<p>  </p> <p>Low-dimensional materials (LDMs) are substances that have at least one dimension with thicknesses in the nanometer (nm) scale. They have attracted tremendous research interests in many fields due to their unique properties that are absent in bulk materials. For instance, in quantum optics/photonics, LDMs offer unique advantages for effective light extraction and coupling with photonic/plasmonic structures; in chemistry, the large surface-to-volume ratio of LDMs enables more efficient chemical processes that are useful for numerous applications. In this thesis, several types of LDMs are studied and engineered with the goal to improve their impact in plasmonic and quantum photonic applications. Two-dimensional hexagonal boron nitride (hBN) is receiving increasing attention in quantum optics/photonics as it hosts various types of quantum emitters that are promising for quantum computing, quantum sensing, etc. In the first study, we explore and demonstrate a radiation- and lithography-free route to deterministically create single-photon emitters (SPEs) in hBN by nanoindentation with an atomic force microscopy. The method applies to hBN on flat, chip-compatible silicon-based substrates, and an SPE yield of up to 36% is achieved. This marks an important step toward the deterministic creation and integration of hBN SPEs with photonic and plasmonic devices. In the second study, the recently discovered negatively charged boron vacancy (V_B^-) spin defect in hBN is investigated. V_B^- defects are optically active with spin properties suitable for sensing at extreme scales. To resolve the low brightness issue of V_B^- defects, we couple them with an optimized nano-patch antenna structure and observe emission intensity enhancement that is nearly an order of magnitude higher than previous reports. Our achievements pave the way for the practical integration of V_B^- defects for quantum sensing. Zero-dimensional nanodiamond is another important host material for solid-state SPEs. Specifically, the negatively charged silicon vacancy (SiV) center in nanodiamonds exhibits optical properties that are suitable for quantum information technologies. In the third study, we, for the first time, demonstrate the creation of single SiV centers in nanodiamonds with an average size of ~20 nm using ion implantation. Stable single-photon emission is confirmed at room temperature, with zero-phonon line (ZPL) wavelengths in the range of 730 – 803 nm. This confirms the feasibility of single-photon emitter creation in nanodiamonds with ion implantation, and offers new opportunities to integrate diamond color centers for hybrid quantum photonic systems. Finally, we have also explored using metal-semiconductor hybrid nanoparticles for plasmon-enhanced photocatalysis. A core-shell nanoparticle structure is synthesized, with titanium nitride (TiN) and titanium dioxide (TiO₂) being the core and shell material respectively. It is observed that such core-shell nanoparticles effectively catalyze the generation of single oxygen molecules under 700-nm laser excitation. The main mechanism behind is the hot electron injection from the TiN core to the TiO₂ shell. Considering the chemical inertness and low cost of TiN, TiN@TiO₂ NPs hold great potential as plasmonic photosensitizers for photodynamic therapy and other photocatalytic applications at red-to-near-infrared (NIR) wavelengths.</p>

No description available.

Systems of interacting colloidal particles are ideal tools for studies of pattern formation and collective non-equilibrium dynamics on the mesoscopic scale. These processes are governed by the interaction between the particles, which can be tuned by sophisticated fabrication. In this thesis, self-assembly of artificially designed magnetic spheres dispersed in water has been studied via video microscopy. The particles are based on silica microspheres with hemispherical ferromagnetic coating of [Co/Pd] multilayers with perpendicular magnetic anisotropy. These particles are exceptional in that they exhibit an off-centered net magnetic moment and yet obey rotational and mirror symmetry. It has been demonstrated how these magnetic properties provide innovative flexibility in pattern formation and collective dynamics based on magnetostatic interactions on the mesoscopic scale. The results are supported by analytical and numerical calculations of interacting spheres with radially shifted point dipoles (sd-particles). In two dimensions, the particles spontaneously self-assemble into branched structures as a result of a bistable assembly behavior where neighboring particles exhibit a non-collinear magnetic orientation. It has been shown that these features, which are atypical for homogeneous systems of magnetic particles, can be reproduced by simulation. It employs a theoretical model of a sphere that contains a distribution of three radially shifted point dipoles in analogy to the magnetization