Arctic soils contain a large fraction of our planets terrestrial carbon (C) pool. When tundra soils become warmer and permafrost thaws, non-native geoengineering earthworms can enter these soils and ingest organic matter accumulated over long timescales. Previous studies have found that earthworms increase mineralization rates of soil organic matter into carbon dioxide (CO2) when introduced. Yet, this initial mineralization boost seems transient with time and it has been hypothesized that earthworms stimulate the formation of persistent C forms. In this study, I investigated how non-native, geoengineering earthworms affected the relative proportions of seven carbon forms in the O and A1 horizon of tundra soil and if their effect induced a change in pH. I used Nuclear Magnetic Resonance (NMR) spectroscopy to understand what happens to soil carbon compounds in two different tundra vegetation types (heath and meadow), that had been subjected to earthworm treatment for three summers. I found that O-aromatic C increased from 7.22% ± 0.24 (mean ± stderr) in the meadow soil lacking earthworms to 8.98% ± 0.30 in the meadow exposed to earthworms, and that aromatic C increased from 8.71% ± 0.23 to 9.93% ± 0.25. In similar, the result suggested that alkyl C decreased in this vegetation type from 20.43% ± 0.38 to 18.70% ± 0.25 due to earthworm activities. I found no effect on the chemical properties in the heath. I conclude that geoengineering earthworms affect the two vegetation types differently and that earthworms seem to enhance the accumulation of recalcitrant aromatic C forms.

We report a systematic investigation of the local electronic, magnetic, and superconducting properties of the new iron-based high temperature superconductor Ba(Fe(1-x)Co(x)As(2) (x = 0, 0.02 , 0.04, 0.082) through the measurement of 75As and 59Co NMR (Nuclear Magnetic Resonance) lineshapes, Knight shift (K), and spinlattice relaxation rate ( 1/ T1) . The 75As NMR lineshape of the undoped parent compound splits into two sets due to discrete values of hyperfine magnetic field B(c)(hf)= ±1.32 Tesla below the magnetic ordering temperature to the SDW (Spin Density Wave) state, TSDW. In contrast, for lightly Co doped samples with x=0.02 and 0.04, the 75As and 59Co lineshapes become broad and featureless below Tsnw , indicating that the ground state is no longer the commensurate SDW ordered state. The observed lineshape is consistent with an incommensurate SDW ordered state, or a commensurate state with large distribution of hyperfine field Bhf. In the optimally doped superconductor with x = 0.082 (Tc = 22 K) , we observe two types of As sites and three types of Co sites, respectively, as expected from a binomial distribution of Co dopants. We found no evidence for induced localized moments in the vicinity of Co dopants. This finding is in remarkable contrast with the case of Zn or Ni doped high Tc cuprates, and suggests that the fundamental physics of iron-based superconductors is different from that of cu prates. The temperature dependences of 75,59K and 75,59 (1/T1T) at both 75As and 59Co sites show that Ba(Fe(1-x)Co(x))(2)As(2) exhibits spin pseudo-gap like behavior down to ~100 K for a broad Co concentration range. Below ~100 K , we observe the enhancement of residual antiferromagnetic spin fluctuations associated with inter-band spin excitations between the hole and electron Fermi surfaces even for x= 0.082. This effect is suppressed in the overdoped sample with x= 0.099, and Tc decreases. Therefore, we suggest that antiferromagnetic spin fluctuations play a crucial role in the superconducting mechanism of Ba(Fe(1-x)Co(x))(2)As(2) . We also demonstrate that the superconductivity arises from a novel electronic state with spin susceptibility Xs ~ constant and in-plane resistivity P(ab)~T, which is not consistent with canonical Fermi-liquid behavior. / Thesis / Doctor of Philosophy (PhD)

<p>This work studies the effect of dopamine (DA) and adenosine triphosphate (ATP) on lipid membranes using a number of complementary experimental methods. These methods include Dynamic Light Scattering to measure electrostatic surface potentials, solid-state Nuclear Magnetic Resonance to measure the degree of lipid acyl chain order, Electron Paramagnetic Resonance to measure changes in membrane viscosity, and X-ray diffuse scattering to measure structural and material parameters of lipid bilayers. It is shown that both DA and ATP have a measurable affinity to the lipid-water interface even in the absence of specialized biological receptors. These results are important for understanding the function of DA and ATP in cellular processes.</p>

No description available.

