FE3 EPR investigation of PLZT 1/65/35 and 8/65/35

X-band EPR spectra of PLZT 1/65/35 and PLZT 8/65/35 doped with 1% FE³⁺ were recorded at temperature range -175°C to 200°C. Three types of paramagnetic centers were found. Two of them are in strong axial and rhombic crystal field due to neighboring oxygen and lead vacancies. The other center has symmetry determined by polarization and oxygen octahedra tilt. EPR spectra of PLZT 8/65/35 are in agreement with its glassy behavior.     

Monte Carlo simulation of thermodynamic systems with cluster formation under different boundary conditions

Thethermodynamic state function free energy F(T,V,N) as function of the cluster distribution N and the thermodynamic parameters (temperature T and volume V) is calculated in the canonical ensemble. With the help of the Legendre transformation we get all other state functions for different boundary conditions. Monte Carlo simulations with 15000 particles starting from metastable homogeneous initial conditions are made for water and methanol. The Bethe-Weizsäcker ansatz and the Padé approximation are used for the binding energy of clusters. A first-order phase transition is observed under appropriate conditions.     

Vaccine genotype and route of administration affect pseudorabies field virus latency load after challenge

The influence of vaccine genotype and route of administration on the efficacy of pseudorabies virus (PRV) vaccines against virulent PRV challenge was evaluated in a controlled experiment using five genotypically distinct modified live vaccines (MLVs) for PRV. Several of these MLVs share deletions in specific genes, however, each has its deletion in a different locus within that gene. Pigs were vaccinated with each vaccine, either via the intramuscular or intranasal route, and subsequently challenged with a highly virulent PRV field strain. During a 2-week period following challenge with virulent PRV, each of the vaccine strains used in this study was evaluated for its effectiveness in the reduction of clinical signs, prevention of growth retardation and virulent virus shedding. One month after challenge, tissues were collected and analyzed for virulent PRV latency load by a recently developed method for the electrochemiluminescent quantitation of latent herpesvirus DNA in animal tissues after PCR amplification. It was determined that all vaccination protocols provided protection against clinical signs resulting from field virus challenge and reduced both field virus shedding and latency load after field virus challenge. Our results indicated that vaccine efficacy was significantly influenced by the modified live vaccine strain and route of administration. Compared to unvaccinated pigs, vaccination reduced field virus latency load in trigeminal ganglia, but significant differences were found between vaccines and routes of administration. We conclude that vaccine genotype plays a role in the effectiveness of PRV MLVs.     

The calculations of dispersion coefficients inside two‐dimensional randomly packed beds of circular particles

The longitudinal (D_L) and transverse (D_T) dispersion coefficients in two‐dimensional (2‐D) randomly packed beds of circular particles in a laminar flow regime are derived. A 2‐D discrete system of particles is divided into cells using modified Voronoi diagrams. The relationship between the variation of the stream function and the averaged vorticity is obtained from computational fluid dynamics (CFD) simulations. The whole flow pattern is then obtained by using the principle of energy dissipation rate minimization. The obtained values of D_L agree well with 3‐D experimental data for all velocities investigated. At very high velocities, D_T in 2‐D appears to be higher than 3‐D experimental data. In addition, the effects of particle‐size distributions, packing structure, and porosity on the D_L and D_T were studied. One result was that an increase in the width of the particle‐size distribution resulted in higher values of D_L and D_T at high velocities. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1002–1011, 2013     

Numerical derivation of dispersion coefficients for flow through three‐dimensional randomly packed beds of monodisperse spheres

The longitudinal (D_L) and transverse (D_T) dispersion coefficients for flow through randomly packed beds of discrete monosized spherical particles are studied. The three‐dimensional (3‐D) porous‐medium model consists of thousands of spherical particles that are divided into cells using Voronoi diagrams. The relationship between the variation of the dual stream function and the vorticity between neighboring particles is derived using Laurent series. The whole flow pattern at low particle Reynolds number is then obtained by minimization of the dissipation rate of energy with respect to the dual stream function. The D_L is obtained by fitting the resulting effluent curve to a 1‐D solution of a continuous model. The D_T is obtained by fitting the numerical concentration profile to an approximate 2‐D solution. The derived D_L and D_T values are in agreement with 3‐D experimental data from the literature enabling a study of the effects of pore structure and porosity on D_L and D_T. © 2013 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J 60: 749–761, 2014