• Title/Summary/Keyword: CaCO%24_3%24

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Early Hydration of Tricalcium Silicate(III) (Tricalcium Silicate의 초기수화반응(III))

  • 오희갑;최상흘
    • Journal of the Korean Ceramic Society
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    • v.24 no.4
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    • pp.385-391
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    • 1987
  • Zeta potential according to the hydration time was studied during the early hydration of C3S with and without CO2 atmosphere. Zeta potential was low as a level of 20mV at the first and second exothermic peaks of heat evolution, but it was rapidly increased up to a level of 300mV. In the CO2 atmosphere, zeta potential was level of 60mV at 10 minutes hydration and it's value became a low gradually according to the hydration time. Zeta potential was also proportioned to the Ca2+ concentration in the liquid phase, i.e., there was positive correlation between zeta potential and Ca2+ concentration. The existence of silicate layer was not found out on the hydrated C3S in the CO2 atmosphere by SEM-EDAX.

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Studies on the Oocytes Activation Regimed for Nuclear Transfer and Co-culture of Nuclear Transferred Embryos

  • Kim, S. K.;Lee, D. S.
    • Proceedings of the KSAR Conference
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    • 2001.10a
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    • pp.58-58
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    • 2001
  • This study was carried out to investigate the optimal activation condition for parthenogenetic development. In order to activate oocytes at 24 hrs post onset of maturation, the oocytes were cultured 3 - 13 μM Ca for 5 min., 5-8 ㎍/㎖ cytoclacin(CH) for 6 hrs, 0.5-2.0 mM 6-dimethylaminopurine(DMAP) for 3 hrs alone or combination. The activated oocytes were cultured in TCM-199 media at 5% CO₂, 95% N₂, 38℃. 1. The cleavage rate after 48 hrs culture of oocytes treated with 3-13 μM Ca for 5 min. were 9.6%-20.0% and 3.8-7.3%, respectively. When oocyte were treated with 10 μM Ca, the blastocyst formation rate was significantly higher than other group. 2. The cleavage rate after 48 hrs culture of oocytes treated with 5-8 ㎍/㎖ cytoclacin(CH) for 6 hrs, were 9.4%-21.8% and 0.0-7.3%, respectively. When oocyte were treated with 10㎍/㎖ CH, the blastocyst formation rate was significantly higher than other group. 3. The cleavage rate after 48 hrs culture of oocytes treated with 0.5-2.0 mM 6-dimethylaminopurine(DMAP) for 3 hrs were 9.1%-21.8% and 0.0-7.3%, respectively. When oocyte were treated with 2.0mM DMAP, the blastocyst formation rate was significantly higher than other group. 4. The cleavage rate after 48 hrs culture of oocytes treated with Ca+CH, Ca+DMAP, CH+DMAP were 75.9%-93.5% and 9.7 -13.3%, respectively. When oocytes were treated with Ca followed by DMAP, the blastocyst formation rate was significantly higher than other group(p〈0.05). 5. When necleus transferred embryos co-cultured with BSA, EGF and CS, the developmental rate to blastocyst were higher than control group.

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Desalinization of marine soil by the application of straw and lime (개흙의 제염에 미치는 볏짚, 석회의 병용효과)

  • Oh, Wang-Keun
    • Korean Journal of Soil Science and Fertilizer
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    • v.24 no.1
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    • pp.35-40
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    • 1991
  • A laboratory column experiment was conducted to learn the desalinization effect of rice straw, fresh or predecayed in limed marine soil, compared with gypsum. One third of Ca equivalent to indigenous Na plus Mg of the soil was applied to the top 10g out of 80g of total column soil, mixing one half of it to the top soil and the rest spreading on the surface. 1. Pre-decaying of rice straw in limed marine soil promoted the permeability of column soil. but showed a less effectiveness in desalinization of sodium than lime alone or lime plus fresh rice straw treatemenents. 2. Gypsum and calcium carbonate treatments without rice straw fixed Mg in the limed top soil and washed it down disolving more from the layer immediatly be low the treated top soil But the treatment of calcium carbonate and rice straw both together washed out Mg more from lower layers than the upper's, showing only physical desalinization. 3. The desalinization of Na was also severe in the layer immediately below the $CaSO_4$ treated top soil, leauing more Na ilo the top soil, which seemed to be attributed to the peptisation of the top soil and retard peptisation of desalinization when washed the soil applying not enough amount or non of gypsum.

