Ultrasound Power Density Research Articles

Flow effects on sonochemical oxidation activity in a 20 kHz ultrasonic horn system

Forced fluid flow, when properly aligned with the geometry of a 20 kHz horn-type sonoreactor, can increase its sonochemical efficiency (SE). We designed a flow-through reactor configuration to evaluate the effect of fluid dynamics on sonochemical activity. Using particle image velocimetry (PIV), we mapped the velocity profiles within the sonoreactor under flow rates up to 350 ml/min, and ultrasound power density from 142 to 498 W/L. KI dosimetry and sonochemiluminescence (SCL) are conducted to correlate fluid motion with chemical activity.At an ultrasound power density below 241 W/L, placing the probe near the water surface with a 288 ml/min flow rate maximized radical generation. Conversely, above 402 W/L, maximum SE is achieved with the probe near the vessel’s bottom at the same flow rate. At power densities below 241 W/L, external flow increases the liquid residence time in acoustically active zones from 0.16 to an average of 6.3 s, yielding enhanced chemical activity. Above 402 W/L, the introduction of forced flow broadens the acoustic jet, relocating bubbles from the active zone below the probe’s tip to the area around its neck. The expansion of this active zone leads to increased SE.A significant discrepancy is noted between Electron Paramagnetic Resonance (EPR) and KI dosimetry in measuring hydroxyl (OH.) radical concentrations. EPR suggests that most of these radicals are lost to recombination, highlighting the rapid dynamics of radical generation and recombination into hydrogen peroxide (H2O2) at interfacial regions.

Predicting Calcein Release from Ultrasound-Targeted Liposomes: A Comparative Analysis of Random Forest and Support Vector Machine.

This study presents a comparative analysis of RF and SVM for predicting calcein release from ultrasound-triggered, targeted liposomes under varied low-frequency ultrasound (LFUS) power densities (6.2, 9, and 10 mW/cm2). Liposomes loaded with calcein and targeted with seven different moieties (cRGD, estrone, folate, Herceptin, hyaluronic acid, lactobionic acid, and transferrin) were synthesized using the thin-film hydration method. The liposomes were characterized using Dynamic Light Scattering and Bicinchoninic Acid assays. Extensive data collection and preprocessing were performed. RF and SVM models were trained and evaluated using mean absolute error (MAE), mean squared error (MSE), coefficient of determination (R²), and the a20 index as performance metrics. RF consistently outperformed SVM, achieving R2 scores above 0.96 across all power densities, particularly excelling at higher power densities and indicating a strong correlation with the actual data. RF outperforms SVM in drug release prediction, though both show strengths and apply based on specific prediction needs.

Hexagonal plate ultrasound pretreatment on the correlation between soy protein isolate structure and cholesterol-lowering activity of peptides, and protein's enzymolysis kinetics, thermodynamics

In this study, a hexagonal plate ultrasound (HPU) pretreatment technology was employed to modify soy protein isolate (SPI) and enhance the hypocholesterolemic activity of enzymatic digests from SPI. Results demonstrated that under the condition of ultrasound power density of 40 W/L, the hypocholesterolemic activity of enzymatic digests from HPU-pretreated SPI (HPU-SPI) increased by 88.40 % compared to control group after gastrointestinal digestion. The sulfhydryl content of HPU-SPI increased by a maximum of 45.32 % compared to control group. Fourier transform infrared and scanning electron microscopy revealed that HPU pretreatment partially unfolded the SPI conformation, reduced the intermolecular interactions, and exposed the internal hydrophobic regions. Pearson correlation analysis showed that sulfhydryl groups (r = 0.860), disulfide bonds (r = −0.875) and random coil (r = 0.917) were strongly correlated with the cholesterol-lowering activity of soy protein hydrolysate (SPH), following a simulated gastrointestinal digestion. Finally, the effects of HPU pretreatment on enzymolysis kinetics and thermodynamics of the SPI enzymatic process showed that HPU pretreatment significantly reduced the Mie's constant, activation energy, activation enthalpy, activation entropy and Gibbs free energy. Overall, the study outcome suggested that HPU pretreatment could positively influence the hypocholesterolemic peptide activity, and thus, may be beneficial to the pharmaceutical/food industry.

Interaction mechanisms of peanut protein isolate and high methoxyl pectin with ultrasound treatment: The effect of ultrasound parameters, biopolymer ratio, and pH.

Ultrasound could effectively change molecular structure of proteins, polysaccharides, and their interactions, and was used to treat the peanut protein isolate-high methoxy pectin (PPI-HMP) complexes in this study. Effects of different ultrasound parameters, PPI-HMP mixing ratio (40:1-5:2), and pH (2.0-8.0) on the PPI-HMP interactions were investigated. Turbidity, solution appearance, and Zeta-potential analysis revealed an electrostatic interaction between PPI and HMP from pH 2.0 to pH 6.0. Ultrasound changed the tertiary structure conformation of PPI according to the surface hydrophobicity analysis. Increased ultrasound power density and pH broke the hydrogen bonds between the complexes according to Fourier transform infrared spectroscopy analysis. Apparent viscosity and confocal laser scanning microscopy analysis showed that appropriate ultrasound treatment (5.43W/cm3, 25min, 25°C) reduced the viscosity of the complexes, and enhanced the electrostatic and hydrophobic interactions between PPI and HMP. These findings will contribute to the application of PPI-HMP complexes in the food industry.

