Variational calculation of positronium-helium-atom scattering length

A basis-set calculation scheme for S-waves Ps-He elastic scattering below the lowest inelastic threshold was formulated using a variational expression for the transition matrix. The scheme was illustrated numerically by calculating the scattering length in the electronic doublet state: a=1.0±0.1 a.u.

Quantum mechanical study of YTiO3 to the investigation of piezoelectricity

In previous articles we reported through theoretical studies the piezoelectric effect in BaTiO3, SmTiO3, and YFeO3. In this paper, we used the Douglas-Kroll-Hess (DKH) second-order scalar relativistic method to investigate the piezoelectricity in YTiO3. In the calculations we used the [6s4p] and [10s5p4d] Gaussian basis sets for the O (3P) and Ti (5S) atoms, respectively, from the literature in combination with the (30s21p16d)/[15s9p6d] basis set for the Y ( 3D) atom, obtained by generator coordinate Hartree-Fock (GCHF) method, and they had their quality evaluated using calculations of total energy and orbital energies (HOMO and HOMO-1) of the 2TiO+1 and 1YO+1 fragments. The dipole moment, the total energy, and the total atomic charges in YTiO3 in C s space group were calculated. When we analyze those properties we verify that it is reasonable to believe that YTiO3 does not present piezoelectric properties. Copyright © 2011 Raimundo Dirceu de Paula Ferreira et al.

Estudo da interação entre flavonóides e a albumina do soro humano

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

As influências do realismo político e do complexo industrial-militar no expansionismo norte americano (1990-2004)

Pós-graduação em História - FCLAS

Theoretical study of molecular and electronic structures of 5(1) knot systems: two-layered ONIOM calculations

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variational and perturbative schemes for a spiked harmonic oscillator

A variational analysis of the spiked harmonic oscillator Hamiltonian operator - d2/dx2 + x2 + l(l + 1)/x2 + λ|x| -α, where α is a real positive parameter, is reported in this work. The formalism makes use of the functional space spanned by the solutions of the Schrödinger equation for the linear harmonic oscillator Hamiltonian supplemented by a Dirichlet boundary condition, and a standard procedure for diagonalizing symmetric matrices. The eigenvalues obtained by increasing the dimension of the basis set provide accurate approximations for the ground state energy of the model system, valid for positive and relatively large values of the coupling parameter λ. Additionally, a large coupling perturbative expansion is carried out and the contributions up to fourth-order to the ground state energy are explicitly evaluated. Numerical results are compared for the special case α = 5/2. © 1989 American Institute of Physics.

Thermogravimetry on calcined mass basis - hydrated cement phases and pozzolanic activity quantitative analysis

When cement hydrated compositions are analyzed by usual initial mass basis TG curves to calculate mass losses, the higher is the amount of additive added or is the combined water content, the higher is the cement 'dilution' in the initial mass of the sample. In such cases, smaller mass changes in the different mass loss steps are obtained, due to the actual smaller content of cement in the initial mass compositions. To have a same mass basis of comparison, and to avoid erroneous results of initial components content there from, thermal analysis data and curves have to be transformed on cement calcined basis, i.e. on the basis of cement oxides mass present in the calcined samples or on the sample cement initial mass basis.The paper shows and discusses the fundamentals of these bases of calculation, with examples on free and combined water analysis, on calcium sulfate hydration during false cement set and on quantitative evaluation and comparison of pozzolanic materials activity.

Confecção e montagem do set-up ortodôntico

Diagnosis and planning stages are critical to the success of orthodontic treatment, in which the orthodontist should have many elements that contribute to the most appropriate decision-making. The orthodontic set-up is an important resource in the planning of corrective orthodontics therapy. It consists of the repositioning of the teeth previously removed from the study dental casts and reassembled on its remaining basis. When properly made, the set-up allows a three-dimensional preview of problems and limitations of the case, assisting in decision-making regarding tooth extractions in cases with problems of space, amount of anchorage loss extent and type of tooth movement, discrepancy of dental arch perimeter, discrepancy of inter-arch tooth volume, among others, indicating the best option for treatment. This paper outlines the most important steps for its confection, an evaluation system and its application in the preparation of orthodontic treatment planning.

Montagem e confecção do set up ortodôntico

Diagnosis and planning stages are critical to the success of orthodontic treatment, in which the orthodontist should have many elements that contribute to the most appropriate decision-making. The orthodontic set-up is an important resource in the planning of corrective orthodontics therapy. It consists of the repositioning of the teeth previously removed from the study dental casts and reassembled on its remaining basis. When properly made, the set-up allows a three-dimensional preview of problems and limitations of the case, assisting in decision-making regarding tooth extractions in cases with problems of space, amount of anchorage loss extent and type of tooth movement, discrepancy of dental arch perimeter, discrepancy of inter-arch tooth volume, among others, indicating the best option for treatment. This paper outlines the most important steps for its confection, an evaluation system and its application in the preparation of orthodontic treatment planning.