Ultrasonic Bath Research Articles

Effect of Ultrasonic Extract of Capparis spinosa‎‎ Fruits Against E. coli‎‎ O157:H7‎


 
 
 
 E. coli‎‎ O157:H7, is one of the main causes of diarrhea and the most prevalent bacterial ‎infection that causes serious illnesses. This research was conducted to investigate the effect of Capparis ‎spinosa fruit ultrasonic extract against resistant E. coli‎‎ O157:H7 was isolated from stools of calves ‎that were suffering from diarrhea; the bacteria were identified by the Vitek 2 system and a latex agglutination ‎test. C. spinosa‎‎‎ was extracted by ultrasonic waves water bath. The phytochemicals were carried out on C. ‎spinosa fruit extract to detect the secondary metabolites. The MIC of the extract was calculated with ‎concentrations of 400, 800, 1600, 3200, 6400, 12800 and 25600 51200 µg/mL by microdilution method ‎‎(checkerboard). While using a field-emission scanning electron microscope to observe the morphological ‎alterations in E. coli‎‎ O157:H7 sample. The findings of this study revealed that the extract contains some ‎biologically active compounds like alkaloids, flavonoids, steroids, glycosides, tannins, cumarines, saponins, ‎quinones, and amino acids. That extract of C. spinosa‎‎‎ had a MIC of 6400 µg/mL and had a perfect action ‎against E. coli‎‎. O157:H7 by forming vacuoles within the cells and that internal content had seeped out as pore ‎formation. This finding could potentially provide an explanation for the traditional utilization of ‎this plant material as an antibacterial agent‎‎.
 
 
 

Effect of ultrasonic agitation on marginal adaptation, intratubular penetration and bonding strength of calcium-silicate-based endodontic sealers: A laboratory study.

The effect of ultrasonic activation (UA) on marginal adaptation, intratubular penetration and bond strength provided by three calcium silicate-based sealers was evaluated. Ninety-six distobuccal root canals of maxillary molars were randomly divided into 8 groups (n = 12) according to the sealer and UA application: EndoSequence BC sealer (ESBC), Sealer Plus BC (SPBC) and Bio-C Sealer (BCS), using AH Plus (AH) as a control group. The specimens were sectioned at 2, 4 and 6 mm from the apex. The data were statistically analysed using Kruskall-Wallis, Dunn, Mann-Whitney and chi-squared tests. UA improved the marginal adaptation of ESBC (6 mm), SPBC (all levels), BCS (2/4 mm) and AH (4 mm) (p < 0.05); the bond strength of SBPC (2 mm) and BCS (6 mm) were also improved (p < 0.05). The UA of endodontic silicate-based sealers improved the marginal adaptation in all levels and the bond strength of SBPC and BCS sealer.

Development of Cloisite20A-polyurethane nanocomposite coatings for thermomechanical performance

Cloisite 20A-polyurethane (C20-PU) nanocomposites were prepared using three processing schemes at different reinforcement levels (1, 2 and 3 wt%). The H-bonding chemistry of hard segments (HS) of PU and C20, leads to compartment effect in C20-PU thus varying the mechanical performance, as deduced from nanoindentation studies. Elastic nanocomposites (7.8 % - 60.6 % decrease in the plasticity index) and plastic nanocomposites (4.8 %–25.3 % increase in the plasticity index) are produced by switching the sequence of homogenizer (HSH) and ultrasonic bath (USB), either in tandem or independently. Polymer phase mixing morphology indicated by Fourier transform infrared (FTIR) and plasticity indices derived from nanoindentation, corroborate the active role of compartment effect in governing the properties and performance of PU and C20-PU nanocomposites. Dynamic mechanical analyzer (DMA) studies demonstrate that C20-PU nanocomposites are thermally and mechanically more robust than pure PU, with a >10 °C right shift in the glass transition temperature (Tg) along with a reduction in Tg peak intensities of nanocomposites. These findings articulate the interaction between PU chains and 2D nanofiller with improved thermomechanical properties.

