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1. Remarkable structural transformations of actin bundles are driven by their initial polarity, motor activity, crosslinking, and filament treadmilling

   https://doi.org/10.1371/journal.pcbi.1007156  

   Chandrasekaran, Aravind; Upadhyaya, Arpita; Papoian, Garegin A.; Cui, Qiang (July 2019, PLOS Computational Biology)
2. A novel filament design for improving fused filament fabrication of continuous fiber composites

   https://doi.org/10.1016/j.jmrt.2025.05.251  

   Parker, M; Norimatsu, S; Matsuzaki, R; Arola, D (July 2025, Journal of Materials Research and Technology)
3. Compressibility in Fused Filament Fabrication

   Kazmer, David O; Colon, Austin; Coogan, Timothy; Mubasshir, AA; Peterson, Amy (April 2020, Society of Plastics Engineers Annual Technical Conference)

   Fused filament fabrication (FFF) is one of the most accessible and flexible additive manufacturing processes. However, it is plagued by consistency issues related to material deposition. The role of compressibility is explored with an instrumented nozzle to relate the observed printing pressure to variations in deposited road widths. Variations in road width are analyzed relative to those predicted using a double domain Tait equation (PVT model) for high impact polystyrene (HIPS). Compressibility was found a critical effect, varying the road widths by up to 50% when accelerating and decelerating. The effect of the speed of transient stress propagation was also investigated but found insignificant. 

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4. Constant spacing in filament bundles

   https://doi.org/10.1088/1367-2630/ab1c2d  

   Atkinson, Daria W.; Santangelo, Christian D.; Grason, Gregory M. (June 2019, New Journal of Physics)

   Abstract Assemblies of one-dimensional filaments appear in a wide range of physical systems: from biopolymer bundles, columnar liquid crystals, and superconductor vortex arrays; to familiar macroscopic materials, like ropes, cables, and textiles. Interactions between the constituent filaments in such systems are most sensitive to thedistance of closest approachbetween the central curves which approximate their configuration, subjecting these distinct assemblies to common geometric constraints. In this paper, we consider two distinct notions of constant spacing in multi-filament packings in ${\mathbb{R}}^3$:equidistance, where the distance of closest approach is constant along the length of filament pairs; andisometry, where the distances of closest approach between all neighboring filaments are constant and equal. We show that, although any smooth curve in ${\mathbb{R}}^3$permits one dimensional families of collinear equidistant curves belonging to a ruled surface, there are only two families of tangent fields with mutually equidistant integral curves in ${\mathbb{R}}^3$. The relative shapes and configurations of curves in these families are highly constrained: they must be either (isometric) developable domains, which can bend, but not twist; or (non-isometric) constant-pitch helical bundles, which can twist, but not bend. Thus, filament textures that are simultaneously bent and twisted, such as twisted toroids of condensed DNA plasmids or wire ropes, are doubly frustrated: twist frustrates constant neighbor spacing in the cross-section, while non-equidistance requires additional longitudinal variations of spacing along the filaments. To illustrate the consequences of the failure of equidistance, we compare spacing in three ‘almost equidistant’ ansatzes for twisted toroidal bundles and use our formulation of equidistance to construct upper bounds on the growth of longitudinal variations of spacing with bundle thickness. 

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5. Velocities of an Erupting Filament

   https://doi.org/10.3847/1538-4357/ac3a04  

   Wang, Shuo; Jenkins, Jack M.; Muglach, Karin; Martinez Pillet, Valentin; Beck, Christian; Long, David M.; Choudhary, Debi Prasad; McAteer, James (February 2022, The Astrophysical Journal)

   Abstract Solar filaments exist as stable structures for extended periods of time before many of them form the core of a coronal mass ejection (CME). We examine the properties of an erupting filament on 2017 May 29–30 with high-resolution Hei10830 Å and Hαspectra from the Dunn Solar Telescope, full-disk Dopplergrams of Hei10830 Å from the Chromospheric Telescope, and EUV and coronograph data from SDO and STEREO. Pre-eruption line-of-sight velocities from an inversion of Heiwith the HAZEL code exhibit coherent patches of 5 Mm extent that indicate counter-streaming and/or buoyant behavior. During the eruption, individual, aligned threads appear in the Heivelocity maps. The distribution of velocities evolves from Gaussian to strongly asymmetric. The maximal optical depth of Hei10830 Å decreased fromτ= 1.75 to 0.25, the temperature increased by 13 kK, and the average speed and width of the filament increased from 0 to 25 km s⁻¹and 10 to 20 Mm, respectively. All data sources agree that the filament rose with an exponential acceleration reaching 7.4 m s⁻²that increased to a final velocity of 430 km s⁻¹at 22:24 UT; a CME was associated with this filament eruption. The properties during the eruption favor a kink/torus instability, which requires the existence of a flux rope. We conclude that full-disk chromospheric Dopplergrams can be used to trace the initial phase of on-disk filament eruptions in real time, which might potentially be useful for modeling the source of any subsequent CMEs. 

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