Design of ordered bimetallic complexes,Part 2:Trans-1,2-cyclohexanediaminetetraacetate bimetallates

Summary Knowledge of the kinetic and thermodynamic behaviour of aqueous solutions containing two divalent cations andtrans-1,2-cyclohexanediaminetetraacetate has been used to design synthetic pathways to ordered bimetallic complexesPart 1: E. Escriva, A. Fuertes and D. Beltran,Transition Met. Chem.,9, 184 (1984).     

Synthesis of Enantiomeric Pure E-Nor-15-azayohimbines

A stereodivergent synthesis of enantiomerically pure E-nor-15-azayohimbines via condensation of tryptamine with derivatives of pyroglutamate 4 is reported. When the Pictet-Spengler reaction was induced in refluxing aqueous AcOH a nearly equimolar ratio of lactams 7 and 8 was obtained, whereas under kinetic control (TFA, room temperature) the trans-derivative 8 was the major product. In contrast, cyclization of amido acetal 12 with TsOH gave the cis-derivative 7 as preponderant component.     

Jules Horowitz Reactor: a high performance material testing reactor

The physical modelling of materials' behaviour under severe conditions is an indispensable element for developing future fission and fusion systems: screening, design, optimisation, processing, licensing, and lifetime assessment of a new generation of structure materials and fuels, which will withstand high fast neutron flux at high in-service temperatures with the production of elements like helium and hydrogen.JANNUS and other analytical experimental tools are developed for this objective. However, a purely analytical approach is not sufficient: there is a need for flexible experiments integrating higher scales and coupled phenomena and offering high quality measurements; these experiments are performed in material testing reactors (MTR). Moreover, complementary representative experiments are usually performed in prototypes or dedicated facilities such as IFMIF for fusion. Only such a consistent set of tools operating on a wide range of scales, can provide an actual prediction capability. A program such as the development of silicon carbide composites (600–1200 °C) illustrates this multiscale strategy.Facing the long term needs of experimental irradiations and the ageing of present MTRs, it was thought necessary to implement a new generation high performance MTR in Europe for supporting existing and future nuclear reactors. The Jules Horowitz Reactor (JHR) project copes with this context. It is funded by an international consortium and will start operation in 2014. JHR will provide improved performances such as high neutron flux (10¹⁵ n/cm²/s above 0.1 MeV) in representative environments (coolant, pressure, temperature) with online monitoring of experimental parameters (including stress and strain control). Experimental devices designing, such as high dpa and small thermal gradients experiments, is now a key objective requiring a broad collaboration to put together present scientific state of art, end-users requirements and advanced instrumentation. To cite this article: D. Iracane et al., C. R. Physique 9 (2008).     

Thomas rotation and Foucault pendulum under a simple unifying geometrical point of view

In this paper we show that there is a complete parallelism between the Foucault pendulum and the Thomas rotation phenomena by using the concept of parallel transport in a surface. In the case of the Foucault pendulum the surface is the ordinary sphere corresponding to the Earth sphere, whereas in the case of the Thomas rotation the surface is the pseudosphere corresponding to the space of relativistic velocities. Moreover, in both cases we use a simple method that reduces the problem to the parallel transport in a conical surface, and so, to the plane.     

Inelastic neutron scattering from isotactic polypropylene

We used inelastic neutron scattering to probe the low‐energy excitations in semicrystalline isotactic polypropylenes with different degrees of crystallinity. The contributions from the amorphous and crystalline regions to the total scattering intensity were extracted under the assumption of a weighted linear contribution of the two regions in a simplified two‐phase system. The resulting intensity from the amorphous region showed a peak at 1.2 meV that was in good agreement with the previously determined boson peak characteristic of atactic polypropylene. The possibility of a contribution to the boson peak region by longitudinal acoustic mode modes that are characteristic of semicrystalline polymers and appear in the same low‐frequency region is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2852–2859, 2001     

A quantitative electron microscopic study of the crystalline structure of ethylene copolymers

Quantitative thin-section electron microscope studies were made on compositional fractions of ethylene copolymers crystallized under several extreme conditions. The co-units chosen were such that the chains contained either ethyl, hexyl, or acetate side groups. Certain general features are independent of the chemical nature of the co-unit. It was found that up to about 2 mol % co-unit content lamellae are observed in all copolymers which were slowly cooled from the melt. The lateral dimensions of lamellae are not as large as in corresponding homopolymers and the lamellae are segmented. As the branch content increases the lamellae become shorter and eventually degrade into small crystallites. Within this broad outline of behavior, differences between the copolymer types are discerned and discussed. By comparison with the Raman LAM it is shown that quantitative values for the crystallite size distribution are obtained by the electron microscopy method used. Furthermore, when the specimen consisted of well-ordered lamellar stacks the degree of crystallinity obtained from the electron micrographs was in quantitative agreement with the enthalpy of fusion.     