distribution in the coated particles. The stability of the assembly has been examined further by external manipulation using optical tweezers and homogeneous magnetic fields. A rich variety of stable structures with diverse spatial and magnetic ordering has been found. Particularly, the collective alignment of the specially designed particles in external fields opens completely new possibilities for the remote control over reversible pattern formation on the micrometer scale. In time-dependent fields, the collective dynamics of the anisotropic particles has revealed a novel approach for magnetically actuated translation. The variety of stable structures particularly enables control over this motion. / Kolloidale Suspensionen sind geeignete Systeme zur Untersuchung von Strukturbildung und kollektiver Nichtgleichgewichtsdynamik in mesoskopischen Größenskalen. Diese Vorgänge werden durch die Wechselwirkung zwischen den Teilchen bestimmt, welche durch geeignete Partikelherstellung angepasst werden kann. In der vorliegenden Arbeit wird ein System von künstlich hergestellten magnetischen Partikelsuspensionen mittels Videomikroskopie untersucht. Quarzglas-Mikrokugeln wurden halbseitig mit einer ferromagnetischen Dünnschicht aus [Co/Pd] Multilagen mit senkrechter Anisotropie beschichtet. Solche Partikel sind ausgezeichnet durch ein resultierendes magnetisches Moment mit Rotations- und Spiegelsymmterie, welches zusätzlich vom Mittelpunkt der Kugel verschoben ist. Die vorliegende Arbeit zeigt, dass diese Besonderheit zu einer bisher unbekannten Flexibilität bei der mesoskopischen Strukturbildung und der kollektiven Dynamik auf der Basis magnetostatischer Wechselwirkung führt. Die vorgestellten Ergebnisse werden durch analytische und numerische Berechnungen unterstützt, denen ein Modell einer idealen Kugel mit verschobenem Dipol zugrunde liegt. Die zweidimensionale Selbstanordnung der Partikel zeigt experimentell zwei stabile Formen der Verknüpfung, welche zu verzweigten Strukturen mit unterschiedlich magnetischer Ausrichtung benachbarter Partikel führen. Diese für ein homogenenes System magnetischer Partikel außergewöhnlichen Eigenschaften konnten in Simulationen durch ein Modellsystem aus Kugeln mit drei verschobenen Punktdipolen reproduziert werden. Darüber hinaus wurde die spontante Anordnung unter externer Manipulation mittels optischer Pinzette und magnetischen Feldern untersucht. Es konnte eine Vielfalt an stabilen Strukturen mit verschiedenen magnetischen und strukturellen Anordnungen gefunden werden. Insbesondere die kollektive Ausrichtung dieser Partikel in externen Feldern eröffnet neuartige Möglichkeiten, kontrolliert und reversibel Mikrostrukturen zu erzeugen. In zeitabhängigen Feldern zeigen die anisotropen Partikel zusätzlich eine kollektive Dynamik welche eine neue Möglichkeit zum magnetischen Antrieb von Partikelagglomeraten eröffnet. Die Vielfalt der möglichen stabilen Strukturen erlaubt es in besonderer Weise diese Bewegung zu steuern.

Among the many active materials in use today, piezoelectric composite patches have enabled notable advances in emerging technologies such as disturbance sensing, control of flexible structures, and energy harvesting. The macro fiber composite (MFC), in particular, is well known for its outstanding performance. Multiscale models are typically required for smart-structure design with MFCs. This is due to the need for predicting the macroscopic response (such as tip deflection under a transverse load or applied voltage) while accounting for the fact that the MFC has microscale details. Current multiscale models of the MFC exclusively focus on predicting the macroscopic response with homogenized material properties. There are a limited number of homogenized properties available from physical experiments and various aspects of existing homogenization techniques for the MFC are shown here to be inadequate. Thus, new homogenized models of the MFC are proposed to improve smart-structure predictions and therefore improve device design. It is notable that current multiscale modeling efforts for MFCs are incomplete since, after homogenization, the local fields such as stresses and electric fields have not been recovered. Existing methods for obtaining local fields are not applicable since the electrodes of the MFC are embedded among passive layers. Therefore, another objective of this work was to find the local fields of the MFC without having the computational burden of fully modeling the microscopic features of the MFC over a macroscale area. This should enable smart-structure designs with improved reliability because failure studies of MFCs will be enabled. Large-scale 3D finite element (FE) models that included microscale features were constructed throughout this work to verify the multiscale methodologies. Note that after creating a free account on cdmhub.org, many files used to create the results in this work can be downloaded from https://cdmhub.org/projects/ernestocamarena.