Showing papers by "University of Palermo published in 1979"
TL;DR: In this article, an atmospheric model is proposed to calculate the diffuse radiation in clouds, and the monthly average values of the global radiation incident on a horizontal surface at Palermo are computed by this method.
87 citations
TL;DR: Stable isotope measurements have been carried out on a number of carbonate and sulfate samples from evaporites of Messinian age as mentioned in this paper, which indicate that the environmental conditions of deposition of Messianic sediments changed widely through time and space.
75 citations
TL;DR: In this paper, the authors measured the dielectric constants for solutions of water in methanol, ethanol, 1-heptanol, and 1-octanol at different temperatures.
Abstract: Dielectric constants (measured at 1 MHz) are reported for solutions of water (concentration range 0 to 0.2 mole fraction) in 1-propanol at 25°C, and in 1-butanol, 1-pentanol, and 1-hexanol at 15, 25, 35, and 45°C. These results, together with literature values for solutions of water in methanol, ethanol, 1-heptanol, and 1-octanol, show that water interacts with alcohols in at least two ways: (1) it can participate in the formation of dynamic hydrogen-bonded chains, thereby raising the polarizability; (2) it can form relatively stable structures such as H2O(ROH)4 which have zero net dipole moment and consequently diminish volume polarizability. For C
n
H
2n+1
OH alcohols,n≥4, most of the initially added water forms complexes: consequently, addition of water to these alcohols lowers the dielectric constant.
62 citations
01 Sep 1979
TL;DR: In this paper, the least squares fitting of measured noise figures and gains versus input termination admission is an established procedure to determine linear two-port noise and gain parameters, however, the method is liable to the serious inconvenience of yielding often erroneous results or even results without physical meaning.
Abstract: The least-squares fitting of measured noise figures and gains versus input termination admittance is an established procedure to determine linear two-port noise and gain parameters. Unfortunately, the method is liable to the serious inconvenience of yielding often erroneous results or even results without physical meaning. Some criteria are suggested which allow the carrying out of measurements in such a manner as to safely avoid the above drawbacks.
59 citations
57 citations
TL;DR: The hole-drilling method is a semidestructive technique which allows the measurement of residual stresses as discussed by the authors, but it is prone to misalignment between the hole and the hole.
Abstract: The hole-drilling method is a semidestructive technique which allows the measurement of residual stresses. In this method, a source of error is due to the misalignment between the hole and ...
56 citations
TL;DR: In this paper, a canonical transformation is presented in order to diagonalize the radiation hamiltonian in the rotating wave approximation, and Dressing of atomic operators in the single and multi-atom cases is obtained explicitly and qualitatively discussed in connection with the problem of resonance fluorescence.
54 citations
TL;DR: The coelomic fluid of Holothuria polii D.Ch contains hemolytic activity against erythrocytes of several vertebrate species, and its heat lability, water insolubility at low pH values, and sensitivity to proteolytic enzymes suggest that hemolysis resides in protein molecules.
Abstract: The coelomic fluid of Holothuria polii D.Ch contains hemolytic activity against erythrocytes of several vertebrate species. The hemolytic potency depends upon calcium ion concentration and varies according to erythrocyte source and cell number in the reaction mixture. Absorption experiments with formalinized rabbit erythrocytes suggest that hemolytic activity is not specific. Its heat lability, water insolubility at low pH values, and sensitivity to proteolytic enzymes suggest that hemolytic activity resides in protein molecules. The activity, maximal in alkaline media, appears to depend up time and temperature.
46 citations
TL;DR: In this paper, the authors rationalized two kinds of interaction between water molecules and alcohols: participation of water molecules in chain formation for the lower alcohols and formation of water-centered complexes for butanol and higher alcohols.
Abstract: Viscosity measurements have been made at 25°C on solutions of water inn-propanol, and at 15, 25, 35, and 45°C on solutions of water inn-butanol,n-pentanol, andn-hexanol over the respective solubility ranges. For most of the systems, water decreases the viscosity of the dry alcohols, while for the lower members of the series literature data report an increase in viscosity on addition of water. These results are rationalized in terms of two kinds of interaction between water molecules and alcohols: participation of water molecules in chain formation for the lower alcohols and formation of water-centered complexes for butanol and higher alcohols.
