Material Properties of Strontium Doped Bioactive Glasses/Hydroxyapatite Composite and Its Mechanism of Promoting Bone Repair

Based on bioactive glasses (BG) of 58S, sol–gel method is used to prepare strontium oxide substituted bioactive glasses (SrO-BG) with different strontium content. SrO-BG and nano hydroxyapatite (HAp) composite materials were synthesized using precipitation method. The phase composition and morphologies of the prepared materials were examined by x-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The dissolution and bio-mineralization of SrO-BG and SrO-BG/HAp composites in SBF are investigated by immersion method. The effects of secretion components of macrophages regulated by strontium doped SrO-BG/HAp composites on the osteogenic differentiation (OD) of bone marrow mesenchymal stem cells (BMSCs) are analyzed. The results demonstrate that the SrO-BG can inhibit the dissolution of BG. Different proportions of SrO-BG/HAp composites show good ability to induce HAp in SBF. The bio-mineralization ability of SrO-BG/HAp composites increases with the increase of SrO-BG content. The results of dissolution behavior and bio-mineralization of SrO-BG/HAp composite show that the dissolution rate of each ion can be controlled by adjusting the content of SrO-BG in the composite, and then the degradation rate can effectively be controlled. The results of in vitro experiments show that SrO-BG/HAp composites with 2%, 5% and 8% strontium content are more effective in promoting M2 polarization of macrophages than SrO-BG/HAp composites with 0% strontium content. Among them, 5% strontium doped SrO-BG/HAp has the strongest effect on M2 polarization of macrophages, and the secretion of macrophages regulated by 5% strontium doped SrO-BG/HAp composite is more conducive to bone repair.

An innovative approach for provenancing ancient white marbles: the contribution of x-ray diffraction to disentangling the origins of Göktepe and Carrara marbles

The paper presents a very efficient, quick, low-cost and minimally micro-destructive approach to discriminating between Roman artefacts sculpted with Göktepe (Aphrodisia, Turkey) or Carrara (Apuan Alps, Italy) white marbles by using a standard X-Ray Powder Diffractometer (XRPD) and a refinement of the unit cell parameters and volume of calcite. At present, the routine way of differentiating between these two almost indistinguishable by-eye marbles is based on the typically higher strontium content of calcite in the Microasiatic lithotype, a unique geochemical-crystallographic feature with respect to all other non-Göktepe fine-grained white marbles used in classical times. The XRPD approach has been verified by testing eighteen samples of known composition, nine from Carrara and nine from Göktepe quarries, which had already been analysed with other laboratory techniques. The applicability of the method to archaeological artefacts was confirmed by an archaeometric study performed on some famous Roman sculptures of the National Archaeological Museum of Venice and from Hadrian’s Villa at Tivoli. The results show that Göktepe/Carrara discrimination is always possible and that this XRPD approach can potentially become a useful and low-cost routine procedure to solve provenance issues.

Osteopathy incidence in children and adolescents consuming drinking water with high content of natural strontium

Introduction. Excessive intake of heavy metals of natural origin with drinking water increases the risk of the formation of non-infectious diseases of systems and organs, depending on the tropism of the chemical compound. The aim is to study the incidence of disorders of bone density and structure (osteopathies) in children and adolescents who consume drinking water with an increased strontium content due to the geochemical characteristics of the territory. Materials and methods. The observation group consisted of 93 children living in a geochemical province with a stable strontium content of more than 2 MPC in the centralized drinking water supply system. The comparison group included 148 children living in an area where strontium concentration in drinking water does not exceed 1 MPC. The incidence evaluation was carried out according to the official data of statistical materials. The analysis of the average values of the concentration in the blood of strontium, ionized calcium, inorganic phosphorus and alkaline phosphatase activity and the frequency of deviations from the norm of the studied parameters was carried out in the studied groups. The value of bone mineral density (Z-index) was determined according to the results of ultrasonic densitometry. Results. The level of long-term incidence of osteopathies for the period 2010-2019 in children and adolescents, the observation area was 6.59 ± 1.32 and 11.26 ± 2.07 ‰, respectively, which was 1.8 and 2.0 times higher than the level of the comparison territory (p = 0.0003-0.0004 ). The concentration of strontium in the blood of children living in the territory of the geochemical province exceeded 2.1 times the permissible reference (p <0.001) and 2.9 times the index of the comparison group (p = 0.0001). In ¾ children of the observation group, increased content of strontium in the blood was recorded, which was 5.2 times more often than the comparison area (p <0.001). In 57% of cases, the children of the observation group had a reduced level of ionized calcium in the blood (p = 0.0001). Low bone mineral density (Z-index) in the observation group occurred 2.3 times more often (17.2 versus 7.4%, p = 0.019). Significant dependences were established by lowering the level of ionized calcium and the value of the Z-index with increasing strontium content in the blood. Conclusion. In children living in geochemical provinces with an elevated strontium content, an increase in the incidence of osteopathy was noted, manifested by a reduced level of ionized calcium in the blood and low bone mineral density, which must be taken into account for the timely diagnosis and prevention of these conditions.

