2,026 research outputs found
Purification of complex biopharmaceuticals with new processes, advanced analytics and computer-aided process design tools
Dissertação para obtenção do Grau de Mestre em
BiotecnologiaViruses are highly efficient vectors that have been used for vaccination and gene therapy applications. However, their complexity renders downstream process particularly challenging since devices and strategies especially designed for virus purification are still lacking or need
further optimization. After an introduction to the challenges of virus purification and the current strategies being employed, this dissertation presents the study of three different stages of the downstream process: clarification, ultrafiltration and chromatography.
A novel clarification procedure based on diatomaceous earth was evaluated. Small-scale
batch incubations led to the identification of Divergan RS – a synthetic non-charged material – as the most promising candidate for integration in a scalable filtration set-up.
Ultrafiltration was addressed with the evaluation of cassette and hollow fiber modules.
The results obtained show that cassette module with cut-offs in the 500 kDa range and highly hydrophilic materials enable complete recovery of infective Adenovirus while reducing process time in half when compared with the best hollow fibers. Despite the encouraging results with
Adenovirus, the experiments using Retrovirus resulted in low yields and possible optimization strategies were identified.
Membrane technology was also evaluated as an alternative to the packed-bed chromatography
columns. By using a scale-down 96-well device, the impact of ligand density, membrane structure and feed conductivity were evaluated for the purification of Adenovirus by ion exchange chromatography. The hydrogel-grafted membrane with ligand density of 2.4 μmol cm-2 operated in bind/elute mode shown the best compromise between yield and purity.
Overall, this thesis contributed to the advancement of virus purification field by exploiting innovative technologies.Fundação para a Ciência e a Tecnologia - (PTDC/EBBBIO/119501/2010
Hybrid particle swarm optimization with spiral-shaped mechanism for solving high-dimension problems
Particle swarm optimization (PSO) is a well-known metaheuristic, whose performance for solving global optimization problems has been thoroughly explored. It has been established that without proper manipulation of the inertia weight parameter, the search for a global optima may fail. In order to handle this problem, we investigate the experimental performance of a PSO-based metaheuristic known as HPSO-SSM, which uses a logistic map sequence to control the inertia weight to enhance the diversity in the search process, and a spiral-shaped mechanism as a local search operator, as well as two dynamic correction factors to the position formula. Thus, we present an application of this variant for solving high-dimensional optimization problems, and evaluate its effectiveness against 24 benchmark functions. A comparison between both methods showed that the proposed variant can escape from local optima, and demonstrates faster convergence for almost every evaluated function
Study of welding strengh in PVC profiles
Polyvinyl chloride, PVC, is one of the most widely produced and used plastic, being commonly used in civil industry due to its wide range of mechanical properties (from rigid to flexible), low cost, durability, and easy to assemble. Due to its good mechanical and thermal properties, PVC can be used to produce window and door frames, protecting the interior from the external actions, such as noise and temperature gradients. In order to achieve the final dimensions and geometry, previously extruded profiles must be cut and assembled, being the butt welding one of the most efficient techniques. This plastic welding method involves three main steps: i) pressing the parts to be joined against either side of a heated plate; ii) removing the plate when the parts are sufficiently molten and iii) pressing the components together and holding them until they are cooled. The amount of molten material, generated during the heating stage at an adequate heating time and the plate temperature, as well as the amount of material forced out from the joint during the pressing stage (joining displacement), have major influence in the final welding properties. Although the lack of information about the butt welding of PVC, previous studies with for others materials [1-3] showed that the welding strength can be optimized changing the plate temperature and/or joining displacement.
