Дисертації з теми "SILICA SYSTEMS"
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Perry, Carole Celia. "Silicification in biological systems." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:ae665ac4-63eb-4963-845a-d2db6aea31a6.
Повний текст джерелаTurner, Richard John. "The rheology and structure of aqueous gelatin-silica systems." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274624.
Повний текст джерелаKokhanenko, Pavlo. "Hydrodynamics and chemistry of silica scale formation in hydrogeothermal systems." Thesis, University of Canterbury. Mechanical Egineering, 2015. http://hdl.handle.net/10092/10247.
Повний текст джерелаRashchi, Fereshteh. "Adsorption on silica in Pb- and Ca-SO4-CO3 systems." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27252.
Повний текст джерелаIn the Pb/sulphate system, precipitates of predominantly Pb-oxide/hydroxide formed on the silica surface. In the Pb/carbonate system, the precipitates were predominantly Pb-carbonate/hydroxy carbonate. Precipitates in both the Pb/SO$ sb4$ and Pb/CO$ sb3$ systems were dispersed by addition of sufficient carbonate, the silica surface eventually becoming free of precipitates. This dispersion was considered to be due to: a high negative surface charge density on both lead carbonate and silica; nucleation being promoted at high concentrations of carbonate, resulting in small precipitates; and increased solubility at high carbonate concentrations.
In the Ca system, calcium sulphate precipitates did not form on the silica particles while calcium carbonate precipitates did. The precipitates were not removed by increasing carbonate concentration. The difference from the Pb system is attributed to a low negative surface charge density on calcium carbonate compared to lead carbonate, leading to less dispersing conditions, and the higher solubility of calcium sulphate compared to lead sulphate.
Meadows, Philippa Jill. "Template-directed synthesis of silica materials based on self-assembling systems." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439957.
Повний текст джерелаRezk, Ahmed Rezk Masoud. "Theoretical and experimental investigation of silica gel/water adsorption refrigeration systems." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3623/.
Повний текст джерелаNeugebauer, Adam (Adam Halbert). "Thermal properties of granular silica aerogel for high-performance insulation systems." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85213.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 65-67).
Based on mounting evidence in support of anthropogenic global climate change, there is an urgency for developments in high-performance building techniques and technologies. New construction projects provide substantial opportunities for energy efficiency measures, but they represent only a small portion of the building stock. Conversely, while existing buildings are plentiful, they typically have a much narrower range of feasible energy efficiency options. Therefore, there will continue to be a need for the development of new and improved energy efficiency measures for new building construction and even more so for deep retrofits of existing buildings. This thesis provides an overview of the research performed into the on-going development at MIT of a high-performance panelized insulation system based on silica aerogel. Two test methods were used for measuring the thermal conductivity of the granules: the transient hot-wire technique and the guarded hot-plate system. Utilizing the hot-wire set-up, it was demonstrated that compressing a bed of granules will decrease the thermal conductivity of the system until a minimum point is reached around the monolithic density of the aerogel. For the Cabot granules, this was seen at 13 mW/m-K and about 150 kg/m3. The MIT granules showed equal performance to the Cabot granules at bed densities 20-30 kg/m3 lower. The hot-plate testing was able to experimentally evaluate previous analytical predictions regarding the conductivity impact of the internal panel truss and the under-prediction of radiant heat transfer in the hot-wire method. Hot-wire testing was also done in a vacuum chamber to quantify potential performance improvements at reduced air pressures. Since a vacuum would require the incorporation of a barrier film into the panel system, some analyses were done into the thermal bridging potential and gas diffusion requirements of such a film. Additionally, physical prototyping was done to explore how the film would be incorporated into the existing panel design. The aerogel-based insulation panel being developed at MIT continues to show promise, though there are still plenty of opportunities remaining in the development cycle.
by Adam Neugebauer.
S.M. in Building Technology
Huang, Pengyu. "Multiscale Modelling of Dynamic Contact Angles for CO2-Water-Silica Systems." Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/20937.
Повний текст джерелаNAIRI, VALENTINA. "Functional ordered mesoporous silica in nanomedicine: target and drug delivery systems." Doctoral thesis, Università degli Studi di Cagliari, 2018. http://hdl.handle.net/11584/255981.
Повний текст джерелаRahman, Shaily. "Cosmogenic Silicon-32 reveals extensive authigenic clay formation in deltaic systems and constrains the marine silica budget." Thesis, State University of New York at Stony Brook, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10140185.
Повний текст джерелаCosmogenic 32Si (t1/2 ∼ 140 yrs) was used in a novel way to constrain the quantity of reactive Si storage and early diagenetic reactions of Si in the highly mobile deltaic sediments along the coast of French Guiana, representative of deposits along the ~1600 km Amazon–Guianas coastline downdrift of the Amazon delta. A sequential leach was developed to extract and purify SiO2 from different operational pools in large samples of surface sediments (0–10cm). This methodology, a hot 1% Na2CO3 leach followed by a hot 4M NaOH leach, was adapted from the existing leaches widely used to estimate biogenic silica (bSi) content in marine sediments, and ultimately to constrain the global oceanic Si budget. 32Si activity was determined in each pool via its daughter product 32P. Results from several sites in coastal mudbanks near Kourou and Sinnamary indicate no detectable 32Si activity in the bSi fraction, whereas 32Si was detected in the Si-NaOH fraction after removal of bSi. The lack of detectable activity in the 1% Na2CO3 leach and its detection in the NaOH fraction (0.4–2.5 dpm) indicate that the method widely used to determine bSi content recovers only a minor fraction of the originally deposited reactive bSi in these deposits. The results are consistent with rapid alteration of biogenic silica and clay authigenesis or reverse weathering. They also demonstrate that the current estimate of biogenic silica storage in tropical deltaic sediments is significantly underestimated. Assuming an initial diatom specific activity range of ∼5–40 dpm/kg SiO 2, the 32Si activity in the NaOH fraction corresponds to a reactive Si storage of ∼150–18,000 µmol Si/g sediment. This magnitude is more consistent with estimates of reactive Si (ΣSi hr) storage in the Amazon delta based on modified operational leach techniques that target poorly crystalline clays and with diagenetic modeling of pore water K+, F−, and Si(OH) 4, though these modified leaches also appear to underestimate the amount of reactive Si stored along this system. To directly confirm whether these modified operational extractions underestimate reactive Si storage, a sequential extraction methodology was also developed to first isolate 32Si activity in the ΣSihr fraction (0.1N HCl followed by 1% Na 2CO3) and then extract any remaining 32Si from the residual fraction using 4M NaOH.
Sediment from 2 stations in the Gulf of Papua, Papua New Guinea, 1 station in the northern Gulf of Mexico near the Southwest Pass, and 1 station in Long Island Sound (Smithtown Bay) were also extracted for 32Si in the bSi fraction as well as the residual fraction after removal of bSi. Bulk 32Si activities in the residual fractions in the Gulf of Papua (0.5–0.7 dpm/kg sediment) were used to extrapolate Si storage in the outer topset and forset of the clinoform delta.
