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Energy-adjusted pseudopotentials for the actinides. Parameter sets and test calculations for thorium and thorium monoxide (1994)

Küchle, W. ; Dolg, M. ; Stoll, H. ; [et al.]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 100 (1994), S. 7535-7542

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ISSN: 1089-7690

Source: AIP Digital Archive

Topics: Physics , Chemistry and Pharmacology

Notes: We present nonrelativistic and quasirelativistic energy-adjusted pseudopotentials, the latter augmented by spin–orbit operators, as well as optimized (12s11p10d8f)/ [8s7p6d4f]-Gaussian-type orbitals (GTO) valence basis sets for the actinide elements actinium through lawrencium. Atomic excitation and ionization energies obtained by the use of these pseudopotentials and basis sets in self-consistent field (SCF) calculations differ by less than 0.2 eV from corresponding finite-difference all-electron results. Large-scale multiconfiguration self-consistent field (MCSCF), multireference configuration interaction (MRCI), and multireference averaged coupled-pair functional (MRACPF) calculations for thorium and thorium monoxide yield results in satisfactory agreement with available experimental data. Preliminary results from spin–orbit configuration interaction calculations for the low-lying electronic states of thorium monoxide are also reported.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.466847

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Myocardial perfusion measured by dual-isotope acquisition of81rubidium/81mkrypton: an experimental verification of the method (1994)

Stoll, H. -P. ; Bay, W. ; Vogel, W. ; [et al.]

Springer

Basic research in cardiology 89 (1994), S. 354-365

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ISSN: 1435-1803

Keywords: 81Rubidium/81mkrypton ; myocardial perfusion ; myocardial perfusion reserve ; isolated rabbit heart ; Langendorff preparation

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary Purpose The purpose of the study was to verify that the81Rubidium/81mkrypton (81Rb/81mKr) method allows the quantitative measurement of myocardial perfusion. Principle The potassium analogous cation81Rb is accumulated in the myocardium by the cell membrane-bound Na−K-ATPase. After accumulation an intracellular equilibrium establishes between81Rb and its radioactive daughter nuclide81mKr. The flow-sensitive method evaluates the disturbance of this equilibrium by perfusion which washes out the short-lived diffusable daughter nuclide81mKr while the mother nuclide81Rb remains cell-bound. Methods Isolated rabbit hearts were prepared in a modified Langendorff technique which allowed quantitative collection of the coronary sinus efflux. The myocardium was labeled with pure81Rb by bolus injection into the aortic cannula. Spectroscopic measurements of81Rb and81mKr gamma radiation were performed using a germanium detector. Perfusion was varied in the range between 0 and 4 ml/min/g. The activity ratio81Rb/81mKr was determined and compared with coronary sinus effusion. Results 81Rb/81mKr activity ratio was closely related (r=0.98) to perfusion as described by the predicted equation Rb/Kr=(F/2.96 P)+1. (Rb/Kr=activity ratio between81Rb and81mKr in the myocardium; F=myocardial perfusion (ml/min/g); P=partition coefficient (myocardium/perfusate) for Krypton gas.) The constant P was found to be 1.14±0.06 (mean±SEM). No saturation of this ratio at high flow rates was observed. Conclusion The activity ratio81Rb/81mKr is a valid quantitative measure for myocardial perfusion in isolated hearts. The main limitation of the method before application in man is the correction of the different gamma ray tissue absorption of both nuclides.