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Textured ceramics are generally fabricated by reactive-templated grain growth using a template material with a suitable anisotropy and topochemical relationship to the target ceramics. We have previously synthesized hexagonal plate-like α-tristrontium phosphate (α-Sr3(PO4)2; α-TSP) single crystals with no topochemical relationship to the apatite system. In the present study, we focused on using the facets of α-TSP particles as nucleation sites for textured apatite, and fabricated <001>-oriented strontium fluoroapatite (Sr10(PO4)6F2; SrFAp) through a reaction between aligned α-TSP platelets and SrF2. The SrFAp phase was formed with a preferred c-axis orientation at 900°C. Sintering in an F-containing atmosphere led, moreover, to fabrication of textured SrFAp ceramics with a high ratio of conversion into apatite. In this way, textured polycrystalline ceramics with no topochemical relationship to the template material can be fabricated through reactive-templated grain growth using the facets of the template particles as nucleation sites. [ABSTRACT FROM AUTHOR]

Nanocrystalline Ba 0·6 Sr 0·4 Co 0·8 Fe 0·2 O 3 (BSCF-6482) powder is synthesized by combustion synthesis technique. Powder calcined at 1000 °C reveals phase pure cubic perovskite. Transmission electron microscopic (TEM) analysis exhibits soft agglomerates of average size ∼50 nm wherein interplanar spacing for (110) and (221) resembles to the cubic lattice. While DC electrical conductivity of 23 S cm−1@800 °C is observed, interfacial polarization measured by electrochemical impedance spectroscopy is found to be the least @850 °C (0.18 Ω cm2). Cell performance has been compared among BSCF-6482, BSCF-5582 and LSCF-6482 mixed ionic and electronic conducting (MIEC) and conventional electrode (LSM). Higher performance (1.37 A/cm2@1.3 V,800 °C) with high hydrogen generation rate (0.57 Nl/cm2/h) is found during steam electrolysis with cell fabricated using BSCF-6482 having minimal area specific resistance 0.33 Ω cm2. Under similar operating condition, BSCF-5582, LSCF-6482 and LSM exhibit hydrogen generation rate of 0.35, 0.28 and 0.23 Nl/cm2/h respectively. Cell microstructure is clinically correlated with the higher reactivity of BSCF-6482 air electrode in steam electrolysis. • Nanocrystalline Ba 0·6 Sr 0·4 Co 0·8 Fe 0·2 O 3 (BSCF-6482) is synthesized by autocombustion. • Interfacial polarization for BSCF-6482 reveals 0.18 Ω cm2@850 °C. • Higher C.D. 1.37 A/cm2@1.3 V,800 °C than MIEC electrodes (BSCF-5582 & LSCF-6482). • Superior hydrogen flux for BSCF-6482 (0.57Nl/cm2/h) than MIEC and LSM electrodes. • Microstructural integrity retained for BSCF-6482 at high cell current. [ABSTRACT FROM AUTHOR]

To date, geopolymer has emerged as a promising and inexpensive precursor with potential application in trapping hazardous elements via physical encapsulation or chemical bonding. In this work, different high‐temperature products derived from Sr‐contained geopolymer precursors were prepared. Different to conventional hazardous elements that immobilized in the geopolymer precursor, which show decreasing leaching rates after high‐temperature treatments, leaching rates of Sr in the resulting high‐temperature products first increase and then decrease with the increasing heating temperature. Herein, we first shed light on the underlying reasons of such temperature‐dependent leaching behaviors by investigating effects of heating temperature on the phase composition, microstructure, and immobilization mechanism. Moreover, a novel immobilization strategy has been proposed based on the blocking effect of formed nepheline structures at 1200°C. Using this strategy, the leaching rate of Sr reduced to 5.82 × 10−7g cm−2 d−1 in the deionized water. [ABSTRACT FROM AUTHOR]

By introducing alkaline-earth metal ions (Mg2+, Ca2+, and Sr2+) as structure-directing agents, three new heterometallic complexes, Mg(H2O)6·[Cu2Mg(L)4(H2O)4]·4H2O (1), [CuCa(L)2(H2O)4]n (2) and [CuSr(L)2(H2O)4]n (3) [H2L = 4-(3-(pyridine-4-yl)-1H-1,2,4-triazol-5-yl)picolinic acid], have been synthesized under hydrothermal conditions and structurally characterized. H2L was in situ generated from hydrolysis of the well-known selective xanthine oxidase inhibitor topiroxostat. Complex 1 crystallizes in the space group P21/c and exhibits a zero-dimensional (0-D) structure containing the discrete [Mg(H2O)6]2+ cationic and [Cu2Mg(L)4(H2O)4]2– dianionic moieties. Complexes 2 and 3 are isostructural and crystallize in the space group C2/c, with one-dimensional (1-D) polymeric structure with infinite Cu(II)–Ca/Sr–carboxylate chains. The results reveal the significant influence of the alkaline-earth metal ions on the molecular structure. Their spectroscopic, thermal and solid-state luminescent properties have also been investigated. [ABSTRACT FROM AUTHOR]

The synthesis and photo-luminescence properties of Eu2+/Eu3+ or Ce3+/Eu3+ co-doped Sr 5 (BO 3) 3 F compounds are reported. Using the Sr 5 (BO 3) 3 F as the host, through the solid state reaction under the reductive atmosphere, Eu2+/Eu3+ and Ce3+/Eu3+co-doped samples were prepared. These compounds exhibit good photo-luminescence properties. Under the excitation of 376 nm, an unusual red orange emission coming from the Eu2+ ions can be obtained in Eu ions doped Sr 5 (BO 3) 3 F, which exhibits a broadband emission in the range of 450–800 nm with the peak at around 600 nm. At the same time, the characteristic f-f excitation and emission of Eu3+ can improve and adjust the Eu2+ emission in Eu3+/Eu2+ codoped Sr 5 (BO 3) 3 F. In addition, the adjustable luminescence properties from blue to white of Sr 5 (BO 3) 3 F:Ce3+, Eu3+ are investigated. The energy transfer behavior from Ce3+ to Eu3+ was confirmed. In the spectra of the co-doped samples, we can hardly observe the characteristic peak of Eu2+, because Ce4+ can oxidize Eu2+ to Eu3+, and Ce4+ itself is reduced to Ce3+. The CIE coordinates from (0.2758, 0.2420) to (0.3857, 0.3015) show Sr 5 (BO 3) 3 F:3%Ce3+, x%Eu3+ (x = 1,3,5,7,9) are in the white light emission region. All results demonstrate that the Sr 5 (BO 3) 3 F:Eu3+/Eu2+ and Sr 5 (BO 3) 3 F:Ce3+/Eu3+ phosphors have good application prospects for LED plant growth and white LED, respectively. The bond energy method was used to explain the reason why the Eu2+/Eu3+ ion instead of only Eu2+ and Ce3+/Eu3+ instead of Ce3+/Eu3+/Eu2+ can exist in the host Sr 5 (BO 3) 3 F. The theoretical analysis agree well with the experimental result. [ABSTRACT FROM AUTHOR]

