Papers by M. Bellissent-funel
Structural and Dynamic Properties of Bulk and Con.Ned Water
Drugs and the Pharmaceutical Sciences, 2004
Physical Review E, 1999
We have made a high-resolution quasielastic incoherent neutron scattering ͑QENS͒ study of the tra... more We have made a high-resolution quasielastic incoherent neutron scattering ͑QENS͒ study of the translational dynamics of supercooled water contained in micropores of Vycor glass at different hydration levels. QENS spectra from the confined H 2 O are analyzed in terms of the ␣-relaxation dynamics predicted by mode-coupling theory of supercooled liquids and by a recent computer molecular-dynamics simulation of extended simple point charge model water. We verify that the stretched exponential relaxation description of the long-time test-particle dynamics is consistent with the measured QENS spectral line shape. We are thus able to determine the wave-number dependence of magnitudes of the structural relaxation rate 1/ and the stretch exponent  as functions of temperature and coverage. A power-law dependence of the average relaxation time on the magnitude of the scattering vector Q is observed. In the Q range studied, the exponent starts out with nearly Ϫ2.0, at room temperature, indicating a continuous diffusion, and gradually becomes less negative as the temperature is decreased to below the freezing temperature.
Physical Review B, 1994
Neutron-diffraction data on liquid iodine at three temperatures on the coexistence curve are pres... more Neutron-diffraction data on liquid iodine at three temperatures on the coexistence curve are presented. The data show that the strong orientational correlations between neighboring molecules, already found at the melting point, persist up to the vicinity of the critical point. The A2 efFective pair potential model is found to describe satisfactorily the structure of the liquid along the entire coexistence curve.
Physical Review Letters, 2000
Intermediate scattering functions for density fluctuation in D 2 O contained in pores of a Vycor ... more Intermediate scattering functions for density fluctuation in D 2 O contained in pores of a Vycor glass have been measured using an improved neutron spin-echo spectrometer at two supercooled temperatures. The measurements cover the time range from 1 to 2300 ps with the Q range spanning the first diffraction peak of water. The time correlation functions can be fitted to a stretched exponential relaxation function with a Q-dependent amplitude. Both the stretch exponent and the relaxation time peak approximately at the Q value corresponding to the first diffraction peak, confirming the validity of the mode coupling idea in supercooled water.
Physica B: Condensed Matter, 1994
In this work we address the problem of multiple scattering and inelasticity corrections in neutro... more In this work we address the problem of multiple scattering and inelasticity corrections in neutron diffraction measurements for structural studies of molecular systems. A variety of pulsed neutron and reactor experiments was performed on hydrogenous samples under different experimental conditions. Monte Carlo simulations were carried out on the basis of a Synthetic Model to describe the neutron-molecule interaction, and they allowed a simultaneous evaluation of multiple, inelastic and beam attenuation processes into the samples. A very good agreement between measurements and simulations was obtained in all cases, for our demanding choice of samples and experimental conditions. * Corresponding author. Also at Consejo Nacional de lnvestigaciones Cientificas y T~cnicas (CONICET), Argentina. 2 Also at CRUB, Universidad Nacional del Comahue. *The material contained in this paper is part ofJ. Dawidowski's PhD thesis (Instituto Balseiro, May 1993).
Water dynamics in DMSO–water mixture
Physica B: Condensed Matter, 2000
We study water dynamics in the eutectic DMSO–water mixture by incoherent quasielastic neutron sca... more We study water dynamics in the eutectic DMSO–water mixture by incoherent quasielastic neutron scattering. Water individual motions are modelled by uncoupled whole-molecule translations and rotations around the center of mass. We determine water self-diffusion coefficients, residence times for jump diffusion and rotational relaxation times, previously related to the hydrogen-bond “lifetime”. We therefore quantify the perturbation of water dynamics due to
Physica B: Condensed Matter, 1995
Neutron diffraction measurement has proven a very powerful tool for the direct study of the inter... more Neutron diffraction measurement has proven a very powerful tool for the direct study of the interatomic interaction law in simple fluids. In a molecular system the anisotropy of the potential does not allow a direct evaluation of the potential itself. Nevertheless, this kind of measurements, especially if performed as a function of thermodynamic parameters like the density and the temperature, contains a rich amount of information on the microscopic behaviour of the sample. We present here the preliminary results of an experiment performed on a diatomic system with a low molecular anisotropy like N2 in such a low density regime that the two-and three-body contributions to the interactions could be evaluated experimentally.
Molecular Physics, 1980
Accurate neutron-diffraction measurements on saturated liquid iodine, up to Q =16 A ', at T=409 K... more Accurate neutron-diffraction measurements on saturated liquid iodine, up to Q =16 A ', at T=409 K are presented. The intermolecular structure factor has been derived and a study performed on the presence of orientational correlations and their contribution to the intensity distribution. The experimental intermolecular pair correlation function has been compared with the results of a simulation performed using the anisotropic atom-atom pair potential proposed by Rodger, Stone, and Tildesley [Mol. Phys. 63, 173 (1988)],giving excellent agreement. A comparison with previous neutron and x-ray data is also discussed.
Structure of liquid chlorine from neutron-diffraction measurements
Molecular Physics, 1990
Intermolecular structure of liquid deuterium: A new neutron diffraction investigation
Journal of Physics: Condensed Matter, 1995
The static centre of mass structure factor of liquid deuterium, already determined by means of ti... more The static centre of mass structure factor of liquid deuterium, already determined by means of time of flight neutron diffraction (as reported in Physical Review E in 1993), has been re-investigated with a two-axis diffractometer at a reactor source. A detailed analysis of the data is presented, with special attention devoted to the correction for inelastic scattering effects. The comparison of the two sets of data reveals the presence of discrepancies, which cannot be attributed to statistical inaccuracies. The density and the temperature derivatives of the structure factor have also been measured with high accuracy. For these quantities, the two experiments are in good agreement with each other. This suggests that the discrepancy in the structure factor is due to systematic effects which vanish in a differential measurement.
