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The incorporation of bioactive ions into biomaterials has gained significant attention as a strategy to enhance bone tissue regeneration on the molecular level. However, little knowledge exists about the effects of the addition of these ions on the immune response and especially on the most important cellular regulators, the macrophages. Thus, this study aimed to investigate the in vitro cytocompatibility and in vivo regulation of bone remodeling and material-related immune responses of a biphasic bone substitute (BBS) coated with metal ions (Sr2+/Mg2+) and PLGA, using the pure BBS as control group. Initially, two cytocompatible modified material variants were identified according to the in vitro results obtained following the DIN EN ISO 10993-5 protocol. The surface structure and ion release of both materials were characterized using SEM-EDX and ICP-OES. The materials were then implanted into Wistar rats for 10, 30, and 90 days using a cranial defect model. Histopathological and histomorphometrical analyses were applied to evaluate material degradation, bone regeneration, osteoconductivity, and immune response. The findings revealed that in all study groups comparable new bone formation were found. However, during the early implantation period, the BBS_Sr2+ group exhibited significantly faster regeneration compared to the other two groups. Additionally, all materials induced comparable tissue and immune responses involving high numbers of both pro-inflammatory macrophages and multinucleated giant cells (MNGCs). In conclusion, this study delved into the repercussions of therapeutic ion doping on bone regeneration patterns and inflammatory responses, offering insights for the advancement of a new generation of biphasic calcium phosphate materials with potential clinical applicability.

Hydroxyapatite (HAp) coatings currently have limited therapeutic applications because they lack anti-infection, osteoinductivity, and poor mechanical characteristics. On the titanium substrate, electrochemical deposition (ECD) was used to construct the strontium (Sr)-featuring hydroxyapatite (HAp)/graphene oxides (GO)/linezolid (LZ) nanomaterial coated with antibacterial and drug delivery properties. The newly fabricated nanomaterials were confirmed by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis and morphological features were examined by scanning electron microscope (SEM) analysis. The results reveal multiple nucleation sites for SrHAp/GO/LZ composite coatings due to oxygen-comprising moieties on the 2D surface of GO. It was shown to be favorable for osteoblast proliferation and differentiation. The elastic modulus and hardness of LZ nanocomposite with SrHAp/GO/LZ coatings were increased by 67 % and 121 %, respectively. An initial 5 h burst of LZ release from the SrHAp/GO/LZ coating was followed by 14 h of gradual release, owing to LZ's physical and chemical adsorption. The SrHAp/GO/LZ coating effectively inhibited both S. epidermidis and S. aureus, and the inhibition lasted for three days, as demonstrated by the inhibition zone and colony count assays. When MG-63 cells are coated with SrHAp/GO/LZ composite coating, their adhesion, proliferation, and differentiation greatly improve when coated with pure titanium. A novel surface engineering nanomaterial for treating and preventing osteoporotic bone defects, SrHAp/GO/LZ, was shown to have high mechanical characteristics, superior antibacterial abilities, and osteoinductivity.

The increasing attention on the unique properties of oxyhydride materials motivates the exploration of their potential applications in optical fields, and the theoretical studies of their luminescence properties are still under progress. Here, we report the experimental and theoretical high-pressure photoluminescence (PL) studies on Eu-activated Sr3–xAxAlO4H (A = Ca and Ba; x = 0 and 1) oxyhydride materials. Under hydrostatic pressures from ambient pressure up to 6.41 GPa, the luminescence band in all the samples exhibits redshift with increasing pressure and the highest energy-shift rate of −101.85 cm−1/GPa was observed in Sr3AlO4H:Eu2+. The asymmetric bands were deconvoluted into two peaks corresponding to the two Eu sites with different coordination environments. Although the shift rates of Eu2+ centers in Sr3AlO4H are not remarkable as expected for the large compressibility of hydride ion ligands, their pressure-dependences in opposite directions were successfully reproduced by constrained density functional theory calculations using the advanced on-site Coulomb interaction parameter (U) determination method. The lower shift rate as seen in conventional oxide phosphors indicates that Eu-4f and 5d level positions are determined by the interaction with less compressive oxide ion ligands. Therefore, the high shift rate required for pressure sensing applications is expected in more hydrogen-rich oxyhydrides and related hydride compounds. [ABSTRACT FROM AUTHOR]

MnO2/MCM-41 composite was prepared by one-pot method to investigate its removal of Sr2+ from radioactive wastewater. The prepared composite were characterized by SEM，BET，FT-IR. The effects of parameters such as mass ratio，pH，adsorption time and competing ion effect of MnO2 and MCM-41 on the adsorption test were investigated. The results showed that the composite adsorbent could rapidly adsorb Sr2+ in water and reached the adsorption equilibrium in 120 min with the maximum adsorption capacity of 85.46 mg/g. The composite adsorbent had the highest adsorption capacity when the mass ratio of MnO2 and MCM-41 was 4∶1 ，and the composite adsorbent had high adsorption performance in the range of pH 4-9. In addition，the composite adsorbent maintained good adsorption capacity in the presence of Na+，K+，Mg2+ and Ca2+，and the inhibited adsorption capacity followed the order of Na+< K+< Mg2+< Ca2+. The adsorption kinetic data analysis of the pseudo-secondary model fit the adsorption data better than the pseudo-first-order model，indicating that chemisorption dominated the adsorption process. The novel MnO2/MCM-41 composite prepared for the removal of Sr2+ from radioactive wastewater had the advantages of rapid adsorption，high adsorption capacity，selectivity，and the ability to be prepared on a large scale，which made it promising to play an important role in the field of Sr2+ containing radioactive wastewater removal.

Mg97Zn1Y2 alloys with high ignition temperatures were developed by adding Sr. The addition of Sr resulted in the formation of a uniform and thin Y2O3 film. Mg–Zn–Y alloys containing at least 0.25 at.% Sr exhibited ignition temperatures of 1270–1320 K. As a result of EDS measurement, Sr was found to be concentrated in the Y2O3 film. In addition, a mixed film of MgO and SrO formed on the outer layer in the 1.5 at.% Sr-containing Mg97Zn1Y2 alloy. These findings suggest that the uniform and thin Y2O3 film that maintains high soundness at high temperatures was formed owing to valence control and the formation of a protective outer oxide film.

