Showing papers by "University of Palermo published in 1975"
TL;DR: An operationally meaningful symmetric function defined on pairs of states of an arbitrary physical system is constructed and is shown to coincide with the usual transition probability in the special case of systems admitting a quantum-mechanical description.
Abstract: An operationally meaningful symmetric function defined on pairs of states of an arbitrary physical system is constructed and is shown to coincide with the usual “transition probability” in the special case of systems admitting a quantum-mechanical description. It can be used to define a metric in the set of physical states. Conceivable applications to the analysis of certain aspects of Quantum Mechanics and to its possible modifications are mentioned.
71 citations
TL;DR: In this paper, the limiting conditions under which an oriented structure is actually possible in extensional flows are critically reviewed, and it is shown that orientation can be obtained either when entanglements are present, i.e., when the polymer molecules form some sort of network, or, if the molecules behave entirely individually, only under very special circumstances.
Abstract: A characteristic feature of extensional flows is their potential capability of determining a stable, oriented structure in liquid materials containing elongated particles. With reference to flexible linear macromolecules, either in solution or as polymer melts, the limiting conditions under which such an oriented structure is actually possible are critically reviewed. It is seen that orientation can be obtained either when entanglements are present, i.e. when the polymer molecules form some sort of network, or, if the molecules behave entirely individually, only under very special circumstances. Further, if the objective is the “freezing” of the oriented structure in a partly crystalline, high-strength material, the conditions become even more restrictive.
48 citations
TL;DR: In this article, the failure of the primitive model (rigid charged spheres in a continuum) is shown to be the consequence of short-range spatial and energetic interactions between ions and adjacent solvent molecules.
Abstract: The conductance of tetrabutylammonium tetraphenylboride, picrate, perchlorate, and nitrate has been measured at 25°C in mixtures ofi-butyronitrile with chlorobenzene,o-dichlorobenzene,p-dicholorobenzene, 1,2-dichloroethane, andn-pentanol covering the range of dielectric constants 10≤D≤20. In these mixtures of polar solvents, both association constants and ionic mobilities depend on ion-solvent interaction energies and on free volume in a manner that is specific for each system. This failure of the primitive model (rigid charged spheres in a continuum) is shown to be the consequence of short-range spatial and energetic interactions between ions and adjacent solvent molecules.
26 citations
TL;DR: In this article, the first example of mononuclear isoheterocyclic rearrangement is reported. But the results obtained are discussed only in terms of the 3-acethylamino-5-phenyl-1,2,4-oxadiazole (6).
25 citations
TL;DR: Results obtained by physical and chemical treatments suggest that hemagglutinin for Phallusia mamillata and Ascidia malaca may be a protein or a protein-like substance.
Abstract: Plasma fromCiona intestinalis, Phallusia mamillata andAscidia malaca possess hemagglutinin for a variety of erythrocytes. Results obtained by physical and chemical treatments suggest that hemagglutinin forPhallusia mamillata andAscidia malaca may be a protein or a protein-like substance.
21 citations
TL;DR: In this paper, tensiostatic anodization of tungsten has been studied in 1 N solutions of H 2 SO 4, HClO 42, HNH 2 SO 3 and HCl at 25 °C.
Abstract: Tensiostatic anodization of tungsten has been studied in 1 N solutions of H 2 SO 4 , HClO 42 , HNH 2 SO 3 and HCl at 25 °C. For several voltage values, the curves of current vs . time and open-circuit voltage vs . time have been obtained. All results indicate that the oxide films produced during the polarization are slowly dissolved in the acid solutions. The HCl, and to a lesser extent the HNH 2 SO 3 solutions, show a more aggressive behaviour. For values of the applied voltage above about 50 V, gas evolution begins. In the case of HCl solutions, the gas is Cl 2 and the electrode is rapidly corroded.
17 citations
TL;DR: A change in the molecular form of alkaline phosphatase in sea urchin embryos accompanies the marked increase in activity that occurs at gastrulation, and the early enzyme appears to have a slightly greater molecular volume, lower net negative charge, and more heterogeneous composition than the late enzyme.
14 citations
TL;DR: The reactivity of 2-nitrothiophene (1) and 3-nithium piperidine (II) with some nucleophiles has been studied in this article, according to calculated electronic densities I can receive nucleophilic attack at C3 and C5 depending on the nucleophile used, but II only at C2.
