On the trees associated to plane curve singularities and ideals

Si comparano diverse nozioni d’equisingolarità per le curve tracciate sopra una superficie complessa liscia, e per gli ideali di dimensione finita dell’anello locale d’uno dei suoi punti. Si vede che, in generale, questi nozioni sono diverse, ma (per le curve) queste coincidono se esse fossero membri della stessa famiglia continua.     

Continued fraction calculation of the eigenvalues of tridiagonal matrices arising from the Schroedinger equation

The usual Sturmanian sequence for finding the eigenvalues of a tridiagonal matrix arising from the radial Schroedinger equation is found to be unstable. A self-stabilising continued fraction approach is suggested.     

Spatio-temporal anomalous diffusion imaging: results in controlled phantoms and in excised human meningiomas

Recently, we measured two anomalous diffusion (AD) parameters: the spatial and the temporal AD indices, called γ and α, respectively, by using spectroscopic pulse gradient field methods. We showed that γ quantifies pseudo-superdiffusion processes, while α quantifies subdiffusion processes. Here, we propose γ and α maps obtained in a controlled heterogeneous phantom, comprised of packed micro-beads in water and in excised human meningiomas. In few words, α maps represent the multi-scale spatial distribution of the disorder degree in the system, while γ maps are influenced by local internal gradients, thus highlighting the interface between compartments characterized by different magnetic susceptibility. γ maps were already obtained by means of AD stretched exponential imaging and α-type maps have been recently achieved for fixed rat brain with the aim of highlighting the fractal dimension of specific brain regions. However, to our knowledge, the maps representative of the spatial distribution of α and γ obtained on the same controlled sample and in the same excised tissue have never been compared. Moreover, we show here, for the first time, that α maps are representative of the spatial distribution of the disorder degree of the system.     

Future contributions to Journal of Chemical Crystallography

Future contributions to Journal of Chemical Crystallography     

Synthesis of 4-(pyrazol-5-yl)-1,2,4-triazole-3-thiones

Condensation of pyrazolyl isothiocyanates 2 with N-substituted hydrazines provided the 2-methyl/phenyl-4-(pyrazol-5-yl)thiosemicarbazides 3 . Cyclization of 3 with formic acid-acetic anhydride or with triethyl orthoacetate-acetic anhydride provided 4-(pyrazol-5-yl)-l,2,4-triazole-3-thiones 4a-f and 5-methyl-4-(pyrazol-5-yl)-1,2,4-triazole-3-thiones 4g-I respectively.     

[1,2,3,4-Tetrakis(α/β-d-galactopyranos-6-yl)phthalocyaninato]zinc(II): a water-soluble phthalocyanine

A novel water-soluble asymmetrical sugar-phthalocyanine was prepared via a statistical cross-condensation of tetrakis(1,2:3,4-di-O-isopropylidene-α-d-galactopyranos-6-yl)phthalonitrile with phthalonitrile. The new compound, with amphiphilic character, can be useful as a selective photosensitizer in photodynamic therapy, as well as for constructing phthalocyanine-based supramolecular systems.     

Lack of delocalized Cup states at the fermi level in the high-T c superconductor YBa2Cu3O∼7 by XANES spectroscopy

The x-ray absorption spectra of the single phase high temperature superconducting YBa₂Cu₃O₇ withT _{c, onset}=97 K have been measured between 30 K and 300 K by using synchrotron radiation.The copperK-edge x-ray absorption near edge structure (XANES) spectrum gives experimental evidence of the lack of delocalized Cup states close to the Fermi level, in fact a spectral distribution of local (at the Cu site) partial (l=1) density of states as in the insulating CuO has been found.The EXAFS (extended x-ray absorption fine structure) spectrum shows evidence of the formation of layers formed by Cu ions coordinated by oxygen square planes sharing corners. The average Cu–O distance at 30 K in the layers has been found to be 1.93 i.e. 0.02 shorter than in CuO and the average distance between Cu ions at the centers of the square planes is 3.85.The present local structure suggests that superconductivity should occur in the crystalline planes formed by CuO₄ square plane units. The lack of delocalized Cu states is in agreement with the hypothesis that conductivity is due to itinerant holesL in the oxygen derived valence band.The results of this experiment have been presented at the Symposium on the Latest Developments in Superconductivity at High Temperatures of the European Physical Society Meeting held in Pisa april 8, 1987     

A versatile route to potential dihydrofolate reductase inhibitors via the hitherto unknown 6-benzyl-2-(O-methyl)uracils: Synthesis of isotrimethoprim

The synthesis of 2, 4-diamino-6-(3, 4, 5-trimethoxybenzyl)pyrimidine (isotrimethoprim) has been accomplished starting from 2-(O-methyl)-6-(3, 4, 5-trimethoxybenzyl)uracil by standard procedures. The benzyluracil derivative has been obtained by reacting O-methylisourea sulphate and ethyl 3, 4, 5-trimethoxyphenacetylace-tate.     

Kinetics of polycondensation reactions during self-assembly of mesostructured films studied by in situ infrared spectroscopy

In situ synchrotron FTIR experiments have been performed during evaporation-induced self-assembly (EISA) of mesoporous films and the role of silica polycondensation in obtaining highly organized mesostructures has been illuminated.     

Molar melting enthalpy in an homologous series of mesophasic polymers

The melting point depression of polymer-solvent mixtures as a function of the concentration has been measured by DSC methods for a group of semiflexible linear mesophasic polymers of formula

$\text{[OOC(CH}{}_2\text{)}{}_{\mathrm{n-2}}\text{COOøC(CH}{}_3\text{)CHø]}{}_{\mathrm{\chi }}$

The molar enthalpic changes associated with the phase transitions have been determined. The values of the ratio between the molar isotropization entropy and the total molar entropic change relative to the sequence of phase transitions leading from the crystal phase to the isotropic liquid have been taken into account as an indication of the order of the mesophase. A particularly high value of this ratio has been found for the even members of the homologous series of polymers.