Most recently, graphene-related composite-modified electrode surfaces are been widely employed to improve surface interactions and electron transfer kinetics. Hydrothermally prepared strontium pyro niobate (SPN) and reduced graphene oxide/ strontium pyro niobate (RGOSPN) nanostructures reveal excellent morphology. X-ray diffraction analysis of SPN and RGOSPN agree with standard data. Thermogravimetry–differential scanning calorimetry analyses show that RGOSPN has higher thermal stability than SPN. In addition, from the polarization–electric field (P–E) loop measurements, the estimated value of remnant polarization (Pr) and coercive electric field (Ec) of SPN are 0.039 μC cm−2 and − 2.90 kV cm−1 and that of RGOSPN nanocomposite are 0.0139 μC cm−2 and − 2.04 kV cm−1. Cyclic voltammetry measurements show that RGOSPN nanocomposite manifests the possibility of electrochemical reversibility beyond long cycles without change in performance. The redox cycle reveal that RGOSPN can be used as part of a composite electrode for hybrid capacitors dynamic conditions. Moreover, the specific capacitance of SPN and RGOSPN was calculated using galvanostatic charge–discharge (GCD) technique. The observed energy density of 9.1 W h kg−1 in RGOSPN is higher when compared with previous reported values.

Strontium lanthanum vanadate La1-xSrxVO3 (LSVO) is a promising anode material for electrochemical devices, especially for solid oxide fuel cells, thanks to its irregular electrical conductivity. However, the known synthesis methods are incapable of producing well-dispersed LSVO nanoparticles (NPs) with homogeneous size distribution, which partly impedes the applicability of the material. Thus, a new approach to synthesize LSVO NPs with such characteristics is of paramount importance. In the present work, we successfully prepare LSVO NPs with a high dispersion degree and homogeneous size distribution via a modified co-precipitation pathway, followed by hydrogen reduction at a temperature as low as 700 oC. The prepared LSVO NPs display uniform sizes in the range of 50 ~ 100 nm and do not contain any secondary phases, according to XRD analysis. The chemical mechanism of reactions that occur to form the LSVO is thoroughly highlighted. The work functions of NPs measured by the UPS analysis are in the 2.13 ~ 3.62 eV range, making the LSVO powders promising for use in thermionic devices. An explanation of the role of Sr substitution in work function values of LSVO is also proposed.

This study provides an assessment on a proposed method for separation of cesium, strontium, and barium using electrochemical reduction at a liquid bismuth cathode in LiCl-KCl eutectic salt, investigated via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS). CV studies were performed at temperatures of 723-823 K and concentrations of the target species up to 4.0wt%. Redox reactions occurring during potential sweeps were observed. Concentration of BaCl2 in the salt did not seem to influence the diffusivity in the studied concentration range up to 4.0wt%. The presence of strontium in the system affected the redox reaction of lithium; however, there were no distinguishable redox peaks that could be measured. Impedance spectra obtained from EIS methods were used to calculate the exchange current densities of the electroactive active redox couple at the bismuth cathode. Results show the rate-controlling step in deposition to be the mass transport of Cs+ ions from the bulk salt to the cathode surface layer. Results from SEM-EDS suggest that Cs-Bi and Sr-Bi intermetallics from LiCl-KCl salt are not thermodynamically favorable.

스트론튬(90Sr)과 니켈(59Ni)은 처분안전성평가에서 중요하게 다루는 핵종들이다. 지하에서 방사성핵종의 이동을 저지하기 위한 다양한 시도가 이루어지고 있는데, 처분시스템에서 용기와 부식반응으로 생기는 광물들 중에 핵종들과 반응성이 뛰어난 광물들이 존재하는 것이 알려졌다. 이들 중에서 철-황화합광물인 맥키나와이트(FeS)를 선정하여 스트론튬, 니켈과 수착 실험을 하였다. 심부지하에서 환원 알카리 환경을 고려하여, pH 8 ~ 12까지 조건에서 pH에 따른 수착영향을 살펴보았다. 실험결과, 스트론튬은 낮은 알카리영역에서 수착능이 저조하였지만, 니켈은 전 실험영역에서 높은 수착능을 보였다. 또, 두 핵종 모두 알카리 조건에서 pH가 증가할수록 수착량(Kd)이 증가하였는데, 이는 pH가 증가하면서 풍부해진 OH‐이온이 광 물표면에 수소나 양이온과 결합해 탈착하면서 광물표면에 전기음성도가 증가해 양이온인 스트론튬과 니켈을 전기적 인력으로 끌어당기기 때문으로 여겨진다.

