Дисертації з теми "Silica monolith"
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1
Smith, Jennifer Houston. "Chromatographic Properties of Silica-Based Monolithic HPLC Columns." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29953.
Анотація:
Silica-based monolithic HPLC columns contain a novel chromatographic support in which the traditional particulate packing has been replaced with a single, continuous network (monolith) of porous silica. The main advantage of such a network is decreased backpressure due to macropores (2 μM) throughout the network. This allows high flow rates, and hence fast analyses that are unattainable with traditional particulate columns.
The Chromolith SpeedROD™ (EM Science, Gibbstown NJ) is a commercially available silica-based monolithic column. This work investigated the chromatographic properties of the 50x4.60 mm (ODS) SpeedROD™. Data fit to the van Deemter equation (mean square error=0.834) indicated that the van Deemter model was valid for monolithic columns. An effective particle size of 4 μM for the SpeedROD™ column was assigned by comparing the minimum of van Deemter curves with a series of particulate columns having various particle diameters. Separation Impedance (E), an empirically derived measure of column performance, was calculated as an alternate method of evaluating column efficiency. Data collected using this model confirmed monolithic columns behaves as a (more efficient) 3 μM column.
A series of experiments were designed to compare the effects of mobile phase strength and mobile phase viscosity between the SpeedROD™ column and a particulate column. The results indicated both solvent strength and viscosity have effects on the monolithic column at the optimum linear velocity.
A fast (90 s) HPLC method was developed using the SpeedROD™ column and a seven-component test mixture with a large range of hydrophobicities. The precision for both retention time and peak area was measured at high linear velocities (8 mL/min) and the percent relative standard deviation (RSD) calculated. Column to column reproducibility (n=6) was measured. The overall percent RSD ranged from 0.25% to 4.56% for retention time and from 1.08% to 6.77% for peak area. Run to run reproducibility (n=15) was measured for all six columns. Averages ranged for retention time from 0.89% to 5.09% RSD and for peak area from 4.65% to 6.18% RSD.
Applications for the SpeedROD™ column with various sample types were developed and discussed. These methods demonstrated the effectiveness of the SpeedROD™ at fast flow rates.Ph. D.
2
El-Debs, Racha. "Synthèse de colonnes capillaires de monolithes de silice et développement d’un procédé photochimique simple, localisable et polyvalent de fonctionnalisation de leur chimie de surface." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10254.
Анотація:
Ce manuscrit est consacré à l’élaboration et à la photofonctionnalisation des monolithes de silice pour les techniques séparatives miniaturisées. La partie bibliographique situe d’abord l’intérêt des monolithes dans les techniques séparatives miniaturisées. L’état d’art sur l’utilisation des monolithes de silice dans ces techniques séparatives est ensuite établi en portant une attention particulière sur leur utilisation dans l’analyse d’échantillons biologiques et/ou environnementaux (préparation d’échantillons couplée aux méthodes séparatives ou utilisation de colonne de grande longueur). Un descriptif de la synthèse des monolithes de silice par le procédé sol gel est ensuite détaillé. Enfin, une étude des différentes méthodes de fonctionnalisation des monolithes de silice est présentée. L’optimisation des paramètres expérimentaux de la synthèse sol-gel a conduit à un procédé de synthèse robuste et répétable de capillaires monolithiques de silice de grandes longueurs et d’efficacités élevées (efficacités de l’ordre de 160 000-200 000 plateaux/m). Le travail expérimental s’est ensuite orienté sur l’optimisation de procédés de fonctionnalisation par voie thermique et sur le développement de nouveaux procédés de photopolymérisation ou de photografting par « photo click chemistry ». Les résultats obtenus dans des modes chromatographiques variés après photofonctionnalisation avec différents monomères montrent que ces procédés sont polyvalents et qu’un contrôle des paramètres permet de conserver les performances chromatographiques du matériau de départ. Outre sa simplicité et sa rapidité, cette approche permet de définir et de localiser différentes chimies de surface au sein d’une même colonne. Cette spécificité a été mise à profit pour le couplage en ligne dans une colonne de nanochromatographie, d’une étape de préconcentration avec une étape de séparation de neuropeptides modèlesThis manuscript is dedicated to the development and functionalization of monolithic silica stationary phases for miniaturized separation techniques. The bibliographic section first summarizes the interest of monolithic phases for the development of miniaturized separation techniques and their advantages over their particulate counterparts (small particles or core shell ones). The state of the art on the use of silica monolithic columns in separation techniques is then established, with a focus on their use in the analysis of biological and/or environmental samples (coupling sample preparation with an analysis method or using long columns). Then a detailed description of the sol gel synthesis of monolithic silica is presented. Finally, a study of different established methods of functionalization of silica monoliths is presented and the potential of photofunctionalization is highlighted for the rapid and homogeneous in-situ functionalization of monolithic capillaries. The experimental part focuses first on the development and optimization of a robust process of synthesis of monolithic silica capillary columns (efficiencies around 160 000-200 000 plates/m). The work is then focused on the improvement of classical functionnalization processes and on the development of new photofunctionalization ways (photopolymerization and photo click chemistry) of silica monolithic columns. The results obtained after photofonctionnalisation in various chromatographic modes (from ion exchange to reversed phase and HILIC) mode with different monomers show that these methods are versatile and that the control of the parameters allows keeping the chromatographic performances of the starting material. Besides its simplicity and speed, this approach allows to define and to locate different surface chemistries in the same column. This specificity has been exploited to the in-line coupling a preconcentration step with a separation step in a single column, for the separation of model neuropeptides
3
Khattab, Amin Khalid. "Fabrication, functionalization and characterization of silica monolith for forensic chemistry applications." Thesis, University of Hull, 2014. http://hydra.hull.ac.uk/resources/hull:10112.
Анотація:
The physiochemical properties of silica monolith make it an ideal base material for drugs extracting, pre-concentrating and separation from biological samples which can interact not only with molecules but also with ions and atoms. However, the fabrication of silica monoliths still has some problems, such as cost, limited capacity and fabrication and modification methodology, which can be time consuming and labour intensive. Structure evolution of silica monolith was studied in microwave and conventionally processed samples over the temperature range from 25 to 70 oC. The samples were produced using sol-gel processing. The microwave process was performed using a single mode cavity at 2.45GHz. Characterization of produced silica monoliths were carried out using a variety of techniques, including Scanning Electron Microscopy (SEM) analysis, EDX analysis, BET and BJH analysis. The data obtained showed that structural differences do exist between conventional and microwave processed samples. It was found however, that microwave based fabrication offered a significantly quicker (11 min) gelation process, compared to those obtained using the thermal heated oven methodology (4,320 min). The silica monolithic surfaces were modified with three different phases C₁₈, gold nanoparticles and graphene which received a thermal treatment at different programmed powers in two different ovens, conventional and microwave. Three substantial variance were also identified from the structural characterization of modified silica surfaces processed using microwave heating and conventional heating methods: 1- The use of microwave heating during C₁₈ surface modification improved not only the attachment of C₁₈ groups to the silica surface but also increased the extraction efficiency of caffeine and eserine from standard solutions (102 % and 97 %, respectively). 2- The fabrication of gold nanoparticles-NH2-silica monolith using microwave heating was found to improve the sensitivity and selectivity of modified silica surface and make possible to extract, detect and quantify more than one type of drugs of abuse at the same time within few minutes. 3- Using graphene-silica monolith makes the extraction of non-polar, polar, very polar and water-soluble analytes, based on both hydrophobic and electronic interactions, easy and simple. Fabrication and modification of silica monoliths using microwave heating make the sol-gel procedure much faster and easier and allow for non-polar, polar, very polar and water-soluble analytes to be extracted more efficiently to produce accurate and precise results compared to the conventional method for fabrication and modification of silica monoliths using three phases (C₁₈, gold nanoparticles and graphene). Finally, this technique make the modified silica monolithic column capable to extract selected drugs of abuse from biological samples and produce qualitative and quantitative results at the same time using chemiluminescence based immunoassays or HPLC-UV.
4
CALDAROLA, DARIO. "Silica beds and silica monoliths for pollutants removal and HPLC." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2506223.
Анотація:
This PhD thesis investigates mesostructured porous silica as a system for removal of pollutants and high performance liquid chromatography (HPLC). In these fields typically the materials used consist of a silica substrate modified with a compound, which has a high selectivity towards the analyte of interest. In this thesis two silica modifiers are proposed: cetyltrimetylammonium bromide (CTABr) and glyphosate.
The CTABr was actually the cationic surfactant used as template for the mesostructure, which was not removed from the silica framework as it usually is by calcination. This surfactant was used for the retention of haloacetic acids (HAACs) and nitrate ion. The glyphosate is an aminoacid present in many commercial herbicides and it has a high complexation capability towards metals. It was linked onto the silica surface using an appropriate reagent, the 3-glycidoxypropyltrimethoxysilane. The behavior of HAACs, NO3- and metals has been investigated because they are some of the most dangerous and monitored pollutants in water.
The chosen surface modifiers have been combined with two different systems: silica particles and silica monoliths. The silica particles have been used until the late 1990s for HPLC columns packing, and they are nowadays mainly used as adsorbents of compounds due to their elevated capacity and strong retention capability. The silica monoliths have become the state of the art in HPLC, because of their better mass transfer, higher efficiency and lower analysis time compared to particle packed columns.
Four materials have been prepared combining the two morphologies with each modifier. Physical-chemical characterization has been performed using several techniques (FTIR, N2 isotherms at 77 K, SEM-EDS, XPS and TGA) then the materials capabilities have been investigated in their respective fields of application.
The interesting results obtained with these brand new adsorbents may have a high impact over the fields of waters purification and analysis, which is one of the recent most important topics due to the huge raise of contaminants during the last 150 years.
5
Roux, Richard. "Synthèse de phase stationnaires monolithiques de silice hybrides pour les techniques séparatives miniaturisées." Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10208.
