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1
Zürner, Andreas. "New Methods Visualizing Mesostructured Materials." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-138428.
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Andersson, Nina. "Mesostructured materials : Synthesis towards applications /." Stockholm : Department of Physical, Inorganic and Structural Chemistry, Stockholm university, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6584.
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Liong, Monty. "Biomedical applications of mesostructured silica materials." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1905693461&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Patel, Jiten. "Optimal design of mesostructured materials under uncertainty." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31829.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Choi, Seung-Kyum; Committee Member: Muhanna, Rafi; Committee Member: Rosen, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.
5
Biz, Sophie. "Synthesis and characterization of mesostructured molecular sieves." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17920.
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Yang, Bin. "Surfactant and polyelectrolytes templated mesostructured inorganic materials." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528113.
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In this work we have explored the possibility of using surfactant/polyelectrolyte complexes as templates to synthesize inorganic mesostructured materials mainly with a film morphology. Inorganic species deposit in those regions of the films which are filled with a polymer hydrogel, surrounding the arrays of ordered surfactant micelles. This method produced thick robust films where the inorganic regions are reinforced and functionalized by the polymer, thus these materials are expected to have potential applications in separation, absorption, catalysis and chemical sensing. Initial work involved mixing silicate precursors directly into CTAB/PEI solutions to form highly ordered 2D hexagonal silica films at the air/water interface. Time resolved synchrotron SAXS allowed investigation of processes occurring in solution during the reaction, from which a film growth mechanism was proposed. Films had good thermal properties and after post-synthesis TMOS vapour treatment, retained structure upon template removal. Silica gel monoliths with various mesostructures were also rapidly fabricated in one minute with surfactant/LPEI complexes. Cat-ionic surfactant mixtures with polymers were also employed to template silica films with different cubic mesostructures at the air/water interface. The mesophases of the interfacial films were enriched due to more complicated interactions between the polymers and two surfactants. Polymer molecular weight, total composite concentration, chemical nature of the polymer as well as the cationic-anionic surfactant molar ratio was used to systematically control the silica film mesophase. Robust titania films were also prepared with cat-anionic surfactant mixtures and polymers at the air/water interface. Although the film mesostructure was lost after calcination, the in-situ and dry free-standing films display ordered cubic mesostructures and the films are stable to calcination after post-synthesis treatment. Ordered lamellar iron oxide films templated by SDS/LPEI complexes were also prepared at the air/water interface.
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Kimura, Tatsuo. "Synthesis of novel mesostructured and mesoporous materials /." Electronic version of summary, 1999. http://www.wul.waseda.ac.jp/gakui/gaiyo/2729.pdf.
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Vogel, Robert. "Dye doped mesostructured materials for optical device applications /." St. Lucia, Qld, 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17360.pdf.
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Tiemann, Michael. "Mesostructured aluminium phosphates synthesised by supramolecular structure direction." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963107097.
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Kirstein, Johanna. "Diffusion of single molecules in nanoporous mesostructured materials." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-79478.
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Xu, Shiyu. "Characterisation of mesostructured films and single zeolite nanosheets." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/characterisation-of-mesostructured-films-and-single-zeolite-nanosheets(2a2a1047-bf17-49c1-b711-120e98ac4cf2).html.
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Thin nanoporous films are attractive for many potential uses for example gas separation, catalysis, filtration of viruses, ore flotation, or as low-dielectric-constant materials. Zeolite and mesoporous materials are the two important nanoporous material classes. In this thesis, we synthesized and characterized two different thin nanoporous films; (i) mesostructured films at the mica-solution interface; (ii) mechanical exfoliated zeolites. The mesoporous materials are well-defined pore shoe and size, and exhibit various morphologies, such as thin films, etc. In contrast, zeolites are a kind of perfect crystal and the morphologies are strongly related to their structures and are difficult to control. Therefore, first we synthesis mesostructured films at mica-solution interface in acidic solution. In-situ Atomic Force Microscopy (AFM) has been used to reveal the formation process of organic and inorganic mesophase films at the molecular level. Then, we synthesized two-dimensional zeolite structures via mechanical exfoliation process that does not involve any chemical intervention and can be applicable to a wide variety of structures with different chemical makeup. Three different zeolite structure nanosheets related to the structure code MWW, UTL, and MFI have been prepared. AFM and TEM have been used to characterized the exfoliated single nanosheet. In order to broaden the application of the single zeolite nanosheet, platinum nano-clusters are encapsulated within mechanical exfoliated zeolite MFI nanosheets by ion exchange from aqueous solution of [Pt(NH3)4](NO3)2. High-angle annular dark field scanning transmission electron microscopy has been used to indicate the Pt clusters in the zeolite MFI structures. Because of the property of the mechanically as-synthesised exfoliated MFI nanosheets that is the long hydrocarbon chains are essentially intact on both sides of the inorganic layer, and can prevent thickening of the zeolite MFI nanosheets along b-axis, we use the mechanically exfoliated MFI as seeds for further growth to form large scale MFI membrane with uniform nano-thickness. Encapsulating noble metals within the channels or cavities of zeolites has already drawn numerous attentions because the well-defined zeolite structure is able to constrain the metal nanoparticle (NPs) aggregation size and enhance the diversity and activity for catalysis. We use the organic surfactant (C22-6-6Br2) and [Pt(NH3)4](NO3)2 as the structure and metal precursor to form Pt-containing nanowires; and use F- to inhibit the premature precipitation of Pt precursors. After involving F-, the Pt-containing nanowire structures were generated.
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Nagamine, Shinsuke. "Synthesis of Mesostructured Solids Templated by Surfactant Micellar Structure." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150278.
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Khimyak, Yaroslav Zenonovych. "Synthesis and characterisation of novel mesostructured and mesoporous solids." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621782.
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Park, In. "Mesostructured silica for the reinforcement of thermoset epoxy polymers." Diss., Connect to online resource - MSU authorized users, 2006.
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Zürner, Andreas [Verfasser], and Thomas [Akademischer Betreuer] Bein. "New Methods Visualizing Mesostructured Materials / Andreas Zürner. Betreuer: Thomas Bein." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2011. http://d-nb.info/1018847278/34.
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Hawley, Adrian Marcus. "Surfactant templated mesostructured titania films : a comparison of three methods." Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512325.
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The formation of thick, robust, mesoporous titania films is of particular interest and the focus of this thesis has been the study and comparison of the surfactant templated formation of such materials by three methods. film structure has been studied using TEM and small angle X-ray and neutron scattering while formation was studied using Brewster angle microscopy and X-ray and neutron reflectometry. Repetitive dip-coating was used to produce films for development into dye sensitized solar cells allowing development of cells of reasonable efficiency when four depositions were used. This research showed that repetitive deposition does not necessarily lead to a linear increase in film thickness, as subsequent depositions may be thinner making the future application of this method for solar cells problematic. In contrast to dip-coating, a fluorinated surfactant was used in a largely alcohol solvent to produce mesostructured films at the air-solution interface. Film formation occurred by a surface driven mechanism via addition of individual precursors and micelles producing a lamellar structure in-situ. After removal from the interface a cubic phase developed after drying of the film. Although films are not stable to calcination the calcined material remains porous. The surfactant templated formation of ZnO films at the air-solution interface was also studied. The di-block copolymer PEPEG2250 was also used to template titania films at the air-solution interface from alcoholic solvent. Film formation occurred via a bulk driven mechanism. Although these films were found to be disordered at the interface and not stable to calcinations they were unusually robust and self supporting after removal from the interface. Studies of subphase development allowed the first time-resolved observation of surfactant templated titania particle formation.
