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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. [ABSTRACT FROM AUTHOR]

Nucleation of particles into crystalline structures can be observed in a wide range of systems from metallic and metal–organic compounds to colloidal and polymeric patch particles. Here, we perform kinetic Monte Carlo simulations to study the nucleation kinetics of particles with different ligancies z at constant supersaturation s. This approach allows one to determine several physico-chemical quantities as a function of s, including the growth probability P(n), the critical nucleus size n*, and the stationary nucleation rate Js. Our numerical results are rationalized in terms of a self-consistent nucleation theory where both n* and Js present a non-trivial dependence on s, but which can be determined from the values of effective z-dependent parameters. [ABSTRACT FROM AUTHOR]

Relations between static and dynamic viscoelastic responses in gels can be very elucidating and may provide useful tools to study the behavior of bio-materials such as protein hydrogels. An important example comes from the viscoelasticity of semisolid gel-like materials, which is characterized by two regimes: a low-frequency regime, where the storage modulus G'(ω) displays a constant value Geq, and a high-frequency power-law stiffening regime, where G'(ω) s ωn. Recently, by considering Monte Carlo simulations to study the formation of peptides networks, we found an intriguing and somewhat related power-law relationship between the plateau modulus and the threshold frequency, i.e., Geq ~ (ω*)β with β = 2/3. Here we present a simple theoretical approach to describe that relationship and test its validity by using experimental data from a --lactoglobulin gel.We show that our approach can be used even in the coarsening regime where the fractal model fails. Remarkably, the very same exponent β is found to describe the experimental data. [ABSTRACT FROM AUTHOR]

It is well-known that the swelling behavior of ionic nanogels depends on their cross-link density; however, it is unclear how different topologies should affect the response of the polyelectrolyte network. Here we perform Monte Carlo simulations to obtain the equilibrium properties of ionic nanogels as a function of salt concentration Cs and the fraction f of ionizable groups in a polyelectrolyte network formed by cross-links of functionality z. Our results indicate that the network with cross-links of low connectivity result in nanogel particles with higher swelling ratios.We also confirm a de-swelling effect of salt on nanogel particles. [ABSTRACT FROM AUTHOR]

We study the nucleation of model two-dimensional crystals formed from anisotropically interacting molecules using kinetic Monte Carlo simulations and the forward flux sampling algorithm. The growth probability P(n) of a cluster of n molecules is measured while the supersaturation s and interaction anisotropy of the molecules are varied, in order to gain insight into the nucleation mechanism. It is found that with increasing degree of interaction anisotropy the nucleus size (defined as the cluster size at which P(n) = 0.5) can increase with increasing s, with sharp jumps at certain s values. Analysis of the cluster shape reveals that nucleation in the system studied is of a non-standard form, in that it embodies elements of both the classical nucleation theory and the density functional theory frameworks. [ABSTRACT FROM AUTHOR]

In this paper, I present a simple and self-consistent framework based on microrheology that allows one to obtain the mechanical response of viscoelastic fluids and gels from the motion of probe particles immersed on it. By considering a non-Markovian Langevin equation, I obtain general expressions for the mean-squared displacement and the time-dependent diffusion coefficient that are directly related to the memory kernels and the response function, and which allow one to obtain estimates for the complex shear modulus and the complex viscosity of the material. The usefulness of such an approach is demonstrated by applying it to describe experimental data on chemically cross-linked polyacrylamide through its solgel transition. [ABSTRACT FROM AUTHOR]

We analyze the behavior of a quantum system described by a one-dimensional asymmetric potential consisting of a step plus a harmonic barrier. We solve the eigenvalue equation by the integral representation method, which allows us to classify the independent solutions as equivalence classes of homotopic paths in the complex plane. We then consider the propagation of a wave packet reflected by the harmonic barrier and obtain an expression for the interaction time as a function of the peak energy. For high energies we recover the classical half-period limit. [ABSTRACT FROM AUTHOR]