The Experts below are selected from a list of 34191 Experts worldwide ranked by ideXlab platform
Xungai Wang - One of the best experts on this subject based on the ideXlab platform.
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Photoprotection by silk Cocoons
Biomacromolecules, 2013Co-Authors: Jasjeet Kaur, Jin Zhang, Rangam Rajkhowa, Takuya Tsuzuki, Keith R. Millington, Xungai WangAbstract:A silk Cocoon protects a silkworm during its pupal stage from various threats. We systematically investigated the role of fiber, sericin, and embedded crystals in the UV protection of a silk Cocoon. Diffuse reflectance and UV absorbance were measured and free radicals generated during exposure to UV radiation were quantified using photoinduced chemiluminescence (PICL). We identified the response to both UV-A and UV-B radiations by silk materials and found that sericin was primarily responsible for UV-A absorption. When sericin was removed, the photoinduced chemiluminescence intensity increased significantly, indicating higher UV-A-induced reactions of Cocoons in the absence of sericin. There is progressively higher sericin content toward the outer part of the Cocoon shell that allows an effective shield to pupae from UV radiation and resists photodegradation of silk fibers. The study will inspire development of advanced organic photoprotective materials and designing silk-based, free-radical-scavenging antioxidants.
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silkworm Cocoon as natural material and structure for thermal insulation
Materials & Design, 2013Co-Authors: Jin Zhang, Rangam Rajkhowa, X Y Liu, Xungai WangAbstract:Silkworm Cocoons are important biological materials that protect silkworms from environmental threat and predator attacks. Silkworm Cocoons are able to provide significant buffer against temperature changes outside of the Cocoon structure. We present our investigation of the thermal insulation properties of both domestic and wild silkworm Cocoons under warm conditions. Wild Cocoons show stronger thermal buffer function over the domestic Cocoon types. Both the Cocoon walls and the volume of inner Cocoon space contribute to the thermal damping behaviour of Cocoons. Wild silkworm Cocoons also have lower thermal diffusivity than domestic ones. Calcium oxalate crystals affects the thermal behaviour of wild silkworm Cocoons, by trapping still air inside the Cocoon structure and enhancing the thermal stability of the Cocoon assembly. The research findings are of relevance to the bio-inspired design of new thermo-regulating materials and structures.
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Mechanical properties and structure of silkworm Cocoons: A comparative study of Bombyx mori, Antheraea assamensis, Antheraea pernyi and Antheraea mylitta silkworm Cocoons
Materials science & engineering. C Materials for biological applications, 2013Co-Authors: Jin Zhang, Rangam Rajkhowa, X Y Liu, Jasjeet Kaur, Xungai WangAbstract:Abstract As a protective shell against environmental damage and attack by natural predators, the silkworm Cocoon has outstanding mechanical properties. In particular, this multilayer non-woven composite structure can be exceptionally tough to enhance the chance of survival for silkworms while supporting their metabolic activity. Peel, out-of-plane compression and nano-indentation tests and micro-structure analysis were performed on four types of silkworm Cocoon walls (domesticated Bombyx mori, semi-domesticated Antheraea assamensis and wild Antheraea pernyi and Antheraea mylitta silkworm Cocoons) to understand the structure and mechanical property relationships. The wild silkworm Cocoons were shown to be uniquely tough composite structures. The maximum work-of-fracture for the wild Cocoons (A. pernyi and A. mylitta) was approximately 1000 J/m2, which was almost 10 times the value for the domesticated Cocoon (Bombyx mori) and 3 ~ 4 times the value for the semi-domesticated Cocoon (A. assamensis). Calcium oxalate crystals were found to deposit on the outer surfaces of the semi-domesticated and wild Cocoons. They did not show influence in enhancing the interlaminar adhesion between Cocoon layers but exhibited much higher hardness than the Cocoon pelades.
Fritz Vollrath - One of the best experts on this subject based on the ideXlab platform.
