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The construction of nuclear power plants necessitates careful consideration of the discharge and fixation of nuclear waste. Geopolymers are new cement-based materials (CBMs) with three-dimensional cage-like structures that enable effective nuclear waste fixation. In this work, the adsorption of radioactive caesium and strontium ions by sodium aluminosilicate hydrate (NASH) gel, the main component of geopolymers, was investigated using molecular dynamics simulations to obtain nanoscale insights into the ions' interactions with the gel. The formation of strong ion–oxygen bonds allowed both ions to be effectively adsorbed on the NASH surface, but the adsorption ratio of strontium ions (17.2%) was slightly lower than that of caesium ions (21.0%). Because strontium ions are divalent, they can form stronger electrostatic interactions with water molecules and chloride ions, which hinders their approach to the interface. For the same reason, the diffusion coefficient of strontium ions in solution is lower than that of caesium ions. These results provide new insights into the nuclear waste fixation capacity of NASH gel and guidance for the design of new CBMs for radioactive waste disposal. [ABSTRACT FROM AUTHOR]

This work is devoted to the preparation and characterization of silver sulfide (Ag2S) nanoparticles and used as an adsorbent for the separation and purification of Zr(IV), Y(III), and Sr(II) as a simulation mode for the purification of 89Zr from its parents (Y or Sr) and separation of 90Y from its parent Sr using batch and dynamic conditions. N2 adsorption-desorption isotherm for Ag2S is of type IV with a specific surface area (222 ± 0.4 m2/g). The surface is homogeneous texture in which connected channels of diameter 8.3 µm with embedded lamellar structures and the average nanoparticle sizes of 42 ± 3 nm. Ag2S nanoparticles sorbent material shows high selectivity for Zr(IV) from 0.01 M HCl with fast kinetics while 67.2% of Y(III) was removed at pH 4.5 and Sr(II) ions are nil. The adsorption process is exothermic and the intra-particle diffusion and film diffusion were involved in the adsorption mechanism. Also, the separation process was achieved using the column technique with a purity of 100% using different concentrations of HNO3 as eluent. Silver sulfide as an adsorbent material shows a promising potential with high sensitivity for separation and purification trace of Zr, Y, and Sr ions. [ABSTRACT FROM AUTHOR]

This study investigates the effects of strontium ions on enhancing the post-hardening strength and durability characteristics of hydrated cement composites, exploring their potential use as a rehabilitation method for aging concrete structures. A 30% strontium nitrate solution served as the source of strontium ions. Cement paste specimens with a water-to-cement ratio of 0.5, cured for 28 days, were submerged in the 30% strontium nitrate solution to facilitate strontium ion penetration. Compressive and flexural strength tests were conducted on the specimens and compared to those cured in deionized water. Moreover, the durability performance, including surface abrasion resistance, water sorptivity, and porosity, was examined. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffractometry (XRD) analyses were also carried out to investigate the microscopic morphology and chemical characteristics of the specimens. Results indicated that the strontium-treated specimens exhibited notable enhancements in both compressive and flexural strengths, especially in flexural strength. The specimens also demonstrated improved surface abrasion resistance, decreased water absorption, and a marked reduction in porosity. SEM analysis revealed a densified microstructure in the strontium-treated cement paste specimens, and EDS and XRD analyses showed changes in their morphology and chemical compositions and structures, indicating the formation of new types of hydrates. Accordingly, this study suggests that the strontium ion treatment method has significant potential for the maintenance and restoration of aging cementitious materials. [ABSTRACT FROM AUTHOR]

The treatment of critical‐sized bone defects has long been a major problem for surgeons. In this study, an intramedullary nail shaped three‐dimensional (3D)‐printed porous titanium implant that is capable of releasing strontium ions was developed through a simple and cost‐effective surface modification technique. The feasibility of this implant as a stand‐alone solution was evaluated using a rabbit's segmental diaphyseal as a defect model. The strontium‐loaded implant exhibited a favorable environment for cell adhesion, and mechanical properties that were commensurate with those of a rabbit's cortical bone. Radiographic, biomechanical, and histological analyses revealed a significantly higher amount of bone ingrowth and superior bone‐bonding strength in the strontium‐loaded implant when compared to an untreated porous titanium implant. Furthermore, one‐year histological observations revealed that the strontium‐loaded implant preserved the native‐like diaphyseal bone structure without failure. These findings suggest that strontium‐releasing 3D‐printed titanium implants have the clinical potential to induce the early and efficient repair of critical‐sized, load‐bearing bone defects. [ABSTRACT FROM AUTHOR]

In the present study, a novel composite coating consisting of magnesium oxide on halloysite nanotube (HNT-MgO) and doping of zinc and strontium ions in beta-tricalcium phosphate (Mn+-β-TCP). The monolayers of biomaterials were developed by coating HNT-MgO-Mn+-β-TCP on Ti–6Al–4V alloy using the electrophoretic method. The physicochemical properties such as functional groups, phase composition, surface morphology, cross-section, and chemical composition of biomaterials were characterized by adopted analytical techniques such as Fourier transform infrared spectroscopy, X-ray diffraction analysis, Scanning electron microscopy-Energy dispersive spectroscopy, Atomic force microscopy, High-resolution transmission electron microscopy. The cytotoxic activity of the prepared composite was tested against osteosarcoma MG-63 cells using MTT assay, and AO/EB staining the results clearly showed, that by increasing the composite concentration (5–100 μg/ml) the cell viability was reduced. Further, a cell adhesion study was performed by FE-SEM analysis, which showed that the MG-63 cells could inhibit and restrict the HNT-MgO-Mn+-β-TCP monolayer composite. The composite coating confirms the significant anticancer activity against osteosarcoma cells suggesting it is a promising candidate for further studies for practical orthopedic applications. [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]

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]

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]

In the Late Permian Zechstein Sea of Central Europe, up to 2000 m of evaporitic rocks were deposited in at least four consecutive cycles. The age of these evaporitic rocks could not yet be precisely determined, because they are virtually fossil-free and do not contain radiometrically datable volcanic layers. A chemostratigraphic age of the succession can be determined by comparing 87Sr/86Sr ratios of marine gypsum and anhydrite to the worldwide marine strontium evolution curve. Unfortunately, published 87Sr/86Sr data of the Zechstein succession are characterized by frequent outliers towards higher ratios, making an age assignment challenging. The scatter in 87Sr/86Sr ratios might be induced by different processes like the contribution of meteoric water to the brine, in-situ Rb decay, or post-depositional hydrothermal or diagenetic overprint. Here, we present a dataset of 26 new gypsum and anhydrite 87Sr/86Sr ratios from drill cores situated at "Alter Stolberg" in the northernmost Thuringian Basin. Evaporites of the Werra-, Staßfurt-, and Leine cycles were sampled. The close proximity of the drillings allows a very accurate assignment of the stratigraphic position of each sample, so that trends and outliers in 87Sr/86Sr ratios can easily be recognized. While the entire Werra Formation obviously revealed non-marine 87Sr/86Sr ratios, the lowermost 87Sr/86Sr ratios in the Staßfurt and Leine Formations can be assumed to represent marine ratios and allow estimating a chemostratigraphic age of 257‒254 Ma. The combination of the 87Sr/86Sr data with the mineral composition of the samples suggests a contribution of meteoric water, probably river water, to the Zechstein Sea as the main reason for the observed increase in 87Sr/86Sr ratios. Additional in-situ Rb decay, related to the riverine input of clay minerals, cannot be excluded. Modelling the amounts of sea water and meteoric water in the brine indicates that 83‒99% of meteoric water would be necessary to explain the highest 87Sr/86Sr ratios observed in the Werra Formation. [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]

