Toward a better understanding of the doping mechanism involved in Mo(tfd-COCF3)3_3)_3 doped PBDTTT-c

In this study, we aim to improve our understanding of the doping mechanism involved in the polymer PBDTTT-c doped with(Mo(tfd-COCF3)3. We follow the evolution of the hole density with dopant concentration to highlight the limits of organic semiconductor doping. To enable the use of doping to enhance the performance of organic electronic devices, doping efficiency must be understood and improved. We report here a study using complementary optical and electrical characterization techniques, which sheds some light on the origin of this limited doping efficiency at high dopant concentration. Two doping mechanisms are considered, the direct charge transfer (DCT) and the charge transfer complex (CTC). We discuss the validity of the model involved as well as its impact on the doping efficiency.Comment: Accepted manuscript, J. Appl. Phy

Unravelling novel modes of antimicrobial action

Dissertation presented to obtain the Ph.D. degree in Biochemistry at the Instituto de Tecnologia Química e Biológica, Universidade Nova de LisboaThe work presented in this thesis aimed at unravelling novel modes of antimicrobial action through: i) the study of Staphylococcus aureus defences against nitric oxide, an antimicrobial weapon of the innate immune system, namely by performing the biochemical characterisation of S. aureus NO-detoxifying flavohaemoglobin and analysing the conditions under which the enzyme is operative; ii) the identification of the mechanisms beyond the antibacterial activity of azole antibiotics towards S. aureus that were shown to include the increase of endogenous reactive oxygen species triggered by the binding of imidazoles to flavohaemoglobin; and iii) the discovery of a novel type of bactericides, the carbon monoxide-releasing molecules, and identification of its potential cellular targets via analysis of the transcriptional response of Escherichia coli to CORM-2, a carbon monoxide-releasing molecule known to mimic the physiological function of carbon monoxide.(...

Towards an optical potential for rare-earths through coupled channels

The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations, defined by nuclear deformations. Proper treatment of such excitations is often essential to the accurate description of reaction experimental data. Previous works have applied different models to specific nuclei with the purpose of determining angular-integrated cross sections. In this work, we present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions in a consistent manner for neutron-induced reactions on nuclei in the rare-earth region. This specific subset of the nuclide chart was chosen precisely because of a clear static deformation pattern. We analyze the convergence of the coupled-channel calculations regarding the number of states being explicitly coupled. Inspired by the work done by Dietrich \emph{et al.}, a model for deforming the spherical Koning-Delaroche optical potential as function of quadrupole and hexadecupole deformations is also proposed. We demonstrate that the obtained results of calculations for total, elastic and inelastic cross sections, as well as elastic and inelastic angular distributions correspond to a remarkably good agreement with experimental data for scattering energies above around a few MeV.Comment: 7 pages, 6 figures. Submitted to the proceedings of the XXXVI Reuni\~ao de Trabalho de F\'{\i}sica Nuclear no Brasil (XXXVI Brazilian Workshop on Nuclear Physics), held in Maresias, S\~ao Paulo, Brazil in September 2013, which should be published on AIP Conference Proceeding Series. arXiv admin note: substantial text overlap with arXiv:1311.1115, arXiv:1311.042

Estimação jackknife ponderada do erro quadrático médio de predição do EBLUP temporal

A metodologia baseada na melhor predição linear empírica não enviesada (Empirical Best Linear Unbiased Prediction), consagrada com o acrónimo EBLUP, é muito utilizada na estimação de parâmetros para pequenos domínios. Apesar da relativa facilidade de dedução dos EBLUPs, mesmo num contexto de um modelo longitudinal, a medição da sua qualidade é um problema complexo devido à di culdade de estimação do erro quadrático médio de predição (EQMP) de tais preditores. Neste trabalho utiliza-se um estimador de parâmetros de interesse em pequenos domínios assistido pelo modelo temporal de Rao-Yu (Rao e Yu, 1994). O EBLUP temporal é apresentado e é revisitada a aproximação analítica assimptótica do EQMP do EBLUP temporal proposta por Rao e Yu (1994). Sob o modelo de Rao-Yu, é proposta uma metodologia jackknife ponderada para estimar o EQMP do EBLUP, desenvolvida a partir dos trabalhos de Chen e Lahiri (2008). Foi realizado um estudo por simulação com o objectivo de comparar o desempenho do estimador proposto com o obtido por via da aproximação analítica do EQMP

Estimação em Pequenos Domínios com modelos que combinam Informação Seccional e Cronológica

O objectivo principal deste artigo consiste na proposta de um novo estimador para parâmetros de interesse em pequenos domínios com dados de nível área

On the width of the last scattering surface

We discuss the physical effects of some accelerated world models on the width of the last scattering surface (LSS) of the cosmic microwave background radiation (CMBR). The models considered in our analysis are X-matter (XCDM) and a Chaplygin type gas. The redshift of the LSS does not depend on the kind of dark energy (if XCDM of Chaplygin). Further, for a Chaplygin gas, the width of the LSS is also only weakly dependent on the kind of scenario (if we have dark energy plus cold dark matter or the unified picture).Comment: 10 pages, 1 figure, 2 tables, accepted to IJMP