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1
Walish, Joseph John. "Bio-inspired optical components." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45950.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references.
Guiding electro-magnetic radiation is fundamental to optics. Lenses, mirrors, and photonic crystals all accomplish this task by different routes. Understanding the interaction of light with materials is fundamental to improving and extending optical science and engineering as well as producing novel optical elements. Improvement in this understanding should not only include work to understand the interaction with traditional engineering materials but also should target the understanding of the interaction of electromagnetic radiation with biological structures as millions of years of evolution have sorted out numerous ways to modulate light (e.g. the fish eye or the skin of the octopus). The goal of this thesis work is to fabricate novel optical elements by taking cues from nature and extending the state of the art in light guiding behavior. Here, optical elements are defined as structured materials that guide or direct electromagnetic radiation in a predetermined manner. The work presented in this thesis encompasses biologically inspired tunable multilayer reflectors made from block copolymers and improvements to liquid filled lenses which mimic the human eye.In this thesis a poly(styrene)-poly(2-vinylpyridine) block copolymer was used to create a bio-mimetic, one-dimensional, multilayer reflector. The wavelengths of light reflected from this multilayer reflector or Bragg stack were tuned by the application of stimuli which included temperature, change in the solvent environment, pH, salt concentration in the solvent, and electrochemistry.
(cont.) A linear-shear rheometer was also built to investigate the mechanochromic color change brought about through the shearing of a one-dimensional, high molecular-weight, block-copolymer, photonic gel. Biologically inspired lenses were also studied through the construction of a finite element model which simulated the behavior of a liquid-filled lens. Several tunable parameters, such as the modulus, internal residual stress, and thickness of the membrane were studied for their influence on the shape of the lens membrane. Based on these findings, suggestions for the reduction of spherical aberration in a liquid filled lens were made. A gradient in the elastic modulus of the membrane was also investigated for use in the reduction of spherical aberration.
by Joseph John Walish.
Ph.D.
2
Santi, Sofia. "Bio-inspired materials for spinal cord regeneration." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/319486.
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This work proposes minimally invasive solutions for spinal cord regeneration after trauma. In particular, injectable biomaterials can be precisely positioned in the lesion site, and eventually repetitively injected until the complete regeneration of the tissue. For this application, a silk fibroin functionalized with collagen type IV and laminin-derived peptides, called bio-inspired multifunctionalized silk fibroin (BMS), possessing piezoelectric properties, has been synthesized.
Another approach that avoids damages to the spinal cord is proposed in the thesis as a multilayer hydrogel with piezoelectric properties that acts as a bridge between the healthy parts surrounding the injury. The multilayer hydrogel consists of i) a thin-layer of gelatin and fish collagen functionalized with VEGF for blood vessels formation, which helps the survival of the cells integrating with the pia mater of the spinal cord; ii) a BMS layer, which helps the adhesion, migration of neural stem cells and induces the sprouting of the axons thanks to the presence of Netrin (a chemoattractive protein); and iii) an adhesive layer of polydopamine (PDA) to fix the patch on the injured site. The adhesive patch exhibits a potential larger than an injectable hydrogel that could guarantee a long-term cell survival and help the axons to move towards a direction. The adhesive patch will be located on the surface of the spinal cord and the chemoattractive protein will induce the sprouting of the ascendant or descendant axons in the spinal cord to reach the axons present in the patch, restoring a signal connection.
Even if not final, the results indicate that the above strategy could be explored further for the regeneration of the spinal cord.
3
Monemian, Seyedali. "Tuning Mechanics of Bio-Inspired Polymeric Materials through Supramolecular Chemistry." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1467882025.
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Grindy, Scott C. (Scott Charles). "Complex mechanical design of bio-inspired model transient network hydrogels." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111249.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 179-191).
The mechanical properties of viscoelastic soft materials are strongly time-dependent, such that we must describe their mechanical properties with material functions. This is an inherently difficult problem for materials scientists: typically,we define structure-property relationships in terms of scalar material properties, such that modifying a material's structure affects a target material property. However, if the property of interest is function-valued, modifying the material's structure may affect different parts of the material function in undesirable ways. The increased dimensionality of the target material property therefore renders the overall materials design problem for soft materials significantly more difficult. Recently, transient interactions have been shown to vastly improve the mechanical properties of soft materials by providing increased energy dissipation through the dissociation of the reversible bonds. However, there is a wide variety of transient interactions to choose from, varying widely in binding strength, kinetics, specificity, and stoichiometry of the groups that form the association. More research needs to be done to identify what physical laws apply universally across the types of transient associations, and what differentiates the abilities of different types of interactions to control material mechanics. In this thesis,we show how transient metal-coordinate bonds inspired by the chemistry of the mussel byssal threads can be used to engineer viscoelastic material functions in an intuitive and facile manner. We show that intelligent understanding of the thermodynamics and kinetics of metal-coordinate complexes allows quasi-independent control over different regimes of the viscoelastic material function. We draw from classical polymer physics and metal-coordinate chemistry to show that our 4-arm polyethylene glycol-based hydrogels crosslinked with transient histidine:metal bonds represent a uniquely ideal system for probing fundamental questions in how the properties of transient interactions affect viscoelastic material functions. In the final part of this thesis, we extend our control over the viscoelastic material functions of hydrogels by exploiting the redox-sensitivity of histidine:metal crosslinks. In this way, we show how histidine:metal interactions are perhaps more versatile than other types of transient interactions, promising a facile way to examine structure-property relationships in transient networks.
by Scott C. Grindy.
Ph. D.
5
Ransil, Alan Patrick Adams. "A bio-inspired approach to increase device-level energy density." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120391.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 120-153).
Battery research has historically focused on improving the properties of the active materials that directly store energy. This research has resulted in active materials with higher specific capacity, increased the voltage of batteries in order to store more energy per electron, and lead to the development of electrolytes and binders compatible with high-performance active materials. However, Lithium-Ion Batteries (LIB) are nearing the limits of energy density achievable using a traditional battery design. Structural batteries are a fundamentally distinct route to optimize device performance, aiming to replace structural materials such as metals, plastics, and composites with multifunctional energy-storing materials. By increasing the device mass fraction that is devoted to energy storage, this strategy could more than double the battery life of electronic devices without requiring improved active materials. In this thesis, I show that rigid, load-bearing electrodes suitable for structural batteries can be fabricated using a novel silicate binder. This binder .can be used to distribute load both within layers and throughout the battery by adhering adjacent battery layers. This innovation turns the entire battery stack into a novel monolithic engineering ceramic referred to as a Structural Ceramic Battery (SCB). Unlike previously published binders, this material does not soften with the introduction of electrolyte, it promotes charge transport within the electrode, and it is compatible with a range of active materials employed in batteries today. This thesis furthermore outlines versatile manufacturing methods making it possible to produce SCBs with a wide variety of shapes and form factors amenable to large-scale production. It is envisioned that this SCB architecture will be used to improve the energy density of both ground-based and flying electric vehicles, and that as improved active material chemistries are discovered they will be dropped in to this architecture in order to promote future increases in vehicle-level energy density.
by Alan Ransil.
Ph. D.
6
Lin, Erica (Erica S. C. ). "Bio-inspired design of geometrically-structured suture interfaces and composites." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98580.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 90-93).
Nature is filled with incredible examples of multi-functional materials that have evolved to possess tailored mechanical behavior. This thesis explores the structure-function-property relationship and design principles of geometrically-structured suture interfaces and composites. Suture interfaces are mechanical structures found in rigid natural materials (e.g. human skulls, turtle shells, seashells) that bear loads and provide flexibility for respiration and growth. The geometry of suture interfaces has been shown to vary within species, across species, through development, and over time as organisms evolve. Using mechanical testing of 3D-printed, bio-inspired prototypes, finite element simulations, and analytical modeling, this thesis offers a systematic, comprehensive understanding of the relationship between suture interface geometry and mechanical behavior and provides insight into the suture interface geometries that exist in nature. Triangular, general trapezoidal, and hierarchical suture interfaces and composites are designed, fabricated, and tested. The stiffness, strength, toughness, and failure mechanisms of suture interfaces are shown to be directly influenced by suture geometry. Therefore, mechanical behavior of suture interfaces can be tailored or amplified through small changes in geometry. In addition, the bending behavior of suture composites can also be tailored through changes in suture interface geometry. With a detailed understanding of the deformation mechanisms of suture composites, optimal, multi-scale, hierarchical geometries can be designed.
by Erica Lin.
Ph. D.
7
Sen, Dipanjan 1980. "Improvement in mechanical properties through structural hierarchies in bio-inspired materials." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62745.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 155-169).
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 of the properties of their base constituents. This is in contrast to many engineering materials, such as metals, alloys, ceramics and their composites which show improvement in one mechanical property (e.g. stiffness) at the cost of another disparate one (e.g. toughness). These excellent design examples from biology raise questions about whether similar design., and improvement in disparate properties, can be achieved using common engineering materials. The identification of broad design principles that can be transferred from biological materials to structural design, and the analysis of the utility of these principles have been missing in literature. In this thesis, we have firstly identified certain universal features of design of biological structures for mimicking with engineering materials: a) presence of geometric design at the nanoscale, b) the use of mechanically inferior building blocks, and c) the use of structural hierarchies from the nanoscale to the macroscale. We firstly design. in silico, metal-matrix nanocomposites, mimicking the geometric design found at the nanoscale in bone. We show this leads to improvements in flow strength of the material. A key finding is that limiting values of certain of these parameters shuts down dislocation-mediated plasticity leading to peak in flow strength of the structure. Metals are however, costly constituents, and we next confront the issue of whether it is possible to use a single mechanically inferior and commonly available constituent, such as silica, to create superior bioinspired structures. We turn to diatom exoskeletons, protective armor structures for algae made almost entirely of silica, and create nanoporous silica structures inspired from their geometry. We show large improvements in ductility of silica through this design, facilitated by a key size-dependent brittle-to-ductile deformation transition in these structures. Nanostructuring, while improving ductility, affects the stiffness of these structures, softening them by up to 90% of bulk silica. Hierarchical assembly of silica structures is then used to regain the stiffness lost due to nanostructuring while not losing their improvement in toughness. Finally, improvement in toughness with several levels of hierarchy is studied, to showcase a defect-tolerant behavior that arises with the addition of hierarchies, i.e., tolerance of the fracture strength to a wide range of sizes of cracks present in the structure. The importance of R-curve behavior, i.e., toughness change with the advance of a crack in the structure. to the defect-tolerance length scale is also established. These findings showcase the validity of using design principles obtained from biological materials for improvement in mechanical properties of engineering materials.
by Dipanjan Sen.
Ph.D.
8
Balogh, Margareta Cristina. "New luminescent materials, bio-inspired and recyclabe, based on lanthanide complexes." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN039.
