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Microgravity experiments on board the International Space Station, combined with particle-resolved direct numerical simulations, were conducted to investigate the long-term flocculation behavior of clay suspensions in saline water in the absence of gravity. After an initial homogenization of the suspensions, different clay compositions were continuously monitored for 99 days, allowing a detailed analysis of aggregate growth through image processing. The results indicate that the onboard oscillations (g-jitter) may have accelerated the aggregation process. Aggregate growth driven by these oscillations is found to occur at a faster rate than aggregation caused by Brownian motion. Complementary numerical simulations confirm this hypothesis and also demonstrate that parameters such as the oscillation amplitude and the solid volume fraction influence growth acceleration. These findings highlight that oscillations may act as a previously unrecognized mechanism that contributes to particle aggregation in fluids.
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http://dx.doi.org/10.1038/s41526-025-00523-7 | DOI Listing |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC12420831 | PMC |
NPJ Microgravity
September 2025
Department of Mechanical Engineering, UC Santa Barbara, Santa Barbara, CA, USA.
Microgravity experiments on board the International Space Station, combined with particle-resolved direct numerical simulations, were conducted to investigate the long-term flocculation behavior of clay suspensions in saline water in the absence of gravity. After an initial homogenization of the suspensions, different clay compositions were continuously monitored for 99 days, allowing a detailed analysis of aggregate growth through image processing. The results indicate that the onboard oscillations (g-jitter) may have accelerated the aggregation process.
View Article and Find Full Text PDFInt J Radiat Biol
September 2025
NASA Space Radiation Laboratory, Collider-Accelerator Dept., Brookhaven National Laboratory, Upton, NY, USA.
Purpose: Human space exploration is on an upward trajectory with new space stations being manufactured for scientific experiments, industrial development, and space tourism. These spacecraft in LEO and MEO will take advantage of Earth's magnetic field for radiation protection. Astronauts on the International Space Station receive an average radiation dose of 25 µSV/hour; around 250 times greater than the average sea level dose rate.
View Article and Find Full Text PDFNPJ Microgravity
September 2025
Department of Mathematical Sciences & Center for Applied Mathematics and Statistics, New Jersey Institute of Technology, Newark, NJ, USA.
Colloid-polymer mixtures are an archetype for modeling phase transition processes, as they exhibit a low-density gas phase, high-density crystalline phase and an intervening liquid phase. While their equilibrium behavior has been studied extensively, the role of hydrodynamics in driving their phase separation is not yet understood. We present a theoretical model that describes hydrodynamic interactions in colloid-polymer mixtures in a microgravity environment.
View Article and Find Full Text PDFNPJ Microgravity
August 2025
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki, 305-8505, Japan.
The LaO-NbO binary system is a unique glass-forming system without conventional network former oxides, exhibiting two distinct glass-forming regions: LaO-rich and NbO-rich compositions. To evaluate its glass-forming ability, the temperature dependence of density, viscosity, and surface tension was measured using the electrostatic levitation furnace aboard the International Space Station (ISS-ELF). Melt density showed linear temperature dependence, and thermal expansion coefficients at 2000 K varied from 2.
View Article and Find Full Text PDFSci Rep
August 2025
Division of Microsystems, Faculty of Electronics, Photonics and Microsystems, Wroclaw University of Science and Technology, 27 Wybrzeze Wyspianskiego Street, 50-370, Wroclaw, Poland.
There is an increase in demand for bio-nanosatellites and biomedical methodologies as a result of experiments conducted in microgravity and radiation conditions. Currently, the latest trend is to replace the experiments carried out by cosmonauts at the International Space Station (ISS) with research performed with the use of autonomous payload for nanosatellite. This paper describes the lab-payload for a biological nanosatellite of the CubeSat type with a size of 2U (10 × 10 × 20 cm).
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