• Asian Journal of Atmospheric Environment
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• v.9 no.3
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• pp.228-235
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• 2015

In order to clarify the thermal and hygroscopic properties of indoor particulate matter (PM) in a semiclosed subway space, which is critically important for understanding of the distinctive particle formation processes as well as the assessment of their health effects, the size-resolved PMs (i.e., $PM_{2.5}$ and $PM_{10-2.5}$) were intensively collected on the platform of Miasageori station on the Seoul Subway Line-4. The elemental concentrations in soluble and insoluble fractions were determined by PIXE from the bulkily pretreated $PM_{2.5}$. The thermal and hygroscopic characteristics of individual particles were investigated via a combination of the unique pretreatment techniques (i.e., the high-temperature rapid thermal process and the water dialysis) and SEM-EDX analysis. Iron and calcium were unequaled in insoluble and soluble $PM_{2.5}$ fractions, respectively, with overwhelming concentration. The SEM-EDX's elemental net-counts for the pre- and post-pyrolyzed PMs newly suggest that magnesium and several elements (i.e., silica, aluminum, and calcium) may be readily involved in the newly generated subway fine PM by a high-temperature thermal processing when trains are breaking and starting. Through the water dialysis technique, it turned out that calcium has meaningful amount of water soluble fraction. Furthermore, the concentrations of the counter-ions associated with the calcium in subway $PM_{10-2.5}$ were theoretically estimated.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.1
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• pp.35-45
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• 1999

Excitatory amino acid (EAA) and substance P (SP) have been known to be primary candidates for nociceptive neurotransmitter in the spinal cord, and calcium ions are implicated in processing of the sensory informations mediated by EAA and SP in the spinal cord. In this study, we examined how $Ca^{2+}$ modified the responses of dorsal horn neurons to single or combined iontophoretical application of EAA and SP in the rat. All the LT cells tested responded to kainate, whereas about 55% of low threshold (LT) cells responded to iontophoretically applied NMDA. NMDA and kainate excited almost all wide dynamic range (WDR) cells. These NMDA- and kainate-induced WDR cell responses were augmented by iontophoretically applied EGTA, but suppressed by $Ca^{2+},\;Mn^{2+},$ verapamil and ${\omega}-conotoxin$ EVTA, effect of verapamil being more prominent and well sustained. $Ca^{2+}$ and $Mn^{2+}$ antagonized the augmenting effect of EGTA. On the other hand, prolonged spinal application of EGTA suppressed the response of WDR cell to NMDA. SP had triple effects on the spontaneous activity as well as NMDA-induced responses of WDR cells: excitation, inhibition and no change. EGTA augmented, but $Ca^{2+},\;Mn^{2+}$ and verapamil suppressed the increase in the NMDA-induced responses and spontaneous activities of WDR cells following iontophoretical application of SP. These results suggest that in the spinal cord, sensory informations mediated by single or combined action of EAA and SP can be modified by the change in calcium ion concentration.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.478-482
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• 2001

This study was conducted to get a knowledge on food components of cuttle bone (CB) as a food resource. The yields and ash contents of CB were about $7.5\%$ on whole cuttle fish and about $90\%$ on dry basis, respectively, The contents of heavy metal might not invoke health risk in using food resource, The major mineral of CB was calcium as about $22\%$ in content. The yields, proximate compositions, heavy metal and mineral contents were not significantly different between domestic and imported CB. Judging from X-ray diffraction pattern, most of calcium in CB was present as a form of calcium carbonate (CC), and scanning electron micrograph showed irregular form. Buffering capacity of CB showed strongly at pH 7, and its pattern was the same as shown in that of CC, And CB solution showed a very high degree in turbidity comparing to that of CC solution. The solubility of CB was superior to that of CC, but inferior to those of calcium powders on the market, It was concluded from above results that CB could be effectively utilized as a calcium source.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1143-1148
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• 2002

Precipitated calcium carbonate is one of the most versatile mineral fillers and is consumed in an wide range of products including paper, paint, plastics, rubber, textiles, sealants, adhesives and printing ink and can be produced by several methods. Calcium carbonate has three isomorphism; vaterite, aragonite and calcite, with numerous variations of morphology in the natural mineral or organism. Formation process of vaterite in the reaction of system $Ca(OH)_2-CH_3OH-H_2O-CO_2$ were investigated by measuring the electrical conductivity, $Ca^{2+}$ ion concentration, pH in the slurries and by means of X-ray diffraction and electron microscopic observation. It was clearly established that the reaction temperature is important variable in the carbonation process; in general over 50${\circ}C$, the vaterite was precipitated with the calcite and aragonite. SEM and XRD observations revealed that the vaterite formation could be prepared the temperature range of 40 to 50${\circ}C$ and mean size of particles in this range is controlled from 0.5 to 0.8 ${\mu}m$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.8
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• pp.1045-1050
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• 2006

Optimum operation condition for pilot scale of alkaline processing for fish muscle was investigated by measuring protein solubility, yield, texture, and water-holding capacity. Recovered protein yield was 33.2% for whole fish and 61.8% for minced muscle. Optimum homogenized speed and time, using industrial scale homogenizer, were 3,000 rpm and 5 min, respectively. Limited centrifugal force of continuous cylinder type was 4,000 rpm for recovering soluble protein, and 2,000 rpm for recovering precipitated proteins. The pH control agents such as citric acid, sodium phosphate and calcium oxide decreased the breaking force and deformation of recovered protein gel. The breaking force and deformation of the recovered proteins were high compared to conventional surimi. The breaking force and deformation were decreased by addition of salt, starch and bovine plasma proteins. Whiteness of recovered protein gel was lower than that of conventional surimi. Alkaline processing greatly decreased nitrogen content and chemical oxygen demand in waste water. The results suggest that alkaline processing has a potential as industrial production for recovering the proteins from fish muscle.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.582-587
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• 2004