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L’objectif de ce projet a été de concevoir des matériaux émissifs recyclables à base de lanthanide, en vue de remplacer les oxydes contenus dans les lampes fluoro-compactes (CFLs). Les lanthanides, en particulier l’Eu¹¹¹ et le Tb¹¹¹ ont été les principaux « ingrédients » dans les phosphores à cause de leurs émissions fines dans le rouge et le vert. Les complexes tris-dipicolinate de lanthanides, solubles dans l’eau sont connus pour leurs excellentes propriétés de luminescence, ce qui en fait de bons candidats pour des applications dans le domaine de l’éclairage.Cette thèse décrit l’étude des complexes de tris-dipicolinate d’Eu¹¹¹ et de Tb¹¹¹ sous forme cristalline avec différents contre-cations, ainsi que des systèmes plus complexes comme des co-cristaux ou des de cristaux cœur/coquille. Ces complexes ont également été utilisés comme dopant dans des silices mésostructurées en utilisant une méthode dites de « incipient wet impregnation » (IWI). Les propriétés photophysiques de ces matériaux ont été étudiées en détail et une forte exaltation des propriétés d’émission a été mise en évidence dans les silices. En particulier, l’influence des oscillateurs O-X a été montrée et la détermination du rendement quantique intrinsèque nous a procuré une meilleure compréhension de cette exaltation.La recyclabilité des complexes de lanthanide dans la silice a pu être réalisée avec des bons rendements. Des matériaux, émettant de la lumière blanche ont pu être obtenus en mélangeant des émetteurs rouge, vert et bleu. Le naphtalimide a été choisi comme émetteur bleu. Ainsi, le mélange des complexes d’Eu¹¹¹ et de Tb¹¹¹ et de naphtalimide au sein d’une silice mésoporeuse a conduit à la première génération de matériaux émettant de la lumière blanche et pouvant être facilement recyclésThe objective of this project was to explore recyclable lanthanide based materials suitable for replacing the oxides from compact fluorescent lamps (CFLs). Lanthanides, particularly Eu¹¹¹ and Tb¹¹¹ have been the main “ingredients” in phosphors due to their colour purity and sharp emission in the red and green range of the visible spectrum. Lanthanide tris-dipicolinates are water soluble complexes, known for their excellent photophysical properties which makes them great candidates for lighting. The thesis describes the study of Eu¹¹¹ and Tb¹¹¹ tris-dipicolinate complexes in the crystalline form with different cations, as well as more complex systems like mixed co-crystals and core/shell crystals. The Eu¹¹¹ and Tb¹¹¹ complexes were also used as dopant in mesostructured silica materials via an incipient wetness impregnation method leading to homogeneous materials. The photophysical properties these different materials were thoroughly studied and a significant exaltation of the emission was evidenced in the silica. In particular, the influence of the O-X oscillators was explored and determination of the intrinsec quantum yield gave a clearer image on this exaltation. The recyclability of the lanthanide complexes from the material has been proven with high rates. Finally, white light emitting materials were obtained by mixing red, green and blue emitters. The naphthalimide moiety was chosen as blue emitter and white luminescence was successfully obtained in the solid state and for a silica material, representing a first generation of recyclable white light emitting materials based on lanthanide tris-dipicolinate complexes
9
Swaminathan, Swathi. "Bio-Inspired Materials and Micro/Nanostructures Enabled by Peptides and Proteins." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4223.
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The development of a general approach for non-destructive chemical and biological functionalization of materials could expand opportunities for both fundamental studies and creating various device platforms. Phage display has emerged as a powerful method for selecting peptides that possess enhanced selectivity and binding affinity toward a variety of targets. In this study, a powerful yet benign approach for identifying binding motifs to materials like (Poly) dimethylsiloxane, epoxy, and (Poly) ethylenetetraphthalate and peptide nanotubes has been demonstrated via comprehensively screened phage-displayed peptides. Further, along with the development of microstructures, micropatterns and micro-molecular self-assembly, recognition with phage-displayed peptides can be specifically localized in these microstructures.
In addition, the development of a facile approach for fabricating a library of precisely positioned nanostructures and microfluidic systems based on mammalian hair offers exciting opportunities in fundamental research and practical applications. The current top-down and bottom-up nanofabrication methods have been restricted in accessibility in standard labs due to their high cost and complexity. Novel fabrication methods utilizing biomimetic materials and natural proteins for large-scale nanopatterning with hierarchical assembly of functional materials have been reported. It is anticipated that these results could open up exciting opportunities in the use of peptide-recognized materials in fundamental biochemical recognition studies, as well as in applications ranging from analytical storage devices, hybrid materials, sensors, surface and interface, to cell biology.
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Xiao, Ming. "BIO-INSPIRED MELANIN-BASED STRUCTURAL COLORS THROUGH SELF-ASSEMBLY." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron149927021458423.
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Svagan, Anna. "Bio-inspired cellulose nanocomposites and foams based on starch matrix." Doctoral thesis, KTH, Biokompositer, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9666.
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In 2007 the production of expanded polystyrene (EPS) in the world was over 4 million tonnes and is expected to grow at 6 percent per year. With the increased concern about environmental protection, alternative biodegradable materials from renewable resources are of interest. The present doctoral thesis work successfully demonstrates that starch-based foams with mechanical properties similar to EPS can be obtained by reinforcing the cell-walls in the foams with cellulose nanofibers (MFC). High cellulose nanofiber content nanocomposites with a highly plasticized (50/50) glycerol-amylopectin starch matrix are successfully prepared by solvent-casting due to the high compatibility between starch and MFC. At 70 wt% MFC, the nanocomposites show a remarkable combination of high tensile strength, modulus and strain to failure, and consequently very high work to fracture. The interesting combination of properties are due to good dispersion of nanofibers, the MFC network, nanofiber and matrix properties and favorable nanofiber-matrix interaction. The moisture sorption kinetics (30% RH) in glycerol plasticized and pure amylopectin film reinforced with cellulose nanofibers must be modeled using a moisture concentration-dependent diffusivity in most cases. The presence of cellulose nanofibers has a strong reducing effect on the moisture diffusivity. The decrease in zero-concentration diffusivity with increasing nanofiber content could be due to geometrical impedance, strong starch-MFC molecular interaction and constrained swelling due to the cellulose nanofiber network present. Novel biomimetic starch-based nanocomposite foams with MFC contents up to 40 wt% are successfully prepared by freeze-drying. The hierarchically structured nanocomposite foams show significant increase in mechanical properties in compression compared to neat starch foam. Still, better control of the cell structure could further improve the mechanical properties. The effect of cell wall composition, freeze-drying temperature and freezing temperature on the resulting cell structure are therefore investigated. The freeze-drying temperature is critical in order to avoid cell structure collapse. By changing the starch content, the cell size, anisotropy ratio and ratio between open and closed cells can be altered. A decrease in freezing temperature decreases the cell size and increases the anisotropy ratio. Finally, mechanical properties obtained in compression for a 30 wt% MFC foam prepared by freeze-drying demonstrates comparable properties (Young's modulus and yield strength) to expanded polystyrene at 50% RH and similar relative density. This is due to the reinforcing cellulose nanofiber network within the cell walls.QC 20100913
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Varshney, Swati (Swati Rani). "Biological and bio-inspired morphometry as a route to tunable and enhanced materials design." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104101.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
Structural materials in nature integrate classical materials selection rules with morphometry (geometry or shape-based rules) to create high-performance, multi-functional structures that exhibit tunable properties through extraordinary complexity, hierarchy, and precise structural control. This thesis explores the use of morphometry as a materials design parameter through the development of bio-inspired, flexible composite armor based on the articulated exoskeleton of an armored fish, Polypterus senegalus, which achieves uniform coverage and protection from predatory threats without restricting flexibility. First, the functional implications of shape and shape variation are examined as materials design parameters within the biological exoskeleton using a new method that integrates continuum strain analysis with landmark-based geometric morphometric analysis in 2D and 3D. Bioinspired flexible composite prototypes are fabricated using multi-material 3D printing and tested under passive loading (self-weight) and active loading (bending) to examine how the shape of scales contributes to local, interscale mobility mechanisms that generate anisotropic, global mechanical behavior. With one prototype design scheme, a wide array of mechanical behavior is generated with stiffness ranging over several orders of magnitude, including 'mechanical invisibility' of the scales, showing how morphometry can tune flexibility without varying the constituent materials. Finally, finite element models simulating the bending experiments are created to establish a computational framework for analyzing the mechanical response of the prototypes. The finite element models are then extended to examine the effect of different loading conditions, scale morphometry, multi-material architecture, and constituent material properties. The results show how morphometric-enabled materials design, inspired by structural biological materials, can allow for tunable behavior in flexible composites made of segmented scale assemblies to achieve enhanced user mobility, custom fit, and flexibility around joints for a variety of protective applications.
by Swati Varshney.
Ph. D.
13
Learsch, Robert (Robert Whitson). "Engineering mechanical dissipation in solid poly(ethylene glycol) hydrogels with bio-inspired metal-coordinate crosslinks." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98658.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (page 32).
Growing evidence supports that the unique mechanical behavior of mussel byssal threads, such as high toughness and self-healing, rely on an intricate balance of permanent covalent and reversible metal coordination bonds. Inspired by this material crosslink chemistry balance, we synthesized polyethylene glycol (PEG) hydrogels with two crosslinked networks; a primary permanent network composed of covalently crosslinked 4-arm PEG and a secondary network composed of 4-arm PEG functionalized with histidine on each arm. The histidine decorated PEG forms a mechanically reversible network via metal ion coordinated crosslinks. Using rheometry, we study the contribution of the metal-coordinate network to the bulk gels mechanics and find that we can control both the amplitude and the frequency of peak mechanical dissipation with the histidine: metal ion ratio and the choice of metal ion, respectively. Furthermore, we can control the mechanical contribution of metal coordinate bonds by changes in pH. These simple bio-inspired gels promise to serve as a new model system for further study of opto-mechanical coupling of metal-coordinate soft materials.
by Robert Learsch.
S.B.
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de, Falco Paolino. "Mechanisms of deformation and energy dissipation in antler and arthropod cuticle with bio-inspired investigations." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/54050.
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Bio-composite hierarchical materials have attracted the interest of the academic community operating in the field of bio-inspired materials for their outstanding mechanical properties achieved via lightweight structural designs. Antler and mantis shrimp's cuticle are extreme examples of materials naturally optimised to resist impacts and bear dynamic loading. Firstly, a class of finite-element fibril models was developed to explain the origin of heterogeneous fibrillar deformation and hysteresis from the nanostructure of antler. Results were compared to synchrotron X-ray data and demonstrated that the key structural motif enabling a match to experimental data is an axially staggered arrangement of stiff mineralised collagen fibrils coupled with weak, damageable interfibrillar interfaces. Secondly, the cuticle of the crustacean Odontodactylus scyllarus, known as peacock mantis shrimp, was investigated. At the nanoscale it consists of mineralised chitin fibres and calcified protein matrix, which form plywood layers at the microscale. Lamination theory was used to calculate fibrillar deformation and reorientation and, in addition, an analytical formulation was used to decouple in-plane fibre reorientation from diffraction intensity changes induced by 3D lamellae tilting. This animal also attracted my attention for using its hammer-like appendages to attack and destroy the shells of prey with a sequence of two strikes. Inspired by this double impact strategy, I performed a set of parametric finite-element simulations of single, double and triple mechanical hits, to compute the damage energy of the target. My results reveal that the crustacean attack strategy has the most damaging effect among the double impact cases, and lead me to hypothesise, that optimal damaging dynamics exists, depending on the sequence of consecutive impacts and on their time separation values. These new insights may provide useful indications for the design of bio-inspired materials for high load-bearing applications.
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Samur, Algan. "Flexible piezoelectric composites and concepts for bio-inspired dynamic bending-twisting actuation." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47680.
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Zhang, Kun. "Mesostructured porous materials : Pore and surface engineering towards bio-inspired synthesis of heterogeneous copper catalysts." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2008. http://tel.archives-ouvertes.fr/tel-00310153.
