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Recent studies have demonstrated that nanoscale crystalline iron oxide minerals are common in natural systems. The discipline of nanoscience suggests that these particles in the size range of approximately 1-50 nm will have properties that deviate from the bulk properties of the same material and that these properties will change as a function of particle size. This study begins to fill the void of corresponding experimental investigations that apply the principles of nanoscience to the geochemical reactivity of nanominerals. The rate of Mn²⁺(aq) oxidation on hematite with average diameters of 7.3 nm and 37 nm was measured in the presence of O₂(aq). In the pH range of 7-8, the surface area normalized rate was one to two orders of magnitude greater on the 7.3 nm average diameter particles. Based on the application of electron transfer theory, it is hypothesized that the particles with diameters less than approximately 10 nm have surface crystal chemical environments which distort the symmetry of the MnMn²⁺ surface complex, reducing the energy required to reorganize the coordinated ligands after oxidation to Mn³⁺. Cu²⁺, an analog for Mn³⁺, was used to probe for the presence and nature of the proposed changes in surface structure. Cu²⁺ and Mn³⁺ show similar electronic structure changes in response to the surrounding crystal field due to their d-electron configurations and Jahn-Teller coordinative distortions. Batch sorption experiments on hematite nanoparticles revealed a shift in the pH-dependent adsorption of Cu²⁺(aq). Specifically, an affinity sequence of 7 nm > 25 nm = 88 nm was determined based on the shift of the 7 nm sorption edge to approximately 0.8 pH units lower than that for the 25 nm and 88 nm samples. These data support the hypothesis that unique binding sites exist on the 7 nm nanoparticles that are not significantly present on the larger particles. The National Nanotechnology Initiative stresses the need to address the broader societal impacts of nanoscale research. This dissertation embraces this viewpoint through the development and inclusion of "Nano2Earth: Introducing Nanotechnology Through Investigations of Groundwater," a curriculum which combines nanoscience with the Earth sciences for high school students. / Ph. D.

Nanotechnology and nanoscience are experiencing rapid development in the last decade. Intensive research has been carried out on nanostructures synthesis and nanodevices fabrication. Due to its small size, a nanodevice usually requires an extremely small power to operate. However, to make the novel nanodevice work, an external power source is normally needed, which can either be a battery or a power source, thus, the size of the battery is usually much larger than that of the device and its life time is limited. It is highly desired to have a nanoscale size power source that harvests its energy from the environment so that it works independently and wirelessly to provide power to the nanodevices. This dissertation provides a solid solution to this dilemma based on nanotechnology. Starting from the synthesis of well aligned ZnO nanowire arrays on different substrates, an innovative method is presented first to measure the mechanical property of the as-synthesized ZnO nanowire arrays by using AFM without destroying and manipulating the sample. This technique is then extended to converte mechanical energy into electricity by scanning the nanowire arrays using a AFM tip in contact mode. Due to the unique semiconducting and piezoelectric dual properties of ZnO, mechanical energy is converted into electricity and is effectively output. This is the invention of the piezoelectric nanogenerator. Then, by replacing AFM tips using a zigzag top electrode, the first prototype direct-cirrent nanogenerator driven by ultrasonic wave has been fabricated. Further investigations have also been carried out about the effect of ZnO carrier density on the output power, and the power generating property of oligomer functionalized ZnO nanowires. This desertation established the fundamental mechanism for the nanogenerator, and it provides a new path towards self-powered nanosystems, which has key applications in in-vivo biosensing, MEMS, environmental mornitoring, defence technology and even personal electronics.

