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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"xerogel"”.
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Hydrophobic, fluorinated silica xerogel for low-k applications.
A new hydrophobic hybrid silica film was synthesized by introducing one silicon precursor (as modifiers) into another precursor (network former). Hybrid films have improved properties. Hydrolysis and condensation of dimethyldiethoxysilane (DMDES) (solvent (EtOH) to DMDES molar ratio R = 4, water to …
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Structure and performance of carbon xerogel molded emitters for micropropulsion applications
… tips. This study investigates the use of carbon xerogels for electrospray applications due to their exceptional properties such as large surface to volume ratio, robustness and pore uniformity. The substrates are created through a synthesis route which is advantageous for reproducibility. Single …
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Development and research of porous alumina xerogel membranes for electrospray propulsion applications
… section specifically focusses on cast alumina xerogels (porosities less than 90% typically around 40-50%) and briefly investigates a manufacturing procedure. The main problem facing the performance of these extractor membranes is the consistency of their geometry and porosity given the …
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Tailoring Local Conductivity by the Formation of Ag Nanoclusters in SiO2 Xerogel Films
<p>Porous silicon dioxide thin films were produced via dip-coating and doped with Ag+ by adding AgNO3 to the dipping solution. Nanoparticles were formed within the pores of these films by UV exposure. Nanoparticle formation was confirmed by UV-visible spectroscopy and Transmission Electron …
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Use of a quartz crystal microbalance to investigate the mechanical stability of silica xerogel membranes for volatile iodine capture
… integrity of the tested materials. Silica-based xerogels, prepared through sol-gel processing using only tetraethoxysilane (TEOS), TEOS with oil as porogen, TEOS with bismuth nanoparticles, and TEOS with both. The technique subjected the adsorbents to a gas stream and used adhesive-coated quartz …
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BISMUTH-FUNCTIONALIZED SORBENTS FOR RADIOIODINE CAPTURE
… were performed to remove oil from silica xerogels. TEOS precursor gave isolated but larger pores while TEOS + MTMS precursor gels gave finer and interconnected pores. As a result of finer pore structure gels made with TEOS+MTMS have a higher surface area of 1068 ± 113 m2g-1. Bismuth …
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Engineering ionic liquid ion sources for ion beam applications
… porous carbon based on resorcinol-formaldehyde xerogels is introduced as an emitter substrate. The target pore sizes and emitter geometries to attain the PIR are obtained through analytical estimates. The carbon xerogel can be shaped to the required micron-sized geometry through mechanical …
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NOVEL SYNTHETIC METHODS AND APPLICATIONS OF POROUS MATERIALS: AEROGEL FOAMS, METALLIC AEROGELS, AMORPHOUS AND GRAPHITIC CARBON AEROGELS
… synthesized from polyurea-crosslinked cobaltia xerogel powder compacts via carbothermal reduction, for application as thermites. III. Carbon aerogels were synthesized from compressed compacts of polyurea- and polyacrylonitrile-crosslinked silica xerogel powders. The process of making …
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Development of novel formulations for mucosal delivery of protein based drugs
… lyophilised chitosan and thiolated chitosan xerogels have been developed for potential delivery of proteins via the buccal mucosa. Membrane dialysis to eliminate sodium acetate (NaAc) and annealing during lyophilisation cycle (developed by differential scanning calorimetry; DSC) were critical …
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Design, Synthesis and Characterization of Porous Silica Nanoparticles and Application in Intracellular Drug Delivery
… and acid-base catalyzed, sol-gel derived, silica xerogel systems were investigated for sustained release of an aminoglycosides antimicrobial against salmonella infection in a mouse model. The release of gentamicin from the inner hollow part of the carrier is delayed. Further, the higher porosity …
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Synthesis and applications of ceramic (silicon carbide and silicon nitride), metallic (cobalt(0)) and polymeric (polyurethane) aerogels
… ceramic and purely metallic aerogels from xerogel powder compacts, and the use of polyurethane aerogels based on cyclodextrins as efficient desiccants.</p><p>I. Highly porous ( > 80%) monolithic SiC and Si<sub>3</sub>N<sub>4</sub>, aerogels were prepared from compressed compacts of …
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DEVELOPMENT OF NANO-STRUCTURED METAL OXIDES/GRAPHENE FOR ENERGY APPLICATIONS
… of the enhanced thermal stability of the V2O5 xerogel. The graphene sheets help to preserve the V2O5 xerogel structure and keep the xerogel from collapsing by maintaining 0.3 water molecules per V2O5 (water molecules serve as a pillar between the V2O5 layers) during the annealing process. The …
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DEVELOPMENT OF NANO-STRUCTURED METAL OXIDES/GRAPHENE FOR ENERGY APPLICATIONS
… of the enhanced thermal stability of the V2O5 xerogel. The graphene sheets help to preserve the V2O5 xerogel structure and keep the xerogel from collapsing by maintaining 0.3 water molecules per V2O5 (water molecules serve as a pillar between the V2O5 layers) during the annealing process. The …
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Porous material and process development for electrospray propulsion applications
… internal surface area was discovered. Carbon xerogel electrodes with embedded wires were designed and fabricated through this research. Specifically, carbon xerogel electrodes with internal surface areas on the order of 500 m² /g were fabricated and tested.
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Síntesis de xerogeles de carbono inducida por microondas para su uso como electrodos en supercondensadores
… de unos materiales carbonosos denominados xerogeles de carbono, mientras que en la segunda se ha evaluado la capacidad de almacenamiento de energía de los xerogeles de carbono sintetizados en el laboratorio, utilizados como material de electrodo en supercondensadores de diversa tipología. …
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Synthetic polymer-collagen composite hydrogel for drug delivery and tissue engineering
… with collagen under basic condition to obtain xerogel. Series of test by the use of equipments such as NMR and DSC or TNBS reagent were carried out to investigate the extent of successful crosslinking. Water contact angle and cell cytotoxicity study were also conducted to examine the …
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Chalcogenide Sol-Gel Assembly: Controlling The Kinetics Of Nanocrystal Aggregation And Film Formation For Applications In Optoelectronics
… form. The synthesis of transparent micron-thick xerogel films of CdSe/ZnS NCs was achieved by employing similar gelation conditions that resulted in transparent gel structures. Films were deposited by immersing a glass substrate horizontally in the pre-oxidized sols, gelling and drying under …
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Raman-Spektroskopie hybridpolymerer Sol-Gel-Materialien : vom Sol bis zur Schicht
… den Sol-Gel-Prozeß hergestellte hybride Sole, Xerogele und Schichten mit Hilfe der Raman-Spektroskopie untersucht. Dazu wurden zunächst die schwingungsspektroskopischen Zuordnungen für verschiedene Alkoxysilanen ergänzt und zusammengefasst. Anschließend wurde die Hydrolyse vom …
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Testing new potential fuels for ion electrospray propulsion systems
… First, it implements and evaluates a carbon xerogel emitter substrate as an alternative over current glass emitters. This substrate was found to fire stably and with higher stable currents than the glass alternative (1.5 - 2 times the maximum stable current). In addition, this work analyzes …
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