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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Neue Methodenentwicklung in der Flüssigchromatografie durch Anwendung der Hochtemperaturtechnik mit subkritischen wässrigen mobilen Phasen konstruktive Aspekte eines speziellen Heizsystems /

Teutenberg, Thorsten. January 2004 (has links) (PDF)
Bochum, Universiẗat, Diss., 2004.
2

Neue Methodenentwicklung in der Flüssigchromatografie durch Anwendung der Hochtemperaturtechnik mit subkritischen wässrigen mobilen Phasen konstruktive Aspekte eines speziellen Heizsystems /

Teutenberg, Thorsten. January 2004 (has links) (PDF)
Bochum, Univ., Diss., 2004. / Computerdatei im Fernzugriff.
3

Superheated water as a mobile phase

Burgess, Robert John January 1999 (has links)
This project has focused on the applicability of using superheated water as an alternative eluent for use in reversed phase high performance liquid chromatography (RP-HPLC). A system based on instrumentation from gas chromatography (GC), HPLC, and supercritical fluid chromatography (SFC) was utilised with some success. Of particular importance was the stability of the column stationary phases commonly employed in RP-HPLC. The most popular phases based on alkyl bonded silica proved unsuitable due to excessive dissolution of the base silica at high temperatures. Nevertheless, two other phases—one a poly(styrene-divinylbenzene) material and the other a porous graphitic carbon—proved stable to temperatures as high as 240°C. At such temperatures compound stability was good, except for a notable case with nitrobenzene. The mechanism of elution remained reversed phase mode throughout, with polar solutes being eluted before non-polar ones.
4

Solvent adsorption in SFC : Adsorption of methanol under supercritical conditions / Lösningsmedelsadsorption i SFC

Edström, Emelie January 2015 (has links)
Chromatography is a widely used separation technique including many different modes, for example supercritical fluid chromatography (SFC) which uses a supercritical fluid as mobile phase. A supercritical fluid is achieved when a substance is subjected to a temperature and pressure above the critical point and the boundary between the liquid phase and gas phase is erased. The interest for SFC has increased in recent years, mainly for separation of chiral molecules in the pharmaceutical industry. What makes SFC interesting is that it is a quick, cost-efficient and green method. This is in part due to less organic solvent used in the mobile phase in SFC compared with liquid chromatography and that the carbon dioxide that represents the major part of the mobile phase is a by-product from other processes. In SFC modifiers, often small alcohols, are added to carbon dioxide based mobile phase in order to increase the solubility of polar compounds. In this study the adsorption of methanol to two different stationary phases; Kromasil-Diol and chiral Lux Cellulose-4 were studied. Adsorption is a phenomenon where surface interactions crate a higher density of molecules at the surface than in the bulk. The aim of this work has been to study the adsorption of modifier (methanol) to the stationary phase both to determine the extent of adsorption and the kinetics for system equilibration. These findings were then put into perspective of normal use of SFC for separation of molecules. There are a number of techniques for measuring adsorption; in this study the tracer pulse method is used. This is a pulse method where a concentration plateau is created and an isotope labelled molecule is injected. This was performed in the mobile phase composition from pure carbon dioxide to pure methanol. In addition to the tracer pulse experiments the isotope effect, the eluent flow, equilibration times for the column and retention times for a set of analytes were measured. For the Diol column no large isotope effect was observed, the method was also proved to be highly reproducible since several runs gave consistent results. Calculations based on the experimental data showed that a 6.3 Å thick layer was built up at a methanol fraction of 13% (v/v), corresponding to a monolayer. Changes of the methanol fraction below the saturation level has has greater effect on the retention factor for the analytes than at higher methanol fractions, when the monolayer was saturated. The conclusion of this is that SFC is more stable in the area where the layer has been built up. A preliminary study has been made for the chiral Lux Cellulose-4 column which was not as conclusive as for the Kromasil-Diol column. This type of column needs further studies to confirm the deviating observations and to investigate the cause for these.
5

Modélisation stock-flux de l'économie tunisienne : analyse des chocs de la crise économique et de la révolution / SFC Modeling of the Tunisian economy : analysis of the impact of the economic crisis and revolution

