Do you want to publish a course? Click here

Microphase separation as the cause of structural complexity in 2D liquids

95   0   0.0 ( 0 )
 Publication date 2013
  fields Physics
and research's language is English




Ask ChatGPT about the research

Complex behavior in glassforming liquids is associated with formation of a mosaic of different structures. Using bond order parameters together with topological characteristics of the bond network, we show that in the mosaic of crystalline and amorphous clusters found in a 2D liquid the difference between structural sub- components translates into a difference between two coexisting phases. We suggest that the observed microphase separated mosaic is a 2D realization of what is usually invoked to explain special features found in 3D complex liquids. Conditions favoring mosaic stability are discussed; these conditions include a new type of critical behavior and long-range correlations between sub-component clusters.



rate research

Read More

Non-equilibrium phase separating systems with reactions can break time-reversal symmetry (TRS) in two distinct ways. Firstly, the conservative and non-conservative sectors of the dynamics can be governed by incompatible free energies; when both sectors are present, this is the leading-order TRS violation, captured in its simplest form by Model AB. Second, the diffusive dynamics can break TRS in its own right. This happens only at higher order in the gradient expansion (but is the leading behaviour without reactions present) and is captured by Active Model B+ (AMB+). Each of the two mechanisms can lead to microphase separation, by quite different routes. Here we introduce Model AB+, for which both mechanisms are simultaneously present, and show that for slow reaction rates the system can undergo a new type of hierarchical microphase separation, whereby a continuous phase of fluid 1 contains large droplets of fluid 2 within which small droplets of fluid 1 are continuously created and then absorbed into the surrounding fluid-1 phase. In this state of bubbly microphase separation the small-scale 1-in-2 droplets arise by the conservative diffusive dynamics with the larger scale 2-in-1 structure governed by the nonconservative reactions.
We review the mechanism and consequences of the bridging-induced attraction, a generic biophysical principle which underpins some existing models for chromosome organisation in 3-D. This attraction, which was revealed in polymer physics-inspired computer simulations, is a generic clustering tendency arising in multivalent chromatin-binding proteins, and it provides an explanation for the biogenesis of nuclear bodies and transcription factories via microphase separation. Including post-translational modification reactions involving these multivalent proteins can account for the fast dynamics of the ensuing clusters, as is observed via microscopy and photobleaching experiments. The clusters found in simulations also give rise to chromatin domains which conform well with the observation of A/B compartments in HiC experiments.
143 - E. Kirkinis , A.V. Andreev , 2011
We introduce a new mechanism for the propulsion and separation by chirality of small ferromagnetic particles suspended in a liquid. Under the action of a uniform d.c. magnetic field H and an a.c. electric field E isomers with opposite chirality move in opposite directions. Such a mechanism could have a significant impact on a wide range of emerging technologies. The component of the chiral velocity that is odd in H is found to be proportional to the intrinsic orbital and spin angular momentum of the magnetized electrons. This effect arises because a ferromagnetic particle responds to the applied torque as a small gyroscope.
We have evidenced by small angle neutron scattering at low temperature the coexistence of ferromagnetism (F) and antiferromagnetism (AF) in Pr0.67Ca0.33MnO3. The results are compared to those obtained in Pr0.80Ca0.20MnO3 and Pr0.63Ca0.37MnO3, which are F and AF respectively. Quantitative analysis shows that the small angle scattering is not due to a mesoscopic mixing but to a nanoscopic electronic and magnetic red cabbage structure, in which the ferromagnetic phase exists in form of thin layers in the AF matrix (stripes or 2D sheets).
Volume and enthalpy relaxation of glasses after a sudden temperature change has been extensively studied since Kovacs seminal work. One observes an asymmetric approach to equilibrium upon cooling versus heating and, more counter-intuitively, the expansion gap paradox, i.e. a dependence on the initial temperature of the effective relaxation time even close to equilibrium when heating. Here we show that a distinguishable-particles lattice model can capture both the asymmetry and the expansion gap. We quantitatively characterize the energetic states of the particles configurations using a physical realization of the fictive temperature called the structural temperature, which, in the heating case, displays a strong spatial heterogeneity. The system relaxes by nucleation and expansion of warmer mobile domains having attained the final temperature, against cooler immobile domains maintained at the initial temperature. A small population of these cooler regions persists close to equilibrium, thus explaining the paradox.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا