Search Results (23)

Origanum dubium, mainly grown in the Mediterranean region, is one of the less extensively studied species among the oregano class. Oregano species are recognized for their significant pharmaceutical properties, primarily attributed to carvacrol and other phenolic compounds. The goal of this study was to establish a sustainable method for the extraction of carvacrol, total phenolic, and total flavonoid compounds (TPC and TFC, respectively). Pulse-mode ultrasonic-assisted extraction (UPAE) was employed, using ethanol–water mixtures as green solvents, for the extraction of the bioactive compounds from the plant material. A Box–Behnken design (BBD) coupled with Response Surface Methodology (RSM) was applied to optimize the extraction process with respect to the extraction temperature, extraction time, ethanol-to-water ratio of the solvent and power amplitude of the ultrasonic processor. The responses of carvacrol (determined by HPLC-PDA), TPC, and TFC (determined by spectrometric methods) were evaluated by RSM. The statistical model identified the optimal extraction conditions, which were a combination of increased extraction temperature (70 °C) for 26 min with an intermediate ethanol–water ratio (60%) at the maximum processor’s power amplitude (100%). These conditions led to the optimal response of the three measured parameters. The optimized parameters represent a green and efficient approach to obtain bioactive-enriched extracts from Origanum dubium, suitable for potential applications in functional foods, preservatives, or other applications. Full article

This paper presents a Class E zero-voltage soft-switching (ZVS) resonant inverter integrated with a CLC filter and a digital resonant frequency tracking technique for driving a piezoelectric ceramic transducer (PZT) in ultrasonic cleaning applications. A digital signal processor (DSP) is used to dynamically monitor and adjust the operating frequency in response to slight variations in the cleaning load, employing a phase-locked loop (PLL) control scheme. The proposed method ensures that the inverter maintains ZVS operation across a frequency range from 30.0 kHz to 34.0 kHz, thereby improving energy efficiency and reducing switching losses. The system is capable of delivering a stable power output of 100 W. Both the simulation and experimental results validate the effectiveness of the proposed technique, demonstrating improved performance under varying load conditions. The combination of CLC filtering and frequency tracking offers a compact and robust solution suitable for ultrasonic cleaner systems and similar resonant-load applications. Full article

In this study, graphene production via liquid-phase exfoliation assisted by sonication was evaluated using deionized water as a solvent and two graphite sources: one recovered from spent lithium-ion batteries (LIBs) and a commercial counterpart. A 750 W, 20 kHz ultrasonic processor was used, with sonication amplitudes ranging from 50% to 80% for two hours while maintaining a constant temperature of 45 °C. The resulting dispersions were left undisturbed for 24 h at ambient temperature to allow natural phase separation between decanted and dispersed fractions. These fractions were subsequently dried and weighed to determine exfoliation yield. High-quality graphene was successfully obtained via direct liquid-phase exfoliation of graphite recovered from LIBs, assisted by sonication in deionized water. Graphene formation was confirmed in both suspended and decanted fractions after two hours of sonication at 80% amplitude through complementary characterization techniques, including UV-Vis, Raman spectroscopy, HRTEM, and XRD. Comparative experiments using thermally pretreated battery graphite and commercial graphite revealed that graphene dispersions derived from untreated LIB-derived graphite exhibited greater long-term stability than those obtained from commercial or thermally pretreated battery graphite before sonication. Full article

Zinc has attracted significant attention as a versatile material with potential applications in various fields, particularly in biomedical engineering. Despite its desirable characteristics, such as biodegradability and biocompatibility, the inherently low mechanical strength of zinc has been a major limitation for its broader use in clinical applications. To address this issue and enhance its mechanical performance without compromising its biocompatibility, a novel composite material was developed by mixing zinc oxide (ZnO) with zinc (Zn). ZnO is widely recognized for its high chemical stability, non-toxicity, and antimicrobial properties, making it an excellent additive for biomedical materials. In this study, Zn-ZnO nanocomposites were fabricated by uniformly dispersing ZnO nanoparticles into molten zinc using an ultrasonic processor. The uniform distribution of ZnO nanoparticles within the zinc matrix was confirmed, and the resulting nanocomposites demonstrated remarkable improvements in mechanical properties. Specifically, the hardness and tensile strength of the Zn-ZnO nanocomposites were increased by approximately 90% and 160%, respectively, compared to pure zinc. To evaluate the biodegradation behavior of the materials, both pure zinc and Zn-ZnO nanocomposite samples were immersed in phosphate-buffered saline (PBS) at 37 °C, simulating physiological conditions. The degradation rate was assessed by measuring the weight loss of the material over time. The biodegradation rate of the Zn-ZnO nanocomposites was found to be nearly identical to that of pure zinc under identical conditions, indicating that the addition of ZnO did not adversely affect the degradability of the material. These findings suggest that Zn-ZnO nanocomposites offer a promising solution for biomedical applications by combining improved mechanical properties with maintained biodegradability and biocompatibility. Full article