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Le contrôle fin de la structure et de la chimie de surface en milieu confiné a été développé dans des silices poreuses mésostucturées de type MCM-41 pour synthétiser des catalyseurs hétérogènes combinant confinement moléculaire, hydrophobicité et spécificité de sites à l'instar des métalloprotéines. La surface considérée comme lisse a en fait une rugosité de type alvéolaire due à l'empreinte de la tête ammonium du tensioactif de synthèse. Pour des températures croissantes du traitement hydrothermal, la taille des mésopores augmente par érosion de cette rugosité puis diminue par épaississement des parois. On a aussi trouvé des conditions de synthèse de zéolihes mésoporeuses avec une micro- et mésoporosité hiérarchisée. Ces surfaces sont polyfonctionnalisées grâce à la technique de pochoir moléculaire pour isoler des fonctions bidentatés aminoéthylaminopropyles par des groupements hydrophobes triméthylsimyles. Les ions cuivriques sont alors retenus dans le matériau par complexation à ces fonctions diamino.
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Merindol, Rémi. "Layer-by-layer assembly of strong bio-inspired nanocomposites." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAE015/document.
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Les performances exceptionnelles des composites naturels comme la nacre ou le bois émergent de l’arrangement précis d’éléments souples et rigides à l’échelle nanométrique. L’assemblage couche-par-couche permet la fabrication de films avec un contrôle nanométrique de l’organisation et de la composition. Ce travail décrit l’assemblage et les propriétés de nouveaux nano-composites contenant des nano-renforts 1-D (fibrilles de cellulose) et 2-D (plaquettes d’argile). Nous avons combiné les argiles avec une matrice extrêmement souple de poly(diméthylsiloxane) dans une architecture lamellaire imitant celle de la nacre. Nous avons étudié des composites à base de fibrilles de cellulose aléatoirement orientées dans le plan, puis alignées dans une direction pour mieux imiter les parois cellulaires du bois. Les propriétés mécaniques de ces composites bio-inspirés égalent ou surpassent celles de leurs homologues naturels, tout en étant transparents et dans certains cas auto-réparantsNatural materials such as nacre or wood gain their exceptional mechanical performances from the precise organisation of rigid and soft components at the nano-scale. Layer-by-layer assembly allows the preparation of films with a nano-scale control over their organisation and composition. This work describes the assembly and properties of new nano-composites containing 1-D (cellulose nano-fibrils) and 2-D (clay nano-platelets) reinforcing elements. The clay platelets were combined with an extremely soft matrix (poly(dimethylsiloxane)) to mimic the lamellar architecture of nacre. Cellulose based composites with a random in plane orientation of the fibrils were studied first, later we aligned the fibrils in a single direction to mimic further the cell wall of wood. The mechanical properties of these bio-inspired composites match or surpass those of their natural counterparts, while being transparent and in one case self-repairing
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Ghodratighalati, Mohamad. "Multiscale Modeling of Fatigue and Fracture in Polycrystalline Metals, 3D Printed Metals, and Bio-inspired Materials." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/104944.
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The goal of this research is developing a computational framework to study mechanical fatigue and fracture at different length scales for a broad range of materials. The developed multiscale framework is utilized to study the details of fracture and fatigue for the rolling contact in rails, additively manufactured alloys, and bio-inspired hierarchical materials. Rolling contact fatigue (RCF) is a major source of failure and a dominant cause of maintenance and replacements in many railways around the world. The highly-localized stress in a relatively small contact area at the wheel-rail interface promotes micro-crack initiation and propagation near the surface of the rail. 2D and 3D microstructural-based computational frameworks are developed for studying the rolling contact fatigue in rail materials. The method can predict RCF life and simulate crack initiation sites under various conditions. The results obtained from studying RCF behavior in different conditions will help better maintenance of the railways and increase the safety of trains.
The developed framework is employed to study the fracture and fatigue behavior in 3D printed metallic alloys fabricated by selective laser melting (SLM) method. SLM method as a part of metal additive manufacturing (AM) technologies is revolutionizing the manufacturing sector and is being utilized across a diverse array of industries, including biomedical, automotive, aerospace, energy, consumer goods, and many others. Since experiments on 3D printed alloys are considerably time-consuming and expensive, computational analysis is a proper alternative to reduce cost and time. In this research, a computational framework is developed to study fracture and fatigue in different scales in 3D printed alloys fabricated by the SLM method. Our method for studying the fatigue at the microstructural level of 3D printed alloys is pioneering with no similar work being available in the literature. Our studies can be used as a first step toward establishing comprehensive numerical frameworks to investigate fracture and fatigue behavior of 3D metallic devices with complex geometries, fabricated by 3D printing.
Composite materials are fabricated by combining the attractive mechanical properties of materials into one system. A combination of materials with different mechanical properties, size, geometry, and order of different phases can lead to fabricating a new material with a wide range of properties. A fundamental problem in engineering is how to find the design that exhibits the best combination of these 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 materials, we have simulated fracture behavior of a pre-designed composite material consisting of soft and stiff building blocks. The results show a better performance of bio-inspired composites compared to their building blocks. Furthermore, an optimization methodology is implemented into the designing the bio-inspired composites for the first time, which enables us to perform the bio-inspired material design with the target of finding the most efficient geometries that can resist defects in their structure. This study can be used as an effective reference for creating damage-tolerant structures with improved mechanical behavior.Doctor of Philosophy
The goal of this research is developing a multiscale framework to study the details of fracture and fatigue for the rolling contact in rails, additively manufactured alloys, and bio-inspired hierarchical materials. Rolling contact fatigue (RCF) is a major source of failure and a dominant cause of maintenance and replacements in many railways around the world. Different computational models are developed for studying rolling contact fatigue in rail materials. The method can predict RCF life and simulate crack initiation sites under various conditions and the results will help better maintenance of the railways and increase the safety of trains. The developed model is employed to study the fracture and fatigue behavior in 3D printed metals created by the selective laser melting (SLM) method. SLM method as a part of metal additive manufacturing (AM) technologies is revolutionizing industries including biomedical, automotive, aerospace, energy, and many others. Since experiments on 3D printed metals are considerably time-consuming and expensive, computational analysis is a proper alternative to reduce cost and time. Our method for studying the fatigue at the microstructural level of 3D printed alloys can help to create more fatigue and fracture resistant materials. In the last section, we have studied fracture behavior in bio-inspired materials. A fundamental problem in engineering is how to find the design that exhibits the best combination of mechanical properties. Biological materials like bone, nacre, and teeth are constructed from simple building blocks and show a surprising combination of high strength and toughness. By inspiring from these materials, we have simulated fracture behavior of a pre-designed composite material consisting of soft and stiff building blocks. The results show a better performance of bio-inspired structure compared to its building blocks. Furthermore, an optimization method is implemented into the designing the bio-inspired structures for the first time, which enables us to perform the bio-inspired material design with the target of finding the most efficient geometries that can resist defects in their structure.
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Young, Seth Lawton. "Atomic force microscopy probing methods for soft viscoelastic synthetic and biological materials and structures." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54982.
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The focus of this dissertation is on refining atomic force micrscopy (AFM) methods and data analysis routines to measure the viscoelastic mechanical properties of soft polymer and biological materials in relevant fluid environments and in vivo using a range of relevant temperatures, applied forces, and loading rates. These methods are directly applied here to a several interesting synthetic and biological materials. First, we probe poly(n-butyl methacrylate) (PnBMA), above, at and below its glass transition temperature in order to verify our experimental procedure. Next, we use AFM to study the viscoelastic properties of coating materials and additives of silicone-based soft contact lenses in a tear-like saline solution. Finally, a major focus in this dissertation is determining the fundamental mechanical properties that contribute to the excellent sensitivity of the strain sensing organs in a wandering spider (Cupiennius salei) by probing under in vivo conditions. These strain-sensing organs are known to have a significant viscoelastic component. Thus, the cuticle of living spiders is directly investigated in near-natural environments (high humidity, temperatures from 15-40 °C). The main achievements of these studies can be summarized through the following findings: We suggest that full time-temperature-modulus relationships are necessary for the understanding of soft materials systems, and present a practical method for obtaining such relationships. These studies will have a direct impact on both scientists in the metrology field by developing practical experimental procedures and data analysis routines to investigate viscoelastic mechanical properties at the nanoscale, and future materials scientists and engineers by showing via spider mechanosensory systems how viscoelasticity can be applied for functional use in sensing technology.
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Huang, Weichun. "Acoustic properties of natural materials." Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1031/document.
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Dans cette thèse, nous étudions un métamatériau inspiré de la paille de blé pour l'absorption parfaite du son. Une botte de paille estidéalisée comme un milieu poreux anisotrope, composé d’un arrangement périodique très concentré de tubes creux cylindriques. L’approche théorique de ce métamatériau repose sur l'homogénéisation asymptotique à deux échelles d'un réseau perméable de résonateursparfaitement rigides dont la physique est enrichi par des résonances internes. Les principales caractéristiques de ce milieu poreux sont lacompressibilité effective négative autour de la résonance du tube et la réduction drastique de la vitesse de propagation du son (slowsound) à très basse fréquence. Une configuration optimale est conçue, basée sur la condition de couplage critique, pour laquelle la fuited’énergie du système résonnant ouvert est parfaitement compensée par les pertes intrinsèques induites par les pertes viscothermiques.Des mesures en tube à impédance sont effectuées sur des échantillons fabriqués par impression additive pour valider les résultatsthéoriques. Nous montrons que ce métamatériau est un absorbeur sub-longueur d'onde capable d’une absorption parfaite à très bassefréquence et d'introduire une quasi-bande interdite autour de la résonance du tube. De plus, la nature anisotrope de ce matériau conduit àune absorption globalement élevée à basse fréquence et ce pour toutes les incidences. Cette étude offre la possibilité de concevoir unabsorbeur acoustique sélectif en angle et en fréquence. Pour conclure, les résultats de cette thèse montrent que la paille est un boncandidat pour une absorption acoustique parfaiteStraw-inspired metamaterials for sound absorption are investigated in this Thesis. A straw stack is idealized as a highly concentratedresonant anisotropic porous medium constituted of a periodic arrangement of densely packed cylindrical hollow tubes. The approach tothis metamaterial relies on the two-scale asymptotic homogenization of a permeable array of perfectly rigid resonators, where the physicsis further enriched by tailoring inner resonances. The main features of such sound absorbing medium are the possibility for the effectivecompressibility to become negative around the tube resonance and the drastic reduction of the effective sound speed (slow sound) at verylow frequency in the system. Moreover, an optimal configuration for sound absorption is designed, based on the critical couplingcondition, in which the energy leakage out of the open resonant system is perfectly compensated by the intrinsic losses induced by thevisco-thermal losses both in the anisotropic matrix and in the resonators. Impedance tube measurements are performed on 3-D printedsamples with controlled parameters to validate the theoretical results. This metamaterial is a sub-wavelength absorber that can achievetotal absorption at a very low frequency and possesses a quasi-band-gap around the tube resonance. Furthermore, the anisotropic nature ofthe configuration gives rise to high absorption at low-frequency range for all incidences and diffuse field excitation. It paves the way tothe design of angular and frequency selective sound absorber. To conclude, the results of this Thesis show that straw is a good candidatefor perfect sound absorption
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Zhang, Yuanwen. "Design of two-dimensional TiO2 based nanomaterials for sustainable applications." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/205464/1/Yuanwen_Zhang_Thesis.pdf.
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This thesis focuses on the design of metal oxide based two‐dimensional nanomaterials for various sustainable applications. The as-prepared 2D TiO2-based nanomaterials and their hybrid compounds have been characterized and applied in different sustainable environmental and energy applications and showed superior properties. It is believed that the research and investigations on 2D nanomaterials based sustainable applications is of great significance for the further development of a green, sustainable, and environmentally friendly society.
