Experimental and numerical investigation of a density-driven instability during a horizontal miscible displacement

We performed an experimental and numerical investigation of a convective buoyancy-driven instability that arises during the injection of a denser miscible fluid into a less dense one in a rectilinear geometry. We visualized the instability using a shadowgraph technique, and we obtained quantitative information using micro-Particle Image Velocimetry. Numerical simulations provided further insights into the three-dimensional (3D) velocity field. We have shown that the instability only occurs above a certain Peclet number, Pe, depending on the Rayleigh, Ra, and Schmidt, Sc, numbers. We suggest scalings of the critical time, T-C, and dimensionless wavelength, ?/h, of the instability, both of which increase with increasing Pe and Ra. Finally, we investigated the interactions of the instability vortices with each other and the geometry boundaries

Chemical flowers: Buoyancy-driven instabilities under modulated gravity during a parabolic flight

This paper is associated with a video winner of the 2021 American Physical Society's Division of Fluid Dynamics (DFD) Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original video is available online at the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2021.GFM.V0036

Neutrophils in cancer: neutral no more

Neutrophils are indispensable antagonists of microbial infection and facilitators of wound healing. In the cancer setting, a newfound appreciation for neutrophils has come into view. The traditionally held belief that neutrophils are inert bystanders is being challenged by the recent literature. Emerging evidence indicates that tumours manipulate neutrophils, sometimes early in their differentiation process, to create diverse phenotypic and functional polarization states able to alter tumour behaviour. In this Review, we discuss the involvement of neutrophils in cancer initiation and progression, and their potential as clinical biomarkers and therapeutic targets

Experimentelle Untersuchungen zur Strukturbildung unter stationärer solutaler Marangoni-Instabilität

Beim Stoffübergang einer grenzflächenaktiven Substanz in einem flüssigen Zweiphasensystem kann solutale Marangoni-Instabilität einsetzen. Die weitere nichtlineare Entwicklung der Marangoni-Instabilität geht mit einer enormen Vielfalt von Strömungsmustern einher. In der Literatur wird dieser Aspekt häufig unter dem unscharfen Ausdruck „Grenzflächenturbulenz“ zusammengefasst. Diese Arbeit stellt heraus, dass drei grundlegende Strukturformen existieren: Rollzellen, Relaxationsoszillationen und Relaxationsoszillationswellen. Ein großer Teil der Komplexität der Strömungsmuster ist dadurch begründet, dass die Grundstrukturen unterschiedliche Hierarchieebenen aufweisen. Es werden die zugrunde liegenden Bedingungen für das Auftreten der jeweiligen Strukturtypen, ihre transiente Natur und die Bildung der hierarchischen Strömungsmuster untersucht. Des Weiteren betrachtet diese Arbeit die Wechselwirkungen mit Dichteeffekten, die sowohl die Charakteristik der Strukturen als auch ihre zeitliche Entwicklung beeinflussen

Experimentelle Untersuchungen zur Strukturbildung unter stationärer solutaler Marangoni-Instabilität

Beim Stoffübergang einer grenzflächenaktiven Substanz in einem flüssigen Zweiphasensystem kann solutale Marangoni-Instabilität einsetzen. Die weitere nichtlineare Entwicklung der Marangoni-Instabilität geht mit einer enormen Vielfalt von Strömungsmustern einher. In der Literatur wird dieser Aspekt häufig unter dem unscharfen Ausdruck „Grenzflächenturbulenz“ zusammengefasst. Diese Arbeit stellt heraus, dass drei grundlegende Strukturformen existieren: Rollzellen, Relaxationsoszillationen und Relaxationsoszillationswellen. Ein großer Teil der Komplexität der Strömungsmuster ist dadurch begründet, dass die Grundstrukturen unterschiedliche Hierarchieebenen aufweisen. Es werden die zugrunde liegenden Bedingungen für das Auftreten der jeweiligen Strukturtypen, ihre transiente Natur und die Bildung der hierarchischen Strömungsmuster untersucht. Des Weiteren betrachtet diese Arbeit die Wechselwirkungen mit Dichteeffekten, die sowohl die Charakteristik der Strukturen als auch ihre zeitliche Entwicklung beeinflussen

Data for: The influence of negatively charged silica nanoparticles on the surface properties of anionic surfactants: electrostatic repulsion or the effect of ionic strength?

The presence of negatively charged nanoparticles affects the surface activity of anionic surfactants in an aqueous phase. Recent studies suggest that electrostatic repulsive forces play an important role in increasing the surface activity of surfactants. However, the addition of nanoparticles also increases the ionic strength of the system, which has a significant impact on the surfactant's properties, e.g. its critical micelle concentration (CMC). To investigate how and to what extent electrostatic forces and ionic strength influence the behavior of ionic surfactants, the surface tension and elasticity of different solutions were measured using drop profile tensiometry as a function of the surfactant (SDBS), nanoparticle (silica) and salt (KNO3) concentration. It is observed that the surface activity of the surfactants is mainly influenced by the change in the system's ionic strength due to the presence of nanoparticles. Several characteristic parameters including the equivalent concentration of the surfactant, the CMC and the apparent partial molar area of the adsorbed surfactant are theoretically calculated and further employed to validate experimental observations. Both the nanoparticles and electrolyte decrease the CMC, while the equivalent concentration of the surfactant remains nearly constant. This paper presents a criterion to estimate the possible influence of such forces for nanoparticles of different sizes and mass fractions