BACKGROUND: Metal ions play an important role in the human body. With the progress of material synthesis and processing technology, a variety of metal ions that can be used in bone tissue engineering have been developed, such as magnesium (Mg2+), zinc (Zn2+), manganese (Mn2+), strontium (Sr2+), and copper (Cu2+). OBJECTIVE: To summarize the research progress and development direction of metal ions in bone tissue engineering. METHODS: The literature collected by CNKI, PubMed and WanFang databases from 2014 to 2022 was retrieved. The Chinese and English key words were “metal ions, bone tissue engineering, osteogenic activity, magnesium ions, zinc ions, manganese ions, strontium ions, copper ions, calcium ions, lithium ions, cobalt ions”. RESULTS AND CONCLUSION: Different metal ions will be released to varying degrees after the materials are implanted into the body, which can change the tissue microenvironment, thus improving the ability of materials to form blood vessels and bones. Compared with growth factors, metal ions are easier to control the release rate, have lower cost, and can also improve the mechanical properties of implant materials. The application of metal ions in bone tissue engineering is full of prospects. Although some metal ions can already be used to treat bone defects, the mechanism of action of many metal ions in the human body is not completely clear, and the application effect is a lack of clinical experiment verification. Further exploration is needed before clinical application. [ABSTRACT FROM AUTHOR]

Crystallographic investigations of eight homoleptic N,N′-dimethylpropyleneurea (dmpu) coordinated metal ions in the solid state, [Mg(dmpu)5]I2 (1), [Ca(dmpu)6]I2 (2), [Ca(dmpu)6](ClO4)2 (3), [Ca(dmpu)6](CF3SO3)2 (4), [Sr(dmpu)6](CF3SO3)2 (5), [Ba(dmpu)6](CF3SO3)2 (6), [Sc(dmpu)6]I3 (7), and [Pr(dmpu)6]I(I3)2 (8), and the complex [CoBr2(dmpu)2] (9) as well as the structures of the dmpu coordinated calcium, strontium, barium, scandium(III) and cobalt(II) ions and the cobalt(II) bromide complex in dmpu solution as determined by EXAFS are reported. The methyl groups in the dmpu molecule are close to the oxygen donor atom, causing steric restrictions, and making dmpu space-demanding at coordination to metal ions. The large volume required by the dmpu ligand at coordination contributes to crowdedness around the metal ion with often lower coordination numbers than for oxygen donor ligands without such steric restrictions. The crowdedness is seen in M⋯H distances equal to or close to the sum of the van der Waals radii. To counteract the space-demand at coordination, the dmpu molecule has an unusual ability to increase the M–O–C bond angle to facilitate as large coordination numbers as possible. M–O–C bond angles in the range of 125–170° are reported depending on the crowdedness caused by the coordination figure and the M–O bond distance. All reported structures of dmpu coordinated metal ions in both the solid state and dmpu solution are summarized to study the relationship between the M–O–C bond angle and the crowdedness around the metal ion. However, highly symmetric complexes seem to be favoured in the solid state due to favourable lattice energies. As a result, the dmpu coordinated lanthanoid(III) ions are octahedral in the solid state, while they, except lutetium, are seven-coordinate in the dmpu solution. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrogen oxidation reaction (NOR) offers an efficient and sustainable approach for conversion of widespread nitrogen (N2) into high‐value‐added nitrate (NO3−) under mild conditions, representing a promising alternative to the traditional approach that involves harsh Haber–Bosch and Ostwald oxidation processes. Unfortunately, due to the weak absorption/activation of N2 and the competitive oxygen evolution reaction, the kinetics of NOR process is extremely sluggish accompanied with low Faradaic efficiencies and NO3− yield rates. In this work, an oxygen‐vacancy‐enriched perovskite oxide with nonstoichiometric ratio of strontium and ruthenium (denoted as Sr0.9RuO3) was synthesized and explored as NOR electrocatalyst, which can exhibit a high Faradaic efficiency (38.6 %) with a high NO3− yield rate (17.9 μmol mg−1 h−1). The experimental results show that the amount of oxygen vacancies in Sr0.9RuO3 is greatly higher than that of SrRuO3, following the same trend as their NOR performance. Theoretical simulations unravel that the presence of oxygen vacancies in the Sr0.9RuO3 can render a decreased thermodynamic barrier toward the oxidation of *N2 to *N2OH at the rate‐determining step, leading to its enhanced NOR performance. [ABSTRACT FROM AUTHOR]

The aim of presented work was to synthesize geopolymers based on the metakaolin and to determine their adsorption capability in the process of cesium and strontium ions removal from the aqueous solutions. New approaches were proposed for obtaining the two samples of geopolymers in techologically suitable forms. Morphology of materials was investigated by means of X-ray fluorescence analysis (XRF), low-temperature nitrogen adsorption/desorption and scanning electron microscopic studies (SEM). As it follow from the data of XRF analysis, SiO2 and Al2O3 oxides found to be the major components in all samples investigated (~ 54–84 wt. %). As was determined by SEM studies, geopolymers consisted from nanosized particles, amorphous geopolymers binder and unreacted kaolin. It has been found that all samples involve the mesopores with approx. 1–40 nm radii. The greatest specific surface area calculated by the Brunauer-Emmet-Teller (BET) method had the sample obtained in the forms of spherical rods (SBET = 88 m² /g) that about 10 times greater than for initial kaolin taken for synthesis. The ion exchange capacities of materials in the process of Cu2+, Cs+ and Sr2+ removal from water solution were determined and it was found that these properties depends on the method of materials obtaining. Data showed that the geopolymers were more effective for removal the desired ions than initial kaolin. The greatest adsorption capacity towards cesium ions was received on the samples obtained in forms of pyramids and was reached 1.75 mmol/g. Experimental data were fitted into the Langmuir models and the main Langmuir constants were calculated. When analysing the data of investigation with comparing the literature data it was noted that geopolymers obtained can be used in adsorption technology for purification of water from radionuclides as technologically suitable sorbents. [ABSTRACT FROM AUTHOR]

Purifying aqueous solutions from radioactive contamination is an extremely relevant scientific topic today. Many organic and inorganic adsorbents can be recommended for the adsorption of heavy metal ions and radionuclides from aqueous solutions, or as carriers for storage and disposal of radioactive waste. Since radionuclides are sources of ionizing radiation, the radiation resistance of the adsorbent is an important characteristic. These studies aim to investigate the titanium silicate behavior and its adsorption properties' changes or their invariability in the field of intense β-radiation. Experimental techniques describe the synthesis of titanium silicate adsorbent by sol-gel method and the study of its adsorption capacity toward Ba2+ cations. The adsorption of Ba2+ cations was investigated under batch conditions with neutral pH of the solution. Initial and residual concentrations of Ba2+ cations were controlled by direct complexometric titration with Na-EDTA with Eriochrom Black T as an indicator. The study of the radiation resistance of the adsorbent to high-energy β-radiation was performed using a 90Sr-90Y β- - source “Sirius” installed in the Microtron Laboratory of the Uzhhorod National University. The distance from the source to the adsorbent samples was 20 cm. The flux of electrons at this distance was 108 el/cm2 ‧per second. The maximum energy of beta particles was 0.456 MeV for 90Sr and 2.28 MeV for 90Y. The maximum duration of exposure was 21 days, which corresponds to 1310 Gy. Raman spectroscopy of irradiated and nonirradiated samples of TiSi was performed using a Raman spectrometer XploRA PLUS installed in the Center for Collective Use of Scientific Equipment “Laboratory of Experimental and Applied Physics” of Uzhhorod National University. Results consist of kinetic of Ba2+ adsorption by titanium silicate and irradiated titanium silicate; isotherm of Ba2+ adsorption and Raman spectrum of nonirradiated, irradiated titanium silicate (TiSi) and TiSi after Ba2+ adsorption. Results showed that the value of the maximal adsorption was 140.5±9.2 mg/g (6.55 %) under a confidence level of 95 %. The adsorption values of barium ions by irradiated and non-irradiated titanium silicate coincide. This indicates that the adsorption properties of this adsorbent do not change under the influence of such a radiation dose. The Raman spectra of irradiated and non-irradiated titanium silicate coincide, while they do not identify free radicals, or ionic formations, which would indicate a change in the properties of the adsorbent under the influence of beta radiation. It can be argued that this adsorbent is radiation-resistant to beta-radioactivity, with a radiation dose of 1310 Gy. The main conclusion of the present work is that the studied sample of titanium silicate is radiation-resistant. It can withstand a radiation dose of 1310 Gy without changing its adsorption properties. Titanium silicate can be used for the adsorption of strontium radionuclides, it can be a carrier for the disposal of radioactive waste. [ABSTRACT FROM AUTHOR]

