Bacterial growth on chicken eggs in various storage environments

An evaluation of the effects of various storage and transport conditions on the bacterial growth associated with chicken eggs that are usually transported without temperature control was done. Chicken egg samples were randomly collected from a layer management system that employs a fully automated environmental control unit. These eggs were subjected to temperature shocks to simulate various transport and storage conditions. The results show that a 4-h low temperature shock is the most effective condition for limiting organism growth in or on eggs. Much higher organism counts were found in both the egg contents and on the eggshells, which had been subjected to high temperature shocks. It is finally recommended to the egg industry that incorporating a cold shock of 4 h and consequent storage at 25 °C will contribute to a longer egg shelf life and enhanced egg quality.     

Experimental investigation of the effects of heat release on mixing processes and flow structure in a high-speed subsonic turbulent H2 jet

In this paper, we explore the effects of heat release on mixing and flow structure in a high-speed subsonic turbulent H₂ jet in an air coflow. Heat release effects are determined from the comparison of nonreacting and reacting jet behavior, boundary conditions being identical in both cases. Experiments are performed in a wind tunnel specifically designed for this purpose. Planar laser induced fluorescence on OH radicals and on acetone (seeded in the hydrogen jet) are used to characterize the cartography of scalars, and laser Doppler velocimetry is used to characterize velocity profiles in the far field of the H₂ jet. Results show significant effects of heat release on mixing and flow structure, indicating an overall reduction of mixing and entrainment in the reacting jet compared to the nonreacting jet. First, a change is observed in the orientation of coherent structures originating from Kelvin-Helmholtz type instabilities, and responsible for air entrainment within the jet, which appear “flatter” in the jet flame. Then, the flame length is increased over what would be predicted from the intersection of the mean stoichiometric contour with the centerline of the nonreacting jet. And finally, the longitudinal average velocity decrease along the jet axis is quicker in the nonreacting jet, and nondimensional transverse velocity fluctuations are about half as high in the reacting jet as in the nonreacting jet, indicating a reduction of the turbulence intensity of the flow in this direction in the jet flame.     

Improvement in calculation of some surface integrals: applicationto junction characterization in cavity filter design

A rigorous method which makes it possible to reduce a surface integral to a contour integral is developed. The application of this formulation to the study of a circular-to-rectangular waveguide junction reduces the time of computation of the scattering parameters by more than 50%. The method is used to calculate the electromagnetic coupling of circular cavities by a rectangular iris. This approach, together with an optimization procedure, has allowed the direct design of a filter without any further mechanical adjustments. The results obtained are in good agreement with experimental data     

The occurrence of campylobacters in water sources in South Africa

Campylobacter spp., mainly C. jejuni and C. coli, are recognized as significant human bacterial pathogens, being responsible for increasing numbers of gastroenteritis cases worldwide. Several reports have indicated that environmental waters are potential reservoirs and transmitting vehicles for these bacteria. The purpose of this study was thus to examine the occurrence of campylobacters in drinking and environmental water sources of South Africa, a country with a warmer climate and higher microbial pollution levels than those previously addressed in the Northern Hemisphere where similar investigations have been undertaken. Various types of water samples (five drinking water, four ground water, 11 surface water and four raw sewage) were collected from different parts of South Africa. Detection was by enrichment in Bolton broth prior to plating on both selective mCCDA or through a 0.6microm membrane filter on non-selective blood agar isolation media. Out of 100 initially selected Campylobacter-like isolates, only 22 did not grow aerobically and were subsequently identified as Campylobacter spp. by biochemical tests. However, the results obtained by 16S rRNA sequence analysis indicated that only three of these strains (13.6%) were Campylobacter jejuni and the remaining 19 strains were identified as Arcobacter butzleri. The spread of Arcobacter via water warrants further investigation, especially in view of the higher levels of detection and pathogenic nature of these bacteria.     

Oxidative reforming of methane to syngas over a NiO-CaO catalyst

Methane was successfully converted to synthesis gas by oxidative reforming over a reduced NiO-CaO catalyst first prepared by Choudhary et al. [1]. In order to compare this work with previously reported results, the effect of space velocity and temperature was investigated. Additionally, the lifetime of the catalyst was tested with both a dry and a wet feed, as well as the influence of CH₄/O₂ ratio on catalyst performance. In accordance with the results of Choudhary on this and other catalysts, the syngas yield was found to deviate from the expected equilibrium values. This may be attributed to the catalyst temperature being higher than the measured bulk gas temperature. Lifetime tests ( 500°C for 50 hours and 700°C for 20 hours) showed that the catalyst slowly lost activity and selectivity. In contrast, the inclusion of low steam feed rates resulted in stable operation (no deactivation and constant bed temperature). Decreasing the CH₄/O₂ ratio resulted in improved CH₄ conversion while, contrary to the expected equilibrium trend, CO selectivity remained constant. When space velocity was increased from 200 000 to 500 000 h⁻¹, CH₄ conversion and CO selectivity remained unchanged, but both values decreased when space velocity was again lowered to 200 000 h⁻¹.     

The life cycle of Gorgoderina rochalimai Pereira and Cuocolo, 1940, a Digenea parasite of Bufo marinus in Guadeloupe

The sporocysts of G. rochalimai were found in Guadeloupe, in the bivalve Mollusc Sphaeriidae Eupera viridans. The cystocercous cercariae are ingested by Odonatan larvae in which the encystement occurs. The Toad Bufo marinus is the definitive host of the parasite. The life-cycle of G. rochalimai shows close similarities with the ones already known in many other speicies of Gorgoderidae.     

Effect of heat treatment on the properties of laser-beam welded rheo-cast F357 aluminum

Semi-solid metal rheo-cast F357 aluminum plates were joined by autogenous Nd:YAG laser welding and were welded in either the as-cast (F) condition, T4 temper or T6 temper condition. The weldability of this age-hardenable Al-7%Si-0.6%Mg casting alloy was characterized by assessment of the microstructure in the fusion and heat-affected zones and by measurement of the weld-plate tensile and hardness properties. The low heat input provided by the laser welding process resulted in high cooling rates (450-600 K/s) within the fusion and adjacent heat affected zones. This thermal cycle closely resembles quenching practice for standard solution treatments (500-700 K/s) and as a result the T4 condition was maintained during the welding process. Tensile properties equivalent to the parent metal T6 condition were obtained after exposing welded T4 plates to conventional artificial ageing treatment.