No abstract available

[en] Caffeine (10^-2 M) induced a high level of chromatid aberrations in neural ganglia of third-instar larvae of Drosophila melanogaster only when it was added to cells in late G₂ and mitotic prophase. No aberrations were observed after treatment in late S-middle G₂ or C-mitosis. We observed that, in these stages, caffeine strongly increased X-ray-induced damage (500 R). This potentiation was quantitatively similar. But it involved all types of aberration after treatment in C-mitosis, and essentially isochromatid deletions and chromatid exhanges after treatment in S-G₂. Some hypotheses are put forth to explain the possible mechanism of action of caffeine in the potentiation of X-ray-induced damage. (orig.)

[en] The lack of plant data is, of course, a typical occurrence for plants under construction, yet the need for an operators training simulator typically arises well before the start-up of the plant itself. As a consequence, the process of validating the mathematical models on which the training simulator is based ought to rely upon measurements from similar plants, when they are available. The use of a computer code like RETRAN, however constitutes one way to provide data where none exists. Due to its characteristics of modularity and extensive validation, RETRAN appears to be particularly well suited as a reference code for testing a number of simulator system models. The two systems considered, i.e. a feedwater system consisting of two parallel trains of feedwater heaters with pumps, valves and by-pass lines, and the once-through boiler of an oil fired power station, were chosen because they are significant examples of two types of systems to be treated in plant simulators: quasi-incompressible single phase systems to be treated in plant simulators: quasi-incompressible single phase systems and compressible two phase systems. The most important differences between the simulator modeling technique and the basic RETRAN modeling approach are also briefly discusses in order to makes the comparison fully appreciable

[en] Experiments conducted on the x irradiation of neural ganglia of Drosophila melanogaster are described. The ganglia were placed in saline containing colchicine. After two hours, they were irradiated and then samples were fixed at 5, 15, 25, 35 minutes from the beginning of irradiation. The results obtained show that the aberration level increases with time subsequent to fixing. This increase takes place first for chromatid deletions and then for isochromatid deletions and chromatid exchanges. Gaps and subchromatid exchanges do not, on the contrary, show any increase with time. We did not observe a difference in radiosensitivity between the sexes. Some hypotheses are put forth in an attempt to explain these results

[en] ¹H NMR spectra of the porcine pancreatic secretory trypsin inhibitor (PSTI) have been recorded vs. pH and temperature. Of the two tyrosines, one titrates with a pK of 1.25, while the resonances from the other are pH insensitive in the investigated range 4.8 less than or equal to pH less than or equal to 12. This is consistent with PSTI having one Tyr solvent exposed (Try-20) and the other buried (Tyr-31). The resonances from the lysyl epsilon-CH₂ protons titrate with a pK of 10.95. The titration is accompanied by a pronounced line broadening, which starts near pH 8.5. Between pH 11.5 and pH 12 the epsilon-CH₂ resonances recover their low pH line width. Titration curves for the lysines and Tyr-20 reflect single proton ionization equilibria, suggesting that these residues do not interact among themselves. On the basis of double resonance experiments, combined with analysis of chemical shifts, spin-spin couplngs, and line widths, all methyl resonances are identified and followed as functions of pH and temperature. The γ-CH₃ doublet from the N-terminal Thr-1 is assigned by comparison between spectra of forms I and II of the inhibitor, the latter lacking the first four residues of form I. The β-CH₃ resonance from Ala-7 is also assigned. Proton resonance parameters of methyl groups are shown to afford useful NMR probes for the characterization of local nonbonded interactions, microenvironments, and mobilities

[en] The correlation between damage induced in somatic cells and that induced in germinal cells of the same genetic pool of individuals is important in establishing the possibility of extrapolation of this damage to the offspring. Drosophila melanogaster was used to compare cytologically the frequency of aberrations induced in the cells of somatic ganglia and in the spermatocytes I of males irradiated with 625 R X-rays. The spermatocytes were more sensitive than the gangliar cells to radiation: the aberrations induced in the spermatocytes I were three times more frequent than those induced in the ganglia. The distribution of the aberrations was, however, similar. The most important variable element lies in our observing no symmetrical exchanges in the spermatocytes. This result seems to us to be related to the fact that in the males of D. melanogaster there is no crossing-over

[en] The aim of this work is to apply a methodology of automation function design to an open cycle gas-turbine for electrical energy production. This methodology, based on superposed automata networks, leads to a flexible design documentation that is easily comprehensible, configuration according to the needs, easy to maintain ect. Operational procedures either in normal and emergency conditions are considered

[en] ¹H-NMR spectra of Aerosol-OT (AOT) reverse micelles in isooctane are reported at various water contents and several temperatures. The resonances from the AOT protons near the polar head are completely assigned. The NMR parameters (chemical shift and linewidth) appear to be suitable probes for characterizing the physico-chemical state of micelles, in particular in order to define the range in which the system is fully homogeneous and transparent. The results correlate well with those obtained from optical density measurements. Lanthanide ions dissolved in the water phase selectively perturb the AOT resonances from the protons nearest to the polar head; conversely, non-polar shift reagents soluble in the organic phase do not cause appreciable effects on any of the observable signals. (Auth.)

[en] The interaction of AOT reverse micelles with Met-enkephalin, the pancreatic secretory trypsin inhibitor (PSTI) and the epidermal growth factor (EGF) is examined by NMR methods and the three systems are compared. While Met-enkephalin adopts a folded conformation, PSTI appears to become highly flexible, suggestive of a non-specific interaction with the micelles. On the other hand, the EGF spectrum shows that, although the main globular features of the protein are retained in the presence of AOT, the C-terminal fragments has to rearrange its conformation when put in contact with the micelle wall. (Auth.)

[en] Mammalian cells were cultured in parallel at the Instituto Superiore di Sanita', in the presence of standard radiation background, and at the INFN-Gran Sasso underground Laboratory, exposed to low radiation background. Both cultures were grown up to six months and periodically tested to check for the onnset of metabolic changes and different sensitivity to genotoxic damage caused by ionizing and UV radiation, as well as by chemical agents. These tests include measurements of enzyme activities protecting from oxidative cell damage, induction of opoptosis and mutation