<br><br>First, the Mechanics of Structure Genome (MSG) was extended to provide a rigorous analytical homogenization method. The MFC was idealized to consist of a stack of homogeneous layers where some of the layers were homogenized with existing rules of mixtures. For the analytical model, the electrical behavior caused by the interdigitated electrodes (IDEs) was approximated with uniform poling and uniform electrodes. All other assumptions on the field variables were avoided; thus an exact solution for a stack of homogeneous layers was found with MSG. In doing so, it was proved that in any such multi-layered composite, the in-plane strains and the transverse stresses are equal in each layer and the in-plane electric fields and transverse electric displacement are constant between the electrodes. Using this knowledge, a hybrid rule of mixtures was developed to homogenize the entire MFC layup so as to obtain the complete set of effective device properties. Since various assumptions were avoided and since the property set is now complete, it is expected that greater energy equivalence between reality and the homogenized model has been made possible. The derivation clarified what the electrical behavior of a homogenized solid with internal electrodes should be—an issue that has not been well understood. The behavior was verified by large-scale FE models of an isolated MFC patch.<br> <br>Increased geometrical fidelity for homogenization was achieved with an FE-based RVE analysis that accounted for finite-thickness effects. The presented theory also rectifies numerous issues in the literature with the use of the periodic boundary conditions. The procedure was first developed without regard to the internal electrodes (ie a homogenization of the active layer). At this level, the boundary conditions were shown to satisfy a piezoelectric macrohomogeneity condition. The methodology was then applied to the full MFC layup, and modifications were implemented so that both types of MFC electrodes would be accounted for. The IDE case considered nonuniform poling and electric fields, but fully poled material was assumed. The inherent challenges associated with these nonuniformities are explored, and a solution is proposed. Based on the homogenization boundary conditions, a dehomogenization procedure was proposed that enables the recovery of local fields. The RVE analysis results for the effective properties revealed that the homogenization procedure yields an unsymmetric constitutive relation; which suggests that the MFC cannot be homogenized as rigorously as expected. Nonetheless, the obtained properties were verified to yield favorable results when compared to a large-scale 3D FE model.<br> <br>As a final test of the obtained effective properties, large-scale 3D FE models of MFCs acting in a static unimorph configuration were considered. The most critical case to test was the smallest MFC available. Since none of the homogenized models account for the passive MFC regions that surround the piezoelectric fiber array, some of the test models were constructed with and without the passive regions. Studying the deflection of the host substrate revealed that ignoring the passive area in smaller MFCs can overpredict the response by up to 20%. Satisfactory agreement between the homogenized models and a direct numerical simulation were obtained with a larger MFC (about a 5% difference for the tip deflection). Furthermore, the uniform polarization assumption (in the analytical model) for the IDE case was found to be inadequate. Lastly, the recovery of the local fields was found to need improvement.<br><br><br>

Made available in DSpace on 2014-12-17T15:42:20Z (GMT). No. of bitstreams: 1 MoisesRC_TESE.pdf: 5138295 bytes, checksum: 2244f5424aa2282bc24737aca40cf3d2 (MD5) Previous issue date: 2013-04-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Topics of research related to energy and environment have significantly grown in recent years, with the need of its own energy as hydrogen. More particularly, numerous researches have been focused on hydrogen as energy vector. The main portion of hydrogen is presently obtained by reforming of methane or light hydrocarbons (steam, oxy, dry or auto reforming). During the methane steam reforming process the formation of CO2 undesirable (the main contributor to the greenhouse effect) is observed. Thus, an oxide material (sorbent) can be used to capture the CO2 generated during the process and simultaneously shifting the equilibrium of water gas shift towards thermodynamically more favorable production of pure hydrogen. The aim of this study is to develop a material with dual function (catalyst/sorbent) in the reaction of steam reforming of methane. CaO is well known as CO2 sorbent due to its high efficiency in reactions of carbonation and easy regeneration through calcination. However the kinetic