Quadruply excited beryllium-like atoms – a semiclassical model

The semiclassical spectrum of quadruply highly excited four-electron atomic systems has been calculated for the plane model of equivalent electrons. The energy of the system consists of rotational and vibrational modes within the circular skeleton orbit approximation, as used in a previous calculation for the triply excited three-electron systems. The full dynamical analysis is carried out within the Hamiltonian theory, accounting for the inertial effects and the complete coupling between different degrees of freedom. Here we present numerical results for energy spectrum of the beryllium atom. The lifetimes of the semiclassical states are estimated via the corresponding Lyapunov exponents. The vibrational modes relative contribution to the energy levels rises with the degree of the Coulombic excitation.     

β-Glucan from mushrooms and dates as a wall material for targeted delivery of model bioactive compound: Nutraceutical profiling and bioavailability

Rutin was nano-encapsulated in date [En-Ru(D)] and mushroom [En-Ru(M)] β-glucan matrix to protect it from the harsh gastrointestinal environment and to enhance its bioavailability and biological activity upon digestion. The encapsulation was carried using green technology i.e., ultra-sonication. The En-Ru(D) and En-Ru (M) showed the hydrodynamic diameter of 314.04 and 482.21 nm with polydispersity index of 0.21 and 0.33. The in vitro release behaviour followed the Higuchi model. The antimicrobial activity of En-Ru(D) and En-Ru(M) were evaluated against gram negative E. coli (ATCC 25922) and gram positive (Staphylococcus aureus) bacteria. Furthermore, En-Ru(D) and En-Ru(M) exhibited increased bioavailability of rutin in intestinal fluid with retention of anti-obesity and antioxidant activities after digestion (p < 0.05). Therefore, β-glucan matrix can efficiently encapsulate flavonoids and regulate the release of functional bioactive ingredients in the simulated human digestive conditions.     

Superposition model in electron magnetic resonance spectroscopy – a primer for experimentalists with illustrative applications and literature database

We review applications of the superposition model (SPM) in EMR area, which enables semi-empirical modeling of zero-field splitting (ZFS) parameters (ZFSPs) for transition ions in crystals by separation of geometrical and physical information. Nomenclature used for ZFS and crystal field (CF) Hamiltonians is presented to expose common framework underlying two independent implementations: SPM/ZFS and SPM/CF, which require distinct model parameters. SPM/ZFSP applications in EMR area for S-state 3d⁵ (4f⁷) ions and 3d^N ions with orbital singlet ground state are reviewed. SPM/ZFS methodology for ML_n complexes [central metal (M) ion surrounded by n ligands (L)] with specific symmetry is presented. SPM-related computer packages combined with other methods, role of axis systems in SPM analysis, and structural models for several ion-host systems, are discussed. Extensive survey of SPM/ZFS applications is provided to elucidate usefulness of SPM modeling for interpretation of ZFSPs. This review is geared for EMR practitioners interested in practical utilization of SPM/ZFS (or SPM/CFP) analysis. Database of SPM/ZFS references is compiled for studies of single molecule magnets and single ion magnets based on transition ions. Due to its comprehensiveness, suitable sets of model parameters required for practical utilization SPM/ZFS may be easily located using source references as pointers.     

The quasiparticle rpa as a model for gamow-teller ß-decay

The validity of the quasiparticle random-phase approximation is studied by comparing it with full shell-model calculations in the sd-shell. Phenomenological interactions relevant for the sd-shell have been applied, and Gamow-Teller ß⁺ strengths are calculated. It is found that in the QRPA, the ß⁺ strength is a factor of two higher than the shell-model result. The shell-model results are less sensitive to the particle-particle interaction strength than the QRPA. With u, v factors from the shell-model wavefunctions, the ß⁺ strength in the QRPA reproduces the shell-model result. This suggests that the QRPA does not contain enough ground-state correlations.     

Exotic nuclei – a challenge for nuclear mean field models

We present a brief overview of the interplay between exotic nuclei and the development of nuclear mean field models. This is exemplified with four test cases addressing the topics of shape coexistence, isotope shifts, long isotopic chains, and superheavy elements. This revised version was published online in August 2006 with corrections to the Cover Date.     

3D simulation of the lightning path using a mixed physical-probabilistic model – The open source lightning model

The modeling of the lightning channel's propagation has been a major issue in lightning protection. Several solutions are already existing based on different assumptions revealing different properties of the lightning, including return strokes, the orientation point (and distance), and several other factors. The path of the lightning channel however is very hard to model using the physical equations and laws only, since a lot of the boundary conditions and starting conditions are unknown. Thus for these purposes the probabilistic approach is practically used. In this paper a lightning path simulation method is shown based on a probabilistic approach. The lightning path is mainly influenced by the electric field, and the existence of the start electrons. These conditions can't always be calculated, thus in many cases a probabilistic model shall be used. The model proposed in this article has a modular approach, it consists of several components. Each of these components can be improved based on existing theories, and empirical data, and this makes this simulation method – besides the realization – “open source”, as the components can be improved individually. At this stage of the development, many lightning parameters are yet omitted, but the model structure of course allows further improvement on this field as well.     

