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Sm 0.5 Sr 0.5 CoO 3-δ (SSC) fiber-electrode materials were prepared via electrospinning in this work. The characteristics of SSC fibers are influenced by the parameters of electrospinning, specifically the nitrate concentration of the spinning solution, applied voltage, and the gap between the spinneret and collector. The as-prepared SSC fibers exhibited average diameters ranging from 240 nm to 6.49 μm, which contracted to 50 nm–2.53 μm after calcination at 800 °C. Symmetric cells with SSC fiber-electrodes demonstrated an area-specific resistance (ASR) ranging from 0.212 to 0.508 Ω cm2 at 700 °C in air. In addition to the morphology of SSC fibers, the average grain size of the SSC fibers also exhibited potential influence on their ASR performance. [ABSTRACT FROM AUTHOR]

In this work, the effects of SrCO 3 and Fe 2 O 3 particle size on the reaction process, morphology and magnetic properties of M-type strontium hexaferrites (SrM) have been further studied. Pure strontium hexaferrite magnetic sample based on SrCO 3 and Fe 2 O 3 molar ratio of 1:6 has been successfully prepared at 1150 °C. The results indicated that Fe 2 O 3 particle size was the main factor of affecting the formation of SrM, a pure SrM phase magnetic sample was able to obtain at lower calcination temperatures by using fine Fe 2 O 3 powder as raw material, and at the same calcination temperature, a sample using fine Fe 2 O 3 powder as raw material was able to obtain pure SrM phase magnetic sample with shorter holding time. When the mean particle size of Fe 2 O 3 was below 60 nm, a pure SrM phase magnetic sample was able to form at 1150 °C at a molar ratio of 1:6 of SrCO 3 and Fe 2 O 3. In this case, the magnetic parameters of the sample with the optimum magnetic parameters were saturation magnetization M S = 77.8 emu/g and coercive force H C = 4122 Oe. And the solid-state reaction process of the corresponding samples was slightly faster when the mean particle size ratio of Fe 2 O 3 and SrCO 3 was between 0.35 and 0.36. Assuming that a SrCO 3 particle is surrounded by Fe 2 O 3 particles, it can be inferred that the corresponding molar ratio of Fe and Sr of the nearest raw material particles is between 3.6 and 3.8. [ABSTRACT FROM AUTHOR]

Strontium is a potent osteo-stimulative element with a wide safe dosage range. In this work, calcium-strontium phosphate (Ca 2 Sr(PO 4) 2 ; abbreviation: CSP) was synthesized, and 3D-printed CSP-based composite (CSP-T) ceramic scaffolds were prepared by introduction of β-tricalcium phosphate (TCP). When sintering the CSP-T ceramic scaffolds, no new phase was produced, but the strontium from CSP was substituted for calcium in TCP; the TCP additives promoted densification of scaffold filaments, resulting in lower porosity of the CSP-T ceramic scaffolds. The porosity (25.6%–77.1 %) and compressive strength (1.5–44.5 MPa) of CSP-T ceramic scaffolds could be adjusted by altering the amount of TCP additives and the sintering temperature. The CSP-T ceramic scaffolds gradually released ions of calcium, phosphorus and strontium, which were in favor of cell growth and osteogenic differentiation. The CSP-T ceramic scaffolds modified by 25 wt% TCP possessed the greatest performances on enhancing mechanical strength and cellular response, which let them serve as promising bone grafts to treat various sites of bone defects. [ABSTRACT FROM AUTHOR]

Sr 1- x Ce x Fe 12 O 19 and Sr 1- x Ce x Fe 12- y O 19-δ (x = 0–0.2, y = 0–2) powders were synthesized by sol-gel auto-combustion method, and the effect on the structure and magnetic properties of changes in doping concentration and iron content has been investigated. XRD results confirmed the formation of M phase and impurities of CeO 2 and Fe 2 O 3. The SEM results show that cerium doping leads to a decrease in grain size. For Sr 1- x Ce x Fe 12 O 19 , the saturation magnetization increases to 77.73 emu/g first and then decreases with the increase of cerium doping. More importantly, our study also found that as the Ce doping concentration and iron content change, the interaction between the two changes differently. This interaction will have different effects on the occupancy of iron ions at spin-up and spin-down sites, ultimately leading to a significant characteristic change in magnetic properties. For Sr 1- x Ce x Fe 12- y O 19-δ , with the iron content decreases, the magnetic properties continue to decrease at x = 0.03, increase first and then decrease at x = 0.1, and keep improving at x = 0.2. It is of reference significance to change the magnetic properties of strontium ferrites by adjusting the relationship between rare earth doping concentration and iron content. [ABSTRACT FROM AUTHOR]

This research was focused on the influence of manganese (Mn) incorporation at Sr and/or Ti sites on the microstructure, relative dielectric permittivity and specific magnetization of strontium titanate (SrTiO 3) ceramics. A solid-state method was used for the preparation of mechanically activated (10, 30 and 120 min) Mn-doped SrTiO 3 ceramics with various manganese dioxide (MnO 2) weight percentages (1.5, 3 and 6 wt%). Rietveld's analysis showed that the mean crystallite size in doped-activated SrTiO 3 ceramics is smaller than in undoped ceramics, which is a consequence of additional crystal structure distortion due to ion substitution. Changes in the Raman spectra indicated dopant incorporation in the SrTiO 3 lattice. The microstructural analysis pointed out a decrease in the mean grain size with increasing dopant concentration and time of activation. The highest values of permittivity and magnetization were observed for Mn-doped SrTiO 3 ceramic mechanically activated for 120 min. Based on all the above, the optimal electrical and magnetic properties of SrTiO 3 ceramics can be achieved by the appropriate choice of mechanical activation time and dopant concentration. [ABSTRACT FROM AUTHOR]

Energy storage capacitors for advanced pulse power systems and high-power electric devices is a kind of important electronic components, the demand continues to grow, specifications are constantly being upgraded, and performance boundaries are continuously being pushed. Multilayer ceramic capacitors (MLCCs) for energy storage applications have received increasing attention due to the advantages of ultralow equivalent series inductance, equivalent series resistance, good frequency characteristics, strong voltage overload ability, and stable operability at high temperatures. However, the relatively low energy storage density significantly limits its broader applications. Here, 0.4Ba 0.55 Sr 0.45 TiO 3 -0.4Bi 0.5 Na 0.5 TiO 3 -0.2SrZrO 3 (0.4BST-0.4BNT-0.2SZ) relaxor ferroelectric MLCCs are prepared at different heating rates. Excellent recoverable energy storage density of 10.3 J cm−3 and high energy efficiency of 93 % are achieved in fast-fired MLCCs under the electric field of 106.3 V μm−1. The impedance spectroscopy and thermally stimulated depolarization current technologies are employed to investigate the conductance mechanism of MLCCs, and the results can explain the effect of heating rate on the performance of MLCCs. In addition, the charge-discharge performances of fast-fired MLCCs are also thoroughly investigated, exhibiting great thermal and fatigue stability. [ABSTRACT FROM AUTHOR]