32Si activity was detected in the both the bSi (0.21 ± 0.04 dpm/kg sediment) and the residual fraction (0.44 ± 0.08 dpm/kg sediment) from the site in the Gulf of Mexico. A Si burial rate using the 32Si activity in the bSi fraction (assuming an activity of 15dpm/kg in starting Si materials) of 0.004Tmol/y was calculated over approximately 5000 km2 of the delta, whereas the burial rate calculated using the Si content in this same fraction from a classic bSi leach, was ∼0.006Tmol/y. Adding the Si burial rate using the 32Si activity in the residual fraction (0.008Tmol/y) yielded a total storage per year of 0.012Tmol Si, ∼10% of the total Si inputs (dissolved and amorphous Si) from the Mississippi-Atchafalaya river system. 32Si activity was also detected in the residual fraction (0.53 ± 0.08 dpm/kg sediment) after removal of ΣSi hr and using this activity yielded similar calculated rates of Si burial (∼0.01 Tmol/y).
In Smithtown Bay, Long Island Sound, 32Si activity was also detected in both the bSi (0.15 ± 0.05 dpm/kg sediment) and the residual (0.4 ± 0.2 dpm/kg sediment) fractions from the site in Smithtown Bay, Long Island Sound, yielding a total Si storage estimate (assuming an activity of 15 dpm/kg in starting Si materials) of 1.6 × 10−3 Tmol/y over the entire Sound, comparable to estimates of Si storage calculated using the Si content in the classic bSi (1.1 × 10 −3 Tmol/y) and the classic ΣSihr (2.2 × 10−3 Tmol/y) leaches. It appears that reverse weathering is an important sink of Si in these deposits and that classic bSi or ΣSi hr leaches can underestimate Si storage in these system by two to four-fold. (Abstract shortened by UMI.)
Cervantes, Martínez Claudia Violeta. "Porous and hybrid silica from biocompatible systems : application to drug release." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0295.
Повний текст джерелаThe objective of this work focuses on the preparation of porous, hybrid silicate materials doped with an active ingredient, based on biocompatible components for pharmaceutical applications, as drug delivery systems. The motivation for this study is related to the need to meet the growing demand for more effective drugs. The first point of interest of this study concerns the compounds used which are biocompatible, low-cost, and which are good candidates for the formation of mesostructured materials. The surfactant used was Kolliphor EL (KEL) and the oils were Miglyol 812N (Mig), and Isopropyl Myristate (IM). The active ingredient Ketoprofen (KTP) was chosen as the molecule model for the evaluation of release assays. Finally, HeLa cells, a cancer cell, were used to assess the toxicity of the synthesized materials. The first chapter is devoted to the state of the art of molecular structures based on non-ionic surfactants as KEL. Then, the main publications relating to porous and hybrid materials as drug carriers are summarized. At the end of this chapter, the kinetic release models and corresponding equations are presented. The second chapter brings together the methods and characterization techniques used. The third chapter studies the phase behaviour of the KEL/water binary system studied in this work and is described. The different 1- and 2-phase domains were determined and characterized by visual inspection, using polarized light optical microscopy and liquid crystal structures by SAXS. Then, the influence of oil addition in the KEL/water system was studied at 25°C. Ternary phase diagrams were established with Miglyol (Mig) and Isopropyl Myristate (IM). From these Mig and IM-based systems, mesoporous materials were prepared. With optimized synthesis conditions, the mesoporous network was structured in both cases. In the fourth chapter the influence of the addition of a block copolymer, the P123 in the KEL/water system is reported and the phase diagram is present. It evaluated the synergy of the two surfactants to form micelles and liquid crystals. Then, the effect of the addition of P123 micelles in Isopropyl Myristate based fine emulsions on the characteristics of the porous materials thus prepared using different P123 micelle contents, it is possible to vary the degree of porosity of the materials. For emulsion (Em)/micelle P123 proportions less than 50/50, mesoporous silicas with two pore sizes are obtained. When the Em/P123 ratio increases, it is possible to control the porosity of the materials. The fifth chapter concerns the study of the encapsulation of KTP in different systems and its release. Concentrated emulsions as well as hybrid materials based on micellar solutions and fine emulsions have been selected. Release studies were performed with a PbS solution at different pH levels: 7.4; 1.2 and 4.6. The results showed that, under neutral conditions, the KTP released by hybrid materials based on micellar solutions reaches 38% after 24 hours and the pH effect increases the amount of KTP released. Then, the release into a receptor solution with different concentrations of P123 was studied. The results show that the amount of KTP released in the presence of 5% P123, reach 65% after 24 hours. In the last part, the toxicity of doped materials and hybrid systems was assessed. The results show that the silica matrix protects the cells because cell viability is increased, from 64 to almost 80% with hybrid materials
Rashchi, Fereshteh. "Adsorption on silica in Pb- and Ca-SO¦4-CO¦3 systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29625.pdf.
Повний текст джерелаWiputri, Yonika. "Microparticle retention aid systems in mechanical pulp suspensions." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/973.
Повний текст джерелаGiri, Supratim. "Mesoporous silica nanomaterials and magnetic nanoparticles based stimuli-responsive controlled-release delivery systems." [Ames, Iowa : Iowa State University], 2008.
Знайти повний текст джерелаKupferschmidt, Natalia. "Toxicological and Immunomodulatory Properties of Mesoporous Silica Particles : Applications in Life Sciences." Doctoral thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-195904.
Повний текст джерелаDavis, Jason Edward. "Geochemcial Controls on Arsenic and Phosphorus in Natural and Engineered Systems." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/31012.
Повний текст джерелаMaster of Science
Khan, Jafar Iqbal. "Physics of colloid vibration potential for imaging ionic species and silica dioxide nanoparticle systems." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531618.
Повний текст джерелаHan, Bing. "Prevention of Cathodic Delamination of Polyurethane from Titanium by Plasma Polymerized Silica/Aminosilane Primer Systems." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491558395253426.
Повний текст джерелаDu, Na. "Investigation of Hydrogenated and Fluorinated Surfactant Based-Systems for the Design of Porous Silica Materials." Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10046/document.
Повний текст джерелаThis work deals with the study of the properties of nonionic hydrogenated and fluorinated surfactant based systems which are related to the synthesis of porous silica. The effect of the solubilization of low fraction of hexadecane or decane in the micelles of C12H25CO(OC2H4)9OCH3 leads to the formation of large mesoporous silica, whereas no swelling effect was noted with cyclohexane. When the materials are templated by fluorinated micelles of C8F17C2H4(OC2H4)9OH, large pore mesoporous materials are obtained with perfluorooctyl bromide (PFOBr). Both PFOBr and perfluorodecalin give rise to macropores at high oil concentrations. With C7F15C2H4(OC2H4)8OH, the fluorocarbon (C4F9CH)2 is not only an effective expander to enlarge the pore size of mesoporous materials, but also very favourable for the design of macropore network. On the contrary, with PFOBr, there is neither mesopore nor macropore. Therefore, both hydrogenated and fluorinated systems obey to the same rule: the formation of macroporous materials template by emulsions is favoured with systems which exhibit a high value of the PIT. Lastly, alcohols used as additives in the C8F17C2H4(OC2H4)9OH -water system to tune the characteristics of the recovered materials. The structural parameters of the hexagonal liquid crystal show the short and medium alcohols behaved like solvent, while the long chain and fluorinated octanol acted as co-surfactant. The short alcohols provoke a micelle breaking effect. Thus, the self-assembly mechanism is disturbed and wormhole-like structures are recovered
Walker, Richard John. "Behaviour of nanocolloidal particles on mica : investigations using atomic force microscopy." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4633.
Повний текст джерелаJoshi, Suvid. "MIXED SURFACTANT SYSTEMS: THERMODYNAMICS AND APPLICATIONS IN METAL OXIDE IMPRINTING." UKnowledge, 2014. http://uknowledge.uky.edu/cme_etds/29.
