A Brownian dynamics simulation was carried out for a spherical nanoparticle with polymer chains tethered to its surface. These simulations are relevant to understanding the transport properties of polymer-stabilized nanoparticles in environmental and other applications. Hydrodynamic interactions (HI) were taken into account to properly describe the diffusion properties of a stabilized particle. HI are important in this context because of the close proximity of the surface-tethered polymer chains. HI were implemented using a method introduced by Fixman (1986 Macromolecules 19 1204), which uses a Chebyshev polynomial expansion to calculate the square root of the diffusion tensor. Simulation predictions were compared to published experimental data for the hydrodynamic radius of a silica particle stabilized by polystyrene tethered chains, and good agreement was achieved. A relationship that allows polymer-stabilized particles with arbitrary polymer-chain densities to be modelled is developed.
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http://dx.doi.org/10.1088/0957-4484/16/7/015 | DOI Listing |
Sci Rep
January 2025
Pesticide Formulation Research Department, Central Agriculture Pesticides Laboratory, Agricultural Research Center, Alexandria, Egypt.
J Colloid Interface Sci
December 2024
Wallenberg Wood Science Center, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden. Electronic address:
Hypothesis: Charge-stabilized colloidal cellulose nanocrystals (CNCs) can self-assemble into higher-ordered chiral nematic structures by varying the volume fraction. The assembly process exhibits distinct dynamics during the isotropic to liquid crystal phase transition, which can be elucidated using X-ray photon correlation spectroscopy (XPCS).
Experiments: Anionic CNCs were dispersed in propylene glycol (PG) and water spanning a range of volume fractions, encompassing several phase transitions.
J Neural Eng
January 2025
Center for Complex Systems and Brain Sciences, Universidad Nacional de San Martin Escuela de Ciencia Y Tecnologia, 25 de Mayo y Francia, San Martín, Buenos Aires, 1650, ARGENTINA.
Objective Magnetic resonance imaging (MRI), functional MRI (fMRI) and other neuroimaging techniques are routinely used in medical diagnosis, cognitive neuroscience or recently in brain decoding. They produce three- or four-dimensional scans reflecting the geometry of brain tissue or activity, which is highly correlated temporally and spatially. While there exist numerous theoretically guided methods for analyzing correlations in one-dimensional data, they often cannot be readily generalized to the multidimensional geometrically embedded setting.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Applied Theoretical Physics - Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany.
The self-assembly of biological membraneless organelles can be mimicked by active droplets resulting from chemically fueled microphase separation. However, how the nonequilibrium, transient structure of these active droplets can be controlled through the physicochemical input parameters is not yet well understood. In our work, a chemically fueled two-state chemical reaction and subsequent droplet growth and decay are modeled with a reactive Brownian dynamics simulation in two spatial dimensions.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Chan Zuckerberg Biohub-San Francisco, 499 Illinois Street, San Francisco, California 94158, USA.
Influenza A viruses (IAVs) must navigate through a dense extracellular mucus to infect airway epithelial cells. The mucous layer, composed of glycosylated biopolymers (mucins), presents sialic acid that binds to ligands on the viral envelope and can be irreversibly cleaved by viral enzymes. It was recently discovered that filamentous IAVs exhibit directed persistent motion along their long axis on sialic acid-coated surfaces.
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