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Corrosion Behavior of High Pressure Die Cast Al-Ni and Al-Ni-Ca Alloys in 3.5% NaCl Solution

  • Arthanari, Srinivasan;Jang, Jae Cheol;Shin, Kwang Seon
    • Corrosion Science and Technology
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    • v.16 no.3
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    • pp.100-108
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    • 2017
  • In this investigation corrosion behavior of newly developed high-pressure die cast Al-Ni (N15) and Al-Ni-Ca (NX1503) alloys was studied in 3.5% NaCl solution. The electrochemical corrosion behavior was evaluated using open circuit potential (OCP) measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization results validated that NX1503 alloy exhibited lower corrosion current density ($i_{corr}$) value ($5.969{\mu}A/cm^2$) compared to N15 ($7.387{\mu}A/cm^2$). EIS-Bode plots revealed a higher impedance (${\mid}Z{\mid}$) value and maximum phase angle value for NX1503 than N15 alloy. Equivalent circuit curve fitting analysis revealed that surface layer ($R_1$) and charge transfer resistance ($R_{ct}$) values of NX1503 alloy was higher compared to N15 alloy. Immersion corrosion studies were also conducted for alloys using fishing line specimen arrangement to simultaneously measure corrosion rates from weight loss ($P_W$) and hydrogen volume ($P_H$) after 72 hours and NX1503 alloy had lower corrosion rate compared to N15 alloy. The addition of Ca to N15 alloy significantly reduced the Al3Ni intermetallic phase and further grain refinement may be attributed for reduction in the corrosion rate.

A Study on evaluation of biological availability of Ca from the seaweeds in rats (미역, 다시마, 파래 함유 식이가 쥐의 체내 칼슘 대사에 미치는 연구)

  • 게수경;한정순
    • Journal of Applied Tourism Food and Beverage Management and Research
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    • v.9
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    • pp.15-32
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    • 1998
  • This experiment was carried out to evaluated biological availability of calcium inthe sea mustard, sea tangle and sea lettuce in the rats. Standard diets were made to supply 0.3% of Ca from CaCO3. Consequently, levels each test ingredients to be added were sets by their Cacontents. The ingredients such as sea mustard, sea tangle and sea lettuce wereadded to basal diet at levels of 15.23%, 12.66% and 23.42% respectively. Ingredients of the basal diet were soybean protein, corn oil, alpha-cellulose, methionine, choline cholride and vitamin and mineral premix. Dextrose was added at level up to 100%. Amount of soybean protein was adjustable to make all the diets isontrogenous. Rats were fed ad libitum the diets for 13 days. The results were summarized as follow: 1. Serum calcium levels of the sea mustard group(15.23%) were higher than those of the other group, but rats fed sea lettuce diets appeared to have the lowest value. 2. Ca concentration in tibia were lower in rats fed with sea lettuce, rather than in those with standard diet. 3. Ca concentration in femur of the rats fed seaweeds did not show any significant difference among groups. 4. In the liver weight in groups fed on the all experimental groups were decreased more than that in the case of the standard diet groups.

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Fabrication and Electrical Properties of SCT thin Film with Substitution Contents of Ca (Ca 치환량에 따른 SCT 박막의 제조 및 전기적 특성)

  • Kim, Jin-Sa;Lee, Joon-Ung
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.10
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    • pp.559-563
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    • 2000
  • The $(Sr_{1-x}Ca_x)TiO_3(SCT)$ thin films are deposited on Pt-coated(Pt/TiN/$SiO_2$/Si) using RF sputtering method with substitutional contents of Ca. The maximum grain of thin films is obtained by substitution of Ca at 15[mol%]. Also the composition of SCT thin films were closed to stoichiometry(1.081∼1.117 in A/B/ ratio). The dielectric constant was increased with increasing the substitutional contents of Ca, while it was decreased if the substitutional contents of Ca exceeded over 15[mol%]. The dielectric constant changes almost linearly in temperature ranges of -80∼+90[^${\circ}C$]. The temperature properties of the dielectric loss have a stable value within 0.02 independent of the substitutional contents of Ca. All SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 2000[kHz]. The current-voltage characteristics of SCT15 thin films showed the increasing leakage current as the measuring temperature increase.