Повний текст джерелаKätzel, Uwe. "Dynamic Light Scattering for the Characterization of Polydisperse Fractal Systems by the Example of Pyrogenic Silica." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1197634640783-66357.
Повний текст джерелаDie Dynamische Lichtstreuung (DLS) ist eine Messmethode zur Größenbestimmung submikroner Partikel. Dabei wird primär die stochastische Bewegung der Teilchen (Diffusion) in Suspensionen und Emulsionen bewertet. Die Stokes-Einstein Gleichung, die das Verhältnis zwischen gemessenem Diffusionskoeffizienten und Partikelgröße wiedergibt, ist jedoch nur für kugelförmige Teilchen, die in sehr niedriger Konzentration vorliegen, gültig. In der vorliegenden Arbeit wird die dynamische Lichtstreuung zur Charakterisierung von Suspensionen pyrogener Kieselsäure eingesetzt. Diese besteht aus fraktalen Aggregaten, die wiederum aus versinterten aber meist kugelförmigen Primärpartikeln zusammengesetzt sind. Diese strukturellen Eigenschaften erschweren die Anwendbarkeit der DLS bzw. die Interpretation der Messergebnisse und verhinderten bisher den Einsatz der DLS als Routinemethode zur Charakterisierung pyrogener Kieselsäuren. Das Hauptziel dieser Arbeit ist daher eine Bewertung der Möglichkeiten der DLS für die Produktentwicklung und Qualitätssicherung in der Herstellung pyrogener Kieselsäuren. Das bedeutet im Besonderen, dass sowohl die messbaren granulometrischen Eigenschaften als auch die Sensitivität der Methode bei Eigenschaftsänderungen ermittelt werden müssen. Die hier durchgeführten Arbeiten sind in vier Teile gegliedert: Simulationen, die eine Beziehung zwischen strukturellen und hydrodynamischen Eigenschaften herstellen, Experimente zur Validierung der Simulationsergebnisse, die Charakterisierung konzentrierter Suspensionen und die anwendungsorientierte Auswertung von DLS-Daten für spezifische industrierelevante Messaufgaben
Kätzel, Uwe. "Dynamic Light Scattering for the Characterization of Polydisperse Fractal Systems by the Example of Pyrogenic Silica." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1197634640783-66357.
Повний текст джерелаKailasam, Varadharajan. "The removal and recovery of oxo-anions from aqueous systems using nano-porous silica polyamine composites." Diss., [Missoula, Mont.] : The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-08312009-114629.
Повний текст джерелаDeyhim, Sina. "Deriving Gas Transport Properties of Microporous Silica Membranes from First Principles and Simulating Separation of Multi-Component Systems in Different Flow Configurations." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31340.
Повний текст джерелаDavis, Christina Clarkson. "Aqueous Silica in the Environment: Effects on Iron Hydroxide Surface Chemistry and Implications for Natural and Engineered Systems." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/33948.
Повний текст джерела
A second phase of research was aimed at identifying the practical implications of silica sorption to iron hydroxide in natural and engineered systems. Two types of surfaces were prepared by exposing pre-formed Fe(OH)3 to aqueous silica (0-200 mg/L as SiO2) for periods of 1.5 hours or 50 days. The concentration of pre-formed iron passing through a 0.45 micron pore size filter at pH 6.0-9.5 increased as the solids aged in the presence of silica. Consistent with formation of small, stable colloids, "soluble" iron concentrations exceeded 0.2 mg/L only at zeta potentials < -15 mV. When arsenate was added to iron hydroxide particles equilibrated with silica for 1.5 hours, percentage arsenate removals were high. In contrast, arsenate removals decreased markedly as pH and silica concentrations increased if silica was pre-equilibrated with the iron for 50 days. Trends in percentage removal of humic substances were similar. Competition for sorption sites was the main cause of hindered anionic contaminant removal. However, interference with hydrolysis and precipitation are expected to be important under some circumstances, particularly during water treatment.
Master of Science
Gutierrez, Cuevas Karla Guadalupe Gutierrez. "LIQUID CRYSTALLINE NANOCOMPOSITES: FROM ACHIRAL TO CHIRAL SYSTEMS." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1500998489695319.
Повний текст джерелаSA, LUCAS TORRES MIRANDA. "SYNTHESIS, CHARACTERIZATION AND EVALUATION OF DRUG DELIVERY SYSTEMS BASED ON MESOPOROUS SILICA FOR IMAGE IN NUCLEAR MEDICINE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=20339@1.
Повний текст джерелаCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O câncer é a segunda maior causa de morte no mundo inteiro e estima-se que até 2030, serão 27 milhões de novos casos e 17 milhões de mortes. Devido a esse fato, o desenvolvimento de novos sistemas de liberação (Drug delivery systems - DDS) que permitam a distribuição de um agente bioativo no seu sítio terapêutico na dose certa, numa taxa específica, acarretando menor toxicidade, e que possa ser utilizado tanto para o tratamento como para o diagnóstico de enfermidades. Atualmente, as sílicas mesoporosa surgem como potenciais DDS ou carreadores em radiofármacos, devido a sua estrutura organizada, alta área superficial e tamanhos e volumes de poros ajustáveis. Nesse trabalho foram sintetizados três potencias sistemas de liberação ou carreadores para radiofármacos para exames de imagem em medicina nuclear. A SBA-15 e sua associação com a hidroxiapatita (HAP) por dois métodos diferentes: adição dos precursores durante formação da mesofase (SBA-15/HAP_1) e o segundo por impregnação na estrutura da SBA-15 já sintetizada e calcinada (SBA-15/HAP_2). Os materiais foram marcados com o radioisótopo 99mTc e tiveram suas marcações e biodistribuições avaliadas. A SBA-15 também foi conjugada com o aptâmero anti-MUC1 para realização de direcionamento ativo para células tumorais. Os materiais foram caracterizados por: espectroscopia de emissão ótica por plasma acoplado indutivamente (ICP-OES); análise termogravimétrica (ATG); fisissorção de nitrogênio; difração de raios-X (DRX); infravermelho (IV); microscopia eletrônica de transmissão e varredura (MET e MEV); e difração a laser. As avaliações da marcação e da biodistribuição foram realizadas por contador de raios gama e gama-câmara respectivamente. A SBA-15 apresentou uma estrutura mesoporosa altamente ordenada, com alta área superficial. Os materiais impregnados com hidroxiapatita apresentaram diferenças estruturais: Na SBA-15/HAP_1 houve bloqueio quase total dos mesoporos com nanopartículas de hidroxiapatita, enquanto na SBA-15/HAP_2, houve um bloqueio parcial dos mesoporos, apresentando também agregados de hidroxiapatita. A metodologia de marcação com o 99mTc apresentou estabilidade de 8 horas. A conjugação da SBA-15 com o aptâmero anti-MUC1 apresentou maior reconhecimento das partículas de SBA-15 por células tumorais.