Nanoliposomal VEGF-R2 peptide vaccine acts as an effective therapeutic vaccine in a murine B16F10 model of melanoma

BackgroundThe vascular endothelial growth factor receptor-2 (VEGFR-2) plays an important role in melanoma development and progression. Peptide vaccines have shown great potential in cancer immunotherapy by targeting VEGFR-2 as a tumor-associated antigen and boosting the immune response against both tumor cells and tumor endothelial cells. Despite this, the low efficiency of peptide vaccines has resulted in moderate therapeutic results in the majority of studies. Enhancing the delivery of peptide vaccines using nanoliposomes is an important strategy for improving the efficacy of peptide vaccines. In this regard, we designed VEGFR-2-derived peptides restricted to both mouse MHC I and human HLA-A*02:01 using immunoinformatic tools and selected three peptides representing the highest binding affinities. The peptides were encapsulated in nanoliposomal formulations using the film method plus bath sonication and characterized for their colloidal properties.ResultsThe mean diameter of peptide-encapsulated liposomes was around 135 nm, zeta potential of − 17 mV, and encapsulation efficiency of approximately 70%. Then, vaccine formulations were injected subcutaneously in mice bearing B16F10-established melanoma tumors and their efficiency in triggering immunological, and anti-tumor responses was evaluated. Our results represented that one of our designed VEGFR-2 peptide nanoliposomal formulations (Lip-V1) substantially activated CD4+ (p < 0.0001) and CD8+ (P < 0.001) T cell responses and significantly boosted the production of IFN-γ (P < 0.0001) and IL-4 (P < 0.0001). Furthermore, this formulation led to a significant decrease in tumor volume (P < 0.0001) and enhanced survival (P < 0.05) in mice.ConclusionOur findings suggest that the nanoliposomal formulation containing VEGFR-2 peptides could be a promising therapeutic vaccination approach capable of eliciting strong antigen-specific immunologic and anti-tumor responses.

Encapsulation of atomized erythrocytes in liposomes as source of heme iron for oral supplementation strategies

AbstractThis work aimed to develop and characterize liposomes of atomized bovine erythrocytes (ABE‐liposomes) for potential use as a heme iron supplement or to fortify food with heme iron. Soy lecithin (SL) and Tween 80 (T80) were chosen to prepare empty liposomes (8 types), and ABE‐liposomes (16 types) by a rotary‐evaporated film method. Variables of interest for our study were: ABE concentration, proportion of SL:T80 and ultrasonic bath time. ABE‐liposomes were characterized according to appearance, color, morphology, Fourier transform infrared spectroscopy (FTIR), size, zeta potential, total iron content, encapsulation efficiency (EE) and in vitro iron release under gastrointestinal conditions. ABE‐liposomes presented a brown color and spherical shape. Hydrogen bridges were the main interactions in ABE‐liposomes. Their size ranged from 379 to 964 nm, the zeta potential from −56 to −74 mV, the iron concentration range was 0.8–9.0 mg/100 mL, and EE ranged from 29% to 48%. Ultrasonic bath time was the most important variable on the reduction of ABE‐liposomes' size and EE. Under in vitro gastrointestinal conditions, iron release from ABE‐liposomes occurred mainly at the intestinal level. In conclusion, ABE‐liposomes were effectively developed, which could become a complement for supplementation or food fortification strategies with nonheme for the prevention of iron deficiency anemia.Practical ApplicationsIn this study atomized bovine erythrocytes (ABE)‐liposomes were developed, due to the: (1) lack of supplements or products to fortify foods based on heme iron, (2) higher bioavailability of heme iron than nonheme iron, especially when working with ABE, and (3) ABE is a low value‐added product that is generated in slaughter plants and in turn is an excellent source of underutilized heme iron. In this study it was possible to develop ABE‐liposomes, where ABE was encapsulated inside liposomes, obtaining a product that could be used as a complement in iron supplementation strategies or food fortification to prevent or treat iron deficiency or iron deficiency anemia, especially in developing countries that have low consumption of heme iron.

