74 research outputs found

    On the qq-parameter spectrum of generalized information-entropy measures with no cut-off prescriptions

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    After studying some properties of the generalized exponential and logarithmic function, in particular investigating the domain where the first maintains itself real and positive, and outlining how the known dualities q1qq \leftrightarrow \frac{1}{q} and q2qq \leftrightarrow 2-q play an important role, we shall examine the set of q-deforming parameters that allow generalized canonical maximum entropy probability distributions (MEPDs) to maintain itself positive and real without cut-off prescriptions. We determine the set of q-deforming parameters for which a generalized statistics with discrete but unbound energy states is possible.Comment: 12 pages, 4 figure

    Contradições entre as políticas públicas do “PCN” e “PNLD 2011”: uma análise da arqueologia brasileira nos livros didáticos de história

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    Dissertação apresentada ao Programa de PósGraduação Stricto Sensu em Educação - Mestrado Acadêmico em Educação, vinculado ao Núcleo de Ciências Humanas da Universidade Federal de Rondônia, como requisito para a obtenção do grau de Mestre em Educação.A pesquisa examina os livros didáticos de História destinados aos 6ºs anos (5ª série) do Ensino Fundamental, aprovados pelo Governo Federal e disponibilizados por meio do Programa Nacional do Livro Didático (PNLD) do ano de 2011. Tem por escopo a verificação da contradição entre aquilo que é proclamado nos Parâmetros Curriculares Nacionais de História (PCN) e o que é tratado sobre o passado pré- colonial brasileiro nos livros distribuídos pelo Governo Federal. A partir dos resultados das contradições, os pesquisadores analisam se aquilo que é rezado nos diplomas legais da educação brasileira, no que concerne à formação da identidade nacional, é possibilitado por meio dos livros didáticos

    Metal-Dependent DNA Recognition and Cell Internalization of Designed, Basic Peptides

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    A fragment of the DNA basic region (br) of the GCN4 bZIP transcription factor has been modified to include two His residues at designed i and i+4 positions of its N-terminus. The resulting monomeric peptide (brHis2) does not bind to its consensus target DNA site (5′-GTCAT-3′). However, addition of Pd(en)Cl2 (en, ethylenediamine) promotes a high-affinity interaction with exquisite selectivity for this sequence. The peptide–DNA complex is disassembled by addition of a slight excess of a palladium chelator, and the interaction can be reversibly switched multiple times by playing with controlled amounts of either the metal complex or the chelator. Importantly, while the peptide brHis2 fails to translocate across cell membranes on its own, addition of the palladium reagent induces an efficient cell internalization of this peptide. In short, we report (1) a designed, short peptide that displays highly selective, major groove DNA binding, (2) a reversible, metal-dependent DNA interaction, and (3) a metal-promoted cell internalization of this basic peptideThis work has received financial support from the MINECO (SAF2013-41943-R, SAF2016-76689-R, and CTQ2015-70698-R), the Xunta de Galicia (2015-CP082, ED431C 2017/19, and Centro Singular de Investigación de Galicia Accreditation 2016–2019, ED431G/09), the European Union (European Regional Development Fund, ERDF), and the European Research Council (Advanced Grant No. 340055). Support of COST CM1306 and the orfeo-cinqa network are also acknowledged. J.R. thanks the Xunta de Galicia for a Ph.D. fellowship. We also wish to acknowledge the generous support by the Fundación AECC (IDEAS197VAZQ grant)S

    Intake of Proton-Pump Inhibitors and Gastric Cancer within the Stomach Cancer Pooling (StoP) Project

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    Background: A potential association between proton-pump inhibitors (PPI) and gastric cancer remains undefined. Thus, we aimed to evaluate such association within the Stomach cancer Methods: Data from five case-control studies of the StoP Project were included (1,889 cases and 6,517 controls). We assessed the impact of different exposure definitions, specifically any reported use of PPIs and exposure definitions based on the duration of PPI intake. Additionally, we modeled the dose-response relationship between the cumulative duration of PPI intake and gastric cancer. Results: Significant associations between PPI intake and gastric cancer, both overall and in the stratified analyses, were limited to exposure definitions based on short durations of intake. The overall odds ratio (OR) for any reported PPI intake was 1.78 [95% confidence interval (CI): 0.76-4.14]. In the dose-response analysis, the ORs of gastric cancer were found to be higher for short durations of PPI intake (6 months: OR 3.26; 95% CI: 2.40-4.42; one year: OR 2.14; 95% CI: 1.69-2.70; 2 years: OR 1.50; 95% CI: 1.22-1.85; 3 years: OR 1.27; 95% CI: 1.03-1.56), with the association becoming not significant for durations longer than 3 years. Conclusions: Our findings suggest that the observed association between PPIs and gastric cancer might be mainly due to reverse causality. Impact: The results of this study suggest that PPIs area safe thera-peutic choice regarding their effect on the occurrence of gastric cancer. See related commentary by Richman and Leiman, p. 112

