DOI: 10.5061/dryad.b8gtht7n0
title: Asymmetric fluctuations and self-folding of active interfaces

description: We study the structure and dynamics of the interface separating a passive
 fluid from a microtubule-based active fluid. Turbulent-like active flows
 power giant interfacial fluctuations, which exhibit pronounced asymmetry
 between regions of positive and negative curvature. Experiments, numerical
 simulations, and theoretical arguments reveal how the interface breaks up
 the spatial symmetry of the fundamental bend instability to generate local
 vortical flows that lead to asymmetric interface fluctuations. The
 magnitude of interface deformations increases with activity: In the high
 activity limit, the interface self-folds invaginating passive droplets and
 generating a foam-like phase, where active fluid is perforated with
 passive droplets. These results demonstrate how active stresses control
 the structure, dynamics, and break-up of soft, deformable, and
 reconfigurable liquid-liquid interfaces.
description: This README.txt file was generated on 2024-12-05 by Liang Zhao #
 Asymmetric fluctuations and self-folding of active interfaces
 [https://doi.org/10.5061/dryad.b8gtht7n0](https://doi.org/10.5061/dryad.b8gtht7n0) Author: Liang Zhao Affiliation: Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106 Email: [liang_zhao@ucsb.edu](mailto:liang_zhao@ucsb.edu) PI: Zvonimir Dogic Affiliation: Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106 and Interdisciplinary Program in Quantitative Biosciences, University of California, Santa Barbara, Santa Barbara, CA 93106 Email: [zdogic@ucsb.edu](mailto:zdogic@ucsb.edu) This work was primarily supported by the US Department of Energy, Office of Basic Energy Sciences under award number DE-SC0019733. Development and optimization of the two-phase system of active liquid–liquid phase separation was supported by NSF-ISS-2224350. We also acknowledge the use of the biosynthesis facility supported by NSF-MRSEC2011846 and NRI-MCDB Microscopy Facility supported by the NIH Shared Instrumentation Grant 1S10OD019969-01A1. Use was made of computational facilities purchased with funds from the NSF (CNS-1725797) and administered by the Center for Scientific Computing (CSC). The CSC is supported by the California NanoSystems Institute and the Materials Research Science and Engineering Center (NSF DMR 2308708). ## Overview: The zip "Data" contains the experimental data.  The subfolder "curvature" contains those for calculating curvature values in Fig.3 a-b. The folders 46nM, 83nM, 129nM and 183nM are for experimental datasets containing different concentrations of kinesin-streptavidin clusters (KSA). In each folder, the subfolder "interface" contains the raw interface at each time frame between the two separated phases as sets of all points on the interface. Each .ply file is one time point. The file can be opened and visualized through the open-source software MeshLab ([https://www.meshlab.net/#download](https://www.meshlab.net/#download)) or processed with the code "getcurvature.m" in the "Code/curvature" subfolder. The subfolder "mesh" contains the rescaled mesh grid of those corresponding interfaces and those .ply files can be opened and processed in the same way.  The subfolder "curvature" contains the local curvature values everywhere on those interfaces calculated from the corresponding interfaces and meshes. The file parameters.mat contains the information of the frames. The subfolder "droplet" contains the experimental data for calculating droplet volume in Fig. 7c and fractions of dextran and PEG in Fig.8b. The subfolders "high_tension" and "low_tension" are experimental datasets of two samples with different surface tension. In each folder, the files contain the fraction of dextran bulk, peg bulk and peg droplets at each depth of the sample. Each file contains one single variable with rows corresponding to the depth and columns corresponding to each time frame. The file can be processed with the code "analyzedroplets_fraction.m" in the "Code/droplet" subfolder. The zip "Code" contains all the necessary scripts needed for processing the data in "Data.zip". The subfolders "curvature" and "droplet" correspond to the folders with the same names in the data. To run the code in "curvature", first download the directory '@TubULAR' and 'DECLab @ 527c50d' from [https://github.com/npmitchell/tubular](https://github.com/npmitchell/tubular). The code "getcurvature.m" calculates the curvatures from the interface data as mentioned above. It calls python programs in "Mesh Lab Python Scripts" to convert the interface data to mesh, and it uses codes in "DECLab" and "TubULAR" to calculate the curvatures from the mesh. "Additional Functions", "Matrix Manipulation Functions" and "Mesh Manipulation Functions" are other helper functions. The code "curvature_distribution.m" calculates curvature distribution from the calculated curvatures. The subfolder "droplet" contains only one file "analyzedroplets_fraction.m", which calculates the droplet volume and fractions of dextran from the data in "Data/droplet".