Consumer acceptance of milk beverages as probiotic beverages is directly linked to their sensory qualities, such as flavor, consistency, visual appearance, and mouthfeel. Overall, products that exhibit syneresis are often viewed as inferior. Thus, this study was conducted to investigate the effects of high-intensity ultrasound on the production of probiotic strawberry beverages, aiming primarily to stabilize the beverage by reducing syneresis and improving sensory properties without compromising the viability of probiotic microorganisms. The effects of the ultrasound processing time (2.5, 5, 7.5, and 10 min) on the physical, chemical, and sensory properties of the beverages were analyzed. Ultrasound was applied using a 750-wW ultrasonic processor (Cole-Parmer^®, 750 W, Vernon Hills, IL, USA) at 40% amplitude, consuming 300 W and resulting in an acoustic power density of 1.2 W/mL. The results indicate that ultrasound significantly influenced the syneresis of the samples, with intermediate times (5 and 7.5 min) demonstrating lower liquid separation. Notably, the U7.5 treatment exhibited syneresis values of 52.06% ± 2.14, 60.75% ± 2.33, and 61.17% ± 1.90 at days 1, 14, and 28, respectively, corresponding to reductions of approximately 18%, 12%, and 11% compared to the control (63.43% ± 0.93, 68.81% ± 0.56, and 68.59% ± 0.10, respectively). The fatty acid composition showed changes according to storage time. Notably, palmitic acid (C16:0) concentrations were above 30 g/100 mL, and the ω6/ω3 ratio ranged from 5.92 to 7.47, falling within the recommended dietary values. Ultrasound also reduced the amount of sucrose in the samples, which may benefit the growth of probiotic microorganisms. In terms of sensory analysis, the ultrasound-treated samples (2.5 to 7.5 min) were preferred by the evaluators compared to the control sample. Furthermore, ultrasound treatment did not result in the inactivation of probiotics, supporting its potential for enhancing probiotic beverage quality. Thus, high-intensity ultrasound proved to be a promising technology for enhancing the quality of probiotic strawberry beverages by reducing syneresis, affecting fatty acid composition, and improving sensory characteristics. This may open up new opportunities in the food industry for more appealing and healthier probiotic products. Full article

Ultrasonic flowmeters are essential sensor devices widely used in remote metering systems, smart grids, and monitoring systems. In these environments, a low-power design is critical to maximize energy efficiency. Real-time data collection and remote consumption monitoring through remote metering significantly enhance network flexibility and efficiency. This paper proposes a low-complexity structure that ensures an accurate time-of-flight (ToF) estimation within an acceptable error range while reducing computational complexity. The proposed system utilizes Hilbert envelope detection and a differentiator-based parallel peak detector. It transmits and collects data through ultrasonic transmitter and receiver transducers and is designed for seamless integration as a node into wireless sensor networks (WSNs). The system can be involved in various IoT and industrial applications through high energy efficiency and real-time data transmission capabilities. The proposed structure was validated using the MATLAB software, with an LPG gas flowmeter as the medium. The results demonstrated a mean relative deviation of 5.07% across a flow velocity range of 0.1–1.7 m/s while reducing hardware complexity by 78.9% compared to the conventional FFT-based cross-correlation methods. This study presents a novel design integrating energy-efficient ultrasonic flowmeters into remote metering systems, smart grids, and industrial monitoring applications. Full article

Cellulose nanocrystals (CNC) receive great attention for their physical and optical properties, high surface area, high tensile strength, rigidity (Young’s modulus up to 140 GPa), and ease of surface modification. However, controlling the properties of CNC is still challenging, given the wide variety of pulp sources and the complexity of finding suitable processing conditions. In the present study, acid hydrolysis efficiently isolated CNC from wood Acacia mearnsii brown kraft pulp (AMKP). Initially, the AMKP was delignified by the treatment with acidified sodium chlorite. The Acacia mearnsii kraft pulp obtained was then subjected to acid hydrolysis with sulfuric acid at concentrations of 50 to 58% 45 °C for 60 min. The hydrolysate was sonicated in an ultrasonic processor for 30 min. The chemical composition was determined by Fourier transform infrared spectroscopy (FTIR), crystallinity by X-ray diffraction (XRD), zeta potential by Zetasizer ZS equipment, thermal stability by thermogravimetric analysis (TGA), and morphology by transmission electron microscopy (TEM) to verify the effect of acid concentration on the yield and properties of CNC. The optimization of the isolation process demonstrated that the maximum yield of 41.95% can be obtained when AMWP was hydrolyzed with sulfuric acid at a concentration of 54%. It was possible to isolate CNC with a crystallinity index between 71.66% and 81.76%, with the onset of thermal degradation at 240 °C; zeta potential of −47.87 to 57.23 mV; and rod-like morphology, with lengths and widths between 181.70 nm and 260.24 nm and 10.36 nm and 11.06 nm, respectively. Sulfuric acid concentration significantly affected the yield of acid hydrolysis, allowing the isolation of CNC with variable dimensions, high thermal stability, high crystallinity index, and great colloidal stability in aqueous medium. Full article

