Korean Ceramic Society
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• v.18 no.4
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• pp.229-236
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• 1981

This study deals with the high temperature (600-135$0^{\circ}C$) properties of Kaolin-Phosphate-Water systems. Phosphoric acid, mono aluminum phosphate, mono ammonium phosphate, the mixture of phosphoric acid and mono aluminum phosphate, and the mixture of phosphoric acid and mono ammonium phosphate were used to characterize the M.O.R of the systems with to quantity of phosphates and firing temperature. Firing shrinkage, creeptest, DTA, TGA, and X-ray diffraction patterns were also measured in order to investigate the factors of strengthening. The resules of the experiments are as follows: 1. Linear shrinkage of kaolin-phosphate systems become larger as the firing temperature rise, and generally in the firing temperature of $600^{\circ}C$ and 100$0^{\circ}C$ the test pieces with phosphate binder show larger then Kaolin-Water system in linear shrinkage and reversed trends were found at 120$0^{\circ}C$ and 135$0^{\circ}C$. 2. Cold M.O.R. of kaolin-phosphate systems show higher trends in strength as the firing temperature rise. Comparing M.O.R. of test pieces after firing at 135$0^{\circ}C$, the mixture of phosphoric acid-mono aluminum phosphate, and phosphoric acid mono ammonium phosphate systems show higher strength than kaolin-mono aluminum phosphate system which widely used, and it shows highest strength when the mole ratio of phosphoric acid and mono ammonium phosphate is 1:1 among the test pieces of kaolin-phosphate systems. 3. The refractoriness of kaolin-phosphate systems are more deteriorated than Kaolin-Water system, and generally, the more addition of phosphate, the lower the refractoriness, however in the range of 4-8% phosphate addition, the difference of the fusion temperature is about 7$0^{\circ}C$. 4. The test pieces of T1 and T2 in creep test were same or even higher than kaolin-water system when 6% of phosphoric acid-mono ammonium phosphate was added to kaolin. 5. In case where the phosphoric acid-mono ammonium phosphate was added to kaolin in mole ratio 1:1 the cold M.O.R., after firing at 135$0^{\circ}C$, refractoriness and $T_2$ in creep test show better results than kaolin-mono-aluminum phosphate system which is widely used. 6. Phosphoric acid and mono ammonium phosphate react with kaolin in temperature over 100$0^{\circ}C$, and it forms aluminum phosphate.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.29-39
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• 2020

A series of struvite (MgNH₄PO₄·6H₂O) was synthesized and dried at various temperatures (15-60℃). Crystallization of struvite and its structural properties were significantly influenced by synthetic and drying temperature. Struvite was favorably formed at synthetic temperatures ≤30℃ with an inverse relationship between the crystallinity and synthetic temperature. The crystallinity of struvite was also significantly reduced by an increase in drying temperature from 45℃ to 60℃ due to the loss of structural water molecules and ammonium ions by the facilitated thermal decomposition. However, struvite formed at lower synthetic temperature showed higher crystallinity, and its amorphization by thermal decomposition was inhibited. These results demonstrate that struvite formed at low temperature with an stable condition thermodynamically through favorable crystallization shows high crystallinity and stability with respect to the structural and thermal resistance.