In this study, the sorption of Cs(I) and Sr(II) onto zirconium tin(IV) phosphate (ZrSnP) nanocomposite was achieved using the batch technique. ZrSnP has been prepared by the sol–gel technique and characterised using different analytical tools such as FT-IR, XRF, XRD, TGA & DTA, SEM, and TEM. The data obtained from this study showed that the sorption process was a fast equilibrium time (120 min). The distribution coefficients have sequence order; Cs(I) ˃ Sr(II). Reaction kinetic obeys the pseudo-second-order model. The capacity has the values 50.0, and 29.8 mg/g for Cs(I) and Sr(II), respectively. Sorption isotherms are more relevant to a Langmuir isotherm. Negative Gibbs energy values proved that the sorption process was spontaneous with high feasibility. Positive enthalpy values reveal that this process was endothermic. Positive entropy values showed that disorder between the solid–liquid phase increased during adsorption. The real sample study reveals that ZrSnP is a promising sorbent for the removal of 134Cs and 85Sr from low-level radioactive waste. The investigation proved that the ZrSnP is suitable for the removal of Cs(I) and Sr(II) from radioactive waste and could be considered potential material for purification of effluent polluted with these ions. [ABSTRACT FROM AUTHOR]

In this study, a novel organic–inorganic hybrid material IIGK@MnO2 (2-naphthalenemethyl-isoleucine-isoleucine-glycine-lysine@manganese dioxide) was designed as a novel adsorbent for the removal of strontium ions (Sr2+). The morphology and structure of IIGK@MnO2 were characterized using TEM, AFM, XRD, and XPS. The results indicate that the large specific surface area and abundant negative surface charges of IIGK@MnO2 make its surface rich in active adsorption sites for Sr2+ adsorption. As expected, IIGK@MnO2 exhibited excellent adsorbing performance for Sr2+. According to the adsorption results, the interaction between Sr2+ and IIGK@MnO2 can be fitted with the Langmuir isotherm and pseudo-second-order equation. Moreover, leaching and desorption experiments were conducted to assess the recycling capacity, demonstrating significant reusability of IIGK@MnO2. [ABSTRACT FROM AUTHOR]

The strontium–aluminium–hexaferrite was substituted with the divalent ions (Mg/Cu) with the chemical formula of Sr1–xMxAl2Fe10O19 (M = Mg, Cu; x = 0.1, 0.2), and all the samples were synthesized via sol–gel auto combustion method. The thermal studies disclosed endothermic and exothermic peaks and showed magnetic phase transition behaviour in the range of 350–450 °C. The particles are shaped in a hexagonal structure with space group P63/mmc and the crystallize size ranges between 44 and 53 nm. The field-emission scanning microscopy revealed the platelet-like morphology of the particles. The magnetic studies disclosed the fine range of magnetic saturation (40.87–49.76 emu/g) and coercivity values (4619–7647 Oe). The particles own single-domain arrangement and decent energy product value (0.32–0.38 MGOe), implying their potential application in permanent magnets. The lower dielectric constant values at high-frequency range suggest their potential employment in microwave applications. [ABSTRACT FROM AUTHOR]

The management of full-thickness skin injuries continues to pose significant challenges. Currently, there is a dearth of comprehensive dressings capable of integrating all stages of wound healing to spatiotemporally regulate biological processes following full-thickness skin injuries. In this study, we report the synthesis of a dandelion-shaped mesoporous strontium-gallium microparticle (GE@SrTPP) achieved through dopamine-mediated strontium ion biomineralization and self-assembly, followed by functionalization with gallium metal polyphenol networks. As a multifunctional wound dressing, GE@SrTPP can release bioactive ions in a spatiotemporal manner akin to dandelion seeds. During the early stages of wound healing, GE@SrTPP demonstrates rapid and effective hemostatic performance while also exhibiting antibacterial properties. In the inflammatory phase, GE@SrTPP promotes M2 polarization of macrophages, suppresses the expression of pro-inflammatory factors, and decreases oxidative stress in wounds. Subsequently, during the stages of proliferation and tissue remodeling, GE@SrTPP facilitates angiogenesis through the activation of the Hypoxia-inducible factor-1α/vascular endothelial growth factor (HIF-1α/VEGF) pathway. Analogous to the dispersion and rooting of dandelion seeds, the root-like new blood vessels supply essential nutrients for wound healing. Ultimately, in a rat chronic wound model, GE@SrTPP achieved successful full-thickness wound repair. In summary, these dandelion-shaped GE@SrTPP microparticles demonstrate comprehensive regulatory effects in managing full-thickness wounds, making them highly promising materials for clinical applications. [ABSTRACT FROM AUTHOR]

In this study, the batch technique was used for the sorption of Sr(II) and Cs(I) onto silica loaded with Aspergillus brasiliensis (AB@S). The precipitation technique was used to synthesize the AB@S bio-sorbent, which was then evaluated using several analytical instruments such as XRD, FT-IR, and SEM. The results of this investigation revealed that the sorption process had a short equilibrium time (40 min). The distribution coefficient values have a sequence order Sr(II) ˃ Cs(I). AB@S sorbent has saturation capacity for Sr(II) and Cs(I) 72.2 and 26.1 mg g−1, respectively. The reaction kinetics follow the pseudo-second-order model with capacity values of 5.01 and 3.53 mg g−1 for Sr(II) and Cs(I), respectively. Applicability of Langmuir isotherms has capacity values of 66.3 and 23.38 mg g−1 for Sr(II) and Cs(I), respectively. Thermodynamics data are endothermic and spontaneous. The AB@S is a promising bio-sorbent for the removal of 85Sr and 134Cs from simulated radioactive waste (SRW). The investigation proved that the AB@S is suitable to adsorb Sr(II) and Cs(I) from aqueous solutions and could be considered potential material for the purification of effluent contaminated with these ions. [ABSTRACT FROM AUTHOR]

The sorption behavior of traces Sr(II) toward β-Ca3(PO4)2 (TCP) depending on the concentration of the cation, pH, and concentrations of humic acids (HA) in the solution was studied. Thermodynamic analysis of the solubility of TCP (1) was performed taking into account the formation of Ca(OH)2 (CH, 2), Ca(H2PO4)2 (MCPA, 3), CaHPO4·2H2O (DCPD, 4), Ca5(PO4)3OH (hydroxyapatite, OHAp, 5), and Ca2P2O7 (DCPP, 6). It was shown that, depending on the pH of the solution, the main equilibrium phases with the solution are phases 4 and 5. X-ray diffraction analysis, Raman spectroscopy, and 31P NMR data of the phase (1) samples after contact with a solution of 0.01 M NaNO3 for about 10 days showed the presence of only the phase 1. The solubility of 1 regarding the concentration of Ca2+, PO43– ions and the stoichiometric ratio (Ca/P) in solutions, depending on pH, correspond to the presence of surface phases 4 or 5. The model of surface complexation in the Henry region adequately describes the mechanism of Sr(II) sorption by the surface phase 5 on TCP particles in the form of the SrHPO40 complex. The formation of the HA complex of Sr(II) in solution does not affect distribution coefficient Kd(Sr) in the range of HA concentrations of 0–150 mg/L due to the competitive effect of hydrogen phosphate ions on strontium complexes. [ABSTRACT FROM AUTHOR]

