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When a nematic liquid crystal is confined in a porous medium with strong anchoring conditions, topological defects, called disclinations, are stably formed with numerous possible configurations. Since the energy barriers between them are…

Soft Condensed Matter · Physics 2015-06-12 Takeaki Araki

We introduce a general description of localised distortions in active nematics using the framework of active nematic multipoles. We give the Stokesian flows for arbitrary multipoles in terms of differentiation of a fundamental flow response…

Soft Condensed Matter · Physics 2023-04-04 Alexander J. H. Houston , Gareth P. Alexander

Topological defects are an essential part of the structure and dynamics of all liquid crystals, and they are particularly important in experiments and simulations on active liquid crystals. In a recent paper, Vromans and Giomi [Soft Matter,…

Soft Condensed Matter · Physics 2017-08-23 Xingzhou Tang , Jonathan V. Selinger

The topological properties of many materials are central to their behavior, with the dynamics of topological defects being particularly important to intrinsically out-of-equilibrium, active materials. In this paper, local manipulation of…

Soft Condensed Matter · Physics 2019-11-01 David P. Rivas , Tyler N. Shendruk , Robert R. Henry , Daniel H. Reich , Robert L. Leheny

When considering flows in biological membranes, they are usually treated as flat, though more often than not, they are curved surfaces, even extremely curved, as in the case of the endoplasmic reticulum. Here, we study the topological…

Fluid Dynamics · Physics 2021-05-27 Rickmoy Samanta , Naomi Oppenheimer

Non-equilibrium dynamics of topological defects can be used as a fundamental propulsion mechanism in microscopic active matter. Here, we demonstrate swimming of topological defect-propelled colloidal particles in (passive) nematic fluids…

Soft Condensed Matter · Physics 2021-09-30 Tianyi Yao , Žiga Kos , Yimin Luo , Edward B. Steager , Miha Ravnik , Kathleen J. Stebe

Topological defects play a central role in the formation and organization of various biological systems. Historically, such nonequilibrium defects have been mainly studied in the context of homogeneous active nematics. Phase-separated…

Soft Condensed Matter · Physics 2023-07-13 Timo Krüger , Ivan Maryshev , Erwin Frey

Topological defects in systems with liquid-crystalline order are crucial in determining their large-scale properties. In active systems, they are known to have properties impossible at equilibrium: for example, $+1/2$ defects in…

Soft Condensed Matter · Physics 2026-02-17 Giacomo Marco La Montagna , Sumeja Burekovic , Ananyo Maitra , Cesare Nardini

Point-like topological defects are singular configurations that occur in a variety of in and out of equilibrium systems with two-dimensional orientational order. As they are associated with a nonzero circuitation condition, the presence of…

Statistical Mechanics · Physics 2023-07-13 Jacopo Romano , Benoît Mahault , Ramin Golestanian

The growing interest in active nematics and the emerging evidence of the relevance of topological defects in biology asks for reliable data analysis tools to identify, classify and track such defects in simulation and microscopy data. We…

Soft Condensed Matter · Physics 2020-02-10 Dennis Wenzel , Michael Nestler , Sebastian Reuther , Maximilian Simon , Axel Voigt

Active materials are capable of converting free energy into directional motion, giving rise to striking dynamical phenomena. Developing a general understanding of their structure in relation to the underlying non-equilibrium physics would…

Soft Condensed Matter · Physics 2018-10-17 Nitin Kumar , Rui Zhang , Juan J. de Pablo , Margaret L. Gardel

Using novel micro-printing techniques, we develop a versatile experimental setup that allows us to study how lateral confinement tames the active flows and defect properties of the microtubule/kinesin active nematic system. We demonstrate…

The self-propulsion of +1/2 topological defects is a hallmark of active nematic fluids, where the defects are advected by the flow field they themselves generate. In this paper we propose a minimal model for defect self-propulsion in a…

Soft Condensed Matter · Physics 2025-08-08 Fridtjof Brauns , Myles O'Leary , Arthur Hernandez , Mark J. Bowick , M. Cristina Marchetti

We characterise the particlelike kinematics of charge-carrying topological defects in nematic media via a geometric field theory. This differs from the theory of electromagnetism, with which it is often compared, due to the absence of…

Soft Condensed Matter · Physics 2026-05-22 Joseph Pollard , Richard G. Morris

We consider active nematodynamics on deformable surfaces. Based on a thermodynamically consistent surface Beris-Edwards model we add nematic activity and focus on the emerging additional coupling mechanism between the nematic field, the…

Soft Condensed Matter · Physics 2024-05-24 Ingo Nitschke , Axel Voigt

A nematic liquid crystal confined to the surface of a sphere exhibits topological defects of total charge $+2$ due to the topological constraint. In equilibrium, the nematic field forms four $+1/2$ defects, located at the corners of a…

Soft Condensed Matter · Physics 2020-07-22 Yi-Heng Zhang , Markus Deserno , Zhan-Chun Tu

Topological defects are a universal concept across many disciplines, such as crystallography, liquid-crystalline physics, low-temperature physics, cosmology, and even biology. In nematic liquid crystals, topological defects called…

Soft Condensed Matter · Physics 2024-06-19 Yohei Zushi , Cody D. Schimming , Kazumasa A. Takeuchi

Defects are a ubiquitous feature of ordered media. They have certain universal features, independent of the underlying physical system, reflecting their topological origins. While the topological properties of defects are robust, they…

Soft Condensed Matter · Physics 2021-02-24 Chiqun Zhang , Amit Acharya , Alan C. Newell , Shankar C. Venkataramani

Morphogenesis emerges from dynamic feedback among geometry, mechanics, and chemistry; however, disentangling these contributions in living systems remains challenging. Here, we focus on the interplay between geometry and mechanics by…

We study the topology of smectic defects in two and three dimensions. We give a topological classification of smectic point defects and disclination lines in three dimensions. In addition we describe the combination rules for smectic point…

Soft Condensed Matter · Physics 2019-11-19 Thomas Machon , Hillel Aharoni , Yichen Hu , Randall D. Kamien