A biomimetic method was used to improve bioactivity of Sr2SiO4. Strontium silicate was obtained by using a combination of techniques such as mechanical activation and reactive sintering, of a powder mixture of strontium carbonate and silicon dioxide. Single phase Sr2SiO4 was obtained after 6 h of mechanical milling of the starting reagents, followed by a uniaxial pressing and a thermal treatment in air at 1200 °C for 6 h. For the biomimetic treatment, samples were immersed in a simulated body fluid (SBF) for 7, 14 and 21 days on a bed of wollastonite powder and were characterized by SEM, EDS, XRD, FT-IR and TEM. For comparison purposes, experiments were also performed without using the bioactive powder bed. Results showed that a bone-like apatite layer was formed on strontium silicate after 21 days of immersion in SBF without a bed of wollastonite and slight layer of Ca, P-rich compound, using a bed of wollastonite powder, corroborating the viability of these oxides to be used as bioactive materials. [ABSTRACT FROM AUTHOR]

Glazes are the most important elements in the technology of producing the ceramic wares. They not only give aesthetic effects, like color and gloss, but also significantly contribute to the improvement of the functional properties of ceramic products. Improving the properties of glazes is a continuous task that is carried out in many research centers. This is also facilitated by the rapid development of research techniques and the development of more and more precise measuring devices. The presented work concerns the ordering of data on the role of selected alkaline earth metal oxides: barium, strontium and zinc oxides. To achieve the set goals, systematic test of samples was carried out. In the first step, characteristic temperatures were determined by means of using a high-temperature microscope and a mechanical dilatometer. Based on selected characteristic temperatures, the viscosity logarithm curves, as a function of temperature, were determined by means of the Vogel–Fulcher–Tamman equation. Next, the effects that occurred during thermal treatment in the temperature range 30–1230–400 °C were defined, by using differential scanning calorimetry techniques. The effect of selected oxides on the phase composition of samples after firing at 1230 °C was also determined. Obtained results allow drawing conclusions about significant differences between glazes modified with above-mentioned oxides and base glaze. Differences in the values of characteristic temperatures, the course of the viscosity curves as a function of temperature, various phase compositions and a description of the phenomena occurring during heating give full technological characteristics on the mentioned oxide modifiers of the properties of ceramic glazes. [ABSTRACT FROM AUTHOR]

The effect of the SrO addition on the microstructure and structure of the glazes from the SiO2–Al2O3–CaO–MgO–K2O system was investigated in this study. The results were obtained by testing the ability of the frits crystallization, the stability of the crystallizing phases during the single-step fast-firing cycle depending on their chemical composition and the effect of addition of strontium oxide. Differential scanning calorimetry (DSC) curves showed that all glazes crystallized, and diopside and anorthite were mainly identified as dominant phases in the obtained glazes, while the size and amount of each depended on the amount of SrO introduced. The thermal characteristic of the frits was carried out using DSC, and crystalline phases were determined by X-ray diffractometry. The glaze microstructure was investigated by scanning electron microscopy and transmission electron microscopy. Additional information on the microstructure of frits was derived from spectroscopic studies in the mid-infrared range. [ABSTRACT FROM AUTHOR]

Introduction: Osteoporosis is the most common metabolic bone disease. Aim: This study aimed to measure the utilization of drugs aff ecting bone structure and mineralization in Serbia from 2013 to 2016, and to compare this data with that from countries with well-developed pharmacotherapeutic practice, such as Finland, Norway, and Denmark. Methods: The utilization of drugs is estimated using the Anatomical Therapeutic Chemical/Defined Daily Dose (DDD) methodology. The amount of total drugs consumed has been expressed in the number of Defined Daily Dose on 1000 inhabitants per day (DDD/1000 inhabitants/day). Results: In 2016, a total of 2.91 DDD/1000 inh/day of all drugs was used in Serbia of which 75.26% belonged to bisphosphonates, whereas they made 37.15% in Finland, 81.56% in Norway and 77.84% in Denmark of the total utilization of M05 drugs subclass. The most frequently used bisphosphonate in Serbia in 2013 was alendronic acid, while in 2016 it was ibandronic acid. In three compared countries the rate of utilization among bisphosphonates was the highest for alendronic acid. The level of other bisphosphonates' utilization in Serbia, as well as the utilization of strontium ranelate, is constantly low compared to other drugs. In comparison to other countries, the utilization of denosumab in Serbia is multiple folds lower, however with an upward trend. Conclusions: The utilization of drugs aff ecting bone structure and mineralization in the examined period in Serbia compared to Finland, Norway and Denmark is three to six fold lower. Furthermore, there is a difference between the structure of prescribed and consumed drugs. [ABSTRACT FROM AUTHOR]

Strontium oxide nanoparticles (SrO NPs) were prepared using an eco-friendly bioreduction method utilizing a plant extract of Green cardamom (Elettaria cardamomum) as a reducing and capping agent (where 1, 8 cineole is the dominant reducing agent in this plant). The strontium oxide polythiophen core shell (SrO@PTh CS) nanocomposite was then prepared and utilized as plate form for graphite paste sensor (GPS) for determination of cilostazol. [Display omitted] • SrONPs were bio-synthesized utilizing Green cardamom extract. • SrO@PTh nanocomposite was prepared by in-situ oxidative polymerization of Th on the SrO surface. • SrO@PTh nanocomposite based sensor successfully detected cilostazol drug. • This sensor was applied in real samples. The green synthesis of metal or metal oxide nanoparticles utilizing plants is a novel promising approach in bio-nanotechnology. The strontium oxide nanoparticles (SrO NPs) were synthesized for the first time utilizing a plant extract of Green cardamom (Elettaria cardamomum) as a reducing and stabilizing agent. The strontium oxide polythiophene (SrO@PTh) nanocomposite was then prepared by in-situ oxidative polymerization of thiophene on the surface of SrO NPs using anhydrous FeCl 3 as an oxidant. FTIR spectrum indicates the coordination of SrO NPs with the binding sites along PTh backbone. TEM analysis resulted in an average particles size of (25 – 50 nm) for SrO NPs and core–shell nanostructure of its composite (SrO@PTh CS) with shell thickness of (20–90 nm). The XRD analysis indicates a crystalline cubic structure of SrO NPs with particles size of ≈ 45 nm in average and interplanar space of (0.24 ∼ 0.36 nm). The crystallinity was relatively diminished to some extent for SrO@PTh CS which exhibits a particle size of about 85 nm and interplanar space of (0.13 ∼ 0.23 nm). A smart and novel electrochemical graphite paste sensor (GPS), based on SrO@PTh CS nanocomposite, has been fabricated for the ultrasensitive in-vitro detection of antiplatelet drug cilostazol. SrO@PTh CS nanocomposite-based square-wave voltammetry biosensor exhibited the lowest limits of detection of 1.99 × 10−10 and 9.83 × 10−10 M for cilostazol drug determination in bulk and human plasma samples, respectively compared to all the reported methods. It exhibited also good reproducibility, repeatability, long-term stability and was free from biological interference effects. [ABSTRACT FROM AUTHOR]