Анотація:
Ce manuscrit est consacré à la synthèse par procédé sol-gel et à la caractérisation de matériaux monolithiques de silice hybrides pour les techniques séparatives miniaturisées : nano-chromatographie en phase liquide (nano-CPL), électrochromatographie capillaire (ECC) et microsystèmes séparatifs. La partie bibliographique situe les axes de développement récents des techniques séparatives : l’augmentation de l’efficacité par unité de temps, l’augmentation de la capacité de pics et la miniaturisation de ces techniques. Après un descriptif détaillé de l’évolution des techniques séparatives lors de ces dernières années, une attention particulière est portée sur les phases stationnaires monolithiques à base de silice. Enfin, une étude approfondie des différentes fonctionnalisations de ces monolithes de silice met en évidence l’intérêt porté aux monolithes de silice hybrides en termes de simplification du protocole de synthèse. La partie expérimentale est ainsi axée sur le développement et la caractérisation de ces monolithes de silice hybrides dédiés à la chromatographie à polarités de phases inversée. Dans un premier temps, la synthèse de monolithes de silice hybrides C3 illustre la possibilité de synthétiser par voie sol-gel (100% aqueux) un monolithe de silice fonctionnalisé et performant en une seule étape (« one pot »). Dans un second temps, ce type de procédé est employé et optimisé afin de synthétiser des capillaires monolithiques de silice hybrides C8 présentant des performances équivalentes à leurs homologues C8 préparés en deux étapes (synthèse puis greffage) et comparables à des colonnes particulaires (d particules 5 μm)This manuscript is dedicated to the synthesis (via sol-gel process) and caracterization of hybrid monolithic silica for miniaturized separation techniques : nano-liquid chromatography (nano-LC), capillary electrochromatography (CEC) and microchips. The bibliography part deals with the recent axis of development of these separatives techniques : increase of efficiency per time unit, increase of peak capacity and miniaturisation of these techniques. After an overview of this evolution, the manuscript is focused on the silica monolithic stationnary phases. Finally, a detailed study on the different kinds of protocol fonctionnalization of these silica monoliths highlights the advantage of simplifying the synthesis using a single step protocol (« one pot »). The experimental part is also focused on this kind of single step protocol so as to synthesize hybrid silica monoliths dedicated to the reversed phase mode in chromatography. First, the synthesis of hybrid C3 silica monoliths shows the ability to synthesize a functionnalized silica monolith via a single step sol gel process (« one pot »). Then, this kind of process is used and optimized in order to synthesize a hybrid C8 silica monolithic into capillaries. These stationary phases allowed reaching performances similar to those synthesized in two steps (sol-gel process and grafting) and to the particulate columns (5 μm)
6
Zhang, Tong. "Preparation, characterization, modification and application of hybrid silica-based monolith in capillary electrochromatography." Thesis, University of Strathclyde, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487859.
Анотація:
Hybrid silica-based monoliths (prepared with tetramethoxysilane and methyltrimethoxysilane 3:1 v/v) were prepared in 100μm I.D. capillaries using a sol-gel technique. Although good electrochromatographic repeatability was shown on a single hybrid silica-based monolithic capillary poor reproducibility of the preparation was evidenced by the small number of good quality columns obtained in this study.
7
Marechal, Audrey. "Colonnes monolithiques multimodales photofonctionnalisées dédiées aux techniques séparatives miniaturisées." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10308/document.
Анотація:
Une des évolutions dans le domaine de l'analyse chimique concerne la miniaturisation des systèmes d'analyse. Cette tendance s'accompagne du développement de nouvelles approches expérimentales basées, par exemple, sur l'intégration de plusieurs étapes analytiques, couplées en ligne en système miniaturisé. Cette intégration, en ligne, d'étapes mettant en jeu des mécanismes de séparation différents et généralement orthogonaux, implique cependant d'être capable de définir des zones (segments de colonne vides et/ou remplis de phase stationnaire) présentant des chimies de surface adaptées. L'approche choisie pour la préparation de ces colonnes " multimodales ", repose sur (1) la synthèse d'un monolithe de silice poreux "générique " dans des tubes capillaires de quelques dizaines de microns de diamètre interne et (2) la modification de surface localisée dans le capillaire permettant d'apporter des propriétés de surface complémentaires. Dans le cadre de cette thèse, deux procédés de fonctionnalisation innovants, initiés par photochimie, ont été développés pour la préparation des colonnes multimodales miniaturisées : la photopolymérisation, basée sur des réactions de polymérisation radicalaire, et la " photoclick chemistry ", basée sur un greffage radicalaire contrôlé (et non plus une polymérisation). Un état de l'art de leur utilisation en sciences séparatives a été dressé pour chacun des procédés, afin de guider le choix des stratégies de greffage. Après une optimisation des conditions de greffage, les résultats présentés dans ce manuscrit montrent que ces procédés de fonctionnalisation sont rapides (fonctionnalisation en quelques minutes), efficaces, polyvalents (transposables à de multiples greffons) et localisables. Leurs potentiels respectifs dans la préparation des colonnes multimodales ont ensuite été démontrés pour la préconcentration/séparation en ligne de plusieurs composés. L'approche par " click chemistry " qui permet un meilleur contrôle du greffage, a été étendue au greffage de biomolécules pour la préparation de supports d'immunoaffinité. Ainsi, une colonne multimodale composée d'une première zone remplie de monolithe photogreffée avec des aptamères et une deuxième zone vide a été préparée pour la préconcentration/séparation électrocinétique en ligne de l'Ochratoxine AMiniaturization of analytical processes is a general trend in analytical chemistry. Such trend is driven by the development of new experimental approaches based, for example, on hyphenated analytical steps or techniques. The in-line coupling of different and generally orthogonal/complementary separation mechanisms at the microscale, is dependent on the capability to define functional segments (open column segments and/or filled with stationary phase). Preparation of such "multimodal" capillary columns is based on (1) the in-capillary synthesis of a "generic" porous silica monolith and (2) on its localized chemical surface modification to define specific functional segments. Herein, two innovative photo-functionalization processes have been investigated for the preparation of multimodal miniaturized columns. The former, called photopolymerization is based on acrylate free radical polymerization reactions while the latter, called photografting, implements the thiol-ene "photoclick chemistry" reaction. These photo-initiated processes, after optimization, prove to be rapid (within few minutes), versatile (adapted to the grafting of various monomers) and localizable. Photopolymerization of acrylate monomers on activated silica monolith (using ?-methacryloxypropyltrimethoxysilane) gives rise to highly retentive columns due to the polymeric nature of the layer obtained. Photografting of octadecanethiol on vinylized silica columns leads to monolayer-like coating. The preparation of dedicated multimodal columns using such approaches was then successfully applied to the in-line preconcentration / separation of neuropeptides and preconcentration / fractionation of various neutral and charged compounds. The "click chemistry" approach which allows a better control of the reaction, has been extended to the grafting of biomolecules for the preparation of immunoaffinity supports. Thus, a multimodal column composed a 1-cm length aptamer-functionalized monolith at the entrance of a CZE open capillary has been prepared and successfully applied to the in-line preconcentration/electrokinetic separation of Ochratoxin A in white wine and beer
8
Izaak, T. I., D. О. Martynova, V. V. Maas, E. М. Slavinskaya, А. I. Boronin, and Y. W. Chen. "Synthesis and Properties of Ag / CuO / SiO2 Nanocomposites." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35611.
Анотація:
In this paper the composites Ag / SiO2 with regularly distributed in bulk matrix silver and copper oxide nanoparticles were synthesized. Herewith, copper ions was introduced into porous support at the stage of sol-gel synthesis. Sample Ag / CuO / SiO2 was tested by the catalytic reaction of CO oxidation and com-pared with Ag / SiO2. It was revealed that sample with introduced copper show lower activity .This fact can be explained by formation of silver cuprate during preparation of composite Ag / CuO / SiO2. Treatment by reaction mixture (CO and O2) led to release of silver in ionic, clusters and metal states that increased cata-lytic activity of the composite.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35611
9
Souza, Israel Donizéti de. "Desenvolvimento de fases monolíticas de sílica híbrida para microextração em sorvente empacotado (MEPS) de fármacos em amostras de plasma e análise por cromatografia líquida acoplada a espectrometria de massas em tandem (LC-MS/MS)." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-02092015-093155/.
Анотація:
Segundo a Organização Mundial da Saúde (OMS), a esquizofrenia é reconhecida como um transtorno neuropsiquiátrico grave que afeta mais de 21 milhões de pessoas em todo o mundo. Para diminuir os sintomas associados a esta doença, a maioria dos pacientes esquizofrênicos fazem uso concomitantemente de antipsicóticos, antidepressivos, ansiolíticos e anticonvulsivantes. O desenvolvimento de métodos analíticos para a determinação desses fármacos em fluidos biológicos é importante para ajustar as doses administradas, minimizar os efeitos adversos e verificar a anuência do paciente à terapia. A química analítica moderna tem se direcionado para a simplificação, através da miniaturização dos sistemas analíticos. Neste contexto, pode-se destacar a técnica de microextração em sorvente empacotado (MEPS). O desenvolvimento de novas fases extratoras para MEPS, como, os monolitos de sílica híbrida permitem pré-concentração seletiva dos analitos. Neste projeto monolitos de sílica híbrida funcionalizados com grupos aminopropil ou cianopropil foram sintetizados pelo processo sol-gel. Estes monolitos apresentaram estrutura contínua, uniforme e porosa, como evidenciado pelas imagens de microscopia eletrônica de varredura (MEV). As análises de espectroscopia vibracional na região do infravermelho por transformada de Fourier (FTIR) dos monolitos de sílica híbrida exibiram picos facilmente identificáveis, característicos dos grupos cianopropil e aminopropil. Estes monolitos foram avaliados como fase estacionária para a MEPS para a determinação de fármacos em amostras de plasma por cromatografia líquida acoplada a espectrometria de massa em Tandem (LC-MS/MS). As variáveis MEPS (influência do pH na sorção dos analitos, número de ciclos aspirar/dispensar, etapa de limpeza do sorvente e solvente de eluição) foram otimizadas para aumentar a eficiência da extração. Em comparação com a fase de sílica híbrida aminopropil, a fase de sílica híbrida cianopropil apresentou maior capacidade de sorção para os fármacos em estudo. O método desenvolvido, MEPS/LC-MS/MS, empregando a fase extratora de sílica híbrida cianopropil, apresentou linearidade adequada com concentrações que variaram desde o limite inferior de quantificação (0,05-1,00 ng.mL-1) até o limite superior de quantificação (40-10.500 ng.mL-1) com coeficientes de determinação (R2) maiores do que 0,9955. Este método apresentou precisão com coeficientes de variação (CV) inferiores a 14% e exatidão com erro padrão relativo (EPR) de -12 a 14%. O método MEPS/LC-MS/MS foi aplicado com êxito para análise simultânea de cinco antipsicóticos (olanzapina, quetiapina, clozapina, haloperidol e clorpromazina), em combinação com sete antidepressivos (mirtazapina, paroxetina, citalopram, sertralina, imipramina, clomipramina e fluoxetina), dois anticonvulsivantes (carbamazepina e lamotrigina) e dois ansiolíticos (diazepam e clonazepam) em amostras de plasma de pacientes esquizofrênicos para fins de monitorização terapêutica.According to World Health Organization (WHO), schizophrenia is recognizably a devastating neuropsychiatric disorder that affects more than 21 million people worldwide. To lessen the symptoms associated with the disease, most schizophrenic patients use other classes of drugs such as antidepressants, anxiolytics, and anticonvulsants concomitantly with antipsychotics. Developing analytical methods to quantify these drugs in biological fluids is important in therapeutic drug monitoring (TDM) to adjust doses, minimize adverse effects, and check patient adherence to the therapy. Regarding miniaturization and automation, microextraction by packed sorbent (MEPS) is a promising sample preparation technique. Sample preparation of biological matrixes is an important step in analytical processes: it removes endogenous components from the sample and pre-concentrates trace-level analytes. The development of new phases for MEPS such as the hybrid silica monoliths allows selective pre-concentration of the analytes. The present study reports on the synthesis of two hybrid silica monoliths functionalized with aminopropyl or cyanopropyl groups by the solgel process; evaluates these monoliths as selective stationary phase for MEPS to determine drugs in plasma samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS); and discusses important factors (influence of pH on the sorption of analytes, number of draw/eject cycles, washing step, and elution solvent) related to the optimization of MEPS efficiency. The prepared hybrid silica monoliths consisted of a uniform, porous, and continuous silica monolithic network, as shown by scanning electron microscopy (MEV) images. The Fourier-transform infrared spectroscopy (FTIR) spectra of the hybrid silica monoliths displayed readily identifiable peaks, characteristic of the cyanopropyl and aminopropyl groups. Compared with the aminopropyl hybrid silica phase, the cyanopropyl hybrid silica phase exhibited higher binding capacity for most of the target drugs. The developed method, MEPS/LC-MS/MS, afforded adequate linearity at concentrations ranging from the lower limit of quantification (0.05 to 1.00 ng.mL-1) to the upper limit of quantification (40 to 10500 ng.mL-1); the coefficients of determination (R2) were higher than 0.9955. The precision of the method presented coefficients of variation (CV) lower than 14%; the relative standard error (RSE) of the accuracy ranged from -12 to 14%. The developed MEPS/LC-MS/MS method allowed for simultaneous analysis of five antipsychotics (olanzapine, quetiapine, clozapine, haloperidol, and chlorpromazine) in combination with seven antidepressants (mirtazapine, paroxetine, citalopram, sertraline, imipramine, clomipramine, fluoxetine), two anticonvulsants (carbamazepine and lamotrigine), and two anxiolytics (diazepam and clonazepam) in plasma samples from schizophrenic patients, which should be valuable for TDM purposes.
