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In this work, we were motivated to develop novel devices for water harvesting inspired by natural trees, and to understand their collection efficiency and working principles. We accomplished that with scale-model and large-scale fog harps, floating leaves, and synthetic trees. Fluids mechanics, physics, and thermodynamics were applied to solve the problems and rationalize the results. Redwood-inspired fog harps were designed with stainless steel vertical wires, using 3D-printing and laser-cutting techniques. Fog harps always harvested more water than any of the meshes, tested both under heavy fog and light fog conditions. The aerodynamic efficiency, deposition efficiency, and sliding efficiency were calculated to compare the fog harvesting performance. These findings provide insight into the new design of fog harvesters with high-efficiency fog harvesting performance, and future development of large fog harps, applied into regions even with light fog conditions, as an economically viable means. synthetic trees were fabricated with a nanoporous ceramic disk and silicone tubes. This tree system was tested in an environmental chamber (6 cm short trees) or a plant growth chamber (3m tall trees), both with controlled ambient humidities. The system pressure was calculated with Darcy's equation, Poiseuille equation and Laplace equation. The stable transpiration can happen to any scalable tree, which pumps water up an array of large tubes. Our synthetic trees, like natural trees, have the ability to lift water across a wide range of water temperatures and ambient humidities. They can be used as the large-scale evaporation-driven hydraulic pump, for example, pumped storage hydropower, filtration, underground water extraction. / Doctor of Philosophy / The purpose of this work is to investigate and characterize novel techniques for water harvesting that are inspired by natural trees. We are interested in two modes of water harvesting in particular: fog harps and synthetic trees. Fog harps were comprised of only vertical wires, inspired by the parallel structures of redwoods, which can capture and shed off fog droplets efficiently. Fog harps harvested more water than the traditional mesh nets, both under heavy fog and light fog conditions. Redwood-inspired fog harps have the high-efficient fog harvesting performance. They can be set up at coastal deserts to collect water from fog, where there is scarce rainfall but plenty of fog, like Chile, Peru and South Africa. Synthetic trees were designed with nanoporous disk (leaf) and tubes (xylem conduits), inspired by the transpiration process in natural trees. This transpiration-powered pump can lift water against the gravity at large scales, driven by the water evaporating from the nanopores. They can be used as the large-scale evaporation-driven hydraulic pump, for example, pumped storage hydropower, filtration, underground water extraction.

Fog harvesting is emerging as a promising means to ease the water shortage crisis in arid regions of the world with ample fog. The current state-of-the-art for fog harvesting is mesh netting, which is accessible yet struggles from a dual constraint: a course mesh lets most microscopic fog droplets pass through it, while a fine mesh clogs. In recent years, fog harps have been gaining attention as a superior alternative to meshes, bypassing these inherent constraints. In this work, we expand upon previous fog harp research with a focus on optimization. First, we analyze wire tangling in a harp due to capillary forces, resulting in a mathematical model that is able to predict when wire tangling will occur. Second, we systematically vary three key parameters of a fog harp (wire material, center-to-center wire pitch, and wire length), arriving at an optimal combination. Finally, we develop a numerical model to describe the dynamics of a fog droplet sliding down a harp wire while coalescing with others littered along it. By applying all knowledge acquired through these studies, the next generation of fog harps will push the performance ceiling of practical fog harvesters higher than ever. / Master of Science / The human population continues to grow, and with it the demand for fresh water. This need has caused many to turn to unconventional sources of water, including fog (the suspension of microscopic liquid water droplets in the air). Fog harvesters already exist in arid regions of the world as mesh nets, but suffer dual constraints from their grid-like structure: course meshes fail to capture most fog droplets passing through, while fine meshes get clogged. To bypass these inherent limits, we turn to nature for a solution. It has been observed that California redwood trees are able to effectively collect fog on their straight leaf needles, dripping droplets to the roots below. Inspired by this, we fabricate a device called a fog harp, which removes the impeding horizontal wires of meshes to effectively capture and slide droplets down its vertical wires. In this work, we expand upon previous fog harp research by investigating ways to optimize its water collection efficiency. First, we develop a mathematical model to describe the tangling of harp wires due to merging droplets on adjacent wires pulling them together. Second, we systematically vary three key parameters of the fog harp (wire material, center-to-center wire spacing, and wire length) to arrive at the optimal combination. Finally, we develop a model to describe the dynamics of droplets sliding down harp wires while merging with others littered along it. These studies will raise the performance ceiling of fog harps and push them to real-world applications.

