Across species, bats exhibit wildly disparate differences in their noseleaf and pinnae shapes. Within Rhinolophid and Hipposiderid families, bats actively deform their pinnae and noseleaf during biosonar operation. Both the pinnae and noseleaf act as acoustic baffles which interact with the outgoing and incoming sound; thus, they form an important interface between the bat and its environment. Beampatterns describe this interface as joint time-frequency transfer functions which vary across spatial direction. This dissertation considers bat biosonar shape diversity and shape dynamics manifest as beampatterns. In the first part, the seemingly disparate set of functional properties resulting from diverse pinnae and noseleaf shape adaptations are considered. The question posed in this part is as follows: (i) what are the common properties between species beampatterns? and (ii) how are beampatterns aligned to a common direction for meaningful analysis? Hence, a quantitative interspecific analysis of the beampattern biodiversity was taken wherein: (i) unit[267]{} different pinnae and noseleaf beampatterns were rotationally aligned to a common direction and (ii) decomposed using principal component analysis, PCA. The first three principal components termed eigenbeams affect beamwidth around the single lobe, symmetric mean beampattern. Dynamic shape adaptations to the pinnae and noseleaf of the greater horseshoe bat (textit{Rhinolophus ferrumequinum}) are also considered. However, the underlying dynamic sensing principles in use are not clear. Hence, this work developed a biomimetic substrate to explore the emission and reception dynamics of the horseshoe bat as a sonar device. The question posed in this part was as follows: how do local features on the noseleaf and pinnae interact individually and when combined together to generate peak dynamic change to the incoming sonar information? Flexible noseleaf and pinnae baffles with different combinations of local shape features were developed. These baffles were then mounted to platforms to biomimetically actuate the noseleaf and pinnae during pulse emission and reception. Motions of the baffle surfaces were synchronized to the incoming and outgoing sonar waveform, and the time-frequency properties of the emission and reception baffles were characterized across spatial direction. Different feature combinations of the noseleaf and pinnae local shape features were ranked for overall dynamic effect. / Ph. D.

This research focuses on the development of a biomimetic photosynthetic energy transduction system which can convert the light energy into a transmembrane potential gradient. This potential gradient provides energy for transmembrane proton pumping, which can be detected potentiometrically and/or spectroscopically through the changes in the optical and electrochemical properties of conductive polymers that supports a lipid bilayer. To achieve this goal, there were two major objectives: 1) Development of a pH sensitive, conducting polymer-based thin film platform as a suitable interface to couple a planar lipid membrane to an ITO electrode and as a pH transducer to detect transmembrane proton motive force (pmf). 2) Construction of an ionophore-aided, transmembrane proton transport model system in a planar supported lipid membrane.Toward the first objective, two different approaches have been used: a) to create a conducting polymer thin film, composed of alternating layers of poly(aniline) PANI and poly(acrylic acid) PAA on an ITO-coated, planar glass substrate. The electroactivity in a neutral environment and the pH dependence of the self-assembled (SA) PANI/PAA multilayer thin films were demonstrated both electrochemically and spectroscopically. Additionally, (PANI/PAA)2 films were shown to be compatible with PSLB. The polymer cushion supported lipid bilayer was found to be highly impermeable to protons, as demonstrated by the blockage of the pH response of the PANI film underneath the lipid membrane. b) to create a PANI nanowire/sol-gel hybrid thin film on an ITO-coated, planar glass substrate. Electrochemical growth of PANI nanowires through a porous sol-gel matrix was demonstrated. The PANI nanowire/sol-gel hybrid thin film with a sol-gel capping layer was found to respond to pH both potentiometrically and spectroscopically and a uniform lipid membrane was formed on the capping layer.To achieve the second objective, a ΔpH-driven transmembrane proton transport model system supported by a PANI nanowire doped sol-gel/ITO substrate with a sol-gel capping layer was developed. Ionophore valinomycin and CCCP were incorporated into the planar supported lipid bilayer (PSLB). Driven by a transmembrane pH gradient, an enhanced rate of proton transport with a proton permeability ca. 3 orders of magnitude higher than that of the lipid membrane without ionophores was demonstrated.

