An efficient synthesis of new thiazolopyrimidinones under microwave irradiation

7‐Chloromethyl‐6‐nitro‐5H‐thiazolo[3,2‐a]pyrimidin‐5‐one ( 2 ) is obtained by cyclocondensation of 2‐aminothiazole with ethyl 4‐chloroacetoacetate. This product was shown to react with various nitronate or malonate anions under microwave irradiation to give potentially bioactive 6‐nitro‐5H‐thiazolo[3,2‐a]pyrimidin‐5‐ones. Extension to other anions centered on S atom allows for the generalization this synthetic procedure.     

Supramolecular Complexes of Multivalent Cholesterol‐Containing Polymers to Solubilize Carbon Nanotubes in Apolar Organic Solvents

Copolymers of 2‐ethylhexyl acrylate (EHA) and cholesteryloxycarbonyl‐2‐hydroxymethacrylate (CEM) were prepared by reversible addition–fragmentation chain‐transfer (RAFT) polymerization. Supramolecular complexes of these copolymers with carbon nanotubes (CNTs) were soluble in THF, toluene, and isooctane. The colloidal solutions remained stable for months without aggregation. The rationale for the choice of CEM was based on the high adsorption energy of cholesterol on the CNT surface, as computed by DFT calculations. Adsorption isotherms were experimentally measured for copolymers of various architectures (statistical, diblock, and star copolymers), thereby demonstrating that 2–5 cholesterol groups were adsorbed per polymer chain. Once the supramolecular complex had dried, the CNTs could be easily resolubilized in isooctane without the need for high‐power sonication and in the absence of added polymer. Analysis by atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicated that the CNTs were devoid of bundles. The supramolecular complexes could also be employed in an inverse emulsion polymerization of 2‐hydroxyethylmethacrylate (HEMA) in isooctane and dodecane, thereby leading to the formation of a continuous polymeric sheath around the CNTs. Thus, this technique leads to the formation of very stable dispersions in non‐polar organic solvents, without altering the fundamental properties of the CNTs.     

A Piecewise Line-Search Technique for Maintaining the Positive Definitenes of the Matrices in the SQP Method

A technique for maintaining the positive definiteness of the matrices in the quasi-Newton version of the SQP algorithm is proposed. In our algorithm, matrices approximating the Hessian of the augmented Lagrangian are updated. The positive definiteness of these matrices in the space tangent to the constraint manifold is ensured by a so-called piecewise line-search technique, while their positive definiteness in a complementary subspace is obtained by setting the augmentation parameter. In our experiment, the combination of these two ideas leads to a new algorithm that turns out to be more robust and often improves the results obtained with other approaches.     

Chaos break and synchrony enrichment within Hindmarsh–Rose-type memristive neural models

Nonlinear Dynamics - The fluctuation of ions concentration across the cell membrane of neuron can generate a time varying electromagnetic field. Thus, memristors are used to realize the coupling...     

Mean-Variance Hedging Under Multiple Defaults Risk

We solve a mean-variance hedging problem in an incomplete market where multiple defaults can occur. For this purpose, we use a default-density modeling approach. The global market information is formulated as a progressive enlargement of a default-free Brownian filtration, and the dependence of the default times is modelled using a conditional density hypothesis. We prove the quadratic form of each value process between consecutive default times and recursively solve systems of coupled quadratic backward stochastic differential equations (BSDEs). We demonstrate the existence of these solutions using BSDE techniques. Then, using a verification theorem, we prove that the solutions of each subcontrol problem are related to the solution of our global mean-variance hedging problem. As a byproduct, we obtain an explicit formula for the optimal trading strategy. Finally, we illustrate our results for certain specific cases and for a multiple defaults case in particular.     

Preparation and electrical properties of dense micro-cermets made of nickel ferrite and metallic copper

Dense micro-cermets made of nickel ferrites and copper micrometric particles were obtained from partial reduction under hydrogenated atmosphere at 350 °C of mixed copper nickel ferrites, and sintering in nitrogen at 980 °C. The small copper particles are homogeneous in size and well dispersed in the spinel oxide matrix. No exudation of copper metal was observed after sintering. The micro-cermets prepared are semi-conducting materials with electrical conductivity lying from 44 to 130 S/cm at 980 °C. Their overall characteristics make them interesting for inert anodes dedicated to aluminium electrolysis in melted cryolite.     

A glimpse at ten years of microwaves and IR spectroscopy on high temperature superconductors

The different technical approaches are considered mostly to compare the accuracy attainable in microwaves to Far IR where new resonant tchniques have been developped. It is possible to use the fringes of the observed spectra to get directly the London penetration length. However in the present state of the Art there is more accuracy to use a two-fluid model with at least one Mid-IR oscillator, and a strategy is possible to fit separately the different parameters. The different results are reviewed and compared to the microwaves data. There is a good accordance, except perhaps for the power law-giving the concentration of quasiparticles in the superconductive phase. For a thin film of YBCO devoid of grain-boundaries (no twins), a θ⁴ law is found instead of a θ^1.5 law for an ordinary film. It should be highly valuable that both microwaves and Far-IR data should be taken on the same sample. presented at the 22nd International Conference on Infrared and Millimeter Waves, July 20–25, 1997, Wintergreen, Virginia 22958 USA.     

High-throughput age synchronisation of Caenorhabditis elegans

We present a passive microfluidic strategy for sorting adult C. elegans nematodes on the basis of age and size. The separation mechanism takes advantage of phenotypic differences between 'adult' and 'juvenile' organisms and their behaviour in microfluidic architectures. In brief, the microfluidic device allows worms to sort themselves in a passive manner.