Solvent effects in the polymerization of propylene catalyzed by octahedral complexes

The effect of solvents (toluene, dichloromethane, and hexane) was studied on the polymerization of propylene with the octahedral complexes bis(trimethylsilyl)benzamidinate titanium dichloride(a), bis(acetylacetonate) titanium dichloride(b), and bis(diethylamino) titanium di‐2‐(diphenylphosphanylamino)pyridine as catalytic precursors and methylalumoxane as the cocatalyst. For comparison, the polymerization was also performed in plain liquid propylene without the addition of any solvent. The obtained polymers were fractionated by refluxing hexane. The activity of the complexes and the molecular weights and tacticities of the whole polymers and their different fractions were the studied parameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4505–4516, 2005     

Borel-Weil-Bott theory on the moduli stack of G-bundles over a curve

Let G be a semi-simple group and M the moduli stack of G-bundles over a smooth, complex, projective curve. Using representation-theoretic methods, I prove the pure-dimensionality of sheaf cohomology for certain “evaluation vector bundles” over M, twisted by powers of the fundamental line bundle. This result is used to prove a Borel-Weil-Bott theorem, conjectured by G. Segal, for certain generalized flag varieties of loop groups. Along the way, the homotopy type of the group of algebraic maps from an affine curve to G, and the homotopy type, the Hodge theory and the Picard group of M are described. One auxiliary result, in Appendix A, is the Alexander cohomology theorem conjectured in [Gro2]. A self-contained account of the “uniformization theorem” of [LS] for the stack M is given, including a proof of a key result of Drinfeld and Simpson (in characteristic 0). A basic survey of the simplicial theory of stacks is outlined in Appendix B. Oblatum 17-XII-1996 & 26 VI-1997     

Regularity and convergence of stochastic convolutions in duals of nuclear Fréchet spaces

Let Φ′ be the strong dual of a nuclear Fréchet space Φ. In this paper we present regularity properties, weak convergence, and convergence in probability and in mean square of Φ′-valued stochastic evolution equations and convolutions with respect to Φ′-valued cadlag martingales.     

Study of collision-induced decomposition of phenothiazine by ion trap mass spectrometry

The collision-induced decomposition pathways of phenothiazine were studied in detail by ion trap mass spectrometry. With this approach, different amounts of energy can be deposited into the fragment ions, thus favouring particular structures. Different relative abundances in the fragmentation patterns of selected ions are observed, depending on whether they are produced by electron impact or multiple mass spectrometry [(MS)ⁿ] methods.     

Onsager's conjecture on the energy conservation for solutions of Euler's equation

We give a simple proof of a result conjectured by Onsager [1] on energy conservation for weak solutions of Euler's equation.     

Graphes et ordonnés démontables, propriété de la clique fixe

This work extends to dismantable graphs many properties of dismantable posets dealing with products, exponentiation, existence of paths in a graph of all homomorphisms, fixed clique property, etc. We show that a poset is dismantlable in the sense of Rival if and only if its comparability graph is dismantlable, thus proving that, for posets, dismantlability is a comparability invariant. We establish the analogues for graphs of results of Duffus, Poguntke and Rival about fixed point sets and cores in posets.     

High-resolution infrared and subterahertz spectroscopy of the v2 = 1, v5 = 1, and v3 = 2 levels of CH3Cl

High-resolution Fourier-transform infrared spectra between 1235 and 1680 cm⁻¹ and subterahertz spectra between 250 and 630 GHz of monoisotopic ¹³CH₃³⁵Cl have been recorded and analyzed simultaneously, with all Coriolis, α-resonance, and l-type interactions in the polyad of the v₂ = 1, v₅ = 1, and v₃ = 2 levels taken into account. Several α-resonances (Δk = ±2, Δl = ?1) generating perturbation-allowed transitions have been assigned in the rovibrational spectra. These resonances enabled us to determine accurately and independently the ground state rotational and centrifugal distortion parameters A₀ = 5.205 746 9 (55) cm⁻¹ and . Even , which is, however, correlated to higher-order α-resonance terms, was determined. With 51 upper state parameters varied, about 5800 rovibrational wavenumbers and more than 550 rotational frequencies pertaining to the excited vibrational states were fitted within their experimental accuracy.     

Microscopic model of critical current noise in Josephson junctions

We present a simple microscopic model to show how fluctuating two-level systems in a Josephson junction tunnel barrier of thickness L can modify the potential energy of the barrier and produce critical current noise spectra. We find low frequency 1/f noise that goes as L5. Our values are in good agreement with recent experimental measurements of critical current noise in Al/AlOx/Al Josephson junctions. We also investigate the sensitivity of the noise on the nonuniformity of the tunnel barrier.