1,720,986 research outputs found
Variational modeling of micro-cracking and failure in fiber-reinforced concretes
No full textA variational micro-mechanical model is proposed to reproduce the complex response of fiber-reinforced concretes to tensile loadings. The composite is described as a mixture where two phases are combined: a brittle phase, corresponding to the cementitious matrix, and an elasto-plastic phase, describing the ductile contribution of fibers. The model is formulated in the simple one-dimensional setting of a tensile bar, and implemented in a finite element code. Simulations of tensile tests are performed, which capture the different stages of the evolution typically observed in experiments: the stress-hardening phase of microcracking, and the subsequent stage of stress-softening in which a macro-crack opens, leading to the sample failure. Simulations also reproduce the stiffness degradation and the occurrence of residual strains observed when samples are unloaded
Sentimenti, emozioni e politica
No full textSolo in tempi relativamente recenti la ricerca storica ha incrinato il monopolio psico-pedagogico determinato dalla considerazione delle emozioni come requisito naturale, per trasformarlo invece in dato culturale, soggetto a modificazioni nel tempo e nella realtà storica di riferimento. Di qui lo sviluppo della cosiddetta History of Emotions come percorso autonomo gestito dagli storici, con l’ampliamento dell’analisi sulla storia dei comportamenti collettivi fino a comprendere i sentimenti e le relazioni amorose, le pratiche sessuali, gli affetti pubblici e privati come tessere di un mosaico composito ma indispensabile per decifrare rotture e persistenze nel costume nazionale, nella specificità dei vari contesti geografici
Il male, il fiore, il desiderio: sul Leopardi dell’ultimo Luzi
No full textL'intervento mira a descrivere e interpretare la presenza della poesia e del pensiero leopardiano nella fase finale della poesia di Mario Luz
Determination of selected phenothiazines in human plasma by solid-phase extraction and liquid chromatography with coulometric detection.
No full textA new analytical method, based on liquid chromatography with coulometric detection, has been developed and applied to the determination of selected phenothiazines (chlorpromazine, promazine, fluphenazine and levomepromazine) in human plasma. The drugs were separated on a Discovery pentafluorophenylpropyl column, using a mobile phase composed of acetonitrile (32%) and a pH 1.9 phosphate buffer (68%). Promethazine was used as the internal standard. Detection was carried out at an oxidation potential of +0.500 V. A novel clean-up procedure was developed by means of solid-phase extraction, using cyanopropyl cartridges, which gave good extraction yield for all the analytes, with absolute recovery values higher than 91.0%. The detector response was linear over a plasma concentration range of 0.5-250.0 ng mL(-1) for chlorpromazine, promazine and levomepromazine and of 0.2-4.0 ng mL(-1) for fluphenazine. Precision results, expressed by the intra-day and the inter-day relative standard deviation values, were good, being lower than 3.9%. Accuracy data were satisfactory as well. The method has been successfully applied to the analysis of drug plasma levels of psychiatric patients undergoing therapy with selected phenothiazine
Modeling solute transport and mixing in heterogeneous porous media under turbulent flow conditions
Full text linkWe develop and test a modeling approach to quantify turbulence-driven solute transport and mixing in porous media. Our approach addresses two key elements: (a) the spatial variability of the effective diffusion coefficient which is typically documented in the presence of a sediment-fluid interface and (b) the need to provide a model that can yield the complete distribution of the concentration probability density function, not being limited only to the mean concentration value and thus fully addressing solute mixing. Our work is motivated by the importance of solute transport processes in the hyporheic zone, which can have strong implications in natural attenuation of pollutants. Our approach combines Lagrangian schemes to address transport and mixing in the presence of spatial variability of effective diffusion. An exemplary scenario we consider targets a setup constituted by a homogeneous (fully saturated) porous medium underlying a clear water column where turbulent flow is generated. Solute concentration histories obtained through a model based solely on diffusive transport are benchmarked against an analytical solution. These are then compared against the results obtained by modeling the combined effects of diffusion and mixing. A rigorous sensitivity analysis is performed to evaluate the influence of model parameters on solute concentrations and mixing, the latter being quantified in terms of the scalar dissipation rate
Análise técnico-econômica e ambiental da produção de ácidos orgânicos a partir de biomassa lignocelulósica utilizando microrganismos recombinantes
Full text linkOrganic acids are of great importance to the general industry, with a focus on the polymer industry. Among the most promising organic acids are succinic and cis,cis-muconic acids, which are considered building blocks because due to their simplified structure they can be used in a large number of applications. The search for the replacement of conventional chemical processes for the production of these acids with sustainable routes based on the use of renewable inputs has been growing in recent years, especially in the use of biotechnological routes. However, the processes still face economic and environmental issues due to the complexity of their purification steps, the need for planting for production and the low yield of the reaction. This work aimed to perform a technical-economic and environmental analysis of the production of muconic acid and succinic acid, considering different production scenarios and drawing a comparison between different biotechnological routes and the conventional chemical route. This allowed for the identification of the applicability of the processes within the Brazilian scenario and the identification of points that require greater attention of choice and need for improvement. The analysis showed that muconic acid still requires more efficient microorganisms and purification steps to be competitive in the market. The compound presents a yield below 10%, which contributes to a minimum selling price of US 3.06, a little above the US 45,81. O rendimento baixo também prejudica o desempenho ambiental do processo proposto. Já a produção de ácido succínico por rota biotecnológica se mostrou economicamente interessante, apresentando um preço mínimo de venda de US 2,94 encontrado no mercado internacional. Do ponto de vista ambiental, a rota possibilita a redução de emissões em categorias de impactos ambientais importantes, como potencial de mudanças climáticas, eutrofização, acidificação e escassez de recursos renováveis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