Cancer is the second major leading cause of death worldwide and is estimated till 2030, 27 million new cases and 17 million of deaths. So, the development of new drug delivery systems (DDS) that allows a bioactive agent distribution in its therapeutic site in the right dose, in a specific rate, leading lower toxicity, and that can be used for treatment and diagnosis of several diseases. Recently, mesoporous silicas arise as promising DDS or carriers for radiopharmaceuticals, because of its highly organized structure, high superficial area and tunable pore size and volumes. In this work, were synthesized three potential DDS or carriers for radiopharmaceuticals for imaging in nuclear medicine. SBA-15 and its association with hydroxyapatite (HAP) by two distinct methodologies: precursors addition during mesophase formation (SBA-15/HAP_1); and precursors impregnation in SBA-15 previously synthesized and calcined (SBA-15/HAP_2). The materials were labelled with tecnecium-99m radioisotope and its labeling methodology and biodistribution were evaluated. SBA-15 was also conjugated with the aptamer Anti-MUC1 for active delivery to tumoral cells. The materials were characterized by: inductively coupled plasma optical emission spectroscopy (ICP-OES); thermogravimetric analysis (TGA); nitrogen physisorption; x-ray diffraction (DRX); infrared (IR), transmission and scanning electronic microscopy (TEM and SEM); and laser diffraction. The labeling and biodistribution evaluation were performed by gamma-ray counter and gamma-camera respectively. The materials were synthesized and have shown peculiar characteristics. SBA-15 has highly ordered mesoporous structure with high superficial area. The materials impregnated with hydroxyapatite showed structural differences: In SBA-15/HAP_1, hydroxyapatite nanocrystals almost blocked the entire mesopores, while in SBA-15/HAP_2, there were a partially blocking of the mesopores and also presented hydroxyapatite nanocrystals aggregates. The tecnecium-99m labeling methodology of the materials showed an 8 hours stability. SBA-15 conjugation with Anti-MUC1 for active delivery has shown a better recognition by tumor cells.
Cole, Robert Paul. "Ballistic Penetration of a Sandbagged Redoubt Using Silica Sand and Pulverized Rubber of Various Grain Sizes." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3565.
Повний текст джерелаRibes, Llop Susana. "Study of different antifungal systems to preserve strawberry jams against fungi spoilage." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/82306.
Повний текст джерелаLas nuevas tendencias en el desarrollo de envases alimentarios innovadores podrían afectar a la estabilidad microbiana del producto durante el almacenamiento. En este sentido, sistemas antifúngicos tales como emulsiones, nanoemulsiones y soportes mesoporosos de sílice pueden ser alternativas prometedoras para preservar la calidad del producto sin tener que aplicar otros tratamientos térmicos. La formulación de sistemas antifúngicos estables y la optimización de la metodología a emplear para preparar estos sistemas, tienen un papel importante en: i) su eficacia antifúngica; ii) pérdidas de los compuestos bioactivos producidas durante su preparación; y iii) su impacto en el perfil sensorial del producto alimenticio. Las nanoemulsiones preparadas con aceites esenciales presentaron por norma general un mayor efecto antifúngico que los aceites libres aplicados a las mismas concentraciones. Asimismo, el tipo de emulsionante utilizado desempeñó un papel clave en la actividad antifúngica de las nanoemulsiones. Las nanoemulsiones preparadas con proteína de suero de leche fueron más eficaces en la inhibición del crecimiento micelial y en la germinación de las esporas que las formuladas con Tween 80. La gran eficacia in vitro de las nanoemulsiones en el control del desarrollo de moho permitió evaluar su aplicación en productos alimenticios, siendo seleccionada la confitura de fresa como matriz alimenticia. Con este fin, las emulsiones de los aceites esenciales de clavo y de hoja de canela fueron incorporadas a las confituras de fresa con el fin de controlar el deterioro fúngico. A pesar de que estas emulsiones fueron capaces de reducir el deterioro fúngico de las confituras de fresa, su incorporación afectó negativamente al aroma, el sabor y la aceptación global de la confitura. En cuanto a la metodología empleada para preparar emulsiones aceite-agua, la combinación de agitación magnética y homogeneización por altas presiones fue la más eficaz para reducir las pérdidas de aceite esencial. Asimismo, se obtuvieron emulsiones estables con una alta capacidad antifúngica, determinada in vitro, frente a los hongos objeto de estudio. A pesar del prometedor uso de las emulsiones de aceite esencial de la corteza de canela en el control del deterioro fúngico de las confituras de fresa, su incorporación al alimento afectó negativamente al aroma, sabor y aceptación global del producto. Debido al gran impacto de los aceites esenciales en el perfil sensorial del producto alimenticio, se investigaron dos nuevos enfoques: i) combinaciones de diferentes compuestos antifúngicos en emulsiones; y ii) inmovilización de compuestos bioactivos sobre superficies de sílice mesoporosas. La combinación de aceite esencial de corteza de canela, el gluconato de zinc y el ácido trans-ferúlico permitió la obtención de un producto considerado microbiológicamente aceptable con buenas características organolépticas pero no se consiguió la inhibición total del crecimiento de moho. Por ello, se estudiaron las propiedades antifúngicas y sensoriales de agentes bioactivos (eugenol y timol) inmovilizados sobre superficies de sílice mesoporosas. La preparación de las confituras con eugenol inmovilizado en las micropartículas de MCM-41, mostró un mejor control de la inhibición fúngica en comparación con las muestras preparadas con timol funcionalizado. El análisis sensorial de las muestras tras la incorporación de los sólidos a la confitura de fresa, reveló que la inmovilización de eugenol y timol reduce el impacto sensorial de estos compuestos en confituras de fresa.
Les noves tendències en el desenvolupament d'envasos alimentaris innovadors podrien afectar l'estabilitat microbiana del producte durant l'emmagatzematge. En aquest sentit, sistemes antifúngics com les emulsions, nanoemulsions i suports mesoporosos de sílice poden ser alternatives prometedores per preservar la qualitat del producte sense haver d'aplicar altres tractaments tèrmics. La formulació de sistemes antifúngics estables, així com l'optimització de la metodologia a emprar per preparar aquests sistemes, tenen un paper important en: i) la seva eficàcia antifúngica; ii) pèrdues dels compostos bioactius produïdes durant la seva preparació; i iii) el seu impacte en el perfil sensorial del producte alimentari. Les nanoemulsions preparades amb olis essencials van presentar per norma general, un major efecte antifúngic que els olis lliures aplicats a les mateixes concentracions. Així mateix, el tipus d'emulsionant utilitzat va tenir un paper clau en l'activitat antifúngica de les nanoemulsions. Les nanoemulsions preparades amb proteïna de sèrum de llet van ser més efectives en la inhibició del creixement micelial i en la germinació de les espores que les formulades amb Tween 80. La gran eficàcia in vitro de les nanoemulsions en el control del desenvolupament de fongs va permetre avaluar la seva aplicació a productes alimentaris, sent seleccionada la confitura de maduixa com a matriu alimentària. Amb aquesta finalitat, les emulsions dels olis essencials de clau i de fulla de canyella van ser incorporades a les confitures de maduixa per tal de controlar el deteriorament fúngic. Tot i que aquestes emulsions reduïren el deteriorament fungic de les confitures de maduixa, la seva incorporació va afectar negativament a l'aroma, el sabor i l'acceptació global de la confitura. Pel que fa a la metodologia emprada per preparar emulsions oli-aigua, la combinació d'agitació magnètica i homogeneïtzació per altes pressions va ser la més eficaç per reduir les pèrdues d'oli essencial. A més, es van obtenir emulsions estables amb una alta capacitat antifúngica, determinada in vitro, davant dels fongs objecte d'estudi. Malgrat el prometedor ús de les emulsions d'oli essencial de l'escorça de canyella en el control del deteriori fúngic de les confitures de maduixa, la seva incorporació a l'aliment va afectar negativament a l'aroma, sabor i acceptació global del producte. A causa del gran impacte dels olis essencials en el perfil sensorial del producte alimentari, es van investigar dos nous enfocaments: i) combinacions de diferents compostos antifúngics en les emulsions; i ii) immobilització de compostos bioactius sobre superfícies de sílice mesoporoses. La combinació d'oli essencial d'escorça de canyella, el gluconat de zinc i l'àcid trans-ferúlic va permetre l'obtenció d'un producte considerat microbiològicament acceptable amb bones característiques organolèptiques però no es va aconseguir la inhibició total del creixement del fong. Per això, es van estudiar les propietats antifúngiques i sensorials d'agents bioactius (eugenol i timol) immobilitzats sobre superfícies de sílice mesoporoses. La preparació de les confitures amb eugenol immobilitzat en les micropartícules de MCM-41, va mostrar un millor control de la inhibició fúngica en comparació amb les mostres preparades amb timol funcionalitzat. L'anàlisi sensorial de les mostres després de la incorporació dels sòlids a la confitura de maduixa, va revelar que la immobilització de eugenol i timol redueix l'impacte sensorial d'aquests compostos en confitures de maduixa.
