Optimization of MAPbI 3 -films grown under ambient conditions on Si/SiO 2 substrates for electrical characterization of perovskite materials

Perovskite materials have recently emerged as a family of potential semiconductor materials for the fabrication of optoelectronic devices such as solar cells, light-emitting diodes, and transistors. This thesis aims to expand the available deposition and characterization techniques of the perovskite materials used by the research group I integrated. This allowed for the extraction of the doping character (n or p) of the perovskite layers deposited. To this end the deposition of MAPbI3 (MAPI) perovskite material on an Si/SiO2 substrate was thoroughly researched and optimized based on morphological, structural, and opti- cal characterization. For that, different solutions, annealing methods and spin-coating parameters were tested and analyzed with the help of characterization tools like SEM, XRD, UV-vis and PL. The film deposition was done under ambient conditions with the aim of allowing this characteriza- tion and deposition method to be made without more expensive equipment like the glovebox, where these materials are usually deposited, due to the controlled atmosphere conditions. The MAPI films showed a small number or nonexistence of pinholes with good coverage across the film. PL and UV-vis measurements revealed a 1.59 eV band gap. The devices showed a field effect mobility of 1.5 · 10!" cm2 /V.s. At lower temperature, the devices improved, and the mobility extracted was 6.1 · 10!# cm2 /V.s.Materiais de perovskite têm surgido como potencias candidatos ao fabrico de dispositivos optoelec- trónicos como células solares, díodos emissores de luz e transístores. Esta tese pretende expandir as técnicas de deposição e caracterização dos materiais de perovskite usa- dos pelo grupo de pesquisa integrado. Para esse fim, a deposição da perovskite MAPbI3 (MAPI) em um substrato de Si/SiO 2 foi totalmente analisada e otimizada baseado em caracterização morfológica, estrutural e ótica. Para isso, soluções diferentes, métodos de recozimento e parâmetros de spin-coating foram testados e analisados com a ajuda de ferramentas de caracterização como SEM, XRD, UV-vis, e PL. A deposição do filme foi feita sobre condições ambientes com o intuito de permitir a caracterização e depo- sição destes materiais sem a necessidade de equipamento mais caro como uma glove-box, onde estes materi- ais são usualmente depositados devido as condições atmosféricas controladas que o equipamento permite. Os filmes de MAPI mostraram boa cobertura com a inexistência de buracos ao longo do filme. Me- dições de PL e UV-vis revelaram um hiato energético de 1.59 eV. Os dispositivos demonstraram uma mobi- lidade de efeito de campo de 1.5 · 10!" cm2 /V.s. A temperaturas mais baixas, os dispositivos melhoraram e mostraram uma mobilidade de 6.1 · 10!# cm2 /V.s

Restructuring Biotecnol

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and EconomicsThis paper is a case-based essay on a biotechnology company – Biotecnol – which is undergoing a period of crucial decisions regarding its activity: to maintain its business as it is, meaning it will continue to provide services together with the development of proprietary products; or to decide to focus on only one area giving up on the other. In order to perform this project, I had several meetings at Biotecnol’s headquarters with both the CEO and the CFO. During these encounters we had long conversations where I had the opportunity to discuss and place all the questions and doubts regarding the history of the company in order to fully understand its background and business

Fractionally integrated moving average stable processes with long-range dependence

Long memory processes driven by Lévy noise with finite second-order moments have been well studied in the literature. They form a very rich class of processes presenting an autocovariance function that decays like a power function. Here, we study a class of Lévy processes whose second-order moments are infinite, the so-called α-stable processes. Based on Samorodnitsky and Taqqu (1994), we construct an isometry that allows us to define stochastic integrals concerning the linear fractional stable motion using Riemann-Liouville fractional integrals. With this construction, an integration by parts formula follows naturally. We then present a family of stationary SαS processes with the property of long-range dependence, using a generalized measure to investigate its dependence structure. At the end, the law of large number’s result for a time’s sample of the process is shown as an application of the isometry and integration by parts formula

