[en] A photopyroelectric technique has been applied to the study of specific heat and thermal conductivity of homeotropically aligned mixtures of small quartz spheres (aerosil) and octylcyanobiphenyl (8CB) with concentration 0≤ρ_s≤0.04g/cm³. Thermal conductivity data show that, even at these very low concentrations, an annealing of the disorder introduced by the aerosil takes place on cooling at the smectic-A - nematic (Sm-A - N) phase transition and not only at the nematic-isotropic (N-I) one. This means that there is some elastic strain in the nematic phase of the sample which is not quenched. Accordingly the suppression of the N-I transition temperature as a function of ρ_s does not fit a random field with a random dilution model that accounts for random quenched disorder only. High resolution specific heat measurements at the A-N and N-I transition show the effect of the aerosil is not the same. While in the first case its peak is suppressed with increasing concentration, in the second case there are some indications that outside the two-phase coexistence region it is enhanced. The effect of surface-induced alignment is also discussed to explain some discrepancies between our data and the ones reported in literature. It is concluded that the amount of disorder in the sample does not depend on ρ_s only, but also on other variables such as external fields. Finally, a relaxation phenomenon in the aerosil network that partially compensate the disordering effect of the particles is suggested to explain the concentration dependence of the transition temperatures

[en] This article outlines a research program on the behaviour of the pressure suppression containment system used in BWR plants during a loss- of-coolant accident. The experimental facility set-up at the Nuclear Engineering Institute of the University of Pisa is briefly described and the results obtained during the first tests carried out by this facility are reported. The analysis of these results allows some interesting conclusions to be drawn, which not only confirm the validity of the research program, but suggest an extension of it

[en] The photoacoustic technique in the gas-cell/microphone configuration has been applied to determine optical and thermal parameters in ion-implanted silicon and gallium arsenide layers, as a function of the ion implantation dose. The results are in good agreement with those reported in the literature, thus demonstrating that the technique is suitable for determining, in a nondestructive way, thermal and optical parameters in thin layers as well as in bulk material, even at wavelengths for which the material is optically opaque. (author)

[en] A magneto electric force acting on the levitating spheres in the experiment of search for quarks by the magnetic levitation electrometer is identified. All the 47 steel spheres (23 with diameter 0.2 mm. and 24 with diameter 0.3 mm. totalling a mass of 3.4 mg.) examined after the elimination of the effects of such force produce the result: N/sub quarks//N/sub nucleons/ < or =5.10^-22

[en] With the use of a new feedback levitation electrometer (with an increase in sensitivity by 10³ in comparison to our previous graphite experiments) iron objects of mass approx. 2 x 10^-4 g have been explored for fractionally charged quarks and/or a possible electron-proton charge difference. Upper limits found were N (quarks)/N (nucleons) < 3 x 10^-21 and (Q/sub p/ - vertical-bar Q/sub e/ vertical-bar)/Q/sub p/ < 10^-21. The present ''sensitivity'' is approx. 10⁷ times that of the original Millikan experiment

[en] Critical currents carried by Bi-Sr-Ca-Cu-O superconducting samples have been measured as a function of temperature and of a weak applied magnetic field. Both polycrystalline samples, of the 2212 (T _c = 85K) and 2223 (T _c = 110K phases, and single crystals of the 85K phase have been investigated. For sintered samples the critical current density, at a temperature of 0.65T _c , is lower than 50 A/cm ² and is strongly reduced in a field of few tens of Gauss. In the single crystals investigated the critical current density are of the same order of magnitude. However in these samples the temperature dependence is markedly different from the one observed in sintered specimens, and is not affected by the presence of weak applied field

[en] Tapping mode atomic force microscopy (AFM) was employed to study the surface structure of spin-coated and solvent-cast films of the newly synthesized electroluminescent copolymer TT9 and its fractions A and B. Fraction A is well soluble in chloroform while fraction B forms aggregates of high molecular weight in the same solvent. TT9 and fraction A are photoluminescent; fraction B is not. TT9 spin-coated and solvent-cast films show similar morphologies characterized by wormlike structures. Solvent-cast films formed by fraction A have a large density of defects. Fraction B forms larger structures, giving rise to more corrugated surfaces. These structures are formed by grains of rather uniform size, likely to be related to the aggregates already present in solution. For all the examined films, the surface roughness scales in the same way with the linear dimension of the surface, suggesting similar growth mechanisms

[en] The results of many runs performed levitating in succession several spheres without opening the levitation chamber show the existence of an additional (magneto-electric) force acting on the sphere. Ignoring this force in the analysis of the data produces 'spurious' fractional charges. (orig.)

[en] The procedure to identify, measure and subtract the magneto-electric force acting on levitating spheres is described. All the 25 steel spheres (with a total mass of 1.75 mg) examined after the elimination of the effects of such a force produce the result: Nsub(quarks)N sub(nucleons) <= 10^-21. (orig.)

[en] Simple and rapid chromatographic systems were used to test the radiochemical purity of eleven sup(99m)Tc-diagnostic agents. Those systems were selected which gave no oxidation or other by-products. The tests were done with equipment normally available in Nuclear Medical Departments. (author)