Segui questo link per vedere altri tipi di pubblicazioni sul tema: NQR Spectrometer.
Tesi sul tema "NQR Spectrometer"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "NQR Spectrometer".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Kachkachi, Noreddine. "Spectromètre RQN à base d’un SoC-FPGA : Conception numérique, vérification fonctionnelle et validation expérimentale". Electronic Thesis or Diss., Université de Lorraine, 2024. http://www.theses.fr/2024LORR0053.
Testo completoAbstract (sommario):
La Résonance quadrupolaire Nucléaire (RQN) est une technique de spectroscopie radio fréquence très utile pour l'identification non invasive et l'analyse de produits chimiques. Cependant cette technique souffre de plusieurs problèmes, notamment de la faible sensibilité et pose beaucoup de défis quand à la conception de l'instrumentation RQN. Afin de relever ces défis techniques et d'améliorer davantage les performances, nous proposons de développer ici, une nouvelle approche qui consiste en la numérisation et l'optimisation de l'architecture électronique en vue d'améliorer la sensibilité. Ainsi, j'ai réalisé dans le cadre de cette thèse, la conception, la vérification fonctionnelle ainsi que la validation expérimentale d'un spectromètre RQN à base d'un SoC-FPGA où l'essentiel de la fonctionnalité matérielle et logicielle est intégré sur une seule puce. Les modules que j'ai conçus et intégrés sur le SoC-FPGA sont: un générateur d'impulsions haute résolution, un module d'acquisition entièrement numérique avec un traitement de signal temps réel et FID stocké sur mémoire externe DDR, un module d'émission numérique entièrement contrôlé et un module de débogage. En plus de la partie logique programmable, j'ai développé et intégré sur le processeur embarqué du SoC-FPGA deux applications Linux pour piloter le spectromètre. La conception de cette architecture, numérique et optimisée, a permis ainsi de se doter d'un nouveau spectromètre de performances et de fonctionnalités remarquables par rapport à l'état de l'art et par rapport aux spectromètres portables commerciaux. La miniaturisation et la numérisation ont permis aussi de réaliser la compacité du système et ainsi d'ouvrir la porte à de nouvelles applications industrielles. En plus, la réalisation de cette nouvelle architecture à base de SoC-FPGA, a apporté une amélioration de la sensibilité grâce à une meilleure immunité aux bruits et à une chaîne d'acquisition entièrement numérique avec un traitement de signal performant. Le spectromètre réalisé a été testé avec succès sur plusieurs échantillons de référence ainsi que sur des échantillons à applications pharmaceutiques tels que le paracétamol et le nitroprussiate de sodiumNuclear Quadrupolar Resonance (NQR) is a radio frequency spectroscopy technique that is very useful for non-invasive identification and analysis of chemical products. However, it suffers from low sensitivity which makes its instrumentation very challenging. In order to tackle these challenges and enhance the performances, especially sensitivity,we present in this thesis a solution which consists in a SoC-FPGA based compact spectrometer, where all the major digital hardware and software modules are integrated on a single System On Chip, including : a high pulse width resolution pulse programmer, a fully controllable transmitter, an acquisition module with real time digital signal processing, and storage of the acquired signal in an external memory, and a hardware debugger, in addition to embedded Linux applications that drive the spectrometer functionalities. This digital integration and miniaturisation brought noticeable performances of the spectrometers' overall functionality, especially in terms of sensitivity and portability. The designed spectrometer was successfully tested on several representative samples
2
Ariando, David Joseph. "A Portable Low-Cost NMR Spectrometer". Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1515170982121573.
Testo completo
3
Digby, Megan Elizabeth. "Broadband DC SQUID NMR spectrometry on metals". Thesis, Royal Holloway, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322702.
Testo completoAbstract (sommario):
This Thesis describes the development of a broadband pulsed NMR spectrometer, based on a sensitive DC SQUID amplifier with wideband electronics, to observe directly the free precession of nuclear spins in bulk metallic samples (with broad NMR linewidths) at Larmor frequencies cß/2 ,r below 1 MHz. The sample is located inside a pickup coil, which forms a superconducting flux transformer with the input coil of the SQUID. The SQUID amplifier operates in a flux-locked-loop (FLL), hence it is sensitive to signals from DC up to the bandwidth of the FLL electronics. A modified commercial DC SQUID amplifier, with modulated feedback electronics, observed NMR signals from bulk platinum samples (T2 - 1.1 ms), at 1.5 K. The SQUID amplifier had a 50 kHz bandwidth, a dead-time - 50 μs, and a coupled energy sensitivity cc - 500h. The measurements showed that it is important to minimise the time-constant of eddy current decay in the sample, which scales with r2, as expected, where r is the sample dimension. A DC SQUID amplifier with additional positive feedback and wideband electronics configured using the direct offset integration technique, observed NMR signals from a bulk aluminium sample (T2 - 30 μs) at 20 mK. This SQUID amplifier had a 7.5 MHz bandwidth, the dead-time was 55 μs for small transmitter pulses and e,; - 600h. The use of a strongly coupled input coil with the SQUID necessitated damping across the coil to smooth out the SQUID flux-voltage characteristicThe NMR measurements showed that eddy current decay is less important if the NMR signal size is enhanced by cooling the sample. Measurements also confirmed that the NMR signal from bulk metal is proportional to 4c0, and that a reasonable estimate of the signal size is made by assuming the signal is due to spins within half the skin-depth of the surface
4
Barlow, G. K. "Development and application of some techniques for proton and sodium NMR". Thesis, University of York, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383846.
Testo completo
5
Gädke, Achim, Markus Rosenstihl, Christopher Schmitt, Holger Stork e Nikolaus Nestle. "DAMARIS – a flexible and open software platform for NMR spectrometer control". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194317.
Testo completoAbstract (sommario):
Home-built NMR spectrometers with self-written control software have a long tradition in porous media research. Advantages of such spectrometers are not just lower costs but also more flexibility in developing new experiments (while commercial NMR systems are
typically optimized for standard applications such as spectroscopy, imaging or quality control applications). Increasing complexity of computer operating systems, higher expectations with respect to user-friendliness and graphical user interfaces as well as increasing complexity of the NMR experiments themselves have made spectrometer control software development a more complex
task than it used to be some years ago. Like that, it becomes more and more complicated for an individual lab to maintain and develop an infrastructure of purely homebuilt NMR systems and software. Possible ways out are:
● commercial NMR hardware with full-blown proprietary software or
● semistandardized home-built equipment and common open-source software environment for spectrometer control.
Our present activities in Darmstadt aim at providing a nucleus for the second option:
DArmstadt MAgnetic Resonance Instrument Software (DAMARIS) [1]. Based on an ordinary PC, pulse control cards and ADC cards, we have developed an NMR spectrometer control platform that comes at a price tag of about 8000 Euro.
The present functionalities of DAMARIS are mainly focused on TD-NMR: the software was successfully used in single-sided NMR [2], pulsed and static field gradient NMR diffusometry [3]. Further work with respect to multipulse/multitriggering experiments in the time domain [4] and solid state NMR spectroscopy multipulse experiments are under development.
6
Persson, Josef. "Measurement of Reduction Efficiency in Green Liquor Using a NIR Spectrometer". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-318.
