Exponential depletion of neutral dangling bonds density (D-0) by rare-earth doping in amorphous Si films

In this work we study the effect reduction in the density of dangling bond species D-0 states in rare-earth (RE) doped a-Si films as a function concentration for different RE-specimens. The films a-Si-1_(x) REx, RE=Y3+, Gd3+, Er3+, Lu3+) were prepared by co-sputtering and investigated by electron spin resonance (ESR) and Raman scattering experiments. According to our data the RE-doping reduces the ESR signal intensity of the D-0 states with an exponential dependence on the rare-concentration. Furthermore, the reduction produced by the magnetic rare-earths Gd3+ and Er3+ is remarkably greater than that caused by Y3+ and Lu3+, which led us to suggest an exchange-like coupling between the spin of the magnetic REs3+ and the spin of silicon neutral dangling bonds. (C) 2011 Elsevier B.V. All rights reserved.

The T-2 phase in the Nb-Si-B system studied by ab initio calculations and synchrotron X-ray diffraction

The solid solution based on Nb5Si3 (Cr5B3 structure type, D8(l), tl32, 14/mcm, No140, a=6.5767 angstrom, c=11.8967 angstrom) in the Nb-Si-B system was studied from the structural and thermodynamic point of view both experimentally and by ab initio calculations. Rietveld refinement of powder X-ray synchrotron data allowed to determine the boron to silicon substitution mechanism and the structural parameters. Ab initio calculations of different ordered compounds and selected disordered alloys allowed to obtain in addition to the enthalpy of formation of the solution, substitution mechanism and structural parameters which are in excellent agreement with the experimental data. The stability of the phase is discussed. (C) 2012 Elsevier Inc. All rights reserved.

Monte Carlo Semi-Empirical Model for Si(Li) X-Ray Detector: Differences between Nominal and Fitted Parameters.

A detailed characterization of a X-ray Si(Li) detector was performed to obtain the energy dependence of efficiency in the photon energy range of 6.4 - 59.5 keV. which was measured and reproduced by Monte Carlo (MC) simulations. Significant discrepancies between MC and experimental values were found when lhe manufacturer parameters of lhe detector were used in lhe simulation. A complete Computerized Tomagraphy (CT) detector scan allowed to find the correct crystal dimensions and position inside the capsule. The computed efficiencies with the resulting detector model differed with the measured values no more than 10% in most of the energy range.

Influence of Equatorial Diatom Processes on Si Deposition and Atmospheric CO(2) Cycles at Glacial/Interglacial Timescales

The causes of the glacial cycle remain unknown, although the primary driver is changes in atmospheric CO(2), likely controlled by the biological pump and biogeochemical cycles. The two most important regions of the ocean for exchange of CO(2) with the atmosphere are the equatorial Pacific and the Southern Ocean ( SO), the former a net source and the latter a net sink under present conditions. The equatorial Pacific has been shown to be a Si(OH)(4)-limited ecosystem, a consequence of the low source Si(OH)(4) concentrations in upwelled water that has its origin in the SO. This teleconnection for nutrients between the two regions suggests an oscillatory relationship that may influence or control glacial cycles. Opal mass accumulation rate (MAR) data and delta(15)N measurements in equatorial cores are interpreted with predictions from a one- dimensional Si(OH)(4)-limited ecosystem model (CoSINE) for the equatorial Pacific. The results suggest that equatorial Pacific surface CO(2) processes are in opposite phase to that of the global atmosphere, providing a negative feedback to the glacial cycle. This negative feedback is implemented through the effect of the SO on the equatorial Si(OH)(4) supply. An alternative hypothesis, that the whole ocean becomes Si(OH)(4) poor during cooling periods, is suggested by low opal MAR in cores from both equatorial and Antarctic regions, perhaps as a result of low river input. terminations in this scenario would result from blooms of coccolithophorids triggered by low Si(OH)(4) concentrations.

