Search results for "PLUT"
showing 10 items of 153 documents
Trace analysis of plutonium in environmental samples by resonance ionization mass spectroscopy (RIMS)
1998
Resonance ionization mass spectroscopy (RIMS) is well suited for trace analysis of long-lived radioisotopes in environmental, biological and technical samples. By multiple resonant laser excitation and ionization of the elemental atoms under investigation, an extremely high element selectivity can be achieved. In addition, isotope selectivity is obtained by subsequent mass analysis. The excellent sensitivity results from the large atomic cross-sections in the excitation–ionization process and the good detection efficiency for ions. The element selectivity of RIMS allows a simplified procedure for the chemical preparation of the samples compared to the requirements of thin sources for α-spec…
Fission fragment anisotropy for the 242mAm fission isomer by spin exchange pumping with polarized rubidium vapour
1992
Abstract The foundations of an experiment have been worked out with which, in principle, the spin, hyperfine constants and the isomer shift of the 14 ms fission isomer 242mAm can be measured. Such an experiment would be based on the fission fragment anisotropy signal which has actually been observed in this work after spin exchange pumping with polarized rubidium vapour in an optical buffer gas cell. A decrease of the count rate of (12±4)% has been measured at 90% with respect to the quantization axis. From this result it is concluded that the nuclear spin of the 242mAm fission isomer must be larger than 1. The low-energy fission isomers originating from the 242Pu(d, 2n)242mAm reaction have…
Geochemical Interactions of Plutonium with Opalinus Clay Studied by Spatially Resolved Synchrotron Radiation Techniques
2017
Plutonium plays an important role within nuclear waste materials because of its long half-life and high radiotoxicity. The aim of this study was to investigate with high spatial resolution the reactivity of the more oxidized forms of Pu(V,VI) within Opalinus Clay (OPA) rock, a heterogeneous, natural argillaceous rock considered as a potential repository host. A combination of synchrotron based X-ray microprobe and bulk techniques was used to study the spatial distribution and molecular speciation of Pu within OPA after diffusion and sorption processes. Microscopic chemical images revealed a pronounced impact of geochemical heterogeneities concerning the reactivity of the natural barrier mat…
Geochemistry, tectonic setting and geodynamic significance of late orogenic dikes in the Melibocus Massif, Bergsträsser Odenwald
2001
The Melibocus Massif forms a tonalite pluton in the W’ Bergstrasser Odenwald, which is interpreted as part of a magmatic arc of Devonian to Carboniferous age. Dikes of various compositions intrude frequently this tonalite. Different dike-lithologies are associated with different strike directions. Most dikes show evidence of high-temperature shearing. A probable maximum paleostress direction of ca. 060° can be estimated, i.e. nearly parallel to the known Variscan subduction zone in the Northwest. Due to their ductile deformation under conditions around the Ar-closing temperature of amphibole, intrusion likely occurred during the Carboniferous (Mississippian). The gabbroic to dioritic dikes …
Resistance to the Bacillus thuringiensis bioinsecticide in a field population of Plutella xylostella is due to a change in a midgut membrane receptor.
1991
The biochemical mechanism for resistance to Bacillus thuringiensis crystal proteins was studied in a field population of diamondback moths (Plutella xylostella) with a reduced susceptibility to the bioinsecticidal spray. The toxicity and binding characteristics of three crystal proteins [CryIA(b), CryIB, and CryIC] were compared between the field population and a laboratory strain. The field population proved resistant (greater than 200-fold compared with the laboratory strain) to CryIA(b), one of the crystal proteins in the insecticidal formulation. Binding studies showed that the two strains differ in a membrane receptor that recognizes CryIA(b). This crystal protein did not bind to the b…
L'anima degli animali. Aristotele, frammenti stoici, Plutarco, Porfirio
2015
E' lecito maltrattare gli animali? E mangiarli? Molto del dibattito odierno sulla natura e sui diritti degli animali ha avuto prodromi antichi, anche se con categorie diverse dalle nostre. Il libro è una selezione di testi chiave sul tema, ritradotti per l'occasione e accompagnati da un commento storico-filologico, aprendo suggestive connessioni con la modernità. Il volume raccoglie l'ottavo e il nono libro della Historia animalium di Aristotele, i frammenti degli stoici sugli animali, i tre trattati di Plutarco sul vegetarianismo e sulla "questione animale" (il De esu carnium, il Bruta animalia ratione uti e il De sollertia animalium) e il De abstinentia di Porfirio
Extending PluTo for Multiple Devices by Integrating OpenACC
2018
For many years now, processor vendors increased the performance of their devices by adding more cores and wider vectorization units to their CPUs instead of scaling up the processors' clock frequency. Moreover, GPUs became popular for solving problems with even more parallel compute power. To exploit the full potential of modern compute devices, specific codes are necessary which are often coded in a hardware-specific manner. Usually, the codes for CPUs are not usable for GPUs and vice versa. The programming API OpenACC tries to close this gap by enabling one code-base to be suitable and optimized for many devices. Nevertheless, OpenACC is rarely used by `standard programmers' and while dif…
Temperature, fluid content and rheology of localized ductile shear zones in subsolidus cooling plutons
2020
Temperature and fluid content are critical parameters that control rock rheology and strain localization in the continental crust. Here, we determine by thermodynamic modelling the urn:x-wiley:02634929:media:jmg12553:jmg12553-math-0004 of localized ductile shearing during cooling of three different granitoid plutons: the Rieserferner and the Adamello plutons in the Italian Alps, and the Lake Edison pluton in the Sierra Nevada—USA. Shear zones exploited precursor joints, associated veins and alteration zones. urn:x-wiley:02634929:media:jmg12553:jmg12553-math-0005 and P−T phase diagram sections were computed with Perple_X in the system MnO−Na2O−CaO −K2O−FeO−MgO−Al2O3−SiO2−H2O−Fe2O3. The phase…
Resonance ionization mass spectroscopy for trace determination of plutonium in environmental samples
1997
Resonance ionization mass spectroscopy (RIMS) is a sensitive and isotope selective method and well suited for trace analysis of plutonium in the environment. After the chemical isolation of plutonium from soil, air filters or urine, e.g., it is electrolytically deposited as hydroxide on a tantalum backing and covered with a thin titanium layer. By heating such a sandwich filament in the RIMS-apparatus under vacuum an atomic beam of plutonium is produced. The atoms are ionized by a three-step resonant excitation using pulsed dye lasers, and the ions are mass-selectively detected with a time-of-flight (TOF) spectrometer and a multi channel plate detector. RIMS yields a low detection limit of …