Testo completoAbstract (sommario):
Domsjö Fabriker has earlier installed a Near Infrared (NIR) spectrometer after one of their recovery boilers. The purpose is to monitor the reduction efficiency of the boiler and later do process optimization. In this work calibration models for the instrument have been created. 108 green liquor samples have been extracted. A NIR spectrum was recorded for each sample and the samples were subsequently analyzed in laboratory for total alkali, sulfide and total sulfur. Several calibration models were created with multivariate data analysis and their performance and robustness were compared. The best model was able to predict reduction efficiency with a RMSEP of 2.75 percent units. Moreover, models were created for prediction of total alkali with a RMSEP of 0.108 mol/l, sulfides with a RMSEP of 1.95 g/l, total sulfur with a RMSEP of 2.83 g/l and S/Na2 ratio with a RMSEP of 0.022. The result is good enough that the instrument could be used to optimize the process and monitor process disturbances.
7
Hughes, Leslie Peter. "Maximum entropy methods applied to NMR and mass spectrometry". Thesis, Durham University, 2001. http://etheses.dur.ac.uk/3785/.
Testo completoAbstract (sommario):
Maximum Entropy data processing techniques have been widely available for use by NMR spectroscopisis and mass spectrometrisls since they were first reported as a tool for enhancing damaged images. However, the techniques have been met with a certain amount of scepticism amongst the spectroscopic community; not least their apparent ability to get something for nothing. The aim of the work presented in this thesis is to demonstrate that if these techniques are used carefully and in appropriate situations a great deal of information can be extracted from both NMR and mass spectra. This has been achieved by using the Memsys5 and Massive Inference algorithms to process a range of NMR and mass spectra which suffer from some of the problems which are commonly encountered in spectroscopy, i.e. poor resolution, poor sensitivity, how to process spectra with a wide range of peak widths. The theory underlying the two algorithms is described simply and the techniques for selecting appropriate point spread functions are outlined. Experimental rather than simulated spectra are processed throughout. Throughout this work the Maximum Entropy results are freated with scepticism. A pragmatic approach is employed to demonstrate that the results are valid. It is concluded that the Maximum Entropy methods do have their place amongst the many other data processing strategies used by spectroscopists. If used correctly and in appropriate situations the results can be worth the investment in time needed to obtain a satisfactory result.
8
Vilenius, Esa. "On the analysis of near-infrared point spectrometer data for the investigation of lunar surface mineralogy". [Katlenburg-Lindau] Copernicus Publ.***5004719, 2009. http://d-nb.info/996869182/04.
Testo completo
9
McGill, Colin Adam. "Studies of low-field nuclear magnetic resonance and Raman spectrometries for process analytical chemistry". Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248282.
Testo completo
10
Gouilleux, Boris. "Gradient-based methodson a benchtop spectrometer : new perspectives for low-field NMR spectroscopy". Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4036/document.
Testo completoAbstract (sommario):
La RMN à haut champ, basée sur des aimants supraconducteurs, est caractérisée par une instrumentation onéreuse et encombrante qui limite son utilisation dans les environnements de production. Le récent renouveau des aimants permanents a engendré des spectromètres RMN de paillasse qui permettent la réalisation d’expériences RMN directement sous la hotte du chimiste. L’objectif de cette thèse est d’améliorer la performance analytique de ces nouveaux spectromètres à bas champ. Dans cette optique, nous avons implémenté pour la première fois la RMN 2D Ultrarapide (UF) ainsi que des méthodes modernes de suppression du signal du solvant sur un spectromètre de paillasse opérant à 43 MHz équipé d’une bobine de gradient de champ magnétique. Suite à plusieurs optimisations, la RMN 2D UF à bas champ délivre des spectres 2D en un temps fortement réduit de qualité tout à fait intéressante. En parallèle, le développement des méthodes de suppressions permet dorénavant d’appréhender l’utilisation de solvant non-deutérés sur des échantillons statiques ou en flux. Ces travaux ont débouché sur de nouvelles opportunités pour la RMN à bas champ. Plusieurs suivis de réactions, réalisés en ligne et en temps réel, ont été menés à bien sur diverses réactions comme le couplage de Heck-Matsuda, la neutralisation de mimes de gaz moutardes ou encore la synthèse d’un composé naturel par chimie en flux. Par ailleurs, la RMN 2D UF à bas champ a été appliquée avec succès pour discriminer des huiles alimentaires en fonction de leurs origines botaniques. Cette méthodologie 2D, compatible avec des analyses à haut débit, démontre une amélioration notable par rapport à la RMN 1DHigh-field NMR based on superconducting magnets involves an expensive and bulky equipment, which has hampered the use of NMR in harsh environments. A new generation of benchtop NMR spectrometers, compact and cryogen free, has brought NMR spectroscopy under the chemist’s fume-hood and as close as possible to production sites. The driving force of this PhD project is to improve the analytical performance of these benchtop NMR systems. We report here the first implementation of Ultrafast (UF) 2D NMR- a method yielding 2D NMR spectra in a single scan- as well as modern gradient-based solvent suppression methods on a 43 MHz benchtop spectrometer, including a B0-gradient coil. Substantial optimizations have led to UF experiments at low-field (LF) with a reasonable performance while the acquisition duration is reduced by one order of magnitude. Then, the presence of non-deuterated solvents –commonly used in LF NMR– has been tackled by the development of suppression methods both in static and flowing conditions. This methodological effort has opened new opportunities for benchtop NMR applications. Several on- and in-line real-time monitorings have been performed on different types of chemical reactions: Heck-Matsuda coupling reaction, oxidative neutralization of mustard-gas simulants or even the synthesis of a natural product in flow-chemistry. Besides applications to process monitoring, UF 2D NMR at 43 MHz has been successfully applied to discriminate the botanical origins of a panel of edible oils. This fast 2D approach has provided a better classification than standard 1D experiments while remaining compatible with high-throughput analysis
11
Ajimo, Jacob. "A UV-Visible-NIR, Time-Resolved Fluorescence Spectrometer for High-Pressure Biological Studies". Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1134160375.
Testo completo
12
Oriola, Folch Marta. "Non-destructive condition assessment of painting canvases using NIR spectrometry". Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/663091.
Testo completoAbstract (sommario):
El soporte de tela de los cuadros se compone mayoritariamente de celulosa. Una de las vias de degradación de la celulosa es la hidrólisis ácida, que implica que en un ambiente ácido (bajo pH), la degradación se produce a una velocidad mayor. La principal consecuencia de esta acidez es la ruptura de las cadenas del polímero de celulosa que se mide a través del grado de polimerización (DP). Una disminución del DP implica que las fibras y los tejidos tienen una resistencia mecánica menor, y consecuentemente este parámetro se puede utilizar para monitorizar el estado de conservación de estos materiales. Así pues, el conocimiento de estos dos parámetros, pH y DP puede ser muy útil para la mejor conservación del soporte textil de los cuadros.
El objetivo principal de esta tesis ha sido determinar si el espectrómetro de infrarrojo cercano (NIR) Labspec 5000, se podría calibrar para que, de manera totalmente no destructiva, pudiera determinar el estado de conservación del soporte de tela de los cuadros a través de medir el pH y el DP. Esto efectivamente se consiguió utilizando la herramienta de quimiometría PLS (Partial Least Squares). Se obtuvieron errores de predicción de ±0.43 para el pH y de ±275 para el DP. La calibración para la identificación del tipo de fibra también se pudo hacer utilizando el Discriminant Analysis, otra herramienta de la quimiometría.