No description available.

<p>Exchange proteins directly activated by cAMP (EPAC) are guanine nucleotide exchange factors for the small GTPases, Rap1 and Rap2. The central regulatory module of EPAC is a cAMP binding domain (CBD), which in the absence of cAMP provides auto-inhibition of the catalytic guanine nucleotide exchange activity. Binding of the allosteric effector, cAMP, removes the auto-inhibition exerted by the CBD of EPAC. Herein, we investigate through NMR spectroscopy the structural and dynamical basis of auto-inhibition and cAMP-dependent allosteric activation in the CBD of EPAC. Specifically, the work described in this dissertation proposes novel methods that utilize NMR chemical shifts to define the network of residues that mediates long-range intra-molecular signalling, <em>i.e.</em> the chemical shift covariance analysis (CHESCA) and the chemical shift projection analysis (CHESPA). Using CHESCA as explained in Chapter 2, we identified an allosteric network that bridges the sites of cAMP-binding and cAMP-dependent structural changes to those of cAMP-dependent dynamical changes, which are critical for the release of auto-inhibition. The CHESCA results therefore rationalize how cAMP leads to activation through modulation of both structure and dynamics. In order to dissect the determinants of auto-inhibition in the absence of cAMP, several mutations along the signaling pathways identified by CHESCA were implemented and their effect on the auto-inhibitory conformational equilibrium of the apo-CBD was assessed through CHESPA, as outlined in Chapters 3 and 4. Overall, we have shown how CHESCA and CHESPA provide unprecedented insight into the allosteric networks underlying auto-inhibition and cAMP dependent activation in the CBD of EPAC. In addition, the methods employed here to map EPAC allostery are likely to be generally applicable to other systems.</p> / Doctor of Philosophy (PhD)

No description available.

[ES] Las zeolitas son sólidos cristalinos microporosos con canales y cavidades de tamaños moleculares, que pueden presentar gran variedad de estructuras y composición química, lo que las hace útiles como catalizadores en gran variedad de procesos químicos. En la presente tesis doctoral, se han estudiado en profundidad las propiedades estructurales de zeolitas con estructura RTH y MFI pura sílice y aluminosilicato, utilizando fundamentalmente la técnica de resonancia magnética nuclear (RMN). Además, se han estudiado catalizadores zeolíticos tipo Ag-FAU para una reacción de interés medioambiental como la Oxidación Catalítica Selectiva de NH3 (NH3-SCO). En esta tesis, las zeolitas tipo MFI y RTH se han sintetizado utilizando tetraalquilamonios y tetralquilfosfonios como ADEs y HF como agente mineralizante. Los resultados referentes a la zeolita MFI pura sílice indican que el ADE utilizado afecta al orden local de la estructura, a la distribución de flúor y a la formación de defectos de red. En la síntesis de la zeolita tipo MFI aluminosilicato, se ha observado que el ADE utilizado y la relación Si/Al produce diferencias significativas en los espectros de RMN de 27Al, que se atribuyen normalmente a variaciones en la distribución del aluminio en diferentes sitios cristalográficos. Sin embargo, las diferencias desaparecen después de la calcinación, lo que cuestiona esta interpretación. La zeolita tipo RTH pura sílice se ha sintetizado con el catión iPr3MeP+ variando los tiempos y la temperatura de síntesis. Estos parámetros afectan tanto a la estructura local de los átomos de silicio como a la distribución del flúor en la zeolita. Se ha observado también la transformación de la estructura tipo STF a RTH durante la síntesis. La modificación con fósforo de zeolitas tipo aluminosilicato, que normalmente se realiza por impregnación, estabiliza el aluminio de la red en condiciones hidrotermales, lo que tiene importantes implicaciones en las aplicaciones industriales. En esta tesis, se han incorporado cantidades variables de fósforo en las zeolitas MFI y RTH aluminosilicatos utilizando mezclas de alquilamonios y alquilfosfonios como ADEs. Los resultados indican que el fósforo permanece en las zeolitas después de la calcinación estabilizando el aluminio de red. La caracterización detallada de las muestras ha permitido proponer las especies Al-P formadas, responsables de la estabilización de la red. Además, las zeolitas P-RTH y P-ZSM-5 se han utilizado como catalizadores para la reacción de metanol a olefinas. Por último, se ha estudiado la influencia de diferentes parámetros como la relación Ag/Al, la presencia de cationes alcalinos o la acidez Brønsted en zeolitas Ag-FAU y sus repercusiones en el comportamiento catalítico