질산스트론튬 수용액 표면처리에 의한 수화시멘트 복합체의 휨강도 개선

성주경,조병휘 한국도로학회 2022 한국도로학회논문집 Vol.24 No.6

PURPOSES : The effects of strontium cations on the strength of hydrated cement composites as well as the morphology and chemical composition changes of cement hydrates due to strontium treatment are investigated in this study. Subsequently, the potential of a strontiumbased aqueous solution as a near-surface treatment method for hydrated cement composites is evaluated. METHODS : To supply strontium cations to a hydrated cement composite, a 30% strontium nitrate aqueous solution was used. Cement paste (w/c = 0.4) specimens were prepared and cured in the 30% strontium nitrate aqueous solution, which allows the strontium ions to penetrate into the specimen and treat the near-surface region. Compressive and flexural strength tests were performed on both specimens treated by the strontium ions and untreated specimens cured in deionized water, and the test results were compared. To investigate the changes in the morphology and chemical compositions of the cement hydrates due to the treatment, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analyses were performed. RESULTS : The results of the strength tests indicate that both the compressive and flexural strengths of the specimens cured in the 30% strontium nitrate aqueous solution improved significantly compared with the specimens cured in deionized water for the same duration. In particular, the strontium nitrate aqueous solution shows greater improvement in terms of the flexural strength compared with the compressive strength. The maximum penetration depth of strontium into the hydrated cement composite is 5 mm during the first 7 d of immersion and increases to 6.5 mm during the subsequent 14 d. The SEM results show that the microstructure of the hydrated cement composite is densified by the strontium nitrate aqueous solution treatment. The EDS results show that morphology and chemical compositions of the cement hydrates are altered. This implies that the strontium cations can be combined with C–S–H and C–S–A–H phases to form new types of hydrates. CONCLUSIONS : The experimentally results show that the strength of hydrated cement composites can be improved by modifying their near-surface regions via the strontium cation penetration technique. This implies that the strontium-based aqueous solution exhibits high potential for the maintenance and rehabilitation of concrete structures.

골막기원세포에서 strontium에 의한 조골세포 표현형의 활성

김신원,김욱규,박봉욱,하영술,조희영,김정환,김덕룡,김종렬,주현호,변준호,Kim, Shin-Won,Kim, Uk-Kyu,Park, Bong-Wook,Hah, Young-Sool,Cho, Hee-Young,Kim, Jung-Hwan,Kim, Deok-Ryong,Kim, Jong-Ryoul,Joo, Hyun-Ho,Byun, June-Ho 대한악안면성형재건외과학회 2010 Maxillofacial Plastic Reconstructive Surgery Vol.32 No.3

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.

Recovery of Strontium From Salt Solution After Chlorination

Sang Woon Kwon,Sang-Kwon Lee,Eun-Young Choi,Chang Hwa Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

Strontium-90 is a high heat-generating nuclide in spent nuclear fuel. The removal of the nuclide separation is indispensable to reduce the burden of storage and disposal of high-level radioactive waste. Korea Atomic Energy Research Institute has developed the molten salt immersion technique to separate the strontium by the chlorination of the strontium oxide in molten salt. It is needed to separate the salt for the recovery of strontium from the salt solution after the chlorination reaction. In this study, it was investigated on the recovery of the strontium from the salt. Vacuum distillation was used for the separation of strontium from the molten salt. The vapor pressures of the candidate salts were calculated by HSC chemistry and the apparent evaporation rates (AER) were measured at 830°C to evaluate the salts for strontium recovery. The candidate salts were LiCl, KCl, MgCl2, NaCl and CaCl2. The AERs of MgCl2 and NaCl were 1.9 and 1.3 g/cm2-h, respectively. Those two salts can be separated from the strontium compound even though the AER values are much lower than those of LiCl-KCl (~ 8 g/cm2-h). CaCl2 salt was rarely evaporated (AER < 0.03 g/cm2-h) and it is not suitable to use as a strontium recovery salt. Therefore, MgCl2, NaCl, LiCl and KCl can be regarded as candidates for a strontium recovery salt.

