Domain Size Driven Instability: Self-Organization in Systems with Advection

Václav Klika; Michal Kozák; Eamonn A. Gaffney

doi:10.1137/17m1138571

Filamentous active matter: Band formation, bending, buckling, and defects

Science Advances ◽

10.1126/sciadv.aaw9975 ◽

2020 ◽

Vol 6 (30) ◽

pp. eaaw9975 ◽

Cited By ~ 1

Author(s):

Gerard A. Vliegenthart ◽

Arvind Ravichandran ◽

Marisol Ripoll ◽

Thorsten Auth ◽

Gerhard Gompper

Keyword(s):

Molecular Motors ◽

Persistence Length ◽

Topological Defects ◽

Domain Size ◽

Self Organization ◽

Design Strategies ◽

Band Formation ◽

Microscopic Interactions ◽

Large Length ◽

Microscopy Techniques

Motor proteins drive persistent motion and self-organization of cytoskeletal filaments. However, state-of-the-art microscopy techniques and continuum modeling approaches focus on large length and time scales. Here, we perform component-based computer simulations of polar filaments and molecular motors linking microscopic interactions and activity to self-organization and dynamics from the filament level up to the mesoscopic domain level. Dynamic filament cross-linking and sliding and excluded-volume interactions promote formation of bundles at small densities and of active polar nematics at high densities. A buckling-type instability sets the size of polar domains and the density of topological defects. We predict a universal scaling of the active diffusion coefficient and the domain size with activity, and its dependence on parameters like motor concentration and filament persistence length. Our results provide a microscopic understanding of cytoplasmic streaming in cells and help to develop design strategies for novel engineered active materials.

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Antiphase Boundaries in Ordered Ni3FE Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006221x ◽

1969 ◽

Vol 27 ◽

pp. 62-63

Author(s):

Y. H. Liu

Keyword(s):

Domain Size ◽

Antiphase Domain ◽

X Ray Diffraction ◽

X Ray ◽

Hardening Mechanism ◽

Superlattice Structure ◽

Disordered Phase ◽

Domain Boundaries ◽

Atomic Scattering ◽

The Difference

Ordered Ni3Fe crystals possess a LI2 type superlattice similar to the Cu3Au structure. The difference in slip behavior of the superlattice as compared with that of a disordered phase has been well established. Cottrell first postulated that the increase in resistance for slip in the superlattice structure is attributed to the presence of antiphase domain boundaries. Following Cottrell's domain hardening mechanism, numerous workers have proposed other refined models also involving the presence of domain boundaries. Using the anomalous X-ray diffraction technique, Davies and Stoloff have shown that the hardness of the Ni3Fe superlattice varies with the domain size. So far, no direct observation of antiphase domain boundaries in Ni3Fe has been reported. Because the atomic scattering factors of the elements in NijFe are so close, the superlattice reflections are not easily detected. Furthermore, the domain configurations in NioFe are thought to be independent of the crystallographic orientations.

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Formation process of periodic non-conservative antiphase boundary structure in L-Pd5Ce

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173947 ◽

1990 ◽

Vol 48 (4) ◽

pp. 162-163

Author(s):

Masaru Itakura ◽

Noriyuki Kuwano ◽

Kensuke Oki

Keyword(s):

Formation Process ◽

Domain Size ◽

Antiphase Boundary ◽

Boundary Structure ◽

Temperature Phase ◽

Arc Melting ◽

Iced Water ◽

Antiphase Domains ◽

Low Temperature Phase ◽

Degree Of Order

The low temperature phase of Pd5Ce (L-Pd5Ce) has a one-dimensional long period superstructure (1D-LPS) derived from Ll2. The periodic antiphase boundaries (APBs) are parallel to (110) planes and have a shift vector of 1/2[110]. Hereafter, the indices are referred to the basic lattices of Ll2 As insertion of the APB causes a change in composition, such an APB is called “non-conservative”. Then, a domain size M depends upon the Ce concentration in the alloy. It was found that M increases also with temperature. The temperature dependency of M is attributed to a change of the degree of order within the antiphase domains. In this work, morphology of the non-conservative APBs is observed to clarify the formation process of the 1D-LPS.The alloy of Pd-16.7 at%Ce was prepared by arc melting in argon atmosphere. Disc specimens made from the alloy ingot were first held at 985 K for 260 ks and quenched in iced water to obtain the state of M=∞ or Ll2, followed by annealing for various lengths of time. The annealing temperature was 873 K where the equilibrium value for M is about 3 in unit of (110) lattice spacing of Ll2. Observation was carried out using microscopes JEM-2000FX, JEM-4000EX (HVEM Lab., Kyushu Univ.) and JEM-2000EX (Dept. of Mater. Sci. Tech., Kyushu Univ.).

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Domains and domain nucleation in magnetron-sputtered CoCr thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151064 ◽

1993 ◽

Vol 51 ◽

pp. 1046-1047

Author(s):

B. G. Demczyk

Keyword(s):

Thin Films ◽

Domain Structure ◽

Magnetic Domain ◽

Domain Size ◽

Film Plane ◽

Magnetic Domain Structure ◽

Perpendicular Magnetization ◽

Columnar Grains ◽

Reversal Mechanism ◽

Lorentz Transmission Electron Microscopy

CoCr thin films have been of interest for a number of years due to their strong perpendicular anisotropy, favoring magnetization normal to the film plane. The microstructure and magnetic properties of CoCr films prepared by both rf and magnetron sputtering have been examined in detail. By comparison, however, relatively few systematic studies of the magnetic domain structure and its relation to the observed film microstructure have been reported. In addition, questions still remain as to the operative magnetization reversal mechanism in different film thickness regimes. In this work, the magnetic domain structure in magnetron sputtered Co-22 at.%Cr thin films of known microstructure were examined by Lorentz transmission electron microscopy. Additionally, domain nucleation studies were undertaken via in-situ heating experiments.It was found that the 50 nm thick films, which are comprised of columnar grains, display a “dot” type domain configuration (Figure 1d), characteristic of a perpendicular magnetization. The domain size was found to be on the order of a few structural columns in diameter.

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