RESUMEN
Here, we establish an approach to determine temperature-dependent aggregation rates in terms of thermostatistical quantities, which can be obtained directly from flat-histogram and statistical temperature algorithms considering the density of states of the system. Our approach is validated through simulations of an Ising-like model with anisotropically interacting particles at temperatures close to its first-order phase transition. Quantitative comparisons between the numerically obtained forward and reverse rates to approximate analytical expressions corroborate its use as a model-independent approach.
RESUMEN
The strain-induced softening behaviour observed in the differential modulus K(T,γ) of hydrogels is typically attributed to the breakage of internal network structures, such as the cross-links that bind the polymer chains. In this study, however, we consider a stress-strain relationship derived from a coarse-grained model to demonstrate that rupture of the network is not necessary for rubber-like gels to exhibit such behaviour. In particular, we show that, in some cases, the decrease of K(T,γ) as a function of the strain γ can be associated with the energy-related contribution to the elastic modulus that has been experimentally observed, e.g., for tetra-PEG hydrogels. Our findings suggest that the softening behaviour can be also attributed to the effective interaction between polymer chains and their surrounding solvent molecules, rather than the breakage of structural elements. We compare our theoretical expressions with experimental data determined for several hydrogels to illustrate and validate our approach.
RESUMEN
CONTEXT: Although the crystallization of monosodium urate monohydrate (MSUM) has a crucial role in the occurrence of gout, which is an inflammatory arthritis disease, theoretical models have not been able to describe all features observed in its seeded growth kinetics. In contrast to previous modeling approaches, we show that our model can reproduce qualitative features typically observed in experiments. In particular, our results show that the higher the initial supersaturation and the lower the viscosity, the faster the crystallization kinetics, and they also indicate that there are distinct growth regimes for low and high concentrations of seeds. METHODS: In this work, we introduce an alternative approach based on a master equation that allows us to incorporate hypotheses for the seeded growth crystallization of MSUM in a more transparent way. Such an approach includes not only effects that are related to the finite time-dependent supersaturation and concentration of seeds, but it can also be used to determine how the viscosity of the solution can affect the crystallization kinetics of MSUM molecules.