• Journal of the Korean Ceramic Society
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• v.25 no.6
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• pp.631-638
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• 1988

Effect of Ca/P mole ratio on the precipitates and powder properties of hydroxyapatite was investigated. Powder and precipitates of hydroxyapatite were synthesized by the reaction of Ca(NO3)2.4H2O and (NH4)2 HPO4 solutions at room temperature. The pH value and compositions (Ca/P mole ratio) in starting solutions were 11 and 1.64-1.79(or 1.85), respectively. Rodlike hydroxyapatite precipitates were agglomerated together. The average agglomerated particle size was ranged from 2-8${\mu}{\textrm}{m}$. Among compositions, the minimum agglomerated particle size was shown at the Ca/P mole ratio 1.75. CO2 was contained in hydroxyapatite powders and these ultrafine powders had poor crystallinity. The specific surface area and specific total pore volume of hydroxyapatite powders were 104-137$m^2$/g and 0.396-0.467cc/g, respectively. When the Ca/P mole ratio was 1.75, these values were the maximum. And water content increased with the Ca/P mole ratio(Ca/P mole ratio>1.67). In most cases, hydroxyapaite was stable to 130$0^{\circ}C$. However, in the case of Ca/P mole ratio 1.64, hydroxyapatite was changed to $\alpha$-whitlockite at 120$0^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.123-131
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• 1989

Hydroxyapatite powders were syntehsized by the reaction of Ca(NO3)2.4H2O and (NH4)2HPO4 in aqueous solution. The effect of the Ca/P mole ratio in the starting solution on the sintering of the powders and its microstructure was studied. When the Ca/P mole ratio in the starting solution was 1.69, the relative density of the sintered bodies was more than 95%. The sinterability was decreased as the Ca/P mole ratio in the starting solution was increased (Ca/P mole ratio >1.67). Hydroxyapatite sintered bodies obtained from the Ca/P mole ratio=1.69 had very excellent bending strength. The best bending strength was obtained at 110$0^{\circ}C$ and its value was 1220kg/$\textrm{cm}^2$. The average grain size was 0.277${\mu}{\textrm}{m}$. Most of sintered bodies were almost shown 100% hydroxyapatite phase. However, in case of the Ca/P mole ratio=1.64 hydroxyapatite was decomposed to $\alpha$-whitlockite above 120$0^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.3
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• pp.388-394
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• 2001

This study was conducted ton investigate the mineral contents of commercial baby foods. Samples were classified into 4 groups; powdered formula, baby juice product (domestic), juice and paste products (imported) and soymilk-based formula. We analyzed Ca, P, Mg, Na, K, Fe, Cu, Zn contents by atomic absorption spectrophotometer after dry-ashing. The difference of analyzed value versus labeled value and Ca/P ratio of analyzed value were calculated. The difference (%) of analyzed value on the labeled value was Ca: 98.6, P: 121.8, Mg: 146.1, Na: 87.4, K: 104.3, Fe: 104.8, Cu: 120.2, Zn: 109.8 in powdered formula, Mg showed the highest difference among the elements. The Ca/P ratio of powdered formula was 1.41 (1.70-1.99). Baby juice products (domestic) were fortified Ca, Fe and the difference (%) of analyzed value on labeled value of Ca and Fe contents was 131.8, 110.2, respectively. The Ca/P ratio of these was 2.36 (1.64-3.71). Differently the domestic products, imported juice and paste products were not fortified Ca, Fe and its Ca/P ratio was 0.38(0.14-0.59). The difference (%) of analyzed value on the labeled value was Ca: 110.2, Mg: 179.5, Na: 83.7, K: 87.8, Cu: 107.8, Fe: 219.8, Zn: 100.5, P: 126.6 in soymilk-based formula, Fe showed the highest difference among the elements. The Ca/P ratio of soymilk-based formula was 1.17 (1.04-0.39).

