Continuous simulation of storm processes

Extremes - Storm processes constitute prototype models for spatial extremes. They are classically simulated on a finite number of points within a given domain. We propose a new algorithm that...     

Intramolecular Scrambling of Aryl Groups in Organopalladium Complexes [ArPd(PPh3)2]+: From Solution to the Gas Phase,Back Again,and In‐Between

Gas‐phase experiments are used to probe the intramolecular scrambling of aryl groups between palladium and phosphorus in organopalladium complexes, [ArPd(PPh₃)₂]⁺, generated by means of electrospray ionization (ESI). To this aim, ESI mass spectrometry, including tandem mass spectrometric experiments, were carried out on deuterated, non‐deuterated, and substituted [ArPd(PPh₃)₂]⁺ complexes. The fragment ions obtained from the deuterated parent ions clearly show the occurrence of intramolecular scrambling between the aryl group bound to palladium and the phenyl groups of the phosphine in the gas phase. Fragmentation pathways, supported by a statistical model, are proposed to explain these migrations and the implications for the condensed‐phase chemistry are probed experimentally by using ESI mass spectrometry.     

Synthesis of potential prodrug systems for reductive activation. Prodrugs for anti-angiogenic isoflavones and VEGF receptor tyrosine kinase inhibitory oxindoles

A number of potential prodrug systems for reductive activation have been investigated. The prodrug systems chosen for the study were the 2-nitrophenylacetyl, 3-methyl-3-(3,6-dimethyl-1,4-benzoquinon-2-yl)butanoyl and 4-nitrobenzyl groups, readily attached to acidic OH or NH groups in drug molecules, and released upon bioreductive activation. The drug molecules studied were the naturally occurring isoflavone biochanin A, an inhibitor of VEGF-induced angiogenesis, and the pyrrolylmethylidenyl oxindole SU5416 (semaxanib) and its 6-hydroxy derivative, inhibitors of VEGF receptor tyrosine kinase. Following coupling the prodrug system to the drug, the compounds were evaluated chemically and biologically. Under chemical reducing conditions, the 3-methyl-3-(3,6-dimethyl-1,4-benzoquinon-2-yl)butanoic acid based prodrugs appear to fragment the most efficiently, followed by the 2-nitrophenylacetate esters with the 4-nitrobenzyl ethers being the least efficient. The potentially pro-anti-angiogenic compounds were also assayed for their ability to block VEGF-induced angiogenesis in HUVECS in comparison to the free agents. Control compounds that cannot be activated under bioreductive conditions are less potent than the free drug, whereas many of the potential prodrugs not only exhibit a dose response, but appear at least equipotent with the free drug.     

Synthesis and X-ray Structure of (2R, 3R, 4R, 5R)-3,4,5-Tris-Benzyloxy-2-Benzyloxymethyl-Piperidin-1-ol, the N-Hydroxy-Analogue of 2,3,4,6-Tetra-O-Benzyl-1-Deoxymannojirimycin

Abstract  The title compound 8 was obtained for the first time by hydride-mediated reduction of the d-fructose-derived nitrone 9. The N-hydroxy piperidine 8 is a precursor of the N-hydroxy analogue of DMJ, a potent inhibitor of α-mannosidases. It was isolated as colorless crystals (triclinic, P1 space group) exhibiting the following cell parameters: a = 9.947(2) ?; b = 12.155(2) ?; c = 13.864(5) ?; α = 100.98(3)°; β = 97.94(2)°; γ = 109.50(1)°. The X-ray analysis of a monocrystal of 8 allowed confirmation of its relative configurations and showed the anti orientation of its N-hydroxy group. This structural feature should be useful for considering the interaction of N-hydroxy iminosugars with the recognition site of carbohydrate processing enzymes. Index Abstract  The title compound 8 was prepared for the first time by hydride-mediated reduction of the d-fructose-derived nitrone 9. Compound 8 is a precursor of the N-hydroxy analogue of DMJ, a potent inhibitor of α-mannosidases. The X-ray analysis allowed confirmation of the relative configurations of 8 and showed the anti orientation of its N-hydroxy group. This structural feature will be useful for considering the interaction of N-hydroxy-iminosugars with specific biological targets.      

Cellular and molecular responses of E. fetida c?lomocytes exposed to TiO2 nanoparticles

An in vitro approach using c?lomocytes of Eisenia fetida was investigated to evaluate toxicity of TiO₂ nanoparticles. C?lomocytes were exposed to well-dispersed suspension of small aggregates (130?nm) of TiO₂ nanoparticles (1?C25???g/ml) during 4, 12 and 24?h. Intracellular localisation suggested that the main route of uptake was endocytosis. Cellular responses showed that TiO₂ nanoparticles were not cytotoxic and had no effect on phagocytosis at any of the four concentrations for each time tested. Concerning molecular responses, an increase of fetidin and metallothionein mRNA expression was observed starting from 4?h of exposure. In contrast, expression of coelomic cytolytic factor mRNA decreased for 10 and 25???g/ml after 4?h. Superoxide dismutase, catalase and glutathione-S-transferase expression were not modified suggesting that oxidative stress was not induced by TiO₂ in our experimental conditions. This in vitro approach showed that TiO₂ nanoparticles were taken up by c?lomocytes and they could modify the molecular response of immune and detoxification system.     

Dimensional instabilities of polyester and polyolefin films as origin of delamination in laminated multilayer

Polymer–metal multilayer films provide attractive barrier properties to air and water, provided by several films bonded together. Used in high temperature and humidity, the delamination is the most common degradation mechanism. This mode of failure is critical because it leads to premature loss of barrier properties. Therefore, delaminations limit the use of multilayer in these conditions. Delamination should result from interfacial shear stress, and plausibly from difference of shrinkage of the films, due to relaxation of internal stress. A method was developed for measuring the deformations of each individual film. The measurements indicate that the shrinkage is anisotropic and controls the decohesion in the multilayer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 309–319