para la reacción de NH3-SCO. Los catalizadores se han caracterizado exhaustivamente antes, durante y después de la reacción, observándose que las partículas de plata metálica, que son los centros activos, se re-dispersan y oxidan en condiciones de reacción. / [CA] Les zeolites són sòlids cristal·lins i microporosos amb canals i cavitats de dimensions moleculars, que poden presentar una gran varietat d' estructures i composició química, això les fa molt interessants com a catalitzadors en un ampli nombre de reaccions químiques. En la present tesi doctoral, s'ha estudiat en profunditat les propietats estructurals de les zeolites amb estructura RTH i MFI pura sílice i amb sílici i alumini, utilitzant fonamentalment la tècnica de ressonància magnètica nuclear. A més, s'han estudiat catalitzadors basats en Ag-FAU zeolites per a una reacció d'interès mediambiental com es l' Oxidació Catalítica Selectiva d'amoníac (NH3-SCO). En aquesta tesi, les zeolites tipus MFI i RTH s'han sintetitzat amb l'ús de cations tetraalquilamoni i tetraalquilfosfoni i HF com agent mineralitzant. Els resultats obtinguts per a la zeolita MFI pura sílice mostren com l'ADE utilitzat juga un paper important en l'ordre local dels àtoms de silici, la distribució de fluor i la formació de defectes zeolítics. En la síntesi de la zeolita MFI aluminosilicat, s'ha observat que la natura dels ADEs i la relació Si/Al produeix diferències significatives a l'espectre de 27Al de RMN, normalment associades a una localització diferent de l'alumini. Però eixes diferències desapareixen amb la calcinació de les zeolites. La zeolita RTH pura sílice ha sigut sintetitzada amb el catió iPr3MeP+ modificant les condicions de síntesi (temps i temperatura). Els resultats mostren que l'ordre local dels àtoms de l' estructura zeolítica o la distribució de fluor es veu influenciada per aquests paràmetres. També s'ha pogut observar que en determinades condicions de síntesi es produeix la transformació de la estructura tipus STF en RTH en el procés de síntesi. La modificació amb fòsfor de les zeolites que contenen alumini, que normalment es realitza per impregnació, estabilitza l'alumini de l'estructura zeolítica en condicions hidrotermals, la qual cosa té una importància crucial per a les aplicacions industrials d'aquests materials. En aquesta tesi, s'han incorporat quantitats creixents de fòsfor a les zeolites RTH i MFI aluminosilicats utilitzant mescles d'alquilamonis i alquilfosfonis com ADEs. Els resultats indiquen que tot el fòsfor introduït roman a la zeolita després de la calcinació, estabilitzant l'alumini en la zeolita. La caracterització dels materials ha permès proposar les espècies Al-P formades a l'interior de les zeolites, que són les responsables de l'alta estabilitat hidrotermal de l'alumini a l'estructura zeolítica. A més, les zeolites RTH i MFI modificades amb fòsfor han sigut utilitzades com a catalitzadors en la reacció de metanol a olefines (MTO). Per últim, s'ha estudiat la influència de alguns paràmetres com la relació Ag/Al, la presència de cations alcalins o centres àcids de BrØnsted als catalitzadors tipus Ag-FAU i les seues repercussions per a la reacció de NH3-SCO. Els catalitzadors s'han caracteritzat abans, durant i després de la reacció i els resultats mostren que les nanopartícules de plata metàl·lica són el centre actiu de la reacció i que es re-dispersen i oxiden en condicions de reacció. / [EN] Zeolites are microporous crystalline solids containing channels and cavities of molecular dimensions, which can present different structures and chemical composition, making them especially interesting as catalysts in several chemical processes. In this doctoral thesis, we have deeply studied the structural properties of pure silica and aluminosilicate RTH- and MFI-type zeolites mainly using nuclear magnetic resonance (NMR) spectroscopy. Moreover, we have studied the properties of Ag-FAU zeolites as catalysts for the selective catalytic oxidation of ammonia (NH3-SCO), which is a reaction of great interest for the environmental. Here, zeolites RTH and MFI have been synthesized in the presence of tetraalkilammonium and phosphonium cations as OSDAs and in fluoride media. The results obtained for the MFI zeolites show that the OSDAs has a strong influence on the local order of the framework, the fluorine distribution and the formation of siloxy/silanol defects. The results for the aluminosilicate MFI-type (ZSM-5) zeolite show that the shape of the 27Al NMR spectrum changes depending on both the OSDA and the Si/Al ratio, which is usually attributed to a different Al sitting in the zeolite. These differences disappear after the calcination of the zeolites, questioning