Thèses : « Proton and phosphorus Nuclear Magnetic Resonance »

1

Potwarka, John J. « A proton decoupled phosphorus-31 nuclear magnetic resonance spectroscopy study of schizophrenia ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0019/MQ58006.pdf.

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SIOTTO, MICHELA BARBARA. « Study of the biodegradation in soil of new generation plactics ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/19950.

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The intense use of plastic contributes to increase the amount of municipal waste that are generally disposed in landfill. For some applications and sectors, an important alternative to the conventional plastic materials can be found in the use of the new generation materials: the biodegradable polymers. Their use can be an alternative to landfill disposal and can thus reduce the cost of waste management and the accumulation in the environment. The biodegradable polymers, in fact, are used by microorganisms as source of carbon and are converted by into carbon dioxide (or methane), water and mineral salts of any other element present (mineralization) plus new biomass. Generally, laboratory test methods developed for determining the biodegradability of polymeric material are based on the evaluation of the carbon dioxide production (respirometric test), but in order to completely describe the biodegradation process and to avoid an underestimation of the biodegradation percentage, it is very important to quantify and identify possible by-products and biomass production. The experimental work presents in this thesis concerned the study of the different aspects of the biodegradation of new generation plastics in soil. Particular attention was focused on the fate of the possible by-products of biodegradable polymers (the monomers) and on the determination of the biomass generated during the process. To summarize: 1) The effects of the soil pH on the mineralization of ten monomers, chosen between the most widely used for the synthesis of plastic materials, was evaluated by respirometric tests and the experimental data were used to validate a numerical model that can estimate the amount of carbon used by microorganism for biochemical synthesis. 2) The mineralization of a model polyester was investigated by respirometric tests in different soil mixtures in order to evaluate the effects of the initial soil pH and of the addition of organic matter. 3) The combustion of soil samples at 550 °C was used for determining the amount of organic matter and biomass in soil samples. The sensitivity of the method was evaluated by adding different low amounts of organic matter to a natural and a synthetic soil. 4) In order to describe the carbon balance during the biodegradation of the model polyester, biomass production and polyester residues in soil were estimated. Biomass and organic matter deriving by polyester biodegradation were studied by combustion of soil samples. Polyester residues were estimated by extractions in soxhlet of soil samples (with chloroform) and the extracts were characterized by 1H-NMR and 31P-NMR acquisitions and GPC.

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Meng, Jiqun J. « Line scan proton magnetic resonance spectroscopic imaging ». Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36963.

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Kendall, Nigel Lincoln. « Nuclear magnetic resonance study of new polycyclic phosphorus compounds ». Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481631.

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5

Wilkes, Philip John. « NMR of phosphorus-containing solids ». Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6666/.

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The purpose of this work has been the determination of structure in solids using the technique of solid-state nuclear magnetic resonance spectroscopy. High-resolution (^31) p NMR spectra have been obtained for a range of phosphate species. A number of techniques have been applied to these systems including cross-polarization, magic angle spinning, and high power proton decoupling. Characterisation using additional NMR techniques such as (^1) H cramps has been carried out wherever possible. The results obtained yield molecular and crystallographic information consistent with data from X-ray diffraction when known. Shielding tensor components were determined from static and/or spinning spectra wherever possible. The phosphate species studied include a series of precipitated calcium phosphates. A particular model for the structure of amorphous calcium phosphate is favoured in the light of (^31) p NMR measurements. One sample showed NMR evidence for changes in composition whilst in the solid state. The origins of (^31) p NMR line widths in high-resolution solid-state spectra have been considered in some detail. Variation of (^31) p NMR linewidth as function of spinning rate has been noted for a number phosphate compounds. Multiple pulse techniques have been applied on the phosphorus channel with pleasing improvements in spectral resolution. Five solid binary phosphorus sulphides have also been studied using phosphorus MAS NMR, and the results compared to solution state data wherever possible. A number of anomalies between solution and solid-state data have been noted and discussed.

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6

Florian, Catarina Ligia. « Proton nuclear magnetic resonance studies of human glioma cell lines ». Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309218.

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Sitanggang, M. Linda. « Application of proton nuclear magnetic resonance in drug metabolism studies ». Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380409.

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Clarke, William. « Human cardiac magnetic resonance spectroscopy ». Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:b75351dc-e4eb-4856-b901-4ba486ffe175.

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The status of the myocardial 'high energy phosphate' metabolism is a sensitive marker of the occurrence and progression of heart failure. Magnetic resonance spectroscopy enables non-invasive, direct and potentially quantitative measurements of the phosphate containing metabolites present in the human myocardium. This thesis is primarily concerned with the creation of measurement techniques for cardiac phosphorus magnetic resonance spectroscopy (³¹P-MRS) at the 7 tesla field strength. Chapter 1 provides an overview of the physical basis of magnetic resonance spectroscopy, the myocardial high energy phosphate metabolism, and the clinical relevance of the technique. Chapter 2 describes the advantage of 7 tesla scanners over lower field strengths. The radio frequency coil hardware is characterised experimentally. The multivoxel spectroscopy methods used throughout the thesis are described. Chapter 3 details the implementation of an open source spectroscopy fitting program. It is validated against previous closed-source implementations. The program's use is demonstrated in several clinical studies of heart failure, and to improve a previously implemented ¹H spectroscopy coil combination method. In Chapter 4 the measurement of inorganic phosphate in the presence of overlapping peaks is attempted. Suppression of overlapping peaks, originating from the blood, is tried using B_o gradients, then saturation transfer. The myocardial pH of hypertrophic cardiomyopathy patients is measured. Chapter 5 describes the effect of creatine kinase catalysed chemical exchange on the ³¹P-MRS spectrum. A survey of methods suitable for measuring creatine kinase kinetics at 7 tesla is made. Multi-parametric fitting of variable repetition time saturation transfer data is explored in simulation and experiment. Chapter 6 describes the re-implementation and extension, for dynamic measurements, of the triple repetition time saturation transfer method for two clinical studies at 3 tesla. The creatine kinase forward rate constant is measured in heart failure and healthy cohorts, at rest, and during cardiac stress. In Chapter 7 a Bloch-Siegert B₁ mapping sequence is implemented for ³¹P-MRS. An optimal Bloch-Siegert method for X-nuclear spectroscopy is calculated. B₁maps are validated in skeletal muscle and collected in 5 volunteer's hearts. Chapter 8 uses the Bloch-Siegert B₁ mapping sequence and the four angle saturation transfer method to implement creatine kinase rate measurement at 7 tesla. The first 3D localised creatine kinase rate measurements in the human myocardium are achieved in 10 volunteers.

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Princz, Eva J. « A proton nuclear magnetic resonance study of human tumor biopsy samples ». Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/6000.

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Vannini, Marianna <1986&gt. « Valorisation of organic waste : new developments from proton nuclear magnetic resonance characterization ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6946/1/Vannini_Marianna_tesi.pdf.

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The last half-century has seen a continuing population and consumption growth, increasing the competition for land, water and energy. The solution can be found in the new sustainability theories, such as the industrial symbiosis and the zero waste objective. Reducing, reusing and recycling are challenges that the whole world have to consider. This is especially important for organic waste, whose reusing gives interesting results in terms of energy release. Before reusing, organic waste needs a deeper characterization. The non-destructive and non-invasive features of both Nuclear Magnetic Resonance (NMR) relaxometry and imaging (MRI) make them optimal candidates to reach such characterization. In this research, NMR techniques demonstrated to be innovative technologies, but an important work on the hardware and software of the NMR LAGIRN laboratory was initially done, creating new experimental procedures to analyse organic waste samples. The first results came from soil-organic matter interactions. Remediated soils properties were described in function of the organic carbon content, proving the importance of limiting the addition of further organic matter to not inhibit soil processes as nutrients transport. Moreover NMR relaxation times and the signal amplitude of a compost sample, over time, showed that the organic matter degradation of compost is a complex process that involves a number of degradation kinetics, as a function of the mix of waste. Local degradation processes were studied with enhanced quantitative relaxation technique that combines NMR and MRI. The development of this research has finally led to the study of waste before it becomes waste. Since a lot of food is lost when it is still edible, new NMR experiments studied the efficiency of conservation and valorisation processes: apple dehydration, meat preservation and bio-oils production. All these results proved the readiness of NMR for quality controls on a huge kind of organic residues and waste.

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Vannini, Marianna <1986&gt. « Valorisation of organic waste : new developments from proton nuclear magnetic resonance characterization ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6946/.

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The last half-century has seen a continuing population and consumption growth, increasing the competition for land, water and energy. The solution can be found in the new sustainability theories, such as the industrial symbiosis and the zero waste objective. Reducing, reusing and recycling are challenges that the whole world have to consider. This is especially important for organic waste, whose reusing gives interesting results in terms of energy release. Before reusing, organic waste needs a deeper characterization. The non-destructive and non-invasive features of both Nuclear Magnetic Resonance (NMR) relaxometry and imaging (MRI) make them optimal candidates to reach such characterization. In this research, NMR techniques demonstrated to be innovative technologies, but an important work on the hardware and software of the NMR LAGIRN laboratory was initially done, creating new experimental procedures to analyse organic waste samples. The first results came from soil-organic matter interactions. Remediated soils properties were described in function of the organic carbon content, proving the importance of limiting the addition of further organic matter to not inhibit soil processes as nutrients transport. Moreover NMR relaxation times and the signal amplitude of a compost sample, over time, showed that the organic matter degradation of compost is a complex process that involves a number of degradation kinetics, as a function of the mix of waste. Local degradation processes were studied with enhanced quantitative relaxation technique that combines NMR and MRI. The development of this research has finally led to the study of waste before it becomes waste. Since a lot of food is lost when it is still edible, new NMR experiments studied the efficiency of conservation and valorisation processes: apple dehydration, meat preservation and bio-oils production. All these results proved the readiness of NMR for quality controls on a huge kind of organic residues and waste.

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Howe, Daniel Trusler. « Nuclear Magnetic Resonance Microscopy of NafionÂ®-117 Proton Exchange Polymer Membranes ». Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/howe/HoweD1204.pdf.

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Lee, Kai Mon. « Solution structures of yeast ribosomal 5S and 5.8S ribonucleic acids via 500 MHz proton nuclear magnetic resonance spectroscopy / ». The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487322984316599.

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Davidson, Anne. « Investigation of treatment related neurotoxicity following childhood cancer by proton magnetic resonance spectroscopy ». Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287842.

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Barbet-Massin, Emeline. « Structure of bio-macromolecular complexes by solid-state Nuclear Magnetic Resonance ». Thesis, Lyon, École normale supérieure, 2013. http://www.theses.fr/2013ENSL0811.