Les simulations moléculaires sont devenues un outil essentiel en biologie, chimie et physique. Malheureusement, elles restent très coûteuses. Dans cette thèse, nous proposons des algorithmes qui accélèrent les simulations moléculaires en regroupant des particules en plusieurs objets rigides. Nous étudions d’abord plusieurs algorithmes de recherche de voisins dans le cas des grands objets rigides, et démontrons que les algorithmes hiérarchiques permettent d’obtenir des accélérations importantes. En conséquence, nous proposons une technique pour construire une représentation hiérarchique d’un graphe moléculaire arbitraire. Nous démontrons l’usage de cette technique pour la mécanique adaptative en angles de torsion, une méthode de simulation qui décrit les molécules comme des objets rigides articulés. Enfin, nous introduisons ARPS – Adaptively Restrained Particle Simulations (“Simulations de particules restreintes de façon adaptative”) – une méthode mathématiquement fondée capable d’activer et de désactiver les degrés de liberté en position. Nous proposons deux stratégies d’adaptation, et illustrons les avantages de ARPS sur plusieurs exemples. En particulier, nous démontrons comment ARPS permet de choisir finement le compromis entre précision et vitesse, ainsi que de calculer rapidement des proprietésstatiques d’équilibre sur les systèmes moléculaires. / Molecular simulations have become an essential tool in biology, chemistry and physics. Unfortunately, they still remain computationally challenging. In this dissertation, we propose algorithms that accelerate molecular simulations by clustering particles into rigid bodies.We first study several neighbor-search algorithms for large rigid bodies, and show that hierarchy-based algorithms may provide significant speedups. Accordingly, we propose a technique to build a hierarchical representation of an arbitrary molecular graph. We show how this technique can be used in adaptive torsion-angle mechanics, a simulation method that describes molecules as articulated rigid bodies. Finally, we introduce ARPS – Adaptively Restrained Particle Simulations – a mathematically-grounded method able to switch positional degrees of freedom on and off. We propose two switching strategies, and illustrate the advantages of ARPS on various examples. In particular, we show how ARPS allow us to smoothly trade between precision and speed, and to efficiently compute correct static equilibrium properties on molecular systems.

Nous examinons une question que l'avènement des nanotechnologies rend de plus en plus pressante pour la philosophie des sciences. Elle prend les allures d'une critique de cette dernière en se fondant sur quelques théories philosophiques, représentatives et suffisamment originales sur la science, développées par Thomas Kuhn, Imre Lakatos, Ian Hacking et Serge Robert. Les différents discours sur les nanos et plus précisément le concept de nanotechnologie se sont révélés, à tout le moins, polysémiques et décrivent parfois prématurément une activité qui n'existe pas encore. Ainsi, nous avons requalifié le concept de nanotechnologie en « nanotechnoscience ». Puis nous avons confronté les philosophies des sciences que nous avons retenues aux fins de les mettre à l'épreuve de ce qui apparaît comme un impensé de leurs philosophies, notamment la dimension technologique de la science souvent connue et reconnue, mais « sous-traitée » et reléguée au mieux au second plan. Nos recherches ont donc porté sur chacune des philosophies que nous avons annoncées, sur les nanotechnosciences elles-mêmes, la philosophie de la technologie, mais aussi sur celle naissante des technosciences et des nanotechnosciences sans oublier notre ouverture à des fins heuristiques sur la philosophie du langage d'Austin et la praxéologie de Denis Vernant. Dans cette étude, nous avons traité d'étymologie, d'histoire du préfixe nano et de définition. Puis, nous avons examiné attentivement les différentes philosophies des sciences par lesquelles il nous a paru pertinent d'examiner les nanotechnosciences émergentes afin de voir ce qui dans ces doctrines permettrait d'envisager une réflexion philosophique sur les nanos. Sachant que ces pensées privilégient la représentation sur l'intervention, nous nous sommes posés la question de la place de la technologie dans ces systèmes philosophiques avec l'idée que la technologie est une condition nécessaire quoique non suffisante de toute philosophie à prétention technoscientifique ou nanotechnoscientifique. C'est dans cette optique que nous avons sollicité la théorie des paradigmes, puis celle du falsificationnisme sophistiqué revu et corrigé par le correctionnisme de Robert avant de tenter l'interventionnisme de Hacking. Nous avons pu constater l'omniprésence de la technologie tout comme l'hétérogénéité de la place qui lui est accordée dans ces théories philosophiques. Ainsi de Kuhn à Hacking, la reconnaissance du rôle et de la place de la technologie va crescendo, au point de nous inviter à penser les nanotechnosciences en termes d'« actes de discours ». L'enchevêtrement ou l'entrelacement entre science et technologie nous a inspiré deux analogies : la première avec l'idée