Showing papers by "University of Bologna published in 1975"
TL;DR: A unitary identification procedure for linear multivariable systems based on the direct determination of a set of invariant indexes completely describing the input-output structure of the system is described.
277 citations
TL;DR: Systematic investigations of the photochemistry of transition metal complexes with the aim of designing suitable systems for solar energy conversion have long-range promise and merit further consideration.
Abstract: The basic concepts for direct and catalyzed photodissociation of water have been summarized. Water dissociation in closed-cycle processes based on endothermic photochemical reactions offers a potential solution to the solar energy conversion problem. Transition metal complexes, whose excited state chemistry is extremely rich (23, 24) although mostly unexplored, are, in principle, suitable "catalysts" for cycles of this type. The most interesting cycles are those involving metal hydrido complexes or binuclear complexes in which the two metal atoms are bound into a macrocyclic ligand. Systematic investigations of the photochemistry of transition metal complexes with the aim of designing suitable systems for solar energy conversion have long-range promise and merit further consideration.
200 citations
TL;DR: The cytochromes produced during aerobic growth were immunologically indistinguishable from those produced during photosynthesis, and the implications of these results to energy coupling in the photosynthetic bacteria are discussed.
179 citations
178 citations
TL;DR: The results obtained with this method are compared with those obtained by the standard Liebermann-Burchard reaction on the same samples and are found to be in close agreement.
172 citations
TL;DR: In this paper, the authors employed the force method to calculate the force constants of HF, H2O, NH3, CH4, HCl and SiH4 using wavefunctions generated by both the STO•3G and 4•31G basis sets.
Abstract: The force method has been employed to calculate the force constants of HF, H2O, NH3, CH4, HCl, H2S, PH3, and SiH4. The computations were performed using wavefunctions generated by both the STO‐3G and 4‐31G basis sets that are standard in the Gaussian 70 program system. The 4‐31G basis set provides reliable harmonic force constants, but those computed with the STO‐3G basis set are poor. Cubic force constants computed at the 4‐31G level are fair to very good. Cubic stretching force constants are reproduced especially well, regardless of the basis set. Quartic stretching force constants are good, but quartic bending constants are in error. A component analysis has been developed and relations have been found that may be useful for qualitative and quantitative discussions.
142 citations
TL;DR: A delayed excitatory effect, that increased over the days when morphine is given chronically, remained unchanged when the same dose of morphine was given 8 months after the cessation of chronic treatment.
101 citations
68 citations
TL;DR: The results show that sleep and thermoregulatory processes interact and, at 0 degrees C ambient temperature, become mutally exclusive.
67 citations
TL;DR: In this article, a new method of calculating the lepton anomalous magnetic moment, combining the features of the dispersive and the mass operator approach, was introduced, and applied to the study of the contributions to the electron and muon anomalies coming from QED vertex graphs containing vacuum polarization insertions.
66 citations
TL;DR: In this article, the bridging azido group in these new complexes reacts with carbon monoxide to give the corresponding cyanato-bridged complexes, whereas with CS 2, CF 3 CN and SCNC 6 H 5 they undergoes 1,3-cycloaddition to form thiatriazolate or tetrazolate groups bridging in dimeric complexes of the type [(diene)CH) 3 ) (M = Pd, Pt), [(π-allyl)Pd(N 3 CS 2 ] 2,[(π-all lt)P
01 Jan 1975
TL;DR: In this paper, the authors present a survey of very recent results in combinatorics of finite planes and problems connected with the existence of finite geometrical structures, and discuss the development of some topics considered in section 3.2 of Dembowski's book [21].
Abstract: In this lecture we intend to present a brief survey of very recent results. We shall be interested in the development of some topics considered in section 3.2 of Dembowski’s book [21] (Combinatorics of finite planes) and in problems connected with the existence of finite geometrical structures.
TL;DR: It is shown that in ETP there is a decreased accessibility of the long chain quinones in comparison with the lower homologs, and that the mechanism of CoQ 3 inhibition is probably related to its insufficient rate of reoxidation by the following segment of the respiratory chain when it has been reduced by NADH dehydrogenase.
TL;DR: The effect of both organic solvents on ATPase may be closely related to changes occurring in the lipid environment which might be transferred to the enzyme activity via a conformational change of the enzymic protein.
TL;DR: A regulatory role of spermine at the level of genome transcription is suggested by isolated rat liver nuclei demonstrating an increased ability to synthesize RNA in the presence of either s permine or spermidine, showing a biphasic effect.
