1,720,959 research outputs found
Multiscale Modelling of Polymer Self-Assembly in Binary Solvent Mixtures
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
Molecules As Building Blocks in a Novel Population Balance Model for Flash Nano-Precipitation: Investigation of the Different Good Solvents Effect on Nanoparticle Formation
No full textSoft matter self-assembly in acetone-water mixtures: a multiscale modeling approach
No full textThis work focuses on macromolecule (poly-ε-caprolactone, PCL) self-assembly in acetone/water mixtures by a novel multiscale approach which combines molecular dynamics (MD), a Smoluchowski population balance model (PBM) and computational fluid dynamics (CFD), to model the self-assembly process from the atomistic to the macro-scal
Multiscale Modelling of Macromolecule Self-Assembly in Solution: The Case of Poly-ε-Caprolactone in Acetone-Water Mixtures
No full textMolecules as building blocks for a CFD-PBE model to describe the effect of fluid dynamics on nanoparticle formation
Full text linkRecently research efforts have focused on the effect of fluid dynamics on particle formation processes, by using special mixing devices, that allow to perform controlled experiments, and complex models, that allow to quantify its influence on the final particle size. The standard modelling approach consists in considering three different steps: nucleation, molecular growth and aggregation. This is usually done by simulating the process with a population balance equation (PBE) coupled with computational fluid dynamics (CFD), in which these three different steps are considered separately. The PBE is often written using as internal coordinate the actual particle size or volume; here, we propose a new modelling strategy that overcomes the concepts of nucleation and molecular growth, by using as internal coordinate the number of molecules which aggregate, or self-assemble, together forming a nanoparticle. The novel modelling approach is therefore defined as a purely-aggregative model
A novel multiscale model for the simulation of polymer flash nano-precipitation
Full text linkNumerous models describe the flash nano-precipitation (FNP) process to form polymer nanoparticles, however most of them are based on equilibrium approaches and are not capable of predicting kinetically stable configurations. Moreover, since FNP occurs through solvent-displacement, the way in which the solvent and anti-solvent are mixed plays an important role, which is often overlooked. Here we propose a multiscale approach, which combines molecular dynamics (MD), a Smoluchowski population balance equation (PBE) and computational uid dynamics (CFD), to model the FNP process, from the atomistic-scale up to the macro-scale. The particle formation process is not described with the usual nucleation-and-growth approach, but as Brownian aggregation of the polymer molecules into nanoparticles. Being the final nanoparticles amorphous, no energy barrier to the aggregation process is considered, whereas the effects of both turbulent mixing and turbulent aggregation on the evolution of the nanoparticles are accounted for. The mainnovelty of this work is that the aggregation kernel appearing in the PBE, coupled in turn with CFD, is calculated from MD simulations, following the multiscale modeling paradigm. The model is tested on the FNP of poly-ε-caprolactone nanoparticles in acetone-water mixtures. Predictions for the final mean nanoparticle size are found in good agreement with experiments, especially at high initial polymer concentrations, where the hypothesis of no energy barrier is more realistic.<br/
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
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