Study of ultrasound, initial concentration and electrode material on the electrochemical removal of selenium and strontium

Since high concentrations of selenium and strontium in water can potentially harm human health, various methods have been developed for their treatment. The objective of this paper was to validate previously published studies on the electrochemical removal of selenium and strontium, while also reducing the reactor operating time and using an ultrasound assisted process. After careful evaluation of the preliminary experiments, a combination of aluminum and iron electrodes was identified as the most suitable option for further investigation. The Design of Experiments approach was utilized to study the effects of ultrasound intensity (0%, 50%, 100%), operating time (2, 6, 10 minutes), applied current (2.5, 7.5, 12.5 A), and initial concentrations of selenium and strontium (1, 3, 5 mg L−1) on the sono-electrochemical removal of selenium and strontium from a synthetic solution. A modified ultrasonic bath, operating at 25 kHz, was used for all the experiments. The results showed that ultrasound and the initial selenium and strontium concentrations had no effect on the removal efficiency. The obtained reduced quadratic models predicted a removal efficiency of 93% for selenium and 34% for strontium under the optimal conditions, which included 10 minutes of operation and 12.5 A of current.

The role of surface tension on the growth of bubbles by rectified diffusion

Rectified diffusion has wide and important applications in sonochemistry, ultrasonic cleaning and medical ultrasound. Recent experimental results have demonstrated that the addition of surfactant substantially enhances bubble growth rate. As a hypothesis, this was widely attributed to the acoustic microstreaming and mass transfer resistance caused by surfactants. In this research, the effects of the surfactant of sodium dodecyl sulphate on the rectification have been simulated by considering only the variation of the surface tension coefficient due to the surfactant. The computations are carried out using a newly developed tractable model based on the multi-scale method and the method of matched asymptotic expansions, which allows the prediction of bubble growth taking place over millions of oscillation cycles. The rate of bubble growth observed in the experiments is accurately predicted by our computations, for a range for bulk surfactant SDS concentrations less than or equal to 2.4 mM. Contrary to the widely held hypothesis in the published literature, this has demonstrated that the dominant physical mechanisms remain the shell and area effects in this range of bulk surfactant concentrations. The further enhancement of bubble growth rate provided by either acoustic microstreaming or the resistance to mass transfer is only evident at higher bulk surfactant concentrations. Therefore, the role of surface tension in rectified diffusion for aqueous surfactant solutions is more significant than previously understood. The new results also show that the bubble growth rate is sensitive to small changes in the bubble radius which may account for its unpredictability in applications of sonochemistry.

Optimum Driving of Ultrasonic Cleaner Using Impedance and FFT Analysis with Validation of Image Processing of Perforated Foils

Over the past decade, ultrasonic cleaners have been widely used in many industries. Now, this technology is finding its way into homes for vegetable, fruit, and clothes cleaning. In widely used ultrasonic cleaners, piezoelectric transducers are externally attached to the steel tank to generate ultrasonic waves inside the tank. Based on the impedance data of the piezoelectric transducers, the driving circuit was tuned to generate the required frequencies inside the cleaning tank. This paper discusses the design, development, and validation of an 800 mL tank capacity ultrasonic cleaner driven with a piezoelectric disc actuator. To achieve an optimum cleaning action without surface abrasion, several characteristics need to be considered in this complex relationship. The placement of transducers has been investigated according to the pressure distribution inside the liquid medium. The optimized ultrasonic cleaner design, along with a class-D half-bridge circuit, was developed to drive the ultrasonic transducer in the resonance frequency range. To validate the optimal design and driving frequency, the acoustic spectrum generated inside the tank was measured using a piezoelectric sensor and FFT analysis was performed. To validate the cleaning effect, a qualitative test based on aluminuim foil perforations was performed. The perforation area in the foils was quantitatively measured using image processing based on the YOLO V5 technique. The proposed image processing technique has an accuracy of 97 % in the detection of perforation areas in the aluminuim foil test.