Prediction for α3(Mz) in a string-inspired model

We apply the Renormalisation Group Evolution (RGE) to analyse the phenomenological implications of an extended supersymmetric model, for the value of the unification scale and the strong coupling at the electroweak scale. The model we consider is predicted to exist in Calabi–Yau string compactifications with Wilson line mechanism for E₆ symmetry breaking, contains additional matter beyond the MSSM spectrum and avoids the “doublet-triplet” splitting problem in the Higgs sector. The calculation is analytical in two-loop order and includes the effects of the heavy thresholds due to the additional matter considered. The value of α₃(M_z) can be brought within the experimental limits without a significant change of the unification scale from the MSSM prediction.     

Yang–Baxter equation-based potential model for a one-dimensional fermion system

We propose a velocity-dependent δ-function potential model for a one-dimensional fermion system, under which the two-particle interchange operators in the Bethe hypothesis satisfy the Yang–Baxter equation. This model, proportional to the product of the momenta of two interacting particles, is not translation invariant. It is found that the ground-state particle distribution densities become negative in the low momentum region. To resolve the controversy, we apply an overall momentum shift to the system, and obtain reasonable solutions. The dependence of the ground-state distributions on the momentum shift is discussed.     

Asymptotic solution for a class of sea-air oscillator model for El Nin^～o-southern oscillation

The El Nifio-Southern Oscillation （ENSO） is an interannual phenomenon involved in the tropical Pacific Oceanatmosphere interactions. In this paper, an asymptotic method of solving the nonlinear equation for the ENSO model is used. And based on a class of oscillator of ENSO model, the approximate solution of a corresponding problem is studied by employing the perturbation method. Firstly, an ENSO model of nonlinear time delay equation of equatorial Pacific is introduced, Secondly, by using the perturbed method, the zeroth and first order asymptotic perturbed solutions are constructed. Finally, from the comparison of the values for a figure, it is seen that the first asymptotic perturbed solution using the perturbation method has a good accuracy. And it is proved from the results that the perturbation method can be used as an analytic operation for the sea surface temperature anomaly in the equatorial Pacific of the atmosphere-ocean oscillation for the ENSO model.     

Green’s function for an electron model with a plane wave

The Green function for a Dirac particle subject to a plane wave field is constructed according to the path integral approach and the Barut’s electron model. Then it is exactly determined after having fixed a matrix U chosen so that the equations of motion are those of a free particle, and by using the properties of the plane wave and also with some shifts.      

Moment stability for a predator–prey model with parametric dichotomous noises

In this paper,we investigate the solution moment stability for a Harrison-type predator–prey model with parametric dichotomous noises.Using the Shapiro–Loginov formula,the equations for the first-order and second-order moments are obtained and the corresponding stable conditions are given.It is found that the solution moment stability depends on the noise intensity and correlation time of noise.The first-order and second-order moments become unstable with the decrease of correlation time.That is,the dichotomous noise can improve the solution moment stability with respect to Gaussian white noise.Finally,some numerical results are presented to verify the theoretical analyses.     

A phase cell cluster expansion for a hierarchical Ø 3 4 model

The formalism developed in a previous paper is applied to yield a phase cell cluster expansion for a hierarchical ø ₃ ⁴ model. The field is expanded into modes with specific renormalization group scaling properties. The present cluster expansion for a vacuum expectation value is formally the natural factorization of each term in the perturbation expansion into the contribution of modes connected to the variables in the expectation via interactions, and that of the complementary set. The expectation value is thus realized as a sum of contributions due tofinite subsets of the modes. We emphasize the following additional features:

1. Partitions of unity are not used.
2. There areessentially no cut-offs.
3. The expansion is developed directly, without an initial need to prove an ultraviolet stability bound, the most difficult part of the traditional approach.

Our main interest in the present phase cell cluster expansion is founded in the belief that it may be the right vehicle for proving the existence of a nontrivial four-dimensional field theory.     

