Some features of flow and particle transport in porous structures

There has been a growing interest in the study of porous and complex flow structures due to its impact in technology. This concerns not only environmental but also diagnostic and therapeutic exposure in medical research. Physics of flow within porous structures is especially important to model transport and deposition of viruses, pollutants and drugs deep in these structures. In this work we analyze numerically low and medium Reynolds number flows in axisymmetric cylindrical duct surrounded by a torus. We also consider three different particle sizes (0.02, 0.1 and 20 micron) for possible physiological and environmental applications

A reduced-order, rotation-based model for thin hard-magnetic plates

We develop a reduced-order model for thin plates made of hard magnetorheological elastomers (hard-MREs), which are materials composed of hard-magnetic particles embedded in a polymeric matrix. First, we propose a new magnetic potential, as an alternative to an existing torque-based 3D continuum theory of hard-MREs, obtained by reformulating the remnant magnetization of a deformed hard-MRE body. Specifically, the magnetizations in the initial and current configurations are related by the rotation tensor decomposed from the deformation gradient, independently of stretching deformation. This description is motivated by recently reported observations in microscopic homogenization simulations. Then, we derive a 2D plate model through the dimensional reduction of our proposed rotation-based 3D theory. For comparison, we also provide a second plate model derived from the existing 3D theory. Finally, we perform precision experiments to thoroughly evaluate the proposed 3D and 2D models on hard-magnetic plates under various magnetic and mechanical loading conditions. We demonstrate that our rotation-based modification of the magnetic potential is crucial in correctly capturing the behavior of plates subjected to an applied field aligned with the magnetization, and undergoing in-plane stretching. In all the tested cases, our rotation-based 3D and 2D models yield predictions in excellent quantitative agreement with the experiments and can thus serve as predictive tools for the rational design of hard-magnetic plate structures

IMUNOTERAPIA COM VENENO DE HIMENÓPTEROS: A EXPERIÊNCIA DE UMA CONSULTA

Resumo: Na Europa a prevalência de alergia ao veneno de himenópteros estima-se em 20%. As reacções sistémicas graves são indicação para imunoterapia específica com veneno de himenópteros após confirmação de atopia. Esta é eficaz em 91-100% dos casos de alergia ao veneno de vespa e 77-80% dos casos de alergia ao veneno de abelha. Apresentamos quatro casos clínicos de doentes com reacções sistémicas ao veneno de himenópteros que efectuaram imunoterapia. Três crianças apresentavam alergia ao veneno de abelha e uma ao veneno de vespa. Tinham IgE específica para o veneno de himenópteros, classes IV a VI. A duração da imunoterapia variou entre quatro e sete anos, com diminuição da classe de IgE específica em todos os doentes no final do tratamento. Três crianças tiveram contacto com o alergénio, durante ou após terminarem a imunoterapia, e nenhuma delas desencadeou uma reacção sistémica. A duração da imunoterapia continua a ser controversa. A ausência de reacção após contacto com o alergénio é sugestiva de sucesso do tratamento

Tração animal: uma experiência piloto no Pará.

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Disorder Averaging and Finite Size Scaling

We propose a new picture of the renormalization group (RG) approach in the presence of disorder, which considers the RG trajectories of each random sample (realization) separately instead of the usual renormalization of the averaged free energy. The main consequence of the theory is that the average over randomness has to be taken after finding the critical point of each realization. To demonstrate these concepts, we study the finite-size scaling properties of the two-dimensional random-bond Ising model. We find that most of the previously observed finite-size corrections are due to the sample-to-sample fluctuation of the critical temperature and scaling is more adequate in terms of the new scaling variables.Comment: 4 pages, 6 figures include

Designing a braille reader using the snap buckling of bistable magnetic shells

A design concept is introduced for the building block, a dot, of programmable braille readers utilizing bistable shell buckling, magnetic actuation, and pneumatic loading. The design process is guided by Finite Element simulations, which are initially validated through precision experiments conducted on a scaled-up, single-shell model system. Then, the simulations are leveraged to systematically explore the design space, adhering to the standardized geometric and physical specifications of braille systems. The findings demonstrate the feasibility of selecting design parameters that satisfy both geometric requirements and blocking forces under moderate magnetic fields, facilitated by pneumatic loading to switch between the two stable states. The advantages of the proposed design include the reversible bistability of the actuators and fast state-switching via a transient magnetic field. While the study is focused on experimentally validated numerical simulations, several manufacturing challenges that need to be resolved for future physical implementations are identified