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Motivated by chromosomes enclosed in nucleus and the recently discovered active topological glass, we study a spherically confined melt of long nonconcatenated active polymer rings. Without activity, the rings exhibit the same average large-scale conformational properties as chromatin fiber. Upon activating consecutive monomer segments on the rings, the system arrives at a glassy steady state due to activity-enhanced topological constraints. The latter generate coherent motions of the system, however the resulting large-scale structures are inconsistent with the fractal globule model. We observe microphase separation between active and passive segments without systematic trends in the positioning of active domains within the confining sphere. We find that tank-treading of active segments along the ring contour enhances active-passive phase separation in the state of active topological glass when both diffusional and conformational relaxation of the rings are significantly suppressed. Finally, although the present model of partly-active rings is not compatible with the large-scale chromatin organization, our results suggest that the activity-enhanced entanglements that result in facilitated intra- and inter-chromosomal contacts might be relevant for chromatin structure at smaller scales.
Epithelial cell monolayers show remarkable displacement and velocity correlations over distances of ten or more cell sizes that are reminiscent of supercooled liquids and active nematics. We show that many observed features can be described within th
We report on the buckling and subsequent collapse of orthotropic elastic spherical shells under volume and pressure control. Going far beyond what is known for isotropic shells, a rich morphological phase space with three distinct regimes emerges upo
The glass transition remains unclarified in condensed matter physics. Investigating the mechanical properties of glass is challenging because any global deformation that may result in shear rejuvenation requires an astronomical relaxation time. Moreo
Spatially resolved electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) has been used to investigate as fluidic phase in nanoubbles embedded in a metallic Pd90Pt10 matrix. Using the 1s->2p excitation of the H
In living cells, proteins combine 3D bulk diffusion and 1D sliding along the DNA to reach a target faster. This process is known as facilitated diffusion, and we investigate its dynamics in the physiologically relevant case of confined DNA. The confi