Showing papers by "University of Seville published in 1979"
TL;DR: In this paper, the authors studied the genetics of carotene biosynthesis in the fungus Phycomyces and found that carS mutants overaccumulate β-carotene and carA mutants lack practically all carotenes.
Abstract: Colour mutants are conspicuous and convenient genetic markers, but there have been few studies on the genetics of carotene biosynthesis. Recent work with the fungus Phycomyces has identified two main structural genes: carB , responsible for phytoene dehydrogenase, and carR , responsible for lycopene cyclase. Four copies of the first enzyme and two of the second constitute an enzyme complex carrying out all reactions from phytoene to β-carotene. The pathway is regulated by a variety of environmental agents with the participation of several genes. Thus, carS mutants overaccumulate β-carotene and carA mutants lack practically all carotenes. Surprisingly, carA and carR are segments of a single, bifunctional gene. The investigations carried out with Neurospora and other microorganisms are briefly reviewed from the viewpoint of the results with Phycomyces .
33 citations
TL;DR: In this article, a comparative study of Avrami-Erofeev and diffusion-controlled reactions has been carried out using thermoanalytical data, calculated by assuming a quasi-isothermal heating technique.
24 citations
TL;DR: The authors studied the possible influences on Boole's logic of the writings related to the controversy over the quantification of the predicate between the philosopher William Hamilton and the mathematician Augustus De Morgan.
Abstract: Summary This paper studies the possible influences on Boole's logic of the writings related to the controversy over the quantification of the predicate between the philosopher William Hamilton and the mathematician Augustus De Morgan. As Boole himself testified in the introduction to his book The mathematical analysis of logic (1847), this controversy was the external agent that stimulated him into writing up his earlier thoughts about a new conception of logic. But in addition to the external role that was played by the controversy, it seems that other kinds of influences on Boole of Hamilton's and De Morgan's ideas about logic, which were made explicit in writings related to the controversy, can also be traced.
23 citations
TL;DR: There are two kinds of redox pairs whose reduction may be coupled with the photooxidation of water to molecular oxygen: those with potential levels similar to the hydrogen electrode and must accept electrons at the reducing side of photosystem I, and those with positive potentials and can interact at the reduced side of photoystem II as mentioned in this paper.
22 citations
TL;DR: A previously unreported association of Brenner and adenomatoid tumor found in the tunica vaginalis testis is presented and ultrastructural features found in mesothelial cells such as intercellular spaces, deeply indented nuclei, tonofilaments and tight desmosomes are presented.
Abstract: A previously unreported association of Brenner and adenomatoid tumor found in the tunica vaginalis testis is presented. Many ultrastructural features found in mesothelial cells such as intercellular spaces, deeply indented nuclei, tonofilaments and tight desmosomes, were also shared by cells present in both neoplastic patterns. The previous histogenetic origins ascribed to testicular Brenner tumors are discussed and the evidence for their origin in the mesothelium considered. Cancer 43:539–543, 1979.
20 citations
TL;DR: The effect of grinding on the kinetics and thermodynamics of thermal decomposition reactions of alkaline-earth carbonates has been studied in this paper, showing that the reaction takes place through the same activated complex, its thermodynamic constants depending on the nature of the cation.
19 citations
TL;DR: In this paper, Picolinealdehyde salicyloylhydrazone reacts with vanadium(V) to produce a yellow 1:1 complex (λmax = 400 nm, ϵ = 2.17 × 104 liters · mol−1 cm−1) in aqueous ethanolic solution.
16 citations
TL;DR: In this article, a semi-automatic spectrophotometric method is described for the catalytic titration of ethylenediaminetetraacetic acid, based on its inhibitory effect on the manganese (II)catalyzed aerial oxidation of 1,4-dihydroxyphthalimide dithiosemicarbazone.
14 citations
TL;DR: In this article, a TPD technique is described in which mass spectrometic detection and normal pressure of the carrier gas are employed, using the thermal decomposition of MgCO3 as a test reaction, and it is proved that kinetic studies of each desorbed product can be realized through the whole signal time curve in a nonrestrictive way.