[Display omitted] • Afterglow transparent smart wood with photochromism was prepared. • Lignin-modified wood was infiltrated with methyl acrylate and SrAl 2 O 4 :Eu2+,Dy3+. • Luminescent timber changed color from colorless in daylight to green in UV. • Absorption band was detected at 365 nm, and two emission bands at 436 and 517 nm. • Luminous wood provided superior UV protection and superhydrophobic activity. Smart windows that use photochromic colorless wooden materials are an intriguing and urgent area of research. Herein, we create afterglow transparent woods with UV-induced photochromic capability. Infiltrating a lignin-modified wood (LMW) with a solution of methyl acrylate (MA) and rare-earth strontium aluminum oxide (SrAl 2 O 4 : Eu2+, Dy3+; SAOED) yielded afterglow and photochromic translucent wood. Preparing photoluminescent transparent wood effectively requires dispersing SAOED phosphor nanoparticles (NPs) in pre-polymerized MA without clumping. CIE (Commission Internationale de ĺEclairage) Lab colorimetric studies indicated that this transparent timber substrate changed color from colorless in daylight to greenish when exposed to ultraviolet rays. Micrographs taken using a transmission electron microscope (TEM) were analyzed to learn more about the morphology of the synthesized SAOED NPs. Different characterization techniques were applied on the photochromic translucent wood samples, including scanning electron microscopy (SEM), energy-dispersive X-ray analyzer (EDX), hardness properties, wavelength-dispersive X-ray fluorescent spectroscopy (WD-XRF), and absorption and emission spectroscopy. Absorption maximum wavelength was detected at 365 nm. Both 436 nm and 517 nm were observed as emission wavelengths in the developed photoluminescence wood. The results displayed that the manufactured transparent wood introduced superior protection from UV radiation and superhydrophobic activity. UV light triggered a rapid and reversible photochromic reaction in the transparent luminous wood. [ABSTRACT FROM AUTHOR]

Partitioning of 90Sr from other radionuclides in radioactive liquid waste is crucial for treating high-level liquid waste (HLLW) generated during spent fuel reprocessing, as the unique high heat-generating and long half-life of 90Sr pose a significant challenge for the long-term storage of nuclear waste. However, it remains difficult to sieve 90Sr for membrane based on size-selective effect, as the radioactive liquid waste contains numerous typical divalent ions, such as 60Co, 63Ni, and 65Zn, which have the same valence and similar hydration diameters to 90Sr. Here, we experimentally demonstrate a rapid and efficient separation of radioactive 90Sr from other radioactive ions by a reduced graphene oxide membrane, which prepared by the amino-hydrothermal method from graphene oxide suspensions. For SrCl 2 /CoCl 2 , SrCl 2 /NiCl 2 , and SrCl 2 /ZnCl 2 binary mixed solutions, SrCl 2 can pass through efficiently, while the rejection rates for CoCl 2 , NiCl 2 , and ZnCl 2 reached 99.9 %. The separation factors reached 3232, 4254, and 3314, which are about one or two orders of magnitude higher than the highest reported separation factors for membranes sieving divalent ions. Our findings offer a simple avenue for the precise treatment of radioactive liquid waste, which is vital for the advancement of nuclear energy technology. [Display omitted] • rGO membrane for rapid and efficient sieving of radioactive strontium ions/di-valent radioactive ions is achieved. • The separation factors are about one or two orders of magnitude higher than the highest factor reported previously. • DFT computations provide detailed insights into the mechanism of the separation performance of rGO. [ABSTRACT FROM AUTHOR]

Modeling the oxygen partial pressure at the interfaces of solid oxide electrolysis cells is essential to understand their degradation. Here we present a bilayer electrolyte equivalent circuit model that does not assume continuity of the oxygen chemical potential at the electrolyte interface, in line with experimental results. We use the model to assess the assumption that strontium zirconate growth is responsible for oxygen electrode interface pressure increases and delamination. We find that 5% Y-doped strontium zirconate does not drive fracture for accumulations up to 250 nm except at 800 °C and 1.6 V. With a low electronic conductivity, 5% La-doped strontium zirconate shows a region of stability where increased thickness actually stabilizes the interface pressure. We also highlight the importance of modeling interface stability with the proper electronic conductivity. Finally, we present interface stability requirements and contextualize the strontium zirconate composition results in terms of interface stabilization strategies. [Display omitted] • An equivalent circuit model for solid oxide cell bilayer electrolytes is presented. • Refined stability criteria for solid oxide electrolysis cells are presented. • The oxygen electrode interface pressure induced by strontium zirconate formation is quantified. [ABSTRACT FROM AUTHOR]

In this investigation, a new transparent boro-tellurite glass series modified with strontium oxide and differing ratios of bismuth oxide was synthesized to explore the radiation shielding ability. The mechanical and physical features were checked theoretically. At the same time, the structure for fabricated glasses was investigated by Raman spectra, thermo-gravimetric analysis (TGA), and X-ray diffraction (XRD). According to Raman spectra results, the prominent peaks displayed enhancing and shifting to lower wavenumber from 774 cm−1 for TBSB0 to 751 cm−1 for TBSB20 with adding Bi 2 O 3 instead of TeO 2. XRD proved the amorphous nature of all glass samples. In contrast, TGA explored the thermal stability by studying the weight loss for TBSB0 and TBSB20 that are 1.6264 % and 0.3198 % at 1000 °C, respectively. The inclusion of Bi 2 O 3 as opposed to TeO 2 resulted in a density enhancement from 4.3200 to 5.6900 g/cm3, packing density (V t) from 0.4221 to 0.4715, and mass attenuation coefficient (μm, at 184 keV) from 0.2921 to 0.7185 cm2/g. On another side, experimental evaluation of the radiation shielding properties was conducted, and the μ m values were compared with XCOM data. The theoretical and experimental relative difference was in the 0.445–5.974 % range. The direct relation between Bi 2 O 3 concentrations and radiation shielding properties is obvious. TBSB20 sample showed the highest radiation shielding capacity compared with other fabricated glasses. These results indicate the ability to use the fabricated glasses in the radiation shielding field. • A series of boro-tellurite modified with different contents of bismuth oxide was prepared by the ordinary melt quench method. • Adding Bi 2 O 3 instead of TeO 2 enhanced the density and mass attenuation coefficient. • TGA checked the thermal stability for current samples. • Raman spectra for current samples showed a main change in peaks with the addition of Bi 2 O 3. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO)-crown ether (CE) composite preparation was carried out using diverse CE/GO configurations where, composite/structural suitability and adsorption characteristics of these composites were evaluated to derive optimal strontium (Sr(II)) separation conditions. Initial characterization and Sr(II) sorption studies evidenced the eminence of GO-18-crown-6-ether (GO-18C6) composites among those explored and, a comprehensive investigation on compositing procedure, ambience, affecting parameters was undertaken to deduce relevant interaction mechanism. 18C6 molecules interact with GO layers via CH-π, hydrogen bond, dipole-dipole and covalent interactions, reduce graphitic content, deteriorate structural order and induce aggregate formation. Sr(II) sorption at composite membranes is determined by GO/18C6 composition and structure, composite mass, Sr(II) concentration and pH of the ambience. Composite membranes prepared at optimal interaction conditions exhibited maximum Sr(II) adsorption capacity of ∼890 mg/g, attributed to development of profusive Sr(II) reactive sites and effective amendment of permeation channels. Inferences on optimal Sr(II) adsorption at composite membranes were validated further via sorption studies on extended and N-functionalized GO/CE structures. The rapid, economic and competent Sr(II) adsorption demonstrated in the present work evidence synergetic performance of GO-CE in composite, re-emphasize the potential of membranes in Sr(II) separation and finds significance in removal of alkali/alkaline earth metal ions from aqueous waste solutions. • Develops diverse CE-GO composites and analyzes the allied interaction mechanisms. • Evaluation of multiple compositing methods, CE structures, Sr adsorption parameters. • GO-CE composite membranes displayed optimum Sr adsorption performance of ∼890 mg/g. • Rapid, economical and efficient Sr separation procedure, devoid of secondary waste. • Evidence synergetic performance of GO-CE, potential of membranes in Sr separation. [ABSTRACT FROM AUTHOR]