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Mujica, Randy. "Layer-by-Layer assembly of nanocellulose composite films with bio-inspired helicoidal superstructures." Thesis, Strasbourg, 2020. http://www.theses.fr/2020STRAE011.
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Les propriétés optiques et mécaniques remarquables des matériaux naturels sont souvent associées à la complexité de leurs structures hiérarchiques. L’une des plus complexes est la structure hélicoïdale, constituée de plusieurs couches de fibres alignées dont l’orientation tourne entre les couches voisines. Cette microstructure, dite de Bouligand, est associée à la résistance aux chocs accrue de la carapace de certains crustacés ainsi qu’à la réflexion préférentielle de la lumière polarisée circulaire de certains fruits et insectes. Dans ce travail, nous avons fabriqué des films minces bio-inspirés complexes composés de nanofibrilles de cellulose et de poly(vinylamine) en utilisant l'approche couche-par-couche (LbL) et la pulvérisation à incidence rasante (GIS), une méthode permettant de contrôler l'alignement dans le plan de nano-objets anisotropes comme les nanofibrilles de cellulose. Nous avons démontré la possibilité de contrôler de façon indépendante la direction de l'alignement de chaque couche de cellulose. Ainsi, nous avons pu préparer des films minces avec une orientation unidirectionnelle, croisée ou hélicoïdale des nanofibrilles de cellulose, ce qu’il n’est pas possible de faire avec d’autres procédés de fabrication. Les propriétés optiques de ces films ont été caractérisées par dichroïsme circulaire et ellipsométrie spectroscopique à matrice de Mueller. Nous avons observé que la réponse chirale des films hélicoïdaux est contrôlée par le sens de rotation, le pas de l’hélice et le nombre de couches avant rotation. Les propriétés mécaniques de ces films ont été étudiées par différentes méthodes de nanoindentation. La méthodologie de fatigue par nano-contact a montré une ductilité accrue des films unidirectionnels et hélicoïdaux, qui peut être indirectement liée à une absorption accrue de l'énergie de ce matériau lors des sollicitations en raison de sa structure interneThe remarkable optical and mechanical properties of natural materials are often associated with the complexity of their hierarchical structures. One of the most complexes is the helical structure which consists of several layers of unidirectionally aligned fibers whose orientation rotates with respect to their neighboring layers. This so-called Bouligand microstructure is responsible for the enhanced impact resistance of the shell of some crustaceans as well as the preferential reflection of circularly polarized light of certain fruits and insects. Here, we fabricated complex bio-inspired thin films made of cellulose nanofibrils and poly(vinylamine) using the layer-by-layer (LbL) approach and grazing incidence spraying (GIS), a method allowing to control the in-plane alignment of anisotropic nano-objects like cellulose nanofibrils. We demonstrated the independent direction of alignment of each cellulose layer, which allowed the preparation of thin films with well-defined internal structures, namely, unidirectional, cross-ply or helical arrangement of the reinforcing nanofibrils, which is impossible to achieve by any other fabrication process. The optical properties of these films were characterized by circular dichroism (CD) and by Mueller matrix ellipsometry. The chirality observed for helicoidal films is controlled by the rotation direction, the pitch, and the number of layers. The mechanical properties of these cellulose-based films were studied by various nanoindentation methods. A nano-contact fatigue methodology showed an increased ductility of the unidirectional and helicoidal films, which can be indirectly related to enhanced absorption of energy of this material owing to their internal structure
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Farhadi-Khouzani, Masoud [Verfasser]. "Study of Structures and Crystallization Behavior of Amorphous Calcium Carbonate (ACC) and its Application in Bio-inspired Materials / Masoud Farhadi-Khouzani." Konstanz : Bibliothek der Universität Konstanz, 2017. http://d-nb.info/1132995663/34.
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Mueller, Lena Verfasser], Alesia [Akademischer Betreuer] [Tietzte, and Gerhard [Akademischer Betreuer] Thiel. "Chemical synthesis of switchable peptide-based nanopores: from ion channels to bio-inspired materials / Lena Mueller ; Alesia A. Tietze, Gerhard Thiel." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1211478009/34.
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Mueller, Lena [Verfasser], Alesia A. [Akademischer Betreuer] Tietze, and Gerhard [Akademischer Betreuer] Thiel. "Chemical synthesis of switchable peptide-based nanopores: from ion channels to bio-inspired materials / Lena Mueller ; Alesia A. Tietze, Gerhard Thiel." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1211478009/34.
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Gaddis, Christopher Stephen. "Diatom Alchemy." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7611.
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This work resulted in the development of multiple distinct and novel methods of cheaply producing large numbers of biologically derived, complex, 3-dimensional microstructures in a multitude of possible compositions. The biologically derived structures employed in this work were diatoms, a type of single celled algae, which grow complex silica shells in species-specific shapes. Due to the wide diversity of naturally occurring diatom shapes (on the order of 105), and the flexibility in tailoring chemical compositions using the methods developed here, real potential exists for cheaply mass-producing industrially relevant quantities of controlled shape and size 3-d particles for the first time. The central theme of this research is the use of diatoms as a transient scaffold onto which a coating is applied. After curing the coating, and in some cases firing the coating to form ceramic, the diatom can be selectively etched away leaving a free standing replica of the original structure with the salient features of the pre-form intact, but now composed of a completely different material. Using this concept, specific methods were developed to suit various precursors. Dip coating techniques were used to create epoxy diatoms, and silicon carbide diatoms. The Sol-Gel method was used to synthesize zirconia diatoms in both the tetragonal and monoclinic phases. A multi step method was developed in which previously synthesized epoxy diatoms were used as a template for deposition of a silicon carbide precursor and then heat treated to produce a silicon carbide/carbon multi-component ceramic. A hydrothermal reaction was also developed to convert Titania diatoms to barium titanate by reaction with barium hydroxide. Finally, the device potential of diatom-derived structures was conclusively demonstrated by constructing a gas sensor from a single Titania diatom. Under suitable conditions, the sensor was found to have the fastest response and recovery time of any sensor of this type reported in the literature. Furthermore, this work has laid the groundwork for the synthesis of many other tailored compositions of diatoms, and provided several compositions for device creation.
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Garmann, Daniel J. "Characterization of the vortex formation and evolution about a revolving wing using high-fidelity simulation." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367927773.
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Ponzio, Florian. "Synthesis at different interfaces of bio-inspired films from mussels' byssus : influence of the oxidant nature at the solid/liquid interface and the addition of polymer at the air/water interface." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAE041/document.
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Les matériaux à base de polydopamine (PDA) s’inspirent de la forte adhésion du byssus de la moule sous l’eau. L’oligomérisation de la dopamine dans un milieu basique permet la formation de revêtement de PDA sur n’importe quel matériau. En plus de la simplicité du procédé celui-ci est vert et versatile. La PDA a des propriétés similaires aux mélanines, d’où son utilisation dans le domaine des phénomènes de conversion d’énergie, de l’environnement et du biomédical. Cependant la structure de la PDA étant inconnue, l’élaboration de matériaux basés sur la relation structure propriétés est difficile. L’un des buts de cette thèse a été de comprendre cette relation pour élaborer de nouveaux matériaux de PDA. En choisissant l’oxydant adéquat nous avons déposé un film épais, superhydrophile et biocompatible sur n’importe quels substrats. De plus nous avons découverts la possibilité de former des films de PDA à l’interface air/eau. L’étude de ce phénomène a permis de former des membranes autosupportées et stimuli responsivesPolydopamine (PDA) materials are inspired from mussels’ byssus strong adhesion underwater. The oligomerization of dopamine in a basic medium allows forming a PDA coating on virtually any materials. In addition to the simplicity, ecofriendly and versatility of the deposition method, PDA has properties similar to those of melanin pigments and displays many outstanding properties. Thus PDAis widely used in energy, environmental and biomedical sciences. However design of PDA based new materials with tailored properties is a challenge since its structure is still unknown. In that sense one of the aims of this thesis is to gain knowledge in PDA structure-property relationship in order to design PDA materials with new properties. By choosing the appropriate oxidant we deposited thick and superhydrophylic films on any materials for the elaboration of low fouling and biocompatible surfaces. Additionally we discovered the possibility to form PDA films at the air/water interface. The investigation of this phenomenon led to the formation of stimuli responsive free standing membranes
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Chiari, Lucile. "Développement de nouveaux systèmes bio-hybrides pour la photocatalyse asymétrique." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAV029.
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Au cours des dernières décennies, le développement d'une chimie durable est devenu une priorité pour notre société Dans ce contexte, la biocatalyse, par l’utilisation d’enzymes naturelles, modifiées ou artificielles constituées d’un catalyseur de synthèse greffé au sein d’une protéine apparait comme une solution intéressante.Dans ce projet, nous cherchons à développer des photocatalyseurs bio-hybrides combinant un photosensibilisateurs (RuPhot) et un catalyseurs (RuCat) au sein d'un cristal protéique pour la photocatalyse hétérogène d’oxydation asymétrique de substrats organiques en utilisant l’eau comme seule source d’atome d’oxygène. La protéine sélectionnée est le domaine d'oligomérisation de la protéine Leafy du Ginkgo biloba. Cette protéine est capable de générer des structures poreuses par auto-assemblage. A l'intérieur des tubes, une chaîne peptidique d'environ 30 acides aminés par monomère est présente et servira de plateforme de greffage. Trois systèmes hybrides cristallins avec RuPhot et RuCat seuls ainsi qu’avec une combinaison des deux ont été obtenus. La mise au point des techniques de caractérisation a été faite sur l’hybride RuCat apportant des informations intéressantes sur la cinétique et la sélectivité du greffage ainsi que sur une modification du catalyseur intervenant au cours du greffage. Les études réalisées sur l’hybrides RuPhot ont quant à elles montrées qu’il était possible, comme cela était planifié de greffer plusieurs chromophores par protéine et de pouvoir bénéficier ainsi d’un effet d’antenne pour une efficacité maximisée. Les études catalytiques pour l'oxydation des sulfures et des alcènes sont en cours.Dans un tout autre domaine, 16% de cette thèse a été consacré à un contrat de doctorat conseil auprès de l'entreprise NMRBio. L'objectif était de développer de nouvelles voies de synthèses de composés marqués par des isotopes stables en vue d'études structurales et dynamiques de protéines par RMNFor the last decades the development of sustainable chemistry became a priority for our society. In this context, biocatalysis appears to be an interesting solution, through the use of natural, modified or artificial enzymes consisting of a synthetic catalyst grafted into a protein.In this project, we aim to develop bio-hybrid photocatalysts combining a photosensitizer (RuPhot) and a catalyst (RuCat) within a protein crystal for heterogeneous asymmetric oxidation photocatalysis of organic substrates using water as the only source of oxygen atoms. The selected protein is the oligomerization domain of the Leafy protein of Ginkgo biloba. This protein is able to generate porous structures by self-assembly. Inside the tubes, a peptide chain of about 30 amino acids per monomer is present and it will serve as grafting platform. Three crystalline hybrid systems were obtained with RuPhot and RuCat alone as well as a combination of the two. The characterization was carried out on the RuCat hybrid providing interesting information on the kinetics and selectivity of grafting as well as on a modification of the catalyst during grafting. The studies carried out on the RuPhot hybrids have shown that it was possible, as planned, to graft several chromophores per protein and thus benefit from an antenna effect for maximum efficiency. Catalytic studies for the oxidation of sulphides and alkenes are underway.In a completely different field, 16% of this thesis was devoted to a doctoral consulting contract with the company NMRBio. The objective was to develop new pathways for the synthesis of stable isotope-labelled compounds in order to perform structural and dynamic NMR studies in proteins
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Pooyan, Parisa. "Bio-inspired polymer nanocomposites for tissue engineering applications." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53439.