of carbonation decreases quickly with time and carbonation/calcination cycles. A calcium aluminate (Ca12Al14O33) should be used to avoid sintering and increase the stability of CaO sorbents for several cycles. Nickel, the industrial catalyst choice for steam reforming has been added to the support from different manners. These bi-functional materials (sorbent/catalyst) in different molar ratios CaO.Ca12Al14O33 (48:52, 65:35, 75:25, 90:10) were prepared by different synthesis methodologies, among them, especially the method of microwave assisted self-combustion. Synthesis, structure and catalytic performances of Ni- CaO.Ca12Al14O33 synthesized by the novel method (microwave assisted selfcombustion) proposed in this work has not being reported yet in literature. The results indicate that CO2 capture time depends both on the CaO excess and on operating conditions (eg., temperature and H2O/CH4 ratio). To be efficient for CO2 sorption, temperature of steam reforming needs to be lower than 700 ?C. An optimized percentage corresponding to 75% of CaO and a ratio H2O/CH4 = 1 provides the most promising results since a smaller amount of water avoids competition between water and CO2 to form carbonate and hydroxide. If this competition is most effective (H2O/CH4 = 3) and would have a smaller amount of CaO available for absorption possibly due to the formation of Ca(OH)2. Therefore, the capture time was higher (16h) for the ratio H2O/CH4 = 1 than H2O/CH4 = 3 (7h) using as catalyst one prepared by impregnating the support obtained by microwave assisted self-combustion. Therefore, it was demonstrated that, with these catalysts, the CO2 sorption on CaO modifies the balance of the water gas-shift reaction. Consequently, steam reforming of CH4 is optimized, producing pure H2, complete conversion of methane and negligible concentration of CO2 and CO during the time of capture even at low temperature (650 ?C). This validates the concept of the sorption of CO2 together with methane steam reforming / T?picos de pesquisa relacionados ? energia e meio ambiente t?m crescido significativamente nos ?ltimos anos, com a necessidade de energia pr?pria como o hidrog?nio. Mais particularmente, in?meras pesquisas t?m sido focadas em hidrog?nio como vetor energ?tico. A maior parte de hidrog?nio ? atualmente obtida por reforma do metano ou hidrocarbonetos (vapor, seco, oxi ou auto reforma). Durante o processo de reforma a vapor do metano, a forma??o de CO2 indesej?vel (principal contribuinte ao efeito estufa) ? observada. Dessa forma, um material ?xido (absorbante) pode ser usado para capturar o CO2 gerado durante o processo e ao mesmo tempo deslocar o equil?brio da rea??o de deslocamento g?s-?gua no sentido termodin?mico mais favor?vel ? produ??o de hidrog?nio puro. O objetivo desse estudo consiste em desenvolver um material com dupla fun??o (catalisador/absorbante) na rea??o de reforma a vapor do metano. CaO ? bem conhecido como absorbante do CO2 devido ? sua elevada efici?ncia em rea??es de carbonata??o e f?cil regenera??o por interm?dio da calcina??o. No entanto, a cin?tica de carbonata??o decresce rapidamente em fun??o do tempo e ciclos de carbonata??o e calcina??o. Um aluminato de c?lcio (Ca12Al14O33) deve ser utilizado para evitar a sinteriza??o e aumentar a estabilidade de absorbantes de CaO durante v?rios ciclos. O n?quel, o catalisador industrial escolhido para a reforma a vapor do metano foi adicionado ao suporte em diferentes maneiras. Estes materiais bi-funcionais (absorbante/catalisador) em diferentes raz?es molares CaO.Ca12Al14O33 (48:52, 65:35, 75:25, 90:10) foram preparados por diferentes m?todos de s?ntese, dentre eles, com destaque o m?todo de autocombust?o assistida por microondas (AAM). S?ntese, estrutura e desempenho catal?tico de Ni- CaO.Ca12Al14O33 sintetizado pelo novo m?todo (autocombust?o assistida por microondas) proposto neste trabalho n?o t?m sido reportado na literatura. Os resultados indicam que o tempo de captura de CO2 depende tanto do excesso de CaO quanto das condi??es de funcionamento (como, por exemplo, a temperatura e a raz?o H2O/CH4). Para ser eficiente na absor??o de CO2, a temperatura de reforma a vapor deve ser inferior a 700 ?C. Uma percentagem otimizada correspondente a 75% de CaO e uma raz?o (H2O/CH4 = 1) fornece os resultados mais prometedores uma vez que uma menor quantidade de ?gua evita uma competi??o entre a ?gua e CO2 para a forma??o de carbonato e hidr?xido. Se esta competi??o for mais efetiva (H2O/CH4 = 3) ter-se-ia uma menor quantidade de CaO dispon?vel para absor??o possivelmente devido ? forma??o de Ca(OH)2. Por isso, o tempo de captura foi maior (16h) para a raz?o H2O/CH4 = 1 do que H2O/CH4 = 3 (7h) usando como catalisador reacional aquele preparado por impregna??o do suporte obtido por AAM. Portanto, foi demonstrado que, com esses catalisadores, a absor??o de CO2 por CaO modifica o equil?brio da rea??o de deslocamento g?s?gua. Consequentemente, a reforma a vapor de CH4 ? otimizada, produzindo hidrog?nio puro, concentra??es desprez?veis de CO2 e CO durante o tempo de captura, mesmo a baixa temperatura (650 ? C). Isso confirma o conceito de absor??o in situ de CO2 durante a reforma a vapor do metano