Strontium isotopes are used for provenience and mobility studies in archaeology, ecology, and forensic studies, and rely on accurate baseline maps that are used to compare and interpret human and animal strontium ratios. Here, we present a bioavailable 87Sr/86Sr map, also called an isoscape, for southern British Columbia derived from modern plant samples’ 87Sr/86Sr ratios. We sampled 67 medium root depth plants over a 900 km transect from the southern BC coast to inland BC to capture the natural 87Sr/86Sr ratios of plants along the four major geological belts in British Columbia. Non-parametric Kruskal–Wallis and pairwise Wilcox tests were used to examine whether the geological belts had statistically significant mean differences. It was found that the province could be effectively divided into east and west, with the Coastal–Intermontane and Omineca–Foreland regions having statistically different means from each other. 87Sr/86Sr ratios had statistically significant relationships with salt deposition, volcanic deposition, and mean age of the underlying lithology. Generally, 87Sr/86Sr ratios increased with distance from the coast as the atmospheric input of radiogenic strontium from marine-derived rainwater decreased and the input of radiogenic strontium isotopes from the underlying geology of the Rockies in the far east of the province increased.

Extensive studies have been performed on layered compounds, ranging from layered cuprates to van der Waals materials with critical issues of intergrowths and stacking faults. However, such structures have been studied less because of experimental difficulty. We present characteristic defect structures of intergrowths in the Ruddlesden–Popper Ca2.46Sr0.54Ti2O7, which is known to exhibit hybrid improper ferroelectricity. Transmission electron microscopy reveals that numerous intergrowths composed of 7 and 15 layers are introduced in the ferroelectric domains. Elemental maps demonstrate that Sr ions are selectively substituted into the perovskite layers of intergrowths. Density functional theory calculations support the site-selective substitution of Sr ions, favorably located in the intergrowths. The stabilization of the Ruddlesden–Popper phase and intergrowths via Sr substitution can be explained by the ionic-radius difference between Ca and Sr ions. The study reveals detailed defect structures originating from the layered perovskite structure of Ca2.46Sr0.54Ti2O7 and shows the usefulness of elemental mapping in probing the substitution effects in oxides. [ABSTRACT FROM AUTHOR]

Proton exchange membrane water electrolysis (PEMWE) is expected to be used in the large-scale green hydrogen production. Reducing the Ir content of the anode catalyst is desirable, as the availability of Ir is limited, thus increasing the cost of PEMWE. To reduce the Ir content, a perovskite-type Sr(Ti,Ir)O 3 is investigated. Characterization and activity studies in acid suggest that the composition realizing both high catalytic activity and low Ir concentration is SrTi 0.67 Ir 0.33 O 3. Prototype catalyst-coated membranes (CCMs) containing SrTi 0.67 Ir 0.33 O 3 anodes are prepared. Regardless of the small Ir loading of 0.17 mg Ir cm−2, high efficiencies of 86.4 % and 69.8 % are respectively observed at 1 and 2 A cm−2, and 60 °C. Long durability of 2660 h is demonstrated at 1 A cm−2 and 60 °C. The post analyses of the CCMs suggest that collapse of the perovskite structure and dissolution of the constituent elements of SrTi 0.67 Ir 0.33 O 3 are factors causing degradation. • Low-Ir-content Sr(Ti,Ir)O 3 is investigated for use as an anode of a PEMWE. • Optimal composition realizing high activity and low-Ir-use is SrTi 0.67 Ir 0.33 O 3. • Prototype CCM using Sr(Ti,Ir)O 3 realized high efficiency and long durability. • Collapse of crystal structure and element dissolution degrades CCM durability. [ABSTRACT FROM AUTHOR]

Background: Restocking by introducing hatchery-reared fish into wild habitats aids in the restoration of fishery aquatic ecosystems and reefs to increase the abundance of fish resources, restore the ecological balance of water bodies, and enhance ecosystem functioning. Accurately, rapidly, and effectively evaluating the success of restocking using chemical markers (e.g., strontium [Sr]) remains challenging for fisheries management. Consequently, for non-lethal fish sampling, hard tissues, such as fin rays, have received increasing attention as a target for marking method. However, data on the differences in marking different types of fin rays remain limited. Therefore, we exposed juvenile blunt snout bream individuals (Megalobrama amblycephala) to 0 (control group) or 800 mg/L of SrCl2·6H2O (marked group) for 5 days and transferred them into normal aerated water for post-immersion culture. We sampled their pectoral, dorsal, ventral, anal, and caudal fin rays. The Sr marks among the fin types were sampled at 0 and 20 days post-immersion and evaluated using an electron probe micro-analyzer (EPMA) for the five-day Sr/Ca ratios, along with line transect and Sr mapping analyses. Results: Sr marking signatures were observed in all fin types in the marked group, with a success rate of up to 100%. Although marking efficiency varied among the different fin ray types, the highest Sr/Ca ratios were most often detected in the dorsal fin. Cross-sectional Sr concentration maps of all fin rays sampled showed high-Sr domains in the marked group; in contrast, the entire cross-sections of the control group displayed low Sr contents, indicating successful marking efficiency. Conclusions: Fin ray Sr marking is a successful method for juvenile M. amblycephala, with the advantages of non-lethality and negligible sampling injuries, facilitating the rapid and effective evaluation of Sr marking in restocking M. amblycephala. [ABSTRACT FROM AUTHOR]