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Piezoelectric and dielectric Properties for Multilayer Piezoelectric Transformer Of Modified $PbTiO_3$ system ceramics (적층 압전 변압기용 변성 $PbTiO_3$ 세라믹스의 압전 및 유전 특성)

  • Yoo, Kyung-Jin;Yoo, Ju-Hyun;Jeong, Yeong-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.06a
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    • pp.344-345
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    • 2006
  • In this study, in order to develop low temperature sintering piezoelectric transformer, $(Pb_{0.99-x}Ca_xSr_{0.01})Ti_{0.96}(Mn_{1/3}Sb_{2/3})_{0.04}O_3$ ceramic systems were fabricated using $Na_2CO_3-Li_2CO_3$ as sintering aids and investigated with the amount of Ca substitution. The piezoelectric transformer requires high electromechanical coupling factor $k_t$ and high mechanical quality factor $Q_{mt}$ for generating high output power At the ($PbCaSr)Ti(MnSb)O_3$ ceramics with 24mol% Ca substitution sintered at $900^{\circ}C$, electromechanical coupling factor $k_t$ and mechanical quality factor $Q_{mt}$ showed the optimal values of 0.504 and 1655 respectively, for thickness vibration mode multilayer piezoelectric transformer application.

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Recycling of Wastepaper(V): -Calcium Hardness Control of Process Water for Zero-Discharge System- (고지재상연구 (제5보) -공정수 폐쇄화를 위한 칼슘경도 조절-)

  • 지경락;류정용;신종호;송봉근;오세균
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.31 no.2
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    • pp.15-24
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    • 1999
  • A new technique for recycling of white water was developed in order to reduce the calcium hardness in a closed OCC recycling system. Calcium ions present in the white water were precipitated as calcium carbonate by reacting with sodium carbonate, and the precipitated $CaCO_3$ was removed from the system using a flotation fractionation method, which has been commonly used in deinking process. In the flotation stage, a mixed gas of $CO_2$-air was purged into the flotation cell because the pH of $Na_2CO_3$-treated white water was reduced to neutral by $CO_2$ gas. Since $CaCO_3$ precipitate tends to stick onto fine fiber surface and then selectively removed from the white water, a proper amount of suspended solid in white water acts as an important factor for deciding the removal efficiency. By the application of $Na_2CO_3$ addition-$CO_2$ flotation to the short circulated white water, the calcium hardness was significantly reduced by 87% and more. Removal of calcium ions with fine fibers led to a drainage improvement, reduction of fresh water consumption, and enhanced efficiency of wet-end chemicals.

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Studies on the Porcine Oocytes Activation Regimed for Nuclear Transfer and Development Following Co-culture of Nuclear Transferred Embryos (핵 이식을 위한 돼지난자의 활성화 및 핵 이식 배와 공배양에 따른 체외발생에 관한 연구)

  • Kim, Sang-keun;Rhee, Man-hwi
    • Korean Journal of Veterinary Research
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    • v.42 no.1
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    • pp.29-33
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    • 2002
  • This study was carried out to investigate the optimal activation condition for parthenogenetic development. In order to activate oocytes at 24 hrs post onset of maturation, the oocytes were cultured $3{\sim}13{\mu}M\;Ca^{2+}$ for 5 min., $5-8{\mu}g/ml$ cytoclacin for 6 hrs, 0.5~2.0 mM 6-dimethylaminopurine(DMAP) for 3 hrs alone or combination. The activated oocytes were cultured in TCM-199 media at 5% $CO_2$, 95% air, $38^{\circ}C$. The cleavage rate after 48 hrs culture of oocytes treated with $3-13{\mu}M\;Ca^{2+}$, $5-8{\mu}g/ml$ cytoclacin and 0.5~2.0 mM DMAP for 5 min., 6 hrs and 3 hrs were 9.6%~20.0%, 0.0%~7.3% and 9.4%~21.8%, 0.0%~7.3% and 9.1%~21.8% and 0.0%~7.3%, respectively. When oocyte were treated with $10{\mu}M\;Ca^{2+}$, $10{\mu}g/ml$ cytoclacin and 2.0 mM DMAP the blastocyst formation rate was significantly higher than other group. The cleavage rate after 48 hrs culture of oocytes treated with $Ca^{2+}$ + cytoclacin, $Ca^{2+}$ + DMAP, cytoclacin + DMAP were 75.9%~93.5% and 9.7%~19.0%, respectively. When oocytes were treated with $Ca^{2+}$ followed by DMAP, the blastocyst formation rate was significantly higher than other group(p<0.05). When necleus transferred embryos co-cultured with bovine serum albumin(BSA), epithemal growth factor(EGF) and calf serum(CS), the developmental rate to blastocyst were higher than control group.

Optimization of Precipitation Process for the Recovery of Lactic Acid (Lactic acid 회수를 위한 침전공정 최적화)

  • Choi, Kook-Hwa;Chang, Yong-Keun;Kim, Jin-Hyun
    • KSBB Journal
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    • v.26 no.1
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    • pp.13-18
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    • 2011
  • In this study, precipitation process was developed for the recovery of the lactic acid from calcium lactate fermentation broth. Calcium lactate yield was improved by decreasing the solubility of calcium lactate through the addition of ethanol (25%, v/v) as a co-precipitant. The optimal lime type, lime concentration, stirrer speed, precipitation time, temperature, and solvent amount for $Ca(LA)_2$ precipitation were CaO, 0.0175 g/mL, 220 rpm, 24 h, $5^{\circ}C$, ethanol 25% (v/v), respectively. Lactic acid was easily and efficiently recovered from precipitated $Ca(LA)_2$ by adding sulfuric acid ($Ca(LA)_2/H_2SO_4$ molar ratio=1:1). In the model solution of organic acids and fermentation broth, the overall yields of recovered lactic acid were 62% and 55%, respectively, under the aforementioned optimal conditions.