La stéréolithographie biphotonique (TPS) est une technique de microfabrication 3D basée sur la polymérisation par absorption biphotonique qui permet d’obtenir en une seule étape des structures 3D complexes avec des détails sub-100nm. Aujourd’hui, en raison des conditions spécifiques de fabrication liées à la TPS (fort flux, confinement spatial de la photoréaction,…), un des enjeux concerne le développement de matériaux fonctionnels compatibles avec ce procédé. Dans ce contexte, l’objectif de cette thèse a été de développer de nouveaux matériaux fonctionnels à base de polymères à empreintes moléculaires (MIP) pour élaborer des capteurs chimiques. Une première partie de ce travail a consisté à mettre en place différentes méthodes dédiées à la caractérisation des propriétés géométriques, chimiques et mécaniques des matériaux élaborés par TPS. Par exemple, la vibrométrie laser a été utilisée pour la première fois afin de sonder de façon non-invasive les propriétés mécaniques de microstructures réalisées par TPS. Dans un second temps, ce travail a été mis à profit pour étudier l’impact du processus de fabrication (i.e. conditions photoniques) ainsi que des paramètres physico-chimiques affectant la photoréaction (i.e. inhibition par oxygène et nature du monomère) sur les propriétés finales des matériaux. Enfin, en s’appuyant sur les résultats obtenus, des microcapteurs chimiques à base de MIP, à lecture optique ou mécanique, ont été fabriqués. Leurs propriétés de reconnaissance moléculaire, ainsi que leurs sélectivités ont été démontrées pour une molécule cible modèle (D-L-Phe). / The two-photon stereolithography (TPS) technique is a micro-nanofabrication method based on photopolymerization by two-photon absorption that allows in a single manufacturing step to obtain complex 3D structures with high-resolution details (sub-100nm). Due to the specific conditions of TPS process (intense photon flux, spatial confinement of the photoreaction…) one of the main concerns today is the development of functional materials compatible with the TPS. According to the aforementioned, the general objective of this thesis was to develop new functional materials based on molecularly imprinted polymers (MIP) to elaborate chemical microsensors. In the first step of this work, different methods were implemented to characterize the geometrical, chemical and mechanical properties of the materials synthesized by TPS. For example, laser-Doppler vibrometry was used for first time to evaluate the mechanical properties of microstructures fabricated by TPS in a non-invasive way. In the second step, the characterization methodology was used to study the impact of the manufacturing process (i.e. photonic conditions) and the physicochemical parameters that affect the photoreaction (i.e. oxygen inhibition and the nature of the monomer) and the final properties of the materials. Finally, the obtained results enabled the prototyping of chemical microsensors based on MIP. Their molecular recognition properties and their selectivity were demonstrated for the molecule (D-L-Phe) by an optical and a mechanical sensing method.

<p>Biogas är benämningen för metangas (CH₄) som är producerad via anaerob (syrefri) rötning av biologiskt material. I Linköping finns en av Sveriges största biogasanläggningar. Anläggningen drivs av Svensk Biogas AB som ägs av Tekniska Verken i Linköping AB (publ.). I anläggningen rötas stora mängder proteinrikt substrat vilket leder till höga halter av ammoniak (NH₃) och ammonium (NH₄⁺) i rötkammaren. Ammoniak (NH₃) är toxiskt för de metanbildare som i en välmående process står för den största delen av metangasproduktionen. Höga halter av ammoniak (NH₃) och ammonium (NH₄⁺) kan inhibera dessa metanbildare vilket leder till minskad gasproduktion.</p><p>Detta examensarbete syftar främst till att genom ett kontinuerligt rötkammarexperiment utreda om zeoliter är ett lämpligt hjälpmedel för att reducera ammonium (NH₄⁺) i en anaerob process. Vid sänkta halter ammonium (NH₄⁺) är hypotesen att de mikroorganismer som är aktiva i den mest effektiva metanbildningsvägen återetableras. Arbetet syftar även till att experimentellt utreda vilka effekter zeoliter i sin helhet har på den anaeroba processen. Zeoliters effekt vid låga zeolitkoncentrationer utreds i en serie utrötningsexperiment i batch. Dessutom har en materialstudie kring zeoliternas kapacitet i olika miljöer genomförts.