Search results for " Methods"
showing 10 items of 4102 documents
The Coordination of Uranyl in Water: A Combined Quantum Chemical and Molecular Simulation Study
2005
The coordination environment of uranyl in water has been studied using a combined quantum mechanical and molecular dynamics approach. Multiconfigurational wave function calculations have been performed to generate pair potentials between uranyl and water. The quantum chemically determined energies have been used to fit parameters in a polarizable force field with an added charge transfer term. Molecular dynamics simulations have been performed for the uranyl ion and up to 400 water molecules. The results show a uranyl ion with five water molecules coordinated in the equatorial plane. The U-O(H(2)O) distance is 2.40 A, which is close to the experimental estimates. A second coordination shell…
Crystal structure of sinhalite MgAlBO4 under high pressure
2015
We report on high-pressure angle-dispersive X-ray diffraction data up to 27 GPa for natural MgAlBO4 sinhalite mineral and ab initio total energy calculations. The experimental bulk modulus of sinhalite is B-0 = 171(3) GPa with a first-pressure derivative of B-0' = 4.2(3). A comparison with other olivine-type compounds shows that the value for B0 is 27% larger than that of Mg2SiO4 forsterite and 29% smaller than that of Al2BeO4 chrysoberyl. These differences are interpreted, on the basis of our ab initio calculations, in terms of the relative incompressibility of Al-O bonds in AlO6 octahedra (with a calculated bulk modulus of 250(1) GPa) as compared to Mg-O bonds in MgO6 octahedra (with a ca…
Impact of monitoring on detection of arrhythmia recurrences in the ESC-EHRA EORP atrial fibrillation ablation long-term registry
2019
Abstract Aims Monitoring of patients after ablation had wide variations in the ESC-EHRA atrial fibrillation ablation long-term (AFA-LT) registry. We aimed to compare four different monitoring strategies after catheter AF ablation. Methods and results The ESC-EHRA AFA-LT registry included 3593 patients who underwent ablation. Arrhythmia monitoring during follow-up was performed by 12-lead electrocardiogram (ECG), Holter ECG, trans-telephonic ECG monitoring (TTMON), or an implanted cardiac monitoring (ICM) system. Patients were selected to a given monitoring group according to the most extensive ECG tool used in each of them. Comparison of the probability of freedom from recurrences was perfo…
Progetti di lessicografia onomastica dell’Atlante Linguistico della Sicilia
2022
L’Atlante Linguistico della Sicilia ha adottato, già una decina di anni fa, lo strumento del dizionario-atlante. Quando si è cominciato ad indagare il ricco universo onomastico, se ne è valutata la spendibilità anche su tre diversi corpora orali: uno relativo alle forme popolari del patrimonio toponomastico (DAToS, Dizionario-atlante toponomastico della Sicilia), uno riguardante l’inventario plurale dei soprannomi etnici (DASES, Dizionario-atlante dei soprannomi etnici in Sicilia), l’ultimo afferente al patrimonio antroponomastico popolare, individuale e familiare (DASS, Dizionario-atlante dei soprannomi di/in Sicilia). Il contributo fornisce lo stato dell’arte dei tre progetti e ne descriv…
DISTRIBUTION OF CARBON STARS IN THE GALAXY
2018
A search for new faint carbon (C) stars in the Polar region δ > 55o has been accomplished by obtaining objective prism spectra in the near infrared 550 -- 900 nm on images of CCD camera of Baldone Schmidt telescope of Astrophysical observatory. The positions of stars having color indices (J – K) > 1.3 mag in Two Micron All Sky Infrared Survey (2MASS) were selected to pick out suspicious carbon stars.Our survey is limited in brightness by J < 10 mag. 24 new carbon stars were found and their characteristics obtained. The correlative relation between Teff and spectral gradient [757 – 685] was confirmed. Such characteristics as Teff, distance from the Sun, absolute Mk were obtained…
Theoretical Study of the Electronic Excited States of Tetracyanoethylene and Its Radical Anion
2005
The low-lying electronic states of tetracyanoethylene (TCNE) and its radical anion were studied using multiconfigurational second-order perturbation theory (CASPT2) and extended atomic natural orbital (ANO) basis sets. The results obtained yield a full interpretation of the electronic absorption spectra, explain the spectral changes undergone upon reduction, give support to the occurrence of a bound excited state for the anionic species, and provide valuable information for the rationalization of the experimental data obtained with electron transmission spectroscopy.
Probing NiO nanocrystals by EXAFS spectroscopy
2010
Abstract The structure relaxation in nanocrystalline NiO (nano-NiO, 13 nm crystallite size) has been studied by X-ray absorption spectroscopy at the Ni K-edge at 300 K. Conventional single-scattering analysis of the EXAFS signals from the first two coordination shells showed a lattice volume expansion by about 1% and a contraction of the Ni–O bonds by about 0.5% in nano-NiO compared to microcrystalline NiO. A more sophisticated approach, based on a combination of classical molecular dynamics and ab initio multiple-scattering EXAFS theory, allowed us to interpret both static relaxation and lattice dynamics in nano-NiO.
On the Low-Lying Excited States ofsym-Triazine-Based Herbicides
2005
We report a joint computational and luminescence study on the low-lying excited states of sym-triazines, namely, 1,3,5-triazine (1) and the ubiquitous herbicides atrazine [6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (2)] and ametryn [6-methylthio-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (3)]. Geometrical structures, energetics, and transition and state properties of I and 2 were computed at the TD-DFT, CASSCF, and CASPT2 levels of theory. The fluorescence and phosphorescence emission spectra, lifetimes, and fluorescence quantum yields were measured for the three compounds, and from these, the energies of the lowest excited states and their corresponding radiative rates…
A call for dissensus in art education!
2019
This article argues for the relevance of the term dissensus by the French philosopher Jacques Rancière in an art educational context in particular and an educational context in general. This argument is based on research referred to in this article, where the author made use of dissensus to analyse how encounters with contemporary art contribute to movements in youngsters’ ways of relating to artworks and the environment that surrounds them, as well as changes in the ways of relating to themselves and others ‐ what here is called events of subjectivation. As dissensus is seen as a premise for subjectivation, the author argues for initiating dissensus by introducing students to both art and …
Toward adjustment profiles for lower secondary student-athletes in the Finnish dual career context: A mixed-methods approach
2022
Engagement, burnout, and experiences are central concepts for understanding student-athlete adjustment in a dual career (DC) environment. As part of a larger 3-year, lower secondary sports schools pilot project, the aim of this study was to examine student-athletes’ DC adjustment in Finnish lower secondary sports schools at the end of the second academic year. By combining quantitative and qualitative methods, we sought to (a) identify adjustment profiles among student-athletes based on measures of engagement and burnout in school and sport and (b) to extract experiences that describe the distribution of student-athletes in the profiles. A latent profile analysis using questionnaire data fr…