Amounts Of Strontium Research Articles

Strontium substituted hydroxyapatites: Synthesis and determination of their structural properties, in vitro and in vivo performance.

The objective of this study is to present a detailed report related to the synthesis and characterization of strontium substituted hydroxyapatites. Based on this purpose, hydroxyapatite (HAp) bioceramics with different amounts of strontium (e.g., 0, 0.45, 0.90, 1.35, 1.80 and 2.25 at.%) were prepared using a sol-gel method. The effects of Sr substitution on the structural properties and biocompatibility of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques, in vitro and in vivo tests. All the samples composed of the nanoparticles ranging from 21 to 27 nm. The presence of Sr at low levels influenced the crystal size, crystallinity degree, lattice parameters and volume of the unit cell of the HAp. Both in vitro conditions and soaking period in simulated body fluid (SBF) significantly affected these properties. Especially, the (Ca+Sr)/P molar ratio gradually decreases with increasing soaking period in SBF. Animal experiments revealed the bone formation and osseointegration for all samples, and as compared with other groups, more reasonable, were observed for the sample with the lowest Sr content.

The influence of Sr content in calcium phosphate coatings.

In this study calcium phosphate coatings with different amounts of strontium (Sr) were prepared using a biomineralization method. The incorporation of Sr changed the composition and morphology of coatings from plate-like to sphere-like morphology. Dissolution testing indicated that the solubility of the coatings increased with increased Sr concentration. Evaluation of extracts (with Sr concentrations ranging from 0 to 2.37 μg/mL) from the HA, 0.06Sr, 0.6Sr, and 1.2Sr coatings during in vitro cell cultures showed that Sr incorporation into coatings significantly enhanced the ALP activity in comparison to cells treated with control and HA eluted media. These findings show that calcium phosphate coatings could promote osteogenic differentiation even in a low amount of strontium.

The Influence of Strontium on the Microstructure of Cast Magnesium Alloys Containing Aluminum and Calcium

Abstract The structure of Mg-9Al-2Ca-xSr alloys is composed of a-Mg grains and the Al2Ca and Al4 Sr phases in the interdendritic areas. These phases are formed as a result of eutectic reactions. Globular particles of the Al8Mn5 phase are observed within the interior of the grains. The addition of strontium to Mg-9Al-2Ca-0.4Mn alloys causes the formation of the Al4Sr phase and increase of its volume fraction with increasing strontium levels. Moreover, increase of the strontium amount causes a decrease of aluminum content in the a-Mg solid solution.

Calcined bone provides a reliable substrate for strontium isotope ratios as shown by an enrichment experiment.

Strontium isotopes ((87) Sr/(86) Sr) are used in archaeological and forensic science as markers of residence or mobility because they reflect the local geological substrate. Currently, tooth enamel is considered to be the most reliable tissue, but it rarely survives heating so that in cremations only calcined bone fragments survive. We set out to test the proposition that calcined bone might prove resistant to diagenesis, given its relatively high crystallinity, as the ability to measure in vivo (87) Sr/(86) Sr from calcined bone would greatly extend application to places and periods in which cremation was the dominant mortuary practice, or where unburned bone and enamel do not survive. Tooth enamel and calcined bone samples were exposed to a (87) Sr-spiked solution for up to 1 year. Samples were removed after various intervals, and attempts were made to remove the contamination using acetic acid washes and ultrasonication. (87) Sr/(86) Sr was measured before and after pre-treatment on a Nu Plasma multi-collector induced coupled plasma mass spectrometer using NBS987 as a standard. The strontium isotopic ratios of all samples immersed in the spiked solution were strongly modified showing that significant amounts of strontium had been adsorbed or incorporated. After pre-treatment the enamel samples still contained significant amounts of (87) Sr-enriched contamination while the calcined bone fragments did not. The results of the artificial enrichment experiment demonstrate that calcined bone is more resistant to post-mortem exchange than tooth enamel, and that in vivo strontium isotopic ratios are retained in calcined bone.