Low-voltage driven ceramic capacitor applications call for relaxor ferroelectric ceramics with superior dielectric energy storage capabilities. Here, the (Bi0.5Na0.5)0.65(Ba0.3Sr0.7)0.35(Ti0.98Ce0.02)O3 + x wt% Ba0.4Sr0.6TiO3 (BNBSTC + xBST, x = 0, 2, 4, 6, 8, 10) ceramics were prepared to systematically investigate the effect of BST content on the phase structure, microscopic morphology and dielectric energy storage properties. A single perovskite structure with a dense and homogenous microstructure is presented in all BNBSTC + xBST ceramics. A recoverable energy storage density Wrec = 1.39 J/cm3 with efficiency η = 81.5% is achieved only under a low electric field of 94 kV/cm in the optimal composition of x = 6, accompanied by an enhanced dielectric temperature stability meeting the requirement of wider working window. In addition to good frequency, anti-fatigue and temperature stability, the BNBSTC + 6BST ceramics exhibit tremendous potential for designing low-voltage driven energy storage ceramic capacitors. [ABSTRACT FROM AUTHOR]

Pulsed power and power electronics systems used in electric vehicles (EVs) demand high-speed charging and discharging capabilities, as well as a long lifespan for energy storage. To meet these requirements, ferroelectric dielectric capacitors are essential. We prepared lead-free ferroelectric ceramics with varying compositions of (1 − x)Ba0.7Sr0.3TiO3–(x)BiMg0.5Ti0.5O3 (BST–BMT) (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1) using a solid-state-reaction method. To analyze the crystallinity and structural parameters, we examined the X-ray diffraction (XRD) patterns using the pseudo-Voigt function in the FullProf software. Additionally, Raman spectrum analysis confirmed the presence of ceramic structural distortion caused by microstrain and doping. Microstructure images of the ceramic samples showed an increase in grain size from 1 to 2.4 μm and an improved distribution of grain sizes with increasing doping levels. We investigated the dielectric properties of the BST–BMT ceramic capacitors across a wide range of frequencies and temperatures. Interestingly, as the BMT content increased, the previously saturated ferroelectric (FE) curve for x = 0.01 gradually shifted towards a narrower relaxor ferroelectric (RFE) curve for x = 0.1. The most favorable effective energy storage density was observed with a BMT doping concentration of x = 0.04, which coincided with exceptionally high-energy efficiency (η ~ 91%) under a field strength of 50 kV/cm and a relatively high dielectric normalized energy storage density of 3.71 µJV−1 cm−2 due to structural modifications that causes relaxor ferroelectric behavior. More interestingly, the energy storage performance of 0.96BST–0.04BMT displays a fatigue free characteristic enduring through numerous switching cycles. We also calculated the optical bandgap (Eg) values from UV–Vis spectra and compared them with the increase in BMT concentration. The Eg value for all ceramics was approximately 3.2 eV, similar to the pure BST ceramic sample. Additionally, the resistive switching behavior demonstrated by our bulk ceramic capacitors is not commonly observed in other bulk ceramics. [ABSTRACT FROM AUTHOR]

Low-voltage driven ceramic capacitor applications call for relaxor ferroelectric ceramics with superior dielectric energy storage capabilities. Here, the (Bi0.5Na0.5)0.65(Ba0.3Sr0.7)0.35(Ti0.98Ce0.02)O3 + x wt% Ba0.4Sr0.6TiO3 (BNBSTC + xBST, x = 0, 2, 4, 6, 8, 10) ceramics were prepared to systematically investigate the effect of BST content on the phase structure, microscopic morphology and dielectric energy storage properties. A single perovskite structure with a dense and homogenous microstructure is presented in all BNBSTC + xBST ceramics. A recoverable energy storage density Wrec = 1.39 J/cm3 with efficiency η = 81.5% is achieved only under a low electric field of 94 kV/cm in the optimal composition of x = 6, accompanied by an enhanced dielectric temperature stability meeting the requirement of wider working window. In addition to good frequency, anti-fatigue and temperature stability, the BNBSTC + 6BST ceramics exhibit tremendous potential for designing low-voltage driven energy storage ceramic capacitors. [ABSTRACT FROM AUTHOR]

Pulsed power and power electronics systems used in electric vehicles (EVs) demand high-speed charging and discharging capabilities, as well as a long lifespan for energy storage. To meet these requirements, ferroelectric dielectric capacitors are essential. We prepared lead-free ferroelectric ceramics with varying compositions of (1 − x)Ba0.7Sr0.3TiO3–(x)BiMg0.5Ti0.5O3 (BST–BMT) (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1) using a solid-state-reaction method. To analyze the crystallinity and structural parameters, we examined the X-ray diffraction (XRD) patterns using the pseudo-Voigt function in the FullProf software. Additionally, Raman spectrum analysis confirmed the presence of ceramic structural distortion caused by microstrain and doping. Microstructure images of the ceramic samples showed an increase in grain size from 1 to 2.4 μm and an improved distribution of grain sizes with increasing doping levels. We investigated the dielectric properties of the BST–BMT ceramic capacitors across a wide range of frequencies and temperatures. Interestingly, as the BMT content increased, the previously saturated ferroelectric (FE) curve for x = 0.01 gradually shifted towards a narrower relaxor ferroelectric (RFE) curve for x = 0.1. The most favorable effective energy storage density was observed with a BMT doping concentration of x = 0.04, which coincided with exceptionally high-energy efficiency (η ~ 91%) under a field strength of 50 kV/cm and a relatively high dielectric normalized energy storage density of 3.71 µJV−1 cm−2 due to structural modifications that causes relaxor ferroelectric behavior. More interestingly, the energy storage performance of 0.96BST–0.04BMT displays a fatigue free characteristic enduring through numerous switching cycles. We also calculated the optical bandgap (Eg) values from UV–Vis spectra and compared them with the increase in BMT concentration. The Eg value for all ceramics was approximately 3.2 eV, similar to the pure BST ceramic sample. Additionally, the resistive switching behavior demonstrated by our bulk ceramic capacitors is not commonly observed in other bulk ceramics. [ABSTRACT FROM AUTHOR]