Largemouth bass Micropterus salmoides, a popular warm water sport fish, is routinely stocked in reservoirs throughout the USA to augment wild populations. Evaluating if these supplementations are successful requires distinguishing hatchery-sourced fish from their wild counterparts. From 2011 to 2019, over 467 000 largemouth bass fingerlings were stocked from multiple hatchery sources into a large southwestern reservoir (Elephant Butte Reservoir, New Mexico, USA) to supplement the sport fish population. To identify hatchery-sourced largemouth bass, we measured strontium isotope ratios (87Sr/86Sr) and determined ages using otoliths and dorsal spines. Otolith analysis of 169 fish classified 92.9% (n = 159) to the reservoir with few fish of hatchery origin (2 from Arkansas, 1.2%, and 1 from Montana, 0.6%). While stocking over 467 000 fingerlings across 8 years appears to reflect negligible stocking success, it is likely that low and variable stocking densities (average 3.0, range 0.29–7.77 fish·ha−1) contributed to the low stocking success in Elephant Butte Reservoir. Dorsal fin spines did not yield accurate age reconstructions and their 87Sr/86Sr values were affected by matrix interferences preventing source assignments. [ABSTRACT FROM AUTHOR]

The development of efficient and reusable Sr2+ adsorbent materials holds great significance for nuclear energy development and environmental protection. In order to address the low crown ether content in crown ether-based solid-phase adsorbents, this study employed condensation polymerization using di(aminobenzo)-18-crown-6 as monomers to prepare polymer materials and porous membranes. The adsorption kinetics, adsorption isotherm, and recyclability of the crown ether-based polymer were comprehensively investigated for Sr2+ adsorption. The results showed that the adsorption behavior of the polymer towards Sr2+ followed a pseudo-first-order kinetic model and Langmuir adsorption model, with a maximum adsorption capacity of 4.6 mg/g. Furthermore, even after five cycles, the adsorption performance of the polymer material for Sr2+ showed no significant decline. This study provides a new perspective for the development of long-lasting and highly efficient Sr2+ adsorbent materials. [ABSTRACT FROM AUTHOR]

The interaction of an aqueous solution of strontium nitrate with magnesium-doped potassium titanate nanotubes synthesized by coprecipitation followed by hydrothermal treatment is studied. It is found that after 2 h of exposure in the solution at room temperature, the composition with the replacement of 10 at % titanium by magnesium showed the greatest sorption capacity. The results obtained show the promise of using magnesium-doped potassium titanate nanotubes as adsorbents of strontium ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

Strontium (Sr) substituted wollastonite bioceramics were prepared by a modified sol-gel technique using bio-wastes such as eggshell as calcium oxide source and rice husk as silica source. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) were used to perform structural analysis. Bioactivity was examined by testing the apatite mineralization ability in vitro by immersing the ceramic pellets in simulated body fluid (SBF) for various time periods. Degradation assay was performed in Tris buffer solutions by following the protocol in ISO 10993-14 standard. Cytocompatibility and cell proliferation were analyzed at different concentrations using osteoblast like MG 63 cells by MTT assay. The results show that the addition of Sr increases the density and mechanical properties of wollastonite but decreases with SrO above 2.5 mol.%. Pure and Sr containing wollastonite possessed excellent apatite formation ability with continuous degradation under physiological conditions. The results of cell culture studies revealed that all prepared ceramics were non-toxic to osteoblast-like cells at different doses (0–1000 μg/mL), and wollastonite ceramics containing Sr also enhanced cell proliferation. [ABSTRACT FROM AUTHOR]

In the chlor-alkali industry, the thorough purification of calcium (Ca2+), magnesium (Mg2+), and strontium ions (Sr2+) presents a considerable challenge. In this context, we developed novel amino carboxylic acid fibers in this study by using laboratory-synthesized polyacrylonitrile-polyethyleneimine amino fibers as the matrix. The amino carboxylation process was achieved by introducing chloroacetic acid under mild alkaline and heating conditions, resulting in the desired amino carboxylic acid fibers (PAN-C-Na). Adsorption experiments demonstrated that the PAN-C-Na fibers reached adsorption equilibrium within 30 s. Additionally, they effectively adsorbed Ca2+ and Mg2+ ions at ultralow concentrations (<0.02 mg/L), exhibiting outstanding adsorption capacities of 0.40 and 0.36 mmol/g, respectively, and exceeding 50% of their saturation adsorption capacities. Moreover, compared to amino-phosphonic acid fibers, which are another type of calcium-magnesium adsorptive fibers, the PAN-C-Na fibers exhibited twice the selectivity for Sr2+ adsorption and proved effective in eliminating residual Sr2+ in brine. These findings highlight the potential of PAN-C-Na fibers as a promising material for the thorough purification of Ca2+, Mg2+, and Sr2+ ions in the chlor-alkali industry. [ABSTRACT FROM AUTHOR]

Co 0.5 Ni 0.5-x Sr x Fe 2 O 4 powders with x values of 0.1, 0.2, 0.3, 0.4 and 0.5 were quickly produced using the Solution Combustion Synthesis (S.C.S.) method. The effects of strontium (Sr) concentrations on the structure, microstructure, and magnetic properties were investigated using a variety of characterization methods. The SC technique produced single-phase spinel ferrites with a space group of Fd-3m (JCPDS data: 01-074-5694) directly and did not require any additional heat treatment throughout the manufacturing process. The lattice parameter increased due to the addition of the Sr ions, but the redistribution of the various cations resulted in a drop in the fraction of the Fe3+ cations found in the (A) sites. The average crystallite size reduced from 23 to 19 nm. Scanning Electron Microscopy (S.E.M.) displays well-shaped spherical grains in the nanoscale region, but larger grains with agglomeration were discovered with Sr doping of spinel ferrite nanoparticles. Room temperature Mössbauer spectra have a structure typical for superparamagnetic nanoparticles. To determine the distributions of iron ions at the A- and B- sites, the low-temperature measurements of Mössbauer spectra were performed at 15K, where the effect of relaxation on the structure of Mössbauer spectra is negotiable, the concentration of iron ions in A- and B-site were determined. It has been established that the substitution of Nickel ions for Strontium ions leads to the growth of F e A 3 + / F e B 3 + ratio from 0.75 to 0.89. In this study, we show the effect of Sr doping on the structure, morphology and magnetic properties Co–Ni ferrite nanoparticles, which are suitable for a wide variety of applications because of their adaptability. [ABSTRACT FROM AUTHOR]

