Sequential regio and chemoselective cross-coupling reactions by means of O-tri-isopropylsulfonate of 4-bromo-pyridazine 3,6-dione

Regioselective desymmetrization of 4-substituted pyridazin-3,6-diones using sterically hindered 2,4,6-triisopropylphenyl-sulfonylchloride allowed efficient sequential palladium cross-coupling reactions.     

Femtosecond to Subnanosecond Multistep Calcium Photoejection from a Crown Ether‐Linked Merocyanine

Photoinduced calcium release from the crown ether‐linked merocyanine DCM–crown is reexamined by femtosecond transient absorption spectroscopy with sub‐100 fs time resolution. Photodisruption of the bond linking the cation to the nitrogen atom shared by the crown and the chromophore is found to take place in 130 fs. Confirming our previous reports, the photoinduced intraligand charge transfer is observed in the picosecond regime but kinetics involving three‐components (1 ps, 8 ps and 77 ps), together with a 56 ps stimulated‐emission time‐resolved red shift, are found in the present study. Both delayed intraligand charge transfer and cation release are assumed to occur in this time range due to repulsion effects between the positively charged nitrogen of the crown ether moiety and the cation. In the subnanosecond regime, a 670 ps time‐resolved red shift of the stimulated‐emission spectrum of the charge‐transfer state, similar to the shift previously observed with Sr²⁺, demonstrates the motion of the cation away from the crown to the bulk. A thorough examination of the present data allows us to conclude that calcium ion is photoejected to the bulk in a multistep process.     

Changes in radioxenon observations in Canada and Europe during medical isotope production facility shut down in 2008

Radioxenon concentration data collected at International Noble Gas Experiment (INGE) monitoring sites in the Northern Hemisphere are demonstrably impacted by emissions from medical isotope (MI) production facilities at Chalk River (CRL), Ontario and Fleurus, Belgium [Saey, J Environ Radioact 100(5):396–406, 2009]. Temporary cessation at these European MI facilities in the latter half of 2008 allowed an opportunity to assess the relative impact of distant MI facilities at INGE monitoring stations. In particular, the concentration distributions at the measurement sites and calculated sensitivities to the putative emission locations through atmospheric transport modelling (ATM) of meteorological Source Receptor Sensitivity (SRS) computations were used to study MI impacts.     

Novel valuable fluorine free copper(I) precursors for copper chemical vapor deposition

Novel fluorine free (β-diketonate)Cu^(I)BTMSA precursors (where BTMSA is bis(trimethylsilyl) acetylene) were prepared in good yield (63–80%) by a simple acid–base reaction. The starting β-diketone structure was modified for tailoring physico-chemical properties of synthesized precursors. High volatile, relative thermally stable and low-melting precursors were prepared when asymmetric β-diketones were used. By using the (1-(cyclobutyl)-1,3-butandionate)Cu^(I)BTMSA precursor, highly pure, compact and smooth copper films were deposited on Ta/TaN substrates at deposition temperatures as low as 150 °C.     

Simulation of primary atomization with an octree adaptive mesh refinement and VOF method

We present different simulations of primary atomization using an adaptive Volume-of-Fluid method based on octree meshes. The use of accurate numerical schemes for mesh adaptation, Volume-of-Fluid advection and balanced force surface tension calculation implemented in Gerris, the code used to perform the simulations included in this work, has made possible to carry out accurate simulations with characteristic scales spreading over several orders of magnitude. The code is validated by comparisons with the temporal linear theory for moderate density and viscosity ratios, which basically corresponds to atomization processes in high pressure chambers. In order to show the potential of the code in different scenarios related to atomization, preliminary results are shown in relation with the study of the two-dimensional and 3D temporal and spatial problem, the influence of the injector and the vortex generated inside the chamber, and the effect of swirling at high Reynolds numbers.     

Microstructural characterisation and behaviour in different salt solutions of sodium polymethacrylate-g-PEO comb copolymers

Different polycarboxylate polymers (PCPs) have been characterised and their microstructure investigated by size exclusion chromatography, ¹H and ¹³C nuclear magnetic resonance spectroscopy. These polymers are comb-like with a sodium polymethacrylate backbone (PMAANa) on which poly(ethylene oxide) (PEO) chains are randomly grafted as shown by ¹³C NMR measurements. Since they are mostly used as superplasticisers in cementeous applications, their behaviour has been investigated at high pH in various salt solutions; average radii were determined at room temperature by static and dynamic light scattering and phase diagrams were determined as a function of temperature. We tried to evaluate the influence of different parameters (ion valence, cations, anions, PCP molecular weight, PEO length and grafting degree). A few experiments on homopolymers (PEO and PMAANa) have been equally performed in order to better understand the behaviour of PCPs in solution.