60 research outputs found

    Process simulation and optimization of biomass fast pyrolysis

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    Die intensive Nutzung fossiler Brennstoffe für die Energie-, Kraftstoff- und Rohstoffproduktion hat globale und langanhaltende ökologische, politische und wirtschaftliche Auswirkungen, von denen ärmere Bevölkerungsschichten und Länder ohne einfachen Zugang zu diesen Rohstoffen außerordentlich stark betroffen sind. Jedem ist klar, denn ein Übergang zu erneuerbaren Energiequellen ist notwendig, der keine vollständige Reform des heutigen Energiesystems erfordert. Biomasse, insbesondere forstwirtschaftliche und pflanzliche Rückstände, ist eine wenig erforschte Energiequelle, deren Nutzung zur weiteren Aufwertung der ländlichen Wirtschaft beitragen kann, indem ein Nebenprodukt von geringem wirtschaftlichem Interesse verwendet wird. Unter den konkurrierenden Möglichkeiten ist Schnellpyrolyse ein thermochemischer Umwandlungspfad, der aus biogenem Material energiereiche Produkte und Produkte mit Mehrwert erzeugen kann. Die Pyrolyse kann Produkte in drei verschiedenen Zuständen erzeugen: gasförmig, flüssig und fest. Dies ist ein wichtiger Vorteil gegenüber traditionellen Verfahren, die nur eine oder zwei dieser Phasen oder überhaupt nur Wärme erzeugen. Alle erzeugten Produkte sind sofort für die Energieerzeugung nutzbar und weisen eine vergleichbare oder höhere Energiedichte als Rohbiomasse auf; sie können auch zu höherwertigen Produkten weiterverarbeitet werden, darunter Wasserstoff, Kraftstoffe, Zwischenprodukte und Feinchemikalien. Dies ist die Hauptmotivation für das bioliq®-Projekt. Dieses Promotionsprojekt konzentriert sich auf die Erstellung eines rigorosen und vielseitig verwendbaren Schnellpyrolysemodells, das auf einer realen Materialisation des bioliq®-Projekts im industriellen Pilotmaß- stab basiert. Das Modell basiert auf den Eigenschaften von lignozellulosehaltiger Biomasse, verwendet eine Reihe von Reaktoren zur Abbildung des realen Biomasseabbaus und bietet strenge Simulationen der Abschreckungsschleifen, die für eine zweistufige Flüssigproduktgewinnung verwendet werden. Bei der Initialisierung des Modells wurde Weizenstroh als Modellbiomasse verwendet, eine ungewöhnliche Wahl aufgrund seines hohen Aschegehalts, der katalytische Effekte begünstigt. In diesem Sinne wurde Thermogravimetrie für die Charakterisierung des Biomasseabbaus, die Schätzung des Lignozellulosegehalts und der Pyrolysekinetik für dieses Ausgangsmaterial verwendet. Um die Vielseitigkeit des Modells in Bezug auf die Eingabedaten zu gewährleisten, wurden mehrere in der Literatur verfügbare Reaktionsnetzwerke, die die lignozellulosehaltige Zusammensetzung der Biomasse in die Endprodukte umwandeln, analysiert und angepasst; die Zusammensetzung des erzeugten Kondensats wurde durch Sekundär- und Alterungsreaktionen auf die experimentellen Daten angepasst. Die Zusammensetzung der Kondensate wurde gestrafft, um die Modellierung zu erleichtern, und die definierten chemischen Spezies wurden im Hinblick auf ihre thermophysikalischen Eigenschaften vollständig charakterisiert. Für einige der ausgewählten Spezies mangelt experimentelle Charakterisierung, und es wurden bestehende Schätzmethoden implementiert, deren Ergebnisse in dieser Arbeit zur Verfügung gestellt wurden. Die abschließenden Tests berücksichtigten die Variation des Feuchtigkeitsgehalts im Weizenstroh und ergaben Ergebnisse, die mit den experimentellen Daten übereinstimmen. Nachfolgende Modelle, die verschiedene lignozellulosehaltige Biomassen berücksichtigten, bestätigten die Vielseitigkeit des entwickelten Modells bei der Vorhersage der Produktverteilung und der Zusammensetzung des Kondensats. Das endgültige Modell ist eigenständig voll funktionsfähig und kann im Hinblick auf Prozessspezifikationen und vor- und nachgeschaltete Implementierungen weiter angepasst werden

