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Magnetic Property of BixCa1-xMnO3: Experimental and First Principles Calculation Study

  • Na, Sung-Ho;Kim, Dong-Jin
    • Journal of Magnetics
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    • v.14 no.1
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    • pp.1-6
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    • 2009
  • The magnetic properties of ${Bi_x}{Ca_{1-x}}{MnO_3}$ for x = 0.12, 0.13, 0.14, 0.15, and 0.16 were examined by measuring magnetic susceptibility, resistivity and electron magnetic resonance at different temperatures. ${Bi_x}{Ca_{1-x}}{MnO_3}$ showed complicated magnetic structure that varies with temperature and composition, particularly around Bi composition x. 0.15. The aim of this study was to determine how the magnetic and physical properties of ${Bi_x}{Ca_{1-x}}{MnO_3}$ change in this region. In addition, first principles calculations of the magnetic phase of ${Bi_x}{Ca_{1-x}}{MnO_3}$ for x = 0, 0.125, 0.25 were carried out, and the spin state, electric and magnetic characteristics are discussed.

Serum Levels of CA15-3, AFP, CA19-9 and CEA Tumor Markers in Cancer Care and Treatment of Patients with Impaired Renal Function on Hemodialysis

  • Estakhri, Rasoul;Ghahramanzade, Ali;Vahedi, Amir;Nourazarian, Alireza
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.3
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    • pp.1597-1599
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    • 2013
  • Since renal failure causes decrease in tumor marker excretion, use of these markers in cancer care and treatment in patients with renal insufficiency or hemodialysis is controversial. The aim of this study was to investigate differences of serum levels of tumor markers CA15-3, AFP, CA19-9 and CEA in patients with impaired renal function. A total of 100 patients referred to the Tabriz Immam Reza and Amiralmomenin hospital from June 2010 to November 2011 were selected for study. Subjects were divided to 3 groups of healthy, dialysis and renal failure but non hemodialysis cases, the last category being re-grouped based on creatinine clearance. No significant relationship between different groups in serum levels of CEA (P=0.99) and CA19-9 (P=0.29) tumor markers was found. A significant correlation was observed between serum levels of AFP (P<0.001) and CA15-3 (P<0.001) and also a tendency between creatinine clearance and CEA (r=0.05, P=0.625). Creatinine clearance significantly correlated with AFP (P<0.001, r=0.53) and CA15-3 (p=0.00, r=-0.412), but not CA19-9 (P=0.089, r=-0.171). According to results of this study it appears that use of tumor markers in patients with impaired renal function should be performed with special precautions.

Properties of ($Sr_{1-x}Ca_{x}$)$TiO_3$Thin Film by RF Sputtering Method (RF 스퍼터링법에 의한 ($Sr_{1-x}Ca_{x}$)$TiO_3$박막의 특성평가)

  • 김진사;조춘남;오용철;김상진;신철기;박건호;이준웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.1001-1004
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    • 2001
  • The (Sr$_{l-x}$Ca$_{x}$)TiO$_3$(SCT) thin films are deposited on Pt-coated electrode(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%]. 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. The current-voltage characteristics of SCT15 thin films showed the increasing leakage current as the measuring temperature increases.ses.

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Simulation of Slotted CSMA/CA MAC in IEEE 802.15.4 WPAN (IEEE 802.15.4 무선 PAN의 Slotted CSMA/CA MAC 시뮬레이션)

  • Lee Hae Rim;Chung Min Young;Lee Tae-Jin
    • Journal of the Korea Society for Simulation
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    • v.14 no.3
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    • pp.101-108
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    • 2005
  • IEEE 802.15.4 low-rate Wireless Personal Area Networks (WPAN) are expected to provide ubiquitous networking between small personal/home devices and sensors with low power consumption and low cost features. The technology employs special CSMA/CA (Carrier Sense Multiple Access/collision Avoidance) to save power consumption for small or portable WPAN-enabled devices. In this paper, we simulation the slotted CSMA/CA of IEEE 802.15.4 MAC and evaluate its performance limit in order to grasp the characteristics of Medium Access Control (MAC) of IEEE 802.15.4 WPAN.