The crystal structure, oxygen content and homogeneity range of Pr 1-x Sr x CoO 3-õ solid solutions from room temperature (RT) up to 1100 °C in air were studied. It has been shown that an increase in temperature and Sr content causes an Orthorhombic → Rhombohedral → Cubic transformation of the crystal structure. The heterovalent substitution of Sr2+ for Pr3+ is compensated by an increase in the mean oxidation state of Co ions (z Co) and the formation of oxygen vacancies. The temperature dependences of thermal expansion and conductivity of Pr 1-x Sr x CoO 3-õ solid solutions are explained from the point of view of crystal and defect structure. The diagram of phase relation in the PrCoO 3 – "SrCoO z " cross section has been constructed. [ABSTRACT FROM AUTHOR]

The development of lead-free dielectric capacitors with good energy storage performance and high reliability is of great practical significance for pulsed power systems. In this study, Nb 2 O 5 -modified 0.6(Bi 0.5 Na 0.5)TiO 3 -0.4(Sr 0.7 Bi 0.2)TiO 3 (BNT-SBT- x Nb, 0 ≤ x ≤ 0.07) ceramics were designed to enhance their energy storage performance and prepared using a hydrothermal method. The results show that Nb doping into the B site of BNT-SBT can induce lattice expansion and promote polar nanoregions, resulting in improved dielectric relaxation behavior. Moreover, the introduction of Nb can lead to the refinement of grain size, the increase in resistivity, the reduction of oxygen vacancies, and the broadening of band gap, thereby significantly enhancing the electrical breakdown strength (E b). Accordingly, the BNT-SBT-0.05Nb system presents excellent energy storage performance with high W rec ∼6.26 J/cm3 and η ∼87.9 % under an large E b of 518 kV/cm in accompany with the wide temperature stability (W rec and η vary within ±6.8 % and ±3.2 % at 40–100 °C). The significant improvement of E b and energy storage performance demonstrates that the BNT-SBT-0.05Nb system is a potential candidate for applications in high-energy storage capacitors. [ABSTRACT FROM AUTHOR]

The crystal structure of La 0.7 Sr 0.3 Mn 1−x Al x O 3 (LSMAO) with x = 0,0.025,0.05,0.075 and 0.10 ceramics prepared by the Sol-gel method were investigated by employing the XRD technique. The XRD patterns analysis by employing the Rietveld analysis confirms the nonexistence of secondary crystal phase/s and, materials are crystallized to the R-3c(167) space group. The microstructural properties were studied using scanning electron microscope (SEM) and transmission electron microscope (TEM). The dielectric property, AC conductivity, complex impedance spectroscopy and complex electrical modulus have been studied over a wide range of frequencies (103 Hz–107 Hz) at different temperatures from 313K to 393K. The Non-Debye type relaxation process has been observed in synthesized samples confirmed from the Nyquist plot. The Cole-Cole plots were employed to estimate the individual grain and grain boundary contributions. The Maxwell-Wagner (MW) polarization model provides an explanation for the greater values of dielectric constant at the lower frequencies. The present study explores the technological usefulness of LSMAO. [ABSTRACT FROM AUTHOR]

Doping Sr has the potential to enhance bioceramic properties. However, controlling purity, Sr concentration, and properties is crucial. Therefore, precise evaluation of synthesis variables is essential, achieved through experimental design techniques. This study synthesized Sr-doped calcium silicate wollastonite using a Plackett–Burman design with 11 variables to identify key factors affecting synthesis yield and physical, structural, and chemical attributes for tissue engineering. Results indicate that the strontium proportion significantly impacts material properties, affecting porosity, surface area, and pore volume. Moreover, observations reveal that calcination temperature contributes to heightened crystallinity and strontium doping. Adjusting calcium and strontium precursor concentrations while reducing the silicon to calcium and strontium ratio improves efficiency crystallinity, purity, and promotes the formation of the preferred β-CaSiO 3 phase. Overall, consistent and reproducible findings provide valuable insights into the variables influencing the process and facilitate optimization for future ceramic synthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

Spinel materials are attractive to photocatalytic degradation of contaminants. In this study, strontium (Sr) doped spinel cobalt chromite (CoCr 2 O 4) was synthesized by solution combustion method and characterized using techniques such as X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and electrochemical impedance spectroscopy (EIS). 30 -50 nm-cubic CoCr 2 O 4 nanocrystals were obtained, and phase transitions of CoO 6 →CoO 4 and CrO 4 →CrO 6 occurred as the Sr doping content increased until 0.6 % Sr doped sample displayed an inverse spinel phase. The modifications in composition and structure induced the co-existence of multivalent states for Co and Cr, which in turn changed the optical, complex impedance, and magnetic spin state of CoCr 2 O 4. The 0.6 % Sr-doped sample showed the highest photocatalytic efficiency of 93 % due to enhanced optical absorption, reduced energy band gap, oxygen vacancies formation, and a high spin state of Co. The XRD structure and photocatalytic activity remained stable even after five cycles without any leakage of metal elements. The degradation pathway and Mott-Schottky curves were employed to elucidate the mechanism behind this enhancement. The strategy employed in this study proved effective, and the synthesized materials show promise for the photocatalytic degradation of contaminants. [ABSTRACT FROM AUTHOR]

The lead-free piezoelectric ceramics used in piezoelectric actuators have attracted extensive attention owing to their substantial electric-field-induced strain. In this study, The (1- x)Bi 0.5 (Na 0.41 K 0.09)TiO 3 - x Sr(Hf 0.5 Sb 0.4)O 3 (BNKT- x SHS) piezoelectric ceramics were synthesized using the conventional solid-state reaction method. The impact of SHS substitution on the microstructure and electrical properties was systematically explored. Among them, the BNKT-0.015SHS sample, featuring ergodic relaxor states, demonstrates a high piezoelectric strain coefficient (d 33 *) of 785 p.m./V under a low electric field of 50 kV/cm(Strain = 0.392 %). It exhibits a repeatable strain value of 0.47 % under an 80 kV/cm electric field(d 33 * = 590 p.m./V). Moreover, the strain values remain around 0.4 % between room temperature and 100 °C, with variations within 90 %. The heightened repeatable strain response is considered to be linked to the electric field-induced reversible phase transition occurring within the ergodic relaxor state. The higher strain temperature stability is ascribed to the coexistence of quadrilateral polar nanoregions and rhombic polydomain nanoregions. This study provides an effective example for achieving significant strain responses, presenting a feasible candidate material for applications in piezoelectric actuators. [ABSTRACT FROM AUTHOR]

Developing low-cost and high-efficiency non-precious metal cocatalysts is the key to the practical application of photocatalysis technology. Here, nickel sulfide (NiS) nanoparticles were synthesized on the surface of strontium titanate (SrTiO 3) via a hydrothermal method, identifying the optimal loading molar concentration of NiS as 10 %. The solar-to-hydrogen efficiency (STH) of 10%NiS/SrTiO 3 :Al was enhanced by 97 times compared to SrTiO 3 :Al and by 1.62 times compared to RhCrCoO x /SrTiO 3 :Al. This improvement is primarily attributed to the metallic-like properties of NiS, which enhance the photocatalyst's light absorption capacity and charge transfer capability. Additionally, the STH value of samples loaded with both NiS and RhCrCoO x reached 0.436 %, indicating a positive synergistic effect in photocatalysis between NiS and RhCrCoO x. Their photocathodic protection capability was also studied in simulated seawater conditions, showing a reduced self-corrosion potential (−0.31V) and a low interface charge impedance (5962 KΩ). This work reveals the potential of NiS as an alternative to precious metal cocatalysts, offering new possibilities for developing cost-effective and high-performance materials for photocatalytic water splitting and photocathodic protection. [ABSTRACT FROM AUTHOR]