Multifunctional fiber mats are explored as potential bioactive matrices for the development of the next generation of guided bone regeneration membranes with tunable microstructure, strength and therapeutic activity. In the present study, polycaprolactone (PCL) nanofibers with different concentrations of ascorbic acid derivatives (ascorbyl palmitate) and strontium polyphosphate nanoparticles (Sr-polyP NPs) were fabricated. The obtained PCL mats scaffolds were assessed not only for microstructure structure features, including morphological observation, hydrophilicity and tensile strength, but also in vitro water uptake, biodegradation (under enzymatic and hydrolytic conditions), bioactivity using SBF, as well as ascorbic acid release study. The observed results showed that the mean fiber diameter of the PCL fibers (388 ± 340 nm) increased with the increase in the concentration of the ASP and Sr-polyP NPs. The addition of ascorbyl palmitate caused an increase in viscosity from 40.6 ± 2.5 to 66.6 ± 2.0 cP in the case of 20% AsP/PCL; however, it caused a decrease in conductivity from 7.3 ± 0.4 to 6.38 µs, while there was an obvious increase in the viscosity and conductivity by Sr-polyP Nps addition from 40.6 ± 2.5 cP in the case of PCL only to 88.3 ± 2.5 cP in the case of PA1/SP15. The contact angle decreases from 125.9 ± 2.5° in the case of PCL only to 112 ± 4 and 102 ± 2.4° in the case of 20% loaded ascorbyl palmitate-PCL mats and 15% Sr/PCL, respectively. Moreover, the assessment of the antioxidant activity of PCL fiber mats containing 10% and 20% ascorbyl palmitate demonstrated that the 20% ascorbyl palmitate-PCL fiber mats have a higher antioxidant effectiveness compared to the 10% mats. This could be attributed to the controlled release of ascorbic acid from PCL, which occurs after 7 days. However, the highest tensile strength was observed for 5% Sr-polyP NPs-loaded PCL/AsP mats at 1.52 ± 0.51 MPa. Further increase of Sr-polyP NPs content resulted in a clear decrease of tensile strength to 1.13 ± 0.13and 0.93 ± 0.71 for 10% and 20% ascorbyl palmitate-PCL mats, respectively. Importantly, the fabricated AsP and Sr-polyP NPs-loaded PCL fiber mats showed induction of calcium phosphate deposition in SBF and the ability to sustain release of ascorbic acid over a time period of 28 d, in addition to the enhancement in cell proliferation compared to PCL only suggesting their application as a favorable synthetic matrix to amplify guided bone regeneration process. [ABSTRACT FROM AUTHOR]

Periodontitis-induced alveolar bone defects necessitate the use of bone grafts for optimal therapeutic outcomes. Therefore, synthetic bone grafts exhibiting consistent properties, sufficient amounts, and multiple application forms have been extensively studied. Our previously designed Ca–Si–Mg cement has demonstrated benefits regarding cell proliferation, osteogenesis, and angiogenesis. Similarly, Sr exhibits osteogenic, anti-osteoclastogenic, and angiogenic properties by influencing several intracellular signaling pathways. In this study, we modified the previously established Ca–Si–Mg cement by incorporating Sr, which resulted in the formation of Mg–Sr-calcium silicate (CS) cement. Furthermore, we evaluated its biocompatibility and efficacy in promoting osteogenesis and angiogenesis. The results revealed that the setting time of the cement was extended with the individual incorporation of either Mg or Sr; notably, the setting time of M5S5 (integrating both Sr and Mg in equal proportions) was 2.7 min shorter than that of M5S0 (integrating only Mg). In addition, the presence of Sr enhanced the mechanical strength to an ultimate strength of 1.89 MPa and reduced the biodegradation rate of the Mg-doped CS cement from a weight loss of 13.9 %–11.5 %. Sr and Mg also demonstrated a synergistic effect on cell proliferation, with no observed cytotoxicity in human periodontal ligament cells (hPDLs). Osteogenic markers such as alkaline phosphate, bone sialoprotein, and osteocalcin were significantly expressed in hPDLs under the combined influence of Mg and Sr on osteogenic activity. Similarly, the angiogenesis-related proteins, vascular endothelial growth factor and angiopoietin-1 exhibited considerable enhancement, indicating the angiogenic capability of M5S5. In summary, our in vitro experiments confirmed that M5S5 is a potential candidate for osteogenic substitutes and alveolar bone regeneration, suggesting its potential applicability in clinical practice. [ABSTRACT FROM AUTHOR]

Measurements of modern bone and tooth enamel show that calcium stable isotopes (δ44Ca), zinc (δ66Zn), and strontium (δ88Sr) have great potential as ecological and dietary tracers for studies on fossil material. Despite the fact that these three elements can be recovered using sequential chromatographic extraction from a single aliquot, a multi-proxy study has not been attempted yet, which would allow a less destructive analysis of precious fossil material. The present study consists of analyzing δ44Ca, δ66Zn, δ88Sr, and 87Sr/86Sr values in fossil bone and tooth enamel of carnivore and herbivore mammals from the Camiac cave (Upper Pleistocene, Gironde, France). Our study aims at (1) developing a protocol for Ca, Zn, and Sr stable isotope analyses from a single fossil bone or enamel aliquot; (2) testing the respective preservation of biological isotopic signatures in bone and tooth enamel; and (3) comparing the patterning of the different isotopic systems in a fossil mammal community. In the present study, fossil enamel samples have not been leached, as it has been done so far for Zn isotope analyses, but fossil bone samples have been leached using diluted acetic acid or were left unleached. Using inclusive statistical analyses, we identify the effect of leaching on bone chemical compositions, and the concentration and isotope composition of Ca, Zn, and Sr in leached bone and unleached enamel show no sizeable diagenetic overprint. We report for the first time δ66Zn values in fossil bone. The results show that bone δ66Zn values mirror the pattern already observed in enamel, e.g., a significant trophic 66Zn depletion between herbivores and carnivores. Bone δ44Ca and δ88Sr values also mirror those in enamel, and the results highlight a clear distinction between ruminants and non-ruminants, the latter being 44Ca-enriched. The present study focuses on the importance of analyzing several isotopic systems in a single fossil bone or enamel aliquot and shows encouraging results for the preservation of biological isotopic signatures in fossil bone, despite the longstanding dread of a so-called associated pervasive diagenesis. The present study will therefore be useful to consider any precious fossil material with limited destructive sampling possibilities. [ABSTRACT FROM AUTHOR]

