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In the recent decade, magnetic compounds have attracted a great deal of interest due to their magnetic behaviour allowing them to be a good candidate for catalytic and biomedical applications. However, the problem of these materials is their aggregation during the synthesis process, and then problems related to particle size. To overcome these problems, an efficient assembly of magnetic nanoparticles with layered double hydroxides compound systems (Fe-NPs@LDH and M/Fe-NPs@LDH; M = Mn, Zn) were prepared by simple co-precipitation process. Analytical tools including TG-dTG, XRD, FTIR, SEM/EDX and BET were used to investigate the thermal, morphological, structural and textural properties of the studied materials. The magnetic properties of the composite were investigated by mean 57Fe Mossbauer spectrometry. [ABSTRACT FROM AUTHOR]

Abstract: The strengthening mechanism based on the formation of precipitates (Guinier-Preston (GP) zones) during decomposition of a metastable supersaturated solid solution is stable and effective below temperatures, which are typically overcome in the piston region facing the combustion chamber. Therefore, pistons experience a progressive loss of strength due to over-aging during service. This contribution reports of a structural investigation on a eutectic AlSi12CuNiMg alloy before and after fatigue testing at high temperatures (up to 350°C). Metallography, color etching, SEM and TEM are used to elucidate the following aspects: 1) the structural features of the alloy (dendrites of α−phase, primary Si particle size and distribution, morphology and distribution of intermetallic phases); 2) the evolution of the strengthening mechanism (GP zones) with high temperature exposure. [Copyright &y& Elsevier]

Abstract: A 13-step alkaline permanganate degradation of Bulgarian oil shale kerogen concentrate at ambient temperature was carried out. A high yield of oxidation products (90.1%) and a low yield of gaseous products (2.79%) were obtained. IR and 1H NMR spectroscopic studies have shown that two significantly different types of high molecular products are present in kerogen. Further oxidation of these structures leads to the formation of low molecular aliphatic and aromatic acids, proven by gas chromotography (GC) and gas chromatography-mass spectrometry (GC-MS). The data obtained at these mild conditions allow us to acquire detailed information about the aromatic structures and polymethylene chain lengths in kerogen. The 5-step oxidation of the kerogen at 90°C provides information about stable aromatic structures. Soluble and insoluble polyfunctional acids in acid medium have close molecular masses and spectral characteristics. The amount of benzene and naphthalene carboxylic acids is 11.3% of the organic matter of the oil shale. [Copyright &y& Elsevier]