Biphasic Calcium Phosphate (BCP) consisted of hydroxyapatite (HAp) and $\beta$-tricalcium phosphate (P-TCP) has been prepared by solid state reaction. The size reduction of the resultant BCP agglomerate was carried out by reaction with hot water under atmospheric condition uld also under high pressure using an autoclave. The influence of processing conditions on the change of crystalline phase and composition, relative amount of constituent, specific surface area, and microstructure was investigated by means of XRD, FT-IR, BET method using a nitrogen adsorption and SEM.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.2
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• pp.239-247
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• 2010

This study was conducted to increase the keeping quality of the minimally processed pear slices during the cold storage. Korean pears, 'Shin-go (Niitaka)', 'Chu-hwang' and 'Won-hwang’ were immersed in 1% ascorbic acid, 0.1% calcium propionate, 1% citric acid, 0.2% N-acetyl cysteine and 0.5 M 4-hexylresorcinol solution for 3 three minutes and then stored at $1{\pm}0.5^{\circ}C$ for 10 days. We have also examined into the firmness and the color difference of pears slices as affected by the application of the anti-browning agents. The firmness of pears slices which that were immersed in 0.1% calcium propionate and 0.2% N-acetyl cysteine solution were not significant at did not differ significantly after 10 days after of cold storage. However, the ${\Delta}E^*$ values of 'Shin-go' slices which that were treated with 0.1% calcium propionate and 0.2% N-acetyl cysteine solution and stored for 10 days decreased by 3.18 and 3.83, when compared with that in of the control, which decreased by 6.36. The ${\Delta}E^*$ values of 'Chu-hwang' slices which that were treated with 0.2% N-acetyl cysteine and 0.1% calcium propionate solution had the slight difference by differed by only 2.09 and 2.14, when compared with that in of the control, which differed by 3.04. The ${\Delta}E^*$ values of 'Won-hwang' slices which that were treated with 1% citric acid and 0.5 M 4-hexylresorcinol were 4.49 and 5.83, respectively, while that in of the control decreased by 8.95. It was assumed that the anti-browning agent treatment had the different activities among varieties of the pear varieties slices, however, application of 0.2% N-acetyl cysteine and 0.1% calcium propionate application had greater the higher antibrowning activity.

• Journal of Dairy Science and Biotechnology
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• v.40 no.2
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• pp.57-65
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• 2022

This study was conducted to evaluate the potential use of milk mineral (MM) as the calcium source for the production of calcium-fortified yogurt. MM was composed of 83% minerals, 7.5% lactose, 3.3% protein, and < 1% fat. Calcium (Ca) content in MM was about 46%; calcium: phosphorous ratio was 1.28:1. The aqueous solubility of Ca increased with the decrease in pH; the solubility at pH 4 and 5 was 98% and 53%, respectively. Ca-fortified yogurt with up to 200 mg Ca/100 mL did not show significant differences in acid production and number of viable cells; however, the viscosity increased significantly (p<0.05) with the increase in Ca levels. Microstructure analysis of Ca-fortified yogurt using confocal scanning laser microscopy indicated that the protein network became denser with increasing fortification with MM. There was no significant difference in the sensory quality between the control and Ca-fortified yogurts. Therefore, MM could be used for the production of Ca-fortified yoghurt without compromising the quality characteristics of yogurt.

• Polymer(Korea)
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• v.32 no.2
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• pp.178-182
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• 2008

Cellulose diacetate (CDA) and calcium carbonate ($CaCO_3$) biodegradable composites were prepared by melt mixing in a twin screw extruder and their physical properties were examined. In the melt processing, triacetine and epoxidized soybean oil were added to the composites as a plasticizer and lubricant, respectively. The optimal conditions for the preparation of the biodegradable composites were determined. Acetic acids ($CH_3COOH$) were made by pyrolysis acetyl group ($-OC (O)CH_3$) of CDA and TA in melt processing. Increasing the amount of $CaCO_3$ in the composites resulted in further enhancement of the $CH_3COOH$ absorption effects. The tensile strength and elongation were decreased, and Young's modulus and $T_g$ value increased with increasing amount of $CaCO_3$.

• Journal of the Korean Ceramic Society
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• v.41 no.9
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• pp.642-646
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• 2004

Na$_2$Si$_2$O$_{5}$ added to the solution affects the hydration of 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$ with calcium sulfate. The reaction between 4CaOㆍAl$_2$O$_3$ Fe$_2$O$_3$and CaSO$_4$ㆍ 2$H_2O$ decrease with increasing amount of Na$_2$Si$_2$O$_{5}$ in solution, owing to low hydraulic reactivity of 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$by the adsorption of silicate ions on the surface of 4CaOㆍAl$_2$O$_3$ㆍ Fe$_2$O$_3$ particles. The dissolution rate of 4CaOㆍAl$_2$O$_3$ㆍ Fe$_2$O$_3$ particles deceased with the increase of the concentration of silicate ion in solution. When the 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$ particles was hydrated in gypsum - Na$_2$Si$_2$O$_{5}$ solution, the hydration was retarded and the rate could not discriminate between formation of ettringite and that of monosulfate, and it stopped in high concentration of silicate ions. However, silicate ion did not any effect on the dissolution rate of gypsum.ypsum.