Sonochemical synthesis of Ag2CO3/CeO2 p-n heterojunction for decomposition of rhodamine B dye

Given their strong resistance to degradation and potential risks to both human health and aquatic life, the proper treatment of organic pollutants disposed in wastewater has received a lot of attention. In this study, we describe the development of an effective Ag2CO3/CeO2 p-n junction for the photocatalytic reduction of rhodamine B dye as a model cationic pollutant under UV radiation. Ag2CO3/CeO2 heterojunction was formed by combining sol-gel and sonochemical routes, on which silver carbonate is successfully distributed in a uniform arrangement on localized active sites in an ultrasonic bath of 300 W intensity. The physicochemical features of the solid specimen were explored via XRD, HRTEM, DRS, and PL experimental analysis. Ag2CO3 depresses the band gap energy of CeO2 revealing the shifting in the photocatalytic response to the visible region. The removal of RhB dye was performed under UV light radiation; however, the amount removed by the adsorption process does not exceed 15%. The decomposition of rhodamine B dye was carried out at a rate of 0.0035 min−1 for the optimum sample containing 5 wt % Ag2CO3 which is sevenfold higher than that on the surface of pristine CeO2 nanoparticles. The charge carrier migration proceeds through the type (II) heterojunction route by electron transfer from the conduction band of CeO2 to that of Ag2CO3.On the other hand, the positive hole jumps from the valence band of Ag2CO3 to that of CeO2. The charge carrier transportation occurs at the interface of the heterojunction until the Fermi levels of both oxidative and reductive are equilibrated and produce a strong inner electric field. The oxidation properties are determined by the positive holes of CeO2, while the reduced properties are controlled by the conduction band electrons of silver carbonate. The novel p–n junction is considered an excellent heterojunction for many photocatalytic applications.

Flow-Assisted Ultrasonic Exfoliation Enabling Scalable and Rapid Graphene Production for Efficient Inkjet-Printable Graphene Ink

Achieving high efficiency in graphene production and printing process simultaneously is challenging, but it needs to be addressed as it is critical for realizing the commercial viability of printed graphene devices. This study successfully substantiates these requirements by significantly improving the efficiency of graphene production and subsequently developing an inkjet-printable graphene ink that enables the rapid formation of the percolation network of graphene flakes. The integration of a flow coil reactor into an ultrasonic bath results in scalable and rapid graphene production, with graphene productivity up to three orders of magnitude higher than conventional liquid-phase exfoliation (LPE), offering the potential that ultrasonic LPE can benefit the scalability and simplicity of graphene production. In addition, the graphene ink, optimized by ink formulation, has a stable high graphene concentration of 3.5 g L–1, resulting in the formation of stable percolation networks of graphene flakes only after two printing passes under optimized printing conditions. The printed graphene patterns are also confirmed to be conformable to various substrates and durable against repeated stretching and bending stress. By ensuring high efficiency in graphene production and inkjet-printable ink preparation, this study would promote the commercialization of graphene production and the resulting printed graphene devices.

A randomized trial of the effectiveness of an ultrasonic denture hygiene intervention program among community dwelling elders.