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Akpe, Victor. "Controlled, self-assembly of silica nanoparticles into uniform mesostructured glass." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17565.
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Making nanoparticles bind with incompatible materials is crucial to the next generation technologies. Possibilities include the inclusion of chemical or biological species into colloidal suspension of silica (SiO2) nanoparticles. This thesis explores challenges that stem from microwires produced from colloidal droplet of silica nanoparticles on a glass substrate during evaporation fabrication, including variable size dimensions and pore sizes, knowing the optimal volume of liquid droplet to add to the surface per unit area, temperature and humidity conditions, and glass surface conditions. The follow up studies focus on clarifying some of these optimal conditions in the fabrication process. Sugar and protein inclusion into silica nanostructures is also explored. Chap. 4.1 evaluates a glass substrate that gives a reproducible surface. Chap. 4.2 demonstrates the importance of surface control and drop deposition to produce a uniform nanostructured surface of silica microwire. The evaporation of liquid droplets on Au-coated and non-coated surfaces in chap. 4.3 showed that Au-coated surface retained less water than the uncoated surface of the same glass material. Superior flow behaviour of a gold-coated surface over a non-coated surface is shown. Chap. 4.4 compares the structural differences of nanostructured surfaces of microwires fabricated both below and above ambient temperatures. Chap. 4.5 recognises the phase patterns of the different nanostructured surfaces of microwires at different temperatures. Chap. 4. 6 presents preliminary studies of the inclusion of protein (protease enzyme), sugars - D-(+)-glucose and D-(+)-trehalose dihydrate into colloidal suspension of silica nanoparticles in order to generate a stable environment for protein storage.
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Corrales, Tomas P. [Verfasser]. "Local dynamics and bending mechanics of mesostructured materials / Tomas P. Corrales." Mainz : Universitätsbibliothek Mainz, 2013. http://d-nb.info/1045264318/34.
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Docampo, Pablo. "Electronic properties of mesostructured metal oxides in dye-sensitized solar cells." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:e97e90f9-47fe-4259-a462-c97f0bf81469.
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Solid-state dye-sensitized solar cells (ssDSCs) offer the possibility of high power conversion efficiencies (PCEs) of over 20%. However, after more than a decade of research, devices still barely reach over 7% PCEs. In this thesis, limitations to device performance are studied in detail, and solutions for future advancement are put forward. In the first part of the thesis, factors limiting charge generation are explored by studying the crystallization environment of mesoporous TiO2 self-assembled through block copolymers. It was found that the density and distribution of sub band gap states are a function of the synthesis conditions and critically affect the performance characteristics of the self-assembled titania used in ssDSCs. As a result, the self-assembled mesoporous oxide system presented in this thesis outperforms for the first time the conventional nanoparticle based electrodes fabricated and tested under the same conditions, with demonstrated PCEs of over 5%. In chapters 6, 7, and 8, the factors limiting the diffusion length and hence, the thickness of the fabricated devices, are carefully examined. Previous literature points towards insufficient pore-filling of the hole transporting material (HTM) as the main limiting factor. In chapter 6, a pore-filling study is shown where a new technique to evaluate the pore-filling fraction of the HTM in the conventional mesoporous metal oxide electrode is also presented and conclude that sufficient pore-filling of thick films can easily be achieved. Another usual strategy to extend the electron lifetime in the devices and thus, the charge diffusion length, involving thin film coatings of insulating metal oxides is examined in chapter 7, with satisfactory results for SnO2-based ssDSCs. The diffusion length can also be extended if the factors limiting the diffusion of charges through the device are identified and removed, as presented in chapter 8. Finally, a study on the stability of the ssDSC is presented in chapter 9. The developments achieved enable long term stability to be effectively targeted, and represent a key milestone towards commercial realization of ssDSCs.
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Sörensen, Malin Helena. "Mesostructured particulate silica materials with tunable pore size : Synthesis, characterization and applications." Doctoral thesis, KTH, Ytkemi (stängd 20081231), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10089.
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Colloidal assemblies of surfactants and polymers in aqueous solutions have been used by human mankind for hundreds of years and they are of great importance in many of our technological processes, such as fabrication of soap and papermaking. Less than two decades ago the idea of using colloidal assemblies as templates of inorganic materials was borne. A new population of materials, referred to as surfactant templated materials, took form. These materials showed extraordinary properties such as monodisperse pore size distribution, large surface areas and pore volumes. The main focus of this thesis has been on synthesis and functionalisation of spherical mesostructured silica particulate materials. In the first part of the work, mesostructured materials with expanded pores have been produced using a well established aerosol-based method as well as the newly developed emulsion and solvent evaporation (ESE) method. Increase in pore size was realized through using Pluronic block copolymer F127 together with a swelling agent poly(propylene glycol) as template. The influence of the swelling agent on pore size expansion was shown to have a roughly linear relationship. Furthermore, the impact of synthesis parameters on internal and exterior morphology has been investigated. Accessibility of the internal pore space, as well as the external surface roughness were shown to be highly dependent on synthesis temperature. Additionally, a very interesting well ordered 3D closed packed (P63/mmc) material was produced using the ionic surfactant C16TAB as template in the ESE method. In the second part of the thesis work, mesoporous spheres with large pore size, having either hydrophilic or hydrophobic surface properties, were used as carriers of an enzyme, lipase. The enzymatic activity of lipase was increased onto the hydrophobic surface, compared to lipase immobilized into the hydrophilic support as well as for lipase free in solution. This effect was probably due to a combination of enhanced hydrophobic interactions preventing denaturation of the enzyme and interfacial activation of the enzyme. This study generated an inorganic carrier material that is a promising candidate for biocatalysis applications. Additionally, mesoporous spheres were used as carriers of a model drug, Ibuprofen, to study the effect of polyelectrolyte multilayers on release properties. However, these layers were shown impermeable independent on pH and the substance was only released from uncoated particles.QC 20100811
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Kim, Jee Yun. "Data-driven Methods in Mechanical Model Calibration and Prediction for Mesostructured Materials." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/85210.
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Mesoscale design involving control of material distribution pattern can create a statistically heterogeneous material system, which has shown increased adaptability to complex mechanical environments involving highly non-uniform stress fields. Advances in multi-material additive manufacturing can aid in this mesoscale design, providing voxel level control of material property. This vast freedom in design space also unlocks possibilities within optimization of the material distribution pattern. The optimization problem can be divided into a forward problem focusing on accurate predication and an inverse problem focusing on efficient search of the optimal design. In the forward problem, the physical behavior of the material can be modeled based on fundamental mechanics laws and simulated through finite element analysis (FEA). A major limitation in modeling is the unknown parameters in constitutive equations that describe the constituent materials; determining these parameters via conventional single material testing has been proven to be insufficient, which necessitates novel and effective approaches of calibration.