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Fleury, Joachim. "Développement de phases stationnaires monolithiques pour la chromatographie en phase gazeuse miniaturisée ultra-rapide." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066652.
Анотація:
La miniaturisation des systèmes conventionnels de chromatographie en phase gazeuse (CPG) est d’un intérêt majeur pour de nombreuses applications. L'objectif est d'aboutir à des améliorations des systèmes existants, en termes de portabilité et d’autonomie, mais aussi en termes de durée d’analyse et de coût. In fine, ces systèmes miniaturisés de CPG pourraient être utilisés directement sur le terrain pour de l’analyse en continu presque en temps réel. Dans ce contexte, ce projet de thèse a consisté à développer des phases stationnaires monolithiques à base de silice afin de séparer, de manière ultra-rapide, des composés très volatils tels que des alcanes légers C1-nC5. Dans une première partie, la synthèse d’un monolithe de silice in situ dans des capillaires de 75 µm d.i. a été optimisée via une approche sol-gel de manière à adapter la perméabilité, et donc la structure macroporeuse des matériaux aux écoulements gazeux. Nous avons pu ainsi obtenir, pour la première fois, des séparations rapides C1-nC5 en CPG à des pressions conventionnelles en tête de colonne (Pin < 4 bar). Le second volet de cette thèse a consisté à optimiser et contrôler l’état de surface des monolithes par l’élaboration de deux traitements post-synthèse différents ayant pour objectif l’élimination du porogène organique résiduel. Des séparations C1-nC5 ultra-rapides (à l’échelle de quelques secondes) à haute température et en régime isotherme ont pu être obtenues en raison de la rétention et de l’efficacité élevées des matériaux. Enfin, le rendement, la répétabilité et la reproductibilité de la synthèse des monolithes de silice ont été étudiés afin d’évaluer leur potentielle fabrication à grande échelleThe miniaturization of conventional gas chromatography (GC) systems is of major interest for many applications. The aim is to achieve improvements in existing systems, in terms of portability and autonomy, but also in terms of analysis time and cost. Ultimately, these miniaturized GC systems could be field-portable for near real-time continuous monitoring. In this context, this PhD project consisted in developing silica-based monolithic stationary phases in order to obtain ultra-fast separation of very volatile compounds such as C1-nC5 light alkanes. First of all, in situ synthesis of a silica monolith in capillaries of 75 μm i.d. has been optimized via a sol-gel approach in order to adapt the permeability, and therefore the macroporous structure of the materials, for gas flows. For the first time, fast C1-nC5 separations were obtained at conventional column inlet pressures (Pin < 4 bar). The second part of this PhD project consisted in optimizing and controlling the surface state of the monoliths by the development of two different post-synthesis treatments with the objective of eliminating the residual organic porogen. Ultra-fast C1-nC5 separations (at a few seconds) at high temperature and isothermal conditions were achieved due to the high retention and efficiency of the materials. Finally, the yield, repeatability and reproducibility of silica monoliths synthesis were studied in order to evaluate their potential large-scale production
11
Courtois, Julien. "Monolithic separation media synthesized in capillaries and their applications for molecularly imprinted networks." Doctoral thesis, Umeå : Department of Chemistry, Umeå Univ, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-923.
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Gutiérrez, Ponce María de Jesús Santa. "Síntese e caracterização de nova fase monolítica para eletrocromatografia capilar usando método sol-gel." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249684.
Анотація:
Orientador: Carla Beatriz Grespan BottoliTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
Made available in DSpace on 2018-08-19T09:05:26Z (GMT). No. of bitstreams: 1 GutierrezPonce_MariadeJesusSanta_D.pdf: 3412773 bytes, checksum: 0fb510ed608f7a239752ee164a4215ad (MD5) Previous issue date: 2011
Resumo: Monolitos à base de sílica têm sido usados como fases estacionárias em eletrocromatografia capilar e apresentam vantagens em relação aos materiais particulados tais como: melhor homogeneidade; controle do tamanho dos poros; alta estabilidade mecânica e térmica; minimização da formação de bolhas e diminuição de problemas com filtros. O presente trabalho teve como objetivo a síntese e caracterização de uma nova fase estacionária monolítica à base de sílica com grupos carboxílicos em sua estrutura, os quais ajudam a sustentar o fluxo eletrosmótico e conferem características de troca catiônica à fase. A fase estacionária monolítica foi sintetizada empregando o processo sol-gel. A síntese do agente sililante foi feita a partir de ácido 4-aminobenzóico e trietóxipropilisocianatossilano. A derivatização da fase estacionária monolítica foi feita adicionando-se ao monolito uma solução de 10% do silano em DMF e deixando reagir por 6 horas a 60 °C. A fase estacionária monolítica funcionalizada foi avaliada por microscopia eletrônica de varredura, espectroscopia no infravermelho e análise elementar. A fase estacionária também foi testada com um equipamento de eletroforese capilar construído no laboratório com detecção condutométrica sem contato (CD) e um equipamento de eletroforese capilar Agilent com detecção UV. Os resultados da microscopia eletrônica confirmaram a formação do monolito dentro do capilar e a espectroscopia no infravermelho, bem como a análise elementar permitiram caracterizar tanto o monolito como o silano empregado na funcionalização do monolito. Na avaliação com detector CD foram separados cátions e aminoácidos, evidenciando a característica de troca catiônica da fase. Na avaliação com detector UV foi confirmada a falta de seletividade da fase para compostos apolares, mas, foram separados alguns fármacos básicos com boa resolução e formato de pico o que indica a possibilidade de aplicação da nova fase em separações de compostos básicos
Abstract: Monoliths are used as stationary phases in capillary electrochromatography since they can effectively overcome the difficulties associated with packed capillary column technology. A remarkable advantage of monolithic columns is the elimination of the end frits required to retain particulate stationary phases. The aim of the present study was to synthesize and characterize a new silica-based monolithic stationary phase with carboxylic groups in its structure, which help to support the electroosmotic flow and confer characteristics of cation-exchange to the phase. The formation of the monolith inside the capillary was achieved using the sol-gel method. The silylant agent was made from 3-(triethoxysilyl)propylisocyanate and 4-aminobenzoic acid. The surface modification of the monolith with the silylant agent used a 10% solution in DMF, left to react for 6 h at 60 °C. The modified monolithic column was evaluated by scanning electron microscopy, infrared spectroscopy and elemental analysis. The column was tested using a homemade capillary electrophoresis system with a capacitively coupled contactless conductivity detector (CD) and with Agilent capillary electrophoresis equipment with UV detection. The results of scanning electron microscopy confirmed the formation of the monolith while infrared spectroscopy and elemental analysis characterized the synthesized silylant agent used in the modification of the monolithic column as well as the modified monolith. In evaluations with the CD cations and amino acids were separated, showing the characteristics of a cation-exchange phase. With UV detection the lack of phase selectivity for apolar compounds was confirmed, but some basic drugs were separated with good resolution and peak shape, which indicates the possibility of applying the new phase in separations of basic compounds
Doutorado
Quimica Analitica
Doutor em Ciências
13
Venet, Saphir. "Stockage du CO2 et séparation CO2/CH4 par des matériaux de silice à porosité et fonctionnalité contrôlées : étude expérimentale et modélisation de dynamique moléculaire." Thesis, Pau, 2018. http://www.theses.fr/2018PAUU3027/document.
Анотація:
Ce travail vise à évaluer les performances de matériaux à base de silice et à rationaliser leur synthèse en fonction des propriétés d’adsorption recherchées (capacité et/ou sélectivité) en combinant des approches expérimentales et la modélisation de dynamique moléculaire. Ces matériaux devaient idéalement présenter une capacité d’adsorption CO2 mais également une sélectivité CO2 /CH4 élevées. Les différentes étapes de ce travail ont été :- la synthèse et la fonctionnalisation des matériaux de silice,- leur caractérisation texturale et chimique,- la détermination des capacités d’adsorption du CO2, de leur sélectivité CO2/CH 4 ,- les caractérisations par différentes techniques spectroscopiques et microscopiques des échantillons pour essayer de localiser l’adsorption du CO2 et mesurer sa mobilité,- l’identification microscopique par modélisation moléculaire des facteurs physico-chimiques influant sur l’adsorption préférentielle du CO2 et sa diffusivité dans le matériau hôte ainsi que sur le rôle du caractère hydrophile/hydrophobe du matériau de silice par le biais de sa fonctionnalisation.Ces objectifs ont nécessité la préparation de matériaux à surfaces spécifiques élevées par le biais d’un procédé sol-gel simple. Ces matériaux ont été modifiés afin d’obtenir un taux de fonctionnalisation par des groupements -CH3 suffisant pour modifier le caractère hydrophile du matériaux tout en conservant une surface spécifique suffisante. L’influence de la taille des pores a également été sondée.Les capacités d’adsorption des gaz sous pression ont été réalisées pour les gaz purs mais également sur des mélanges CO2/CH4 dans différentes proportions. La sélectivité CH 4 /CO 2 , souvent estimée à partir des isothermes des corps purs et/ou la méthode IAST, a dans ce cas été déterminée à partir de la mesure directe des isothermes des mélanges de gaz. Il est apparu que l’eau joue un rôle crucial sur les capacité et sélectivités d’adsorption. Ce paramètre est l’un de ceux qui a été étudié à travers les simulations de dynamiques moléculaires. L’influence de l’introduction de groupements hydrophobes a également été exploré.Les résultats obtenus par dynamique moléculaire sont dans l’ensemble en bon accord avec les données expérimentales. Ces deux approches parallèles expérience/théorie ont mis en évidence la sélectivité de l’un des matériaux pour des applications où l’effluent gazeux est peu chargé en CO 2This work aims to evaluate the performance of silica-based materials and to rationalize their synthesis according to their desired adsorption properties (capacity and/or selectivity) by combining experimental approaches and the management of the molecular animal. These materials are ideally suited for CO2 adsorption capacity but also CO2/ CH4 selectivity. The different stages of this work were:- the synthesis and functionalization of the silica materials,- their textural and chemical characterization,- the determination of CO2 adsorption capacities, of their CO2/ CH4 selectivity.- the characterizations by various spectroscopic and microscopic techniques of tests to try to locate the adsorption of CO2 and to measure its mobility,- microscopic identification by the factor of physic-Factors influence the preferential adsorption of CO2 and its diffusivity in the role of hydrophilic / hydrophobic character in silica by functional.These objectives required the preparation of high specific surface materials through a simple sol-gel process. These materials have been modified in order to obtain a degree of functionalization with -CH3 groups sufficient to modify the hydrophilic nature of the material while maintaining a sufficient specific surface area. The influence of pore size was also probed.The adsorption capacities of the gases under pressure were carried out for pure gases but also on CO2/ CH4 mixtures in different proportions. The CH4/ CO2 selectivity, often estimated from the pure body isotherms and / or the IAST method, was in this case determined from the direct measurement of the isotherms of the gas mixtures. It has become apparent that water plays a crucial role in adsorption capacity and selectivity. This parameter is one of those studied through molecular dynamics simulations. The influence of the introduction of hydrophobic groups has also been explored.The results obtained by molecular dynamics are on the whole in good agreement with the experimental data. These two parallel experience / theory approaches have highlighted the selectivity of one of the materials for applications where the gaseous effluent is little loaded with CO2
14
Lynch, John. "Encapsulation of Bacterial Endospores in Silica Aerogel Monoliths." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1385114520.
