We revisit the classic problem of the effective diffusion constant of a Brownian particle in a square lattice of reflecting impenetrable hard disks. This diffusion constant is also related to the effective conductivity of non-conducting and infinitely conductive disks in the same geometry. We show how a recently derived Green's function for the periodic lattice can be exploited to derive a series expansion of the diffusion constant in terms of the disk's volume fraction φ. Second, we propose a variant of the Fick-Jacobs approximation to study the large volume fraction limit. This combination of analytical results is shown to describe the behavior of the diffusion constant for all volume fractions.
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http://dx.doi.org/10.1063/5.0009095 | DOI Listing |
J Colloid Interface Sci
January 2025
School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China. Electronic address:
The limited transport of oxygen at the solid-liquid interface and the poor charge separation efficiency of single catalyst significantly impedes the generation of reactive oxygen species (ROS), thereby weakening the application potential of photocatalytic technology in water pollution control. Herein, a hollow porous photocatalytic aerogel sphere (calcium alginate/cellulose nanofibers (CA/CNF)) loaded BiOBr/TiC, combining a favourable mass transfer structure with effective catalytic centers was firstly presented. The floatability and hollow pore structure facilitated rapid O transfer via a triphase interface, thereby promoting the generation of ROS.
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Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.
Single-Photon Avalanche Photodiodes (SPADs) are increasingly utilized in high-temperature-operated, high-performance Light Detection and Ranging (LiDAR) systems as well as in ultra-low-temperature-operated quantum science applications due to their high photon sensitivity and timing resolution. Consequently, the jitter value of SPADs at different temperatures plays a crucial role in LiDAR systems and Quantum Key Distribution (QKD) applications. However, limited studies have been conducted on this topic.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Institute of Process Equipment, College of Energy Engineering, Zhejiang University, Hangzhou 310007, China.
The hygrothermal aging model, based on Fick's second law of diffusion, characterizes the degradation of engineering constants in T700 carbon fiber/epoxy resin composites. It focuses on changes in the tensile modulus, shear modulus, and transverse Poisson's ratio due to moisture absorption and temperature variations. The model validates through mass change observations before and after seawater immersion, along with surface morphology assessments and tensile experiments.
View Article and Find Full Text PDFJ Comput Chem
January 2025
Department of Mechanical Engineering, Universidad Técnica Federico Santa María, Valparaíso, Chile.
The standard Poisson-Boltzmann (PB) model for molecular electrostatics assumes a sharp variation of the permittivity and salt concentration along the solute-solvent interface. The discontinuous field parameters are not only difficult numerically, but also are not a realistic physical picture, as it forces the dielectric constant and ionic strength of bulk in the near-solute region. An alternative to alleviate some of these issues is to represent the molecular surface as a diffuse interface, however, this also presents challenges.
View Article and Find Full Text PDFBiomimetics (Basel)
January 2025
College of Engineering, Design, and Physical Sciences, Brunel University London, Uxbridge UB8 3PH, UK.
The ability to control and manipulate biological fluids within microchannels is a fundamental challenge in biological diagnosis and pharmaceutical analyses, particularly when buffers with very high ionic strength are used. In this study, we investigate the numerical and experimental study of fluidic biochips driven by ac electrothermal flow for controlling and manipulating biological samples inside a microchannel, e.g.
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