Showing papers by "University of Palermo published in 1970"
TL;DR: In this article, a trigonale bipyramidal geometry is proposed for the structure of R2SnL, where the two carbon (R) atoms and the azomethine nitrogen atom are allocated in the trigonal plane and the O, O or S, O ligand atoms lie in axial position.
Abstract: Komplexverbindungen vom Typ R2SnL (R = CH3, C6H5; L ist ein dreizahniger ONO- oder SNO-Ligand) werden dargestellt und ihre IR-, KMR- und elektronischen Spektren untersucht, um die Strukturen zu klaren.
Als Liganden (LH2) werden benutzt: 4-(2-Benzothiazolinyl)-pentan-2-on, (hier zum ersten Mal dargestellt); 3-(o-Hydroxyphenylamino)crotonophenon; 2-(o-Hydroxyphenyl)-benzothiazolin; und N-o-Hydroxybenzyliden-o′-hydroxyanilin.
Im festem Zustand umgeben die organischen Liganden L2− das Zinn(IV)-Atom als ebene dreizahnige Liganden. Die R2SnIV-Reste sind wahrscheinlich nicht linear. Eine mogliche Anordnung der Liganden ist eine trigonale Bipyramide, in der die zwei R-Reste und das Stickstoffatom in der trigonalen Ebene und die zwei Sauerstoffatome bzw. das Sauerstoff- und das Schwefelatom in den zwei anderen Positionen auf beiden Seiten der Ebene liegen.
Complexes R2SnL (R = CH3, C6H5; L2− = tridentate ONO and SNO ligands) are synthesized, and their configuration is investigated by vibrational, PMR and electronic spectroscopy.
The ligands H2L are: 2-pentanone-4-(2-benzothiazolinyl), (prepared for the first time); 3-(o-hydroxyphenylamino)crotonophenone; 2-(o-hydroxyphenyl)benzothiazoline; 2,2′methylidynenitrilo diphenol. Their configuration at the solid state is discussed. The ligands seem to coordinate the tin (IV) atoms as planar tridentates, in the dianion Schiff base form.
The R2SnIV moieties very probably assume a bent configuration in R2SnL. Hypotheses on the structure of R2SnL are then advanced: the possible occurrence of a quasi trigonal bipyramidal geometry, where the two carbon (R) atoms and the azomethine nitrogen atom are allocated in the trigonal plane and the O, O or S, O ligand atoms lie in axial position, is discussed.
57 citations
TL;DR: In this article, the conditions presiding to the production of geothermal energy are reviewed in order to determine how and how far the different geochemical data are relevant to the objectives of Geothermal exploration.
54 citations
TL;DR: The cytoplasmic environment in the egg and in the pre-gastrula embryo is such that when nuclei from neurula endoderm cells are transplanted into enucleated eggs, they stop ribosomal RNA synthesis, although they synthesize DNA-like and soluble RNAs and are able to sustain normal development of the embryo.
Abstract: AMPHIBIAN oocytes provide very convenient material for the study of the mechanisms that control ribosomal RNA synthesis because their pattern of ribosomal RNA synthesis does not change greatly during oogenesis. During the lampbrush stage of oogenesis (stage 4) more than 97 per cent of the RNA synthesized per unit time in the oocytes is ribosomal. This happens because the genes for ribosomal RNA are specifically amplified3–5 to such an extent that the oocyte nucleus (germinal vesicle) has an rDNA content approximately 1,500 times more than the haploid amount4. On the other hand, in mature oocytes (stage 6) no ribosomal RNA is synthesized1,2, although the extra copies of the ribosomal cistrons are still present. There must therefore be a mechanism in these cells which turns off ribosomal RNA synthesis. It should also be remembered that ribosomal RNA synthesis resumes only after the embryo has reached gastrulation6,7. Furthermore, the cytoplasmic environment in the egg and in the pre-gastrula embryo is such that when nuclei from neurula endoderm cells, active in ribosomal RNA synthesis, are transplanted into enucleated eggs, they stop ribosomal RNA synthesis, although they synthesize DNA-like and soluble RNAs and are able to sustain normal development of the embryo. Ribosomal RNA synthesis in the nuclear transplanted embryos resumes only at gastrulation8. It has been suggested9,10 that this cytoplasmic control of the pattern of nuclear transcription could be mediated through a factor which specifically inhibits ribosomal RNA synthesis.
47 citations
TL;DR: This work has used the scanning electron microscope to investigate the changes that occur in scalp hair during infection with Trichophyton violaceum and presents evidence that their hyphae dig tunnel-like burrows into the hair shaft, dissociating hair into keratin fibrils.
33 citations
TL;DR: A search for pulsed gamma ray emission from NP 0532 has been carried out with a balloon-borne experiment using a spark chamber as the central detector.