To elucidate the hydrochemical characteristics, controlling factors, sources and mechanisms of strontium ion enrichment in groundwater in the northwest plain of Shandong Province, China, 88 groundwater samples were collected, including 51 shallow pore groundwater samples, 29 deep pore groundwater samples and 8 karst groundwater samples. The hydrochemical characteristics of the different types of groundwater were quite different. The karst groundwater samples were all fresh water with a single hydrochemical type, either HCO3-Ca or HCO3-Ca·Mg. The deep pore groundwater samples were mainly brackish water, and the shallow pore groundwater samples were brackish water–salt water, which has complex hydrochemical types. The hydrochemical characteristics of all the types of groundwater were controlled by mineral dissolution and active positive cation exchange. In shallow pore groundwater, deep pore groundwater and karst groundwater, the dissolution of silicate, evaporite and carbonate minerals dominated the hydrogeochemical process. The strontium in groundwater was derived from the dissolution of minerals with strontium isomorphism. The average contents of strontium in shallow, deep and karst groundwater were 1.59 mg/L, 0.58 mg/L and 0.50 mg/L, respectively. The strontium in shallow pore groundwater was mainly derived from the enrichment of groundwater runoff, and its sources are abundant, with silicic rock being the main source. The deep pore groundwater mainly derived from the evaporative minerals containing strontium, and the karst water mainly derived from carbonate rock dissolution with similar characteristics. [ABSTRACT FROM AUTHOR]

Compact and robust optical clocks are significant in scientific research and engineering. Here, we present a physical system for a strontium atomic optical clock with dimensions of 465 mm × 588 mm × 415 mm and a weight of 66.6 kg. To date, this is one of the most compact physical systems ever reported. The application of the magnetic shielding box in this physical system allowed the effect of external magnetic field fluctuation on cold atoms to be negligible. The physical system passed rigorous environmental tests and remained operational. A wavelength meter integrated in this physical system could monitor the wavelengths of the incident laser, and it could automatically calibrate the wavelengths of all lasers using a microcomputer. This compact and robust physical system could be a hardware basis for demonstrating a portable optical clock or even a space optical clock. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N 2 O) is an environmentally damaging gas and alternative methods for its abatement are needed. In this work, we developed an electrochemical route using the mixed ionic electronic conductor Sr 2 Fe 1·5 Mo 0·5 O 6- δ (SFMO) as electrocatalyst for N 2 O reduction in the temperature range of 600–800 °C, at ambient pressure, for application in Solid Oxide Fuel Cells (SOFCs). The electrode mechanism, studied by electrochemical impedance spectroscopy (EIS), is discussed to involve a competition between both O 2 and N 2 O species, particularly at lower temperatures, where N 2 O thermal decomposition is lower. In terms of electrocatalytic properties, galvanostatic transients were used to assess N 2 O electroreduction on the SFMO electrode. The results showed that, after cathodic polarization, the N 2 O conversion increases. In particular, a highest Faradaic efficiency (| Λ|) of 3.94 was obtained at 600 °C. The reversibility of the mechanism was also assessed, and the results showed that the reaction rate returns to its open circuit value upon current interruption. This work indicates, therefore, that the electrochemical promotion of N 2 O reduction can be an attractive tool to be implemented for the reduction of this environmentally damaging gas in SOFC systems. • The viability of SFMO as electrocatalysts for N 2 O reduction is demonstrated. • The N 2 O electroreduction mechanism on the SFMO cathode is outlined. • Competition between O 2 electroreduction and N 2 O decomposition is suggested. [ABSTRACT FROM AUTHOR]

The table-like behavior of the magnetic entropy change is generally observed in rare-earth-based alloys (e.g. La(Fe,Si)13, Gd50Co45Fe5, Gd56Ni15Al27Zr2, Gd (1 − x − y) Co x Al y etc). Here, we report similar table-like behavior in a bulk perovskite Eu0.5Sr0.5MnO3–EuMnO3 composite system with a working temperature span of ∼80 K for a field change of ∼70 kOe. AC susceptibility and time-dependent DC magnetization relaxation measurements confirm the presence of interacting ferromagnetic clusters with a Vogel–Fulcher freezing temperature of T 0 ∼ 42.7 K. The Langevin function fittings of the isothermal magnetization curves show a non-monotonous variation of cluster size with temperature. We propose a model for the high-field dependency of the ferromagnetic cluster coupling in the composite system. This widens the transition temperature region of long-range order formation and hence gives rise to the table-like magnetocaloric effect in Eu0.5Sr0.5MnO3–EuMnO3 composite systems. [ABSTRACT FROM AUTHOR]

In this study, perovskite La0.8Sr0.2FeO3 nanocrystals were formed in heavy metal oxide glass under Al2O3 tailoring. The influence of formation of La0.8Sr0.2FeO3 to glass structure and magnetic behavior was studied through various techniques such as X-ray diffraction, Raman, X-ray photoelectron microscopy, electron paramagnetic resonance, and Mössbauer spectra. The 10-30 nm-orthogonal La0.8Sr0.2FeO3 nanocrystals were synthesized and well distributed in glass whose structure and coordination numbers of B2O3, Al2O3, and Bi2O3 were changed by the La0.8Sr0.2FeO3 crystallization. Aluminum abnormality effect was observed in 10%Al2O3 doped glass which showed highest transparency, smallest La0.8Sr0.2FeO3 size (10 nm) and least non-bridging oxygen defects. The glass with 10%Al2O3 exhibited enhanced electron paramagnetic resonance signal, highest (71%) tetrahedral FeO4 units and improved Mössbauer sextets intensity which is promising for photonics device applications. [ABSTRACT FROM AUTHOR]

