• Journal of dental hygiene science
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• v.22 no.3
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• pp.191-198
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• 2022

Background: The purpose of this study was to evaluate the composition of the crystal phases of various calcium silicate-based materials (CSMs): ProRoot white MTA^Ⓡ (mineral trioxide aggregate) (WMTA), Ortho MTA^Ⓡ (OM), Endocem MTA^Ⓡ (EM), Retro MTA^Ⓡ (RM), Endocem Zr^Ⓡ (EN-Z), Biodentine^TM (BD), EZ-seal^TM (EZ), and OrthoMTA III (OM3). Methods: In a sample holder, 5 g of the powder sample was placed and the top surface of the material was packed flat using a sterilized glass slide. The prepared slides were mounted on an X-ray diffraction (XRD) instrument (D8 Advance; Bruker AXS GmbH, Germany). The X-ray beam 2θ angle range was set at 10~90° and scanned at 1.2° per minute. The Cu X-ray source set to operate at 40 kV and 40 mA in the continuous mode. The peaks in the diffraction pattern of each sample were analyzed using the software Diffrac (version 2.1). Then, the peaks were compared and matched with those of standard materials in the corresponding Powder Diffraction File (PDF-2, JCPDS International Center for Diffraction Data). A powder samples of the materials were analyzed using XRD and the peaks in diffraction pattern were compared to the Powder Diffraction File data. Results: Eight CSMs showed a similar diffraction pattern because their main component was calcium silicate. Eight CSMs showed similar diffraction peaks because calcium silicate was their main component. Two components were observed to have been added as radiopacifiers: bismuth oxide was detected in WMTA, OM, and EM while zirconium oxide was detected in RM, EN-Z, BD, EZ, and OM3. Unusual patterns were detected for the new material, OM3, which had strong peaks at low angles. Conclusion: It was caused by the presence of Brushite, which is believed to have resulted in crystal growth in a particular direction for a specific purpose.

• Korean journal of food and cookery science
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• v.24 no.6
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• pp.876-881
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• 2008

The aim of this study was to evaluate the quality characteristics and antioxidant activities of green tea garlic paste added calcium. Garlic was heated with green tea and charcoal at high temperature ($120^{\circ}C$) and high pressure ($1.5\;kgf/cm^2$) for 20 min, and then added several calcium sources (calcium carbonate, calcium citrate, calcium lactate, mixed calcium, calcium powder). Calcium carbonate, mixed calcium or calcium powder significantly increased pH of green tea garlic paste (p<0.05). All kinds of calcium sources significantly increased the viscosity of green tea garlic paste (p<0.05). Solid soluble content of green tea garlic paste was increased only in calcium citrate and calcium powder groups. Lightness, redness and yellowness of green tea garlic paste with calcium were increased, compared with control group (green tea garlic paste without calcium). The antioxidant activities by DPPH and hydroxyl radical scavenging activity of green tea garlic paste added calcium citrate, calcium lactate or calcium carbonate group were much higher than those of the other control groups. The garlic odor and garlic taste by sensory test were significantly weaker in calcium carbonate or calcium citrate group (p<0.05). Based on these results, it was suggested that calcium carbonate or calcium citrate is appropriate material for deodorizing and fortifying agent for green tea garlic paste.

• Journal of Powder Materials
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• v.26 no.6
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• pp.493-501
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• 2019

In this work, ultra-fine calcium oxide (CaO) powder derived from eggshells is used as the starting material to synthesize mineral trioxide aggregate (MTA). The prepared CaO powder is confirmed to have an average particle size of 500 nm. MTAs are synthesized with three types of fine CaO-based powders, namely, tricalcium silicate (C3S), dicalcium silicate (C2S), and tricalcium aluminate (C3A). The synthesis behavior of C3S, C2S and C3A with ultra-fine CaO powder and the effects of C₃A content and curing time on the properties of MTA are investigated. The characteristics of the synthesized MTA powders are examined by X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), and a universal testing machine (UTM). The microstructure and compressive strength characteristics of the synthesized MTA powders are strongly dependent on the C3A wt.% and curing time. Furthermore, MTA with 5 wt.% C3A is found to increase the compressive strength and shorten the curing time.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.1-9
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• 2015

In this study, the objective of the study is to evaluate the effect of calcium carbonate powder, produced by the microbial reactions, on the strength of soft ground (sand). To analyze the cementation effects of calcium carbonate powder produced by microbial reactions on the strength of the sand, six different types of specimens (untreated, calcium carbonate, cement, carbonate+cement (1:9, 3:7, 5:5)) were made. The specimen were tested after curing (7 and 28 days). Uniaxial compressive strengths were measured on $D5cm{\times}H10cm$ specimens. Based on the test results, as both the weight ratio and the curing period increase, calcium carbonate, cement, and calcium carbonate+cement specimens showed an increase in the strength. In addition, compared with the strength of the specimen with cement, the strengths of the specimens with mixing ratios of 1:9, 3:7, and 5:5 (carbonate : cement) were found to be 93.5~95.8%, 825.%, 65.2~70.6%.