Iguarivarius internationalization to Cuba

This work project provides a deeper comprehension of the Cuban current situation and suggests processual and investment choices to Iguarivarius - a Portuguese meat exporter. We analysed the macro and micro environments and we also studied the application of Just-In-Time methodology, evaluating its impacts, as well as an internationalization approach based on the Uppsala model. With business opportunities arising from an increased number of tourists that demand more and higher quality meat, we concluded that Iguarivarius should enter the market, following a sequential entry strategy with low commitment of resources, applying a logistic methodology that allows cost-efficiency and customer satisfactio

Compreensão sobre o adoecimento e o tratamento quimioterápico de crianças com câncer

Este estudo de abordagem qualitativa investigou como crianças com câncer compreendiam a doença e o tratamento. Quinze crianças com câncer, de 6 a 12 anos de idade, em tratamento quimioterápico ou finalizado há menos de cinco meses, foram entrevistadas sobre sua vivência em relação ao câncer e à quimioterapia. Para análise das entrevistas foi utilizado o método preconizado por Bardin. Identificou-se que as crianças conheciam seu diagnóstico e tinham percepção de sua gravidade. A quimioterapia foi associada à possibilidade de cura, mas crianças mais novas não compreendiam como um procedimento que gerava piora e mal-estar era a esperança de cura. Crianças mais velhas, com leucemia, relataram insegurança quanto à eficácia do tratamento. Ouvir as crianças fortaleceu a necessidade de envolvê-las nos procedimentos a fim de melhorar sua qualidade de vida

Levantamento e Análise das Redes Sem Fio IEEE 802.11 b/g/n em Campo Mourão

Este artigo descreve os resultados de um levantamento das redes sem fio locais baseadas no padrão IEEE 802.11 b/g/n na região central de Campo Mourão e de uma análise quanto a distribuição e segurança dessas redes, visando identificar padrões de configuração, uso, segurança e interferência

Contributions from specific and general factors to unique deficits: two cases of mathematics learning difficulties

Mathematics learning difficulties are a highly comorbid and heterogeneous set of disorders linked to several dissociable mechanisms and endophenotypes. Two of these endophenotypes consist of primary deficits in number sense and verbal numerical representations. However, currently acknowledged endophenotypes are underspecified regarding the role of automatic vs. controlled information processing, and their description should be complemented. Two children with specific deficits in number sense and verbal numerical representations and normal or above-normal intelligence and preserved visuospatial cognition illustrate this point. Child H.V. exhibited deficits in number sense and fact retrieval. Child G.A. presented severe deficits in orally presented problems and transcoding tasks. A partial confirmation of the two endophenotypes that relate to the number sense and verbal processing was obtained, but a much more clear differentiation between the deficits presented by H.V. and G.A. can be reached by looking at differential impairments in modes of processing. H.V. is notably competent in the use of controlled processing but has problems with more automatic processes, such as nonsymbolic magnitude processing, speeded counting and fact retrieval. In contrast, G.A. can retrieve facts and process nonsymbolic magnitudes but exhibits severe impairment in recruiting executive functions and the concentration that is necessary to accomplish transcoding tasks and word problem solving. These results indicate that typical endophenotypes might be insufficient to describe accurately the deficits that are observed in children with mathematics learning abilities. However, by incorporating domain-specificity and modes of processing into the assessment of the endophenotypes, individual deficit profiles can be much more accurately described. This process calls for further specification of the endophenotypes in mathematics learning difficulties

Mycorrhiza-like structures in rooted microshoots of Pinus pinea L.

Pinus pinea L. (stone pine) is one of the major plantation species in Iberian Peninsula, being Portugal the largest edible seed producer in the world. The induction and improvement of in vitro rhizogenesis of microshoots of Pinus pinea was developed in our laboratory using a co-culture system with ECM fungi. In the acclimation phase in mixed substrates, or in rhizotrons, anatomical and morphological studies were done to observe the evolution of the root system in microshoots from the co-culture system vs. control plants. Extensive dichotomous and coralloid branching of lateral roots occurred spontaneously in inoculated and control plants as well. Moreover, similar branching occurred in liquid culture of excised seedling roots without the presence of ECM fungi. The striking similarity of these organs with pine ectomycorrhizas prompted their anatomical analysis; however the presence of Hartig net was not confirmed. These results suggested that the development of ECM-like structures might have occurred spontaneously