Portland clinker production with carbonatite waste and tire-derived fuel: crystallochemistry of minor and trace elements

This paper presents results on the composition of Portland clinkers produced with non-conventional raw-materials and fuels, focusing on the distribution of selected trace elements. Clinkers produced with three different fuel compositions were sampled in an industrial plant, where all other parameters were kept unchanged. The fuels have chemical fingerprints, which are sulfur for petroleum coke and zinc for TDF (tire-derived fuel). Presence of carbonatite in the raw materials is indicated by high amounts of strontium and phosphorous. Electron microprobe data was used to determine occupation of structural site of both C3S and C2S, and the distribution of trace elements among clinker phases. Phosphorous occurs in similar proportions in C3S and C2S; while considering its modal abundance, C3S is its main reservoir in the clinker. Sulfur is preferentially partitioned toward C2S compared to C3S. Strontium substitutes for Ca2+ mainly in C2S and in non-silicatic phases, compared to C3S.

Synthesis and dielectric properties of strontium substituted calcium niobate ceramics

Layered perovskite KCa2(1−x)Sr2xNb3O10 ceramic (x=0, 0.2, 0.4, 0.6, 0.8 and 1) materials were prepared by a conventional solid-state reaction method, and the effects of Sr substitution for Ca on the crystal structure and dielectric properties of the KCa2(1−x)Sr2xNb3O10 system were investigated. Also, potassium ions were exchanged with proton ions to obtain HCa2(1−x)Sr2xNb3O10. Then, X-ray diffraction, infra-red spectra, and energy dispersive detector analysis were carried out to verify immaculate substitution. Unlike alkali cations intercalated powder, the dielectric properties of 2Ca(1−x)SrxNb2O6–Ca2(1−x)Sr2xNb2O7 mixtures, which were obtained from HCa2(1−x)Sr2xNb3O10 by sintering, showed high dielectric permittivity with increasing amounts of strontium, and remained unaffected by frequency change from 1kHz to 1MHz. Its compositional dependence behavior was analyzed through Raman spectral analysis. X-ray diffraction, differential thermal analysis, and thermogravimetry observation revealed the phase transition on sintering of HCa2(1−x)Sr2xNb3O10.

Strontium content and collagen-I coating of Magnesium-Zirconia-Strontium implants influence osteogenesis and bone resorption.

Our objective was to study the role of Collagen type-I (Col-I) coating on Magnesium-Zirconia (Mg-Zr) alloys, containing different quantities of Strontium (Sr), in enhancing the in vitro bioactivity and in vivo bone-forming and mineralisation properties of the implants. MC3T3-E1 osteoblast cell line was used to analyse the in vitro properties of Col-I coated and uncoated alloys. Cell viability analysis was performed by MTT assay; cell attachment on alloy surfaces was studied by scanning electron microscopy (SEM); and gene profiling of bone-specific markers in cells plated on uncoated alloys was performed by Quantitative RT-PCR. In vivo studies were performed by implanting 2-mm-sized cylindrical pins of uncoated and coated alloys in male New Zealand white rabbits (n=33). Bone formation and mineralisation was studied by Dual Energy X-ray Absorptiometry (DXA) and histological analysis at one and three months post-implantation. Our results clearly showed that Sr content and Col-I coating of Mg-Zr-Sr alloys significantly improved their bone inducing activity in vitro and in vivo. Osteoblasts on coated alloys showed better viability and surface binding than those on uncoated alloys. Sr inclusion in the alloys enhanced their bone-specific gene expression. The in vivo activity of implants with higher Sr and Col-I coating was superior to uncoated and other coated alloys as they showed faster bone induction and higher mineral content in the newly formed bone. Our results indicate that bone-forming and mineralising activity of Mg-Zr-Sr implants can be significantly improved by controlling their Sr content and coating their surface with Col-I.

Biofortification of Soy (Glycine max (L.) Merr.) with Strontium Ions

Soy (Glycine max (L.) Merr.) is an annual plant cultivated worldwide mostly for food. Moreover, due to its pharmacological properties it is widely used in pharmacy for alleviating the symptoms of osteoporosis. The aim of the present study was to investigate the biofortification of soy treated with various concentrations of strontium. Soy was found to have a strong capacity to absorb Sr(2+) (bioconcentration factor higher than 1). A positive linear correlation (R(2) > 0.98) between the amount of strontium in the growth medium and its content in the plant was also observed. Moreover, at a concentration of 1.5 mM, strontium appeared to be nontoxic and even stimulated plant growth by approximately 19.4% and 22.6% of fresh weight for shoots and roots, respectively. Our research may be useful to obtain vegetable products or herbal preparations containing both phytoestrogens and strontium to prevent postmenopausal osteoporosis.

