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1. Directed assembly of small binary clusters of magnetizable ellipsoids

   https://doi.org/10.1039/D4SM00300D  

   Harris, David H; Torres-Díaz, Isaac (August 2024, Soft Matter)

   We report the effect of shape anisotropy and material properties on the directed assembly of binary suspensions composed of magnetizable ellipsoids. In a Monte Carlo simulation, we implement the ellipsoid-dipole model to calculate the pairwise dipolar interaction energy as a function of position and orientation. The analysis explores dilute suspensions of paramagnetic and diamagnetic ellipsoids with different aspect ratios in a superparamagnetic medium. We analyze the local order of binary structuresas a function of particle aspect ratio, medium permeability, and dipolar interaction strength. Our results show that local order and symmetry are tunable under the influence of a uniform magnetic field when one component of the structure is dilute with respect to the other. The simulation results match previously reported experiments on the directed assembly of binary suspension of spheres. Additionally, we report the conditions on particle aspect ratios and medium properties for various structures with rotational symmetries, as well as open and enclosed structures under the influence of a uniform magnetic field. 

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2. Radiation-resistant binary solid solutions via vacancy trapping on solute clusters

   https://doi.org/10.1016/j.mtla.2021.101261  

   Daniels, Craig; Bellon, Pascal; Averback, Robert C. (November 2021, Materialia)

   Additions of solute that trap vacancies slow down vacancy diffusion and promote point-defect recombination in alloys subjected to irradiation. Such selective alloying can thus help to minimize the detrimental consequences resulting from point defect fluxes. The current work investigates the effect of solute additions on the recombi- nation rate using kinetic Monte Carlo simulations for a model alloy system, which was parametrized to Cu-Ag in the dilute limit, but with an increased solubility limit, ≈0.86 at.% at 300 K. As the solute concentration was increased above 0.1 at.%, solute clustering was observed and led to a strong increase in recombination rate. The beneficial effects of solute clustering on reducing vacancy mobility, and reducing solute drag, were analyzed by calculating relevant transport coefficients using the KineCluE code (Schuler et al., Computational Materials Science (2020) 172,109,191). Moreover, it was observed in the KMC simulations that large recombination rates resulted in a shift of steady-state distributions of solute cluster sizes to smaller clusters compared to equilibrium distributions in the solid solution. This shift is rationalized as resulting from the irreversible character of the interstitial-vacancy recombination reaction. These results suggest a novel irradiation effect on phase stability where a high recombination rate increases the solubility limit of a solute at steady state over its equilibrium value. 

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3. On the Rate of Neutron Star Binary Mergers from Globular Clusters

   https://doi.org/10.3847/2041-8213/ab5dc5  

   Ye, Claire S.; Fong, Wen-fai; Kremer, Kyle; Rodriguez, Carl L.; Chatterjee, Sourav; Fragione, Giacomo; Rasio, Frederic A. (January 2020, The Astrophysical Journal)
4. Stellar Dynamics in Open Clusters Increases the Binary Fraction and Mass Ratios: Evidence from Photometric Binaries in 35 Open Clusters

   https://doi.org/10.3847/1538-4357/ade9bc  

   Childs, Anna C; Geller, Aaron M (August 2025, The Astrophysical Journal)

   Using the Bayesian Analysis of Stellar Evolution-9 code and Gaia DR3, Pan-STARRS, and 2MASS data, we identify photometric binaries in 35 open clusters (OCs) and constrain their masses. We find a strong correlation between the binary fraction and cluster dynamical age and an even stronger correlation between core binary fraction and cluster dynamical age. We find that the binary mass-ratio (q) distribution of dynamically young OCs is statistically distinct from that of the old OCs. On average, dynamically young OCs display multimodalqdistributions rising toward unity and toward our detection limit ofq= 0.5 while more dynamically evolved clusters display more uniformqdistributions, often with a peak nearq= 1. Interestingly, the uniformqdistribution with a peak nearq= 1 is consistent with binaries in the field. We also observe a similar transition from multimodal to unimodalqdistributions when comparing low-mass to high-mass OCs in our sample. Finally, we find a correlation between the medianqof the binary population in a cluster and the cluster dynamical age. We interpret these results as an indication that dynamical encounters tend to increase the fraction of high-mass-ratio binaries within a given cluster—in particular within the cluster’s core, where stellar dynamics are likely more important. This may be the result of stellar exchanges that tend to produce binaries with largerqand/or the preferential disruption or evaporation of lower-qbinaries. 

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5. Intermediate-mass Black Holes from High Massive-star Binary Fractions in Young Star Clusters

   https://doi.org/10.3847/2041-8213/abdf5b  

   González, Elena; Kremer, Kyle; Chatterjee, Sourav; Fragione, Giacomo; Rodriguez, Carl L.; Weatherford, Newlin C.; Ye, Claire S.; Rasio, Frederic A. (February 2021, The Astrophysical Journal)

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