The aim of this work was to study the influence of the plate temperature and the heating time in the welding strength of PVC profiles used in windows frames. The profiles were welded in an industrial butt welder machine, setting the plate temperature at 245ºC, 260ºC and 275ºC and the heating time at 15 and 20s. The mechanical properties were evaluated by mechanical bending tests, according to UNE-EN 514 standard and the welding strength was correlated with the morphology of the welded parts observed by optical microscopy. The results are showing that the increase of plate temperature and heating time increase the welding strength. However, the presence of impurities in the joint, such as trapped air or degraded material, as well as the joint alignment, can have a detrimental effect on the welding strength, as observed by the morphological analyses
O FOMENTO À PARTICIPAÇÃO, MOBILIZAÇÃO E ORGANIZAÇÃO DOS/AS USUÁRIOS/AS E A DIMENSÃO PEDAGÓGICA DOS CENTROS POP.
RESUMO: Este trabalho tem como objetivo problematizar sobre a dimensão pedagógica ou socioeducativa da intervenção nos Centros de Referência Especializados Para População em Situação de Rua, argumentando que se trata de uma dimensão central neste serviço. O trabalho ocorre com ênfase em uma das possibilidades desta dimensão, qual seja o estímulo à mobilização, organização e participação de usuários/as do serviço. Buscam-se dados sobre como o tema em tela vêm sendo efetivado nos Centros POP brasileiros e realizam-se ponderações iniciais acerca de tais dados, detectando as referidas ações ainda carecem de fortalecimento, assim como a participação dos usuários no cotidiano dos serviços
Extreme Learning Machine combined with a Differential Evolution algorithm for lithology identification
Lithology identification, obtained through the analysis of several geophysical properties, has an important role in the process of characterization of oil reservoirs. The identification can be accomplished by direct and indirect methods, but these methods are not always feasible because of the cost or imprecision of the results generated. Consequently, there is a need to automate the procedure of reservoir characterization and, in this context, computational intelligence techniques appear as an alternative to lithology identification. However, to acquire proper performance, usually some parameters should be adjusted and this can become a hard task depending on the complexity of the underlying problem. This paper aims to apply an Extreme Learning Machine (ELM) adjusted with a Differential Evolution (DE) to classify data from the South Provence Basin, using a previously published paper as a baseline reference. The paper contributions include the use of an evolutionary algorithm as a tool for search on the hyperparameters of the ELM. In addition, an activation function recently proposed in the literature is implemented and tested. The computational approach developed here has the potential to assist in petrographic data classification and helps to improve the process of reservoir characterization and the production development planning
An off-board multi-functional electric vehicle charging station for smart homes: analysis and experimental validation
This paper presents the analysis and experimental validation of a single-phase off-board multi-functional electric vehicle (EV) charging station (MF-EVCS), which has a single ac interface and two dc interfaces. As innovative aspects, the proposed MF-EVCS handles the interface of the ac power grid, the dc interface of a renewable energy source (RES), as well as the dc interface of an EV to perform dc charging or discharging of the batteries (in off-board grid-to-vehicle (G2V) or vehicle-to-grid (V2G) modes). Considering the power grid, the individual operation modes of the RES and the EV interfaces can be considered. Moreover, a combination of these modes is also possible. Besides, the MF-EVCS has as key innovative aspect the possibility of operating as an active power filter (APF), supporting the operation with reactive power and/or selected current harmonics. This possibility can be associated with any of the previous mentioned modes. These new features are framed in two distinct scenarios: in a smart home, where the ac-side current can be determined as a function of the other electrical appliances; in a smart grid, where the ac-side current can be determined as a requisite of the power grid. The proposed power theory, as well as the current control strategies for both ac-side and dc-side of the MF-EVCS, are presented in the paper for all the possible operation scenarios. A laboratory prototype was developed to validate the proposed MF-EVCS and the experimental results confirm its suitability for smart homes.INCT-EN -Instituto Nacional de Ciência e Tecnologia para Excitotoxicidade e Neuroproteção(DAIPESEV PTDC/EEI-EEE/30382/2017