A calibration framework based in Bayesian inference, which integrates data from simulations and physical experiments, has been applied to a study involving a mesostructured material fabricated by fused deposition modeling. Calibration results provide insights on what values these parameters converge to as well as which material parameters the model output has the largest dependence on while accounting for sources of uncertainty introduced during the modeling process. Additionally, this statistical formulation is able to provide quick predictions of the physical system by implementing a surrogate and discrepancy model. The surrogate model is meant to be a statistical representation of the simulation results, circumventing issues arising from computational load, while the discrepancy is aimed to account for the difference between the simulation output and physical experiments. In this thesis, this Bayesian calibration framework is applied to a material bending problem, where in-situ mechanical characterization data and FEA simulations based on constitutive modeling are combined to produce updated values of the unknown material parameters with uncertainty.Master of Science
A material system obtained by applying a pattern of multiple materials has proven its adaptability to complex practical conditions. The layer by layer manufacturing process of additive manufacturing can allow for this type of design because of its control over where material can be deposited. This possibility then raises the question of how a multi-material system can be optimized in its design for a given application. In this research, we focus mainly on the problem of accurately predicting the response of the material when subjected to stimuli. Conventionally, simulations aided by finite element analysis (FEA) were relied upon for prediction, however it also presents many issues such as long run times and uncertainty in context-specific inputs of the simulation. We instead have adopted a framework using advanced statistical methodology able to combine both experimental and simulation data to significantly reduce run times as well as quantify the various uncertainties associated with running simulations.
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Sörensen, Malin Helena. "Mesostructured particulate silica materials with tunable pore size : synthesis, characterization and applications /." Stockholm : Skolan för kemivetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10089.
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Kustra, Joanna. "Elaboration of micro and mesostructured sol-gel materials using polysilsesquioxane molecular precursors." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1081/document.
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Le projet de thèse a pour but de synthétiser de nouveaux matériaux siliciques à microstructure contrôlée en utilisant des procédés de polycondensation à basse température, et de développer de nouvelles approches de microfabrication 3D à haute résolution par excitation bi-photonique d’une formulation sol-gel. La synthèse de matériaux microstructurés est ici centrée sur le procédé sol-gel, impliquant des réactions d’hydrolyse-polycondensation. Les mtériaux les plus étudiés par ces approches en particulier dans le cadre d’un contrôle de la porosité sont préparés à partir de tetraéthoxide de silicium (TEOS)/ Le matériau est structuré généralement par des agent moléculaires structurants (« templates ») tels que les composés tensioactifs. Ces derniers sont en général éliminés, après condensation des silanols, par traitement thermique ou lavage afin de libérer la porosité et générer la structuration. Cette étape d’élimination des agents structurants est souvent problématique, en particulier au niveau industriel, car elle utilise soit des hautes températures, soit des quantités importantes de solvants. Il y a un enjeu important à développer des approches de microstructuration s’affranchissant de ces agents moléculaires structurants, cela représentant le principal objectif de cette thèse.Deux stratégies sont abordées aux cours de ce travail de recherche. La première implique l’utilisation de précurseurs organosilylés donc la structure moléculaire permet une microstructuration du matériau synthétisé. Cette partie explore l’utilisation de précurseurs de la famille des silsesquioxanes et leur transformation vers les matériaux. La deuxième approche propose d’évaluer pour la première fois l’utilisation de l’excitation biphotonique pour contrôler l’étape de condensation sol-gel par modification de pH au point focal d’un laser et ainsi apporter une résolution micrométrique à la structuration du matériauThe main goal of this research was the synthesis of new siliceous materials with controlled microstructures, using low-temperature polycondensation process, and develop the new approach towards 3D microfabrication under two-photon excitation of a sol-gel formulation. Synthesis of microstructured materials is based on the sol-gel process, i.e. hydrolytic polycondensation. Most known siliceous materials with controlled microstructure are synthesized from tetraethoxysilane (TEOS). The materials are generally structured by structuring molecular agents ("templates") such as surfactant compounds, which are then removed by heat treatment or washing with appropriate solvents. This stage of removal of structuring agents is often problematic, particularly at the industrial level, because it uses either high temperatures or large amounts of solvents. Therefore, new methods to obtain materials with controlled porosity without the need to use templates are still being developed. Two strategies are discussed during this research work. First one involved the use of organosilicon precursors with a define structure that at molecular level modify the structure of the final materials. The use of well-defined precursors (silsesquioxanes), in appropriate proportions, allows the control of the porosity of the obtained silica materials. The second approach investigated in this work is the local photo-induced structuration of silicon based pre-hydrolyzed precursors under two-photon excitation allowing high 3D resolution
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CARA, CLAUDIO. "Siliceous and non-siliceous mesostructured iron oxide nanocomposites for H2S removal from syngas." Doctoral thesis, Università degli Studi di Cagliari, 2018. http://hdl.handle.net/11584/255985.
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This thesis is devoted to give a contribution to develop new mesostructured iron oxide-nanocomposites for sulphur compounds removal in view of possible applications in syngas purification from coal at mid-temperature. Even if coal is considered one of the main source of carbon dioxide production, the combination of gasification technologies with Carbon Capture and Sequestration (CCS) could in principle solve this main drawback and make coal still an appealing feedstock for hydrogen, energy, liquid fuels, fertilizers and chemicals production. In this framework, the key challenge is the effective purification of the sour syngas, which is usually carried out at low temperatures (around 50°C), leading to losses in the energy efficiency of the plant. Technologies to clean at temperatures between 300 °C and 600 °C (mid-temperature range) have been investigated in order to sort this issue out. Mesostructured metal oxide-based nanocomposites, can be proposed as potential removers in this specific range of temperatures due to their promising features and thermal stability. They consist of a mesostructured inert support able to disperse homogeneously the active phase and iron oxide chosen as active phase due to their fast kinetics and favourable thermodynamics of the reaction with H2S, as well as for their low cost and no toxicity. The use of an inorganic mesostructured materials with different textural properties (surface area, pore size and pore structure) and chemical nature (amorphous silica or crystalline titania) as a host for iron oxide nanoparticles can provide an effective way to tailor their features in terms of phase, size and size distribution and to control its dispersion. The correlation between the textural and structural properties of the nanocomposites with their performances has allowed to get new insights for the development of novel more and more efficient H2S sorbents.
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Holdaway, James. "A study of the structure and formation of biocompatible mesostructured polymer- surfactant hydrogel films." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648942.
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The aim of this work has been to investigate the formation of films and to couple their properties with the bulk behaviour of the film forming components. The primary goal was to improve the biocompatibility of the films, as films are of great interest to the biomedical industry. The investigated films form spontaneous at an air-water interface and some are robust enough to be removed from the surface. The films are formed by mixed surfactants of the cationic CTAB and the zwitterionic SB3-14 together with the polymer PEI, in a short and long form. The film structures are investigated with varying CTAB:SB3-14 ratio. It was found replacing CTAB with SB3-14 reduced mesostructure in the films, however when PEI was used to form the films in its long form there was sufficient polymer network to kinetically trap mesostructure in the films. To increase biocompatibility, CTAB was replaced with calcium chloride to emulate the cationic charge and present opportunites for complex formation with the polymers. SB3-14 was still present as the surfactant to impart mesostructure with PEI as the polymer. Here it was found that mesostructure could be controlled with calcium chloride concentration due to its hygroscopic nature modulating the amount of water in the films and therefore the resulstant mesophases. Finally, anionic biopolymers were investigated with the spray coated films. Here it was found that they complexed with calcium chloride more fully than PEI and thus the competition between calcium chloride and SB3-14 for water resulted in more hydrated mesophases than when PEI was used as the film forming polymer. The bulk solutions and films were investigated mainly with small angle scattering and reflectivity techniques. It was found that as a progression to previous work in the research group that more biocompatible methods could be used to form structured films.
