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Articles 1 - 30 of 65
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Darwin's Bark Spider: Giant Prey In Giant Orb Webs (Araneidae: Caerostris Darwini), Todd Blackledge, Matjaz Gregoric, Ingi Agnarsson, Matjaz Kuntner
Darwin's Bark Spider: Giant Prey In Giant Orb Webs (Araneidae: Caerostris Darwini), Todd Blackledge, Matjaz Gregoric, Ingi Agnarsson, Matjaz Kuntner
Todd A. Blackledge
Although the diversity of spider orb web architectures is impressive, few lineages have evolved orb webs larger than lm in diameter. Until recently, such web gigantism was reported only in a few nephilids and araneids. However, new studies on bark spiders (Caerostris) of Madagascar report a unique case of web gigantism: Darwin's bark spider (C. darwini) casts its webs over substantial water bodies, and these webs are made from silk whose toughness outperforms all other known spider silks. Here we investigate C darwini web architecture and provide data to begin to answer two intriguing questions to explain these extraordinary web …
Conflicts Around A Study Of Mexican Crops., Todd Blackledge
Conflicts Around A Study Of Mexican Crops., Todd Blackledge
Todd A. Blackledge
No abstract provided.
High-Performance Spider Webs: Integrating Biomechanics, Ecology And Behaviour, Todd Blackledge, Aaron Harmer, Joshua Madin, Marie Herberstein
High-Performance Spider Webs: Integrating Biomechanics, Ecology And Behaviour, Todd Blackledge, Aaron Harmer, Joshua Madin, Marie Herberstein
Todd A. Blackledge
Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence …
Spider Dragline Silk: Correlated And Mosaic Evolution In High-Performance Biological Materials, Todd Blackledge, Brook Swanson, Cheryl Hayashi, Adam Summers
Spider Dragline Silk: Correlated And Mosaic Evolution In High-Performance Biological Materials, Todd Blackledge, Brook Swanson, Cheryl Hayashi, Adam Summers
Todd A. Blackledge
The evolution of biological materials is a critical, yet poorly understood, component in the generation of biodiversity. For example, the diversification of spiders is correlated with evolutionary changes in the way they use silk, and the material properties of these fibers, such as strength, toughness, extensibility, and stiffness, have profound effects on ecological function. Here, we examine the evolution of the material properties of dragline silk across a phylogenetically diverse sample of species in the Araneomorphae (true spiders). The silks we studied are generally stronger than other biological materials and tougher than most biological or man-made fibers, but their material …
Changes In The Adhesive Properties Of Spider Aggregate Glue During The Evolution Of Cobwebs, Todd Blackledge, Ali Dhinojwala, Vasav Sahni
Changes In The Adhesive Properties Of Spider Aggregate Glue During The Evolution Of Cobwebs, Todd Blackledge, Ali Dhinojwala, Vasav Sahni
Todd A. Blackledge
We compare the prey capture glues produced by orb-weaving spiders (viscid glue) and their evolutionary descendents, the cobweb-weaving spiders (gumfoot glue). These glues are produced in homologous glands but exhibit contrasting structure, properties and response to changing humidity. Individual glue droplet stretching measurements indicate that the gumfoot glue behaves like a viscoelastic liquid in contrast to the viscid glue, which behaves like a viscoelastic solid. Moreover, the gumfoot glue is largely humidity-resistant – elasticity and adhesion are constant across variation in humidity and there is weak volume-dependence. Viscid glue, however, is highly humidity-sensitive. The glue expands an order of magnitude …
Spider Capture Silk: Performance Implications Of Variation In An Exceptional Biomaterial, Todd Blackledge, Brook Swanson, Cheryl Hayashi
Spider Capture Silk: Performance Implications Of Variation In An Exceptional Biomaterial, Todd Blackledge, Brook Swanson, Cheryl Hayashi
Todd A. Blackledge
Spiders and their silk are an excellent system for connecting the properties of biological materials to organismal ecology. Orb-weaving spiders spin sticky capture threads that are moderately strong but exceptionally extensible, resulting in fibers that can absorb remarkable amounts of energy. These tough fibers are thought to be adapted for arresting flying insects. Using tensile testing, we ask whether patterns can be discerned in the evolution of silk material properties and the ecological uses of spider capture fibers. Here, we present a large comparative data set that allows examination of capture silk properties across orb-weaving spider species. We find that …
