Intramolecular Hydroamination of Selenoalkynes to 2-Selenylindoles in the Absence of Catalyst

In this work, a series of 2-chalcogenylindoles was synthesized by an efficient methodology, starting from chalcogenoalkynes, including a previously unreported tellurium indole derivative. For the first time, these 2-substituted chalcogenylindoles were obtained in the absence of metal catalyst or base, under thermal conditions only. In addition, the results described herein represent a methodology with inverse regioselectivity for the chalcogen functionalization of indoles.     

Embedded eigenvalues of Sturm Liouville operators

In this work we study the behavior of embedded eigenvalues of Sturm-Liouville problems in the half axis under local perturbations. When the derivative of the spectral function is strictly positive, we prove that the embedded eigenvalues either disappear or remain fixed. In this case we show that local perturbations cannot add eigenvalues in the continuous spectrum. If the condition on the spectral function is removed then a local perturbation can add infinitely many eigenvalues.     

Finitely additive integration and local integration with respect to upper integrals

Summary We study the integration theory for general integral metrics when restricted to upper integrals q, finding improvements in the relation between the classes of the q-integrable and the q_l-integrable functions. We give new results and notions which lead to the desirable characterizations of q-integrable functions as q_l-integrable f with q(|f|) < ∞, and of q_l-integrable functions via the integrability of their upper truncations, under natural conditions which are fulfilled in most finitely additive integration theories.     

Static light scattering,ultraviolet–visible,and fluorescence spectroscopy from fluorescent methyl methacrylate/benzazole dye copolymers displaying an intramolecular proton‐transfer mechanism in the electronically excited state

The solution behavior of new copolymers of methyl methacrylate and benzazole dyes emitting fluorescence because of an intramolecular proton‐transfer mechanism in the electronically excited state has been investigated by static light scattering, fluorescence spectroscopy, ultraviolet–visible, and gel permeation chromatography. In the dilute regime, with tetrahydrofuran (THF) and chloroform as solvents, the copolymers behave as typical polydisperse linear chains in good solvents. The analysis of the osmotic modulus for concentrated solutions in THF (c ≥ 60 g L^?1) indicates the existence of an interchain association mechanism. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 341–350, 2003     

Preliminary study of the thermally stimulated blue luminescence of ulexite

In this paper, novel results on the blue thermally stimulated luminescence (TSL) emission of ulexite (NaCaB₅O₆(OH)₆·5H₂O) have been studied. The four maxima appearing at 60, 110, 200 and 240°C on the TSL glow curves of this borate could be respectively associated to: (i) the first dehydration (NaCaB₅O₆(OH)₆·5H₂O→NaCaB₅O₆(OH)₆·3H₂O), (ii) the creation-annihilation of the three-hydrated phase, (iii) the Na-coordinated chains dehydroxylation and the starting point of the alkali self-diffusion through the lattice and (iv) the amorphisation of the lattice. These results are fairly well correlated with the differential thermal analyses (DTA), in situ thermal observations under environmental scanning electron microscope (TESEM) and thermal X-ray diffraction (TXRD) techniques.     

Boundary conditions of Sturm-Liouville operators with mixed spectra

We study bounds on averages of spectral functions corresponding to Sturm-Liouville operators on the half line for different boundary conditions. As a consequence constraints are obtained which imply existence of singular spectrum embedded in a.c. spectrum for sets of boundary conditions with positive measure and potentials vanishing in an interval [0,N]. These constraints are related to estimates on the measure of sets where the spectral density is positive.