Cardiovascular disease is the leading cause of death worldwide. Due to the extremely low natural regeneration rate of heart muscle, development of new therapeutics directed towards heart repair is challenging. A potential approach to regenerate damaged heart is offered by cardiac tissue engineering. Specifically, it aims at engineering cardiac muscle in vitro and implanting it into the site of injury so that it can be integrated into the host tissue and restore the heart’s function. To ensure the effectiveness of this technique, the engineered tissue needs to recapitulate structural and functional properties of the native myocardium. Myocardium consists of laminar sheets of uniaxially aligned cardiac muscle cells (cardiomyocytes) wrapped around the heart. Therefore, achieving high cardiomyocyte alignment in engineered muscle is crucial. In this study we aimed at stimulating cardiomyocyte alignment by mimicking their niche in the embryonic heart. We hypothesized that recapitulating the extracellular cues that guide myocardial development in the embryo can guide cardiac tissue organization in vitro. To test this hypothesis, we imaged the structure of fibronectin – the most abundant protein in embryonic heart’s extracellular matrix (ECM) – and derived a 2D pattern from it that was then microcontact printed onto a substrate to guide cell alignment. We compared chick cardiomyocyte alignment on the biomimetic pattern and line patterns that have been extensively studied in the past. Results revealed a unique cell density-dependent response of cardiomyocytes to the biomimetic pattern that allowed us to elucidate the role of cell-cell and cell-ECM interactions in cardiomyocyte alignment on fibronectin patterns by looking at the effect of local pattern features on alignment and inhibiting N-cadherin-based cell-cell junctions. Further, to engineer more clinically relevant tissues, we differentiated human induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs) into cardiomyocytes and seeded them onto the fibronectin patterns. Cardiac tissues produced with these cells showed significant differences compared to the chick tissues due to their immature phenotype. We showed that co-culture with cardiac fibroblasts (CFBs) as well as maturation of iPSC-derived cardiomyocytes (iPSC-CMs) increased tissue alignment, indicating the important role of both of these factors in developing novel methods to engineer functional cardiac tissues.

This project investigates the experience of physiological discomfort during travel through an urban environment such as London or New York in winter. The over and underground networks that lace a current metropolis, form vital passages that lead the traveller though a multitude of spaces each defined by unique temperature, humidity and activity level. It is impossible to predict possible eventualities and consequently accommodate in a selection of clothing to ensure physiological comfort. Modular clothing assemblies are currently employed for the management of physiological comfort to adjust the insulation and ventilation properties of a clothing system and rely on combinations of behavioural methods and textile properties. This method is compromised by factors such as limited availability of space and wearer’s ability to detect and respond to the onset of discomfort sensations. Current smart systems rely on temperature as a stimulus for actuation. Experimental work suggests that humidity is a more suitable trigger. Botanical mechanisms that employ hygroscopic expansion/contraction for seed and spore deployment were identified as paradigms for the development of a smart textile system. Biomimetic analysis of these natural mechanisms inspired the design of a textile prototype able to adapt its water vapour resistance in response to humidity changes in the microclimate of the clothing system. The resulting structure decreases its permeability to air by 20% gradually as relative humidity increases from 60% to 90%.

Mobile robots for rough terrain are of interest to researchers as their range of possible uses is large, including exploration activities for inhospitable areas on Earth and on other planets and bodies in the solar system, searching in disaster sites for survivors, and performing surveillance for military applications. Nature generally achieves land movement by walking using legs, but additional modes such as climbing, jumping and rolling are all produced from legs as well. Robotics tends not to use this integrated approach and adds additional mechanisms to achieve additional movements. The spherical device described within this thesis, called Jollbot, integrated a rolling motion for faster movement over smoother terrain, with a jumping movement for rougher environments. Jollbot was developed over three prototypes. The first achieved pause-and-leap style jumps by slowly storing strain energy within the metal elements of a spherical structure using an internal mechanism to deform the sphere. A jump was produced when this stored energy was rapidly released. The second prototype achieved greater jump heights using a similar structure, and added direction control to each jump by moving its centre of gravity around the polar axis of the sphere. The final prototype successfully combined rolling (at a speed of 0.7 m/s, up 4° slopes, and over 44 mm obstacles) and jumping (0.5 m cleared height), both with direction control, using a 0.6 m spherical spring steel structure. Rolling was achieved by moving the centre of gravity outside of the sphere’s contact area with the ground. Jumping was achieved by deflecting the sphere in a similar method to the first and second prototypes, but through a larger percentage deflection. An evaluation of existing rough terrain robots is made possible through the development of a five-step scoring system that produces a single numerical performance score. The system is used to evaluate the performance of Jollbot.

