Palaeoenvironmental studies in mid-Tertiary carbonates of SW Sicily

Upper Oligocene limestones up to c. 50 m thick form disconnected outcrops within a 20 km radius of Sciacca in southwest Sicily. Two facies are present: foraminiferal grainstone-packstones (dominatedby large benthonic foraminifera, particularly Lepidocyclines), and rhodolithic algal packstone-wackestones (in which eight species of coralline red algae are present). Petrology, fauna and flora indicate deposition in cool oxygenated waters of normal marine salinity at depths of 80-250 m in tropical subtropical latitudes; the two facies representing differences in local water depth and turbulence. Rare feldspars within the limestones are diagenetic, with a variable sodic oligoclase - calcic anorthoclase composition related to localised synchronous glauconitisation. The limestones rest disconformably on Cretaceous/Eocene carbonates, locally burrowed by Thalassinoid.es paradoxioa. A basal conglomerate contains both locally derived limestone cobbles and allochthonous phosphatised Eocene pebbles. All phosphate occurs as francolite re-placing limestone. Features of major, trace and Rare Earth elements clearly differentiate these phosphates from Lower Miocene phosphorites of both southeast Sicily and the Maltese islands, which have a very similar geochemistry. Lower Miocene limestones form similar outcrops generally to the north of the Upper Oligocene limestones and comprise a glauconitic limestone facies and a sandy limestone facies. Glauconite occurs as ubiquitous pellets, its geochemistry indicating formation by a gradational alteration of calcium carbonate. Petrology indicates deposition of the sediments in an outer shelf environment. Field relations of the two facies indicate that the Western Sicily Bridge (auot,) was a positive structural feature from basal Miocene times, acting as a barrier to the arenaceous Numidian Flysch facies derived from the west-southwest. Porosity of the Oligocene - Miocene limestones has been greatly reduced by compaction and by phases of both early submarine and latesubaerial diagenesis. Southward thrusting and associated folding post Lower Miocene times have slightly transported the sequences from their original (Saccense) carbonate platform and (Sicani) basin environments.<p

Friction Stir Processing of SSM356 Aluminium Alloy

AbstractThe aim of this experiment was to improve the mechanical properties of SSM 356 aluminum alloys by friction stir processing, a solid-state technique for microstructural modification using the heat from a friction and stirring. The parameters of friction stir processing for SSM 356 aluminum alloys were studied at three different travelling speeds: 80, 120 and 160mm/min under three different rotation speeds 1320, 1480 and 1750rpm. The hardness and tensile strength properties were increased by friction stir processing. The hardness of friction stir processing was 64.55 HV which was higher than the base metal (40.58 HV). The tensile strengths of friction stir processing were increased about 11.8% compared to the base metal. The optimal processing parameter was rotation speed at 1750rpm with the travelling speed at 160mm/min. Consequently, the application of the friction stir processing is a very effective method for the mechanical improvement of semi-solid metal aluminum alloys

Developmental Origin of Oligodendrocyte Lineage Cells Determines Response to Demyelination and Susceptibility to Age-Associated Functional Decline.

Oligodendrocyte progenitors (OPs) arise from distinct ventral and dorsal domains within the ventricular germinal zones of the embryonic CNS. The functional significance, if any, of these different populations is not known. Using dual-color reporter mice to distinguish ventrally and dorsally derived OPs, we show that, in response to focal demyelination of the young adult spinal cord or corpus callosum, dorsally derived OPs undergo enhanced proliferation, recruitment, and differentiation as compared with their ventral counterparts, making a proportionally larger contribution to remyelination. However, with increasing age (up to 13 months), the dorsally derived OPs become less able to differentiate into mature oligodendrocytes. Comparison of dorsally and ventrally derived OPs in culture revealed inherent differences in their migration and differentiation capacities. Therefore, the responsiveness of OPs to demyelination, their contribution to remyelination, and their susceptibility to age-associated functional decline are markedly dependent on their developmental site of origin in the developing neural tube.A.H.C. was funded by a Wellcome Trust Integrated Training Fellowship (096384/Z/11/Z). Work in R.J.M.F.’s laboratory was funded by The UK Multiple Sclerosis Society (941) and by a core support grant from the Wellcome Trust and MRC to the Wellcome Trust – Medical Research Council Cambridge Stem Cell Institute. Work in W.D.R.’s laboratory was funded by the Medical Research Council (G0800575), the Wellcome Trust (WT100269AIA), and the European Research Council (293544).This is the final version of the article. It first appeared from Cell Press via http://dx.doi.org/10.1016/j.celrep.2016.03.06