Functionally Independent Components Of Prey Capture Are Architecturally Constrained In Spider Orb Webs, Todd Blackledge, Chad Eliason
Functionally Independent Components Of Prey Capture Are Architecturally Constrained In Spider Orb Webs, Todd Blackledge, Chad Eliason
Todd A. Blackledge
Evolutionary conflict in trait performance under different ecological contexts is common, but may also arise from functional coupling between traits operating within the same context. Orb webs first intercept and then retain insects long enough to be attacked by spiders. Improving either function increases prey capture and they are largely determined by different aspects of web architecture. We manipulated the mesh width of orbs to investigate its effect, along with web size, on prey capture by spiders and found that they functioned independently. Probability of prey capture increased with web size but was not affected by mesh width. Conversely, spiders …
Humidity Responsive Materials And Systems And Methods Using Humidity Responsive Materials, Todd Blackledge, Ali Dhinojwala, Ingi Agnarsson
Humidity Responsive Materials And Systems And Methods Using Humidity Responsive Materials, Todd Blackledge, Ali Dhinojwala, Ingi Agnarsson
Todd A. Blackledge
The invention relates to silk or other materials formed to have predetermined contraction/relaxation characteristics, wherein the contraction/relaxation characteristics are initiated by exposure thereof to predetermined humidity characteristics in the adjacent atmosphere. The materials may comprise a single silk fiber, a bundle of fibers of a predetermined size or diameter, a meshwork of fibers forming a predetermined configuration such as one or more sheets, bundles or other bodies. In this manner, the material can be scaled across a size range of any desired magnitude to produce predetermined force and/or displacement characteristics in association therewith.
How Super Is Supercontraction? Persistent Versus Cyclic Response To Humidity In Spider Dragline Silk, Todd Blackledge, Cecilia Boutry, Shing-Chung Wong, Avinash Baji
How Super Is Supercontraction? Persistent Versus Cyclic Response To Humidity In Spider Dragline Silk, Todd Blackledge, Cecilia Boutry, Shing-Chung Wong, Avinash Baji
Todd A. Blackledge
Spider dragline silk has enormous potential for the development of biomimetic fibers that combine strength and elasticity in low density polymers. These applications necessitate understanding how silk reacts to different environmental conditions. For instance, spider dragline silk `supercontracts' in high humidity. During supercontraction, unrestrained dragline silk contracts up to 50% of its original length and restrained fibers generate substantial stress. Here we characterize the response of dragline silk to changes in humidity before, during and after supercontraction. Our findings demonstrate that dragline silk exhibits two qualitatively different responses to humidity. First, silk undergoes a previously unknown cyclic relaxation–contraction response to …
Fine Dining Or Fortress? Functional Shifts In Spider Web Architecture By The Western Black Widow Latrodectus Hesperus, Todd Blackledge, Jacquelyn Zevenbergen, Nicole Schneider
Fine Dining Or Fortress? Functional Shifts In Spider Web Architecture By The Western Black Widow Latrodectus Hesperus, Todd Blackledge, Jacquelyn Zevenbergen, Nicole Schneider
Todd A. Blackledge
Spiders alter web architecture in response to many environmental factors. Yet, the functional implications of this behavioural plasticity are poorly understood, especially for spiders that spin long-lasting webs such as cobwebs. The western black widow spins a three-dimensional web that captures terrestrial prey and can persist for many days. However, the shape of the cobweb depends upon changes in the spider's body condition. Starved spiders invest more silk in sticky gumfooted threads, whereas sated spiders invest more silk in supporting threads. We tested the hypothesis that the increased investment in sticky gumfooted threads by starved spiders functions to improve the …
Gumfooted Lines In Black Widow Cobwebs And The Mechanical Properties Of Spider Capture Silk, Todd Blackledge, Adam Summers, Cheryl Hayashi
Gumfooted Lines In Black Widow Cobwebs And The Mechanical Properties Of Spider Capture Silk, Todd Blackledge, Adam Summers, Cheryl Hayashi
Todd A. Blackledge
