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21.
Generalized seniority is shown to provide a useful variational formalism for alike-nucleon systems even in the presence of strong shell effects. 相似文献
22.
We suggest that a new coupling scheme, based on the O(6) boson symmetry, may be useful in describing the spectra of odd-A nuclei towards the end of major shells. We describe the main properties of this scheme and show one example of it. 相似文献
23.
J. Jolie P. van Isacker K. Heyde J. Moreau G. van Landeghem M. Waroquier O. Scholten 《Nuclear Physics A》1985,438(1):15-28
We present a multilevel calculation within the framework of the interacting boson-fermion model (IBFM-1) of the odd-mass 101–109Rh isotopes. We calculate both positive- and negative-parity states of the same hamiltonian, starting from the , , , and single-particle orbitals. We discuss energy spectra, electromagnetic E2 transition rates and one-nucleon transfer properties. We also discuss the influence of the orbital on the one-nucleon transfer properties. The results of the calculation for the negative-parity states are compared with the results of the ) supersymmetry scheme of the interacting boson model. 相似文献
24.
Bonnot C Chambron JC Espinosa E Bernauer K Scholten U Graff R 《The Journal of organic chemistry》2008,73(20):7871-7881
The protonation of a sterically crowded [N2S6] macropentacycle (1) with 1 equiv of CF3SO3H in CDCl3 is slow and gives the singly (oo(+) [1 x H](+)) and doubly (o(+)o(+) [1 x 2H](2+)) protonated forms as kinetic products, the i(+)o form of [1 x H](+) being the thermodynamic product. i(+)o [1 x H](+) is C3 helically chiral in the solid state and in solution. The barrier to racemization (DeltaG(double dagger)) of the [1 x H](+) propeller is >71 kJ mol(-1). The ammonium proton is encapsulated in the tetrahedral coordination sphere provided by the endo (i) nitrogen bridgehead atom and the three proximal thioether sulfurs, which makes [1 x H](+) a proton complex. Use of the optically active acid (R)-(-)- or (S)-(+)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (BNPH) in chloroform allowed us to induce a significant diastereomeric excess (24% de), which produced a detectable ICD. The de was decreased in acetone-d6 (10%), suggesting that the sense of chirality of [1 x H](+) is controlled by ion-pair interactions. Detailed NMR studies allowed us to locate the chiral anion on the endo side of [1 x H](+), in the cavity lined by endo t-Bu groups, and to establish that the rate of anion exchange in [1 x H][(S,R)-(+/-)-BNP] was higher than the rate of propeller inversion of [1 x H](+). 相似文献
25.
The self-consistent-charge density functional tight binding (SCC-DFTB) method is compared with other semiempirical methods (MNDO, AM1, PM3, OM1, OM2, OM3). Despite the differences in the underlying philosophy and derivation, these methods share many common features. Systematic evaluations of their performance are reported for standard test sets that are in common use. The overall accuracy of SCC-DFTB and the other methods is in the same range, with the overall tendency AM1相似文献
26.
CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
27.
S. A. Kandil B. Scholten K. F. Hassan H. A. Hanafi S. M. Qaim 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(3):823-832
The radiochemical separation of 88Y from proton irradiated natSrCO3 and alpha-particle irradiated natRbCl, of 86Y from proton irradiated 86SrCO3, and of 87Y from alpha-particle irradiated natRbCl were studied at no-carrier-added levels by two techniques, namely, ion-exchange chromatography using Dowex 50W-X8 and
Dowex 21K resins, and solvent extraction using HDEHP. Out of all those methods, the ion-exchange chromatography using Dowex
50W-X8 (cation-exchanger) was found to be the best: the separation yield was high, the chemical impurity in the separated
radioyttrium (inactive Sr or Rb) was low (0.5 μg) and the final product was obtained in the form of citrate. The optimized
separation method using Dowex 50W-X8 was applied in practical production of 86Y and 88Y via proton irradiations of 86SrCO3 and natSrCO3, respectively, at 16 MeV as well as of 87Y and 88Y via α-particle irradiation of natRbCl at 26 MeV. The tangible experimental yields of 86Y and 87Y amounted to 150 and 5.7 MBq/μA·h, respectively. The yields of 88Y obtained were 0.06 MBq/μA·h and 1 MBq/μA·h for alpha-particle and proton irradiations, respectively. Each yield value corresponds
to more than 70% of the respective theoretical value. 相似文献
28.
Putkunz CT D'Alfonso AJ Morgan AJ Weyland M Dwyer C Bourgeois L Etheridge J Roberts A Scholten RE Nugent KA Allen LJ 《Physical review letters》2012,108(7):073901
Ptychographic coherent diffractive imaging (CDI) has been extensively applied using both x rays and electrons. The extension to atomic resolution has been elusive. This Letter demonstrates ptychographic electron diffractive imaging at atomic resolution, permitting identification of structure in a boron nitride helical cone at a resolution of order 1 ?, beyond that of comparative Z-contrast images. A scanning transmission electron microscope is used to create a diverging illumination in a defocused Fresnel CDI geometry, providing a robust strategy leading to a unique solution. 相似文献
29.
I. V. Ajinenko H. Białkowska H. Böttcher F. Botterweck F. Crijns A. De Roeck E. A. De Wolf K. Dziunikovska A. M. F. Endler P. F. Ermolov Z. C. Garutchava Y. A. Golubkov N. G. Grigoryan G. R. Gulkanyan P. van Hal T. Haupt J. K. Karamyan Z. A. Kirakosyan D. Kisielewska W. Kittel S. S. Megrabyan F. Meijers A. B. Michałowska K. Olkiewicz L. P. Petrovikh A. M. Rybin H. Saarikko L. Scholten E. K. Shabalina F. Verbeure R. Wischnewski S. A. Zotkin 《Zeitschrift fur Physik C Particles and Fields》1991,49(3):367-374
Collective characteristics are studied of hadrons produced in beam fragmentation of non-single-diffractive π+ p-interactions at 250 GeV/c. An attempt is made to obtain experimental information on the properties of leading cluster production and fragmentation. On average, the leading cluster carries 0.8±0.1 of the incident momentum, so that the mean value of the inelasticity coefficient of 〈k〉=0.2±0.1 is significantly smaller than that deduced from leading single hadron spectra. The momentum transfer distribution shows that nonsingle-diffractive processes are less peripheral than diffraction dissociation. The analysis of thrust and sphericity shows jet-like structure of pion fragmentation, that of the charge flow an average forward charge of 〈Q f 〉=0.45±0.04, in agreement with the average charge of the beam valence quarks. Our data are compared to diffraction dissociation and to the Fritiof model. 相似文献
30.