Para poder construir el método NIR no destructivo, primero había que analizar de manera destructiva un número significativo de muestras que fueron tomadas de cuadros mayoritariamente de los siglos XIX y XX.
El segundo objetivo principal de esta tesis ha sido conocer cuáles son los valores típicos de pH y DP y el tipo de fibra de los cuadros. Por lo que a esto se refiere, los resultados han sido que la tela de los cuadros tiene, la mayoría de las veces, un carácter ácido (la media de los resultados de todos los cuadros fue de pH 5.51, con una desviación estándar de 0.66). El estudio del pH ha permitido constatar que la tela de los reentelados realizados con pasta de harina, en general, es claramente más ácida que la tela de los cuadros no reentelados. En relación al tipo de fibra, se ha detectado que las telas de yute són más ácidas que las de lino y algodón. No se ha encontrado una relación directa entre la fecha de los cuadros y su valor de pH, y sólo una ligera relación entre la fecha y el DP. Se detectó que pH y DP están fuertemente correlacionados, aunque no de manera directa, cosa que implica que hay otros factores como el tipo de fibra, la fecha del cuadro u otros, que influyen en la correlación entre estos dos parámetros.
El tercer objetivo principal de esta tesis ha sido establecer el significado de los varios valores de DP por lo que se refiere al estado de conservación de la pintura sobre tela. Esta información junto con el valor de pH, sirvió para diseñar una ¿Clasificación según el estado de conservación¿, cosa que habría de permitir establecer una organización de los cuadros según las acciones de conservación-restauración a emprender. Se realizó un test con la participación de un grupo de conservadores-restauradores especializados en pintura sobre tela y procedentes de distintos países que permitió ver que la apreciación subjetiva del conservador-restaurador sobre el estado de conservación de las muestras de tela, en general se corresponde con el grado de polimeración de éstas. A través de los resultados de este estudio se pudo establecer que el valor de ¿DP crítico¿ para un cuadro está en <400 y el valor de ¿DP seguro¿ está en >1400. La ¿Clasificación según el estado de conservación¿ se diseñó teniendo en cuenta toda esta nueva información y por eso se priorizó el tratamiento de aquellos cuadros con una tela más ácida pero con valores de DP todavía no muy bajos, puesto que los resultados indicaban que estos cuadros serían los que más se beneficiarían de algún tipo de tratamiento de desacidificación (activo o pasivo).
El último objetivo de la tesis ha consistido en aplicar la técnica NIR no destructiva desarrollada, así como la ¿Clasificación según el estado de conservación¿ sobre un caso real de pinturas pertenecientes al Museu Nacional d¿Art de Catalunya (MNAC), fechadas alrededor del año 1900. También se ha estudiado un grupo menor de cuadros de Salvador Dalí de la Fundació Gala-Salvador Dalí. Los resultados han corroborado por un lado la buena aplicabilidad del método no destructivo dessarrollado y, por otro, la acidez (y la presencia de cierta degradación) de la tela de todos los cuadros.
Habiendo confirmado, tanto que la tela de los cuadros es mayoritariamente ácida como la influencia que ésta tiene en la velocidad de su degradación, se considera que es de vital importancia empezar a tomar medidas para contrarrestar la acidez de las telas; especialmente si la intención es no aplicar operaciones tan intrusivas como el reentelado en los cuadros durante el máximo tiempo posible. Juntamente con esto, se detecta que es necesaria mucha más investigación sobre los efectos positivos y negativos de la desacidificación de la tela de los cuadros, así como también el estudio de los orígenes concretos de esta acidez (materiales originales, materiales de restauración, entorno de las obras, etc.).
13
Pagnano, Marco Aurelio de Oliveira. "Automação de um espectrômetro por ressonância magnética nuclear pulsada". Universidade de São Paulo, 1993. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-19082014-101639/.
Testo completoAbstract (sommario):
Este trabalho consistiu na automação do espectrômetro de Ressonância Magnética Nuclear Pulsada existente no laboratório dos professores José Pedro Donoso e Claudio José Magon. Foram efetuados circuitos adicionais e melhorias no equipamento que eles possuíam, à nível de hardware e software. Foram construídas e programadas interfaces paralelas que ligam o microcomputador a um gerador de pulsos, fabricado pela Tecmag Inc., e a um digitalizador rápido (10 ns) Nicolet 430. O programador de pulsos pode acionar independentemente 75 linhas durante o intervalo de tempo subdividido em 2048 eventos, também independente. O software desenvolvido permite a programação de todas as linhas e eventos de forma eficiente e prática. Foi todo escrito em linguagem C, é modular, portátil, e permite a geração de seqüências de pulsos sofisticadas e também o controle da aquisição e transferência de dadosThis work describes the Project developped to automatize the pulsed nuclear magnetic resonance spectrometer housed in the laboratory of the professors José Pedro Donoso e Cláudio José Magon. To satisfy our needs we have improved their old equipment, at the level of hardware and software. Were built and programmed the parallel interface between the microcomputer and a pulse programmer made by Tecmag Inc. and with a fast digitizer (10 ns) Nicolet 430. The pulse programmer can control 75 independent output channels during 2048 time intervals. The software we developped allow us to control the whole pulse sequence on a very efficient and practical way. It was written in C-language, and provides the timing signals necessary to generate sofisticated pulse seqüencies, the data acquisition and data transfer to the host computer
14
Motyčka, Lukáš. "Radiofrekvenční metoda detekce výbušnin a drog - NQR". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-219982.
Testo completoAbstract (sommario):
The thesis deals with RF spectroscopic methods, which are applicable for the detection of hazardous substances such as explosives or drugs. Particular attention is focused on promising method of nuclear quadrupole resonance. Abroad this method has recently been applied in the detection of energetic materials in hazardous locations. The cornerstone of the nuclear quadrupole resonance is to evaluate the interaction between electromagnetic radiation, in the range of medium to very short waves, and the researched substance. Observed parameter are the resonant frequencies of the substance. Spectral analysis of signal is used for their evaluation. Resonant frequencies are always typical for the crystalline structure, therefore every explosive or drug is clearly identifiable by this method.
15
Weekes, Anna L. "Design and construction of an ultrasonic probe for use in a Cryo-Magnet NMR Spectrometer". Thesis, Aston University, 1998. http://publications.aston.ac.uk/9612/.