Affetti musici : ne quali si contengono motetti a una, 2, 3, 4, & sei voci ; co'l modo per concertarli nel basso per l'organo

7 Stb.: Canto, Alto, Tenore, Basso, Quinto, Sesta parte, Organo

Si and SixGe1-x NWs studied by Raman spectroscopy

Group IV nanostructures have attracted a great deal of attention because of their potential applications in optoelectronics and nanodevices. Raman spectroscopy has been extensively used to characterize nanostructures since it provides non destructive information about their size, by the adequate modeling of the phonon confinement effect. The Raman spectrum is also sensitive to other factors, as stress and temperature, which can mix with the size effects borrowing the interpretation of the Raman spectrum. We present herein an analysis of the Raman spectra obtained for Si and SiGe nanowires; the influence of the excitation conditions and the heat dissipation media are discussed in order to optimize the experimental conditions for reliable spectra acquisition and interpretation.

Opus sermonum de aduentu / religiosissimi viri, artiu[m] ac sacre theologie in Parisien[si] academia quondam professoris, et euangelice doctrine co[n]cionatoris celebratissimi Ioannis Raulini ordinis Cluniacen[sis], dilige[n]ti quidem cura mendis o[mn]ibu

Raulin, Jean (O.S.B.), 1443-1514. Itinerarium paradisi religiosissimi patris artium ac sacre pagine p[ro]fessoris Parisien[sis] diuiniq[ue] verbi declamatoris facundissimi magistri Ioannis Raulin ordinis Cluniace[nsis], co[m]plecte[n]s sermones de Penit

Opus sermonum de aduentu / religiosissimi viri, artiu[m] ac sacre theologie in Parisien[si] academia quondam professoris, et euangelice doctrine co[n]cionatoris celebratissimi Ioannis Raulini ordinis Cluniacen[sis], dilige[n]ti quidem cura mendis o[mn]ibu

Pie de imp. tomado del colofón

A DIALÉTICA ENTRE O CONHECIMENTO DE SI E O CONHECIMENTO DE DEUS NO LIVRO X DAS CONFISSÕES DE SANTO AGOSTINHO

O conhecimento de si e o conhecimento de Deus estabelecem uma relação fundamental na obra mais conhecida de Agostinho, Confissões. O livro X das Confissões contém as narrativas centrais para a análise da dialética entre o conhecimento de si e o conhecimento de Deus, que tem como chave de leitura a memória para a constituição do cogito existencial. É examinada a relação que existe, no texto narrativo de Agostinho, entre a interpretação da Escritura e a constituição do si, em que há aspectos do discurso interior e abordagem no quadro da teoria narrativa que é dada a partir do conceito de identidade narrativa. A constituição do si é desenvolvida na dialética interna do personagem entre a afirmação de si e a negação de si, que apresenta a imanência do homem como característica pessoal e, ao mesmo tempo, o desejo de transcendência daquilo que o ser humano tem de mais íntimo em relação a Deus. Esta é uma análise da tensão existente entre a visão que o ser humano tem da consciência de si e a que ele tem de Deus, na busca pela felicidade.(AU)

A DIALÉTICA ENTRE O CONHECIMENTO DE SI E O CONHECIMENTO DE DEUS NO LIVRO X DAS CONFISSÕES DE SANTO AGOSTINHO

O conhecimento de si e o conhecimento de Deus estabelecem uma relação fundamental na obra mais conhecida de Agostinho, Confissões. O livro X das Confissões contém as narrativas centrais para a análise da dialética entre o conhecimento de si e o conhecimento de Deus, que tem como chave de leitura a memória para a constituição do cogito existencial. É examinada a relação que existe, no texto narrativo de Agostinho, entre a interpretação da Escritura e a constituição do si, em que há aspectos do discurso interior e abordagem no quadro da teoria narrativa que é dada a partir do conceito de identidade narrativa. A constituição do si é desenvolvida na dialética interna do personagem entre a afirmação de si e a negação de si, que apresenta a imanência do homem como característica pessoal e, ao mesmo tempo, o desejo de transcendência daquilo que o ser humano tem de mais íntimo em relação a Deus. Esta é uma análise da tensão existente entre a visão que o ser humano tem da consciência de si e a que ele tem de Deus, na busca pela felicidade.(AU)