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We perform lattice Boltzmann simulations of an active nematic fluid confined in a two-dimensional channel to study the range of flow states that are stabilised by the confinement: unidirectional flow, oscillatory flow, the dancing state, localised active turbulence and fully-developed active turbulence. We analyse the flows in Fourier space, and measure a range of different length scales which describe the flows. We argue that the different states occur as a result of flow instabilities inherent to the system. As a consequence the characteristic length scale for oscillatory flow, the dancing state and localised active turbulence is set by the channel width. Fully-developed active turbulence occurs only when the channel width is larger than the intrinsic, active length scale of the bulk fluid. The results clarify why the activity number is a control parameter for the flow transitions.
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http://dx.doi.org/10.1039/d1sm01434j | DOI Listing |
Lab Chip
September 2025
Department of Biomedical Engineering, Lund University, Lund, Sweden.
Droplet splitting plays an important role in droplet microfluidics by providing precise control over droplet size, which is essential for applications such as single-cell analysis, biochemical reactions, and the fabrication of micro- and nanosized material. Conventional methods of droplet splitting using obstructions or junctions in the microchannel have a clear limitation that the split ratio for a particular device remains fixed, while existing active splitting methods are constrained by low flow rates, the need for complex systems, or limitations to specific droplet types. In this study, we demonstrate that droplet splitting can be achieved simply using a one-dimensional standing-wave field excited within a microchannel.
View Article and Find Full Text PDFRev Sci Instrum
September 2025
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
In this work, we developed a vacuum-compatible long trace profiler (LTP) for in situ metrology of ultra-precise x-ray optics within synchrotron vacuum chambers. Although traditional LTPs operate ex situ under atmospheric pressure, earlier optical setups-such as that by Qian et al.-performed in situ distortion measurements by directing laser beams through vacuum viewports.
View Article and Find Full Text PDFInt J Environ Res Public Health
July 2025
Department of Environment, Center for Energy, Environmental and Technological Research (CIEMAT), Avenida Complutense 40, 28040 Madrid, Spain.
According to the World Health Organization (WHO), indoor air quality (IAQ) is becoming a serious global concern due to its significant impact on human health. However, not all relevant health parameters are currently regulated. For example, particle number concentration (PNC) and its associated carbonaceous species, such as black carbon (BC), which are classified as carcinogenic by the International Agency for Research on Cancer (IARC), are not currently regulated.
View Article and Find Full Text PDFSports (Basel)
August 2025
Laboratory of Sports Medicine, Department of Physical Education and Sports Science, Aristotle University of Thessaloniki, 57001 Thessaloniki, Greece.
Adverse cardiovascular events and increased mortality are associated with cardiac autonomic nervous system dysfunction in the early stages of the systemic sclerosis (SSc), even prior to the development of cardiac fibrosis. The objective of the study was to evaluate the impact of a three-month exercise training regimen and a subsequent comparable period of detraining on the activity of the cardiac autonomic nervous system in patients with SSc. A total of forty patients with SSc were randomized to either the control group (Group COΝ) or the exercise training group (Group ET).
View Article and Find Full Text PDFSci Rep
August 2025
Department of Physics, Indian Institute of Technology (BHU), Varanasi, 221005, India.
We present a theoretical model to explore the dynamics and phase evolution of growing bacterial suspensions. The model described by the hydrodynamic evolution of bacterial density, orientation, and fluid velocity, incorporating birth and death terms to account for colony growth. Starting from a low-density regime, the system undergoes structural and dynamical transitions driven by bacterial proliferation, leading to the emergence of distinct phases: dilute, turbulent, and heterogenous.
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