• Analytical Science and Technology
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• v.5 no.4
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• pp.401-408
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• 1992

The ion-selectrodes based on calcium ferrite were prepared by mixing calcium oxide with ferric oxide on molar ratio of 0.6:1.4, 0.8:1.2, 1.0:1.0, respectively. The specimens were sintered at $1400^{\circ}C$ for 2hrs in $O_2$ and for 20min in $H_2$ atmosphere. The selectrode sintered in hydrogen atmosphere showed better responded potential and wider range of responded concentration than selectrode sintered in oxygen atmosphere. The ion-selectrodes base on calcium ferrite(0.6:1.4 molar ratio.) showed the highest potential to bivalent cations such as $Ca^{2+}$, $Ba^{2+}$, $Mg^{2+}$, $Zn^{2+}$ and halogen anions such as $I^-$, $Br^-$ in the range of $10^{-1}{\sim}10^{-7}M$. It showed good agreement with theoretical nernstian values.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.525-534
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• 2015

The effects of aqueous calcium oxide (CaO) treatment on the quality characteristics and shelf life of mulberry (Morus alba L.) were investigated. Mulberry fruits were immersed in 0, 0.5, 1, and $2g{\cdot}L^{-1}$ CaO solutions for 0, 1, 3, 6, and 12 min. Mulberries were then rinsed with potable tap water for 1 min and stored at $-1^{\circ}C$ for 14 days. CaO treatment was effective at promoting the retention of titratable acid, pH, and ascorbic acid as well as total flavonoid contents. CaO concentration and treatment time were significant factors affecting the sensory qualities of the fruits, including off-odor, flavor, and texture. For shelf life determinations, the total bacterial count was reduced by CaO treatment so that the samples treated with $1g{\cdot}L^{-1}$ CaO for 12 min had bacterial levels at 14 days comparable to those of the control at 4 day, and no coliform group was detected after CaO treatment. These results indicate that calcium oxide treatment is a promising approach for the preservation of mulberry fruit.

• International Journal of Oral Biology
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• v.40 no.4
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• pp.211-216
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• 2015

Nitric Oxide (NO) is an important signaling molecule in the nociceptive process. Our previous study suggested that high concentrations of sodium nitroprusside (SNP), a NO donor, induce a membrane hyperpolarization and outward current through large conductances calcium-activated potassium ($BK_{ca}$) channels in substantia gelatinosa (SG) neurons. In this study, patch clamp recording in spinal slices was used to investigate the sources of $Ca^{2+}$ that induces $Ca^{2+}$-activated potassium currents. Application of SNP induced a membrane hyperpolarization, which was significantly inhibited by hemoglobin and 2-(4-carboxyphenyl) -4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (c-PTIO), NO scavengers. SNP-induced hyperpolarization was decreased in the presence of charybdotoxin, a selective $BK_{Ca}$ channel blocker. In addition, SNP-induced response was significantly blocked by pretreatment of thapsigargin which can remove $Ca^{2+}$ in endoplasmic reticulum, and decreased by pretreatment of dentrolene, a ryanodine receptors (RyR) blocker. These data suggested that NO induces a membrane hyperpolarization through $BK_{ca}$ channels, which are activated by intracellular $Ca^{2+}$ increase via activation of RyR of $Ca^{2+}$ stores.

• Journal of the Korean Applied Science and Technology
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• v.25 no.1
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• pp.15-22
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• 2008

The effects of fillers on the mechanical and thermal properties of glass/novolac composites have been studied. The matrix polymer and reinforcement were novolac type phenolic resin and milled glass fiber, respectively. Three different fillers, such as calcium carbonate, aluminum oxide, and wood powder were used for glass fiber reinforced plastic(GFRP) manufacture. Gravity, moisture content, tensile and flexural strength were measured to analyze the mechanical properties of GFRP and the final composites was burned in the electronic furnace at $1000^{\circ}C$ to confirm thermal properties GFRP containing aluminium oxide shows the highest thermal stability with 32% of weight loss at $1000^{\circ}C$ for one hour. GFRP containing calcium carbonate shows the maximum flexural strength (146 MPa), but that containing wood powder dose the highest tensile strength (65 MPa). Conclusively, we found that the characteristics of final composites strongly depend on several factors, such as types of materials, contents and chemical affinity of fillers. Therefore, it is very important to set up the combination of fillers for GFRP manufacturing to improve both mechanical and thermal properties at the same time.