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MUREDDU, MAURO. "Mesostructured metal oxide-based nanocomposites as sorbents for H2S removal from syngas coal gasification." Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266555.
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Desulphurization of gas phase sulphur compounds has been receiving dramatic attention since
hazardous, corrosive, and toxic gases that cause environmental damages (especially acid rain) and
industrial challenges (i.e., corrosion of equipment and deactivation of catalysts).
This dissertation presents results of R&D efforts to develop efficient MeOx/SBA-15-based sorbents
for H2S removal in view of possible applications in hydrogen purification, air pollution control, and deep
desulphurization of fossil fuels. It is precisely in the latter topic that the research project was born. The
production of power, fuels and chemicals in most countries is predominantly based on oil and, to a minor
extent, on natural gas. It is well-known that the reserves of both of these fuels are limited to a range of
40, 60 years. On the contrary, coal is a widely available fossil fuel, and it is expected to last for about
230 years. The imminent oil production limitations and the longer availability of coal, the wish to improve
the security of the energy supply, and the possibility to reduce greenhouse gas emissions by means of
carbon capture and sequestration (CCS) are sufficient motivations to increase the use of this resource.
Integrated Gasification Combined Cycle (IGCC) process is a high efficiency power generation technology
which gasifies coal to generate the fuel (syngas) for a high efficiency gas turbine. A key challenge for
producing clean power or hydrogen via gasification is cost effective purification of the sour syngas.
There are many commercial treatment techniques that are used to remove H2S, but their disadvantage is
that hot coal gas must be cooled down near to ambient temperature for desulphurization. The cooling
equipment required, and the need to reheat the clean syngas before its use in a gas turbine result in
economic and thermodynamic penalties that decrease the efficiency of a gasification plant. It is for this
reason that hot gas desulphurization technique has attracted more and more attention due to the fact
that it can reduce H2S down to 100 ppm level and avoid heat loss. Mid-temperature desulphurization is
achieved by the use of solid sorbents such as oxides of those metals that form stable sulphides, based on
the non-catalytic reaction between a metal oxide and hydrogen sulphide. The optimum desulphurization
temperature has been recommended in the range of 300 to 450 °C, also in according to the more
favourable thermodynamic equilibrium of sulphur compounds removal. To accomplish this task, Zinc
oxide- and Iron oxide-based materials have been successfully employed for decades in different domains
of the chemical industry. The pure metal oxides used as sorbents, however, suffer from evaporation, loss
in the surface area and porosity due to sintering and mechanical disintegration that affect their
performance and life time adversely. With the purpose of overcoming this problem and to improve their
performance, metal oxides can be confined into a support, where under such conditions the materials
are stable. The main properties required for support materials are inertness, high surface area, large
pores and good mechanical strength.
The thesis reports some simple and versatile routes which can be proposed to prepare a great
variety of MeOx/SBA-15 composites where the mesostructured SBA-15 silica, a high-surface area (up to
1000 m2/g) material, with 6–7 nm-wide regular channels and thick (3–4 nm) pore walls has been used as
efficient and stable support. MeOx active phase, formed inside the mesochannels, can reach the maximum
size of 6-7 nm physically imposed by the pore diameter. Such a structure provides an ideal reactor
where the mesopores act as channels for the transport of reactant. As a consequence, enhancement of
the active phase reactivity might be expected. The proposed “Two-solvents” incipient impregnation
method is easily reproducible and easy to scale up. Furthermore, this method should provide, at least in
principle, ideal systems to be compared, and therefore to understand how the active phase nature
influence their performance.
For the first time, a careful comparative study on the effect of the different nature of the
nanostructured MeOx (Me = Zn, Fe) dispersed into a mesostructured silica matrix (SBA-15) on the H2S
removal performance is carried out.
The behaviour of the MeOx/SBA-15 composites in the removal of H2S is investigated in a fixed-bed
reactor and compared with that of an unsupported ZnO commercial sorbent. The morphological,
structural, and textural features of fresh, sulphided, and regenerated sorbents have been assessed by a
multi-technique approach, including the study of the possible interactions between the guest oxide and
the host silica support. Furthermore, the sorption-desorption behaviour, which is commonly justified only
on the basis of the different nature of the active phase and of the textural features (surface area and
pore volume), is discussed also considering the morphology and the crystallinity of the active phase.
In the literature, to our best knowledge, no one have reported similar correlations. For this reason
this work can give an important contribution to improve the basic knowledge in the field of sorbents for
gas-removal.
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Zhang, Kun. "Mesostructured porous materials : Pore and surface engineering towards bio-inspired synthesis of heterogeneous copper catalysts." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2008. http://tel.archives-ouvertes.fr/tel-00310153.
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Le contrôle fin de la structure et de la chimie de surface en milieu confiné a été développé dans des silices poreuses mésostucturées de type MCM-41 pour synthétiser des catalyseurs hétérogènes combinant confinement moléculaire, hydrophobicité et spécificité de sites à l'instar des métalloprotéines. La surface considérée comme lisse a en fait une rugosité de type alvéolaire due à l'empreinte de la tête ammonium du tensioactif de synthèse. Pour des températures croissantes du traitement hydrothermal, la taille des mésopores augmente par érosion de cette rugosité puis diminue par épaississement des parois. On a aussi trouvé des conditions de synthèse de zéolihes mésoporeuses avec une micro- et mésoporosité hiérarchisée. Ces surfaces sont polyfonctionnalisées grâce à la technique de pochoir moléculaire pour isoler des fonctions bidentatés aminoéthylaminopropyles par des groupements hydrophobes triméthylsimyles. Les ions cuivriques sont alors retenus dans le matériau par complexation à ces fonctions diamino.
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Schöbel, Judith [Verfasser], and Andreas [Akademischer Betreuer] Greiner. "Block Copolymer Micelles as Efficient Templates for Mesostructured Hybrid Materials / Judith Schöbel ; Betreuer: Andreas Greiner." Bayreuth : Universität Bayreuth, 2018. http://d-nb.info/115963310X/34.
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Archer, Jared Rausch. "Synthesis, characterization, and application of thin films and mesostructured materials using self-assembled surfactant templates." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1111694248.
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Archer, Jared Rausch. "Synthesis, characterization, and application of thin films and mesostructured materials using self-asssembled surfactant templates." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1111694248.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xvi, 161 p.; also includes graphics (some col.). Includes bibliographical references (p. 155-161). Available online via OhioLINK's ETD Center
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Crosman, George Adrian. "Immobilization of Rh-diphosphine complexes on mesostructured materials and their application to asymmetric hydrogenation and hydroboration." Aachen Shaker, 2009. http://d-nb.info/999464981/04.
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Zhou, Wen-Juan. "Polyamine and Schiff base metal complexes incorporated in mesostructured templated porous silicas : tentative application in selective oxidation." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2009. http://tel.archives-ouvertes.fr/tel-00533599.