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La RMN du solide a récemment émergé en tant que technique très puissante en biologie structurale, permettant de caractériser au niveau atomique des systèmes qui ne peuvent être étudiés par d’autres méthodes. Des protocoles spécifiques à la RMN du solide sont à présent bien établis pour la préparation des échantillons, l’attribution des spectres et l’acquisition de contraintes structurales. Ensemble, ces protocoles ont ouvert la voie aux premières déterminations de structures tridimensionnelles de molécules biologiques à l’état solide avec une résolution atomique, et ce non seulement pour des échantillons protéiques microcristallins, mais également pour des systèmes plus complexes tels que des fibrilles ou des protéines membranaires.La détermination structurale de tels systèmes est cependant encore loin d’être une routine, et des avancées de plus large ampleur sont attendues grâce à des développements aux niveaux méthodologique et matériel. Pour cette raison, une majeure partie du travail présenté dans cette thèse a été consacrée au développement d’expériences à la fois nouvelles et sophistiquées pour améliorer la sensibilité et la résolution des méthodes déjà existantes pour attribuer les spectres et élargir les possibilités offertes par la RMN du solide en vue d’étudier la structure de systèmes protéiques plus larges. Ces développements reposent notamment sur l’utilisation de champs magnétiques très intenses et sur la rotation des échantillons à l’angle magique dans la gamme des très hautes vitesses angulaires. Nous montrons que dans ce cadre, il est possible de concevoir des expériences utilisant uniquement des champs radiofréquences à faible puissance ainsi que d’utiliser des transferts sélectifs, l’acquisition de corrélations à travers les liaisons chimiques et la détection proton.En particulier, nous montrons que des expériences de corrélation homonucléaire reposant sur des transferts scalaires deviennent une alternative compétitive aux expériences basées sur des transferts dipolaires. Deux nouvelles séquences d’impulsion permettant de détecter des corrélations 13C-13C à travers les liaisons chimiques avec une excellente résolution sont présentées; couplées à des transferts 15N-13C, elles permettent l’attribution des résonances de la chaîne principale des protéines avec une grande sensibilité.De plus, nous démontrons qu’il est possible d’obtenir des raies très fines pour les résonances de protons dans des protéines complètement protonées à l’état solide grâce à la rotation à l’angle magique à ultra-haute vitesse, sans avoir recours à la deutération. Dans ce contexte, nous avons développé de nouvelles stratégies permettant d’attribuer rapidement et de façon fiable les résonances des spins 1H, 15N, 13CO, 13CA et 13CB dans différentes classes de protéines, ainsi que pour mesurer des contraintes structurales à partir des distances entre protons. L’approche proposée repose sur la haute sensibilité des protons et accélère donc considérablement les processus d’attribution et de détermination structurale des protéines à l’état solide, comme illustré sur la protéine beta-2-microglobuline.Enfin, nous avons appliqué cette nouvelle approche pour réaliser l’attribution et l’étude structurale et fonctionnelle de trois catégories de complexes protéiques: les fibrilles amyloidogènes formées par beta-2-microglobuline, les nucléocapsides du virus de la rougeole, et les nucléocapsides d’Acinetobacter phage205. Nous avons également utilisé la technique de Polarisation Nucléaire Dynamique pour obtenir des informations sur l’ARN des nucléocapsides du virus de la rougeole.Nous considérons que les résultats présentés dans cette thèse représentent une avancée substantielle dans le domaine de la RMN du solide appliquée à la biologie structurale. Grâce aux progrès actuels dans ce domaine, l’impact de la RMN biomoléculaire à l’état solide promet d’augmenter dans les prochaines années
Solid-state NMR has recently emerged as a key technique in modern structural biology, by providing information at atomic level for the characterization of a wide range of systems that cannot be investigated by other atomic-scale methods. There are now well established protocols for sample preparation, resonance assignment and collection of structural restraints, that have paved the way to the first three-dimensional structure determinations at atomic resolution of biomolecules in the solid state, from microcrystalline samples to fibrils and membrane-associated systems. These determinations are however still far from being routine, and larger breakthroughs are expected with further methodological and hardware developments. Accordingly, most of the work presented in this thesis consists of the development of new, sophisticated NMR experiments to improve the sensitivity and resolution of the currently existing schemes for resonance assignment and to extend the capabilities of solid-state NMR in terms of structural investigation of proteins for the analysis of large substrates. These developments notably rely on the use of very high magnetic fields and ultra-fast magic-angle spinning (MAS). We show the great potential of this particular regime, which enables the use of low-power experiments and the acquisition of selective cross-polarization transfers, through-bond correlations and 1H-detected correlations.In particular, we show that homonuclear correlation experiments based on through-bond transfers become competitive alternatives to dipolar transfer schemes. Two new pulse sequences that detect sensitive and resolved 13C-13C through-bond correlations are introduced, which coupled to 15N-13C dipolar transfer steps provide sensitive routes for protein backbone resonance assignment.Furthermore, we demonstrate that narrow 1H NMR line widths can be obtained for fully protonated proteins in the solid state under ultra-fast MAS, even without perdeuteration. In this context, we have developed new strategies for extensive, robust and expeditious assignments of the 1H, 15N, 13CO, 13CA and 13CB resonances of proteins in different aggregation states, and new schemes for the measurements of site-specific 1H-1H distance restraints. This approach relying on the very high sensitivity of 1H spins remarkably accelerates the processes of assignment and structure determination of proteins in the solid state, as shown by the assignment and de novo structure determination of native beta-2-microglobulin. Finally, we apply this new approach to perform resonance assignment and to study structural and dynamic features of three complex protein aggregates: amyloid fibrils formed by native and D76N beta-2-microglobulin, Acinetobacter phage 205 nucleocapsids and measles virus (MeV) nucleocapsids. We also used Dynamic Nuclear Polarization to obtain the first information about RNA in MeV nucleocapsids.We believe that the results presented in this thesis represent a substantial step forward for solid-state NMR in structural biology. With all the current advances in the field, the impact of biomolecular solid-state NMR is likely to increase in the next years

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Huang, Wenlin. « Structural studies of polyoxoanionic solids by vanadium-51 and phosphorus-31 solid state magic angle spinning NMR spectroscopy ». Access to citation, abstract and download form provided by ProQuest Information and Learning Company ; downloadable PDF file, 302 p, 2007. http://proquest.umi.com/pqdweb?did=1354134041&sid=15&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Lee, Martin Bryce. « Betaine Homocysteine Methyltransferase, Disease and Diet : The Use of Proton Nuclear Magnetic Resonance on Biological Methylamines ». Thesis, University of Canterbury. Chemistry, 2006. http://hdl.handle.net/10092/1319.

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Homocysteine, an independent risk factor for cardiovascular disease, is methylated in the liver via the zinc metalloenzyme betaine-homocysteine methyltransferase (BHMT). Established assays for BHMT include a radiochemical assay, a colorometric assay, an HPLC assay and an in vivo microbiological assay. These techniques are either unsuitable for substrate specificity studies, or are unable to give kinetic measurements. BHMT was purified from liver and measured directly and kinetically by a novel ¹H-NMR spectroscopic assay. The disappearance of substrates and the formation of products are monitored simultaneously. Using 2 mM glycine betaine and homocysteine as substrates in 20 mM phosphate buffer (pH = 7.5) and measuring the production of N,N-dimethylglycine the CV is 6.3% (n = 6) and the detection limit is 6 nkatal. An endpoint assay for BHMT activity was also developed and had CV = 5.3%, n = 6, with a detection limit of 2 nkatal. The NMR spectroscopic assay was used to determine the substrate specificity with a library of alternative substrates. Analysis of betaine analogues with different chain length, α-substitution, substitution of the nitrogen and carboxyl moieties demonstrated that BHMT is inactive if there is any steric crowding of the nitrogen or α-carbon positions. BHMT is capable of using group VI heteroatom betaines as methyl donors, with much faster rates than glycine betaine. For glycine betaine the Km was 0.19 ± 0.03 mM with a Vmax of 17 ± 0.7 nMol min-1 mg-1. The same assay was used to detect and partially characterise a BHMT activity from hagfish liver that is similar to that of the mammalian enzyme. NMR spectroscopy was adapted for measurements of glycine betaine in urine, along with other medically significant methylamines. These were shown to be valid for clinical use and in animal studies. A novel metabolite of the sulfonium analogue of glycine betaine (methylsulfinylmethanoate) was identified in rats.

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Bray, Christina L., Robert G. Bryant, M. J. Cox, Gianni Ferrante, Y. Goddard, Sandip Sur et Joseph P. Hornack. « The proton Nuclear Magnetic Resonance spin-lattice relaxation rate of some hydrated synthetic and natural sands ». Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-192008.

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The proton nuclear magnetic resonance (NMR) spin-lattice relaxation rate (R1) of hydrated sands is often used to determine porosity characteristics of near-surface aquifers using magnetic resonance sounding. Large variations in R1 have been reported in laboratory measurements on hydrated sands. To understand these variations, the R1 values of several fully hydrated sands were studied as a function of grain diameter (d) and magnetic field strength (BB0). We conclude the variations are a consequence of trace paramagnetic metals in the sand grains. R1 values from magnetic resonance sounding data should not be used to predict void size in aquifers unless the exact chemical composition of the grains is known.

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Wang, Zhonghua. « Proton Nuclear Magnetic Resonance Investigation of the Native and Modified Active Site Structure of Heme Proteins ». FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/513.

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Hemoproteins are a very important class of enzymes in nature sharing the essentially same prosthetic group, heme, and are good models for exploring the relationship between protein structure and function. Three important hemoproteins, chloroperoxidase (CPO), horseradish peroxidase (HRP), and cytochrome P450cam (P450cam), have been extensively studied as archetypes for the relationship between structure and function. In this study, a series of 1D and 2D NMR experiments were successfully conducted to contribute to the structural studies of these hemoproteins. During the epoxidation of allylbenzene, CPO is converted to an inactive green species with the prosthetic heme modified by addition of the alkene plus an oxygen atom forming a five-membered chelate ring. Complete assignment of the NMR resonances of the modified porphyrin extracted and demetallated from green CPO unambiguously established the structure of this porphyrin as an NIII-alkylated product. A novel substrate binding motif of CPO was proposed from this concluded regiospecific N-alkylation structure. Soybean peroxidase (SBP) is considered as a more stable, more abundant and less expensive substitute of HRP for industrial applications. A NMR study of SBP using 1D and 2D NOE methods successfully established the active site structure of SBP and consequently fills in the blank of the SBP NMR study. All of the hyperfine shifts of the SBP-CN- complex are unambiguously assigned together with most of the prosthetic heme and all proximal His170 resonances identified. The active site structure of SBP revealed by this NMR study is in complete agreement with the recombinant SBP crystal structure and is highly similar to that of the HRP with minor differences. The NMR study of paramagnetic P450cam had been greatly restricted for a long time. A combination of 2D NMR methods was used in this study for P450cam-CN- complexes with and without camphor bound. The results lead to the first unequivocal assignments of all heme hyperfine-shifted signals, together with certain correlated diamagnetic resonances. The observed alternation of the assigned novel proximal cysteine β-CH2 resonances induced by camphor binding indicated a conformational change near the proximal side.

