Etude de la structure ramifiée du polyéthylène basse densité par viscosité et diffusion de la lumière de fractions issues de la chromatographie d'exclusion gpc

Fractions of high density polyethylene (PEhd) and low density polyethylene (PEld) obtained from gel permeation chromatography were studied by viscometry and light scattering. The variations of the intrinsic viscosity [η], the molecular weight M?_w, and the radius of gyration R_g for PEhd and PEld were compared with one another and the relationships [η] vs M and R_g vs. M for PEhd were established. The dependence of structural parameters g = (R_g²)_branch/(R_g²)_linear and g′ = [η]_branch/[η]_linear on the molecular weight was determined for three samples of PEld.     

Influence de la nature du solvant sur les propriétés physico-chimiques des polyamides aromatiques en solution diluée

The dilute solution properties of some aromatic polyamides like: poly(1,4-phenyleneterephthalamide), (or poly(imino-1,4-phenyleneiminoterephthaloyl)), poly(parabenzamide), (or poly(imino-1,4-phenylenecarbonyl)), and some chlorinated derivatives of poly(1,4-phenyleneterephthalamide) have been investigated. Solvents like 96% sulfuric acid, methanesulfonic and chlorosulfonic acid and also N,N-dimethylacetamide + LiCl have been used. An increase of the intrinsic viscosity and of the exponent of the viscosity law when we use methanesulfonic and chlorosulfonic acids has been observed and is explained by an increase of the rigidity and hydrodynamic diameter of the molecule. The measurements of the radius of gyration, and optical anisotropy confirm this. In N,N-dimethylacetamide, the molecules of poly(parabenzamide) exhibit an association which depends on parameters such as percentage of LiCl and temperature.     

La vérification ultime au lit du malade: résultats d''une enquête nationale sur les réactifs et dispositifs utilisés en France

The national reference Center for blood groups checked samples of reagents and devices used in France for a definitive verification of pretransfusion ABO tests performed at the patient's bedside, as defined by French health authority regulations. The results of an initial inquiry was published in 1991. The new study shows no significant improvement of the quality of reagents and devices. This is a major concern considering the importance of ABO incompatibility in severe hemolytic transfusion reactions.     

Relation entre les paramètres diélectriques et la cinétique de réaction de polymérisation en phase liquide

The aim of this study is to characterize the state of progress of a polymerization reaction by a non-destructive electric method. For this purpose, results deduced from measurements of complex permittivity are compared with those obtained from chemical analysis of the reaction mixture at successive instants of its evolution. Chemical analysis allows the rate of disapperace of expoxy groups during the polymerization reaction in liquid phase to be evaluated. Exploitation of electric measurements of complex relative permittivity enables the evolution of the polymerization to be followed from both the product of the epoxy group concentration and the square of the mean value of their dipole moment and also from the most probable relaxation time of this dipole. As expected, the variations of relaxation time are closely correlated to those of the viscosity of the medium.     

Etude par spectroscopie infrarouge d'alcanes ramifiés et de polymères modèles — application à la determination du taux de ramifications dans les polyéthylènes basse densité

The absorption band at 1378 cm^?1 was used for the quantitative determination of branching in polyethylene. Using various models with different alkyl groups (12-alkyltriacosanes, 11,20-dialkyltriacontances, alkylcyclohexanes, homopolymers), new absorption coefficients, depending on their branching, were obtained. The degrees of branching of a series of copolymers deriving from α-olefins (15 compounds) determined by infrared spectroscopy with the new coefficients and by ¹³C NMR spectroscopy were compared.     

Diagnostic moléculaire des infections respiratoires à entérovirus : apport de la PCR et du génotypage pour une meilleure approche de la circulation des souches en Basse-Normandie au cours de l’année 2008

The PCR assays are currently used in diagnosis of enterovirus (EV) meningitis. Nevertheless, the use of molecular diagnosis of EV should be investigated in respiratory tract infections (RTI).

Objectives

To perform enterovirus molecular diagnostic tools, PCR and genotyping, in nasal samples for diagnostic and epidemiologic purposes.

Methods

During 2008, 3612 nasal specimen (NS) were studied by IFD and MRC5 culture. Next, we realised successively viral isolation on HuH7 culture (for NS negative by IFD assay) and a duplex PCR enterovirus-rhinovirus for the 816 HuH7 positive supernatants. Furthermore, 327 NS collected from neonates were systematically tested by a real-time RT-PCR. This assay was used in routine for EV diagnosis setting in cerebrospinal fluid. Enterovirus genotyping was then performed for the 68 positive supernatants.

Results

Thirty-five NS (0.97%) were positive for EV by culture (MRC5). A combination of both PCR assays, PEVRV and PEV, allowed an additional identification of 41 EV, eight EV-RV and 12 RV, increasing the number of positive to 96 NS (2.6%). Among the neonates, 32 NS (11.3%) were positive for EV by PEV. Of the 98 NS tested by the two PCR assays (PEV and PEVRV), 27 were positive and we detected 10 EV, five EV-RV and 12 RV. From January to December 2008, the circulation of EV showed the usual peak in June-July when a small outbreak of aseptic meningitis occurred and an additional autumnal peak corresponding to respiratory tract infections. Five main serotypes were isolated: 19 EV68 (29.7%), 12 CB3 (18.7%), nine E3 (14,1%), six CA9 (9.4%) and six CB1 (9.4%); the 19 EV68 were isolated in October-November and 17/19 (89.5%) of positive patients were hospitalised for severe respiratory diseases.

Conclusion

The use of molecular screening techniques (PCR assays and genotyping) on nasal samples collected from patients with respiratory infections allowed a prospective, effective and precise identification of circulating strains.