This research meticulously explores the synthesis, structural, thermal and optical characterization of zinc oxide nanoparticles (NPs) infused strontium borate glasses (termed SZ glasses) and their applicability as radiation shielding. The glasses have been produced using the melt quenching process in the composition series of (60-x)B 2 O 3 : xZnO: 10SrO: 10Na 2 O: 10CaO: 10BaO, where x varied from 0 to 20 % mol. In order to dope ZnO into glasses, its structural and morphological characteristics were investigated after it was synthesized by solution combustion method. It was found that the inclusion of ZnO significantly impacted the glasses' density, molar volume, hardness, yield stress, and thermal stability. The optical properties of the produced glasses, such as transmittance, reflection, transparency, opacity and band gap energies, were examined and the effect of ZnO on the optical properties of the glasses was investigated. Crucially, the SZ glasses exhibited notable efficiency in shielding against gamma photons and fast neutrons. This is evidenced by the favourable change in the mass attenuation coefficients with increasing ZnO concentration. Parameters like the half-value layer, effective atomic number, and energy absorption buildup factors were calculated to gauge the radiation attenuation proficiency of the SZ glasses, demonstrating their potential utility in radiation protection. In conclusion, the developed SZ glasses display advantageous structural, thermal, and optical qualities, along with robust shielding capabilities against gamma photons and fast neutrons. This study contributes significant knowledge to the field of novel glass materials, paving the way for their application in various industrial and medical contexts requiring radiation shielding. [ABSTRACT FROM AUTHOR]

The pursuit of efficient materials for technological applications is essential. Among these materials, zirconia emerges as a promising candidate with potential for several applications, from applications related to mechanical resistance to optoelectronic applications. By introducing dopants into this compound, it becomes feasible to modulate its inherent properties. In this study, ZrO 2 doped with strontium was synthesized for the first time via the sonochemical method at different percentages in mol (1, 2, 4, and 8 mol%). Analysis via X-ray diffraction (XRD) and Raman spectroscopy unveiled the formation of both monoclinic and tetragonal phases, with the latter being stabilized through the incorporation of the dopant element. In addition to observing irregular morphology through scanning electron microscopy (SEM-FEG), a reduction in particle size was also evidenced following the introduction of Sr2+ ions, a phenomenon corroborated via Rietveld refinement. The reflectance spectra of the doped samples exhibited an optical absorption tail characterized by the Urbach energy (E U), indicating an increase in structural disorder in the samples. The photoluminescence (PL) results indicated that the introduction of Sr2+ ions into the ZrO 2 matrix induced modifications in the characteristics of the spectrum profile. The phase transformation observed in XRD was reflected in the changes observed in the photoluminescent behavior of the samples, which emitted light between the blue and green regions. [ABSTRACT FROM AUTHOR]

A nickel catalyst on mesoporoussilica created through a direct synthesis and modified with a strontium promoter. After conducting dry and steam reforming tests, the prepared samples characterized using the XRD, XRF, BET, TPR and HR-TEM, and then considered to study the catalyst stability and activity. And, the CH 4 and CO 2 conversion and ratio of H 2 /CO with using the Sr–Ni/MCM-41 catalyst in the DRM and SRM processes at 700 °C, were determined about (73.3% and 80.6%), (55.81% and 60.25%), and (0.88 and 3.1), respectively. Furthermore, SEM, TPR, and TPD analysis were used to characterize the utilized catalyst. The finding demonstrated a good structural order and the specific surface area (SSA) of 889.5 m2/g. The presence of a strontium enhanced nickel oxide's reducibility and strengthened its interaction with the base. Furthermore, strontium enhanced the catalytic activity. [Display omitted] • Sr-promoted Ni/MCM-41 catalyst was synthesized by the direct method. • Catalysts were compared in two dry and steam methane reforming processes. • Sr–Ni/MCM-41 catalyst had better catalytic performance in dry reforming of methane. • Sr–Ni/MCM-41 catalyst shows the highest stability and resistance to deposition and coke formation. [ABSTRACT FROM AUTHOR]

Hexaferrites, with their exceptional crystalline anisotropy, substantial coercivity, tuneable cations, and high magnetic hardness, are crucial as permanent magnets in applications such as information storage, sensors, high-frequency and microwave-absorbing devices. In this study, the focus was on synthesizing copper and cadmium-substituted strontium W-type hexagonal ferrites (SrCu 2-x Cd x Fe 16 O 27) with varying x values of 0.00, 0.01, 0.02, 0.03, and 0.04. To comprehensively investigate their structural, morphological and optical characteristics, several analytical techniques were employed, including XRD, SEM, FT-IR spectroscopy and UV–Vis spectroscopy along with dielectric and magnetic techniques. The XRD analysis showed a minimum crystallite size of 13 nm for x = 0.0 and a maximum of 21 nm for x = 0.04. The morphology was examined through SEM, affirming the characteristic structure of W-type hexaferrites. FT-IR spectra exhibited two prominent peaks at 491 cm−1 and 890 cm−1, further validating the creation of W-type hexaferrites. Notably, the UV–Vis spectroscopy demonstrated a reduction in the optical band gap from 2.41 to 2.11 eV with increasing concentrations. In terms of dielectric properties, a peak dielectric constant of 71 was observed at frequencies above 2.5 GHz. Furthermore, the AC conductivity displayed a linear trend at lower frequencies, reaching a maximum value of 0.35 [ohm cm]−1 at higher frequencies. The magnetic measurements indicated that the substitution of x = 0.04 exhibited the highest saturation magnetization, Ms value of 1.7 emu/g, but the lowest coercivity, Hc value of 75 Oe was observed. [ABSTRACT FROM AUTHOR]

Wollastonite (CaSiO 3 , CS) has shown a great potential as a bone biomaterial due to its favorable degradation behavior and the beneficial silicon and calcium ions released during its degradation. However, the rapid degradation of CS may result in a rapid increase in local pH values and lead to cell death. To address this issue and further enhance the biocompatibility, osteogenic, angiogenic, and osteoclast differentiation inhibitory properties of CS; zinc (Zn) and strontium (Sr) ions were introduced into CS through an ion-doping method. The effects of Zn doping, Sr doping, and Zn/Sr co-doping on the crystal structure, in vitro mineralization, and cellular responses of CS were systematically investigated. The results indicated that Zn doping and Sr doping had no significant effect on the phase of CS, while Zn/Sr co-doping promoted the substitution of Zn and Sr ions for calcium ions. Moreover, the introduction of Zn and Sr ions slowed the degradation process of CS and inhibited its in vitro mineralization activity. Furthermore, while Zn doping and Sr doping significantly enhanced the cytocompatibility and osteogenesis of CS, respectively, Zn/Sr co-doping exhibited synergistic effects in enhancing the osteogenesis of CS. Interestingly, the introduction of Zn and Sr ions also improved the angiogenic properties of CS and increased its ability to inhibit osteoclast differentiation; however, there was no significant synergistic effect between Zn doping and Sr doping on these properties. In conclusion, Zn/Sr co-doped CS exhibits a more suitable degradation rate and enhanced bioactivity, presenting significant application prospects in the field of bone defect repair. [ABSTRACT FROM AUTHOR]