In the present study, an Iranian natural zeolite (Sabzevar region) was evaluated as a natural adsorbent for the elimination and immobilization of strontium ions from an aqueous solution. For improving the adsorption efficiency of strontium ion, the zeolite surface was modified by the Schiff base ligand of bis (2-hydroxybenzaldehyde)1,2-diaminoethane (H2L). The natural zeolite and zeolite/H2L were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray fluorescence (XRF), BET and scanning electron microscope (SEM). Analysis of the natural zeolite showed that the zeolite is from the type of clinoptilolite and has a crystalline structure with the specific surface area 29.74 m2/g. The results showed that strontium adsorption onto modified zeolite increases compared to unmodified zeolite from 64.5% to 97.2% (at pH = 6). The effective parameters pH, adsorbent dosage, initial concentration of strontium ions, contact time, temperature, and interfering ions, were studied and optimized. The maximum adsorption efficiency was confirmed by modified zeolite and found to be 97.5% after 60 min of equilibrium time at pH 6, 0.05g as adsorbent dosage, and at 25 °C. Adsorption of strontium was confirmed by Langmuir model with maximum adsorption capacity of 10.31 mg/g. Kinetic studies showed that the adsorption of strontium ions on the adsorbent follows pseudo-second-order (PSO) model. Also, the thermodynamics of the adsorption process indicated that the adsorption of strontium on zeolite/H2L is an endothermic and spontaneous process, and the adsorption mechanism is a combination of physical and chemical adsorption. Finally, to manage the secondary waste generated from the adsorption process, strontium ions were immobilized in a zeolite structure. The results showed that the stabilization is well done with the thermal preparation process. After thermal treatment at 25–900 °C, modified zeolite satisfactorily retains strontium during back-exchange tests with NaCl solution. According to the results, the amount of strontium released from the adsorbent phase decreases from 52.6 to 1.6% with increasing heat treatment temperature. [ABSTRACT FROM AUTHOR]

Carbon-coated ZrO2/Mn-Mg-Zn ferrites nanostructures (CZ-FN) have been prepared as a new inorganic sorbent to remove Cs (I) and Sr (II) from a waste stream. Adsorption of Cs (I) and Sr (II) has been implemented considering different noteworthy parameters, for example, shaking time and the optimum time achieved high adsorption capacity of both ions [103 and 41 mg/g for Sr (II) and Cs (I)] was found 30 min. Also, the impact of pH values was studied; the best pH value for the adsorption process is pH 6. The adsorption saturation capacity of CZ-FN is 420.22 and 250.45 mg/g for strontium and cesium, respectively. The solubility percentage of CZ-FN was calculated utilizing diverse molarities from HNO3, HCl, and NaOH as eluents, the obtained data reveals an increase in the solubility percentage with more increase in the molarity of the eluents. The elevation in the solubility percentage follows the following order; HNO3 < HCl < NaOH. The kinetic studies were applied using the nanolinear form of different kinetic models; it was found that the adsorption process obeys the nonlinear pseudo-second-order. According to equilibrium studies, the Langmuir model has been more accurate than the Freundlich model for adsorption in the case of binary systems. The values of Di for the strontium and cesium are 10−10 m2/s, which displays the chemisorption nature of this process. The greatest values of the desorption process for the strontium and cesium are 96.87% and 94.43 by 0.3 M of HNO3. This indicated that the carbon-coated ZrO2/Mn-Mg-Zn ferrites could be regenerated and recycled to remove strontium and cesium ions from waste streams. [ABSTRACT FROM AUTHOR]

Green synthesized cellulose nanocrystals (CNCs) was prepared using Neurospora intermedia, characterized, and used to remove Strontium ions (Sr2+) from an aqueous solution with high efficiency. The characterization of CNCs was performed using a UV-Vis Spectrophotometer, Dynamic Light Scattering (DLS), Zeta Potential (ZP), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) mapping, EDX elemental analysis and BET surface analyzer. In this study, Response Surface Methodology (RSM) based on Box-Behnken Design (BBD) was successfully applied for the first time to optimize the dynamic adsorption conditions for the maximum removal of Sr2+ ions from aqueous solutions using CNCs as adsorbent. The effects of parameters, such as initial concentration of Sr2+ (50–500 ppm), adsorbent dosage (0.05–0.2 g/50ml), and contact time (15–120 min.) on removal efficiency were investigated. A mathematical model was studied to predict the removal performance. The significance and adequacy of the model were surveyed using the analysis of variance (ANOVA). The results showed that the second-order polynomial model is suitable for the prediction removal of Sr2+ with regression coefficient (R2 = 97.41%). The highest sorption capacity value of Sr2+ was obtained (281.89 mg/g) at the adsorbent dosage of 0.05 g/50 ml, contact time of 120 min., and the pollutant (Sr2+) concentration of 275 ppm. [ABSTRACT FROM AUTHOR]

Barium strontium titanate (BST) Ba1−xSrxTiO3 nanopowders have been successfully synthesized using the sol-gel route. This systematic study examines the effects of increasing strontium ions on the structural, morphological, and optical properties of the BaSrTiO3 compound. The x-ray diffraction (XRD) results revealed that the polycrystalline barium strontium titanate (BST) phase was formed at greater than 700°C. The samples crystallize in pure perovskite and change from tetragonal to pseudo-cubic or cubic when Sr+2 ions increase. In addition, the effect of Sr+2 ion replacement on the crystal structure and optical characteristics of Ba1−xSrxTiO3 particles (with x ranging from 0.2 to 0.6) was studied. The rise in Sr+2 from x = (0.2 to 0.6) reduced particle sizes from 91.39, nm 288.89 nm, 144.88 nm, 86.42 nm, and 46 nm revealed by field emission scanning electron microscopy. With the increase in Sr+2 ions, the density, lattice parameter, particle size and cell volume are reduced. The percentage of porosity increased as the concentration of Sr+2 ions increased. Spectrophotometer readings indicated that the optical gap energy changed with Sr+2 ion concentration x. The optical gap energy changed toward low energy and fell from 3.6 eV to 3.2 eV when the ion concentration of Sr+2 rose from 0.2 to 0.6. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) cauliflower-shaped Strontium (Sr)-doped SnO2 nanoparticles were synthesised at ambient temperature through a simple co-precipitation technique. The 3D cauliflower-shaped 7 wt-% Sr-doped SnO2 nanoparticles increase light harvesting features and also promote electron transport across grain boundaries. 3D cauliflower-shaped Sr-doped SnO2 nanoparticles offer low charge transfer resistance, which is validated by the electrochemical impedance spectroscopy spectrum. XRD studies of SnO2 and Sr-doped SnO2 have revealed a tetragonal structure, and PL spectra corroborate the greater charge splitting. This study may be the first ever report on the 3D microstructure of cauliflower-shaped 7 wt-% Sr-doped SnO2 nanoparticles that demonstrated higher photocatalytic activity under visible-light for MB dye solution. [ABSTRACT FROM AUTHOR]

Here, we have reported a simple and one-step hydrothermal method for preparing a highly uniform sodium zirconosilicate mesoporous sorbent supported with vanadium oxide nanoparticles (VO2). The results showed the formation of NPs with a surface area of 73.21 m2/g and with a particle size ranged from 67 to 80 nm. Furthermore, the proposed fabricated composite has been used to significantly remove the cesium and strontium ions from the aqueous solution by a batch method. The phase and structural characteristics of the VO2/zirconosilicate nanocomposites were well studied by using XRD, SEM, HRTEM, and nitrogen adsorption techniques. The results showed that the cesium and strontium ions were efficiently adsorbed by mesoporous VO2/zirconosilicate ion exchanger at a natural and wide pH ranges. Various kinetic and isotherms models have been developed to highlight the adsorption process of cesium and strontium ions. The fabricated zeolitic materials exhibited an adsorption capacity of 30.5 and 22.2 mg g−1 for Cs(I) and Sr(II), respectively. The collected data showed that the synthesized VO2/zirconosilicate has the maximum potential to properly remove Cs(I) and Sr(II) from the aqueous media. A microporous VO2/zirconosilicate nanocomposite adsorbent has been designed for efficient removal of cesium and strontium from contaminated samples. The synthesized nanocomposite indicated a highly ability to remove Cs(I) and Sr(II) ions in ultra-dilute solutions. [ABSTRACT FROM AUTHOR]