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Bray, Christina L., Robert G. Bryant, M. J. Cox, Gianni Ferrante, Y. Goddard, Sandip Sur et Joseph P. Hornack. « The proton Nuclear Magnetic Resonance spin-lattice relaxation rate of some hydrated synthetic and natural sands ». Diffusion fundamentals 10 (2009) 8, S. 1-3, 2009. https://ul.qucosa.de/id/qucosa%3A14098.

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The proton nuclear magnetic resonance (NMR) spin-lattice relaxation rate (R1) of hydrated sands is often used to determine porosity characteristics of near-surface aquifers using magnetic resonance sounding. Large variations in R1 have been reported in laboratory measurements on hydrated sands. To understand these variations, the R1 values of several fully hydrated sands were studied as a function of grain diameter (d) and magnetic field strength (BB0). We conclude the variations are a consequence of trace paramagnetic metals in the sand grains. R1 values from magnetic resonance sounding data should not be used to predict void size in aquifers unless the exact chemical composition of the grains is known.

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Kim, Jong Hwa. « Bacillus megaterium ribosomal 5S RNA structure from proton nuclear magnetic resonance spectroscopy and molecular dynamics simulations / ». The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487683049376233.

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Hudson, Alexander Morgar James. « Proton detected '1'3C imaging : implementation and development ». Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299710.

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Choi, Seongjin. « Proton NMR and MRI studies of sub-millimeter sized biological objects ». Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1204559010.

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Jenkinson, Richard I. « The quantum dynamics of proton transfer in the hydrogen bond ». Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299563.

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Luo, Ying. « Heme Proton Resonance Assignments and Kinetics Study in High-spin and Mixed-spin Metmyoglobin Complexes by Chemical Exchange NMR Spectroscopy ». PDXScholar, 1996. https://pdxscholar.library.pdx.edu/open_access_etds/5238.

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NMR studies of paramagnetic hemoproteins have improved significantly our understanding of the structure-function relationship ofhemoproteins in general. Up to date most of the studies focus on low-spin ferric systems which are characterized by relatively narrow resonance peaks and concomitant better resolution. However, characterizing in detail the NMR spectra of high-spin ferric hemoproteins is important since there are several hemoproteins, such as peroxidases, catalases, oxygenases, and some ferricytochromes that contain high-spin iron (III) in their biologically active forms. Yet assigning resonances from heme peripheral protons and/or heme pocket residues in high-spin myoglobins is a daunting undertaking. Only a sparse number of active site residues are assigned in such instances, even for metaquo-myoglobin. The protons from the heme and heme pocket residues in high-spin complexes experience extremely fast relaxation and very broad linewidths, which impede the 2D methods that detect through-space and through-bond connectivities. It is the intention of this study to develop an effective strategy to gain more resonance assignments for fast-relaxing protons in hemoproteins. We have set out to use a combined strategy, using two-dimensional exchange spectroscopy (2D-EXSY) with two dimensional nuclear Overhauser effect spectroscopy I correlation spectroscopy I total correlation spectroscopy (NOESY/COSY/TOCSY). I demonstrate here that 2D EXSY experiments can be used to obtain assignment correlations for the heme protons of methydroxy-, metthiocyano-, metaquo-, and metimidazole-myoglobin forms. All these assignments are unambiguous and straightforward. Moreover, saturation-transfer experiments allow determination of ligand binding kinetics. Thus, the exchange rates between the metaquo- and metimidazole- or methyl substituted imidazole myoglobin complexes are estimated. The differences between the exchange rates reflect the differences in the hydrophobic and steric interactions between the ligands and the protein moiety. Although I only demonstrate the feasibility of2D EXSY for the myoglobin case, this assignment strategy should to be applicable to other hemoprotein systems.

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Tambelli, Caio Eduardo de Campos. « Estudo por Ressonância Magnética Nuclear do Condutor Protônico HPb2Nb3O10. nH2O ». Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-15092010-135855/.

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Neste trabalho foi estudado o condutor protônico HPb2Nb3O10. nH2O , por Ressonância Magnética Nuclear pulsada do próton \'ANTPOT.1H\'. Tanto o estudo da forma de linha como a relaxação spin-rede, em função da temperatura, refletem a mobilidade das espécies protônicas neste material. O início dos movimentos iônicos e moleculares produzem um forte estreitamento da largura de linha acima de 130 K. Os dados da taxa de relaxação spin-rede (1/T1) mostra um máximo entre 253 K e 273 K que depende da hidratação (n). As energias de ativação obtidas dos resultados de relaxação e largura de linha variam entre 0,14eV e 0,4eV, dependendo da hidratação. Os resultados de condutividade e RMN são consistente com um mecanismo de condução do tipo Grotthus, que consiste numa sucessão de movimentos reorientacionais e saltos de prótons. O coeficiente de difusão protônica foi estimado dos parâmetros obtidos de RMN sendo da ordem de 10-8 cm2/s. Este valor leva a uma condutividade da ordem de 10-3 S/ cm.
The protonic conductor HPb2Nb3O10. nH2O , was studied by pulsed Nuclear Magnetic Resonance (NMR) of \'ANTPOT.1H\'. The temperature dependence of the spin-lattice relaxation rate (1/\'T IND.1\') and line width, reflect the mobility of the protonic species present in this material. The onset of ionic and molecular motions produces a strong narrowing of the line at temperatures above 130 K. The spin-lattice relaxation data, obtained above 200 K, shows a maximum in 1/\'T IND.1\', peaking in the range 253 K to 273 K, depending on the value of n. Activation energies of protonic motions, measured from line width and relaxation data, are n dependent and lies in the range of 0,14 eV to 0,4 eV. Results of NMR and conductivity are consistent with the Grotthus conduction mechanism, consisting of a succession of molecular re-orientations and proton jumps. The protonic diffusion coefficient was estimated from the parameters obtained from NMR relaxation and found to be of the order of 10-8 cm2/s, leading to a conductivity of about 10-3 S/ cm.

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McIntosh, Laura Maureen. « A proton nuclear magnetic resonance study of muscle growth, dystrophy, repair and drug treatments in control and mdx mice ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23637.pdf.

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Purvis, Lucian A. B. « Absolute quantification of human in vivo hepatic 31P magnetic resonance spectroscopy at 7 tesla ». Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:80bc4b80-059b-43b5-9e4c-c38a6e29274c.

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Phosphorus (³¹P) metabolites are emerging liver disease biomarkers. This work aims to develop a quantification protocol for human hepatic ³¹P magnetic resonance spectroscopy (MRS) at 7 tesla (T). It should have high SNR, deliver robust measurements of metabolite concentrations with high reproducibility, and be feasible to use in clinical studies. This will allow detailed characterization of liver metabolism in diseases such as cirrhosis, increasing the utility of ³¹P-MRS as a clinical tool. A 3D chemical shift imaging method using a 16 channel ³¹P array at 7 T is chosen to give high SNR ³¹P spectra from the human liver in vivo, while also providing good spatial localization and spectral resolution. The Oxford Spectroscopy Analysis (OXSA) toolbox, our MATLAB-based processing software package, is introduced and adaptations for analysis of liver spectra are described. Five volunteers were scanned to determine T₁s for the ten visible ³¹P metabolites. Simulations were used to determine design criteria for calibration phantoms at 1.5, 3 and 7 T. I compare three candidate approaches to give "absolute" concentrations in mmol/L wet tissue using a 10 cm loop coil, and then extend these approaches to data acquired using the 16 element receive array. The final protocol was applied to data acquired in ten healthy volunteers and eleven patients with cirrhosis to determine reproducibility and the differences between healthy and diseased livers. This protocol allows distinction between healthy and cirrhotic livers with 90% specificity and sensitivity, using cut-offs in either Î3-adenosine triphosphate or inorganic phosphate concentrations. This ³¹P-MRS absolute quantification protocol is an important first step in fully utilising the increased SNR afforded by the 7 T scanner, offering valuable insight into liver metabolism, and paving the way for other novel ³¹P-MRS methods to be developed in the liver at 7 T.

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Kheswa, Ntombizonke Yvonne. « Synthesis of the metallocenes for the production of exotic high energy ion beams ». University of the Western Cape, 2019. http://hdl.handle.net/11394/6664.

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Philosophiae Doctor - PhD
The Subatomic Physics Department of iThemba Laboratory for Accelerated Based Sciences (iThemba LABS) conducts experiments that require a variety of particle beams in order to study nuclear properties (reaction, structure, etc.) of various nuclides. These particle beams are accelerated using the K-200 Separated Sector Cyclotron (SSC) and delivered to different physics experimental vaults. Prior to acceleration, the particle beam is first ionised using an Electron Resonance Ion Source (ECRIS). The main goal of this study is the production of exotic metallic beams of 60Ni8+ and 62Ni8+ using ECRIS4, which are required for the Coulomb excitation experiments approved by the Programme Advisory Committee (PAC) at iThemba LABS. In order to provide the metallic beams of nickel, a development study of organometallic materials containing 60Ni and 62Ni isotopes in a form of metallocene complexes was undertaken. The nickelocene (NiCp2) complex, a member of the organometallic family, was synthesised at the Physics Target Laboratory of iThemba LABS for the first time. Method development involved the use of natural nickel during the multi-step synthesis before the use of enriched nickel-60 (60Ni) and nickel-62 (62Ni). Nine samples of NiCp2 were synthesised; two were isotopically enriched nickelocene (60NiCp2 and 62NiCp2). The percentage yields of the synthesised nickelocene samples ranged between 16 to 50 %, and samples were characterised by investigating their crystal structure and bonding arrangements in the complexes by X-ray diffraction (XRD) , Fourier Transform Infrared (FT-IR) spectroscopy, and Proton Nuclear Magnetic Resonance (1H NMR). The synthesised nickelocene were further used with ECRIS4 for the production of Ni beams on the Q-line of the cyclotron. The Metal Ions from Volatile Compounds (MIVOC) technique was used for the conversion of 60Ni and 62Ni to ion species. The method used the organometallic compounds which are volatile at specific pressures at ambient temperatures. Metallic ion beams of nickel were successfully produced after a carefully pre-sample conditioning in the MIVOC container before connecting the MIVOC set-up to the new injection system of the ECRIS4. Measured beam intensities during the experiment for both 60Ni+ and 62Ni+ were approximately 30 μA, optimum for physics measurements. The development of the MIVOC technique opens up new beam-target combinations with the use of new exotic stable beams for new science cases at iThemba LABS. Reactions in inverse kinematics, multi-step Coulomb-excitation and other types of reactions will immensely benefit from these developments.

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Kalapos, Thomas Lawrence. « Interaction of Water with the Proton Exchange Fuel Cell Membrane ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1175891061.

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Baker, Ross E. « The time course of changes in skeletal muscle metabolites during muscle repair, as detected by proton nuclear magnetic resonance spectroscopy ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ41678.pdf.

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Van, Calsteren Marie-Rose. « Phosphorus-31 and deuterium solid-state nuclear magnetic resonance studies of the headgroup conformation of phosphonolipids in biological and model membranes ». Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7929.

