• Title, Summary, Keyword: $CaCO_3$ preparation

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Characterization and Preparation of Ceramic Interconnect of SOFC by Thermal Plasma Spray Coating Process (열 플라스마 용사법에 의해 코팅된 고체산화물 연료전지용 세라믹 연결재 특성 연구)

  • Park, Kwang-Yeon;Lim, Tak-Hyoung;Lee, Seung-Bok;Park, Seok-Joo;Shin, Dong-Ryul;Song, Rak-Hyun
    • 한국신재생에너지학회:학술대회논문집
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    • pp.187-190
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    • 2009
  • $LaCrO_3$ series are the most common candidate materials for a ceramic interconnect for SOFC and the thermal expansion coefficient of these matches very well with that of YSZ electrolyte. In this study, characteristics of the coated films on the anode-support, which were formed by using $La_{0.8}Ca_{0.2}CrO_3$, $La_{0.8}Sr_{0.2}CrO_3$, $La_{0.8}Ca_{0.2}Co_{0.1}Cr_{0.9}O_3$ for ceramic interconnet for SOFC, were investigated. All powders showed single perovskite phase and the precursors had spherical shapes of $2{\mu}m{\sim}30{\mu}m$. According to SEM analysis, coated film of LCC on pretreated anode-support was more thicker, whereas the coated film on untreated anode-support was densely formed. As the results of electrical conductivity of anode-support coated with the ceramic interconnects, LCCC exhibited the most excellent electrical conductivity of 0.15S/cm at $750^{\circ}C$.

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Characteristics of Bacillus sphaericus PSB-13 as Phosphate Solublizing Bacterium Isolated from Citrus Orchard Soil (감귤원 토양에서 분리한 인산염 가용화 미생물 Bacillus sphaericus PSB-13의 특성)

  • Joa, Jae-Ho;Lim, Han-Cheol;Han, Seung-Gap;Chun, Seung-Joung;Suh, Jang-Sun
    • Korean Journal of Soil Science and Fertilizer
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    • v.40 no.5
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    • pp.405-411
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    • 2007
  • This study was carried out to measure insoluble phosphorus fractions content fixed in different soil type and isolate a superior phosphate solublizing bacteria(PSB) producing free phosphate in citrus orchard soil. Distribution of insoluble phosphate fraction ordered Al-P>Ca-P>Fe-P in the investigated citrus orchards. Insoluble phosphate fraction such as Al-P, Ca-P, Fe-P were higher in volcanic ash than in non-volcanic ash soil. A PSB with high holo zone in PDA-P medium isolated from citrus orchard soil. This strain identificated by MIDI system as Bacillus sphaericus. The optimum growth of pH and temperature were at 4~5, $30^{\circ}C$, respectively. When Bacillus sphaericus cultured at $25^{\circ}C$, 150 rpm condition in LB broth medium included different phosphate. Bacillus sphaericus produced free phosphate in the culture broth medium from tricalcium-phosphate(207.0 ppm), aluminium phosphate(324.5 ppm) and hydroxyapatite(334.8 ppm) and Phosphatase activity of Bacillus sphaericus was higher at $35^{\circ}C$ culture condition than that of $25^{\circ}C$. Two type preparation inoculated Bacillus sphaericus made with carrier materials such as Bentonite, $CaCO_3$, Sodium alginate. Density of PSB in this preparation conserved at $10^5c.f.u.\;g^{-1}$ level during storage in different temperature condition for 7 month. It also showed that free phosphate produced at PDA-P medium.