15
Ahmad, Sher. "Traitement des eaux contenant de la tétracycline avec la laccase de Trametes Versicolor immobilisée sur des monolithes de silice macroporeux." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTG034.
Анотація:
Dans ce travail de recherche, des monolithes en silice présentant une très grande porosité (83 %), une double distribution de taille de pores (des macropores de diamètre 20 μm et des méseopores de diamètre 20 nm) et une très grande surface spécifique (370 m2 g-1) ont été utilisés comme supports pour immobiliser une laccase de Trametes versicolor par greffage covalent avec du glutaraldéhyde. Les monolithes enzymatiques ont été utilisés pour dégrader la tétracycline (TC) en solution aqueuse dans un réacteur de configuration tubulaire type "Flow Through Reactor" avec recyclage. Au cours des 5 premières heures de réaction à pH 7 ; 40 à 50 % de la TC a été dégradée, puis un seuil a été atteint. Une des hypothèses pouvant expliquer ce comportement est un éventuel manque de co-substrat (oxygène) à proximité des sites catalytiques. Des monolithes enzymatiques ont été utilisés pendant 75 h de fonctionnement séquentiel sans perte d'activité. L'efficacité de la dégradation de la TC a pu être simulée à travers un modèle mathématique construit en couplant la cinétique de la réaction (Michaelis-Menten) avec un bilan matière en régime dynamique. Les résultats de la simulation ont révélé que le procédé global est contrôlé par la cinétique enzymatique mais que la taille des monolithes pouvait être adaptée pour dégrader 100 % de la CT en un seul passage à travers un monolitheIn this research work, silica monoliths with high porosity (83 %), double pore size distribution (20 μm and 20 nm macro- and mesopores diameters, respectively) and high surface area (370 m2 g-1) have been used as solid supports to immobilize a laccase from Trametes versicolor by covalent grafting with glutaraldehyde. Enzymatic monoliths were applied to degrade tetracycline (TC) in aqueous solutions in a tubular “Flow Through Reactor” configuration with recycling. During the first 5h of reaction at pH 7, 40–50% of TC was degraded, and then a threshold was reached. One of the hypotheses explaining this behaviour is a possible co-substrate lack (oxygen) near catalytic sites. Enzymatic monoliths were used during 75 h of sequential operation without losing activity. A mathematical model built coupling the Michaelis-Menten reaction kinetics with a dynamic mass balance allowed computing TC degradation efficiency. Simulation results revealed that the global process is controlled by the enzymatic kinetics but the monolith size could be adapted to degrade 100 % TC in a single pass
16
Smått, Jan-Henrik. "Hierarchically porous silica, carbon, and metal oxide monoliths : synthesis and characterization /." Turku : Åbo akademi University, 2006. http://catalogue.bnf.fr/ark:/12148/cb409697351.
17
Khadra, Ibrahim A. "Preparation, characterization and evaluation of silica based monoliths in capillary electrochromatography." Thesis, University of Strathclyde, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432083.
18
Wehring, Markus, Jan-Henrik Smått, Mika Lindén, Frank Stallmach, and Jörg Kärger. "NMR studies on silica monoliths - diffusion in a hierarchical pore structure." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194114.
19
Wehring, Markus, Jan-Henrik Smått, Mika Lindén, Frank Stallmach, and Jörg Kärger. "NMR studies on silica monoliths - diffusion in a hierarchical pore structure." Diffusion fundamentals 6 (2007) 71, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14251.
20
Cao, Shengli. "Preparation, characterization and applications of monolithic titania-silica aerogels /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202007%20CAO.
21
Ahmed, Adham Saleh. "Morphology control on porous monoliths and silica microspheres and applications in chromatography." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569199.
Анотація:
Silica-based stationary phases have been under investigation since they were first produced, and studies still continue to try to improve their morphology and porosity. A handful of reliable and straightforward synthetic procedures are used routinely for their manufacture. The most widely applied procedures are variations of the modified Stober synthesis route that allow the manufacture of relatively monodisperse particles in the nanometer range, or the sol-gel route that produces larger porous microstructures. However, the controlled manufacture of silica stationary phase with the desired physical properties is still a challenge, and most of their preparation involves multi-step preparation, adding cost and time. This dissertation outlines work that introduces a set of new protocols that were developed for the preparation of silica with controlled morphology and porosity. Herein, silica microspheres with tuneable pore size and particle size distribution were synthesised using a modified Stober method. Hydrophilic polymers were introduced into the reaction system, which acted as stabilising agent. Further altering the reaction parameters resulted in the formation of silica microspheres with controlled surface morphology, beads-on-bead silica particles. The preparation conditions were extensively studied in order to understand the reason for such phenomena. The beads-on-beads particles exhibit chromatographic potential, especially for proteins separation. Moreover, porous silica microspheres were further used for the preparation of hierarchically porous silica monoliths by a controlled freezing approach. The macropore morphologies could be tuned with the addition of surfactants in the silica colloidal suspensions during the freezing process. The engineering of porosity and improvement on mechanical stability of the silica materials were achieved through a further soaking and sol-gel process. It was also possible to enhance the mechanical stability through thermal treatment of the materials. Directional freezing approach was also evaluated to direct the assembly of silica nanoparticles. The presence of water-soluble polymers resulted in better aligned features and acted as a gelling agent in the case of charged polymer. The monolith was successfully prepared inside a fused-silica capillary column and was investigated for chromatographic applications. Preformed emulsion-templated porous polyacrylamide beads and monolith were used as a scaffold for controlled growth of silica spheres on macroporous surface. A hierarchical hybrid structure was formed. The polymer scaffold could be removed to form porous silica spheres and macroporous structures. Further investigation was considered to control the porosity and the size of the forming microspheres. This study was further extended into the preparation of fluorescent silica spheres and composite materials. Furthermore, a simple and generic method was also developed for the preparation of gradient emulsion-templated structures. The gradient could be achieved with the aid of centrifugation mechanism. This method enabled the formation of dual gradient mesoporous and macroporous composites.
22
Iapichella, Julien. "Structuration hiérarchique des particules et des monolithes siliciques pour la chromatographie." Montpellier 2, 2006. http://www.theses.fr/2006MON20180.
Анотація:
Cette thèse traite de deux types de morphologies de silices poreuses : les particules et les monolithes. Suivant leur morphologie, ces matériaux siliciques possèdent des performances chromatographiques variables. En travaillant sur de tels matériaux pour la chromatographie, il est donc capital de se préoccuper de leurs morphologies. Il est possible de structurer la mésoporosité de ces matériaux siliciques en MTS (Matériaux aux Tensioactifs Structurants) tout en conservant leur morphologie initiale. Par ce procédé, appelé transformation pseudomorphique, nous avons pu obtenir différents matériaux particulaires mésostructurés (MCM-41, MCM-48 et MTS), issus du même précurseur silicique (Lichrospher 60 commercialisée). Tous ces matériaux ont pu être utilisés pour des applications séparatives en chromatographie liquide. Cette étude nous a permis de comprendre l’influence des différents types de mésostructuration sur les performances chromatographiques. La perméabilité des monolithes siliciques permet de séparer des solutés à très haute vitesse sans générer de perte de charge. Le procédé sol-gel de synthèse, de ces matériaux, permet de contrôler indépendamment la méso- et la macroporosité. De plus ce procédé semble être la voie la plus prometteuse pour travailler sur la miniaturisation de systèmes analytiques. La transformation pseudomorphique, sur les monolithes siliciques, a permis d’ordonner la mésoporosité au sein de ces matériaux qui sont déjà poreux à 80%. Le greffage d’alkylsilane a permis de fonctionnaliser divers matériaux siliciques amorphes et structurés obtenus au cours de la thèse (MCM-41 et MTS, particules et monolithes). Les taux de recouvrement, avant et après mésostructuration par pseudomorphisme, nous ont permis de mieux comprendre les propriétés chimiques de la surface de ces matériaux. Après fonctionnalisation, toute forme de silice poreuse présente une grande stabilité mécanique (jusqu’à 3000 Bars). Les phases particulaires, mésostructurées par pseudomorphisme et fonctionnalisées par des alkylsilanes, peuvent être utilisées pour la chromatographie en phase inverse et même sous de haute pression
23
Epelde, Elezcano Nerea. "Matériaux Hybrides nanostructures photoactifs pour des applications optiques et biomédicales." Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3007/document.