This study aimed to assess the effectiveness of ultrasonic denture hygiene interventions in improving denture cleanliness among elderly individuals. Sixty-six participants who had received upper metal framework removable partial dentures within the past 5 years were randomly allocated into three denture hygiene intervention groups: group 1 (mechanical cleaning with a toothbrush and ultrasonic cleaning with cetylpyridinium chloride), group 2 (mechanical cleaning with a toothbrush and ultrasonic cleaning with distilled water), and control (mechanical cleaning with a toothbrush only). Denture cleanliness was assessed at baseline and 1-month using: i) Denture Cleanliness Index (DCI) scores; ii) plaque coverage percentage; and (iii) microbiological samples for bacterial and yeast detection. Differences between groups were assessed with one-way analysis of variance and Chi-squared tests. Mean DCI scores and mean percentages of plaque coverage area were significantly reduced in group 1 and group 2, compared to the control group for both cobalt chromium (CoCr) and acrylic fitting surfaces (p<0.001). No significant differences were found between groups 1 and 2 with regard to the prevalence and viable counts of yeasts or total microbial viable counts. No significant differences in the investigated clinical and microbiological parameters were observed between CoCr and acrylic surfaces following the intervention period. The ultrasonic cleaner was significantly more effective than mechanical cleaning in the reduction of biofilm coverage on metal framework removable partial dentures over a 1-month intervention period. Nevertheless, the adjunctive use of cetylpyridinium chloride with ultrasonic cleaning did not yield additional benefits.

Superhydrophobic Conductive Suede Fabrics Based on Carboxylated Multiwalled Carbon Nanotubes and Polydopamine for Wearable Pressure Sensors

Textile-based pressure sensors have attracted considerable attention due to their potential to detect vital signals in humans, enhance sports performance, and facilitate human–machine interactions. However, practical challenges, such as unstable assembly structures, weak interfacial bonds with functional materials, and incompatibility with current established finishing technologies in production, remain significant obstacles to their widespread applications. This research explores commercially available suede fabric as a promising substrate for pressure sensing. The conductive suede sensor was readily by integrating carboxylated multiwalled carbon nanotubes (C-MWCNTs) and polydopamine (PDA) and subsequently modifying it with hexadecyltrimethoxysilane to achieve a superhydrophobic surface. The resulting suede sensor, featuring a robust PDA-(C-MWCNTs)-HDTMS chemical configuration, exhibited satisfactory hydrophobicity, excellent stability, and repeatability, capable of detecting pulse, throat movement, and daily human motions. Furthermore, the properties of the suede sensor can be well preserved after 60 min of machine washing and ultrasonic cleaning, highlighting its potential in practical applications. This study provides an environmentally stable, lightweight, and well-structured substrate for high-performance electronic textiles suitable for large-scale production.

Evaluation paste removal method and bond strength between resin cement and lithium disilicate ceramic: An in vitro study

Statement of problemAfter the use of evaluation paste, residue can remain on the bonding surface. However, how adhesion to lithium disilicate ceramic is affected is unclear. PurposeThe purpose of this in vitro study was to determine the effectiveness of lithium disilicate cleaning after contamination with an evaluation paste and before the application of a resin cement. Material and methodsRectangular lithium disilicate (IPS e.max CAD) specimens were obtained with a simulated milled surface, crystallized, etched with 5% hydrofluoric (HF) acid, and contaminated with an evaluation paste. The cleaning methods tested were air-water spray (SPRAY), 37% phosphoric acid (HPO), ultrasonic bath (ULT), cleaning paste (IVOC), and a conventional surface treatment (HF + silane–HF+SIL). The control (CTRL) group was not contaminated. After silane had been applied, resin cement cylinders were fabricated and light polymerized. Half of the cylinders (n=56) were tested for microshear bond strength at baseline (24 hours), and the other half after 210 days of water storage and 25 000 thermal cycles. Surface roughness, failure analysis, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were performed. Statistical analysis was performed with the Kruskal-Wallis and Mann-Whitney tests for surface roughness and the 2-way ANOVA and Bonferroni post hoc tests for bond strength (α=.05). ResultsAt baseline, only SPRAY did not restore the bond strength compared with CTRL. After aging, the bond strengths of SPRAY and IVOC were lower than of CTRL (P<.05); no significant difference was found between CTRL, HPO, ULT, and HF+SIL (P>.05). EDS demonstrated the presence of carbon in the SPRAY and ULT groups, probably remnants of the evaluation paste. SEM analysis identified such remnants in the SPRAY group only. ConclusionsFor optimal bond strength between lithium disilicate and resin cement after evaluation paste use, cleaning the ceramic surface with 37% phosphoric acid, ultrasonic bath, or with hydrofluoric acid worked best.