Marouane, Amine 18 December 2013 (has links)
L’objet de cette thèse est de modéliser l’économie tunisienne dans le cadre d’une approche post keynésienne stock-flux cohérente en économie ouverte afin de fournir une analyse des faits stylisés observés depuis 2001. Ce type de modélisation macro économique post keynésienne se distingue par le fait qu’il tient compte non seulement de la dimension flux mais également de la dimension stock de l’économie tunisienne. Il constitue en fait un nouveau cadre d’analyse des effets de de la crise financière et économique mondiale de 2007-2008 et des conséquences économiques issues de la récente révolution tunisienne de 2011. Notre modèle se compose de six secteurs : les entreprises, les ménages, les banques, la banque centrale, l’Etat et enfin le reste du monde. Ce dernier représente l’Union Européenne étant donnée la forte dépendance de l’économie tunisienne vis-à-vis de l’économie des pays européens. Nous avons essayé alors d’expliquer l’évolution du PIB tunisien à travers quatre types de chocs à savoir : les variations du taux de croissance de l’Europe et ce, pour prendre en compte l’impact de la crise économique mondiale, les modifications du taux d’intérêt et du taux de change issues des changements dans la politique monétaire tunisienne ainsi que la réaction de la politique budgétaire et enfin le choc de confiance et de productivité pour évaluer l’impact de la crise économique lors de la révolution tunisienne de 2011. Ces quatre chocs nous ont permis de reproduire les faits stylisés de l’économie tunisienne et de comprendre les effets des crises de la dernière décennie. Puis, nous avons envisagé trois scénarios pour l’économie tunisienne, un premier scénario optimiste, un second pessimiste et un troisième scénario intermédiaire. / The purpose of this thesis is to model the Tunisian economy in a post Keynesian stock-flow consistent approach in order to provide an analysis of the observed stylized facts since 2001. This kind of post Keynesian macroeconomic model retains not only the stock dimension but also the flow dimension of the Tunisian economy. Thus it is a new framework for analyzing the effects of the financial and economic crisis of 2007-2008 and economic consequences resulting from the recent Tunisian revolution of 2011. Six sectors make our economy: households, firms, banks, central bank, government and the rest of the world. The rest of the world represents the European Union given the strong dependence of the Tunisian economy on European economies. In order to explain the trend of the Tunisian GDP, four shocks are considered namely the impact on the growth rate in European Union to take into account the global crisis, the changes in interest rate and exchange rate to explain the impact of monetary policy and the response of fiscal policy and finally the shock in the state of confidence and productivity to understand the effects of the economic crisis during the Tunisian revolution. These four shocks have allowed us to reproduce the stylized facts of the Tunisian economy and understand the effects of the crisis of the last decade. Then we consider three scenarios for the Tunisian economy: an optimistic scenario, a pessimistic scenario and intermediate scenario.
6

Frekvensomriktare i hydraulhissdrift

Leek, Thomas, Nilsson, Peter January 2006 (has links)
Hydroware Elevation Technology AB sells control and regulation equipment for hydraulic elevators. The company now wants to investigate the possibility of changing their present softstarters to frequency inverters to supply power to their pump engines. They also want to investigate the possibility of future use in so called ”intelligent” houses. The purpose of this report is to investigate these possibilities.
7

Frekvensomriktare i hydraulhissdrift

Leek, Thomas, Nilsson, Peter January 2006 (has links)
<p>Hydroware Elevation Technology AB sells control and regulation equipment for hydraulic elevators. The company now wants to investigate the possibility of changing their present softstarters to frequency inverters to supply power to their pump engines. They also want to investigate the possibility of future use in so called ”intelligent” houses.</p><p>The purpose of this report is to investigate these possibilities.</p>
8

Chemische Synthese in überkritischem Ammoniak

Mesri, Fatima Zohra. Unknown Date (has links)
Techn. Universiẗat, Diss., 2007--Darmstadt.
9

Stratégies chromatographiques en phase liquide et supercritique pour l'analyse de candidats médicaments / Liquid and supercritical chromatographic strategies for analysis of drug candidates

