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M. et alin Astronomy and Astrophysics (2015), 582Context. The direct detection of exoplanets with high-contrast imaging requires advanced data processing methods to disentangle potential planetary signals from bright quasi-static speckles. Among them ... [more ▼]Context. The direct detection of exoplanets with high-contrast imaging requires advanced data processing methods to disentangle potential planetary signals from bright quasi-static speckles. Among them, angular differential imaging (ADI) permits potential planetary signals with a known rotation rate to be separated from instrumental speckles that are either statics or slowly variable. The method presented in this paper, called ANDROMEDA for ANgular Differential OptiMal Exoplanet Detection Algorithm is based on a maximum likelihood approach to ADI and is used to estimate the position and the flux of any point source present in the field of view. Aims. In order to optimize and experimentally validate this previously proposed method, we applied ANDROMEDA to real VLT/NaCo data. In addition to its pure detection capability, we investigated the possibility of defining simple and efficient criteria for automatic point source extraction able to support the processing of large surveys. Methods. To assess the performance of the method, we applied ANDROMEDA on VLT/NaCo data of TYC-8979-1683-1 which is surrounded by numerous bright stars and on which we added synthetic planets of known position and flux in the field. In order to accommodate the real data properties, it was necessary to develop additional pre-processing and post-processing steps to the initially proposed algorithm. We then investigated its skill in the challenging case of a well-known target, $\beta$ Pictoris, whose companion is close to the detection limit and we compared our results to those obtained by another method based on principal component analysis (PCA). Results. Application on VLT/NaCo data demonstrates the ability of ANDROMEDA to automatically detect and characterize point sources present in the image field. We end up with a robust method bringing consistent results with a sensitivity similar to the recently published algorithms, with only two parameters to be fine tuned. Moreover, the companion flux estimates are not biased by the algorithm parameters and do not require a posteriori corrections. Conclusions. ANDROMEDA is an attractive alternative to current standard image processing methods that can be readily applied to on-sky data. [less ▲]Detailed reference viewed: 21 (0 ULg) Direct experimental evidence for atomic tunneling of europium in crystalline Eu8Ga16Ge30Hermann, Raphaël ; Keppens, Veerle; Bonville, Pierre et alin Physical Review Letters (2006), 97(1), Mossbauer-effect and microwave absorption experimental evidence unambiguously demonstrates the presence of slow, similar to 450 MHz, tunneling of magnetic europium between four equivalent sites in ... [more ▼]Mossbauer-effect and microwave absorption experimental evidence unambiguously demonstrates the presence of slow, similar to 450 MHz, tunneling of magnetic europium between four equivalent sites in Eu8Ga16Ge30, a stoichiometric clathrate. Remarkably, six of the eight europium atoms, or 11% of the constituents in this solid, tunnel between these four sites separated by 0.55 angstrom. The off centering of the atoms or ions in crystalline clathrates appears to be a promising route for producing Rabi oscillators in solid-state materials. [less ▲]Detailed reference viewed: 10 (0 ULg) Direct extraction of hadronic form factors from elastic-scattering dataMartynov, E.; Cudell, Jean-René ; Lengyel, A.in Nuclear Physics B-Proceedings Supplements (2005, September), 146Non-forward elastic hadron-scattering data are collected and analysed within the Regge approach. Through an analysis of the data in small bins in t, we have directly extracted the pomeron trajectory and ... [more ▼]Non-forward elastic hadron-scattering data are collected and analysed within the Regge approach. Through an analysis of the data in small bins in t, we have directly extracted the pomeron trajectory and the hadronic form factors (or reggeon couplings). We found higher values than usually used for the intercept and for the slope of the soft pomeron trajectory. The presence of zeros in t for the effective hadronic form factors is emphasised. [less ▲]Detailed reference viewed: 