This paper presents an approach to damage identification in beams by modal curvatures based on the use of beamforming algorithms. These processors have been successfully used in acoustics for the last thirty years to solve the inverse problems encountered in source recognition and image reconstruction, based on ultrasonic waves. In addition, beamformers apply to a broader range of problems in which the forward solutions are computable and measurable. This especially concerns the field of structural vibrations, where the use of such estimators has not received attention to date. In this paper, modal curvatures will play the role of replica vectors of the imaging field. The choice to use modal curvatures is motivated by means of numerical studies and experimental tests on a steel beam. Furthermore, we compare the performance of the Bartlett and minimum variance distortionless response (MVDR) beamformers with an estimator based on the simple minimization of the difference between model and measured data. The results suggest that the application of the MVDR beamformer is highly effective, especially in cases of slight damage between two sensors. MVDR enables both damage localization and quantification. Full article

In this paper, the essential oil (EO) extraction from thyme by the consecutive use of ultrasound and microwave treatments is presented. The aim of this study was to apply an ultrasound pre-treatment of thyme leaves to enhance the thymol content and the extraction yield of the EO obtained by microwave-assisted hydro-distillation (MWHD). Compared with conventional hydro-distillation (CHD), the consecutive use of ultrasound pre-treatment and microwave extraction resulted in a 72% lower extraction time. When the ultrasound pre-treatment (using the ultrasonic processor with an amplitude of 70%) was applied, the EO content was 23% higher compared to the extraction without pre-treatment (2.67 ± 0.06 g EO/100 g DM for the MWHD with ultrasound pre-treatment compared with 2.18 ± 0.07 g EO/100 g DM for the MWHD without pre-treatment). The EO samples were analyzed by GC/MS. The results showed that the major component, thymol, varied from 43.54% (by CHD) to 65.94% (by the consecutive use of ultrasound and microwave treatments). Full article

The caper bush has developed different mechanisms to survive in Mediterranean conditions, such as drought tolerance and seed dormancy. Many studies have been carried out to improve the germination of caper seeds, but ultrasound is one of the least studied methodologies in this species. This study aimed to analyze the effects of treatments with an ultrasonic probe processor on the imbibition and germination of caper seeds. After applying the ultrasound treatment using three output powers and three holding times, the seed coat’s disruption level was determined, and the imbibition, viability and germination tests were carried out. Ultrasonication fastens the initial imbibition, but after 48 h of soaking, seed moisture does not present differences compared to non-sonicated seeds. It produces the scarification of the testa but does not affect the tegmen, so moistening occurs through the hilar region, as in control seeds. There is a significant linear and negative correlation between the germination of the seeds and the temperature reached during the sonication treatment, so that temperatures above 40 °C practically annulled the germination. The combination of 20 W and 60 s provided the greatest germination percentage, being the only treatment that statistically improves germination in relation to the control seeds. When the output power and/or holding time were higher, the temperature increased, and the germination percentage statistically decreased. Full article

A study that evaluated the use of ultrasonic-guided waves to detect water in hollow pipes is presented. In this work, a guided wave system employed a 40 kHz piezoelectric (PZT) transmitter and a PZT ultrasound transducer. The transmitter was based on a battery-operated microcontroller, and the receiver was composed of a digital signal processor (DSP) module connected to a PC via a USB for monitoring purposes. The transmitter and receiver were attached, non-intrusively without perfect alignment, to the external wall of a steel tube 1 m × 270 mm × 2 mm in size. Flood detection was performed based on guided wave attenuation due to energy leakage from the internal steel wall of the tube to water. Two approaches were carried out. The former was an off-line signal response based on the wavelet energy entropy analysis of a received pulse; the latter was a real-time hit-and-miss analysis centered on measuring the time–space in-between two transmitted pulses. Experiments performed in the laboratory successfully identified flooded tubes. Full article