</p><p>Materialstudien visade att den valda zeoliten som studerades, clinoptilolite, hade en maximal katjonbytarkapacitet på ≈ 19 mg NH₄⁺/g zeolit. Vidare konstaterades att zeoliter med mindre diameter än 1 mm har avsevärt bättre kapacitet än zeoliter med större diameter. I det kontinuerliga rötkammarexperimentet konstaterades att clinoptilolite kan användas i en rötkammare för att reducera ammoniumhalten (NH₄⁺). Detta utan att några allvarliga processtörningar uppstår. Cirka 175 g zeolit/l krävdes för att reducera ammoniumhalten (NH₄⁺) från 5300 mg NH₄⁺/l till 3200 mg NH₄⁺/l. Det är inte realistisktatt använda så stora mängder zeoliter i en fullskalig anläggning. Mikrobiologiskt sett observerades ingen förändring av de metanbildarna som dominerar den effektivaste metanbildningsvägen.</p><p>Resultaten från utrötningsförsöket i batch visade att zeolittillsatser av 5 g/l respektive 10 g/l hade en klart positiv effekt på metanbildningen jämfört utan zeolittillsats. I de batcher med 1-10 g zeolit/l startade metangasproduktionen ≈ 14 dagar tidigare än batcherna med 0 g zeolit/l. 16 dagar efter att experimentet startade hade batcherna med 5-10 g zeolit/l producerat ≈ 500 ml metangas (CH₄) jämfört med serien utan zeoliter som vid samma tidpunkt producerat ≈ 75 ml metangas (CH₄). Utrötningsgraden ökade i samtliga serier med zeolittillsats jämfört med serien utan zeoliter. Tillsatsen av 5 g zeolit/l ökade den specifika metangasproduktionen med ≈ 19 % jämfört med utan zeolittillsatser. Slutsatsen är att clinoptilolite i små koncentrationer, mellan 5-10 g/l, påverkar så väl kinetiken som utrötningsgraden för den anaeroba processen på ett positivt sett. Den optimala koncentrationen av clinoptilolite i en mesofil anaerob process bör ligga mellan 5-10 g zeolit/l.</p> / <p>Methane (CH₄) is formed by anaerobic (oxygen-free) digestion of biological materials. One of Sweden's largest biogas plants is placed in Linköping. The plant is operated by Svensk Biogas AB, which is owned by Tekniska Verken i Linköping AB (publ.). In their biogas plant a large amount of protein rich material is handled. High amounts of protein leads to high levels of ammonia (NH₃) and ammonium (NH₄⁺) in the digestion chamber. High levels of ammonia (NH₃) are toxic to the most dominant methane forming microorganism. High concentrations of ammonia (NH₃) and ammonium (NH₄⁺) can inhibit these methane forming microorganisms which may lead to a reduction in gas production.</p><p>This aim with this master thesis was to reduce high ammonium levels by adding zeolites to a lab scale continuous digestion chamber. The hypothesis is that at reduced levels of ammonium (NH₄⁺) the most effective methane forming microorganism will reestablish. This thesis also aims to experimentally investigate all types of effects that zeolites may have in an anaerobic digestion process. Which effect zeolites at low concentration have in a digestion chamber will be investigated by using lab scale batch digestion chambers. In addition, a material study on the capacity of the zeolites in different environments will be investigated.</p><p>The material study showed that the selected zeolite, clinoptilolite, had a cat ion exchange capacity around 19 mg NH₄⁺/g zeolite. It was also found that the zeolites with a diameter less than 1 mm had significantly better capacity than zeolites with larger diameter. In the continuous digestion experiment it was found that clinoptilolite can be used in a digestion chamber to reduce high levels of ammonium (NH₄⁺). This without any serious disorder on the process. Around 175 g zeolite/l was needed to reduce ammonium levels (NH₄⁺) from 5300 mg NH₄⁺/l to 3200 mg NH₄⁺/l. However, it is not realistic to use such large amounts of zeolites in a full-scale digestion chamber. No changes in the culture of methane forming microorganisms were found.</p><p>The results of the batch experiment showed that concentrations of 5 g zeolite/l and 10 g zeolite/l had a positive effect on the methanogenesis compared to batches without additives. In the batches with 1-10 g zeolite/l the forming of methane began about 14 days earlier than in the batches without any zeolites. After 16 days, batches with 5-10 g zeolite/l had produced about 500 ml of methane (CH₄), compared with series without additives, which at the same time had produced about 75 ml of methane (CH₄). The methane yield increased in all series which included zeolites compared to the batches without zeolites. Addition of 5 g zeolite/l increased the specific methane production by approximately 19 % compared to no additives. The conclusion is that clinoptilolite in small concentrations; 5-10 g/l have a positive effect on as well the kinetics as on the methane yield for the anaerobic process. The best concentration of zeolites in a mesophile anaerobic digestion chamber appears to be between 5-10 g zeolite/l.</p>