30 citations
TL;DR: Developing animal quartets removed surgically from 8-cell stage of Ascidia malaca and Phallusia mamillata have been treated for a short time with a low concentration of trypsin results in differentiation of some neural structures, of pigment spots and of a tissue-specific enzyme, brain pigment cell tyrosinase.
26 citations
TL;DR: In this article, the interaction energy of water with the tautomeric species 4-hydroxy-pyridine (4-h-p) and 4pyridone (4p) is analyzed in the SCF-LCAO-MO approximation.
TL;DR: In this paper, the pyrrolo [2,1-f]-1,2,4-triazine-2, 4(1H, 3H)dione derivatives were cycled under basic conditions.
TL;DR: In this article, it was suggested that light speed invariance would not seem to be fully consistent with ordinary space geometry unless proper time is allowed to undergo one independent dilatation for each degree of space freedom.
TL;DR: Four new diterpenoid species from some Marrubium species endemic in the Iberian Peninsula have been isolated, including 6-acetyl-marrubenol, 19- acetyl- marrubenols, premarrubenoli and 6- Acetyl-premarubenol.
TL;DR: In this paper, the authors considered shakedown analysis problems for elastic-perfectly plastic solids subjected to quasi-static loads which vary arbitrarily within a given domain, and gave a general inequality which is able to generate Melan's theorem for shakedown, as well as bounds on plastic strains at any point of the solid.
TL;DR: In this paper, a model of non-linear viscoelasticity with relaxation times dependent upon free volume is proposed, which is related to the isotropic part of the stress tensor by means of a simple differential equation.
Abstract: A model of non-linear viscoelasticity with relaxation times dependent upon free volume is here proposed. The free volume is related to the isotropic part of the stress tensor by means of a simple differential equation. The model predictions are compared with a large amount of experimental results taken on polymeric melts or concentrated solutions and reported in the literature. The single parameter of the model is determined, within each set of data, by fitting of the viscosity curve. A satisfactory agreement is obtained with data taken under both elongation and shear for which also the relaxation behavior after single and double strain steps is considered.
TL;DR: An electron microscopic analysis of non nucleated and parthenogenetically activated sea urchin eggs shows figures that can be interpreted as dividing mitochondria, in agreement with previous observations showing that the egg nucleus negatively controls mitochondrial DNA synthesis.
01 Jan 1979
TL;DR: The first example of a mononuclear heterocyclic rearrangement involving an XYZ = CCN side-chain sequence was reported in this paper, where the 3-(o-aminophenyl)-, and 3-(methylaminophenyl]-5-methyl-1,2,4-oxadiazoles (3a,b) gave a thermally induced rearrange into 3-acylaminoindazoles (4a, b).
TL;DR: In this paper, a series of 10 Schlumberger V.E.S. have been executed in a spot of the Palermo coastal plane upon a layered structure with unconfined aquifer in order to study the time variations of the shapes of the curves and their interpretations obtained by means of a computerized indirect method.
TL;DR: A purification procedure and some properties of a nonspecific nucleoside phosphotransferase of chick embryo, an activity which catalyzes the transfer of the phosphate ester from a deoxyribon nucleotide or a pyrimidine ribonucleotide to a dexyribonucleoside acceptor is described.
Abstract: This paper describes a purification procedure and some properties of a nonspecific nucleoside phosphotransferase of chick embryo, an activity which catalyzes the transfer of the phosphate ester from a deoxyribonucleotide or a pyrimidine ribonucleotide to a deoxyribonucleoside acceptor. The enzyme is very unstable to heat, dilution and dialysis and it is almost entirely inactivated by DEAE-cellulose chromatography or gel filtration. A marked enhancement in its stability is caused by numerous nucleotides. In these experiments at least 920-fold purification was obtained by using dTTP (50μm) as nucleotide protector. The enzyme, purified in presence of dTTP, has a molecular weight about 270 000, an isoelectric point of 6.27, a pH optimum of 8.8 and is stable at 37 °C at least for 10 min. In absence of nucleotide protector, nucleoside phosphotransferase is converted at 37 °C or by gel filtration in a very small active form with a lower molecular weight (about 30 000) and a pH optimum of 7.6.