The paper reports the results of U–Pb dating, Nd–Sr–Pb isotope systematics, and geochemical study of quartz diorites associated with ore-bearing (Cu–Pd–Au–Ag) gabbro of the Volkovsky massif, which is localized within the Urals Platinum Belt, at its eastern border with the Silurian–Devonian volcanogenic complexes of the Tagil megazone. The age of the quartz diorites according to U–Pb (TIMS) dating is 429 ± 9 Ma, MSWD = 0.009. Sr–Nd–Pb isotope characteristics (εNd(T) = +5.5...+6.7; (87Sr/86Sr)t = 0.70382–0.70392; 206Pb/204Pb = 18.38–18.57; 207Pb/204Pb = 15.56–15.58; 208Pb/204Pb = 38.14–38.30) indicate a juvenile source with a model age of 570–760 Ma. The obtained data fall within values typical of basalts of ensimatic island arcs. The geochemical features of the granitoids of the Volkovsky massif (low REE concentration, differentiated REE pattern (La/Yb = 8–14) with a weak positive Eu anomaly (Eu/Eu* = 0.9–1.4)) are consistent with the characteristics of melts obtained in experiments on hydrous melting of mafic rocks in equilibrium with amphibole–pyroxene residue. The anomalous concentration of strontium (more than 1000 ppm) in the quartz diorites is due to the high content of this element in a source. Such source could be the oldest rocks of the Urals Platinum Belt—olivine gabbro and metamorphic rocks of their surroundings. The identical ages of the quartz diorites of the Volkovsky massif and monzonitoids of the Kushvinsky massif allow us to consider these rocks as the result of the almost simultaneous mantle and crust melting at the final stage of the formation of the Tagil island-arc system. [ABSTRACT FROM AUTHOR]

Sr2+ ions in an aqueous solution were removed using Na-A zeolites synthesized from kaolin, a natural mineral. Na-A zeolites with high crystallinity were synthesized using NaOH/kaolin mass ratios of 0.6 (ZK06) and 0.9 (ZK09). The adsorption reached equilibrium within 120 min. The adsorption data obtained from experiments for Sr2+ using ZK06 and ZK09 were appropriately analyzed with pseudo-second-order kinetic and Langmuir isotherm models. Comparing the maximum adsorption capacities (qm) of ZK06 and ZK09 for Sr2+, the highest values were obtained at 1.90 and 2.42 mmol/g, respectively. Consequently, the Na-A zeolites synthesized from kaolin can be evaluated as adsorbents with high adsorption capacities for the removal of Sr2+, proportional to the degree of their crystallinity. [ABSTRACT FROM AUTHOR]

Titanium dental implants are one of the best replacements for the natural teeth. It can reduce early failures compared to other implant materials. During mastication, generally, implant loosening occurs between the bone and the implant surface. Therefore, to resolve this issue, surface modification of the implant surface was done which can provide better bonding between the implant and the bone. In this study, we designed five different types of surface texture on the implant and compared them with the solid non-textured implant. In addition to that, we used four different hybrid composite coating materials along with hydroxyapatite, for better osseointegration and bone formation. Thus, we modeled a bony structure like mandible using solid modeling technique. We considered average biting force of 250 N with different bone conditions. After the analysis, it has been observed that 'U' and 'V' shape textures exhibited the optimized textures for dental implant with coating combination of HA1.5TO1.5SR and HA3Sr for weak and very weak bone conditions. The coating for straight and dome shaped textures for strong and very strong bone conditions showed better results, whereas 'U' shaped and dome shaped textures showed better results for normal bone condition. [ABSTRACT FROM AUTHOR]

Apatite minerals can have various anions and cations in their crystal structure in addition to phosphate ion (PO₄³⁻) and calcium ion (Ca2+). The aim of this study is to investigate effects of the borate, fluoride and strontium ions on biomimetic nucleation of calcium phosphate. Nano-crystalline hydroxyapatite (H-Ap) was obtained from a supersaturated buffered solution containing 4.12 mM HPO 4 2- and 5.88 mM Ca2+ (H-Ap). Four additives were used in solid solution methods: (i) 0.588 mM F- (F-Ap), (ii) 5.88 mM Sr2+ (Sr-Ap), (iii) 4.12 mM BO 3 3- (BO3-Ap), and (iv) a surface pre-reacted glass ionomer (S-PRG) filler eluate that contained 0.17 mM Sr2+, 0.588 mM F-, 11.1 mM BO 3 3-- (SPRG-Ap). Apatite crystallization was investigated using a solid-state magic-angle spinning NMR spectroscopy and X-ray diffraction (XRD) with the Rietveld analysis. A 2D 1H–31P heteronuclear-correlation NMR showed F- ion incorporation in the apatite structure of the F-Ap and SPRG-Ap. The peaks on the 31P axis of the F-Ap, Sr-Ap, and BO 3 -Ap were different from that of the H-Ap, and the full width at half maximum increased in the following order: H-Ap∼F-Ap∼BO 3 -Ap< SPRG-Ap< Sr-Ap, suggesting the incorporation of the F-, Sr2+ and BO 3 3-. The incorporation of F and BO 3 was further confirmed by 19F and 11B NMR. The XRD revealed that Sr2+ was preferentially incorporated into the CaII site. The F-, Sr2+ and BO 3 3-ions might be involved in modifying the crystallization of apatite precipitation, producing a variety of apatite. S-PRG filler that release these ions may have an effect on remineralization, i.e., the reformation of apatite lost due to caries. • F-, Sr2+ and probably BO 3 3- from surface S-PRG filler are incorporated in hydroxyapatite crystal lattice. • Sr2+ incorporation is indicated by the increase in the axis lengths. • The ions from S-PRG filler are involved in modifying the crystallization of apatite precipitation. [ABSTRACT FROM AUTHOR]

The growth of epitaxial thin films from the Ruddlesden–Popper series of strontium iridates by magnetron sputtering is analyzed. It was found that, even using a non-stoichiometric target, the films formed under various conditions were consistently of the perovskite-like n = ∞ SrIrO3 phase, with no evidence of other RP series phases. A detailed inspection of the temperature–oxygen phase diagram underscored that kinetics mechanisms prevail over thermodynamics considerations. The analysis of the angular distribution of sputtered iridium and strontium species indicated clearly different spatial distribution patterns. Additionally, significant backsputtering was detected at elevated temperatures. Thus, it is assumed that the interplay between these two kinetic phenomena is at the origin of the preferential nucleation of the SrIrO3 phase. In addition, strategies for controlling cation stoichiometry off-axis have also been explored. Finally, the long-term stability of the films has been demonstrated. [ABSTRACT FROM AUTHOR]

