We have explored the idea of producing the equilibrium equation of state, i.e. the pressure as a function of packing fraction, βP(φ), of a confined system up to very high pressures to yield the configuration that leads to the maximum packing fraction. For this purpose we have massively implemented the replica exchange Monte Carlo algorithm in graphics processing units (GPUs), in such a way that each GPU core handles a single simulation cell. This yields a very easy scheme to implement parallelization for a very large amount of replicas (thousands), which densely sample configuration space. We have tested this idea with a very well studied system, i.e. discs confined in a circular cavity, for a number of particles N ≤ 125. In all cases, our outcomes for configurations having maximum packing fractions are in perfect agreement with those already reported and conjectured optimal in the literature, for which there is no formal mathematical proof, strongly suggesting that they are indeed optimal configurations. Furthermore, in most cases, we have obtained the same function βP(φ), by compressing loose random configurations and by decompressing copies of the configuration having the largest packing fraction. This reveals numerically that the so obtained maximum packing configurations are the correct answer.
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http://dx.doi.org/10.1039/c8cp03727b | DOI Listing |
J Chem Phys
January 2025
Centre for Theoretical Chemistry and Physics, The New Zealand Institute for Advanced Study (NZIAS), Massey University Albany, Private Bag 102904, Auckland 0745, New Zealand.
The theory of periodic Barlow multi-lattices (X1X2…XN)∞ with Xi ∈ {A, B, C} and Xi ≠ Xi+1 of stacked two-dimensional hexagonal close-packed layers is presented and used to derive exact lattice sum expressions in terms of fast converging Bessel function expansions for inverse power potentials. We describe in detail the mathematical properties of Barlow sphere packings and demonstrate that only two basic lattice sums are required to describe all periodic packings. For the sticky hard-sphere model with an attractive inverse power law potential, we find a linear correlation between the cohesive energies of different Barlow packings and the face-centered cubic packing fraction.
View Article and Find Full Text PDF3D Print Addit Manuf
October 2024
Department of Mechanical Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, USA.
Digital light processing (DLP) is rapidly growing in popularity as an additive manufacturing method for the fabrication of composite structures, and is an effective way to prepare high-resolution filled parts, such as ceramic green parts or composite magnets. Yet, higher solid loadings of resins and the resulting dramatic increases in viscosity limit DLP printing for applications that depend upon maximization of filler content. In this work, we investigate the capacity of a bimodal particle size distribution to enable the printing of a photosensitive resin containing up to 70 vol% of fillers.
View Article and Find Full Text PDFJ Phys Chem B
December 2024
Department of Physics, University of South Florida, Tampa, Florida 33620, United States.
Using a Lubachevsky-Stillinger-like growth algorithm combined with biased SWAP Monte Carlo and transient degrees of freedom, we generate ultradense disordered jammed ellipse packings. For all aspect ratios α, these packings exhibit significantly smaller intermediate-wavelength density fluctuations and greater local nematic order than their less-dense counterparts. The densest packings are disordered despite having packing fractions ϕ(α) that are within less than 0.
View Article and Find Full Text PDFMedicine (Baltimore)
December 2024
Department of Cardiovascular Surgery, Ege University Faculty of Medicine, İzmir, Turkey.
The Pulse Index Contour Continuous Cardiac Output (PICCO) module provides advanced and continuous monitoring of cardiac output through the use of arterial pulse contour analysis and transpulmonary thermodilution. The objective of this study was to compare the early postoperative outcomes of patients who were monitored using the conventional method and the pulse contour analysis method. A prospective observational study was conducted involving 45 patients who underwent cardiac surgery between 2020 and 2022.
View Article and Find Full Text PDFACS Appl Polym Mater
December 2024
Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States.
Microgel suspensions have garnered significant interest in fundamental research due to their phase transition between liquid-like to paste-like behaviors stemming from tunable interparticle and particle-solvent interactions. Particularly, stimuli-responsive microgels undergo faster volume changes in response to external stimuli in comparison to their bulk counterparts, while maintaining their structural integrity. Here, concentrated and diluted suspensions of poly(-isopropylacrylamide) (PNIPAm) microgels are dispersed to different packing fractions in water for the characterizations of temperature-responsive rheological responses.
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