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.4
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• pp.530-536
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• 2014

In a $2{\times}2$ factorial experiment the hypotheses tested were that the metabolic acid load caused by benzoic acid (BA) added to the feed affects bone mineralization of weanling pigs, and that a wide dietary calcium (Ca) to phosphorus (P) ratio in phytase-supplemented feeds with a marginal P concentration has a positive effect on bone mineralization. The four experimental diets, which contained 0.4% P and were supplemented with 1,000 FTU phytase/kg, contained either 5 g BA/kg or no BA and either 0.77% Ca or 0.57% Ca. The 68 four-week-old Large White pigs were fed the experimental diets ad libitum for six weeks and were then slaughtered. Benzoic acid increased feed intake (p = 0.009) and growth rate (p = 0.051), but did not influence the feed conversion ratio (p>0.10). Benzoic acid decreased the pH of the urine (p = 0.031), but did not affect breaking strength and mineralization of the tibia (p>0.10). The wide Ca:P ratio decreased feed intake (p = 0.034) and growth rate (p = 0.007) and impaired feed the conversion ratio (p = 0.027), but increased the mineral concentration in the fat-free DM of the tibia (p = 0.013) without influencing its breaking strength (p>0.10). The observed positive effect of the wide Ca:P ratio on bone mineralization may be attributed, at least in part, to the impaired feed conversion ratio, i.e. to the higher feed intake and consequently to the higher mineral intake per kg BW gain. The negative impact on animal performance of the wide dietary Ca:P ratio outweighs its potentially positive effect on bone mineralization, precluding its implementation under practical feeding conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.2
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• pp.93-100
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• 2010

The calcium to phosphate ratio (Ca/P) in biphasic calcium phosphates powders using X-ray diffraction analysis (XRD) was characterized. The BCP powders with various stoichiometric Ca/P molar ratio were synthesized with coprecipitation process and calcination. Compositions of the powders with Ca/P molar ratio between 1.5 and 1.67 were subjected to starting Ca/P molar ratio, pH = 10, and thermal treatment up to $900^{\circ}C$. The structural, morphological and chemical characterizations for BCP powders with stoichiometric Ca/P ratio were carried out with scanning electron microscope (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) and a phase quantification was investigated by XRD. The solubility of HAp, $\beta$-TCP, and BCP powders was tested in the phosphate buffer solution (PBS) at $36.5^{\circ}C$ and pH = 7.4.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.3
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• pp.299-303
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• 1986

To provide useful information on the improving cultural practices of mungbean, investigations were made on Ca/Mg and (equation omitted) ratio in soil and plant grown under three fertilizer levels of N, P, K with different upland soils, using variety, Kyonggijaerae 5. Highly significant possitive correlations were observed between the soil extracted molar Ca/Mg ratio, (equation omitted) ratio at flowering time and yield, number of pods per plant, respectively. Soil-extracted Ca/Mg ratio at flowering time ranged from 1.9 to 6.4 and (equation omitted) ratio ranged from 0.17 to 0.33. Yield decreased rapidly as extracted soil Ca/Mg ratio became smaller than the ratio of 3.9, and yield was the highest the (equation omitted) ratio adjusted to 0.23 at flowering time. At harvesting time, Ca/Mg ratio in plant ranged from 1.4 to 4.3 and the yield decreased rapidly as Ca/Mg ratio in plant became smaller than 2.6. Yields, however, were not related to the soil-extracted Ca/Mg ratio interval from 3.9 to at least 6.4 in flowering time and Ca/Mg ratio in plant ranged from 2.6 to 4.3 at harvesting time.

• Journal of the Korean Ceramic Society
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• v.29 no.9
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• pp.729-738
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• 1992

The glass formation and structural change with the glass compositions were investigated in the CaO-P2O5-SiO2 system with less than 40 wt% of P2O5. The glass formation range was determined by XRD, SEM and EDS techniques for water quenched specimens. The structural analyses were made for binary CaO-SiO2 glasses and ternary CaO-P2O5-SiO2 glasses by using FT-IR and Raman spectroscopy. The glass formation was affected by CaO/SiO2 mole ratio, P2O5 content and primary crystalline phase. The stable glass formation range was found when the transformed CaO/SiO2 mole ratio (new factor derived from structural changes) was in the range of 0.72~1.15 with less than 10 mol% of P2O5. The structural analyses of CaO-SiO2 glasses indicated that as the CaO/SiO2 ratio was increased, the nonbridging oxygens in the structural unit of the glasses were increased. With addition of P2O5 to CaO-SiO2 glasses, the P2O5 enhanced the polymerization of [SiO4] tetrahedra unit in CaO-SiO2 glasses, which contained a large portion of nonbridging oxygen. The phosphate eliminated nonbridging oxygens from silicate species, forcing polymerization of silicate structures and produced in [PO4] monomer in glasses. When added P2O5 was kept constant, the structural change with various CaO/SiO2 ratio was very similar to that of CaO-SiO2 glasses.

