• 제목/요약/키워드: Strontium

검색결과 399건 처리시간 0.031초

용융염법에 의한 strontium barium niobate 분말 합성 및 분말의 형상 변화 (Powder synthesis and morphology changes of strontium barium niobate by molten salt method)

  • 윤상옥;박상엽
    • 한국결정성장학회지
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    • 제6권4호
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    • pp.501-508
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    • 1996
  • NaCl-KCl 용융염을 사용하여 strontium barium niobate 분말을 합성하였으며 반응온도, 시간 및 용융염의 첨가량 변화에 따른 반응과정 및 입자 형상 변화를 조사하였다. 반응 온도 및 반응 시간이 증가함에 따라 반응율은 증가하였으며, 분말의 형상은 덩어리 형태에서 침상형태로 변화하였다. 용융염의 첨가량 증가에 따라 반응율은 크게 증가하였으나, 분말의 형상은 침상형태에서 구상형태로 변화하였다. NaCl-KCl 용융염을 사용한 합성법에 의해 융제비가 1인 경우 $1000^{\circ}C$에서, 융제비가 4인 경우 $650^{\circ}C$에서 반응율 90 % 이상의 strontium barium niobate 분말 합성이 가능하였다.

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식물체 내에서 Strontium의 대사 : 밀(Triticum aestivum L.)의 발아과정중 Polyamine 생합성에 미치는 Strontium의 영향 (Strontium Metabolism in Higher Plants: Effect of Strontium of the Polyamine Biosynthesis during Germination of Wheat(Triticum aestivum L.))

  • 김태완;게오르그하인리히
    • 한국환경농학회지
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    • 제14권1호
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    • pp.55-71
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    • 1995
  • 소맥 종자의 발아 과정중 strontium의 생리적 작용을 규명하기 위해 초엽, 종근 및 배유에서의 free amine의 함량변화가 측정되었다. $GA_3$를 포함한 배양액에 strontium 농도의 증가는 종근에서의 putrescine과 초엽에서의 spermidine의 축적을 현저히 유발하였다. $10\;{\mu}M$ 정도의 저농도에서도 strontium에 의한 putrescine 증가는 뚜렷한 반면, spermidine 증가는 10 mM의 고농도 처리에서 현저했다. 종근 생장을 억제하는 1mM 내지 10mM의 strontium 농도에서, g 생체중당 putrescine 수준은 동일농도 calcium 처리에서 보다 각각 22.4배와 15.3배 높았다. 특히 putrescine과 spermidine 증가에 의한 총 free amine 수준의 중가는 생체중 대비 뿐만이 아닌 RNA 함량 대비에서도 중요한 생리적 반응으로 보여졌다. Strontium과 대조적으로 고농도 calcium (10 mM) 처리는 초엽과 종근에서의 agmatine과 cadaverine 함량의 증가를 유발했다. Cadaverine은 calcium을 처리했을 경우에만 검출되었다. 그러나 $1\;{\mu}M$ 에서 1 mM 수준의 calcium 처리는 총 free amine 함량의 감소를 가져왔다. Strontium과 calcium 존재하에서의 발아과정중 축적되는 amine 종류의 차이와 총 free amine 중 diaminine 비율과 총 free amine 중 Polyamine 비율의 변화는 strontium과 calcium 간의 생리적 대사반응의 차이중 하나로 판단되었다.

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숙주의 발아과정 동안 폴리아민 생합성과 Diamine 산화효소에 대한 스트론티움 효과 (Effect of Strontium on Polyamine Synthesis and Diamine Oxidase during the Germination of Mung Bean (Vigna radiata L.))

  • 김태완;권영업;윤승길
    • 한국토양비료학회지
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    • 제36권6호
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    • pp.437-444
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    • 2003
  • 본 연구는 고등식물 세포 내 대사작용에 대한 스트론티움의 역할을 구명하고자 수행되었다. Strontium에 의한 diamine 산화효소의 활성화로 putrescine의 함량은 감소하였다. 배축에서의 diamine 산화효소의 활성은 $0.5-1.8\;mol\;putrescine\;oxidation\;mg^{-1}\;protein\;min^{-1}$이었다. 자엽에서의 putrescine 감소는 적어도 diamine 산화효소에 의한 putrescine의 산화의 결과였다. 더 나아가 strontium 1-10 mM 처리에 의해 spermidine과 spermine 의 축적이 관찰되었다. strontium이 없는 대조구에 비해 spermldine은 2-3배 증가하였다. 이러한 증가는 생체중을 기준으로 하였을 경우뿐만 아니라 RNA를 기준으로 하였을 경우에도 동일한 결과였다. 결론적으로 이러한 결과는 strontium이 diamine 산화 및 polyamine 축적과 같은 polyamine의 대사와 관련되어있음을 보여주었다.