Supersaturated Zincate Solutions: A Structural Study
Journal of The Electrochemical Society, 1995
ABSTRACT
Slow dynamics of water molecules on the surface of a globular protein
Faraday Discussions, 1996
In recent years interfacial water has attracted considerable interest in the field of biology, be... more In recent years interfacial water has attracted considerable interest in the field of biology, because the effects of hydration on equilibrium protein structure and dynamics are fundamental to the relationship between structure and biological function.'-' In particular, the assessment of ...
Dynamics of a Deuterated C-Phycocyanin Protein as studied by Coherent inelastic Neutron scattering
Le Journal de Physique Colloques, 1981
Le Journal de Physique Colloques, 1984
Resume-Nous avons &tudi@ l e s mecanismes de diffusion des protons dans =pure e t l e s solutions... more Resume-Nous avons &tudi@ l e s mecanismes de diffusion des protons dans =pure e t l e s solutions aqueuses de ZnC12, par d i f f u s i o n quasi-elastique incoherente de neutrons e t avons montre q u ' i l e t a i t indispensable de t e n i r compte du mouvement de rotation des mol@cules d'eau ; l e temps de r e l axation c a r a c t e r i s t i q u e associe passe de 0.8 ps pour l ' e a u pure Z 20 ps pour l a solution saturee ce que l ' o n i n t e r p r e t e en termes de rotationsg&nees dans l e s solutions concentrees. La p a r t i e t r a n s l a t i o n n e l l e des spectres a 6t.S convenablement representee sur t o u t l e domaine en Q explore, Z 1 'aide d'un modele de diffusion par s a u t s a l e a t o i r e s. La longueur de saut obtenue r e s t e pratiquement l a meme quand on passe de l ' e a u l a solution saturee e t voisine de l a distance e n t r e protons dans l a mol6cule d'eau. Abstract-W e studied the d i f f u s i v e motions of t h e protons in pure water and ZnCl aqueous solutions, using incoherent quasi-elastic neutron s c a t t e r i n g. W e siowed t h a t i t i s essential t o take i n t o account the rotational motion of the water molecules ; t h e associated c h a r a c t e r i s t i c relaxation time varies from 0.8 ps f o r H20 t o 20 ps f o r the saturated solution which i s interpreted in terms of hindered rotations f o r the concentrated solutions. The translational linewidth i s conveniently f i t t e d over the whole Q-range, using the Random Jump Diffusion model f o r which t h e jump length turns out t o be roughly t h e same f o r pure H20 and t h e saturated solution, f a i r l y close t o the d i stance between ~r o t o n s i n t h e water molecule.
Il Nuovo Cimento D, 1990
Background: Growth differentiation factor 6 (GDF6) has been reported to be a novel disease gene f... more Background: Growth differentiation factor 6 (GDF6) has been reported to be a novel disease gene for age-related macular degeneration (AMD) in Caucasians. This study aimed to investigate whether rs6982567 was associated with neovascular AMD (nAMD) or polypoidal choroidal vasculopathy (PCV) in a Han Chinese cohort. Methods: A total of 612 participants (251 PCV patients, 157 nAMD patients and 204 controls) were included in this study. The SNaPshot system was used to genotype the rs6982567. PLINK software was used to evaluate the genotypes and allele frequencies of patients and controls. Results: The allele frequencies of rs6982567 were not significantly associated with nAMD, PCV or PCV and nAMD combined. Subjects with the TT genotype had a 2.42-fold greater risk of PCV (95% confidence interval, 1.07-5.43, p = 0.0290) than subjects with CC genotype. A recessive model of rs6982567 was statistically significantly associated with PCV (odds ratio, 2.29; 95% confidence interval, 1.04-5.05; p = 0.0351). However, the association did not withstand stringent Bonferroni correction. There were no significant differences in genotype distributions or models in nAMD. Conclusions: There was a possible weak association between the rs6982567 near GDF6 and PCV in this replication study with an independent Han Chinese cohort. A complete survey of the GDF6 locus with a larger sample size is needed in future studies.
Neutron Diffraction Study of the Effect of a Polyelectrolyte on the Hydration of Nickel Ions
The Journal of Physical Chemistry, 1994
ABSTRACT
Journal de Physique I, 1992
Journal de Physique I, 1992
Recent Structural Studies of Liquid D2O by Neutron Diffraction
Hydrogen-Bonded Liquids, 1991
We present our recent structural studies of liquid D2O performed by neutron diffraction. The resu... more We present our recent structural studies of liquid D2O performed by neutron diffraction. The results cover a large temperature range extending from 95°C down to −31.5°C i.e. close to the temperature of homogeneous nucleation and particularly in the low temperature range where liquid water exhibits an abnormal behaviour. The structural changes versus temperature are discussed using a difference function technique. We show that the isochoric temperature derivative function ΔdL (r,ΔT)/ΔT where dL (r,T) is the pair correlation function at T, has a universal shape for distances larger than 2 A, indicating a systematic change in spatial correlations over the density maximum. The structural investigation of deeply supercooled water has been achieved by using emulsions with water droplets of some µm diameter. At −31.5°C the pair distribution function of water shows an increase of the spatial correlations which confirms the fact that the structure of deeply supercooled water tends towards that of low density amorphous ice.
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Papers by M. Bellissent-funel