Skim coconut milk processing by thermal- and ultrasonic-thermal pasteurization

The coconut industry in Indonesia is significant for national income, with the potential for value-added products that could enhance the industry’s expansion. Skim coconut milk, a by-product of virgin coconut oil production, is a healthy substitute for dairy milk that can be consumed by people with lactose intolerance. The low-fat and high-protein content of skim coconut milk makes it a healthier alternative to regular coconut milk and cow milk. This study compares ultrasonic-assisted pasteurization of skim coconut milk to conventional pasteurization technique in terms of contamination reduction efficacy and energy efficiency with minimum product characteristic change. The process consisted of thawing frozen skim coconut milk, homogenization of liquid skim coconut milk and pasteurization in a shaking water bath or ultrasonic bath. Total cell counting was conducted, D-value and z-value were estimated to measure the effectiveness of pasteurization in reducing the number of harmful microorganisms in skim coconut milk. The study found that ultrasonic-assisted pasteurization reduced the number of microorganisms more effectively than conventional pasteurization with a lower energy consumption. The study showed the removal efficiency of ultrasonic-assisted pasteurization and conventional pasteurization at 70°C and 15 minutes were 28.74% and 12.33%, respectively. At that condition, energy consumption for every microbial cell being removed was approximately 3 times lower in ultrasonic-assisted pasteurization than the conventional one (0.13 kWh vs. 0.36 kWh). Skim coconut milk processed by ultrasonic-assisted pasteurization at 75°C for 15 minutes featured homogeneous white liquid with shelf time of 11.2 h, which was 2.65 times longer than the unprocessed coconut skim milk. The research suggests that ultrasonic-assisted pasteurization can be a feasible and sustainable processing technology for skim coconut milk, with potential commercial value for small companies and farmers in Indonesia.

Biocompatibility, Surface Morphology, and Bacterial Load of Dental Implant Abutments following Decontamination Protocols: An In-Vitro Study.

The long-term success of dental implant rehabilitation depends significantly on proper peri-implant soft tissue integration. Therefore, decontamination of abutments prior to their connection to the implant is beneficial to enhance soft tissue attachment and to aid in maintaining marginal bone around the implant. Consequently, different implant abutment decontamination protocols were evaluated regarding biocompatibility, surface morphology, and bacterial load. The protocols evaluated were autoclave sterilization, ultrasonic washing, steam cleaning, chlorhexidine chemical decontamination, and sodium hypochlorite chemical decontamination. The control groups included: (1) implant abutments prepared and polished in a dental lab without decontamination and (2) unprepared implant abutments obtained directly from the company. Surface analysis was performed using scanning electron microscopy (SEM). Biocompatibility was evaluated using XTT cell viability and proliferation assays. Biofilm biomass and viable counts (CFU/mL) (n = 5 for each test) were used for surface bacterial load evaluation. Surface analysis revealed areas of debris and accumulation of materials, such as iron, cobalt, chromium, and other metals, in all abutments prepared by the lab and with all decontamination protocols. Steam cleaning was the most efficient method for reducing contamination. Chlorhexidine and sodium hypochlorite left residual materials on the abutments. XTT results showed that the chlorhexidine group (M = 0.7005, SD = 0.2995) had the lowest values (p < 0.001) (autoclave: M = 3.6354, SD = 0.1510; ultrasonic: M = 3.4077, SD = 0.3730; steam: M = 3.2903, SD = 0.2172; NaOCl: M = 3.5377, SD = 0.0927; prep non-decont.: M = 3.4815, SD = 0.2326; factory: M = 3.6173, SD = 0.0392). Bacterial growth (CFU/mL) was high in the abutments treated with steam cleaning and ultrasonic bath: 2.93 × 109, SD = 1.68 × 1012 and 1.83 × 109, SD = 3.95 × 1010, respectively. Abutments treated with chlorhexidine showed higher toxicity to cells, while all other samples showed similar effects to the control. In conclusion, steam cleaning seemed to be the most efficient method for reducing debris and metallic contamination. Bacterial load can be reduced using autoclaving, chlorhexidine, and NaOCl.