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Increasing emphasis has been placed on the use of renewable resources, on decreased reliance on petroleum in order to better utilize global energy needs. Biological structures available in nature have been a constant inspiration to the design and fabrication of the new line of functional biomaterials whose unique phenomena can be exploited in novel applications. In tissue engineering for example, a natural biomimetic material with close resemblance to the profile features existed in a native extracellular matrix could provide a temporary functional platform to regulate and control cellular interactions at a molecular level and to subsequently direct a tissue regeneration. However, the lack of rigidity of natural materials typically limits their mass production. One promising approach to address this shortcoming is to introduce a biomimetic composite material reinforced by high purity nanofibers found in nature. As an attractive reinforcing filler phase, cellulose nanowhiskers (CNWs) offer exceptional properties such as high aspect ratio, large interface area, and significant mechanical performance. As such, CNWs could integrate a viable nanofibrous porous candidate, resulting in superior structural diversity and functional versatility. Inspired by the fascinating properties of cellulose and its derivatives, we have designed two bio-inspired nanocomposite materials reinforced with CNWs in this work. The successful grafting of CNWs within the host matrix and their tendency to interconnect with one another through strong hydrogen bonding gave rise to the formation of a three-dimensional rigid percolating network, fact which imparted considerable mechanical strength and thermal stability to the entire structure with only a small amount of filler content, i.e. 3 wt.%. Also, the biocompatibility of the nanocomposite was probed by in-vitro incubation of human-bone-marrow-derived mesenchymal stem cells (MSCs), which resulted in the invasion and proliferation of MSCs around the nanocomposite at day 8 of culture. The green functional biomaterial with its unique features in this work could open new perspectives in the self-assembly of nanobiomaterial for tissue-engineered scaffolding, while it could make the design of the next generation of fully green functional biomaterial a reality.
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Wan, Yiyang. "Bio-Inspired Material Surfaces with Self-cleaning, Micromanipulation and Water Collection." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505257/.
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Geckos are famous for the skill of switchable adhesion that they use to stick on various surface while keep their fingers super clean. In the dissertation, a unique mechanism was discovered to explain gecko self-cleaning phenomena. Using atomic force microscopy (AFM), we managed to compare the microparticle-substrate adhesion and the microparticle-seta adhesion with a single seta bonded to the AFM cantilever. A dynamic effect was approved that high pulling-off speed could increase the microparticle-substrate adhesion and thus the self-cleaning appears at high moving speed. Based on the self-cleaning theory, a gecko-inspired N-doped graphene surface with switchable adhesion was achieved, which was designed into a bio-inspired micromanipulator with a success rate over 90%. When electrical bias was applied on this biomimetic surface, the charge concentration induced an electrical double layer (ELD) on the convex surfaces, which attracts polar water molecules to form a water bridge on it, significantly enhancing the adhesion on the wrinkled graphene surface, mimicking the capillary force on beetle feet. Therefore, the bio-inspired adhesive surface can be controlled with speed, electrical bias, humidity and different material surfaces. The water attraction phenomenon on the polarized surface was further tested for the potential application of water collection and evaporation in microsystems.
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Lavayen, Farfán Daniel. "Non-linear beam theory in context of bio-inspired sensing of flows." Master's thesis, Pontificia Universidad Católica del Perú, 2016. http://tesis.pucp.edu.pe/repositorio/handle/123456789/8324.
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The thesis at hand is part of a research project that attempts to study and develop
vibrissa inspired tactile sensors for object and fluid flow detection. The main focus of the thesis
is on the development of a model for a vibrissa-like sensor for obstacle contour recognition under
fluid loads. To this end, a mechanical model – based on the non-linear Euler-Bernoulli beam theory
– is established. The model includes the main characteristics found in a natural vibrissa, such as
elasticity of the base, that acts as the vibrissa follicle; the intrinsic curvature; and conicity.
The characteristics are represented as parameters of the model. The model is subjected to a contact
load and a fluid flow load, represented by a concentrated load and a distributed load,
respectively. Then, the model is transformed into a dimensionless representation for further
studies to achieve more general assertions. A variation of the magnitude of these loads, as well as
the vibrissa parameters is also analyzed. A direct numerical approximation using the finite
difference method, along with the shooting method, is used to obtain a solution of the model.
Subsequently, the model is used to simulate an ideal contact between an obstacle and the vibrissa.
This simulation considers a quasi-static sweep of the artificial vibrissa with the contour of a
profile, while measuring and recording the forces and moment at the base. This procedure is then
repeated in combination of a distributed force acting on the vibrissa, simulating the effect of a
fluid flow. Two types of contact phases are identified and the conditions for each one are set.
Finally, the measured quantities, which represent the observables an animal solely relies on, are
used to obtain the magnitude of the fluid load and to reconstruct the profile contour of the
obstacle. The developed model is used again for the reconstruction, an analysis of the observables
is performed to identify and predict which contact phase the vibrissa is in. The results
successfully show identification of the fluid flow load as well as reconstruction of the profile,
the difference between the reconstructed profile and the
original profile is then calculated as a measure of reconstruction quality.Tesis
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Garner, Austin Michael. "Examining the Relationships between Form, Function, Environment, and Behavior in Adhesive Pad-bearing Lizards." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1626363948177358.
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Richtár, Jan. "Syntéza a charakterizace nových organických materiálů pro organickou elektroniku." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-433253.
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Organická elektronika a bioelektronika zažívá v moderním věku obrovskou snahu o vývoj nových organických materiálů s vlastnostmi, které běžná elektronika na bázi křemíku obvykle nedosahuje. Tato práce se zabývá syntézou a charakterizací nových organických materiálů pro organickou elektroniku. Zaobírá se přípravou nových pentafluorsulfanylových heterocyklických stavebních bloků, alkylovaných vysokoúčinných organických pigmentů a bioinspirovaných organických -konjugovaných materiálů s modifikovatelnými fyzikálně-chemickými vlastnostmi a racionálními syntetickými přístupy k jejich přípravě. Pentafluorsulfanylová skupina (SF5) je ceněna pro svou vysokou elektronegativitu, lipofilitu, tepelnou a chemickou stabilitu. Pozitivně ovlivňuje optické a elektronické vlastnosti, rozpustnost a stabilitu v často lepší míře než u zavedených CF3-analogů. Šesti a čtyřkrokovou syntézou byly připraveny dva typy derivátů 3-SF5-substituovaných pyrrolidinů, které mohou sloužit jako všestranné stavební jednotky pro začlenění do pokročilých aromatických a heteroaromatických -konjugovaných systémů prostřednictvím atomů dusíku jako fluorované terminální skupiny. Modelový derivát byl zaveden jako terminální skupina do elektronově chudého heteroaromatického systému nukleofilní substitucí. Vodíkovými můstky vázané vysokovýkonné organické pigmenty přitahují velkou pozornost díky svým působivým polovodivým vlastnostem, silné 2D molekulární asociaci, vysoké tepelné, chemické a fotochemické stabilitě a nízké toxicitě. Přesto jsou pouze omezeně rozpustné a zpracovatelné, což lze vyřešit zavedením solubilizačních skupin. Je známo, že obzvláště objemné rigidní skupiny nesoucí adamantyl zlepšují uspořádání molekulární struktury, tepelnou stabilitu a výsledné vlastnosti díky samoorganizační schopnosti adamantanu. Adamantylmethylová a adamantylethylová skupina byla zavedena do vybraných barviv a pigmentů ze skupiny karbonylových azaacenů, rylen-diimidů a indigoidů pomocí nukleofilní substituce se zaměřením na zvýšení rozpustnosti a zpracovatelnosti při zachování tepelné stability a efektivní molekulární organizaci v pevné fázi. Fyzikálně-chemické studie série derivátů quinacridonu a epindolidionu ukázaly srovnatelnou, nebo vyšší tepelnou stabilitu než u nesubstituovaných derivátů, dobrou rozpustnost v organických rozpouštědlech, silnou fluorescenci v pevné fázi a roztoku v oblasti VIS a unikátní krystalovou strukturu pozorovanou z RTG analýzy. Flaviny jsou všudypřítomné bioinspirované organické materiály s nepostradatelnými biologickými funkcemi, výhodnými fyzikálně-chemickými vlastnostmi, chemickou a aplikační všestranností. Cílem práce byla modifikace optických, elektronických, elektrochemických, tepelných a dalších vlastností rozšířením -konjugovaného systému syntetizovaných materiálů. V první fázi byly navrženy dva syntetické přístupy pro přípravu série NH-nesubstituovaných flavinů, u kterých byly provedeny komplexní fyzikálně-chemické studie. Poté byly navrženy dva přístupy k syntéze N,N'-dialkylovaných flavinů s inkorporovaným butylovým, adamantylethylovým a triethylenglykolovým substituentem. Alkylací byla zvýšena rozpustnost v organických rozpouštědlech a vodném prostředí, zesílena fluorescence v pevné fázi a v roztocích a modifikovány tepelné vlastnosti v závislosti na zavedeném alkylovém substituentu.
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Mortier, Claudio. "Conception de surfaces bio-inspirées à mouillabilité contrôlée à partir de polymères conducteurs." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4110/document.
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Le contrôle de la mouillabilité de surface est un enjeu majeur pour le développement de matériaux innovants liés aux nano, bio et smart technologies. La mouillabilité est fonction de deux paramètres majeurs : l’énergie de surface du matériau et sa morphologie. La combinaison de ces deux paramètres est à la base de phénomènes tels que la super/parahydrophobie ou la superoléophobie. Ces capacités extrêmes à repousser les liquides avec soit une forte ou faible adhésion sont des propriétés de surface très intéressantes pour de multiples applications industrielles. La présente thèse propose l’étude d’une série de dérivés du polypyrrole élaborés par électrodéposition permettant d’influencer les paramètres régissant la mouillabilité de surface. Par cette approche, il a été possible d’élaborer des surfaces aux morphologies diverses avec une gamme de mouillabilité complète. Les différentes fonctionnalisations par des groupements hydrophobes greffés sur différentes positions préférentielles du monomère ont conduit à l’élaboration de surfaces para et superhydrophobes mettant en évidence l’impact de l’énergie de surface et de la morphologie sur la mouillabilité. Des études préliminaires ont mis en évidence la possibilité d’obtenir des morphologies variées allant de sphères jusqu’à des fibres à l’échelle du micro/nanomètre. Finalement, ces travaux contribuent à un contrôle en amont de la mouillabilité et de la morphologie de surface pour de nombreuses applications potentielles comme les matériaux collecteurs d’eau, les membranes séparatrices de liquide ou bien les revêtements auto nettoyantThe control of the surface wettability is a key point for the development of innovative materials in several domains such as nano-, bio- and smart-technologies. The wettability is a function of two main parameters of the materials, such as the surface energy and the surface morphology. The combination of these two parameters allows to observe wetting phenomena as super/parahydrophobicity and superoleophobicity. These extreme abilities to repel liquids with different adhesion behaviors are very interesting properties for several industrial applications. This work presents a series of polypyrrole derivatives elaborated by electrodeposition allowing to influence the parameters driving the surface wettability. Following this approach, it was possible to develop surfaces with several types of morphology and different wetting behaviors from a low to high wettability. The different functionalizations using hydrophobic compounds grafted on various preferential positions on the monomer core yielded to para and superhydrophobic surfaces showing the impact of the surface energy and morphology on the wettability. Thanks to preliminary studies, it was showed the possibility to obtain several morphologies from spherical aggregates to fibers at the micro/nano scale. Finally, this work contributes to an upstream control of the surface wettability and morphologies for many potential applications such as water harvesting, separation membranes and self-cleaning coatings
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Abry, Sébastien. "Ingénierie moléculaire de surface appliquée à la conception de catalyseurs hétérogènes bio-inspirés." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2007. http://tel.archives-ouvertes.fr/tel-00260531.
