By studying numerically the phase-ordering kinetics of a two-dimensional ferromagnetic Ising model with quenched disorder (either random bonds or random fields) we show that a critical percolation structure forms at an early stage. This structure is then rendered more and more compact by the ensuing coarsening process. Our results are compared to the nondisordered case, where a similar phenomenon is observed, and they are interpreted within a dynamical scaling framework.
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http://dx.doi.org/10.1103/PhysRevE.95.022101 | DOI Listing |
Soft Matter
September 2024
Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
Lung surfactant is inactivated in acute respiratory distress syndrome (ARDS) by a mechanism that remains unclear. Phospholipase (PLA) plays an essential role in the normal lipid recycling processes, but is present in elevated levels in ARDS, suggesting it plays a role in ARDS pathophysiology. PLA hydrolyzes lipids such as DPPC-the primary component of lung surfactant-into palmitic acid (PA) and lyso-PC (LPC).
View Article and Find Full Text PDFPhys Rev Lett
December 2023
Instituto de Física, Universidade Federal do Rio Grande do Sul, CP 15051, 91501-970, Porto Alegre RS, Brazil.
I report on the experimental confirmation that critical percolation statistics underlie the ordering kinetics of twisted nematic phases in the Allen-Cahn universality class. Soon after the ordering starts from a homogeneous disordered phase and proceeds toward a broken Z_{2}-symmetry phase, the system seems to be attracted to the random percolation fixed point at a special timescale t_{p}. At this time, exact formulas for crossing probabilities in percolation theory agree with the corresponding probabilities in the experimental data.
View Article and Find Full Text PDFJ Chem Phys
December 2023
Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
Using phase-field simulations, we investigate the bulk coarsening dynamics of ternary polymer solutions undergoing a glass transition for two models of phase separation: diffusion only and with hydrodynamics. The glass transition is incorporated in both models by imposing mobility and viscosity contrasts between the polymer-rich and polymer-poor phases of the evolving microstructure. For microstructures composed of polymer-poor clusters in a polymer-rich matrix, the mobility and viscosity contrasts significantly hinder coarsening, effectively leading to structural arrest.
View Article and Find Full Text PDFPhys Rev E
October 2022
Instituto de Física, Universidade Federal do Rio Grande do Sul, CP 15051, 91501-970, Porto Alegre RS, Brazil.
After a sudden quench from the disordered high-temperature T_{0}→∞ phase to a final temperature well below the critical point T_{F}≪T_{c}, the nonconserved order parameter dynamics of the two-dimensional ferromagnetic Ising model on a square lattice initially approaches the critical percolation state before entering the coarsening regime. This approach involves two timescales associated with the first appearance (at time t_{p_{1}}>0) and stabilization (at time t_{p}>t_{p_{1}}) of a giant percolation cluster, as previously reported. However, the microscopic mechanisms that control such timescales are not yet fully understood.
View Article and Find Full Text PDFACS Macro Lett
October 2021
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States.
We report a scalable melt blowing method for producing porous nonwoven fibers from model cocontinuous polystyrene/high-density polyethylene polymer blends. While conventional melt compounding of cocontinuous blends typically produces domain sizes ∼1-10 μm, melt blowing these blends into fibers reduces those dimensions up to 35-fold and generates an interpenetrating domain structure. Inclusion of ≤1 wt % of a block copolymer compatibilizer in these blends crucially enables access to smaller domain sizes in the fibers by minimizing thermodynamically-driven blend coarsening inherent to cocontinuous blends.
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