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Chemical stability assessment of soft magnetic composites for biomedical applications

Powojska Anna, Niewęgłowska Joanna, Suska Sylwia, Cavadas Adelio, Mystkowska Joanna

Engineering of Biomaterials

2022

vol. 25, no. 164

2--8

Silicone-based elastic composites with a metallic filler have been strongly developed in recent years. These materials are considered applicable in many fields of science, including medicine. The advantageous mechanical parameters provided by the NdFeB micropowder reinforcement are balanced by the elasticity and biocompatibility guaranteed by the silicone matrix. So far, there have been several reports regarding such composites’ properties important from the biomedical point of view. The article deals with the physicochemical parameters of the new material for medical applications as well as the properties of the incubation liquid. The aim of the work was to determine effects of both the magnetic particles content (0, 30, 50, 70 wt%) and the incubation process under physiological conditions on the physicochemical properties of the material and the solution after incubation. The samples were incubated for various periods of time (8, 16 and 24 weeks) at the temperature of 37°C in a 0.9 wt% NaCl solution. The density, water contact angle, and water absorption of the materials were measured. The electrolytic conductivity, pH value, redox potential, surface tension, and kinematic viscosity were determined for the liquids after the materials incubation. The results obtained for pure silicone and the silicone-based composite reinforced with NdFeB microparticles were compared. The results indicate that incubation affects the samples and liquids, changing their physiochemical properties. For composites, the density decreased, which results in a noticeable concentration of the examined elements in the solutions.

Geochemistry and fluid-inclusion microthermometry of the Farsesh barite deposit, Iran

Zarasvandi A., Zaheri N., Pourkaseb H., Chrachi A., Bagheri H.

Geologos

2014

Vol. 20, No. 3

201--214

The Permian carbonate-hosted Farsesh barite deposit is located southeast of the City of Aligudarz in the prov-ince of Lorestan, Iran. Structurally, this deposit lies in the Zagros metallogenic belt and the Sanandaj-Sirjan Zone. Barite mineralisations occur as open-space filling veins, and as massive and replacement ores along fractures, faults and shear zones of the Permian carbonate host rocks. In order to determine the structure, in addition to pe-trographic and fluid-inclusions studies, an ICP-MS analysis was carried out in order to measure the major as well as the trace and rare earth elements. The Farsesh barite deposit has a simple mineralogy, of which barite is the main mineral, followed by calcite, dolomite, quartz, and opaque minerals such as Fe-oxides. Replacement of bar-ite by calcite is common and is more frequent than space-filling mineralisation. Sulphide minerals are minor and mainly consist of chalcopyrite and pyrite, which are altered by weathering to covellite, malachite and azurite. Petrographic analysis and micro-thermometry were carried out on the two-phase liquid/vapour inclu-sions in ellipsoidal or irregularly shaped minerals ranging in size from 5–10 μm. The measurements were conducted on fluid inclusions during the heating and subsequent homogenisation in the liquid phase. The low homogenisation temperatures (200–125°C) and low to moderate salinity (4.2–20 eq wt% NaCl) in-dicate that the barite had precipitated from hydrothermal basinal water with low to moderate salinity. It appears from the major and trace elements that geochemical features such as Ba and Sr enrichment in the barite samples was accompanied by depletion of Pb, Zn, Hg, Cu and Sb. The geochemistry of the rare earth elements, such as low ΣREE concentrations, LREE-enrichment chondrite-normalised REE patterns, the negative Ce and positive Eu anomalies, the low Ce/La ratio and the positive La and Gd anomalies, suggest that the Farsesh barite was deposited from hydrothermally influenced sea water. The Farsesh deposit contains low-temperature hydrothermal barite. The scatter plots of the barite (close to sea water) in different areas on the CeN/SmN versus CeN/YbN diagram support the possibility that the barite was formed from seawater-bearing hydrothermal fluids.