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La double fonctionnalisation de la surface d'une silice mésostructurée de type MCM-41 (LUS) a été étudiée, en utilisant une nouvelle technique de "pochoir moléculaire" conduisant à une distribution régulière des fonctions. C'est un procédé de greffage séquentiel qui met en œuvre dans la 1ère étape un principe de rétention du tensioactif assurant la régularité spatiale des groupements à greffer. La 2nde fonctionnalisation par organosilylation est réalisée avec déplacement du reste du tensioactif. Des complexes polyammino biosinspirés de cuivre et d'europium ont été greffés dans des silices mésoporeuses LUS en utilisant cette approche. Les caractérisations effectuées à chaque étape de synthèse en utilisant un panel de techniques (dont XRD, N2-adsorption-desorption, 13C et 29Si MAS-RMN, FT-IR, RPE, EXAFS et MET) confirment l'intégrité de la structure poreuse, la formation des complexes et l'homogénéité de la distribution des fonctions.
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McConney, Michael Edward. "Learning and applying material-based sensing lessons from nature." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29749.
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Thesis (Ph.D)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2010.Committee Chair: Tsukruk, Vladimir; Committee Member: Shofner, Meisha; Committee Member: Srinivasarao, Mohan; Committee Member: Thio, Yonathan; Committee Member: Weissburg, Marc. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Bonnefoy, Jonathan. "Conception de nouveaux matériaux hybrides types MOFs bio-inspirés à fonctionnalités avancées pour la catalyse." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10195/document.
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Les MOFs sont des solides à la structure cristalline poreuse à base de clusters métalliques et de ligands organiques qui font l'objet de très nombreuses études, dans des champs d'applications très variés, qui vont de la catalyse au « drug delivery », en passant par le stockage de gaz et, plus récemment, en tant que senseurs biologiques. Les ligands organiques, qui les constituent, peuvent lorsqu'ils possèdent un point d'ancrage, comme des groupements amino, être fonctionnalisés grâce à des réactions chimiques. Les travaux présentés dans cette thèse reportent la fonctionnalisation de MOFs, via différentes stratégies, comme des greffages covalent et issues de la chimie de coordination, tel que le couplage peptidique ou encore la synthèse d'urée. Dans cette thèse, est notamment présentée une nouvelle méthode permettant de greffer très rapidement des peptides chiraux dans les nanopores des MOFs. Une large bibliothèque MOF-peptides a ainsi été obtenue et caractérisée. Ces nouveaux composés ont également été utilisés pour l'ancrage de complexes organométalliques dans les cavités des MOFs. Suivant un échange de ligands post-synthétique, il a aussi été possible d'intégrer un complexe organométallique photo-catalytique dans la structure d'un MOF, améliorant ainsi ses activités et sélectivités pour la photo-réduction de CO2. Enfin, les performances catalytiques de ces derniers matériaux MOFs se sont révélées supérieures aux versions homogènes des complexes, ce qui offre de nouvelles opportunités pour la catalyse fineMetal Organic Frameworks, MOFs, are porous crystalline solid based on metal clusters and organic ligands, investigated for numerous applications such as catalysis, drug delivery, gas storage and, more recently, biosensors. The work presented in this thesis focuses on functionalizing MOFs through different strategies, such as covalent grafting or surface coordination chemistry, through chemical reactions, such as peptide coupling or synthesis of urea. In particular, a new method to very quickly graft chiral peptides into the nanopores of MOFs is reported. A large library of MOF-peptides has thus been obtained and characterized. These novel compounds have also been used for grafting organometallics in the cavities of MOFs. Following a post-synthetic ligand exchange, it was also possible to integrate a photocatalytic complex in the structure of a MOF, improving its activities and selectivities for the photocatalytic CO2 reduction. In general, the catalytic performances of these materials were superior to those of their homogeneous counterparts, thus further expanding the potential of MOFs as well-defined heterogeneous catalysts for fine chemistry
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Vernekar, Amit A. "Bio-inspired Materials : Antioxidant and Phosphotriesterase Nanozymes." Thesis, 2014. http://hdl.handle.net/2005/3026.
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Bio-inspired or biomimetic chemistry deals with the replication of the nature’s fundamental processes, which can help in understanding the functioning of biological systems and develop novel applications. Although a large number of researchers worked towards the replication of natural synthetic pathways through biogenetic syntheses, enzyme mimicry by the small organic molecules and inorganic complexes emerged in leaps and bounds over the years. The development of biomimetic chemistry then continued in designing the molecules that can function like enzymes. And now, with the advent of nanotechnology, nanostructured materials have been shown to exhibit enzyme-like activities (nanozymes). Interestingly, the two distinct fields, biology and materials science, have been integrated to form an entirely new area of research that has captured a great attention. Along with the pronounced application of nanomaterials as drug delivery vehicles, anticancer agents, antimicrobials, etc., research is also focused on designing nanomaterials for the biomimetic applications.
The thesis consists of five chapters. The first chapter provides a general overview of the recently discovered nanozymes that mimic heme-peroxidase, oxidase, superoxide dismutase, catalase, haloperoxidase and phosphatase. This chapter also deals with the nanozymes’ application in sensing and immunoassay, and as antioxidants, neuroprotective agents. The factors affecting the nanozymes’ activity and the challenges associated with them is also covered in this chapter. Chapter 2 is divided into two parts and it deals with the biomimetic properties of graphene-based materials. In part A, the remarkable peroxynitrite (PN) reductase and isomerase activities of hemin-functionalized reduced graphene oxide (rGO) is discussed. In part B, the activity of graphene oxide (GO) as peroxide substrate for the glutathione peroxidase (GPx) enzyme is discussed. In chapter 3, the oxidant material, V2O5, is shown to exhibit significant GPx-like antioxidant activity in its nano-form. Chapter 4 deals with the oxidase-like activity of MnFe2O4 nanooctahedrons for the antibody-free detection of major oxidative stress biomarker, carbonylated proteins. In chapter 5, the phosphotriesterase mimetic role of vacancy engineered nanoceria is discussed. instead of H2O2 for glutathione peroxidase (GPx) enzyme. As partial reduction of GO was observed when treated with GPx enzyme due to the fact that large sheet-like structures cannot be accessible to the active site, we studied the reaction with some GPx mimetics (Fig. 2). Varying the concentration of cofactor glutathione (GSH) required for the reaction, GPx mimic, ditelluride, could accomplish the reduction of GO following Michaelis-Menten kinetics. As the structure of GO is elusive and under active investigation, our study highlights the presence of peroxide linkages as integral part of GO other than hydroxyl, epoxy and carboxylic groups. This study also highlights an important fact that the modification of GO by biologically relevant compounds such as redox proteins must be taken into account when using GO for biomedical applications because such modifications can alter the fundamental properties of GO.
Figure 2. The GO reductase and decarboxylase activities of GPx mimetic ditelluride compound, suggesting the presence of peroxide linkages on GO.
In chapter 3, we have discussed about the novel antioxidant nanozyme that combats oxidative stress. During our attempts in the investigation of antioxidant nanozymes, we surprisingly noticed that the oxidant material, V2O5, shows significant GPx-like antioxidant activity in its nano-form. The Vn readily internalize in the cells and exhibit remarkable protective effects when challenged against reactive oxygen species (ROS). Although Vn has been shown to protect cells from ROS-induced damage, cells treated with bulk V2O5 and few vanadium complexes resulted in generation of ROS and severe toxicity. Detailed investigation on the mechanism of this interesting phenomenon
Chapter 4 deals with the development of novel methodology for detection of biomarkers. Inspired by the use of antibodies and enzymes for detection of a specific antigen, we have shown for the first time that the nanozymes can entirely replace antibodies and enzymes in Enzyme-linked Immunosorbent Assays (ELISA). As a specific example, we focused on the antibody-free detection of chief oxidative stress biomarker, carbonylated proteins, as our target. To achieve this, we designed MnFe2O4 nanooctahedrons that can function as oxidase enzyme and form signaling point of detection. We functionalized MnFe2O4 nanooctahedrons with hydrazide terminating groups so that carbonylated proteins can be linked to nanozymes by hydrazone linkage (Fig. 4a). Treatment of various carbonylated proteins (hemoglobin (Hb), Myoglobin (Mb), Cytochrome c (Cyt c), RNase and BSA) coated in well plate with hydrazide-terminated MnFe2O4 nanooctahedrons and then with 3,3’,5,5’-tetramethylbenzidine substrate, resulted in instantaneous detection by well plate reader (Fig. 4b). Considering the challenges and difficulties associated with the conventional methods used to detect such modified proteins, this methodology opens up a new avenue for the simple, cost-effective, instantaneous and entirely antibody-free ELISA-type detection of carbonylated proteins. Our results provide a cumulative application of nanozymes’ technology in oxidative stress associated areas and pave a new way for direct early detection of post translational modification (PTM) related diseases.
Figure 4. a) Nanozyme linked to the carbonylated protein coated on a plate through hydrazone linkage. b) General bar diagram showing detection of oxidized (carbonylated) proteins by nanozymes.
Synopsis
Figure 5. a) A cartoon view of surface of ceria showing vacancy. b) Zoomed portion of high resolution transmission electron microscopic image showing few vacancies on the surface of nanoceria. c) Catalytic mechanism of detoxification of paraoxon at the defect site.
In the final chapter, chapter 5, we have discussed about the nanomaterial that can function as phosphotriesterase enzyme. Phosphotriesterase enzyme is a bacterial enzyme that is involved in the rapid hydrolysis of sarin gas-related deadly nerve agents such as paraoxon, parathion and malathion. When encountered with these orgnaophospatetriesters, living beings tend to undergo nerve shock to cause paralysis by inhibiting an extremely important enzyme called acetylcholine esterase. They are also known to cause severe oxidative stress problems and are associated with neurodegenerative disorders. Therefore, curbing the toxic effects and detoxification of these nerve agents is a world-wide concern and many research teams have focused their attention to address this important problem. Working on the development of nanozymes for important problems, we found that nanoceria, especially the vacancy engineered one (Fig. 5a,b), can serve as active mimic of phosphotriesterase enzyme in the presence of N-methylmorpholine (acting as a distal base histidine). Vacancy engineered nanoceria has been shown to catalyze the hydrolysis of high amounts of paraoxon quiet efficiently and within few minutes with very low activation energy and high kcat. Detailed mechanistic investigation revealed that the presence of both Ce(III) and Ce(IV) is very essential for detoxification activity (Fig. 5b). The vacancies on the surface of nanoceria, were the buried Ce(III) ions are directly exposed to the reaction environment, behave as hotspots or enzyme active sites for detoxification reaction (Fig. 5b).
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Aitken, Heather. "Tuning the Self Assembly of Bio-inspired Catalysts and Materials." Phd thesis, 2022. http://hdl.handle.net/1885/264166.