13 (1 ULg) Direct identification of bacteria from BacT/ALERT anaerobic positive blood cultures by MALDI-TOF MS: MALDI Sepsityper kit versus an in-house saponin method for bacterial extraction.MEEX, Cécile ; Neuville, Florence; DESCY, Julie et alin Journal of Medical Microbiology (2012), 61In cases of bacteraemia, a rapid species identification of the causal agent directly from positive blood culture broths could assist clinicians in the timely targeting of empirical antimicrobial therapy ... [more ▼]In cases of bacteraemia, a rapid species identification of the causal agent directly from positive blood culture broths could assist clinicians in the timely targeting of empirical antimicrobial therapy. For this purpose, we evaluated the direct identification of micro-organisms from BacT/ALERT (bioMérieux) anaerobic positive blood cultures without charcoal using the Microflex matrix-assisted laser desorption/ionization (MALDI) time of flight MS (Bruker), after bacterial extraction by using two different methods: the MALDI Sepsityper kit (Bruker) and an in-house saponin lysis method. Bruker's recommended criteria for identification were expanded in this study, with acceptance of the species identification when the first three results with the best matches with the MALDI Biotyper database were identical, whatever the scores were. In total, 107 monobacterial cultures and six polymicrobial cultures from 77 different patients were included in this study. Among monomicrobial cultures, we identified up to the species level 67 and 66 % of bacteria with the MALDI Sepsityper kit and the saponin method, respectively. There was no significant difference between the two extraction methods. The direct species identification was particularly inconclusive for Gram-positive bacteria, as only 58 and 52 % of them were identified to the species level with the MALDI Sepsityper kit and the saponin method, respectively. Results for Gram-negative bacilli were better, with 82.5 and 90 % of correct identification to the species level with the MALDI Sepsityper kit and the saponin method, respectively. No misidentifications were given by the direct procedures when compared with identifications provided by the conventional method. Concerning the six polymicrobial blood cultures, whatever the extraction method used, a correct direct identification was only provided for one of the isolated bacteria on solid medium in all cases. The analysis of the time-to-result demonstrated a reduction in the turnaround time for identification ranging from 1 h 06 min to 24 h 44 min, when performing the blood culture direct identification in comparison with the conventional method, whatever the extraction method. [less ▲]Detailed reference viewed: 70 (13 ULg) Direct identification of bacteria from positive blood cultures by MALDI-TOF MS : MALDI Sepsityper kit (Bruker) VS home made saponin method for bacterial extractionMEEX, Cécile ; NEUVILLE, Florence; DESCY, Julie et alPoster (2011)Detailed reference viewed: 22 (6 ULg) Direct imaging of Earth-like planets: why we care about exozodisAbsil, Olivier ; Defrère, D.; Roberge, A. et alin Danchi, W. C.; Delplancke, F.; Rajagopal, J. K. (Eds.) Optical and Infrared Interferometry II (2010, July)The presence of large amounts of exozodiacal dust around nearby main sequence stars is considered as a potential threat for the direct detection of Earth-like exoplanets (exoEarths) with future space ... [more ▼]The presence of large amounts of exozodiacal dust around nearby main sequence stars is considered as a potential threat for the direct detection of Earth-like exoplanets (exoEarths) with future space-based coronagraphic and interferometric missions. In this paper, we estimate the amount of exozodiacal light that can be tolerated around various stellar types without jeopardizing the detection of exoEarths with a space-based visible coronagraph or a free-flying mid-infrared interferometer. We also address the possible effects of resonant structures in exozodiacal disks. We then review the sensitivity of current ground-based interferometric instruments to exozodiacal disks, based on classical visibility measurements and on the nulling technique. We show that the current instrumental performances are not sufficient to help prepare future exoEarth imaging missions, and discuss how new groundor space-based instruments could improve the current sensitivity to exozodiacal disks down to a suitable