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The problem of controlling cylindrical tank bioreactor conditions for cell and tissue culture purposes has been considered from a flow dynamics perspective. Simple laminar flows in the vortex breakdown region are proposed as being a suitable alternative to turbulent spinner flask flows and horizontally oriented rotational flows. Vortex breakdown flows have been measured using three-dimensional Stereoscopic particle image velocimetry, and non-dimensionalized velocity and stress distributions are presented. Regions of locally high principal stress occur in the vicinity of the impeller and the lower sidewall. Topological changes in the vortex breakdown region caused by an increase in Reynolds number are reflected in a redistribution of the peak stress regions. The inclusion of submerged scaffold models adds complexity to the flow, although vortex breakdown may still occur. Relatively large stresses occur along the edge of disks jutting into the boundary of the vortex breakdown region.
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http://dx.doi.org/10.1002/bit.20960 | DOI Listing |
Materials (Basel)
August 2025
Photovoltaic Technologies Laboratory, Department of Physics, Faculty of Fundamental Sciences, Vilnius Gediminas Technical University (Vilnius Tech), Saulėtekio av. 3, LT-10257 Vilnius, Lithuania.
The transport properties of biased type II superconductors are strongly influenced by external magnetic fields, which play a crucial role in optimizing the stability and performance of low-noise superconducting electronic devices. A major challenge is the stochastic behavior of Abrikosov vortices, which emerge in the mixed state and lead to energy dissipation through their nucleation, motion, and annihilation. Uncontrolled vortex dynamics can introduce electronic noise in low-power systems and trigger thermal breakdown in high-power applications.
View Article and Find Full Text PDFRep Prog Phys
September 2025
Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-sen University, Guangzhou 510275, People's Republic of China.
Since 2009, magnetic skyrmions have been identified in diverse materials, attracting interest for their small size, intriguing emergent physics and new device concepts. Over the years, the interplay between deformation and dynamics has been an important topic of magnetic textures, with well-known phenomena like Döring mass, domain wall Walker breakdown and vortex oscillations. This topic is being extended to magnetic skyrmions and is critical for their practical applications.
View Article and Find Full Text PDFUltrason Sonochem
September 2025
State Key Laboratory of Hydroscience and Engineering, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of CO(2) Utilization and Reduction Technology, Tsinghua University, Beijing 100084, China. Electronic address:
Hydrodynamic cavitation (HC) surge accompanied by strong swirl is widely present in fluid machinery and has become a hot topic in many engineering fields. This paper employed a two-way coupling Eulerian-Lagrangian multiscale cavitation modeling method to investigate the unsteady characteristics of HC surge under two typical conditions in a diffuser with swirling flow. Compared with the available experimental data, the quasi-periodic growth, shedding and fragmentation of HC surge into discrete bubbles are well reproduced by the multiscale cavitation modeling method.
View Article and Find Full Text PDFUltrasonics
December 2025
Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan. Electronic address:
Transdermal delivery is a convenient and noninvasive route for drug administration across several medical applications. However, its efficacy is significantly hindered by the barrier function of the skin stratum corneum. Previous studies have investigated various ultrasound-based configurations for noninvasively enhancing transdermal drug penetration; however, the requirements for prolonged sonication, high energy levels, and microbubble cavitation have raised safety concerns.
View Article and Find Full Text PDFElife
July 2025
Laboratory for Physical Biology, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan.
The chirality of tissues and organs is essential for their proper function and development. Tissue-level chirality derives from the chirality of individual cells that comprise the tissue, and cellular chirality is considered to emerge through the organization of chiral molecules within the cell. However, the principle of how molecular chirality leads to cellular chirality remains unresolved.
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