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Detailed structural characterization and experimental measurement of airflow across open‐celled aluminum foam structures with near‐spherical cells varying in pore sizes and interstices are presented herein. The aluminum foam structures were produced by infiltrating liquid aluminum into convergent gaps created by packed beds of near‐spherical hydrosoft salt beds varying in particle sizes, packing densities, and infiltration pressures. A quantitative assessment of the unit pressure drops developed across these structures show that viscous and inertial terms of these structures were observed to greatly depend on the shape and structural macroscopic parameters of the porous medium. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1355–1364, 2019 [ABSTRACT FROM AUTHOR]

Summary: We introduce a smoothed particle hydrodynamics (SPH) concept for the stabilization of the interface between 2 fluids. It is demonstrated that the change in the pressure gradient across the interface leads to a force imbalance. This force imbalance is attributed to the particle approximation implicit to SPH. To stabilize the interface, a pressure gradient correction is proposed. In this approach, the multi‐fluid pressure gradients are related to the (gravitational and fluid) accelerations. This leads to a quasi‐buoyancy correction for hydrostatic (stratified) flows, which is extended to nonhydrostatic flows. The result is a simple density correction that involves no parameters or coefficients. This correction is included as an extra term in the SPH momentum equation. The new concept for the stabilization of the interface is explored in 5 case studies and compared with other multi‐fluid models. The first case is the stagnant flow in a tank: The interface remains stable up to density ratios of 1:1000 (typical for water and air), in combination with artificial wave speed ratios up to 1:4. The second and third cases are the Rayleigh‐Taylor instability and the rising bubble, where a reasonable agreement between SPH and level‐set models is achieved. The fourth case is an air flow across a water surface up to density ratios of 1:100, artificial wave speed ratios of 1:4, and high air velocities. The fifth case is about the propagation of internal gravity waves up to density ratios of 1:100 and artificial wave speed ratios of 1:4. It is demonstrated that the quasi‐buoyancy model may be used to stabilize the interface between 2 fluids up to high density ratios, with real (low) viscosities and more realistic wave speed ratios than achieved by other weakly compressible SPH multi‐fluid models. Real wave speed ratios can be achieved as long as the fluid velocities are not very high. Although the wave speeds may be artificial in many cases, correct and realistic wave speed ratios are essential in the modelling of heat transfer between 2 fluids (eg, in engineering applications such as gas turbines). [ABSTRACT FROM AUTHOR]

A multicentre, controlled, randomised and blinded study was carried out in three French pig herds to assess the efficacy of doxycycline administered in the feed for the control of pneumonia. About 20 per cent of 363 pigs from the three fattening units were diseased at the start of the study. Pneumonic lesions were found on pigs examined postmortem and was isolated from the lungs of pigs in all the herds. infection was confirmed either by detection in pneumonic lungs or by seroconversion in pigs sampled three weeks apart. and were isolated from 64 per cent, 50 per cent and 2 per cent, respectively, of 148 nasal swabs. The following variables were significantly different between the treated and untreated groups (P≤0.001): the incidence of diseased pigs during the three weeks from the start of treatment (8.1 per cent in treated group v 35.4 per cent in control group), mean daily weight gain over the same period (934 g/day in the treated group v 834 g/day in the control group) and the cure rate of pigs which were diseased at the start of treatment (73.5 per cent in treated group v 35.3 per cent in control group). These data demonstrate that an average dose of 11 mg doxycycline/kg bodyweight per day in feed for eight days was effective in controlling pneumonia due to and in these fattening pigs. [ABSTRACT FROM PUBLISHER]

Minimum inhibitory concentrations of doxycycline and oxytetracycline were determined against 55 strains, 59 strains and 26 strains isolated from the respiratory tract of pigs. An additional set of 76 strains isolated from pneumonic pigs was tested for their minimum inhibitory concentrations of doxycycline. The and strains were isolated in France and the minimum inhibitory concentrations were determined by an agar dilution method. The strains were isolated in the United Kingdom and minimum inhibitory concentrations were determined by a serial broth dilution method. All the strains tested were susceptible to doxycycline whereas 15 per cent of the strains and 22 per cent of the strains were resistant to oxytetracycline. Doxycycline concentrations inhibiting 90 per cent of strains were 1 μg/ml for and 2 μg/ml for . The ratio of the minimum inhibitory concentrations of doxycycline and oxytetracycline ranged between 1/1 and 1/4 for the oxytetracycline-susceptible strains and between 1/16 and 1/64 for the oxytetracycline-resistant strains. All the strains were susceptible to doxycycline and oxytetracycline, the concentrations inhibiting 90 per cent of strains being 1 μg/ml and 2 μg/ml, respectively. These data confirm that doxycycline has a higher in vitro activity against pig respiratory pathogens than oxytetracycline. [ABSTRACT FROM PUBLISHER]