Hydrogen storage in transition mixed metal oxides (MMOs) are predicted from their tendency for adsorption-desorption hydrogen. Hydrogen itself requires initial forces pressure for initiation of condensation. MMOs, based on their effective immobilization matrices, are potential nanocatalysts for energy storage. Even various materials are highlighted for hydrogen storage; however, their adsorption capacities are insufficient for real applications. Here we report, for the first time, a novel hydrogen storage MMOs (Sr 2 Co 9 O 14 nanoparticles) potential for physical hydrogen sorption, containing a redox species. This polycrystalline nanoparticle is prepared via a combustion method in the presence of various fuels like glucose, fructose, sucrose, lactose, and maltose. The glucose supports the pure and homogenous formation of Sr 2 Co 9 O 14 nanoparticles consisting the particles less than 100 nm. Interestingly, a maximum discharge capacity of around 950 mA h/g at room temperature has recorded; emphasizing Sr 2 Co 9 O 14 nanoparticles is a potential substrate for hydrogen storage. • Auto-combustion utilize for production of Sr 2 Co 9 O 14 nanostructures. • Variation of reducing agents foster particles formation. • Polycrystalline Sr 2 Co 9 O 14 nanostructures well growth in glucose. • A mixed conductive matrix, and crystalline texture support hydrogen storage ability. • Presence of redox species in structure enhance hydrogen discharge properties. [ABSTRACT FROM AUTHOR]

Strontium phosphates with apatite structure containing cobalt and fluoride atoms in the trigonal channels were synthesized and characterized by magnetic measurements. The compounds exhibit slow magnetization relaxation with two types of relaxing centers with an energy barrier for magnetization reversal of about 55 and 200 cm–1, respectively. On the fluoride incorporation, the nature of the magnetic centers remains the same as in the initial hydroxyapatite, while the quantity of cobalt incorporated in the channels is reduced substantially. In the sample with the highest fluoride content slow relaxation behaviour almost disappears. [ABSTRACT FROM AUTHOR]

Strontium phosphate glasses with varying minor over weight cobalt oxide were prepared and investigated by impedance spectroscopy. The ac conductivity was measured for all samples in the range of frequencies from 0.1 Hz to 20 MHz at different temperatures. It was found that the ac conductivity showed an increasing behavior with increasing both the temperature and frequency at fixed glass composition. On the other hand, the real and imaginary parts of dielectric constant and dissipation factor tangent showed a decreasing trend with increasing frequency for all prepared samples. In addition, frequency exponent is observed to decrease with increasing temperature, where 0.5 < s ≤ 1. Based on the obtained data correlated barrier hopping (CBH) can be considered as the suitable conduction mechanism in the investigated glasses. Ac conductivity was identified to decrease with increasing doping (CoO) concentration. • Strontium phosphate glasses doped with minor amount of cobalt oxide were prepared. • Prepared samples were studied using dielectric impedance spectroscopy. • Frequency exponent (s) is observed to decrease with increasing temperature. • Correlated barrier hopping (CBH) considered as the suitable mechanism of conduction. [ABSTRACT FROM AUTHOR]

The Sr2 –xLaxTiO4 (x = 0–2.0) catalysts were synthesized based on strontium titanate with a layered perovskite structure. The effect of the degree of substitution of La for Sr on the physicochemical (phase composition and textural characteristics) and catalytic properties of oxides in the oxidative condensation of methane at temperatures of 700–800°C were studied. It was found that multiphase Sr2 – xLaxTiO4 samples with the degree of substitution x = 0.8–1.8 were most active and selective in the test reaction; this was likely related to the presence of lanthanum oxide and strontium oxide impurities in them, their optimum distribution over the surface, and the specific surface area. [ABSTRACT FROM AUTHOR]

In this paper, the effect of impurity ions on the preparation and properties of Portland cement was studied. The crystal appearance and structural changes of cement clinker minerals are reviewed in this paper. Various anions and cations (groups) are added to Portland cement clinker and its minerals and sulfid aluminate cement mineral C4A3. The effect of impurity ions on the structure of high cementitious cement is analyzed from the point of view of chemical structure parameters. Some impurity ions can improve the burnability and strength of clinker by using some impurity ions alone or in combination. The mechanism is to reduce the decomposition temperature of calcium carbonate, to improve the properties of liquid phase and to increase the amount of liquid phase, to form defects in clinker minerals, to cause lattice distortion or to stabilize different crystal variants, to form new minerals, and so on. These effects are related to chemical structure parameters such as impurity ion radius, electricity price, electronegativity and so on. The effect of introducing new minerals on the properties of cement during doping is also reviewed. [ABSTRACT FROM AUTHOR]

The physicochemical properties of glasses in the 50SrO · 50B2O3–50SrO · 50SiO2 join (mol %), such as density, microhardness, thermal expansion, and glass-transition temperature, are studied. Comparison with the characteristics of strontium-borosilicate glasses in other join with the constant strontium oxide content shows that the molar volume increases with an increase in the concentration of B2O3 and does not depend on the SrO content in the range of 50 to 35 mol %. It is determined that the glass-transition temperature decreases with the replacement of SiO2 by B2O3. The concentration dependences of the microhardness, thermal expansion coefficient above the glass transition region (αl), and the change of the thermal expansion coefficient in the glass transition region (Δα) have a maximum in the composition range rich in boron oxide. [ABSTRACT FROM AUTHOR]

Molecular complexes of Ca, Sr, and Ba with the reduced forms of 3,6‐di‐tert‐butyl‐o‐benzoquinone as ligands (catecholate, 3,6‐Cat2–, or semiquinone 3,6‐SQ–‧) were synthesized and structurally characterized. Trinuclear complexes [M3(3,6‐Cat)3(thf)6] (1, M = Ca; 2, M = Sr) or tetranuclear complex [Ba4(3,6‐Cat)4(thf)6] (3) crystallize from tetrahydrofuran (thf) solutions. In the structures of 1 and 2 metal atoms form a nearly right triangle with two µ3‐bridging 3,6‐Cat ligands; in 3, the metal atoms form a tetrahedron contracted along a twofold axis, and all the catecholates are µ3‐bridging. In nonpolar media the complexes 1–3 lose coordinated thf, upon which 1 is converted into complex [Ca4(3,6‐Cat)4(thf)4] (4), structurally similar to 3. Complex 1 is oxidized by one equivalent of the quinone to yield mixed‐ligand complex [Ca3(3,6‐SQ)2(3,6‐Cat)2(thf)4] (5), structurally similar to 1. Successive oxidation by the quinone leads to dissociation to mononuclear species, [Ca(3,6‐SQ)2(thf)3] (5), which possesses pentagonal‐bipyramidal coordination with two semiquinolate ligands lying in an equatorial plane. Solution behavior of the complexes is studied by NMR (for catecholates) and EPR (for semiquinolates) spectroscopy. [ABSTRACT FROM AUTHOR]

