Cocoon microstructures through the lens of topological persistence.

Biological materials display a wide array of functionality, often dictated by complicated microstructures. New geometric and topological strategies allow one to describe the microstructures in a precise and systematic way. This article describes the application of topological persistence and other geometric methods to the microstructural analysis of three-dimensional X-ray micro-computed tomography scans of the silkworm cocoons.

Hydrolyzable tannins are incorporated into the endocarp during sclerification of the water caltrop Trapa natans.

The water caltrop (Trapa natans) develops unique woody fruits with unusually large seeds among aquatic plants. During fruit development, the inner fruit wall (endocarp) sclerifies and forms a protective layer for the seed. Endocarp sclerification also occurs in many land plants with large seeds; however, in T.

Adhesives free bark panels: An alternative application for a waste material.

The proportion of bark in tree trunks is in the range of ~ 10-20%. This large amount of material is currently mainly considered as a by- or even waste-product by the timber processing industry. Recently, efforts towards the use of bark have been made, e.

Curvature in Biological Systems: Its Quantification, Emergence, and Implications across the Scales.

Surface curvature both emerges from, and influences the behavior of, living objects at length scales ranging from cell membranes to single cells to tissues and organs. The relevance of surface curvature in biology is supported by numerous experimental and theoretical investigations in recent years. In this review, first, a brief introduction to the key ideas of surface curvature in the context of biological systems is given and the challenges that arise when measuring surface curvature are discussed.

Cellulose lattice strains and stress transfer in native and delignified wood.

Small specimens of spruce wood with different degrees of delignification were studied using in-situ tensile tests and simultaneous synchrotron X-ray diffraction to reveal the effect of delignification and densification on their tensile properties at relative humidities of 70-80 %. In addition to mechanical properties, these analyses yield the ratio of strains in the cellulose crystals and in the bulk, which reflects the stress-transfer to crystalline cellulose. While the specific modulus of elasticity slightly increases from native wood by partial or complete delignification, the lattice strain ratio does not show a significant change.

Repetitive hygroscopic snapping movements in awns of wild oats.

Wild oat (Avena sterilis) is a very common annual plant species. Successful seed dispersion support its wide distribution in Africa, Asia and Europe. The seed dispersal units are made of two elongated stiff awns that are attached to a pointy compartment containing two seeds.

Advanced materials design based on waste wood and bark.

Trees belong to the largest living organisms on Earth and plants in general are one of our main renewable resources. Wood as a material has been used since the beginning of humankind. Today, forestry still provides raw materials for a variety of applications, for example in the building industry, in paper manufacturing and for various wood products.

Microstructural features influencing the mechanical performance of the Brazil nut (Bertholletia excelsa) mesocarp.

Brazil nut (Bertholletia excelsa) fruits are capable of resisting high mechanical forces when released from trees as tall as 50 m, as well as during animal dispersal by sharp-teethed rodents. Thick mesocarp plays a crucial part in seed protection. We investigated the role of microstructure and how sclereids, fibers, and voids affect nutshell performance using compression, tensile and fracture toughness tests.

Topological Interlocking and Geometric Stiffening as Complementary Strategies for Strong Plant Shells.

Many organisms encapsulate their embryos in hard, protective shells. While birds and reptiles largely rely on mineralized shells, plants often develop highly robust lignocellulosic shells. Despite the abundance of hard plant shells, particularly nutshells, it remains unclear which fundamental properties drive their mechanical stability.

Wood and the Activity of Dead Tissue.

Wood is a prototypical biological material, which adapts to mechanical requirements. The microarchitecture of cellulose fibrils determines the mechanical properties of woody materials, as well as their actuation properties, based on absorption and desorption of water. Herein it is argued that cellulose fiber orientation corresponds to an analog code that determines the response of wood to humidity as an active material.

The Puzzle of the Walnut Shell: A Novel Cell Type with Interlocked Packing.

The outer protective shells of nuts can have remarkable toughness and strength, which are typically achieved by a layered arrangement of sclerenchyma cells and fibers with a polygonal form. Here, the tissue structure of walnut shells is analyzed in depth, revealing that the shells consist of a single, never reported cell type: the polylobate sclereid cells. These irregularly lobed cells with concave and convex parts are on average interlocked with 14 neighboring cells.

Unraveling the Rapid Assembly Process of Stiff Cellulosic Fibers from Mistletoe Berries.

The mucilaginous viscin tissue within mistletoe berries possesses an extraordinary ability to be rapidly processed under ambient conditions into stiff cellulosic fibers (>14 GPa) through simple mechanical drawing. This rapid and extreme transformation process is hydration-dependent and involves an astonishing >200-fold increase in length, providing a relevant role model for efforts to produce advanced composites from cellulose-based structures such as cellulose nanocrystals or cellulose nanofibrils. Using a combination of in situ polarized light microscopy, synchrotron X-ray scattering, and humidity-controlled mechanical analysis, we examine here the dynamic transition of a viscin cell bundle from hydrogel-like tissues to high-performance fibers.

An AP2/ERF transcription factor ERF139 coordinates xylem cell expansion and secondary cell wall deposition.