Stable strontium and barium isotopes are potential tracers for understanding planetary differentiation and the nature of the building blocks of terrestrial planets. Strontium and barium are fluid-mobile elements, but it remains unclear how terrestrial weathering affects the Sr-Ba isotopes compositions in achondrites, thus hampering the utility of Sr-Ba isotopes in cosmochemistry. In this study, we conducted acetic acid leaching on three eucrites with varying weathering degrees (fall: Qiquanhu, hot desert find: Northwest Africa (NWA) 13583, and Antarctic find: Grove Mountains (GRV) 13001). Combined with detailed petrography observations and major and trace element analyses, we investigated the variations in Sr-Ba isotopes during terrestrial weathering. The degree of weathering follows an order of: NWA 13583 > GRV 13001 > Qiquanhu, evaluated based on several alteration signs, including: the presence of secondary carbonate, the enrichment of large ion lithophile elements (e.g., Sr, Ba, and U), and the Ce and Eu anomalies. The concentrations of Sr and Ba in the leachates of NWA 13583 show a good correlation with Ca, suggesting that the soluble Sr and Ba are derived from secondary carbonate. Differently, the concentrations of Sr and Ba in the leachates of Qiquanhu correlate with Al and Na, suggesting that the soluble Sr and Ba in Qiquanhu are derived from primary plagioclases. This also indicates that silicates dissolution may be inevitable in an acid leaching experiment for achondrites, even when using weak acetic acid. GRV 13001 shows no variation in Sr and Ba isotopes during leaching experiments. The δ 138/134Ba in the leachate (0.26 ± 0.02 ‰) of Qiquanhu is higher than that of the residue (0.04 ± 0.03 ‰), reflecting that aqueous fluids preferentially uptake heavy Ba isotopes during plagioclase dissolution. Conversely, the leachate of NWA 13583 shows lower δ 138/134Ba (-0.19 ± 0.05 ‰) than that of residue (-0.10 ± 0.03 ‰), reflecting the lighter Ba isotope composition in carbonate. Notably, the residue of NWA 13583 has δ 138/134Ba ∼ 0.1 ‰ lower than those of Qiquanhu and GRV 13001. This discrepancy may reflect plagioclase dissolution during hot-desert weathering rather than magmatism on the parent body. Different from Ba isotopes, the δ 88/86Sr of Qiquanhu shows tiny variation in the leaching experiment, suggesting that the dissolution of plagioclase may cause negligible Sr isotope fractionation. For NWA 13583, the δ 88/86Sr of leachate is slightly heavier than that of leaching residue and bulk rock, reflecting the high δ 88/86Sr in terrestrial fluids. Our results suggest that Ba and Sr isotopes of eucrites show different behaviors during terrestrial weathering. Sr isotopes show a smaller fractionation scale and may have greater resistance for terrestrial weathering than Ba isotopes. [ABSTRACT FROM AUTHOR]

Evaluate the ability of strontium fluoride on bond strength and enamel integrity after incorporation within orthodontic adhesive system as a delivery vehicle. Experimental orthodontic adhesive system Transbond™ XT were modified with 1% Sr2+, 0.5% SrF 2 , 1% strontium, 0.5% Sr2+, 1% F-, 0.5% F-, and no additions were control. Mixing of formulation was monitored using Fourier transform infrared spectroscopy. Small-molecule drug-discovery suite was used to gain insights into Sr2+, F-, and SrF 2 binding. Shear bond testing was performed after 6-months of ageing. Enamel blocks were cut, and STEM pictures were recorded. Specimens were indented to evaluate elastic modulus. Raman microscope was used to collect Raman spectra and inspected using a scanning electron microscope. Crystal structural analysis was performed using X-ray diffraction. Effect of material on cellular proliferation was determined. Confocal was performed to evaluate the effect of formulation on biofilms. FTIR of modified adhesives depicted peak changes within range due to various functional groups existing within samples. TEM represented structurally optimized hexagonal unit-cell of hydroxyapatite. Mean shear bond strength is recorded highest for Transbond XT with 1% SrF2. Dead bacterial percentage appeared higher in 0.5% SrF 2 and 1% F- specimens. Crystal lengths showed an increase in 0.5% and 1% SrF 2 specimens. Phase contrast within TEM images showed a union of 0.5% SrF 2 crystal with enamel crystal with higher elastic modulus and highly mineralized crystalline hydroxyapatite. Intensity of ν1 PO 4 3- and ν1 CO 3 2- along with carbonate - / ν1PO 4 3- ratio displayed good association with strontium fluoride. The formulation showed acceptable cell biocompatibility (p < 0.353). All specimens displayed characteristic diffraction maxima of different apatite angles within XRD. Experimental results suggested good biocompatibility, adequate mechanical strength, and far-ranging crystallization ability. This would provide a new strategy to overcome the two major challenges of fixed orthodontics, biofilm growth, and demineralization of enamel. [ABSTRACT FROM AUTHOR]

Strontium zirconate (SrZrO 3) is a technical ceramic with potential for refractory applications due to its chemical stability at high temperatures, high melting temperature, and favourable thermal expansion coefficient. Practical use of SrZrO 3 is limited by poor mechanical strength relative to ceramics such as alumina (Al 2 O 3). Sintering of SrZrO 3 with a hydratable Al 2 O 3 binder is investigated as a method for improving mechanical performance. Density, phase composition, thermomechanical properties, and chemical stability in contact with alloys up to 1350 °C are considered. Results are compared with SrZrO 3 samples formed using a traditional polyvinyl alcohol (PVA) binder. SrZrO 3 reacts with alumina during sintering to form SrAl 2 O 4 and ZrO 2. Compared to the PVA binder, the alumina binder drastically reduced porosity in the ceramic, while increasing the indirect tensile strength and fracture toughness. No significant detriment to thermal expansion or chemical stability was found, offering potential for high-temperature applications particularly as a dense crucible material. [ABSTRACT FROM AUTHOR]

In order to mitigate the rapid grain growth, a sintered ferrite magnet exhibiting stable characteristics was successfully synthesized. M-type strontium ferrite Sr 1- x Sm x Fe 12- x Co x O 19 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.10) was synthesized via a low-temperature co-firing method, incorporating an appropriate quantity of Bi 2 O 3 and CuO as additives within the solid-phase reaction process. The magnetic and electrical properties of the resulting composites were meticulously examined, and X-ray diffraction (XRD) analysis was performed for structural characterization. The findings reveal that a pure hexagonal strontium phase is achieved consistently when the substitution level, x , remains below 0.5. With an increase in the substitution level, a heterogeneous phase α-Fe 2 O 3 becomes apparent within the phase structure. Upon introducing doping elements, the subtle incorporation of SmCo (x ≤ 0.02) enhances the saturation magnetization, remanent magnetization, and coercivity of the composite material. Moreover, the resistances of grain and grain boundary (Rg, Rgb) have been downscaled from 1.856 × 106Ω and 3.61 × 106Ω to 3.182 × 104Ω and 4.37 × 105Ω respectively. Consequently, the Sr 1- x Sm x Fe 12- x Co x O 19 ferrite sintered under low-temperature conditions demonstrates outstanding electromagnetic characteristics, presenting a viable option for materials in microwave device applications. [ABSTRACT FROM AUTHOR]