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Solid-state nuclear magnetic resonance (NMR) techniques were applied to the study of the phase behavior and to the determination of the headgroup conformation of phosphonolipids, both natural and synthetic. The results are compared with those for analogous phospholipids in biological and model membranes. $\sp{31}$P NMR was used to characterize the phase behavior of phospho- and phosphonolipids present in polar and total lipid extracts of the protozoa Tetrahymena thermophila. The $\sp{31}$P NMR spectra of aqueous dispersions of polar and total lipids consist in the partial superposition of two powder patterns, one for each phosphorus-containing lipid class. At low temperature, both lipid extracts give rise to lineshapes characteristic of the lamellar structure. Spectra of the polar lipids show that between 15 and 40$\sp\circ$C, a broad, reversible transition from bilayer to hexagonal phase takes place. On the other hand, the phase behavior for total lipids is different: no hexagonal phase is formed, the lipids remain in the bilayer phase at a higher temperature, and a transition to an isotropic phase occurs between 35 and 40$\sp\circ$C, which is not easily reversible. A large proportion of ethanolamine-containing lipids, both phosphate and phosphonate analogs, is responsible for the hexagonal phase formation observed with the polar lipids. When neutral lipids are present with the polar lipids, the bilayer is stabilized up to a higher temperature. One of the neutral lipid components, tetrahymanol, a pentacyclic triterpenoid, is believed to be responsible for this stabilization. The results show that the conformation of the headgroup up to the phosphorus atom is very similar in phospho- and phosphonolipids, i.e. the C2-C3-O-P torsion angle is nearly trans and the C3-O-P-C1 angle variable over the range of values investigated, with a bend at the phosphorus atom. Contrary to the phosphodiester moiety in analogous phospholipids which adopts a gauche-gauche conformation, two solutions for the next torsion angle O-P-C1-C2 were found around 100 and 130$\sp\circ$. The last segment P-C1-C2-N is nearly trans, whereas the corresponding O-C1-C2-N segment in phospholipids is gauche. Despite the differences in the torsion angle values, the overall appearance of the headgroup is similar for both phospho- and phosphonolipids. The headgroup first extends out of the bilayer plane, bending at the phosphorus atom and the terminal portion lies nearly parallel to the membrane surface. (Abstract shortened by UMI.)

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Xu, Bo. « Proton NMR relaxation investigations of particle exfoliation and distribution in polymer/clay nanocomposites ». Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42936.

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In the past two decades polymer/clay nanocomposites (PCNs) have emerged as promising materials that exhibit remarkably improved properties when compared to conventional composites and pristine polymers. Such improvements strongly depend on the dispersion of clay nanoparticles in the polymer matrix. In spite of great efforts expended in characterizing clay dispersion, effective, simple and quantitative techniques are still needed. This work addresses this challenge by presenting new aspects of 1H solid-state NMR for quantifying clay dispersion in PCNs filled with clay containing paramagnetic ions. Employing these 1H solid-state NMR methods, some structure-processing-deformation relationships of PCNs were derived, and basic insights into nuclear relaxation and spin diffusion in PCNs were gained as well. Detailed models and analyses were described for 1H spin-lattice relaxation in the presence of paramagnetic clays in PCNs. Relaxation recovery was analytically correlated to clay dispersion in two ways: one is the initial relaxation recovery which is related to clay surface area, and the other is the spin-lattice relaxation time which is related to interparticle spacing. These two NMR observables were employed to quantitatively observe the evolution of clay morphology in poly(propylene)/clay (PP/MMT) nanocomposites upon equibiaxial stretching, as well as upon in situ uniaxial deformation. The initial relaxation recovery was independently utilized to determine the polymer-clay interfacial surface area and the degree of clay exfoliation. We demonstrated the capabilities of our models in quantitatively characterizing several materials, including poly(vinyl alcohol), nylon 6, poly(å-caprolactone) (PCL), poly(lactic acid) (PLA) and PP nanocomposites. These results were used to examine the dependence of clay morphology upon processing (strain ratio, strain rate, temperature), deformation (extension), component characteristics (polymer molecular weight, clay surface modification) and clay content. Effects of paramagnetic Fe3+ concentration and external magnetic field strength on 1H spin-lattice relaxation in PCNs were also investigated and discussed. In particular, low field separates the initial relaxation recovery into two stages: one related to clay content and the other related to the polymer-clay interfacial surface area. The low field was observed to enhance the paramagnetic contribution to the spin-lattice relaxation rate, increasing its sensitivity to clay morphology. In addition, measurements of long-distance spin diffusion coefficients for a variety of polymers and paramagnetic characteristics of organically modified clay were explored. Overall, the utility of NMR relaxometry in characterizing PCNs has been significantly expanded and successfully demonstrated in this dissertation.

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Taghavikish, Mona. « Tetrakis(2,6-diisopropylphenyl)diphosphine and related compounds : an electrochemical and EPR spectroscopic study of radical cations ». Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Chemistry and Biochemistry, c2012, 2012. http://hdl.handle.net/10133/3310.

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In this thesis the synthesis and full characterization of a new bulky diphosphine, tetrakis-(2,6-diisopropylphenyl)diphosphine, are described. This compound displays facile oxidation and a thorough investigation of its redox properties has been studied by combining solution electrochemical techniques such as cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry, with spectroscopic methods such as electron paramagnetic resonance (EPR) and Simultaneous Electrochemical Electron Paramagnetic Resonance (SEEPR) spectroscopy over a wide temperature range. Density functional theory (DFT) calculations were carried out to aid in structural characterization of the radical cation that is produced and to provide computed hyperfine splitting (HFS) constants for comparison with experimental results. For comparison to this species with bulky aromatic substituents, similar studies were conducted that have identified the previously unreported radical cation of tetrakis-tert-butyldiphosphine with a bulky aliphatic substituent that provides even higher steric pressure than the 2,6-diisopropylphenyl group. DFT calculations are reported, as is full characterization with fluid and frozen-solution EPR spectroscopy. Further CV and EPR (SEEPR) studies are reported that led to the identification of radical cations of tris(2,6-diisopropylphenyl)arsine and bis(2,4,6-triisopropylphenyl)(2,6-diisopropylphenyl)phosphine. DFT calculations are reported, as is full characterization with fluid and frozen-solution EPR spectroscopy.
xix, 172 leaves : ill (some col.) ; 29 cm

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Tan, Paul S. G. « Phosphorus 31 nuclear magnetic resonance study of the mechanism and kinetics of the hydrolysis of zinc (II) O,O'-dialkyl dithiophosphate, its basic salt and some related compounds ». Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/14518.

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S1P n.m.r. spectroscopy was used to investigate the mechanism and kinetics of hydrolysis of zinc (II) O,O'-dialkyl dithiophosphates (ZDTP's) in aqueous 1,2-dimethyoxyethane solution at 85°C. All the major intermediates and products were identified and the relative reaction rates of the key steps in the hydrolysis determined. Diethyl ZDTP was found to be hydrolysed (k= 2.35 x 10~4 s"1) to phosphoric acid via O,O'-diethyl dithiophosphoric acid 9ktyj = 1.35 x 10~2 s"1) and thiophosphoric acid (kfcyj = 0.78 x 10~6 s"1); O-ethyl dithiophosphoric acid and dithiophosphoric acid were found to be intermediates; O-elhyl, O,O'-diethyl thiophosphoric and O-ethyl phosphoric acids were produced as by-products of the reaction. From a study of the order of appearance of the intermediates and products, a detailed mechanism for the hydrolysis of ZDTP's has been proposed. The relationship between the 'normal' salt of a ZDTP and its 'basic' form was also studied and the isopropyl derivative was found to dissociate in a variety of organic solvents (including xylene, toluene, diethyl ether, chloroform, 1,2-dimethoxy ethane, acetone, dimethyl formamide and dimethyl sulphoxide) via a facile equilibrium into its 'normal' salt and zinc (II) oxide. The dissociation was promoted by increasing temperature and solvent polarity and by increasing the water content in aqueous 1,2-dimethoxy-ethane. This equilibrium in favour of the 'normal' salt and zinc (II) oxide was also acid-catalysed. Zinc (II) oxide arising from the dissociation of the 'basic' form was found to inhibit the hydrolysis of 'normal' zinc (II) O,O'-diisopropyl dithiophosphate by reaction with its primary hydrolysis product, O,O'-diisopropyl dithiophosphoric acid. Eventual hydrolysis occurred after all the zinc (II) oxide was consumed.

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Msayib, Yunus. « Quantifying impaired metabolism following acute ischaemic stroke using chemical exchange saturation transfer magnetic resonance imaging ». Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:a98323ce-5998-436d-bca4-09df549cf191.

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In ischaemic stroke a disruption of cerebral blood flow leads to impaired metabolism and the formation of an ischaemic penumbra in which tissue at risk of infarction is sought for clinical intervention. In stroke trials, therapeutic intervention has largely been based on perfusion-weighted measures, but these have not been shown to be good predictors of tissue outcome. The aim of this thesis was to develop analysis techniques for magnetic resonance imaging (MRI) of chemical exchange saturation transfer (CEST) in order to quantify metabolic signals associated with tissue fate in patients with acute ischaemic stroke. This included addressing robustness for clinical application, and developing quantitative tools that allow exploration of the in-vivo complexity. Tissue-level analyses were performed on a dataset of 12 patients who had been admitted to the John Radcliffe Hospital in Oxford with acute ischaemic stroke and recruited into a clinical imaging study. Further characterisation of signals was performed on stroke models and tissue phantoms. A comparative study of CEST analysis techniques established a model-based approach, Bloch-McConnell model analysis, as the most robust for measuring pH-weighted signals in a clinical setting. Repeatability was improved by isolating non-CEST effects which attenuate signals of interest. The Bloch-McConnell model was developed further to explore whether more biologically-precise quantification of CEST effects was both possible and necessary. The additional model complexity, whilst more reflective of tissue biology, diminished contrast that distinguishes tissue fate, implying the biology is more complex than pH alone. The same model complexity could be used reveal signal patterns associated with tissue outcome that were otherwise obscured by competing CEST processes when observed through simpler models. Improved quantification techniques were demonstrated which were sufficiently robust to be used on clinical data, but also provided insight into the different biological processes at work in ischaemic tissue in the early stages of the disease. The complex array of competing processes in pathological tissue has underscored a need for analysis tools adequate for investigating these effects in the context of human imaging. The trends herein identified at the tissue level support the use of quantitative CEST MRI analysis as a clinical metabolic imaging tool in the investigation of ischaemic stroke.

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Brady, Marcus Evan. « In vivo quantitation of the phosphorus-containing metabolites in rat hind limb by nuclear magnetic resonance spectroscopy during four weeks of creatine depletion induced by feeding beta-guanidinopropionic acid ». Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/6026.

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Mirbahai, Ladan. « Biomarkers of cell stress and cell death detected by proton high resolution magic angle spinning (¹H HR-MAS) nuclear magnetic resonance (NMR) spectroscopy in a rat glioma cell line ». Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/619/.