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Cyanidin-3-glucoside Inhibits ATP-induced Intracellular Free $Ca^{2+}$ Concentration, ROS Formation and Mitochondrial Depolarization in PC12 Cells

  • Perveen, Shazia;Yang, Ji Seon;Ha, Tae Joung;Yoon, Shin Hee
    • The Korean Journal of Physiology and Pharmacology
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    • v.18 no.4
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    • pp.297-305
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    • 2014
  • Flavonoids have an ability to suppress various ion channels. We determined whether one of flavonoids, cyanidin-3-glucoside, affects adenosine 5'-triphosphate (ATP)-induced calcium signaling using digital imaging methods for intracellular free $Ca^{2+}$ concentration ([$Ca^{2+}$]i), reactive oxygen species (ROS) and mitochondrial membrane potential in PC12 cells. Treatment with ATP ($100{\mu}M$) for 90 sec induced [$Ca^{2+}$]i increases in PC12 cells. Pretreatment with cyanidin-3-glucoside ($1{\mu}g/ml$ to $100{\mu}g/ml$) for 30 min inhibited the ATP-induced [$Ca^{2+}$]i increases in a concentration-dependent manner ($IC_{50}=15.3{\mu}g/ml$). Pretreatment with cyanidin-3-glucoside ($15{\mu}g/ml$) for 30 min significantly inhibited the ATP-induced [$Ca^{2+}$]i responses following removal of extracellular $Ca^{2+}$ or depletion of intracellular [$Ca^{2+}$]i stores. Cyanidin-3-glucoside also significantly inhibited the relatively specific P2X2 receptor agonist 2-MeSATP-induced [$Ca^{2+}$]i responses. Cyanidin-3-glucoside significantly inhibited the thapsigargin or ATP-induced store-operated calcium entry. Cyanidin-3-glucoside significantly inhibited the ATP-induced [$Ca^{2+}$]i responses in the presence of nimodipine and ${\omega}$-conotoxin. Cyanidin-3-glucoside also significantly inhibited KCl (50 mM)-induced [$Ca^{2+}$]i increases. Cyanidin-3-glucoside significantly inhibited ATP-induced mitochondrial depolarization. The intracellular $Ca^{2+}$ chelator BAPTA-AM or the mitochondrial $Ca^{2+}$ uniporter inhibitor RU360 blocked the ATP-induced mitochondrial depolarization in the presence of cyanidin-3-glucoside. Cyanidin-3-glucoside blocked ATP-induced formation of ROS. BAPTA-AM further decreased the formation of ROS in the presence of cyanidin-3-glucoside. All these results suggest that cyanidin-3-glucoside inhibits ATP-induced calcium signaling in PC12 cells by inhibiting multiple pathways which are the influx of extracellular $Ca^{2+}$ through the nimodipine and ${\omega}$-conotoxin-sensitive and -insensitive pathways and the release of $Ca^{2+}$ from intracellular stores. In addition, cyanidin-3-glucoside inhibits ATP-induced formation of ROS by inhibiting $Ca^{2+}$-induced mitochondrial depolarization.

Structural and Dielectric Properties of (Sr.Ca)$TiO_3$-based Ceramics with the Substitution of Ca (Ca 치환에 따른 (Sr.Ca)$TiO_3$계 세라믹스의 구조적 및 유전 특성)

  • 최운식;강재훈;서용진;김창일;김충혁;박용필
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.11
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    • pp.879-884
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    • 2001
  • In this paper, the structural and dielectric properties of (Sr$_{l-x}$Ca$_{x}$)TiO$_3$ (0$\leq$x$\leq$0.2) -based grain boundary layer ceramics were investigated by XRD, SEM and HP4194A. The ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were 1420~152$0^{\circ}C$ and 4 hours, respectively. The average grain size and the lattice constant were decreased with increasing content of Ca. The average grain size was increased with increase of sintering temperature. The relative density of all specimens was 96~98%. The 2nd Phase formed by the thermal diffusion of CuO from the surface leads to very excellent dielectric properties, that is, $\varepsilon$$_{r}$>50000, tan $\delta$<0.05, $\Delta$C<$\pm$10%. The appropriate Ca content was under 15 ㏖%.s under 15 ㏖%.%.

