scholarly journals Microscale modelling of dielectrophoresis assembly processes

2021 ◽  
Vol 379 (2208) ◽  
pp. 20200407 ◽  
Author(s):  
A. Tiribocchi ◽  
A. Montessori ◽  
M. Lauricella ◽  
F. Bonaccorso ◽  
K. A. Brown ◽  
...  
Keyword(s):  
Hierarchical Structures ◽  
Dynamics Simulation ◽  
Theme Issue ◽  
Quantitative Characterization ◽  
Topological Features ◽  
Numerical Tool ◽  
Microscale Modelling ◽  
Design And Manufacture ◽  
New Strategies ◽  
Microscale Approach

This work presents a microscale approach for simulating the dielectrophoresis assembly of polarizable particles under an external electric field. The model is shown to capture interesting dynamical and topological features, such as the formation of chains of particles and their incipient aggregation into hierarchical structures. A quantitative characterization in terms of the number and size of these structures is also discussed. This computational model could represent a viable numerical tool to study the mechanical properties of particle-based hierarchical materials and suggest new strategies for enhancing their design and manufacture. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

The consequences of hierarchy for modeling in forest ecosystems

2000 ◽  
Vol 30 (12) ◽  
pp. 1837-1846 ◽  
Author(s):  
Andrew P Robinson ◽  
Alan R Ek
Keyword(s):  
Forest Ecosystem ◽  
Forest Ecosystems ◽  
Model Building ◽  
Hierarchical Structures ◽  
Ecosystem Dynamics ◽  
Model Construction ◽  
Ecosystem Models ◽  
Model Classification ◽  
New Strategies

An overview of forest ecosystem models in the context of hierarchies is presented, considering spatiophysical, mechanistic, temporal, usage, and range resolutions. We argue that models of forest ecosystem dynamics can be treated as inherently hierarchical structures of discrete submodels or modules. These submodels represent distinct but connected processes, such as growth, mortality, or regeneration. This approach has important ramifications for model building, fitting, criticism, and application. It provides new strategies for dealing with common modeling problems, such as component choice, as well as placing in context established modeling strategies. A system of categories that avoids popular and simplistic dichotomies is provided to assist in model classification. The need for more sophisticated techniques at each stage of model construction is demonstrated, and candidate solutions are suggested.

scholarly journals Topological Features of the Alluaudite-Type Framework and Its Derivatives: Synthesis and Crystal Structure of NaMnNi2(H2/3PO4)3

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 237
Author(s):  
Sergey M. Aksenov ◽  
Natalia A. Yamnova ◽  
Natalia A. Kabanova ◽  
Anatoly S. Volkov ◽  
Olga A. Gurbanova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Topological Analysis ◽  
Structure Type ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Quantitative Characterization ◽  
Synthesis And Crystal Structure ◽  
Topological Features ◽  
Nickel Phosphate

A new sodium manganese-nickel phosphate of alluaudite supergroup with the general formula NaMnNi2(H2/3PO4)3 was synthesized by a hydrothermal method. The synthesis was carried out in the temperature range from 540 to 660 K and at the general pressure of 80 atm from the oxides mixture in the molar ratio MnCl2: 2NiCl2: 2Na3PO4: H3BO3: 10H2O. The crystal structure was studied by a single-crystal X-ray diffraction analysis: space group C2/c (No. 15), a = 16.8913(4), b = 5.6406(1), c = 8.3591(3) Å, β = 93.919(3), V = 794.57(4) Å3. The compound belongs to the alluaudite structure type based upon a mixed hetero-polyhedral framework formed by MX6-octahedra and TX4-tetrahedra. The characteristic feature of the title compound is the absence of cations or H2O molecules in channel II, while the negative charge of the framework is balanced by the partial protonation of PO4 tetrahedra. The presence of the transition metals at the A-type sites results in the changes of stoichiometry and the local topological features. Topological analysis of the hetero-polyhedral alluaudite-type frameworks and its derivatives (johillerite-, KCd4(VO4)3-, and keyite-type) and quantitative characterization of their differences was performed by means of natural tilings.

scholarly journals A fast and efficient deep learning procedure for tracking droplet motion in dense microfluidic emulsions

2021 ◽  
Vol 379 (2208) ◽  
pp. 20200400 ◽  
Author(s):  
Mihir Durve ◽  
Fabio Bonaccorso ◽  
Andrea Montessori ◽  
Marco Lauricella ◽  
Adriano Tiribocchi ◽  
...  
Keyword(s):  
Deep Learning ◽  
Clustering Algorithms ◽  
Dynamics Simulation ◽  
General Study ◽  
Theme Issue ◽  
Droplet Motion ◽  
Fluid Systems ◽  
Learning Procedure ◽  
Biological Flows ◽  
Learning Technique

We present a deep learning-based object detection and object tracking algorithm to study droplet motion in dense microfluidic emulsions. The deep learning procedure is shown to correctly predict the droplets’ shape and track their motion at competitive rates as compared to standard clustering algorithms, even in the presence of significant deformations. The deep learning technique and tool developed in this work could be used for the general study of the dynamics of biological agents in fluid systems, such as moving cells and self-propelled microorganisms in complex biological flows. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

scholarly journals From vesicles to materials: bioinspired strategies for fabricating hierarchically structured soft matter