Evaluation of cleaning process efficacy of instruments for robotic surgery using the adenosine triphosphate test

BackgroundDespite the advances in robotic surgery and its benefits for the patient and surgeon, there are difficulties and challenges in reprocessing surgical instruments, including with regard to patient safety, such as the risk of infection. The aim of this article is to evaluate the effectiveness of manual plus ultrasonic cleaning of EndoWrist devices used in robotic surgery using the adenosine triphosphate bioluminescence quantitative test. MethodsA prospective cross-sectional study assessed the cleanliness of robotic instrumentals used in surgeries. Surgical instruments were collected immediately after the end of the surgery and sent for cleaning and disinfection following standard hospital procedures. The adenosine triphosphate test was done after visual evaluation. According to our hospital standard, instruments were classified as “approved” if the test found ≤50 relative light units. FindingsWe evaluated 279 EndoWrist instruments from 65 robotic surgeries. The most frequently used instruments were needle drivers (102; 39%), followed by bipolar instruments (65; 25%). Median relative light units were 49 (range = 4–13,095); 54% of instruments were classified as approved according to the hospital’s threshold (relative light units ≤50) and 78% when the manufacturer’s threshold (relative light units ≤150) was used. Monopolar instruments presented the best rate of approval (94% considering relative light units ≤50 and 100% with relative light units ≤150). The average relative light units did not vary with the number of reuses. There were no surgical site infections. ConclusionManual plus automated cleaning processes reduced bioburden in all situations evaluated. It seems that instruments can be safely reprocessed ≤9 times and that monopolar instruments are the easiest to clean.

Universal scaling of droplet retraction dynamics on vibrating surfaces

Over the past decade, extensive efforts have been made in the study of droplet impact, especially on stationary surfaces, owing to its direct applications in thermal cooling, self-cleaning, and power generation. However, many practical applications, such as ultrasonic cleaning, aerosolized drug delivery, and vibration-assisted welding, involve the direct interaction of droplets with vibrating surfaces, on which droplets undergo spreading and retraction. Distinct from stationary surfaces where the retraction behaviors, such as the retraction velocity and rate, are mainly governed by the surface wettability and droplet inertia, the retraction behaviors on vibrating surfaces become complicated due to the vibration velocity, which dictates the outcomes of droplet impact, such as the pinning, bouncing, gyrating, and jetting. Here, we revealed the synergistic effect of droplet inertia and vibration velocity on droplet retraction. We found that the droplet retraction behaviors on both stationary and vibrating surfaces could be characterized by a universal scaling law, allowing us to analyze and predict the maximum droplet retraction velocities. Moreover, we found that the maximum retraction rate increased with the maximum spreading radius at low Weber numbers. We demonstrated that the droplet retraction dynamics at both low Weber numbers and high Weber numbers could be unified into one integrated model, which indicates the decisive role of the maximum droplet spreading in droplet retraction dynamics.