A red-emitting Eu3+-activated double perovskite Sr 3 MoO 6 phosphor material was successfully synthesized by a high-temperature solid-state reaction. Upon 353 and 467 nm excitations, the prepared phosphors exhibited the feature emission properties of Eu3+ ions with the corresponding characteristic electronic transitions. The concentration quenching of Eu3+ ions was found at 30 mol% and the quadrupole-quadrupole interaction was dominant in quenching process. The chromaticity coordinates for the optimal doping concentration of Eu3+ ions under the 353 and 467 nm excitations were in the pure red region, while the color purity was calculated to be about 94.536 and 94.780%, respectively. The superior luminescence properties of the red-emitting Sr 3 MoO 6 :0.3Eu3+ phosphor were achieved and with further blending with commercial phosphors, the white light-emitting diode (WLED) devices were fabricated for practical application. The fabricated WLED device based on 385 nm near-ultraviolet (NUV) chip revealed the color-rendering index and color temperature values of 90.96 and 6381 K, respectively. And the soft polydimethylsiloxane film emitted the pure red region under NUV light. These results suggest that this kind of material could be a promising red-emitting phosphor for WLEDs and flexible display film. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) was prepared, characterized, and applied for adsorption of Sr(II) in aqueous solution. The adsorption capacity was calculated to be 137.80 mg/g according to the Langmuir model. The observation by scanning electron microscope with energy dispersive X-ray detector (SEM-EDX), high-resolution transmission electron microscope (HRTEM), and X-ray diffraction (XRD) revealed the crystal structure of Sr compound on the surface of graphene sheets. The analyses by the Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated the involvement of O–C=O, C–O, and C–O–C groups during the adsorption. The X-ray absorption fine structure (XAFS) analysis provided the detail information of GO-Sr composites, and the fitting results were given by Sr(HCOO)2 and SrCO3 model, and the coordination numbers (CN) and interatomic distances (R) of Sr–O shell and Sr–C shell were calculated. The adsorption mechanism of Sr(II) was attributed to complexation between Sr and the acidic oxygen-containing groups, which lead to the agglomeration of graphene oxide. Two types of crystals were proposed. Type 1 was formed by coordination between Sr(II) and O–C=O groups, and type 2 was formed by coordination between Sr(II) and C–O/C–O–C groups. [ABSTRACT FROM AUTHOR]

A method of the oxygen isotope exchange with equilibration of the gas phase was used in order to obtain the temperature dependences of the oxygen surface exchange and diffusion coefficients of the proton-conducting oxides La 1– x Sr x ScO 3–δ (x = 0; 0.04; 0.09) in the temperature range of 600–900 °C and oxygen pressure of 1.01 kPa. The diffusion and oxygen surface exchange coefficients increase with the strontium content in oxides. The rates of the individual stages of the oxygen exchange process on the surface of the oxides were determined. The oxygen incorporation was revealed to be rate-determining for the undoped LaScO 3 oxide. However, for the strontium-doped oxides La 1– x Sr x ScO 3–δ (x = 0.04; 0.09), the difference between the rates of oxygen dissociative adsorption and oxygen incorporation decreases with increasing the strontium concentration, in a way that for the La 0.91 Sr 0.09 ScO 3−δ oxide these stages become competing. The possible reasons for these differences in oxygen surface exchange kinetics were analyzed in this paper. Using the obtained oxygen diffusion coefficients, the oxygen-ionic conductivities in accordance with the Nernst-Einstein equation, and the contributions of the oxygen-ion and proton components of the total conductivity of the La 1– x Sr x ScO 3–δ (x = 0.04; 0.09) oxides in the wet reducing atmosphere (p H 2 O = 2.35 kPa, p O 2 = 10−15 Pa) were calculated. The proton transference numbers were found to be close to unit at the wet reducing atmospheres in the temperature range of 500–600°С. • The oxygen surface exchange rates are measured in La 1− x Sr x ScO 3−δ oxides. • The oxygen diffusion coefficients are measured in La 1− x Sr x ScO 3−δ oxides. • The proton transference numbers are estimated in La 1− x Sr x ScO 3−δ oxides. [ABSTRACT FROM AUTHOR]

We have synthesized CaMoO4- and SrMoO4-based scheelite-like compounds and located the stability ranges of (Ca/Sr)1 – 3xBi2xMoO4 solid solutions (x = 0.2125). The materials with x ≥ 0.175 have been shown to undergo superstructure ordering related to the arrangement of cation vacancies in their structure. The reflection spectra of the solid solutions have been measured and their band gap for direct transitions has been shown to range from 2.8 to 3.5 eV. We have studied photocatalytic properties of the solid solutions using powder samples. The photocatalytic characteristics of Ca1 – 3xBi2xMoO4 under UV illumination have been shown to be comparable to those of titania. The electrical conductivity of Ca1 – 3xBi2xMoO4 is lower than that of Sr1 – 3xBi2xMoO4. [ABSTRACT FROM AUTHOR]

Two new metal iodates, namely, M(IO3)2(HIO3) (M = Ca, Sr), were successfully synthesized by the hydrothermal method, and their structures were determined by single-crystal X-ray diffraction. They were found to be isostructural, and crystallized in the monoclinic space group P21/n with the lattice parameters: a = 6.9647(14) Å, b = 15.719(3) Å, c = 7.2042(14) Å, β = 92.76(3)°, Z = 4 for Ca(IO3)2(HIO3), and a = 7.0697(14) Å, b = 15.986(3) Å, c = 7.3802(15) Å, β = 93.13(3)°, Z = 4 for Sr(IO3)2(HIO3). The structure featured a [HIO3]·[IO3]− complex with strong intermolecular interactions, and it was composed of [IO3]− anions and [HIO3]·[IO3]− complexes interconnected by Ca2+ or Sr2+ cations. The two compounds were characterized by X-ray diffraction, IR and Raman spectroscopies, UV–Vis diffuse reflectance spectroscopy, thermogravimetry and differential scanning calorimetry as well as by theoretical calculations. [ABSTRACT FROM AUTHOR]

Samples of Sr1−xCexFe12O19 (x = 0.0, 0.05, 0.1, and 0.15) were synthesized by a hydrothermal process. The X-ray diffraction patterns and the Rietveld refinement method confirmed the formation of the pure nano-crystalline phase of the M-type hexaferrite for all samples, except for the x = 0.15 sample with a small CeO2 phase. Fourier transform-infrared spectroscopy measurements showed the formation of the M-type hexaferrite. Field emission-scanning electron microscopy revealed that the prepared samples were nanoparticles that agglomerated in irregular platelets. The hysteresis loops (M–H) measured at room temperature indicated a decrease in the saturation magnetization with an increase in the Ce content. The band gap dependency on the Ce content was also studied using the UV–Vis spectra, which showed that the band gap energies were in the range of 1.37–1.51 eV. The dielectric constant and dielectric tangent loss measurements showed that the x = 0.1 sample has higher values than others. [ABSTRACT FROM AUTHOR]