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comparing the microstructure and mechanical properties of bombyx mori and antheraea pernyi Cocoon composites
Acta Biomaterialia, 2017Co-Authors: Juan Guan, Wenshu Zhu, Binghe Liu, Kang Yang, Fritz VollrathAbstract:Abstract Silkworm Cocoon material is a natural composite consisting of silk fibres and sericin glues. Both domestic and wild silkworms produce Cocoons but with different functionality – one selected by man for textile manufacture whereas the other selected by Nature to provide damage-tolerant housing. To understand the structure-–property relationship of Cocoons, we evaluated and compared the microstructure and mechanical properties of two representative Cocoon walls. It appears that a “brittle and weak” composite is produced by domestic Bombyx mori (B. mori) while a “tough and strong” composite is made by wild Antheraea pernyi (A. pernyi). The superior mechanical performance of A. pernyi Cocoons can be attributed to both the material properties and the fibre network microstructures. Failure mechanisms and different failure modes for Cocoon fibre composites were also proposed. A finite element model revealed qualitatively the effect of fibre properties and inter-fibre bonding strength on the mechanical properties of the fibre network. It emerged that both good mechanical properties of fibres and robust inter-fibre bonding were required for tough and strong fibre composites. The new insights could inspire new designs of synthetic fibre composites with enhanced mechanical properties. Statement of Significance Natural Cocoons are an important group of natural fibre composites with versatile functionalities. Previous studies have focused on the diversity of Cocoon species and different morphological and mechanical features. It was suggested that the Cocoon network structure determined the final mechanical properties of the Cocoon composite. Nevertheless, the full structure–propertyfunction relationships for the Cocoon composite are not understood. By studying two distinct Cocoon species with specific functionalities, we prove that the mechanical properties of two Cocoons are determined by both network properties and fibre properties. A robust fibre network is the prerequisite, within which the good mechanical properties of the fibres can play a part. The finding will inspire new designs of synthetic composites with desirable and predictable mechanical properties.
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the silkmoth Cocoon as humidity trap and waterproof barrier
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2013Co-Authors: Nicholas P C Horrocks, Fritz Vollrath, Cedric DickoAbstract:To better understand how silkmoth Cocoons maintain the correct internal moisture levels for successful pupation, we examined Cocoons from the long-domesticated mulberry silkmoth Bombyx mori as well as from two wild silkmoth species, Antheraea pernyi and Philosamia cynthia ricini. We determined fluid-independent values for the porosity, tortuosity and permeability of the inner and outer surfaces of Cocoons. Permeabilities were low and, with the exception of A. pernyi Cocoons, inner surfaces were less permeable than outer surfaces. B. mori Cocoons exhibited the highest permeability overall, but only at the outer surface, while A. pernyi Cocoons appeared to show different patterns from the other species tested. We discuss our findings in light of the ecophysiology of the various species and propose a 'tortuous path' model to help explain our results. The model describes how the structure of the inner and outer layers of the Cocoon allows it to function as both a humidity trap and a waterproof barrier, providing optimum conditions for the successful development of the pupa.
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Morphology and structure of silkworm Cocoons
Materials Science and Engineering: C, 2012Co-Authors: Fujia Chen, David Porter, Fritz VollrathAbstract:Abstract Silkworm Cocoons are natural polymer fibre composites made from silk fibres and sericin binder. While silk is an interesting natural material per se , an understanding of the role of silk within one of its main functional applications in silkworm Cocoons will provide inspiration and tools for the design of new artificial silk composites. Here, we describe in some detail the structure and morphology of the Cocoons of 27 different species of silkworm. While Cocoon morphology can be described very broadly as a nonwoven fibre composite, we demonstrate a diversity of structural features such as: the number and connectivity of layers through the Cocoon wall thickness, the amount and distribution of sericin binder, the diameter and packing density of the silk fibres, the degree of orientation of the nonwoven structure, the distribution of larger holes within that structure, and the presence of calcium oxalate crystals.
Jin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Photoprotection by silk Cocoons
Biomacromolecules, 2013Co-Authors: Jasjeet Kaur, Jin Zhang, Rangam Rajkhowa, Takuya Tsuzuki, Keith R. Millington, Xungai WangAbstract:A silk Cocoon protects a silkworm during its pupal stage from various threats. We systematically investigated the role of fiber, sericin, and embedded crystals in the UV protection of a silk Cocoon. Diffuse reflectance and UV absorbance were measured and free radicals generated during exposure to UV radiation were quantified using photoinduced chemiluminescence (PICL). We identified the response to both UV-A and UV-B radiations by silk materials and found that sericin was primarily responsible for UV-A absorption. When sericin was removed, the photoinduced chemiluminescence intensity increased significantly, indicating higher UV-A-induced reactions of Cocoons in the absence of sericin. There is progressively higher sericin content toward the outer part of the Cocoon shell that allows an effective shield to pupae from UV radiation and resists photodegradation of silk fibers. The study will inspire development of advanced organic photoprotective materials and designing silk-based, free-radical-scavenging antioxidants.