M-type strontium ferrites Sr1-xLnxFe12-xMxO19 (Ln: Sm; M: Mn; x = 0, 0.03, 0.06, 0.09, 0.12) doped with equivalent Sm-Mn ions were synthesized via the sol-gel method. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electric microscopy (SEM) and vibrating sample magnetometer (VSM). The samples with x from 0.00 to 0.12 were confirmed to the single-phase M-type strontium ferrite, and the impurity phases Fe2O3 and SmFeO3 were detected when the content of dopants x ≥ 0.09. When x = 0.09, the saturation magnetization (Ms) and the remanent magnetization (Mr) of strontium ferrites Sr1-xSmxFe12-xMnxO19 reached to the maximum values of 37.19 emu/g and 22.48 emu/g, respectively. When x = 0.06, the coercive force (Hc) of strontium ferrites Sr1-xSmxFe12-xMnxO19 reached to the maximum values of 6224 Oe. Acid-treatment reduces the magnetic properties of the Sr1-xSmxFe12-xMmxO19 (x = 0.03). Compared to 950 °C preparation, preparation at 1200 °C decreases its magnetic properties and the Hc drop is very significant. [ABSTRACT FROM AUTHOR]

The non-surgical treatments are being required to reconstruct damaged tissue, prioritizing our body's natural healing process. Thus, the use of bioactive materials such as bioactive glass has been studied to support the repair and restoration of hard and soft tissue. Thus, in this work Bioglass 45S5 was developed, adding 1 and 2%mol of SrO or MgO and the physical and biological properties were evaluated. The addition of MgO and SrO at the studied concentrations promoted the slight increase in non-bridging oxygens number, observed through the temperature shift in phase transitions to lower values compared to Bioglass 45S5. The insertion of the ions also showed a positive effect on Saos-2 cell viability, decreasing the cytotoxic of Bioglass 45S5. Besides the Ca/P ratio on the pellets surface demonstrating no evidence of higher reactivity between Bioglass 45S5 and Bioglass with Sr and Mg, micrographs show that at 24 h the Ca/P rich layer is denser than in Bioglass 45S5 after the contact with simulated body fluid. The samples with Sr and Mg show a higher antibacterial effect compared to Bioglass 45S5. The addition of the studied ions may benefit the biological response of Bioglass 45S5 in dental applications as scaffolds or coatings. [ABSTRACT FROM AUTHOR]

Ruddlesden Popper-type (RP-type) oxides have been attracted due to their immense applications in oxygen separation, antennas, luminescence, catalysts, lithium-ion battery electrodes, sensors, and solid oxide fuel cells. The RP- type Sr2(Ce1-xFex)O4 (x = 0–1.0) series has been synthesised via a novel sol–gel technique and characterised with regards to structure, detailed bond length/angles, and Raman spectra. It involves the mixing of nitrate salt solutions with oxalic acid, digestion for 12 h, dried at 130 °C for 24 h and calcined at 900–950 °C for 5 h in air for the formation. X-ray diffraction cum Rietveld refinement depicts single (orthorhombic), dual (orthorhombic + tetragonal), and single (tetragonal) phase formation with x = 0–0.03, 0.05–0.80, and 0.90–1.0, respectively. It possesses lattice parameters ao = 6.123 Å, bo = 10.359 Å, co = 3.598 Å, Z = 4, space group Pbam for x = 0 and tetragonal parameters at = bt = 3.867 Å, ct = 10.167 Å, Z = 2, space group I4/mmm for x = 1.0. However, the volume of orthorhombic and tetragonal unit cells decreases and increases, respectively, with iron. As iron in Sr2(Ce1-xFex)O4 increases, the structure becomes distorted, and octahedral angles B–O–B and O–B–O deviate drastically. The average bond length decreases from 2.715 to 2.308 Å with 'x', showing the analogous nature of the orthorhombic cell volume. Also, total cell volume decreases by 228.1–181.8 Å3 with iron. The particle size lies in the range of 100–200 nm. Raman spectra consist of bands at 144, 287, 343, 385, and 553 cm−1 for x = 0, and reveal vibrational and stretching modes. It depicts vibrational mode of strontium (Sr2+) ions coordinated by oxygen, stretching mode of Ce–O2 (equatorial), Ce–O1 (terminal), strontium displacement along c-axis, and vibration of Ce–O bonds. Bands at 139, 178, 273, 378, 456, and 581 cm−1, for x = 1 (tetragonal phase), reveal vibration of Sr–O2, Sr–O1 in ab plane, Sr–O2 in the c-plane, bridging in Sr–O2–Sr in ab plane, and vibration of FeO6 octahedra along c-axis, respectively. The intensity at 287 cm−1 band is higher than that at 385 cm−1 indicating applications in luminescence. Further, the band shifted towards a higher wave number with iron. Interestingly, structural and Raman results are supporting each other in the Sr2(Ce1-xFex)O4 (x = 0–1.0) series. [ABSTRACT FROM AUTHOR]

Nickel modified strontium hydroxyapatite (Ni/Sr-HAP) supported catalysts are studied in selective methanation of CO/CO2. In this work, a new type of nano rod-shaped strontium hydroxyapatite-based catalysts with two different sizes and aspect ratios were prepared by sol–gel method and in next step, Ni precursor was wet impregnated i.e., denoted as Ni/Sr-HAP and Ni/Sr-HAP(F127). The catalytic tests were performed in CO and CO2 methanation reactions and evaluated the light-off temperatures curves (225–450 °C) under ambient pressure in a fixed-bed flow reactor. The physicochemical properties of the prepared catalysts were characterized by XRD, N2 physisorption, TEM, SEM, TPR, CO2/H2-TPD and H2-chemisorption techniques. From XRD analysis, both Ni/Sr-HAP and Ni/Sr-HAP(F127) were identified as the hydroxyapatite type structure with high crystallinity and very low intensity peaks corresponds to strontium phosphates as the main phase and structure. The TEM and SEM micrographs of Ni/Sr-HAP catalysts displayed a nano- rod shaped morphology with different dimensions and exhibited average Ni particle size of ~ 9.2 nm. While Ni/Sr-HAP(F127) shown the rod size in the length in the range of 100–250 nm and width in the range of 20–40 nm with average Ni particle size 5.7 nm. The F127 mediated support Sr-HAP synthesis i.e., Ni/Sr-HAP(F127) mesoporous catalyst possessed higher metal surface with smaller Ni particles size and possessed higher CO2 adsorption capacity. The medium strength basic sites of Ni/Sr-HAP catalyst played an important role in methanation reactions. Based on the characterization and the catalysts activity results, small sized nanorods of Ni/Sr-HAP(F127) is the most active and selective catalyst due to the higher Ni dispersion, higher amounts of medium basic sites, and reducibility character than the bigger nanorods based Ni/Sr-HAP catalyst. [ABSTRACT FROM AUTHOR]

In this work, the Prussian blue nanorod was successfully synthesized and layer-by-layer deposited on polyurethane foams for removed strontium ions. The prepared composites were characterized by Fourier transform infrared (FT-IR), thermalgravimetric analysis (TG), atomic force microscope (AFM) and scanning electron microscopy (SEM). Prussian blue/Polyurethane foams (PB/PUF) exhibit huge surface area, pore volume and good resilience. PB/PUF displayed a maximum adsorption capacity of 45.15 mg/g for Sr2+ at room temperature. The pseudo-second-order equation was the best fit model for adsorption kinetic data compared with pseudo first-order and Elovich equation. The adsorption isotherm was investigated at 25, 30, and 35 °C, the data were in good agreement with the Freundlich isotherm. The thermodynamic parameters calculated by Van't Hoff equation, the negative ΔG° indicated the adsorption process was spontaneous. Furthermore, the effect of co-existing ions on adsorption and the reusability of PB/PUF was also investigated. The PB/PUF presented high adsorption performance on Sr2+ and easy separation from wastewater. It is predicate that PB/PUF being an effective adsorbent for eliminating Strontium from radioactive wastewater. [ABSTRACT FROM AUTHOR]

