1,723,597 research outputs found
Solvent effect on the optical properties of [(NH3)(5)Ru-pyrazine](+m) (m=2,3) complexes by ab initio calculations
No full textWe have carried out a study, by ab initio methods, of the solvent effect on [(NH3)(5)Ru-pyrazine](m+) (m=2 and 3) complexes, which are of interest as basic units of metallic chains with potential application in molecular electronics and photonics. We have performed multireference configuration interaction (CI) calculations in which solvent effects are included by the Polarizable Continuum Model. A new method for the estimate of the size of the cavities in this approach, which has proven to be suitable for the specific case under study, is also proposed. Our calculations account for the red shift of the metal-to-ligand charge transfer band, observed experimentally for the Ru(LI) compound as the solvent donor number increases, and furnish an explanation with a solid theoretical foundation. For the Ru(III) compound we find that the ground state configuration is different in vacuum and in electron donor solvents. (C) 1998 American Institute of Physics. [S0021-9606(98)31243-X]
The Silurian of the External Nappes (southeastern Sardinia)
No full textThe most complete and best known Silurian succession of southeastern Sardinia is exposed in the Gerrei tectonic Unit. The Silurian sequence starts with Rhuddanian-lowermost Gorstian black graptolitic shales (Lower Graptolitic Shales), followed by a lower Gorstian-end Pridoli nodular calcareous unit (Ockerkalk). Graptolitic shales (Upper Graptolitic Shales) document the Lower Devonian. An integrated scheme of graptolite and conodont biozonation, compiled from Sardic data, is provided
Valutazione delle prestazioni dimensionali della tecnologia spin casting con stampi al silicone
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Theoretical study of the absorption spectrum of [(NH3)(5)Ru-(4,4 '-bipyridine)](2+) in solution
No full textThe absorption spectrum of [(NH3)(5)Ru-(4,4'-bipyridine)](2+) in the visible has been studied by ab initio methods, taking into account solvent effects by means of the polarizable continuum model and performing extensive CI calculations. The dependence of the ground and lowest excited states has been investigated as a function of the torsional angle between the two pyridine rings of bipyridine in vacuo, as well as in nitromethane, water, and dimethylsulfoxide. Including the torsion, the position and profile of the metal-to-ligand charge transfer band has also been computed. The results obtained in water are in good agreement with the only experimental result available, while they an predictive in the two other solvents
Little pieces of mystery from the Silurian of the Dingle Peninsula, Ireland
Full text linkThree-dimensionally preserved fragments of the enigmatic organism Sandvikina, previously reported from the Silurian of Ireland, Scotland and Scandinavia, were recovered from the original Irish material that had revealed the problematic in thin sections. The new specimens derive from conodont residue and document silicified sectors of the distal part of the skeleton. A different pattern characterizes the outer and inner walls, with an external net-like reticulated and an internal continuous and apparently imperforate framework, getting therefore a filter-like feeding system function highly improbable
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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