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De nouveaux matériaux ont été conçus à partir de matériaux hybrides organique-inorganiques mésoporeux renfermant des complexes de Cu(II). Ils ont été mis en œuvre comme catalyseurs dans des réactions d'oxydation sélective. La localisation des sites du métal a été contrôlée en utilisant trois ligands synthétiques le type organosilane et deux stratégies différentes, c. àd.,une synthèse dite "one-pot", et un greffage post-synthètique. Les organosilanes ont été le N-(2-aminoéthyl)-3-aminopropyltriméthoxysilane (L1), le N-propylamine-salicylaldimine-triméthoxy-silane (L2) et le de N-(salicylaldimine)- (N'-propyltriméthoxylsilane)-diéthylènetriamine (L3). En outre, l'ion Ni(II) a été utilisé comme sonde structurale. Selon la synthèse "one-pot", les complexes Ni(II)-L1, Cu(II)-L1 et Cu(II)-L2 ont été co-condensés avec du silicate de sodium en présence d'un tensoactif, le cé-tyltriméthylammonium tosylate. Ce dernier avait le rôle de gabarit structurant pour la cons-truction d'organosilices mésoporeuses périodiques (PMOs), de structure bien ordonnée de type MCM-41. Ces matériaux ont ensuite été soumis à des traitements mis au point pour pré-server la structure mésoporeuse utilisant un mélange de chlorotriméthylsilane et hexaméthyl-disilazane ou une quantité appropriée de HCl aqueux (lavage) pour extraire le tensio-actif. Dans les greffages post synthétiques, les complexes Ni(II)-L1, Cu(II)-L1 ou Cu(II)-L3 ont été liés de façon covalent à la surface de silice mésoporeuse préformée selon une distribution uniforme mettant en œuvre une technique dite de pochoir moléculaire. Une caractérisation multitechnique approfondie fut mener pour vérifier la structure et la morphologie du matériau et pour déterminer le site de coordination du métal (XRD, TEM, isothermes d'adsorp-tion-désorption d'azote, analyse élémentaire, ATG, spectroscopies DRUV, FT-IR et RPE). De plus, l'accessibilité chimique du site métallique et le relargage du métal ont été testés en utili-sant 1) l'isothiocyanate (SCN-) comme ligand sonde, 2) l' échange des ions Ni(II) par les ions Cu (II) d'ions ou encore 3) la résistance à la lixiviation acide. Outre les sites métalliques des canaux obtenus par greffage et trés ressemblant à des sites "en solution", deux autres sites ont été mis en évidence. Ils sont tous les deux situés dans les murs des pores. L'un non accessible, est appelé “site enlisé”, l'autre est “site émergenant”. L'activité catalytique en hydroxylation du phénol par le peroxyde d'hydrogène et oxydation du catéchol par le dioxygène dépend de la localisation du métal. Les complexes Cu(II)-L3 greffés présentent les meilleures activités catalytiques et fonctionnent dans l'eau. La conversion et la sélectivité en produits valorisables comme le catéchol et l'hydroquinone, ont été étudiées en fonction du temps, de la température, du pH et du rapport substrat /oxydant. Enfin, le recyclage du catalyseur a également été étu-dié.
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Crosman, George A. [Verfasser]. "Immobilization of Rh-diphosphine complexes on mesostructured materials and their application to asymmetric hydrogenation and hydroboration / George A Crosman." Aachen : Shaker, 2009. http://d-nb.info/1124365893/34.
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Park, Seok Chan. "Single molecule tracking studies of flow-aligned mesoporous silica monoliths: pore order and pore wall permeability." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/35731.
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Doctor of PhilosophyDepartment of Chemistry
Daniel A. Higgins
This dissertation describes single-molecule tracking (SMT) studies for the quantitative characterization of one-dimensional (1D) nanostructures in surfactant-templated mesoporous silica monoliths prepared within microfluidic channels. Single molecule diffusion of fluorescent probe molecules within the cylindrical mesopores reflects microscopic morphologies and mass-transport properties of the materials with high temporal and spatial resolution. The pore organization and materials order are initially investigated as a function of sol aging prior to loading into the microfluidic channels. Mesopores in these materials are templated by Cetyltrimethylammonium bromide (CTAB). Wide-field fluorescence videos depict 1D motion of the dyes within the individual mesopores. Orthogonal regression analysis of these motions provides a measure of the mesopore orientation. Channels filled prior to gelation of the sol produce monoliths incorporating large monodomains with highly aligned mesopores. In contrast, channels filled close to or after gelation yield monoliths with misaligned pores that are also more disordered. Two-dimensional (2D) small angle X-ray scattering (SAXS) experiments support the results obtained by SMT. These studies help to identify conditions under which highly aligned mesoporous monoliths can be obtained and also demonstrate the utility of SMT for characterization of mesopore order. The non-ionic surfactant Pluronic F127 is also utilized as the structural-directing agent. The diffusive motions of PDI dyes that are uncharged, cationic and anionic are explored by SMT and fluorescence correlation spectroscopy (FCS). The SMT studies for the uncharged dye show development of 1D diffusion along the flow direction while charged dyes exhibit predominant isotropic diffusion, with each of these behaviors becoming more prevalent as a function of aging time after filling of the microfluidic channels. SMT studies from silica-free F127 gels suggest that partitioning plays a important role in governing the diffusion behavior of the PDI dyes within the surfactant-filled mesopores. FCS results exhibit similar mean diffusion coefficients for all three dyes that suggest these dyes diffuse through similar sample regions. These studies demonstrate that the silica pore walls in the mesoporous silica monoliths remain permeable after gelation and that partitioning of solute species to different regions within the pores plays an important role in restricting the dimensionality of their diffusive motion
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Costacurta, Stefano. "Mesoporous films obtained by supramolecular self-assembly and their characterisation by advanced techniques." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425017.
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Mesoporous films are characterised by the presence of ordered porosity in the 2 to 50 nm range. These systems are extremely interesting from a technological viewpoint due to the very high specific surface area (on the order of 1000 m^2/g) and the possibility to tune important parameters such as chemical composition, pore size and shape, pore accessibility. This doctorate work was aimed at the study on mesoporous thin films, a goal that has been tackled following two directions. The first goal was to promote a basic study on the synthetic and processing parameters through which mesoporous films are obtained: for example, using different precursors in order to vary the chemical composition of the films and modify physical parameters such as pore size and shape. The second direction followed in this work was to pursue an explorative study regarding applications of mesoporous coatings, for example for hierarchical multiscale porosity materials and in patterning of mesoporous thin films. Whilst dealing with these subjects, advanced characterisation techniques using synchrotron radiation were developed for the basic study of mesoporous films.
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Alvarado, Perea Leo [Verfasser], Andreas [Akademischer Betreuer] Seidel-Morgenstern, and Franziska [Akademischer Betreuer] Scheffler. "Direct conversion of ethene to propene on Ni-alumino-mesostructured catalysts : synthesis, characterization and catalytic testing / Leo Alvarado Perea. Betreuer: Andreas Seidel-Morgenstern ; Franziska Scheffler." Magdeburg : Universitätsbibliothek, 2014. http://d-nb.info/1054638403/34.