Gas produced water is originated from formation associated water produced during oil and gas production operations, which is characterized by numerous types, high mineralization and complex pollution components. Through sampling, testing and analyzing gas produced water in the Eastern Sichuan area, it is found that the carboniferous formation is rich in mineral resources, such as strontium (up to 814 mg/L), bromine (up to 717 mg/L), which is much higher than the content in the brine of Qaidam Basin salt lakes or seawater. And currently, China's strontium ore and bromine are in a situation of high import demand and supply shortage. By clarifying the strontium and bromine recovery techniques and evaluating the preliminary economic feasibility of potential mining, it is found that there are significant prospects of development and utilization. This study aims to provide scientific basis for the extraction of strontium and bromine resources in gas produced water in the Eastern Sichuan area and to establish the foundation for better sustainable development and resource utilization of oil and gas fields. [ABSTRACT FROM AUTHOR]

The magnetic anisotropy of strontium ferrite (SF)/PA12 filament, a popular hard magnetic ferrimagnetic composites that is used for 3D-printing of permanent magnets, is studied by vibrating sample magnetometry. The studied filaments have a composition of SF/PA-12 thermoplastic composite with a 40% wt. ratio of SF. SF particles are non-spherical platelets with an average diameter of 1.3 um and a diameter to thickness ratio of 3. Filaments are produced by a twin-screw extruder and have a diameter of 1.5 mm. SEM images show that the SF particles are homogeneously distributed through the filament. VSM measurements on different parts of the filaments show that the outer part of the cylindrical filament has a higher anisotropy, and the core is mostly isotropic. This conclusion is consistent with computational work by others which suggest that particle alignment predominantly takes place near the walls of the extruder die where shear flow is maximum. Additional hysteresis curve measurement of the outer cylindrical part of the filament parallel to the r and ϕ directions indicates that the squareness of the hysteresis curve (S) is larger in the r-direction. This indicates that the outer surface of the filament has a strong easy axis in the r-direction. We conclude that the SF platelets line up parallel to the walls of the extrusion die. [ABSTRACT FROM AUTHOR]

2D titanium carbide (Ti3C2Tx, where Tx indicates the surface termination) MXene nanosheets are synthesized by etching the Ti3AlC2 MAX phase using two kinds of etchants: potassium hydroxide (KOH) base and hydrofluoric (HF) acid. This study aims to reduce the environmental side effects caused by the etchant in fabricating MXene nanosheets to extract strontium ions (Sr2+) from nuclear wastewater. Ti3C2Tx MXene synthesized using alkaline KOH etchant shows a 99% Sr2+ removal rate, which is much higher than that synthesized using the conventional HF etchant (82%). The enhanced Sr2+ removal rate associated with KOH etching is explained by unique surface termination, which offers more active adsorption sites for Sr2+ by the partial hydrolysis of TiC bonds on the surface of MXene nanosheets. [ABSTRACT FROM AUTHOR]

Nowadays, the design of porous bone scaffolds represents a crucial issue in orthopedical applications. In this article, the mechanical properties of a multi-component scaffold with different porosity percentages were investigated. Mori–Tanaka equations were used to estimate various properties of calcium phosphate (CaP) bone cement reinforced by strontium nitrate nanoparticles (NPs) based on porosity percentages in both cases; before and after samples placement in simulated body fluid (SBF) solution. With the support of these equations, the mechanical properties of bone cement material without porosity were estimated to be used in finite element analysis (FEA); so then to assess structural stability and stress distribution, the experimental compression tests on the scaffold were simulated with the ABAQUS engineering package. The mechanical properties observation indicates that the grain and particle size increased by nitrate addition to the bone cement. The approach in this manuscript allows quantifying the effect of porosity on mechanical properties of CaP cements reinforced by the strontium nitrate NPs, to be fabricated based on the patient's needs. [ABSTRACT FROM AUTHOR]

[Display omitted] Currently, novel technologies are highly prerequisite as an outstanding approach in the field of photocatalytic water splitting (PWS). Previous research has shown that copolymerization technology could improve the photocatalytic performance of pristine carbon nitride (CN) more efficiently. As this technology further allows the charge carrier recombination constraints, due to novel monomer-incorporated highly abundant surface-active sites of metals in polymeric carbon nitride-based heterojunction. However, in present study, a novel previously unexplored thiophenedicarboxaldehyde (TAL) conjugated, strontium-titanium (SrTiO 3) induced and CN based heterojunction, i.e., SrTiO 3 /CN-TAL 10.0 , was prepared for solar-driven hydrogen evolution reaction (HER). This heterojunction effectively enables the proficient isolation of photoinduced charge carriers and enhanced the charge transport over the surface junction, by enhancing the optical absorption range and average lifetime of photogenerated charges. The incorporation of TAL within the structure of CN via copolymerization highly increases the photocatalytic activity, as well as maintaining its photostability performance. The SrTiO 3 concentration and the proportion of TAL among CN can be precisely controlled to provide the optimal photocatalytic efficiency with a maximum HER of 285.9 µmol/h under visible light (λ = 420 nm). Based on these results, our optical analysis shows that coupling of SrTiO 3 and TAL monomer in the structure of CN considerably reduce the band gap of superior sample from (3.42 to 2.66 eV), thereby, signifying the outstanding photocatalytic performance of SrTiO 3 /CN-TAL 10.0. Thus, this study provide a new guideline in order to develop the multidimensional photocatalysts with proper functioning for sustainable energy conversion and production. [ABSTRACT FROM AUTHOR]