Orb-weaving spiders produce webs using two types of silk that have radically different mechanical properties. The dragline silk used to construct the supporting frame and radii of the web is stiff and as strong as steel, while the capture spiral is much weaker but more than ten times as extensible. This remarkable divergence in mechanical properties has been attributed to the aqueous glue that coats the capture spiral, which is thought to decrease capture spiral stiffness and increase its extensibility. However, discerning the effect of the aqueous glue on fiber performance is complicated because dragline silk and the capture spiral …
Bioprospecting Finds The Toughest Biological Material: Extraordinary Silk From A Giant Riverine Orb Spider, Todd Blackledge, Matjaz Kuntner, Ingi Agnarsson
Bioprospecting Finds The Toughest Biological Material: Extraordinary Silk From A Giant Riverine Orb Spider, Todd Blackledge, Matjaz Kuntner, Ingi Agnarsson
Todd A. Blackledge
Background: Combining high strength and elasticity, spider silks are exceptionally tough, i.e., able to absorb massive kinetic energy before breaking. Spider silk is therefore a model polymer for development of high performance biomimetic fibers. There are over 41.000 described species of spiders, most spinning multiple types of silk. Thus we have available some 200.000+ unique silks that may cover an amazing breadth of material properties. To date, however, silks from only a few tens of species have been characterized, most chosen haphazardly as model organisms (Nephila) or simply from researchers' backyards. Are we limited to ‘blindly fishing’ in efforts to …
Evolution Of Supercontraction In Spider Silk: Structure-Function Relationship From Tarantulas To Orb-Weavers, Todd Blackledge, Cecilia Boutry
Evolution Of Supercontraction In Spider Silk: Structure-Function Relationship From Tarantulas To Orb-Weavers, Todd Blackledge, Cecilia Boutry
Todd A. Blackledge
Spider silk is a promising biomaterial with impressive performance. However, some spider silks also 'supercontract' when exposed to water, shrinking by up to ∼50% in length. Supercontraction may provide a critical mechanism to tailor silk properties, both for future synthetic silk production and by the spiders themselves. Several hypotheses are proposed for the mechanism and function of supercontraction, but they remain largely untested. In particular, supercontraction may result from a rearrangement of the GPGXX motif within the silk proteins, where G represents glycine, P proline and X is one of a small subset of amino acids. Supercontraction may prevent sagging …
Supercontraction Forces In Spider Dragline Silk Depend On Hydration Rate, Todd Blackledge, Cecilia Boutry, Ingi Agnarsson, Shing-Chung Wong
Supercontraction Forces In Spider Dragline Silk Depend On Hydration Rate, Todd Blackledge, Cecilia Boutry, Ingi Agnarsson, Shing-Chung Wong
Todd A. Blackledge
Spider dragline silk is a model biological polymer for biomimetic research due to its many desirable and unusual properties. 'Supercontraction' describes the dramatic shrinking of dragline silk fibers when wetted. In restrained silk fibers, supercontraction generates substantial stresses of 40-50 MPa above a critical humidity of approximately 70% relative humidity (RH). This stress may maintain tension in webs under the weight of rain or dew and could be used in industry for robotics, sensor technology, and other applications. Our own findings indicate that supercontraction can generate stress over a much broader range than previously reported, from 10 to 140 MPa. …
Condition-Dependent Spider Web Architecture In The Western Black Widow, Latrodectus Hesperus, Todd Blackledge, Jacquelyn Zevenbergen
Condition-Dependent Spider Web Architecture In The Western Black Widow, Latrodectus Hesperus, Todd Blackledge, Jacquelyn Zevenbergen
Todd A. Blackledge
Animals use behavioural plasticity to cope with conflicting selective pressures. We investigated how prey availability affects the spinning of cobwebs, whose architecture influences both prey capture and defence. Fed western black widows spun cobwebs containing more silk than did fasted spiders. However, fed spiders invested relatively less silk in the sheets and sticky gumfooted threads of webs and relatively more silk in supporting threads than did fasted spiders. The material properties of silk spun by fed and fasted spiders were relatively similar, but silk threads spun by fed spiders were twice as thick as those of fasted spiders, increasing web …
Spider Silk As A Novel High Performance Muscle Driven By Humidity, Todd Blackledge, Ali Dhinojwala, Ingi Agnarsson, Vasav Sahni