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Alvarado, Perea Leo [Verfasser], Andreas Akademischer Betreuer] Seidel-Morgenstern, and Franziska [Akademischer Betreuer] [Scheffler. "Direct conversion of ethene to propene on Ni-alumino-mesostructured catalysts : synthesis, characterization and catalytic testing / Leo Alvarado Perea. Betreuer: Andreas Seidel-Morgenstern ; Franziska Scheffler." Magdeburg : Universitätsbibliothek, 2014. http://d-nb.info/1054638403/34.
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Baffert, Mathieu. "Synthesis of ruthenium complexes having one or more N-heterocyclic carbene ligands supported on hybrid mesostructured silicas and their use in the hydrogenation of carbon dioxide." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00838661.
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The goal of this PhD was to elaborate supported Ru-NHC catalytic materials based on hybrid organic-inorganic materials having imidazolium units perfectly distributed within a silica matrix. Passivation of these imidazolium materials followed by formation of NHC-carbene and reaction with [RuCl2(p-cymene)]2 provided these well-defined surface sites of general structures RuCl2(NHC)(L), where L was para-cymene (p-cymene) or THF depending on the reaction conditions, which could be further replaced by PMe3. These systems were then tested in the hydrogenation of CO2 in presence of amine to give formamides. The mono-NHC systems were highly active only in the presence of PMe3 ligands, but suffered from Ru leaching, evidencing the low stability of the NHC-Ru bond under the reaction conditions. On the other hand, dinuclear bis-NHC Ru systems were also developed, and they displayed much improved activity and stability in the hydrogenation of CO2 in the presence of PMe3 compared to the mono-NHC systems. This allowed the use of much higher reaction temperatures (200 °C) and provided heterogeneous catalysts with performances close to those obtained with the best homogeneous catalysts, Cl2Ru(dppe)2.
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Adeyeye, Adekunle Olusola. "Magnetic mesostructures." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627615.
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Nykl, Scott L. "Interactive Mesostructures." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1382459151.
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Lopes, Silva Susana. "Développement de nouveaux catalyseurs d'hydrotraitement basés sur l'encapsulation d'hétéropolyoxometallates dans des silices mésostructurées : application à la production de carburants propres." Thesis, Lyon, École normale supérieure, 2013. http://www.theses.fr/2013ENSL0799/document.
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Le développement de technologies plus propres et économes en énergie amène aujourd’hui l’industrie du raffinage à modifier ses stratégies de préparation de catalyseurs et à se tourner vers l'utilisation plus massive de catalyseurs hétérogènes plus actifs, sélectifs, stables et régénérables.Récemment une méthode originale a été développée par Dufaud et al. (J. Mater. Chem., 2009, 19, 1142-1150) pour encapsuler des polyoxométallates (POMs) dans les murs des silices mésoporeuses. Le projet de thèse a visé l’élaboration de nouveaux catalyseurs basés sur cette nouvelle méthodologie qui devrait conduire à des systèmes à haute teneur en métal actif Mo/W bien dispersé, avec une meilleure proximité spatiale entre le Mo/W et son promoteur. Afin de mettre en évidence cette proximité, différentes voies ont été envisagées :i) synthèse en deux étapes comportant l'encapsulation des POMs dans les murs de SBA-15, suivie d’une imprégnation à sec des promoteurs (Ni(NO3)2 ou Co(NO3)2)ii) synthèse en une seule étape comportant l'imprégnation à sec de POMs substitués Co3PCoMo11O40H, Ni3PNiMo11O40H, Co3/2PMo12O40 ou Ni3/2PMo12O40 iii) préparation traditionnelle par co-Imprégnation à sec d’une silice SBA-15 par une solution de POMs et Ni(NO3)2 ou Co(NO3)2, afin de mettre en évidence non seulement l'intérêt de la nouvelle méthode de préparation mais aussi le gain lié à l'utilisation de supports de type SBA-15 (par rapport aux supports aluminiques conventionnels) ayant des caractéristiques texturales aussi remarquables. L’effet du traitement de sulfuration sur ces solides a été étudié et l’évaluation des propriétés catalytiques de ces matériaux a été réalisée sur des molécules modèles en hydrogénation du toluène, hydrodésulfuration du thiophène et du 4,6-DMDBT. A partir des résultats obtenus, une des stratégies de synthèse a été optimisée, en vue de l'élaboration de matériaux encore plus actifsEconomic growth in the developing countries over the past decade has increased the global demand for crude oil. It is projected that the global crude slate will become sourer, with a sulfur content above 1.3 wt%. An overall aim of policymakers is thus to ensure that transportation fuels do not surpass a sulfur content of 10 ppm. Several solutions are possible to achieve the nowadays goals, that affect either the process or the catalyst. The latter solution, which does not involve significant additional costs for refiners, is therefore the most studied. One way to improve the nowadays catalysts would be to increase the content of active metal (eg cobalt and molybdenum in the case of CoMo systems). Nevertheless, at higher metal loadings, the formation of refractory species such as CoMoO4 or Co3O4 by sintering during calcination and/or sulfidation steps has been reported for alumina-Supported catalysts. This PhD project is based on the development of new hydrotreating catalysts, through a 2-Step one-Pot method : synthesis of polyoxometalates-Containing mesoporous SBA-15 materials, followed by incipient wetness impregnation of active phase promoter. The encapsulation of these species within the silica matrix would prevent the agglomeration of large particles during sulfidation reactions and could thus lead to systems with high content of active metal well dispersed over the support. One aim of this study was to evaluate the potential of these catalysts in the hydrotreating of several feedstocks, such as diesel oil, gasoline or vegetal oil. A second objective was the understanding of the nature of the different interactions between the active phase precursors and the support, according to each preparation technique.The non-Promoted hybrid catalyst showed a better dispersion of the metallic phase in the oxide state, compared to the catalysts prepared by incipient wetness impregnation, which can be correlated with stronger interactions between encapsulated POM and silica functionalities, such as siloxanes and silanols, as evidenced by Raman spectroscopy. However, the wide-Angle XRD showed the presence of MoO3 crystallites. HRTEM analyzes of the sulfided catalysts showed different species on this catalyst: small MoS2 slabs and metal particles (∼ 1 nm) mainly in the walls but also on the surface of pores; curved MoS2 slabs at mesopores surface leaving the entrance of the pore free; MoS2 hanks blocking the pores.This catalyst showed a relatively low sulfidation rate (determined by XPS), which could be associated with the presence of refractory species already present before activation. Thus, the toluene conversion represented per MoS2 clearly showed the interest of the catalyst prepared by this innovative method, presenting an intrinsic activity two-Fold higher than that of the catalyst prepared by dry impregnation.The subsequent impregnation of the active phase promoter of the hybrid catalyst (Pr(NO3)2, Pr = Ni or Co; 4
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Perrot, Alexandre. "Revêtements sol-gel incorporant des particules mésostructurées actives élaborées par aérosol pour la protection contre la corrosion des alliages d’aluminium aéronautiques." Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066744.