Abstract: Isolated rat liver nuclei demonstrate an increased ability to synthesize RNA in the presence of either spermine or spermidine. Spermidine has more effect on the low-salt alpha-amanitin-insensitive reaction, and spermine has more effect on the high-salt alpha-amanitin-sensitive reaction. Spermine is effective at concentrations of 0.1 mM and 1 muM, showing a biphasic effect. The RNA polymerase activity associated with nuclear chromatin is increased in the presence of spermine only at a concentration of 0.1 mM. Aso the transcription of deproteinized liver DNA by liver form-B polymerase or Escherichia coli enzyme is more efficient in the presence of 0.1 mM-spermine. Only when liver chromatin is transcribed by its homologous enzyme (and not by E. coli enzyme) is spermine active at both 0.1mM and 1 muM as in purified nuclei. The lower concentration of spermine (1 muM) is able to affect chromatin transcription by increasing the affinity of chromatin for the enzyme. Our findings suggest a regulatory role of spermine at the level of genome transcription.
TL;DR: By measurements of polymerization rate, grafting efficiency and number-average molecular weight of free and grafted polystyrene, the α-dicumyl peroxide initiated polymerization of styrene on cis-1,4 polybutadiene at 100°C and at low extents of reaction was studied.
TL;DR: A radioimmunoassay was developed which allows detection of as little as 0.5 ng of amanitins in 1 ml of serum and the clearance of α-amanitin from the blood of poisoned mice was measured.
Abstract: The production of antibodies against amanitins is described. By means of these antibodies, a radioimmunoassay was developed which allows detection of as little as 0.5 ng of amanitins in 1 ml of serum. By this method, the clearance of α-amanitin from the blood of poisoned mice was measured.
TL;DR: The hypothesis is made that in the obese child the function of the pituitary-adrenal axis does not differ from the norm thanks to the adaptation of the ACTH secretion to the greater of the adrenal glands to this hormone.
Abstract: The behavior of the secretion of ACTH, GH, and plasma cortisol during the insulin-induced hypoglycemia test on normal and obese children was studied. The secretion of the above-mentioned hormones was determined by calculating the integrals of the curves. The mean values of the integrals of the plasma cortisol and ACTH curves do not show any significant differences between the two groups of children. The mean values of the ratios between the integrals of the plasma cortisol and ACTH curves show a significant difference between the two groups (P smaller than 0.01). Since the mean values of the integrals of the plasma cortisol curves are practically the same in both groups, the difference in the above-mentioned ratios refers to the lower values of the integrals of the ACTH curves found in the obese children. This enables us to make the hypothesis that in the obese child the function of the pituitary-adrenal axis, at least during the insulin test, does not differ from the norm thanks to the adaptation of the ACTH secretion to the greater sensitivity of the adrenal glands to this hormone. In both the groups examined there was no correlation between the secretion of ACTH and plasma cortisol, between ACTH and GH, and between plasma cortisol and GH.
TL;DR: Spermine stimulates the specific radioactivity of RNA of subcellular fractions and acetylation of the arginine-rich histone fractions, involved in the regulation of RNA transcription, is enhanced by spermine.
Abstract: The relationship between polyamines and RNA synthesis was studied by considering the action of spermine on histone acetylation in perfused heart. In addition, the effect of methylglyoxal bis(guanylhydrazone), inhibitor of putrescine-activated S-adenosylmethionine decarboxylase activity, on RNA and polyamine specific radioactivity and on acetylation of histone fractions was also investigated in perfused heart. Different concentrations of spermine and/or methylglyoxas bis(guanylhydrazone) were injected into the heart, 15 min after beginning the perfusion. The results demonstrate that spermine stimulates the specific radioactivity of RNA of subcellular fractions. Acetylation of the arginine-rich histone fractions, involved in the regulation of RNA transcription, is enhanced by spermine. The perfusion with methylglyoxal bis(guanylhydrazone) causes a decrease in the specific radioactivity of polyamines and RNA, and in acetylation of histone fractions. However, spermine is able to reverse the methylglyoxal bis(guanylhydrazone) inhibition when injected simultaneously. From these results we may assume a possible role for spermine in the regulation of RNA transcription.
TL;DR: ATPase activity and ATP-induced energization of photosynthetic membranes from Rhodopseudomonas capsulata are stimulated by phosphate; the maximum stimulatory effect occurs at a concentration between 1 and 2 mM.
TL;DR: In this article, a method of investigation into the voltage endurance of solid dielectrics is described, based upon measurements of the short-time electric strength of specimens prestressed by the same magnitude of ac voltage but for different times.
