Biomedical subjects

D R Reichman

Publications and source records attributed to D R Reichman.

5 recordsLinked to original sources

PubMed2005

Glasslike arrest in spinodal decomposition as a route to colloidal gelation.

Colloid-polymer mixtures can undergo spinodal decomposition into colloid-rich and colloid-poor regions. Gelation results when interconnected colloid-rich regions solidify. We show that this occurs when these regions undergo a glass transition, leading to dynamic arrest of the spinodal decomposition. The characteristic length scale of the gel decreases with increasing quench depth, and the nonergodicity parameter exhibits a pronounced dependence on scattering vector. Mode coupling theory gives a good description of the dynamics, provided we use the full static structure as input.

Colloids↗

PubMed2004

Out-of-equilibrium dynamical fluctuations in glassy systems.

In this paper we extend the earlier treatment of out-of-equilibrium mesoscopic fluctuations in glassy systems in several significant ways. First, via extensive simulations, we demonstrate that models of glassy behavior without quenched disorder display scalings of the probability of local two-time correlators that are qualitatively similar to that of models with short-ranged quenched interactions. The key ingredient for such scaling properties is shown to be the development of a criticallike dynamical correlation length, and not other microscopic details. This robust data collapse may be described in terms of a time-evolving "extreme value" distribution. We develop a theory to describe both the form and evolution of these distributions based on a effective sigma model approach.

Journal Article↗

PubMed2004

Anomalous diffusion probes microstructure dynamics of entangled F-actin networks.

We study the thermal motion of colloidal tracer particles in entangled actin filament (F-actin) networks, where the particle radius is comparable to the mesh size of the F-actin network. In this regime, the ensemble-averaged mean-squared displacement of the particles is proportional to tau(gamma), where 0<gamma<1 from 0.1<tau<100 s and depends only on the ratio of the probe radius to mesh size. By directly imaging hundreds of particles over 20 min, we determine this anomalous subdiffusion is due to the dynamics of infrequent and large jumps particles make between distinct pores in the network.

Actins↗

PubMed2001

Self-consistent mode-coupling theory for self-diffusion in quantum liquids.

A closed, self-consistent equation for the velocity autocorrelation function of a quantum liquid within the framework of a quantum mode-coupling theory is derived. The solution of the quantum generalized Langevin equation requires static input which is generated by an appropriate path-integral Monte Carlo scheme. In order to assess the accuracy of our approach we have studied the self-diffusion process of liquid para-hydrogen at two thermodynamic state points. Quantitative agreement for the self-diffusion constant is obtained in comparison to experimental measurements and other theoretical predictions.

Journal Article↗

PubMed2001

Mode-coupling theory of the fifth-order Raman spectrum of an atomic liquid.

A fully microscopic molecular hydrodynamic theory for the two-dimensional (fifth-order) Raman spectrum of an atomic liquid (Xe) is presented. The spectrum is obtained from a simple mode-coupling theory by projecting the dynamics onto bilinear pairs of fluctuating density variables. Good agreement is obtained in comparison with recently reported molecular dynamics simulation results. The microscopic theory provides an understanding of the timescales and molecular motions that govern the two-dimensional signal. Predictions are made for the behavior of the spectrum as a function of temperature and density. The theory shows that novel signatures in the two-dimensional Raman spectrum of supercritical and supercooled liquids are expected.

Journal Article↗