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Effects of A-site Ca and B-site Zr Substitution on the Dielectric Characteristics and Microstructure of BaTiO3-CaTiO3 Composite (A-site Ca 및 B-site Zr 첨가에 의한 BaTiO3-CaTiO3복합체의 유전특성 및 미세구조에 미치는 영향)

  • 윤만순;박영민
    • Journal of the Korean Ceramic Society
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    • v.40 no.1
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    • pp.37-45
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    • 2003
  • The dielectric and sintering characteristics of composites made by substituting Ca ion to Ba-site and Zr ion to Ti site in $(Ba{1-x}Ca_x)(Ti{0.96-yZr_ySn_{0.04})O_3$ $(0.15{\leq}x{\leq}0.20,\;0.09{\leq}y{\leq}0.14)$ were investigated. As the content of Ca was more than 15 mol%, composite was formed by precipitating the second phase whose main element was $CaTiO_3$ and the fraction of the second phase was increased. The curie temperature of composites was depended on Ca concentration, $-1.7^{\circ}C$ per mol% and the maximum dielectric constant of composite was decreased by the rate of 200/mol%. The substitution of Zr ion decreased the curie temperature by the rate of $10^{\circ}C$ per mol% and the maximum dielectric constant was decreased by 217/mol% due to the increase of diffuse phase transition. The density and insulation breakdown characteristics were improved by suppressing the abnormal grain growth due to the increase of second phase. We developed the composition of Y5U (EIA standard) condenser which had high breakdown voltage and dielectric constant by controlling diffuse phase transition by the addition of Zr ion into composite.

Low-temperature Sintering and Dielectric Properties of $CaZrO_3-CaTiO_3$ Ceramics for Middle- Permittivity LTCC Substrate (중유전율 LTCC 기판용 $CaZrO_3-CaTiO_3$계 세라믹스의 저온소결 및 유전특성)

  • Park Jeong-Hyun;Choi Young-Jin;Ko Won-Jun;Park Jae-Hwan;Park Jae-Gwan
    • Journal of the Microelectronics and Packaging Society
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    • v.11 no.3
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    • pp.17-22
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    • 2004
  • The microwave dielectric properties of $CaZrO_3$ ceramics with addition of $CaTiO_3$ were studied. The effect of glass addition on the low-temperature sintering and microwave dielectric properties of $CaZrO_3-CaTiO_3$ ceramics were also evaluated to develop the materials for functional substrates of low-temperature co-fired ceramics. When $10-20 wt\%$ of lithium borosilicate glass was added, the sintering temperature of the $CaZrO_3-CaTiO_3$ ceramics decreased from $1450^{\circ}C$ to below $900^{\circ}C$. As the $T_f$ of glass frits and $CaZrO_3$ are slightly negative and that of $CaTiO_3$ is significantly positive, zero $T_f$ could be realized by mixing an appropriate amount of $CaTiO_3$ with $CaZrO_3$. The $CaZrO_3-CaTiO_3$ ceramics sintered at $875^{\circ}C$ with $15wt\%$ glass frits showed the relative density of $98\%$, permittivity of 23, quality factor of 2500 GHz, and temperature coefficient of resonant frequency of $ -3 ppm/^{\circ}C$.

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Defect Chemistry of Ca and Nb doped $BaTiO_3$ (Ca와 Nb가 첨가된 $BaTiO_3$의 결함화학)

  • Jeong, Jae-Ho;Han, Yeong-Ho;Park, Sun-Ja
    • Korean Journal of Materials Research
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    • v.4 no.7
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    • pp.798-807
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    • 1994
  • The increase in the resistance of $BaTio_{3}$ with addition of Ca is attributed to the formation ofthe acceptor impurity by $CaCa^{2+}$" which substitutes Ti4+. However, some authors suggested that $Ca^{2+}$ can not substitute $Ti^{4+}$ because of its larger ionic radius. In this work, the existence of acceptor by Ca hasbeen studied through the high temperature equilibrium electrical conductivity of $BaTiO_{3}$ codoped with Caand Nb, where Ba/(Ti+Ca+Nb) was kept equal to unity. It was measured at $1000^{\circ}C$, and the oxygenpartial pressure was controlled between $10^{-15}$ ~ 1 atm. Changing the amount of added Ca and Nbresulted in the compensation effect between donor and acceptor, i.e., Nb was compensated by the acceptor.And through the defect chemical interpretation of the measured data, it was concluded that Ti canbe substitued with Ca. The existence of such acceptor was reaffirmated by ICTS(Isotherma1 CapacitanceTransient Spectroscopy) measurements.oscopy) measurements.

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Preparation and properties of porous (Ca,Mg)0.15Zr0.7O1.7 ceramics (다공성 (Ca,Mg)0.15Zr0.7O1.7 세라믹스의 제조 및 특성)

