C(2)-symmetric Sc(III)-complexes as chiral Lewis acids. Catalytic enantioselective aldol additions to glyoxylate esters

Cationic Lewis acid complexes [Sc(pyridyl-bis(oxazolinyl)](Cl(2))SbF(6) 1a and 1b catalyze aldol reactions with ethyl glyoxylate with enantioselectivities ranging from 90 to 99% ee and syn reaction diastereoselections ranging from 90:10 to 95:5. [reaction: see text]     

Etude du changement de phase solide-liquide en relation avec la stabilite thermique des formes polymorphes et pseudopolymorphes du lorazepam et identification spectrale

Thermal decomposition of lorazepam begins by lose of a water mole between two groups NH-OH and occurs at different temperatures depending on the formes of polymorphs. Melting temperature of a form can be determined only if it is below that of decomposition.The thermoanalytical and spectral study of lorazepam commercial drugs (a) and (b) recrystallisation product at 20°C in benzine (c), in carbon tetrachlorid (d), in acetonitrile (e) were carried out.Thermal behaviour, RX diffraction, IR spectroscopy allow us to identify polymorph (a, b, c) and two solvates (d and e). The solvates stoechiometry (d and e) has been determined by thermogravimetry (3-2) d, (2-1) e, and confirmed by magnetic nuclear resonance for (e).

Nous exprimons nos vifs remerciements à Madame Eliane Toreilles, Directeur de recherche au CNRS (Laboratoire de Chimie Organiques UA 458 CNRS, Ecole Nationale Supérieure de Chimie de Montpellier) pour sa collaboration personnelle en spectroscopie.     

Etude thermoanalytique de substances psychotropes. IV. Lorazepam et oxazepam

We have studied the thermal behaviour of lorazepam (a) and oxazepam (b), defined the crystal form and the thermal stability. After recrystallization in several solvents under known temperature and pressure conditions the thermoanalytical study of samples has shown polymorphs for (a) and (b) and pseudopolymorphs for (a), (a) Polymorphs are I (t_f = 183°C), II (T_f =173°C), III (T_f =170°C). IV (_Tf, =163°C), V (_Tf =158°C), VI (_Tf, =153°C), and seven pseudopolymorphs, three of which are clathrate type of 1:1 molar composition with propanol, chloroform and isopentanol. We have found eight polymorphs for (b): I (T_f = 207°C), II (T_f=201°C), III (T_f=193°C), IV (T_f=189°C). A, B, C and D show a solid ? solid transition. Commercial samples of (a) are form I, those of (b) are form II.A spectral and dissolution kinetic study completes the thermoanalytical results in relation to biological availability.     

Synthesis and characterization of nanoapatites organofunctionalized with aminotriphosphonate agents

Organofunctionalized apatite nanoparticles were prepared using a one step process involving dissolution/precipitation of natural phosphate rock and covalent grafting of nitrilotris(methylene)triphosphonate (NTP). The synthesized materials were characterized by Brunauer–Emmett–Teller (BET) surface measurement, thermogravimetry, inductively coupled plasma emission spectroscopy (ICP–ES), elemental analysis, multinuclear solid state cross-polarization/magic angle spinning (CP/MAS) and single-pulse NMR spectroscopy, transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDXA). After grafting BET measurements yielded particle specific surface areas ranging from 88 to 193 m² g^?1 depending on the grafted phosphonate. The results show that the surfaces of the nanoapatite particles can be covered with functional groups bound through a variable number of R–P–O–Ca bonds to render them organoapatites.     

Comportement thermique et etude des melanges binaires: ethinyl-estradiol — lynestrenol,ethinyl-estradiol — acetate de chlormadinone par thermomicroscopie,analyse calorimetrique differentielle et mesure de la transparence

Study of the thermal behaviour of the active ingredients and establishment of the conditions for the eventual formation of the most stable polymorphic forms permitted the phase diagrams to be obtained for ethynyl-estradiol — lynestrenol (A) and ethynyl-estradiol — chlormadinone acetate (B) mixtures by means of thermomicroscopy, differential scanning calorimetry and the transparency method. The compositions of the eutectic (for A and B) and peritectic points (B) and that of a defined compound (B) were determined from a further physicochemical study, particularly as regards solubility in relation to bioavailability.