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Effect of Split Diets on Laying Performance and Egg Quality in Layers (산란계 사료의 오전, 오후 분리 급여 효과)

  • 이상진;김상호;강보석
    • Korean Journal of Poultry Science
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    • v.25 no.2
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    • pp.71-77
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    • 1998
  • This study was investigated to study split diets on laying performance and eggshell quality with Hy-Line brown layers 43 weeks old for 12 weeks Layers fed a conventional diet and split diets were divided into morning and afternoon diet. The conventional diet contained 3.4 % Ca was given constant nutrients all day. Hens of the split diets fed morning diets contained 0.5 % Ca constantly and afternoon diets contained 5.9, 8.0, and 10.0 % Ca in T1to T3. Split diets were given morning diets from 04:00 to 15:00 and afternoon diets 15:00 to 21 :00 alternately. Egg production, egg weight, and egg mass were not significantly different among diets. Abnormal eggs decreased in T1 and T2, but no significantly differed(P>0.05). Feed intake decreased in all of split diets compared to control diets (P <0.05). So, feed conversion ratio also improved in split diets(P<0.05). ME and CP intake decreased in T2 and T3, and Ca intake increased in proportion to Ca content of diets(P<0.05). ME and CP requirements per kg eggs decreased in the split diets, and that of Ca increased. Although there were not different significantly, egg shell strength and thickness improved slightly in T2 at 12 week. Yolk color, haugh unit and yolk index were not different among diets. Therefore, we concluded that split diet feeding to layer could improve feed and economic efficiency with normal egg production.

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Effect of $Al_2O_3$ Additives on Microwave Dielectric Properties of (Ba,Ca,Mg)-$Nd_2O_3-TiO_2+10wt%Bi_2O_3$ Ceramics ($Al_2O_3$ 첨가가 (Ba,Ca,Mg)-$Nd_2O_3-TiO_2+10wt%Bi_2O_3$ 세라믹의 마이크로파 유전특성에 미치는 영향)

  • 최지원;강종윤;하종윤;윤석진;김현재;정현진;윤기현
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.653-656
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    • 1999
  • Effect of $Al_2O_3$ Additives on Microwave Dielectric Properties of $0.15(Ba_{0.85}Ca_{(0.15-y)}Mg_y)$-0.125 $Nd_2O_3-0.60TiO_2+10wt%Bi_zO_3$ (y=0.05, 0.08) Ceramics was investigated. To control of $\tau\;{f}$ on microwave dielectric properties of $0.15(Ba_{0.85}Ca_{(0.15-y)}Mg_y)$-0.125 $Nd_2O_3-0.60TiO_2+10wt%Bi_zO_3$ ceramics $Al_2O_3$ was doped in the composition range of 0 to 0.15 wt%. As a result, dielectric constant was decreased from 94 to 80 but $Q\cdot{f}_0$ value was increased from 4980 to 5210 GHz and temperature coefficient of resonant frequency can be controlled from +9 to -10$ppm^\circ{C}$ as an increase of$Al_2O_3$ doping concentration. Especially, a new microwave dielectric material having $\varepsilon\;_r=84,\;Q\cdot{f}_0=5120\;GHz\;and\;\tau_f=0\;ppm/^\circ{C}$ was obtained at $Al_2O_3$ doping concentration of 0.08 wt%.

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Influence of Mixtures Composed of $Fe_2O_3$, $MnO_2$, $CaF_2$ and $TiO_2$ as Mineralizers on Mullitization (광화제로서 $Fe_2O_3$, $MnO_2$, $CaF_2$$TiO_2$의 혼합물이 Mullite화에 미치는 영향)

  • 백용혁;최상흘;정창주;박현수
    • Journal of the Korean Ceramic Society
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    • v.15 no.1
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    • pp.9-15
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    • 1978
  • The possiblity of mullitization from the domestic alunite by adding of $Fe_2O_3-MnO_2$, $Fe_2O_3-MnO_2-TiO_2$, $Fe_2O_3-MnO_2-CaF_2$, and $Fe_2O_3-MnO_2-CaF_2-TiO_2$ mixtures as mineralizers was studied at the temperature range between $1, 250^{\circ}C$~$1, 430^{\circ}C$. The modifying method of domestic alunite was performed by calcination, wet ballmilling, and washing with water. The following results were obtained; 1) When added of 3.0% $Fe_2O_3$ plus 1.0-1.5% $MnO_2$ to modified alunite, the appropriate temperature range of mullite-forming was $1, 350^{\circ}C$-$1, 400^{\circ}C$. 2) When added of $TiO_2$ as mineralizer, the mullite-forming temperature was higher than not added. 3) When added of $CaF_2$ as mineralizer, the synthesized mullite was resolve at the temperature above $1, 350^{\circ}C$.