Street culture and peripheral youth policies: historical aspects and a look to hip-hop in Africa and Brazil
UID/SOC/04647/2013A cultura hip-hop se orienta em torno de estabelecer um projeto coletivo para a sociedade como um todo. Nesse caso, o objetivo do ensaio é analisar as ações culturais do hip-hop em África e Brasil como possíveis mediações para novas práticas de sociabilidade e formas de representação diante aos diversos conflitos presentes no cotidiano. A partir de uma pesquisa bibliográfica centrada na linha teórica dos Estudos Culturais, para pensar o processo de representação social e identitário, e também das conversas informais com os coletivos de hip-hop realizadas no ano de 2012, evidenciamos o hip-hop no papel da democratização da informação, como de novo canal de informação e a inclusão de novos emissores.publishersversionpublishe
The importance of prenatal dental care: a concise systematic review
Introduction: Prenatal dental care is extremely important, as it requires a series of specific care for pregnant patients. There is a need for specific care with the health of the mouth and informing the patient of essential care for her and her baby's health. Also, the microorganisms that cause these diseases can migrate to the uterus and cause premature births. Several studies show that dental care was considered safe for the mother and fetus throughout the entire period of pregnancy. Objective: To carry out a brief systematic review of the literature to elucidate the main considerations for success during the treatment of oral health in pregnant women. Methods: The research was carried out from May 2021 to June 2021 and developed based on Scopus, PubMed, Science Direct, Scielo, and Google Scholar, following the Systematic Review-PRISMA rules. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results: A total of 244 articles were found. A total of 76 articles were evaluated in full and 19 were included and evaluated in the present study. A total of 3 Studies with a High Risk of Bias and 1 Study with Uncertain Risk. Studies have suggested a protective effect of prenatal oral health care against the onset of caries in infancy and up to before 4 years of age. The transport of S. mutans in children was also significantly reduced in the intervention group. Children exposed to the use of maternal substances had a higher incidence of hospitalization for dental caries than unexposed children. Thus, inadequate prenatal education in oral health can negatively impact the quality of oral hygiene in children. It is imperative to develop strategies to improve oral health and develop a health system strengthening by interprofessional collaboration in the prenatal phase of pregnant women. Furthermore, an inverse relationship was observed between 25(OH)D levels and the number of decayed primary teeth. Conclusion: Taking care of oral health is part of the daily rhythm of personal hygiene. The monitoring of a dental surgeon during pregnancy is considered to prevent and treat the pregnant woman's oral diseases and clarify the doubts of future mothers since the baby's oral health begins to establish itself during the gestational period
Custo de capital próprio e transparência dos lucros no mercado brasileiro de capitais
This research paper investigates the relationship between the Cost of Equity and the Earnings Transparency in the Brazilian capital market. For this purpose, supported by a literature review, especially based on Barth et al. (2013), data were analyzed from 246 companies between 2005 and 2014. The data analysis was performed using descriptive statistics, correlations and regressions. Initially regressions were estimated with fixed effects panel data and by the observation of high standard deviations of the variables and the possibility presence of heteroscedasticity, estimates were made by quantile regressions and GLS to control these phenomena. In the results, it can be seen that Earnings variables of the companies had high standard deviations in the analyzed period, influencing the analysis for fixed effects. From the models by quantile regressions in median and GLS it was possible to see that, despite the segregation of companies for portfolios based on their size, it did not present influence in the analysis, and the ratio of Expected Cost of Equity with Earnings Transparency was negative and significant. It is concluded that in the period analyzed the higher the Earnings Transparency, the lower the Cost of Equity of companies. Therefore, the identification of the most suitable models to heteroskedastic earnings analysis in the Brazilian market, as well as their evidence of reduced Cost of Equity by increasing the Earnings Transparency, stand out as major contributions of this study.Keywords: Cost of Equity, Earnings Transparency, quantile regression.Este trabalho investigou a relação entre o Custo de Capital Próprio e a Transparência dos Lucros no mercado brasileiro de capitais. Para