The study of the mineral content of leaves, stems and inflorescences of chaste-tree (vitex agnus-castus l.) And chinese chaste-tree (vitex cannabifolia sieb.)

Six macro- and thirteen microelements have been qualitatively and quantitatively determined by the emission spectroscopy method in leaves, stems and inflorescences of Vitex agnus-castus L. and Vitex cannabifolia Sieb. It has been found that silicon, iron, aluminium and zinc are mostly cumulated in V. agni-casti leaves, while V. cannabifoliae leaves obviously collect iron. It has been also determined that nickel is mostly cumulated in V. cannabifoliae inflorescences. The minor amounts of cadmium and mercury have been found in all samples under research, their concentration was lower than the maximum permissible concentration for the plant raw material and food products. Among technogenic elements zinc and mercury have been revealed, their amount is safe for human. Slight amounts of strontium have been found in all samples. In all samples the content of inorganic elements, except Cu, was below the maximum permissible concentration for food products and the plant raw material (if there are any). The copper content was higher than the maximum permissible concentration in all samples and was 1.0-2.3 mg/100 g with the maximum permissible concentration of 0.5 mg/100 g. Thus, further investigation of this mineral content in drugs based on the plants studied and development of the appropriate normative documents for the medicinal plants mineral content are of current interest. It has been also found that V. agni-casti leaves can selectively cumulate silicon, iron and zinc, and V. cannabifoliae leaves can cumulate iron. The content of the rest elements was approximately the same in all specimens. The total number of the minerals investigated was the highest in stems of both plants. The variation coefficient was in the range of 8.3-12.9%.

Ultrasonic-Assisted Dispersive Liquid Phase Microextration with Low-Volume Toxic Solvent for the Separation of Strontium and its Application for Strontium Isotope Determination

In this paper, a new and novel method of ultrasonic-assisted dispersive liquid phase microextration was applied for the pre-concentration of trace strontium ion in water samples, which was determined by inductively coupled plasma optical emission spectroscopy. In this pretreatment, acetonitrile was used as dispersive solvent, 1,1,2,2-tetrachloroethane as an extractant and dicyclohexyl-18-crown-6 as the chelating reagent. The factors influencing the extraction of the method were optimized. These factors were type and volume of extraction solvents, the type and volume of dispersive solvents, pH value and extraction time. The linear ranged from 40 to 2000 mu g/L with the limit of detection of 12 mu g/L. Under the optimum condition, the amount of strontium and the variation of strontium isotopic composition in four real water samples were investigated by the proposed method. The method can be applied to the determination of strontium and its isotopic composition in environmental samples.

X-Ray diffraction, electronic structure and magnetic characterization of nano and single crystals SrLaAlO4: Mn optical materials

• SrLaAlO 4 : Mn nano and single crystals were examined by XRD method to determine the crystal structure. • SEM/EDX imaging has been done. • XPS electronic structure was examined and discussed. • Experimental effective magnetic moment and the calculated one were compared. The XRD, XPS, SEM and magnetic characterization of the nano and single crystals SrLaAlO 4 doped with Mn were done. The sol–gel method was used to obtain the nanopowder and SEM imaging confirmed the sub-micron size of grains. The single crystals were grown by the Czochralski method. All compounds exhibit excess of strontium and deficiency of aluminium. The unit cell volumes increase with the amount of strontium. The electronic structures measured by XPS of the undoped yellowish single crystals and those nominally doped with 0.02 Mn (amber) and 0.1 Mn (olive) are very similar with comparable ratios of the main to the additional lines. It differs in the case of the nanocrystals, where the surface decomposition is observed. The magnetic measurements indicate the presence of the Mn 4+ ions and are in good agreement with the spectroscopic data.