de « contexte de performance oral » de Mamoussé Diagne analogue elle-même à la seconde, la performativité introduite et initiée par les réflexions d'Austin sur le discours ordinaire. Notre investigation prend les allures d'une mise à l'épreuve de toutes ces philosophies à l'aune de la place qu'occupe la technologie dans leurs systèmes respectifs. Nous avons eu recours à l'analyse comparative des discours philosophiques sur la science ainsi que ce que nous avons appris sur les pratiques scientifiques, le tout complété par une approche lexicométrique basée sur le corpus des principaux ouvrages de Kuhn, Lakatos, Robert et Hacking. Notre démarche nous a amené à mettre en cause l'étymologie du préfixe nano trop hâtivement attribuée au grec alors qu'il serait plus à propos de la considérer comme latine, puis nous avons tenté d'établir l'idée que les « nanotechnologies » n'existent pas et que ce que l'on appelle bien souvent ainsi relève d'un abus de langage et d'une sorte d'anachronisme inversée. De cette critique nous avons tenté de tirer des leçons qui ont inspiré la requalification conceptuelle de l'activité qu'est censé désigner ce morphème en « nanotechnoscience » que nous avons redéfini en tenant compte de plusieurs facteurs déterminants. / This thesis focuses on the consideration of a question that the advent of what is called nanotechnology makes it increasingly urgent to philosophy in general and the philosophy of science in particular because of the inexistence of the “nanotechnology” stricto sensu, the lack of good definition and the default of something like a “nanophilosophy”. We critique the latter based on some philosophical, representative and sufficiently original theories of science, developed by Thomas Kuhn, Imre Lakatos, Ian Hacking and Serge Robert. Different discourses on nanos and more specifically the concept of nanotechnology proved, at least, polysemous and sometimes describe an activity which in the strict sense does not exist prematurely. Thus, we have reclassified the concept of nanotechnology "nanotechnoscience" and proposed a more rigorous definition emphasizing the hybrid nature of this activity, both theoretical and practical, scientific and technological. Then we compared the philosophies of science that we have selected to make them confront what appears to be an unthought of their philosophies, including the technological dimension of science often known and recognized, but "outsourced" and relegated to better secondary. Our research has therefore focused on each of the philosophies that we announced on the nanotechnosciences themselves, philosophy of technology, but also on emerging technosciences and nanotechnoscience not forgetting our opening for heuristic purposes on the philosophy of language of Austin and praxeology of Denis Vernant. Then, we carefully examined the different philosophies of science which seemed appropriate to consider the emerging nanotechnosciences so as to see what in these doctrines would help envisaging a philosophical reflection on the Nano. Knowing that these thoughts favor representing rather than intervening, we questioned the role of technology in these philosophical systems with the idea that technology is a necessary though not sufficient condition for any claim of technoscientific or nanotechnoscientific philosophy. It is in this context that we solicited the paradigms theory, then the sophisticated falsificationism reviewed and corrected by Robert's correctionism before attempting interventionism Hacking's interventionism. During this exercise we have seen the pervasiveness of technology as well as the heterogeneity of the place it is granted in these philosophical theories. The entanglement or intertwining between science and technology inspired us two analogies: the first with the idea of "context of oral performance" by Mamoussé Diagne, analogous itself to the second, performativity introduced and initiated by Austin's reflections on ordinary language. Our investigation takes on the appearance of a testing of all these philosophies in terms of the place of technology in their respective systems. To achieve this, we resorted to the comparative analysis of philosophical discourse on science and what we have learned about scientific practices, complemented by a lexicometric approach based on the corpus of the principal works published from Kuhn, Lakatos, Robert and Hacking. From our critique we have tried to draw lessons that inspired the conceptual requalification of the activity that this morpheme is intended to mean into "nanotechnoscience" which we have redefined. This established at the end of this analysis, we could say that neither the philosophy of Kuhn or Lakatos, nor that of Robert leave enough space for technology to position itself as philosophies of technosciences. The one which seems the most appropriate is the interventionism defended by Hacking, but which Gilbert Hottois criticized for not having taken the step that would have led to a philosophy of authentic technosciences. It was then that tracks to Bacon and Peirce are suggested respectively by Hacking and Schmidt and Nordmann.

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