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71.
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73.
The transverse field μSR-signal from μ+ implanted in a CeAs single crystal shows a splitting into two components, displaying a positive and a negative Knight shift,
respectively which both scale reasonably well with the magnetic bulk susceptibility above 10 K. The orientation dependence
of the frequency shifts, measured at 15 K, is fully accounted for by the demagnetization field, implying an isotropic Knight
shift, consistent with the μ+ residing at the only interstitial site of high (cubic) symmetry, i.e., at the position (1/4,1/4,1/4). The occurrence of a
split signal remains unexplained.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
74.
A. Amato C. Geibel F. N. Gygax R. H. Heffner E. Knetsch D. E. MacLaughlin C. Schank A. Schenck F. Steglich M. Weber 《Zeitschrift für Physik B Condensed Matter》1992,86(2):159-160
Positive-muon spin rotation (
+ SR) measurements have been carried out in the new heavy-fermion superconductors UM2Al3, M=Ni and Pd. In UNi2Al3 the observed
+ frequencies in zero applied field indicate commensurate antiferromagnetic (AF) ordering of U moments 0.1
B
/U atom. These moments coexist with superconductivity and have the highest values observed in an AF heavy-fermion superconductor. The absence of well-defined frequencies in zero-field
+ SR in the AF state of UPd2Al3 suggests symmetric
+ stopping sites. In this system
+ SR linewidths belowT
c
yield a preliminary value of 8000 Å for the London penetration depth. 相似文献
75.
J. S. Amato V. J. Grenda T. M. H. Liu E. J. J. Grabowski 《Journal of heterocyclic chemistry》1979,16(6):1153-1155
Reactions of 2-(4′-fluorophenyl)imidazole ( 1 ) and related compounds under various nitrating conditions are discussed. With 90% nitric acid in 20% oleum at ?10°, 1 affords 2-(4′fluorophenyl)-4(5)-nitroimidazole ( 2 ) in 80% yield. Reaction of 2 with the same reagents at 25° affords 2-(4′-fluoro-3′-nitrophenyl)-4(5)-nitroimidazole ( 4 ) in 90% yield, whereas with 90% nitric acid in acetic acid at 95°, 2 affords 4,5-dinitro-2-(4′-fluorophenyl)imidazole ( 5 ) in 80% yield. Reaction of 1 with 70% nitric acid in concentrated sulfuric acid at 25° affords 2-(4′-fluorophenyl)-5-hyroximinoimidazolin-4-one ( 6 ), which rearranges and hydrolyzes to 5-(4′-fluorophenyl)-1,2,4-oxadiazole-3-carboxylic acid. A discussion of these reactions is presented. 相似文献
76.
77.
78.
Raffaele Pastore Marco Caggioni Domenico Larobina Luigi Santamaria Amato Francesco Greco 《中国科学:物理学 力学 天文学(英文版)》2019,(10)
Concentrated suspensions of Brownian hard-spheres in water are an epitome for understanding the glassy dynamics of both soft materials and supercooled molecular liquids. From an experimental point of view, such systems are especially suited to perform particle tracking easily, and, therefore, are a benchmark for novel optical techniques, applicable when primary particles cannot be resolved. Differential variance analysis(DVA) is one such novel technique that simplifies significantly the characterization of structural relaxation processes of soft glassy materials, since it is directly applicable to digital image sequences of the sample. DVA succeeds in monitoring not only the average dynamics, but also its spatio-temporal fluctuations, known as dynamic heterogeneities. In this work, we study the dynamics of dense suspensions of Brownian beads in water, imaged through digital video-microscopy, by using both DVA and single-particle tracking. We focus on two commonly used signatures of dynamic heterogeneities: the dynamic susceptibility, χ_4, and the non-Gaussian parameter, α_2. By direct comparison of these two quantities,we are able to highlight similarities and differences. We do confirm that χ_4 and α_2 provide qualitatively similar information, but we find quantitative discrepancies in the scalings of characteristic time and length scale on approaching the glass transition. 相似文献
79.
F. Amato R. Ambrosino C. Cosentino G. De Tommasi 《Nonlinear Analysis: Hybrid Systems》2011,5(1):89-101
Finite-time stabilization of a special class of hybrid systems, namely impulsive dynamical linear systems (IDLS), is tackled in this paper. IDLS exhibit jumps in the state trajectory which can be either time-driven (time-dependent IDLS) or subordinate to specific state values (state-dependent IDLS). Sufficient conditions for finite-time stabilization of IDLS are provided. Such results require solving feasibility problems which involve Differential–Difference Linear Matrix Inequalities (D/DLMIs), which can be numerically solved in an efficient way, as illustrated by the proposed examples. 相似文献