Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1910.13745

Mechanical behavior of a wormlike chain with variable bending rigidity along the chain contour in free space

Ming Li·Jizeng Wang
View original source ↗Read source document ↗Export metadata ↓

Abstract

In this paper, we present a theory to efficiently deal with mechanical properties of heterogeneous polymer chain in free space and the central problem is to evaluate the diffusion equation and orientation-orientation correlation function, under the condition of varying persistence length (a measure of bending rigidity) along the chain contour. Additionally, we give the specifically experimental method to measure the variable persistence length to examine our theory. In order to verify the theoretical predictions, we also performed large numbers of Brownian dynamics simulations based on the Generalized Bead-Rod (GBR) model and showed that our theory is in good agreement with simulation results. As an application, sequence dependence of the mechanical behavior of DNA chains is successfully analyzed and we have given the exact persistence length of basic dinucleotide steps, which is verified through using the basic steps to design other DNA fragments.

Explore related subjects

physics.bio-phcond-mat.soft

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Ming Li, Jizeng Wang. 2019-11-04. Mechanical behavior of a wormlike chain with variable bending rigidity along the chain contour in free space. https://arxiv.org/abs/1910.13745

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Biology and Physics

This article frames the relation between biology and physics by characterizing the former as a subdiscipline rather than a special case of the latter. To do this, we posit biological physics as the science of living matter in contrast to classic biophysics, the study of organismal properties by physical techniques. At the scale of the individual cell, living matter is nonunitary, i.e., not composed of aggregated subunits, and has features (e.g., intracellular organizational arrangements and biomolecular condensates) that are unlike any materials of the nonliving world. In transiently or constitutively multicellular forms (social microorganisms, animals, plants), living matter sustains physical processes that are generic (shared with nonliving matter, e.g., subunit communication by molecular diffusion in cellular slime molds), biogeneric (analogous to nonliving matter but realized through cellular activities, e.g., subunit demixing in animal embryos) or nongeneric (pertaining to sui generis materials, e.g., budding of active solids in plants). This "forms of matter" perspective is philosophically situated in the dialectical materialism of Engels and Hessen and the multilevel physicalism of Neurath and the logical empiricists. We counterpose this view to informationism and to genetic and other hierarchically reductionist physical theories of biological systems and highlight open questions regarding incompletely characterized and enigmatic forms of living matter.

physics.bio-ph↗
arXiv2026

Stabilizing by steering: Enhancing bacterial motility by non-uniform diffusiophoresis

Bacteria often traverse confined spaces to perform critical functions in symbiosis, infection, drug delivery, and soil bioremediation. While the canonical run-and-tumble strategy enables exploration, its reliance on stochastic reorientation limits efficiency under confinement. We show that salt gradients can physically steer Pseudomonas putida by biasing their runs toward salt through asymmetric diffusiophoretic forces. These gradients impose a torque strong enough to overcome Brownian rotation, aligning cells along the gradient and producing straighter, more persistent motion. This response persists in a Δ{cheA} mutant, demonstrating that canonical CheA-dependent chemotaxis is not required. We further show that when toxic organic contaminants are present, salt gradients promote bacterial dispersion toward the source despite reduced motility, suggesting potential applications in bacterial delivery for bioremediation. This work uncovers a previously unrecognized mechanism by which salt gradients direct bacterial motility, revealing a physical route to control microbial transport in complex environments.

physics.bio-ph↗
arXiv2026

Signature of mechanically induced cell extrusions in cell size distribution

How a growing tissue organizes its own homeostatic state is a central question in the physics of living matter. We show that when a growing epithelial sheet counteracts increasing cell density by mechanically squeezing cells out of its plane, a homeostatic in-plane pressure emerges as a generalization of a yield stress. We find that in the quasistatic growth limit the homeostatic state is marginally stable, with a pseudogap in the distribution of local distances to the extrusion threshold pressure. Because such mechanically induced extrusions arise from an instability of individual cells, the pseudogap is imprinted in the distribution of cell areas. This provides an image-based way to test for presence of mechanically induced extrusions and we identify this signature in the developing wing epithelium of \textit{D.~melanogaster}. We expect the same principles to apply to confined three-dimensional tissues.

physics.bio-ph↗