• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.3
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• pp.177-184
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• 2013

Calcium hydroxide mixture medicaments can nearly be considered to be the ideal primary tooth filling material. However, long-term application of calcium hydroxide combinations as an intra canal medicament softens dentin. The aim of this study was to evaluate the effect of calcium hydroxide on the microhardness of root dentin of primary tooth. For the study, 60 extractedprimary incisors were divided into 3 groups (no medicament, calcium hydroxide/iodorform mixture, and calcium hydroxide/distilled water mixture). After the cleansing and shaping of canals, calcium hydroxide medicaments were applied and stored for different periods of time (1, 7, 30, 90 days). The root was horizontally sectioned into 2 mm thick specimens and the microhardness was measured using Vickers microhardness tester. The results were as follows : Root dentin microhardness of primary teeth decreased with long term exposure to calcium hydroxide medicaments according to the experimental period and showed statistically significance (p < 0.05). Root dentin microhardness of primary tooth filled with calcium hydroxide mixed with distilled water showed more decrease than filled with Vitapex and showed statistically significance (p < 0.05). Root dentin microhardness of a control group without exposure to calcium hydroxide decreased according to the experimental period and showed statistically significance (p < 0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.454-460
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• 2005

The purpose of study was to observe the effect of calcium and citric acid on the dental erosion of human premolar enamel. Enamel specimens were demineralized in 0.1%, 0.3%, 0.5%, or 1.0% citric acid solutions with 0.05%, 0.1%, or 0.2% calcium for 5, 15, 30, and 60 minutes, and then the surface microhardness of the enamel was measured. The hardness decreased as the concentration of citric acid and the demineralization time increased. Hardness after 5 minutes was 76~90% in case of no calcium and the inhibition of dental erosion by calcium addition was 2??15%. Hardness after 15 minutes was 65~84% in case of no calcium and the inhibition of dental erosion by calcium addition was 3~17%. Hardness after 30 minutes was 53~72% in case of no calcium and the inhibition of dental erosion by calcium addition was 6~22%. Hardness after 60 minutes was 43~66% in case of no calcium and the inhibition of dental erosion by calcium addition was 7~19%. The inhibition was the highest in 1.0% citric acid and 0.2% calcium. In 0.1% citric acid the inhibition increased as the demineralization time increased, but in 0.3% to 1.0% citric acid the inhibition was most high at 30 minutes and decreased a little at 60 minutes. These results suggest that calcium has a inhibitory effect on the citric acid induced dental erosion.

• Horticultural Science & Technology
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• v.29 no.4
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• pp.298-305
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• 2011

This study was conducted to enhance the stem firmness of standard chrysanthemum 'Baekma' bred in Korea for commercial quality improvement and inhibition of stem breaking during transportation through foliar spray with calcium agents. Calcium agent screening 'Baekma' was examined using $CaCl_2{\cdot}2H_2O$, $Ca(NO_3)_2{\cdot}4H_2O$, and OS-Ca (natural liquid calcium compounds extracted from oyster shell) depending on each concentration (0, 0.001, 0.01, 0.1, and 1.0%, respectively). All calcium agents sprayed with 1.0% caused chemical injury such as stem bending or leaf burn. OS-Ca also showed more sensitive response to chemical injury than the other calcium agents because OS-Ca was absorbed very well by 'Baekma' leaves. Maximum stem firmness measured during the final harvest was greater in OS-Ca than in the other calcium agents. Especially, maximum stem firmness was greatest in 0.01% OS-Ca. However, elastic strength and maximum bending stress were greater in 0.001% OS-Ca than in the others. Thus, OS-Ca ranged from 0.005 to 0.05%, which did not show any chemical injury, was finally selected as the first candidate for hardening the stem of 'Baekma'. The next experiment using OS-Ca was conducted with the concentrations of 0, 0.005, 0.01, and 0.05%, respectively. From the results, 0.05% OS-Ca showed better plant growth and parameters such as plant height, stem diameter (upper and middle part), the number of leaves, and dry weights of each part than the other concentrations of OS-Ca and control. As for stem firmness depending on OS-Ca concentration, the Ca content within stem, maximum firmness, elastic strength, and maximum bending stress of stem in 'Baekma' sprayed with 0.05% OS-Ca showed the highest values among all the treatments and it turned out to be very high level of significance between control and OS-Ca treatments. However, the area and percentage of the inside cavity within horizontal stem section in 'Baekma' did not show any significance between any treatments including control. Thus, stem firmness of 'Baekma' did not show any correlation with the inside cavity area of stem. In conclusion, we recommend foliar sprays with 0.05% OS-Ca at vegetative growth stage to enhance stem firmness of 'Baekma' during transportation.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.362-368
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• 2005