Ribes Llop, S. (2017). Study of different antifungal systems to preserve strawberry jams against fungi spoilage [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/82306
TESIS
Premiado
Schmidt, Alexandra [Verfasser], and Thomas [Akademischer Betreuer] Bein. "Synthesis and functionalization of mesoporous silica materials for applications as host-guest-systems / Alexandra Schmidt. Betreuer: Thomas Bein." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1080479228/34.
Повний текст джерелаBouledjouidja, Abir. "Imprégnation supercritique pour l'élaboration de systèmes à libération prolongée." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4303/document.
Повний текст джерелаSupercritical impregnation is an attractive “clean” alternative to conventional impregnation processes using generally liquid organic solvents. Among other applications, the impregnation process can be used for the development of controlled drug delivery systems applied to the pharmaceutical and medical fields. This work focuses on the preparation of controlled drug delivery systems using supercritical impregnation of drugs in two kinds of impregnation supports: polymeric matrices (intraocular lenses) and porous supports (mesoporous silica). Firstly, the supercritical impregnation of polymeric intraocular lenses (IOLs), used in cataract surgery, by an anti-inflammatory drug (Dexamethasone 21-phosphate disodium: DXP) and an antibiotic (Ciprofloxacin: CIP), is studied. More particularly, two polymeric IOLs were tested: rigid intraocular lenses made from derivative of PMMA and foldable intraocular lenses made from derivative of P-HEMA. Supercritical impregnations were carried out in a batch mode and the impregnation yields were determined through drug release kinetics studies in a solution simulating the aqueous humor. The influence of operating conditions on impregnation was studied by performing preliminary impregnation experiments followed by experimental designs. The second part of this work deals with the loading of a poorly water-soluble drug (Fenofibrate) in a mesoporous silica for improving drug dissolution kinetics. Supercritical impregnations were carried out with pure CO2 at different pressures (100 to 200 bar) and depressurization rates (rapid and slow)
Oliveira, Fernando Jose Volpi Eusebio de. "Hibridos inorganico-organicos mesoporosos nanoestruturados = aspectos estruturais e energeticos das interações cations-centros basicos na interface solido/liquido." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250026.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-15T02:31:23Z (GMT). No. of bitstreams: 1 Oliveira_FernandoJoseVolpiEusebiode_D.pdf: 14034511 bytes, checksum: befefa4bb08edceee361642b479a35ca (MD5) Previous issue date: 2009
Resumo: Três conjuntos de sílicas mesoporosas foram sintetizados com os agentes direcionadores dodecilamina, brometo de cetiltrimetilamônio (CTAB) e co-polímero tribloco EO20-PO70-EO20 (P123 ¿ Pluronic®). As matrizes inorgânicas foram funcionalizadas com agentes sililantes contendo de um a três átomos de nitrogênio nas cadeias. Além disso, estes silanos reagiram com o ligante tiocarbamida, em uma etapa livre de solvente, anteriormente à formação da sílica, em processo de co-condensação. A rota de síntese empregada para as amostras preparadas a partir do direcionador P123 foi a pósfuncionalização. Para as estruturas obtidas utilizando-se dodecilamina, do tipo HMS, observou-se o colapso da estrutura após a extração do direcionador, conforme mostraram os espectros de IV e os difratogramas antes e depois do processo de remoção. Contudo, as amostras apresentaram tamanho médio de poros na faixa que constituem os materiais mesoporosos, sendo então investigados no estudo da remoção de metais tóxicos. Para as amostras preparadas CTAB e P123 foram observados os sinais da reflexão típica de materiais do grupo p6mm, denominada 2D-hexagonal, cujas amostras análogas aos materiais MCM-41 e SBA-15, respectivamente. Todos os híbridos modificados com tiocarbamida foram aplicados em sorção de íons metálicos, ajustados ao modelo não linear de sorção de Langmuir. As interações na interface sólido/líquido foram determinadas por microcalorimetria. Os resultados revelaram que os materiais do tipo SBA-15 apresentam alta capacidade de remoção de Cu, Cd e Pb, devido ao procedimento de pós-funcionalização. As amostras obtidas por co-condensação, do tipo HMS e MCM-41, apresentaram capacidade máxima de sorção superior aos resultados observados na literatura para materiais análogos. Os experimentos calorimétricos mostraram que as interações entre os sólidos e os íons metálicos são exotérmicas, com exceção dos íons Pb. Outro aspecto destacado trata-se da importância do termo entrópico, que parece reger o processo na maioria dos casos, devido à liberação de moléculas de água coordenadas aos íons e às matrizes. Portanto, todos os sistemas estudados apresentaram um comportamento energeticamente favorável.
Abstract: Three set of mesoporous silicas have been synthesized through dodecylamine, cetiltrimethylamonium bromide (CTAB) and the triblock co-polymer EO20-PO70-EO20 (P123 ¿ Pluronic®) as structure directing agents (sda). The inorganic matrices have been functionalized with silylating agents presenting from one to three nitrogen atoms on their chains. In addition, these silanes reacted with thiocarbamide through a free-solvent step, before the silica formation, by co-condensation process. However the synthetic route for the samples templated by P123 was the post-grafting. For the structures obtained by using dodecylamine, HMS-like, it was observed the structure collapsed after template removal, as shown by IR spectra and XRD patterns, before and after the removal process. These samples presented pore size comprised on mesoporous range, being then investigated for toxic metal removal capacity. For the samples prepared from CTAB and P123, the typical reflections for p6mm group materials, named 2D-hexagonal, were observed, and these samples are analogous to MCM-41 and SBA-15 materials, respectively. All thiocarbamide-modified hybrids were applied to metal ions sorption, being adjusted to Langmuir non-linear fit model. The interactions at the solid/liquid interface were determined through microcalorimetry. The results reveal that the SBA-15-like materials present high removal capacity for Cu, Cd e Pb, due to the post-grafting procedure. The samples obtained through cocondensation route, HMS- and MCM-41-like, presented maximum sorption capacity higher than those results for analogous published materials. With exception of Pb, all calorimetric determinations showed that the interactions between the solids and metal ions are exothermic. Another highlighted feature is about the importance of the entropic term that seems to rule the processes for several cases, due to the ion and surface coordinated water molecules displacement. Thus, all studied systems presented an energetically favorable behavior.