In this work, strontium hexaferrite (SrFe 12 O 19) with partial substitutions of aluminum and calcium (Sr 0·67 Ca 0·33 Fe 8 Al 4 O 19) and hexaferrite with partial substitutions of manganese (SrMnFe 11 O 19) were synthesized by the polymeric complex method (Pechini). The samples were calcined at a temperature of 1000 °C for 4 h. The crystalline phases, structure, and morphology of the samples were determined by X-ray diffraction, scanning electron microscope, and transmission electron microscopy. The magnetic properties were measured at room temperature using a vibrating sample magnetometer with an applied field of up to 20 kOe. The point of zero charge was determined by measuring the zeta potential. Finally, for adsorption experiments, the concentration of Pb (II) in the samples was determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The results show that the sample with partial manganese substitutions (SrMnFe 11 O 19) exhibits the highest removal of pollutants (Pb2+) with a maximum adsorption capacity of 24.23 mg/g. [ABSTRACT FROM AUTHOR]

The high-entropy oxide (HEO) Sr(Ce 0.05 Sn 0.08 Zr 0.2 Ti 0.16 Y 0.3 Nb 0.11 Al 0.1)O 2.9 with a significant B-sublattice cation size deviation, was predicted by thermodynamic approach and synthesized via a conventional solid-state route at 1500–1600 °C. The thermodynamic findings revealed an energy minimum at 623 °C, influencing the stability of the HEO. These insights highlight the temperature limitations for synthesis (<1623 °C) and underscore the impact of the composition on overall stability. Microstructure analysis demonstrates reactive sintering, resulting in a dense (90–93 %) low-porosity sample. EDS and mapping reveal uniform dispersion cations with minimal Ce 0.86 Y 0.14 O 1.93 impurity grain formation. The stability of the perovskite-like structure was assessed based on factors such as tolerance factor, new tolerance factor, and deviations of sizes, valences, and electronegativity of metals in the B-sublattice. Despite significant deviations in cation radii, the HEO perovskite structure was still formed, showcasing the role of valence combinations in stabilizing the structure. The achieved mechanical properties, such as acceptable hardness value 5.6 ± 0.1 GPa and high fracture toughness coefficient 3.47 ± 0.22 MPa m1/2 result from high lattice distortions. These findings shed light on the complex behavior and properties of high-entropy oxides, providing insights into their synthesis, structure, and mechanical attributes. [ABSTRACT FROM AUTHOR]

The present work conducts the synthesis, thermal, optical, and magnetic characterization of (60-x)B 2 O 3 +20Li 2 O+20SrF 2 + x Nd 2 O 3 where x = 0, 0.5, 1, 1.5, 2 mol% glass samples. The samples were investigated via X-ray diffraction (XRD), Raman spectroscopy, differential scanning calorimetry (DSC), UV–Vis absorption spectroscopy, and vibrating sample magnetometry (VSM). XRD patterns for borate strontium fluoride glass samples doped with Nd 2 O 3 showed broad humps around 30 and 43°, indicating their amorphous structure. Raman spectra of glass samples indicated that as Nd3+ ions were added to the host matrix, there was an increase in Raman intensity due to bond breakdown and the development of more non-bridging oxygen (NBO) species. The DSC data of the borate strontium fluoride glass samples doped with Nd 2 O 3 demonstrated that the glass transition temperature (T g) generally increased. UV–Vis absorption spectra showed transitions in Nd3+ ions doped borate glasses that are associated with the bands at different wavelengths, attributed to 4G 5/2 +2G 7/2 , 2H 11/2 , 4F 9/2 , 2H 9/2 +4F 5/2 , and 4F 3/2. The refractive index of borate strontium fluoride glass samples doped with Nd 2 O 3 increased. The saturation magnetization values decreased from 0.9 to 0.29 upon increasing the Nd 2 O 3 percentage (0–2 mol%). These low saturation magnetization glass samples can be used in spintronic devices to effectively reduce switching current density and lower the damping constant. [ABSTRACT FROM AUTHOR]

• Sr isotopes prove valuable in illegal timber investigations. • Pilot study reveals Sr isotope signatures in Brazilwood. • Challenges and promises in Sr isotope timber provenance. • Method ruled out questioned samples' origin in Brazilwood National Park. The illicit exploitation of Brazilwood (Paubrasilia echinata) presents a significant challenge in Brazil, given its substantial value in the global production of bows for musical instruments. To address timber provenance, the use of strontium (Sr) isotope ratios as indicators of bedrock signatures has emerged as a robust tool in forensic investigations. In this study, we critically evaluate the efficacy of this approach using Sr isotope data derived from bulk soils and trees collected at two distinct sites in Brazil. Despite the statistically indistinguishable 87Sr/86Sr ratios observed in the investigated tree species, the compiled 87Sr/86Sr isotope ratios of Brazilwood from Brazilwood National Park (PNPB) and the ES Group provide valuable insights into the potential application of this method for tracing forensic timber seizures. This pilot study also addresses crucial sampling considerations. While the regional signatures exhibit clear distinctions, the limited sample sizes underscore the necessity for supplementary methods to confidently attribute timber to a specific source forest. In isolation, this method proves most effective in refuting presumed timber provenances rather than definitively confirming them. The discussion delves into the nuances of the Sr isotope data, emphasizing the importance of increasing the number of samples and exploring complementary techniques for a more comprehensive and reliable assessment of timber origin. [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]

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]

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]

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]

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]

• The addition of at least 0.25 at.% Sr to Mg–Zn–Y alloys increased ignition temperature. • A thin and uniform Y 2 O 3 film formed on Mg–Zn–Y alloys containing at least 0.25 at.% Sr. • Sr was enriched in the Y 2 O 3 film and an outer protective MgO+SrO film was formed. • Strong compressive stresses acted on both MgO and SrO in the MgO+SrO film. Mg 97 Zn 1 Y 2 alloys with high ignition temperatures were developed by adding Sr. The addition of Sr resulted in the formation of a uniform and thin Y 2 O 3 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 Y 2 O 3 film. In addition, a mixed film of MgO and SrO formed on the outer layer in the 1.5 at.% Sr-containing Mg 97 Zn 1 Y 2 alloy. These findings suggest that the uniform and thin Y 2 O 3 film that maintains high soundness at high temperatures was formed owing to valence control and the formation of a protective outer oxide film. [ABSTRACT FROM AUTHOR]

High entropy materials offer optimal conditions for regulating and modifying new material properties due to their vast composition space. Through traditional solid phase sintering, this article successfully synthesized a series of Sr(Ti 0.2 Zr 0.2 Y 0.2 Sn 0.2 Hf 0.2 Sc 0.2x)O 3-σ high entropy perovskite oxides with varying Sc3+ doping concentrations and comprehensively investigated the microstructure morphology, crystal structure, and electrical conductivity of Sc-doped HEPs as well as their influence on oxygen transfer rate. The results demonstrate the successful incorporation of Sc3+ into the high entropy lattice, resulting in a transformation of the crystal to a positively cubic structure with enhanced reciprocity. While the lattice vibration of BO 6 octahedron is weakened by the introduction of Sc3+, it has no impact on the phase stability of the crystal structure. Moreover, The results of the electrochemical impedance spectroscopy test demonstrate that at a temperature of 750 °C, with a doping amount of Sc3+ at 0.14, the conductivity (σ) of Sc3+ is measured to be 5.74 × 10−3 S/cm, exhibiting an increase of 61.7% compared to non-doped samples. Correspondingly, the activation energy (Ea) is reduced from 0.51 eV to 0.39 eV as well. This doping strategy effectively expands the potential applications of high entropy perovskite oxides in solid oxide fuel cells (SOFCs). These findings serve as a driving force for further investigation into high entropy ceramics of the strontium series that exhibit optimal properties. [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]

