Le tournant global des sciences sociales

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Le moment global des sciences sociales

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Des sciences sociales à la science sociale. Fondements anti-utilitaristes.

International audienceno abstrac

Des sciences sociales à la science sociale. Fondements anti-utilitaristes.

International audienceno abstrac

Sensory characteristics changes of red Grenache wines submitted to different oxygen exposures pre and post bottling

National audienceIt is widely accepted that oxygen contributes to wine development by impacting its colour, aromatic bouquet, and mouth-feel properties. The wine industry can now also take advantage of engineered solutions to deliver known amounts of oxygen into bottles through the closures. This study was aimed at monitoring the influence of oxygen pick-up, before (micro-oxygenation, Mox) and after (nano-oxygenation) bottling, on wine sensory evolution. Red Grenache wines were prepared either by flash release (FR) or traditional soaking (Trad) and with or without Mox during elevage (FR + noMox, FR + Mox, Trad + noMox, Trad + Mox). The rate of nano oxygenation was controlled by combining consistent oxygen transfer rate (OTR) closures and different oxygen controlled storage conditions. Wine sensory characteristics were analyzed by sensory profile, at bottling (TO) and after 5 and 10 months of ageing, by a panel of trained judges. Effects of winemaking techniques and OTR were analyzed by multivariate analysis (principal component analysis and agglomerative hierarchical clustering) and analysis of variance. Results showed that. at bottling, Trad wines were perceived more animal and FR wines more bitter and astringent. Mox wines showed more orange shade. At 5 and 10 months, visual and olfactory differences were observed according to the OTR levels: modalities with higher oxygen ingress were darker and fruitier but also perceived significantly less animal than modalities with lower oxygen. Along the 10 months of ageing, the influence of OTR became more important as shown by increased significance levels of the observed differences. As the mouth-feel properties of the wines were mainly dictated by winemaking techniques, OTR had only little impact on "in mouth" attribute

Mechanistic studies of Gd3+^{3+}-based MRI contrast agents for Zn2+^{2+} detection: towards rational design

International audienceA series of novel pyridine-based Gd$^{3+}$ complexes have been prepared and studied as potential MRI contrast agents for Zn$^{2+}$ detection. By independent assessment of molecular parameters affecting relaxivity, we could interpret the relaxivity changes observed upon Zn$^{2+}$ binding in terms of variations of the rotational motion

Isoquinoline-Based Lanthanide Complexes: Bright NIR Optical Probes and Efficient MRI Agents

In the objective of developing ligands that simultaneously satisfy the requirements for MRI contrast agents and near-IR emitting optical probes that are suitable for imaging, three isoquinoline-based polyaminocarboxylate ligands, L1, L2 and L3, have been synthesized and the corresponding Gd3+, Nd3+ and Yb3+ complexes studied. The specific challenge of the present work was to create NIR emitting agents which (i) have excitation wavelengths compatible with biol. applications and (ii) are able to emit a sufficient no. of photons to ensure sensitive NIR detection for microscopic imaging. Here the authors report the first observation of a NIR signal arising from a Ln3+ complex in aq. soln. in a microscopy setup. The lanthanide complexes have high thermodn. stability (log KLnL =17.7-18.7) and good selectivity for lanthanide ions vs. the endogenous cations Zn2+, Cu2+, and Ca2+ thus preventing transmetalation. A variable temp. and pressure 17O NMR study combined with nuclear magnetic relaxation dispersion measurements yielded the microscopic parameters characterizing water exchange and rotation. Bishydration of the lanthanide cation in the complexes, an important advantage to obtain high relaxivity for the Gd3+ chelates, has been demonstrated by 17O chem. shifts for the Gd3+ complexes and by luminescence lifetime measurements for the Yb3+ analogs. The water exchange on the three Gd3+ complexes is considerably faster (kex298 = (13.9-15.4) × 106 s-1) than on com. Gd3+-based contrast agents and proceeds via a dissociative mechanism, as evidenced by the large pos. activation vols. for GdL1 and GdL2 (+10.3 ± 0.9 and +10.6 ± 0.9 cm3 mol-1, resp.). The relaxivity of GdL1 is doubled at 40 MHz and 298 K in fetal bovine serum (r1 = 16.1 vs. 8.5 mM-1 s-1 in HEPES buffer), due to hydrophobic interactions between the chelate and serum proteins. The isoquinoline core allows for the optimization of the optical properties of the luminescent lanthanide complexes in comparison to the pyridinic analogs and provides significant shifts of the excitation energies toward lower values which therefore become more adapted for biol. applications. L2 and L3 bear two methoxy substituents on the arom. core in ortho and para positions, resp., that further modulate their electronic structure. The Nd3+ and Yb3+ complexes of the ligand L3, which incorporates the p-dimethoxyisoquinoline moiety, can be excited up to 420 nm. This wavelength is shifted over 100 nm toward lower energy in comparison to the pyridine-based analog. The luminescence quantum yields of the Nd3+ (0.013-0.016%) and Yb3+ chelates (0.028-0.040%) are in the range of the best nonhydrated complexes, despite the presence of two inner sphere water mols. More importantly, the 980 nm NIR emission band of YbL3 was detected with a good sensitivity in a proof of concept microscopy expt. at a concn. of 10 μM in fetal bovine serum. The authors' results demonstrate that even bishydrated NIR lanthanide complexes can emit a sufficient no. of photons to ensure sensitive detection in practical applications. In particular, these ligands contg. an arom. core with coordinating pyridine nitrogen can be easily modified to tune the optical properties of the NIR luminescent lanthanide complexes while retaining good complex stability and MRI characteristics for the Gd3+ analogs. They constitute a highly versatile platform for the development of bimodal MR and optical imaging probes based on a simple mixt. of Gd3+ and Yb3+/Nd3+ complexes using an identical chelator. Given the presence of two inner sphere water mols., important for MRI applications of the corresponding Gd3+ analogs, this result is particularly exciting and opens wide perspectives not only for NIR imaging based on Ln3+ ions but also for the design of combined NIR optical and MRI probes

Early alteration of the locus coeruleus in phenotypic variants of Alzheimer’s disease

International audienceNeuropathological studies showed early locus coeruleus (LC) neuronal loss associated with tauopathy in Alzheimer's Disease (AD). We used the LC signal intensity (LC-I) on 3T MRI to assess the LC integrity in AD (n = 37) and controls (n = 17). The LC-I was decreased in AD regardless of typical (amnesic) and atypical presentation (logopenic aphasia/visuo-spatial deficit), from the prodromal stage, and independently of the amyloid load measured by PiB-PET. The LC-I was correlated with memory performance of typical AD. This supports the pathophysiological model in which the LC plays a critical role in AD and may thus be a potential therapeutic target