جستجوی مقالات مرتبط با کلیدواژه "استرانسیوم" در نشریات گروه "علوم پایه"

Graphene-based nanomaterials are being investigated for their biocompatibility and bioactivity, as well as their ability to improve osteogenic differentiation. In this research, the base material, reduced graphene oxide (rGO) sheets, were decorated with hydroxyapatite and strontium (rGO / HAp-Sr) to induce osteogenic differentiation in adipose-derived mesenchymal stem cells. Different techniques were used to determine the properties of the nanocomposite such as diffraction analysis techniques (XRD) and transmission electron microscopy (to evaluate the size and morphology of HAp-Sr on rGO plates), FT-IR (to analyze the nanocomposite functional group), Raman spectroscopy (to investigate possible disorders in nanocomposite structure and number of layers), induced dual plasma emission spectroscopy (to assess atomic concentration of Ca and Sr), zeta potential(electrical potential of the nanocomposite) and MTT (nanocomposite cytotoxicity assessment) were used. The ossification potential of the synthesized nanocomposite was investigated and confirmed using the calcium deposition test in dipose-derived mesenchymal stem cells. According to the obtained results, osteogenic differentiation induction is possible using synthesized nanocomposites without the need for chemical inducers.

TEOS xerogel was investigated as adsorbent to removal strontium ion from aqueous solution in batch operations. Batch experiments were carried out as a function of pH, initial concentration, time, and temperature. Simple kinetic and thermodynamic models have been applied to the rate and isotherm sorption data and kinetic and thermodynamic parameters were determined. These studies were showed that the Langmuir isotherm model and pseudo-second-order kinetic model were fitted well with experimental data. The maximum capacity of the adsorbent for Sr(II) is 17 mg/g. The paper discusses the thermodynamic parameters of the adsorption (the Gibbs free energy, entropy, and enthalpy). Results demonstrate that the adsorption process was spontaneous and endothermic under natural conditions.

The original mineralogy of carbonate- evaporite series of Kangan and Dalan formations in central Persian Gulf area has been determined in this study. Uranium and strontium elemental concentrations were determined in the samples of two wells using inductively coupled plasma tool. The concentrations of these two elements show the same variations in the studied formations. Comparison of these elements with uranium wire line data showed the same trend. As both uranium and strontium preferentially enrich in aragonite other than calcite, they can be used for determination of the original mineralogy of carbonate deposits. The results showed that in the end-Permian time, there was an aragonite sea stage that was favorable of life for carbonate secreting organisms. After that, an equilibrium condition was dominated with simultaneous precipitation of aragonite and calcite. At the end-Permian time just below the Permian-Triassic boundary, there was an acidic condition that was hostile to life. Comparing this period with other sections withcomplete end-Permian record showed that there is a gap in these sediments. Using carbon- hydrogen- uranium and oxygen system, anoxic conditions determined at the later stage. These results show that combination of acidic and anoxic conditions made a serious problem for life at the end-Permian time in central Persian Gulf area at the time of deposition.

Yttrium-90 radioisotope as a daughter of Strontium-90 is one of the nuclear fission products and plays an important role in the treatment of malignant tumors in nuclear medicine. There are at least five methods for the separation of Y-90 from Sr-90 including: Liquid membrane separation, Precipitation solvent extraction ion exchange and solvent extraction combined with ion exchange method. In this work ion exchange chromatography was used by Dowex50Wx8 resin as a stationary phase and ammonium oxalate, EDTA and sodium Acetate solutions as mobile phases. Separation of yttrium and strontium was performed in the various simulation conditions and for determining the elements, ICP-AES technique was used. The activities of real samples were estimated with β-liquid scintillation counter. The various shielding parameters for designing different parts of generator were also considered in this work.