Trace element detection and mapping are key capabilities of the Planetary Instrument for X-ray Lithochemistry (PIXL) on board the Mars 2020 rover Perseverance. However, poor signal-to-noise ratios due to the short integration times required to make high-spatial-resolution map scans operationally feasible raise the possibility of misidentifying statistical noise as a signal from a trace element, which can cause many false detections of a trace element among the hundreds to thousands of data points in each PIXL scan. Here, we apply a statistical technique to quantify the likelihood of such misidentifications and determine what concentration of a trace element must be present to reach statistical confidence in a detection. This approach is anticipated to be applicable both when analyzing existing PIXL data to ensure that noise is not misinterpreted as signals from trace elements and operationally to inform scan parameters when trace elements of interest are anticipated to be present. • M2020 Perseverance PIXL statistical trace element detection confidence is presented • PIXL detection limits for cerium, strontium, and other elements are quantified • Factors influencing trace element detection limits are investigated [ABSTRACT FROM AUTHOR]

• Sr-Al-Ce pigment was prepared via the sol-gel method. • The formulations were based on VEOVA and Styrene acrylic with the prepared pigment. • New pigment based on Al-Si doped with traces of Ce was prepared. • Physical and antimicrobial properties of the treated pottery were tested. • The prepared formulations offered good consildating properties to the pottery. After being buried in the soil for long periods exceeding thousands of years, archeological pottery showed many phases of deterioration leaving them with extreme impairment. Polymeric coatings are the traditional consolidants which can be used in the improvement of many of these discovered artifacts. Many of the used polymers can offer good protection performance, but this is accompanied with some problems; such as low stability with chromatic changes and wetting-drying cycles. The process of reinforcing the polymeric coating with functional pigments can enhance their performance in providing advanced functions to the consolidated coatings. In this work, polymers of styrene acrylic and VEOVA were integrated with inorganic pigment of strontium aluminate doped with traces of cerium to add-valued properties to the polymeric mixture and provide modified mechanical and anti-microbiological protection for the pottery artifacts. Different techniques were used to evaluate the effect of the prepared formulations such as their color change index, porosity, compressive strength, digital and scanning microscope besides the antimicrobial effects. The results showed that styrene-acrylic polymer integrated with the prepared strontium aluminate pigment was better in its protection and consolidating properties than that of VEOVA. [Display omitted] [ABSTRACT FROM AUTHOR]

Anti-inflammatory drug pollution and its potentially disastrous consequences have recently emerged as a major health issue worldwide because of its widespread use in inadequate environments. Among, Flufenamic acid (FFA) is a class of anti-inflammatory drugs widely used for therapeutic treatments, and its over usage causes severe issues in the biological systems. In this work, a particle– like strontium phosphate (Sr 2 P 2 O 7) was prepared. The efficiency was increased by making a composite with functionalized carbon nanofiber (F-CNF) and used to detect FFA. The prepared individual materials (Sr 2 P 2 O 7 and F-CNF) and the composite (Sr 2 P 2 O 7 @F-CNF) were confirmed by various spectroscopy techniques. The electrochemical studies of Sr 2 P 2 O 7 @F-CNF were done by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A sensitive i-t amperometry technique was used for the determination of FFA. The attained results show that Sr 2 P 2 O 7 @F-CNF shows a higher active surface area (A= 0.197 cm2), a wide linear range of 0.001–80.8 µM, a low detection limit of 0.9 nM, and higher selectivity. Finally, the Sr 2 P 2 O 7 @F-CNF was taken to the real-time analysis with the water and urine samples. The result shows an acceptable recovery range of ± 97.50–99.66 % for the water and urine samples. [Display omitted] [ABSTRACT FROM AUTHOR]

M-type strontium (SrM) hexaferrites exhibiting large magnetocrystalline anisotropy, high saturation magnetization and coercivity, and narrow ferrimagnetic resonance (FMR) linewidth have a great potential for applications in high-performance motors and self-biased circulators. Ca doping in SrM hexaferrites is an effective method for tailoring the intrinsic electromagnetic parameters and modifying polycrystalline microstructure to meet the application requirements. However, the regulation mechanism of Ca doping is still obscure, and its regulation effect is not optimized. Here, the magnetic and electrical properties of SrM hexaferrites with site-controlled two-step Ca doping are reported. The spatial concentration distribution and diffusion dynamics of Ca2+ ions are investigated when introduced by CaCO 3 as the reactant and sintering additive, respectively. The existence of the Ca2+ ions in the crystallites added as the reactant reduces the diffusion of the Ca2+ ions in the grain boundaries added as the additive, which synergistically tailors the magnetocrystalline anisotropy field, crystallite orientation, and polycrystalline morphology, and further optimizes the coercivity, remanence, and maximum energy product. Moreover, the impact of the Ca2+ ions on the resistivities of the grain and grain boundary is also investigated, revealing the synergetic effect of Ca2+ ions at different sites on lowering the loss. These results prove the effectiveness of the site-controlled two-step Ca doping in synergistically enhancing the magnetic and electrical properties of SrM hexaferrites. [ABSTRACT FROM AUTHOR]

Rare earth ion substitution is one of the most important methods for adjusting the magnetic properties of M-type hexagonal ferrites; however, the regularity of these phase formations has rarely been studied. In this work, La substituted Sr hexaferrite La x Sr 1- x O· n Fe 2 O 3 (La-SrM, 4.9 ≤ n ≤ 6.0, 0 ≤ x ≤ 0.6) was prepared using the traditional ceramic method. The effects of the Fe/Sr molar ratio (n), calcining temperature, and La3+ substitution (x) on SrM phase formation, the crystalline structure, and magnetic properties were investigated. With an increase of x up to a maximum value of 0.5–0.6, a higher calcining temperature is required to form the single M-phase of La-SrM samples. However, the optimal n values of single-phase La-SrM samples differ as the La substitution varies: when x = 0.1, n = 5.5–6.0; x = 0.2, n = 5.5–5.9; x = 0.3, 0.4 and 0.5, n = 5.7–5.8. The magnetic measurements show that La 0.2 Sr 0.8 O·5.8Fe 2 O 3 has the highest specific saturation magnetization (σ s), which is 2.2% higher than that of unsubstituted SrM (SrO·6Fe 2 O 3), while the anisotropic field (H A), the anisotropic constant (K 1), and Neel point (T N) of La3+ substituted SrM decreased. Detailed structure analyses were conducted to explain the changes in magnetic properties. Fe3+ in the spin-up 2 a sublattice of La x Sr 1- x O·5.8Fe 2 O 3 decreased by approximately 5% from 98.5% (x = 0) to 93.85% (x = 0.4) with an increase in x. Additionally, a small amount of Fe3+ was reduced to Fe2+ in the spin-down 4 f 2 sublattice with the maximum reduction amount of 4.13% reached at x = 0.2, thereby improving σ s. The decrease in the bond angle of (4 f 1) Fe3–O2–Fe5 (12 k), (2 a) Fe1–O4–Fe3 (4 f 1), and (4 f 1) Fe3–O4–Fe5 (12 k) lead to the weakening of Fe–O–Fe superexchange of La-SrM so that H A , K 1, and T n decreased with increasing values of x. This work lays a solid foundation for the study of process regulation and ion substitution of permanent magnet ferrite. [ABSTRACT FROM AUTHOR]

