Search results for "FLUID"

Pressure-Induced Deformation of Pillar-Type Profiled Membranes and Its Effects on Flow and Mass Transfer

2019

In electro-membrane processes, a pressure difference may arise between solutions flowing in alternate channels. This transmembrane pressure (TMP) causes a deformation of the membranes and of the fluid compartments. This, in turn, affects pressure losses and mass transfer rates with respect to undeformed conditions and may result in uneven flow rate and mass flux distributions. These phenomena were analyzed here for round pillar-type profiled membranes by integrated mechanical and fluid dynamics simulations. The analysis involved three steps: (1) A conservatively large value of TMP was imposed, and mechanical simulations were performed to identify the geometry with the minimum pillar density…

Shaping 1,2,4-Triazolium Fluorinated Ionic Liquid Crystals

2023

The synthesis and thermotropic behaviour of some di-alkyloxy-phenyl-1,2,4-triazolium trifluoromethane-sulfonate salts bearing a seven-carbon atom perfluoroalkyl chain on the cation is herein described. The fluorinated salts presenting a 1,2,4-triazole as a core and differing in the length of two alkyloxy chains on the phenyl ring demonstrated a typical liquid crystalline behaviour. The mesomorphic properties of this set of salts were studied by differential scanning calorimetry and polarized optical microscopy. The thermotropic properties are discussed on the grounds of the tuneable structures of the salts. The results showed the existence of a monotropic, columnar, liquid crystalline phase…

Eco-friendly cavity-containing iron oxides prepared by mild routes as very efficient catalysts for the total oxidation of VOCs

2018

Iron oxides (FeOx) are non-toxic, non-expensive and environmentally friendly compounds, which makes them good candidates for many industrial applications, among them catalysis. In the present article five catalysts based on FeOx were synthesized by mild routes: hydrothermal in subcritical and supercritical conditions (Fe-HT, Few200, Few450) and solvothermal (Fe-ST1 and Fe-ST2). The catalytic activity of these catalysts was studied for the total oxidation of toluene using very demanding conditions with high space velocities and including water and CO2 in the feed. The samples were characterized by X-ray diffraction (XRD), scanning and high-resolution transmission electron microscopy (SEM and…

Laboratory formation of a scaled protostellar jet by coaligned poloidal magnetic field

2014

International audience; Although bipolar jets are seen emerging from a wide variety of astrophysical systems, the issue of their formation and morphology beyond their launching is still under study. Our scaled laboratory experiments, representative of young stellar object outflows, reveal that stable and narrow collimation of the entire flow can result from the presence of a poloidal magnetic field whose strength is consistent with observations. The laboratory plasma becomes focused with an interior cavity. This gives rise to a standing conical shock from which the jet emerges. Following simulations of the process at the full astrophysical scale, we conclude that it can also explain recentl…

k-epsilon Predictions of Heat Transfer in Turbulent Recirculating Flows Using an Improved Wall Treatment

1989

Shape optimization for Stokes problem with threshold slip boundary conditions

2017

This paper deals with shape optimization of systems governed by the Stokes flow with threshold slip boundary conditions. The stability of solutions to the state problem with respect to a class of domains is studied. For computational purposes the slip term and impermeability condition are handled by a regularization. To get a finite dimensional optimization problem, the optimized part of the boundary is described by B´ezier polynomials. Numerical examples illustrate the computational efficiency. peerReviewed

Zastosowanie CFD w ocenie drożności górnych dróg oddechowych

2016

Obliczeniowa dynamika płynów (CFD) to szybko rozwijająca się dziedzina nauki, mająca szereg zastosowań praktyc - znych. Od lat używana jest w aerodynamice, inżynierii, hydraulice, meteorologii, budownictwie oraz wielu innych dziedz - inach. Pierwsze publikacje dotyczące użycia CFD w medycynie dotyczyły przede wszystkim pulmonologii i kardiologii, czyli dziedzin, w których dynamiczne właściwości gazu i płynu odgrywają ważną rolę w prawidłowym funkcjonowa - niu organizmu. W laryngologii CFD umożliwia pomiar oraz wizualizację dynamicznie zmieniających się parametrów przepływu powietrza w górnych drogach oddechowych.

DNA recovery from Droplet Digital™ PCR emulsions using liquid nitrogen

2020

Droplet microfluidics is a technology that enables the production and manipulation of small volumes. In biosciences, the most popular application of this technology is Droplet Digital™ PCR (ddPCR™), where parallel nanoliter-scale PCR assays are used to provide a high sensitivity and specificity for DNA detection. However, the recovery of PCR products for downstream applications such as sequencing can be challenging due to the droplets' stability. Here we compared five methods for disrupting the droplets to recover DNA. We found that rapid freezing in liquid nitrogen results in a clear phase separation and recovery of up to 70% of the DNA content. Liquid nitrogen freezing can thus offer a si…

Cerebrospinal fluid glucose and lactate concentrations after traumatic brain injury

2021

El estudio del metabolismo cerebral mediante el uso de la microdiálisis en el paciente con traumatismo craneoencefálico (TCE) ha puesto de manifiesto que un descenso a nivel cerebral en la concentración de glucosa o un ascenso de los niveles de lactato son marcadores de alteraciones en el metabolismo cerebral. Aun así, la microdiálisis no es una técnica de uso rutinario en la práctica clínica habitual en el momento actual y existen pocos datos y estudios acerca de las concentraciones de glucosa y lactato en líquido cefalorraquídeo (LCR) de estos pacientes. Este estudio analiza la relación entre los niveles de glucosa y lactato en LCR y el pronóstico de los pacientes tras el TCE. In patients…

Extraction of lapachol from Tabebuia avellanedae wood with supercritical CO2: an alternative to Soxhlet extraction?

2003

The solubility of lapachol in supercritical CO2 was determined at 40°C and pressures between 90 and 210 bar. Supercritical fluid extraction of lapachol and some related compounds by CO2 from Tabebuia avellanedae wood is compared to Soxhlet extraction with different solvents. A standard macroscale (100-200 g wood) and a microscale (~10 mg wood) experimental setup are described and their results are compared. The latter involved direct spectrophotometric quantification in a high-pressure autoclave with an integrated optical path and a magnetic stirrer, fitted directly into a commercial spectrophotometer. The relative amount of lapachol extracted by supercritical CO2 at 40°C and 200 bar was ab…