The pH, alkalinity and calcium hardness could be adjusted by $CO_2$, $Ca(OH)_2$, and $Na_2CO_3$ addition in the water treatment process for corrosion protection of the water pipes. This research was performed to investigate the effect on the variation of water quality on the unit process by addition $CO_2$, $Ca(OH)_2$, and $Na_2CO_3$ in water treatment process. Carbon dioxide and lime were added before the coagulation basin and soda ash was added after the BAC process. pH and aklainity were increased at coagulation basin then after the water qualities had sustained similiarly to BAC process. There was no effect on turbidity and DOC removal efficiency during experimental period by addition\ $CO_2$, $Ca(OH)_2$, and $Na_2CO_3$ solution was added into clear well, the last process for optimum control of CCPP and is used mainly to control pH and alkalinity. In this research, average pH, alkalinity, and calcium hardness in treated water were 8.39, 61.4 mg/L as $CaCO_3$, 59.4 mg/L as $CaCO_3$, respectively and CCPP of treated water was higher than 29.5 mg/L to BAC process water, so adjusted water was expected to prevent internal corrosion of water pipe.

• Journal of Bio-Environment Control
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• v.16 no.1
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• pp.21-26
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• 2007

This study was carried out to investigate the effects of tree-spray of calcium formate compound extracted from oyster shell with several active agents on the calcium concentration, fruit skin shape and quality of 'Fuji' apple. The tree-spray of calcium formate compound extracted from oyster shell (Os-CaF, $52.4\;mg{\cdot}kg^{-1}$) appeared to have more effectiveness on the calcium translocation into leaves, fruit skin and flesh than control. Addition of adjuvants to Os-CaF increased calcium concentration of 'Fuji' apple when sprayed three times before harvest. Among the active agents examined, the treatment ascorbic acid and poly-vinyl alcohol (PVA) in leaves, Ag-colloidal and PVA in fruit skin, ascorbic acid, Ag-colloidal, and PVA in fruit flesh exhibited highest effectiveness. Fruit qualities (fruit weight, firmness, soluble solids, acidity and Hunter value) were not affect by Os-CaF on different concentrations and solutions of active agents.

• Food Science and Preservation
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• v.20 no.1
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• pp.76-80
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• 2013

This study investigated the textural changes after the calcium-pectin bonding of ginseng roots and their vinegar and calcium solution immersion. The strength and breakdown of the ginseng roots increased according to the increase in the calcium carbonate concentration, with the highest in the 0.7~1.0% calcium carbonate. The hardest and softest ginseng roots were obtained in the 1.0% calcium carbonate concentration. The strength, brittleness and hardness of the ginseng roots that were soaked in 1% calcium carbonate and 5~6% acidity vinegar continued to increase with the long-term storage of the ginseng root drink. The softness of the ginseng root that was dipped in 5% acidity vinegar with 1.0% calcium carbonate decreased with the long-term storage of the ginseng root drink. Thus, calcium and vinegar immersion of ginseng roots could prevent softening and clouding during the long-term storage of the ginseng root drink.