A Robust and Highly Precise Alternative against the Proliferation of Intestinal Carcinoma and Human Hepatocellular Carcinoma Cells Based on Lanthanum Strontium Manganite Nanoparticles

In this report, lanthanum strontium manganite at different Sr2+ ion concentrations, as well as Gd3+ or Sm3+ ion substituted La0.5−YMYSr0.5MnO3 (M = Gd and Sm, y = 0.2), have been purposefully tailored using a sol gel auto-combustion approach. XRD profiles confirmed the formation of a monoclinic perovskite phase. FE-SEM analysis displayed a spherical-like structure of the La0.8Sr0.2MnO3 and La0.3Gd0.2Sr0.2MnO3 samples. The particle size of the LSM samples was found to decrease with increased Sr2+ ion concentration. For the first time, different LSM concentrations were inspected for their cytotoxic activity against CACO-2 (intestinal carcinoma cells) and HepG-2 (human hepatocellular carcinoma cells). The cell viability for CACO-2 and HepG-2 was assayed and seen to decrease depending on the Sr2+ ion concentration. Half maximal inhibitory concentration IC50 of CACO-2 cell and HepG-2 cell inhibition was connected with Sr2+ ion ratio. Low IC50 was noticable at low Sr2+ ion content. Such results were correlated to the particle size and the morphology. Indeed, the IC50 of CACO-2 cell inhibition by LSM at a strontium content of 0.2 was 5.63 ± 0.42 µg/mL, and the value increased with increased Sr2+ ion concentration by up to 0.8 to be = 25 ± 2.7 µg/mL. Meanwhile, the IC50 of HepG-2 cell inhibition by LSM at a strontium content of 0.2 was 6.73 ± 0.4 µg/mL, and the value increased with increased Sr2+ ion concentration by up to 0.8 to be 31± 3.1 µg/mL. All LSM samples at different conditions were tested as antimicrobial agents towards fungi, Gram positive bacteria, and Gram negative bacteria. For instance, all LSM samples were found to be active towards Gram negative bacteria Escherichia coli, whereas some samples have presumed antimicrobial effect towards Gram negative bacteria Proteus vulgaris. Such results confirmed that LSM samples possessed cytotoxicity against CACO-2 and HepG-2 cells, and they could be considered to play a substantial role in pharmaceutical and therapeutic applications.

Strontium and 87Sr/86Sr isotopic ratio of ground brines in the northeastern Angara-Lena artesian basin

The purpose of this study is to identify the major formation processes of the ionic and isotopic composition of chloride brines in the sedimentary basins of the Siberian platform. The object and subject of research are deep-seated strong, very strong and extremely saturated brines as well as their strontium content and the ratio of Sr stable isotopes. The groundwater ionic-salt composition was determined by traditional methods (titrimetric, gravimetric, flame photometry), the 87Sr/86Sr isotopic ratio was measured using mass-spectrometers (Irkutsk, Russia and Canada). The brines lying at the depth of 1500–3000 m were tapped and classified into saline and subsalt hydrogeological formations. Their feature is high salinity (385–530 g/L) and high content of strontium (2.3–7 g/L). The 87Sr/86Sr isotopic ratio ranges from 0.708 to 0.713062. By isotopic composition most of the brine samples are close to the waters of the Vendian-Cambrian paleoocean. However, some brine samples from the subsalt part of the sedimentary section of the basin are significantly enriched in the isotope 87Sr compared to the paleoocean waters and other samples. It could be due to the substantial input of 87Sr into the brines during the long-term interaction of groundwater with the host Lower Cambrian sandstones.