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Early detection of biomarkers of tumour treatment response improves clinical management, in vivo. Magnetic resonance spectroscopy (MRS) has demonstrated potential for identifying early biomarkers of effective treatment. However, more detailed in vitro studies are required to improve our understanding and facilitate its use. The aim of this study is to determine ¹H high-resolution magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR) biomarkers of cytostasis and cell death in a rat glioma BT4C cell line. Cytostasis and cell death were induced in BT4C cells using cisplatin and substrate free medium, respectively. Cell viability was examined by various techniques. The lipid and metabolite alterations in whole cells were investigated by ¹H HR-MAS NMR. Significant alterations in lipids and metabolites were detected in response to cytostasis or necrosis. NMR lipid accumulation was associated with an increase in cytoplasmic lipid droplets seen prior to morphological and molecular markers of cell death. Significant differences were detected in individual choline containing metabolites (CCMs), emphasising the importance of identifying CCMs separately. Alterations were also detected in lactate, alanine, glycine, glutamate, and succinate levels, suggesting changes in the energy metabolism pathways which may provide novel biomarkers in vivo. ¹H HR-MAS NMR reveals alterations in lipids and metabolites during cytostasis and cell death which may provide early markers of treatment efficacy.

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Yee, Sidney. « Solution-State Proton Nuclear Magnetic Resonance (NMR) Spectroscopic Studies of the Active Site of Myoglobins in Various Ligated States : Models for Macromolecule-Substrate Binding and Advancement of Paramagnetic NMR Techniques ». PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/1253.

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This work focuses on pigmy sperm whale and horse myoglobins (Mbs), which are distinguished by a single heme pocket residue variant in the CD3 position, when the heme iron is in the +3 oxidation state (i.e. the met form). The strategy employed is as follows: (i) assign heme peripheral protons; (ii) assign the amino acid residues from the heme cavity; (iii) assess the dynamics of ligand binding in the active site by means of hydrogen Iability, solvent isotope effects, and heme-insertion isomer trapping, all by NMR methods. The results of these studies portray dynamic solution structure of the Mb ligand binding site, and provide a set of standard parameters for the studies of larger hemoproteins. The findings are also important for understanding protein-ligand interactions in general. My research investigates the mixed spin metazido and metimidazole complexes of Mbs for the following reasons. First, the allosteric properties of hemoglobin arise mainly from the transition between its two possible quaternary structures. This can be studied by paramagnetic NMR because it is one of the most sensitive tools in terms of changes in the molecular and/or electronic structure of the heme. Second, both the N₃- and imidazole (lm-) complexes are good compromises, in terms of sizes, between the small diatomic oxygen or CN⁻ molecules and the bulky phenyl group. Thus, we can determine the influence of ligand size on structural perturbation of the Heme crevice by comparison among the different size groups. Third, the saturation-transfer phenomenon between metMbIm and metMbH₂0 provides a route to assignments in metMbH₂0 by using assignments of metMbIm. This is crucial because metMbH₂0 is the basis of theoretical calculations of the isotropic shift due to axial ligand field in pure high-spin hemoproteins. Finally, the importance of the metMbIm is underscored by the fact that it is a bis-imidazolium complex, which can then serve as a model other bis-histidyl proteins. Most of the heme peripheral resonances of metEqMbIm and metEqMbN₃ were identified by means of two-dimensional NOESY,COSY, and EXSY spectroscopy. The strongly relaxed upfield protons in metMbIm were assigned based on steady-state 1D NOE and T₁ experiments. Based on the results from metMblm in which saturation transfer of one upfield resonance led to two different free ligand peaks, bound Im equilibration was envisioned and proven by the divergence of broad downfield heme methyl peaks into two peaks each, showing distinctive population preference of each isomer. Dicyanoheme probe, as well as hydrogen Iability comparison studies between pigmy sperm whale Mb and horse Mb in the azido and imidazole states, asserts that single variant pocket residue CD3 is crucial in gating the ligand mobility into and out of the active site. The assignments of heme peripheral and upfield resonances enabled the subsequent assignments of some heme pocket amino acid residues. The facile exchange of bound Im with solvent H₂0 lays the ground work for identification of heme pocket residues in metMbH₂0. Furthermore, while deuterated heme previously allowed only assignment of the non-diastereomeric specific heme 2-vinyl β proton, saturation-transfer from horse imidazole Mb affords the specific identification of 2Hᵦt.

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Чередниченко, К. С. « Застосування ЯМР І ЕПР в медицині ». Thesis, Сумський державний університет, 2018. http://essuir.sumdu.edu.ua/handle/123456789/66953.

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MARANI, DEBORA. « Development of hybrid proton-conducting polymers for proton exchange membrane fuel cells ». Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2006. http://hdl.handle.net/2108/202679.

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Lo sviluppo di elettroliti polimerici di nuova generazione è un requisito essenziale per la diffusione su grande scala delle celle a combustibile a membrana polimerica. Tali conduttori protonici devono esibire stabilità morfologica, idrolitica, meccanica ed adeguate proprietà di conducibilità (σ~ 0.01 Scm-1) a temperature superiori a 100 °C per bassi valori d’umidità relativa. Nel presente lavoro sono esplorate diverse strategie per la sintesi di polimeri conduttori ibridi organici-inorganici nanocompositi a partire da polimeri termoplastici aromatici. L'impiego di materiali ibridi permette di sfruttare l'effetto sinergico dovuto alla contemporanea presenza di una componente organica, nel caso specifico polimerica, e di una inorganica, nel caso specifico a base di silicio. Tale effetto sinergico si esplica nella possibilità di modulare e controllare la separazione tra la fase idrolifila ed idrofobica da cui fortemente dipendono le prestazioni dell'elettrolita polimerico. Membrane ibride di classe I a base di polietereterchetone solfonato (S-PEEK) sono così state sintetizzate insieme a numerosi esempi di membrane ibride di classe II a base di S-PEEK e polifenilsolfone solfonato (S-PPSU), contenenti come porzione inorganica atomi di silicio diversamente funzionalizzati. La caratterizzazione dei materiali ha riguardato l’analisi della struttura, le proprietà chimico fisiche ed il comportamento elettrochimico. Risultati molto positivi sono stati ottenuti principalmente con due dei sistemi investigati: una miscela polimerica a base di S-PEEK e S-PPSU sililato ed un polimero interconnesso tramite ponti -SO2- (SOPEEK) e sililato (SOSiPEEK).
The development of new generation polymer electrolytes is an essential prerequisite for grand scale commercialisation on of polymer electrolyte membrane fuel cells. These proton conductors must show good morphological, hydrolytic and mechanical stability and an appropriate conductivity (σ ~ 0.01 Scm-1) at a temperature above 100°C at low relative humidity. In this work, diverse strategies for synthesis of hybrid organic-inorganic proton conducting polymer nanocomposites were explored, based on aromatic thermoplastic polymers. The use of hybrid materials permits exploitation of the synergy between the simultaneously present organic polymeric component and an inorganic silicon-based part. These effects can be explained by the possibility to modulate and to control the separation between hydrophilic and hydrophobic parts, which strongly modify the properties of the electrolytic polymer. Hybrid materials of class I based on sulfonated poly-ether-ether-ketone (S-PEEK) were synthesized as well as several examples of hybrid materials of class II based on SPEEK and poly-phenyl-sulfone sulfonated (S-PPSU) and containing as inorganic part diverse functionalized silicon atoms. These materials were characterized from the point of view of structure, physical and chemical properties and electrochemical behaviour. Very positive results were obtained mainly for two investigated systems: a mixture of S-PEEK and S-PPSU silylated polymer and a cross-linked polymer, through -SO2- bridges (SOPEEK) and silylated (SOSiPEEK).

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Mantovani, Cristina de Faria. « Análise metabolômica (1H RMN) do líquido sinovial de equinos hígidos e acometidos por osteocondrite dissecante ». Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/10/10137/tde-10042014-144355/.

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A osteocondrite dissecante (OCD) é uma das principais doenças que afetam os equinos jovens e uma das condições incluídas nas Doenças Ortopédicas do Desenvolvimento. Por se tratar de importante afecção articular, a OCD pode ser responsabilizada por perdas econômicas substanciais em decorrência da diminuição do desempenho atlético e reprodutivo dos animais acometidos. Sua etiologia é considerada multifatorial sendo associada a fatores nutricionais, endócrinos, genéticos e biomecânicos. A análise dos biomarcadores do líquido sinovial fornece dados fundamentais acerca das alterações representativas de inflamação e danos à cartilagem articular, por isso o monitoramento do ambiente articular caracteriza-se como uma importante ferramenta para o diagnóstico e acompanhamento da progressão da doença. A análise metabolômica por Ressonância Magnética Nuclear de prótons de hidrogênio (1H RMN) é um método de avaliação holístico, simultâneo e em tempo real, dos metabólitos de pequenas moléculas presente no líquido sinovial, capaz de fornecer dados a respeito da progressão da doença, da resposta a tratamentos e de determinar biomarcadores. No presente estudo objetivou-se estabelecer o perfil metabólico global do líquido sinovial de equinos acometidos por OCD, estudar a aplicabilidade da 1H RMN no diagnóstico da OCD e avaliar a possibilidade de distinção entre os líquidos sinoviais de articulações com OCD sintomática e assintomática. A determinação do perfil metabólico do líquido sinovial de equinos hígidos e acometidos por OCD assintomática e sintomática resultou em 32 metabólitos comuns às três condições articulares. Além destes, 2 compostos foram identificados somente nas articulações doentes, sendo eles o propilenoglicol e o composto aromático, porém, não foi possível diferenciar as articulações com OCD assintomática das articulações sintomáticas, pois ambos os grupos apresentavam metabólitos semelhantes e com intensidades similares.. Na comparação entre a intensidade dos espectros, observaram-se aumentos dos metabólitos glicose, glutamina, etanol, leucina, isoleucina, dimetilsulfona, creatina, creatinina, Nacetilglucosamina e N-acetilglutamina e -metil histidina e dos compostos propilenoglicol e composto aromático nas articulações com OCD com relação às hígidas. Dos metabólitos que apresentaram redução na intensidade dos espectros das articulações doentes têm-se o 3- hidroxibutirato e o acetato. Outros metabólitos demonstraram a mesma intensidade de sinal para os três tipos de articulação, sendo eles: piruvato, citrato, metionina, histidina, tirosina, valina, lactato, alanina, glicina, glicerol e fenilalanina. A análise estatística por PCA foi capaz de realizar o agrupamento dos espectros e atribuir a importância do composto aromático na diferenciação entre os animais hígidos e doentes. A análise metabolômica por 1H NMR mostrou-se técnica com alta reprodutibilidade entre as amostras e sensibilidade de detecção dos componentes do líquido sinovial, revelando claras diferenças entre os perfis bioquímicos de articulações hígidas e acometidas por OCD, indicativo das alterações metabólicas que ocorrem com a progressão desta doença, relacionadas principalmente com o processo de degradação cartilagínea. Este estudo salienta o potencial da análise metabolômica em fornecer uma nova perspectiva dos processos bioquímicos envolvidos na progressão da OCD.
Osteochondritis dissecans (OCD) is one of the most common diseases affecting young horses and one of the conditions classified as Developmental Orthopedic Diseases. As an important joint disorder, OCD is held responsible for substantial economic losses in consequence of the decrease in athletic and reproductive performance in affected horses. The condition presents a multifactorial ethiology, related to nutritional, endocrine, genetic and biomechanical factors, although its pathogeny is well established, associated with a disturbance of the process of endochondral ossification. Synovial fluid biomarkers analysis provide data regarding changes representative of inflammation and articular cartilage damage, which is why monitoring the joint cavity is an important tool for diagnosis and assessing disease progression. Proton Nuclear Magnetic Resonance spectroscopy is a holistic, simultaneous and real time approach, of the metabolites present in the synovial fluid, offering the potential to provide data regarding disease progression, response to treatment and to determine disease biomarkers. The aim of the present study was to establish the global metabolic profiling of normal and osteochondritic synovial fluid, to evaluate the applicability of the 1H RMN in the diagnosis of OCD, and to asses possible distinctions between symptomatic and asymptomatic horses. The metabolic profile determination resulted in 32 common metabolites to the three joint conditions. Moreover, 2 compounds were identified exclusively in the diseased joints, namely propylene glycol and aromatic compound, but we were unable to discern between asymptomatic and symptomatic individuals for both groups presented similarities in metabolites as well as their concentrations. When comparing spectral intensities, we observed marked increases in the metabolites glucose, glutamine, ethanol, leucine, isoleucine, dimethyl sulphone, creatine, creatinine, N-acetylglucosamine, N-acetylglutamine and -methyhistidine, besides the compounds propylene glycol and aromatic compound, in the affected joints compared to the healthy ones. Decrease in spectral intensities were related to the metabolites 3-hydroxybutirate and acetate in affected joints. Other metabolites showed no difference in intensities in all joint conditions, those being pyruvato, citrate, methionine, histidine, tyrosine, valine, lactate, alanine, glycine, glycerol and phenylalanine. PCA based statistical analysis was able to group spectra and to ascribe the importance of the aromatic compound in differentiating healthy from diseased joints. 1H RMN spectroscopy showed high reproductability between samples and sensitive in detecting synovial fluid compounds, unveiling clear diferences between the biochemical profiles of healthy and OCD affected joints, thus indicating metabolic alterations occuring with disease progression, related mainly with the cartilage degradation process. This study projects the potential of metabolomics analysis in providing a new perspective of the biochemical processes involved in OCD progression.