Enhancing hydrogen production by dry reforming process with strontium promoter

Hydrogen is an ideal energy carrier and can play a very important role in the energy system. The present study investigated the enhancement of hydrogen production from catalytic dry reforming process. Two catalysts namely Ni/γ-Al2O3 and Co/γ-Al2O3 promoted with different amounts of strontium were used to explore selectivity and yield of hydrogen production. Spent and fresh catalysts were characterized using techniques such as BET, XRD, H2-TPR, CO2-TPD, TGA and O2-TPO. The catalyst activity and characterization results displayed stability improvement due to addition of Sr promoter. The least coke formations i.e. 3.8 wt% and 5.1 wt% were obtained using 0.75 wt% Sr doped in Ni/γ-Al2O3 and 0.5 wt% Sr doped in Co/γ-Al2O3 catalysts respectively. Time on stream tests of promoted catalysts for about six hours at 700 °C showed stable hydrogen selectivity. Moreover, the hydrogen selectivity was significantly improved by the addition of Sr in Ni and Co based catalysts. For instance the hydrogen selectivity increased from 45.9% to 47.8% for Ni/γ-Al2O3 and from 48% to 50.9% for Co/γ-Al2O3 catalyst by the addition of 0.75 wt% Sr in Ni/γ-Al2O3 and 0.5 wt% Sr in Co/γ-Al2O3 catalyst respectively.

Strontium Localization in Bone Tissue Studied by X-Ray Absorption Spectroscopy

Strontium has recently been introduced as a pharmacological agent for the treatment and prevention of osteoporosis. We determined the localization of strontium incorporated into bone matrix from dogs treated with Sr malonate by X-ray absorption spectroscopy. A new approach for analyzing the X-ray absorption spectra resulted in a compositional model and allowed the relative distribution of strontium in the different bone components to be estimated. Approximately 35-45% of the strontium present is incorporated into calcium hydroxyapatite (CaHA) by substitution of some of the calcium ions occupying highly ordered sites, and at least 30% is located at less ordered sites where only the first solvation shell is resolved, suggesting that strontium is surrounded by only oxygen atoms similar to Sr(2+) in solution. Strontium was furthermore shown to be absorbed in collagen in which it obtains a higher structural order than when present in serum but less order than when it is incorporated into CaHA. The total amount of strontium in the samples was determined by inductively coupled plasma mass spectrometry, and the amount of Sr was found to increase with increasing dose levels and treatment periods, whereas the relative distribution of strontium among the different components appears to be independent of treatment period and dose level.

Isolation of strontium pools and isotope ratios in modern human hair

The elements of human hair record specific information about an individual's health, diet, and surrounding environment. Strontium isotope ratios of human hair have attracted interest as they potentially record an individual's environment. Yet, separating the external environmental signals from the internal dietary indicators has remained a challenge. Here, we examined the effects of five different hair-cleaning methodologies to determine the extent that internal and external strontium signals can be isolated from human hair. In the first study of its kind, we employed an in-line strontium purification methodology and a multi-collector inductively coupled plasma mass spectrometer to obtain high-precision strontium isotope ratio of human hair and of leachates of the different washing treatments. We found that the different applications of an individual treatment removed a consistent amount of strontium from hair and that replicate analyses showed each treatment altered the strontium isotope ratios of hair consistently. A mass-balance approach was applied to demonstrate that strontium was quantitatively removed and was accounted for in either the treated hair or the leachate. We observed that strontium isotope ratio varied as a function of treatment aggressiveness so as to suggest that there was a fine-scale structuring of strontium within hair (transverse cross-sectional variations); these variations existed as differences in strontium concentrations and isotope ratios. As a result, the Sr isotope ratio of hair and hair leachates treated with the most aggressive cleaning methods reflected the isotope ratios of the interior and total exterior strontium signatures, respectively. The results of this study indicate that external environmental strontium signals can be distinguished from the internal signals and therefore permit the application of strontium isotope ratios of modern human hair for geospatial applications.

