Практико-ориентированная направленность подготовки студентов стоматологического факультета

МЕДИЦИНСКИЕ УЧЕБНЫЕ ЗАВЕДЕНИЯОБРАЗОВАНИЕ МЕДИЦИНСКОЕСТУДЕНТЫ МЕДИЦИНСКИХ УЧЕБНЫХ ЗАВЕДЕНИЙОБРАЗОВАНИЕ СТОМАТОЛОГИЧЕСКОЕПРАКТИКО-ОРИЕНТИРОВАННОЕ ОБРАЗОВАНИ

The gluon content of the η\eta and η′\eta^{\prime} mesons and the ηγ\eta\gamma, η′γ\eta^{\prime}\gamma electromagnetic transition form factors

We compute power-suppressed corrections to the \eta\gamma and \eta^{\prime}\gamma transition form factors Q^2F_{\eta(\eta^{\prime})\gamma}(Q^2) arising from the end point regions x \to 0,1 by employing the infrared-renormalon approach. The contribution to the form factors from the quark and gluon content of the \eta,\eta^{\prime} mesons is taken into account using for the \eta-\eta^{\prime} mixing the SU_f(3) singlet \eta_1 and octet \eta_8 basis. The theoretical predictions obtained this way are compared with the corresponding CLEO data and restrictions on the input parameters (Gegenbauer coefficients) B_2^q(\eta_1), B_2^g(\eta_1), and B_2^q(\eta_8) in the distribution amplitudes for the \eta_1,\eta_8 states with one nonasymptotic term are deduced. Comparison is made with the results from QCD perturbation theory.Comment: 25 pages, RevTeX4 used. 9 figures as EPS files. Text significantly changed to include variation of theoretical parameters. Figures modified. Corrected typo in equation (34) and trivial mistake in $\beta_1$-coefficient. References added. Conclusions unchange

Effects of cascade-induced dislocation structures on the long-term microstructural evolution in tungsten

In recent years, a number of systematic investigations of high-energy collision cascades in tungsten employing advanced defect analysis tools have shown that interstitial clusters can form complex non-planar dislocation structures. These structures are sessile in nature and may potentially have a strong impact on the long-term evolution of the radiation microstructure. To clarify this aspect, we selected several representative primary damage states of cascades debris and performed annealing simulations using molecular dynamics (MD). We found that immobile complexes of non-planar dislocation structures (CDS) evolve into glissile and planar shaped 1/2 loops with an activation energy of similar to 1.5 eV. The CDS objects were implemented in an object kinetic Monte Carlo (OKMC) model accounting for the event of transformation into 1-D migrating loops, following the MD data. OKMC was then used to investigate the impact of the transformation event (and the associated activation energy) on the evolution of the microstructure.Peer reviewe

The influence of carbon impurities on the formation of loops in tungsten irradiated with self-ions

The microstructure changes taking place in W under irradiation are governed by many factors, amongst which C impurities and their interactions with self-interstitial atoms (SIA). In this work, we specifically study this effect by conducting a dedicated 2-MeV self-ions irradiation experiment, at room temperature. Samples were irradiated up to 0.02, 0.15 and 1.2 dpa. Transmission electron microscopy (TEM) expectedly revealed a large density of SIA loops at all these doses. Surprisingly, however, the loop number density increased in a non-monotonous manner with the received dose. Performing chemical analysis with secondary ion spectroscopy measurements (SIMS), we find that our samples were likely contaminated by C injection during the irradiation. Employing an object kinetic Monte Carlo (OKMC) model for microstructure evolution, we demonstrate that the C injection is the likely factor explaining the evolution of loops number density. Our findings highlight the importance of the well-known issue of C injection during ion irradiation experiments, and demonstrate how OKMC models can help to rationalize this effect.Peer reviewe