Stabilization of cell-centered compressible Lagrangian methods using subzonal entropy

This work deals with the stabilization of early stages of Lagrangian calculations of compressible gas dynamics in the context of cell-centered discretization. We describe a totally conservative algorithm based on an entropy analysis of the distortion of a Lagrangian mesh. It prevents the tangling of the mesh, while remaining consistent and conservative in mass, momentum, and total energy. The method described can be applied to any cell-centered Lagrangian scheme. In this article, we detail the extension to the cell-centered Glace scheme published in Carré et al. (2009) [G. Carré, S. Del Pino, B. Després, E. Labourasse, A cell-centered Lagrangian hydrodynamics scheme on general unstructured meshes in arbitrary dimension, J. Comput. Phys. 228 (2009) 5160–5183]. Numerical tests are proposed to assess the accuracy and robustness.     

Palladium complexes of 8-(di-tert-butylphosphinooxy) quinoline

The preparation of the new ligand 8-(di-tert-butylphosphinooxy)quinoline (1) and the palladium derivatives [PdCl₂(1)] (2), [Pd(η³-all)(1)]⁺ [all = C₃H₅ (3a), 1-PhC₃H₄ (3b) and 1,3-Ph₂C₃H₃ (3c)] and [Pd(η²-ol)(1)] [ol = dimethyl fumarate (4a) and fumaronitrile (4b)] is reported. The cationic species 3a-3c have been isolated as salts. The complex 3a(BF₄) is obtained either from the reaction of 1 with [Pd(μ-Cl)(η³-C₃H₅)]₂ or from the reaction of ClP(CMe₃)₂ with [Pd(η³-C₃H₅)(8-oxyquinoline)], followed in both cases by chloride abstraction with NaBF₄. In the complexes, the ligand 1 is P,N chelated to the central metal, as shown by the X-ray structural analysis of 3a(BF₄). At 25 °C in solution, 3a(BF₄) and 3b(BF₄) undergo a fast η³−η¹−η³ dynamic process which brings about a syn-anti exchange only for the allylic protons cis to phosphorus, while for 4a and 4b a slow rotation of the olefin around its bond axis to palladium takes place. The complexes 2 and 3a(BF₄) are efficient catalyst precursors in the coupling of the phenylboronic acid with aryl bromides and chlorides.     

Determination of thyreostats in urine and thyroid gland by ultra high performance liquid chromatography tandem mass spectrometry

Thyreostatic compounds could be illegally administered to animals in order to obtain a weight gain due to a higher retention of water in the edible tissue and the gastro-intestinal tract. In the European Union their use for animal production is banned since 1981. Recently a highly sensitive method exploiting the determination of thyreostats with 3-iodobenzylbromide prior to purification to determine thyreostats in urine and other matrices was reported. For the first time, the UPLC instrumentation was used to separate the 3-iodobenzyl derivatives of various thyreostats. The deuterated internal standards tapazole-d₃ and propylthiouracil-d₅ were for the first time used for the quantification of tapazole, thiouracil, methylthiouracil, propylthiouracil, phenylthiouracil and mercaptobenzimidazole. The confirmative quantitative liquid chromatographic tandem mass spectrometric (LC–MS/MS) method was validated according to Commission Decision 2002/657/EC. The decision limit (CCα) and the detection capability (CCβ) were found to be for all compounds below the recommended value of 10 μg kg⁻¹.     

Selective Synthesis of Novel In and In3Sn Nanowires by an Organometallic Route at Room Temperature

No Abstract     

Molecular assemblies from imidazolyl-containing haloalkenes and haloalkynes: competition between halogen and hydrogen bonding

The structural characterization of molecular assemblies constructed from imidazolyl-containing haloalkenes and haloalkynes is reported. 1-(3-Iodopropargyl)imidazole (2) and 1-(2,3,3-triiodoallyl)imidazole (5) were synthesized from 1-propargylimidazole (1). In the solid state, these wholly organic modules self-assemble through N...I halogen-bonding interactions, thus giving rise to polymeric chains. The N...I interaction observed in 2 (d(N...I)=2.717 A, angle-spherical C(sp)-I...N=175.8 degrees) is quite strong relative to previously reported data. The N...I interaction in 5 (d(N...I)=2.901 A, angle-spherical C(sp2)-I...N=173.6 degrees) is weaker, in accordance with the order C(sp)-X<--base>C(sp2)-X<--base. Compound 5 was found to give a 1:1 cocrystal 4 with morpholinium iodide (6). In the X-ray crystal studies of 4, N...I halogen-bonding interactions similar to those observed in 5 were shown not to be present, as the arrangement of the molecules is governed by two interwoven hydrogen-bonding networks. The first network involves N-H...O interactions between nearby morpholinium cations, and the second network is based on N-H...N hydrogen bonding between morpholinium cations and imidazolyl groups. Both hydrogen-bonding schemes are charge-assisted. Halogen bonding is not completely wiped out, however, as the triiodoalkene fragment forms a halogen bond with an iodide anion in its vicinity (d(I...I)=3.470 A, angle-spherical C(sp2)-I...I=170.7 degrees). X-ray crystal studies of 6 show a completely different arrangement from that observed in 4, namely, N-H...O interactions are not present. In crystalline 6, morpholinium cations are interconnected through C-H...O bridges (d(H...O)=2.521 and 2.676 A), and the NH2+ groups interact with nearby iodide anions (d(H...I)=2.633 and 2.698 A).     

