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31.
Miller RI Kiefl RF Brewer JH Sonier JE Chakhalian J Dunsiger S Morris GD Price AN Bonn DA Hardy WH Liang R 《Physical review letters》2002,88(13):137002
Evidence for static alternating magnetic fields in the vortex cores of underdoped YBa2Cu3O6+x is reported. Muon spin rotation measurements of the internal magnetic field distribution of the vortex state of YBa2Cu3O6.50 in applied fields of H = 1 T and H = 4 T reveal a feature in the high-field tail of the field distribution which is not present in optimally doped YBa2Cu3O6.95 and which fits well to a model with static magnetic fields in the vortex cores. The magnitude of the fields is estimated to be 18(2) G and decreases above T = 10 K. We discuss possible origins of the additional vortex core magnetism within the context of existing theories. 相似文献
32.
Ronald C. Scherer Moderator Editor David W. Brewer Raymond Colton Lucille S. Rubin Bonnie N. Raphael Richard Miller Elizabeth Howell G. Paul Moore 《Journal of voice》1994,8(4):359-374
The integration of voice science, voice pathology, medicine, public speaking, acting, and singing has been central to evolution in all fields. The Voice Foundation Symposia have played a seminal and central role in fostering integration among disciplines. The result has been an improvement in the knowledge and practice in each field. And the future promises to be even more informative and exciting. 相似文献
33.
G. M. Marshall A. Adamczak J. M. Bailey J. L. Beveridge G. A. Beer J. H. Brewer V. M. Bystritsky M. P. Faifman B. M. Forster M. C. Fujiwara T. M. Huber R. Jacot-Guillarmod P. Kammel K. R. Kendall N. P. Kherani S. K. Kim P. E. Knowles A. R. Kunselman M. Maier V. E. Markushin V. S. Melezhik G. R. Mason F. Mulhauser A. Olin C. Petitjean T. A. Porcelli L. A. Schaller V. A. Stolupin J. Zmeskal 《Hyperfine Interactions》2001,138(1-4):203-211
Since the discovery that muonic deuterium at energies near a few eV could travel distances of the order of 1 mm in condensed
hydrogen, and in particular that muonic tritium and muonic deuterium could emerge from the surface of a solid hydrogen layer,
the advantages of solid targets have enabled the study of several processes important in muon catalyzed fusion. A review of
the results is presented, emphasizing the strengths and limitations of the use of solid hydrogen layer targets.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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36.
N. Nishida R.S. Hayano K. Nagamine T. Yamazaki J.H. Brewer D.M. Garner D.G. Fleming T. Takeuchi Y. Ishikawa 《Solid State Communications》1977,22(4):235-239
In recent positive-muon spin rotation experiment at TRIUMF on single crystal Fe, a clear temperature dependent change has been observed, for the first time, both in frequency and depolarization rates from 300 K down to 23 K. The μ+ depolarization was explained by the μ+ diffusion through inhomogeneous dipolar fields and the diffusion constant was found to obey an Arrhenius law (activation energy 17 meV) above 70 K but surprisingly deviated from this at lower temperatures, indicating quantum diffusion. We have also found that the μ+ hyperfine field has a temperature dependence slightly stronger than that of the magnetization. 相似文献
37.
A ring fragmentation and intramolecular azomethine ylide 1,3-dipolar cycloaddition sequence of reactions was successfully used in the preparation of a known (±)-cycloclavine precursor in good overall yield. Results of efforts to incorporate the tetrasubstituted cyclopropane ring present in cycloclavine are also discussed. 相似文献
38.
39.
E. J. Ansaldo J. Boyle Ch. Niedermayer G. D. Morris J. H. Brewer C. E. Stronach R. S. Cary 《Zeitschrift für Physik B Condensed Matter》1992,86(3):317-318
Three distinct electronic states were detected for positive muons (+) after implantation into a C60 powder sample. About 40% of the + remained in the bare (diamagnetic) state, essentially an interstitial charged point particle. The rest of the muons were found to thermalize predominantly in two muonium (Mu=+ e–) atomic species. A vacuum Mu state, with hyperfine coupling close to that of free Mu, most likely at the molecular center, and a muonic substituted radical, i.e. a hydrogen-like Mu addition to double bonds on the carbon rings. This opens up a rich subfield of fullerene spectroscopy using muons. 相似文献
40.
Jian Fang Evan M. Howard Prof. Dr. Matthias Brewer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12927-12931
Structurally complex diazo-containing scaffolds are formed by conjugate addition to vinyl diazonium salts. The electrophile, a little studied α-diazonium-α,β-unsaturated carbonyl compound, is formed at low temperature under mild conditions by treating β-hydroxy-α-diazo carbonyls with Sc(OTf)3. Conjugate addition occurs selectively at the 3-position of indole to give α-diazo-β-indole carbonyls, and enoxy silanes react to give 2-diazo-1,4-dicarbonyl products. These reactions result in the formation of tertiary and quaternary centers, and give products that would be otherwise difficult to form. Importantly, the diazo functional group is retained within the molecule for future manipulation. Treating an α-diazo ester indole addition product with Rh2(OAc)4 caused a rearrangement to occur to give a 2-(1H-indol-3-yl)-2-enoate. In the case of diazo ketone compounds, this shift occurred spontaneously on prolonged exposure to the Lewis acidic reaction conditions. 相似文献