The sustained and warped helicoidal pattern of a xylan-cellulose composite: the stony endocarp model

Reis, Danièle; Roland, Jean-Claude; Mosiniak, M.; Darzens, D.; Vian, B.

doi:10.1007/bf01320139

Cited by 32 publications

(37 citation statements)

References 34 publications

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“…Increasing the elastic anisotropy and/or length scale (ξ/h 0 ), and/or decreasing the length scale (ξ/p 0 ), results in a reduced number of defects by bending and dilating the chiral nematic layers. In the natural helicoidal plywoods observed in plant cell walls [2,39,40], the layer bending and dilation mechanism is employed to structurally adapt to the presence of secondary phases such as cells, lumens and pit canals, thus avoiding energetically costly defects ( Figure 2 and 5(f)). The present model is able to reproduce the experimentally observed saddle defect observed in secondary cell wall of walnut [40].…”

Section: Discussionmentioning

confidence: 99%

“…Although in reality these cells are often irregular in shape and surface profile, the cells are represented by uniform circles in this model. Allowing this discrepancy is validated by the fact, known both from experiments [40] and simulations [35], that chiral nematic mesophase is robust enough to overcome surface irregularities and can form a monodomain after a finite healing length (usually in the order p 0 ). This geometry inherently generates anisotropic confinement in the domain of self assembly.…”

Section: Computational Domainmentioning

confidence: 91%

“…The presence of secondary phases, such as plant cells and pit canals in the domain of self-assembling cell wall material, are evidently the origin of surface constraints that results in distortions, vortices and defect disclinations, such as saddle-like patterns [39,40]. LC analogues in plant cell walls having the structure of chiral-nematic LC phases, can nucleate disclination characteristics of orientationally ordered nematic LCs, as well as dislocations characteristic of layered Smectic-A LCs.…”

Section: Introductionmentioning

confidence: 99%

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Modeling Textural Processes during Self-Assembly of Plant-Based Chiral-Nematic Liquid Crystals

Murugesan

Rey

2010

Polymers

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Biological liquid crystalline polymers are found in cellulosic, chitin, and DNA based natural materials. Chiral nematic liquid crystalline orientational order is observed frozen-in in the solid state in plant cell walls and is known as a liquid crystal analogue characterized by a helicoidal plywood architecture. The emergence of the plywood architecture by directed chiral nematic liquid crystalline self assembly has been postulated as the mechanism that leads to optimal cellulose fibril organization. In natural systems, tissue growth and development takes place in the presence of inclusions and secondary phases leaving behind characteristic defects and textures, which provide a unique testing ground for the validity of the liquid crystal self-assembly postulate. In this work, a mathematical model, based on the Landau-de Gennes theory of liquid crystals, is used to simulate defect textures arising in the domain of self assembly, due to presence of secondary phases representing plant cells, lumens and pit canals. It is shown that the obtained defect patterns observed in some plant cell walls are those expected from a truly liquid crystalline phase. The analysis reveals the nature and magnitude of the viscoelastic material parameters that lead to observed patterns in plant-based helicoids through directed self-assembly. In addition, the results provide new guidance to develop biomimetic plywoods for structural and functional applications.

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Section: Discussionmentioning

confidence: 99%

Section: Computational Domainmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Modeling Textural Processes during Self-Assembly of Plant-Based Chiral-Nematic Liquid Crystals

Murugesan

Rey

2010

Polymers

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“…In contrast the sclereids comprising the stony endocarp of Prunus spp. have beautifully complex, writhing microfibril patterns that leave little averaged orientation in any direction (Reis et al, 1992): an adaptation for hardness. Secondary wall structure is where form and function meet in sclerenchyma cells.…”

Section: Cell Wall Formationmentioning

confidence: 99%

Sclerenchyma

Jarvis

2012

Encyclopedia of Life Sciences

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Sclerenchyma is a specialised tissue, adapted to withstand both compressive and tensile stresses in plants. Sclerenchyma cell types may be divided into fibres, associated with phloem, xylem and other tissues; and sclereids or varied kinds. Sclereids originate from parenchyma and expand by intrusive growth. Phloem and xylem fibres in trees originate from the vascular cambium through delicately controlled, parallel cell divisions. Sclerenchyma cells have secondary wall layers that are constructed from cellulose microfibrils in a matrix of hemicelluloses and lignin. The cell geometry and the orientation of the cellulose are tailored to provide diverse combinations of strength, flexibility and stiffness in plant organs subjected to different loads by gravity, wind and weather. These properties are utilised in wood textiles and other natural materials of commercial importance. Key Concepts: Sclerenchyma is a plant tissue providing mechanical stiffness and strength. Fibres and sclereids are the main types of sclerenchyma cells. Most sclerenchyma cells show intrusive growth. The cell walls of sclerenchyma have thickened secondary layers made from cellulose, hemicelluloses and lignin. The stiffness of sclerenchyma depends on the orientation of cellulose and varies widely under developmental control. Formation of sclerenchyma is controlled by a range of transcription factors.

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“…16,27 The presence of secondary phases, such as plant cells and pit canals in the domain of self-assembling cell wall material are evidently the origin of surface constraints that result in distortions, vortices and defect disclinations such as saddlelike patterns. 32,33 LC analogues in plant cell wall having the structure of chiral-nematic LC phases, can nucleate disclinations characteristics of orientationally ordered nematic LCs as well as dislocations characteristic of layered Smectic-A LCs. 27 The core of disclinations can be singular, when the equilibrium orientational order is distorted or nonsingular, such that the rod-like molecules escape into the third dimen- sion avoiding gradients in molecular order.…”

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confidence: 99%

Liquid crystal models of biological materials and silk spinning

Rey

Herrera‐Valencia

2011

Biopolymers

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A review of thermodynamic, materials science, and rheological liquid crystal models is presented and applied to a wide range of biological liquid crystals, including helicoidal plywoods, biopolymer solutions, and in vivo liquid crystals. The distinguishing characteristics of liquid crystals (self-assembly, packing, defects, functionalities, processability) are discussed in relation to biological materials and the strong correspondence between different synthetic and biological materials is established. Biological polymer processing based on liquid crystalline precursors includes viscoelastic flow to form and shape fibers. Viscoelastic models for nematic and chiral nematics are reviewed and discussed in terms of key parameters that facilitate understanding and quantitative information from optical textures and rheometers. It is shown that viscoelastic modeling the silk spinning process using liquid crystal theories sheds light on textural transitions in the duct of spiders and silk worms as well as on tactoidal drops and interfacial structures. The range and consistency of the predictions demonstrates that the use of mesoscopic liquid crystal models is another tool to develop the science and biomimetic applications of mesogenic biological soft matter.

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The sustained and warped helicoidal pattern of a xylan-cellulose composite: the stony endocarp model

Cited by 32 publications

References 34 publications

Modeling Textural Processes during Self-Assembly of Plant-Based Chiral-Nematic Liquid Crystals

Modeling Textural Processes during Self-Assembly of Plant-Based Chiral-Nematic Liquid Crystals

Sclerenchyma

Liquid crystal models of biological materials and silk spinning

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