level. [less ▲]Detailed reference viewed: 32 (11 ULg) Direct imaging of extra-solar planets in star forming regions. Lessons learned from a false positive around IM Lup.Mawet, Dimitri; Absil, Olivier ; Riaud, Pierre et alin Astronomy and Astrophysics (2012), 544Context. Most planet imagers consist of ground-based adaptive optics coronagraphic cameras which are currently limited in contrast, sensitivity and astrometric precision, but advantageously observe in the ... [more ▼]Context. Most planet imagers consist of ground-based adaptive optics coronagraphic cameras which are currently limited in contrast, sensitivity and astrometric precision, but advantageously observe in the near-infrared window (1 - 5 µm). Because of these practical limitations, our current observational aim at detecting and characterizing planets puts heavy constraints on target selection, observing strategies, data reduction, and follow-up. Most surveys so far have thus targeted very young systems (1 - 100Myr) to catch the putative remnant thermal radiation of giant planets, which peaks in the near-infrared. They also favor systems in the solar neighborhood (d < 80 pc), which eases angular resolution requirements but also ensures a good knowledge of the distance and proper motion, which are critical to secure the planet status, and enable any subsequent characterization. Aims. Because of their youth, it is very tempting to target the nearby star forming regions, which are typically twice as far as the bulk of objects usually combed for planets by direct imaging. Probing these very interesting reservoirs in practice sets additional constraints that we review in this paper by presenting the planet search that we initiated in 2008 around the disk-bearing T Tauri star IM Lup, which is part of the Lupus star forming region (140-190 pc). Methods. We show and discuss why age determination, the choice of evolutionary model for both the central star and the planet, precise knowledge of the host star proper motion, relative or absolute (between different instruments) astrometric accuracy (including plate scale calibration), and patience are the key ingredients for exoplanet searches around more distant young stars. Results. Unfortunately, most of the time, precision and perseverance are not paying off: we discovered a candidate companion around IM Lup in 2008, which we report here to be a false positive event. We nevertheless review in details the lessons learned from our endeavor, and additionally present the best detection limits ever calculated for IM Lup. We also accessorily report on the successful use of innovative data reduction techniques, such as the damped-LOCI and iterative roll subtraction. [less ▲]Detailed reference viewed: 65 (4 ULg) Direct imaging, photometry and spectroscopy of gravitationally lensed quasarsRicci, Davide Doctoral thesis (2012)Detailed reference viewed: 25 (3 ULg) Direct Inclusion of Proximity-Effect Losses in Two-Dimensional Time-Domain Finite-Element Simulation of Electrical MachinesGyselinck, Johan; Dular, Patrick ; Geuzaine, Christophe et alin Proceedings of the 8th International Symposium on Electric and Magnetic Fields (EMF2009) (2009)This paper deals with eddy-current effects in the distributed winding of electrical machines, and in particular with the proximity effect and the associated losses. A previously proposed homogenization ... [more ▼]This paper deals with eddy-current effects in the distributed winding of electrical machines, and in particular with the proximity effect and the associated losses. A previously proposed homogenization method for windings in two-dimensional (2D) time-domain finite-element (FE) models is shown to be applicable without additional computational cost, producing a precise estimate of the instantaneous proximity-effect losses. The method is illustrated by considering the conductors in a single stator slot of a 3kW induction motor. The brute-force model, with fine discretisation of each conductor, and the homogenized model yield macroscopic results that are very close to each other. [less ▲]Detailed reference viewed: 73 (10 ULg) Direct induction of burst firing by SK channel blockade in serotonergic neurons in vivoRouchet, Nathalie; Waroux, Olivier ; Moreau, Jacqueline et alScientific conference (2007, November 04)Small conductance calcium-activated potassium channels (SK channels) are widely expressed throughout the central nervous system and underlie