• VUV spectroscopic properties and emission decay dynamics. • Luminescence from two crystallographic sites can be identified. • Excellent thermally stable phosphor based on Sr 9 Lu(PO 4) 7 :Ce3+. Ce3+-doped Sr 9 Lu(PO 4) 7 polycrystalline material has been synthesized using a solid state reaction at high temperature. Luminescence spectroscopic properties and emission decay kinetics have been studied upon UV-VUV excitation. Emission from Ce3+ ions located in two types of crystallographic sites has been identified in low-temperature spectra. Ce3+ ions have been shown to prefer occupying Sr2+ sites rather than Lu3+ sites. The temperature-dependent decay curves of Ce3+ 5d→4f emission demonstrate an excellent luminescence thermal stability. [ABSTRACT FROM AUTHOR]

• Strontium doping enhances NO x storage and reduction performance of bulk LaCoO 3. • 30% is the optimum strontium doping degree for bulk perovskites, La 0.7 Sr 0.3 CoO 3. • A more efficient use of the perovskite can be achieved by supporting it over Al 2 O 3. • Perovskite loading around 30% over Al 2 O 3 maximizes its utilization. • NSR performance was better for Al 2 O 3 supported perovskites than bulk ones. Here we report the effects of strontium doping of perovskites (La 1-x Sr x CoO 3) on NO x storage and reduction (NSR) as well as the effects of supporting the perovskite onto an alumina support. The NSR capacity of La 0.7 Sr 0.3 CoO 3 improved with strontium doping: this material displayed a good balance between NO oxidation capacity and adsorption sites accessibility. Increased accessibility was mainly due to the strontium oxide segregates. In addition, different loadings of La 0.7 Sr 0.3 CoO 3 perovskite (10, 20, 30, 40 and 50%) were impregnated onto alumina in order to increase the exposed surface area of the perovskite. This had the effect of increasing the NSR capacity of the perovskite. The results of X-Ray diffraction, UV–vis–NIR spectroscopy, N 2 adsorption-desorption, electron microscopy, and temperature programmed techniques, demonstrated that the cobalt ions preferably formed cobalt aluminate (CoAl 2 O 4) in the case of low perovskite loadings (<20%). Meanwhile, a well-developed perovskite phase was observed with the higher loadings (>30%). The specific NO oxidation rate per gram of perovskite increased dramatically with the incorporation onto an alumina support. 30% LSCO/Al 2 O 3 sample had an oxidation rate of 138 μmol min-1 (g LSCO)-1 at 350 °C, more than double the rate of the bulk La 0.7 Sr 0.3 CoO 3 (49 μmol min−1 (g LSCO)−1). Likewise, the 30% LSCO/Al 2 O 3 sample had a higher NO x storage capacity than its bulk counterpart at 400 °C: 306 vs. 115 μmol (g LSCO)−1. The higher oxidation capacity of the alumina-supported samples also facilitated the diffusion of the intermediate compounds from oxidation to adsorption sites. Impregnating alumina with perovskite could be used to improve the efficiency of perovskite mediated NO x removal in automobile applications. Furthermore, adding palladium onto optimum alumina-supported perovskite sample, i.e. 1.5% Pd-30% LSCO/Al 2 O 3 , resulted in a clear improvement in NO x storage and reduction capacity. This last sample demonstrated a nitrogen yield as high as 65%, an improvement over the model Pt-based NSR catalyst. [ABSTRACT FROM AUTHOR]

Recently, aminohydroximate ligands have found wide applications in the fascinating class of polynuclear metallamacrocyclic compounds named 15-MC-5 metallacrowns. The enhanced interest in water-soluble aminohydroximate Ln(iii)–Cu(ii) complexes is largely due to their rich coordination chemistry, diverse properties and ease of synthesis. We examined glycinehydroxamic acid as a simple ligand for the preparation of the first water-soluble polynuclear metallamacrocyclic Sr(ii)–Cu(ii) compound. The complex Sr(H2O)3[15-MCCuGlyha-5](Cl)2 was synthesized and characterized structurally and spectroscopically. The single-crystal structure reveals the classic metallamacrocyclic 15-MC-5 configuration. The Sr(ii) ion is located at the center of the 15-MCCu(II)Glyha-5 ring and coordinated by five oxygen atoms of the cycle in the equatorial plane and an additional three oxygen atoms of the water molecules at apical positions. Detailed DFT and QT AIM studies were carried out for the hydrated isoelectronic Sr[15-MCCuGlyha-5]2+ and Y[15-MCCuGlyha-5]3+ systems. The ionic contribution to the metal–ligand interactions appears to be higher for the Sr(ii) derivative despite the smaller charge separation. DFT calculations suggest a thermodynamically favorable substitution of the Sr(ii) central ion with Y(iii). Indeed, it was shown experimentally that the strontium ion can be easily replaced by yttrium. Preliminary cytotoxic studies revealed the low toxicity of the strontium complex and its yttrium analogue, so the water-soluble Sr(ii) and Y(iii) metallacrowns can be further investigated as possible platforms for the development of new 90Sr and 90Y radiotherapy drugs. [ABSTRACT FROM AUTHOR]

The novel amorphous strontium oxide (α-SrO) resistive random access memory (RRAM) device based on the ITO/α-SrO/Pt sandwich-like structure was presented. Photosensitivity to ultraviolet (UV) light for α-SrO based RRAM was investigated. The resistive switching characteristics were affected through the modification of the number of oxygen vacancy by the UV irradiation. Ultraviolet light-assisted oxygen vacancy manipulation in the SrO film is an effect method to adjust device resistive switching behavior. The current conduction mechanism of the SrO-based RRAM device was changed from the Schottky emission mechanism to Poole-Frankel mechanism after the UV light illumination. In order to unveil the stability of the SrO samples after the UV light illumination, the physical models for different switching processes were proposed. Additionally, the improved switching uniformity via UV light irradiation gives physical insight into designing resistive memory devices. [ABSTRACT FROM AUTHOR]

Highlights • A simple and effective modification method is developed to modified the 3D rGO/PPY with Sr. • This scaffold holds macropores size and higher surface biological activity. • This scaffold significantly enhances the early adhesion, proliferation and osteogenic ability of MC3T3-E1 cells. Abstract The development of a bone tissue engineering scaffold with a biologically active surface for fast bone cell adhesion, proliferation, and extracellular matrix mineralization has been hotly pursued in recent years. However, most substrate materials do not show enough biological activity. Here, polydopamine-assisted immobilization of strontium (Sr) endows a three-dimensional reduced graphene oxide/polypyrrole (3D rGO/PPY) composite scaffold with higher bioactivity. Compared to the bare 3D rGO/PPY scaffold, 3D rGO/PPY modified with Sr (3D rGO/PPY/PDA/Sr) has a higher surface roughness. Moreover, benefiting from the introduction of Sr, the 3D rGO/PPY/PDA/Sr scaffold can significantly enhance early adhesion and proliferation of MC3T3-E1 cells on the 2nd day of culture. Additionally, ALP activity and extracellular matrix mineralization are distinctly enhanced. [ABSTRACT FROM AUTHOR]