Spider Silk As A Novel High Performance Muscle Driven By Humidity, Todd Blackledge, Ali Dhinojwala, Ingi Agnarsson, Vasav Sahni
Todd A. Blackledge
The abrupt halt of a bumble bee's flight when it impacts the almost invisible threads of an orb web provides an elegant example of the amazing strength and toughness of spider silk. Spiders depend upon these properties for survival, yet the impressive performance of silk is not limited solely to tensile mechanics. Here, we show that silk also exhibits powerful cyclic contractions, allowing it to act as a high performance mimic of biological muscles. These contractions are actuated by changes in humidity alone and repeatedly generate work 50 times greater than the equivalent mass of human muscle. Although we demonstrate …
Spider Orb Webs Rely On Radial Threads To Absorb Prey Energy, Todd Blackledge, Andrew Sensenig, Kimberly Lorentz, Sean Kelly
Spider Orb Webs Rely On Radial Threads To Absorb Prey Energy, Todd Blackledge, Andrew Sensenig, Kimberly Lorentz, Sean Kelly
Todd A. Blackledge
The kinetic energy of flying insect prey is a formidable challenge for orb-weaving spiders. These spiders construct two-dimensional, round webs from a combination of stiff, strong radial silk and highly elastic, glue-coated capture spirals. Orb webs must first stop the flight of insect prey and then retain those insects long enough to be subdued by the spiders. Consequently, spider silks rank among the toughest known biomaterials. The large number of silk threads composing a web suggests that aerodynamic dissipation may also play an important role in stopping prey. Here, we quantify energy dissipation in orb webs spun by diverse species …
Shifting Continents, Not Behaviours: Independent Colonization Of Solitary And Subsocial Anelosimus Spider Lineages On Madagascar (Araneae, Theridiidae), Todd Blackledge, Matjaz Kuntner, Ingi Agnarsson, Jonathan Coddington
Shifting Continents, Not Behaviours: Independent Colonization Of Solitary And Subsocial Anelosimus Spider Lineages On Madagascar (Araneae, Theridiidae), Todd Blackledge, Matjaz Kuntner, Ingi Agnarsson, Jonathan Coddington
Todd A. Blackledge
Madagascar is a biodiversity hotspot, thought to be colonized mostly via Cenozoic dispersal from Africa, followed by endemic radiation of multiple lineages. Anelosimus spiders are diverse in Madagascar, and, like their congeners in the Americas, are most diverse in wet montane forests. Most Anelosimus species are social in that they cooperate in web building and prey capture either during a part of their life cycles (subsocial), including hitherto studied Malagasy species, or permanently (quasisocial). One Central American coastal species, Anelosimus pacificus, has secondarily switched to solitary living, and available evidence suggests that its closest relatives from S. America and Europe …
Behavioral And Biomaterial Coevolution In Spider Orb Webs, Todd Blackledge, Andrew Sensenig, Ingi Agnarsson
Behavioral And Biomaterial Coevolution In Spider Orb Webs, Todd Blackledge, Andrew Sensenig, Ingi Agnarsson
Todd A. Blackledge
Mechanical performance of biological structures, such as tendons, byssal threads, muscles, and spider webs, is determined by a complex interplay between material quality (intrinsic material properties, larger scale morphology) and proximate behaviour. Spider orb webs are a system in which fibrous biomaterials--silks--are arranged in a complex design resulting from stereotypical behavioural patterns, to produce effective energy absorbing traps for flying prey. Orb webs show an impressive range of designs, some effective at capturing tiny insects such as midges, others that can occasionally stop even small birds. Here, we test whether material quality and behaviour (web design) co-evolve to fine-tune web …
A Review On Spider Silk Adhesion, Todd Blackledge, Ali Dhinojwala, Vasav Sahni
A Review On Spider Silk Adhesion, Todd Blackledge, Ali Dhinojwala, Vasav Sahni
Todd A. Blackledge
Spiders employ clever behavioral strategies combined with almost invisible custom-made adhesive silk fibers to spin prey capture webs. The adhesives used in these webs evolved over millions of years into a class of natural materials with outstanding properties. Here, we review how spiders use different adhesives to capture prey. We show how spiders take advantage of the elasticity of both the capture silk and the glue to enhance adhesive forces, thereby providing important insights in designing new synthetic adhesives.