Biogas är benämningen för metangas (CH4) som är producerad via anaerob (syrefri) rötning av biologiskt material. I Linköping finns en av Sveriges största biogasanläggningar. Anläggningen drivs av Svensk Biogas AB som ägs av Tekniska Verken i Linköping AB (publ.). I anläggningen rötas stora mängder proteinrikt substrat vilket leder till höga halter av ammoniak (NH3) och ammonium (NH4+) i rötkammaren. Ammoniak (NH3) är toxiskt för de metanbildare som i en välmående process står för den största delen av metangasproduktionen. Höga halter av ammoniak (NH3) och ammonium (NH4+) kan inhibera dessa metanbildare vilket leder till minskad gasproduktion. Detta examensarbete syftar främst till att genom ett kontinuerligt rötkammarexperiment utreda om zeoliter är ett lämpligt hjälpmedel för att reducera ammonium (NH4+) i en anaerob process. Vid sänkta halter ammonium (NH4+) är hypotesen att de mikroorganismer som är aktiva i den mest effektiva metanbildningsvägen återetableras. Arbetet syftar även till att experimentellt utreda vilka effekter zeoliter i sin helhet har på den anaeroba processen. Zeoliters effekt vid låga zeolitkoncentrationer utreds i en serie utrötningsexperiment i batch. Dessutom har en materialstudie kring zeoliternas kapacitet i olika miljöer genomförts. Materialstudien visade att den valda zeoliten som studerades, clinoptilolite, hade en maximal katjonbytarkapacitet på ≈ 19 mg NH4+/g zeolit. Vidare konstaterades att zeoliter med mindre diameter än 1 mm har avsevärt bättre kapacitet än zeoliter med större diameter. I det kontinuerliga rötkammarexperimentet konstaterades att clinoptilolite kan användas i en rötkammare för att reducera ammoniumhalten (NH4+). Detta utan att några allvarliga processtörningar uppstår. Cirka 175 g zeolit/l krävdes för att reducera ammoniumhalten (NH4+) från 5300 mg NH4+/l till 3200 mg NH4+/l. Det är inte realistisktatt använda så stora mängder zeoliter i en fullskalig anläggning. Mikrobiologiskt sett observerades ingen förändring av de metanbildarna som dominerar den effektivaste metanbildningsvägen. Resultaten från utrötningsförsöket i batch visade att zeolittillsatser av 5 g/l respektive 10 g/l hade en klart positiv effekt på metanbildningen jämfört utan zeolittillsats. I de batcher med 1-10 g zeolit/l startade metangasproduktionen ≈ 14 dagar tidigare än batcherna med 0 g zeolit/l. 16 dagar efter att experimentet startade hade batcherna med 5-10 g zeolit/l producerat ≈ 500 ml metangas (CH4) jämfört med serien utan zeoliter som vid samma tidpunkt producerat ≈ 75 ml metangas (CH4). Utrötningsgraden ökade i samtliga serier med zeolittillsats jämfört med serien utan zeoliter. Tillsatsen av 5 g zeolit/l ökade den specifika metangasproduktionen med ≈ 19 % jämfört med utan zeolittillsatser. Slutsatsen är att clinoptilolite i små koncentrationer, mellan 5-10 g/l, påverkar så väl kinetiken som utrötningsgraden för den anaeroba processen på ett positivt sett. Den optimala koncentrationen av clinoptilolite i en mesofil anaerob process bör ligga mellan 5-10 g zeolit/l. / Methane (CH4) is formed by anaerobic (oxygen-free) digestion of biological materials. One of Sweden's largest biogas plants is placed in Linköping. The plant is operated by Svensk Biogas AB, which is owned by Tekniska Verken i Linköping AB (publ.). In their biogas plant a large amount of protein rich material is handled. High amounts of protein leads to high levels of ammonia (NH3) and ammonium (NH4+) in the digestion chamber. High levels of ammonia (NH3) are toxic to the most dominant methane forming microorganism. High concentrations of ammonia (NH3) and ammonium (NH4+) can inhibit these methane forming microorganisms which may lead to a reduction in gas production. This aim with this master thesis was to reduce high ammonium levels by adding zeolites to a lab scale continuous digestion chamber. The hypothesis is that at reduced levels of ammonium (NH4+) the most effective methane forming microorganism will reestablish. This thesis also aims to experimentally investigate all types of effects that zeolites may have in an anaerobic digestion process. Which effect zeolites at low concentration have in a digestion chamber will be investigated by using lab scale batch digestion chambers. In addition, a material study on the capacity of the zeolites in different environments will be investigated. The material study showed that the selected zeolite, clinoptilolite, had a cat ion exchange capacity around 19 mg NH4+/g zeolite. It was also found that the zeolites with a diameter less than 1 mm had significantly better capacity than zeolites with larger diameter. In the continuous digestion experiment it was found that clinoptilolite can be used in a digestion chamber to reduce high levels of ammonium (NH4+). This without any serious disorder on the process. Around 175 g zeolite/l was needed to reduce ammonium levels (NH4+) from 5300 mg NH4+/l to 3200 mg NH4+/l. However, it is not realistic to use such large amounts of zeolites in a full-scale digestion chamber. No changes in the culture of methane forming microorganisms were found. The results of the batch experiment showed that concentrations of 5 g zeolite/l and 10 g zeolite/l had a positive effect on the methanogenesis compared to batches