Anionically Substituted 1,1′,1″‐Methylidynetris[1H‐pyrazole] Ligands for the Formation of Neutral Lanthanide Complexes in Water: Synthesis,Characterization, and Photophysical Properties

The six‐step synthesis of the new podand‐type ligand 6,6′,6″‐[methylidenetri(1H‐pyrazole‐1,3‐diyl)]tris[pyridine‐2‐carboxylic acid] (LH₃) is described. Reaction of LH₃ with LnCl₃ ?6 H₂O (Ln=Eu, Gd, Tb) in MeOH resulted in the isolation of [LnL]?HCl complexes characterized by elemental analysis, mass and IR spectroscopy. Photophysical studies of the Eu and Tb complexes in aqueous solutions revealed the characteristic luminescence features of the metal atoms, indicative of an efficient ligand‐to‐metal energy‐transfer process. Determination of the luminescence quantum yields in H₂O showed the Tb complex to be highly luminescent (?=15%), while, for the Eu complex, the quantum efficiency was only 2%. Excited‐state‐lifetime measurements in H₂O and D₂O evidenced the presence of ca. three H₂O molecules in the first coordination sphere of the complexes. Investigation of the Gd complex allowed the determination of the ligand‐centered triplet state and showed the ligand to be well suited for energy transfer to the metal. The luminescence properties of the complexes are described, and the properties of the ligand as a suitable complexation pocket is questioned.     

Impact of Partial Separability on Large-Scale Optimization

ELSO is an environment for the solution oflarge-scale optimization problems. With ELSO the user is required to provide only code for the evaluation of a partially separable function. ELSO exploits the partialseparability structure of the function to computethe gradient efficiently using automatic differentiation.We demonstrate ELSO's efficiency by comparing thevarious options available in ELSO.Our conclusion is that the hybrid option in ELSOprovides performance comparable to the hand-coded option, while having the significantadvantage of not requiring a hand-coded gradient orthe sparsity pattern of the partially separable function.In our test problems, which have carefully coded gradients,the computing time for the hybrid AD option is within a factor of two of thehand-coded option.     

Real Paley-Wiener theorems associated with the weinstein operator

In this paper we use real analysis techniques to establish a new real Paley-Wiener theorems for the Fourier-Bessel transform associated with the Weinstein operator. More precisely we characterize the C ^∞-functions whose image under the Fourier-Bessel transform are functions with compact support through an L ^p growth condition, p ∈ [1, +∞] and we give another version of the real Paley-Wiener theorem for L ²-functions.     

Directed and elliptic flow in 197Au+197Au at intermediate energies

Directed and elliptic flow for the ¹⁹⁷Au+¹⁹⁷Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4π multi-detector. For semi-central collisions, the excitation function of elliptic flow shows a transition from in-plane to out-of-plane emission at around 100 MeV per nucleon. The directed flow changes sign at a bombarding energy between 50 and 60 MeV per nucleon and remains negative at lower energies. Molecular dynamics calculations (CHIMERA) indicate sensitivity of the global squeeze-out transition on the σ _NN and demonstrate the importance of angular momentum conservation in transport codes at low energies.     

The LPCTrap experiment: measurement of the β–ν angular correlation in 6He using a transparent Paul trap

We report on the status of the LPCTrap experiment, devoted to measure the β–ν angular correlation in the pure Gamow–Teller decay of ⁶He. This measurement is motivated by the search for the presence of tensor type contributions to the weak interaction. The ⁶He ions are confined in a novel transparent Paul trap. The β particles and the recoil ions are detected in coincidence to deduce the angular correlation parameter. The commissioning run performed in 2005 has given the proof of principle of this experiment. Up to 10⁵ coincidences were recorded during a second run in 2006.     

Stable products of spheres in the non-linear coupling of oscillators or quasi-periodic motions

For generic families of vector fields or transformations, normally hyperbolic invariant products of spheres appear near partially elliptic rest points. To cite this article: M. Kammerer-Colin de Verdière, C. R. Acad. Sci. Paris, Ser. I 339 (2004).     

Cube factorizations of complete graphs

A cube factorization of the complete graph on n vertices, K_n, is a 3‐factorization of K_n in which the components of each factor are cubes. We show that there exists a cube factorization of K_n if and only if n ≡ 16 (mod 24), thus providing a new family of uniform 3‐factorizations as well as a partial solution to an open problem posed by Kotzig in 1979. © 2004 Wiley Periodicals, Inc.