    Computer Simulations Applied to Small-Field Dosimetry in Radiotherapy

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    With the advancement of radiotherapy techniques, we find some challenges in small field dosimetry that are widely used in head and neck treatments, so computer simulations with the Monte Carlo method, already well established in medical physics, are a great tool for  studying small field dosimetry. The present work aims to report the validate of the geometry model used for the simulations of a 6 MV LINAC beam, in addition to estimating the TPS, PDD and PDD 20,10 curves for several regular and small fields, allowing comparisons with experimental data

    E-commerce no Brasil: revisão sistemática de literatura de 2011 a 2021 / E-commerce in Brazil: systematic literature review from 2011 to 2021

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    O surgimento da era digital e da internet no final do século XX desencadeou uma proliferação de novos modelos de negócios eletrônicos e continua a evoluir consistentemente nas últimas três décadas (Mendonça, 2016). O início do e-commerce no Brasil remonta ao meio da década de 1990, então o tema ainda é bastante recente no mercado e a produção acadêmica enxuta reflete essa jovialidade do tema. O presente estudo qualitativo se propôs a levantar, a partir de uma revisão sistemática de literatura em bases de artigos disponíveis no Portal de Periódicos da CAPES, quais são os temas abordados na produção acadêmica a respeito do e-commerce no Brasil entre o período de 2011 e maio de 2021. A partir de uma pesquisa inicial com 642 artigos e mais três rodadas de refinamento foram selecionados 23 artigos válidos que foram analisados em profundidade. Esses artigos foram agrupados em três grandes temas: comportamento do consumidor, negócios e outros. O presente artigo se mostra relevante em função da contemporaneidade do tema e como ponto de partida para futuras pesquisadores se aprofundarem nos tópicos identificados e nos aspectos ainda não abordados sobre comércio eletrônico no Brasil.

    Thermochemical and catalytic conversion technologies for the development of Brazilian biomass utilization

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    The social, economic, and environmental impacts of climate change have been shown to affect poorer populations throughout the world disproportionally, and the COVID-19 pandemic of 2020–2021 has only exacerbated the use of less sustainable energy, fuel, and chemical sources. The period of economic and social recovery following the pandemic presents an unprecedented opportunity to invest in biorefineries based on the pyrolysis of agricultural residues. These produce a plethora of sustainable resources while also contributing to the economic valorization of first-sector local economies. However, biomass-derived pyrolysis liquid is highly oxygenated, which hinders its long-term stability and usability. Catalytic hydrogenation is a proposed upgrading method to reduce this hindrance, while recent studies on the use of nickel and niobium as low-cost catalysts, both abundant in Brazil, reinforce the potential synergy between different economic sectors within the country. This review gathers state-of-the-art applications of these technologies with the intent to guide the scientific community and lawmakers alike on yet another alternative for energy and commodities production within an environmentally sustainable paradigm

    Sustained NMDA receptor hypofunction impairs brain-derived neurotropic factor signalling in the PFC, but not in the hippocampus, and disturbs PFC-dependent cognition in mice

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    BACKGROUND: Cognitive deficits profoundly impact on the quality of life of patients with schizophrenia. Alterations in brain derived neurotrophic factor (BDNF) signalling, which regulates synaptic function through the activation of full-length tropomyosin-related kinase B receptors (TrkB-FL), are implicated in the aetiology of schizophrenia, as is N-methyl-D-aspartate receptor (NMDA-R) hypofunction. However, whether NMDA-R hypofunction contributes to the disrupted BDNF signalling seen in patients remains unknown. AIMS: The purpose of this study was to characterise BDNF signalling and function in a preclinical rodent model relevant to schizophrenia induced by prolonged NMDA-R hypofunction. METHODS: Using the subchronic phencyclidine (PCP) model, we performed electrophysiology approaches, molecular characterisation and behavioural analysis. RESULTS: The data showed that prolonged NMDA-R antagonism, induced by subchronic PCP treatment, impairs long-term potentiation (LTP) and the facilitatory effect of BDNF upon LTP in the medial prefrontal cortex (PFC) of adult mice. Additionally, TrkB-FL receptor expression is decreased in the PFC of these animals. By contrast, these changes were not present in the hippocampus of PCP-treated mice. Moreover, BDNF levels were not altered in the hippocampus or PFC of PCP-treated mice. Interestingly, these observations are paralleled by impaired performance in PFC-dependent cognitive tests in mice treated with PCP. CONCLUSIONS: Overall, these data suggest that NMDA-R hypofunction induces dysfunctional BDNF signalling in the PFC, but not in the hippocampus, which may contribute to the PFC-dependent cognitive deficits seen in the subchronic PCP model. Additionally, these data suggest that targeting BDNF signalling may be a mechanism to improve PFC-dependent cognitive dysfunction in schizophrenia