without additives. In the batches with 1-10 g zeolite/l the forming of methane began about 14 days earlier than in the batches without any zeolites. After 16 days, batches with 5-10 g zeolite/l had produced about 500 ml of methane (CH4), compared with series without additives, which at the same time had produced about 75 ml of methane (CH4). The methane yield increased in all series which included zeolites compared to the batches without zeolites. Addition of 5 g zeolite/l increased the specific methane production by approximately 19 % compared to no additives. The conclusion is that clinoptilolite in small concentrations; 5-10 g/l have a positive effect on as well the kinetics as on the methane yield for the anaerobic process. The best concentration of zeolites in a mesophile anaerobic digestion chamber appears to be between 5-10 g zeolite/l.

Ceramics are distinguished from metals and polymers by their inorganic nature and lack of metallic properties. They can be highly crystalline to amorphous, and their physical and chemical properties can vary widely. Ceramics can, for instance, be made to resemble the mineral phase in bone and are therefore an excellent substitute for damaged hard tissue. They can also be made porous, surface active, chemically inert, mechanically strong, optically transparent or biologically resorbable, and all these properties are of interest in the development of new materials intended for a wide variety of applications. In this thesis, the focus was on the development of different ceramics for use in the controlled release of drugs and ions. These concepts were developed to obtain improved therapeutic effects from orally administered opioid drugs, and to reduce the number of implant-related infections as well as to improve the stabilization of prosthetic implants in bone. Geopolymers were used to produce mechanically strong and chemically inert formulations intended for oral administration of opioids. The carriers were developed to allow controlled release of the drugs over several hours, in order to improve the therapeutic effect of the substances in patients with severe chronic pain. The requirement for a stable carrier is a key feature for these drugs, as the rapid release of the entire dose, due to mechanical or chemical damage to the carrier, could have lethal effects on the patient because of the narrow therapeutic window of opioids. It was found that it was possible to profoundly retard drug release and to achieve almost linear release profiles from mesoporous geopolymers when the aluminum/silicon ratio of the precursor particles and the curing temperature were tuned. Ceramic implant coatings were produced via a biomimetic mineralization process and used as carriers for various drugs or as an ion reservoir for local release at the site of the implant. The formation and characteristics of these coatings were examined before they were evaluated as potential drug carriers. It was demonstrated that these coatings were able to carry antibiotics, bisphosphonates and bone morphogenetic proteins to obtain a sustained local effect, as they were slowly released from the coatings. / <p>Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 710</p>

This thesis entails the utilisation of ab initio density functional theory (DFT) in conjunction with neutron and synchrotron spectroscopy to study the mechanical, vibrational, and dielectric response of metal-organic framework (MOF) materials at the molecular level. MOFs are crystalline materials with nanoscale porosity, which have garnered immense scientific and technological interest for a wide variety of innovative engineering applications. One part of the thesis involves using low-frequency lattice vibrations to characterise the various physical motions that are possible for framework materials. These collective modes detected at terahertz (THz) frequencies have been used to reveal a broad range of exciting possibilities. New evidence has been established to demonstrate that THz modes are intrinsically linked to anomalous elasticity underpinning gate-opening and pore-breathing mechanisms, and to shear-induced phase transitions and the onset of structural instability. The phenomenon of molecular rotor mechanisms and trampoline-like motions are also observed, along with the first experimental confirmation of coordinated shear dynamics. Additionally, a new method to characterise the effects of temperature, and hence thermally-induced structural amorphisation is reported. Finally, for the first time, the frequency-dependent (dynamic) dielectric response of MOF materials, across the extended infrared (IR) spectral region was reported. The results were obtained from experimental synchrotron radiation IR reflectivity and DFT to reveal the low-&kcy; dielectric response of MOFs and established structure-property trends that highlight them as promising systems for microelectronic device applications.