13 citations
TL;DR: The possible role of cell interactions during the development and differentiation of Paracentrotus lividus embryos is discussed.
13 citations
TL;DR: In this paper, the synthesis of halogenophenylantimonates (V) MIPhSbX5 (MI = Me4N, Ph4As; X = F, Cl, Br) is described, and their IR spectra (1100-100 cm−1) interpreted.
13 citations
TL;DR: In this paper, a growing process of the structure, governed by a set of relations similar to those governing the plastic flowing process, is described. But this model is restricted to finite element-linear programming.
TL;DR: In this article, the authors consider discrete rigid-plastic structures which are subjected to the action of loads varying quasi-statically within given limits, and study the conditions for workhoardening adaptation, that is, conditions to ensure that the structure, after an initial rigidplastic phase, shows a purely rigid behavior.
Abstract: The paper considers discrete rigid-plastic structures which are subjected to the action of loads varying quasi-statically within given limits. It studies the conditions for workhoardening adaptation, that is the conditions to ensure that the structure, after an initial rigid-plastic phase, shows a purely rigid behavior. The safety factor against the workhardening inadaptation is defined by two dual optimization problems. Some characteristic features of the yielding surface at failure are pointed out, using also a proper geometric description. Static and kinematic theorems, which are similar to those of shakedown theory, are given. A simple application concludes the paper.
TL;DR: In this article, the synthesis and reactivity of dimethylgold(III) complexes with multidentate ligands as TRIPHOS (i.e. 2,2′,2″-triaminotriethylamine) have been examined.
TL;DR: In this article, the condensation of anisidines with ethyl benzoylacetate in diphenyl ether and the transformations of some intermediates were studied, including 2-phenyl-4-o-anisidyl-1-8-methoxy-quinoline.
TL;DR: The isolated plasma membranes appear to be pure from contamination of other cell membranes, and they can therefore be used for analytical studies on the composition and structure of plasma membrane.
TL;DR: In this article, a method for the determination of the absolute retardation families in photoelasticity was proposed, which used real-time holographic interferometry, and required only one hologram for the observation of absolute retardations over the whole model.
Abstract: A method for the determination of the absolute retardations families in photoelasticity.The method, which use real-time holographic interferometry, requires only one hologram for the observation of the absolute retardations over the whole model.This is achieved by viewing in the reconstruction process the loaded model through a polarizer. Where the polarization direction is parallel to one of the principal stresses, only the corresponding family of absolute retardations is observed.As an example of application the absolute retardations and stresses in a deep beam centrally loaded are determined.
TL;DR: In this paper, a trigonal bipyramidal structure for the complex anions Ph 3 Sn(N 3 ) − 2, Ph 3 N 3 )(NCS) −, Me 2 Sn(n 3 ) 2− 4, R 2 Sn IV compounds are assumed to be trans-octahedral species.
TL;DR: In this paper, a novel complex hal2Sntrid, where hal Cl, Br, and trid2− are dianions of tridentate ligands with ONO and SNO donor basic atoms, were synthesized and structurally investigated in the solid state mainly by far infrared and MOSSBAUER spectroscopy.
Abstract: Novel complexes hal2Sntrid, where hal Cl, Br, and trid2− are dianions of „planar” tridentate ligands with ONO and SNO donor basic atoms, were synthesized and structurally investigated in the solid state mainly by far infrared and MOSSBAUER spectroscopy. Possible configurations were advanced and discussed, and it was concluded that the most probable is a monomeric trigonal bipyramidal structure for all compounds, although polymers, or dimers with O or Cl bridges, were not a priori excluded, in a special way for Br2Sntrid.
Infrarot- und MOSSBAUER-spektroskopische Untersuchungen an Komplexen von Hal2SnIV mit dreizahnigen Liganden
Neue Komplexverbindungen von Typ hal2Sntrid werden dargestellt (hal Cl, Br, und trid2− ebene, dreizahnige Liganden mit ONO- und SNO-Atomen, als zweiwertige Anionen). In festem Zustand wurden die Strukturen durch IR- und MOSSBAUER-Spektren untersucht. Mogliche Anordnungen der Liganden um das Zinn(IV)-Atom werden vorgeschlagen und diskutiert.