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Quercetin-induced Growth Inhibition in Human Bladder Cancer Cells Is Associated with an Increase in $Ca^{2+}$-activated $K^+$ Channels

  • Kim, Yang-Mi;Kim, Wun-Jae;Cha, Eun-Jong
    • The Korean Journal of Physiology and Pharmacology
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    • v.15 no.5
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    • pp.279-283
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    • 2011
  • Quercetin (3,3',4',5,7-pentahydroxyflavone) is an attractive therapeutic flavonoid for cancer treatment because of its beneficial properties including apoptotic, antioxidant, and antiproliferative effects on cancer cells. However, the exact mechanism of action of quercetin on ion channel modulation is poorly understood in bladder cancer 253J cells. In this study, we demonstrated that large conductance $Ca^{2+}$-activated $K^+$ ($BK_{Ca}$) or MaxiK channels were functionally expressed in 253J cells, and quercetin increased $BK_{Ca}$ current in a concentration dependent and reversible manner using a whole cell patch configuration. The half maximal activation concentration ($IC_{50}$) of quercetin was $45.5{\pm}7.2{\mu}m$. The quercetin-evoked $BK_{Ca}$ current was inhibited by tetraethylammonium (TEA; 5 mM) a non-specific $BK_{Ca}$ blocker and iberiotoxin (IBX; 100 nM) a $BK_{Ca}$-specific blocker. Quercetin-induced membrane hyperpolarization was measured by fluorescence-activated cell sorting (FACS) with voltage sensitive dye, bis (1,3-dibutylbarbituric acid) trimethine oxonol ($DiBAC_4$2(3); 100 nM). Quercetin-evoked hyperpolarization was prevented by TEA. Quercetin produced an antiproliferative effect ($30.3{\pm}13.5%$) which was recovered to $53.3{\pm}10.5%$ and $72.9{\pm}3.7%$ by TEA and IBX, respectively. Taken together our results indicate that activation of $BK_{Ca}$ channels may be considered an important target related to the action of quercetin on human bladder cancer cells.

Studies on the Chemical Compositions and Distributions of Ambient Sumicron Aerosols (Submicron 부유분진의 화학적 조성 및 분포에 관한 연구)

  • 황인조;김동술
    • Journal of Korean Society for Atmospheric Environment
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    • v.14 no.1
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    • pp.11-23
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    • 1998
  • The purpose of this study was to survey chemical distribution of inorganic elements and ions in the submicron particles, to characterize qualitatively emitting sources by factor analysis, and finally to reveal existing patterns in terms of chemical compounds by a stepwise multiple regression analysis. Total of 141 samples were collected by a cascade impactor from 1989 to1996. Fifteen chemical species (Al, Ba, Cd, K, Pb, Cu, Fe, Ni, $Cl^-, NO_3^-, SO_4^{2-}, K^+, Mg^{2+}, Ca^{2+}, and Na^+$) were characterized by AAS and IC. The study showed that average seasonal levels of submicron particulate matters $(d_p<0.43 \mum)$ were 18.7 $\mug/m^3$ in spring, 15.5 $\mug/m^3$ in summer, 15.7 $\mug/m^3$ in fall, and 24.5 $\mug/m^3$ in winter, respectively. All of the anion concentrations in the particle were highest in the winter season. By applying a factor analysis, 5 source patterns were qualitatively obtained, such as sulfate related source, nitrate related source, oil burning source, calcium related source, and coal combustion source. Finally, when applying a stepwise multiple regression analysis, the results clearly showed that $Na^+ and Ca^{2+}, K^+ and Ca^{2+}, NO_3^-$ and relative humidity, $Cl^-$ and ambient temperature, $Ca^{2+} and Cl^-, Mg^{2+} and SO_4^{2-}, Na^+ and NO_3^-, and Ca^{2+} and NO_3^-$, respectively, are negatively contributed to each other. As a result of those statistical analysis, we could suggest that some chemical compounds in the submicron particles such as$NaNO_3, MgSO_4, Ca(NO_3)_2, and CaCl_2$ may not exist on the filter as final composing products; however, other compounds may possibly exist in the form of $Mg(NO_3)_2, CaSO_4, Na_2SO_4, K_2SO_4, MgCl_2, NaCl, and KCl$. Thus, it must be necessary to identify differences between the results of above statistical analysis and of the real world by laboratory experiments.

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