Анотація:
Dans ce manuscrit, la synthèse et la caractérisation complète de différents matériaux hybrides dédiés à des applications dans le domaine optique ou thérapeutique sont décrites. Dans un premier temps, des systèmes macroscopiquement ordonnés sont obtenus par intercalation de colorants tels que le Styryl 722 ou la pyronine-Y dans plusieurs films à base d’argile de type smectite. Les films d’argile sont élaborés par spin-coating et les colorants intercalés par immersion des films dans les solutions de ces colorants. Les effets de l’argile sur les propriétés des colorants sont analysés en détail et leur orientation préférentielle dans l’espace inter-couches est étudié grâce à la réponse anisotropique des films en lumière linéairement polarisée. Dans la deuxième partie, la synthèse par chimie sol-gel de monolithes de silice de grande dimension contenant des colorants laser présentant une forte absorption et une émission de fluorescence dans le visible est abordée. Des colorants laser à l’état solide (SSDL) avec de bonnes stabilités photochimique, thermique et chimique sont ainsi proposés. Dans le troisième chapitre, la synthèse par voie sol-gel de nanoparticules de silice (NP) d’environ 50 nm de diamètre fonctionnalisées sur leur surface externe est ensuite décrite. Grâce à l’encapsulation de molécules de colorants fluorescents dans leur cœur et le greffage de photosensibilisateurs sur leur écorce, des nanoparticules biocompatibles adaptées à la bio-imagerie et la thérapie photodynamique (PDT) ont été préparées. Pour optimiser leurs performances, les propriétés photophysiques et plus particulièrement la production d’oxygène singulet d’une nouvelle série de photosensibilisateurs basés sur les chromophores de type PODIPY ont d’abord été étudiées en détail. A partir de ces résultats, des BODIPY particulièrement efficaces ont été greffés sur les nanoparticules de silice afin de les utiliser pour la PDT. Les propriétés photophysiques de ces matériaux ont été analysées par spectroscopie d’absorption et de fluorescence (stationnaire ou résolue en temps) et les rendements quantiques de production d’oxygène singulet déterminés par des méthodes directe (émission de luminescence de l’oxygène singulet à 1270 nm) ou indirecte (utilisation de sondes chimiques spécifiques à l’oxygène singulet). Par ailleurs les matériaux hybrides ont été complètement caractérisés par plusieurs techniques (SEM, TEM, XRD, XPS, IR, DLS, BET)Along this manuscript different hybrid materials are synthesized and extensively characterized for several uses: from optical to therapeutic applications. First, by the intercalation of different dyes, styryl 722 and pyronine-Y into several smectite clay films, macroscopically ordered system are obtained. Clay films are elaborated by spin-coating technique and the dyes are intercalated by the immersion of clay thin films into dye solutions. The effect of clay on the dye properties is deeply analyzed and its preferential orientation in the interlayer space of the clay is studied by the anisotropic response of the films to the linear polarized light. Second, large silica monoliths with embedded laser dyes with strong absorption and fluorescence bands in different region of the Visible spectrum are attained by sol-gel chemistry to obtain solid-state dye laser (SSDL) with good photo, thermal and chemical stabilities. Third, silica nanoparticles (NP) with suitable size (50 nm) and functionalized external surface are also synthesised by sol-gel chemistry. Through the encapsulation of fluorescent dye molecules in their core and by the grafting of photosensitizers on their shell, biocompatible nanoparticles for bio-imaging and Photodynamic Therapy (PDT) applications are prepared. In order to optimize their properties, a careful investigation of the photophysical properties and mainly the singlet oxygen generation of a large range of new photosensitizers based on chromophores known as BODIPYs, is previously carried out. Based on these results, some efficient BODIPYs are selected for grafting on silica nanoparticles in order to use them for PDT. The photophysical properties of all these hybrid materials are analyzed by absorption and fluorescence (steady-state and time correlated) spectroscopies, and the singlet oxygen measurements are monitored by direct method (recording the singlet oxygen luminescence at 1270 nm) and by indirect method (using selective chemical probe). Moreover, the hybrid materials are fully characterized by several techniques such as, SEM, TEM, XRD, XPS, IR, DLS, BET
24
Ishizuka, Norio. "Studies on structure control and chromatographic properties of monolithic silica column." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149779.
25
Saito, Haruko. "Formation Process and Liquid Transport of Sol-gel Derived Monolithic Porous Silica." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/57273.
26
Feng, Airong. "Monolithe polymérique ou à base de silice pour la préconcentration couplée à l'électrophorèse capillaire pour l'analyse de biomolécules." Paris 11, 2010. http://www.theses.fr/2010PA114823.
Анотація:
L’électrophorèse capillaire (EC) est une technique analytique séparative moderne qui offre les avantages d’une haute résolution, de temps d’analyse courts et d’une consommation minimale des échantillons et réactifs. Toutefois, il est difficile d'analyser ces échantillons directement par EC sans prétraitement. Par conséquent, la purification des échantillons et l'amélioration de la sensibilité de détection sont primordiales afin de permettre l’utilisation de l’EC pour analyser ces composés. Ainsi, le but de ce travail était de développer et de synthétiser in-situ des monolithes dans des capillaires pour la pré-concentration de protéines et d’ADN en EC. Le couplage en ligne de l'extraction et la séparation d'ADN par EC a été développé en préparant un monolithe aminé à base de silice. Par ailleurs, la polymérisation d'un monolithe fonctionnalisé par des anticorps immobilisés a été mise au point pour une pré-concentration de protéines par immuno-affinité couplée à leur séparation par ECCapillary electrophoresis (CE) is increasingly important for biomolecular analysis with the advantages of high resolution, short separation time, minimal sample and reagent requirement. However, because of the complexity of real biological sample in which matrices (e. G. , salts, lipids) interfere with the injection and assay, it remains difficult to analyze biological sample directly by CE without pretreatment. Moreover, in the case of low concentration levels of analytes in real samples, CE is limited by its detection sensitivity. The in situ prepared monolithic materials, which have the advantages of easy preparation, excellent permeability, were proposed for the preconcentration purpose in CE. In this thesis, an amino silica monolith was developed for efficient DNA extraction and in-line coupling with CE for DNA separation. In addition, the polymerization and application of an affinity polymer monolithic capillary for immunopreconcentration-CE of protein were included in this work
27
Ozcan, Aysenur. "Investigating The Extrusion Of Alumina Silicate Pastes For Synthesis Of Monolith Zeolite A." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606469/index.pdf.
Анотація:
Zeolites are highly porous materials that are most commonly used in granular or beaded forms. In general, zeolite granules, beads or monoliths are manufactured by using an inorganic binder which helps to cement zeolite crystals together. However, this inorganic binder decreases the purity of the zeolite structures and accessibility to the zeolite pores. A new and relatively easy method was offered for the production of binderless zeolite A tubes and bars from amorphous alumina silicate extrudates in this study. Amorphous alumina silicate powder, which is obtained by filtering the homogenous hydrogel with a composition of 2.5Na2O:1Al2O3:1.7SiO2:150H2O, is mixed with an organic binder (HEC-Hydroxyethyl Cellulose) to obtain the paste. The paste is then extruded through a die of a home-made extruder into bars and tubes. These extrudates were dried at room temperature for 24 hours, then calcined at 600oC for 2
hours and finally synthesized at 80oC for 72 hours in hydrothermal conditions to convert amorphous alumina silicate to zeolite.
The most appropriate amorphous alumina silicate powder (A) / 4wt% HEC solution (H) ratio to prepare paste, hence to prepare bars and tubes was found as 0.82. The crystallinity of bars and tubes was 91% and 97%, respectively, and zeolite A was the only crystalline material. The bars and tubes were composed of highly intergrown zeolite A crystals with high porosity. Porosity of the bars is approximately 39% and porosity of the tubes is 29%, with a narrow pore size distribution. Bars have macropores of 2 μ
m, while the macropores of the tubes are 3-4 &
#956
m. The BET surface area of the bars was 411 m2/g and of tubes was 439 m2/g, which are comparable with the commercial zeolite A beads. Bars had a crushing strength of 0.42 MPa, which is sufficiently high to handle. In conclusion, zeolite A bars and tubes, with their high purity, macroporous structure and high mechanical strength, can be used in adsorption and ion exchange processes. The developed synthesis method can be scaled up to prepare honeycomb monoliths that provide higher surface are per unit volume with an appropriate extruder die.
28
Abi, Jaoudé Maguy. "Développement de phases monolithiques à base de dioxyde de titane pour la séparation et l’enrichissement des produits phosphorylés." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10310.
Анотація:
Ce manuscrit est consacré à l’élaboration de phases monolithiques à base de dioxyde de titane pour les techniques séparatives appliquées à l’analyse des produits phosphorylés. La partie bibliographique situe d’abord l’intérêt des monolithes pour le développement des techniques séparatives en portant une attention particulière à la problématique de miniaturisation. L’état de l’art sur l’utilisation du dioxyde de titane, dans les sciences séparatives, est ensuite établi. À ce niveau, les principales caractéristiques physico-chimiques et chromatographiques de ce matériau sont revues pour les lits particulaires. Un descriptif de la synthèse des monolithes de dioxyde de titane par le procédé sol-gel est ensuite détaillé avant d’illustrer la mise en oeuvre de ce type de colonnes dans les techniques séparatives. La partie expérimentale est axée d’abord sur la compréhension du comportement du dioxyde de titane particulaire en chromatographie liquide à interaction hydrophile (HILIC). Le travail expérimental est ensuite orienté vers l’élaboration d’un procédé sol-gel répétable, permettant d’obtenir le matériau sous le format monolithique. Dans un premier temps, le support est élaboré sous forme de barreau, dont l’utilisation potentielle après mise en colonne est illustrée dans le cadre de la purification et de l’enrichissement des acides aminés phosphorylés. Des adaptations de protocole sont apportées pour la synthèse in situ de ces monolithes à l’intérieur des capillaires afin de répondre aux contraintes des techniques séparatives miniaturisées. Ces monolithes sont caractérisés en HILIC, par comparaison avec les phases particulaires. Pour terminer, les propriétés chromatographiques originales de ces phases sont mises à profit pour la séparation et le traitement d’échantillons, contenant des produits phosphorylésThis manuscript is dedicated to the development of monolithic titania phases for chromatographic analysis of phosphorylated compounds. The bibliography section first summarizes the interest of monolithic phases for the development of separation techniques while emphasizing on the problem of miniaturization. The state of the art on the use of titanium dioxide in liquid chromatography techniques is established. In this subject, the physico-chemical and chromatographic behaviour of this material are reviewed for particle beds. Then a detailed description of the sol-gel synthesis of monolithic titania is presented with a final illustration of the potential use of this support in separation techniques. The experimental part concentrates first on the analysis of the chromatographic behaviour of particulate titania in the hydrophilic interaction mode (HILIC). The work is then focused on the development of a repeatable sol-gel process that enables the formation of monolithic titania. The monolithic phase is first synthesized at a large scale, and its potential use, after column cladding, is illustrated with the purification and enrichment of phosphorylated amino acids. The elaboration process is also adapted to meet with the miniaturized separation techniques by performing an in situ synthesis route within capillary columns. These columns are characterized in HILIC by comparison with the chromatographic properties observed for titania particulate beds. The original behaviour of native titania observed also for the synthesized monolithic phases is finally applied to the separation and sample treatment of mixtures of phosphorylated products
29
Malkin, Douglas Scott, and Douglas Scott Malkin. "An Investigation of a Novel Monolithic Chromatography Column, Silica Colloidal Crystal Packed Columns." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/193936.