Magnetic nanocomposite (hard) SrFe12O19-(soft) La(1-x) SrxMnO3 powders in 4:1 weight ratio was synthesized via a one-pot auto-combustion technique using nitrate salts followed by heat treatment in air at 950°C. Structural and morphological characterizations were performed via x-ray diffraction (XRD) and transmission electron microscopy (TEM). Vibrating sample magnetometer (VSM) was used to study the magnetic properties of the samples. XRD analysis shows presence of pure phase components in the nanocomposite. TEM images show presence of needle shape Sr-Ferrite particles. The room temperature hysteresis loops of the samples showed the presence of exchange-coupling between the hard and soft phases of the composite. The room temperature magnetic measurements revealed the higher Mr/Ms ratio for the nanocomposite than that for the single phase SrFe12O19 which proves the existence of the inter-grain exchange coupling between hard and soft magnetic phases with the exchange spring behavior. The highest Mr/Ms ratio of 0.58 was obtained in SrFe12O19- La0.25Sr0.75MnO3 composite which exhibited 82% increase in the coercivity (Hc∼6.26 kOe) as compared to pure SrFe12O19 (Hc∼3.63kOe). Synthesis of hard-soft exchange couple nanocomposite by controlling the "magnetic softness" of a soft phase instead of more traditional approach of varying concentration of the soft phase could be the promising way to use them in many magnetic applications. [ABSTRACT FROM AUTHOR]

Surface functionalized tri-metallic strontium magnesium ferrite (Sr 0.3 Mg 0.7 Fe 2 O 4 , SMF) nanoparticles were synthesized by using facile solvent less green oleo polyol method. Various analytical techniques (XRD, XPS, FT-IR, TEM, SEM, BET, and VSM) were used for the investigation of the crystal lattice, surface functionalization, morphology, surface area, and magnetic properties of these nanoparticles. SEM and TEM analysis revealed that the nanoparticles exhibit mesoporous morphology with cubic structure. These mesoporous nanoparticles have been exploited for the removal of toxic organic pollutant (Congo red, CR) from the aqueous solution. Detailed investigations on the adsorption of CR dye by these nanoparticles have been conducted via the rate kinetics study using various adsorption isotherms (Freundlich, Langmuir, Temkin, etc.). These studies revealed that the mesoporous SMF nanoparticles with the high surface area (21.85 m2g−1), have exhibited superior adsorption capacity (>90% within 30 min) and fast separation ability under the influence of external magnetic field along with good recyclability (∼93%). The adsorption analysis of magnetic SMF revealed pseudo-second order dye removal kinetics and follow Freundlich isotherms. These properties of magnetic SMF nanocubes provide an extra edge over other such reported systems and may find its potential as a cost-effective magnetic adsorbent for water treatment application. Image 1 • Cost-effective oleo polyol method have been used to synthesize Sr 0.3 Mg 0.7 Fe 2 O 4 nanoparticles. • SEM and TEM confirms the formation of mesoporous morphology with cubic structure. • These nanoparticles exhibited excellent magnetic properties with a high surface area. • They displayed excellent dye absorption capacity (∼ 90% within 30 min). • Fast removal of toxic dye (Congo red) make their potential in water treatment. [ABSTRACT FROM AUTHOR]

Abstract We have reported the synthesis of core-shell nanostructure of mesoporous silica coated lanthanum strontium manganese oxide nanoparticles (MSLN) as a potential candidate for cancer treatment via magnetic hyperthermia. N 2 adsorption-desorption isotherm revealed that mesoporous silica shell coating increased the surface area and pore volume of lanthanum strontium manganese oxide nanoparticles (LSMO). In comparison to LSMO, MSLN showed a stable colloidal dispersion up to 48 h. In-vitro studies using A549 cells demonstrated increased biocompatibility in MSLN as compared to LSMO. Moreover, cells treated with MSLN exhibited high cell survival rate of up to 1 mg/ml concentration. Further, we used different parameters to modulate the heating efficacies of these nanoparticles. The modulation of specific absorption rates (SAR) with different sample concentrations (0.5, 1, 1.5, 2.0 mg/ml) were studied under four different alternating current magnetic field (AMF) amplitudes (10, 11, 12, 13 kA/m) at a constant frequency of 335 KHz for magnetic hyperthermia experiments. Under the application of AMF, MSLN exhibited faster Néel and Brownian relaxation compared to their LSMO counterparts. SAR value of 295 W/g and intrinsic loss power (ILP) of 5.22 nHm2/kg, at a low sample concentration of MSLN (0.5 mg/ml) were obtained, which was within the clinical limit. Interestingly, our results showed 45% improvement in terms of the heating efficiency over the commercially available products (Table 3). Hence, we conclude that MSLN with high SAR and ILP values, good colloidal dispersion ability and low cytotoxicity could be a potential candidate for magnetic hyperthermia therapy in cancer and warrant further testing in both in-vitro and in-vivo studies. Further, due to their mesoporous nature, MSLN could be considered for target-specific drug delivery applications in clinical therapy. Highlights • Mesoporous silica-coated lanthanum strontium manganese oxide nanoparticles (MSLN) were synthesized. • Structural parameters of lanthanum strontium manganese oxide (LSMO) were calculated using Rietveld refinement software. • MSLN showed a larger surface area and pore volume as compared to LSMO. • MSLN exhibited better colloidal dispersion and enhanced biocompatibility than LSMO nanoparticles. • MSLN showed high specific absorption rate (SAR; 295W/g) as well as high intrinsic loss power (ILP; 5.22 nHm2kg−1). [ABSTRACT FROM AUTHOR]

The catalytic activities of three topotactic phase strontium cobaltites (SCO, hexagonal, orthorhombic and tetragonal) for H2O2 decomposition were studied. All they present excellent catalytic activity with good stability at cycled test, and the mesoporous tetragonal SCO exhibits the best activity. Detailed kinetic research indicates the zero-order process of H2O2 decomposition. Increasing the temperature will accelerate the reactions greatly with the controlled temperature in the range of 20-45 °C. The calculated active energy (Ea) for H-SCO, O-SCO and T-SCO is 93.2, 85.1 and 87.5 (kJ/mol), respectively. The efficient catalytic degradation of Rhodamine B illustrates that SCO is a kind of promising catalysis for the advanced oxidation process. [ABSTRACT FROM AUTHOR]

This study investigates grain growth in the perovskite oxide strontium titanate in an electric field. The seeded polycrystal technique was chosen as it provides a sensitive and controlled setup to evaluate the impact of different parameters on grain growth due to the well‐defined driving force for grain growth. Current blocking electrodes were used to prevent Joule heating. The results show faster grain growth, and thus, higher grain‐boundary mobility at the negative electrode. It is argued that the electric field causes point‐defect redistribution, resulting in a higher oxygen vacancy concentration at the negative electrode. The local oxygen vacancy concentration is suggested to affect the space‐charge potential at the grain boundaries. A thermodynamic treatment of the grain‐boundary potential at a grain boundary without field shows that for a high oxygen vacancy concentration less space‐charge and less accumulation of cationic defects to the boundary occurs. Therefore, at the negative electrode, a higher oxygen vacancy concentration results in less space‐charge and less accumulation of cationic defects. The lower degree of defect accumulation requires less diffusion of segregated defects during grain‐boundary migration, so that at the negative electrode faster grain growth is expected, as found in the experiments. [ABSTRACT FROM AUTHOR]