    Optoelectronic simulations for novel light management concepts in Cu(In,Ga)Se2 solar cells

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    One of the trends making its way through the Photovoltaics (PV) industry, is the search for new application possibilities. Cu(In,Ga)Se2 (CIGS) thin film solar cells stand out due to their class leading power conversion efficiency of 23.35 %, flexibility, and low cost. The use of sub-μm ultrathin CIGS solar cells has been gaining prevalence, due to the reduction in material consumption and the manufacturing time. Precise CIGS finite-difference time-domain (FDTD) and 3D-drift diffusion baseline models were developed for the Lumerical suite and a 1D electrical model for SCAPS, allowing for an accurate description of the optoelectronic behavior and response of thin and ultrathin CIGS solar cells. As a result, it was possible to obtain accurate descriptions of the optoelectronic behavior of thin and ultrathin solar cells, and to perform an optical study and optimization of novel light management approaches, such as, random texturization, photonic nanostructures, plasmonic nanoparticles, among others. The developed light management architectures enabled to push the optical performance of an ultrathin solar cell and even surpass the performance of a thin film solar cell, enabling a short-circuit current enhancement of 6.15 mA/cm2 over an ultrathin reference device, without any light management integrated.publishe

    On the importance of joint mitigation strategies for front, bulk, and rear recombination in ultrathin Cu(In,Ga)Se2 solar cells

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    Several optoelectronic issues, such as poor optical absorption and recombination limit the power conversion efficiency of ultrathin Cu(In,Ga)Se2 (CIGS) solar cells. To mitigate recombination losses, two combined strategies were implemented: a Potassium Fluoride (KF) Post-Deposition Treatment (PDT) and a rear interface passivation strategy based on an Aluminium Oxide (Al2O3) point contact structure. The simultaneous implementation of both strategies is reported for the first time on ultrathin CIGS devices. Electrical measurements and 1-D simulations demonstrate that, in specific conditions, devices with only KF-PDT may outperform rear interface passivated based devices. By combining KF-PDT and rear interface passivation, an enhancement in open-circuit voltage of 178 mV is reached over devices that have a rear passivation only and of 85 mV over devices with only a KF-PDT process. Time-Resolved Photoluminescence measurements showed the beneficial effects of combining KF-PDT and the rear interface passivation at decreasing recombination losses in the studied devices, enhancing charge carrier lifetime. X-ray photoelectron spectroscopy measurements indicate the presence of a In and Se rich layer that we linked to be a KInSe2 layer. Our results suggest that when bulk and front interface recombination values are very high, they dominate and individual passivation strategies work poorly. Hence, this work shows that for ultrathin devices, passivation mitigation strategies need to be implemented in tandem.publishe

    On the importance of joint mitigation strategies for front, bulk, and rear recombination in ultrathin Cu(In,Ga)Se2 solar cells

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    Several optoelectronic issues, such as poor optical absorption and recombination limit the power conversion efficiency of ultrathin Cu(In,Ga)Se2 (CIGS) solar cells. To mitigate recombination losses, two combined strategies were implemented: a Potassium Fluoride (KF) Post-Deposition Treatment (PDT) and a rear interface passivation strategy based on an Aluminium Oxide (Al2O3) point contact structure. The simultaneous implementation of both strategies is reported for the first time on ultrathin CIGS devices. Electrical measurements and 1-D simulations demonstrate that, in specific conditions, devices with only KF-PDT may outperform rear interface passivated based devices. By combining KF-PDT and rear interface passivation, an enhancement in open-circuit voltage of 178 mV is reached over devices that have a rear passivation only and of 85 mV over devices with only a KF-PDT process. Time-Resolved Photoluminescence measurements showed the beneficial effects of combining KF-PDT and the rear interface passivation at decreasing recombination losses in the studied devices, enhancing charge carrier lifetime. X-ray photoelectron spectroscopy measurements indicate the presence of a In and Se rich layer that we linked to be a KInSe2 layer. Our results suggest that when bulk and front interface recombination values are very high, they dominate and individual passivation strategies work poorly. Hence, this work shows that for ultrathin devices, passivation mitigation strategies need to be implemented in tandem.publishe

    Variação estacional do óleo essencial em arnica (Lychnofora ericoides Mart.)