ToF-SIMS analysis of osteoblast-like cells and their mineralized extracellular matrix on strontium enriched bone cements

Commonly used implants for therapeutic approaches of non-systemically impaired bone do not sufficiently support the healing process of osteoporotic bone. Since strontium (II) has been proven as an effective anti-osteoporotic drug new types of strontium enriched calcium phosphate bone cements were developed. As osteoporosis is characterized by an imbalance of osteoblast and osteoclast activity the influence of this newly generated strontium enriched biomaterials on the cellular behavior of osteoblast-like cells was investigated by time of flight secondary ion mass spectrometry (ToF-SIMS). ToF-SIMS is used to analyze whether strontium is incorporated in the mineralized extracellular matrix (mECM) and whether there is strontium uptake by osteogenically differentiated human mesenchymal stem cells (hMSCs). Therefore hMSCs were cultured in osteogenic differentiation medium for 21 days on two different strontium enriched bone cements (S100 and A10) and for reference also on the pure calcium phosphate cement (CPC) and on a silicon wafer. The distribution of strontium in the osteoblast-like cells and within their mineralized extracellular matrix was analyzed. A higher intensity of the strontium signal could be detected in the region of the mECM, synthesized by cells cultivated on the Sr- substituted bone cement (S100) in comparison to the reference groups. The osteoblast-like cells used the released strontium from the biomaterial to synthesize their mECM. Apart from that a uniform strontium distribution was measured within all investigated cells. However, different amounts of strontium were found in cells cultured on different biomaterials and substrates. Compared to the negative controls the strontium content in the cells on the strontium enriched biomaterials was much higher. A higher concentration of strontium inside the cells means that more strontium can take part in signaling pathways. As strontium is known for its beneficial effects on osteoblasts by promoting osteoblastic cell replication and differentiation, and reducing apoptosis, the newly developed strontium enriched calcium phosphate cements are promising implant materials for osteoporotic bone.Electronic supplementary materialThe online version of this article (doi:10.1186/1559-4106-8-17) contains supplementary material, which is available to authorized users.

Metal oxide enhanced microfiltration for the selective removal of Co and Sr ions from nuclear laundry wastewater

The present study investigated the potential use of a hybridized adsorption/microfiltration system for the selective removal of hazardous cobalt and strontium ions from nuclear power plant laundry wastewater, which is essential for managing low-level radioactive wastes. A crystalline silicotitanate (CST) and four different iron oxides were fabricated and used as adsorbents, which had different crystal structures and adsorptive mechanisms, such as ion exchange and surface coordination. CST showed the greatest affinity for Co and Sr ions (e.g., the Freundlich isotherm constant, KF=23.5mg/g and 33.9mg/g, respectively, at pH 7) and its adsorption capacity was independent of solution pH (pH 5–9), whereas the iron oxides removed substantive amounts of Co ions at neutral and alkaline pH levels, but only marginal amounts of strontium. Background species (e.g., K+, Na+, Ca2+, and Mg2+) had no significant impact on the affinities of the adsorbents for Co and Sr ions. The selectivity coefficients of CST for both Co and Sr ions ranged from 3 to 130. CST and ferrihydrite adsorbents were successfully regenerated using NaCl and HCl solutions, respectively, and their post-regeneration adsorption capacities were unchanged without any sign of significant inactivation after multiple adsorption and regeneration cycles. The addition of adsorbents to the microfiltration system enhanced the membrane permeability (>30%), probably because the cobalt species were removed prior to precipitation at the membrane surface. Substantial and stable metal removals (>90% for both Co and Sr) were achieved during 50h of continuous system operations.

High Li ion conductivity in strontium doped Li7La3Zr2O12 garnet

Strontium doped lithium ion garnets Li 7 La 3 Zr 2 O 12 (LLZ) with 0.9 wt% to 8.4 wt% content of added Sr were synthesized via conventional solid-state reaction. X-ray diffraction patterns confirmed the cubic garnet structure of the sintered samples. A small amount of strontium was substituted to lanthanum in LLZ lattice. Further analysis showed SrCO 3 acted as a sintering aid for cubic LLZ ceramics and significantly increased the grain size of the sintered pellets. A conductivity of 2.10 × 10 − 4 S/cm at 297 K was obtained for the undoped LLZ. The total ionic conductivity reached a maximum of about 5 × 10 − 4 S/cm at 297 K with an activation energy of about 0.31 eV for 1.7 wt% Sr added LLZ sintered for 20–24 h in alumina crucible. • Pellets of strontium doped Li 7 La 3 Zr 2 O 12 with cubic garnet structure were processed through solid state reaction. • 1.7 wt% Sr added LLZ displayed high ionic conductivity up to 4.95 × 10 − 4 S/cm. • 1.7 wt% Sr added LLZ displayed a low activation energy of 0.31 eV. • Sr was substituted to La in the lattice and excess SrCO 3 acted as a sintering agent.