  • Kim, Bok-Hee;Kim, Sang-Hee;Choi, Eun-Sil
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.21 no.2
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    • pp.70-74
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    • 2011
  • [ $(Ca,Mg)_{0.15}Zr_{0.7}O_{1.7}$ ]ceramics was investigated for the application to SOFC ceramic supporter with high porosity and mechanical strength. $ZrO_2$ powder was prepared by combustion method with glycine using the solution of $ZrO(NO_3)_2{\cdot}2H_2O$ dissolved into deionized water and calcination at $800^{\circ}C$ Porous $(Ca,Mg)_{0.15}Zr_{0.7}O_{1.7}$ ceramics was prepared by sintering the mixture of prepared $ZrO_2$ powder, dolomite and carbon black at $1200{\sim}1400^{\circ}C$ for 1 h. The open porosity ofthe $(Ca,Mg)_{0.15}Zr_{0.7}O_{1.7}$ ceramics sintered at $1300^{\circ}C$ was over 30 % and increased linearly with the amount of carbon black. The crystal structure of $(Ca,Mg)_{0.15}Zr_{0.7}O_{1.7}$ ceramics consisted of single cubic phase. The open pore of this ceramics was connected continuously and distributed well on the whole. This ceramics sintered at $1300^{\circ}C$ showed the porosity from 32 to 55 % and mechanical strength from 90 MPa to 30 MPa with increasing the content of added carbon black.

Effects of Ca, BSA, Heparin, Semen Storage and Individual Bull on Sperm Motility and Acrosome Reaction (Ca, BSA, Heparin, 精液의 貯藏 및 수소 個體가 精子의 活力과 尖帽反應에 미치는 影響)

  • Park, Yeong-Sik;Im, Gyeong-Sun
    • Korean Journal of Animal Reproduction
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    • v.15 no.1
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    • pp.1-6
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    • 1991
  • This study was carried out to investigate the effects of Ca, BSA, heparin, semen storage and individual bull on motility and acrosome reaction of bovine fresh sperm and sperm stored in lactose-egg yolk solution(LES) at 5$^{\circ}C$ for 4hours, and the results obtained were as follows: 1. When sperm was incubated in SCS containing Ca, BSA, Ca + BSA, heparin, heparin + Ca, heparin + BSA, and heparin + Ca + BSA for 15 minutes, there was significant difference in sperm motility among the treatments, especially BSA showed significantly higher sperm motility than the others. Also there was significant difference in sperm acrosome reaction among the treatments, especially BSA and Ca + BSA showed significantly higher sperm acrosome reaction than the others. 2. Bull KNC 1 showed significantly higher sperm motility than KNC 1, HOL 1 and 2 in both fresh and stored semen, however KNC 1 showed significantly lower sperm acrosome reaction than KNC 1, HOL 1 and 2. Therefore, there was significant difference in sperm motility and acrosome reaction among individual bulls. 3. When KNC 1 and KNC 2 sperm were incubated in SCS and SCS + Ca, SCS + BSA, SCS + Ca + BSA, SCS + heparin, SCS + heparin + Ca, SCS + heparin + BSA, and SCS + heparin + Ca + BSA, there was significant difference in sperm motility among individual bulls, especially BSA in KNC 1 and BSA, Ca and Ca + BSA in KNC 2 showedsignificantly higher motility than the others. However, there was significant difference in sperm acrosome reaction among individual bulls, Ca in KNC 1 and Ca + BSA in KNC 2 showed higher acrosome reaction than the others.

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Effect of Calcium Source using Tilapia Mossambica Scales on the Bone Metabolic Biomarkers and Bone Mineral Density in Rats (Tilapia Mossambica 비늘 (어린) 유래 칼슘소재가 흰쥐의 골격대사지표와 골밀도에 미치는 영향)

  • Yoon, Gun-Ae;Kim, Kwang-Hyeon
    • Journal of Nutrition and Health
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    • v.43 no.4
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    • pp.351-356
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    • 2010
  • This study was done to evaluate the effect of Ca source using fish (Tilapia mossambica) scales on the bone metabolism. Male Sprague-Dawley rats, 4 weeks of age, were fed low-calcium diet (0.15% Ca) for 2 weeks. The rats on the low-calcium diet were further assigned to one of following three groups for an additional 4 weeks: 1) Ca-depletion group (LoCa) given 0.15% Ca diet ($CaCO_3$), 2) Ca-repletion group (AdCa) given 0.5% Ca diet ($CaCO_3$), 3) Ca-repletion diet (AdFa) received 0.5% Ca diet (Ca source from Tilapia mossambica scales). Serum parathyroid (PTH) and calcitonin showed no differences among experimental groups. Whereas LoCa group elevated the turnover markers, serum ALP and osteocalcin, and urinary deoxypyridinoline (DPD), AdCa and AdFa groups reduced their values. Elevation in the femoral weight, ash and Ca contents was observed in AdCa and AdFa groups. Bone mineral density was increased in AdCa and AdFa groups by 25-26% compared with LoCa group. These data demonstrate that Ca repletion with either Ca source from Tilapia mossambica scales or $CaCO_3$ is similarly effective in the improvement of bone turnover markers and BMD, suggesting the usefulness of Tilapia mossambica scales in the prevention of bone loss compared with $CaCO_3$.