La régénération osseuse est un processus impliquant de nombreux types cellulaires comme les ostéoblastes, les chondrocytes ou les cellules stromales mésenchymateuses (CSM). Les CSM possèdent des capacités de différenciation suggérant leur implication dans ce processus de réparation. La régénération osseuse est le fruit de la coordination complexe de l'activité de nombreux facteurs de croissance. Parmi eux, l'« Heparin affin regulatory peptide » (HARP) est fortement exprimé dans le callus durant la régénération mais son rôle n'est pas clairement établi. Le but de ce travail de thèse a été (1) d'évaluer les effets de HARP sur les propriétés de migration, de prolifération et de différenciation des CSM in vitro ; (2) évaluer la capacité de HARP à induire une formation osseuse ou une régénération osseuse in vivo.Nos résultats démontrent que HARP est chémoattractant pour les CSM et potentialise leur prolifération. De plus, nous montrons pour la première fois que le traitement de CSM par HARP durant leur chondroinduction conduit à une différenciation chondrocytaire de type hypertrophique. Ce type cellulaire est primordial dans les derniers stades de la formation osseuse endochondrale qui se met en place durant la croissance osseuse, mais également durant la réparation. L'implantation de biomatériaux associés à HARP dans un défaut osseux de condyle fémoral a conduit à la formation de cartilage et d'os dans l'implant, reproduisant le mécanisme physiologique de formation osseuse endochondrale. Le biomatériau seul n'a été envahi que par du tissu fibreux.Durant les processus de réparation tissulaire, les glycosaminoglycannes (GAG), des chaînes polysaccharidiques sulfatées, composants majeurs de la matrice extracellulaire, participent à la modulation des effets des facteurs de croissance durant la réparation. Récemment, des mimétiques structuraux et fonctionnels des GAG ont été développés. Durant ma thèse, j'ai été associé au travail d'un doctorant de l'équipe de P.Albanese, qui a montré que des mimétiques de GAG induisent une différenciation ostéoblastique des CSM en l'absence de traitement ostéoinducteur. L'implantation sous-cutanée de biomatériaux covalemment associés aux mimétiques ont également été menées, et ont permis d'observer des potentialisations des processus de vascularisation de l'implant et de l'activité ostéoclastique. Ces resultats ont permis de valider l'interêt des GAG mimétiques dans le cadre des thérapies de régénération osseuse.Cette étude démontre pour la première fois les effets chondroinducteurs directs de HARP sur la production de molécules de la matrice cartilagineuse par les CSM in vitro, mais également sur la synthèse de tissu cartilagineux in vivo. Les effets de HARP observés sur la régénération osseuse confirment qu'il pourrait être un bon candidat en chirurgie orthopédique en permettant une régénération de type endochondrale typique de la réparation physiologique. De plus les nouvelles stratégies developpées dans le laboratoire sur la fonctionnalisation covalente de biomateriaux par des GAG mimétiques, meriteraient d'etre testées en association avec HARP, afin d'augmenter sa demi-vie et de controler son relarguage et ses activités biologiques in vivo. / Bone regeneration is a complicated process which involved many cellular types such as osteoblasts, chondrocytes and mesenchymal stromal cells (MSC). MSC can differentiate toward chondrocytes and osteoblasts, suggesting their implication in bone regeneration processes. Bone reparation involved a complex coordination of growth factors. Among them, heparin affin regulatory peptide (HARP) is found in callus during regeneration. However, its role is poorly understood. The aim of this thesis was (1) to evaluate HARP effects on proliferation, migration and differentiation of MSC in vitro, (2) to evaluate HARP ability to promote bone regeneration or bone formation.Our results demonstrate that HARP has chemoattractive and proliferative properties on human MSC. Moreover, we show for the first time that HARP commits human MSC toward hypertrophy during chondrogenesis. This is of great interest since hypertrophic chondrocytes are of primary importance in the late stage of endochondral bone formation. We further tested the association of HARP to scaffolds in a model of bone regeneration in femoral defect in rat. HARP associated scaffolds showed an invasion of cartilage and bony tissues, mimicking endochondral bone formation, whereas scaffold alone