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    Lychnophora ericoides Mart., comumente conhecida como arnica, vegeta em regiões de campos rupestres e pertence à família Asteraceae. No aspecto fármaco-terapêutico é empregada como antiinflamatório e anestésico, entre outras aplicações. Com o objetivo de encontrar o melhor período para a colheita, surgiu a necessidade de traçar o perfil sazonal do conteúdo do óleo essencial dessa planta, até o momento não identificado. Para isso, foram escolhidas duas áreas preservadas nos municípios de Cristalina e de Vianópolis, ambos situados no Estado de Goiás, Brasil. As coletas foram efetuadas no período entre julho de 2001 e julho de 2002. As amostras de cada acesso foram submetidas a extração por hidrodestilação, tendo sido encontrados 71 componentes no óleo essencial dessa planta. As amostras de óleo essencial extraídas foram analisadas por cromatografia gasosa acoplada a espectrometria de massa (CG-EM). As plantas coletadas em Cristalina apresentaram maiores teores de óleo em comparação com as de Vianópolis, com as maiores porcentagens nos meses de setembro de 2001 e novembro de 2001. Não se observou diferença significativa no teor de óleo das plantas em Vianópolis

    Cu(In,Ga)Se2 based ultrathin solar cells: the pathway from lab rigid to large scale flexible technology

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    For the first time, the incorporation of interface passivation structures in ultrathin Cu(In,Ga)Se2 (CIGS) based solar cells is shown in a flexible lightweight stainless-steel substrate. The fabrication was based on an industry scalable lithography technique - nanoimprint lithography (NIL) - for a 15x15 cm2 dielectric layer patterning, needed to reduce optoelectronic losses at the rear interface. The nanopatterning schemes are usually developed by lithographic techniques or by processes with limited scalability and reproducibility (nanoparticle lift-off, spin-coating, etc). However, in this work the dielectric layer is patterned using NIL, a low cost, large area, high resolution, and high throughput technique. To assess the NIL performance, devices with a NIL nanopatterned dielectric layer are benchmarked against electron-beam lithography (EBL) patterning, using rigid substrates. Up to now, EBL is considered the most reliable technique for patterning laboratory samples. The device patterned by NIL shows similar light to power conversion efficiency average values compared to the EBL patterned device - 12.6 % vs 12.3 %, respectively - highlighting the NIL potential for application in the solar cell sector. Moreover, the impact of the lithographic processes, such as different etch by-products, in the rigid solar cells’ figures of merit were evaluated from an elemental point of view via X-ray Photoelectron Spectroscopy and electrically through a Solar Cell Capacitance Simulator (SCAPS) fitting procedure. After an optimised NIL process, the device on stainless-steel achieved an average power conversion efficiency value of 11.7 % - a slightly lower value than the one obtained for the rigid approach, due to additional challenges raised by processing and handling steel substrates, even though scanning transmission electron microscopy did not show any clear evidence of impurity diffusion towards the absorber. Notwithstanding, time-resolved photoluminescence results strongly suggested the presence of additional non-radiative recombination mechanisms in the stainless-steel absorber, which were not detected in the rigid solar cells, and are compatible with elemental diffusion from the substrate. Nevertheless, bending tests on the stainless-steel device demonstrated the mechanical stability of the CIGS-based device up to 500 bending cycles.This work was funded in part by the Fundação para a Ciência e a Tecnologia (FCT) under Grants 2020.04564.BD, IF/00133/2015, PD/BD/142780/2018, SFRH/BD/146776/2019, UIDB/04564/2020 and UIDP/04564/2020, 2020.07073.BD, as well as through the projects NovaCell (PTDC/CTMCTM/28075/2017), CASOLEM (028917) “Correlated Analysis of Inorganic Solar Cells in and outside an Electron Microscope”, and InovSolarCells (PTDC/FISMAC/29696/2017) co-funded by FCT and the ERDF through COMPETE2020. And by the European Union's Horizon 2020 research and innovation 15 programme under the grants agreements N°. 720887 (ARCIGS-M project) and grand agreement N°.715027 (Uniting PV). The Special Research Fund (BOF) of Hasselt University is also acknowledged. P. Salomé and P. A. Fernandes would like to acknowledge FCT for the support of the project FCT UIDB/04730/2020. This work was developed within the scope of the project i3N, UIDB/50025/2020 & UIDP/50025/2020, financed by national funds through the FCT/MEC. The authors also acknowledge the support of Carlos Calaza in the fabrication for the 200 mm Si point contact stamp.info:eu-repo/semantics/publishedVersio
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