Testo completoAbstract (sommario):
SINNMR (Sonically Induced Narrowing of the Nuclear Magnetic Resonance spectra of solids), is a novel technique that is being developed to enable the routine study of solids by nuclear magnetic resonance spectroscopy. SINNMR aims to narrow the broad resonances that are characteristic of solid state NMR by inducing rapid incoherent motion of solid particles suspended in a support medium, using high frequency ultrasound in the range 2-10 MHz. The width of the normal broad resonances from solids are due to incomplete averaging of several components of the total spin Hamiltonian caused by restrictions placed on molecular motion within a solid. At present Magic Angle Spinning (MAS) NMR is the classical solid state technique used to reduce line broadening, but: this has associated problems, not least of which is the appearance of many spinning side bands which confuse the spectra. It is hoped that SlNNMR will offer a simple alternative, particularly as it does not reveal spinning sidebands The fundamental question concerning whether the use of ultrasound within a cryo-magnet will cause quenching has been investigated with success, as even under the most extreme conditions of power, frequency and irradiator time, the magnet does not quench. The objective of this work is to design and construct a SINNMR probe for use in a super conducting cryo-magnet NMR spectrometer. A cell for such a probe has been constructed and incorporated into an adapted high resolution broadband probe. It has been proved that the cell is capable of causing cavitation, up to 10 MHz, by running a series of ultrasonic reactions within it and observing the reaction products. It was found that the ultrasound was causing the sample to be heated to unacceptable temperatures and this necessitated the incorporation of temperature stabilisation devices. Work has been performed on the investigation of the narrowing of the solid state 23Na spectrum of tri-sodium phosphate using high frequency ultrasound. Work has also been completed on the signal enhancement and T1 reduction of a liquid mixture and a pure compound using ultrasound. Some preliminary "bench" experiments have been completed on a novel ultrasonic device designed to help minimise sample heating. The concept involves passing the ultrasound through a temperature stabilised, liquid filled funnel that has a drum skin on the end that will enable the passage of ultrasound into the sample. Bench experiments have proved that acoustic attenuation is low and that cavitation in the liquid beyond the device is still possible.
16
Gipson, Geoffrey T. Sokhansanj Bahrad. "Discovery Of discriminative LC-MS and 1H NMR metabolomics markers /". Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2766.
Testo completo
17
Shah, Siddharth Prakashchandra. "LIPID COMPOSITIONS OF MICROBIAL ORGANISMS ISOLATED FROM EXTREME ENVIRONMENTS AND THEIR IMPLICATION IN THERMO STABILITY OF BACTERIAL CELL MEMBRANE STRUCTURE". Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/419298.
Testo completoAbstract (sommario):
ChemistryPh.D.
Microorganisms with an ability to thrive in harsh environments are referred as “extremophiles”. With advances in biotechnology, interest has grown in the extremophile research because of their unique macromolecules’ characteristics due to their growth environments. Over last decade, researchers have isolated many extremophiles from environments like volcano, salt lakes, hydrothermal vents, deep oceans, Antarctica glaciers etc. Macromolecules of these extremophiles are responsible for their survival in extreme environments. In this research work we have isolated lipid molecules from three different microorganisms. 1) GWE1 strain, a thermophilic bacterium, isolated from dark crusty material from sterilization ovens. 2) 7L strain, a thermophilic bacterium, isolated from Chilean Copahue Volcano. 3) I1P strain, a facultative anaerobe of the family Enterobacteriaceae, recently isolated from Antarctica. Complex lipid arrangement and/or type in the cell membrane are known to affect thermostability of microorganisms and efforts were made to understand the chemical nature of the polar lipids of membrane. In this work, we extracted total lipids from cell membrane, separated them by TLC into various fractions and characterize the lipid structures of fractions with analytical tools such as 1H, 13C, 31P and 2D NMR spectroscopy, ATR-FTIR spectroscopy and MSn spectrometry. In GWE1 strain, we were able to identify glycerophosphoethanolamine, glycerophosphate, glycerophosphoglycerol and cardiolipin lipid classes and an unknown glycerophospholipid class with novel MS/MS spectra pattern. We have also noticed the presence of saturated iso-branched fatty acids with NMR spectra in individual lipid classes. In case of I1P strain, we have identified glycerophosphoglycerol, glycerophosphoethanolamine, glycerophosphate, and acyl glycerophosphoglycerol lipid classes with unsaturated fatty acids in their structure, which could be one of the many reasons for survivability at lower temperatures. In case of 7L strain, we were able to identify glycerophosphoglycerol, cardiolipin, glycerophosphoethanolamine and glycerophosphate lipid classes with saturated iso branched fatty acids. FAME analysis revealed iso-15:0 (52.29 %) and iso-17:0 (18.64 %) as major fatty acyl chains. We did not observe major difference in polar head group composition of lipid classes between thermophiles (GWE1 and 7L) compare to psychrophiles (I1P). Major difference among these three strains was in fatty acid composition of lipid molecule. Both thermophiles showed presence of lipids with long chain saturated fatty acids while I1P showed presence of lipid molecule with unsaturated fatty acid chain. Lipids made of unsaturated fatty acids have lower melting points and they introduce kink in the cell membrane structure. At lower temperatures, these effects allow membrane to maintain fluidity and its functionality, which in turn allows the microorganism to grow at lower temperature. Lipids made with saturated iso branched fatty acid chain have higher melting points and they pack together densely in cell membrane. At high temperature because of higher melting point and dense packing, membrane fluidity is not affected and this effect allows microorganism to grow at the higher temperature. We believe that change in fatty acid composition is one of the many reasons for these microorganisms to survive the extreme condition. Thermostability of the other macromolecules (DNA, enzyme) of these extremophiles is not studied in this dissertation.
Temple University--Theses
18
Li, Jian. "Using cadmium-113 NMR spectrometry to study metal complexation by natural organic matter". Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/25720.
Testo completo
19
Petry, David P. "Silicalite Clear Sol Precursors Studied by NMR, Mass Spectrometry and Dynamic Light Scattering". Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525295.
Testo completo
20
Kindahl, Lill. "Structural studies of saccharides and glycopeptides in aqueous solution by ¹H NMR spectroscopy /". Uppsala : Dept. of Chemistry, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a377.pdf.
Testo completo
21
Chen, Ling. "Improvements in excitation selectivity and spectral precision in Fourier transform NMR and mass spectrometry /". The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487330761219982.
Testo completo
22
Puschmann, Robert. "Analysis and Quantification of Inositol Poly- and Pyrophosphates by NMR Spectroscopy and Mass Spectrometry". Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21044.
Testo completoAbstract (sommario):
Inositolpyrophosphate (PP-InsP) sind eine Gruppe sekundärer Signalmoleküle, die in einer Vielzahl zellulärer Prozesse, von Phosphathomeostase über Insulinsignalisierung bis Apoptose eine Rolle spielen. Die Art und Weise, wie PP-InsPs ihre Funktion ausführen, noch weitgehend unbekannt. Deshalb wurden zwei neue analytische Methoden basierend auf Kernspinresonanzspektroskopie und Flüssigchromatographie mit Massenspektrometrie-Kopplung (LCMS) entwickelt.
Um die limitierende Sensitivität der Kernresonanzspektroskopie zu umgehen, wurde die Synthese von kernspinresonanzaktivem, 13C-markiertem Inositol optimiert. Des Weiteren wurde eine chemoenzymatische Synthese für alle Säugetier-PP-InsP-Isomere entwickelt, die auf der skalierbaren Ausfällung mittels Mg2+ Ionen basiert. Menschliche Zellen wurden mit 13C-Inositol isotopenmarkiert und in den Spektren der Zellextrakte wurde, basierend auf den PP-InsP-Standards, Fingerabdrucksignale identifiziert mit denen die Konzentrationen der dazugehörigen Moleküle bestimmt werden konnte.