the classical interpretation. RTH-type zeolite has been synthesized using the iPr3MeP+ cation varying the synthesis conditions (time and temperature). The results show that these parameters affect the local environment of the silicon atoms and the fluorine distribution inside the zeolite. It has been also possible to identify the zeolitic transformation of the STF structure into the RTH-type during the synthesis. The introduction of phosphorus in the aluminosilicate zeolites, usually done by the impregnation procedure, stabilizes the framework aluminium under steam conditions, with important implications in industrial processes. In this doctoral thesis, we have varied the P/Al molar ratios using the dual-template synthesis technique. All phosphorus from the P-based OSDAs remain inside the zeolites after the thermal/hydrothermal treatments. The exhaustive characterization of the materials has allowed us to propose the Al-P species formed inside the zeolites responsible of the aluminium stabilization. Moreover, some phosphorus modified RTH and MFI zeolites were tested in the methanol to olefins (MTO) reaction. Finally, we have studied the influence of different parameters such as the Ag/Al ratio, the alkali cations or the presence of BrØnsted acid sites in the Ag-FAU zeolites and its implications in the NH3-SCO reaction. The Ag-FAU catalysts have been deeply characterized before, during and after the catalytic tests, identifying the Ag0 specie, which is the active centre for this reaction, and that metal particles are re-dispersed and oxidized under reaction conditions. / Martínez Ortigosa, J. (2021). Caracterización estructural de zeolitas por Resonancia Magnetica Nuclear y su aplicación como catalizadores [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/165576

While Li-ion batteries (LIBs) are the prevailing electrochemical energy storage technology, development of batteries using earth abundant alkali metals (e.g., Na and K) is necessary to alleviate LIB supply chain concerns. K-ion batteries (KIBs) offer a compelling advantage over Na via their compatibility with commercialized graphite anodes, and therefore may be more readily adopted within existing battery production lines. K-ions present some inherent advantages as well, such as rapid diffusion and low energy barriers to desolvation in the battery electrolyte that may enable fast charging. Presently, research on KIBs is in early stages and it is unclear if the same battery design principles produced by decades of study on LIBs apply to KIBs. Here, I examine structure-performance relationships in KIB anodes and electrolytes to propose broad design rules. In the first chapter, I summarize the motivations and prominent advancements in materials used for KIBs, providing commentary on the direction of the field. I begin by summarizing present concerns over materials criticality facing LIBs and how KIBs address these concerns but do not necessarily achieve lower costs. I continue with a summary of popular materials choices for KIB anodes, cathodes, and electrolytes. I place particular emphasis on the discovery and development of graphite anodes and the advantages of using a weak Lewis acid such as K-ions in batteries. Finally, I discuss the challenges presented by using highly reactive K metal anodes in research. In the second chapter, I examine the mechanisms of potassiation/depotassiation of two high-capacity tin phosphide anodes, Sn₄P₃ and SnP₃, and discuss possible failure modes. Ex situ 31P and 119Sn solid-state nuclear magnetic resonance (NMR) analyses reveal that both Sn₄P₃ and SnP₃ exhibit phase separation of elemental P and the formation of KSnP-type environments (which are predicted to be stable based on DFT calculations) during potassiation, while only Sn₄P₃ produces metallic Sn as a byproduct. In both anode materials, K reacts with elemental P to form K-rich compounds containing isolated P sites that resemble K₃P, but K does not alloy with Sn during potassiation of Sn₄P₃. During charge, K is only fully removed from the K3P-type structures, suggesting that the formation of ternary regions in the anode and phase separation contribute to capacity loss upon reaction of K with tin phosphides. The third chapter addresses the use of fluorinated electrolyte additives in KIBs. Fluoroethylene carbonate (FEC) is a well-known additive used in Li-ion electrolytes, because the products of its sacrificial decomposition aid in forming a stable solid electrolyte interphase (SEI) on the anode surface. Here, we show that FEC addition to KIBs containing hard carbon anodes results in a dramatic decrease in capacity and cell failure. Using a combination of 19F solid-state NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS), we show that FEC decomposes during galvanostatic cycling to form insoluble KF and K₂CO₃ on the anode surface, which correlates with increased interfacial resistance in the cell. Our results strongly suggest KIB performance is sensitive to accumulation of an inorganic SEI, likely due to poor K transport in these compounds. The fourth chapter presents a nonflammable electrolyte mixture for use in KIBs. In this report, we show that a low-concentration (1 M) KPF6 electrolyte combining ethylene carbonate (EC), propylene carbonate (PC), and triethyl phosphate (TEP) is nonflammable, retains high ionic conductivity, and is compatible with graphite. Notably, we then show that this electrolyte is only usable in KIBs; the analogous Li electrolyte fails immediately due to the incompatibility of Li, PC, and graphite. We continue the study by characterizing the impact of TEP on the graphite interphase using a combination of EIS, XPS, and 1D and 2D NMR spectroscopy. We show that, compared to using EC/PC alone, the addition of TEP reduces resistance of the SEI layer, lessens reductive decomposition of carbonates to soluble organic species, and produces inorganic phosphate salts (that we posit contribute to passivation in lieu of fluorination in the SEI). The fifth chapter concludes by summarizing the design strategies learned in each of the preceding three chapters and makes recommendations for future studies. The proposed research emphasizes the need for fundamental studies on materials properties in KIBs, contradicting the current push towards optimizing capacity and longevity of KIBs to prove their relevance. Doing so will not only inform how to design high-performance batteries, but potentially uncover distinct advantages of KIBs that complement existing LIB technologies.

Actuellement, des méthodes quantitatives de résonance magnétique nucléaire (RMN) offrent des biomarqueurs qui permettent la réalisation d’études longitudinales pour le suivi de l’évolution des maladies neuromusculaires et des essais thérapeutiques de manière non-invasive. A la différence de la dégénérescence graisseuse, les processus d’inflammation/œdème/nécrose et fibrose sont des signes d’activité des maladies et leurs quantifications constitueraient ainsi de biomarqueurs parfaitement adaptés pour le suivi thérapeutique. Ce travail de thèse a consisté à mettre en place des méthodologies quantitatives plus précises et adaptées à l’étude clinique du muscle pour : (i) détecter et quantifier des sites d’activité de maladies par la cartographie T2 de l’eau ; (ii) identifier les différents processus pathophysiologiques qui sont à l’origine des altérations du T2 ; et (iii) détecter et quantifier la fibrose musculaire. Nous avons implémenté deux méthodes pour la quantification du T2 de l’eau dans le muscle. La première est basée sur une séquence d’écho de spin du type CPMG, où les signaux provenant des protons des lipides et de l’eau sont acquis simultanément et séparés à postériori par un traitement tri-exponentiel qui exploite la différence entre les T2 qui caractérisent les signaux de l’eau et de la graisse. La deuxième technique est basée sur une séquence de « partially spoiled steady state free precession (pSSFP) ». Différemment de la première technique qui nécessite un traitement assez élaboré sur des images acquises à 17 temps d’écho différents, dans la pSSFP la cartographie T2 est extraite à partir de deux séries de données 3D. L’acquisition 3D est compatible avec des techniques de sélection spectrale de l’eau, ce qui évite la contamination par les signaux des lipides. Les deux méthodes ont été validées expérimentalement chez des malades et des sujets sains et ont démontré leur capacité à détecter et quantifier des sites d’activité de maladies. Ces deux travaux font l’objet de deux publications dans des journaux scientifiques internationaux : Azzabou, de Sousa, Araujo, & Carlier, 2014. Journal of Magnetic Resonance Imaging. DOI 10.1002/jmri.24613 (in press); et de Sousa, Vignaud, Araujo, & Carlier . 2012. Magnetic Resonance in Medicine. 