• Korean journal of food and cookery science
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• v.26 no.2
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• pp.188-197
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• 2010

In this study, the quality characteristics and storage properties of gat kimchi added with oyster shell powder and Salicornia herbacea powder were investigated during a storage time of 80 days at $5^{\circ}C$. After storage for 80 days, the average calcium contents were significantly higher in the kimchi containing the oyster shell powder and Salicornia herbacea powder than the control. In addition, the average hardness value was significantly higher in the OS4 group(oyster shell powder at 4% and Salicornia herbacea powder at 2%) than the control group, as well as the OS10 group(oyster shell powder at 10% and Salicornia herbacea powder at 2%) during storage for 80 days. The hunter b value of the OS4 group was significantly lower than the control group. During fermentation, gat kimchi containing the oyster shell powder and Salicornia herbacea powder had a higher pH and a lower acidity value than the control group. In terms of sensory evaluation, there were no significant differences between the control and calcium-added kimchi during fermentation. After 40 days of storage, the OS4 group showed a lower total viable count, as well as lower lactic acid bacteria, yeast and E. coli, as compared with the control and OS10 groups. Based on the microbial load, the gat kimchi containing the oyster shell powder showed limitations in terms of shelf life.

• Journal of Powder Materials
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• v.26 no.4
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• pp.334-339
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• 2019

To meet the current demand in the fields of permanent magnets for achieving a high energy density, it is imperative to prepare nano-to-microscale rare-earth-based magnets with well-defined microstructures, controlled homogeneity, and magnetic characteristics via a bottom-up approach. Here, on the basis of a microstructural study and qualitative magnetic measurements, optimized reduction conditions for the preparation of nanostructured Sm-Co magnets are proposed, and the elucidation of the reduction-diffusion behavior in the binary phase system is clearly manifested. In addition, we have investigated the microstructural, crystallographic, and magnetic properties of the Sm-Co magnets prepared under different reduction conditions, that is, $H_2$ gas, calcium, and calcium hydride. This work provides a potential approach to prepare high-quality Sm-Co-based nanofibers, and moreover, it can be extended to the experimental design of other magnetic alloys.

• Applied Biological Chemistry
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• v.41 no.2
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• pp.175-180
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• 1998

As a part of investigation for quality improvement of surimi gel from fish with a red muscle by addition of calcium-based powder from fish bone, we investigated the processing condition of calcium-fortified mackerel surumi gel and its quality stability during storage at $5^{\circ}C$. Judging from the results of the soluble calcium content and jelly strength, the reasonable addition concentration of calcium-based powder from Alaska pollack bone for improvement of functional properties in surimi gel was revealed 0.9% on the weight basis of the chopped mackerel meat. The soluble calcium content of the calcium-fortified surimi gel (105.0 mg/100 g) was more than that of the ordinary surumi gel (2.9 mg/100 g). During cold storage of calcium-fortified surumi gel, the moisture contents, amino acid compositions, soluble calcium and phosphorus contents were little changed, the pH, volatile basic nitrogen contents, histamine contents, peroxide values and brown pigment formation were slightly increased and viable cell counts and coliform groups were not detected. The calcium-fortified surimi gel was superior in the lysine and calcium contents, EPA and DHA compositions to the ordinary surumi gel. Judging from the results, it was suggested that calcium-fortified surumi gel was nutritive, functional and safety foods.

• Journal of Microbiology and Biotechnology
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• v.29 no.12
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• pp.1982-1992
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• 2019

The alkaliphilic, calcium carbonate precipitating Bacillus sp. strain AK13 can be utilized in concrete for self-repairing. A statistical experimental design was used to develop an economical medium for its mass cultivation and sporulation. Two types of screening experiment were first conducted to identify substrates that promote the growth of the AK13 strain: the first followed a one-factor-at-a-time factorial design and the second a two-level full factorial design. Based on these screening experiments, barley malt powder and mixed grain powder were identified as the substrates that most effectively promoted the growth of the AK13 strain from a range of 21 agricultural products and by-products. A quadratic statistical model was then constructed using a central composite design and the concentration of the two substrates was optimized. The estimated growth and sporulation of Bacillus sp. strain AK13 in the proposed medium were 3.08 ± 0.38 × 10⁸ and 1.25 ± 0.12 × 10⁸ CFU/ml, respectively, which meant that the proposed low-cost medium was approximately 45 times more effective than the commercial medium in terms of the number of cultivatable bacteria per unit price. The spores were then powdered via a spray-drying process to produce a spore powder with a spore count of 2.0 ± 0.7 × 10⁹ CFU/g. The AK13 spore powder was mixed with cement paste, yeast extract, calcium lactate, and water. The yeast extract and calcium lactate generated the highest CFU/ml for AK13 at a 0.4:0.4 ratio compared to 0.4:0.25 (the original ratio of the B4 medium) and 0.4:0.8. Twenty-eight days after the spores were mixed into the mortar, the number of vegetative cells and spores of the AK13 strain had reached 10⁶ CFU/g within the mortar. Cracks in the mortar under 0.29 mm were healed in 14 days. Calcium carbonate precipitation was observed on the crack surface. The mortar containing the spore powder was thus concluded to be effective in terms of healing micro-cracks.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.77-82
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• 2003

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of high-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder. After making origin cement paste, then processing the accelarated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions. As a result of the thermal analysis, the CaCo3 content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because CaCo3 content is increased when neutralization is progressed. And as a result of XRD analysis, in case of origin powder of non-neutralized paste, CaO peak is found at 700℃. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at 700℃ shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%. However, it would be quite difficult to manage quality of recycle cement according to recycling points of various concrete waste.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.77-82
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• 2003

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of hish-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder After making origin cement paste, then processing the accelerated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions As a result of the thermal analysis, the CacO3 content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because CacO3 content is increased when neutraliTation is preBlessed. And as a result of XRD analysis. in case of origin powder of non-neutralized paste, CaO peak is found at $700^{\circ}C$. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at $700^{\circ}C$ shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%. However, it would be quite difficult to manage quality of recycle cement according to recycling points of various concrete waste.