Local structure study of vanadium pentoxide 1D-nanostructures

Vanadium pentoxide (V2O5·nH2O) 1D-nanostructures as nanowires and nanorods have been obtained by decomposition of vanadium peroxide in hydrothermal conditions. Electron microscopy, Raman spectroscopy, and X-ray absorption spectroscopy (XAS) were employed to characterize the morphology and the local structure of as-obtained samples. Scanning transmission electron microscopy (STEM) revealed that the diameter of the nanowires and nanorods were found to be 10–20 and 30–40 nm, respectively. The results demonstrated that a combination of Raman and XAS techniques allowed the accurate characterization of the local structure of V2O5 1D-nanostructures which are related to different morphologies. Analyses of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra reveals that the local structure of V in the as-obtained samples is similar to the bulk V2O5 (in orthorhombic phase), except for a higher degree of local symmetry within the structure of the VO5 square pyramid. Additionally, the nanostructures prepared by this technique present a single crystalline nature and could emit visible light at room temperature which is related to the local order of V atoms of the studied samples.FAPESPCAPESCNP

A Reescrita do riso: uma abordagem crítica de duas traduções portuguesas da obra The Importance of Being Earnest

Orientadora: Mestre Maria Helena GuimarãesO objectivo deste nosso trabalho é identificar, através de uma abordagem crítica de duas das traduções portuguesas da obra de Oscar Wilde The Importance of Being Earnest, quais os processos de fabricação do cómico, para utilizar aqui uma terminologia bergsoniana, bem como tentar sistematizar alguns dos problemas que a sua tradução coloca e apontar para estratégias que ajudem a solucionar as múltiplas dificuldades tradutivas presentes em textos marcados pela ironia e pelo humor. Cremos poder afirmar que as questões inerentes à tradução do Riso, do que de humorístico há num texto, escrito ou oral, raramente são abordadas pelos teóricos dos Estudos de Tradução, embora seja indiscutível o ser humor um fenómeno transversal a todas as culturas e os textos de cariz jocoso serem, em geral, bastante apreciados. Partimos deste pressuposto para estabelecer quer o nosso corpus de análise, quer a organização do nosso trabalho. A nossa investigação recairá, como já dissemos, sobre duas das traduções portuguesas existentes da obra de Oscar Wilde The Importance of Being Earnest, uma obra exemplar em termos da complexidade de interpretação e de tradução do humor, a saber: A Importância de Ser Earnest de Januário Leite1 Quanto Importa Ser Leal de António Pedro2 No Capítulo 2, socorrer-nos-emos das obras Le Rire, de Henri Bergson, e The Joke and its Relation to the Unconscious, de Sigmund Freud, para tentar chegar a uma definição do conceito de humor. No Capítulo 3, traçamos o quadro metodológico transdisciplinar que norteou este nosso trabalho de investigação. No Capítulo 4, tentaremos, com base na análise crítica comparada de duas traduções da peça de Oscar Wilde, The Importance of Being Earnest, apontar, pela via transdisciplinar, aqueles que consideramos ser os maiores obstáculos a uma correcta tradução do risível

One-step hydrothermal synthesis of graphene decorated V2O5 nanobelts for enhanced electrochemical energy storage

Graphene-decorated V2O5 nanobelts (GVNBs) were synthesized via a low-temperature hydrothermal method in a single step. V2O5 nanobelts (VNBs) were formed in the presence of graphene oxide, a mild oxidant, which also enhanced the conductivity of GVNBs. From the electron energy loss spectroscopy analysis, the reduced graphene oxide (rGO) are inserted into the layered crystal structure of V2O5 nanobelts, which further confirmed the enhanced conductivity of the nanobelts. The electrochemical energy-storage capacity of GVNBs was investigated for supercapacitor applications. The specific capacitance of GVNBs was evaluated using cyclic voltammetry (CV) and charge/discharge (CD) studies. The GVNBs having V2O5-rich composite, namely, V(3)G(1) (VO/GO = 3:1), showed superior specific capacitance in comparison to the other composites (V(1)G(1) and V(1)G(3)) and the pure materials. Moreover, the V(3)G(1) composite showed excellent cyclic stability and the capacitance retention of about 82% was observed even after 5000 cycles.open

Presence of excited electronic state in CAWO4 crystals provoked by a tetrahedral distortion: an experimental and theoretical investigation

By combining experimental techniques such as x-ray diffraction, Fourier transform Raman, ultraviolet-visible, x-ray absorption near edge structure,extended x-ray absorption fine structure spectroscopy, and theoretical models, a general approach to understand the relationship among photoluminescence(PL) emissions and excited electronic states in CaWO4 crystals is presented. First-principles calculations of model systems point out that the presence of stable electronic excited states (singlet) allow us to propose one specific way in which PL behavior can be achieved. In light of this result, we reexamine prior experiments on PL emissions of CaWO4.MALTA-Consolider Ingenio Program (CSD2007-00045)Fundación Bancaja (P11B2009-08)Spanish-Brazilian Program (PHB2009-0065-PC)MICINN (CTQ2009-14541-C02)Generalitat Valenciana (PROMETEO/2009/053)CAPESCNPqFAPES