TL;DR: In this paper, the tangential stress build-up after a sudden imposition of a shear rate and the decay after cessation of steady shear flow have been collected, which is used to further test a constitutive equation already advanced by some of the authors.
Abstract: Some new data in shear flow are presented for two commercial polyisobutylene samples, namely Vistanex LMMH and L 100. In particular beyond a few steady state results, the tangential stress build-up after a sudden imposition of a shear rate and the decay after cessation of steady shear flow have been collected. The data are used to further test a constitutive equation already advanced by some of the authors. The comparison seems to confirm the validity of the proposed model, whose single adjustable parameter is shown to be independent of molecular weight.
TL;DR: In this paper, the structure of 3,4-Dibenzoyl-2,oxobutyrate 4-semicarbazone (3.4) and diethyl phenacyloxaloxalectate (DPE)-3.7-(6H)diones (6c) were assigned.
TL;DR: From the aerial parts of Cleonia lusitanica four previously known diterpenoids have been isolated and a new isopimarane derivative, cleonioic acid, has been obtained.
TL;DR: In this paper, 2.2-Nitrobenzenesulfonyl chloride reacts with ω-aminoacetophenone and 4amino-3,5-dimethyl-isoxazole to give 3 and 7, respectively.
TL;DR: In this article, the reaction of (Alk2SnO)n with OCH·CCl3 gives compounds of elemental formula Alk2snOCH- (CCI3)O (alk = Bun, Octn), probably by addition of the Sn-O bond to the carbonyl group.
01 Dec 1979
TL;DR: Per quest'ultima affezione it Cotrimoxazolo viene attualmente considerato il trattamento di scelta, raggiungendo concentrazioni terapeuticamente efficaci nel parenchima e nel secreto prostatico, a differenza di quasi tutti gli altri antibiotici 0 chemioterapici.
Abstract: Le associazioni fra un sulfamidico .ed il trimethoprim sono state ampiamente adoperate, nel corso degli ultimi anni, nella terapia delle infezioni dell'apparato urinario. 11 Cotrimoxazolo, il piu nota fra tali associazioni, viene utilizzato alla dose di due compresse ogni 12 ore, contenenti ciascuna 80 mg di trimethoprim e 400 mg di sulfametossazolo. n Cotrimoxazolo e efficace, in vitro ed in vivo, sulla maggior parte dei ceppi batterici responsabili delle infezioni urinarie (specialmente E. coli, Klebsiella, Aerobacter, alcune specie di Proteus, Streptococcus faecalls), Gli effetti tossici secondari sono, in genere, rari e di scarsa entita, Particolarmente degna di rilievo e l'elevata concentrazione che il Cotrimoxazolo raggiunge nei tessuti, oltre che nelle urine. Il farmaco trova pertanto utile applicazione nelle pielonefriti e nelle prostatiti. Per quest'ultima affezione it Cotrimoxazolo viene attualmente considerato il trattamento di scelta, raggiungendo concentrazioni terapeuticamente efficaci nel parenchima e nel secreto prostatico, a differenza di quasi tutti gli altri antibiotici 0 chemioterapici. Concentrazioni battericide vengono ottenute anche nelle secrezioni vaginali. Cia ne consente un utile impiego nelle donne affette da cistiti secondarie alla presenza di germi patogeni nelle regioni periuretrali e vulvo-vaginali. La terapia per via orale e agevole e di basso costo. 11 limite piu importante e rappresentato dalla inefficacia quasi costante sulle infezioni da Pseudomonas aeruginosa, condizione piuttosto frequente nei pazienti urologici.t'! e dalla resistenza di molti stipiti di Proteus. Il suo usa e sconsigliato durante la gravidanza ed i primissimi mesi di vita.