X-ray diffraction and Raman spectroscopy studies of temperature and composition induced phase transitions in Ba2−xSrxMWO6 (M = Ni, Co and 0 ⩽ x ⩽ 2) double perovskite oxides

X-ray diffraction and Raman spectroscopy studies of Sr doped double perovskites compound Ba2−xSrxMWO6 with (M=Ni, Co and 0⩽x⩽2) were investigated. The samples show a transition from cubic to tetragonal phase as a function of composition while increasing strontium amount; both Rietveld refinements and Raman studies showed that this transition occurs between x=1.2 and 1.4. Furthermore, increasing temperature for the tetragonal compositions (1.4⩽x⩽2), manifest the tetragonal to cubic phase transition. For this series, the transition from tetragonal (I4/m)/to cubic (Fm-3m) shows considerable changes in the composition and temperature dependence of the modes: all the Raman modes show a linear behavior when temperature is increased, then the slope change dramatically indicating the symmetry change from tetragonal to cubic. To better view this phase transition, the full width at half maximum (FWHM) temperature dependence of the most intense modes were studied; by this study, we have obtained a sensitive guide to the onset of the phase transition. A large increase of the FWHM with increasing temperature is observed for all modes in the spectrum, clear transitional effects were observed: the width behaves in a linear way as a function of temperature; when the temperature reached the transition temperature, a drop in the width of this mode was observed.

Influencing the crystallization of secondary alloy AlSi6Cu4 with strontium

This work deals with modification of aluminum alloy AlSi6Cu4 with strontium in graduated amounts. Submited article examines modification influence on the mechanical properties such as tensile strength (Rm), elongation (A5) and Brinell hardness (HBW). Article also includes analysis of alloy microstructure modified by strontium and analyzes the impact of strontium on the gas content of the melt. This work deals with finding the optimal amount of strontium to achieve changes in the shape of the coarse eutectic silicon plates to fine rounded AlSi6Cu4 alloy rods. Durin experiment was found, that optimum amount of the used modifier with respect to the mechanical properties of the surveyed sample is 2000 ppm AlSr5. But with the increasing amount of modifier in the alloy decreases fludity.

Evaluation of the proliferation and differentiation behaviors of mesenchymal stem cells with partially converted borate glass containing different amounts of strontium in vitro

The objective of this study was to examine the proliferation and differentiation behaviors of different compositions of strontium-containing (from 0-12 mol%) borate glasses with mesenchymal stem cells (MSCs). The Cell Counting Kit-8 (CCK-8) assay revealed that after three days of culturing, the 6Sr group had the highest cell growth rate. Analysis of cell morphology revealed that cells proliferated well near the particles of the samples in all the groups on day 3. On day 7, cells in the 6Sr group demonstrated a higher proliferation rate than other 4 groups under the microscope. When performing the Live-Dead staining experiment, the 6Sr group had the least number of dead cells. Total DNA qualification indicated that the 6Sr group had a statistically higher concentration compared with the remaining groups. It was found that on day 7, compared with the 0Sr group, the core binding factor α1 (Cbfa1) mRNA expression level was significantly higher in the 6Sr, 9Sr and 12Sr groups. On day 14, compared with the 0Sr group, the bone sialoprotein (BSP) mRNA level was significantly higher in the 6Sr group. Additionally, on day 21, the 6Sr and 9Sr groups demonstrated higher osteocalcin (OCN) mRNA expression levels compared with the 0Sr group. In the alkaline phosphatase (ALP) activity test, on day 21, the 6Sr group presented a higher activity than the 0Sr group. Further, the number of mineralized nodules per unit in MSCs was measured by Alizarin Red S staining. The results showed that the 6Sr and 9Sr groups had the greatest number of mineralized nodules. Therefore, it could be concluded that borate glasses containing strontium oxide of 0, 3, 6, 9 and 12 mol% demonstrate a significant level of proliferation when interacting with MSCs. The borate glass containing 6 mol% strontium oxide had the greatest level of proliferation when cultured with MSCs. The borate glass containing 6 and 9 mol% strontium oxide facilitated an improved bone formation ability compared with the remaining two compositions.