High frequency wave packets for the Schrödinger equation and its numerical approximations

We build Gaussian wave packets for the linear Schrödinger equation and its finite difference space semi-discretization and illustrate the lack of uniform dispersive properties of the numerical solutions as established in Ignat and Zuazua (2009) [6]. It is by now well known that bigrid algorithms provide filtering mechanisms allowing to recover the uniformity of the dispersive properties as the mesh size goes to zero. We analyze and illustrate numerically how these high frequency wave packets split and propagate under these bigrid filtering mechanisms, depending on how the fine grid/coarse grid filtering is implemented.     

Electrosynthesis of a Bis-Ketenedithioacetal Disulphide Derivative From 1-Phenyl-3-Methyl-4-Butyldithiocarboxylate-5-Pyrazolone Using a Glassy Carbon Electrode

The electrooxidation of 1-phenyl-3-methyl-4-butyldithiocarboxylate-5-pyrazolone 1 has been studied in ethanol/water solution, using a glassy carbon electrode surface. The electrochemical and spectroscopic data are in agreement with a bis-ketenedithioacetal disulphide compound 2 as the only product of the reaction.     

Transforming Computed Energy Landscapes into Experimental Realities: The Role of Structural Rugosity

We exploit the possible link between structural surface roughness and difficulty of crystallisation. Polymorphs with smooth surfaces may nucleate and crystallise more readily than polymorphs with rough surfaces. The concept is applied to crystal structure prediction landscapes and reveals a promising complementary way of ranking putative crystal structures.     

Water‐Filtered Infrared Radiation Decreases the Generation of Photodermatoses Dependent on Ultraviolet and Visible Radiation

The potential role of infrared radiation in photodermatoses has received very little attention, even though the main sources of radiation used for photobiological studies (UVA, UVB and visible light) include infrared radiation. The objective of the work was to assess whether infrared radiation is involved in the development of skin lesions in patients with different types of photodermatoses. Twenty patients with different photodermatoses were exposed to UVA, UVB and visible radiation using a high‐pressure mercury UVA lamp, a fluorescent broadband UVB lamp, a tungsten bulb and a slide projector for visible radiation. Part of the radiation emitted by these lamps was water‐filtered to block infrared radiation above 1300 nm. All 20 patients developed lesions when exposed to different light sources used for phototest. When exposed to same sources without infrared radiation, 17 patients (85%) did not develop any lesions and the other three (15%) developed less severe lesions than in the area exposed to unfiltered light. Our results show that infrared radiation was necessary for the development of skin lesions in 85% of the patients with photodermatoses in our study. We believe that infrared radiation studies should be included in standard photobiology protocols.     

SPANamine derivatives in the catalytic asymmetric α-fluorination of β-keto esters

The use of C₂-symmetric enantiopure nitrogen ligands in the asymmetric catalytic α-fluorination of β-ketoesters is described. SPANamine 1 in the presence of nickel salts gives up to 63% ee in the fluorination of tert-butyl 2-oxocyclopentanecarboxylate with N-fluorosuccinimide (NFSI). The same enantioselectivity is obtained when SPANamine 1 is used as an organocatalyst, although the reaction is much slower.     

Structure of a spin-crossover Fe(II)–1,2,4-triazole polymer complex dispersed in an isotactic polystyrene matrix

Isotactic polystyrene (i-PS) was employed as a matrix to disperse a metallo-organic polymer of [Fe(II) (4-octadecyl-1,2,4-triazole)₃(ClO₄)₂] in order to obtain novel functional materials exhibiting thermal spin-crossover transition. A detailed investigation of the structure of the metallo-organic polymer and metallo-organic polymer/iPS blends has been carried out by DSC, WAXD and SAXS techniques as a function of temperature and metallo-organic polymer/iPS proportion.The results obtained confirm on the one hand that a structural transition associated with a change in the magnetic susceptibility of the metallo-organic polymer is preserved in the presence of i-PS. This transition was found to be associated to both, an inter-conversion of lamellar structures into hexagonal structures and to an increase of inter-sheet distances within the lamellar structures in metallo-organic polymer films prepared by casting from toluene solutions. On the other hand, an increase of the degree of crystallinity of the iPS is observed in the presence of the metallo-organic polymer which suggests some nucleating effect of the metallo-organic polymer in the crystallization of isotactic polystyrene.     

Alkyldithiocarboxylation of 3-hydroxy-1-phenyl-2-pyrazolin-5-one

4-Alkyldithiocarboxylate-3,5-dihydroxy-1-phenylpyrazoles 2, are prepared in good yield by the reaction of 3-hydroxy-1-phenyl-2-pyrazolin-5-one 1 with sodium acetate in dimethylformamide (DMF), carbon disulfide and alkyl halides.     

An octanol hinge opens the door to water transport

Despite their prevalent use as a surrogate for partitioning of pharmacologically active solutes across lipid membranes, the mechanism of transport across water/octanol phase boundaries has remained unexplored. Using molecular dynamics, graph theoretical, cluster analysis, and Langevin dynamics, we reveal an elegant mechanism for the simplest solute, water. Self-assembled octanol at the interface reversibly binds water and swings like the hinge of a door to bring water into a semi-organized second interfacial layer (a “bilayer island”). This mechanism is distinct from well-known lipid flipping and water transport processes in protein-free membranes, highlighting important limitations in the water/octanol proxy. Interestingly, the collective and reversible behavior is well-described by a double well potential energy function, with the two stable states being the water bound to the hinge on either side of the interface. The function of the hinge for transport, coupled with the underlying double well energy landscape, is akin to a molecular switch or shuttle that functions under equilibrium and is driven by the differential free energies of solvation of H₂O across the interface. This example successfully operates within the dynamic motion of instantaneous surface fluctuations, a feature that expands upon traditional approaches toward controlled solute transport that act to avoid or circumvent the dynamic nature of the interface.

Despite their pharmacological relevance, the mechanism of transport across water/octanol phase boundaries has remained unexplored. Octanol molecular assemblies are demonstrated to reversibly bind water and swing like the hinge of a door.