Published Content: Jeedimalla, N.; Jacquet, C.; Bahneva, D.; Youte Tendoung, J.-J.; Roche, S. P. J. Org. Chem. 2018, 83, 12357. The present thesis will be focused on the study of House-Meinwald Rearrangement (HMR) reactions for the congested trisubstituted spiro-epoxide molecules. Including their regio-selective, chemo-selective, enantio- selective selective and stereo-selectivity’s will be discussed in detailed by the mechanistic study approach of HMR reaction of trisubstituted spiro-epoxides. Chapter 1 will present the efforts towards the biomimetic total synthesis of meroterpenoid natural product (+)-liphagal, which possess a recognizable biological activity. The shortcomings associated with its stereochemical assignment, and also the revision of stereochemical assignment of siphonodictyal B, through which the biosynthesis of (+)-liphagal was proposed were discussed. Chapter 2 will focus on the study of regio and chemoselective HMR reaction. In addition, a three-step sequence for the synthesis of α-arylated cyclohexanones and the most challenging cycloheptanones is reported. First, an efficient one-pot synthesis of β, β’-disubstituted benzylidene cycloalkanes using the palladium-catalyzed Barluenga reaction from readily available feedstock chemicals is described. Second, an epoxidation followed by the HMR of spiro-epoxides is reported to produce a number of α -arylated cycloalkanones upon the ring expansion. Reactions catalyzed by bismuth triflate underwent quasi-exclusively ring expansion for all substrates (electronically poor and rich), demonstrating the difficulty to achieve the ring enlargement for electron deficient spiro-epoxides. On the other hand, via catalysis with aluminium trichloride the rearrangement proceeded typically in high yields and with remarkable regioselectivity. In this case, a switch of regioselectivity was achieved for spiro-epoxides with electron-withdrawing substituents which enabled this method to be successfully extended to some chemo specific arene shifts and it can also synthesize aldehydes derivatives bearing a α-quaternary carbon. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Many different experimental approaches were attempted to achieve carbon-carbon bond formation by nucleic acid template-directed reactions and ribozyme catalysis as potential lipid synthesizing machineries in the RNA world. A novel biomimetic condition for decarboxylative Claisen condensation in polyketide biosynthesis was discovered. The reaction of a malonic acid half oxyester with a Nhydroxysuccinmidyl ester forming reagent resulted in self-condensation to provide the corresponding 1,3-acetonedicarboxylic acid diester in the absence of a divalent metal chelator or a coordinating solvent. The decarboxylative Claisen condensation of malonyl adenosine using a poly-U template in solution or with immobilized poly-U was attempted. Various analytical methods demonstrated that malonyl adenosine underwent an exclusive hydrolysis reaction instead of condensation in the given conditions. Similar results were observed for the reaction of malonyl-CoA with acetyl-CoA on poly-U templates. No evidence for the decarboxylative Claisen condensation was observed by a DNA-templated system although a double helical structure of DNA duplex was proven to facilitate a bimolecular reaction by offering a favorable proximity effect. Therefore, it seems that the unsuccessful condensation resulted not from the bad template effect but from the intrinsic properties of the decarboxylative Claisen condensation reaction itself. Two tRNA molecules loaded with a malonic acid were prepared by ligation of truncated tRNAs with malonylated dinucletides. Our initial attempts to probe carbon-carbon bond formation by subjecting malonylated tRNAs to the in vitro translational machinery were not successful. Novel carbon isosteres of α-amino acids are suggested as a potential source of a more stable and reactive carbanion for future experiments. Isoprenoid conjugates of nucleoside 5??-diphosphates, which were proposed as either an initiator nucleotide or substrate molecule for in vitro selection of prenyl-transferase ribozyme were prepared by one step nucleophilic displacement reactions. A random DNA pool was constructed for selection of a ketosynthase ribozyme. A substrate bearing a biotin tag was prepared by one-step conjugation. Hig-tagged T7 RNA polymerase was expressed and purified for a large scale transcription reaction. In vitro transcription of the random DNA pool with a 5??-thiol modified GMP analogue as an initiator nucleotide produced a thiol-modified random RNA library.

