Araracuara, un nuevo género de Rhamnaceae de la Amazonía colombiana

Se describe e ilustra Araracuara Fern. Alonso, un nuevo género de la familia Rhamnaceae conocido tan sólo de las mesetas de arenisca de la Amazonía colombiana. Se discuten sus posibles afinidades en la familia y se sugiere que estaríamos ante un género relíctico, relacionado con el pantropical Colubrina y en menor medida con el amazónico Ampelozizyphus. Se incluye una clave para los géneros de Rhamnaceae de Colombia y un apéndice con una muestra representativa de especies de los géneros estudiados, algunos de ellos pobremente documentados de territorio colombiano.Peer reviewe

Electronic structure and chemical bonding in Ti4SiC3 investigated by soft x-ray emission spectroscopy and first principle theory

The electronic structure in the new transition metal carbide Ti4SiC3 has been investigated by bulk-sensitive soft x-ray emission spectroscopy and compared to the well-studied Ti3SiC2 and TiC systems. The measured high-resolution Ti L, C K and Si L x-ray emission spectra are discussed with ab initio calculations based on density-functional theory including core-to-valence dipole matrix elements. The detailed investigations of the Ti-C and Ti-Si chemical bonds provide increased understanding of the physical properties of these nanolaminates. A strongly modified spectral shape is detected for the buried Si monolayers due to Si 3p hybridization with the Ti 3d orbitals. As a result of relaxation of the crystal structure and the charge-transfer from Ti (and Si) to C, the strength of the Ti-C covalent bond is increased. The differences between the electronic and crystal structures of Ti4SiC3 and Ti3SiC2 are discussed in relation to the number of Si layers per Ti layer in the two systems and the corresponding change of materials properties.Comment: 12 pages, 7 figures, 1 tabl

Redescription of the Deep-Sea Cirrate Octopod Cirroteuthis magna Hoyle, 1885, and Considerations on the Genus Cirroteuthis (Mollusca: Cephalopoda)

31 pages, 29 figures, 4 tables, 1 appendix.The deep-living octopod Cirroteuthis magna Hoyle, 1885 is redescribed, based on the only three specimens known of the species: a mature female (holotype) captured in the south Indian Ocean between Prince Edward and Crozet islands at 2557 m and two specimens, one submature female and one mature male, recently captured in the central Atlantic at 1300 and 3351 m depth, respectively. Video images from the capture of the latter specimen were recorded. This species is characterized by its very great size (to 1300 mm TL), making it the largest known cirrate octopod; butterfly-like shell with open wings; very voluminous eyes with large lenses; arm length 73-79% of the total length; primary web inserted at different levels on the dorsal and ventral ends of the dorso- and ventrolateral arms on both sides, and at the same level on both ends of the dorsal and ventral arms; each arm is independent of the primary web, and is connected with it by a single vertical membrane or intermediate web that is attached along the dorsum of the arm; absence of nodule at the fusion point of both webs. Very large cirri, the first cirri commencing between the 4th and 5th suckers, with three types of suckers on all the arms; cylindro-conical form and those with the acetabulum highly deformable on the first 2/3 of arms and barrel-like on the rest of the arm; absence of particularly enlarged suckers. C. magna is compared with C. muelleri and other related species. Sperm sacs and spermatozoids from C. magna and C. muelleri are described and compared. The Cirroteuthis genus is reviewed and a diagnosis is proposed. This study confirms that the members of the Cirroteuthidae family show several unusual features of great interest.During this study one of the authors (R.V.) was supported by a post-doctoral fellowship from the Spanish Ministery of Education and Science.Peer reviewe

Ti3SiC2-formation during Ti–C–Si multilayer deposition by magnetron sputtering at 650 °C

Titanium Silicon Carbide films were deposited from three separate magnetrons with elemental targets onto Si wafer substrates. The substrate was moved in a circular motion such that the substrate faces each magnetron in turn and only one atomic species (Ti, Si or C) is deposited at a time. This allows layer-by-layer film deposition. Material average composition was determined to Ti0.47Si0.14C0.39 by energy-dispersive X-ray spectroscopy. High-resolution transmission electron microscopy and Raman spectroscopy were used to gain insights into thin film atomic structure arrangements. Using this new deposition technique formation of Ti3SiC2 MAX phase was obtained at a deposition temperature of 650 °C, while at lower temperatures only silicides and carbides are formed. Significant sharpening of Raman E2g and Ag peaks associated with Ti3SiC2 formation was observed

Regulating Sustainable Finance in Capital Markets: A Perspective from Socially Embedded Decentered Regulation

We present an ab initio theoretical analysis of the temperature-dependent stability of inherently nanolaminated (Cr1−xMnx)2AlC. The results indicate energetic stability over the composition range x = 0.0 to 0.5 for temperatures ≥600 K. Corresponding thin film compounds were grown by magnetron sputtering from four elemental targets. X-ray diffraction in combination with analytical transmission electron microscopy, including electron energy-loss spectroscopy and energy dispersive x-ray spectroscopy analysis, revealed that the films were epitaxial (0001)-oriented single-crystals with x up to 0.16.Funding Agencies|European Research Council under the European Community|258509227754|Knut and Alice Wallenberg Foundation||Swedish Research Council|||DFG-SPP 1299|</p