hartree-fock (hf) and density functional theory (dft) methods employed to study the effect of conformational change on the 13c chemical shifts of 6-mono axial and equatorial substituted and 6,7-di axial-axial, equatorial-equatorial and axial-equatorial substitutedderivatives of 5,6,7,8-tetrahydrodibenzo[a,c]cyclo-octene. the geometry of the conformers have been optimized in the gas phase employ...

G. Fehrenbacher, F. Gutermuth, T. Radon GSI Darmstadt, Germany An important aspect to be considered when designing the GSI future project will be the radiation protection of both the staff and the environment. One of the prerequisites for a permission for the operation of a high-energy accelerator is a careful planning of the necessary radiation shielding equipment. In order to give recommendat...

Shielding effects of a nanocage can be determined by the field felt by an encapsulated noble gas (NG) atom. Using the polarizability distributions about NG endohedral fullerenes (NGEFs), a new scheme based on the local polarizability of the NG is introduced to detect the shielding effects of fullerenes, using density functional theory calculations and Hirshfeld population analysis. For large ca...

The requirements for shielding a treatment vault with a Varian Clinac 2100 medical linear accelerator operated both with and without the flattening filter were assessed. Basic shielding parameters, such as primary beam tenth-value layers (TVLs), patient scatter fractions, and wall scatter fractions, were calculated using Monte Carlo simulations of 6, 10 and 18 MV beams. Relative integral target...

During the 1960s Andrew and others examined the rapid spinning of a sample about an axis that makes an angle of 54” 44’ with the direction of the static magnetic field (I-LJ in order to remove broadening effects in the NMR spectra of solids (l-3). It was much later when Schaefer and Stejskal (4) applied this approach, magic-angle spinning (MAS), to remove broadening due to chemical shift anisot...

in this research, we studied the structure, properties and nmr parameters of interaction f2 gas with pristine and 3c-doped (8, 0) zigzag models of boron phosphide nanotubes (bpnts). in order to reach these aims, we considered four different configurations for adsorption of f2gas on the outer and inner surfaces of bpnts. the structures of all models were optimized by using density functional the...

Background The use of a medical simulator should enhance the goals of minimally invasive surgery: patient safety, cosmesis, shortening the length of hospital admissions, and reducing cost. Using an innovative approach to the handling of ultrasound images in virtual reality simulation, this article describes a process that employs a hybrid model of deformable models that can be applied in the te...

In the discussion that follows, we assume that gamma rays are the radiation of interest. The principles discussed also apply to monoenergetic x rays; in many cases of concern in x-ray shielding, however, the photons are produced in the bremsstrahlung process that yields a wide and continuous distribution of photon energies. Specialized shielding approaches have been developed to carry out shiel...