Temat: particle manipulation - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Capture efficiency of magnetically labeled particles traveling through an intracranial aneurysm
Autorzy:: Cardona, M.
Ramírez, J.
Benavides-Moran, A. G.
Powiązania:: https://bibliotekanauki.pl/articles/1839903.pdf
Data publikacji:: 2021
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:: magnetohydrodynamika
dynamika płynów
śródbłonek
endothelization
particle manipulation
computational fluid dynamics
magnetohydrodynamics
Opis:: Cell manipulation using external magnetic fields has been proposed to accelerate the neck reendothelization of saccular unruptured stented intracranial aneurysms. This work presents a computational fluid dynamics (CFD) model of a Saccular Brain Aneurysm that incorporates a helicoidal stent. An Eulerian-Lagrangian model implemented in ANSYS-Fluent is used to simulate the hemodynamics in the aneurysm. In silico studies have been conducted to describe the incidence of the magnetic field direction, frequency and amplitude on the blood hemodynamics and particle capture efficiency, when an external magnetic field is used to trap magnetically labeled particles traveling through the aneurysm. It is found that the magnetic field direction affects the particle concentration in the target region. Simulation results show that the highest particle capture efficiency is obtained with a 1T magnetic field amplitude in an open bore MRI scanner, when a permanent magnet is used.
Źródło:: International Journal of Applied Mechanics and Engineering; 2021, 26, 1; 65-75
1734-4492
2353-9003
Pojawia się w:: International Journal of Applied Mechanics and Engineering
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Physical restrictions of the flotation of fine particles and ways to overcome them
Autorzy:: Karakashev, Stoyan I.
Grozev, Nikolay A
Ozdemir, Orhan
Guven, Onur
Ata, Seher
Bournival, Ghislain
Batjargal, Khandjamts
Boylu, Feridun
Hristova, Svetlana
Çelik, Mehmet Sabri
Powiązania:: https://bibliotekanauki.pl/articles/2146879.pdf
Data publikacji:: 2022
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: fine particle flotation
frequency of collisions
surface force manipulation
thin wetting films
Opis:: This work analyses the basic problems of the fine particles flotation and suggests new ways to overcome them. It is well accepted that the poor recovery of fine particles is due to the small collision rate between them and the bubbles due to the significant difference between their sizes. This common opinion is based on a theory, assuming in its first version a laminar regime, but later has been advanced to intermediate turbulence. It accepts that the particles are driven by the streamlines near the bubbles. In reality, the high turbulence in the flotation cells causes myriads of eddies with different sizes and speeds of the rotation driving both bubbles and particles. Yet, a theory accounting for high turbulence exists and states that the collision rate could be much higher. Therefore, we assumed that the problem consists of the low attachment efficiency of the fine particles. Basically, two problems could exist (i) to form a three-phase contact line (TPCL) the fine particle should achieve a certain minimal penetration into the bubble, requiring sufficient push force; (ii) a thin wetting film between the bubble and the particle forms, thus increasing the hydrodynamic resistance between them and making the induction time larger than the collision time. We assumed particles with contact angle θ = 80°, and established a lower size flotation limit of the particles depending mostly on the size of the bubbles, with which they collide. It spans in the range of Rp = 0.16 um to Rp = 0.40 um corresponding to bubbles size range of Rb = 50 um to Rb = 1000 um. Hence, thermodynamically the particle size fraction in the range of Rp = 0.2 um to Rp = 2 um are permitted to float but with small flotation rate due to the small difference between the total push force and maximal resistance force for formation of TPCL. The larger particles approach slowly the bubbles, thus exceeding the collision time. Therefore, most possibly the cavitation of the dissolved gas is the reason for their attachment to the bubbles. To help fine particles float better, the electrostatic attraction between bubbles and particles occurred and achieved about 92% recovery of fine silica particles for about 100 sec. The procedure increased moderately their hydrophobicity from θ ≈ 27.4° to θ ≈ 54.5°. Electrostatic attraction between bubbles and particles with practically no increase of the hydrophobicity of the silica particles ended in 47% recovery. All this is an indication of the high collision rate of the fine particles with the bubbles. Consequently, both, an increase in the hydrophobicity and the electrostatic attraction between particles and bubbles are key for good fine particle flotation. In addition, it was shown experimentally that the capillary pressure during collision affected significantly the attachment efficiency of the particles to the bubbles.
Źródło:: Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 153944
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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