2021 ◽  
Vol 379 (2206) ◽  
pp. 20200338
Author(s):  
Esther Amstad ◽  
Matthew J. Harrington
Keyword(s):  
Soft Matter ◽  
Hierarchical Structures ◽  
Polymeric Materials ◽  
Advanced Materials ◽  
Ambient Conditions ◽  
Theme Issue ◽  
Structured Materials ◽  
Multi Scale ◽  
Condensed Liquid ◽  
Mussel Byssus

Certain organisms including species of mollusks, polychaetes, onychophorans and arthropods produce exceptional polymeric materials outside their bodies under ambient conditions using concentrated fluid protein precursors. While much is understood about the structure-function relationships that define the properties of such materials, comparatively less is understood about how such materials are fabricated and specifically, how their defining hierarchical structures are achieved via bottom-up assembly. Yet this information holds great potential for inspiring sustainable manufacture of advanced polymeric materials with controlled multi-scale structure. In the present perspective, we first examine recent work elucidating the formation of the tough adhesive fibres of the mussel byssus via secretion of vesicles filled with condensed liquid protein phases (coacervates and liquid crystals)—highlighting which design principles are relevant for bio-inspiration. In the second part of the perspective, we examine the potential of recent advances in drops and additive manufacturing as a bioinspired platform for mimicking such processes to produce hierarchically structured materials. This article is part of the theme issue ‘Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)’.

scholarly journals Director alignment at the nematic–isotropic interface: elastic anisotropy and active anchoring

2021 ◽  
Vol 379 (2208) ◽  
pp. 20200394 ◽  
Author(s):  
Rodrigo C. V. Coelho ◽  
Nuno A. M. Araújo ◽  
Margarida M. Telo da Gama
Keyword(s):  
Elastic Anisotropy ◽  
Dynamics Simulation ◽  
Interfacial Flows ◽  
Hydrodynamic Models ◽  
Theme Issue ◽  
Translational Invariance ◽  
Active Length ◽  
Wide Range ◽  
The One ◽  
Preferential Alignment

Activity in nematics drives interfacial flows that lead to preferential alignment that is tangential or planar for extensile systems (pushers) and perpendicular or homeotropic for contractile ones (pullers). This alignment is known as active anchoring and has been reported for a number of systems and described using active nematic hydrodynamic theories. The latter are based on the one-elastic constant approximation, i.e. they assume elastic isotropy of the underlying passive nematic. Real nematics, however, have different elastic constants, which lead to interfacial anchoring. In this paper, we consider elastic anisotropy in multiphase and multicomponent hydrodynamic models of active nematics and investigate the competition between the interfacial alignment driven by the elastic anisotropy of the passive nematic and the active anchoring. We start by considering systems with translational invariance to analyse the alignment at flat interfaces and, then, consider two-dimensional systems and active nematic droplets. We investigate the competition of the two types of anchoring over a wide range of the other parameters that characterize the system. The results of the simulations reveal that the active anchoring dominates except at very low activities, when the interfaces are static. In addition, we found that the elastic anisotropy does not affect the dynamics but changes the active length that becomes anisotropic. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

scholarly journals Imaging and analysis of a three-dimensional spider web architecture

2018 ◽  
Vol 15 (146) ◽  
pp. 20180193 ◽  
Author(s):  
Isabelle Su ◽  
Zhao Qin ◽  
Tomás Saraceno ◽  
Adrian Krell ◽  
Roland Mühlethaler ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Three Dimensional ◽  
Hierarchical Structures ◽  
Material Design ◽  
Spider Web ◽  
Topological Features ◽  
Web Architecture ◽  
Orb Web ◽  
2D Images ◽  
3D Web

Spiders are abundantly found in nature and most ecosystems, making up more than 47 000 species. This ecological success is in part due to the exceptional mechanics of the spider web, with its strength, toughness, elasticity and robustness, which originate from its hierarchical structures all the way from sequence design to web architecture. It is a unique example in nature of high-performance material design. In particular, to survive in different environments, spiders have optimized and adapted their web architecture by providing housing, protection, and an efficient tool for catching prey. The most studied web in literature is the two-dimensional (2D) orb web, which is composed of radial and spiral threads. However, only 10% of spider species are orb-web weavers, and three-dimensional (3D) webs, such as funnel, sheet or cobwebs, are much more abundant in nature. The complex spatial network and microscale size of silk fibres are significant challenges towards determining the topology of 3D webs, and only a limited number of previous studies have attempted to quantify their structure and properties. Here, we focus on developing an innovative experimental method to directly capture the complete digital 3D spider web architecture with micron scale resolution. We built an automatic segmentation and scanning platform to obtain high-resolution 2D images of individual cross-sections of the web that were illuminated by a sheet laser. We then developed image processing algorithms to reconstruct the digital 3D fibrous network by analysing the 2D images. This digital network provides a model that contains all of the structural and topological features of the porous regions of a 3D web with high fidelity, and when combined with a mechanical model of silk materials, will allow us to directly simulate and predict the mechanical response of a realistic 3D web under mechanical loads. Our work provides a practical tool to capture the architecture of sophisticated 3D webs, and could lead to studies of the relation between architecture, material and biological functions for numerous 3D spider web applications.