Nickel modified strontium hydroxyapatite (Ni/Sr-HAP) supported catalysts are studied in selective methanation of CO/CO2. In this work, a new type of nano rod-shaped strontium hydroxyapatite-based catalysts with two different sizes and aspect ratios were prepared by sol–gel method and in next step, Ni precursor was wet impregnated i.e., denoted as Ni/Sr-HAP and Ni/Sr-HAP(F127). The catalytic tests were performed in CO and CO2 methanation reactions and evaluated the light-off temperatures curves (225–450 °C) under ambient pressure in a fixed-bed flow reactor. The physicochemical properties of the prepared catalysts were characterized by XRD, N2 physisorption, TEM, SEM, TPR, CO2/H2-TPD and H2-chemisorption techniques. From XRD analysis, both Ni/Sr-HAP and Ni/Sr-HAP(F127) were identified as the hydroxyapatite type structure with high crystallinity and very low intensity peaks corresponds to strontium phosphates as the main phase and structure. The TEM and SEM micrographs of Ni/Sr-HAP catalysts displayed a nano- rod shaped morphology with different dimensions and exhibited average Ni particle size of ~ 9.2 nm. While Ni/Sr-HAP(F127) shown the rod size in the length in the range of 100–250 nm and width in the range of 20–40 nm with average Ni particle size 5.7 nm. The F127 mediated support Sr-HAP synthesis i.e., Ni/Sr-HAP(F127) mesoporous catalyst possessed higher metal surface with smaller Ni particles size and possessed higher CO2 adsorption capacity. The medium strength basic sites of Ni/Sr-HAP catalyst played an important role in methanation reactions. Based on the characterization and the catalysts activity results, small sized nanorods of Ni/Sr-HAP(F127) is the most active and selective catalyst due to the higher Ni dispersion, higher amounts of medium basic sites, and reducibility character than the bigger nanorods based Ni/Sr-HAP catalyst. [ABSTRACT FROM AUTHOR]

Lead-free Ba1−xSrxTiO3 (BST) (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.45) ceramics were successfully prepared via the solid-state reaction route. A pure perovskite crystalline structure was identified for all compositions by X-ray diffraction analysis. The basic phase transition temperatures in these ceramics were studied over a wide temperature range. A change in symmetry from a tetragonal to cubic phase was detected, which was further proven by phonon anomalies in composition/temperature-dependent Raman spectra. The incorporation of Sr2+ into BaTiO3 (BT) lead to a shift in the phase transitions to lower temperatures, suppressing the ferroelectric properties and inducing relaxor-like behavior. Therefore, it was reasonable to suppose that the materials progressively lack long-range ordering. The initial second-harmonic generation (SHG) measurements demonstrated that the cubic phase of BST ceramics is not purely centrosymmetric over a wide temperature interval. We discussed the possible origin of the observed effects, and showed that electric field poling seems to reconstruct the structural ordering destroyed by the introduction of Sr2+ to BT. In the first approximation, substitution of Sr for larger Ba simply reduced the space for the off-central shift in Ti in the lattice and hence the domain polarization. A-site cation ordering in BST and its influence on the density of electronic states were also explored. The effect of doping with strontium ions in the BST compound on the density of electronic states was investigated using ab initio methods. As the calculations showed, doping BT with Sr2+ atoms led to an increase in the bandgap. The proposed calculations will also be used in the subsequent search for materials optimal for applications in photovoltaics. [ABSTRACT FROM AUTHOR]

Many non-traditional isotopes, such as chlorine, magnesium, calcium, etc., are widely used as groundwater tracers. A new sample processing protocol of purification and concentration for isotopic analysis is presented to overcome many of the major drawbacks of existing methods. Contemporary sample preparation often requires several laborious off-line procedures in a ultra clean laboratory prior to instrumental determination; additionally, interference ions in real samples are difficult to completely remove, especially when the concentration of those ions is equal to that of the target ions. The new protocol includes the following steps: (i) one-step purification using a newly developed isotopic preparative chromatograph (IPC) with a background suppressed mode to obtain extremely pure components that only have target ions and H2O; (ii) enrichment of the collected pure solution from the previous step using a newly developed ultra clean concentrator filled with high purity nitrogen; (iii) transforming the enriched target ion into suitable speciation inside the ultra clean concentrator; (iv) finally, sending the enriched solutions to a multi-collector inductively coupled-plasma mass-spectrometer (MC-ICP-MS) or thermal ionization mass spectrometer (TIMS). The present method was validated using certified reference materials and real samples for both chlorine and magnesium; the precision of chlorine ratio value was generally below 0.22‰ and that of Mg was below 0.12‰. This processing protocol provides a potential method for isotope sample preparation and analysis in a small number of geological samples with low concentrations of many other elements or compounds such as nitrate, sulfate, lithium, calcium, strontium, etc. [ABSTRACT FROM AUTHOR]

While barium (Ba) and strontium (Sr) stable isotopes are increasingly used as tracers of biogeochemical processes and paleo-proxies, the role of biotic processes on Ba and Sr isotope fractionation is poorly understood. Here, Ba and Sr stable isotope fractionations were studied in the laboratory using Gloeomargarita lithophora , a cyanobacterium that selectively hyperaccumulates Ba and Sr within intracellular amorphous carbonate biominerals. Our results show that lighter Ba and Sr isotopes are enriched in G. lithophora cells compared to the initial solution by –0.24‰ to –0.03‰ (δ137Ba) and –0.33‰ to –0.01‰ (δ88Sr) depending on the stage of the experiment. The fractionation of Ba and Sr isotopes is distinct in magnitude from that occurring during abiogenic and other known biogenic carbonate formation cases. Additionally, using a Rayleigh fractionation model, the fractionation factors of Ba and Sr isotopes between G. lithophora cells and the fluid (the growth medium), i.e., Δ137Ba (bac-sol) and Δ88Sr (bac-sol) , were equal to –0.25‰ and between –0.46‰ and –0.38‰, respectively. Interestingly, δ137Ba sol and δ88Sr sol decreased at the end of Ba and Sr uptake stages back towards their initial values, which caused departures from the Rayleigh fractionation model. This suggests the existence of a back reaction resulting in a Ba and Sr outflux from cells to the solution. Possible hypotheses for this back-reaction include dissolution of amorphous carbonate inclusions in response to cellular stress, or a first-order rate dependence of amorphous carbonate dissolution on the amount of Ba and Sr inside the cell. Our findings suggest that bacteria forming intracellular amorphous carbonates could introduce Ba and Sr isotope variability in environmental records, especially in environments where they thrive. Moreover, the enrichment of lighter isotopes of Ba and Sr during amorphous carbonate formation is consistent with that occurring during the formation of other biogenic carbonates but slightly differs in magnitude, opening a discussion about the possibility to use Δ137Ba (bac-sol) and Δ88Sr (bac-sol) as an indicator of intracellular amorphous carbonate biomineralization in the fossil rock record. Overall, this work highlights the complexity of the biological uptake of alkali-earth metals and stresses the overlooked role of bacteria forming intracellular amorphous carbonates in Ba and Sr biogeochemical cycles. [ABSTRACT FROM AUTHOR]