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silkworm Cocoon as natural material and structure for thermal insulation
Materials & Design, 2013Co-Authors: Jin Zhang, Rangam Rajkhowa, X Y Liu, Xungai WangAbstract:Silkworm Cocoons are important biological materials that protect silkworms from environmental threat and predator attacks. Silkworm Cocoons are able to provide significant buffer against temperature changes outside of the Cocoon structure. We present our investigation of the thermal insulation properties of both domestic and wild silkworm Cocoons under warm conditions. Wild Cocoons show stronger thermal buffer function over the domestic Cocoon types. Both the Cocoon walls and the volume of inner Cocoon space contribute to the thermal damping behaviour of Cocoons. Wild silkworm Cocoons also have lower thermal diffusivity than domestic ones. Calcium oxalate crystals affects the thermal behaviour of wild silkworm Cocoons, by trapping still air inside the Cocoon structure and enhancing the thermal stability of the Cocoon assembly. The research findings are of relevance to the bio-inspired design of new thermo-regulating materials and structures.
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Mechanical properties and structure of silkworm Cocoons: A comparative study of Bombyx mori, Antheraea assamensis, Antheraea pernyi and Antheraea mylitta silkworm Cocoons
Materials science & engineering. C Materials for biological applications, 2013Co-Authors: Jin Zhang, Rangam Rajkhowa, X Y Liu, Jasjeet Kaur, Xungai WangAbstract:Abstract As a protective shell against environmental damage and attack by natural predators, the silkworm Cocoon has outstanding mechanical properties. In particular, this multilayer non-woven composite structure can be exceptionally tough to enhance the chance of survival for silkworms while supporting their metabolic activity. Peel, out-of-plane compression and nano-indentation tests and micro-structure analysis were performed on four types of silkworm Cocoon walls (domesticated Bombyx mori, semi-domesticated Antheraea assamensis and wild Antheraea pernyi and Antheraea mylitta silkworm Cocoons) to understand the structure and mechanical property relationships. The wild silkworm Cocoons were shown to be uniquely tough composite structures. The maximum work-of-fracture for the wild Cocoons (A. pernyi and A. mylitta) was approximately 1000 J/m2, which was almost 10 times the value for the domesticated Cocoon (Bombyx mori) and 3 ~ 4 times the value for the semi-domesticated Cocoon (A. assamensis). Calcium oxalate crystals were found to deposit on the outer surfaces of the semi-domesticated and wild Cocoons. They did not show influence in enhancing the interlaminar adhesion between Cocoon layers but exhibited much higher hardness than the Cocoon pelades.
Rangam Rajkhowa - One of the best experts on this subject based on the ideXlab platform.
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Photoprotection by silk Cocoons
Biomacromolecules, 2013Co-Authors: Jasjeet Kaur, Jin Zhang, Rangam Rajkhowa, Takuya Tsuzuki, Keith R. Millington, Xungai WangAbstract:A silk Cocoon protects a silkworm during its pupal stage from various threats. We systematically investigated the role of fiber, sericin, and embedded crystals in the UV protection of a silk Cocoon. Diffuse reflectance and UV absorbance were measured and free radicals generated during exposure to UV radiation were quantified using photoinduced chemiluminescence (PICL). We identified the response to both UV-A and UV-B radiations by silk materials and found that sericin was primarily responsible for UV-A absorption. When sericin was removed, the photoinduced chemiluminescence intensity increased significantly, indicating higher UV-A-induced reactions of Cocoons in the absence of sericin. There is progressively higher sericin content toward the outer part of the Cocoon shell that allows an effective shield to pupae from UV radiation and resists photodegradation of silk fibers. The study will inspire development of advanced organic photoprotective materials and designing silk-based, free-radical-scavenging antioxidants.
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silkworm Cocoon as natural material and structure for thermal insulation
Materials & Design, 2013Co-Authors: Jin Zhang, Rangam Rajkhowa, X Y Liu, Xungai WangAbstract:Silkworm Cocoons are important biological materials that protect silkworms from environmental threat and predator attacks. Silkworm Cocoons are able to provide significant buffer against temperature changes outside of the Cocoon structure. We present our investigation of the thermal insulation properties of both domestic and wild silkworm Cocoons under warm conditions. Wild Cocoons show stronger thermal buffer function over the domestic Cocoon types. Both the Cocoon walls and the volume of inner Cocoon space contribute to the thermal damping behaviour of Cocoons. Wild silkworm Cocoons also have lower thermal diffusivity than domestic ones. Calcium oxalate crystals affects the thermal behaviour of wild silkworm Cocoons, by trapping still air inside the Cocoon structure and enhancing the thermal stability of the Cocoon assembly. The research findings are of relevance to the bio-inspired design of new thermo-regulating materials and structures.