Die LCMS basierte Methode wurde auf dem Prinzip der Umsetzung von hochgeladenen Inositolpyrophosphaten zu ihren korrespondieren Methylestern mittels Trimethylsilyldiazomethan geplant. Die ungeladenen, permethylierten PP-InsPs wären geeignet für LC-Auftrennungen und MS-Messungen und sollten eine von Kernspinresonanzspektroskopie nicht erreichbare Sensitivität ermöglichen. Die Methode wurde mittels Inositolhexakisphosphat (InsP6), einem einfacheren PP-InsP-Analog, etabliert und methyliertes InsP6 konnte in Mengen von 10 femtomol detektiert werden. Die Adaption der Methode für die PP-InsPs gestaltete sich jedoch herausfordernd, da der Analyt während der Reaktion zersetzt wurde. Ein Wechsel zu Diazomethan als Methylierungsagens zeigte vielversprechende Resultate.Inositol pyrophosphates (PP-InsPs) are a well conserved group of second messengers that are involved in a plethora of cellular processes including phosphate homeostasis, insulin signaling, and apoptosis. Despite much effort, it is still mostly unknown how PP-InsPs exert their diverse functions. In order to decipher the mechanisms, researchers have relied either on metabolic labeling with radioactive inositol or on electrophoretic separation on polyacrylamide gels but these methods either lack ease of use or sensitivity. Therefore, two new analytical tools, based on nuclear magnetic resonance (NMR) spectroscopy, and liquid chromatography coupled mass spectrometry (LCMS), were developed. To overcome the limited sensitivity provided by NMR spectroscopy, a high yielding synthesis of NMR-active 13C-labeled inositol was designed and optimized. Furthermore, a chemoenzymatic synthesis of all mammalian PP-InsPs isomers was developed that relied on a scalable purification strategy utilizing precipitation with Mg2+ ions. Human cells were metabolically labeled with 13C-inositol and the prepared PP-InsPs were used as standards to identify peaks in the NMRspectra. These fingerprint signals enabled the quantification of the corresponding molecules. The LCMS-based method was based on the derivatization of the highly charged inositol pyrophosphates to their corresponding methyl esters by trimethylsilyldiazomethane. The permethylated InsPs and PP-InsPs were suitable for LC separation and MS measurement, and provide a sensitivity unmatched by NMR spectroscopy. The method was established using inositol hexakisphosphate, a simpler analog of PP-InsPs, and methylated InsP6 could be detected at quantities as low as 10 femtomole. However, the adaptation of the derivatization for PP-InsPs proved challenging as the reaction caused degradation of the analyte but strategies to circumvent the decay by changing the derivatization agent to diazomethane were promising.
23
Brodbeck, Roland. "Balloon-borne far-infrared Fabry-Perot spectrometer for astrophysical observations /". [S.l.] : [s.n.], 1997. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=12510.
Testo completo
24
Bajwa, Tejbir Singh. "Development of a software tool to perform qualitative analysis on spectral data obtained from a NIR-MOEMS spectrometer". abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1464416.
Testo completo
25
Banerjee, Utsab. "Development of Novel High-Frequency EPR Spectrometer and In-house fabrication of NMR MAS drive caps and ultra-centrifuge kit packing tools". Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS585.pdf.
Testo completoAbstract (sommario):
La spectroscopie par résonance magnétique nucléaire (RMN) est une méthode puissante qui permet de comprendre les processus chimiques et de caractériser une grande variété de molécules. La simplicité de la préparation, l'absence de dommages à l'analyte et les faibles des échantillons sont autant de raisons qui font de la RMN une méthode de spectroscopie largement utilisée. Cependant, elle présente également certains inconvénients, notamment une faible sensibilité. Il existe plusieurs méthodes pour améliorer la sensibilité de la RMN. La polarisation nucléaire dynamique (DNP) est l'un des moyens les plus puissants d'améliorer la sensibilité de la RMN. Pour évaluer avec précision les paramètres de la DNP et caractériser les propriétés dynamiques de spin dans des échantillons de compositions identiques (mêmes concentration et solvant) et soumis à la même puissance d'irradiation par micro-ondes, à la même basse température de l'hélium liquide ainsi qu'au même champ magnétique, il est nécessaire de détecter simultanément les signaux de RMN et de RPE. Afin de construire facilement et à coût modéré une sonde RPE/RMN, on a utilisé la technique de détection longitudinale de la RPE. La détection longitudinale (LOD) de la RPE repose sur l'utilisation d'une bobine de détection alignée parallèlement au champ magnétique statique, afin de détecter les variations de l'aimantation longitudinale. La bobine de détection est placée dans un plan orthogonal à la bobine d'émission et accordée sur une gamme de fréquences différente, ce qui réduit le couplage éventuel et le bruit de l'émission. Une modulation d'amplitude des micro-ondes afin de saturer périodiquement l'aimantation électronique, réalisant ainsi également une modulation de l'aimantation longitudinale. L'aimantation longitudinale variable qui en résulte induit alors une tension alternative dans la bobine EPR dont l'axe est parallèle à l'axe de la bobine. Dans cette thèse, nous avons également montré que l'EPR LOD peut être utilisé comme "hacheur" optique. Ceci est important car cela nous permettra d'utiliser le hacheur optique avec des sources de micro-ondes de haute puissance comme le gyrotron où la modulation d'amplitude des micro-ondes n'est pas possible. L'autre sujet de ce travail concerne les couvercles des rotor pour la RMN à l'état solide, par impression 3D, et les kits d'ultracentrifugation pour emballer les échantillons dans les rotors de RMN à l'état solide. La technologie d'impression en 3D permet de produire des pièces à faible coût et avec une grande précision (<100 micron). Un examen de la littérature récente dans le domaine a montré que la technologie d'impression 3D pouvait être mise à profit pour fabriquer un système de rotation à angle magique (MAS) destiné à la spectroscopie par résonance magnétique nucléaire (RMN) à l'état solide. Nous montrons ici que non seulement les imprimantes 3D de paillasse à des prix abordables permettent de produire des capuchons de 3,2 mm avec une qualité similaire à celle de la version commercialisée, mais aussi des capuchons plus petits, de 2,5 mm et de 1,3 mm, malgré un léger compromis en termes de performances. Toutes les têtes d'entraînement fabriquées en interne (de 1,3 à 7 mm) peuvent être reproduites de manière reproductible (>90 %) et permettent d'atteindre d'excellentes performances en rotation. En résumé, les systèmes > 3,2 mm ont des performances similaires à celles des systèmes commerciaux, tandis que les coiffes de 2,5 et 1,3 mm peuvent tourner jusqu'à 26 kHz ± 2 Hz et 46 kHz ± 1 Hz, respectivement. La fabrication interne rapide et peu onéreuse des capuchons de rotors MAS permet de prototyper facilement de nouveaux modèles de capuchons d'entraînement MASNuclear magnetic resonance (NMR) spectroscopy is a powerful method that can give insights into chemical processes and has the capability to characterize a wide variety of molecules. The simplicity of the preparation, absence of damage to the analyte, and moderate sample volumes needed are among the important reasons which make NMR a widely used spectroscopy method. However, it also has some drawbacks, such as low sensitivity. There are several methods to improve the sensitivity of NMR. One of the most powerful ways to improve the NMR sensitivity is dynamic nuclear polarization (DNP). Therefore, to