Differentiation of xylem elements involves cell expansion, secondary cell wall (SCW) deposition and programmed cell death. Transitions between these phases require strict spatiotemporal control. The function of Populus ERF139 (Potri.

Protecting Offspring Against Fire: Lessons From Seed Pods.

Wildfires are a natural component in many terrestrial ecosystems and often play a crucial role in maintaining biodiversity, particularly in the fire-prone regions of Australia. A prime example of plants that are able to persist in these regions is the genus . Most species that occur in fire-prone regions produce woody seed pods (follicles), which open during or soon after fire to release seeds into the post-fire environment.

Biological composites-complex structures for functional diversity.

The bulk of Earth's biological materials consist of few base substances-essentially proteins, polysaccharides, and minerals-that assemble into large varieties of structures. Multifunctionality arises naturally from this structural complexity: An example is the combination of rigidity and flexibility in protein-based teeth of the squid sucker ring. Other examples are time-delayed actuation in plant seed pods triggered by environmental signals, such as fire and water, and surface nanostructures that combine light manipulation with mechanical protection or water repellency.

Temperature-induced self-sealing capability of follicles.

Many plants in fire-prone regions retain their seeds in woody fruits in the plant canopy until the passage of a fire causes the fruit to open and release the seeds. To enable this function, suitable tissues are required that effectively store and protect seeds until they are released. Here, we show that three different species of the Australian genus incorporate waxes at the interface of the two valves of the follicle enclosing the seeds, which melt between 45°C and 55°C.

Climate-Dependent Heat-Triggered Opening Mechanism of Seed Pods.

Heat-triggered fruit opening and delayed release of mature seeds are widespread among plants in fire-prone ecosystems. Here, the material characteristics of the seed-containing follicles of (Proteaceae), which open in response to heat frequently caused by fire, are investigated. Material analysis reveals that long-term dimensional stability and opening temperatures of follicles collected across an environmental gradient increase as habitats become drier, hotter, and more fire prone.

Comparative in situ analysis reveals the dynamic nature of sclerenchyma cell walls of the fern Asplenium rutifolium.

Background And Aims: A key structural adaptation of vascular plants was the evolution of specialized vascular and mechanical tissues, innovations likely to have generated novel cell wall architectures. While collenchyma is a strengthening tissue typically found in growing organs of angiosperms, a similar tissue occurs in the petiole of the fern Asplenium rutifolium.

Methods: The in situ cell wall (ultra)structure and composition of this tissue was investigated and characterized mechanically as well as structurally through nano-indentation and wide-angle X-ray diffraction, respectively.

Combined serum free light chain levels are associated with carotid atherosclerosis in type 2 diabetes mellitus.

Background: Patients with type 2 diabetes mellitus face an increased risk of cardiovascular events compared to non-diabetic counterparts. Chronic inflammation and activation of the immune system, including B-lymphocyte maturation is believed to play a role in atherosclerosis. Recent investigations suggest combined serum free light chains as a potential biomarker for cardiovascular events.

Mechanoresponsive lipid-protein nanoglobules facilitate reversible fibre formation in velvet worm slime.

Velvet worms eject a fluid capture slime that can be mechanically drawn into stiff biopolymeric fibres. Remarkably, these fibres can be dissolved by extended exposure to water, and new regenerated fibres can be drawn from the dissolved fibre solution-indicating a fully recyclable process. Here, we perform a multiscale structural and compositional investigation of this reversible fabrication process with the velvet worm Euperipatoides rowelli, revealing that biopolymeric fibre assembly is facilitated via mono-disperse lipid-protein nanoglobules.

Age Effects on Hypocotyl Mechanics.

Numerous studies deal with composition and molecular processes involved in primary cell wall formation and alteration in Arabidopsis. However, it still remains difficult to assess the relation between physiological properties and mechanical function at the cell wall level. The thin and fragile structure of primary cell walls and their large biological variability, partly related to structural changes during growth, make mechanical experiments challenging.

A materials perspective of Martyniaceae fruits: Exploring structural and micromechanical properties.

Several species of the plant family Martyniaceae are characterised by unique lignified capsules with hook-shaped extensions that interlock with hooves and ankles of large mammals to disperse the seeds. The arrangement of fruit endocarp fibre tissues is exceptional and intriguing among plants. Structure-function-relationships of these slender, curved, but mechanically highly stressed fruit extensions are of particular interest that may inspire advanced biomimetic composite materials.

Structural and mechanical characterization of growing Arabidopsis plant cell walls.

This book chapter describes how structural and mechanical properties of living Arabidopsis hypocotyls can be measured by using small-angle X-ray scattering and micromechanical tensile tests. This approach is particularly useful to detect structural differences between selected mutants and to show how these differences are reflected in the tensile properties.

Omnidispersible poly(ionic liquid)-functionalized cellulose nanofibrils: surface grafting and polymer membrane reinforcement.

We report a facile one-step route to graft poly(ionic liquid)s (PILs) onto cellulose nanofibrils (CNFs). The dispersibility of the PIL-functionalized CNFs in water and various organic solvents could be tuned by the choice of the PIL-binding anion. We demonstrate that such omnidispersible PIL@CNF hybrids can be used to reinforce porous poly(ionic liquid) membranes.