Difference of Neuronal Recovery by Incubation Condition after Transient Hypoxia (배양조건에 의한 일과성 저산소상태 후 신경세포회복의 차이)

  • Moon, Soo-Hyeon;Oh, Jae-Inn;Park, Youn-Kwan;Chung, Heung-Sub;Lee, Hoon-Kap;Lee, Ki-Chan
    • Journal of Korean Neurosurgical Society
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    • v.29 no.9
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    • pp.1161-1170
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    • 2000
  • Objective : The transverse hippocampal slice is one of the most commonly studied in vitro models of mammalian brain physiology. However, despite its broad usage, there has been no standardization of slice preparation techniques or recording condition. It is well known that variations in recording conditions can result in profound different effects to neuronal responses. Evoked field potentials, recorded extracellularly, were used to investigate the effects of variations in hippocampal slice preparation protocol on hypoxia responses of CA1 neurones. Material & Methods : Before hypoxic injury, hippocampal slices were incubated for 4 hours. During incubation period, the slices were placed in a incubation chamber($21^{\circ}C$) for recovery from preparation injury and then transferred to recording chamber($34^{\circ}C$) for more recovery and baseline electric recording with current stimulation(0.1Hz). Various time periods in incubation chamber and recording chamber were applied to each experimental group(group 1=60min : 180min, group 2=90min : 150min, group 3=180min : 60min, time in incubation chamber : time in recording chamber) before 10 min hypoxia produced by replacing 95% $O_2$+5% $CO_2$ mixed gas to 95% $N_2$+5% $CO_2$ gas. Calcium, Magnesium ions and several drugs effecting on glutamate receptor also were studied. Recoveries from hypoxic injury of hippocampal slices were estimated by percent recovery of population spike(PS). Statistic analysis of study were performed using paired t-test. Results : The percent recovery of PS after 10min hypoxia was considerably enhanced by increasing the period of current stimulation during incubation period before hypoxic injury. Temperature effect on the result of this experiment was also studied(group 4) but the result from this showed no statistic significance. Low magnesium ion concentration of artificial CSF(Mg-free aCSF) during incubation period enhanced the recovery of PS but low calcium (calcium-free) and high magnesium ion concentration(2mM) reduced it after hypoxic injury. L-glutamate($100{\mu}M$) and AP-5($50{\mu}M$) had no effect on the recovery of PS but CNQX($10{\mu}M$) in artificial CSF during incubation period markedly enhanced the recovery of PS. Co-treatment of AP-5($50{\mu}M$), CNQX($10{\mu}M$) and high magnesium concentration(2mM) enhanced recovery of PS in immediate following period of hypoxic injury but the effect of cotreatment after then decayed rapidly and lost statistic significance. Conclusions : Judging from above results, the condition of baseline recording is important in observing the recovery of population spike after hypoxia, and the time and the condition should be controled more strictly to obtain reliable results.

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Development of a Catalyst/Sorbent for Methane-Steam Reforming (메탄스팀개질반응용 촉매흡착제 개발에 관한 연구)

  • Cho, Yong-Hoon;Na, Jeong-Geol;Kim, Seong-Soo;Kim, Jin-Gul;Chung, Soo-Hyun
    • Korean Chemical Engineering Research
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    • v.44 no.3
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    • pp.307-313
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    • 2006
  • In order to improve the efficiency of methane steam reforming process, a part of the system which produces hydrogen from heavy hydrocarbon resources such as coal, we combined metal catalyst with CaO sorbent and fabricated catalyst/sorbent. To increase the porosity and the compressive strength of sorbent, carbon black and ${\alpha}-alumina$ were mixed with CaO powder during preparation. The effects of sorbent composition on the physical properties were investigated by SEM, TGA, BET, XRD, abrasion strength measuring device and adsorption-desorption instrument. Sorbent with 5 wt% $Al_2O_3$ and 10 wt% carbon black showed the best physical features with $7.61kg_f$ strength and 47% $CO_2$ adsorption capability. Various metal catalysts such as Ni, Co and Fe were supported on the sorbent developed and 10 wt% Ni/sorbent was selected for methane steam reforming process based on the result of reaction experiment. The reaction system using the catalyst/sorbent showed better $H_2$ productivity compared to the detached system with catalyst and sorbent, indicating the effectiveness of the system developed in this study.

