Search results for " composition"
showing 10 items of 1437 documents
Formation and migration of oxygen vacancies in La1−xSrxCo1−yFeyO3−δperovskites: insight from ab initio calculations and comparison with Ba1−xSrxCo1−y…
2013
The formation and migration of oxygen vacancies in the series of (La,Sr)(Co,Fe)O3−δ perovskites, which can be used as mixed conducting SOFC cathode materials and oxygen permeation membranes, are explored in detail by means of first principles density functional calculations. Structure distortions, charge redistributions and transition state energies during the oxygen ion migration are obtained and analyzed. Both the overall chemical composition and vacancy formation energy are found to have only a small impact on the migration barrier; it is rather the local cation configuration which affects the barrier. The electron charge transfer from the migrating O ion towards the transition metal ion…
Decomposition studies of group 6 hexacarbonyl complexes. Part 1: Production and decomposition of Mo(CO)6 and W(CO)6
2015
Abstract Chemical studies of superheavy elements require fast and efficient techniques, due to short half-lives and low production rates of the investigated nuclides. Here, we advocate for using a tubular flow reactor for assessing the thermal stability of the Sg carbonyl complex – Sg(CO)6. The experimental setup was tested with Mo and W carbonyl complexes, as their properties are established and supported by theoretical predictions. The suggested approach proved to be effective in discriminating between the thermal stabilities of Mo(CO)6 and W(CO)6. Therefore, an experimental verification of the predicted Sg–CO bond dissociation energy seems to be feasible by applying this technique. By in…
Perlecan Maintains microvessel integrity in vivo and modulates their formation in vitro
2012
Perlecan is a heparan sulfate proteoglycan assembled into the vascular basement membranes (BMs) during vasculogenesis. In the present study we have investigated vessel formation in mice, teratomas and embryoid bodies (EBs) in the absence of perlecan. We found that perlecan was dispensable for blood vessel formation and maturation until embryonic day (E) 12.5. At later stages of development 40% of mutant embryos showed dilated microvessels in brain and skin, which ruptured and led to severe bleedings. Surprisingly, teratomas derived from perlecan-null ES cells showed efficient contribution of perlecan-deficient endothelial cells to an apparently normal tumor vasculature. However, in perlecan…
Considerations on the modelling and optimisation of resolution of ionisable compounds in extended pH-range columns
2005
Abstract The problems associated to the modelling and optimisation of the chromatographic resolution of mixtures involving ionisable solutes at varying pH and acetonitrile content are discussed. Several retention models that separate the contributions of solute, column and stationary phase, were used. The retention was predicted with low errors in large pH domains (2–12), which was an essential requirement to face the optimisation of resolution. The selected mixture was particularly problematic under the viewpoint of resolution, owing to the excessively diverse acid–base behaviour of solutes. This variety led to sudden drops in retention at different pH for each solute, yielding numerous pe…
Metabolic profiling of ripe olive fruit in response to moderate water stress
2013
a b s t r a c t The concentrations of different metabolites in olive (Olea europaea (L.)) fruit at harvest can be affected by water availability, with significant consequences on the composition and the quality of the resulting oil. The aim of the present study was to profile the metabolic composition of ripe olives (cv. Cipressino) grown under water-stress and irrigated conditions applied during the last part of the fruit developmental cycle (from pit hardening to commercial harvest). The imposed conditions resulted in a moderate water stress (−3.5 MPa) at the end of the experimental period. Samples (pulp + skin) of fruit collected at the stage of complete epicarp pigmentation were analyze…
The effect of complementary irrigation on fruit growth, ripening pattern and oil characteristics of olive (Olea europaea L.) cv. Carolea
1996
SummaryComplementary irrigation, 80 mm, distributed only during the third stage of fruit development, delayed ripening time and increased fruit size and oil content for fruits of the olive cv. Carolea. Prolonged water deficit reduced fruit growth, oil accumulation rate, K content of the fruit and enhanced ripening and pre-harvest fruit drop. Harvest time affected oil characteristics more than the water availability. Fatty acid composition was not affected by the water regime but polyphenol content increased and alcohol content decreased in the oil produced by irrigated trees.
U-Pb zircon and Sm-Nd dating of Moldanubian H P /H T granulites from South ohemia, Czech Republic
1994
Conventional multigrain U-Pb systematics of zircon and single-grain evaporation data of zircons in combination with Nd model ages are presented for pyroxene-free, felsic, garnetiferous granulites and orthopyroxene-bearing granulites of felsic, mafic and intermediate composition from the Blansky Les mountains granulite complex, S Bohemia. Zircons from mafic and intermediate granulites yield Concordia intercept ages between 346 ± 5 and 351 ± 6 Ma as well as a single-grain evaporation age of 346 ± 12 Ma. These ages define the time of Variscan high-grade metamorphism in S Bohemia and are supported by an internal Sm-Nd garnet-zircon-plagioclase-whole rock isochron age of 343 ± 21 Ma. Euhedral zi…
Chemical composition of the essential oil from the aerial parts of Ononis reclinata L. (Fabaceae) grown wild in Sicily
2016
In the present study, the chemical composition of the essential oil from aerial parts of Ononis reclinata L., a species not previously investigated, collected in Sicily was evaluated by GC and Gas chromatography-Mass spectrometry. The main components of O. reclinata were menthone (43.6%), isopimpinellin (38.4%) and pulegone (11.2%). The comparison with other studied oils of genus Ononis showed a peculiar and characteristic profile.
Geochemical constraints on volatile sources and subsurface conditions at Mount Martin, Mount Mageik, and Trident Volcanoes, Katmai Volcanic Cluster, …
2017
Abstract We use the chemical and isotopic composition of volcanic gases and steam condensate, in situ measurements of plume composition and remote measurements of SO2 flux to constrain volatile sources and characterize subvolcanic conditions at three persistently degassing and seismically active volcanoes within the Katmai Volcanic Cluster (KVC), Alaska: Mount Martin, Mount Mageik and Trident. In situ plume measurements of gas composition were collected at all three volcanoes using MultiGAS instruments to calculate gas ratios (e.g. CO2/H2S, SO2/H2S and H2O/H2S), and remote measurements of SO2 column density were collected from Mount Martin and Mount Mageik by ultraviolet spectrometer system…
Die Musikalische Composition in Unterrichts-Briefen
1906
Rokraksta litogrāfija