Search results for "Valence"
showing 10 items of 2732 documents
Evaluation of the magnetic moment ofRa213
1991
The hyperfine field at the nucleus of singly ionized radium has been investigated using the relativistic linked-cluster many-body-perturbation-theory procedure, including the effects of distributed charge and magnetization over the nucleus. The total hyperfine field of 1239 T, when combined with the experimentally observed hyperfine constant for $^{213}\mathrm{Ra}^{+}$, yields a nuclear moment of 0.607(12)${\mathrm{\ensuremath{\mu}}}_{\mathit{N}}$, in excellent agreement with the experimentally observed moment of 0.6133(18)${\mathrm{\ensuremath{\mu}}}_{\mathit{N}}$ from Zeeman measurements. Our investigation leads to exchange core-polarization and correlation contributions of 14% and 13%, r…
Quasi-elastic reactions: an interplay of reaction dynamics and nuclear structure
2011
Multinucleon transfer reactions have been investigated in 40Ar+208Pb with the Prisma+Clara set-up. The experimental differential cross sections of different neutron transfer channels have been obtained at three different angular settings taking into account the transmission through the spectrometer. The experimental yields of the excited states have been determined via particle-γ coincidences. In odd Ar isotopes, we reported a signif cant population of 11/2− states, reached via neutron transfer. Their structure matches a stretched conf guration of the valence neutron coupled to vibration quanta.
Superheavy element flerovium (element 114) is a volatile metal.
2014
The electron shell structure of superheavy elements, i.e., elements with atomic number Z ≥ 104, is influenced by strong relativistic effects caused by the high Z. Early atomic calculations on element 112 (copernicium, Cn) and element 114 (flerovium, Fl) having closed and quasi-closed electron shell configurations of 6d(10)7s(2) and 6d(10)7s(2)7p1/2(2), respectively, predicted them to be noble-gas-like due to very strong relativistic effects on the 7s and 7p1/2 valence orbitals. Recent fully relativistic calculations studying Cn and Fl in different environments suggest them to be less reactive compared to their lighter homologues in the groups, but still exhibiting a metallic character. Expe…
Nuclear Two-Body Interaction and Configuration Mixing
2007
In previous chapters the nucleus was described as a collection of non-interacting nucleons in a mean-field potential. The wave function of a nuclear state was taken to be a Slater determinant corresponding to a definite way of placing the valence nucleons in the mean-field single-particle orbitals. In this way the energy of a nuclear state was fully determined by the energies of the occupied single-particle orbitals.
Effects of the Surface and Finite Temperature on the Electronic Structure of Metal Clusters
1996
The most fascinating feature of simple metal clusters is the existence of the electronic shell structure. This was observed first in alkali[1] and noble metals[2] and later also in some other nontransition metals[3,4,5]. The shell structure is a consequence of nearly free valence electrons confined to a finite volume. A spherical potential will always lead to a shell structure, the origin of which is the orbital angular momentum l and the large degeneracy (2l+1) associated with it. However, this primitive shell structure is strengthened by ’accidental’ degeneracies between states having different principal quantum numbers. Thus the shell structure of a hydrogen atom is different from that o…
Energy gap of intermediate-valentSmB6studied by point-contact spectroscopy
2001
We have investigated the intermediate valence narrow-gap semiconductor ${\mathrm{SmB}}_{6}$ at low temperatures using both conventional spear-anvil type point contacts as well as mechanically controllable break junctions. The zero-bias conductance varied between less than $0.01 \ensuremath{\mu}\mathrm{S}$ and up to 1 mS. The position of the spectral anomalies, which are related to the different activation energies and band gaps of ${\mathrm{SmB}}_{6},$ did not depend on the the contact size. Two different regimes of charge transport could be distinguished: Contacts with large zero-bias conductance are in the diffusive Maxwell regime. They had spectra with only small nonlinearities. Contacts…
Electronic structure of a quantum ring in a lateral electric field
2001
The electronic states of novel semiconductor quantum rings (QR's) under applied lateral electric fields are theoretically investigated for different values of the ratio ${r}_{2}{/r}_{1},$ where ${r}_{2}$ ${(r}_{1})$ is the outer (inner) radius of the ring. The eigenstates and eigenvalues of the Hamiltonian are obtained from a direct matrix diagonalization scheme. Numerical calculations are performed for a hard-wall confinement potential and the electronic states are obtained as a function of the electric field and the ratio ${r}_{2}{/r}_{1}.$ An anomalous behavior in the energy vs. electric-field fan plot due to the break of symmetry is predicted. Analytical expressions for the energy level…
Formulation predictive dissolution (fPD) testing to advance oral drug product development: an introduction to the US FDA funded ‘21st Century BA/BE’ …
2018
Over the past decade, formulation predictive dissolution (fPD) testing has gained increasing attention. Another mindset is pushed forward where scientists in our field are more confident to explore the in vivo behavior of an oral drug product by performing predictive in vitro dissolution studies. Similarly, there is an increasing interest in the application of modern computational fluid dynamics (CFD) frameworks and high-performance computing platforms to study the local processes underlying absorption within the gastrointestinal (GI) tract. In that way, CFD and computing platforms both can inform future PBPK-based in silico frameworks and determine the GI-motility-driven hydrodynamic impac…
Predicting Pharmacokinetics of Multisource Acyclovir Oral Products Through Physiologically Based Biopharmaceutics Modeling.
2021
Abstract Highly variable disposition after oral ingestion of acyclovir has been reported, although little is known regarding the underlying mechanisms. Different studies using the same reference product (Zovirax ®) showed that Cmax and AUC were respectively 44 and 35% lower in Saudi Arabians than Europeans, consistent with higher frequencies of reduced-activity polymorphs of the organic cation transporter (OCT1) in Europeans. In this study, the contribution of physiology (i.e., OCT1 activity) to the oral disposition of acyclovir immediate release (IR) tablets was hypothesized to be greater than dissolution. The potential role of OCT1 was studied in a validated physiologically-based biopharm…
Generalized distance-squared mappings of the plane into the plane
2016
Abstract We define generalized distance-squared mappings, and we concentrate on the plane to plane case. We classify generalized distance-squared mappings of the plane into the plane in a recognizable way.