the medium afterhyperpolarization following a single or a train ... [more ▼]Small conductance calcium-activated potassium channels (SK channels) are widely expressed throughout the central nervous system and underlie the medium afterhyperpolarization following a single or a train of action potentials. It has been shown that they are involved in the regulation of the excitability and the firing pattern of several types of neurons. In vivo, serotonergic (5-HT) neurons of the dorsal raphe nucleus usually show a tonic pattern of discharge, but they can also display repetitive burst firing activity, usually involving doublets of closely spaced (< 20 ms) action potentials. It has been shown that burst firing is correlated with an increase in transmitter release and postsynaptic effects (Gartside et al., Neuroscience, 98, 295-300, 2000). We hypothesized that SK channels modulate the firing pattern of 5-HT neurons. In a preliminary study, extracellular single-cell recordings combined with iontophoresis showed that UCL1684, a water soluble SK blocker (200 µM), significantly increased the % of spikes produced in bursts in 60% of presumed serotonergic neurons in the anesthetized rat. We confirm here this observation by demonstrating that UCL1684 significantly increased the production of doublets in 17 out of 25 serotonergic neurons. In order to explore whether a GABAergic input was involved in this effect, additional experiments were performed in the presence of the specific GABAA antagonist SR 95531. In these conditions, 50 % (5 out of 10) of serotonergic neurons showed an increase in the production of doublets when UCL 1684 was applied (p = 0.31 vs control), suggesting that a GABAergic input is not implicated in the regulation of the firing pattern of 5-HT neurons by the SK blocker. Finally, the effect of SK channel blockade was explored in vitro in slices. Bath application of the SK blocker apamin (300 nM) did not induce bursting in 15 out of 18 neurons (p < 0.001 vs in vivo control conditions), although it did increase the coefficient of variation of the interspike intervals.Taken together, our results suggest that SK blockade induces burst firing in a majority of dorsal raphe serotonergic neurons. This effect does not involve GABAergic interneurons, but requires an input that is only present in vivo. [less ▲]Detailed reference viewed: 7 (1 ULg) Direct inhibition of the DNA-binding activity of POU transcription factors Pit-1 and Brn-3 by selective binding of a phenyl-furan-benzimidazole dication.Peixoto, Paul ; Liu, Yang; Depauw, Sabine et alin Nucleic Acids Research (2008), 36(10), 3341-53The development of small molecules to control gene expression could be the spearhead of future-targeted therapeutic approaches in multiple pathologies. Among heterocyclic dications developed with this aim ... [more ▼]The development of small molecules to control gene expression could be the spearhead of future-targeted therapeutic approaches in multiple pathologies. Among heterocyclic dications developed with this aim, a phenyl-furan-benzimidazole dication DB293 binds AT-rich sites as a monomer and 5'-ATGA sequence as a stacked dimer, both in the minor groove. Here, we used a protein/DNA array approach to evaluate the ability of DB293 to specifically inhibit transcription factors DNA-binding in a single-step, competitive mode. DB293 inhibits two POU-domain transcription factors Pit-1 and Brn-3 but not IRF-1, despite the presence of an ATGA and AT-rich sites within all three consensus sequences. EMSA, DNase I footprinting and surface-plasmon-resonance experiments determined the precise binding site, affinity and stoichiometry of DB293 interaction to the consensus targets. Binding of DB293 occurred as a cooperative dimer on the ATGA part of Brn-3 site but as two monomers on AT-rich sites of IRF-1 sequence. For Pit-1 site, ATGA or AT-rich mutated sequences identified the contribution of both sites for DB293 recognition. In conclusion, DB293 is a strong inhibitor of two POU-domain transcription factors through a cooperative binding to ATGA. These findings are the first to show that heterocyclic dications can inhibit major groove transcription factors and they open the door to the control of transcription factors activity by those compounds. [less ▲]Detailed reference viewed: 13 (2 ULg) A direct link between growth retardation and inflammation? Identification of a splice site mutation in the bovine RNF11 