Magnesium phosphate-based cements (MPCs) are nowadays regarded as promising materials in the field of bone repair. The inclusion of Sr ions in the formulations may represent a valuable strategy to improve their bone regeneration performances, but the effect that such ion exerts on the physico-chemical properties of the material have not been investigated so far. In this work we describe the development of Sr-MPCs obtained including Sr ions in different forms, i.e., using Sr-substituted tri-magnesium phosphate precursor powder or including in the formulation Sr-based salts (SrCl 2 and SrHPO 4). The materials were characterized both in the form of pastes and hardened cements, finding that according to the type of Sr precursor used we can tune the setting time, the amount of binding phases in the cements, their morphology and thermal behavior. The dissolution behavior and the release kinetics of Mg2+ and Sr2+ can as well be modulated, and in particular the use of SrCl 2 in the formulation leads to a higher dissolution and a faster release of a significant amount of both Mg2+ and Sr2+, compared to the other samples. Given the unsatisfying performances obtained during the injectability and anti-washout tests, we also included two polymeric additives, namely poly(N-isopropylacrylamide) and mucin, in the Sr-MPCs formulations. The results demonstrate that it is possible to obtain Sr-MPCs with promising properties for applications as bone cements, that can be tuned according to the form under which Sr is included in the formulation. In addition, mucin markedly improves the cohesion and injectability of the Sr-MPC pastes, providing a simple but effective strategy to develop materials of interest in the orthopedic field. [ABSTRACT FROM AUTHOR]

Whilst strontium (Sr2+) is widely investigated for treating osteoporosis, it is also related to mineralization disorders such as rickets and osteomalacia. In order to clarify the physiological and pathological effects of Sr2+ on bone biomineralization , we performed a dose-dependent investigation in bone components using a 3D scaffold that displays the hallmark features of bone tissue in terms of composition (osteoblast, collagen, carbonated apatite) and architecture (mineralized collagen fibrils hierarchically assembled into a twisted plywood geometry). As the level of Sr2+ is increased from physiological-like to excess, both the mineral and the collagen fibrils assembly are destabilized, leading to a drop in the Young modulus, with strong implications on pre-osteoblastic cell proliferation. Furthermore, the microstructural and mechanical changes reported here correlate with that observed in bone-weakening disorders induced by Sr2+ accumulation, which may clarify the paradoxical effects of Sr2+ in bone mineralization. More generally, our results provide physicochemical insights into the possible effects of inorganic ions on the assembly of bone extracellular matrix and may contribute to the design of safer therapies for treating osteoporosis. Physiological-like (10% Sr2+) and excess accumulation-like (50% Sr2+) doses of Sr2+ are investigated in 3D biomimetic assemblies possessing the high degree of organization found in the extracellular of bone. Above the physiological dose, the organic and inorganic components of the bone-like scaffold are destabilized, resulting in impaired cellular activity, which correlates with bone-weakening disorders induced by Sr2+. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of novel bioactive materials with improved physical and biological properties is crucial for advancing tissue engineering applications. In this study, we synthesized a Vanadium and Strontium co-doped hydroxyapatite (V–Sr:HAp) nanoparticle intending to enhance the performance of pure HAp. The V–Sr:HAp nanoparticles were synthesized using a microwave-assisted reflux condensation method, and their structural and chemical characteristics were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The morphology and elemental composition of the nanoparticles were examined through scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The XRD analysis confirmed the presence of characteristic peaks of HAp in each sample. SEM images revealed well-connected and highly agglomerated small sphere-like morphology in both pure HAp and V–Sr:HAp nanoparticles. The Vickers hardness test demonstrated the improved mechanical strength in V–Sr:HAp compared to pure HAp. Antibacterial efficacy was evaluated using an agar diffusion test, which showed enhanced antibacterial activity in the co-doped HAp samples against S. aureus and P. aeruginosa. Moreover, the Ca–P deposition rate on the surface of the co-doped HAp samples during biomineralization was higher. Hemolysis assay results have indicated compatibility of both pure HAp and V–Sr:HAp with human blood (<5% lysis). The results of cell viability tests demonstrate that the V and Sr co-doped HAp samples do not exhibit any cytotoxic effects and instead promote cell proliferation. Overall, the incorporation of V and Sr metal ions into HAp presents a promising bio-functional tool for tissue engineering applications, offering improved mechanical and antibacterial properties. [ABSTRACT FROM AUTHOR]

Double substitution of strontium hexaferrite by calcium and aluminum leads to a tremendous rise of hard magnetic properties, such as coercivity and natural ferromagnetic resonance frequency (NFMR). However, the properties are also inextricably linked to the material microstructure (especially, particle size), to the solid solution inhomogeneity as well as aluminum ions distribution among iron sites in crystal structure. In this work, we obtained M-type hexaferrite particles Sr 1- x /12 Ca x /12 Fe 12- x Al x O 19 (x = 4–6) via a facile citrate-nitrate auto-combustion method and studied the influence of the annealing temperature in a broad range on the microstructure, features of crystal structure and hard magnetic properties. At low annealing temperatures (900–1000°С) hexaferrite nanoparticles with 90% of nominal Al content and a wide chemical distribution are formed. Next, with an increase in the annealing temperature the distribution significantly narrows, chemical composition becomes close to the nominal one and particles size transfer firstly to submicron, then to micron range. The aluminum distribution over iron sites is independent distinctly on the annealing temperature. For all the compositions single domain particles with the maximum coercivity values between 22.8 and 36 kOe are obtained at 1200 °C. At 900–1000 °C the samples demonstrate coercivities up to 25 kOe, while above 1300 °C, the crystallites begin to pass into a polydomain state with a reduced coercivity. The hexaferrites with narrow chemical distribution reveal resonance absorption in sub-terahertz band. The highest NFMR frequency of 270 GHz was observed for x = 5.5 sample annealed at 1400 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] Recent advances in osteoimmunology have led the focus on the immunomodulatory design of metal–organic framework (MOF)-based porous materials for encouraging bone repair by influencing the immune microenvironment using implanting biomaterials. Despite the growing interest in porous materials, few research studies have been done on how extracellular Sr2+ and Ca2+ loaded in MOFs leads the organism toward optimal osteogenesis. In this study, in vitro evaluations showed that both Sr2+ and Ca2+ nanoparticles have a dual effect, stimulating matrix secretion by osteoblasts while suppressing matrix resorption by osteoclasts. Sr2+ significantly increased RUNX2 transcriptional activity and phosphorylation in gene expression evaluation. On day seven, hBMSC cells on HKUST-1@CaNPs/SrNPs showed a significant increase in collagen gene expression compared to HKUST-1@CaNPs/SrNPs@PEG, indicating a high level of proliferation and differentiation. At the same time, the HKUST-1@SrNPs hBMSC cells expressed the RUNX2 gene at a much higher level than the other groups. ALP activity was measured on days 7 and 14 of culture to see how it compares to more extended incubation periods. As the culture time for HKUST-1@SrNPs and HKUST-1@CaNPs/SrNPs was extended from 7 to 14 days, the ALP activity was shown to rise. Findings indicated that HKUST-1@CaNPs/SrNPs improved hBMSC osteogenic differentiation potential. In conclusion, HKUST-1@CaNPs/SrNPs could show promising results for bone tissue engineering. [ABSTRACT FROM AUTHOR]