• Journal of Nutrition and Health
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• v.26 no.6
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• pp.728-742
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• 1993

The effects of dietary calcium levels on the blood pressure and calcium metabolism were investigated. Nine normotensive female college students having hypertention family history were participated in 4-week dietary expeiments. They were provided with either high Ca diet (HCa, average 797mg/day) or low Ca diet(LCa, average 225mg/day) during two weeks, each, consecutively. Sodium amounts of the body diets were 3566~4022mg/day, which were ordinary sodium intake levels in Korea. After the HCa, systolic blood pressures(SBR) in both seated and isogrip-seated postitions were decreased by about 2.5mgHg, comparing with those after the LCa(p<.05). Diastoilc blood pressures(DBP) were not changed by dietary calcium levels. Serum total Ca, ionized Ca, Mg and P levels and Ca/Mg ratio were not different between the HCa and the LCa. Serum parathyroid hormone(PTH) levels were similar between two diets, but individually in seven of nine subjects, the slightly lower values of PTH were observed after the HCa than after the LCa. Urinary excretion of Ca(p<.01), Mg(p<.05) and P(p<.1) were increased after the HCa comparing with the LCa, but Ca/Mg ratio were not different between the two diets. SBP was in positive correlations with boty urinary excretion of Ca(supine, r=.7356, p<.05) and urinary Ca/Mg ratio(isogrip-seated, r=.7483, p<.05). SBP was also negatively correlated with serum P level(supine, r=-.6930, p<.05) and DBP was in negative correlation with urinary P excretion(seated, r=-.8586, p<.01). Serum total and ionized Ca, Mg, Ca/Mg ratio were not significantly correlated with blood pressures.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.153-158
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• 2012

Purpose: The purpose of this study was to evaluate the convergence accommodation to convergence (CA/C) ratio and to investigate relationships among age, accommodative amplitude and PD (interpupillary distance) of adults in their early twenties with normal binocular vision. Methods: 44 subjects (mean age, $21.75{\pm}1.16$ years) with healthy eyes were examined. The CA/C ratios were measured by using the difference of Gaussian (DOG) target with retinoscopy. Results: The mean CA/C ratio was $0.052{\pm}0.017$ D/$\Delta$. A moderate negative correction was present between CA/C ratio and age (r = -0.50, p = 0.0005), and a highly positive correction was found between CA/C ratio and accommodative amplitude (r = 0.79, p<0.0001). There was no relation between PD and CA/C ratio. Conclusions: The CA/C ratio presented was mean value for adults in their early twenties with healthy eye between 19 and 25 years of age. There was a high correlation between accommodative amplitude and CA/C ratio. Therefore, the CA/C ratio will be useful basic information for comparison in age, gender and binocular anomalies with similar data from other countries.

• Journal of the Korean Ceramic Society
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• v.28 no.5
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• pp.373-382
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• 1991

The effect of Ca/P mole ratio (Ca/P=1.60, 1.67, 1.75) in the initial solution on the mechanical properties of alumina added hydroxyapatite was investigated. Hydroxyapatite was synthesized by precipitation method using Ca(NO3)2$.$4H2O and (NH4)2HPO4 as starting materials and 5 wt% of ${\alpha}$-Al2O3 was added to precipitation solution. The powder was calcined at 800$^{\circ}C$ and sintered at 1,150∼1,400$^{\circ}C$ under water vapor atmosphere. With the increasing of Ca/P mole ration in the initial solution, the amount of tricalcium phosphate formed from the decomposition of hydroxyapatite reduced and the sinterability and mechanical properties were increased. The bending strength and Vickers hardness of the specimen sintered at 1,300$^{\circ}C$ with the Ca/P mole ratio of 1.75 in the initial solution were 230 MPa and 650 kg/$\textrm{mm}^2$, respectively. The improvement of mechanical properties was attributed to not only the effect of Ca/P mole ratio but also the strengthening of sintered body by Al substitution for P ions.