accurately evaluate the DNP parameters, and characterize the spin dynamic properties of samples containing the same concentration and solvent and subjected to the same microwave irradiation power, cryogenic temperature, and magnetic field, a dual detection capability of NMR and EPR is required. In order to easily and cost effectively build an EPR/NMR probe, longitudinal detected EPR technique is used here. Longitudinal detection (LOD) of EPR is based on a pickup coil aligned parallel to the static magnetic field, , to measure a changing longitudinal magnetization. The detection coil is placed orthogonal to the transmit coil and tuned to a different frequency range, which reduces the transmit crosstalk and noise. The longitudinal magnetization can be modulated by an amplitude modulation of microwave to periodically saturate the electron magnetization. The resulting time-dependent longitudinal magnetization then induces an alternating voltage in the EPR coil with an axis parallel to . Here in this thesis we have also showed that LOD EPR can be used optical chopper. This is important because this will enable us to use the optical chopper with high power microwave sources like the gyrotron where microwave amplitude modulation is not possible. The other topic mentioned here is 3D printed caps for solid state NMR and ultracentrifuge kits to pack samples in solid state NMR rotors.The 3D-printing technology has emerged as a well-developed method to produce parts with considerably low cost and yet with high precision (<100 micron). Recent literature has shown that the 3D-printing technology can be exploited to fabricate a magic-angle spinning (MAS) system in solid-state nuclear magnetic resonance (NMR) spectroscopy. Here, we show that not only lab-affordable benchtop 3D printers can produce 3.2 mm drive caps with a similar quality as the commercialized version, but also smaller 2.5 mm and 1.3 mm MAS drive caps—despite a slight compromise in performance. All in-house fabricated drive caps (1.3 to 7 mm) can be consistently reproduced (>90 %) and achieve excellent spinning performances. In summary, the > 3.2 mm systems have similar performances as the commercial systems, while the 2.5- and 1.3-mm caps can spin up to 26 kHz ± 2 Hz, and 46 kHz ± 1 Hz, respectively. The low-cost and fast in-house fabrication of MAS drive caps allows easy prototyping of new MAS drive cap models and, possibly, new NMR applications
26
Dag, Semiha. "Structural studies of some bacterial lipopolysaccharides and extracellular polysaccharides using NMR spectroscopy and mass spectrometry /". Uppsala : Dept. of Chemistry, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200545.pdf.
Testo completo
27
Moletta, Mattia <1994>. "Organic Synthesis and Characterization (NMR, mass spectrometry) of Beta-Glucosyl-Cholesterol for Parkinson's Disease research". Master's Degree Thesis, Università Ca' Foscari Venezia, 2020. http://hdl.handle.net/10579/18008.
Testo completoAbstract (sommario):
The aim of this research consists in the organic synthesis and characterization of a synthetic equivalent of β-glucosylcholesterol bearing a terminal alkyne functionality to ascertain, in collaboration with a research group of biologists from University of Padova, the possible involvement of this class of derivatives in the Parkinson’s disease’s aetiology. The target molecule, thanks to the presence of a reactive acetylenic moiety is suitable to further conjugation by “Click Chemistry” with azido functionalized solid supports or fluorophores. The synthetic approach consisted into overall 12 synthetic steps to produce the 3 synthetic synthons (glucosyl, cholesteryl and acetylenic units) requested for the preparation of the final molecule. The synthesis of the three synthons has been almost completed and largely optimized and each intermediate has been thoroughly characterized by NMR spectroscopy and high resolution mass spectrometry. In the near future the final target molecule will be obtained through final coupling methods.
28
Zoppi, Ugo. "Isobar suppression in accelerator mass spectrometry /". [S.l.] : [s.n.], 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10373.
Testo completo
29
Piecuch, Scott. "A Fast NIR Spectrometer for Examining Explosive Events: Emission of PETN Based Explosives and H₂O Absorption Method Feasibility". [Milwaukee, Wis.] : e-Publications@Marquette, 2009. http://epublications.marquette.edu/theses_open/13.
Testo completo
30
Srivastava, Abhishek. "Metabolism and bioactivation of nevirapine in humans and rats : Integrated application of NMR and mass spectrometry". Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526804.
Testo completo
31
Sanh, Alan Dominique. "Peptide-RNA recognition : investigation of non-covalent interactions using ESI-mass spectrometry and proton NMR spectroscopy". Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/352.
Testo completo
32
Tolonen, A. (Ari). "Analysis of secondary metabolites in plant and cell culture tissue of Hypericum perforatum L and Rhodiola rosea L". Doctoral thesis, University of Oulu, 2003. http://urn.fi/urn:isbn:9514271610.
Testo completoAbstract (sommario):
Abstract
Sensitive chromatographic methods were developed for the quantitative analysis of secondary metabolites in Hypericum perforatum (St. John's wort) and Rhodiola rosea (Golden root, rose root) extracts. Sample preparation methods were developed for plant, cell culture and biotransformation suspension matrixes. High performance liquid chromatography (HPLC) was used for the separation of analytes, and chromatographic data was acquired using photodiode array (PDA) detection or atmospheric pressure ionization mass spectrometry (API-MS). Ionization efficiencies with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) were compared under different conditions. Specific mass spectrometric detection methods such as multiple reaction monitoring (MRM) and selective ion monitoring (SIM) were utilized. For identification of known and new secondary metabolites in plant tissues, mass spectrometric methods with triple quadrupole and time-of-flight mass spectrometers were used together with one- and two-dimensional nuclear magnetic resonance spectroscopy (NMR).
33
Samino, Gené Sara. "Mass spectrometry and nuclear magnetic resonance based metabolomics applied to the study of polycystic ovary syndrome". Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/128209.
Testo completoAbstract (sommario):
Objectives:
Three objectives of this thesis have been: (i) Mastering of the main analytical platforms used in metabolomics, (ii) Developing an untargeted metabolomic workflow, involving novel aspects of sample preparation, and data processing for metabolite identification, (iii) Implementing our untargeted metabolomic workflow to the study of human patients with Polycystic Ovary Syndrome (PCOS) and their response to drug treatment
Results:
In Work 1: Optimization metabolite extraction conditions for NMR analysis, followed by LC/ESI-MS by using the same sample extract with no need for solvent exchange or further pretreatment.
In Work 2: Investigate the impact of different aspects of univariate statistical analysis on untargeted LC-MS based metabolomic experiments.
In Work 3: Implementation of GC-MS untargeted metabolomic approach to provide new insights on the impact that obesity exerts on the metabolic derangements associated with PCOS.
In Work 4: Implementation of multiplatform metabolomics approach based on NMR and LC-MS to provide new insights in PCOS disease in a cohort of young lean PCOS patients.
In Work 5: Implementation of multiplatform metabolomics approach based on NMR, GC-MS and LC-MS to provide new insights on the action of drug polytherapy to PCOS disorder.