The purpose of this study was to optimize the effect of particle size, time and ultrasonic intensity on the extraction of phenolic compounds and energy efficiency. Sonication was performed with a VC750 Sonics processor at the following amplitudes: 30, 50 and 70%, which corresponds to the ultrasonic intensity, respectively: 1.6; 5.1 and 8.6 W∙cm⁻². The frequency of ultrasound was 20 kHz. Extraction was carried out in a 5 s on–10 s off pulse system. The content of polyphenols and their antioxidant activity were assayed by the spectrophotometric method. Response surface methodology (RMS) was used to optimize the investigated variables. On the basis of the developed model, the highest polyphenols yield was obtained under the following extraction conditions (particle size 0.65 mm, extraction time 13.14 min, ultrasound intensity 6.92 W∙cm⁻², which resulted in a maximum value of 15.24 mg GAE∙g⁻¹ dry matter of hemp. Taking into account the lowest unit energy consumption, the best conditions were obtained for particle size of approx. 0.5 mm, extraction time 7.7 min, and ultrasound intensity 1.8 W∙cm⁻², which resulted in a phenolic yield of 10.14 mg GAE∙g⁻¹ dry matter of hemp. The best agreement between values of optimization variables within investigated criteria was obtained for the variable particle size. The developed models of pulsed ultrasound-assisted extraction can be used for obtaining polyphenols from Cannabis sativa L. at low unit energy consumption. Full article

The rapid growth of the electronics industry and the increase in processor power levels requires new techniques to improve the heat transfer rate in their cooling systems. In this study, ultrasonic vibration technology was introduced as an active method to enhance the thermal performance of water-cooling systems. The effects of ultrasonic vibrations at power levels of 30, 60, and 120 watts for different cooling airflow rates were investigated experimentally. The results were validated with available empirical correlations to ensure the accuracy of the measurement systems. The findings indicated that the ultrasonic vibrations enhanced the heat transfer in the liquid-cooling heat exchangers. In addition, the thermal performance of the ultrasonic vibrations was improved by reducing the airflow rate and increasing the ultrasonic power. In addition to the feature of heat transfer improvement, ultrasonic waves are widely used for the cleaning of different types of heat exchangers. Regarding the anti-fouling and anti-accumulation effects of the ultrasonic vibrations, the introduced technology could provide a practical way for developing high-performance nanofluids-based computer cooling systems. Full article

Visually impaired people face many challenges that limit their ability to perform daily tasks and interact with the surrounding world. Navigating around places is one of the biggest challenges that face visually impaired people, especially those with complete loss of vision. As the Internet of Things (IoT) concept starts to play a major role in smart cities applications, visually impaired people can be one of the benefitted clients. In this paper, we propose a smart IoT-based mobile sensors unit that can be attached to an off-the-shelf cane, hereafter a smart cane, to facilitate independent movement for visually impaired people. The proposed mobile sensors unit consists of a six-axis accelerometer/gyro, ultrasonic sensors, GPS sensor, cameras, a digital motion processor and a single credit-card-sized single-board microcomputer. The unit is used to collect information about the cane user and the surrounding obstacles while on the move. An embedded machine learning algorithm is developed and stored in the microcomputer memory to identify the detected obstacles and alarm the user about their nature. In addition, in case of emergencies such as a cane fall, the unit alerts the cane user and their guardian. Moreover, a mobile application is developed to be used by the guardian to track the cane user via Google Maps using a mobile handset to ensure safety. To validate the system, a prototype was developed and tested. Full article

The pineapple is an essential fruit in Taiwan. Farmers separate pineapples into two types, according to the percentages of water in the pineapples. One is the “drum sound pineapple” and the other is the “meat sound pineapple”. As there is more water in the meat sound pineapple, the meat sound pineapple more easily rots and is more challenging to store than the drum sound pineapple. Thus, farmers need to filter out the meat sound pineapple, so that they can sell pineapples overseas. The classification, based on striking the pineapple fruit with rigid objects (e.g., plastic rulers) is most commonly used by farmers due to the negligibly low costs and availability. However, it is a time-consuming job, so we propose a method to automatically classify pineapples in this work. Using embedded onboard computing processors, servo, and an ultrasonic sensor, we built a hitting machine and combined it with a conveyor to automatically separate pineapples. To classify pineapples, we proposed a method related to acoustic spectrogram spectroscopy, which uses acoustic data to generate spectrograms. In the acoustic data collection step, we used the hitting machine mentioned before and collected many groups of data with different factors; some groups also included the noise in the farm. With these differences, we tested our deep learning-based convolutional neural network (CNN) performances. The best accuracy of the developed CNN model is 0.97 for data Group V. The proposed hitting machine and the CNN model can assist in the classification of pineapple fruits with high accuracy and time efficiency. Full article