排序方式: 共有12条查询结果,搜索用时 31 毫秒
1.
Dr. Sigurd Øien-Ødegaard Dr. Calliope Bazioti Dr. Evgeniy A. Redekop Dr. Øystein Prytz Prof. Karl Petter Lillerud Prof. Unni Olsbye 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21581-21586
Herein, we report the discovery of a toroidal inorganic cluster of zirconium(IV) oxysulfate of unprecedented size with the formula Zr70(SO4)58(O/OH)146⋅x(H2O) (Zr70), which displays different packing of ring units and thus several polymorphic crystal structures. The ring measures over 3 nm across, has an inner cavity of 1 nm and displays a pseudo-10-fold rotational symmetry of Zr6 octahedra bridged by an additional Zr in the outer rim of the ring. Depending on the co-crystallizing species, the rings form various crystalline phases in which the torus units are connected in extended chain and network structures. One phase, in which the ring units are arranged in layers and form one-dimensional channels, displays high permanent porosity (BET surface area: 241 m2 g−1), and thus demonstrates a functional property for potential use in, for example, adsorption or heterogeneous catalysis. 相似文献
2.
Skutterudites, with rattler atoms introduced in voids in the crystal unit cell, are promising thermoelectric materials. We modify the binary skutterudite with atomic content Co(8)P(24) in the cubic crystal unit cell by adding La as rattlers in all available voids and replacing Co by Fe to maintain charge balance, resulting in La(2)Fe(8)P(24). The intention is to leave the electronic structure unaltered while decreasing the thermal conductivity due to the presence of the rattlers. We compare the electronic structure of these two compounds by studying the L-edges of P and of the transition elements Co and Fe using electron energy loss spectroscopy (EELS). Our studies of the transition metal white lines show that the 3d electron count is similar for Co and Fe in these compounds. As elemental Fe has one electron less than Co, this supports the notion that each La atom donates three electrons. The L-edges of P in these two skutterudites are quite similar, signalling only minor differences in electronic structure. This is in reasonable agreement with density functional theory (DFT) calculations, and with our multiple scattering FEFF calculations of the near edge structure. However, our experimental plasmon energies and dielectric functions deviate considerably from predictions based on DFT calculations. 相似文献
3.
K. Prytz 《The European Physical Journal C - Particles and Fields》2001,22(2):317-321
The notion of a pomeron structure function arises in a model of electromagnetic diffractive scattering based on Regge factorization.
Due to its small size we expect gluon recombination to occur significantly in the pomeron. The latest data from H1 (1999)
show a evolution in qualitative accordance with the GLR-MQ equations; these are the DGLAP (Altarelli–Parisi) equations corrected
for the effect of gluon recombination.
Received: 9 October 2000 / Revised version: 25 July 2001 / Published online: 5 November 2001 相似文献
4.
Max Stuhl und K. Prytz 《Fresenius' Journal of Analytical Chemistry》1891,30(1):321-323
Ohne Zusammenfassung 相似文献
5.
K. Prytz 《Fresenius' Journal of Analytical Chemistry》1897,36(1):503
Ohne Zusammenfassung 相似文献
6.
Selke W. Dickens P. Pring M. E. Spencer J. F. Thanheiser G. Bobtelsky M. Kaplan D. Heczko Th. Spindeck F. Sanfourche A. Hahn Fr. L. Clarke B. L. Wooten L. A. Compton K. G. Czaporowski L. Wierciński J. Prytz M. Holst G. Kahler H. de Eds Floyd Vosburgh W. C. Elmore K. L. Gane R. Ingold C. K. 《Analytical and bioanalytical chemistry》1932,89(7-8):283-292
Analytical and Bioanalytical Chemistry - 相似文献
7.
Peer Birch Bodil Gümoes Hanne Stavad Svend Prytz Eva Bjrkner Johan Sundberg 《Journal of voice》2002,16(1):61-71
The velopharyngeal opening (VPO) is analyzed in 17 professional operatic singers, 3 high sopranos, 3 sopranos, 2 mezzo-sopranos, 3 tenors, 2 baritones, 2 bass-baritones, and 2 basses singing the vowels [a, i, u] at middle degree of vocal loudness at different pitches throughout their pitch range. Three methods were used for detection of a VPO. One was nasofiberscopy, which revealed VPO of various shapes in several singers. Another method was recording nasal and oral airflow by means of a divided flow mask. These measurements showed a nasal DC airflow at least at some pitches in a majority of the singers. A third method was a comparison of the level of the fundamental in the nasal and oral airflow signals; this level difference was less than 15 dB in cases where a nasal DC airflow was observed. Values less than 15 dB were observed in some cases, thus suggesting the presence of a VPO. The tokens produced by the singers were assessed by an expert panel with respect to nasal quality of the vowel timbre; no correlation was found between rated nasal quality and the presence of a VPO. 相似文献
8.
A formalism for diffractive deep inelastic scattering is presented based on the concept of a pomeron structure function. Assuming the pomeron to be essentially a gluonic object with the small size indicated by its small interaction cross-sections, we show that the QCD evolution of its structure function exhibits large screening corrections due to gluon recombinations at small-χ. With a gluon-to-quark conversion appropriate at small-χ, diffractiveep cross-sections are obtained giving large enough statistics at HERA to distinguish between QCD evolution governed by the conventional Altarelli-Parisi equations and by the non-linear Gribov-Levin-Ryskin equation. 相似文献
9.
In a particular model of the pomeron, its gluon and quark distributions are subject to anti-shadowing, as described by a modified GLR equation recently derived. Inclusion of antishadowing cures the problem of momentum nonconservation previously existing in the GLR equation. A possible outcome of a measurement of the pomeron structure function at HERA is shown in case of DGLAP, GLR and modified GLR parton dynamics. 相似文献
10.
W. Selke P. Dickens M. E. Pring J. F. Spencer G. Thanheiser M. Bobtelsky D. Kaplan Th. Heczko F. Spindeck A. Sanfourche Fr. L. Hahn B. L. Clarke L. A. Wooten K. G. Compton L. Czaporowski J. Wierciski M. Prytz G. Holst H. Kahler Floyd de Eds W. C. Vosburgh K. L. Elmore R. Gane und C. K. Ingold 《Fresenius' Journal of Analytical Chemistry》1932,89(7-8):283-292
Ohne Zusammenfassung 相似文献