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L’objectif de ce travail de doctorat est de remplacer les systèmes anticorrosion de références incorporant des sels de chromes hexavalents cancérigènes par des films sol-gel chargés en particules aérosols actives. Notre stratégie de protection vise à incorporer des particules aérosols encapsulant des inhibiteurs de corrosion dans une matrice hybride mésostructurée au contact de l’alliage laquelle est recouverte d’une couche hybride barrière. Cette dernière a pour objectif d’empêcher les espèces chimiques impliquées dans l’initiation de la corrosion (Cl- et H2O) d’arriver jusqu’au substrat apportant ainsi une protection passive contre la corrosion. En cas de rupture de ce film passif les particules Aérosols doivent libérer des inhibiteurs de corrosion lesquels peuvent diffuser dans la couche mésostructurée jusqu’aux zones d’attaques ou ils forment un film passif insoluble qui provoque l’arrêt des réactions de corrosion conférant ainsi au substrat une protection active. La séparation spatiale de ces deux actions permet de s’affranchir du nécessaire compromis entre diffusion des inhibiteurs et effet barrière que l’on retrouve dans les systèmes de référence permettant ainsi de maximiser l’efficacité anticorrosion. Des particules aérosols mésostructurées ont dans un premier temps été obtenues par atomisation-séchage via différentes voies de catalyses. Ces dernières ont ensuite été chargées à différents taux en 8-HQ et BTA, deux inhibiteurs de corrosion organiques. Les particules chargées ont enfin été incorporées dans différents films sol-gel de manière à mettre en lumière leur effet actif sur la corrosion. L’efficacité anticorrosive des différents matériaux mis en forme a été évaluée par Spectroscopie d’Impédance Electrochimique et Brouillard Salin NeutreThe aim of this PhD is to replace anticorrosion protection coatings containing carcinogenic hexavalent chromium by hybrid sol-gel films containing active aerosol particles. Our protection strategy is to incorporate aerosol particles loaded with corrosion inhibitors within a mesostructured hybrid layer on top of the substrate, covered by a hybrid barrier top layer. This layer’s goal is to prevent chemical species associated with corrosion initiation (Cl- et H2O) to diffuse to the alloy thus providing a passive protection. In case of film cracking aerosol particles release their corrosion inhibitors which can diffuse through the mesostructure of the film to corrosion sites where they form a passive insoluble film which stops corrosion reactions thus providing an active protection. Spatial separation between those two different actions allows us to overcome the necessary compromise found in reference corrosion protection systems between inhibitor diffusion and barrier effect thus maximizing anticorrosion efficiency. Aerosol mesostructured particles were obtained by spray drying using different catalysts. They were later charged with two organic corrosion inhibitors 8-HQ and BTA with variable loadings. Loaded particles were then incorporated within different sol-gel films in order to demonstrate their active effect on corrosion. Anticorrosion efficiency of those different materials was evaluated through electrochemical impedance spectroscopy and salt spray test
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Harvey, Michael D. "Hybrid material systems for micro-optical devices : the synthesis and characterisation of dye doped mesostructured TiO2, low refractive index mesoporous SiO2 and the analysis of thin films made thereof /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19323.pdf.
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Mueller, Andre. "Designer 3D magnetic mesostructures." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558883.
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Micro Hall probe magnetometry has been used to investigate the magnetisation of various electrodeposited microcrystals. Superconducting tin crystals of almost perfect square cuboid shapes exhibit a strong size dependence of the supercooling of the superconducting state and, for the smallest accessible crystals, the crossover to the mesoscopic regime can be readily explored close to their critical temperatures. Experimental results are in good agreement with Ginzburg-Landau simulations using the exact experimental parameters. Electroplating of the tin cores with another material provides unique core-shell structures of either two superconductors (S-S’: tin-lead) or of a superconducting core, covered with a ferromagnetic shell (S-F: tin/lead-nickel). The critical parameters of the tin core in Sn-Pb core-shell crystals are considerably enhanced and superconductivity in the tin core is detected up to 1:16 TSn c . Little-Parks oscillations in the shell can be analysed to reveal the extent of the superconducting sheath and hence can be utilised to measure the range of the proximity effect close to the critical temperature of the shell. In S-F core-shell structures, field cancellation effects govern the overall behaviour. Under certain conditions it was possible to switch the overall magnetic response from para(ferro-)magnetic to diamagnetic and back at finite applied fields. Micromagnetic simulations qualitatively reproduce the experimentally observed effects. Applications for the core-shell structures include magnetic guidance or memory devices.
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Alabi, Akinleye Christopher Grubbs Robert H. Davis Mark E. "I. Synthesis and proton conductivity studies of mesostructured organosilicates and bitriazole-polymer composites ; II. Targeted nanoparticles for siRNA delivery /cChristopher Akinleye Alabi ; Robert H. Grubbs, committee chair ; Mark E. Davis, advisor." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-05262009-145437.
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Nykl, Erik L. "Point Cloud Mesostructure Impostors." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou151214093467185.
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Faul, C. F. J. (Charles Frederick James). "Directed synthesis of polymer mesostructures." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51729.
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Thesis (PhD)--Stellenbosch University, 2000.ENGLISH ABSTRACT: The objective of this research was to produce discrete, nano-shaped polymeric structures on the same length scale as, or one to one copies of, templates, deformable templates or structure-directing hosts. Polymerisation of hydrophobic organic monomers in high concentration surfactant solutions, leads to the formation of shaped particles (rod-like, plank-like and ribbon-like particles) in the micrometer size range. The origin of these regularly shaped particles was investigated. It is proposed that they were not polymeric in nature, but formed by the crystallisation of the surfactant in the presence of electrolytes and ethanol as solvent. The polymeric particles that were formed were found to be of spherical shape, and no directing of the shape was detected. Mesostructured hosts were then investigated for their possible use as structure-directing agents. A series of polyelectrolyte-surfactant complexes of polydiallylammonium chloride with sodium sulphate surfactants (ranging from C10 to C16) were synthesised and characterised in terms of their thermal, mechanical and structural properties. The complex of polydiallylammonium chloride and sodium dodecyl sulphate was selected as an appropriate self-assembled model system for investigations into the structure-directing properties of these new materials. The polymerisation of hydrophobic organic monomers, such as styrene and the di-functional monomer m-diisopropenylbenzene (m-DIB), within the above mesoscopically structured polyelectrolyte-surfactant complex as host, lead to the formation of unconventionally shaped polymeric particles. The influence of the presence of monomers and guest polymers on the phase morphology of the host was investigated by small angle X-ray analyses (SAXS) and dynamic mechanical analyses (DMA). SAXS analyses showed that these new, stable hosts can hold up to 17 % guest polymer before phase disruption is encountered. These findings were supported by changes in the mechanical properties, as determined by DMA. The transmission electron microscopy (TEM) images of particles obtained after polymerisation showed very clearly that the poly-(m-DIB) did not form a continuous copy of the 3D hexagonal structure of the host, but rather colloidal copies of a part of the host structure that swelled the most. The shapes of the polymer mesostructures were dictated by the morphology of the phase of the structure-directing host, to produce nanosized wires (dimensions 4 by 100 nm), cigar-shaped particles (dimensions 8 by 50 nm) and fibrillar bent shapes (larger than 200 nm), as revealed by TEM. According to literature these are the first shaped, polymer nano-particles produced in a soft, selfassembled, organic templating host.
