Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"nacre"”.
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Multiscale mechanical studies of nacre from gastropod mollusk Trochus Nilocitus
(cont.) revealed jagged and branched crack fronts at plate interface, tortuous crack paths, non-uniform angles of polygons (suggesting possible intrinsic deformability and displacement/sliding). The technique of nanoindentation was carried out on individual aragonite tablets using a diamond-coated …
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Hierarchical Assembly Strategy and Multiscale Structural Origin of Exceptional Mechanical Performance In Nacre
<p>Nacre (mother of pearl) is a self-assembled hierarchical nanocomposite in possession of exquisite multiscale architecture and exceptional mechanical properties. Previous work has shown that the highly-ordered brick-mortar-like structure in nacre is assembled via epitaxial growth and the …
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Mapping of elastic modulus and hardness in Trochus niloticus seashell nacre by nanoindentation
… was carried out in the freshly-cleaved nacre found in the shell of the gastropod mollusk Trochus niloticus. Nacre is a hierarchical biocomposite composed of mineral tablets of 95 weight % calcium carbonate (CaCO3) in the aragonite mineral form and a biomacromolecular organic matrix. …
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Mechanical behavior of ultrastructural biocomposites
… strength and toughness. One such example is nacre, which is found in the shells of many mollusks, and consists of an inorganic phase of aragonite tablets 5-8jim in planar dimension and 0.5-1gm in thickness direction and an organic phase of biomacromolecules. High resolution microscopy imaging …
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Multiscale structural and mechanical design of mineralized biocomposites
Gastropod mollusk nacre tablets and Polypterus senegalus armored scales share common features such as a very complex and changing structure spanning several length scales. The smallest building blocks are single crystals, have dimensions of a from tens of nanometers to several microns and are …
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Actiononaias Ligamentina as a Biomonitor in the Green River: An Unique Approach for Analysis of Environmental Impacts
… 45 miles downstream. Analyzing the shell nacre of these mussels, and the soft tissue of recently collected specimens, produced an abundance of information including high tissue concentrations of organochloride pesticides, significant concentrations of several metals including Cadmium, …
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Graphene Nano-Composites For Hypervelocity Impact Applications
… with mortar-brick nano-structure inspired from nacre. Nacre-like composites were successfully manufactured, based on three host polymers, with a wide range of graphene concentrations. The manufactured exfoliated graphene nano-platelet, embedded in a host polymer, provided good potential for …
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Self-Assembly of Surface-modified Clays for Functional Biomimetic Materials
… to that observed in natural mother of pearl (nacre). I first introduce a simple strategy that successfully suppresses Laponite’s ageing phenomenon and enables the system’s isotropic-to-LC phase transition. By grafting Laponite particle surfaces with comb-like polymers, poly (L-lysine)-g-poly …
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Time-Space-Resolved Raman Analysis of Structure-Property Relationships in Heterogeneous Structural Materials
… to study the structureproperty relationships in nacre material. The crystallographic texture of the nacre is correlated with its energy absorption capacity to study the toughening mechanism. A corporative movement of co-oriented stacks of aragonite platelets is observed, which defined the …
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Fracture of the interlayer junction of the shell from a deep-sea hydrothermal vent gastropod
… bands analogous to dilatation bands observed in nacre under certain stress-states. Thus, the mechanisms behind grain separation, the micro-architecture of the anisotropic aragonite grains and other constituents, and the gradual compositional change observed in the tougher gradient layer all acted …
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Broadcasting the Profession: The American Library Association and the National Children's Radio Hour
… National Advisory Council on Radio in Education (NACRE) and the National Broadcasting Company (NBC), to the offer of a script created by Newbery Award winner Hendrik Van Loon, and the program's eventual demise due to political and economic pressures. It reveals parallels between librarians of the …
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Light localization in biological media
… equilibrium, clearly differentiates silk and nacre from diffusive structures sharing the microscopic morphological similarity. This explains how the dimension, the size, and the distribution of disordered biological nanostructures result in enhanced light-matter interactions, in spite of low …
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Experiments augmented computational analysis of structural materials: A focus on metallic and biological systems
… extends to bio-inspired materials, investigating Nacre like structures for topology optimization aimed at enhancing mechanical properties and wave filtering capabilities. The dynamic behavior of these metamaterials is examined, revealing how hierarchical design influences their multifunctional …
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Fracture mechanics in the semigrand canonical ensemble
… polymers or organics, such as gas shale, nacre, stress-induced transformational toughening mechanisms in ceramics, and toughening of sparse elastic networks in hydrogels, to name a few.
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Bioinspired algorithmic-driven design of additively manufactured composites
… learning. Specifically, this thesis takes nacre and conch as model natural materials and deconstructs them in the bioinspired algorithmic-driven design (BADD) framework to build up rationally designed engineering composites. In this work, we show that structural feature placement introduces …
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Debonding in bi-layer material systems under moisture effect : a multiscale approach
… in many natural and biological materials such as nacre or bone. One of the most human-related applications of bi-layer material systems is the artificial tooth involving the bonding between the natural tooth and the metal cap glued with a polymer based material. The structural integrity of a …
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Biologically inspired materials for electro-responsive coatings and the photo-oxidation of water
… of complex hierarchical structures such as the nacre of abalone. Tools such as phage and yeast display libraries have enabled the combinatorial screening of peptides against a multitude of materials to which natural systems typically have no exposure. These techniques have yielded peptides that …
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Improvement in mechanical properties through structural hierarchies in bio-inspired materials
Structural biological materials such as bone, nacre, insect cuticle, and sea sponge exoskeleton showcase the use of inferior building blocks like proteins and minerals to create structures that afford load-bearing and armor capabilities. Many of these are composite structures that possess the best …
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Multiscale Modeling of Fatigue and Fracture in Polycrystalline Metals, 3D Printed Metals, and Bio-inspired Materials
… properties. Biological composites like bone, nacre, and teeth attracted much attention among the researchers. These materials are constructed from simple building blocks and show an uncommon combination of high strength and toughness. By inspiring from simple building blocks in bio-inspired …
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