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104.
Isospin asymmetry in the pseudospin dynamical symmetry 总被引:1,自引:0,他引:1
Alberto P Fiolhais M Malheiro M Delfino A Chiapparini M 《Physical review letters》2001,86(22):5015-5018
Pseudospin symmetry in nuclei is investigated considering the Dirac equation with a Lorentz structured Woods-Saxon potential. The isospin correlation of the energy splittings of pseudospin partners with the nuclear potential parameters is studied. We show that, in an isotopic chain, the pseudospin symmetry is better realized for neutrons than for protons. This behavior comes from balance effects among the central nuclear potential parameters. In general, we found an isospin asymmetry of the nuclear pseudospin interaction, opposed to the nuclear spin-orbit interaction which is quasi-isospin symmetric. 相似文献
105.
Anna Maria Cardinale Daniele Macciò Stefano Delfino Adriana Saccone 《Journal of Thermal Analysis and Calorimetry》2011,103(1):103-109
The isothermal section of the Nd–Al–Si ternary system at 500 °C has been investigated using differential thermal analysis,
X-ray diffraction analysis, scanning electron microscopy and electron micro-probe analysis. Four ternary intermetallic compounds
were confirmed: NdAl2Si2 (τ1), hP5-CaLa2O2 structure type, Nd2Al3Si (τ2), hP3-AlB2 structure type, NdAl1−x
Si1+x
, 0.25 ≤ x ≤ 0.3 (τ3), tI12-αThSi2 structure type and Nd2Al1−x
Si1+x
, 0 ≤ x ≤ 0.2, (τ5), oS8-CrB structure type. A new ternary intermetallic phase (τ4) was found: Nd4Al3Si3, orthorhombic oS20, isotypic with Pr4Al3Ge3. 相似文献
106.
Delfino I Manzoni C Sato K Dennison C Cerullo G Cannistraro S 《The journal of physical chemistry. B》2006,110(34):17252-17259
We have applied femtosecond pump-probe spectroscopy to investigate the excited-state dynamics of umecyanin from horseradish roots, by exciting its 600-nm ligand-to-metal charge-transfer band with a 15-fs pulse and probing over a broad range in the visible region. The decay of the pump-induced ground-state bleaching is modulated by clearly visible oscillations and occurs exponentially with a time constant depending on the observed spectral component of the transmission difference signal, ranging from 270 fs up to 700 fs. The slower decaying process characterizes the spectral component corresponding to the metal-to-ligand charge-transfer transition. The excited-state decay rate is significantly lower than in other blue copper proteins, probably because of the larger energy gap between ligand- and metal-based orbitals in umecyanin. Wavelength dependence of the recovery times could be due to either the excitation of several transitions or the occurrence of intramolecular vibrational relaxation within the excited state. We also find evidence of a hot ground-state absorption, at 700 nm, persisting for several picoseconds. The vibrational coherence induced by the ultrashort pump pulse allows vibrational activity to be observed, mainly in the ground state, as expected in a system with fast excited-state decay. However, we find evidence of a rapidly damped oscillation, which we assign to the excited state. Finally, the Fourier transform of the oscillatory component of the signal presents additional bands in the low-frequency region which are assigned to collective motions of the protein. 相似文献
107.
Carina Sinclér Delfino Michel Nicolau Youssef Fábio Barbosa De Souza Rodivan Braz Míriam Lacalle Turbino 《Optik》2012,123(3):263-267
The objective of this study was to compare the microhardness of two resin composites (microhybrid and nanoparticles). Light activation was performed with argon ion laser 1.56 J (L) and halogen light 2.6 J (H) was used as control. Measurements were taken on the irradiated surfaces and those opposite them, at thicknesses of 1, 2 and 3 mm. To evaluate the quality of polymerization, the percentages of maximum hardness were calculated (PMH). For statistical analysis the ANOVA and Tukey tests were used (p ≤ 0.05). To microhybrid was shown that the hardness with laser was inferior to the hardness achieved with halogen light, for both the 1 mm and 2 mm. The nanoparticles polymerized with laser, presented lower hardness even on the irradiated surface, than the same surface light activated with halogen light. The microhybrid attained a minimum PMH of 80% up to the thickness of 2 mm with halogen light, and with laser, only up to 1 mm. The nanoparticles attained a minimum PMH of 80% up to 3 mm thickness with halogen light and with laser this minimum was not obtained at any thickness. Based on these results, it could be concluded that light activation with argon ion laser is contra-indicated for the studied nanoparticles. 相似文献