Doutorado
Quimica Inorganica
Doutor em Ciências
Alleman, Coleman. "Molecular Dynamics Investigations of Polystyrene-Based Binary Thin Film Systems: Interfacial Properties and Mechanical Behavior." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306909005.
Повний текст джерелаGoursaud, Matthieu. "Contribution to the development of nano-systems for the recognition of fluoride in water." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209378.
Повний текст джерелаMost of the synthetic systems reported for fluoride recognition have been extensively studied in organic solvents (DMSO, acetonitrile) using tetrabutylammonium fluoride (TBAF) as the source of fluoride. In many cases, titra- tion behaviours are observed that cannot be ascribed to a classical 1:1 binding isotherm, deprotonation problems of Brønsted-Lowry acid type of receptors aside. In the first part of our thesis we investigated, using a uranyl-salophen re- ceptor which recognizes fluoride via Lewis Acide/Base interactions, the origin of the unusual titration behaviour. Via UV/vis, 19F and 1H NMR spectroscopies, we have been able to highlight that the equilibrium between the fluoride and the corresponding bihalide ion, HF−2 ,which is inevitably generated along with the hydroxide anion in situ due to trace amounts of water, can be at the ori- gin of this singular behaviour. Our results put to light that when undertaking titrations with fluoride in DMSO, the fluoride–bihalide equilibrium can affect the data and that the latter species can even be the dominating species at low TBAF concentrations. When varying the solvent from DMSO to acetonitrile, the s-shape titration curves observed by UV/vis are no longer observed for the uranyl-salophene receptor that we studied. The fluoride-bifluoride equilibrium is still present but both of the anions generated in this process are recognised by the uranyl-salophene receptor with similar affinity constants above 10^6 M−1.
The second part of our work was devoted to finding ways to solubilize anion receptors that are efficient in organic solvents, into an aqueous environment. Two approaches were investigated: (i) grafting of the receptors onto silica nanoparticles and (ii) the micellar incorporation of the receptors. For the first strategy, we developed two silylated urea-based receptors. These receptors were first studied in organic solvents (DMSO and/or acetonitrile) where they showed selectivity, among halides, towards fluoride. Once grafted on the silica nanoparticles, due to the fact that hydroxyl groups and solvent molecules are present in the silica matrix, fluoride recognition was not possible.
We explored it with different simple H-bond based urea receptors in the second srategy. With the cationic surfactants, cetyl trimethyl ammonium chloride and bromide, the counter-ions of the micelles interfere with the fluoride recognition. With the neutral surfactant triton X-100, the incorporation of the anion receptors proved to be difficult. Moreover, the variations observed in the UV/vis spectra upon titrations were too small to be able to make any conclusions about fluoride recognition.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Hernández, Teruel Adrián. "Smart drug delivery systems designed to improve Inflammatory Bowel Disease therapy." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/129863.
Повний текст джерела[CAT] La present tesi doctoral titulada "Sistemes d'alliberament controlat de farmacs dissenyats per a millorar el tractament de Malaltia Inflamatoria Intestinal" se centra en el disseny, preparacio, caracteritzacio i avaluacio in vivo de diferents sistemes d'alliberament controlat de farmacs en colon (*CDDS, per les seues sigles en angles) utilitzant com a suport microparticules de si'lice mesoporosa, funcionalitzades amb portes moleculars. En conclusio, els estudis realitzats demostren que els materials de si'lice mesoporosa, en combinacio amb portes moleculars sensibles a estimuls especifics, tenen un gran potencial per al desenvolupament de nous sistemes d'alliberament controlat de farmacs en el colon, dirigits a millorar l'arsenal terapeutic disponible per al tractament de MII. La possibilitat d'adaptar o personalitzar la carrega i les portes moleculars, fa que aquests suports de silice mesoporosa siguen una opcio interessant per al desenvolupament de nous sistemes d'alliberacio controlada de farmacs en diferents aplicacions biomediques. Finalment, esperem que els resultats obtinguts en aquesta tesi doctoral servisquen d'inspiracio per al desenvolupament de sistemes d'alliberament controlat de farmacs innovadors i cada vegada mes intel·ligents, per a la seua aplicacio tant en medicina com en altres arees.
[EN] This PhD thesis entitled "Smart drug delivery systems designed to improve Inflammatory Bowel Disease therapy" is focused on the design, synthesis, characterization and in vivo evaluation of several Colon Drug Delivery Systems (CDDS) using hybrid mesoporous silica microparticles as scaffolds containing molecular gates. In conclusion, the studies shown in this Thesis demonstrate that mesoporous silica materials in combination with responsive molecular gates have great potential in the design and preparation of new CDDS to improve the therapeutic options available for IBD. The possibility to adapt the cargo and the molecular gate makes mesoporous silica support especially appealing for similar controlled drug delivery applications in the biomedical field. We hope that the obtained results could inspire the development of new innovative smart drug delivery systems in this or other fields.
We thank the Spanish Government (projects MAT2015-64139-C4-1-R and AGL2015-70235-C2-2-R (MINECO/FEDER)) and the Generalitat Valenciana (project PROMETEOII/2014/047) for support. AHT thanks to the Spanish MEC for his FPU grant. We thank the Generalitat Valenciana (Project PROMETEO2018/024)
Hernández Teruel, A. (2019). Smart drug delivery systems designed to improve Inflammatory Bowel Disease therapy [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/129863
TESIS
Hecht, Mandy. "Particulate systems and thin-film based platforms." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17329.
Повний текст джерелаThe combination of fluorescence and nanomaterials has developed into an emerging research area. Nonetheless until now the step from an organic sensory molecule to a final sensor format is a complex endeavor. This thesis aimed at the preparation of particulate and thin-film based platforms for various analytes through combining the features of an appropriate host material with outstanding properties of dyes concomitant with sensitive fluorescence detection techniques. In particular, pH sensitive fluorescent probes were sterically immobilized into a thin membrane. The dip-stick allows the assessment upon change in pH with the eye. Especially a probe working at high basic pH range was converted into a water-soluble analogue and was directly applied at the growth front of silica biomorphs to detect local pH changes. But also particulate structures are suitable host materials. It is shown how the silica matrix of nanoparticles lead to improved optical properties for embedded dyes. The interactions of silica and fluorescent dyes within the pores of mesoporous particles were exploited to develop an actual sensor format based detection of TATP. In another approach it was possible to detect mercury ions in water. Heavy metal ions were also successfully detected in a quencher displacement assay involving receptor-dye functionalized silica nanoparticles. The impact of the unique surface properties of cellulose microparticles was shown by a fluorescent dye which allows an assessment of the surface functional groups and microenvironment through the reactivity and its changes in the optical properties. The performance of the prepared materials were evaluated mostly by spectroscopic methods and if possible assessed in terms of sensitivity, selectivity and response time. The newly developed and investigated materials based on fluorescent particulate and thin-films show the facile application of innovative sensor probes for potentially sensing devices.
Junges, Fernando. "Novel catalyst systems based on Ni(II), Ti(IV), and Cr(III) complexes for oligo-and polymerization of ethylene." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2005. http://hdl.handle.net/10183/6358.