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Gerhalter, Teresa. « Characterization of the dystrophic muscle by ²³Na NMR and ¹H NMR T₂ spectrum ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS219/document.

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Le but de la thèse était d'étudier la sensibilité de nouveaux biomarqueurs RMN visant à quantifier les changements pathologiques dans le muscle dystrophique. La dystrophie musculaire (DM) désigne un groupe hétérogène de maladies avec une atrophie musculaire progressive associée à un état de faiblesse. Elle est caractérisée par des degrés variables de nécrose, de régénération, de troubles de l'homéostasie ionique, d'inflammation chronique et finalement par le remplacement des muscles par du tissu fibro-graisseux. Mon objectif était d’évaluer la RMN du ²³Na et les techniques avancées de mesure du temps de relaxation transversal ¹H (T₂) en tant que des biomarqueurs sensibles et précoces. La RMN du ²³Na mesure les concentrations de sodium étroitement contrôlées et donne sa distribution dans le tissu. Cette information peut être utilisée pour évaluer l'homéostasie ionique et l'intégrité cellulaire. Cependant, la concentration in vivo en ²³Na est faible, la RMN du ²³Na souffre donc d'une faible sensibilité par rapport à ¹H. L’altération du T₂ ¹H du muscle, communément interprétée comme un indicateur de l'activité de la maladie, est liée à une variété d’événements non-spécifiques tels que l'œdème, l'inflammation ou la nécrose, qui précèdent le remplacement musculaire par la graisse. Des protocoles comprenant diverses méthodes de RMN du ²³Na et de ¹H T₂ ont été mis en œuvre pour évaluer les tissus musculaires squelettiques sains et dystrophiques sur des modèles animaux et sur patients. Ce travail fournit des preuves que la RMN du ²³Na pourrait offrir un biomarqueur sensible capable de surveiller l'altération spécifique du muscle dystrophique à un stade très précoce
The aim of the thesis is to investigate the sensitivity of novel NMR outcome measures (OM) aiming to quantify pathological changes in the dystrophic muscle. Muscular dystrophy (MD) refers to a heterogeneous group of diseases with progressive muscle wasting and associated weakness characterized by variable degrees of necrosis, regeneration, ionic homeostasis disturbances, chronic inflammation, and, ultimately, resulting in the replacement of muscles by fibro-fatty tissue. My focus was on the evaluation of ²³Na NMR and advanced ¹H transverse relaxation time (T₂) techniques as early, sensitive OM. ²³Na NMR measures the tightly controlled sodium concentrations and distribution in skeletal muscle tissue. This biophysical information can be used to assess ion homeostasis and cell integrity. However, ²³Na NMR suffers from a low sensitivity and in vivo concentration compared to ¹H. Alterations in the muscle ¹H T₂, commonly interpreted as an indicator of disease activity, are linked to a variety of non-specific events like oedema, inflammation, or necrosis that precede the actual muscle replacement by fat. Protocols including different ²³Na NMR and ¹H T₂ methods were implemented to evaluate healthy and dystrophic skeletal muscle tissues of animal models and patients. This work provides evidence that ²³Na NMR could offer a sensitive outcome measure able to monitor specific alteration of the dystrophic muscle at a very early stage

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Koch, Katharina [Verfasser], Jaroslaw [Gutachter] Maciaczyk et Dieter [Gutachter] Willbold. « Analysis of metabolic reprogramming during the enrichment of glioblastoma stem-like cells in glioblastoma via high resolution proton nuclear magnetic resonance (HR 1H-NMR) spectroscopy / Katharina Koch ; Gutachter : Jaroslaw Maciaczyk, Dieter Willbold ». Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2020. http://d-nb.info/1223705242/34.

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Nemeth, Angéline. « Développement et validation de stratégies de quantification lipidique par imagerie et spectroscopie proton à 3T : Application à l’étude de la surnutrition ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI089/document.

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L’imagerie et la spectroscopie par résonance magnétique nucléaire (IRM et SRM) sont des méthodes non-invasives qui ont le potentiel d’estimer in vivo la quantité et la qualité des adiposités abdominales. Le contexte scientifique et clinique de ce manuscrit s’articule autour de l’étude de surnutrition « Poly-Nut » dont l’un des objectifs est d’analyser les évolutions des tissus adipeux (TA) dans une phase rapide de prise de poids. L’originalité et la complexité de cette thèse résident dans le développement, l’adaptation et la comparaison de plusieurs méthodes quantitatives d’IRM et de SRM, pour l’étude du signal lipidique dans un contexte clinique à 3T. La fiabilité et la validation des mesures obtenues in vivo par ces techniques font ici l’objet d’une étude approfondie. Pour l’analyse quantitative du signal de spectroscopie, différentes méthodes existantes ont été comparées à celle développée spécifiquement pour notre étude clinique. L’estimation paramétrique par moindres carrés non linéaires appliquée aux spectres RMN des lipides peut conduire, selon la fonction modèle utilisée, à un problème non linéaire mal posé. Nous montrons alors que l’utilisation d’un modèle simplifié se fondant sur la structure d’une chaine de triglycéride, comme utilisé récemment en imagerie quantitative, constitue une solution valide au regard de l’état de l’art. Ensuite différentes méthodes (IRM, SRM, Dual Energy X-ray absorptiometry, chromatographie en phase gazeuse) ont été utilisées pour caractériser les TA sous-cutanés et viscéraux. Le suivi par IRM du contenu lipidique du foie ainsi que du volume et de la composition en acide gras des TA à partir d’une unique acquisition en multi-écho de gradient est démontré. Enfin des développements expérimentaux menés parallèlement à l’étude clinique sur un imageur préclinique à 4,7T, comparent différentes stratégies d’encodage du déplacement chimique par imagerie et caractérisent des méthodes SRM pour estimer in vivo la proportion d’omégas-3 dans les chaînes d’acides gras
Magnetic resonance imaging and spectroscopy (MRI and MRS) are non-invasive methods that have the potential to estimate in vivo the quantity and the quality of abdominal adipose tissues (AT). The scientific and clinical context of this thesis is based on an overfeeding study entitled "Poly-Nut". One of the main objectives of this study is to analyze changes in adipose tissues in a rapid phase of weight gain. The originality and complexity of this thesis rely in the development, adaptation and comparison of several quantitative methods of MRI and MRS, for the study of lipid signal, in a clinical context, at 3T. The reliability and the validation of the measurements obtained in vivo using these techniques are the main subject of this PhD thesis. For the quantitative analysis of the spectroscopy signal, different existing methods have been compared to those developed specifically for our clinical study. According to the model function used, the nonlinear-least-squares parametric estimation applied to the lipid spectra can lead to an ill-posed nonlinear problem. We demonstrated that the use of a simplified model based on the structure of a triglyceride chain, as recently used in quantitative imaging, was a valid solution regarding the state of the art. Then different methods (MRI, MRS, Dual Energy X-ray absorptiometry, gas chromatography) were used to characterize the subcutaneous and visceral AT. We demonstrated the feasibility of MRI to follow the lipid content in the liver as well as the volume and the fatty acid composition of AT using a single multiple gradient-echo acquisition. Finally, experimental developments were carried out in parallel with the clinical study, on a 4.7T preclinical system, first, to compare different strategies for encoding the chemical shift using imaging and, secondly, to characterize MRS methods for in vivo estimation of the relative proportion of omega-3 among all fatty acids

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Zang, Tuo. « Quantitative characterization of paediatric burn blister fluid ». Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/122968/1/Tuo_Zang_Thesis.pdf.

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Burn injury is a highly traumatic event for any infant or child. The degree of burn severity often determine the treatment operations and the extent of later scar formation, which may require long-term surgical remediation or skin grafting. This investigation quantitatively characterises the biochemical composition of burn blister fluid from paediatric patients using advanced analytical techniques. The correlation of the abundance of proteins and metabolic molecules were explored by statistical and bioinformatics methods. Thus, this study is able to provide a timely and objective measurement that may reflect the burn wound microenvironment and assist clinical diagnosis.

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Bruylants, Gilles. « Etude par calorimétrie à titrage isotherme (ITC) et spectroscopie de résonnance magnétique nucléaire (RMN) des effets de protonation liés à l'interaction entre l'alpha-chymotrypsine et la proflavine / Gilles Bruylants ». Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210977.