Abstract Surface chemistry and topography can determinatively affect the osseointegration of dental implants. Strontium (Sr) has a significant effect on the promotion of bone formation and inhibitation of bone resorption. The emphasis of this study lies on the evaluation of a new surface treatment that aims to improve the early osseointegration of dental implantation both in vitro and in vivo. A hydrothermal method was used to prepare an SrTiO 3 incorporation on sandblasted large-grit double acid-etched (SLA) titanium surfaces in SrCl 2 solution. The composition and morphology of the SrTiO 3 doped surface were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy，and scanning electron microscopy. In addition, the external release figure of Sr was examined by inductively coupled plasma mass spectrometry. The proliferation, adhesion and differentiation of MC3T3-E1 cells on this surface were evaluated in vitro and presented a significant increase in SLA-Sr group compared with that in SLA group. An in vivo study in 24 New Zealand rabbits indicated a remarkable growth in the volume of direct bone-to-implant contact and peri-implant bone in SLA-Sr group, which were compared with SLA group after 3 and 6 weeks, and removal torque tests exhibited a higher torque removal value of SLA-Sr implants. The study gave the result that the biological effect of SLA-Sr implants was significantly superior to that of the SLA implants at the early stage of osseointegration. Highlights • SrTiO 3 was incorporated on sandblasted large-grit double acid-etched (SLA) titanium surfaces by hydrothermal method. • SrTiO 3 incorporated SLA surface promoted the bone formation in vitro and in vivo, especially at the early stage of osseointegration. • The work will have a remarkably clinical potential and take a step forward in respect to the current clinical practice. [ABSTRACT FROM AUTHOR]

Novel Brönsted acid functionalized magnetic polymeric nanocomposite, Ba0.5Sr0.5Fe12O19@PU-SO3H, has been successfully synthesized and characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) techniques. The catalytic activity of the nanocomposite was tested in the regioselective synthesis of 7-aryl-benzo[h]tetrazolo [5,1-b] quinazoline-5,6-diones in an eco-friendly and recyclable media, deep eutectic solvent (DES), based on choline chloride and urea. This novel method offers several advantages, such as high yields, short reaction time, environmentally friendly reaction media, easy isolation of the product, and also offers an easy method for the synthesis of nanocatalysts. The catalyst was readily recycled by the use of an external magnetic field and could be reused 6 times without significant loss of activity or mass. DES as one of the most promising environmentally benign and cost-effective alternatives to conventional ionic liquids and volatile organic solvents was recovered from the aqueous filtrate by evaporating the water under vacuum. The recycled DES was used up to 4 runs without any loss in activity. [ABSTRACT FROM AUTHOR]

Abstract Stoichiometric 0.5 BaO·0.5 SrO·2 ZnO·2 SiO 2 glass was doped with 5 mol% Nb 2 O 5 or Ta 2 O 5. The effect of these additives on the crystallization behavior was studied using thermal analyses, X-ray diffraction, as well as scanning electron microscopy including elemental analyses. The addition of Nb 2 O 5 or Ta 2 O 5 significantly increases the glass stability enabling the preparation of crystal-free BaO·SrO·ZnO·SiO 2 glasses with almost stoichiometric composition. Besides the desired main crystal phase Ba 1-x Sr x Zn 2 Si 2 O 7 , also alkaline earth tantalates and niobates as well as Zn 2 SiO 4 are observed. The Nb-containing glass shows solely surface crystallization, whereas in the Ta-containing glass, additionally numerous barium tantalate crystals precipitate in the bulk acting as seeds for the nucleation of Ba 1-x Sr x Zn 2 Si 2 O 7. If the surface crystallized layer of Ba 1-x Sr x Zn 2 Si 2 O 7 approaches such a barium tantalate crystal or gets close to it, then the crystallization of Ba 1-x Sr x Zn 2 Si 2 O 7 is initiated. It is supposed that these nucleation processes are notably facilitated by the stresses present in these glass-ceramics. [ABSTRACT FROM AUTHOR]

To separate Y(III) from a Sr(II)-Y(II) mixture, two silica-based adsorbents, CMPO/SiO2-P and (CMPO + Dodec)/SiO2-P were prepared by impregnating octyl(phenyl)-N,N-diisobutylcarbamoyl methylphosphine oxide (CMPO) extractant and a molecule modifier (1-Dodecanol) into macroporous silica/polymer composite support (SiO2-P). The Adsorbents showed high adsorption affinity to Y(III) and weak adsorption affinity to Sr(II) in HNO3 solution. The amount of adsorbed Y(III) increased with the HNO3 in the solution. The amount of adsorbed Y(III) increased with contact time and reached equilibrium within 30 min. The results showed that a pseudo-second-order kinetic model with a high correlation coefficient described the adsorption process better than other kinetic models. Successful Y(III) separation from Sr(II)-Y(III) mixture in HNO3 solution was achieved. [ABSTRACT FROM AUTHOR]

Abstract A series of ZnO-SrO mixed oxide catalysts were prepared by co-precipitation with different compositions and tested for dimethyl carbonate synthesis from urea and methanol. The catalysts were characterized by BET surface area, XRD, NH 3 -TPD and CO 2 -TPD. The catalyst with 1:1 mol ratio exhibited high DMC yield of 35%. The uniform distributions of moderate to strong basic sites along with considerable number of acidic sites are accountable for high activity. Different reaction parameters were also screened and best possible conditions were established. The catalyst was easily recovered and reused with consistent activity. Graphical abstract Unlabelled Image Highlights • Zn and Sr mixed oxide are active catalysts for synthesis of DMC with high yield • The activity of the catalysts depends on the mole ratio and calcinations temperature. • The presence of both acidity and basic sites directing the DMC yield. [ABSTRACT FROM AUTHOR]

Abstract A membrane reactor containing an immobilized heterogeneous catalyst is an alternative for traditional homogeneous-based catalyzed transesterification for biodiesel production. Major problems in homogeneous catalysis are related to catalyst recuperation and soap formation, which can be overcome by using heterogeneous catalysts. Conversion can be increased by a combination of reaction and separation, using membranes with a specific pore size. The aim of this work was to study the performance of different membrane reactors combined with heterogeneous catalysis. The main objectives were: to identify a proper catalyst, to choose the proper immobilization technique, to establish the membrane with the adequate pore size, and to control the reaction and separation process. Amberlyst®15 with acid sites and different types of strontium oxide with basic sites were tested as heterogeneous catalysts. Strontium oxide provided the highest sunflower oil conversion (around 93%) and was easy to immobilize. Two catalytic membrane reactor configurations were investigated, thus confirming the production of several types of methyl esters. The configuration comprising the physical immobilization of the catalyst over the membrane reached a methyl ester yield of > 90 wt%. Highlights • Ultra-pure SrO is a proper catalyst for transesterification in membrane reactor. • Membranes with MWCO of 0.2 μm guarantee total oil and glycerol rejection. • IMRCF with the cell heating system has better performance than conventional CMR. • IMRCF with SrO immobilized over the membrane provided a FAME yield of 90.2 wt%. [ABSTRACT FROM AUTHOR]