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Objectives: Sonication of explanted prosthesis constitutes an element of microbiological diagnostics. The aim of performing this procedure is to remove biofilm and to increase sensitivity of diagnostics. Ultrasound used for medical purposes are low-frequency and low-intensity. With this wide range of frequency which can be used in sonication process it is necessary to find the golden mean between biofilm dislodging and planktonic bacteria sparing. Materials and methods: The aim of this study was to determine the least harming low-intensity ultrasound frequency (35 kHz, 40 kHz or 53 kHz) used during sonication process with other parameters constant. Four bacteria species were examined: S. aureus, E. faecalis, E. coli, K. pneumoniae. Number of microbiological studies (n) for each group (g) counted 40 specimens (based on scheme 1 bacteria type – 4 groups, 40 studies each). Results: A detailed analysis of gathered data was conducted. Based on study findings following conclusions were drawn. Sonication has a significant and negative impact on survival of sonicated planktonic bacteria. Part of bacteria in planktonic state are damaged/killed by ultrasound, which is demonstrated by lower CFU count in sonicated samples versus control group. Conclusions: Optimal ultrasound frequencies for sonication of S. aureus, P. aeruginosa and E. coli are 35 kHz and 40 kHz. Ultrasound frequencies used in sonication process (35 kHz, 40 kHz, 53 kHz) of E. coli showed same impact on bacteria survival. It is crucial to perform further assessment of ultrasound parameters on clinical effects of sonication used in PJI diagnostics.

The aim of this study was to investigate the effects of process conditions as well as ultrasound and microwave pretreatments on shrinkage of potato strips during deep-fat frying process. Ultrasound pretreatment was performed at frequencies of 28 and 40 kHz and microwave pretreatment was conducted at powers of 3 and 6 W/g on the potato slices. Then, the frying process was done at 150, 170 and 190°C for 1, 2, 3 and 4 min. According to the results, ultrasound pretreatment significantly reduced the shrinkage of potato strips. However, microwave pretreatment resulted in a significant increase in the samples shrinkage. In addition, frying time as an important process factor had a significant effect on shrinkage; such that by increasing time, shrinkage was increased. Moreover, the results showed that temperature effect on shrinkage is not significant. Furthermore, six models were presented in order to predict shrinkage considering the process conditions and for the models constants, multivariate models were obtained based on multivariate regression analysis as a function of process conditions (ultrasound frequency, microwave power and process temperature).

The objective of this study was to investigate the effect of ultrasonic frequencies and drying time on fatty acid profiles of beef jerky samples possessing different microbial compositions. Beef slices were cured using curing solutions formulated both with and without Lactobacillus sakei . Curing was carried out for 18 h at 4 °C prior to hot air drying at 60 °C for 4 h. Jerky samples from both treatment groups were then subjected to ultrasonic frequencies of 25 kHz, 33 kHz and 45 kHz for 30 min. Beef jerky samples were subsequently analysed for fatty acid profile using Gas Chromatography. In the present study, beef slices showed a high level of MUFAs, which accounted for 45.6–53.8%, followed by the SFAs (36.3–47.8%) and PUFAs (4.8–13.7%), respectively. Results demonstrated a significant effect of beef jerky processing on fatty acid profile. Various correlation analyses showed that changes in fatty acid profiles were significantly affected by individual and/or interactive effects of L. sakei , drying time and ultrasonic frequency.

This paper presents an experimental study of the ultrasonic degradation of organic pollutants in terms of the effect of ultrasonic frequency (40–380–850–1000 kHz). The removal efficiency of two endocrine disrupting compounds [17β-estradiol (E2) and 17α-ethinylestradiol (EE2)] is investigated using laboratory scale ultrasonic baths at low power intensities. Higher ultrasonic frequencies were found to be more effective for pollutant degradation with 850 kHz the best: 9.0 × 10−1 mg/kW h for E2 and 6.8 × 10−1 mg/kW h for EE2 at initial concentrations of 1 ppm. Additionally, the removal of p-nitrophenol was investigated under the same conditions, as a dosimetry reaction for estimating the hydroxyl radical production, key component in organic pollutant removal. In order to describe the overall phenomena occurring inside the reactor and to predict the apparent hydroxyl radical production, a simulation algorithm is proposed. It incorporates the solution of ODE systems that embodies bubble dynamics, heat and mass transfer through the bubble wall and chemical reactions in the gas–vapor phase for an initial bubble nuclei population. The experimental degradation measures of p-nitrophenol over the range of frequencies studied were found to be comparable with the model results of hydroxyl radicals produced during the sonication treatment.

Cataloged from PDF version of article. Capacitive micromachined ultrasonic transducers (cMUT) have become an alternative to piezoelectric transducers in the past few years. They consist of many small circular membranes that are connected in parallel. In this work, we report; a new detection method for cMUTs. We model the membranes as capacitors and the interconnections between the membranes as inductors. This kind of LC net-work is called an artificial transmission line. The vibrations of the membranes modulate the electrical length of the transmission line, which is proportional to the frequency of the signal through it. By measuring the electrical length of the artificial line at a high RF frequency (in the gigahertz range), the vibrations of the membranes can be detected in a very sensitive manner. Far the devices we measured, we calculated the minimum detectable displacement to be in the order of 10(-5) Angstrom/root Hz with a possible improvement to 10(-7) Angstrom/root Hz.

Ultrasound is a promising non-thermal clean technology in the fresh-cut industry of vegetables due to the inactivation of microorganism caused by cavitation [1]. Depending on the intensity of the ultrasound, time of application and temperature, reduction levels up to 1.3 Log UFC/g have been achieved [2]. However, there are fewer studies that evaluate the effect of the frequency of the ultrasonic wave and treatment time on the reduction of microorganism. ¿e main aim of this work was to evaluate the effect of bath sonication treatments of 25 and 42 kHz during 10 and 20 minutes on slices of carrots. Experiments were conducted at 24.0 ± 1.0°C. ¿e temperature of the water bath and carrot slices was monitored during treatments. Mesophilic aerobic microorganisms, yeast and moulds were evaluated in accordance with ISO 4833:2003 and ISO 7954:1987 protocols. Additionally, instrumental colour and texture of carrot slices were also evaluated. ¿e higher the frequency–time applied the higher core temperature obtained. A¿er 20 minutes at 42 kHz, the core temperature raised 7.3 ± 0.2°C. However, at 25 kHz half of the increase was found, 3.3 ± 0.2°C. ¿e effect of ultrasound frequency and time was evaluated through two way-Anova analysis (¿ < 0.05). From our results there were no significant interaction between the studied factors (¿ > 0.05). ¿e reduction of mesophilic bacteria was higher at 25 kHz but there were a significant effect of the time of application. ¿e maximum reduction achieved was 1 Log10 at 10 minutes. ¿ere were no significant differences on the reduction of moulds and yeast and 1 Log10 reduction was achieved. Alegria et al. [3] obtained lesser microbial reduction in sonicated fresh-cut carrots (45 kHz / 1 min). ¿e authors reported a maximum of 0.5 Log10 reductions for both mesophilic flora and yeast and moulds group. ¿e instrumental firmness and colour of the all the sonicate carrot slices were no significantly different to the raw carrot (¿ > 0.05). From our results, ultrasonic treatment can be an alternative to reduce the microbial load in fresh-cut products with no effect on texture and colour. However, higher microorganism reductions may be needed by the fresh-cut industry. Further studies on the possible combination of clean treatments may be the solution to reduce the chlorine concentration used on these food products.