It is shown that the bending of FCN and FNC molecules adsorbed on Si (100) - (2 × 1) surface, is due to the Renner-Teller effect induced by the orbital charge transfers by adsorption. From ab initio calculations of free FCN and FNC and the molecules adsorbed on the model Si9H12 cluster, the orbital charge transfers to and from the molecules were calculated, the vibronic coupling constants were estimated, and the curvature K of the adiabatic potentials for the bending coordinate of adsorbed molecules was evaluated. Calculations show that for both side-on adsorbed species, as well as for end-on adsorbed FNC molecule K<0 that leads to their bending. For the end-on adsorbed FCN K>0, and this molecule remains linear
Strontium aluminate (SrAl2O4) and the indium aluminate (SrIn2O4) spinels have been proven to be efficient host materials, which offer the possibility of generating broadband emission after doping with rare earth trivalent ions. The present work is devoted to the calculation of the crystal field parameters and the energy levels of the trivalent europium doped in SrAl2O4 and SrIn2O4 spinels, using the superposition model of the crystal field. Using the intrinsic parameters for Eu3+-O2− bonds, and the geometry structure of the each crystal, we modeled the CFPs and simulated the low-lying energy levels schemes. The obtained results are compared with the experimental data and discussed.
Zinc aluminate (ZnAl2O4) doped with rare earth metal ions has been investigated most frequently because of the unique luminescent properties resulting from its stability and high emission quantum yields. The present work is devoted to calculate the Judd-Ofelt parameters (Ω2, Ω4 and Ω6) of the trivalent europium doped in ZnAl2O4 spinel, the quality factor (Q) and the branching ratio (β).
The paper presents the experimental installation for the production, in argon plasma, of cavitational iron microparticles (pore microspheres, microtubes and octopus-shaped microparticles). Experimental results are presented and discussed and it is shown that absorbant particles with a minimum iron content are obtained by the plasma procedures
It is shown that the isometry group of the de Sitter spacetime includes two different three-dimensional Abelian subgroups which transform between themselves through a discrete isometry corresponding to the time reversal in the five-dimensional Minkowski spacetime embedding the de Sitter one. The eigenfunctions of the generators of these Abelian subgroups form two different sets of quantum modes correlated by the mentioned isometry.
Single crystals of Y1−xRxCa4O(BO3)3 (R = Sc or Lu) of good quality have been grown from the melt by the Czochralski pulling method. The chemical compositions of the grown crystals were determined. Type-I noncritical phase matching (NCPM) wavelengths for second harmonic generation (SHG) in Y1−xRxCa4O(BO3)3 grown crystals were also determined.
The aim of present paper is to report the results on the modeling of the crystal field and spin-Hamiltonian parameters of Cr2+ doped in II-VI host matrix ZnS and simulate the energy levels scheme of such system taken into account the fine interactions entered in the Hamiltonian of the system. All considered types of such interaction are expected to give information on the new peculiarities of the absorption and emission bands, as well as of non-radiative transitions between the electronic states of impurity ions. The obtained results were disscused, compared with similar obtained results in literature and with experimental data.
This study presents the effects induced by X-rays, medium doses (20-70 Gy), over the meristematic tissues of three cereal species: one of barley and two of wheat. The cytogenetic investigation was based on the response of young seedlings during their very early ontogenetic stages to the ionizing radiation exposure. The study was focused on the identification and counting of the chromosomal aberrations for various doses compared to the control samples. Qualitative evaluation revealed: interchromatidian bridges, expulsed chromosomes or chromosome fragments, and complex aberrations (combination of the already mentioned ones). The different behavior of these three species was discussed over the mitotic index, the number of abnormal ana-telophases and over the percentages of the mitosis phases. In each case, the mitotic index was increased in comparison with the control, and also the number of aberrations was found increased; however no evident mathematical correlations with applied doses could be established.
An arthritic knee affects the patient’s life by causing pain and limiting movement. If the cartilage and the bone surfaces are severely affected, the natural joint is replaced with an artificial joint. The procedure is called total knee arthroplasty (TKA). Lately, the numbers of implanted total knee prostheses grow steadily. An important factor in TKA is the perfect alignment of the total knee prosthesis (TKP) components. Component misalignment can lead to the prosthesis loss by producing wear particles. The paper proposes a study on mechanical behaviors of a TKP based on numerical analysis, using ANSYS software. The numerical analysis is based on both the normal and the changed angle of the components alignment.
Determining the center of pressure trajectories, as an indicator of postural stability or lumbar pathology, has been a challenging issue for researchers during the last decades. The paper advances an investigational method in order to determine a correlation between lumbar spine movements and feet center of pressure distribution. Five young healthy volunteers were simultaneously tested using an ultrasound based motion analyzing system and a force platform, while performing imposed tasks. Results showed specific patterns described by the center of pressure trajectories and a good coordination of angular amplitudes during lumbar spine movement.