Influence of ultrasound application on the microbiota of raw goat milk and some food pathogens including Brucella melitensis

The aim of the present study was to investigate the detrimental effect of ultrasound application, as an alternative to pasteurization, on raw goat milk microorganisms and some food pathogens including Brucella melitensis. For this purpose, six different ultrasound applications with a power of 20 kHz at 100%, 50% and 10% amplitudes with or without pulsation were practiced. Colour changes as an increase in brightness (L-value) and decrease in yellow colour value (b-value) were determined in either pasteurized or ultrasonified groups. The most efficient detrimental effect on bacteria was obtained at 100% amplitudes (III and IV group). In these groups, decrease of TAMB, coliforms, streptococci, lactobacilli, yeast and mould counts were 6.52, 6.27, 5.31, 5.61, 5.27 and 4.02 log cfu/ml respectively in raw milk. Inactivation of food pathogens Brucella melitensis type 3, Salmonella Typhimirium, Escherichia coli, Listeria monocytogenes and methicilin resistant Staphylococcus aureus inoculated in goat milk was approximately 99%, which was as efficient as HTST and LTLT pasteurization process. Consequently, ultrasound applications can be an alternative to heat processes in dairy since effective bacterial inactivation could be attained in a relatively economic and environmentally friendly way.

A blood-mimicking fluid with cholesterol as scatter particles for wall-less carotid artery phantom applications

Aim of the study: At present, there are few scatter particles used in preparing blood-mimicking fluids, such as nylon, sephadex, polystyrene microsphere, and poly(4-methystyrene). In this study, we present cholesterol as a new scatter particle for blood-mimicking fluid preparation. Materials and methods: The procedure for the preparation of the proposed blood-mimicking fluid involved the use of propylene glycol, D(+)-Glucose and distilled water to form a ternary mixture fluid, with cholesterol used as scatter particles. Polyethylene glycol was first used as part of the mixture fluid but the acoustic and physical properties were not suitable, leading to its replacement with D(+)-Glucose, which is soluble in water and has a higher density. A common carotid artery wall-less phantom was also produced to assess the flow properties. Results: The prepared blood-mimicking fluid with new scatter particles has a density of 1.067 g/cm3, viscosity of 4.1 mPa.s, speed of sound 1600 m/s, and attenuation of 0.192 dB/cm at 5 MHz frequency. Peak systolic velocity, end diastolic velocity and mean velocity measurements were gotten to be 40.2 ± 2.4 cm/s, 9.9 ± 1.4 cm/s, and 24.0 ± 1.8 cm/s, respectively. Conclusion: Based on the results obtained, the blood-mimicking fluid was found suitable for ultrasound applications in carotid artery wall-less phantoms because of its good acoustic and physical properties.

Analysis of Predistortion Techniques on Fresnel Zone Plates in Ultrasound Applications

In this work, we analyze the effect of predistortion techniques on the focusing profile of Fresnel Zone Plates (FZPs) in ultrasound applications. This novel predistortion method is based on either increasing or decreasing the width of some of the FZP Fresnel rings by a certain amount. We investigate how the magnitude of the predistortion, as well as the number and location of the predistorted rings, influences the lens focusing profile. This focusing profile can be affected in different ways depending on the area of the lens where the predistortion is applied. It is shown that when the inner area of the lens, closer to its center, is predistorted, this technique allows the control of the focal depth at the main focus. However, when the predistortion is applied to an area farther from the center of the lens, the acoustic intensity distribution among the main focus and the closest adjacent secondary foci can be tailored at a certain degree. This predistortion technique shows great potential and can be used to control, modify and shape the FZP focusing profile in both industrial and therapeutic applications.