Анотація:
Many researchers have investigated ways to improve the separation power of conventional chromatography, most notable is the development of ultra-high performance liquid chromatography (UHPLC). However, only slight improvements in separation efficiency have been achieved up to this point, and unfortunately, modern reversed phase liquid chromatography (RPLC) methods do not have high enough resolving power to analyze complex proteomic mixtures.Uniformly sized silica particles from 10 nm to 1 micron are known to self-assemble into a highly ordered face centered cubic crystal. Silica colloidal crystals have shown recent promise in biological applications such as permselective nanoporous membranes, DNA sieving, reversed phase separation of small molecules on planar substrates, protein sieving, microarrays, total internal reflection fluorescence microscopy of live cells, and 3-D scaffolds for supported lipid films. In this work, silica colloidal crystals packed in capillaries are explored for their potential improvement in the efficiency of reversed phase chromatography.The silica colloidal crystal columns were chemically stabilized by with trichlorosilanes. The trichlorosilanes form chemical bonds between the particles and the particles and the substrate creating an increase in mechanical stability, and at the same time, providing an excellent chromatographic monolayer. After stabilization the fritless columns were able to withstand the pressure limit of the commercial UHPLC. Next, the columns were characterized using a small dye molecule, 1,1' - Didodecyl - 3,3,3',3' - tetramethylindocarbocyanine (DiIC12). The dye was run under capillary electrochromatography (CEC), and sub-micron plate heights were achieved. Further, a van Deemter plot of the dye molecule indicates that the plate height is largely due to the molecule's diffusion. This result suggests that the plate heights for proteins would be even smaller, since proteins have diffusion coefficients an order of magnitude smaller. The analysis of proteins by CEC yielded nanometer plate heights. Finally, pressure driven flow separations coupled with nano-electrospray ionization (n-ESI) MS have also been explored. The Poiseuille flow profile has been shown not to perturb the low plate heights. Gradient elution of peptides was also achieved, and the results demonstrate the highest chromatographic peak capacities for short analysis times to date.
30
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.
Анотація:
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
31
Macedo, José A. "Monolithic silicon receiver front-ends for portable radio." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0004/NQ32343.pdf.
32
Danesh, Mina. "Monolithic inductors for silicon radio frequency integrated circuits." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/MQ45607.pdf.
33
Haque, Talha. "Silicon-based Microwave/Millimeter-wave Monolithic Power Amplifiers." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31174.
Анотація:
There has been increased interest in exploring high frequency (mm-wave) spectrum (particularly the 30 and 60 GHz ranges), and utilizing silicon-based technology for reduced-cost monolithic millimeter integrated circuits (MMIC), for applications such as WLAN, inter-vehicle communication (IVC) automotive radar and local multipoint distribution system (LMDS). Although there has been a significant increase in silicon-based implementations recently, this area still has significant need for research and development. For example, one microwave/mm-wave front-end component that has seen little development in silicon is the power amplifier (PA).
Two potential technologies exist for providing a solution for low-cost microwave/mm-wave power amplifiers: 1) Silicon-Germanium (SiGe) HBT and 2) Complementary metal-oxide semiconductor (CMOS). SiGe HBT has become a viable candidate for PA development since it exhibits higher gain and higher breakdown voltage limits compared to CMOS, while remaining compatible with BiCMOS technology. Also, SiGe is potentially lower in cost compared to other compound semiconductor technologies that are currently used in power amplifier design. Hence, this research focuses on design of millimeter-wave power amplifiers in SiGe HBT technology.
The work presented in this thesis will focus on design of different power amplifiers for millimeter-wave operating frequencies. Amplifiers present the fundamental trade-off between linearity and efficiency. Applications at frequencies highlighted above tend to be point-to-point, and hence high linearity is required at the cost of lowered efficiency for these power amplifiers. The designed power amplifiers are fully differential topologies based on finite ground coplanar waveguide (FGC) transmission line technology, and have on-chip matching networks and bias circuits. The selection and design of FGC lines is supported through full-wave EM simulations. Tuned single stub matching networks are realized using FGC technology and utilized for input and output matching networks.
Two 30-GHz range SiGe HBT PA designs were carried out in Atmel SiGe2RF and IBM BiCMOS 8HP IC technologies. The designs were characterized first by simulations. The performance of the Atmel PA design was characterized using microwave/mm-wave on wafer test measurement setup. The IBM 8HP design is awaiting fabrication. The measured results indicated high linearity, targeted output power range, and expected efficiency performance were achieved. This validates the selection of SiGe HBT as the technology of choice of high frequency point-to-point applications. The results show that it is possible to design power amplifiers that can effectively work at millimeter-wave frequencies at lower cost for applications such as mm-wave WLAN and IVC where linearity is important and required transmitted power is much lower than in cellular handset power amplifiers. Moreover, recommendations are made for future research steps to improve upon the presented designs.Master of Science
34
Schaub, Jeremy Daniel. "Photodetectors and monolithic optical receivers in silicon technologies /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
35
Bernardin, Evans K. "Demonstration of Monolithic-Silicon Carbide (SiC) Neural Devices." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7474.
Анотація:
Brain Machine Interfaces (BMI) provide a communication pathway between the electrical conducting units of the brain (neurons) and external devices. BMI technology may provide improved neurological and physiological functions to patients suffering from disabilities due to damaged nervous systems. Unfortunately, microelectrodes used in Intracortical Neural Interfaces (INI), a subset of the BMI device family, have yet to demonstrate long-term in vivo performance due to material, mechanical and electrical failures. Many state-of-the-art INI devices are constructed using stacks of multiple materials, such as silicon (Si), titanium (Ti), platinum (Pt), parylene C, and polyimide. Not only must each material tolerate the biological environment without exacerbating the inflammatory response, each of the materials used must physically withstand the environment as well as interact well with each other.
One approach to address abiotic mechanisms has been optimizing the materials required to fabricate the INI devices. Silicon Carbide (SiC) is a physically robust, hemo and biocompatible, and chemically inert semiconductor. An ‘all-SiC’, or monolithic SiC, device may be the disruptive technology needed in the BMI field to finally achieve long-term and wide-spread use of this technology in humans. The all-SiC device concept is where SiC serves as all device layers: the base (substrate), the conducting traces (electrodes), and the surface conformal insulating layer. The monolithic SiC neural probe is realized by forming high-quality pn junctions of heavily doped SiC on a layer of the opposite polarity. Heavily doped semiconductors display semi-metallic electrical performance, which allow for efficient electrical conduction in the electrode without the deleterious effects of metal ions interacting with the neural environment. The conformal insulator is realized using amorphous-SiC (a-SiC) which can be patterned to open windows to allow electrical conduction to occur between the electrode tips and the brain.
Several generations of monolithic SiC devices have been fabricated, tested and are reported in this dissertation. The devices were fabricated utilizing two polytypes of SiC (4H-SiC and 3C-SiC). The monolithic SiC microelectrodes were fabricated utilizing techniques used in the fabrication of Si based microelectrodes. Monolithic SiC devices fabricated include planar single-ended MEAs (with varying lengths and varying active recording area), 60-channel MEAs for in-vitro studies, and 16-electrode Michigan style neural probes for in-vivo studies. Electrical testing of the pn junction demonstrated that the 4H-SiC device can block a forward bias voltage of up to 2.3V and displays reverse bias leakage below 1 nArms well past -20V. Current leakage between adjacent electrodes was ~7.5 nArms over a voltage range of -50V to +50V. Furthermore, electrochemical results show that the 4H-SiC microelectrodes interact with an electrochemical environment primarily through capacitive mechanisms and has an impedance comparable to gold electrodes. Electrode impedance ranged from 675±130 kΩ (GSA = 496 µm2) to 46.5±4.80 kΩ (GSA = 500K µm2). However, the 4H-SiC devices cannot deliver charge as efficiently as other conventionally used microelectrode materials, such as iridium oxide (IrOx), but a larger water window compensates for this since larger stimulation voltages are supported compared to IrOx.
All studies and data collected thus far indicate that the monolithic SiC neural device can aid in the advancement of chronic INI use in clinical settings. The all-SiC devices rely on the integration of only robust and highly compatible SiC material, they may offer a promising solution to probe delamination and biological rejection associated with the use of multiple materials used in many current INI devices. Follow-on work is planned to prove this assertion via in vivo studies.
36
McNaughton, Adam L. "High Temperature Compression Testing of Monolithic Silicon Carbide (SiC)." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/McNaughtonAL2007.pdf.
37
Mirabelli, Alessandro James. "Highly efficient monolithic Perovskite/Silicon bifacial tandem solar cells." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20369/.
Анотація:
Perovskite solar cells have been the focus of photovoltaics research in this past decade. Owing to their many favorable properties - like low cost solution processability, tunable bandgap and high efficiency, they have seen much attention in various types of solar cell designs. A promising technology has coupled perovskite cells with another semiconductor material in monolithic tandem solar cells, reaching record efficiencies of 29.15%. However, these kinds of devices require current matching condition to maximize the output of solar cells, making their fabrication challenging. Here, we propose the innovative bifacial tandem configuration to overcome current matching limits between the two sub-cells, by collecting photons from the surrounding environment, i.e. albedo. The extra light shining on our silicon bottom cell boosts the photogenerated current above monolithic tandem values. We show that the current density gain is more pronounced in perovskite solar cells with a narrow bandgap, 1.59 eV, than those with a wider one 1.7 eV. In other words, current matched tandems show little to no increase in efficiency with the extra albedo, while mismatched cells exhibit the most power, reaching up to ~28% in the best scenario. To give more credit to our work, we report outdoor data gathered in various locations around the world, and we show how different albedos have distinct effects on bifacial tandems.
38
Kohns, Richard [Verfasser], and Ulrich [Akademischer Betreuer] Tallarek. "Understanding sol–gel processing: Hierarchical silica monoliths towards applications in chemical reaction engineering / Richard Kohns ; Betreuer: Ulrich Tallarek." Marburg : Philipps-Universität Marburg, 2021. http://d-nb.info/1227580118/34.
39
McGiveron, James Kevin. "Aspects of sol-gel chemistry : the adsorption properties of silica sol-gel monoliths and the preparation of indium(III) oxide and indium(III)/tin(IV) oxide thin films by the inorganic sol-gel process." Thesis, Brunel University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294504.
40
Weller, Harald. "CMOS monolithic pyroelectric infrared focal plane arrays using PVDF thin films." Thesis, Edinburgh Napier University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323080.
41
Dávila, Pineda Diana. "Monolithic integration of VLS silicon nanowires into planar thermoelectric microgenerators." Doctoral thesis, Universitat Autònoma de Barcelona, 2011. http://hdl.handle.net/10803/83966.
Анотація:
La creciente demanda de energía portátil requerida por sistemas miniaturizados está impulsando el desarrollo de nuevas tecnologías y materiales para lograr una eficiente generación de energía a una microescala. Los microgeneradores termoeléctricos ofrecen una oportunidad para recolectar el calor residual de dispositivos electrónicos y convertirlo en energía, eliminando a la vez dicho calor. La baja eficiencia de conversión termoeléctrica de los materiales semiconductores utilizados actualmente en microelectrónica ha limitado su aplicación para fines de aprovechamiento energético. Sin embargo, recientemente se ha constatado una mejora de varios órdenes de magnitud en las propiedades termoeléctricas del silicio cuando se presenta en forma de nanohilos, abriéndose de esta manera la oportunidad para la integración de generadores termoeléctricos en microtecnología de silicio.