Recent studies have suggested that minimal actomyosin systems have the intrinsic property to oscillate whensubjected to an elastic load. A similar situation can be found in various biological systems, leading, both in-vivoand in-vitro, to spontaneous oscillations. In particular, muscular systems as well as mechanosensitive hair-cellbundles in the inner ear have been shown to oscillate spontaneously as the result of active force production by anacto-myosin protein complex. We attempt to shed light on the mechanism behind the oscillatory activity of theacto-myosin system, in particular by determining the parameters that control the frequency and amplitude ofoscillation. The stiffness of the system, the total force developed by the motors and the type of motors have beenproposed as being influential in this respect. To investigate this effect, we make use of a modified motility assayconsisting of a motor-driven stiff polarized actin bundle subjected to an elastic load provided by opticaltweezers. During the course of this work, we also characterized auto-assembled magnetic bead columns andassessed their viability as molecular force sensors to study the oscillations. The fact that they can easily beorganized into large arrays makes them interesting as potential 'high-throughput' force sensors

Pressure sensitive adhesive surfaces are often inspired by nature. Miming the toe-surface of gecko, engineered surfaces made of thousands of micro-pillars show promising adhesive properties. This surfaces, covered with cylindrical pillars arranged into a pattern have adhesive properties greatly dependent on the geometrical characteristics. In this thesis, have been studied successively two models of micro-patterned surfaces, one two-dimensional, the other in three-dimensional using a FEM tool. Varying geometry parameters, has been determined optimal geometries to improve adhesive strength on these biomimetic, micropatterned surfaces. This study concludes to the non-adaptability of one-level scale micropatterned surface to large area of adhesion, to the strong advantage from the point of adhesion per contact area for high aspect ratio at each level of the geometry and study the opportunity of hierarchical structures. Some further suggestions of improvements to adhesion properties are discussed in the final chapter.

An estimated 200,000 injuries to the anterior cruciate ligament (ACL) occur annually in the United States, with approximately 100,000 total ACL reconstructions performed each year. Due to inherent limitations with existing ACL reconstruction strategies, the development of tissue engineered ligaments is a key area of musculoskeletal research. Although great strides have been made in the scaffold design, current strategies are limited by the inability to replicate the mechanical behavior of native ligament tissue with synthetic polyesters or natural polymers. Poly(ester urethane)s have recently been investigated as possible scaffold materials because of their established biocompatibility, excellent mechanical properties, and exceptionally tunable structure. However, non-specific degradation makes it difficult to tailor polyurethane structure to complement ligament regeneration. In contrast, a biomaterial that features system-responsive degradation would integrate with native ligament remodeling and thus provide effective load transfer to newly formed tissue that is necessary to restore mechanical integrity. In this study, enzyme-labile peptide sequences were conjugated to ether-based polyols to form collagen-mimetic soft segments that feature cell-responsive degradation. Synthetic routes were first developed to functionalize these polyols with favorable end groups for peptide coupling. Upon successful conjugation, biodegradable soft segments were then incorporated into the structure of linear polyurea elastomers. By varying soft segment chemistry, soft segment molecular weight, and the hard to soft segment ratio, a library of cell-responsive, biodegradable polyureas was developed. This library can then be used to elucidate key structure-property relationships necessary to complement neotissue formation. Overall, synthesis of a novel biomaterial that combines the strength and tunability of synthetic elastomers with cell-responsive degradation will assist in the development of an improved tissue engineered graft for ACL reconstruction.