Features of the electrophysical and mechanical properties of n-component ferroactive solid solutions of composition PZT–PZN–PMN

Study of the fatigue endurance and mechanical strength of solid solutions of the PZT–PZN–PMN system, modified with Ba and Sr, corresponding to the formula (Pb[Formula: see text]Sr[Formula: see text]Ba[Formula: see text] [Ti[Formula: see text]Zr[Formula: see text](Nb[Formula: see text]Zn[Formula: see text] (Nb[Formula: see text]Mg[Formula: see text]]O3, with [Formula: see text] = 0.02 ÷ 0.12; [Formula: see text] = 0.02, [Formula: see text] = 0.0036 ÷ 0.073; [Formula: see text]= 0.385 ÷ 0.430, [Formula: see text]= 0.402 ÷ 0.447 is presented. It is shown that the evolution of the polarization characteristics with an increase in the number of repolarization cycles, [Formula: see text], is characterized by two sections: slow fatigue and logarithmic evolution. It was found that an increase in the strontium content shifts the beginning of the logarithmic stage towards to the large [Formula: see text]. It is shown that an increase in the average grain size decreases the mechanical strength. A conclusion is made about the expediency of using the obtained data in the development of devices operating in power modes.

Investigating the effect of strontium in bone mineral density measurements of trabecular bone mimicking phantoms using quantitative ultrasound

Dual-energy x-ray absorptiometry (DXA) is the current gold standard method used for the diagnosis of osteoporosis. However, it is well-established that the presence of strontium in bone could lead to significant error in measurement of bone mineral density (BMD) and diagnosis of osteoporosis using DXA. The objectives of this study are: (1) to develop novel bone-mimicking phantoms containing different concentrations of strontium, and (2) to investigate the effect of bone strontium content on the BMD measurement using quantitative ultrasound (QUS) technique. Measurements using the research and clinical QUS systems showed a strong dependency of the BUA (broadband ultrasound attenuation) of the medium with the BMD. Moreover, increasing strontium concentrations in bone phantoms of up to 3 mol% strontium showed no effect on the BUA or the SOS values measured with either system. Therefore, the QUS technique is independent of level of bone strontium of up to 3 mol/mol [Sr/(Sr+Ca)] %.

Investigating the effect of strontium in bone mineral density measurements of trabecular bone mimicking phantoms using quantitative ultrasound

Dual-energy x-ray absorptiometry (DXA) is the current gold standard method used for the diagnosis of osteoporosis. However, it is well-established that the presence of strontium in bone could lead to significant error in measurement of bone mineral density (BMD) and diagnosis of osteoporosis using DXA. The objectives of this study are: (1) to develop novel bone-mimicking phantoms containing different concentrations of strontium, and (2) to investigate the effect of bone strontium content on the BMD measurement using quantitative ultrasound (QUS) technique. Measurements using the research and clinical QUS systems showed a strong dependency of the BUA (broadband ultrasound attenuation) of the medium with the BMD. Moreover, increasing strontium concentrations in bone phantoms of up to 3 mol% strontium showed no effect on the BUA or the SOS values measured with either system. Therefore, the QUS technique is independent of level of bone strontium of up to 3 mol/mol [Sr/(Sr+Ca)] %.

Statistical Relationship Between Strontium Content and Cooling Rate on A356 Alloy by Using Regression Analysis

Eutectic silicon modification is an important casting parameter on Al-Si alloys on the aspect of mechanical capability and energy absorption of the cast part. Chemical modifier element strontium has been used to obtain eutectic modification on Al-Si alloy commercially. On the other hand, high cooling rate on Al-Si alloys both refine dendrites and silicon phase which enhances mechanical characteristic. In order to find a statistical relationship between strontium amount and cooling rate, a special mold was designed in order to obtain different range of cooling rates in same cast part, then tensile test data of A356 alloy were analyzed in Minitab software. Therefore, after regression and analysis of variance tests have been proceeded, it was found that strontium amount is only dominant for lower cooling rates of < 0.9 oC.