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Le nombre de cibles potentielles pour la conception de nouvelles molécules à activité thérapeutique ne cesse de croître. Pour chaque cible, il est nécessaire d’identifier des molécules actives et de les optimiser afin d’atteindre l’affinité et la sélectivité recherchées. Ces nouveaux défis accentuent la nécessité d’améliorer notre compréhension des facteurs qui mènent à la reconnaissance moléculaire entre une drogue potentielle et une macromolécule biologique, et particulièrement des facteurs énergétiques à la base de la stabilisation d’un complexe d’interaction. Dans le cadre de ce travail, nous nous sommes intéressés à l’effet que pouvaient avoir les équilibres de protonation/déprotonation des résidus ionisables d’une protéine sur les paramètres thermodynamiques caractérisant la complexation d’un ligand. Dasns ce but, nous avons étudié l’interaction entre l’α-chymotrypsine et un de ses inhibiteurs compétitifs, la proflavine. Cette protéine est représentative d’un nombre important d’enzymes présentant le même mécanisme catalytique. La compréhension des facteurs qui régissent les équilibres de protonation/déprotonation des résidus ionisables présents dans son site actif ainsi que de l’effet sur ceux-ci de l’interaction avec des ligands est d’une importance primordiale pour le développement d’inhibiteurs plus sélectifs de ces protéases.

Cette étude s’est essentiellement composée de trois volets. (i) La réalisation d’un modèle du complexe d’interaction afin de confronter des données structurales aux données expérimentales recueillies. (ii) L’étude de l’interaction entre l’α-chymotrypsine et la proflavine par spectroscopie de Résonance Magnétique Nucléaire (RMN) afin de mettre en évidence les résidus ionisables dont les équilibres de protonation/déprotonation sont influencés par la complexation du ligand. (iii) L’étude de la thermodynamique de l’interaction par Calorimétrie à Titrage Isotherme (ITC) et spectroscopie d’absorption en fonction de l’état d’ionisation des résidus identifiés par l’étude RMN.

Le modèle du complexe d’interaction entre l’α-chymotrypsine et la proflavine a été réalisé sur base de la structure cristallographique du complexe entre cet inhibiteur et une protéase apparentée à la chymotrypsine, la thrombine. Il ressort de l’analyse du modèle obtenu que la proflavine est profondément enfouie dans le subsite S1 de l’enzyme et présente une très grande complémentarité de surface avec cette poche hydrophobe. Nous avons également pu constater la présence de plusieurs molécules d’eau immobilisées au sein du complexe, et d’une molécule en particulier faisant office de relais de liens-H.

L’étude de l’interaction entre l’α-chymotrypsine et la proflavine par RMN du 1H a été précédée par une étude de l’effet du degré de maturité de l’enzyme sur les interactions liant les différents résidus composant la triade catalytique (Asp102, His57 et Ser195). Lors de l’activation du précurseur inactif de l’enzyme, le chymotrypsinogène, vers la forme mature, l’α-chymotrypsine, il semble en effet que le lien-H entre le NH&949;2 de l’His57 et le Oγ de la Ser195 soit affaibli, contrairement à celui qui relie le NHδ1 de cette même histidine au Oδ1 de l’Asp102. Nous rapportons pour la première fois l’observation de l’influence de la protonation de l’Asp102 sur les déplacements chimiques des protons NHδ1 et NH&949;2 de l’His57. L’étude de l’interaction entre l’α-chymotrypsine et la proflavine par RMN, nous a permis de mettre en évidence l’effet de la complexation du ligand sur l’état d’ionisation des résidus His57 et Asp102 de la triade catalytique, les pKa de ces résidus dans l’enzyme libre valant respectivement 7 et approximativement 4.

Les paramètres thermodynamiques de l’interaction α-chymotrypsine - proflavine et des différents équilibres de protonation/déprotonation qui y sont liés ont été obtenus par spectroscopie d’absorption et ITC. Cette dernière technique constitue un outil précieux pour l’étude d’interactions moléculaires car il s’agit de la seule technique expérimentale permettant la mesure directe de l’enthalpie d’interaction. Lorsque des équilibres de protonation/déprotonation sont thermodynamiquement liés à l’interaction, il s’agit également de la seule technique permettant la quantification de ces effets. En mesurant la constante d’affinité et l’enthalpie d’interaction observées à différents pH et dans différents tampons, nous avons pu, sur base du modèle obtenu par RMN, déterminer les paramètres thermodynamiques intrinsèques des différents équilibres.

La corrélation entre les données thermodynamiques obtenues par ITC et spectroscopie d’absorption et les données structurales obtenues par RMN et sur base de l’analyse du modèle du complexe d’interaction, nous a permis de rationaliser les facteurs à la base de l’interaction préférentielle de l’inhibiteur avec une des formes de l’enzyme. L’interaction entre l’α-chymotrypsine et la proflavine est la plus favorable lorsqu’à la fois l’His57 et l’Asp102 sont déprotonnés. Cette interaction est caractérisée par un terme enthalpique favorable et un terme entropique légèrement défavorable. Ce dernier terme s’expliquerait en partie par l’immobilisation dans le site d’interaction de plusieurs molécules d’eau. L’affinité entre l’α-chymotrypsine et la proflavine diminue lorsque l’His57 se protonne. La répulsion électrostatique entre les charges positives de la proflavine et de l’His57 est vraisemblablement un des facteurs permettant d’expliquer cette diminution de la constante d’affinité. Nous n’avons pu mettre en évidence d’interaction entre ces deux molécules dès lors que l’Asp102 est protonné, malgré que ce résidu soit situé relativement loin de la proflavine dans le complexe. Il s’agit donc d’un effet indirect, probablement relayé par l’His57. Tant que l’Asp102 est déprotonné, sa charge négative compenserait la charge positive de l’His57 et réduirait la répulsion électrostatique avec la proflavine, ce qui n’est plus le cas lorsque l’aspartate se protonne.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished

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Rodrigues, Marcos. « Legacy phosphorus in Brazilian agriculture and cover crops contribution to enhance this nutrient bioavailability in tropical Oxisols ». Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-29062018-091614/.

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Phosphorus (P) one of the essential elements to plants and animals, is a non-renewable resource and accuatlly high demanded in agriculture. The World\'s population growth and future estimatives on food demands raises the question about the sustainability of the current agriculture systems, speccially concerns about the low P use efficiency in agroecosystems. Brazilian agriculture requires high P inputs and many researches has been developed to increase the crops yield and, consequently, food production efficiency. However, this development was achieved at the high costs of mineral fertilisers (specially P) and long-term perspectives about the costs of the intensification in the tropical agriculture is accuattly in debate. In this conxtext, in the present thesis chapter two we evaluated the evolution of the Brazilian cropland basis and P demands, quantifying the Brazil P Legacy and, based on scenarios involving the cropland area and yield expansion, we estimated the future (up to 2050) Legacy P and P fertilisers demand. We also estimated the potential aleviation that could be achieved in the mineral fertilizers consumption by utilisation and improvements on manure P recycling. Alternatively, considering the systems intensification and its effects on P availability, we proposed alternative scenarios to promote the Legacy P utilisation in Brazil\'s improved agriculture systems to grant the agriculture expansion without huge increments on the national P fertilisers consumption. A worldwide recognized advance in Brazilian agriculture is the Cerrado, where large cropland areas accually are cultivated twice a year, improving the food and fiber production without any additional disturbance of natural ecossystems. In this context, no-tillage (NT) agriculture has been widely used and, as consequence, soil fertility has been improved, which could be also farorable to the P availability, when rotation with crop species with P mobilization mechanisms are introduced, such as cover crops utilisation. However, the effects of these improved rotated systems on P bioavailability in long-term in tropical soils remains uncert in the literature and was our objective in the chapter three, where is described a study envolving the evaluation of long-term changes on P fractions in tropical Oxisols, from two long-term field trials involving tillage systems (NT and conventional tillage, CT) and cover crops (millet, brachiaria, maize and control, fallow). The long-term cultivation generated large amounts of legacy P in the soil and with the brachiaria introduction as cover crop, more P was recycled in the topsoil and labile P and all the organic P fractions increased. Based on the cover crop effects, we proposed that the bioavailability of the legacy P could be represented by the P extracted by the labile fractions + moderately labile P fractions. In the chapter four, we used other techniques actually widely applied to P speciation, and we applied in tropical soils affected by the native Cerrado conversion into NT and CT agriculture. A multiple approach to identify and quantify the P forms in tropical soils were proposed by the utilisation of Hedley\'s fractionation togheter with P K-edge XANES for P-bindings into inorganic soil matrix and liquid 31P-NMR spectroscopy to complement the organic P species in tropical soils.
Fósforo (P), um dos elementos essenciais às plantas e animais, é um recurso não-renovável e altamente demandado na agricultura atualmente. O crescimento da população mundial e as estimativas futuras da demanda de alimentos aumentam os questionamentos sobre a sustentabilidade dos sistemas agrícolas atuais, especialmente no que se refere a baixa eficiência no uso do P na agricultura. A agricultura brasileira requer altas quantidades de P e muitas pesquisas tem sido desenvolvidas para aumentar a produtividades das culturas e, conseequentemente, a eficiencia da produção de alimentos. Entretanto, este desenvolvimento tem sido alcançado a altos custos com uso de fertilizantes minerais (sobretudo P) e as perspectivas de longo prazo sobre os custos da intensificação da agricultura tropical estão atualmente em debate. Nesse contexto, no capítulo dois da presente tese avaliamos a evolução da área cultivada no Brasil e das demandas de P, quantificando o legado do P no Brasil e, baseado em cenários envolvendo a expansão da área cultivada e da produtividade, estimamos o futuro (até 2050) legado de P e as demandas por fertilizantes fosfatados. Ainda estimamos a potencial redução no consumo de fertilizantes fosfatados que pode ser alcançada pela utilização e melhorias na reciclagem do P oriundo de dejetos. Alternativamente, considerando a intensificação dos sistemas e seus efeitos na disponibilidade de P, propusemos cenários alternativos visando a utilização do \"Legacy P\" em sistemas agrícolas melhorados para garantir a expansão agrícola sem drásticos incrementos no consumo nacional de fertilizantes fosfatados. Um avanço internacionalmente reconhecido na agricultura Brasileira é o Cerrado, onde extensas áreas agrícolas são cultivadas duas vezes ao ano, incrementando assim a produção de alimentos e fibras sem qualquer custo aos ecossistemas naturais. Nesse contexto, a agricultura sob plantio direto (PD) tem sido amplamente difundida e, como consequencia, a fertilidade dos solos tem-se elevado, o que pode também favorecer a disponibilidade de P, quando são introduzidas rotações com espécies de plantas que apresentam mecanismos de mobilização do P, como o uso de plantas de cobertura. Entretanto, os efeitos desses sistemas melhorados de rotação na biodisponibilidade de P em solos tropicais no longo prazo permanecem incertos na literatura e foram objeto de estudo no capítulo três, onde está descrito um estudo envolvendo a avaliação das mudanças de longo-prazo nas frações de P em Latossolos, oriundos de dois experimentos de campo de longa duração no Cerrado, envolvendo a avaliação de sistemas de preparo (PD e preparo convencional, PC) e plantas de cobertura (milheto, braquiária milho e um controle, apenas pousio). O cultivo por longo tempo resultou em grandes quantididades de \"Legacy P\" acumulado no solo e, com o uso de braquiária como cultura de cobertura, maior quantidade de P foi reciclado para as camadas superiores do solo e as frações de P lábil e todas as frações organicas aumentaram. Baseado nos efeitos das plantas de cobertura, sugerimos que a biodisponibilidade do \"Legacy P\" pode ser representada pelo P extraído nas frações lábeis + o P de frações moderadamente lábeis. No capítulo quatro, utilizamos outras técincas atualmente difundidas para a especiação de P, aplicando-as em solos tropicais influenciados pela conversão do Cerrado nativo em agricultura sob PD e PC. Uma abordagem múltipla para identificação e quantificação de formas de P em solos tropicais foi proposta através da utilização do fracionamento de P proposto por Hedley em conjunto com a especiação de P por XANES da borda K do P para identificação de ligação do P a matrix inorgânica do solo, e espectroscopia de ressonância magnética nuclear (NMR) para complementação da identificação de espécies orgânicas de P em solos tropicais.