AFRIKAANSE OPSOMMING: Die doel van hierdie navorsing was om diskrete, nano-gevormde polimeriese partikels van dieselfde lengteskaal as, of direkte een tot een kopië van, 'n templaat, 'n vervormbare of struktuur-rigtende gasheersisteem te produseer. Die polimerisasie van hidrofobiese organiese monomere in seep oplossings van hoë konsentrasie, het gelei tot die produksie van gevormde partikels. Die oorsprong van hierdie partikels is ondersoek. Dit word voorgestel dat die partikels nie polimeries van aard is nie, maar gevorm is deur die kristallisasie van die seep in die teenwoordigheid van elekotroliete en etanol as oplosmiddel. Die polimeriese partikels wat wel geproduseer is, was sferies in vorm, en geen rigtende invloed op die vorm van die partikels is waargeneem nie. Meso-gestruktureerde gasheersisteme is ook ondersoek vir moontlike gebruik as struktuur-rigtende agente. 'n Reeks poliëlektroliet-seep komplekse van polidiallielammoniumchloried en natriumsulfaat sepe (van C10 tot C16) is gesintetiseer en gekarakteriseer in terme van hul termiese, meganiese en strukturele eienskappe. Die kompleks van polidiallielammoniumchloried en natrium dodekielsulfaat is gekies as 'n toepaslike self-organiserende modelsisteem vir die ondersoeke na die struktuur-rigtende eienskappe van hierdie nuwe materiale. Polimerisasie van hidrofobiese organiese monomere, soos byvoorbeeld stireen en die di-funksionele monomeer m-di-isopropenielbenseen (m-DIB), in hierdie mesoskopies-gestruktureerde poliëlektroliet-seep kompleks, het gelei tot die vorming van nie-konvensionele gevormde polimeriese partikels. Die invloed van die teenwoordigheid van monomere en gaspolimere op die fasemorfologie van die gasheersisteem is ondersoek d.m.v. kleinhoek X-straal diffraksie (Eng. SAXS) en dinamiese meganiese analise (DMA). SAXS analises het aangetoon dat hierdie nuwe, stabiele gasheersisteem tot 17 % gaspolimeer kan inkorporeer voordat fasevernietiging plaasvind. Hierdie resultate is verder ondersteun deur veranderinge in die meganiese eienskappe soos waargeneem deur DMA. Transmissie elektronmikroskopie (TEM) afbeeldinge van partikels geïsoleer na polimerisasie het baie duidelik gewys dat, in die geval van poli-(m-DIB), die gaspolimeer nie 'n kontinue kopie van die drie dimensionele heksagonale struktuur van die gasheersisteem produseer nie. Daar word eerder 'kolloïdale kopieë' van dele van die gasheersisteem wat die meeste swel gevorm. Die vorms van die polimeer mesostrukture word dus bepaal deur die morfologie van die fase van die struktuur-rigtende gasheer, om nanogrootte draadjies (dimensies 4 x 100 nm), sigaarvormige partikels (8 x 50 nm) en fibrillêre gebuigde vorms (groter as 200 nm) te vorm, soos waargeneem met TEM. Volgens die literatuur is hierdie die eerste geval van gevormde polimeer nanopartikels geproduseer in 'n self-organiserende templaat gasheersisteem.
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Ho, Christopher Sui-keung. "Mesostructure quantification of fibre-reinforced composites." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0017/MQ49722.pdf.
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Engbarth, Miles. "Hall magnetometry of electrodeposited superconducting Pb mesostructures." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520543.
Full textAbstract:
Hall probe magnetometry measurements have been used to investigate the magnetic state of various Pb microcrystals grown by electrodeposition, where careful control of deposition parameters has allowed the tuning of their architectures. The internal flux distribution when in the superconducting state is seen to be highly dependent on the size and geometry of the investigated samples. In nanowires single flux vortex states are seen to form, showing typical type II behaviour. As the diameter of the nanowires increases these vortex states are seen to bunch together, behaviour that begins to approach that of a type I superconductor. Measurements of Pb triangles with sloped sides show the formation of giant vortex states typical of type I behaviour. These results also highlight the importance of geometry on surface barriers and the corresponding effect these have on flux distribution. Investigation of an icosahedron shows how symmetry effects can determine the stability of different flux states. Experimental results are in good agreement with Ginzburg-Landau calculations.
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Silva, Luis Carlos Cides da. "Síntese de sílica mesoestruturada empregando tratamento hidrotérmico em forno de microondas." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-23022018-174331/.
Full textAbstract:
Estruturas de sílica mesoporosa cúbica em forma de gaiola (originalmente identificadas como FDU-1) altamente ordenadas, estáveis térmica e hidrotermicamente, com tamanhos de poros da ordem de 12 nm, foram sintetizadas a partir de TEOS e como molde utilizou-se o copolímero tribloco poli(óxido de etileno)-poli(óxido de butileno)-poli(óxido de etileno) 850-6600 (EO39BO47EO39), em meio ácido. Foi desenvolvido um procedimento de síntese, empregando um forno de microondas no tratamento hidrotérmico para obtenção da sílica FDU-1. Após tratamento hidrotérmico, as amostras foram calcinadas a 540°C, em duas etapas, empregando atmosferas de N2 e ar. Os materiais foram caracterizados por análise elementar, FTIR, TG, SAXS e Isotermas de adsorção de N2 a 77 K. Os dados de SAXS, associados aos das Isotermas de adsorção de N2, demonstraram que os materiais obtidos com 45 e 60 min de exposição a microondas, apresentaram propriedades texturais compatíveis com aquelas do material obtido pelo método convencional. Os ensaios de termogravimetria evidenciam a faixa de temperatura em que ocorrem as decomposições térmicas do copolímero no material como sintetizado e conduziram a uma otimização das melhores condições para calcinação. As curvas TG/DTG indicaram que no aquecimento dos materiais até 1200ºC, há a transformação completa dos grupos silanóis em siloxanos a partir da eliminação de água. Esse fato é confirmado a partir dos espectros de absorção na região do IV e possibilitou estimar que a quantidade dos grupos Si-OH na superfície do material varia com o tempo de tratamento hidrotérmico na etapa de síntese.Highly ordered, thermally and hidrotermally stable, with large pore size of 12 nm, caged-like cubic mesoporous silica structures (originally denoted FDU-1) were synthesized from TEOS and poly(ethylene oxide)-poly(butylene oxide)poly(ethylene oxide) B50-6600 triblock copolymer template (EO39BO47EO39) under acidic conditions.The synthesis procedure was developed using microwave oven for hydrothermal treatment to obtain FDU-1 silica. After hydrothermal treatment, the samples were calcined to 540 ºC, in two stages, using N2 and air atmospheres. The materials characterized by elementary analysis, FTIR, TG, DRX and nitrogen adsorption isothermal at 77 K. The data association of SAXS and the nitrogen adsorption isothermal demonstrated that the material isolated with 45 and 60 minutes of the exposition to the microwaves in the hydrothermal treatment showed testure properties compatible to that one of material obtained by the conventional method. Thermogravimetric experiments evidenced the temperature range where occur copolymer thermal decomposition according to the synthesis, as synthesized materials. This information was important to optimize the material calcination conditions. The TG/DTG curves indicated that, in the material heated up to 1200 ºC, occurs complete transformation of silanol in to siloxane groups with water elimination. This fact is confirmed through the IR spectra and enabled to calculate the quantity of the Si-OH groups in the material surface which vary hydrothermal treatment time in the syntesis stage.