geneSartelet, Arnaud ; Fasquelle, Corinne ; Tamma, Nico et alin New Biotechnology (2010, April 27), (supplement 1), 63Detailed reference viewed: 18 (1 ULg) Direct measurement of static chest wall compliance in unsedated calvesDesmecht, Daniel ; Rollin, Frédéric ; Amory, Hélène et alin Proceedings of the 8th Comparative Respiratory Society Meeting (1989)Detailed reference viewed: 5 (0 ULg) Direct measurements of interactions between hydrophobically anchored strongly charged polyelectrolyte brushesAbraham, T.; Giasson, S.; Gohy, Jean-François et alin Langmuir (2000), 16(9), 4286-4292We investigated the nature and the range of interactions between negatively charged polyelectrolyte-coated surfaces as a function of salt concentration using the surface forces apparatus. The measured ... [more ▼]We investigated the nature and the range of interactions between negatively charged polyelectrolyte-coated surfaces as a function of salt concentration using the surface forces apparatus. The measured force profiles (interaction forces versus separation distance) are purely repulsive and show long-range electrostatic and short-range steric interactions. The measured range of interaction in salt-free as well as in low ionic strengths extends well beyond the contour length of the polyelectrolyte chain. It is shown that the interaction range between the ionic brush layers and the grafting density depend on the ionic strength of the solution. In salt-free solution, the counterions associated with polyelectrolyte cause the chains to stretch and give rise to long-range double-layer electrostatic repulsions between the opposing chains. When salt is added to the system, the electrostatic interactions are partially screened and the polymer chain regains its flexibility and therefore the range of interactions is reduced. The measured total range of interaction exhibits relatively weaker dependence on the salt concentration. We find that our force−distance profiles with added salt in a compressed regime can be very well described by the Pincus scaling model. [less ▲]Detailed reference viewed: 19 (1 ULg) Direct Modelling of Unit Operations on Molecular LevelBabic, D; Pfennig, Andreas Conference (2006)Detailed reference viewed: 1 (0 ULg) Direct multiple-point geostatistical simulation of edge properties for modeling thin irregularly-shaped surfacesHuysmans, Marijke; Dassargues, Alain in Mathematical Geosciences (2011), 43Thin irregularly-shaped surfaces such as clay drapes often have a major control on flow and transport in heterogeneous porous media. Clay drapes are often complex curvilinear 3-dimensional surfaces and ... [more ▼]Thin irregularly-shaped surfaces such as clay drapes often have a major control on flow and transport in heterogeneous porous media. Clay drapes are often complex curvilinear 3-dimensional surfaces and display a very complex spatial distribution. Variogram-based stochastic approaches are often also not able to describe the spatial distribution of clay drapes since complex, curvilinear, continuous and interconnected structures cannot be characterized using only two-point statistics. Multiple-point geostatistics aims to overcome the limitations of the variogram. The premise of multiple-point geostatistics is to move beyond two-point correlations between variables and to obtain (cross) correlation moments at three or more locations at a time using "training images" to characterize the patterns of geological heterogeneity. Multiple-point geostatistics can reproduce thin irregularly-shaped surfaces such as clay drapes but is often computationally very intensive. This paper describes and applies a methodology to simulate thin irregularly-shaped surfaces with a smaller CPU and RAM demand than the conventional multiple-point statistical methods. The proposed method uses edge properties for indicating the presence of thin irregularly-shaped surfaces. This method allows directly simulating edge properties instead of pixel properties to make it possible to perform multiple-point geostatistical simulations with a larger cell size and thus a smaller computation time and memory demand. [less ▲]Detailed reference viewed: 44 (7 ULg) Direct multiple-point geostatistical simulation of edge properties for modeling thin irregularly-shaped surfacesHuysmans, Marijke; Dassargues, Alain in Cockx, L.; Van Meirvenne, M.; Bogaert, P. (Eds.) et al 8th International Conference On Geostatistics for Environmental