Strontium doping effects on the characteristics of solution-processed aluminum oxide dielectric layer and its application to low-voltage-operated indium-gallium-zinc-oxide thin-film transistors

Kim, Jaeyoung,Choi, Seungbeom,Kim, Minho,Ha, Tae-Jun,Kim, Yong-Hoon Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.16

<P><B>Abstract</B></P> <P>In this paper, we investigated the strontium doping effects on the electrical and physical characteristics of solution-processed aluminum oxide dielectric layer and its application to low-voltage-operated indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs). With an optimized doping concentration of strontium (5at%) in aluminum oxide (Al<SUB>2</SUB>O<SUB>3</SUB>), an oxide gate dielectric layer having a dielectric constant of ~7 and low leakage current characteristics (~4 × 10<SUP>−7</SUP> A/cm<SUP>2</SUP> at 3MV/cm) could be achieved by a solution process, which are comparably better than those of pristine Al<SUB>2</SUB>O<SUB>3</SUB> film. The enhanced dielectric properties from strontium doping can be attributed to the change in the physical properties of Al<SUB>2</SUB>O<SUB>3</SUB> film incorporated with strontium, providing charge relaxation of defect states in Al<SUB>2</SUB>O<SUB>3</SUB> film. Also, since the strontium is highly reactive with oxygen, the strontium substitution through a doping leads to more strongly bound structure in an Al<SUB>2</SUB>O<SUB>3</SUB> film without considerable lattice distortion. Using the strontium-doped aluminum oxide film as a gate dielectric layer, having a thickness less than 10nm, solution-processed IGZO TFTs operating at ≤ 1V were demonstrated showing a field-effect mobility of 1.74 ± 1.10cm<SUP>2</SUP>/Vs and an on-current level of ~10<SUP>−5</SUP> A.</P>

Sr-containing Hydroxyapatite for Bone Replacement

최정신,박홍채,윤석영 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.10

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. 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.

Adsorption characteristics of strontium onto K₂Ti₄O<SUB>9</SUB> and PP-g-AA nonwoven fabric

Tae hun Lee,Choon-Ki Na,Hyunju Park 대한환경공학회 2018 Environmental Engineering Research Vol.23 No.3

This study investigated the possibility of using potassium titanate oxide (K₂Ti₄O9) and acrylic acid-grafted polypropylene fabric (PP-g-AA) as adsorbents capable of removing strontium from aqueous solutions. K₂Ti₄O9 showed the highest rate of strontium removal in the weak alkaline range, while the PP-g-AA increased strontium removal in the neutral range. Moreover, the adsorption capacity of the K₂Ti₄O9 was not affected by the coexistence of K and Na ions, while the adsorption capacity decreased when Ca and Mg ions were present at the same concentration as that of strontium. When coexisted at the same concentration as strontium, Na, K, Ca, and Mg ions strongly reduced the adsorption capacity of the PP-g-AA. The results also indicated that the adsorption of strontium on K₂Ti₄O9 was consistent with both the Langmuir and Freundlich adsorption isotherms. In contrast, the adsorption of strontium on the PP-g-AA was more consistent with the Langmuir isotherm model. Moreover, the adsorption equilibrium time of K₂Ti₄O9 was generally 12 h, while that of the PP-g-AA was 5 h, indicating that the adsorption rates were consistent with the pseudo-second order kinetics model. K₂Ti₄O9 and the PP-g-AA could be regenerated by simple washing with 0.5 N HCl.

Carbonation of Strontium Chloride by Solid-Solid Reaction After Evaporation of LiCl-KCl Eutectic

Sang Woon Kwon,Eunsoo Lee,Byungsuk Park,Joon Bo Shim,Chang Hwa Lee 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

It has been investigated on the management of Strontium-90 in KAERI. It is needed to separate the solute from the salt solution for the recovery of strontium after the chlorination of the strontium oxide in molten salt. A vacuum distillation technology was used for the separation of strontium from the molten salt in our previous study. Strontium chloride was successfully carbonated by reactive distillation of SrCl2 – K2CO3 – LiCl – KCl system. In this study, it was tried to develop another route to recover strontium from the salt solution by a solid-solid reaction for avoiding the entrainment of product and the salt-K2CO3 reaction. Reactive distillation experiments were carried out for SrCl2 - K2CO3 – LiCl – KCl system. The carbonation temperature and pressure were 520°C and 0.8 bar. After the carbonation reaction, the temperature was elevated to 820°C to remove KCl from the reaction product. SrCO3 and KCl peaks were found in the XRD analysis of the residual product. It could be concluded that SrCl2 can be successfully carbonated after salt removal by the solid-solid reaction.