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Oliveira, Clovisson Menotti Boeira de. « Quantificação de formas de fósforo em diferentes tipos de solo e usos em Santa Catarina ». Universidade do Estado de Santa Catarina, 2014. http://tede.udesc.br/handle/handle/600.

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The total content of phosphorus (P) is distributed in the soil forms with different degrees of lability, being the distribution of the forms affected by type soils and soil manegement. The work consisted of three studies, being that the first study quantified the stock of the forms of inorganic and organic P in the surface horizon and in 42 profiles soil of six orders in the Santa Catarina State. After collection, the samples were subjected to chemical fractionation of P Hedley. The soils most weathered had higher stock of P total, while the soils less weathered showed higher levels of labile organic P. In the second study was conducted fractionation analysis of P and P nuclear magnetic resonance (NMR) in soil agroecosystems with high organic matter content. The areas were evaluated in apple orchard, native grass and pine plantation. The results of chemical fractionation and NMR of P, showed that the conversion of natural ecosystems to areas cultivated altered the distribution of P forms in soil, where the fractions organic were reduced in culture without the addition of phosphate fertilizer systems. The third study involved the assessment of forms of P in soils with different clay contents that subjected the applications of liquid swine manure. Soil samples were collected in three regions of Santa Catarina State and subjected to chemical fractionation of P. The results showed that the addition of liquid swine manure for long term increased the content of all forms of P evaluated by fractionation, mainly in inorganic forms, with more accumulated in the topsoil. In soils with sandy texture there accumulation of labile P, and in soils clay there accumulation the of forms lower lability
O conteúdo total de fósforo (P) do solo é distribuido em formas com diferentes graus de labilidade. A distribuição das formas de P podem ser afetadas pelo tipo de solo e o manejo adotado durante seu uso. O trabalho foi composto de três estudos. O primeiro estudo quantificou o estoque das formas de P inorgânicas e orgânicas no horizonte superficial e nos perfis de 42 solos de seis ordens no Estado de Santa Catarina (SC). Após a coleta, as amostras foram submetidas ao fracionamento químico de P de Hedley. No segundo estudo foi realizado o fracionamento químico de P e análise de ressonância magnética nuclear de P (RMN) em amostras de solo de áreas de pomar de maçieira, campo nativo e florestamento de pinus com alto teor de matéria orgânica. O terceiro estudo consistiu na avaliação das formas de P em solos com diferentes teores de argila que foram submetidos a aplicações de dejetos líquidos de suínos. As amostras de solo foram coletadas em três regiões do Estado de SC e submetidas ao fracionamento químico de P. No estudo 1 os solos mais intemperizados apresentaram maiores estoque de P total enquanto os solos menos intemperizados apresentaram maiores teores de P lábil e P orgânico. No segundo estudo os resultados do fracionamento químico e RMN de P mostraram que a conversão de ecossistemas naturais em áreas cultivadas alterou a distribuição das formas de P no solo, onde as frações orgânicas foram reduzidas em sistemas de cultivo sem a adição de fertilizantes fosfatados. Os resultados do terceiro estudo mostraram que a adição de dejetos líquidos de suínos por longo prazo aumentou o teor em todas as formas de P avaliadas pelo fracionamento, principalmente em formas inorgânicas, sendo mais acumulado na camada superficial do solo. Nos solos com textura arenosa houve acúmulo de P principalmente nas frações lábeis e em solos de textura argilosa houve acúmulo de P principalmente em formas de menor labilidade

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Bonnet, Marie. « Analyse multi-échelle du comportement hygromécanique du bois : Mise en évidence par relaxométrie du proton et mesures de champs volumiques de l'influence de l'hétérogénéité au sein du cerne ». Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1042/document.

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La variabilité des propriétés du bois ainsi que son hygroscopicité pourraient être un frein à son utilisation dans la construction, même s’il peut être considéré comme un matériau de choix dans le contexte environnemental et économique actuel. Il est donc primordial de mieux comprendre les origines physiques du comportement du bois pour être capable d’améliorer la prédiction de ses propriétés, et pouvoir ainsi le rendre plus compétitif par rapport aux autres matériaux de construction. Le comportement hygromécanique du bois, caractérisé par des variations dimensionnelles en présence de variations d’hygrométrie, est particulièrement difficile à prédire, du fait de sa microstructure multi-échelle et de ses interactions complexes avec l’eau.Dans ce contexte, la thèse vise à comprendre et enrichir les relations entre la microstructure du bois, ses propriétés de sorption et son comportement hygromécanique, en étudiant l’influence de l’hétérogénéité de l’accroissement annuel (cerne), constitué de bois initial et de bois final dont la structure et les propriétés présentent de nombreuses différences. Cette étude est menée sur du Douglas (Pseudotsuga menziesii (Mirb.) Franco), actuellement référencé comme un matériau de structure intéressant. Des outils de caractérisation avancés sont utilisés : la Résonance Magnétique Nucléaire (RMN) du proton pour caractériser les mécanismes de sorption ; la corrélation d’images volumiques (DVC) pour mesurer les champs de déformations à partir d’images 3D de microtomographie aux rayons X (µTRX), donnant aussi accès à la densité locale du bois.Après une introduction sur le matériau bois et un état de l’art sur son comportement hygromécanique, une caractérisation préliminaire de la microstructure (angle des microfibrilles, largeur de cerne, densité) et du comportement hygromécanique d’échantillons de bois initial et de bois final prélevés dans différents cernes est menée. Une forte anisotropie du bois initial est mise en évidence en opposition au comportement isotrope transverse du bois final. Les déformations suivant la direction des fibres présentent aussi de fortes non-linéarités peu discutées dans la littérature. Une discussion sur la variabilité des propriétés est par ailleurs engagée, ainsi que sur les relations structure-propriétés à l’échelle macroscopique.L’origine des différences de comportement hygromécanique entre le bois initial et le bois final est tout d’abord recherchée au niveau des mécanismes de sorption, au travers une étude de relaxométrie RMN du proton en 2D (cartes T1-T2). Deux types d’eau liée situés dans des environnements distincts sont mis en évidence et leur isotherme de sorption diffère dans les deux types de bois. Une hypothèse sur leur localisation dans la paroi cellulaire est proposée, puis une modélisation simplifiée 2D est effectuée pour évaluer leur impact respectif sur le comportement hygromécanique du bois initial et du bois final, en particulier dans la direction des fibres.Enfin, les champs de déformations locaux et globaux sont étudiés en analysant par DVC des images de µTRX de bois initial et de bois final soumis à différentes sollicitations hydriques. Le couplage entre ces deux matériaux est aussi étudié pour évaluer leurs interactions et comprendre le comportement du bois à l’échelle du cerne. Un protocole de DVC adapté aux images de bois est proposé. Les comportements hygromécaniques du bois initial, du bois final et du cerne sont comparés. A l’échelle locale, des hétérogénéités du champ de déformations sont mises en évidence et corrélées à la densité locale. Leur effet sur le comportement du cerne et sur la courbure des échantillons induite par le chargement hydrique est analysé. Une modélisation 3D par éléments finis, tenant compte des gradients locaux de propriétés, vient enfin compléter cette étude pour améliorer la compréhension des interactions mécaniques entre le bois initial et le bois final
Wood has highly variable properties and is also hygroscopic. These characteristics may restrict its use in construction even if it can be considered as a material of choice with the current environmental and economical concerns. Therefore, it is essential to better understand the physical origins of the behavior of wood in order to improve the prediction of its properties, and making it competitive with respect to other building materials. Dimensional changes of wood appear when it is subjected to relative humidity variations. This hygromechanical behavior is particularly difficult to predict because of the multiscale structure of wood and its complex interactions with water.In this context, the present work aims to understand and enrich relationships between microstructure, sorption properties and hygromechanical behavior of wood. More specifically, it is focused on the influence of the growth-ring heterogeneity, constituted of earlywood and latewood which have different structures and properties. The study is performed on Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), which is a species of significant interest for structural applications. Advanced characterization tools are used: proton Nuclear Magnetic Resonance (NMR) to characterize sorption mechanisms; digital volume correlation (DVC) to measure deformation fields from X-Ray microtomography 3D images (XRµT), also providing local density of wood.At first wood properties and its hygromechanical behavior are described through a literature overview. Preliminary microstructural (microfibril angle, growth-ring width, density) and hygromechanical behavior characterizations of earlywood and latewood samples with different cambium age are performed. Earlywood reveals a strong anisotropic behavior compared to latewood which is isotropic in the transversal plane. Moreover, strains along the fiber direction nonlinearly evolve with moisture content. This phenomenon has been hardly reported and studied in the literature. Discussions on variability of properties and on relationships between structure and properties are also initiated.Sorption mechanisms are then studied by 2D NMR relaxometry (T1-T2 correlation spectra) in order to investigate differences between earlywood and latewood hygromechanical behaviors. Two types of bound water located in distinct environments are highlighted and their sorption isotherms are shown to be different in the two types of wood. A hypothesis on their location in the cell-wall is proposed and a simple 2D model is developed to evaluate their respective effect on the hygromechanical behavior of earlywood and latewood, especially in the fiber direction.Furthermore, local and global strains fields are studied using DVC from XRµT images of earlywood and latewood subjected to relative humidity variations. The coupling of these two materials is also investigated in order to evaluate their mechanical interactions and to understand the behavior at the growth-ring scale. A specific DVC procedure is developed for images of wood. The hygromechanical behaviors of earlywood, latewood and a growth-ring are compared. At the local scale, strains fields heterogeneities are highlighted and correlated to the local density. Their effect on the growth-ring behavior and the samples curvature is analyzed. A 3D finite elements model which takes into account local gradients of properties is finally developed to better understand earlywood-latewood mechanical interactions

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