Acoustic power dependent detachment of PSL particles adhered to glass surfaces by dissolved gas and anionic surfactant in an ultrasonic field

While numerous cleaning techniques have been proposed for the semiconductor cleaning process, the ultrasonic cleaning method has become an increasingly adopted technique that removes contaminated particles from semiconductor devices. Till date, little attention has been given to understand the role of surfactant and dissolved gas on the dynamics of cavitation bubbles at different ultrasonic powers. In this study, we propose a mechanism for the influence of SDS (sodium dodecyl sulfate) and dissolved H2 gas in deionized water (DIW) on the removal of PSL particles at different ultrasonic powers by evaluating the particle removal efficiency (PRE) via high-speed videography. It was observed that at US (ultrasonic) powers of 12 and 16 W, the PRE reached a maximum value at a SDS surfactant concentration of 20 ppm and then drastically decreased with increasing surfactant concentration. However, H2 gas dissolved DIW shows a high PRE compared to DIW at US powers of 4–16 W. Furthermore, the PRE reached a maximum value at 20 ppm SDS in a H2-DIW solution and then decreased with increasing surfactant concentration up to 100 ppm. However, the PRE decreased slightly with increasing SDS surfactant concentration when dissolved in H2-DIW. It was revealed that the US power and concentration of SDS significantly influence the removal of PSL particles. Furthermore, the size, cluster, population, and dynamic characteristics of bubbles affected the PRE differently in the presence of SDS and H2 gas. Our present research demonstrates a different approach towards the development of a more feasible ultrasonic cleaning process.

3D printed triboelectric nanogenerator for underwater ultrasonic sensing

The underwater ultrasound power measurement has become necessary due to the rapid development of sonochemistry and sonocatalysis. This article presents construction of novel triboelectric nanogenerator (TENG) and its application for a detection of ultrasonic waves in water. The device was 3D printed using widely available and cost-effective materials. TENG consisted of the device housing and movable polymer pellets confined between flat electrodes. The device housing and pellets were 3D printed via stereolithography (SLA) and fused deposition modelling (FDM) methods, respectively. The pellets moved periodically driven by the ultrasonic waves leading to generation of an alternating voltage signal. The electric response of TENG was calibrated using a commercially available ultrasonic power sensor. The open-circuit voltage output of TENG was registered in different sections of the ultrasonic bath in order to determine the distribution of the acoustic power. TENG electric responses were analyzed by applying the fast Fourier transform (FFT) and fitting the theoretical dependence to experimental data. The main peaks in the frequency spectra of the voltage waveforms corresponded to the fundamental excitation frequency of the ultrasonic bath. TENG device, presented in this paper, can be successfully applied as a self-powered sensor for detection of ultrasonic waves. It enables precise control of the sonochemical process and reduction of power losses of the ultrasonic reactor. 3D printing technology has been confirmed to be fast, easy, and scalable method of fabrication of the ultrasonic sensors.

Liquid‐Metal‐Assisted Programmed Galvanic Engineering of Core–shell Nanohybrids for Microwave Absorption

AbstractCore–shell nanostructures have received widespread attention because of their potential usage in various technological and scientific fields. However, they still face significant challenges in terms of fabrication of core–shell nanostructure libraries on a controlled, and even programmed scale. This study proposes a general approach to systematically fabricate core–shell nanohybrids using liquid‐metal Ga alloys as reconfigurable templates, and the initiation of a local galvanic replacement reaction is demonstrated utilizing an ultrasonic system. Under ultrasonic agitation, the hydrated gallium oxides generated on the liquid metal droplets, simultaneously delaminated themselves from the interfaces. Subsequently, single‐metal or bimetallic components are deposited on fresh smooth Ga‐based alloys via galvanic reactions to form unique core–shell metal/metal nanohybrids. Controlled and quantitative regulation of the diversity of the non‐homogeneous nanoparticle shell layer composition is achieved. The obtained core–shell nanostructures are used as efficient microwave absorbers to dissipate unwanted electromagnetic wave pollution. The effective absorption bands (90% absorption) of core–shell GaNi and GaCoNi nanohybrids are 3.92 and 3.8 GHz at a thickness of 1.4 mm, respectively. This general and advanced strategy enables the growth of other oxides or sulfides by spontaneous interfacial redox reactions for the fabrication of functional materials in the future.