67:1379-1390. Malgré le fait de permettre la détection des sites d’activité de maladies, la mesure mono-exponentielle du T2 de l’eau par imagerie reste non-spécifique vis-à-vis des processus physiologiques à l’origine de l’augmentation du T2. Il est connu que la relaxation T2 du muscle squelettique n’est pas mono-exponentielle. Cela est interprété comme une conséquence de la compartimentation anatomique de l’eau tissulaire. Nous avons mis au point une méthode pour l’acquisition localisée de données CPMG. Cette technique permet l’acquisition des données dans des conditions nécessaires pour la réalisation de traitements multi-exponentiels précis. Ce travail nous a permis d’établir un modèle de compartimentation qui explique parfaitement la relaxation T2 dans le muscle. Il a fait l’objet d’un article publié dans le « Biophysical Journal » (Araujo, Fromes & Carlier 2014. New Insights on skeletal muscle tissue compartments revealed by T2 NMR relaxometry. (In press)). Les essais réalisés chez des sujets malades suggèrent un grand potentiel pour l’application de la méthode dans des études cliniques. La formation de la fibrose commence avec une accumulation excessive de tissu conjonctif intramusculaire (TCIM). Nous avons exploité la technique « Ultrashort Time-to-Echo » (UTE) pour essayer de détecter et caractériser le signal du TCIM. Dans une première étude, nous avons caractérisé in vivo une composante à T2 court (~500 µs) dans le muscle, et nous avons trouvé des indices qui suggèrent qu’elle représente le TCIM. Dans une deuxième étude, nous avons mis au point une méthodologie qui a permis d’imager cette composante à T2 court dans le muscle pour la première fois. / Current quantitative nuclear magnetic resonance (NMR) technics offer biomarkers that allow performing non-invasive longitudinal studies for the follow up of therapeutic trials in neuromuscular disorders (NMD). In contrast to fat degeneration, the mechanisms of inflammation/oedema/necrosis and fibrosis are characteristic signs of disease activity, which makes their quantification a promising source of crucial biomarkers for longitudinal studies. This thesis work consisted on the implementation of more precise quantitative NMR methods adapted to the clinical study of skeletal muscle (SKM) for : (i) detection and quantification of sites of disease activity by T2-mapping of muscle water ; (ii) investigation of the different pathophysiological mechanisms underlying T2 alterations ; and (iii) Detection and quantification of muscle fibrosis. We implemented two methods for T2 mapping of muscle water. The first one is based on a multi-spin-echo sequence du type CPMG. In this method the 1H-NMR signals from water and lipids are acquired simultaneously. The acquired data are fitted to a tri-exponential model, in which water and fat signals are separated by exploring the T2 difference between water and fat. This method allows extraction of muscle water T2-value in the presence of fat infiltration. The second method is based on a « partially spoiled steady state free precession » (pSSFP) sequence. In contrast to the first method, which demands a sophisticated post-treatment of images acquired at 17 different echo-times, with the pSSFP a T2-mapping is extracted from two 3D data sets. 3D acquisition is compatible with spectrally selective water excitation, which eliminates signal contribution from lipids. Both methods were validated experimentally on patients and healthy subjects. The results demonstrated their capacity to detect and quantify disease activity sites. This 2 works have been published in two international journals : Azzabou, de Sousa, Araujo, & Carlier, 2014. Journal of Magnetic Resonance Imaging. DOI 10.1002/jmri.24613 (in press); et de Sousa, Vignaud, Araujo, & Carlier . 2012. Magnetic Resonance in Medicine. 67:1379-1390. Although it was shown to reveal disease activity, mono-exponential T2 of muscle water is non-specific to what concerns the mechanisms underlying its alterations. It has been long known that T2 relaxation in SKM tissue is multi-exponential. This is currently accepted to reveal anatomical compartmentation of myowater. We implemented a method for localized spectroscopic CPMG acquisition. CPMG data respect echo-time sampling and signal to noise ration limits for allowing robust multiexponential analysis. This work allowed us to establish a compartmentation model that perfectly explains the multi-exponential T2 relaxation observed in SKM tissue. This work was published in the « Biophysical Journal » (Araujo, Fromes & Carlier 2014. New Insights on skeletal muscle tissue compartments revealed by T2 NMR relaxometry. (In press)). Pilot studies performed in patients show promising results and suggest potential application of the method in clinical studies. Fibrosis starts with an excessive accumulation of intramuscular connective tissue (IMCT). We have explored the « Ultrashort time to echo » (UTE) method with the aim to detect and characterize the signal from IMCT. In a first study we characterized in vivo a short T2 component (~500 µs) in SKM, and we collected evidences suggesting that this component might reflect IMCT. Then we implemented a methodology that allowed imaging this short component in SKM tissue for the first time.