Search results for " density"
showing 10 items of 2709 documents
Uncertainties in polarimetric 3D reconstructions of coronal mass ejections
2015
P.P. acknowledges STFC for financial support. Date of Acceptance: 21/01/2015 Aims. The aim of this work is to quantify the uncertainties in the three-dimensional (3D) reconstruction of the location of coronal mass ejections (CMEs) obtained with the so-called polarization ratio technique. The method takes advantage of the different distributions along the line of sight of total (tB) and polarized (pB) brightnesses emitted by Thomson scattering to estimate the average location of the emitting plasma. This is particularly important to correctly identify of CME propagation angles and unprojected velocities, thus allowing better capabilities for space weather forecastings. Methods. To this end, …
Molecular Electron Density Theory: A Modern View of Reactivity in Organic Chemistry
2016
A new theory for the study of the reactivity in Organic Chemistry, named Molecular Electron Density Theory (MEDT), is proposed herein. MEDT is based on the idea that while the electron density distribution at the ground state is responsible for physical and chemical molecular properties, as proposed by the Density Functional Theory (DFT), the capability for changes in electron density is responsible for molecular reactivity. Within MEDT, the reactivity in Organic Chemistry is studied through a rigorous quantum chemical analysis of the changes of the electron density as well as the energies associated with these changes along the reaction path in order to understand experimental outcomes. St…
Experimental investigations of two doubly excited NI multiplets
2005
Experimental Stark-broadening studies of two NI multiplets ( 1 D)3s 2 D - ( 1 D)3p 2 D° and ( 1 D)3s 2 D - ( 1 D) 3 p 2 F° are reported. Measurements were performed using a wall-stabilized arc operated at atmospheric pressure in helium with small amounts of nitrogen and hydrogen. The Stark broadening parameters: the electron impact width (w e ) and shift (d e ) have been determined.
Increased conductivity of a hole transport layer due to oxidation by a molecular nanomagnet
2008
Thin film transistors based on polyarylamine poly?N,N?-diphenyl-N,N ?bis?4-hexylphenyl?- ?1,1?biphenyl?-4,4?-diamine ?pTPD? were fabricated using spin coating in order to measure the mobility of pTPD upon oxidation. Partially oxidized pTPD with a molecular magnetic cluster showed an increase in mobility of over two orders of magnitude. A transition in the mobility of pTPD upon doping could also be observed by the presence of a maximum obtained for a given oxidant ratio and subsequent decrease for a higher ratio. Such result agrees well with a previously reported model based on the combined effect of dipolar broadening of the density of states and transport manifold filling. Peer Reviewed
1H nmr chemical shifts of [14]annulenes and their dianion salts
1987
Abstract The bridged (14]annulene 2 was reduced into its dianion and the structure of the dianion salt was proven by chemical and spectroscopic means. The 1H NMR spectroscopic properties of 2 are similar to those of the structurally related bridged [14]annulene 1 , whereas the corresponding dianions 2 2- and 1 2- are strikingly different. The geometries of 1 and 2 and their dianions were studied by means of a modified π-SCF force field approach. Almost planar perimeters without significant bond length alternation are obtained for the neutral annulenes 1 and 2 , whereas their dianions are characterized by structures with reduced symmetry. The 1H chemical shifts of the bridged [14]annulenes a…
First-principles calculations for SrTiO3() surface structure
2002
As a continuation of our recent abinitio calculations of SrTiO 3(1 0 0) surface relaxation for the two different terminations (SrO and TiO2) [Phys. Rev. B 64 (2001) 23417], we analyze here their electronic structures (band structure, density of states, and the electronic density redistribution with emphasis on the covalency effects). We compare results of abinitio Hartree–Fock method with electron correlation corrections and density functional theory with different exchange-correlation functionals, including hybrid (B3PW, B3LYP) exchange techniques. Our results are also compared with previous abinitio plane-wave local density approximation calculations and experiments when availab le. Consi…
Electrophoresis of colloidal dispersions in the low-salt regime
2007
We study the electrophoretic mobility of spherical charged colloids in a low-salt suspension as a function of the colloidal concentration. Using an effective particle charge and a reduced screening parameter, we map the data for systems with different particle charges and sizes, including numerical simulation data with full electrostatics and hydrodynamics and experimental data for latex dispersions, on a single master curve. We observe two different volume fraction-dependent regimes for the electrophoretic mobility that can be explained in terms of the static properties of the ionic double layer.
A comprehensive experimental study of the rheological behaviour of HDPE.
1986
Extensional properties of four high density polyethylenes with different molecular weights and molecular weight distributions are presented. The samples have already been well characterized in shear and non-isothermal extensional flow. The data were collected at 180 °C for elongational rates between 3 · 10−1 and 10−4s−1. Some qualitative and quantitative generalizations of the results are given.
Preventive effect of risedronate on bone loss and frailty fractures in elderly women treated with anastrozole for early breast cancer.
2011
The aim of this study was to assess the effect of adjuvant anastrozole, alone or associated with risedronate, on BMD and bone fracture risk in women more than 70 years old with hormone receptor-positive early breast cancer (EBC). In a group of 51 elderly women (aged 76.4 ± 5.0 years) considered for adjuvant aromatase inhibitors for EBC, 24 patients with T-scores ≥ -2 and no prevalent fractures received anastrozole 1 mg/day (group A), and 27 patients with T-scores < -2, or with T-scores ≥ -2 and prevalent fractures (group B), received anastrozole (1 mg/day) plus risedronate (35 mg/week). Both groups received supplementation with 1 g calcium carbonate and 800 IU vitamin D per day. Differen…
Computational nuclear quantum many-body problem: The UNEDF project
2013
The UNEDF project was a large-scale collaborative effort that applied high-performance computing to the nuclear quantum many-body problem. The primary focus of the project was on constructing, validating, and applying an optimized nuclear energy density functional, which entailed a wide range of pioneering developments in microscopic nuclear structure and reactions, algorithms, high-performance computing, and uncertainty quantification. UNEDF demonstrated that close associations among nuclear physicists, mathematicians, and computer scientists can lead to novel physics outcomes built on algorithmic innovations and computational developments. This review showcases a wide range of UNEDF scien…