Abstract: A TPD technique is described in which mass spectrometic detection and normal pressure of the carrier gas are employed. Using the thermal decomposition of MgCO3 as a test reaction, it is proved that kinetic studies of each desorbed product can be realized through the whole signal-time curve in a nonrestrictive way.
11 citations
TL;DR: The synthesis and analytical properties of bipyridylglyoxal bis(4-phenyl-3-thiosemicarbazone) are described and the solubility, spectral characteristics and pK values are reported, as well as the absorptivity and stoichiometric ratio of metal chelates formed.
11 citations
TL;DR: In vitro inactivation of Chlorella fusca NADH-nitrate reductase can be obtained by preincubation of the enzyme with reduced nicotinamide adenine dinucleotide because ADP cooperates with NADH in this inactivation.
TL;DR: A review of the inorganic analytical uses of phenylhydrazines and phenyl-hydrazones is given in this paper, where they have found use in qualitative and gravimetric analysis, as indicators of high alkalinity and in spectrophotometric and catalytic procedures.
TL;DR: In this paper, the critical radii obtained from analyses of the elastic scattering of alpha-particles by a range of nuclei are found to be closely connected with the nuclear matter distributions obtained by summing the squares of single-particle wavefunctions.
TL;DR: The ultrastructural features were indicative of maturity in all cell lines and even the neurons exhibited well formed synapses, and marked cytoplasmic fibrillary change, similar to that found in central nervous system gliosis, was observed in the astrocytes.
Abstract: An ultrastructural study of mature (grade o) neurogenic peritoneal implants from an ovarian immature teratoma grade 1 is presented. The presence of different types of neuroectodermal cells challenges the current terminology of this lesion, which implies a single proliferating cell type. The ultrastructural features were indicative of maturity in all cell lines and even the neurons exhibited well formed synapses. Marked cytoplasmic fibrillary change, similar to that found in central nervous system gliosis, was observed in the astrocytes. The ependymal cells had abnormal cilia with an altered configuration and number of microtubules.
TL;DR: In this paper, a cell for the measurement of the excess enthalpy of volatile liquids in a microcalorimeter was described, which was calibrated with n -hexane + cyclohexane at 298.15 K.
TL;DR: In this paper, 6.6-Methylpyridine-2-aldehyde p -nitrophenylhydrazone is suggested as an indicator for colorimetric pH measurements in the high-alkaline range.
TL;DR: In this paper, a linear resistive multiport based on simple modules is proposed, which allows voltage-controlled as well as current-controlled ports and every port may be grounded or floating, i.e. it is possible to design either (n + l)-terminal or n-port networks.
Abstract: This paper gives a new method for designing an arbitrary linear resistive multiport based on simple modules. The new approach presents two distinctive features which are not presently shared with other related design procedures. First, it allows voltage-controlled as well as current-controlled ports. Secondly, every port may be grounded or floating, i.e. it is possible to design either (n + l)-terminal or n-port networks
01 Apr 1979
TL;DR: In this paper, the effects of ageing on the plastic properties of NiO single crystals were determined in samples doped with 20 ppM to 2 500 ppM manganese.
Abstract: The effects of ageing on the plastic properties of NiO single crystals were determined in samples doped with 20 ppM to 2 500 ppM manganese. Microhardness and slip band length were measured. Maximum microhardness occurs for very short ageing time at 550 °C and 850 °C ; on the contrary, slip band length shows no minimum and shows strengthening only after ageing at 550 °C. These effects can be attributed to various aggregation states of point defects.
TL;DR: Through an analysis of the expression of the autocorrelation function of the velocities in the matrix representation, an identification is made of all the matrix elements which lead to the so-called t or ϵ explicit divergence.
Abstract: Through an analysis of the expression of the autocorrelation function of the velocities in the matrix representation, an identification is made of all the matrix elements which lead to the so-called t or ϵ explicit divergence. The terms in the expansion can be easily summed and as a result the divergence is eliminated. A comparison with the procedure recently developed by Bartis and Oppenheim is made.