Повний текст джерелаThe complex of Brookhart Ni(α-diimine)Cl2 (1) (α-diimine = 1,4-bis(2,6- diisopropylphenyl)-acenaphthenediimine) has been characterized after impregnation on silica (S1) and MAO-modified silicas (4.0, 8.0 and 23.0 wts.% Al/SiO2 called S2, S3 and S4, respectively). The treatment of these heterogeneous systems with MAO produces some active catalysts for the polymerization of the ethylene. A high catalytic activity has been gotten while using the system supported 1/S3 (196 kg of PE/mol[Ni].h.atm; toluene, Al/Ni = 1000, 30ºC, 60 min and atmospheric pressure of ethylene). The effects of polymerization conditions have been tested with the catalyst supported in S2 and the best catalytic activity has been gotten with solvent hexane, MAO as cocatalyst, molar ratio Al/Ni of 1000 and to the temperature of 30°C (285 kg of PE/mol[Ni].h.atm). When the reaction has been driven according to the in situ methodology, the activity practically doubled and polymers showed some similar properties. Polymers products by the supported catalysts showed the absence of melting fusion, results similar to those gotten with the homogeneous systems by DSC analysis. But then, polymers gotten with the transplanted system present according to the GPC’s curves the polydispersity (MwD) varies between 1.7 and 7.0. A polyethylene blend (BPE/LPE) was prepared using the complex Ni(α-diimine)Cl2 (1) (α-diimine = 1,4-bis(2,6-diisopropylphenyl)-acenaphthenediimine) and {TpMs*}TiCl3 (2) (TpMs* = hydridobis(3-mesitylpyrazol-1-yl)(5-mesitylpyrazol-1-yl)) supported in situ on MAO-modified silica (4.0 wts. -% Al/SiO2, S2). Reactions of polymerization of ethylene have been executed in the toluene in two different temperatures (0 and 30°C), varying the molars fraction of nickel (xNi), and using MAO as external cocatalyst. To all temperatures, the activities show a linear variation tendency with xNi and indicate the absence of the effect synergic between the species of nickel and the titanium. The maximum of activity have been found at 0°C. The melting temperature for the blends of polyethylene produced at 0 °C decrease whereas xNi increases indicating a good compatibility between phases of the polyethylene gotten with the two catalysts. The melting temperature for the blends of polyethylene showed be depend on the order according to which catalysts have been supported on the MAO-modified silica. The initial immobilization of 1 on the support (2/1/S2) product of polymers with a melting temperature (Tm) lower to the one of the polymer gotten when the titanium has been supported inicially (1/2/S2). The observation of polyethylenes gotten with the two systems (2/1/S2 and 1/2/S2) by scanning electron microscopy (SEM) showed the spherical polymer formation showing that the spherical morphology of the support to been reproduced. Are described the synthesis, the characterization and the catalytic properties for the oligomerization of the ethylene of four organometallics compounds of CrIII with ligands ([bis[2-(3,5-dimethyl-1-pyrazolyl)ethyl]amine] chromium (III) chloride (3a), [bis[2-(3,5- dimethyl-l-pyrazolyl)ethyl]benzylamine] chromium (III) chloride (3b), [bis[2-(3,5-dimethyl-lpyrazolyl) ethyl]ether] chromiun(III)chloride (3c), [bis[2-(3-phenyl-lpyrazolyl) ethyl]ether]chromiun(III)chloride (3d)). In relation of the oligomerization, at exception made of the compounds 3a, all complex of the chromium showed be active after activation with MAO and the TOF gotten have one effect differentiated to those formed with CrCl3(thf)3. The coordination of a tridentate ligand on the metallic center doesn't provoke any considerable changes on the formation of the C4 and C6, but the amount of C8 are decrease and the C10 and C12+ have increased. The Polymers produced by the catalyst 3a to 3 and 20 bar of ethylene have, according to analyses by DSC, the temperatures of fusion of 133,8 and 136ºC respectively. It indicates that in the two cases the production of high density polyethylene. The molar mass, gotten by GPC, is 46647 g/mols with MwD = 2,4 (3 bar). The system 3c/MAO showed values of TOF, activity and selectivity to different α-olefins according to the pressure of ethylene uses. Himself that shown a big sensibility to the concentration of ethylene solubilized.
May, Masnou Anna. "Insights into nanomaterials: from surfactant systems to meso/macroporous materials and nanoparticles." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/285940.
Повний текст джерелаEls nanomaterials són materials amb propietats morfològiques entre 1 i 100 nm en almenys una direcció. En aquesta tesi s'estudien els materials meso- i meso/macroporosos de sílice, que tenen porus en aquestes dimensions, i nanopartícules, la grandària de les quals es troba també en aquest rang. En una primera fase s'estudien els sistemes tensioactius, com les solucions micel·lars i les emulsions, que s'usen per a la síntesi d’aquests materials. El primer estudi consta de l’anàlisi de les emulsions formades amb cristall líquid a la fase contínua. La microestructura d'aquests sistemes s'estudia amb diversos models reològics. També es comparen amb sistemes amb fase micel·lar en la fase contínua i a diferents concentracions de tensioactiu i fase dispersa. En un segon estudi es determinen les variables de procés que tenen un efecte significatiu sobre les propietats de les emulsions. Com a variables de resposta s'usen la mida de gota i les propietats reològiques. També s'estudia l'escalat en la preparació de les emulsions altament concentrades i es determinen els invariants d’escala. El tercer estudi se centra en la preparació de materials meso i meso/macroporosos. Es sintetitza un material amb mesoporus bimodals i estructura hexagonal ordenada a partir d'una barreja de dos tensioactius, i la síntesi de materials mesoporosos ordenats a partir d'uns tensioactius amb grups amino. També es preparen materials amb macroporus a partir d'emulsions formades amb aquest tensioactiu i, en última instància, es preparen esferes mesoporoses de sílice a partir d'emulsions aigua-en-oli altament concentrades. L'últim estudi se centra en la síntesi de nanopartícules de sílice, en les variables de procés que tenen un efecte directe sobre la mida obtinguda, i en l'aplicació d'aquestes nanopartícules en la coagulació de la sang per controlar hemorràgies internes. S'estudien les propietats de coagulació i es funcionalitzen amb agents que acceleren o disminueixen aquesta activitat. Les tècniques de síntesi i caracterització inclouen reologia, microscòpia òptica, adsorció-desorció de nitrogen, dispersió de raigs X, microscòpia electrònica de transmissió i de rastreig (TEM i SEM) i potencial zeta, entre altres.
Elsherif, Ahmed Gamal Attallah Abdelmaksoud [Verfasser]. "Study of the pore systems of metal-organic frameworks, mesoporous silica, and low-k dielectric layers by means of positron annihilation spectroscopy / Ahmed Gamal Attallah Abdelmaksoud Elsherif." Halle, 2018. http://d-nb.info/1160514496/34.
Повний текст джерелаRuhge, Forrest. "EFFECT OF GERMANIUM DOPING ON ERBIUM SENSITIZATION IN THE ERBIUM DOPED SILICON RICH SILICA MATERIAL SYSTEM." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2933.
Повний текст джерелаM.S.
Other
Optics and Photonics
Optics
Kamapantula, Bhanu K. "In-silico Models for Capturing the Static and Dynamic Characteristics of Robustness within Complex Networks." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/4049.
Повний текст джерелаCirillo, Silvia <1990>. "Personalization of Electronic Nicotine Delivery Systems Toxicological impact in in-vivo model." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9182/1/Silvia%20Cirillo_Tesi.pdf.
Повний текст джерелаChen, Ming. "In silico systems analysis of biopathways." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972067272.
Повний текст джерелаGonzález, Fernández Alfredo A. "Studies and integration of Silicon-based light emitting systems." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/285863.