Pattern formation and mass transfer under stationary solutal Marangoni instability

Orientador Prof. Dr. André Luiz BattaiolaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Humanas, Programa de Pós-Graduação em Design. Defesa : Curitiba, 29/10/2020Inclui referências: p. 107-110Resumo: Apesar das diversas características culturais peculiares do mangá, história em quadrinhos japonesa, como a leitura invertida, as referências aos costumes e a história do Japão e uma linguagem própria que, entre outras coisas, padroniza formas de expressar as emoções dos personagens, o mangá atrai atenção e leitores em diferentes países. Este fato leva ao questionamento do porquê o mangá é tão atrativo a leitores com perfis tão diferentes? Seria a narrativa, a arte gráfica, os personagens, ou a combinação de todos estes elementos? Dada a dificuldade de se responder a uma questão tão ampla, esta pesquisa se ateve a analisar a arte gráfica do mangá. A imagem é um dos elementos centrais dos quadrinhos, assim, pode-se questionar, por exemplo, quais recursos a arte gráfica do mangá utiliza para atrair seus leitores? Além dos vários recursos já apontados pelos estudiosos dos quadrinhos para o elemento imagem (enquadramento, linhas de movimento, linhas de ação etc), um conceito praticamente inexplorado em pesquisas acadêmicas são as figuras de linguagens no contexto da retórica visual, as quais podem ser utilizadas para enfatizar determinados momentos da narrativa, ampliando e reforçando os significados das imagens nas quais são aplicadas. Além disso, esta pesquisa preenche uma lacuna acadêmica, pois uma consulta à literatura mostrou que o mangá tem sido objeto de estudo em diversas áreas, no entanto, ainda é pouco analisado no âmbito do design. Assim, esta dissertação tem o objetivo de identificar como a retórica visual é utilizada no mangá. Esta pesquisa se classifica como de natureza exploratória, pois visa criar maior familiaridade com o tema, neste caso o mangá. Tem objetivo descritivo pois visa descrever como a retórica visual é utilizada no mangá. Sua abordagem é qualitativa, pois busca entender a relação entre a retórica visual e o mangá de forma holística provendo resultados que podem gerar diversas interpretações de análise. Os métodos de pesquisa aplicados foram a revisão bibliográfica sistemática e a análise de imagem. Os resultados obtidos foram um protocolo de análise para histórias em quadrinhos que permitiu a elaboração de um diagnóstico preliminar do uso da retórica visual nos mangás analisados. As análises de três mangás diferentes apontam para um uso consciente e efetivo por parte dos mangakás (autores de mangá) das figuras de linguagem, bem como para a capacidade do protocolo elaborado de prover conclusões sobre o uso destas linguagens. Por outro lado, cabe ressaltar a natureza exploratória desta pesquisa, ou seja, o protocolo elaborado deve ser aplicado em mais amostras para que se possa tanto aperfeiçoar os seus elementos de análise, quanto se possa identificar o alcance do uso das figuras de linguagem pelos mangakás. Palavras-chave: mangá, retórica visual, figuras de linguagem, imagem.Abstract: Despite the diverse cultural characteristics peculiar to the manga, Japanese comic books, such as inverted reading, references to Japanese customs and history and its particular language that, among other things, standardizes ways of expressing the characters emotions, the manga attracts attention and readers in different countries. This fact leads to the question: why the manga is so attractive to readers with such different profiles? Would it be the narrative, the graphic art, the characters, or the combination of all these elements? Given the difficulty of answering such a broad question, this research focused on analyzing the graphic art of the manga. The image is one of the central elements of comics, so someone can ask, for example, what resources the graphic art of the manga uses to attract its readers? Cartons researches have already analyzed the image elements (framing, lines of movement, lines of action, etc.), but a concept that is practically unexplored in academic research is the application of rhetoric figures of speech to images. The concept of figures of speech applied in a visual context which can emphasize certain moments of the narrative, expanding and reinforcing the meanings of the images in which they are applied. In addition, this research fills an academic gap, as a survey of literature showed that manga has been the object of study in several areas, however it is still poorly analyzed in the scope of design. Thus, this dissertation has an objective to identify how rhetoric figures of speech are used in the manga images. This research is classified as exploratory in nature, as it aims to create greater familiarity with the theme, in this case the manga. It has a descriptive objective because it aims to describe how rhetoric figures of speech is used in the manga images. And its approach is qualitative, as it seeks to understand the relationship between visual rhetoric and manga in a holistic way, providing results that can generate different interpretations of the analysis. The research methods applied were systematic bibliographic review and image analysis. The results obtained were an analysis protocol for comic books that allowed the elaboration of a preliminary diagnosis of the use of rhetoric figures of speech in the analyzed mangas images. The analysis of three different mangas points to a conscious and effective use by the mangakas (mangas authors) of the rhetoric figures of speech in a visual context, as well to the developed protocol's ability to provide conclusions about the use of these languages. On the other hand, it is worth mentioning the exploratory nature of this research, that is, the developed protocol must be applied to more samples so that one can both improve its elements of analysis, as well identify the scope of the use of figures of speech by the mangaka. Keywords: manga, visual rhetoric, rhetoric figures of speech, image