Sul metodo delle minime potenze ponderate e sul metodo di Ritz per il calcolo approssimato nei problemi della Fisica-Matematica

Rendiconti del Circolo Matematico di Palermo Series 1 -     

Rearrangement of 3,5-dicyano-1,4-dihydropyridines to densely functionalized cyclopentadienes

3,5-Dicyano-1,4-dihydropyridines underwent ring contraction to give functionalized cyclopentadienes upon treatment with trifluoroacetic anhydride.     

Maggiorazione degli integrali delle equazioni totalmente paraboliche alle derivate parziali del secondo ordine

Sunto. Si conseguono semplici formole generali maggioranti gli integrali, soggetti ad assegnate condizioni al contorno atte a determinarli, delle equazioni totalmente paraboliche alle derivate parziali del second'ordine in due o più variabili indipendenti. La ricerca offre numerosi nuovi risultati, fra i quali, per esempio, quelli concernenti il comportamento all'infinito degli integrali; il teorema d'unicità per l'annoso problema della propagazione del calore in un mezzo conduttore illimitato, senza l'aggiunta di ulteriori ipotesi — affatto estranee al punto di vista fisico — sul comportamento all'infinito delle derivate della soluzione; le condizioni atte a determinare ? in grande ? gli integrali delle equazioni lineari alle derivate parziali del primo ordine, ecc. Insignita del premio Tenore dall'Accademia Pontaniana di Napoli, nella seduta del 10 giugno 1928.     

Thermotropic mesomorphism in penta- and hepta-coordinated metal complexes

New Ni(II) and UO₂(II) metallomesogens obtained from mesomorphic N,N'-salicyliden(3,3'-diamine-N-methyldipropylamine) ligands containing a pentadentate N₃O₂ chelating cavity and bearing two or four lateral substituents, are isolated and fully characterized. Some of the synthesized nickel and dioxouranium complexes show a SmC mesophase. To the best of our knowledge, these species are the first pentacoordinated Ni(II) and heptacoordinated UO₂(II) metallomesogens to be reported.     

Synthesis,characterization and antitumor activity of palladium(II) complexes of imidazolidine-2-thione

Complexes of the type cis-[PdX₂(imzt)(PPh₃)] {imzt = imidazolidine-2-thione; PPh₃ = triphenylphosphine; X = Cl (1), Br (2), I (3), SCN (4)} have been synthesized and characterized by elemental analyses, molar conductance, IR and ¹H NMR spectroscopies. The complex 1·MeOH was obtained from the reaction of [PdCl₂(CH₃CN)₂], imidazolidine-2-thione and triphenylphosphine in CHCl₃/CH₃OH. Complexes 2·MeOH, 3 and 4 were prepared by metathesis of the chlorido ligands in 1 with bromide, iodide and thiocyanate, respectively. Elemental analyses showed good agreement with the expected mononuclear compositions, while the molar conductivities of the complexes in DMF were consistent with their nonelectrolytic nature. NMR spectra confirmed coordination of the imidazolidine-2-thione and triphenylphosphine ligands. Single-crystal X-ray diffraction determination of 1·CH₃OH showed that the coordination geometry around Pd^II is nearly square planar, with the chlorido ligands in a cis configuration. All four complexes have been tested in vitro by XTT assay for their cytotoxicity against human glioblastoma cell line (U87MG). The binding of 1 with guanosine was studied by ¹H NMR spectroscopy, revealing that the coordination takes place via N7.     

The use of a gold disc microelectrode for the determination of copper in human sweat

A novel approach of using a gold disc microelectrode to analyze sweat samples for copper ions by anodic square wave stripping voltammetry (SW stripping voltammetry) is described. Sweat was collected from the lower back of four subjects after physical exercise and the sample volume required for the determinations was 100 μL. Under the optimized conditions, the calibration plot was linear over the range 1-100 μmol L⁻¹ Cu(II) with a limit of detection of 0.25 μmol L⁻¹. The precision was evaluated by carrying out five replicate measurements in a 1 μmol L⁻¹ Cu(II) solution and the standard deviation was found to be 1.5%. Measurements were performed by inserting the microelectrode into sweat drops and Cu(II) concentrations in the analyzed samples ranged from 0.9 to 28 μmol L⁻¹. Values obtained by the proposed voltammetric method agreed well with those found using graphite furnace atomic absorption spectroscopy (GFAAS).     

Mobility of a single alkali metal atom on fullerene C60: first principles molecular dynamical study

The dynamical behavior of a single K or Na alkali metal atom on the surface of a C(60) molecule is investigated via Car-Parrinello molecular dynamics simulations in a temperature range up to 300 K. These provide direct evidence for the heteroatom motion, postulated earlier in pioneering experiments, and show that an alkali metal atom can move both on the surface and radially outward from the surface, resulting in a dynamics ranging from diffusive to free orbital motion, on time-scales of up to a few picoseconds.