골막기원세포에서 strontium에 의한 조골세포 표현형의 활성 (STIMULATION OF OSTEOBLASTIC PHENOTYPES BY STRONTIUM IN PERIOSTEAL-DERIVED CELLS)

  • 김신원;김욱규;박봉욱;하영술;조희영;김정환;김덕룡;김종렬;주현호;변준호
    • Maxillofacial Plastic and Reconstructive Surgery
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    • 제32권3호
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    • pp.199-206
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    • 2010
  • This study investigated the effects of strontium on osteoblastic phenotypes of cultured human periostealderived cells. Periosteal tissues were harvested from mandible during surgical extraction of lower impacted third molar. Periosteal-derived cells were introduced into cell culture. After passage 3, the periostealderived cells were further cultured for 28 days in an osteogenic induction DMEM medium supplemented with fetal bovine serum, ascorbic acid 2-phosphate, dexamethasone and at a density of $3{\times}10^4$ cells/well in a 6-well plate. In this culture medium, strontium at different concentrations (1, 5, 10, and 100 ${\mu}g$/mL) was added. The medium was changed every 3 days during the incubation period. We examined the cellular proliferation, histochemical detection and biochemical measurements of alkaline phosphatase (ALP), the RT-PCR analysis for ALP and osteocalcin, and von Kossa staining and calcium contents in the periostealderived cells. Cell proliferation was not associated with the addition of strontium in periosteal-derived cells. The ALP activity in the periosteal-derived cells was higher in 5, 10, and 100 ${\mu}g$/ml strontium-treated cells than in untreated cells at day 14 of culture. Among the strontium-treated cells, the ALP activity was appreciably higher in 100 ${\mu}g$/ml strontium-treated cells than in 5 and 10 ${\mu}g$/ml strontium-treated cells. The levels of ALP and osteocalcin mRNA in the periosteal-derived cells was also higher in strontium-treated cells than in untreated cells at day 14 of culture. Their levels were increased in a dose-dependent manner. Von Kossa-positive mineralization nodules were strongly observed in the 1 ${\mu}g$/ml strontium-treated cells at day 21 and 28 of culture. The calcium content in the periosteal-derived cells was also higher in 1 ${\mu}g$/ml strontium-treated cells at day 28 of culture. These results suggest that low concentration of strontium stimulates the osteoblastic phenotypes of more differentiated periosteal-derived cells, whereas high concentration of strontium stimulates the osteoblastic phenotypes of less differentiated periosteal-derived cells. The effects of strontium on osteoblastic phenotypes of periosteal-derived cells appear to be associated with differentiation-extent.

지지막을 이용한 액막 추출기에 의한 합성해수 중의 $Sr^{2+}$ 이온 분리 (Separation of $Sr^{2+}$ Ion from Seawater by Liquid Membrane Permeator with Two Micro-Porous Films)

  • 주창식;이회근;정갑섭
    • 한국환경과학회지
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    • 제9권6호
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    • pp.517-522
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    • 2000
  • Separation of strontium ion from synthetic seawater in the contained liquid membrane permeator with two micro-porous films was performed. The permeator consisted of a liquid membrane and two cells for aqueous solutions. The liquid membrane consisted of $D_2EHPA(di-2-ethylhexy1-phosphoric acid)$ and DCH18C6 (dicyclohexano-18-crown-6),diluted to 30 vol% with kerosine and was trapped between two micro-porous hydrophilic films. This liquid membrane separated two aqueous solutions, one of which was synthetic seawater and the other of which was the stripping solutions consisting of 1mol/L $H_2SO_4$ solution. The effects of various operating parameters on the extraction rate and equilibrium extraction ratio of strontium ion from synthetic seawater were experimentally examined. The addition of DCH18C6 to the $D_2EHPA$ solution caused synergy effect on the extraction of strontium ion. The permeator extracted strontium ion from synthetic seawater effectively with high membrane life time.