En esta tesis se han integrado monolíticamente matrices densas y ordenadas de nanohilos de silicio (Si NWs) en un dispositivo micromecanizado también en silicio. La técnica VLS-CVD ha sido utilizada para el crecimiento lateral controlado de los nanohilos. La microestructura ha sido apropiadamente diseñada para adaptar el crecimiento tridimensional de las matrices de nanohilos de silicio en una arquitectura plana y para asegurar el acceso eléctrico a los nanohilos. Adicionalmente, el dispositivo permite el establecimiento de un gradiente de temperatura interno plano cuando se pone en contacto con una fuente de calor, lo que da lugar a un microgenerador termoeléctrico completo en el que los nanohilos de silicio actúan como el material termoeléctrico nanoestructurado.
Esta tesis tiene por objeto presentar los primeros desarrollos de integración de materiales termoeléctricos, técnicas de caracterización y tecnologías de fabricación realizados en el IMB-CNM (CSIC), sentando las bases para el desarrollo de futuras generaciones de microgeneradores termoeléctricos.
Esta tesis se compone de cuatro capítulos. En el primer capítulo se presenta una breve introducción al mundo de la termoelectricidad, revisando el estado del arte de materiales y dispositivos termoeléctricos. El segundo capítulo está enfocado en las técnicas experimentales y tecnológicas empleadas a lo largo del estudio. El capítulo tres describe el proceso seguido para el diseño, simulación y fabricación de un microgenerador termoeléctrico plano basado en una sola matriz de nanohilos de silicio. Finalmente, el capítulo cuatro estudia el aumento en el rendimiento de los microgeneradoes termoeléctricos mediante matrices de nanohilos de silicio conectadas transversalmente, adaptando y explotando aún más el crecimiento lateral 3D de nanohilos de silicio VLS.The increasing demand for portable power required by miniaturized systems is driving the development of new technologies and materials to achieve efficient energy generation at the microscale. Apart from removing heat from electronic devices, thermoelectric microgenerators offer an attractive opportunity to harvest waste heat converting it into power. The low thermoelectric conversion efficiency of current bulk microelectronics semiconductor materials has limited their implementation for energy harvesting purposes. However, recent studies have proven, at single nanowire level, that nanostructuring of silicon into nanowires greatly enhances the thermoelectric properties of this material, opening up the opportunity for the integration of thermoelectric generators into silicon microtechnology. In this thesis, dense and well-ordered arrays of silicon nanowires (Si NWs) have been monolithically integrated into a silicon micromachined device. The VLS-CVD technique has been used for the controlled lateral growth of nanowires. The microstructure has been appropriately designed to adapt the tridimensional growth of the Si NWs arrays to a planar architecture, and to assure electrical accessibility to the nanowires. Additionally, the device allows an internal in-plane temperature gradient to be established when placed in contact with a heat source, giving rise to a complete thermoelectric microgenerator in which the Si NWs act as the nanostructured thermoelectric material. This thesis is intended to bring new background in thermoelectric materials integration, characterization techniques and fabrication technologies to the IMB-CNM (CSIC), paving the way for the development of future generations of thermoelectric microgenerators. The work presented in this thesis is divided into four chapters. The first chapter introduces thermoelectricity and its underlying physics, reviewing the state-of-the-art of thermoelectric materials and devices. The second chapter focuses on the experimental and technological tools employed along this study. The third chapter describes the process followed for the design, simulation and fabrication of the building block of the proposed planar thermoelectric microgenerators based on a single Si NWs array. Finally, chapter four studies the enhanced performance of thermoelectric microgenerator structures by means of transversally linked Si NWs arrays, further adapting and exploiting the 3D lateral growth of VLS Si NWs.
42
Comeau, Jonathan P. "Integration Issues Associated with Monolithic Silicon-Germanium Microwave Radar Systems." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/13990.
Анотація:
Active electronically scanned array (AESA) radar systems for military and commercial applications have fueled interest in low-cost, high-performance technologies capable of delivering integrated circuits for transmit-receive (T/R) modules and monolithic radar systems. Silicon-Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) technology has been flagged as a strong candidate for such applications because of its high-speed low-noise devices, high integration capabilities, and relatively low cost.
This work investigates integration issues associated with monolithic silicon-germanium radar systems for military (8-12 GHz) and automotive (24 GHz) applications. The design and implementation of critical circuits, such as phase shifters, power amplifiers, up-conversion mixers, down-conversion mixers, and voltage-controlled oscillators will be investigated, along with the system level considerations associated with these components. These building blocks have been fabricated and tested at wafer level, utilizing commercially available SiGe HBT BiCMOS technologies, demonstrating acceptable performance for these applications. Preliminary research into substrate coupling associated with these BiCMOS technologies will also be presented, demonstrating the potential for circuit-to-circuit substrate coupling to occur at these microwave frequencies.
43
Hu, Chen. "Surface Optimization of the Silicon Templates for Monolithic Photonics Integration." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37226.
Анотація:
Silicon photonics is emerging as a potential field to achieve optical interconnects towards the realization of ultra high bandwidth. The indirect band-gap property of silicon still remains as a big challenge to incorporate silicon photonic active device, for example, silicon-based laser. In the Laboratory of Semiconductor Materials at KTH, a monolithic integration platform based on nano-epitaxial lateral overgrowth (nano-ELOG) technique has been proposed to integrate III-V semiconductor materials with silicon for light source application. The integration process involves uneven surface morphology at different stages. The surfaces of the indium phosphide seed layer on silicon used for ELOG, the mask deposited on it (the silicon/silicon dioxide waveguide) and the ELOG indium phosphide layer grown on it prior to laser growth are often rough. In this thesis work, we have optimized chemical mechanical polishing (CMP) technique in order to achieve an even surface. The same procedure is also necessary to reach the optimal thickness of different layers to enable effective coupling of light from the laser source into the waveguide. CMP of indium phosphide to obtain an average surface roughness of < 1 nm has been optimized by a two-step polishing using different slurries; it results in a step height of ca 3 nm. Similarly the surface of silicon/silicon dioxide “waveguide” has also been optimized with the roughness of ~ 0.5 nm. In the latter case, a step height of 40 nm is retained and this increase with respect to InP is identified to be mainly due to limitations of the polishing machine which is different from that used for indium phosphide. The reduction in step heights with polishing time is analyzed and compared with an existing theoretical model. Our results are in good qualitative agreement with the model. The optimized surface morphology obtained in this work was tested for its suitability for integration. For this evaluation, InP was grown by ELOG in a hydride vapour phase epitaxy reactor with and without CMP of the involved surfaces. The surface after CMP yields layers of better surface morphology with fewer defects as revealed by atomic force microscopy, surface profilometer and cathodoluminescence analysis. The results indicate that the CMP process is useful for monolithic integration for silicon photonics.
44
Huang, Kevin T. Y. "Expandable monolithic silicon network for cost-effective large-area electronics /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
45
Hudson, Melanie. "Studies of the formation of homogeneous mixed silicon-titanium/zirconium oxides by the sol-gel route." Thesis, Brunel University, 1994. http://bura.brunel.ac.uk/handle/2438/5371.
Анотація:
This thesis is concerned with the preparation of mixed silicon-titanium oxides (Ti02=4.1-21.9wt%) and silicon-zirconium oxides (Zr02=4.1-22.Iwt%) by the sol-gel route. Methods of preparing homogeneous Si02-TiO2 gels and SiO2-Zr02 gels have been explored. In this work bis(acetylacetonato)titanium diisopropoxide or bis(acetylacetonato)zirconium dipropoxide and tetraethyl orthosilicate (TEOS) have been hydrolysed simultaneously in iso-propanol to form homogeneous gels. Using these systems, the effects of the reaction conditions, amount of titania/zirconia present in the gel, drying conditions and thermal treatment of the dry gels on the bulk and structural properties have been investigated by a variety of experimental methods including X-ray diffraction, mid- and near-infrared spectroscopy and gas adsorption techniques. For SiO2-TiO2 powders and monoliths, and SiO2-ZrO3 monoliths, thermal treatment has been found to significantly reduce the surface area (from 750-1.0m2g-1), pore volume (from 0.56-0.001cm3g-1') and relative number of silanol groups on the surface of the sample above 700°C. Average pore diameters remain constant at temperatures below 900°C (ca 54-21Å for monoliths), although the micropore volume does decrease (0.04-0.0cm3g-1) suggesting that smaller pores are destroyed by the heating process. For SiO2-TiO2 powders, the average pore diameter was ca IOÅ larger than for the corresponding monolith suggesting that small pores are destroyed during powdering. At 1100°C, gas adsorption data indicate that the samples are fully densified. This is supported by NIR spectra which detect no silanol groups on the surface of the sample. Structural changes arising from compositional changes and differing thermal treatment regimes have been monitored using mid-infrared spectroscopy and X-ray diffraction. With increasing temperature the silica matrix strengthens and titanium/zirconium are incorporated into the matrix. Monolithic SiO2-TiO2 gels (Ti02=6.34 weight%) remained amorphous at 1100°C, whereas powders began to exhibit diffraction patterns predominantly from anatase at 700°C. Anatase crystallite sizes have been calculated using the Scherrer equation and have been found to be between 16.3 and 5.4nm. Monolithic SiO2-ZrO2 gels containing 4.1 and 4.9 weight% zirconia were found to be amorphous after treatment at 1100°C. Increasing the zirconia content to 6.4 and 22.1 weight% resulted in gels that were amorphous up to 900°C. Further treatment at 1100°C, resulted in tetragonal zirconia and some cristobalite being formed. Crystallite sizes have been calculated as being between 2.7 and 1.6nm for tetragonal zirconia and from 4.1 to 2.8nm for cristobalite. Increasing the levels of titania/zirconia in the sample resulted in higher relative levels of hydrogen-bonded silanol groups. On hydration, the increased levels of titania/zirconia resulted in no observable free silanol groups on the surface suggesting that the surface becomes more hydrophilic as the amount of titania/zirconia present in the sample increases. This suggests that water becomes more tightly bound to Ti-OH /Zr-OH groups on the surface and within the pores, resulting in fewer free silanol type groups. A double alkoxide bis(acetylacetonato)titanium di(triethoxysilane) [Ti(acac)2(OSi(OC2H5)3)2] has also been synthesised and characterised. Mixed Si02-TiO2 gels have also been prepared by the simultaneous hydrolysis of Ti(acac)2(OSi(OC2H5)3)2 and TEOS under acidic conditions in ethanol. The effects of reaction conditions and thermal treatment of the dry gels have been investigated. Increasing the treatment temperature of the samples resulted in the progressive decrease in surface area (533-3.0m2g-1), pore volume (0.18-0.003cm3g-1), micropore volume (0.06-0.00cm3g-1) and relative number of silanol groups on the surface. However, the average pore diameter remained constant at temperatures up to 700°C. Changes in pore volume (0.07-0.005cm3g-1), surface area (300-3.0m2g-1) and average pore diameter (26.9-91.9Å) were largest at 900°C, and the samples were found to be almost completely dense. This was confirmed by the absence of observable silanol groups by NIR spectroscopy. After heating at temperatures up to 900°C, the samples were found to be amorphous by XRD. However increasing the temperature to 1100°C resulted in the formation of some crystalline anatase. The anatase crystal sizes have been calculated as being from 16.3 to 10.8nm in diameter. NIR studies of silica-zirconia and silica-titania gels (prepared by both methods), indicate that decreasing the amount of acid used in the hydrolysis reaction resulted in higher relative levels of hydrogen bonded silanol species. Similarly, decreasing the amount of acid increased the micropore volume and decreased the mesoporosity of the resulting samples. Generally, decreasing the amount of acid used for the hydrolysis for silica-zirconia and silica-titania gels (prepared by both methods), results in a decrease in the overall surface area and pore volume of the resulting material. The resulting isotherms indicate that the samples became less mesoporous as the amount of acid used in the hydrolysis reaction decreased. This was accompanied by an increase in the micropore volume. For SiO2-TiO2 monoliths prepared from a double alkoxide and Si02-ZrO2 monoliths the resulting pore structure is more rigid and composed of smaller pores than that of SiO2-TiO2 powders and monoliths prepared from bis(acetylacetonato)titanium diisopropoxide.