Abstract: A new method of investigation into the voltage endurance of solid dielectrics is described. This method is founded upon measurements of the short-time electric strength of specimens prestressed by the same magnitude of ac voltage but for different times. By plotting electric strength against the aging time and comparing the experimental points with theoretical patterns, obtained by a theory previously put forward, determination of the coefficient of voltage endurance n is possible in a short time and with good precision. To check the results, other means are also used. The experimental data are plotted on the Weibull paper in order to determine the dimensional coefficient b which is closely related to n. Measurements of nondestructive properties are carried out, too; according to the aging theory remarked above it seems possible, in fact, to determine the coefficent n by means of such measurements. After showing the theoretical background of the new research, experimental data, pertinent to solid insulating materials for medium-and high-voltage cables, are reported. For polyethylene (PE) the data agree very well with the theory, for a value of n equal to 13. Ethylene-propylene rubber (EPR) shows an uneven period in the first hours of stressing, after which the material seems to settle with a high value of n, larger than 20. In both cases the new method has shown its great usefulness in arriving at the result in a very short time and with high reliability.
TL;DR: In this article, the authors compared the results corresponding to a semi-crystallic structure characterized by correlated density fluctuations of the four spin-isospin nucleon types, with those corresponding to the standard Fermi gas homogeneous and isotropic nuclear-matter structure.
Abstract: Variational computations of the binding energy per particle for various models of nuclear matter are reported The main purpose is to compare the results corresponding to a «semi-crystallic» structure characterized by correlated density fluctuations of the four spin-isospin nucleon types, with those corresponding to the standard «Fermi gas» homogeneous and isotropic nuclear-matter structure It is found that, in some cases, the semicrystallic configuration yields more overall attraction (actually less overall repulsion) than the Fermi-gas case, already at (mean) nuclear densities equal to the central density of ordinary (heavy) nuclei This effect becomes more pronounced at higher (mean) nuclear densities; it can, in most cases, be attributed, at least in part, to the tensor component of the nuclear interaction, that averages to zero in the Fermi-gas case, and yields instead an attractive contribution in configurations with appropriately correlated density fluctuations of the four spin-isospin nucleon states All computations are based on realistic one-boson exchange nucleon-nucleon potentials The correlations associated with the strongly repulsive character of the nucleon-nucleon interaction at short range have not been properly accounted for The results of this paper have therefore no immediate phenomenological implications; whether the effect displayed here is preserved when the repulsive core of the nucleon-nucleon interaction is properly taken into account (both in the computations with and without density fluctuations) remains an open question
TL;DR: In this paper, the microwave rotational spectrum of phenylsilane has been investigated in the region from 8 to 27 GHz and the potential barrier has been derived as V 6 = 17.78 cal/mole.
TL;DR: Results are interpreted as evidence that the high-energy state of the membrane induces a conformational change of the ATPase, making it sensitive to attack by N-ethylmaleimide; this conformationalchange might be related to the active state ofThe ATPase.
TL;DR: In this article, a vibrational assignment is proposed for cyclopentadiene and three of its deuterated derivatives, supported by a normal coordinate analysis based on a valence force field.
TL;DR: The results suggest that most of sensitive imput and many systems of stimuli propagation may be mediated by cholinergic mechanisms in the optic tectum of teleosts.
Abstract: A histochemical study has been carried out on the localization of acetylcholinesterase (AChE) in the cerebellum and optic tectum of four species of freshwater teleosts. AChE distribution in the cerebellar cortex of teleosts shows differences among the species examined and, in the trout, also differences between different cerebellar areas. This uneven kind of enzyme distribution corresponds to a similar variety of AChE patterns noticed in other vertebrates, especially mammals. AChE distribution in the optic tectum shows a prevalent pattern characterized by precise laminar distribution of enzymatic activity which is alternatively strong, weak or absent in the different tectal layers. The results suggest that most of sensitive imput and many systems of stimuli propagation may be mediated by cholinergic mechanisms in the optic tectum of teleosts.
TL;DR: To isolate the sexualizing substance, 1200 specimens of Polycelis nigra were homogenized and separated into four fractions by differential centrifugation, which showed structures that can be considered as neurosecretosomes only in the first and second fractions.
TL;DR: In this article, an ab initio SCF geometry optimization on the simple cations H 2 X, with X = F, Cl, NH 2 and PH 2 has been performed at the split valence shell (4-31G) level.
TL;DR: In this article, the ground state electronic structure of p-anisoles and p-thioanisisoles has been investigated with PES and in terms of CNDO/2 calculations coupled with It is explained why the first band of the p-Anisoles shows a sensitivity to substituent effect greater than the first bands of the other bands.
TL;DR: In this paper, the rotational spectrum of ONCl in (0, 0, 1) and excited vibrational states has been determined and the inertia defects in these states have been determined.