Topological features of structural relaxations in a two-dimensional model atomic glass II

1989 ◽  
Vol 329 (1608) ◽  
pp. 575-593 ◽  
Keyword(s):  
Molecular Dynamics ◽  
Dynamics Simulation ◽  
Two Dimensional ◽  
Structure And Properties ◽  
High Angle ◽  
Stable Sets ◽  
Dimensional Model ◽  
Topological Features ◽  
Atom Clusters ◽  
Two Dimensional Model

The topological features of atom motions in a high-temperature melt, a sub-cooled melt above T g , and a glass below T g , were analysed in detail by means of a two-dimensional molecular dynamics simulation. A striking analogy was observed between the structure and properties of the liquid-like material separating quasi-ordered domains of atom clusters, and high-angle grain boundaries. The main feature of the structural relaxation below the melting point, both above and below T g was the gradual dissolution and disappearance of the liquid-like material, permitting increasing order in the previously quasi-ordered domains and a growth in their sizes. In these processes, many sequences reminiscent of cancellation of dislocation pairs, or mutual reactions to give more stable sets, were observed.

Realtime Rigid Folding Algorithm for Quadrilateral-Based 1-DOF Tessellations

2013 ◽  
Author(s):  
Yves Klett
Keyword(s):  
Real Time ◽  
Three Dimensional ◽  
Unit Cell ◽  
Degree Of Freedom ◽  
Folding Process ◽  
Topological Features ◽  
Folding Algorithm ◽  
Successful Design ◽  
Foldable Structures ◽  
Design And Manufacture

Origami tessellations consisting of repetitively tiled unit cell elements can be used to manufacture cellular three-dimensional structures with interesting mechanical and other properties. In recent years, the search for alternative and innovative core materials for sandwich constructions has resulted in renewed interest in such foldable structures. The ability to simulate the folding process of such structures with one kinematic degree of freedom is essential for their successful design and manufacture. We present an algorithm that allows for the implicit calculation of arbitrary rigid folding states of quadrilateral-based structures with certain topological features. This enables reliable real-time virtual folding of a large number of important tessellation types which has been put to good use in numerous projects.

scholarly journals Salt- and gas-filled ices under planetary conditions

2019 ◽  
Vol 377 (2146) ◽  
pp. 20180262 ◽  
Author(s):  
Livia E. Bove ◽  
Umbertoluca Ranieri
Keyword(s):  
Molecular Dynamics ◽  
High Pressure ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Theme Issue ◽  
Planetary Interiors ◽  
Guest Species ◽  
Gas Molecules ◽  
Simulation Results ◽  
Experimental Findings

In recent years, evidence has emerged that solid water can contain substantial amounts of guest species, such as small gas molecules—in gas hydrate structures—or ions—in salty ice structures—and that these ‘filled’ ice structures can be stable under pressures of tens of Gigapascals and temperatures of hundreds of Kelvins. The inclusion of guest species can strongly modify the density, vibrational, diffusive and conductivity properties of ice under high pressure, and promote novel exotic properties. In this review, we discuss our experimental findings and molecular dynamics simulation results on the structures formed by salt- and gas-filled ices, their unusual properties, and the unexpected dynamical phenomena observed under pressure and temperature conditions relevant for planetary interiors modelling. This article is part of the theme issue ‘The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets’.

scholarly journals Lattice Boltzmann simulations on the tumbling to tank-treading transition: effects of membrane viscosity

2021 ◽  
Vol 379 (2208) ◽  
pp. 20200395 ◽  
Author(s):  
Fabio Guglietta ◽  
Marek Behr ◽  
Luca Biferale ◽  
Giacomo Falcucci ◽  
Mauro Sbragaglia
Keyword(s):  
Lattice Boltzmann ◽  
Viscosity Ratio ◽  
Dynamics Simulation ◽  
Theme Issue ◽  
Membrane Viscosity ◽  
Lattice Boltzmann Simulations ◽  
Realistic Description ◽  
Transition Effects ◽  
Lattice Boltzmann Models ◽  
Range Of Values

The tumbling to tank-treading (TB-TT) transition for red blood cells (RBCs) has been widely investigated, with a main focus on the effects of the viscosity ratio λ (i.e., the ratio between the viscosities of the fluids inside and outside the membrane) and the shear rate γ ˙ applied to the RBC. However, the membrane viscosity μ m plays a major role in a realistic description of RBC dynamics, and only a few works have systematically focused on its effects on the TB-TT transition. In this work, we provide a parametric investigation on the effect of membrane viscosity μ m on the TB-TT transition for a single RBC. It is found that, at fixed viscosity ratios λ , larger values of μ m lead to an increased range of values of capillary number at which the TB-TT transition occurs; moreover, we found that increasing λ or increasing μ m results in a qualitatively but not quantitatively similar behaviour. All results are obtained by means of mesoscale numerical simulations based on the lattice Boltzmann models. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

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