[en] Gels based on attapulgite, obtained by mixing attapulgite, a clay, with water or chemicals have been used as decontaminating agents. The method has been optimized through extensive scale laboratory experiments carried out under standard conditions. A wide variety of materials, used in nuclear technologies, and significant radionuclides have been tested. Gels obtained with water only in some cases allow full decontamination, when acids are added to clay, complete contamination removal, is possible except for extreme pHs radionuclides solution and on non-passivated or porous surfaces. The optimized decontaminating technique has successively been set up and applied on materials contaminated by routine or accident. Laboratory scale results have been confirmed through practical use. Process data are reported. This method is simple to perform and requires no special equipment. No liquid radioactive waste arises from the process and the resulting solid waste can be conditioned with cement

[en] A standarized technique for transferring radionuclides deposited on non-porous solid materials, into a liquid system by means of a two step process, involving the use of suspensions obtained by mixing attapulgus clay with nitric acid solutions, is described. Possible applications of the methodology are the recovery of radionuclides of particular interest, dispersed or deposited on non-porous surfaces and the quantitative determination of radionuclides present on the same kind of surface. 2 refs.; 1 figure; 2 tabs

No abstract available

[en] Results are reported for experiments in which standard samples, artificially contaminated with uranium and thorium salts, were decontaminated using a semi-solid material whose basic constituent was attapulgite (a hydrated magnesium silicate). The application of attapulgus clay suspensions with additions of mineral acids resulted in the almost complete removal of these actinides from various surfaces. Since the results obtained on a laboratory scale were quite satisfactory, the method was applied to real materials, namely a glove box utilized for some years in various and repeated manipulations of natural uranium. This method of decontamination caused no damage to the surface subjected to the treatment, was simple to perform and required no special equipment. No liquid radioactive waste was generated and we were able to recover the glove box for further use. (orig.)

[en] The Bo.S.Co project (Bioremediation of contaminated soils by compost) aims at creating an innovative bioremediation technology ready-to-use and competitive in price. This technology use a particular kind of certified compost that optimizes cleaning processes. Compost, in fact, is a very rich matrix that can supply nutrients, used by the autochthonous microflora. In the present study compost was used to enhance diesel oil and PAHs degradation in two heavily contaminated soils; laboratory scale experiments were performed by preparing four soil-bio piles, under laboratory conditions chemical, microbiological and eco toxic parameters were analyzed at different times. Compost addition was effective in enhancing biodegradation of diesel oil compounds and simultaneous reduction of genotoxicity with respect to the control.

[en] Using a new XMM-Newton observation, we have characterized the X-ray properties of the middle-aged radio-quiet γ-ray pulsar J0357+3205 (named Morla) and its tail. The X-ray emission from the pulsar is consistent with a magnetospheric non-thermal origin plus a thermal emission from a hot spot (or hot spots). The lack of a thermal component from the whole surface makes Morla the coldest neutron star in its age range. We found marginal evidence for a double-peaked modulation of the X-ray emission. The study of the 9' long tail confirmed the lack of extended emission near the pulsar itself. The tail shows a very asymmetric brightness profile and its spectrum lacks any spatial variation. We found the nebular emission to be inconsistent with a classical bow shock, ram-pressure-dominated pulsar wind nebula. We propose thermal bremsstrahlung as an alternative mechanism for Morla's tail emission. In this scenario, the tail emission comes from the shocked interstellar medium (ISM) material heated up to X-ray temperatures. This can fully explain the peculiar features of the tail, assuming a hot, moderately dense ISM around the pulsar. For a bremsstrahlung-emitting tail, we can estimate the pulsar distance to be between 300 and 900 pc. A pulsar velocity of ∼1900 km s^–1 is required, which would make Morla the pulsar with the largest velocity, and high inclination angles (>70°) are preferred. We propose Morla's nebula as the first example of a new 'turtle's tail' class of thermally emitting nebulae associated with high-velocity pulsars.

