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31.
A. Veiga N. Martínez P. Mendoza Zélis G. A. Pasquevich F. H. Sánchez 《Hyperfine Interactions》2006,167(1-3):905-909
A prototype of a programmable constant-velocity scaler is presented. This instrument allows the acquisition of partial Mössbauer spectra in selected energy regions using standard drivers and transducers. It can be fully operated by a remote application, thus data acquisition can be automated. The instrument consists of a programmable counter and a constant-velocity reference. The reference waveform generator is amplitude modulated with 13-bit resolution, and is programmable in a wide range of frequencies and waveforms in order to optimize the performance of the transducer. The counter is compatible with most standard SCA, and is configured as a rate-meter that provides counts per selectable time slice at the programmed velocity. As a demonstration of the instrument applications, a partial Mössbauer spectrum of a natural iron foil was taken. Only positive energies were studied in 512 channels, accumulating 20 s per channel. A line width of 0.20 mm/s was achieved, performing with an efficiency of 80%. 相似文献
32.
E. K. Sadykov V. V. Arinin G. I. Petrov A. V. Pyataev F. G. Vagizov O. A. Kocharovskaya 《Hyperfine Interactions》2006,167(1-3):893-896
The role of quantum interference (QI) in spectra of the resonant Mössbauer scattering is investigated. As a mechanism ensuring the QI conditions, the radio-frequency (RF) mixing of the spin sublevels of the excited nuclear state is considered. It is shown that QI leads to a significant intensity redistribution of the elastic and Raman scattering. 相似文献
33.
The 57Fe Mössbauer technique has been used to investigate the effect of zinc oxide substitution in (25???x)MnO–xZnO–15Fe2O3–60B2O3 glass system (x?=?0, 5, 10, 15 and 20 mol% of ZnO ). Mössbauer absorption spectra for all the samples recorded at room temperature suggest the existence of the two paramagnetic quadrupole doublets. The observed variations in hyperfine parameters have been explained on the basis of cations distribution and exchange interaction at the lattice sites and it is concluded that B–B interaction increases while the metal–metal interaction decreases due to replacement of manganese oxide by zinc oxide. These results suggest that the present glass system exhibits a paramagnetic behaviour that changes towards the weak paramagnetic when manganese oxide was replaced with zinc oxide. 相似文献
34.
The decision problem for positively quantified formulae in the theory of linearly ordered Heyting algebras is known, as a special case of work of Kreisel, to be solvable; a simple solution is here presented, inspired by related ideas in Gödel-Dummett logic. 相似文献
35.
The stress tensor of a massless scalar field satisfying a mixed boundary condition in a (1 + 1)-dimensional Reissner- Nordstrom black hole background is calculated by using Wald's axiom. We find that Dirichlet stress tensor and Neumann stress tensor can be deduced by changing the coefficients of the stress tensor calculated under a mixed boundary condition. The stress tensors satisfying Dirichlet and Neumann boundary conditions are discussed. In addition, we also find that the stress tensor in conformal flat spacetime background differs from that in flat spacetime only by a constant. 相似文献
36.
Summary At first, a necessary and sufficient condition for a K?hler-Norden manifold to be holomorphic Einstein is found. Next, it
is shown that the so-called (real) generalized Einstein conditions for K?hler-Norden manifolds are not essential since the
scalarcurvature of such manifolds is constant. In this context, we study generalized holomorphic Einstein conditions. Using
the one-to-one correspondence between K?hler-Norden structures and holomorphic Riemannian metrics, we establish necessary
and sufficient conditions for K?hler-Norden manifolds to satisfy the generalized holomorphic Einstein conditions. And a class
of new examples of such manifolds is presented. Finally, in virtue of the obtained results, we mention that Theorems 1 and
2 of H. Kim and J. Kim [10] are not true in general. 相似文献
37.
I. Ortalli G. Pedrazzi K. Jiang X. Zhang C. Carlo-Stella V. Rizzoli 《Il Nuovo Cimento D》1992,14(4):351-358
Summary A new approach to cancer treatment using low-energy gamma-rays is discussed. Cultures of bone marrow mononuclear cells collected
from normal donors and patients with chronic myelogenous leukaemia have been studied after the addition of hematin, at different
concentrations, and irradiation by a M?ssbauer gamma-ray source. Growth stimulation has been observed when hematin is added
to normal bone marrow cultures, while growth inhibition is observed when hematin is added to leukaemic cultures. The effect
becomes then more pronounced when hematin is used in combination with M?ssbauer gamma-rays. 相似文献
38.
The Randi? index R(G) of a (chemical) graph G is also called connectivity index. Hansen and Mélot [Variable neighborhood search for extremal graphs 6: analyzing bounds for the connectivity index, J. Chem. Inf. Comput. Sci. 43 (2003) 1-14] in their paper, characterized the chemical trees of given order and number of pendent vertices which have the minimum and maximum Randi? index, respectively. In this note, we point out the mistakes in the proofs of their results Theorems 8 and 10, while we still believe that the two theorems are true, and then we give their corrected proofs. 相似文献
39.
H. P. Gunnlaugsson K. Bharuth-Ram M. Dietrich M. Fanciulli H. O. U. Fynbo G. Weyer 《Hyperfine Interactions》2006,169(1-3):1315-1318
We report on the detection of Fe i –B pairs in heavily B doped silicon using 57Fe emission Mössbauer spectroscopy following implantation of radioactive 57Mn+ parent ions (T 1/2?=?1.5 min) at elevated temperatures >?850 K. The Fe i –B pairs are formed upon the dissociation of Fe i –V pairs during the lifetime of the Mössbauer state (T 1/2?=?100 ns). The resulting free interstitial Fei diffuses over sufficiently large distances during the lifetime of the Mössbauer state to encounter a substitutional B impurity atom, forming Fe i –B pairs, which are stable up to ~1,050 K on that time scale. 相似文献
40.
Mössbauer spectroscopy was used to investigate the influence of dissolved hydrogen on the interatomic bonds in austenitic steels. It was carried out to prove the decohesion mechanism of hydrogen embrittlement (HE). It is shown that hydrogen increases Debye temperature, i.e., the interatomic bonds in hydrogenated austenitic steel becomes stronger. 相似文献