Conclusion:
Metabolomics can be consider as a powerful tool for the study of metabolic disorders. Furthermore, metabolite profiling has demonstrated feasibility and flexibility for revealing new mechanistic insights in metabolic disorders that are not been consider when classical analysis is used. Therefore, our metabolomic analysis have demonstrated a great potential as a useful diagnostic technique and can facilitate monitoring of both disease progression and effects of therapeutic treatment.Objetivos: El presente trabajo tiene dos objetivos generalizables que han sido estudiados con más detalle en la presente tesis doctoral. El primero de ellos es mejorar aspectos metodológicos en el ámbito de la metabolómica y el segundo ha sido la aplicación de la metabolómica en el estudio del síndrome del ovario poliquístico (PCOS). Resultados: Del primer objetivo se han realizado dos trabajos: en el primero, la optimización de un método de extracción común para analizar muestras biológicas en dos plataformas analíticas complementarias utilizadas en metabolómica como son la resonancia magnética nuclear y la espectrometría de masas. Del segundo trabajo realizado se han obtenido unas pautas para abordar los retos que surgen del análisis de datos de metabolómica en espectrometría de masas. Del segundo objetivo también han sido realizados dos trabajos: en ambos se ha utilizado la metabolómica no dirigida para abordar el estudio del PCOS. En el primer trabajo, se ha utilizado la metabolómica para conocer el impacto que ejerce la obesidad en los trastornos metabólicos asociados al PCOS. En el segundo trabajo, se ha utilizado la metabolómica no dirigida para evaluar como afecta la aplicación de una politerapia con medicamentos al metabolismo de pacientes con PCOS. Conclusión: La metabolómica puede ser utilizada como una nueva herramienta para estudiar los trastornos metabólicos.
34
Gädke, Achim, Markus Rosenstihl, Christopher Schmitt, Holger Stork e Nikolaus Nestle. "DAMARIS – a flexible and open software platform for NMR spectrometer control: DAMARIS – a flexible and open software platform for NMRspectrometer control". Diffusion fundamentals 5 (2007) 6, S. 1-9, 2007. https://ul.qucosa.de/id/qucosa%3A14270.
Testo completoAbstract (sommario):
Home-built NMR spectrometers with self-written control software have a long tradition in porous media research. Advantages of such spectrometers are not just lower costs but also more flexibility in developing new experiments (while commercial NMR systems are
typically optimized for standard applications such as spectroscopy, imaging or quality control applications). Increasing complexity of computer operating systems, higher expectations with respect to user-friendliness and graphical user interfaces as well as increasing complexity of the NMR experiments themselves have made spectrometer control software development a more complex
task than it used to be some years ago. Like that, it becomes more and more complicated for an individual lab to maintain and develop an infrastructure of purely homebuilt NMR systems and software. Possible ways out are:
● commercial NMR hardware with full-blown proprietary software or
● semistandardized home-built equipment and common open-source software environment for spectrometer control.
Our present activities in Darmstadt aim at providing a nucleus for the second option:
DArmstadt MAgnetic Resonance Instrument Software (DAMARIS) [1]. Based on an ordinary PC, pulse control cards and ADC cards, we have developed an NMR spectrometer control platform that comes at a price tag of about 8000 Euro.
The present functionalities of DAMARIS are mainly focused on TD-NMR: the software was successfully used in single-sided NMR [2], pulsed and static field gradient NMR diffusometry [3]. Further work with respect to multipulse/multitriggering experiments in the time domain [4] and solid state NMR spectroscopy multipulse experiments are under development.
35
Roos, Felix Franz. "Algorithms for peptide identification by tandem mass spectrometry /". Zürich : ETH, 2006. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16844.
Testo completo
36
Sierk, Bernd. "Solar spectrometry for determination of tropospheric water vapor /". Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13850.
Testo completo
37
Wortmann, Arno. "Investigation of noncovalent complexes with soft ionization mass spectrometry /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17353.
Testo completo
38
Müller, Lukas Niklaus. "Novel computational techniques for quantitative mass spectrometry based proteomics /". Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17802.
Testo completo
39
Paudel, Liladhar. "High Field 1H Nuclear Magnetic Resonance (NMR) Spectroscopy Based Metabolomics and Complex Mixture Analysis by Multidimensional NMR and Liquid Chromatography-Mass Spectrometry (LC-MS)". University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1343403647.
Testo completo
40
Forshed, Jenny. "Processing and analysis of NMR data : Impurity determination and metabolic profiling". Doctoral thesis, Stockholm : Dept. of analytical chemistry, Stockholm university, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-712.
Testo completo
41
Chen, Yanyi. "Dissecting Key Determinants for Calcium and Calmodulin Regulation of GAP Junction and Viral Protein". Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/chemistry_diss/64.
Testo completoAbstract (sommario):
Calcium and calmodulin are implicated in mediating the Ca2+-dependent regulation of gap junctions that are essential for the intercellular transmission of molecules such as nutrients, metabolites, metal ions and signal messengers (< 1000 Da) through its specialized cell membrane channels and communication to extracellular environment. To understand the key determinants for calcium and calmodulin regulation of gap junction, in this study, we identified a calmodulin binding domain in the second half of the intracellular loop of Cxonnexin50 (the major gap junction protein found in an eye lens) using peptide fragments that encompass predicted CaM binding sites and various biophysical methods. Our study provides the first direct evidence that CaM binds to a specific region of the ubiquitous gap junction protein Cx50 in a Ca2+-dependent manner. Furthermore, two novel CaM binding regions in cytosolic loop and C-termini of Connexin43 (the most ubiquitous connexin) have been shown to interact with CaM with different binding modes in the presence of Ca2+ using high resolution NMR. Our results also elucidate the molecular determinants of regulation of gap junction by multiple CaM targeting regions and provide insight into the molecular basis of gap junction gating mechanism and the binding of CaM to the cytoslic region Cx43-3p as the major regulation site. Upon response to the cytosolic calcium increase, CaM binds to the cytosolic loop to result in the conformational change of gap junction and close the channel. It is possible for CaM to use an adjacent region as an anchor close to the regulation site to allow for fast response. Since a large number of residues in the Cxs mutated in human diseases reside at the highly identified CaM binding sites in Cxs, our studies provide insights into define the critical cellular changes and molecular mechanisms contributing to human disease pathogenesis as part of an integrated molecular model for the calcium regulation of GJs. In addition, we have applied the grafting approach to probe the metal binding capability of predicted EF-hand motifs within the streptococcal hemoprotein receptor (Shr) of Streptococcus pyrogenes as well as the nonstructural protein 1 (nsP1) of Sindbis virus and Poxvirus. This fast and robust method allows us to analyze putative EF-hand proteins at genome-wide scale and to further visualize the evolutionary scenario of the EF-hand protein family. Further, mass spectrometry has also been applied to probe modification of proteins such as CaM labeling by florescence dye and 7E15 by PEG.
42
Rigau, Roca Laura. "Identification of protein-ligand interactions by mass spectrometry and NMR, case studies: LFA-1, Bcl-xl and Bcl-2". Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492546.
Testo completoAbstract (sommario):
Current genomic and proteomic research is generating a considerable number of potential new therapeutic targets. To tackle all these pharmacological targets, the development of rapid and reliable screening methods, which give information on protein-ligand interactions, are of great importance. New advances in these technologies are often emerging and more will surely follow.
43
Abdullah, Sewa Faraj. "Proteomics approaches to polyketide synthases interfaces by mass spectrometry and NMR spectroscopy and the application of chemometrics to metabolomics". Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682232.