[en] The middle-aged PSR J0357+3205 is a nearby, radio-quiet, bright γ-ray pulsar discovered by the Fermi mission. Our previous Chandra observation revealed a huge, very peculiar structure of diffuse X-ray emission originating at the pulsar position and extending for >9' on the plane of the sky. To better understand the nature of such a nebula, we have studied the proper motion of the parent pulsar. We performed relative astrometry on Chandra images of the field spanning a time baseline of 2.2 yr, unveiling a significant angular displacement of the pulsar counterpart, corresponding to a proper motion of 0.''165 ± 0.''030 yr^–1 at a position angle (P.A.) of 314° ± 8°. At a distance of ∼500 pc, the space velocity of the pulsar would be of ∼390 km s^–1 assuming no inclination with respect to the plane of the sky. The direction of the pulsar proper motion is aligned very well with the main axis of the X-ray nebula (P.A. = 315.°5 ± 1.°5), pointing to a physical, yet elusive, link between the nebula and the pulsar space velocity. No optical emission in the Hα line is seen in a deep image collected at the Gemini telescope, which implies that the interstellar medium into which the pulsar is moving is fully ionized.

[en] We report the results of a deep XMM-Newton observation of the radio-faint γ-ray pulsar J1741–2054 and its nebula together with the analysis of five years of Fermi Large Area Telescope (LAT) data. The X-ray spectrum of the pulsar is consistent with an absorbed power law plus a blackbody, originating at least partly from the neutron star cooling. The nebular emission is consistent with that of a synchrotron pulsar wind nebula, with hints of spatial spectral variation. We extended the available Fermi LAT ephemeris and folded the γ-ray and X-ray data. We detected X-ray pulsations from the neutron star: both the thermal and non-thermal components are ∼35%-40% pulsed, with phase-aligned maxima. A sinusoid fits the thermal-folded profile well. A 10 bin phase-resolved analysis of the X-ray emission shows softening of the non-thermal spectrum during the on-pulse phases. The radio, X-ray, and γ-ray light curves are single-peaked, not phase-aligned, with the X-ray peak trailing the γ-ray peak by more than half a rotation. Spectral considerations suggest that the most probable pulsar distance is in the 0.3-1.0 kpc range, in agreement with the radio dispersion measure.

[en] We quantitatively establish the sensitivity to the detection of young to middle-aged, isolated, gamma-ray pulsars through blind searches of Fermi Large Area Telescope (LAT) data using a Monte Carlo simulation. We detail a sensitivity study of the time-differencing blind search code used to discover gamma-ray pulsars in the first year of observations. We simulate 10,000 pulsars across a broad parameter space and distribute them across the sky. We replicate the analysis in the Fermi LAT First Source Catalog to localize the sources, and the blind search analysis to find the pulsars. We analyze the results and discuss the effect of positional error and spin frequency on gamma-ray pulsar detections. Finally, we construct a formula to determine the sensitivity of the blind search and present a sensitivity map assuming a standard set of pulsar parameters. The results of this study can be applied to population studies and are useful in characterizing unidentified LAT sources.

[en] We carried out deep optical observations of the middle aged γ -ray pulsar PSR J1741−2054 with the Very Large Telescope (VLT). We identified two objects, of magnitudes m _v = 23.10 ± 0.05 and m _v = 25.32 ± 0.08, at positions consistent with the very accurate Chandra coordinates of the pulsar, the faintest of which is more likely to be its counterpart. From the VLT images we also detected the known bow-shock nebula around PSR J1741−2054. The nebula is displaced by ∼0.″9 (at the 3 σ confidence level) with respect to its position measured in archival data, showing that the shock propagates in the interstellar medium consistently with the pulsar proper motion. Finally, we could not find evidence of large-scale extended optical emission associated with the pulsar wind nebula detected by Chandra , down to a surface brightness limit of ∼28.1 mag arcsec⁻². Future observations are needed to confirm the optical identification of PSR J1741−2054 and characterize the spectrum of its counterpart.