Determination of plutonium isotopes (^238,239,240Pu) and strontium (⁹⁰Sr) in seafood using alpha spectrometry and liquid scintillation spectrometry

Shin, C.,Choi, H.,Kwon, H.M.,Jo, H.J.,Kim, H.J.,Yoon, H.J.,Kim, D.S.,Kang, G.J. Elsevier Applied Science Publishers 2017 JOURNAL OF ENVIRONMENTAL RADIOACTIVITY Vol.177 No.-

<P>The present study was carried out to survey the levels of plutonium isotopes (Pu-238,Pu-239,Pu-240) and strontium (Sr-90) in domestic seafood in Korea. In current, regulatory authorities have analyzed radionuclides, such as Cs-134, Cs-137 and I-131, in domestic and imported food. However, people are concerned about contamination of other radionuclides, such as plutonium and strontium, in food. Furthermore, people who live in Korea have much concern about safety of seafood. Accordingly, in this study, we have investigated the activity concentrations of plutonium and strontium in seafood. For the analysis of plutonium isotopes and strontium, a rapid and reliable method developed from previous study was used. Applicability of the test method was verified by examining recovery, minimum detectable activity (MDA), analytical time, etc. Total 40 seafood samples were analyzed in 2014-2015. As a result, plutonium isotopes (Pu-238,Pu-239,Pu-240) and strontium (90Sr) were not detected or below detection limits in seafood. The detection limits of plutonium isotopes and strontium-90 were 0.01 and 1 Bq/kg, respectively. (C) 2017 Elsevier Ltd. All rights reserved.</P>

숙주의 발아과정 동안 폴리아민 생합성과 Diamine 산화효소에 대한 스트론티움 효과

김태완,권영업,윤승길,Kim, Tae-Wan,Kwon, Young-Up,Yun, Seung-Gil Korean Society of Soil Science and Fertilizer 2003 한국토양비료학회지 Vol.36 No.6

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. Objective of this experiment was to investigate the role of strontium in intracellular processes in mung bean (Vigna radiata L.). Diamine oxidase (DAO) induction by $Sr^{2+}$ appeared to a decrease in putrescine levels correspondently. DAO activities in the hypocotyls were in a range of 0.5 to $1.8unit{\cdot}mg^{-1}\;protein{\cdot}min^{-1}$. The decrease in Put levels in the cotyledons might be partly resulted from Put degradation by DAO. It was observed that the accumulation of spermidine and spermine by $Sr^{2+}$ was in the range of 1 mM to 10 mM. Spermidine levels were 2 to 3 fold higher than in the absence of strontium. The increase in polyamine levels was observed not only on a basis of g fresh weight but also a RNA basis. These results demonstrated that the inhibitory action of $Sr^{2+}$ may be closely related with polyamine metabolism as well as diamine oxidation and polyamine accumulation.

Two Step Process for the Recovery of Strontium From Salt Solution

Sang Woon Kwon,Eunsoo Lee,Byungsuk Park,Joon Bo Shim,Chang Hwa Lee 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

It has been investigated on the management of the nuclides in KAERI. Strontium-90 is a high heatgenerating nuclide in spent nuclear fuel. It is needed to separate the salt from the salt solution for the recovery of strontium after the chlorination of the strontium oxide in molten salt. A vacuum distillation technology was used for the separation of strontium from the molten salt. It was investigated on operating conditions of reactive distillation process for the recovery of the strontium from the salt solution. At a reduced pressure, considerable amount of the carbonation agents such as K2CO3 and Li2CO3 were reduced during heating in the distiller due to the thermal decomposition. Therefore, the two step process was proposed, which is composed of a reaction step at an atmospheric pressure and a salt distillation step at a reduced pressure. In the reaction step, the condition of low temperature and high pressure is suitable to suppress the decomposition of the carbonation agent. In the salt distillation step, reduced pressure is preferable at a suitable temperature depending on the evaporation rate of the salt.