[Display omitted] Bioceramics have been extensively used to improve osteogenesis of polymers because of their excellent bone-forming capabilities. However, the inadequate interfacial bonding between ceramics and polymers compromises their mechanical properties. In this study, zeolitic imidazolate framework-8 (ZIF-8) was grown in situ on strontium carbonate (SrCO 3) to construct a core–shell SrCO 3 @ZIF-8, which was then added to poly- l -lactic acid (PLLA) to print a SrCO 3 @ZIF-8/PLLA composite scaffold using selective sintering technology. First, ZIF-8 characterized by its multiple organic ligands, forms a robust interface with PLLA. Second, SrCO 3 characterized by its negative zeta potential in solution, exhibits the ability to adsorb positively charged zinc ions. This, in turn, promotes the in situ growth of ZIF-8 on SrCO 3 , eventually achieving perfect bonding between the second phase and the PLLA matrix. Our findings indicated that the composite scaffold exhibited the highest compressive strength (21.93 MPa) and significantly promoted the osteogenic differentiation of mouse mesenchymal stem cells. Moreover, the in vivo results established that the SrCO 3 @ZIF-8/PLLA scaffold significantly accelerated bone regeneration efficiency in rat femur defects. The prepared scaffold, with its favorable mechanical properties and osteogenic activity, shows considerable promise for applications in bone repair. [ABSTRACT FROM AUTHOR]

The Pauzhetka geothermal field was surveyed to study the mineral deposits that were formed as thermal water was discharged from well separators. We studied the compositions, structure, and geochemical properties of these sediments along the flow and in vertical cross sections of manmade "sinters". It was found that, at the beginning of thermal water discharges, the sediments were composed of X-ray-amorphous mordenite–opal mixtures; later on, the sediments became wholly siliceous. The zeolite component of the mineral deposits determines their high sorption properties in relation to Au, Ag, Hg, As, Rb, Sr, Ba, Cs and other elements; the mordenite matrix receives sulfides of iron, silver, and copper. It is shown that the mineral deposits which were formed at the ground surface of the Pauzhetka geothermal field constitute an indicator of alkaline mineral-forming and ore-forming environment in the lower horizons of the Pauzhetka geothermal system. [ABSTRACT FROM AUTHOR]

A method for determining activity of 89Sr and 90Sr in a sample where 90Sr and 90Y are not in equilibrium is presented. The method consists of an experimental design and equations for accurately calculating activity of 89Sr and 90Sr based on 90Y β particle counts and the total counts of β particles emitted from 89Sr, 90Sr, and 90Y in a sample. The equations are derived based on chemical separation sequences, β particle counting sequences, and the Bateman equation. The presented method allows simultaneously obtaining the activity of 89Sr and 90Sr in a non-equilibrated 90Sr/90Y system without the need of Cerenkov counting. [ABSTRACT FROM AUTHOR]

Understanding the effect of glass network structure on the solubility properties of bioactive glasses is fundamental for designing new compositions with tailored biological functions and applications. This paper bridged the composition-structure-property relationship utilizing experimental measurements and molecular dynamics simulations. The Sr atom reorganized the network structures through a partial transformation of tetrahedral to trigonal boron units and the change of the ratio of bridged oxygen/non-bridged oxygen, which modified the glass structures at longer lengths scales, such as through changing the ring size distribution. Our results demonstrated that the evolution of solubility properties can be linked to the atomic structure change in short- and medium-range ordering. The structure-property relationship can be used to design and tune bioactive glass composition with specific properties. [Display omitted] [ABSTRACT FROM AUTHOR]

A Sr(II) complex [Sr(L)2 (H2O)4 ]n (1) was synthesized with 1,4,5,8-naphthalene tetracarboxylic acid (H4L1) and strontium chloride hexahydrate under solvothermal conditions. The structure was characterized by elemental analysis (EA), single crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), infrared spectroscopy (IR) and thermogravimetric analysis (TGA). The single crystal X-ray diffraction results indicate that H2L1 undergoes in-situ reaction to generate 1,3-dioxo-1H,3H-benzo[de]isomere-6,7-dicarboxylic acid (H2L). In complex 1, each Sr(II) atom is located in the geometric configuration of a square antiprism. The L- ligands connect Sr atoms to form a one-dimensional chain structure. 2D supramolecular structure is formed through hydrogen bonding and π ... π stacking interactions. The solid states luminescence behavior of complex 1 was explored. It is found that complex 1 produces a wide emission spectrum band (450-690 nm) at the excitation wavelength of 211 nm, and the maximum emission wavelength appears at 535 nm. Therefore, it can be seen that complex 1 is a potential green light material. [ABSTRACT FROM AUTHOR]

Sr2CrOsO6 has the highest magnetic transition temperature (725 K) among the double perovskite oxides. Ca2CrOsO6 was obtained by replacing Sr ions with smaller volume Ca ions, and the magnetic transition temperature was higher than room temperature. Further substitution of Cr ions by Mo ions with more delocalized d orbitals yielded Ca2MoOsO6. The electronic structures and magneto-optical Kerr effects of the double perovskite oxides Sr2CrOsO6, Ca2CrOsO6 and Ca2MoOsO6 have been systematically calculated by density functional theory. The electronic structures indicate that all three materials are semiconductors. The electronic structures of Sr2CrOsO6 and Ca2CrOsO6 are very similar, and the band gap of Ca2MoOsO6 is extremely small, only 0.10 eV. Observing the magneto-optical Kerr effect line, all three materials show significant magnetooptical Kerr effects in the range of infrared to visible spectrum. The maximum Kerr rotation angles of Sr2CrOsO6, Ca2CrOsO6 and Ca2MoOsO6 are 1.18°, 0.98° and 0.65°. The maximum Kerr rotation angle of the three materials is greater than 0.2°, which makes them to be ideal magneto-optical materials. The calculated results show that the inclusion of both 3d(4d) and 5d transition metal ions in the compound contributes to the significant magneto-optical Kerr effect. Analysis of the optical conductivity tensor shows that the peak of the magneto-optical Kerr line of three materials originates from the interband transition and is dominated by the imaginary part of the off-diagonal element of optical conductivity tensor. [ABSTRACT FROM AUTHOR]