The complex oxide Sr 1·95 Fe 1·4 Ni 0·1 Mo 0·5 O 6–х–δ (F х), where х = 0, 0.1, 0.2 and 0.3, as one of the most promising materials for electrodes of symmetrical electrochemical devices based on solid electrolytes is studied. The unit cell parameter increases monotonically with the addition of the fluorine–containing precursor in the synthesis of materials. The absence of fluorine traces in the sintered oxides was reliably confirmed by a combination of potentiometry using a fluorine–selective electrode and i n situ mass spectrometry analysis of the gas media formed during heating the synthesized powders. It is suggested that the use of a fluorine–containing precursor makes it possible to increase the concentration of oxygen vacancies in the oxide, which positively affects its functional characteristics, such as the oxygen exchange rate with the gas phase and the oxygen electroreduction rate. [Display omitted] • Sr 1·95 Fe 1·4 Ni 0·1 Mo 0·5 O 6–х–δ (F х) are synthesized using strontium fluoride at 1100 °C. • Mass spectrometry and fluorine–selective potentiometry show the absent of fluorine. • The enhancement in rates of interfacial oxygen exchange and ORR is found. [ABSTRACT FROM AUTHOR]

Surface oxygen exchange in the La 2 NiO 4+δ and La 1.5 Sr 0.5 Ni 1- y Fe y O 4+δ (y = 0.3, 0.4) oxides is analyzed using the data on oxygen permeability through the membranes with different thicknesses measured under various oxygen partial pressure P (O 2) gradients in the 800–1000 °C range. The increase in P (O 2) gradient induced surface limitations in La 2 NiO 4+δ leading to a predominant role of surface exchange in the overall oxygen flux. The origin of surface exchange limitations in La 2 NiO 4+δ is ascribed to a relatively fast decrease in oxygen excess and Ni3+ concentration with P (O 2) reduction compared to La 1.5 Sr 0.5 Ni 0.7 Fe 0.3 O 4+δ and La 1.5 Sr 0.5 Ni 0.6 Fe 0.4 O 4+δ , which retained an oxygen excess. Faster surface exchange kinetics for La 1.5 Sr 0.5 Ni 0.6 Fe 0.4 O 4+δ in comparison with that for La 1.5 Sr 0.5 Ni 0.7 Fe 0.3 O 4+δ is interpreted on the basis of surface microstructure obtained by electron backscatter diffraction (EBSD). It is suggested that the observed changes in size, shape and crystallographic orientation of grains in La 1.5 Sr 0.5 Ni 0.6 Fe 0.4 O 4+δ (compared to La 1.5 Sr 0.5 Ni 0.7 Fe 0.3 O 4+δ) could result in a higher amount of 3 d -metal cations in surface layers of the oxide. • Surface exchange limitations in La 2 NiO 4+δ correlate with bulk Ni3+ concentration. • Fe doping in La 1.5 Sr 0.5 Ni 1-y Fe y O 4+δ affects orientation of crystallites. • Increase in number of (001) faces with Fe doping can facilitate surface exchange rate. [ABSTRACT FROM AUTHOR]

Perovskites based on lanthanum-strontium ferrite are considered promising electrode materials for use in various types of fuel cells. The strategy of modifying these materials by partial substitution of iron with highly charged ferroactive cations has proven to be an effective way to enhance their chemical stability. It was shown here that La 0.5 Sr 0.5 Fe 1−x Nb x O 3−δ forms a continuous series of substitutional solid solutions up to niobium concentration x = 0.1. It was found for the first time that a further increase in the niobium concentration leads to a transformation of initial rhombohedral (hexagonal) perovskite structure (R 3 ‾ c) to less symmetrical structure of orthorhombic perovskite (Pbnm). The latter also forms a number of substitutional solid solutions in the range 0.1 < x ≤ 0.25. High-temperature diffraction analyses of perovskites of composition La 0.5 Sr 0.5 Fe 1−x Nb x O 3−δ (x = 0.03, 0.05, 0.1) were carried out in the air atmosphere and in vacuum. It was demonstrated that with an increase in the Nb content in the perovskite, the temperature of the "hexagonal-cubic" phase transition goes up, which indicates an increase in the structural stability of the oxide in the range of operating temperatures of SOFCs/SOECs. [Display omitted] [ABSTRACT FROM AUTHOR]

The morphology of bioactive glass nanoparticles has been reported to impact apatite-forming ability, biocompatibility, and cell functions. In this study, mesoporous bioactive glass nanoparticles (MBGNs) of mixed morphologies with nominal compositions (%mol) given by 74Si O 2 _ (26 − x) C a O _ x S r O , (where x = 0,1,3 , a n d 5) were prepared through a modified sol-gel method. The MBGNs were characterized by thermal gravimetric analysis (TGA), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), N 2 adsorption/desorption, X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). In particular, the effect of Sr concentration on the glass structure, surface morphology, particle size, microstructure, chemical durability, ion release, and in vitro mineralization on the MBGNs was studied. All compositions showed similar thermal degradation profiles irrespective of Sr concentrations. SEM observation showed a mixture of aggregated spherical- and rod-shaped particles in which particle sizes decreased with increasing Sr concentration. Textural analysis showed a decrease in specific surface area with increasing Sr concentration. NMR analysis revealed a reduction in glass network polymerization with increasing Sr concentration. NMR analysis showed hasty depletion of modifier cations from the MBGNs to the simulated body fluid (SBF), the effect more prominent in the pristine sample. We observed prompt surface modifications on MBGNs as a response to their interaction with SBF that led to interconversion of 29Si speciation in the order Q C a , S r 1 + Q C a , S r 2 → Q H 2 → Q H 3. SEM, EDX, and XRD revealed the formation of crystalline hydroxyapatite (HA) on the MBGNs after three days of immersion in SBF. In vitro apatite-forming ability of MBGNs decreased with increasing Sr concentration. The MBGNs revealed promising potential properties for applications in orthopedics, dentistry, wound healing, and drug delivery systems. [ABSTRACT FROM AUTHOR]

A commercial composite powder was used to develop a new paste for stereolithography processing (SLA) of dense 11Ce-TZP-based composites containing 8 vol.% of alumina and 8 vol.% of strontium aluminate. The same powder was used to prepare reference ceramics by conventional Cold Isostatic Pressing (CIP) and sintering. The use of SLA gave rise to a microstructure containing larger strontium aluminate clustering surrounded by zirconia grains devoid of alumina particles, which appeared embedded in a matrix of zirconia-alumina grains. This slightly more heterogeneous microstructure favoured the formation of a greater number of thinner transformation bands, causing a larger plastic deformation in SLA samples (failure strain of 0.65 % instead of 0.35 % for CIP samples), without compromising characteristic strength ( σ 0 = 560 and 586 MPa respectively). Thus, SLA does not affect the ductile behaviour that characterizes this type of ceramics and appears as a very promising method for the development of custom-made ceramic prostheses. [ABSTRACT FROM AUTHOR]