Wahrscheinlich sind alle diese Verbindungen monomer mit einer trigonal-bipyramidalen Struktur; aber es konnen polymere oder dimere Anordnungen mit O- oder Cl-Brucken, besonders bei Br2Sntrid, nicht vollig ausgeschlossen werden.
TL;DR: In this paper, the weakly absorbed 1.2-μ combination band of water was accurately studied as a function of temperature, in both its profile and first derivative, to obtain information on the bulk properties of liquid water.
Abstract: The weakly absorbed 1.2-μ combination band of water was accurately studied as a function of temperature, in both its profile and first derivative, to obtain information on the bulk properties of liquid water. Arrhenius plots of integrated component intensity ratios showed well aligned experimental points, except for a neatly defined break occurring in the 30 to 40°C temperature interval for pure water A similar break, shifted by some 18°C towards lower temperature, was found in the case of 1M NaClO4 aqueous solutions. The breaks are tentatively assumed to result from abrupt though subtle changes involving low-frequency modes. This tentative, assumption appears independent of specific models and assignments and, although in agreement with available neutron-scattering and NMR data, needs more direct verification.
TL;DR: In this article, the synthesis of the solid adducts Me3SnOH · Me3 SnNCO, Me3snOH · ME3SnNCS · Me 3PbN3 is reported.
TL;DR: Results of an experiment performed with (14)C-labeled urea demonstrate that the action of L-histidine is based on the retardation of the rise of pH, which prolongs the stationary phase and the survival of a T-strain of mycoplasma.
Abstract: The addition of L-histidine to the growth medium prolongs the stationary phase and the survival of a T-strain of mycoplasma. Results of an experiment performed with 14C-labeled urea demonstrate that the action of L-histidine is based on the retardation of the rise of pH.
TL;DR: The Mossbauer parameters of compounds Ph3Sn MCl · TMED (M = Cd, Zn; TMED = N,N,N′, N′-tetramethylethylenediamine), (Ph3Sn)2CdL2 (L2 = TMED, 2,2′-bipyridine and o-phenanthroline) and Ph3sn)2 Zn · TM ED have been determined and discussed in this paper.
TL;DR: In this article, the configurations of the complexes hal 2 Sn Salen (hal = Cl, Br) were investigated by infrared and Mossbauer spectroscopic studies, and single vibrational modes were observed to occur, which would suggest linear geometries of the Sn IV hal 2 moieties, although bent configurations were not excluded.
TL;DR: An investigation was made into the links between electric activity of antral and of duodeno-jejunal musculature in different functional conditions and the function of the gastroduodenal junction in this linking mechanism was analysed.
Abstract: An investigation was made into the links between electric activity of antral and of duodeno-jejunal musculature in different functional conditions. The function of the gastroduodenal junction in this linking mechanism was analysed. The following observations were made: (a) in the absence of gastric stimulation, the slow electric activities of stomach and duodenum appear to be completely independent; (b) the gastroduodenal junction evidences no electric activity of its own but is affected by that of the two adjacent structures; (c) chemical stimulation of the gastric mucosa causes activation of the electric and mechanical activity of the stomach and analogous activation of duodenal musculature; this effect is mediated by the gastroduodenal junction; (d) very probably, the transmission of gastric activation to the duodenum is myogenic for it ceases after surgical transection but not after cooling or after ligature. The possible functional role of the pyloric junction in the complex gastroduodenal mechanism is discussed.
TL;DR: In this paper, the finite element method is used to obtain formulations of analysis problems relative to elastic-plastic structures when subjected to prescribed programmes of loads, and under the restrictive hypotheses: the yielding surfaces are piecewise linearized, and the plastic flow-laws are supposed to be of holonomic type within a single “finite” time interval.
Abstract: The finite element method approach is used to obtain formulations of analysis problems relative to elastic-plastic structures when subjected to prescribed programmes of loads, and under the restrictive hypotheses:a) the yielding surfaces are piecewise linearized, andb) the plastic flow-laws are supposed to be of holonomic type within a single “finite” time interval. For mulations are given as linear complementarity problems and quadratic programming problems: one pair of formulations in terms of velocity and plastic multiplier rate histories, and another pair in terms of plastic multiplier rate histories only. The solutions are shown to be characterized by two minimum principles for displacement and plastic strain rate histories. After some general remarks about computational procedures, the paper is concluded with some suggestions for future developments.