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101.
The pressure dependence of the electric field gradient (EFG) in the AgIn2 intermetallic compound was measured from zero up to 35 kbar using the time differential perturbed angular correlation technique
in111Cd. The unit cell volume and thec/a ratio variations with pressure were measured up to 80 kbar. The temperature dependence of the cell parameters was also measured,
in a range varying from 300 K up to 458 K. The relationship of these results showed that the contribution of the lattice thermal
expansion to the EFG variations is about 1/3, a small but not negligible part. The estimated EFG volumetric dependence is
at variance with the systematic results found in pure metals.
Work supported in part by FINEP and CNPq (Brasil). 相似文献
102.
S. M. Fries J. Crummenauer U. Gonser P. Schaaf C. L. Chien 《Hyperfine Interactions》1989,45(1-4):301-308
The Mössbauer study of the mixed magnetic dipole and electric quadrupole interaction in the paramagnetic state of amorphous Fe?Zr and Fe?Hf alloys is presented. Strong evidence for chemical short range order of the iron-pure alloys is found. The hyperfine parameters of the iron-rich alloys are marked by a complex applied field and temperature dependence, suggesting a not negligible spincorrelation well above Tc. 相似文献
103.
We calculate the production of high-energy photons from Compton scattering and annihilation of a quark jet passing through a quark gluon plasma produced in a relativistic heavy ion collision. The contributions are large and reflect the momentum distribution of the jets and the initial conditions of the plasma. 相似文献
104.
R. Brandelik W. Braunschweig H.-U. Martyn H.G. Sander D. Schmitz W. Sturm W. Wallraff D. Cords R. Felst R. Fries E. Gadermann H. Hultschig P. Joos W. Koch U. Kötz H. Krehbiel D. Kreinick S. Yamada 《Physics letters. [Part B]》1977,70(3):387-392
The semileptonic and leptonic decay modes of charmed hadrons produced in e+e? collisions above 4 GeV in the cm have been investigated by selecting events with a single electron plus at least two charged tracks. The electron momentum spectrum peaks near 0.5 GeV/c with few events above 0.7 GeV/c. The spectrum excludes large rates for the decays and , but is compatible with , or a mixture of both. The semileptonic branching ratio is obtained both by comparing the inclusive electron cross section with the total cross section attributable to charm, and by studying the fraction of events containing a second electron. The semileptonic charm branching ratios obtained are 0.11 ± 0.03 and 0.16 ± 0.06 respectively. A single event with three electrons and hadrons is found, consistent with the estimated background. The 90% confidence upper limit for σ(e+e? → 3e + hadrons) is 0.1 nb. 相似文献
105.
Suo Z Yang X Avci R Kellerman L Pascual DW Fries M Steele A 《Langmuir : the ACS journal of surfaces and colloids》2007,23(3):1365-1374
Most bacteria, planktonic and sessile, are encapsulated inside loosely bound extracellular polymeric substance (EPS) in their physiological environment. Imaging a bacterium with its capsule requires lengthy sample preparation to enhance the capsular contrast. In this study, Salmonella typhimurium was investigated using atomic force microscopy for a practical means of imaging an encapsulated bacterium in air. The investigation further aimed to determine the relation between the buffers used for preparing the bacterium and the preservation of the capsular material surrounding it. It was observed that rinsing bacteria with HEPES buffer could stabilize and promote capsule formation, while rinsing with PBS, Tris, or glycine removes most of the capsular EPS. For bacteria rinsed with HEPES and air-dried, the height images showed only the contour of the capsular material, while the phase and amplitude images presented the detailed structures of the bacterial surface, including the flagella encapsulated inside the capsular EPS. The encapsulation was attributed to the cross-linking of the acidic exopolysaccharides mediated by the piperazine moiety of HEPES through electrostatic attraction. This explanation is supported by encapsulated bacteria observed for samples rinsed with N,N'-bis(2-hydroxyethyl)-piperazine solution and by the presence of entrapped HEPES within the dry capsular EPS suggested by micro-Raman spectroscopy. 相似文献
106.
H.J. Behrend Ch. Chen H. Fenner J.H. Field V. Schr?der H. Sindt G. DAgostini W.-D. Apel S. Banerjee J. Bodenkamp D. Chrobaczek J. Engler G. Flügge D.C. Fries W. Fues K. Gamerdinger G. Hopp F. Pierre 《Physics letters. [Part B]》1982,114(5):378-382
From the two-photon exchange processes e+e? → e+e?η' (958) → e+e??0γ and e+e? → e+e?A2 (1310) → e+e?π+π?π0 observed using the CELLO detector at PETRA the radiative widths of the η' and A2 have been determined with the results: Γγγ(η') = 5.4 ± 1.0[stat.] ± 0.7[syst.] keV; Γγγ(A2) = 0.59 ± 0.14[stat.] ?0.08+0.31[syst.] keV. 相似文献
107.
M. Faierman R. J. Fries R. Mennicken M. Möller 《Integral Equations and Operator Theory》2000,38(1):9-27
We determine the essential spectrum of the linearized Navier-Stokes operator with physical boundary conditions. In contrast to other approaches we do not make use of pseudo-differential operators. We establish a direct proof using only some fundamental results for matrix operators.Supported in part by a grant from the NRF of South Africa and by the John Knopfmacher Centre for Applicable Analysis and Number Theory, University of the Witwatersrand, Johannesburg 相似文献
108.
109.
110.
Fries PH 《The Journal of chemical physics》2012,136(4):044504
We propose an easily applicable method for investigating the pair distribution function of a lanthanide Ln(3+) complex LnL (L = ligand) with respect to any solvent or solute molecule A carrying observable nuclear spins. Let r be the distance of Ln(3+) to the observed nuclear spin I. We derive a simple expression of the experimental value of the configurational average of 1/r(6) in terms of longitudinal paramagnetic relaxation (rate) enhancements (PREs) of the spin I measured on a standard high-resolution NMR spectrometer and due to well-chosen concentrations of LnL complexes in which Ln(3+) is a fast-relaxing paramagnetic lanthanide or the slowly-relaxing gadolinium Gd(3+). The derivation is justified in the general case of a molecule A which is by turns in a bound state where it follows the complex and a free state where it moves independently. It rests on the expression of the underlying PRE theory in terms of the angle-dependent pair distribution function of LnL and A. The simplifications of this theory in the high-field regime and under the condition of fast exchange between bound and free states are carefully discussed. We also show that original information on the angle dependence of the molecular pair distribution function can be gained from the measured paramagnetic dipolar shifts induced by complexed fast-relaxing Ln(3+) ions. The method is illustrated by the case study of the anionic Lnttha(3-) = [Ln(3+)(ttha)](3-) (ttha(6-) = triethylene tetraamine hexacetate) complex interacting with the biologically important tripeptide Arg-Gly-Asp (RGD) which carries peripheral ionic groups. The usefulness of an auxiliary reference outer sphere probe solute is emphasized. 相似文献