Accurate experimental and theoretical enthalpies of association of TiCl with typical Lewis bases used in heterogeneous Ziegler-Natta catalysis.

Adducts of TiCl with Lewis bases used as internal or external donors in heterogeneous Ziegler-Natta (ZN) catalysis represent a fundamental interaction contributing to the final composition of MgCl supported ZN-catalysts. This study presents the accurate experimental evaluation, from titration calorimetry, of the formation enthalpy of TiCl adducts with 15 Lewis bases of industrial interest. In addition, we report the accurate energies of association of TiCl with the same Lewis bases from calculations at the DLPNO-CCSD(T) level of theory.

Influence of regio- and stereoregularity of propene insertion on crystallization behavior and elasticity of ethene-propene copolymers.

Melting enthalpies of several ethene-propene samples, obtained by different single-center catalytic systems and having widely different constitutions and compositions in the range of industrial interest, are compared. For the first time, a clear evidence of influence of the regio- and stereoregularity of propene insertion on crystallization behavior of ethene/propene copolymers is provided. This influence is in qualitative agreement with the results of simplified energy calculations relative to models of pseudo-hexagonal packing of ethene-propene copolymers.

[Peptidergic innervation of the human dental pulp: neuropeptide Y].

The localization and distribution of the Neuropeptide Y (NPY) has been studied with immunofluorescent methods in the human dental pulp. Immunofluorescence for the NPY has been observed in nervous fibers running in medium and big nerves associated in vascular structures, and in single fibers scattered in the pulpar connective or organized in the subdontoblastic plexus.