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151.
Lav Tandon Kevin Kuhn Patrick Martinez Joseph Banar Laurie Walker Terry Hahn David Beddingfield Donivan Porterfield Steven Myers Stephen LaMont Daniel Schwartz David Gallimore Scott Garner Khalil Spencer Lisa Townsend Heather Volz Russ Gritzo Rodney McCabe Ramiro Pereyra Dominic Peterson Mark Scott Christy Ruggiero Diana Decker Amy Wong 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):573-579
This paper presents results from the examination of a number of archived neutron-irradiated uranium targets used for past plutonium production testing. Three of these targets were destructively characterized using Los Alamos National Laboratory actinide analytical chemistry capabilities. A validated conduct-of-operations protocol was followed for this characterization effort. Chemical analyses included measurements for radionuclides, uranium assay, uranium isotopic abundances, trace actinides, trace metals, and non-metals. Material scientists also examined materials for morphological and microstructural properties and individual particles were examined for trace impurities. After characterization of the targets was completed, a reactor modeling effort was undertaken to corroborate target details in historical records. Time since irradiation calculations utilized both activation and fission products. The described examination of uranium targets has a tremendous impact from a safeguards verification and nuclear forensics perspective. 相似文献
152.
153.
J.H. McCabe 《Journal of Computational and Applied Mathematics》1981,7(4):271-275
A set of rhombus rules is given for generating the coefficients of the Perron fractions whose convergents form sawtooth sequences in the Padé table of a normal series. The coefficients of the Perron fractions for the reciprocal series are also derived, without finding the reciprocal series, and hence the Padé table for the series is obtained. 相似文献
154.
155.
P. M. McCabe J. A. Leach D. J. Needham 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2005,8(3):210-217
In this note, we consider a class of scalar, non-linear, singular (in the sense that the reaction terms in the equation are not Lipschitz continuous) reaction-diffusion equations with positive initial data being of (a) O(x–) or (b) O(x–e– x) at large x (dimensionless distance), where , > 0 and are constants. We establish, by developing the small–t (dimensionless time) asymptotic structure of the solution, that the support of the solution becomes finite in infinitesimal time in both cases (a) and (b) above. The asymptotic form for the location of the edge of the support as t 0 is given in both cases. 相似文献
156.
Srinivasan SG Liao XZ Baskes MI McCabe RJ Zhao YH Zhu YT 《Physical review letters》2005,94(12):125502
Atomistic simulations, confirmed by electron microscopy, show that dislocations in aluminum can have compact or dissociated cores. The calculated minimum stress (sigma(P)) required to move an edge dislocation is approximately 20 times smaller for dissociated than for equivalent compact dislocations. This contradicts the well accepted generalized stacking fault energy paradigm that predicts similar sigma(P) values for both configurations. Additionally, Frank's rule and the Schmid law are also violated because dislocation core energies become important. These results may help settle a 50-year-old puzzle regarding the magnitude of sigma(P) in face-centered-cubic metals, and provide new insights into the deformation of ultra-fine-grained metals. 相似文献
157.
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159.
The fluorescein conjugate, FITC-APEC (2-[2-[4-[2-[2-[1,3-dihydro-1,1-bis(4-hydroxyphenyl)-3-oxo-5-isobenzofuranthioureidyl]ethylaminocarbonyl]ethyl] phenyl]ethylamino]-5-N-ethylcarboxamidoadenosine), is a novel ligand derived from a series of functionalized congeners that act as selective A2a-adenosine receptor agonists. The binding of FITC-APEC to bovine striatal A2a-adenosine receptors measured by fluorescence techniques was saturable and of a high affinity, with aB
max of 2.3±0.3 pmol/mg protein andK
D of 57±2 nM. TheK
D value estimated by fluorescence was consistent with theK
i (11±0.3 nM) obtained by competition studies with [3H]CGS 21680. Additionally, theB
max value found by FITC-APEC measurement was in agreement withB
max values obtained using radioligand binding. FITC-APEC exhibited rapid and reversible binding to bovine striatum. The potencies of chemically diverse A2a-adenosine receptor ligands estimated by inhibition of FITC-APEC binding were in good agreement with their potencies determined using radioligand binding techniques (r=0.97,P=0.0003). FITC-APEC binding was not altered by purine derivatives that do not recognize A2a-adenosine receptors. These findings demonstrate that the novel fluorescent ligand FITC-APEC can be used in the quantitative characterization of ligand binding to A2a-adenosine receptors. 相似文献
160.
Carver FJ Hunter CA Livingstone DJ McCabe JF Seward EM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(13):2848-2859
Chemical double mutant cycles have been used to measure the magnitude of edge-to-face aromatic interactions in hydrogen-bonded zipper complexes as a function of substituents on both aromatic rings. The interaction energies vary depending on the combination of substituents from +1.0 kJ mol-1 (repulsive), to -4.9 kJ mol-1 (attractive). The results correlate with the Hammett substituent constants which indicates that electrostatic interactions are responsible for the observed differences in interaction energy. The experiments can be rationalised based on local electrostatic interactions between the protons on the edge ring and the pi-electron density on the face ring as well as global electrostatic interactions between the overall dipoles on the two aromatic groups. 相似文献