was just filled with fibrous tissue.During regenerative processes glycosaminoglycans, polysaccharides sulfated chains, are known as major components of the extracellular matrix and modulate the effects of growth factors during regenerative processes. Recently, structurally and functionally mimetics of GAG had been developed. During my PhD thesis, I was associated to the work of a doctoral student of P. Albanese who showed that GAG mimetics induce osteoblastic differentiation of MSC without any other osteoinductive treatment. The ectopic implantation of mimetic associated scaffolds didn't show effects on osteoformation but induced an enhancement of vascularization and of osteoclastic activity, both related to tissue remodeling. These results validate that GAG mimetics are of great interest in bone regenerative field.This study demonstrates for the first time the chondroinductive potential of HARP through its ability to induce cartilage specific matrix production by MSC in vitro but also by inducing cartilage tissue synthesis in vivo. The effects of HARP observed on bone regeneration, by inducing an endochondral bone formation similar to that observed in normal bone regeneration, confirm that HARP could be a good candidate in orthopedic surgery. Moreover, scaffold covalently linked with GAG mimetics should be tested in association with HARP. This strategy could increase the half life, control the release and potentiate HARP properties in vivo.

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HARP (Heparin Affin regulatory peptide) est un facteur de croissance qui constitue avec la midkine une sous-famille des Heparin Binding Growth Factors (HBGFs). HARP est impliqué dans de nombreux processus physiologiques comme la neurogenèse et la vasculogenèse mais aussi dans des processus physiopathologiques comme l’angiogenèse et la progression tumorale. HARP interagit avec différents récepteurs (N-syndécan, RPTPβ/ζ, et ALK). Plus récemment, il a été montré au laboratoire que la nucléoline, protéine navette entre le noyau, le cytoplasme, et la surface cellulaire est un nouveau récepteur à HARP. Malgré les avancées dans ce domaine, l’interaction de HARP avec ses récepteurs n’est pas totalement élucidée. L'objectif de ce projet de thèse était la recherche de nouveaux partenaires moléculaires qui interagissent avec HARP, de comprendre le mécanisme de leurs interaction et d’analyser les effets biologiques. A ce titre, j’ai participé à l’étude de l’interaction de HARP avec le facteur de croissance des fibroblastes, le FGF-2. Ce facteur liant l’héparine est également mitogène et angiogène. En utilisant des techniques de biocapteurs optiques et d’interaction protéine-protéine, nous avons montré une interaction directe entre HARP et le FGF-2 et qui implique les domaines C-TSR-I et C-terminale de HARP. De plus, cette interaction inhibe la migration et la prolifération des cellules endothéliales, induites par le FGF-2 ou par HARP seuls. En parallèle, j’ai mis en évidence l’interaction entre HARP et la NRP-1. NRP-1 est une protéine transmembranaire, ayant comme ligands principaux, les sémaphorines de classe 3 (SEMA 3A), le facteur de croissance endothélial vasculaire (VEGF) et le FGF-2. En plus de son rôle crucial dans le développement des systèmes nerveux et cardiovasculaires, la NRP-1 est impliquée dans les processus physiopathologiques tels que l’angiogenèse et l’invasion tumorale. Ainsi, la NRP-1 présente un profil biologique similaire à HARP. En utilisant des tests d’ELISA, d’immunoprécipitation et de « pull-down », nous avons montré que HARP interagit avec la NRP-1. Cette interaction semble être directe et s’effectue via les domaines de liaison à l’héparine TSR-I. HARP induit l’internalisation de la NRP-1 au bout de 15 minutes et son recyclage partiel à la surface cellulaire au bout d’une heure. L’internalisation de la NRP-1 s’accompagne par la phosphorylation des voies MAPK (ERK1/2), Akt et FAK. L’interaction HARP/NRP-1 est cruciale pour la migration des cellules endothéliales et l’invasion des cellules tumorales. En conclusion, ces résultats apportent de nouvelles avancées concernant les partenaires moléculaires de HARP en particulier et montrent également la complexité des interactions des facteurs de croissance entre eux et avec leurs récepteurs. Plus généralement, cette étude permet d'envisager des stratégies thérapeutiques ciblant l’interaction de la NRP-1 avec HARP et aussi les autres facteurs de croissance. / HARP (Heparin Affin regulatory peptide) is a growth factor that constitutes with midkine a subfamily of Heparin Binding Growth Factors (HBGFs). HARP is involved in many physiological processes such as neurogenesis and vasculogenesis but also in pathophysiological processes such as angiogenesis and tumor progression. HARP interacts with different receptors (N-syndecan, RPTPβ / ζ and ALK). More recently, it has been shown in the laboratory that nucleolin, a protein shuttle between the nucleus, cytoplasm, and cell surface, is a new HARP receptor. Despite the advances in this field, the interaction of HARP with its receptors is not fully understood. The aim of this thesis was the search for new molecular partners that interact with HARP, to understand the mechanism of their interaction and analyze the biological effects. My work was firstly to participate to the study of the interaction of HARP with the fibroblast growth factor-2, FGF-2. This factor is also an heparin-binding factor, with mitogenic and angiogenic activities. Using techniques of optical biosensors and protein-protein interaction, we have shown a direct interaction between HARP and FGF-2 that involves C-TSR-I and C-terminus domains of HARP. In addition, HARP inhibits the migration and proliferation of endothelial cells induced by FGF-2. In parallel, I highlighted the interaction between HARP and NRP-1. NRP-1 is a transmembrane protein having as main ligands, semaphorins class 3 (SEMA 3A), the vascular endothelial growth factor (VEGF) and FGF-2. In addition to its crucial role in the development of the nervous and cardiovascular systems, the NRP-1 is involved in physiopathological processes such as angiogenesis and tumor invasion. Thus, NRP-1 has a biological profile similar to HARP. Using ELISA, immunoprecipitation and "pull-down" tests, we have shown that HARP interacts with NRP-1. This interaction appears to be direct and occurs via heparin binding domains of HARP: TSR-I. HARP induces internalization of NRP-1 after 15 minutes and partial recycling to the cell surface after one hour. The internalization of the NRP-1 is accompanied by the phosphorylation of MAPK pathways (ERK1 / 2), Akt and FAK. HARP/NRP-1 interaction is crucial for endothelial cell migration and invasion of tumor cells. In conclusion, these results provide new advances on molecular partners of HARP in particular and also show the complexity of the interactions between these growth factors and their receptors. More generally, this study allows considering therapeutic strategies targeting the interaction of NRP-1 with HARP as well as other growth factors.

When one realizes how little the harp of the 1700's had advanced from its Biblical predecessors, its neglect by such masters as Bach, Haydn, and Beethoven does not seem remarkable. Why should a serious composer waste his time in writing for an instrument with no facilities for modulating, an instrument the weak tones of which would be lost in an orchestra?

During the 20th century, chamber works for harp expanded to include significantly different instrumentations, like flute, voice and harp. Indeed, a body of works for flute, voice, and harp began to develop mainly through the commissioning efforts of ensembles comprised of these instruments. This study of George Crumb's Federico's Little Songs for Children for flutes, soprano, and harp considers the unique advantages and challenges of this instrumentation and offers specific suggestions for performance. Attention to various compositional elements of Federico's Little Songs for Children, especially as they relate to the text, is also helpful in preparing to perform this work. The form, pitch material, and text-painting in the work allow for special opportunities to convey meaning to audiences in ways that do not rely on traditional tonal relationships. Accompanying the shift away from traditional tonal relationships, the development of the harp repertoire in chamber and solo settings during the 20th century also led to the development of many extended- techniques for this instrument. For the most part, these techniques have been described and given various notational symbols but not discussed in detail with regard to execution. Federico's Little Songs for Children itself requires several unique extended-techniques. Recommendations are given in this paper concerning how to achieve the extended-techniques in Crumb's work in a stylistically appropriate and effective manner.