Estimation Of Capture Areas Of Spider Orb Webs In Relation To Asymmetry, Todd Blackledge, Rosemary Gillespie
Estimation Of Capture Areas Of Spider Orb Webs In Relation To Asymmetry, Todd Blackledge, Rosemary Gillespie
Todd A. Blackledge
We examined the utility of several popular formulae used to estimate the capture areas of orb webs across a large sample of Cyclosa Menge 1866 and Tetragnatha Latreille 1804 webs. All formulae evaluated contained at least some bias in estimation of the capture areas of webs. We identified two types of asymmetry in orb webs that affect capture area estimation differently. Web asymmetry measures the ratio of the horizontal and vertical diameters of orb webs while hub asymmetry measures the displacement of the hub from the geometric center of a web. An analysis of model webs that varied in web …
Environmentally Induced Post-Spin Property Changes In Spider Silks: Influences Of Web Type, Spidroin Composition And Ecology, Todd Blackledge, Sean Blamires, Chun-Lin Wu, I-Min Tso
Environmentally Induced Post-Spin Property Changes In Spider Silks: Influences Of Web Type, Spidroin Composition And Ecology, Todd Blackledge, Sean Blamires, Chun-Lin Wu, I-Min Tso
Todd A. Blackledge
Many spiders use silk to construct webs that must function for days at a time, whereas many other species renew their webs daily. The mechanical properties of spider silk can change after spinning under environmental stress, which could influence web function. We hypothesize that spiders spinning longer-lasting webs produce silks composed of proteins that are more resistant to environmental stresses. The major ampullate (MA) silks of orb web spiders are principally composed of a combination of two proteins (spidroins) called MaSp1 and MaSp2. We expected spider MA silks dominated by MaSp1 to have the greatest resistance to post-spin property change …
Silken Toolkits: Biomechanics Of Silk Fibers Spun By The Orb Web Spider Argiope Argentata (Fabricius 1775), Todd Blackledge, Cheryl Hayashi
Silken Toolkits: Biomechanics Of Silk Fibers Spun By The Orb Web Spider Argiope Argentata (Fabricius 1775), Todd Blackledge, Cheryl Hayashi
Todd A. Blackledge
Orb-weaving spiders spin five fibrous silks from differentiated glands that contain unique sets of proteins. Despite diverse ecological functions, the mechanical properties of most of these silks are not well characterized. Here, we quantify the mechanical performance of this toolkit of silks for the silver garden spider Argiope argentata. Four silks exhibit viscoelastic behaviour typical of polymers, but differ statistically from each other by up to 250% in performance, giving each silk a distinctive suite of material properties. Major ampullate silk is 50% stronger than other fibers, but also less extensible. Aciniform silk is almost twice as tough as other …
How Did The Spider Cross The River? Behavioral Adaptations For River-Bridging Webs In Caerostris Darwini (Araneae: Araneidae), Todd Blackledge, Matjaz Gregoric, Ingi Agnarsson, Matjaz Kuntner
How Did The Spider Cross The River? Behavioral Adaptations For River-Bridging Webs In Caerostris Darwini (Araneae: Araneidae), Todd Blackledge, Matjaz Gregoric, Ingi Agnarsson, Matjaz Kuntner
Todd A. Blackledge
Background: Interspecific coevolution is well described, but we know significantly less about how multiple traits coevolve within a species, particularly between behavioral traits and biomechanical properties of animals' “extended phenotypes”. In orb weaving spiders, coevolution of spider behavior with ecological and physical traits of their webs is expected. Darwin's bark spider (Caerostris darwini) bridges large water bodies, building the largest known orb webs utilizing the toughest known silk. Here, we examine C. darwini web building behaviors to establish how bridge lines are formed over water. We also test the prediction that this spider's unique web ecology and architecture coevolved with …
Quasistatic And Continuous Dynamic Characterization Of The Mechanical Properties Of Silk From The Cobweb Of The Black Widow Spider Latrodectus Hesperus, Todd Blackledge, John Swindeman, Cheryl Hayashi
Quasistatic And Continuous Dynamic Characterization Of The Mechanical Properties Of Silk From The Cobweb Of The Black Widow Spider Latrodectus Hesperus, Todd Blackledge, John Swindeman, Cheryl Hayashi
Todd A. Blackledge
Spider silks are among the strongest and toughest known materials, but investigation of these remarkable properties has been confined largely to orb-weaving spiders. We investigated the mechanical performance of silk from the cobweb-weaving spider Latrodectus hesperus. Both silk from the scaffolding region of the web and sticky gumfooted capture lines had material properties similar to the major ampullate silk that orb weavers use as the framework for their orb webs. Major ampullate fibers obtained from anaesthetized Latrodectus spiders were similar, but exhibited increased stiffness and reduced extensibility. Novel continuous dynamic analysis of the silks revealed that the loss tangent (tanδ) …
