μSR measurement of the superconducting condensate reduction induced by Zn in underdoped, optimally doped and overdoped YBCO

We present an extensive study on the parallel reduction of T_c and the condensate density in ceramic YBCO samples, upon substitution of Cu by Zn. Strong evidence is collected in support of non magnetic pair breaking in a d‐wave pairing state. This revised version was published online in August 2006 with corrections to the Cover Date.     

BPSCCO-Ag powders obtained by a wet method and with a low carbon content for tape preparation

Il Nuovo Cimento D - High-T c superconductors with nominal composition Bi1.8Pb0.4Sr2Ca2.2Cu3O x and eventually admixed with metallic silver were prepared by an original version of the citrate route...     

CO abundances in the magellanic clouds

Summary We present here the first tentative of the chemistry of extragalactic molecular clouds. In particular, we study the mechanism and efficiency of the transformation of C into CO in order to explain the recent observations in the Small and the Large Magellanic Clouds. Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984.     

Measurements of the order parameter by proton N.M.R. on N-(4-alkoxybenzylidene)4'-toluidines

N-(4-alkoxybenzylidene)4'-toluidines are a family of organic compounds which present a nematic and (depending on the chain length) a smectic mesophase. We have performed proton spin echo measurements on some members of the family in these mesophases. N.M.R. spectra present well-defined structures that can be assigned to one of the two end methyl groups on the basis of phenomenological as well as analytical discussion, despite the large number of protons contributing to the total line shape. The order parameter derived from this analysis is compared with optical data on the same compounds.     

Muon localization and hyperfine fields in simple antiferromagnets MnF2 and CoF2

Muons implanted in MnF₂ and CoF₂ are localized at low temperatures in an interstitial site which exhibits octahedral symmetry. Measurements of the critical damping close toT _N and the hyperfine field in the AF phase are reported.This work was supported by the Italian Research Council and G.N.S.M. The wire-chamber spectrometer was constructed with the support of CERN-EP Division and INFN, Milano. We would like to thank Dr. T. Niinikoski and Mr. G. Coubra for assistence with the cryogenic facility and the personnel of the Crystallography Division of MASPEC Lab.-Parma for the X-ray analysis of the crystals. The collaboration of the MSC group at CERN during the experiments is gratefully acknowledged.     

A new HPLC method to determine glomerular filtration rate and effective renal plasma flow in conscious dogs by single intravenous administration of iohexol and p-aminohippuric acid

A high-performance liquid chromatography method to determine iohexol (IOX) and p-aminohippuric acid (PAH) in the plasma of dogs is evaluated according to recovery, reproducibility, and linearity utilizing a gradient pump. The mobile phase consists of 50mM sodium dihydrogen phosphate with 0.5mM tetrabutylammonium chloride, the pH is adjusted to 4.1, methanol is added to the final ratio of 90:10 (v/v), the flow rate is set at 1 mL/min, and separation is achieved with an ODS2 Luna column. The UV detector is set at 254 nm. IOX and PAH are used for evaluation of the effective renal plasma flow (ERPF) and glomerular filtration rate (GFR). The present method tested in three dogs demonstrates the accuracy in the evaluation of ERPF and GFR. Because of its precision and simplicity and low cost, it can be considered a good tool for ERPF and GFR in small animal practice.     

Regio- and stereoselective cycloadditions of cyclic nitrones to maleic diamide forced in a peptide: synthesis of potent ligands of human NK-2 receptor

The regioselectivity and the stereoselectivity induced by relatively small peptidomimetic maleic diamide 1 in cycloaddition reactions with cyclic nitrones 2-5 was studied. The high regio- and stereoselectivity observed, sensibly increased by nonpolar solvents, was the effect of a double-asymmetric induction produced by the nitrone substituent on the pseudopeptidic tether. A new class of potent human tachykinin NK-2 receptor ligands was synthesized.     

Highly ordered "defect-free" self-assembled hybrid films with a tetragonal mesostructure

One-pot self-assembled hybrid films were synthesized by the cohydrolysis of methyltriethoxysilane and tetraethoxysilane and deposited via dip-coating. The films show a high "defect-free" mesophase organization that extends throughout the film thickness and for domains of a micrometer scale, as shown by scanning transmission electron microscopy. We have defined these films defect-free to describe the high degree of order that is achieved without defects in the pore organization, such as dislocations of pores or stacking faults. A novel mesophase, which is tetragonal I4/mmm (space group), is observed in the films. This phase evolves but retains the same symmetry throughout a wide range of temperatures of calcination. The thermal stability and the structural changes as a function of the calcination temperature have been studied by small-angle X-ray scattering, scanning transmission electron microscopy, and Fourier transform infrared spectroscopy. In situ Fourier transform infrared spectroscopy employing synchrotron radiation has been used to study the kinetics of film formation during the deposition. The experiments have shown that the slower kinetics of silica species can explain the high degree of organization of the mesostructure.     

Molecular Mechanism of Photosensitization XI. Membrane Damage and DNA Cleavage Photoinduced by Enoxacin

The photosensitizing activity of enoxacin, 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carboxilic acid (ENX), toward membranes and DNA has been studied, taking into account human erythrocyte photohemolysis, unilamellar liposome alterations and plasmid pBR322 DNA photocleavage. Hydroxyl radicals and an aromatic carbene generated from ENX photode-fluorination seem to be the active intermediates involved in the photosensitization process. The steady-state photolysis products do not participate in the process. The mechanism of photosensitization responsible for the membrane damage depends on the oxygen concentration and follows a different path with respect to that operative for DNA cleavage. Between oxygenated radicals, the hydroxyl seems the species mainly responsible for membrane damage, whereas DNA cleavage is mainly produced by the carbene intermediate. A molecular mechanism of the photosensitization induced by ENX is proposed.     

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.