Are attitudes toward immigration changing in Europe? An analysis based on latent class IRT models

Advances in Data Analysis and Classification - We analyze the changing attitudes toward immigration in EU host countries in the last few years (2010–2018) on the basis of the European Social...     

Special values of symmetric hypergeometric functions

We discuss the -adic formula (0.3) of P. Th. Young, in the framework of Dwork's theory of the hypergeometric equation. We show that it gives the value at 0 of the Frobenius automorphism of the unit root subcrystal of the hypergeometric crystal. The unit disk at 0 is in fact singular for the differential equation under consideration, so that it's not a priori clear that the Frobenius structure should extend to that disk. But the singularity is logarithmic, and it extends to a divisor with normal crossings relative to in . We show that whenever the unit root subcrystal of the hypergeometric system has generically rank 1, it actually extends as a logarithmic -subcrystal to the unit disk at 0. So, in these optics, ``singular classes are not supersingular'. If, in particular, the holomorphic solution at 0 is bounded, the extended logarithmic -crystal has no singularity in the residue class of 0, so that it is an -crystal in the usual sense and the Frobenius operation is holomorphic. We examine in detail its analytic form.

     

On automorphisms fixing non-normal subgroups of groups

This work was carried out when the last named author visited the Department of Mathematics of the University of Napoli Federico II in March 1994. He is very grateful for the hospitality he enjoyed and for the support by the C.N.R.     

Groups with many normal-by-finite subgroups

A subgroup of a group is said to be normal-by-finite if the core of in has finite index in . In this article groups satisfying the minimal condition on subgroups which are not normal-by-finite and groups with finitely many conjugacy classes of subgroups which are not normal-by-finite are characterized.

     

On the -rank Artin Conjecture

We assume the generalized Riemann hypothesis and prove an asymptotic formula for the number of primes for which can be generated by given multiplicatively independent numbers. In the case when the given numbers are primes, we express the density as an Euler product and apply this to a conjecture of Brown-Zassenhaus (J. Number Theory 3 (1971), 306-309). Finally, in some examples, we compare the densities approximated with the natural densities calculated with primes up to .

     

Steric Crowding and Redox Reactivity in Platinum(II) and Platinum(IV) Complexes Containing Substituted 1,10-Phenanthrolines

The effect of the phenanthroline substituents on the structure and reactivity of platinum(II) and platinum(IV) complexes has been investigated. The X-ray crystal structures of the compounds [PtI(2)(4,7-Ph(2)phen)].CHCl(3) (1dz.CHCl(3)), [PtI(4)(4,7-Ph(2)phen)].CHCl(3) (2dz.CHCl(3)), [PtI(2)(2,9-Me(2)-4,7-Ph(2)phen)] (1fz), and [PtI(4)(2,9-Me(2)-4,7-Ph(2)phen)].I(2) (2fz.I(2)) have shown that complexes 1fz and 2fz, containing ortho-substituted phenanthrolines, exhibit a remarkable displacement of the equatorial iodine atoms from the N-Pt-N' plane (average 0.477(2) and 0.199(2) ?, respectively), a bending of the phenanthroline [angle between outer rings of 19.9(7) and 14.2(7) degrees, respectively] and a rotation of the N-C-C'-N' plane with respect to the N-Pt-N' plane [32.3(10) and 26.5(9) degrees, respectively]. Comparison between the structures of 1fz and 2fz, both having the phenanthroline with methyl substituents in the ortho position, indicates that, in the latter case, because of the presence of the two axial iodine ligands, the displacements of the ligands from the equatorial plane are smaller and find a compensation in a narrowing of the I(1)-Pt-I(1') angle (5 degrees ) and a lengthening of the Pt-N bonds (0.07 ?). The electrochemical behavior of the four-coordinate platinum(II) complexes shows that compounds possessing regular planar geometry have access to the one-electron reduced species, whereas those with distorted coordination geometry are irreversibly reduced by collapsing of the complex geometry. This is in sharp contrast with the behavior of related nickel complexes for which the pseudo-tetrahedral coordination imposed by bulky 2,9-substituents of phenanthroline stabilizes the nickel(I) species. Spectroscopic results allow us to assign a significant Pt(I) character to [1d](-) monoanions. The electrogenerated, plus one electron, complexes are not indefinitely stable and, because of conjugation with the phen ligand, progressively restore the Pt(II) oxidation state by transferring the electron to the peripheral organic ligand. The latter process can involve multiple electron additions in the macroelectrolysis time scale. The related platinum(IV) complexes [PtX(4)(L)] undergo irreversible two-electron reduction accompanied by fast release of the axial ligands and formation of the corresponding platinum(II) species.     