Applications, GeoENV’2010 (2010, September)Thin irregularly-shaped surfaces such as clay drapes often have a major control on flow and transport in heterogeneous porous media. Clay drapes are often complex curvilinear 3-dimensional surfaces and ... [more ▼]Thin irregularly-shaped surfaces such as clay drapes often have a major control on flow and transport in heterogeneous porous media. Clay drapes are often complex curvilinear 3-dimensional surfaces and display a very complex spatial distribution. Variogram-based stochastic approaches are often also not able to describe the spatial distribution of clay drapes since complex, curvilinear, continuous and interconnected structures cannot be characterized using only two-point statistics. Multiple-point geostatistics aims to overcome the limitations of the variogram. The premise of multiple-point geostatistics is to move beyond two-point correlations between variables and to obtain (cross) correlation moments at three or more locations at a time using "training images" to characterize the patterns of geological heterogeneity. Multiple-point geostatistics is able to reproduce thin irregularly-shaped surfaces such as clay drapes but is often computationally intensive. To capture the thin surfaces, a small grid cell size should be adopted for the training image. This results in large training images and a large search template size and thus a large CPU and RAM demand (Huysmans and Dassargues, 2009). [less ▲]Detailed reference viewed: 45 (12 ULg) Direct n.m.r. evidence for substrate-induced conformational changes in a beta-lactamase.Jamin, M.; Damblon, Christian ; Bauduin-Misselyn, A. M. et alin Biochemical Journal (1994), 301 ( Pt 1)Cefoxitin and other beta-lactam antibiotics with a methoxy group on the alpha-face behave as very poor substrates of the Bacillus licheniformis beta-lactamase. The kinetic properties of the enzyme ... [more ▼]Cefoxitin and other beta-lactam antibiotics with a methoxy group on the alpha-face behave as very poor substrates of the Bacillus licheniformis beta-lactamase. The kinetic properties of the enzyme-cefoxitin system made it theoretically suitable for a detailed structural study of the acyl-enzyme. Unfortunately, soaking the crystals in cefoxitin solution did not allow detection of a crystalline acyl-enzyme complex. In contrast, direct observation by n.m.r. of the stable acyl-enzyme formed with cefoxitin and moxalactam indicated clear modifications of the enzyme structure, which were reflected in the aromatic and high-field methyl regions of the spectrum. The return to the initial free enzyme spectrum was concomitant with the hydrolysis of the acyl-enzyme, the process being slow enough to allow multidimensional n.m.r. experiments. [less ▲]Detailed reference viewed: 13 (0 ULg) Direct nano-in-micropatterning of TiO2 thin layers and TiO2/Pt nanoelectrode arrays by deep X-ray lithographyFaustini, M.; Marmiroli, B.; Malfatti, L. et alin Journal of Materials Chemistry (2011), 21Detailed reference viewed: 9 (1 ULg) Direct NMR evidence for a local resriction in the segmental chain mobility of a model ionomerVanhoorne, Pierre; Jérôme, Robert ; Teyssié, Philippe et alin Macromolecules (1994), 27(9), 2548-2552To probe the local mobility of the chain segments directly attached to ionic multiplets, two model ionomers have been synthesized. The first one is a carboxylato-telechelic deuterated polystyrene in which ... [more ▼]To probe the local mobility of the chain segments directly attached to ionic multiplets, two model ionomers have been synthesized. The first one is a carboxylato-telechelic deuterated polystyrene in which the chain segments bearing the sodium carboxylate end groups have been selectively protonated; the second one has a protonated polystyrene backbone terminated at both ends with a deuterated polystyrene segment bearing the sodium carboxylate groups. Both polymers have been studied by high-resolution solid-state C-13 NMR. Line-width measurements of the protonated units have clearly shown that the dipolar interactions of the sodium carboxylate end groups are responsible for a mobility restriction of the chain end segments. This experiment is thought to be the first direct evidence for the model recently proposed by Eisenberg et al. for ionomer morphology according to which the ionic multiplets are surrounded with a shell of constrained polymer segments. [less ▲]Detailed reference viewed: 12 (1 ULg)