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골 대체재로의 스트론튬(Sr)이 고용된 Hydroxyapatite (Sr-containing Hydroxyapatite for Bone Replacement)

  • 최정신;박홍채;윤석영
    • 한국세라믹학회지
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    • 제45권10호
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    • pp.589-593
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    • 2008
  • The hydroxyapatite with different amounts of strontium was synthesized with wet chemical technique. The structural, morphological and chemical characterizations for the prepared hydroxyapatite with various strontium amounts were carried out with XRD, SEM, EDS, and FT-IR. Strontium is quantitatively incorporated into hydroxyapatite where its substitution for calcium provokes a well distribution in the EDS mapping and a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups, coherent with the greater ionic radius of strontium.

한국식품 중의 방사능 함량 (제4보) 한국 우유의 스트론튬-90 함량 (Fallout Radioactivity in Korean Foodstutts (Part 4) Stronitium-90 in Liquid Whole Milk Produced in Korea)

  • 양경린
    • 대한화학회지
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    • 제13권2호
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    • pp.181-186
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    • 1969
  • The concentration of Strontium-90 in liquid whole milk produced in Korea were measured during past four years. The samples of milk were purchased from dairies in Seoul. Strontium-90 was analysed radiochemically and the amount of stable calcium was also determined. Radioactivity of Yttrium-90 was counted in low background beta counter which has the background of 1.38 cpm. The concentrations of Strontium-90 in the milk are 25.1 PCi $^{90}Sr$/g.Ca in 1965, 26.8 PCi $^{90}Sr$/g. Ca in 1966, 13.7 PCi 90Sr/g.Ca in 1967 and 18.2 PCi $^{90}Sr$/g.Ca in 1968 in annual average. The concentrations of Strontium-90 in the milk of 1967 and of 1968 were decreased approximately compared with the values of 60% 1965 and 1966. From the results we can see that Strontium-90 concentrations in the milk vary roughly proportionally with the specific activity of fallout. Considering on the safety problems, the Strontium-90 levels in the milk produced in Korea were far below the maximum permissible level recommended by ICRP.

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o-Cresolphthaleoxon을 이용한 스트론튬의 전기화학적 분석 (Determination of Trace Strontium with o-Cresolphthaleoxon by Electroanalytical method)

  • 최원형;이진식;김도훈;김재수
    • 분석과학
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    • 제6권3호
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    • pp.247-254
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    • 1993
  • 스트론튬을 비롯한 알칼리 토금속의 전기화학적 분석의 적용은 수용액상에서 DME(Drop Mercury Electrod)에 대한 환원이 어렵기 때문에 그 연구가 많지 않다. 본 연구에서는 지금까지 UV-VIS 흡광광도법에서 스트론튬의 분석에 이용되어 온 o-Cresolphthaleoxon을 가지고 이들 사이의 착물형성에 따른 전자이동을 이용하여 전기화학적 분석에 적용시켰다. 이 때 지지전해질의 선택, Accumulation Potential 등 전기화학적 분석에 영향을 미치는 실험조건 등을 조사하여 정량범위를 결정짓고, 분석시 공존 이온의 영향을 조사하였다. UV-VIS 흡광광도법의 경우 $100{\mu}g/L$로 검출감도가 좋지 못하였으나, 전기화학적 방법을 이용할 경우 $5{\sim}30{\mu}g/L$ 범위까지의 정량이 가능하였다.

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Effect of the Sintering Temperature on Electrical Properties of Porous Barium-strontium Titanate Ceramics

  • Kim, Jun-Gyu;Sim, Jae-Hwang;Cho, Won-Seung
    • 한국세라믹학회지
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    • 제40권1호
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    • pp.5-10
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    • 2003
  • Porous barium-strontium titanate ceramics were fabricated by adding corn- or potato-starch (are referred to as starch). The effect of sintering temperature on the microstructure and electrical properties of the porous ceramics was investigated. The room-temperature electrical resistivity of the barium-strontium titanate ceramics decreased with sintering temperature. The porosity and pore size were decreased and the grain size was increased with increasing the sintering temperature. The porosity and grain size of the barium-strontium titanate ceramics with corn-starch sintered at 1300 and 1450$^{\circ}C$ were 28.5, 22.6% and 3.2, 6.2 $\mu\textrm{m}$, respectively. The average pore sizes of the barium-strontium titanate ceramics with corn-starch sintered at 1300, 1400 and 1450$^{\circ}C$ were 0.5, 0.3 and 0.2 $\mu\textrm{m}$, respectively. The decrease in the room-temperature resistivity with increasing sintering temperature is attributed mainly due to the increase of grain size and the decrease of the electrical barrier height of grain boundaries as well as the partial decrease of porosity.