Повний текст джерелаEste proyecto aborda el estudio de dispositivos y materiales luminiscentes basados en silicio para su uso en la fabricación de un sistema óptico que integre emisor de luz, guía de ondas, y sensor en un solo chip obtenido mediante el uso de técnicas y materiales estándar para la fabricación CMOS. Las características atómicas y estructurales de los materiales son analizados y relacionados con su respuesta luminiscente. Considerando los resultados de la caracterización del material activo, se presenta el diseño, fabricación, y caracterización de dispositivos electroluminiscentes basados en dichos materiales. Finalmente, se discute y analizan el diseño, fabricación, y caracterización de un transceptor como Sistema Óptico Integrado. Los materiales activos para la emisión de luz fueron distintos Dióxidos de Silicio enriquecidos con Silicio (SRO por sus siglas en inglés) y bi-capas SRO-Si3 N4, obtenidos mediante una variedad de técnicas compatibles con los procesos CMOS y distintos parámetros para los mismos. Se identificaron dos mecanismos que contribuyen a la fotoluminiscencia del SRO en todos los casos, relacionados con defectos radiativos y fenómenos de Confinamiento Cuántico, respectivamente. Se sugiere y pone a prueba un modelo para describir este último, basado en la aproximación de la masa efectiva y la relación entre la cantidad de enlaces Si-Si y el volumen de nano-aglomerados. En muestras bi-capa, se observó una banda adicional de luminiscencia, cuya generación fue identificada en el material de transición entre el nitruro de silicio y el óxido, y relacionada con estados de energía introducidos por defectos. Muestras con un espesor de SRO diez veces mayores a aquel del nitruro presentaron una clara dominación de la luminiscencia relacionada con el óxido. Se halló que los centros responsables por la electroluminiscencia en los dispositivos electrónicos son fundamentalmente los mismos que los responsables de la fotoluminiscencia a pesar de las diferencias en los espectros medidos, y se concluyó que la influencia de la arquitectura sobre el espectro de salida es de importancia significativa. Se mostró que dispositivos bi-capa entregan mejores resultados en términos de eficiencia, control sobre la luz emitida, distribución de la misma, y estabilidad en el funcionamiento. Se observó que los mecanismos de transporte de carga hallados en los dispositivos están dominados por ruptura del material en el caso de dispositivos de una sola capa, y Tuneleo Asistido por Trampas en el caso de dispositivos bi-capa. El Sistema Óptico que integra el emisor, una guía de ondas, y el detector de luz, fue diseñado y fabricado con base en los resultados de la fabricación y análisis de los dispositivos emisores de luz aislados. Durante la etapa de diseño, se corroboró mediante simulaciones por computadora que las características de la luz emitida por los dispositivos que presentaron la máxima eficiencia y fiabilidad fueran apropiadas para su transmisión a través de la guía de ondas propuesta. También se corroboró teóricamente que las capacidades de detección de los sensores diseñados fuera la adecuada para el tipo de luz emitida. Se exploró el apropiado funcionamiento de los elementos del sistema finalmente fabricado. Se encontraron diferencias en la operación de los dispositivos emisores de luz aislados y aquellos integrados, pero la luminiscencia resultante se halló dentro de los límites del espectro transmisible. La operación del Sistema Óptico Integrado fue probada y estudiada de manera preliminar, con la obtención de resultados positivos en su respuesta estímulo-detección, cumpliendo así con el objetivo principal del trabajo, y abriendo la puerta para estudios posteriores que pueden guiar a la optimización del diseño del sistema para aplicaciones particulares.
Griffin, N. "Low-dimensional systems in silicon/silicon-germanium heterostructures." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599710.
Повний текст джерелаLargenton, Béatrice. "Etude rhéologique de systemes "chitosane-silice"." Brest, 1996. http://www.theses.fr/1996BRES2002.
Повний текст джерелаSun, Chen Ph D. Massachusetts Institute of Technology. "Silicon-photonics for VLSI systems." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99784.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 173-183).
As raw compute power of a single chip continues to scale into the multi-teraflop regime, the processor I/O communication fabric must scale proportionally in order to prevent a performance bottleneck. As electrical wires suffer from high channel losses, pin-count constraints, and crosstalk, they are projected to fall short of the demands required by future memory systems. Silicon-photonic optical links overcome the fundamental tradeoffs of electrical wires; dense wavelength division multiplexing (DWDM) - where multiple data channels share a single waveguide or fiber to greatly extend bandwidth density - and the potential to combine at chip-scale with a very large scale integrated (VLSI) CMOS electrical chip make them a promising alternative for next-generation processor I/O. The key device for VLSI photonics is the optical microring resonator, a compact micrometer-scale device enabling energy-efficient modulation, DWDM channel selection, and sometimes even photo-detection. While these advantages have generated considerable interest in silicon-photonics, present-day integration efforts have been limited in scale owing to the difficulty of integration with advanced electronics and the sensitivity of microring resonators to both process and thermal variations. This thesis develops and demonstrates the pieces of a photonically-interconnected processor-to-memory system. We demonstrate a complete optical transceiver platform in a commercial 45 nm SOI process, showing that optical devices can be integrated into an advanced, commercial CMOS SOI process even without any changes to the manufacturing steps of the native process. To show that photonic interconnects are viable even for commoditized and cost-sensitive memory, we develop the first monolithic electronic-photonic links in bulk CMOS. As the stabilization of ring resonators is critical for use in VLSI systems, we contribute to the understanding of process and thermal variations on microring resonators, leading to the demonstration of a complete auto-locking microring tuning system that is agnostic to the transmitted data sequence and suitable for unencoded low-latency processor-to-memory traffic. Finally, the technology and methods developed in this work culminate in the demonstration of the world's first processor chip with integrated photonic interconnects, which uses monolithically integrated photonic devices to optically communicate to main memory.
by Chen Sun.
Ph. D.
Lintereur, Phillip. "EFFECTS OF SOURCE WATER BLENDING FOLLOWING TREATMENT WITH SODIUM SILICATE AS A CORROSION INHIBITOR ON METAL RELEASE WITHIN A WAT." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2967.
Повний текст джерелаPh.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Electrical Engineering PhD
Damart, Tanguy. "Energy dissipation in oxide glasses." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1189/document.
Повний текст джерелаThe origin of sound attenuation at low and high frequency in glasses stays elusive mainly because of the complex temperature and frequency dependence of the phenomena at its root. Indeed, the presence of complex structures and multi-scale organizations in glasses induce the existence of relaxation time ranging from the second to the femto-second and of spatial correlation ranging from the Angström to a hundred nanometers. At low-frequency, a better understanding of the phenomena at the origin of dissipation would be beneficial to several applications. For example, the multi-layers coating the mirrors of gravitational waves detectors consists of a superposition of two oxide glasses: silicate (SiO2) and tantalum pentoxide (Ta2O5), are an important source of dissipation. At high frequency, the study of dissipation raises theoretical questions about the link between attenuation and dissipation as well as between loclt asymmetry and dissipation. In the present study, we conducted an analysis of the interaction between mechanical waves and the structure of two oxide glasses using simulation techniques such as non-equilibrium molecular dynamics. At high-frequencies, we implemented and used mechanical spectroscopy to measure dissipation numerically and performed in parallel an analytical development based on the projection of the atomic motion on the vibrational eigenmodes. At low-frequencies, we used molecular dynamics to gather sets of thermally activated events that we classed in three categories based on topologically distinct atomic motions and from which we predicted dissipation numerically using a refreshed TLS model