46
Su, Yinmei [Verfasser]. "Multi-functional Monolithic ICs for 94GHz Transmitters on Silicon / Yinmei Su." Ulm : Universität Ulm. Fakultät für Ingenieurwissenschaften und Informatik, 2015. http://d-nb.info/1065309724/34.
47
Ting, Steve M. (Steve Ming) 1973. "Monolithic integration of III-V semiconductor materials and devices with silicon." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9537.
48
Cai, Yan Ph D. Massachusetts Institute of Technology. "Materials science and design for germanium monolithic light source on silicon." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92958.
Анотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, September 2014.This 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. "September 2014."
Includes bibliographical references (pages 190-197).
Germanium (Ge) is an optically active material with the advantages of Si-CMOS compatibility and monolithic integration. It has great potential to be used as the light emitter for Si photonics. Tensile strain and n-type doping are two key properties in Ge to achieve optical gain. This thesis mainly focuses on: (1) physical understandings of the threshold behavior of Ge-on-Si bulk laser and the temperature dependent performance; (2) process developments to grow and planarize the epitaxial Ge on Si in oxide trenches and corners; (3) introduction of n-type dopant into Ge-on-Si thin films while studying the threading dislocation behavior in n-Ge during annealing; (4) Design an external cavity Ge laser integrated with Si waveguides for a low threshold current and single mode operation. Heavy n-type doping was observed to change the Ge electronic band structure by band gap narrowing effect. We also found a failure of using a simple Drude model to explain free carrier absorption in n-Ge. We modified the optical gain simulation based on the above two observations in Ge. We found a broad gain bandwidth of ~ 200 nm from 1550 nm to 1750 nm and a higher net materials gain. We predicted a theoretical lasing threshold current density of 5~10 kA/cm² in the bulk Ge laser device with the n-type doping of mid-10¹⁹ cm-³ at room temperature. We also predicted the Ge laser device would have better temperature stability regarding the threshold current compared to the III-V laser. Single crystalline Ge was epitaxial grown on Si in oxide trenches using ultra high vacuum chemical vapor deposition. The selective growth lead to the faceting in Ge because of the different growth rates of crystal orientations. We developed a suitable photolithography and oxide etch process to get the vertical oxide sidewall for Ge trench filling. We also tested the Ge growth in the T-shape corners to improve the reflectivity at the waveguide end. The T-shape structure was also useful for the Ge/Si waveguide coupling in the external cavity laser. Furthermore, we developed a chemical mechanical polishing (CMP) process for the over-grown Ge waveguides. The Ge CMP process was selective to oxide, flexible to change in the CMP rate by DI water dilution and controllable for a minimum dishing of Ge in the oxide trenches. N-type doping helped to increase the direct band transition in Ge for light emission. We developed a delta-doping method to grow a dopant source called "delta doping layer" on the single crystalline Ge layer without introducing extra defects. We then used rapid thermal annealing to drive the dopant into the underlying Ge layer. The dopant enhanced diffusion was discovered to speed up the drive-in process. The active n-type concentration in Ge could reach up to 5×10¹⁹ cm-3 using the delta doping source and annealing process. Since the dopant source layer had a disrupted Ge growth, we used the developed CMP process to remove it after the dopant drive-in. A comprehensive dopant diffusion simulation was developed to predict the annealing temperature and time to achieve high n-type doping and uniform distribution. We used plan-view transmission electron microscopy to examine the threading dislocation density (TDD) in n-Ge for both blanket films and trench grown waveguides. We found a high TDD of ~ 1×10⁸cm-² in 1 [mu]m thick blanket Ge with doping of 3×10¹⁸ cm-³ after high temperature annealing at 850 °C for 40 min. The TDD is 1×10⁹ cm-² in the 300 nm thick and 1 [mu]m wide Ge waveguide. We examined the effects of annealing temperature, Ge thickness, Si/Ge inter-diffusion and trench width on the threading dislocation behavior. However, we have not found the exact reason causing the high TDD and therefore, further study is required on the TDD reduction for the Ge waveguide. Finally, we designed an external cavity Ge laser using distributed Bragg reflector (DBR) gratings on Si waveguides. A detailed discussion on the cross section design was presented to mitigate the internal optical loss from claddings and metal layers and to improve the current injection uniformity across the Ge waveguide. The aim of the DBR grating design was to achieve a single mode operation by controlling the full width half maximum of the grating reflectance spectrum. We also discussed the coupling between Ge and Si waveguides and different designs were presented to increase the coupling efficiency.
by Yan Cai.
Ph. D.
49
Lei, Yi-Shu Vivian 1979. "Post assembly process development for Monolithic OptoPill integration on silicon CMOS." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28548.
Анотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (leaves 108-110).
Monolithic OptoPill integration by means of recess mounting is a heterogeneous technique employed to integrate III-V photonic devices on silicon CMOS circuits. The goal is to create an effective fabrication process that enables the volume production of high performance optoelectronic integrated circuits (OEICs). This thesis focuses on the development of post-assembly processes and technologies, in which InGaAs/InP P-i-N photodiodes were integrated as long wavelength photodetectors with an optical clock receiver circuit. Fabrication procedures, challenges experienced, and results accomplished are presented for each process step including the formation of alloyed and non-alloyed ohmic contacts on n-type and p-type InGaAs contact layers, active area definition by dry-etching InGaAs/InP with ECR-enhanced RIE, BCB passivation and planarization, via opening by dry-etching BCB with RIE, and top contact metallization. In conjunction, an InP-based test heterostructure was fabricated into discrete photodiodes. Decoupling the fabrication and benchmarking of III-V photonic device from the Si-CMOS electronic circuit allowed for the independent electrical and optical characterization of the photodetectors. Measurements and analysis of the P-i-N photodiodes will assist the forthcoming analysis of the final OEIC. Preliminary results and discussions of the calibration sample are presented in this thesis.
by Yi-Shu Vivian Lei.
S.M.
50
Wang, Jianfei Ph D. Massachusetts Institute of Technology. "Resonant-cavity-enhanced multispectral infrared photodetectors for monolithic integration on silicon." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62682.
Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 162-172).
Multispectral infrared (IR) detection has been widely employed for numerous applications including hyperspectral imaging, IR spectroscopy, and target identification. Traditional multispectral detection technology is based on the combination of broadband focal plane arrays (FPA) and spectral filters, grating spectrometers, or Fourier transform spectrometers, which requires bulky, high-cost mechanical scanning instruments and have a slow response. Hybrid structures integrating FPA and silicon readout integrated circuits (Si ROIC) greatly limit the yield and result in extremely expensive devices. Single photodetectors capable of detecting multiple wavebands simultaneously and monolithic integration with Si ROIC, however, enable dramatically simplified system design with superior mechanical robustness, and thus attract a lot of interest around the world today. In this thesis, we focus on the development of novel IR sensitive material and resonant-cavity- enhanced (RCE) photodetector devices that address the emerging need in the field of IR radiation detection. Polycrystalline PbTe films have been identified as the IR absorbing layers due to their high photosensitivity and fabrication flexibility; on the device side, we have established a universal design theory for multispectral detection and demonstrated fully functional mid-IR RCE photodetectors capable of monolithic integration with Si ROIC. We have developed room-temperature-sensitized, polycrystalline PbTe films using single source thermal evaporation for detecting IR light up to 5 pm in wavelength. Thinner PbTe layers yields enhanced performance than thicker layers due to strong thickness dependence of both photo-responsivity and detectivity. Structural, electrical, and optical property studies reveal photoconductivity mechanism in the films and point out directions of further material optimization. We have established a versatile and scalable design theory for cavity-enhanced multispectral photodetectors using phase-tuned propagation. Critical coupling condition is identified as the prerequisite to achieve near unity quantum efficiency in RCE photodetectors. Coupling-matching layers are positioned between cascaded planar resonant cavities for controlling optical phase and coupling strength between incident light and resonant modes to obtain critical coupling condition. After developing another two IR transparent layers as low and high index materials, evaporated As2S3 and sputtered Ge, we design and fabricate distributed Bragg reflectors (DBR) for mid-IR resonant cavities. In our design example of dual waveband RCE photodetectors, peak quantum efficiencies over 80% have been realized in both wavebands (1.55 pm and 3.6 pm) with only 50 nm and 100 nm thick PbTe IR absorbers, and spectral cross talk as low as 0.1% is obtained. Preliminary results on our first attempt of fabricated dual waveband RCE photodetectors demonstrate the two resonant cavity modes at 1.61 pm and 3.70 pm. And quantum efficiencies as high as 92% and 68% have been achieved in two wavebands respectively. We have developed and optimized a multi-step lift-off patterning technique to fabricate RCE photodetectors on a Si platform. Single waveband RCE photodetectors for mid-IR (3.5 pm) have been designed according to critical coupling condition to achieve near unity quantum efficiency. The fabricated devices show high quantum efficiency (90%) and peak responsivity at the resonant wavelength of 3.5 pm, which is 13.4 times higher than blanket PbTe film of the same thickness. We demonstrate detectivity as high as 0.72x0 cmHzmW~l, comparable with commercial polycrystalline mid-IR photodetectors. As low temperature processing (150 'C) is accomplished in the entire fabrication process, this demonstration paves the way for monolithic integration of RCE photodetectors with Si ROIC. Lastly, for the first time, we fabricate and test integrated devices of single waveband (3.6 pm) RCE photodetectors and Si ROIC. Both hybrid and monolithic integration structures are investigated. We have developed the fabrication process to accommodate Si ROIC chips of only 3 mm x 5 mm in area, and successfully integrated RCE photodetectors on Si ROIC directly. Our preliminary results show high promise for monolithic integration of RCE photodetectors and Si ROIC in the future.
by Jianfei Wang.
Ph.D.