Lemasson, Elise 18 January 2018 (has links)
Le profilage d’impuretés de candidats médicaments est une préoccupation majeure des industries pharmaceutiques. L’identification et la quantification des impuretés doivent être strictement contrôlées pour assurer l’efficacité et la toxicité limitée du principe actif. Il est donc nécessaire de disposer de méthodes analytiques performantes afin de s’assurer que l’ensemble des impuretés est identifié. L’HPLC phase inverse sur phase C18 reste aujourd’hui la méthode de choix pour cette tâche. Cependant, il arrive que cette méthode échoue, notamment lorsque le principe actif n’est pas suffisamment retenu sur la colonne ou que les impuretés ne sont pas parfaitement séparées du composé principal. Il est alors essentiel de pouvoir se tourner vers des méthodes analytiques alternatives et complémentaires.Ce travail de recherche traite du développement et de l’évaluation de méthodes analytiques alternatives à l’HPLC phase inverse sur phase C18 pour le profilage d’impuretés de principes actifs pharmaceutiques. L’HPLC phase inverse sur d’autres phases stationnaires, l’HPLC mixed-mode ainsi que la SFC ont été explorées et leurs performances chromatographiques comparées. La comparaison et l’étude des différentes méthodes ont permis de proposer une stratégie d’analyse du candidat médicament. / Impurity profiling of drug candidates is a significant concern of pharmaceutical industries. The identification and quantification of impurities must be strictly controlled to ensure the efficacy and limited toxicity of the active ingredient. It is therefore necessary to have efficient analytical methods to ensure that all impurities are identified. Today, reversed-phase HPLC with C18 column remains the method of choice for this task. However, this method sometimes fails, particularly when the active pharmaceutical ingredient is not sufficiently retained on the column or when the impurities are not resolved from the main compound. It is therefore essential to turn to alternative and complementary analytical methods.This work deals with the development and evaluation of alternative analytical methods to reversed-phase HPLC on C18 phase for impurity profiling of pharmaceuticals. Reversed-phase HPLC on other stationary phases, mixed-mode HPLC as well as SFC were explored and their chromatographic performances compared. The comparison and the study of the different methods allowed proposing a strategy of analysis of the drug candidate.
10

Optimisation de méthodes bidimensionnelles en ligne LCxLC-UV/MS et LCxSFC-UV pour l’analyse d’échantillons complexes / Optimization of on-line two-dimensional LCxLC-UV/MS and LCxSFC-UV methods for the analysis of complex matrices

Sarrut, Morgan 17 October 2016 (has links)
La chromatographie en phase liquide bidimensionnelle « comprehensive » en ligne (LCxLC) est une technique à très haut pouvoir de séparation. Après avoir établi son intérêt mais aussi les enjeux liés au développement de méthodes et les conditions expérimentales utilisées, une attention particulière est portée à l'optimisation des méthodes en LCxLC. Une procédure d'optimisation basée une méthode « Pareto-optimal » est décrite. Les conditions optimales prédites sont ensuite appliquées à la séparation RPLCxRPLC d'un mélange complexe de peptides et comparée avec la 1D-RPLC en termes de capacité de pics, temps d'analyse et facteur de dilution démontrant l'avantage fournit par la RPLCxRPLC. L'optimisation d'une méthode HICxRPLC-UV/MS en ligne permettant la caractérisation exhaustive d'un anticorps conjugué est réalisée soulignant, entre autres, la grande complémentarité entre les différents modes de détection employés en 1D et 2D.Enfin, la possibilité de développer un couplage RPLCxSFC est explorée dans le but d'augmenter l'espace de séparation pour des composés neutres. La méthode RPLCxSFC optimisée est comparée avec une séparation RPLCxRPLC optimisée pour l'analyse d'une bio-huile montrant qu'elle peut-être considérée comme une alternative crédible pour la séparation de tels échantillons / Comprehensive two-dimensional liquid chromatography is a powerful but complex separative technique. After detailing the interest of such a technique, the method development issues and the experimental conditions employed throughout this work, a particular attention is paid to the optimization of LCxLC methods. Accordingly an optimization procedure based on Pareto-optimal method is described. The predicted optimal conditions are then applied to experimental RPLCxRPLC separations of complex samples of peptides and compared with 1D-RPLC in terms of peak capacity, analysis time and sensitivity clearly showing the advantage of RPLCxRPLC approach.The optimization of a HICxRPLC-UV/MS method for the exhaustive characterization of an antibody-drug conjugate is achieved highlighting the high complementarity of the different detection modes used both in 1D and 2D. Finally, a proof of concept concerning the implementation of RPLCxSFC coupling is achieved with the aim of increasing the separation space coverage for neutral compounds. The optimized RPLCxSFC separation is then compared with an optimized RPLCxRPLC approach for the analysis of a bio-oil sample showing that RPLCxSFC is a credible alternative for the separation of such a sample

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