• Journal of Powder Materials
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• v.16 no.5
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• pp.336-341
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• 2009

To produce alloy powders with only Sm$_2$Fe$_{17}$ single phase by reduction-diffusion (R-D) method, the effect of excess samarium oxide on the preparation of Sm-Fe alloy powder during R-D heat treatment was studied. The quantity of samarium oxide was varied from 5% to 50% whereas iron and calcium were taken 0% and 200% in excess of chemical equivalent, respectively. The pellet type mixture of samarium, iron powders and calcium granulars was subjected to heat treatment at 1100$^{\circ}C$ for 5 hours. The R-D treated pellet was moved into deionized water and agitated to separate Sm-Fe alloy powders. After washing them in deionized water several times, the powders were washed with acetic acid to remove the undesired reaction products such as CaO. By these washing and acid cleaning treatment, only 0.03 wt% calcium remained in Sm-Fe alloy powders. It was also confirmed that the content of unreacted $\alpha$-Fe in Sm$_2$Fe$_{17}$ matrix gradually decreased as the percentage of samarium oxide is increased. However, there was no significant change above 40% excess samarium oxide.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.149-159
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• 1998

To utilize the oyster shell containing a lot of calcium, we investigated the bioavailability of calcium compounds from oyster shell. First, calcium oxide was prepared by burning of oyster shell at $1200^{\circ}C$. Its purity was approximately $98.5\%$. Calcium compounds, $CaCl_2$, and $CaHPO_4$, from the calcium oxide were prepared by chemical reaction. Effect on calcium absorption by the calcium compounds from oyster shell was improved using fish skin gelatin peptides.(FSGP), which was prepared by enzymatic hydrolysis of fish skin gelatin for 4hr with tuna pyloric caeca crude enzyme (TPCCE). in vitro experiment, calcium absorption by addition of FSGP in a mixture solution of calcium and phosphate was higher approximately $70\%$ than that by control. in vivo using calcium deficient rats, a group taken the diets with $3\%$ FSGP and $CaHPO_4$ was significantly improved amount of calcium and ash in femur and strength of femur. These results suggest that calcium compounds from oyster shell and FSGP could be used as an effective dietary calcium source.

• Restorative Dentistry and Endodontics
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• v.37 no.4
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• pp.188-193
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• 2012

Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed.

• The Korean Journal of Pharmacology
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• v.31 no.3
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• pp.279-284
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• 1995

The aim of the present study was to know whether exogenously administered nitric oxide (NO) may differently modulate muscle mechanics between heart and aorta. We used PIANO method to generate NO. In isolated rat atrial tissues, neither heart rate nor contractility was affected by PIANO $(STZ,\;30{\sim}100\;{\mu}M)$. Only high concentration $(100\;{\mu}M)$ of 8-bromo cyclic GMP slightly depressed cardiac contractility. However, the same concentrations of 8-Br cGMP and PIANO significantly relaxed the rat thoracic aorta contracted with phenylephrine $(0.1\;{\mu}M)$. In isolated rabbit cardiac atrial myocytes, the amplitude of calcium currents were decreased in the whole voltage range by the presence of streptozotocin, which was further potentiated by UV light. Calcium currents were also decreased in those preparations treated with bradykinin, nitroprusside and 8-Br cGMP. These findings suggest that exogenous NO may modulate calcium current in cardiac myocyte. However, it remains why this does not affect myocardial contractility and heart rate. We concluded that NO may differently regulate calcium signal between aorta and heart muscle.

• Journal of Environmental Science International
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• v.27 no.9
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• pp.763-770
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• 2018

Bioremediation in situ is heavily dependent on the oxygenic environment which would privide the dwelling microorganism with sufficient oxygen. The situation could be easily resolved with supply of an Oxygen Releasing Compound (ORC). In this paper we prepared that sort of material out of oyster shell powder (mostly calcium carbonate) that prevails every shore areas of the country. We used two different oxidizing methods in the first step of the whole manufacturing process-conventional heating in a furnace and an ultrasound generator to obtain calcium oxide. Then that calcium oxide was further oxidized into calcium peroxide which may release oxygen under a moisturized condition. The oxygen releasing experiments were run to test the performance of our products, and to determine the gas kinetics during the experiments. Interestingly, calcium peroxide derived from ultrasound treatment was much more energy-effective as ORC than that from furnace heating although the heat derived process was better than that of ultrasound in terms of oxygen content and its releasing rate. We also found that most of the data collected from the gas releasing experiments fairly supported an ordinary $1^{st}$ order kinetics to oxygen concentration, which shaped a sharp discharge of oxygen at the very early moment of each test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.171-174
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• 2000

We have investigated the CMP slurry properties of silicate oxide thin films surface on CMP cleaning process. The metallic contaminations by CMP slurry were evaluated in four different oxide films, such as plasma enhanced tetra-ethyl-ortho-silicate glass(PE-TEOS), $O_3$ boro-phospho silicate giass( $O_3$-BPSG), PE-BPSG, and phospho-silicate glass(PSG). All films were polished with KOH-based slurry prior to entering the post-CMP cleaner. The Total X-Ray Fluorescence(TXRF) measurements showed that all oxide surfaces are heavily contaminated by potassium and calcium during polishing, which is due to a CMP slurry. The polished $O_3$-BPSG films presented higher potassium and calcium contaminations compared to PE-TEOS because of a mobile ions gettering ability of phosphorus. For PSG oxides, the slurry induced mobile ion contamination increased with an increase of phosphorus contents.