An intramolecular journey of a carboxyl group around 1,2-dihydropyridines: multisite δ- versus γ-lactonization reactions

In contrast to substituted 4-acetic acid 1,4-dihydropyridines, giving only δ-lactones upon intramolecular reactions, 2-substituted 1,2-dihydropyridines led, besides to δ-lactones, also to new, structurally interesting γ-lactones as the result of a bromine-induced carbon-carbon double bond ‘Umpolung’.     

Evaluation of DNA damage and cytotoxicity of polyurethane-based nano- and microparticles as promising biomaterials for drug delivery systems

The in vitro cytotoxicity and DNA damage evaluation of biodegradable polyurethane-based micro- and nanoparticles were carried out on animal fibroblasts. For cytotoxicity measurement and primary DNA damage evaluation, MTT and Comet assays were used, respectively. Different formulations were tested to evaluate the influence of chemical composition and physicochemical characteristics of particles on cell toxicity. No inhibition of cells growth surrounding the polyurethane particles was observed. On the other hand, a decrease of cell viability was verified when the anionic surfactant sodium dodecyl sulfate (SDS) was used as droplets stabilizer of monomeric phase. Polyurethane nanoparticles stabilized with Tween 80 and Pluronic F68 caused minor cytotoxic effects. These results indicated that the surface charge plays an important role on cytotoxicity. Particles synthesized from MDI displayed a higher cytotoxicity than those synthesized from IPDI. Size and physicochemical properties of the particles may explain the higher degree of DNA damage produced by two tested formulations. In this way, a rational choice of particles’ constituents based on their cytotoxicity and genotoxicity could be very useful for conceiving biomaterials to be used as drug delivering systems.     

Emission control in broad periodic waveguides and critical coupling

Broad periodic channel waveguides, with a corrugation on their edge, exhibit a remarkable structure in their dispersion diagram, in the form of stripes of minigaps, whose hyperbolic shape is demonstrated. Around the Brillouin zone edge, the contra-directional feedback borrows the geometry of Littrow diffraction. Spontaneous emission from a large subset of modes then acquires a strong modulation. Lasing on these modes, the so-called “Littrow lasing”, offers also the lowest lasing threshold of the open resonator system. Reviewing our recent studies of this system, we discuss slow light and critical coupling phenomena: for a properly adjusted contra-directional coupling, the bands become substantially flat in a sizable area of the dispersion diagram, opening various perspectives. The band engineering tools to master these phenomena and the physical implications in other domains are briefly reviewed.     

On risk averse competitive equilibrium

We discuss risked competitive partial equilibrium in a setting in which agents are endowed with coherent risk measures. In contrast to social planning models, we show by example that risked equilibria are not unique, even when agents’ objective functions are strictly concave. We also show that standard computational methods find only a subset of the equilibria, even with multiple starting points.     

Anisotropic linear-polarization luminescence in CdTe/CdMnTe quantum wires

We theoretically studied anisotropic linear optical polarization properties in CdTe/Cd_0.75Mn_0.25Te quantum wires (QWRs) by using the multi-band effective mass method. In this QWR system, the spatial distribution of the Mn composition influences both the lateral quantum confinement and the sp-d exchange coupling. The calculated expectation value of the hole spin demonstrates that the hole spin is reoriented along the external magnetic field when applying the magnetic field parallel to the QWR. The hole-spin reorientation causes anisotropic behavior in the Zeeman shift and the linearly polarized optical transitions, which sensitively depends on the Mn spatial distribution. Such characteristic features appeared in the QWR have been demonstrated experimentally and compared with the theoretical calculations.     

A swept intersection‐based remapping method for axisymmetric ReALE computation

We use here a reconnection ALE (ReALE) strategy to solve hydrodynamic compressible flows in cylindrical geometries. The main difference between the classical ALE and the ReALE method is the rezoning step where we allow change in the topology. This leads for ReALE to a polygonal mesh, which follows more efficiently the flow. We present here a new displacement of generators in order to keep the Lagrangian features, which are usually lost using ALE with fixed topology. The reconnection capability allows to deal with complex geometries and high‐vorticity problems contrary to ALE method. The main difficulty of ReALE is the remapping step where we have to remap physical variables on a mesh with a different topology. For this step, a new remapping method based on a swept intersection algorithm has been developed in the case of planar geometries. We present here the extension of the swept intersection‐based remapping method to cylindrical geometries. We demonstrate that our method can be applied to several numerical examples up to problem representative of hydrodynamic experiments. Copyright © 2015 John Wiley & Sons, Ltd.