Prey Capture As A Determinate Of Tangle Web Architecture In Dictyna Volucripes, Todd Blackledge, John Wenzel
Prey Capture As A Determinate Of Tangle Web Architecture In Dictyna Volucripes, Todd Blackledge, John Wenzel
Todd A. Blackledge
Foraging behaviors result from dynamic trade-offs made by organisms, incorporating factors such as past foraging success, reproductive effort, and predation risk. But, decision-making by animals occurs with incomplete information about the environment. We examined the relationship of web architecture and foraging decisions in the tangle web-building spider Dictyna volucripes Keyserling, a common spider in North American fields. Tangle webs are constructed over many days, which increases the total material and energetic investment in webs compared to orb-webs that are rebuilt daily. This reduces the profitability of changing web sites for tangle web spiders, making decisions about allocation of resources to …
Adult Spiders Use Tougher Silk: Ontogenetic Changes In Web Architecture And Silk Biomechanics In The Orb-Weaver Spider, Todd Blackledge, Andrew Sensenig, Ingi Agnarsson
Adult Spiders Use Tougher Silk: Ontogenetic Changes In Web Architecture And Silk Biomechanics In The Orb-Weaver Spider, Todd Blackledge, Andrew Sensenig, Ingi Agnarsson
Todd A. Blackledge
Body size increases greatly during ontogeny in most animals and is often accompanied by dramatic shifts in foraging strategies and hence food resources. Orb-weaver spiders provide an interesting case, where a relatively homogeneous foraging strategy, aerial silk webs, is employed across all ontogenetic stages. Orb webs are spun soon after spiders emerge from the egg sac through growth of up to two orders of magnitude in body size. The sizes of prey targeted by the spiders are also likely to increase as spiders develop. Here, we examine how relative silk investment, web architecture, and the material properties of silk in …
Unraveling The Mechanical Properties Of Composite Silk Threads Spun By Cribellate Orb-Weaving Spiders, Todd Blackledge, Cheryl Hayashi
Unraveling The Mechanical Properties Of Composite Silk Threads Spun By Cribellate Orb-Weaving Spiders, Todd Blackledge, Cheryl Hayashi
Todd A. Blackledge
Orb-web weaving spiders depend upon the mechanical performance of capture threads to absorb the energy of flying prey. Most orb-weavers spin wet capture threads with core fibers of flagelliform silk. These threads are extremely compliant and extensible due to the folding of their constituent proteins into molecular nanosprings and hydration by a surrounding coating of aqueous glue. In contrast, other orb-weavers use cribellate capture threads, which are composite structures consisting of core fibers of pseudoflagelliform silk surrounded by a matrix of fine dry cribellar fibrils. Based on phylogenetic evidence, cribellate capture threads predate the use of viscid capture threads. To …
Dry Adhesion Based On Electrospun Polymer Nanofibers, Todd Blackledge, Sching Wong, Kai Wan, J Najem
Dry Adhesion Based On Electrospun Polymer Nanofibers, Todd Blackledge, Sching Wong, Kai Wan, J Najem
Todd A. Blackledge
Dry Adhesion exists between polymer nano/microfibers. An elaborate experiment was performed to directly measure the adhesion between electrospun poly(ε-caprolactone) (PCL) microfibers using a nano force tensile tester. Electrospun nano/microfibers with radius ranging from 0.2 to 1.1 μm were investigated. It was found that the adhesion force depended on the fiber radius following a linear relationship, which complied with the classical Johnson-Kendall-Roberts (JKR) contact mechanics model. The force increased with temperature and decreased with relative humidity between two fibers positioned in orthogonal directions. Our data suggested the van der Waals’ (vdW) interactions are primarily operative between the micro-/nano-fibers.
Plasticity In Major Ampullate Silk Production In Relation To Spider Phylogeny And Ecology, Todd Blackledge, Cecilia Boutry, Milan Rezak
Plasticity In Major Ampullate Silk Production In Relation To Spider Phylogeny And Ecology, Todd Blackledge, Cecilia Boutry, Milan Rezak
Todd A. Blackledge
Spider major ampullate silk is a high-performance biomaterial that has received much attention. However, most studies ignore plasticity in silk properties. A better understanding of silk plasticity could clarify the relative importance of chemical composition versus processing of silk dope for silk properties. It could also provide insight into how control of silk properties relates to spider ecology and silk uses. We compared silk plasticity (defined as variation in the properties of silk spun by a spider under different conditions) between three spider clades in relation to their anatomy and silk biochemistry. We found that silk plasticity exists in RTA …