Homogeneous liquid crystal (LC) alignment on hafnium strontium oxide (HfSrO) films prepared by sol-gel process via ion-beam (IB) bombardment was investigated. Uniform LC alignment was achieved on the IB-irradiated HfSrO films at IB intensity of 1.8 keV. We confirmed the effect of surface morphology on LC alignment using field-emission scanning electron microscope (FE-SEM). In addition, we observed electro-optical characteristics of the twisted-nematic (TN)-LC cells based on HfSrO films to verify the possibility of LC display (LCD) application.

전 세계적으로 원자력 발전소는 442기가 가동 중이며, 62기가 충원될 예정이다. 원자력 발전소의 증가에 따라 방사성 폐기물 유출에 대한 위험성도 증가하였다. 이러한 이유 때문 에, 방사성 폐기물의 처리는 인간, 동물, 식물을 포함하는 자 연 생태계를 보전하는 관점에서 중요하다. 또한, 방사성 폐 기물 유출은 그 지역뿐만 아니라 전 세계적으로 심각한 문 제를 야기한다. 본 연구는 입체 배양세포에 방사성 핵종원 소 (세슘, 스트론튬, 코발트)를 처리하였고 이에 대한 영향력 을 확인하였다. 입체 배양 구조체는 아가로오스 하이드로겔 을 이용하여 제작했으며 암세포 및 정상세포 (HeLa, HepG2, COS-7)를 사용하여 입체 배양을 실시 하였다. 입체 형태로 세포를 배양한 후 세슘, 스트론튬, 코발트 농도 변화에 따라 세포 생존능력을 분석하였다. 이때 입체 배양세포에서 생존 능력이 단층 배양세포 보다 최대 42% 우수한 것을 확인하였 다. 입체 배양구조체는 세포가 형태 및 생리학적으로 in vivo 환경인 조직과 비슷하게 배양을 가능하게 하였다. 따라서, 입체 배양구조체는 기존의 단층 배양 한계점인 in vivo 환경 에 적용시킬 수 없다는 한계를 극복하였다. 본 입체 배양 기 술이 중금속 독성평가 및 단시간 내에 다수의 물질 분석을 수행하는 고속 대량 스크리닝 기술에 활용될 것으로 기대한 다.

In this study, we investigated primary biocompatibility and osteogenic gene expression of porous granular BCP bone substitutes with or without strontium (Sr) doping. In vitro biocompatibility was investigated on fibroblasts like L929 cells and osteoblasts like MG-63 cells using a cell viability assay (MTT) and one cell morphological observation by SEM, respectively. MTT results showed a cell viability percent of L929 fibroblasts, which was higher in Sr-BCP granules (98-101%) than in the non-doped granules (92-96%, p< 0.05). Osteoblasts like MG-63 cells were also found to proliferate better on Sr-doped BCP granules (01-111%) than on the non-doped ones (92-99%, p< 0.05) using an MTT assay. As compared with pure BCP granules, SEM images of MG-63 cells grown on sample surfaces confirmed that cellular spreading, adhesion and proliferation were facilitated by Sr doping on BCP. Active filopodial growth of MG-63 cells was also observed on Sr-doped BCP granules. The cells on Sr-doped BCP granules were well attached and spread out. Gene expression of osteonectin, osteopontin and osteoprotegrin were also evaluated using reverse transcriptase polymerase chain reaction (RT-PCR), which showed that the mRNA phenotypes of these genes were well maintained and expressed in Sr-doped BCP granules. These results suggest that Sr doping in a porous BCP granule can potentially enhance the biocompatibility and bone ingrowth capability of BCP biomaterials.

본 연구는 효율적인 돼지 난자의 활성화를 통한 수핵란의 대량 확보를 위하여 ethanol, Ca-ionophore 및 strontium의 최적 농도 및 노출 시간을 규명하기 위하여 실시되었다. Ethanol은 10%에서 10분간 노출시켰을 때 난할율과 배발달 성적이 각각 51.4%와 45%로 다른 처리구에 비하여 유의적으로 높았으며 (P<0.05), Ca-ionophore는 에서 2분간 노출시켰을 때 난할율과 배발달 성적이 유의적으로 높았다. 또한 st

Sr2Ta2O7, a layered perovskite compound, has been reported to possess most excellent photocatalytic properties among the layered perovskite materials. Recently, we have demonstrated that Ba5Ta4O15 that was prepared under a mol ratio of Ba: Ta=1:1 has high photocatalytic performance as well as Sr2Ta2O7. In this study, the photocatalyst samples with a mol ratio of Sr: Ba: Ta = (1-x): x: 1 were prepared. The maximum photocatalytic performance was obtained for x= 0.2, which is three times as high as that of undoped Sr2Ta2O7.