Abstract: A SEARCH for pulsed gamma ray emission from NP 0532 has been carried out with a balloon-borne experiment using a spark chamber as the central detector. This pulsar, situated in the Crab Nebula, is already known to pulsate in the radio, optical and X-ray range1–5.
29 citations
TL;DR: A study was made of the serum insulin level after the intravenous administration of glucose in two groups of normal subjects—18 in the 60–85 age bracket and 16 in the 23–45 age bracket, which had a normal coefficient of glucose utilization and a normal blood glucose curve after intravenous Administration of glucose.
Abstract: A study was made of the serum insulin level after the intravenous administration of glucose (0.33 gm/ kg) in two groups of normal subjects—18 in the 60–85 age bracket, and 16 in the 23–45 age bracket. All had a normal coefficient of glucose utilization and a normal blood glucose curve after intravenous administration of glucose. Serum insulin was assayed by the radio-immunological method, with use of an ion exchange resin. Blood samples were drawn at 2, 5, 10, 30, 45 and 60 minutes after the end of the glucose infusion.
In the elderly subjects the maximal value was reached only after 5 minutes and the mean value was 39± 9 µU/ml (range, 27–50), whereas in the younger subjects the serum insulin level rose immediately, reaching a maximal value 2 minutes after glucose infusion, the mean value being 54 ± 10 µU/ml (range, 42–66). Thus the response of the pancreatic beta-cells to functional stimulation in the elderly subjects was slower and weaker than in the younger ones, although there was no decrease in glucose tolerance. There were no differences with respect to the peripheral utilization of insulin.
19 citations
18 citations
TL;DR: The essential role of arginine for plaque formation of measles virus is suggested by experiments in whichArginine added to the agar overlay restored the plating efficiency of measlesirus in cultures maintained in a minimal nutrient medium.
Abstract: Presence of mycoplasma in MK cell cultures caused an inhibition of measles virus, as revealed by a lower plating efficiency. When arginine is supplemented to the cell-system, mycoplasma contaminated cells yield plaque titers as high as those of uncontaminated cells. The essential role of arginine for plaque formation of measles virus is suggested also by experiments in which arginine added to the agar overlay restored the plating efficiency of measles virus in cultures maintained in a minimal nutrient medium.
17 citations
TL;DR: Quasi-localized MO's have been constructed for the π electron system of the three pyridone isomers as discussed by the authors, where the electron system is composed of three different isomers.
Abstract: Quasi-localized MO's have been constructed for the π electron system of the three pyridone isomers.
14 citations
TL;DR: In this paper, the kinetics of the reaction of a series of 2-nitro-3-bromo-5-X-thiophenes with sodium thiophenoxide in methanol were determined.
10 citations
DOI•
01 Jan 1970TL;DR: In this paper, a generalised model is described for the analysis of the pollutant substances released in the atmosphere by urban transportation means, which essentially requires data referring to the running transportation fleet, year by year.
Abstract: In this paper a generalised model is described for the analysis of the pollutant substances released in the atmosphere by urban transportation means. It essentially requires data referring to the running transportation fleet, year by year, that are generally on disposal of the local administrators through official data-bases. Pollutant emissions are here taken into account by means of the algorithms provided by the COPERT methodology, that applies to many European countries.The method, by means of a suitable statistical analysis of data concerning the running car fleet, allows also the definition of an useful indicator, that is the "yearly average vehicle", that can be assumed as representative of the average pollutant emissions of a given urban context. This indicator can be adopted for suitably ranking the environmental effects produced by different policy options concerning the transportation sector.
TL;DR: The mechanism of the action of ethionine (ethyl analog of methionine) on sea urchin embryo development was investigated and radioactivity from ethyl-labeled l -ethionine was detected in DNA, mainly in its pyrimidine bases, but no evidence of DNA ethylated bases was found.
TL;DR: In this article, the authors dealt with thermal stresses that arise in discs with eccentric holes, such as are employed in the rotors of multi-stage gas turbines, and analyzed the stress distribution by the photothermoelastic method CR 39 sheets were used as the material and dry ice as the refrigerant.
Abstract: The paper deals with thermal stresses that arise in discs with eccentric holes, such as are employed in the rotors of multi-stage gas turbines The stress distribution was analysed by the photothermoelastic method CR 39 sheets were used as the material and dry ice as the refrigerantThe effect of several geometric parameters on stress distribution, especially the influence of adjacent holes, was investigated by testing 32 configurations of discsCurves that allow the determination of the peak stresses and optimum spacing of holes are given
TL;DR: It is shown that female rats, three months after castration, emit a lower number of responses, and the effect of hormonal treatment lasts for the duration of the experiments.
TL;DR: The complete configuration of atractyligenin has been obtained by a three-dimensional single-crystal X-ray difiraction study as mentioned in this paper, and the configuration of the epoxy group has been confirmed.
TL;DR: Evidence is presented showing that ribosomes isolated from several eucaryotic (plant and animal) organisms exhibit ample variations of the composition of their protein moiety and that the degree of dissimilarity correlates with thedegree of taxonomic kinship of the organisms from which the ribosome were derived.