Single-particle Characterization of Aerosol Samples Collected at an Underground Shopping Area (단일입자분석법을 이용한 지하상가에서 채취한 실내입자의 특성분석)

  • Kang, Sun-Ei;Hwang, Hee-Jin;Park, Yu-Myung;Kang, Su-Jin;Kim, Hye-Kyung;Ro, Chul-Un
    • Journal of Korean Society for Atmospheric Environment
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    • v.24 no.5
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    • pp.594-603
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    • 2008
  • A single particle analytical technique, named low-Z particle electron probe X-ray microanalysis, was applied to characterize four samples collected at an underground shopping area connected to Dongdeamun subway station, in January and May 2006. Based on the analysis of their chemical compositions of the samples, many distinctive particle types are identified and the major chemical species are observed to be soil-derived particles, iron-containing particles. sulfates. nitrates, and carbonaceous particles. which are encountered both in coarse and fine fractions. Carbonaceous particles exist in carbon-rich and organic. Soil derived particles such as aluminosilicates, AlSi/C, $CaCO_3\;and\;SiO_2$ are more frequently encountered in spring samples than winter samples. Nitrate- and sulfate-con taming particles are more frequently encountered in winter samples, and those nitrate- and sulfate-containing particles mostly exist in the chemical forms of $Ca(CO_3,\;NO_3),\;Ca(NO_3,\;SO_4),\;(Na,\;Mg)NO_3\;and\;(Mg,\;Na)(NO_3,\;SO_4)$. Fe-containing particles which came from nearby subway platform are in the range of about 10% relative abundances for all the samples. It is observed that nitrate- and sulfate-containing particles and carbonaceous particles are much more frequently encountered in indoor aerosol samples than in outdoor aerosols, implying that $NO_x,\;SO_x$, and VOCs at the underground shopping area were more partitioned into aerosol phase.

Early Hydration of Tricalcium Silicate(II) (Tricalcium Silicate의 초기수화반응(II))

  • 오희갑;최상흘
    • Journal of the Korean Ceramic Society
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    • v.24 no.2
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    • pp.133-138
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    • 1987
  • The behavior of CaO and SiO2 in the reaction produced which produced in the early hydration of C3S was studied by XRD and thermal analyzer. Polymerization of hydrated siltcates was also studied by TMS method. TMS derivatives were separated by gaschromatography. Cao/SiO2 molar ratios of the produced CSH gel under the air atmosphere were higher than that in the CO2. Dimerization rate of hydrated silicates was very fast in the early hydration stage. Trimer began to appear later than dimer and its increasing rate was very low. The amount of dimer and trimer formed under the CO2 atmosphere was less than that in the air.

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A Study on Effect of Inorganic Fillers to Rubber Properties (고무물성(物性)에 미치는 국산(國産) 무기충전제(無機充塡劑)의 효과(效果)에 관(關)한 연구(硏究))

  • Kim, Ki-Joo;Kim, Jong-Seok;Ahn, Byung-Kook;Suh, Soo-Kyo;Chang, Young-Jae;Kang, Kyoung-Ho
    • Elastomers and Composites
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    • v.24 no.4
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    • pp.276-289
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    • 1989
  • This study deals with both effects of inorganic fillers to vulcanized rubbers such as NR, CR, EPDM, NBR & SBR and inorganic characteristics of domestic fillers in comparision with hard clay produced in the USA. The results were as follows. 1. Main ingredient of domestic clay "Ha-dong clay" was Halloysite, "No-ha Island" was Pyrophyllite with $\alpha$-Quartz, and both of "Hard clay" & "Hwa-soon clay" were proved to be Kaolinite by XRD, DT-TGA and chemical analysis by XRF. 2. Tensile strength value of SBR compounded with these fillers, was Hard clay $146kg\;f/cm^2$, Kaolinite $123kg\;f/cm^2$, Pyrophyllite $82kg\;f/cm^2$, Halloysite $80kg\;f/cm^2$, precipitated $CaCO_3\;27kg\;f/cm^2$, and ground $CaCO_3$ was $21kg\;f/cm^2$. These results showed the increase of seven times according to filler species. 3. The physical properties of non-crystalline rubbers, such as SBR, NBR & EPDM, compared with NR & CR, have been considerably changed according to crystalline phase, particle size, shape and surface structure of fillers. Especially, tensile strength value in case of SBR & EPDM, was differentiated about 1.5 times by the particle size of fillers. 4. In SBR, physical properties of rubber compounded with Kaolinite which was surface treated with fatty acid and silane, almost approach to the value of hard clay. 5. Delayed cure time of Kaolinite and decrease of rubber properties by $CaCO_3$ can be improved by blending kaolinite & $CaCO_3$ in the ratio of 2:1.

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