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Zusammenfassung Eine Untersuchung des thermischen Verhaltens der aktiven Ingredienten und die Ermittlung der Bedingungen für die eventuelle Bildung der stabilsten polymorphen Formen ermöglichte, Phasendiagramme für Mischungen von Ethynyl-estradiol-Lynestrenol (A) und Ethynylestradiol-Chlormadinon-acetat (B) mittels Thermomikroskopie, DSC und der Transparenzmethode zu bestimmen. Die Zusammensetzung am eutektischen (für A und B) und peritektischen (für B) Punkt und die einer definierten Verbindung (B) wurden in Hinsicht auf eine physikalisch-chemische Untersuchung bestimmt, die sich im besonderen mit der Beziehung zwischen Löslichkeit und der therapeutischen AktivitÄt des Medikamentes (der BiodisponibilitÄt) befa\t.

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Nous adressons nos plus vifs remerciements eu Laboratoire Cassenne qui a eu l'amabilité de nous procurer les échantillons d'ethinyl-estradiol (lot n 4 F 0353) et d'acétate de chlormadinone (lot n B 5 F 5002).Nous remercions le Laboratoire Organon qui a eu l'obligeance de nous procurer l'échantillon de lynestr6nol (lot 2/4102) par I'intermédiaire du Docteur Marie Mayer.     

Design and implementation plan for indirect-drive highly nonlinear ablative Rayleigh–Taylor instability experiments on the National Ignition Facility

In the context of National Ignition Facility Basic Science program we propose to study on the NIF ablative Rayleigh–Taylor (RT) instability in transition from weakly nonlinear to highly nonlinear regimes. Based on the analogy between flame front and ablation front, highly nonlinear RT instability measurements at the ablation front can provide important insights into the initial deflagration stage of thermonuclear supernovae of type Ia. NIF provides a unique platform to study the rich physics of nonlinear and turbulent mixing flows in High Energy Density plasmas because it can accelerate targets over much larger distances and longer time periods than previously achieved on the NOVA and OMEGA lasers. In one shot, growth of RT modulations can be measured from the weakly nonlinear stage near nonlinear saturation levels to the highly nonlinear bubble-competition, bubble-merger regimes and perhaps into a turbulent-like regime. The role of ablation on highly-nonlinear RT instability evolution will be comprehensively studied by varying ablation velocity using indirect and direct-drive platforms. We present a detailed hydrocode design of the indirect-drive platform and discuss the implementation plan for these experiments which only use NIF diagnostics already qualified.     

Characterization by Raman microspectrometry of residual compressive stresses induced by resin curing in single filament composite samples

The present work concerns monofilament composite samples used in the pull-out test to quantify the effect of different fibre surface treatments on the adhesion of a high modulus polyethylene in a polyester resin. Optical observations revealed local deformations induced by a compressive stress generated in the fibre by the resin shrinkage during the curing. The sensitivity of the polyethylene Raman peak at 1130 cm⁻¹ to elastic strain has been used to characterize the local compression state still present in the fibre after the curing. The results show residual stresses varying along the fibre embedded length up to a level depending on the applied surface treatment i.e. on the degree of adhesion between the fibre and the resin. This is consistent with the localization and the morphologies of shear bands observed in the samples. More the Raman microspectrometry has been used to determine the tensile stress profile along the embedded part of the fibre when its free part is stretched. Corrected of the initial compression state this profile represents the stress transfer effectively realized from the fibre to the resin for different adhesion conditions. Its knowledge is very useful to clarify the interface damage and pull-out mechanisms.