Nanoparticles derived from amphiphilic γ-cyclodextrins

Three alkylcarbonates of γ-cyclodextrin, i.e. hexyl, octyl and dodecylcarbonate, were synthesized and characterized, with the goal of formulating solid nanoparticles. The series of alkylcarbonates showed amphiphilic properties and were capable of forming micelles and nanoparticles. Blank and drug-loaded alkylcarbonate nanoparticles were prepared with each alkylcarbonate, using the solvent injection technique. Progesterone was chosen as model drug. The sizes of both unloaded and loaded nanoparticles were in the 80–200 nm range, with narrow size distribution and spherical shape, as shown by TEM analysis. The zeta potentials of unloaded nanoparticles were in the −20 to −24.0 mV range, and were slightly decreased in loaded nanoparticles. Drug-loading capacity was good; DSC analysis did not detect the progesterone melting peak, indicating the drug had interacted with the cyclodextrin alkylcarbonates. In vitro release kinetics of progesterone from the three types of nanoparticles were slow. These results indicate that γ-CD alkylcarbonate nanoparticles might be used as prolonged drug delivery system.     

New Bimetallic Ni–Rh Carbonyl Clusters: Synthesis and X-ray Structure of the [Ni7Rh3(CO)18]3?, [Ni3Rh3(CO)13]3? and [NiRh8(CO)19]2? Cluster Anions

The reaction of the [Ni₆(CO)₁₂]²⁻ dianion with [Rh(COD)Cl]₂ (COD = cyclooctadiene) in acetone affords a mixture of bimetallic Ni–Rh clusters, mainly consisting of the new [Ni₇Rh₃(CO)₁₈]³⁻ and [Ni₈Rh(CO)₁₈]³⁻ trianions. A study of the reactivity of [Ni₇Rh₃(CO)₁₈]³⁻ led to isolation of the new [Ni₃Rh₃(CO)₁₃]³⁻ and [NiRh₈(CO)₁₉]²⁻ anions. All these new bimetallic Ni–Rh carbonyl clusters have been isolated in the solid state as tetrasubstituted ammonium salts and have been characterised by elemental analysis, X-ray diffraction studies, ESI-MS and electrochemistry. The unit cell of the [NEt₄]₃[Ni₇Rh₃(CO)₁₈] salt contains two orientationally-disordered ν₂-tetrahedral [Ni₇Rh₃(CO)₁₈]³⁻ trianions with occupancy factors of 0.75 and 0.25. Besides, their inner Ni₃Rh₃ octahedral moieties show two cis sites purely occupied by Rh atoms, two trans sites purely occupied by Ni atoms and the remaining two cis sites are disordered Ni and Rh sites with respective occupancy fraction of 0.5. At difference from the parent [Ni₇Rh₃(CO)₁₈]³⁻, the octahedral [Ni₃Rh₃(CO)₁₃]³⁻ displays an ordered distribution of Ni and Rh atoms in two staggered triangles. The [NiRh₈(CO)₁₉]²⁻ dianion adopts an isomeric metal frame with respect to that of the [PtRh₈(CO)₁₉]²⁻ congener. As a fallout of this work, new high-yield synthesis of the known [Ni₆Rh₃(CO)₁₇]³⁻ and [Ni₆Rh₅(CO)₂₁]³⁻, as well as other currently-investigated bimetallic Ni–Rh clusters have been obtained.     

Novel Hydroxyicosatetraenoic and Hydroxyicosapentaenoic Acids and a 13-Oxo Analog. Isolation from a Mixture of the Calcareous Red Algae Lithothamnion corallioides and Lithothamnion calcareum of Brittany Waters

A mixture of the red calcareous algae Lithothamnion corallioides CROUAN and Lithothamnion calcareum (PALLAS ) ARESCHOUGH , from Brittany waters, gives, on ethanolic extraction, the novel icosanoids ethyl 13-hydroxy-arachidonate (=(+)-all-Z-ethyl 13-hydroxyicosa-5,8, 11,14,-tetraenoate; (+)- 1 )), ethyl 13-hydroxytimnodonate (=(+)-(all-Z)-ethyl 13-hydroxyicosa-5,8,11,14,17-pentaenoate ((+)- 2 ), and (5Z,9E,11E,14E)-ethyl 8-hydroxy-13-oxoicosa-5,9,11,14-tetraenoate ( 3 ). Moreover, the ethyl esters of four known icosatetraenoic acids are contained in the above algae. Structural elucidations of these metabolites are based mainly on NMR data.