    Geographical distribution of American cutaneous leishmaniasis and its phlebotomine vectors (Diptera: Psychodidae) in the state of São Paulo, Brazil

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    <p>Abstract</p> <p>Background</p> <p>American cutaneous leishmaniasis (ACL) is a re-emerging disease in the state of São Paulo, Brazil. It is important to understand both the vector and disease distribution to help design control strategies. As an initial step in applying geographic information systems (GIS) and remote sensing (RS) tools to map disease-risk, the objectives of the present work were to: (i) produce a single database of species distributions of the sand fly vectors in the state of São Paulo, (ii) create combined distributional maps of both the incidence of ACL and its sand fly vectors, and (iii) thereby provide individual municipalities with a source of reference material for work carried out in their area.</p> <p>Results</p> <p>A database containing 910 individual records of sand fly occurrence in the state of São Paulo, from 37 different sources, was compiled. These records date from between 1943 to 2009, and describe the presence of at least one of the six incriminated or suspected sand fly vector species in 183/645 (28.4%) municipalities. For the remaining 462 (71.6%) municipalities, we were unable to locate records of any of the six incriminated or suspected sand fly vector species (<it>Nyssomyia intermedia</it>, <it>N. neivai</it>, <it>N. whitmani</it>, <it>Pintomyia fischeri</it>, <it>P. pessoai </it>and <it>Migonemyia migonei</it>). The distribution of each of the six incriminated or suspected vector species of ACL in the state of São Paulo were individually mapped and overlaid on the incidence of ACL for the period 1993 to 1995 and 1998 to 2007. Overall, the maps reveal that the six sand fly vector species analyzed have unique and heterogeneous, although often overlapping, distributions. Several sand fly species - <it>Nyssomyia intermedia </it>and <it>N. neivai </it>- are highly localized, while the other sand fly species - <it>N. whitmani, M. migonei, P. fischeri </it>and <it>P. pessoai </it>- are much more broadly distributed. ACL has been reported in 160/183 (87.4%) of the municipalities with records for at least one of the six incriminated or suspected sand fly vector species, while there are no records of any of these sand fly species in 318/478 (66.5%) municipalities with ACL.</p> <p>Conclusions</p> <p>The maps produced in this work provide basic data on the distribution of the six incriminated or suspected sand fly vectors of ACL in the state of São Paulo, and highlight the complex and geographically heterogeneous pattern of ACL transmission in the region. Further studies are required to clarify the role of each of the six suspected sand fly vector species in different regions of the state of São Paulo, especially in the majority of municipalities where ACL is present but sand fly vectors have not yet been identified.</p

    The Role of Isotretinoin Therapy for Cushing’s Disease: Results of a Prospective Study

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    Objective. This prospective open trial aimed to evaluate the efficacy and safety of isotretinoin (13-cis-retinoic acid) in patients with Cushing’s disease (CD). Methods. Sixteen patients with CD and persistent or recurrent hypercortisolism after transsphenoidal surgery were given isotretinoin orally for 6–12 months. The drug was started on 20 mg daily and the dosage was increased up to 80 mg daily if needed and tolerated. Clinical, biochemical, and hormonal parameters were evaluated at baseline and monthly for 6–12 months. Results. Of the 16 subjects, 4% (25%) persisted with normal urinary free cortisol (UFC) levels at the end of the study. UFC reductions of up to 52.1% were found in the rest. Only patients with UFC levels below 2.5-fold of the upper limit of normal achieved sustained UFC normalization. Improvements of clinical and biochemical parameters were also noted mostly in responsive patients. Typical isotretinoin side-effects were experienced by 7 patients (43.7%), though they were mild and mostly transient. We also observed that the combination of isotretinoin with cabergoline, in relatively low doses, may occasionally be more effective than either drug alone. Conclusions. Isotretinoin may be an effective and safe therapy for some CD patients, particularly those with mild hypercortisolism

    Gestão de pessoas em ONGs

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    -Este livro apresenta as principais ferramentas da gestão de pessoas, destacando como podem ser aplicadas á realidade das organizações não-governamentais. Fruto de uma pesquisa realizada em diversas ONGs, apresenta soluções práticas ara os desafios relacionados ao gerenciamento das equipes desse tipo de organização. Dada a complexidade que caracteriza o trabalho das ONGs, faz-se necessário o desenvolvimento de ações mais efetivas visando a seleção, o desenvolvimento, a motivação e o entrosamento dos empregados e voluntários, o que pode ser beneficiado pelo conhecimento das técnicas de gestão expostas na obra. Tem como público-alvo gestores de ONGs, estudiosos do terceiro setor e estudantes de administração e demais ciências relacionadas à gestão social e ao gerenciamento de pessoas
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