• Horticultural Science & Technology
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• v.32 no.5
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• pp.636-644
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• 2014

This experiment examined the effects of preharvest Ca-chitosan spraying and short-term post-harvest treatment with high $pCO_2$ on the shelf-life of 'Seolhyang' strawberry fruit. Fruit firmness decreased when harvested late in the season and was little affected by Ca-chitosan spray treatments. Short-term treatment with high $pCO_2$ after harvest, however, significantly increased fruit firmness regardless of preharvest treatment. The combined treatment of Ca-chitosan spray and high $pCO_2$ led to an additional increase in shelf-life through delay of skin disorder, fruit decay incidence and firmness loss during simulated marketing. The residual effects of both treatments, however, were reduced when fruit were harvested late in the season. Fruit firmness was more affected by high $pCO_2$ treatment whereas decay and visual quality were affected by preharvest spraying with Ca-chitosan. Although more research is required to determine the optimum concentration of calcium and chitosan, and the optimal spray interval, our results show that the combined treatment of preharvest Ca-chitosan spray and postharvest high $pCO_2$ is effective in improving strawberry fruit shelf-life by increasing firmness and delaying decay.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.561-566
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• 2010

The effects of calcium concentrations of coating bag treatment to reduce berry cracking were investigated through the changes of pericarp structure and berry cracking rate in 'Kyoho' grape. The soluble solids and anthocyanin contents in harvested grapes were highest at $18.1^{\circ}Brix$ and $2.56{\mu}g{\cdot}cm^{-2}$ in non bagging group compared with those of calcium coating bag treatments. The firmness of pericarp was lowest in non bagging group ($1.18kg{\cdot}5mm^{-1}{\O}$) compared with bagging treatments (1.23, 1.24, 1.27, $1.35kg{\cdot}5mm^{-1}{\O}$) which increased effectively in proportion to calcium concentration. As a result of histological observation of the fruit skin, the bagging with higher calcium concentration developed thicker epidermal and sub-epidermal layer of cell wall than that of non bagging. Moreover, the strengthened berry skin of calcium treatments effectively decreased berry cracking rate under critical turgor pressure. However, the 9% calcium coating bag treatment which was the most effective for cracking reduction seriously decreased marketability of harvested grape with white color staining on berry skin caused by eluted calcium from the coated paper bag. Based on our results, we recommend that 6% calcium coating bag be available for berry cracking reduction and higher quality production.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04a
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• pp.25-25
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• 1999

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.165.2-166
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• 2003

최소 가공 수박의 가공과 유통 중 품질 열화에 있어 가장 중요한 문제는 과육의 조직연화이다. 따라서 본 연구에서는 세포 분리를 제한하고 과실 조직의 경도를 유지시키는데 효과가 있는 것으로 알려져 있는 칼슘제제 중 calcium chloride, calcium lactate, CaO를 처리하여, 최소 가공 수박에서 조직연화로 발생되는 품질저하 억제에 가장 효과적인 칼슘제제를 알아보고자 하였다. 수박의 과육부위를 2cm의 정육면체 형태로 절단한 후, 0.5% calcium chloride, 0.5% calcium lactate, 0.05% CaO용액에 3분 동안 침지시켰다. 그리고 fan을 이용하여 상온에서 30분 동안 draining한 다음 PP tray에 담아 PP film로 sealing하고 $10^{\circ}C$에서 일주일간 저장하며 품질변화를 살펴보았다. 호흡특성은 0.05% CaO 및 0.5% calcium chloride용액을 처리한 구가 호흡률이 가장 낮게 나타났다. 가용성고형분은 처리 직후 처리구의 함량이 무처리구에 비해 다소 낮아지는 경향을 보였으나, 저장기간 중 0.5% calcium chloride 용액처리구는 다른 처리구에 비하여 큰 함량 변화 없이 당도가 일정 수준으로 유지되었다. pH 변화는 0.5% calcium chloride용액 처리구에서 변화가 가장 작았으며, 경도변화 역시 저장 초기값과 비교하였을 때보다 감소가 적게 일어나 다른 처리구에 비하여 연화 저해에 효과가 있는 것으로 확인되었다. 따라서 최소가공 수박에 대해 칼슘제제 중 calcium chloride용액 처리가 품질유지에 가장 효과적임을 알 수 있었다.