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With a view to designing selective bio-inspired catalysts, the following thesis seeks to understand and tune the self-assembly of bio-inspired and biological materials and catalysts. The first chapter introduces the concept of self-assembly and its importance in bio-inspired chemistry. In chapter 2, to highlight the role of self-assembly in biology, DNA G-quadruplex formation is simulated using molecular dynamics to determine the structural deformities caused by specific mutations of the human telomerase reverse transcriptase gene which are over-expressed in most cancers. In chapter 3, self-assembly of a model bio-inspired amphiphilic polymer is studied using experimental and computational chemistry techniques. The hydrophobicity and mechanical properties of this dynamic non- covalent material is tuned by altering the monomer ratio and swelling conditions. In chapter 4, the importance of weak non-covalent interactions in catalysing small molecule reactions and determining their selectivity is highlighted using quantum mechanics calculations. Finally in chapter 5, using what we have learned in chapters 2-4, we build a self-assembled enzyme mimic using amphiphilic macromolecules, for selective ester hydrolysis.
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LOUKA, ALEXANDRA. "Design of chimeric (metallo-) proteins for the development of novel bio-inspired materials." Doctoral thesis, 2016. http://hdl.handle.net/2158/1069123.
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Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. Two outstanding examples of biomineral morphogenesis are the formation of highly elaborate nano-patterned silica shells by diatoms, and the formation of HydroxyApatite (HA) in hard tissues of vertebrates. An interesting application of the biomineralization process is the enzyme immobilization. Enzymes are inherently “green” catalysts that can perform complex chemical tasks under mild conditions in a fully aqueous environment (i.e., under physiological conditions). Bio-minerals are hybrid materials consisting of organic and inorganic constituents. Understanding the molecular structure of the interface between organic and inorganic constituents of bio-minerals is a main goal in biomineralization research. The interactions between organic and inorganic components are assumed to be of key importance for the formation of the remarkable structures of biominerals as well as their outstanding materials properties. In this study, I have used bio-silica and HA as solid matrices to immobilize enzymes/proteins, to synthesize hybrid biomaterials for potential medical application.
Solid-state NMR spectroscopy is very well suited to investigate biomaterials, their organic-inorganic interface, and to obtain structural information on the immobilized proteins/enzymes and on the inorganic matrices.
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Yen-TingLiu and 劉嫣婷. "Employ Bio-Inspired Surface Modification to Enhance Biological Response of Dental Implant Materials." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/abjtp3.
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博士國立成功大學
材料科學及工程學系
102
Dental implant, a special biocompatible component serving with the rehabilitation of the damaged chewing apparatus due to loss of the natural teeth, is currently the most intensively developing field of dentistry. Today, the increasing demands from patients with missing teeth for masticatory function and aesthetic dissatisfaction of their replaced teeth to be restored and for shortening of the period of osseointegration of the implants. Zirconia and titanium have been widely used as a framework material in dental implants, due to their excellent mechanical properties and chemical stability. However, zirconia and titanium are categorized as bio-inert materials which make them difficult to achieve a chemical bond with living tissue and restricts their application in the field of biomedicine. Various forms of surface modification have been used to accelerate the initial osseointegration soon after implantation in order to improve the reactions of the tissue and shorten the healing period of the bone. In this study, a biologically inspired idea from mussels was used to establish a synthetic adhesive platform for medical-implant application. Moreover, three-dimensional structures with numerous craters were produced to mimic bone morphology and function in order to optimize the integration of the implant. In first part of this thesis, an easy, efficient, solvent-free process was proposed for the coating of DOPA film on a zirconia surface which was shown to increase the biocompatibility to osteoblasts. Specifically, the thickness of the coating and initial cell spreading ability were both enhanced by preparing samples at higher temperatures. Then, the study was subsequently related to the trace element strontium, which we did added into the DOPA polymerization process. Strontium has been attracting considerable attention for clinical applications to treat osteoporosis. The incorporation of strontium greatly increases osteoblast response, such as differentiation and mineralization in DOPA-coated zirconia. Interestingly, the level of DOPA is highly dependent on the strontium concentration, suggesting that strontium may promote DOPA polymerization. In the next part of this thesis, an organic-inorganic multilayer coating process was developed for the modification of titanium implants. A three-dimensional porous structure comprising strontium and micro-arc oxidized (MAO) titanium was covered with a film of DOPA to form a multilayer coating. The DOPA film facilitates the initial attachment and proliferation of cells. Cell differentiation is sequentially enhanced by the release of strontium from the coatings. Moreover, MAO process produced a much rougher surface with crater-like structures which provides early fixation and long-term mechanical stability. The results demonstrate the efficacy of the proposed coating process in enhancing the multi-biological function of implant surfaces to improve cellular characteristics. Moreover the surface properties were simply changed by adjusting the compositions of the electrolyte solutions that alters the local chemistry of the coatings and in so doing changes the biological properties of the MAO coating. A porous manganese-calcium-phosphate coating was prepared on titanium through MAO process. The manganese in electrolytes can be incorporated within MAO coatings in a dose dependent manner. Manganese concentration did not appear to have a significant effect on thickness, hydrophilicity, pore size, or overall porosity of the MAO coatings. However, the addition of manganese alters the local chemistry of the coatings and improve cell-mediated mineralization. All findings in this thesis indicated that combining the beneficial characteristics of both bio-inspired modifications shows considerable promise as a biomaterial for implants. These findings may give a new important insight into further advancing the research on exploring the impact of bio-inspired modifications on the degree of osseointegration.
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(8782580), Di Wang. "Mechanical behaviors of bio-inspired composite materials with functionally graded reinforcement orientation and architectural motifs." Thesis, 2020.
Find full textAbstract:
Naturally-occurring biological materials with stiff mineralized reinforcement embedded in a ductile matrix are commonly known to achieve excellent balance between stiffness, strength and ductility. Interestingly, nature offers a broad diversity of architectural motifs, exemplify the multitude of ways in which exceptional mechanical properties can be achieved. Such diversity is the source of bio-inspiration and its translation to synthetic material systems. In particular, the helicoid and the “brick and mortar” architectured materials are two key architectural motifs we are going to study and to synthesize new bio-inspired materials.
Due to geometry mismatch(misorientation) and incompatibilities of mechanical properties between fiber and matrix materials, it is acknowledged that misoriented stiff fibers would rotate in compliant matrix beneath uniaxial deformation. However, the role of fiber reorientation inside the flexible matrix of helicoid composites on their mechanical behaviors have not yet been extensively investigated. In the present project, fiber reorientation values of single misoriented laminae, mono-balanced laminates and helicoid architectures under uniaxial tensile are calculated and compared. In the present work, we introduce a Discontinuous Fiber Helicoid (DFH) composite inspired by both the helicoid microstructure in the cuticle of mantis shrimp and the nacreous architecture of the red abalone shell. We employ 3D printed specimens, analytical models and finite element models to analyze and quantify in-plane fiber reorientation in helicoid architectures with different geometrical features. We also introduce additional architectures, i.e., single unidirectional lamina and mono-balanced architectures, for comparison purposes. Compared with associated mono-balanced architectures, helicoid architectures exhibit less fiber reorientation values and lower values of strain stiffening. The explanation for this difference is addressed in terms of the measured in-plane deformation, due to uniaxial tensile of the laminae, correlated to lamina misorientation with respect to the loading direction and lay-up sequence.
In addition to fiber, rod-like, reinforced laminate, platelet reinforced composite materials, “brick and mortar” architectures, are going to be discussed as well, since it can provide in-plane isotropic behavior on elastic modulus that helicoid architecture can offer as well, but with different geometries of reinforcement. Previous “brick and mortar” models available in the literature have provided insightful information on how these structures promote certain mechanisms that lead to significant improvement in toughness without sacrificing strength. In this work, we present a detailed comparative analysis that looks at the three-dimensional geometries of the platelet-like and rod-like structures. However, most of these previous analyses have been focused on two-dimensional representations. We 3D print and test rod-like and tablet-like architectures and analyze the results employing a computational and analytical micromechanical model under a dimensional analysis framework. In particular, we focus on the stiffness, strength and toughness of the resulting structures. It is revealed that besides volume fraction and aspect ratio of reinforcement, the effective shear and tension area in the matrix governs the mechanical behavior as well. In turns, this leads to the conclusion that rod-like microstructures exhibit better performance than tablet-like microstructures when the architecture is subjected to uniaxial load. However, rod-like microstructures tend to be much weaker and brittle in the transverse direction. On the other hand, tablet-like architectures tend to be a much better choice for situations where biaxial load is expected.
Through varying the geometry of reinforcement and changing the orientation of reinforcement, different architectural motifs can promote in-plane mechanical properties, such as strain stiffening under uniaxial tensile, strength and toughness under biaxial tensile loading. On the other hand, the various out-of-plane orientation of the reinforcement leads to functionally graded effective indentation stiffness. The external layer of nacre shell is composed of calcite prisms with graded orientation from surface to interior. This orientation gradient leads to functionally graded Young’s modulus, which is confirmed to have higher fracture resistance than homogenous materials under mode I fracture loading act.
Similar as graded prism orientation in calcite layer of nacre, the helicoid architecture found in nature exhibits gradients on geometrical parameters as well. The pitch distance of helicoid architecture is found to be functionally graded through the thickness of biological materials, including the dactyl club of mantis shrimp and the fish scale of coelacanth. This can be partially explained by the long-term evolution and selection of living organisms to create high performance biological materials from limited physical, chemical and geometrical elements. This naturally “design” procedure can provide us a spectrum of design motifs on architectural materials.
In the present work, linear gradient on pitch distance of helicoid architectures, denoted by functionally graded helicoid (FGH), is chose to be the initial pathway to understand the functionality of graded pitch distance, associated with changing pitch angle. Three-point bending on short beam and low-velocity impact tests are employed in FEA to analyze the mechanical properties of composite materials simultaneously. Both static(three-point bending) and dynamic(low-velocity impact) tests reveal that FGH with pitch angle increasing from surface to interior can provide multiple superior properties at the same time, such as peak load and toughness, while the helicoid architectures with constant pitch angle can only provide one competitive property at one time. Specifically, helicoid architectures with smaller pitch angle, such as 15-degree, show higher values on toughness, but less competitive peak load under static three-point bending loading condition, while helicoid architectures with middle pitch angle, larger than or equal to 22.5-degree and smaller than 45-degree, exhibit less value of toughness, but higher peak load. The explanation on this trend and the benefits of FGH is addressed by analyzing the transverse shear stresses distribution through the thickness in FEA, combined with analytical prediction. In low-velocity impact tests, the projected delamination area of helicoid architectures is observed to increase when the pitch angle is decreasing. Besides, laminates with specific pitch angles, such as 45-degree, classical quasi-isotropic laminate, 60-degree, specific angle ply, and 90-degree, cross-ply, are designed to compare with helicoid architectures and FGH.
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Mueller, Lena. "Chemical synthesis of switchable peptide-based nanopores: from ion channels to bio-inspired materials." Phd thesis, 2019. https://tuprints.ulb.tu-darmstadt.de/11495/1/200419_Mueller_Dissertation.pdf.