Preparation of M Type Hexa-Ferrite Using the Mill Scale (Mill Scale을 이용한 M형 Ferrite의 합성)

  • 오영우
    • Journal of the Korean Magnetics Society
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    • v.6 no.4
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    • pp.204-210
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    • 1996
  • M type hexa-ferrites were prepared by means of a solid state reaction using mill scale, $Fe_{2}O_{3}$, and the mixture of mill scale and $Fe_{2}O_{3}$. The mixture of powders were calcined at $1150^{\circ}C$ for 2 hrs. and sintered at $1250^{\circ}C$ for 2 hrs, with varing the mole ratio of $Fe_{2}O_{3}$/$BaCO_{3}$, by 5.2~6.0. And the magnetic properties and morphologies of Baferrites with impurities such as $SiO_{2},\;Al_{2}O_{3},\;MgO,\;CaO\;and\;Na_{2}O$ in the mill scale were investigated. The magnetic properties were worsened by the addition of $Na_{2}O because of non-reacted iron oxide and intermediate compound of $BaFe_{2}O_{4}$ but they were improved apparently by the addition of $Si_{2}$ and $Al_{2}O_{3}$ in the composition of $BaO.5.6Fe_{2}O_{3}$. Moreover, $M_{s}$ decreased but $_{B}H_{C}$ increased through the addition of $Al_{2}O_{3}$ in Ba-ferrite. ${(BH)}_{max}$ of sintered BM($BaCO_{3}$, mill scale mixture) and BFM($BaCO_{3}$, $Fe_{2}O_{3}$, and null scale mixture) were 0.86 and 1.04 MGOe, respectively, and the magnetic properties were changed around $440^{\circ}C$.

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Preparation of the Tofu Coagulant from Egg-shell and It's Use (난각으로부터 두부응고제 제조와 그 이용에 관하여)

  • Kim, Joong-Man;Baek, Seung-Hwa;Hwang, Ho-Sun
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.17 no.1
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    • pp.25-31
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    • 1988
  • The crude calcium acetate (CCA) was made from egg-shell and acetic acid to use the CCA as a coagulant for Tofu (soy bean curd). Amount of CCA. $CO_2$ and residue made from 5.6g egg-shell (average weight of a egg-shell) and 10% acetic acid(50m1) was 3.8g, $300{\pm}10ml(at\;25^{\circ}$ and 2.1g. respectively. Tofu formable minimum concentration of the CCA was about 0.14% similar to that of $CaCl_2$, $MgCl_2$. Volume, hardness, taste and content f protein and lipid of Tofu by addition of CCA were not significantly different in those of Tofu that magnesium chloride and calcium chloride were used.

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A Study on the Preparation of Bone Ash and Celadon Bone Body Using Pig Bone (돼지 뼈를 이용한 Bone Ash 제조 및 청자 Bone 소지에 관한 연구)

  • Jeong, Jae-Jin;Lee, Sang-Hee;Lee, Yong-Seok;Lee, Byung-Ha
    • Journal of the Korean Ceramic Society
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    • v.44 no.1
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    • pp.12-17
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    • 2007
  • Recently, Korean food culture has westernized and the consumption of meat has been increased. As a result an enormous amount of disposal of bone is generated and most of them are buried without reutilization. By making bone ash using pig bone, the possibilities of application are examined. The purpose of this study is to establish a manufacturing process of bone ash for the celadon bone body using pig bone. The calcination of the pig bone was mostly to change to the calcium phosphate hydroxide $(Ca_5(PO_4)_3OH)$. The celadon body mixed with pig bone ash 8%, $CaCO_3$ 9%, when fired at $1240^{\circ}C$ under reduction atmosphere, shows 0.1% of water absorption, 65.23 MPa of bending strength.