Luminescent Di‐ and Trinuclear Boron Complexes Based on Aromatic Iminopyrrolyl Spacer Ligands: Synthesis,Characterization, and Application in OLEDs

New bis‐ and tris(iminopyrrole)‐functionalized linear (1,2‐(HNC₄H₃‐C(H)?N)₂‐C₆H₄ ( 2 ), 1,3‐(HNC₄H₃‐C(H)?N)₂‐C₆H₄ ( 3 ), 1,4‐(HNC₄H₃‐C(H)?N)₂‐C₆H₄ ( 4 ), 4,4′‐(HNC₄H₃‐C(H)?N)₂‐(C₆H₄‐C₆H₄) ( 5 ), 1,5‐(HNC₄H₃C‐(H)?N)₂‐C₁₀H₆ ( 6 ), 2,6‐(HNC₄H₃C‐(H)?N)₂‐C₁₀H₆ ( 7 ), 2,6‐(HNC₄H₃C‐(H)?N)₂‐C₁₄H₈ ( 8 )) and star‐shaped (1,3,5‐(HNC₄H₃‐C(H)?N‐1,4‐C₆H₄)₃‐C₆H₃ ( 9 )) π‐conjugated molecules were synthesized by the condensation reactions of 2‐formylpyrrole ( 1 ) with several aromatic di‐ and triamines. The corresponding linear diboron chelate complexes (Ph₂B[1,3‐bis(iminopyrrolyl)‐phenyl]BPh₂ ( 10 ), Ph₂B[1,4‐bis(iminopyrrolyl)‐phenyl]BPh₂ ( 11 ), Ph₂B[4,4′‐bis(iminopyrrolyl)‐biphenyl]BPh₂ ( 12 ), Ph₂B[1,5‐bis(iminopyrrolyl)‐naphthyl]BPh₂ ( 13 ), Ph₂B[2,6‐bis(iminopyrrolyl)‐naphthyl]BPh₂ ( 14 ), Ph₂B[2,6‐bis(iminopyrrolyl)‐anthracenyl]BPh₂ ( 15 )) and the star‐shaped triboron complex ([4′,4′′,4′′′‐tris(iminopyrrolyl)‐1,3,5‐triphenylbenzene](BPh₂)₃ ( 16 )) were obtained in moderate to good yields, by the treatment of 3 – 9 with B(C₆H₅)₃. The ligand precursors are non‐emissive, whereas most of their boron complexes are highly fluorescent; their emission color depends on the π‐conjugation length. The photophysical properties of the luminescent polyboron compounds were measured, showing good solution fluorescence quantum yields ranging from 0.15 to 0.69. DFT and time‐dependent DFT calculations confirmed that molecules 10 and 16 are blue emitters, because only one of the iminopyrrolyl groups becomes planar in the singlet excited state, whereas the second (and third) keeps the same geometry. Compound 13 , in which planarity is not achieved in any of the groups, is poorly emissive. In the other examples ( 11 , 12 , 14 , and 15 ), the LUMO is stabilized, narrowing the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO–LUMO), and the two iminopyrrolyl groups become planar, extending the size of the π‐system, to afford green to yellow emissions. Organic light‐emitting diodes (OLEDs) were fabricated by using the new polyboron complexes and their luminance was found to be in the order of 2400 cd m^?2, for single layer devices, increasing to 4400 cd m^?2 when a hole‐transporting layer is used.     

Development and validation of a sensitive and selective method using GC/MS-MS for quantification of 5-fluorouracil in hospital wastewater

Pollution of the environment by pharmaceuticals is a subject of growing scientific and societal concern. However, few quantitative data have been reported concerning hospital wastewater contamination. Among the different molecules used at hospital, antineoplastic drugs appear to be of special interest, and 5-fluorouracil (5-FU) can be considered as a key compound of this therapeutic class. To monitor this pharmaceutical in hospital wastewater, a highly specific and selective method was developed using gas chromatography tandem mass spectrometry after solid-phase extraction. This sensitive method (limit of quantification = 40 ng L⁻¹) was then applied to assess sewage contamination of a middle-size hospital with oncology service located in Paris, France. Native 5-FU was detectable in 12 of the 14 analysed samples. In positive samples, concentration range was measured from 0.09 to 4.0 μg L⁻¹. Finally, a predicting model for the hospital wastewater concentrations is presented, and results of this model are discussed.     

Air‐Stable {(C5H5)Co} Catalysts for [2+2+2] Cycloadditions

Cobalt cyclopentadienyl complexes incorporating a fumarate and a CO ligand (see picture) efficiently catalyze inter‐ and intramolecular [2+2+2] cycloadditions of alkynes, nitriles, and/or alkenes to give benzenes, pyridines, or 1,3‐cyclohexadienes. Unlike catalysts such as [CpCo(CO)₂] or [CpCo(C₂H₄)₂] (Cp=C₅H₅), they are air‐stable, easy to handle, compatible with microwave conditions, and do not necessarily require irradiation to be active.