In this study, activated carbons derived from walnut shells (CA-N) and apple wood (CA-M) were used as adsorbents to remove cobalt(II) and strontium(II) ions from aqueous solutions. The novel materials were obtained using nitric acid (CA-Mox) and nitric acid/urea mixture (CA-Mox-u, CA-Nox-u) as oxidizing agents. The physical–chemical characteristics of activated carbons were determined from nitrogen sorption isotherms, SEM-EDX, FTIR, pH metric titrations, the Boehm titration method and elemental analysis. The results of batch experiments indicate that maximum adsorption can be achieved in broad pH ranges: 4–8 for Co(II) and 4–10 for Sr(II). The maximum adsorption capacities of Co(II) and Sr(II) on oxidized activated carbons at pH = 4 are: CA-Mox, 0.085 and 0.076 mmol/g; CA-Mox-u, 0.056 and 0.041 mmol/g; and CA-Nox-u, 0.041 and 0.034 mmol/g, respectively. The mathematical models (pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models, and Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin–Pyzhev isotherm models) were used to explain the adsorption kinetics, to study the adsorption mechanism and predict maximum adsorption capacity of the adsorbents. The adsorption mechanisms of toxic metal ions on activated carbons were proposed. [ABSTRACT FROM AUTHOR]

The Reshui area, located to the northeast of the Qinghai–Tibet Plateau, exhibits complex geological conditions, well-developed structures, and strong hydrothermal activities. The distribution of hot springs within this area is mainly controlled by faults. In this paper, five hot springs from the area were taken as the research object. We comprehensively studied the geochemical characteristics and genetic mechanism of the geothermal water by conducting a field investigation, hydrogeochemistry and environmental isotopic analysis (87Sr/86Sr, δ2H, δ18O, 3H). The surface temperature of the geothermal water ranges from 84 to 91 °C. The geothermal water in the area exhibits a pH value ranging between 8.26 and 8.45, with a total dissolved solids' (TDS) concentration falling between 2924 and 3140 mg/L, indicating a weakly alkaline saline nature. It falls into the hydrochemical type CI-Na and contains a relatively high content of trace components such as Li, Sr, B, Br, etc., which are of certain developmental value. Ion ratio analysis and strontium isotope characteristics show that the dissolution of evaporite minerals and carbonate minerals serves as a hot spring for the main source of solutes. Hydrogen and oxygen stable isotope characteristics findings indicate that the geothermal water is primarily recharged via atmospheric precipitation. Moreover, the tritium isotopic data suggest that the geothermal water is a mixture of both recent water and ancient water. Moreover, the recharge elevation is estimated to be between 6151 and 6255 m. and the recharge area is located in the Kunlun Mountains around the study area. The mixing ratio of cold water, calculated using the silicon enthalpy equation, is approximately 65% to 70%. Based on the heat storage temperature calculated using the silicon enthalpy equation and the corrected quartz geothermal temperature scale, we infer that the heat storage temperature of geothermal water in the area ranges from 234.4 to 247.8 °C, with a circulation depth between 7385 and 7816 m. The research results are highly valuable in improving the research level concerning the genesis of high-temperature geothermal water in Reshui areas and provide essential theoretical support for the rational development and protection of geothermal resources in the area. [ABSTRACT FROM AUTHOR]

The strontium (II) uptake on Chlorella vulgaris was studied in a batch system. The interactive effects of parameters such as pretreatment, initial pH, temperature, initial concentration, and biosorbent dosage, on the biosorption of strontium were analyzed using the response surface methodology. The biosorption capacity of the algae at optimal conditions of initial pH 7.4, biosorbent dosage 1 g/L, and initial strontium concentration 300 mg/L for Ca-treated biomass was found to be 98.33 mg/g. Investigation of the kinetics showed that the biosorption process follows the pseudo-second-order model. Also the equilibrium of the process showed a better fit by the Langmuir isotherm. [ABSTRACT FROM AUTHOR]

To achieve the mutual separation of yttrium(Y(III)) and strontium(Sr(II)) from acidic solution, a diglycolamic acid-grafted adsorbent (DGAA−Si adsorbent) was successfully developed via a facile amidation reaction between diglycolic anhydride and a 3-aminopropyl-functionalized silica-gel. The adsorption performances of DGAA−Si adsorbent toward Y(III) and Sr(II) were systematically investigated in terms of the effect of the acid concentration etc. The particle-induced X-ray emission analysis method was used to study the adsorption behavior in the solid-state and elucidated the distribution conditions of the adsorbed Y(III) and Sr(II). Moreover, the mutual separation of Y(III) and Sr(II) was successfully achieved using acid in different concentration as an effluent solution. [ABSTRACT FROM AUTHOR]

Saffron is regarded as the most expensive spice, mainly because of its laborious harvest. Only a few countries dominate the global saffron market, with Iran producing by far the most saffron, and the saffron production of all other countries thus being much smaller. However, the respective national production (not only of saffron) is usually preferred by local consumers with respect to foreign products and often has a higher price. Cases of saffron with mislabeled geographic origin have repeatedly occurred. Thus, to protect local saffron production, control of the declared geographic origin is required. In the present case, differentiation of the geographic origin by 87Sr/86Sr is performed. The results show the saffron of several countries of origin to vary within the range of marine carbonates; however, saffron samples of Moroccan and Indian origin mainly show elevated 87Sr/86Sr values. Within the Indian saffron samples, one sample from Kishtwar Valley can be differentiated from the Kashmir saffron samples. The results are thus promising, especially when using the combination of Sr and Rb concentrations to differentiate geographic origin whenever the regions are of homogenous bedrock geology within and of different geology between the regions. However, the reported findings need to be checked and confirmed by further and additional saffron samples. [ABSTRACT FROM AUTHOR]

The physical and chemical properties of many oxide materials depend strongly on their defect concentration, which gives rise to unique electronic, optical, and dielectric properties. One such promising material for various applications, including energy storage, photocatalysis, and electronics, is SrTiO3 (STO). It exhibits several interesting phenomena, including a metal-to-insulator transition that can be induced by reduction. By extension, 1-D defects, such as dislocations, play a significant role in its electronic properties. Thus, we investigate the process of dislocation movement, its creation, and annihilation under two stimuli: ion thinning and electron irradiation. First, we designed and produced a lamella from a mechanically modified sample with variable thickness in the form of a wedge using a focused ion beam (FIB/Ga+) to investigate thickness-dependent dislocation movement. The lamella was investigated by transmission electron microscopy, allowing for the measurements of dislocation concentration as a function of its thickness. We have noticed a sharp decrease in the defect concentration with respect to the starting sample, showing a process of annihilation of dislocations. Second, we used an electron beam to drive a relatively large current into the STO surface. This experiment produced an electrical breakdown-like pattern. Optical and atomic force microscopy revealed that this pattern evolved due to the removal of material from the surface and local metal-insulator-transition along the dislocations network. Thus, we observe the dislocations generation and movement. [ABSTRACT FROM AUTHOR]

Focusing on the degradation of organic dyes in wastewater, a novel titania composite nanofiber small area film photocatalyst with improvedphotocatalytic activity using strontium ions and graphite as dual cocatalysts has been synthesized by electrospinning and hydrothermal methods.Morphology control, doping causing crystal defect engineering (strontium ion doping), and heterojunction building (graphite surface modification) strategies are simultaneously applied to the synthetic design of new photocatalysts.In degradation tests of rhodamine B, methyl orange, methylene blue, and malachite green, the degradation rate constants were 2.57, 2.85, 3.06, or 3.54 times higher than those of pure titania, respectively.The composite nanofiber small area film exhibited excellent recyclability in fourrecycling tests.The improved photocatalytic activity of titania composite nanofiber small area film is attributed to the morphology of the nanofibers with the addition of more reaction sites, dopingwith more crystal defects, and heterojunctions providing channels for the transfer of photogenerated carriers.Design solutions with the synergistic effects of multiple strategies inform the use of titania in industrial applications. [ABSTRACT FROM AUTHOR]