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The generation of different types of peptide-based nanopores is elucidated in this work. First, biological nanopores are investigated. Ion channels and pore-forming proteins represent an ultra-selective and ultra-sensitive category of nanopores. Eukaryotic potassium channels are structures of enormous size while prokaryotic potassium channels are comparable in their overall gating behavior but some are extremely reduced in their size. Within this work, the total chemical synthesis of the viral potassium channel KcvNTS is shown using Solid Phase Peptide Synthesis (SPPS) and Native Chemical Ligation (NCL) towards product formation. The main attention is on overcoming the challenging key steps including the substantial insolubility of the extensively hydrophobic fragments. Secondly, hybrid nanopores are generated. Nanopores composed of solid-state materials can be used as a robust and stable scaffold to integrate a selective and sensitive peptide moiety to generate a hybrid nanopore for a sensing application. In this work, the immobilization of the Amino Terminal Cu(II)- and Ni(II) binding motif (ATCUN) to conically shaped PET-based solid state nanopores is undertaken. The generated sensor is tuned (pH 6.5) to only bind Cu(II) leading to the design of a selective and sensitive Cu(II)-sensor (limit of detection in solution 13.5 nM using fluorescence titration; hybrid system in fM range using I-V measurements). Furthermore, the motif is investigated substantially regarding the mandatory histidine moiety. Mutants are designed and examined towards their binding behavior. Additionally, the DNA scission ability of the ATCUN motif and its mutants is investigated towards several plasmids paving the way for the design of a sequencing device using the presented polymer-based hybrid nanopore system.
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Thomas, Ananya. "Thermal and calorimetric evaluations of some bio-inspired fire-resistant coatings for ligno-cellulosic materials." Thesis, 2020. https://vuir.vu.edu.au/40844/.
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Through the current project, we have investigated the passive fire protection efficiency of some bio-inspired substrates, which included: β-cyclodextrin, dextran, potato starch, agar agar, tamarind, chitosan, rice bran and fish gelatin. In an attempt to enhance the passive fire protection attributes of these substrates, we prepared formulations of these with both inorganic and organic compounds, the latter included some phosphorus-containing compounds with the phosphorus atom in different chemical environments and oxidation states. Here we have also explored both the reactive and additive strategies. The degrees of functionalization were primarily gauged from inductively-coupled plasma/optical emission spectroscopy (ICP-OES), 31P solid-state Nuclear Magnetic Resonance Spectroscopy (NMR). We also chose several thermal and calorimetric techniques for evaluating the efficacies of such formulations, such as: thermo-gravimetric analysis (TGA), pyrolysis combustion flow calorimetry (PCFC), a proprietary ignition propensity test and cone calorimetry. In addition, with a view to deciphering the elements of condensed phase mechanism, we carried out an estimation of the extents of phosphorus retention in the char residues (using ICP-OES) and chemical nature of the char residues (via solid-state NMR and Raman spectroscopies) that were obtained through the cone calorimetric runs. The unmodified counterparts were also subjected to the same set of analyses with a view to serving as controls. We also endeavoured to analyse the gaseous volatile fragments emanating from some of the additives using, either by employing gas chromatography/mass spectrometry (GC/MS), or pyrolysis-GC/MS, technique.
Phosphorus analyses, primarily, through ICP-OES on the recovered samples showed different degrees of incorporation. Such observations were verified through solid-state 31P NMR spectroscopy. The thermograms of the modified substrates were noticeably different from the unmodified counterparts, both in terms of the general profiles and the amounts of char residues produced. Such observations correlated well with the relevant parameters obtained through the PCFC runs. Furthermore, we have carried out a detailed kinetic analyses of the thermograms of the unmodified substrates, obtained at different heating rates, using the Flynn Wall Ozawa (FWO) method, and through a proprietary software developed by our research group (SB method). We have also endeavoured to seek correlations, if any, among the various empirical parameters that were collated through the different test methods.
Overall, the modified systems containing phosphorus were found to be less combustible than the parent substrates, and thus can be considered as promising base matrices for environmentally-benign fire resistant coatings. With a view to understanding the overall flammability profiles, optionally, in some of the formulations, initially we screened them through an ignitability propensity test that was developed in our laboratories. This was followed by cone calorimetric measurements on Radiata Pine plaques, particularly, coated with potato starch, chitosan, chitin, rice bran and fish gelatin. The results from the cone tests indicated that formulations based on fish gelatin endowed with the best fire protection property, followed by chitosan, whereas potato starch and rice bran seem to be ineffective as fire proofing agents.
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Bartlett, Michael David. "Scaling reversible adhesion in synthetic and biological systems." 2013. https://scholarworks.umass.edu/dissertations/AAI3603051.
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Geckos and other insects have fascinated scientists and casual observers with their ability to effortlessly climb up walls and across ceilings. This capability has inspired high capacity, easy release synthetic adhesives, which have focused on mimicking the fibrillar features found on the foot pads of these climbing organisms. However, without a fundamental framework that connects biological and synthetic adhesives from nanoscopic to macroscopic features, synthetic mimics have failed to perform favorably at large contact areas. In this thesis, we present a scaling approach which leads to an understanding of reversible adhesion in both synthetic and biological systems over multiple length scales. We identify, under various loading scenarios, how geometry and material properties control adhesion, and we apply this understanding to the development of high capacity, easy release synthetic adhesive materials at macroscopic size scales. Starting from basic fracture mechanics, our generalized scaling theory reveals that the ratio of contact area to compliance in the loading direction, A/C, is the governing scaling parameter for the force capacity of reversible adhesive interfaces. This scaling theory is verified experimentally in both synthetic and biological adhesive systems, over many orders of magnitude in size and adhesive force capacity (Chapter 2). This understanding is applied to the development of gecko-like adhesive pads, consisting of stiff, draping fabrics incorporated with thin elastomeric layers, which at macroscopic sizes (contact areas of 100 cm2) exhibit force capacities on the order of 3000 N. Significantly, this adhesive pad is non-patterned and completely smooth, demonstrating that fibrillar features are not necessary to achieve high capacity, easy release adhesion at macroscopic sizes and emphasizing the importance of subsurface anatomy in biological adhesive systems (Chapter 2, Chapter 3). We further extend the utility of the scaling theory under shear (Chapter 4) and normal (Chapter 5) loading conditions and develop simple expressions for patterned and non-patterned interfaces which describe experimental force capacity data as a function of geometric parameters such as contact area, aspect ratio, and contact radius. These studies provide guidance for the precise control of adhesion with enables the development of a simple transfer printing technique controlled by geometric confinement (Chapter 6). Force capacity data from each chapter, along with various literature data are collapsed onto a master plot described by the A/C scaling parameter, with agreement over 15 orders of magnitude in adhesive force capacity for synthetic and biological adhesives, demonstrating the generality and robustness of the scaling theory (Chapter 7).
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(8586705), Amelia A. Putnam. "Designing Functional Biomimetic Adhesives: Bringing Nature's Methods to Market." Thesis, 2020.
Find full textAbstract:
An estimated 20 million tons of adhesives are used globally each year, and the amount is continually increasing. Glues are used in nearly every economic sector but are largely consumed by key external drivers of the industry including construction and transportation equipment to replace mechanical fasteners. Many of these applications require specific functionality, like moisture resistance, desirable mechanical properties, or low toxicity. However, specific features usually occur at the expense of adhesive strength, and there is no “one size fits all” adhesive. The search for more practical and stronger glues has contributed to the development of biomimetic adhesives. Marine mussels and other sea creatures produce biological adhesives that stick well underwater. By using nature as an inspiration for better glues, we can combine stronger bonding and additional functionality into one adhesive system. Introducing the same catechol moiety used by marine organisms into synthetic polymers has allowed us to produce adhesives stronger than commercial glues in both dry and wet environments.
While many of these biomimetic polymer adhesives have been prepared, few have made it to market. Here, multiple biomimetic polymer adhesives are studied and optimized for different applications to provide the next step towards commercialization. The adhesives were tailored for use on different surfaces and conditions through formulation or polymer design. Structure-function studies have showed how surface energy influences optimal adhesion with catechol-containing polymers for applications in bonding dissimilar substrates while maintaining desired mechanical properties. Multiple adhesive systems were studied in mice to assess toxicity and determine viability as potential surgical glues. Underwater formulation and application methods were also pursued to improve product development strategies for offering a competitive advantage as an underwater glue. In addition to these practical-use modifications of the adhesives, industry research and market analysis was conducted to provide insight into further applications to pursue. A cost analysis led to creating new synthetic strategies for cost-reduction and scale-up, both of which are essential in the commercialization of a catechol-containing polymer adhesive.
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Abreu, Beatriz Martins de. "Bio-inspired nanocellulose composites systems with structural coloration as optical security features." Master's thesis, 2019. http://hdl.handle.net/10362/91293.
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TOTO, ELISA. "Functional nanocomposites based on graphene/DNA interface: Towards a bio-inspired sensing of UV radiation effects." Doctoral thesis, 2020. http://hdl.handle.net/11573/1366317.
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Ultraviolet (UV) radiation naturally characterizes the Earth environment and the outer space, representing one of the most hazardous agents for human health and for the useful lifetime of organic materials. The possibility to develop a UV-detecting system able to ensure a good sensitivity and stability during measurements, and possessing at the same time low weight and real-time response, represents a fascinating challenge towards new technological advances in the field of radiation sensitive materials. This thesis is focused on the design, preparation and testing of bio-inspired UV sensitive nanocomposites based on graphene/DNA interface. The sensing principle of such nanocomposites relies on the highly conductive nature of graphene combined with the chemical sensitivity of DNA strands to UV radiation, particularly in the UV-C band (100 nm to 280 nm). The engineering of these bio-hybrid nanomaterials in the form of thin films or miniaturized materials would be desirable to overcome traditional problems that affect space mission equipment, such as onboard encumbrance, or that can limit their use on terrestrial environments involving a daily use of UV radiation, such as sterilization plants. To this aim, the UV sensitive graphene/DNA filler was integrated in different polymer matrices based on poly(3,4-ethylenedioxythio-phene):poly(styrenesulfonate) (PEDOT:PSS) or polydimethylsiloxane (PDMS), obtaining stiff and flexible UV sensitive materials, respectively. The UV response was investigated using several techniques, including electrical impedance spectroscopy, Raman microscopy, optical contact angle, electrical tomography resistance. In addition, differential scanning calorimetry was used to analyze the curing behavior of the PDMS-based prepolymers and the thermal stability of the related nanocomposites. Results revealed that the bio-hybrid nanocomposites with graphene/DNA filler show a specific UV response, in particular in terms of electrical conductivity variations, and therefore these materials have the potential to be applied in UV monitoring systems, with the additional advantages of real-time response, low weight/mass and reduced size
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"Thermal Performance of PNIPAm as an Evaporative Cooling Medium within a Ventilated Wall Cavity." Master's thesis, 2018. http://hdl.handle.net/2286/R.I.50596.
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abstract: Learning from the anatomy of leaves, a new approach to bio-inspired passive evaporative cooling is presented that utilizes the temperature-responsive properties of PNIPAm hydrogels. Specifically, an experimental evaporation rate from the polymer, PNIPAm, is determined within an environmental chamber, which is programmed to simulate temperature and humidity conditions common in Phoenix, Arizona in the summer. This evaporation rate is then used to determine the theoretical heat transfer through a layer of PNIPAm that is attached to an exterior wall of a building within a ventilated cavity in Phoenix. The evaporation of water to the air gap from the polymer layer absorbs heat that could otherwise be conducted to the interior space of the building and then dispels it as a vapor away from the building. The results indicate that the addition of the PNIPAm layer removes all heat radiated from the exterior cladding, indicating that it could significantly reduce the demand for air conditioning at the interior side of the wall to which it is attached.Dissertation/Thesis
Masters Thesis Built Environment 2018