Numerical study of friction-induced instability and acoustic radiation – Effect of ramp loading on the squeal propensity for a simplified brake model

This paper presents a numerical study of the influence of loading conditions on the vibrational and acoustic responses of a disc brake system subjected to squeal. A simplified model composed of a circular disc and a pad is proposed. Nonlinear effects of contact and friction over the frictional interface are modelled with a cubic law and a classical Coulomb?s law with a constant friction coefficient. The stability analysis of this system shows the presence of two instabilities with one and two unstable modes that lead to friction-induced nonlinear vibrations and squeal noise. Nonlinear time analysis by temporal integration is conducted for two cases of loadings and initial conditions: a static load near the associated sliding equilibrium and a slow and a fast ramp loading. The analysis of the time responses shows that a sufficiently fast ramp loading can destabilize a stable configuration and generate nonlinear vibrations. Moreover, the fast ramp loading applied for the two unstable cases generates higher amplitudes of velocity than for the static load cases. The frequency analysis shows that the fast ramp loading generates a more complex spectrum than for the static load with the appearance of new resonance peaks. The acoustic responses for these cases are estimated by applying the multi-frequency acoustic calculation method based on the Fourier series decomposition of the velocity and the Boundary Element Method. Squeal noise emissions for the fast ramp loading present lower or higher levels than for the static load due to the different amplitudes of velocities. Moreover, the directivity is more complex for the fast ramp loading due to the appearance of new harmonic components in the velocity spectrum. Finally, the sound pressure convergence study shows that only the first harmonic components are sufficient to well describe the acoustic response.     

Derivation of a 1/r~2 potential term for Q in a potential model

We clarify the difference among potential models so far proposed to explain mass spectra of heavylight mesons via transformations of the vacuum.Applying our idea to QQ quarkonium,we obtain the extra term,1/r 2 with positive coefficient,other than non-relativistic potential terms expected for quarkonium.     

A classical particle in a Poincaré gauge field as a model for the gravitational interaction

The geometrical and mechanical aspects of a particle interacting with a Poincaré gauge field are considered and the relation with a gravitational interaction is studied.     

Validation of a lattice Boltzmann model for gas–solid reactions with experiments

A lattice Boltzmann method is used to model gas–solid reactions where the composition of both the gas and solid phase changes with time, while the boundary between phases remains fixed. The flow of the bulk gas phase is treated using a multiple relaxation time MRT D3Q19 model; the dilute reactant is treated as a passive scalar using a single relaxation time BGK D3Q7 model with distinct inter- and intraparticle diffusivities. A first-order reaction is incorporated by modifying the method of Sullivan et al. [13] to include the conversion of a solid reactant. The detailed computational model is able to capture the multiscale physics encountered in reactor systems. Specifically, the model reproduced steady state analytical solutions for the reaction of a porous catalyst sphere (pore scale) and empirical solutions for mass transfer to the surface of a sphere at Re = 10 (particle scale). Excellent quantitative agreement between the model and experiments for the transient reduction of a single, porous sphere of Fe₂O₃ to Fe₃O₄ in CO at 1023 K and 10⁵ Pa is demonstrated. Model solutions for the reduction of a packed bed of Fe₂O₃ (reactor scale) at identical conditions approached those of experiments after 25 s, but required prohibitively long processor times. The presented lattice Boltzmann model resolved successfully mass transport at the pore, particle and reactor scales and highlights the relevance of LB methods for modelling convection, diffusion and reaction physics.     

Novel multi-band quantum soliton states for a derivative nonlinear Schrödinger model

We show that localized N-body soliton states exist for a quantum integrable derivative nonlinear Schrödinger model for several nonoverlapping ranges (called bands) of the coupling constant η. The number of such distinct bands is given by Euler's φ-function which appears in the context of number theory. The ranges of η within each band can also be determined completely using concepts from number theory such as Farey sequences and continued fractions. We observe that N-body soliton states appearing within each band can have both positive and negative momentum. Moreover, for all bands lying in the region η>0, soliton states with positive momentum have positive binding energy (called bound states), while the states with negative momentum have negative binding energy (anti-bound states).     

The Massachusetts Toxics Use Reduction Act: a model for nanomaterials regulation?

Polyvinylimidazole (PVIm)-grafted superparamagnetic iron oxide nanoparticles (SPION) (Si-PVIm-grafted Fe₃O₄ NPs) were prepared by grafting of telomere of PVIm on the SPION. The product identified as magnetite, which has an average crystallite size of 9?±?2?nm as estimated from X-ray line profile fitting. Particle size was estimated as 10.0?±?0.5?nm from TEM micrographs. Mean particle size is found as 8.4?±?1.0?nm which agrees well with the values calculated from XRD patterns (9?±?2?nm). Vibrating Sample Magnetometer (VSM) analysis explained the superparamagnetic nature of the nanocomposite. Thermogravimetric analysis showed that the Si-Imi is 25?% of the Si-PVIm-grafted SPION, which means an inorganic content is about 75?%. Detailed electrical and dielectric properties of the properties of the product are also presented. The conductivity of the sample increases significantly with temperature and has the value in the range of 1.14?×?10^?7?C1.78?×?10^?4?S?cm^?1. Analysis of the real and imaginary parts of the permittivities indicated temperature and frequency dependency representing interfacial polarization and temperature-assisted reorganization effects.