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1. Phase-separating pyrenoid proteins form complexes in the dilute phase

   https://doi.org/10.1038/s42003-022-04373-x  

   He, Guanhua; GrandPre, Trevor; Wilson, Hugh; Zhang, Yaojun; Jonikas, Martin C.; Wingreen, Ned S.; Wang, Quan (December 2023, Communications Biology)

   Abstract While most studies of biomolecular phase separation have focused on the condensed phase, relatively little is known about the dilute phase. Theory suggests that stable complexes form in the dilute phase of two-component phase-separating systems, impacting phase separation; however, these complexes have not been interrogated experimentally. We show that such complexes indeed exist, using an in vitro reconstitution system of a phase-separated organelle, the algal pyrenoid, consisting of purified proteins Rubisco and EPYC1. Applying fluorescence correlation spectroscopy (FCS) to measure diffusion coefficients, we found that complexes form in the dilute phase with or without condensates present. The majority of these complexes contain exactly one Rubisco molecule. Additionally, we developed a simple analytical model which recapitulates experimental findings and provides molecular insights into the dilute phase organization. Thus, our results demonstrate the existence of protein complexes in the dilute phase, which could play important roles in the stability, dynamics, and regulation of condensates. 

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2. Elasticity versus phase field driven motion in the phase field crystal model

   https://doi.org/10.1088/1361-651X/ac860b  

   Acharya, Amit; Angheluta, Luiza; Viñals, Jorge (August 2022, Modelling and Simulation in Materials Science and Engineering)

   Abstract The inherent inconsistency in identifying the phase field in the phase field crystal theory with the material mass and, simultaneously, with material distortion is discussed. In its current implementation, elastic relaxation in the phase field crystal occurs on a diffusive time scale through a dissipative permeation mode. The very same phase field distortion that is included in solid elasticity drives diffusive motion, resulting in a non physical relaxation of the phase field crystal. We present two alternative theories to remedy this shortcoming. In the first case, it is assumed that the phase field only determines the incompatible part of the elastic distortion, and therefore one is free to specify an additional compatible distortion so as to satisfy mechanical equilibrium at all times (in the quasi static limit). A numerical solution of the new model for the case of a dislocation dipole shows that, unlike the classical phase field crystal model, it can account for the known law of relative motion of the two dislocations in the dipole. The physical origin of the compatible strain in this new theory remains to be specified. Therefore, a second theory is presented in which an explicit coupling between independent distortion and phase field accounts for the time dependence of the relaxation of fluctuations in both. Preliminary details of its implementation are also given. 

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3. First-Order Phase Transition in Liquid Ag to the Heterogeneous G-Phase

   https://doi.org/10.1021/acs.jpclett.9b03699  

   An, Qi; Johnson, William L.; Samwer, Konrad; Corona, Sydney L.; Goddard, William A. (January 2020, The Journal of Physical Chemistry Letters)

   null (Ed.)
4. First-Order Phase Transition in Liquid Ag to the Heterogenous G-Phase

   https://doi.org/10.1021  

   Qi, An; Johnson, William L.; Samwar, Konrad; Corona, Sydney L.; Goddard III, William A. (January 2020, The journal of physical chemistry letters)

   A molten metal is an atomic liquid that lacks directional bonding and is free from chemical ordering effects. Experimentally, liquid metals can be undercooled by up to ∼20% of their melting temperature but crystallize rapidly in subnanosecond time scales at deeper undercooling. To address this limited metastability with respect to crystallization, we employed molecular dynamics simulations to study the thermodynamics and kinetics of the glass transition and crystallization in deeply undercooled liquid Ag. We present direct evidence that undercooled liquid Ag undergoes a first-order configurational freezing transition from the high-temperature homogeneous disordered liquid phase (L) to a metastable, heterogeneous, configura-tionally ordered state that displays elastic rigidity with a persistent and finite shear modulus, μ. We designate this ordered state as the G-phase and conclude it is a metastable non-crystalline phase. We show that the L−G transition occurs by nucleation of the G-phase from the L-phase. Both te L- and G-phases are metastable because both ultimately crystallize. The observed first-order transition is reversible: the G-phase displays a first-order melting transition to the L-phase at a coexistence temperature, TG,M. We develop a thermodynamic description of the two phases and their coexistence boundary. 

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5. Probing the phase transformation and dislocation evolution in dual-phase high-entropy alloys

   https://doi.org/10.1016/j.ijplas.2018.10.014  

   Fang, Qihong; Chen, Yang; Li, Jia; Jiang, Chao; Liu, Bin; Liu, Yong; Liaw, Peter K. (March 2019, International Journal of Plasticity)