Determination of titratable acidity and ascorbic acid in fruit juices in continuous-flow systems

Summary Two continuous-flow systems for the determination of titratable acidity and ascrobic acid in fruit juice samples are described. The assemblies permit on-line dialysis of analytes prior to the reaction step, thus improving selectivity and performing sample dilution. Flow systems are built with a channel carrying the donor phase (sample in both determinations) and another channel carrying an acceptor phase, both of them entering the dialyser. The outcoming stream transporting the dialysed sample fills the valve loop, permitting its injection into a carrier stream which continuously passes through the spectrophotometric detector. For the titratable acidity, acceptor phase and carrier are distilled water, the reagent merged with the carrier channel being a buffered solution of bromothymol blue (pH 7). The analytical signal obtained is then monitored at 616 nm. For ascorbic acid, the acceptor phase was a Fe(III) solution, which reacts with the dialysed analyte to form Fe(II). A buffered solution of o-phenanthroline (pH 4.5) is used as carrier, reacting with Fe(II) to give the analytical signal, which is monitored at 510 nm. Chemical and physical parameters are optimized for both systems. The analytical features of the determination are established. Finally, the proposed procedures are compared with the official volumetric AOAC methods for both parameters. The FIA methods turn out to be suitable for a rapid and accurate control of fruit juice samples, compared with the reference methods; additionally they compete advantageously with the volumetric methods in the case of turbid and highly coloured samples.     

Measurement of dissolved oxygen during red wines tank aging with chips and micro-oxygenation

Nowadays, micro-oxygenation is a very important technique used in aging wines in order to improve their characteristics. The techniques of wine tank aging imply the use of small doses of oxygen and the addition of wood pieces of oak to the wine. Considering the low dissolved oxygen (DO) levels used by micro-oxygenation technique it is necessary to choose the appropriate measurement principle to apply the precise oxygen dosage in wine at any time, in order to assure its correct assimilation. This knowledge will allow the oenologist to control and run the wine aging correctly.This work is a thorough revision of DO measurement main technologies applied to oenology. It describes the strengths and weaknesses of each of them, and draws a comparison of their workings in wine measurement. Both, the traditional systems by electrochemical probes, and the newest photoluminescence-based probes have been used. These probes adapted to red wines ageing study are then compared.This paper also details the first results of the dissolved oxygen content evolution in red wines during a traditional and alternative tank aging. Samples have been treated by three different ageing systems: oak barrels, stainless-steel tanks with small oak wood pieces (chips) and with bigger oak pieces (staves) with low micro-oxygenation levels. French and American oak barrels manufactured by the same cooperage have been used.     

Domain Analysis and Motif Matcher (DAMM): A Program to Predict Selectivity Determinants in Monosiga brevicollis PDZ Domains Using Human PDZ Data

Choanoflagellates are single-celled eukaryotes with complex signaling pathways. They are considered the closest non-metazoan ancestors to mammals and other metazoans and form multicellular-like states called rosettes. The choanoflagellate Monosiga brevicollis contains over 150 PDZ domains, an important peptide-binding domain in all three domains of life (Archaea, Bacteria, and Eukarya). Therefore, an understanding of PDZ domain signaling pathways in choanoflagellates may provide insight into the origins of multicellularity. PDZ domains recognize the C-terminus of target proteins and regulate signaling and trafficking pathways, as well as cellular adhesion. Here, we developed a computational software suite, Domain Analysis and Motif Matcher (DAMM), that analyzes peptide-binding cleft sequence identity as compared with human PDZ domains and that can be used in combination with literature searches of known human PDZ-interacting sequences to predict target specificity in choanoflagellate PDZ domains. We used this program, protein biochemistry, fluorescence polarization, and structural analyses to characterize the specificity of A9UPE9_MONBE, a M. brevicollis PDZ domain-containing protein with no homology to any metazoan protein, finding that its PDZ domain is most similar to those of the DLG family. We then identified two endogenous sequences that bind A9UPE9 PDZ with <100 μM affinity, a value commonly considered the threshold for cellular PDZ–peptide interactions. Taken together, this approach can be used to predict cellular targets of previously uncharacterized PDZ domains in choanoflagellates and other organisms. Our data contribute to investigations into choanoflagellate signaling and how it informs metazoan evolution.