Preparation and Application of CSA Expansive Additives Using Industrial Wastes (산업폐기물을 이용한 CSA계 팽창재 제조 및 응용)

  • Yoon Sung-Won;Rho Jae-Seong
    • Journal of the Korea Concrete Institute
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    • v.16 no.3
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    • pp.369-374
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    • 2004
  • Calcium sulfoalumiante(CSA) was prepared for using natural calcite($CaCO_3$) and industrial by-products and wastes, such as $Al(OH)_3,\;CaSO_4{\cdot}2H_2O$. The mixture of raw materials was fired at 20, 400, 600, $1200^{\circ}C$ for 1h and cooled rapidly in air. The cement replaced by 10 wt% $C_4A_3S$ expansive additives was investigated by the measurement of the hydration products and compressive strength, setting time, expansion at wet curing condition. $C_4A_3S$ was found in x-ray diffraction pattern over the temperature $1200^{\circ}C$. The setting time or the cement pastes added clinkers fired at different temperature was shorter than ordinary portland cement. The compressive strength was higher than the ordinary portland cement about 20~30%. The mainly hydration products were ettringite, and $Ca(OH)_2$. The expansion due to the formation of ettringite during hydration decreased the drying shrinkage of hardened cement rather than the ordinary portland cement.

Volatile Flavor Compounds from Pear Juice (Pyrus pyrifolia cv. Niitaka) (배주스의 휘발성 향기성분)

  • Kim, Mi Young;Seo, Won Ho;Huang, Ying
    • The Korean Journal of Food And Nutrition
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    • v.31 no.6
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    • pp.890-896
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    • 2018
  • The aim of this study was to determine volatile flavor compounds in Shingo pear juice. Volatile flavor compounds were analyzed using solid-phase micro-extraction (SPME) - gas chromatography-mass spectrometry (GC-MS). The effect of inorganic salts solution on the extraction ability of the SPME fiber was treated by adding saturated $CaCl_2$ solution at the ratio of 1:20 (v/v) after 0, 60, 120 min of preparing pear juice, respectively. As a result, a total of 22 volatile compounds were identified in Shingo pear juice. Ethyl acetate was found to be the most abundant volatile compound ($13.36{\sim}19.61{\mu}g/kg$), followed in order by hexanal, ethyl hexanoate, ethyl 3-(methylthio)-2-propenoate, ethyl octanoate and 2-hexenal. Total contents of volatile flavor compounds were $31.07{\mu}g/kg$ (control), $40.93{\mu}g/kg$ (0 min), $27.62{\mu}g/kg$ (60 min) and $26.32{\mu}g/kg$ (120 min). This result indicated that the addition of saline solutions could inhibit the enzymatic reaction of volatile flavor compounds effectively when treated as soon as juice preparation.

Study on the Hollow Fiber Nano-composite Membrane Preparation onto the Porous PVDF Membrane Surfaces using the Interfacial Polymerization (다공성 PVDF 막의 polyamide 계면중합법처리를 통한 나노 중공사 복합막 제조 연구)

  • Kang, Su Yeon;Cho, Eun Hye;Kim, Ihl hyung;Kim, Cheong Sik;Rhim, Ji Won
    • Membrane Journal
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    • v.24 no.2
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    • pp.107-112
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    • 2014
  • The composite membranes were prepared on the surface of hydrophobic porous poly (vinylidene fluoride) (PVDF) hollow fiber membranes through the interfacial polymerization. The preparation variables were the concentrations of piperazine (PIP), trimesoyl chloride (TMC) and the contents of polyethylene glyco l (PEG). The separation characterization of the resulting membranes were carried out for aqueous 100 ppm solution of NaCl, $CaSO_4$, and $MgCl_2$ and also mixed 300 ppm solution of NaCl and $CaSO_4$ in terms of the flux and rejection. Both the flux and rejection were the highest when the interfacial polymerization was conducted using TMC. When TMC concentration was 0.1 wt%, the flux and rejection were shown 48.3 LMH ($L/m^2{\cdot}hr$) and 59%, respectively. To improve the flux, the annealing post-treatment and the addition of PEG into piperazine were done. As expected, the overall flux was enhanced while the rejection was reduced.