isso, apoiado em uma revisão de literatura, especialmente com base no estudo de Barth et al. (2013), foram analisados os dados de 246 empresas entre os anos de 2005 e 2014. As análises foram realizadas a partir de estatísticas descritivas, correlações e regressões. Inicialmente, foram estimadas regressões em dados em painel com Efeitos Fixos e, ao se observar altos desvios-padrão das variáveis e possibilidade de heterocedasticidade, foram realizadas estimativas de regressões quantílicas e por GLS para controlar esses fenômenos. Em seus resultados, pode-se verificar que as variáveis de lucro das companhias apresentaram altos desvios-padrão no período analisado, influenciando as análises por Efeitos Fixos. A partir dos modelos por regressões quantílicas na mediana e por GLS, foi possível verificar que, apesar de a segregação das empresas por portfólios baseados em seu tamanho não ter apresentado influência nas análises, a relação do Custo de Capital Esperado com a Transparência dos Lucros foi negativa e significante. Com isso, conclui-se que, no período analisado, quanto maior foi a Transparência dos Lucros, menor foi o Custo de Capital Próprio das empresas. Assim, destacam- -se como principais contribuições deste estudo a identificação dos modelos mais adequados à análise de lucros heterocedásticos no mercado brasileiro, assim como suas evidências de redução do Custo de Capital Próprio com o aumento da Transparência dos Lucros.Palavras-chave: Custo de Capital Próprio, Transparência dos Lucros, regressão quantílica
Custo de capital próprio e transparência dos lucros no mercado brasileiro de capitais
This research paper investigates the relationship between the Cost of Equity and the Earnings Transparency in the Brazilian capital market. For this purpose, supported by a literature review, especially based on Barth et al. (2013), data were analyzed from 246 companies between 2005 and 2014. The data analysis was performed using descriptive statistics, correlations and regressions. Initially regressions were estimated with fixed effects panel data and by the observation of high standard deviations of the variables and the possibility presence of heteroscedasticity, estimates were made by quantile regressions and GLS to control these phenomena. In the results, it can be seen that Earnings variables of the companies had high standard deviations in the analyzed period, influencing the analysis for fixed effects. From the models by quantile regressions in median and GLS it was possible to see that, despite the segregation of companies for portfolios based on their size, it did not present influence in the analysis, and the ratio of Expected Cost of Equity with Earnings Transparency was negative and significant. It is concluded that in the period analyzed the higher the Earnings Transparency, the lower the Cost of Equity of companies. Therefore, the identification of the most suitable models to heteroskedastic earnings analysis in the Brazilian market, as well as their evidence of reduced Cost of Equity by increasing the Earnings Transparency, stand out as major contributions of this study.Keywords: Cost of Equity, Earnings Transparency, quantile regression.Este trabalho investigou a relação entre o Custo de Capital Próprio e a Transparência dos Lucros no mercado brasileiro de capitais. Para isso, apoiado em uma revisão de literatura, especialmente com base no estudo de Barth et al. (2013), foram analisados os dados de 246 empresas entre os anos de 2005 e 2014. As análises foram realizadas a partir de estatísticas descritivas, correlações e regressões. Inicialmente, foram estimadas regressões em dados em painel com Efeitos Fixos e, ao se observar altos desvios-padrão das variáveis e possibilidade de heterocedasticidade, foram realizadas estimativas de regressões quantílicas e por GLS para controlar esses fenômenos. Em seus resultados, pode-se verificar que as variáveis de lucro das companhias apresentaram altos desvios-padrão no período analisado, influenciando as análises por Efeitos Fixos. A partir dos modelos por regressões quantílicas na mediana e por GLS, foi possível verificar que, apesar de a segregação das empresas por portfólios baseados em seu tamanho não ter apresentado influência nas análises, a relação do Custo de Capital Esperado com a Transparência dos Lucros foi negativa e significante. Com isso, conclui-se que, no período analisado, quanto maior foi a Transparência dos Lucros, menor foi o Custo de Capital Próprio das empresas. Assim, destacam- -se como principais contribuições deste estudo a identificação dos modelos mais adequados à análise de lucros heterocedásticos no mercado brasileiro, assim como suas evidências de redução do Custo de Capital Próprio com o aumento da Transparência dos Lucros.Palavras-chave: Custo de Capital Próprio, Transparência dos Lucros, regressão quantílica
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