Testo completoAbstract (sommario):
Proteomics is a rapidly growing discipline dealing with structure, molecular interactions, conformational dynamics, modifications and the functions of proteins. Mass spectrometry (MS) and (nuclear magnetic resonance) (NMR) have been used comprehensively to study protein interactions. Acyl carrier protein (ACP) interacts with more than 30 partner proteins during either fatty acid or polyketide biosynthesis. In order to be fully activated ACP gains a 4'-phosphopantetheinyl (4'-PP) group from coenzyme A using acyl carrier protein synthase (AcpS) via posttranslational modification. Protein-protein interactions of the ACP from the actinorhodin (act) polyketide synthase (PKS) complex and AcpS were investigated using oxidative footprinting with hydroxyl radicals generated from the Fenton reaction. Chemical modification of acidic residues was also used to investigate the interaction between these proteins using l-ethyl-3-(3- dimethylaminopropyl) carbodiimide (EDC) this acted as a zero length cross linker to induce modification with Me-Glycine. MS was used to identify the modified residues and peptides and the extent of modification. Several residues were found to be protected in the complex between the two proteins and these may participate in the interaction interface between ACP and ACPS. Isotopically labelled ACP was expressed and purified and multidimensional NMR experiments were recorded to investigate this interaction interface identified using oxidative footprinting techniques. Chemical shift perturbations for ACP residues were calculated, and these revealed that many residues were affected by oxidation of ACP. Oxidation of methionine to methionine sulfoxide was confirmed. Metabolomics is a discipline which deals with metabolites in a biological system. It provides a wealth information for disease diagnosis, drug discovery, toxicology and genetic modification. Attempts have been made in this thesis to utilize metabolomics in biometrics. Mice were used as a model to attempt to determine individuals' age by their scent. In this part of the project chemometric methods were used to discriminate mice using a gas chromatography-mass spectrometry dataset of volatile organic compounds obtained from their urine. Principal component regression (PCR), partial least squares regression (PLSR) and support vector regression (SVR) were used to determine mouse age. Mice could be discriminated by their age using SVR without overfitting the data.
44
Grajcar, Michal. "New concepts of ¹°Be accelerator mass spectrometry at low energies /". Zürich : ETH, 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16249.
Testo completo
45
Bensimon, Maklouf. "Photodissociation d'ions par laser infrarouge dans un spectromètre de masse à transformée de Fourier /". [S.l.] : [s.n.], 1987. http://library.epfl.ch/theses/?nr=694.
Testo completo
46
O'Kennedy, Sean James. "A kinetic and thermodynamic study of procyanidin oligomer conformation by 1H NMR and DFT". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/98054.
Testo completo
47
Ma, Cunxian. "Tentative Identification of Hydroxylated 2,2',3,5',6-pentachlorobiphenyl Metabolites in Whole Poplar Plants by a Combination of Chromatographic and Spectrometry Techniques". Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/4691.
Testo completoAbstract (sommario):
2,2',3,5',6-pentachlorobiphenyl (PCB95) is a chiral congener of the persistent organic pollutants (POPs) family of PCBs. It has been shown that chiral PCBs can be enantioselectively transformed into hydroxylated metabolites by cytochrome P450 in animals. Previous studies in our group suggested that PCB 95 can be enantioselectively translocated and metabolized in whole poplar plants. In this work, healthy whole poplar plants were hydroponically exposed to PCB95 for 30 days. Two unknown OH-PCB95 metabolites were detected in the roots by HPLC-MS. Different chromatographic and spectrometry techniques, including HPLC-MS, NMR and GC-MS, were tried to determine the structure of the more abundant metabolite of the two. It was identified to be 4'-OH-PCB95 (4'-95) by GC-MS method. The data show that PCB95 can be transformed into at least two hydroxylated metabolites by whole poplar plants, with one of them being 4'-95. Chiral analysis of 4'-95 by HPLC-MS showed slightly more abundance of the second eluting enantiomer E2-4'-95 in the roots, suggesting that the biotransformation of PCB95 to 4'-95 is enantioselective. Comparison with animal studies shows a distinct metabolite profile in whole poplar plants.
48
Joubert, Valentin. "Analyse isotopique positionnelle pour les sciences forensiques : développement et utilisation de la spectrométrie RMN quantitative 13C and 15N NMR spectrometry". Thesis, Nantes, 2018. http://www.theses.fr/2018NANT4078/document.
Testo completoAbstract (sommario):
Dans la bataille contre le trafic des stupéfiants, c’est le concept de profilage du produit illicite qui est couramment utilisé comme outil de lutte contre les réseaux de distribution de la drogue. Ce profilage est réalisé à partir des teneurs en impuretés de synthèse, des solvants résiduels, etc. Le projet ANR FRIIME propose de suivre le même objectif en utilisant la teneur isotopique comme marqueur intrinsèque de la molécule cible. Jusqu’à présent seule la teneur moyenne en isotope a été exploitée et mesurée par spectrométrie de masse isotopique (SMRI). En recourant à une technologie innovante utilisant la résonance magnétique nucléaire (RMN), la capacité de mesurer site par site les teneurs isotopiques, donne maintenant accès à de nouvelles informations. Ces travaux de thèse reposent sur l’optimisation d’une séquence multi-impulsionnelle (INEPT) permettant d’améliorer significativement la sensibilité de la RMN 13C et d’assurer un traçage isotopique complet des molécules de taille importante. Ce nouvel outil sera testé sur des échantillons réels de drogue pour lesquels les agents de coupage seront analysés afin d’obtenir un profil isotopique marqueur de leur origine. De nouvelles informations sur les réseaux seront ainsi collectées. Pour la première fois, ce savoir-faire sera également transposé à l’analyse isotopique positionnelle en 15N par RMN quantitative comme contribution pour les analyses d'explosifs comme le 2,4,6-trinitrotoluène (TNT)In the battle against the illicit drugs market, this is drug profiling which is currently used as a tool to track drugs trafficking routes. Profiling methods can rely on synthetic impurities, residual solvents, etc. In the ANR project FRIIME, the same objective will be pursued but using the intrinsic marker of the isotopic content of the target molecules. So far, only overall isotopic content has been exploited and measured by isotope ratio mass spectrometry (irm-MS). By using innovative methods employing nuclear magnetic resonance (NMR), the study of the position-specific isotopic distribution of the targeted products is now obtained. This work was based on the optimization of a multi-pulse sequence (INEPT) enabling to improve significantly NMR 13C sensitivity in order to ensure full isotopic tracing on large molecules. This new tool will be tested on real samples of drug for which the cutting agents will be analyzed to have an isotopic profile marker of their origin. Then new information on networks will be obtained. For the first time, this knowledge will be transposed to 15N position-specific isotopic analysis by quantiative NMR as contribution for explosives analyses as 2,4,6-trinitrotoluene (TNT)
49
Bovet, Cédric. "Characterizing the endocrine disrupting activity of small molecules using mass spectrometry /". Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17873.
Testo completo
50
Dubois, Frédéric Dubois Frédéric. "Ion formation and detection in matrix-assisted laser desorption/ionization mass spectrometry /". [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13255.
Testo completo