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Mechanical properties and structure of silkworm Cocoons: A comparative study of Bombyx mori, Antheraea assamensis, Antheraea pernyi and Antheraea mylitta silkworm Cocoons
Materials science & engineering. C Materials for biological applications, 2013Co-Authors: Jin Zhang, Rangam Rajkhowa, X Y Liu, Jasjeet Kaur, Xungai WangAbstract:Abstract As a protective shell against environmental damage and attack by natural predators, the silkworm Cocoon has outstanding mechanical properties. In particular, this multilayer non-woven composite structure can be exceptionally tough to enhance the chance of survival for silkworms while supporting their metabolic activity. Peel, out-of-plane compression and nano-indentation tests and micro-structure analysis were performed on four types of silkworm Cocoon walls (domesticated Bombyx mori, semi-domesticated Antheraea assamensis and wild Antheraea pernyi and Antheraea mylitta silkworm Cocoons) to understand the structure and mechanical property relationships. The wild silkworm Cocoons were shown to be uniquely tough composite structures. The maximum work-of-fracture for the wild Cocoons (A. pernyi and A. mylitta) was approximately 1000 J/m2, which was almost 10 times the value for the domesticated Cocoon (Bombyx mori) and 3 ~ 4 times the value for the semi-domesticated Cocoon (A. assamensis). Calcium oxalate crystals were found to deposit on the outer surfaces of the semi-domesticated and wild Cocoons. They did not show influence in enhancing the interlaminar adhesion between Cocoon layers but exhibited much higher hardness than the Cocoon pelades.
X Y Liu - One of the best experts on this subject based on the ideXlab platform.
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silkworm Cocoon as natural material and structure for thermal insulation
Materials & Design, 2013Co-Authors: Jin Zhang, Rangam Rajkhowa, X Y Liu, Xungai WangAbstract:Silkworm Cocoons are important biological materials that protect silkworms from environmental threat and predator attacks. Silkworm Cocoons are able to provide significant buffer against temperature changes outside of the Cocoon structure. We present our investigation of the thermal insulation properties of both domestic and wild silkworm Cocoons under warm conditions. Wild Cocoons show stronger thermal buffer function over the domestic Cocoon types. Both the Cocoon walls and the volume of inner Cocoon space contribute to the thermal damping behaviour of Cocoons. Wild silkworm Cocoons also have lower thermal diffusivity than domestic ones. Calcium oxalate crystals affects the thermal behaviour of wild silkworm Cocoons, by trapping still air inside the Cocoon structure and enhancing the thermal stability of the Cocoon assembly. The research findings are of relevance to the bio-inspired design of new thermo-regulating materials and structures.
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Mechanical properties and structure of silkworm Cocoons: A comparative study of Bombyx mori, Antheraea assamensis, Antheraea pernyi and Antheraea mylitta silkworm Cocoons
Materials science & engineering. C Materials for biological applications, 2013Co-Authors: Jin Zhang, Rangam Rajkhowa, X Y Liu, Jasjeet Kaur, Xungai WangAbstract:Abstract As a protective shell against environmental damage and attack by natural predators, the silkworm Cocoon has outstanding mechanical properties. In particular, this multilayer non-woven composite structure can be exceptionally tough to enhance the chance of survival for silkworms while supporting their metabolic activity. Peel, out-of-plane compression and nano-indentation tests and micro-structure analysis were performed on four types of silkworm Cocoon walls (domesticated Bombyx mori, semi-domesticated Antheraea assamensis and wild Antheraea pernyi and Antheraea mylitta silkworm Cocoons) to understand the structure and mechanical property relationships. The wild silkworm Cocoons were shown to be uniquely tough composite structures. The maximum work-of-fracture for the wild Cocoons (A. pernyi and A. mylitta) was approximately 1000 J/m2, which was almost 10 times the value for the domesticated Cocoon (Bombyx mori) and 3 ~ 4 times the value for the semi-domesticated Cocoon (A. assamensis). Calcium oxalate crystals were found to deposit on the outer surfaces of the semi-domesticated and wild Cocoons. They did not show influence in enhancing the interlaminar adhesion between Cocoon layers but exhibited much higher hardness than the Cocoon pelades.