Abstract: The data presented and discussed in this report summarize evidence showing that ribosomes isolated from several eucaryotic (plant and animal) organisms exhibit ample variations of the composition of their protein moiety and that the degree of dissimilarity correlates with the degree of taxonomic kinship of the organisms from which the ribosomes were derived. They also provide evidence that (a) the 80-S ribosomes isolated from the cytoplasmic matrix of higher plants and yeast and the 70-S ribosomes derived from both chloroplasts and mitochondria are endowed with highly dissimilar protein complements, (b) the organellar (67-S) ribosomes derived from the chloroplasts of more or less distantly related plants exhibit a greater degree of dissimilarity than the corresponding 78-S ribosomes derived from the extra-chloroplast, extramitochondrial portion of the cytoplasm, i.e., in distant organisms the protein composition of cytoplasmic ribosomes tends to be more congruent than that of organellar ribosomes...
TL;DR: Das Rechenprogramm zur Berechnung der Farbdifferenz fur eine elektronische Tischrechenmaschine wurde aufgestellt as discussed by the authors.
Abstract: Das Rechenprogramm zur Berechnung der Farbdifferenz fur eine elektronische Tischrechenmaschine wurde aufgestellt, und zwar a) fur die vom National Bureau of Standards angenommene Formel vonJudd undHunter und b) fur die von der Internationalen Kommission fur das Beleuchtungswesen (CIE) angenommene Formel vonWyszecki. Die vorgeschlagene Rechenmethode kann von nicht qualifiziertem Personal durchgefuhrt werden. Die fur die Berechnung notige Zeit wird von 1 Stunde auf 80 Sekunden verkurzt.
TL;DR: In this article, the second harmonic generation by an isolated spin in a cavity is described when both the ω driving field and the 2ω detected field are along the x axis, the static field H o coinciding with the z -axis.
TL;DR: In this paper, the second harmonic generation at microwave frequency by a spin S = 1 2 in a cavity has been studied as a function of the external magnetic field using a resolvent technique, and the average transition rates to states with an increased number of double frequency photons has been calculated.
TL;DR: The rapid and frequent exchange of the 70S ribosomes in Escherichia coli, with their 50S and 30S subunits, has been established by kinetic studies and heavy isotope techniques and still very little is known about protein initiation in eucaryotic organisms.
Abstract: The rapid and frequent exchange of the 70S ribosomes in Escherichia coli, with their 50S and 30S subunits, has been established by kinetic studies and heavy isotope techniques (1-4) . While these studies were in progress, it was reported that ribosomes of Candida krusei, a eucaryote, undergo frequent exchange of ribosomal subunits (5) . It has been suggested that ribosomes dissociate and re-form between successive rounds of protein synthesis . The mechanism of polypeptide initiation in procaryotes has been well documented (6-8) . On the other hand, still very little is known about protein initiation in eucaryotic organisms . Early works on ribosomal synthesis in HeLa cells suggested that ribosomal subunits participate in polyribosome formation prior to being assembled in single monosomes (9, 10). It has also been shown that vaccinia-virus RNA becomes associated with the smaller ribosomal subunit before appearing on polysomes (11) . The cellular slime molds have been mainly studied as a model organism for problems concerning morphogenesis and differentiation (12, 13) . The life cycle can be easily subdivided into a phase of growth (cell division) and differentiation . During the growth phase, the amebas feed on bacteria and divide by mitosis approximately every 3 hr. These organisms thus offer great advantages to study ribosome dissociation and re-assembly by both kinetics and heavy isotope techniques .
TL;DR: In this paper, an approximate rapid method is described for calculating in the moire technique the transversal strain directly from the longitudinal strain distribution across sections of symmetry, based on evaluation of the load transmitted through the section and is corroborated by two examples.
Abstract: An approximate rapid method is described for calculating in the moire technique the transversal strain directly from the longitudinal strain distribution across sections of symmetry. The method is based on evaluation of the load transmitted through the section and is corroborated by two examples.
TL;DR: In this paper, the role of media under the lens of scrutiny in order for getting new substantial and constructive course of actions in the way news are covered and fabricated. But, the role has changed to other shapes, which leads media to be producers of "the spectacle of disaster" and ushers audience into a biased view of reasons behind terrorism.
Abstract: Mass-media plays a crucial role in the society, oddly as moral reinforces whose function consisted in the thematization of social issues. Nonetheless, in the consuming society, we are witness how this role has changed to other shapes, which leads media to be producers of “the spectacle of disaster”. The 9-11 has marked a turning point not only showing how media tergiversates the meaning of reality but also how news are covered and fabricated. This ushers audience into a biased view of reasons behind terrorism. This essay review places the role of media under the lens of scrutiny in order for getting new substantial and constructive course of actions in the way news are covered.