Color-Changing Reflection Hologram for Quality Assurance of Therapeutic Ultrasound Systems.

The acoustic output of clinical therapeutic ultrasound equipment requires regular quality assurance (QA) testing to ensure the safety and efficacy of the treatment and that any potentially harmful deviations from the expected output power density are detected as soon as possible. A hologram, consisting of a reflection grating fabricated in an acrylate photopolymer film, has been developed to produce an immediate, visible, and permanent change in the color of the reconstructed hologram from red to green in response to incident ultrasound energy. The influence of the therapeutic ultrasound insonation parameters (exposure time, ultrasound power density, and proximity to the point of maximum acoustic pressure) on the hologram's response has been investigated for two types of therapeutic ultrasound systems: a sonoporation system and an ultrasound physiotherapy system. Findings show that, above a switching temperature of 45 °C, the ultrasound-induced temperature rise produces a structural change in the hologram, which manifests as a visible color change. The area of the color change region correlates with the ultrasound exposure conditions. The suitability of the hologram as a simple and quick QA test tool for therapeutic ultrasound systems has been demonstrated. A prototype ultrasound testing unit which facilitates user-friendly, reproducible testing of the holograms in a clinical setting is also reported.

Influence of cerebrospinal fluid on power absorption during transcranial magnetic resonance-guided focused ultrasound treatment.

Ultrasound beam aberration correction is vital when focusing ultrasound through the skull bone in transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) applications. Current methods make transducer element phase adjustments to compensate for the variation in skull properties (shape, thickness, and acoustic properties), but do not account for variations in the internal brain anatomy. Our objective is to investigate the effect of cerebrospinal fluid (CSF) and brain anatomy on beam focusing in tcMRgFUS treatments. Simulations were conducted with imaging data from 20 patients previously treated with focused ultrasound for disabling tremor. The Hybrid Angular Spectrum (HAS) method was used to test the effect of including cerebral spinal fluid (CSF) and brain anatomy in determining the element phases used for aberration correction and beam focusing. Computer tomography (CT) and magnetic resonance imaging (MRI) images from patient treatments were used to construct a segmented model of each patient's head. The segmented model for treatment simulation consisted of water, skin, fat, brain, CSF, diploë, and cortical bone. Transducer element phases used for treatment simulation were determined using time reversal from the desired focus, generating a set of phases assuming a homogeneous brain in the intracranial volume, and a second set of phases assigning CSF acoustic properties to regions of CSF. In addition, for three patients, the relative effect of separately including CSF speed of sound values compared to CSF attenuation values was found. We found that including CSF acoustic properties (speed of sound and attenuation) during phase planning compared to phase correction without considering CSF increased the absorbed ultrasound power density ratios at the focus over a range of 1.06 to 1.29 (mean of 17%±6%) for 20 patients. Separately considering the CSF speed of sound and CSF attenuation showed that the increase was due almost entirely to including the CSF speed of sound; considering only the CSF attenuation had a negligible effect. Based on HAS simulations, treatment planning phase determination using morphologically realistic CSF and brain anatomy yielded an increase of up to 29% in the ultrasound focal absorbed power density. Future work will be required to validate the CSF simulations.

An Ultrasonically-Powered System for 1.06mm3 Implantable Optogenetics and Drug Delivery Dust

This paper presents an ultrasonically powered micro-system for deep tissue optogenetic stimulation. The developed system is composed of a Base for Powering and Controlling (BPC) and an implantable Dust for optogenetics and drug delivery. The Dust consists of a piezoelectric crystal, a rectifier chip, and a micro-scale custom-designed light-emitting-diode (μLED) integrated, miniaturized, and envisioned to be used for freely moving animal studies. The proposed Dust operates in frequencies up to 5 MHz, power levels in the 0–10 mW range, achieves start-up within 1.8 μs at 2.9 MHz operating frequency at 14.4 mW/mm2 ultrasound power density, and 98.1% chip efficiency at 2 mW input power. With the BPC implemented and attached to (500 μm)3 PZT4 crystals, set to 60 V at 2.8 MHz operating frequency at 3 mm distance in demineralized water, the dust delivered up to 6 mW to its load (μLED for optogenetics), which translates to 0.11% total system efficiency.

Removal of drug dexamethasone from aqueous matrices using low frequency ultrasound: Kinetics, transformation products, and effect of microplastics

Sonochemical oxidation was employed for the degradation of the drug dexamethasone (Dex). The oxidation at 20 kHz followed pseudo-first-order kinetics and increased with applied ultrasound power density. Acoustic cavitation at 71 W/L was able to eliminate 500 μg/L of dexamethasone from ultrapure water at inherent pH in less than 60 min. The oxidation was enhanced at pH 3 and decreased at increased Dex concentration. Scavenging experiments with tert-butanol showed that hydroxyl radicals play a crucial role in decomposition, where the reaction mainly occurs on the gas-liquid interface of the formed cavities. The addition of chloride did not affect Dex removal, while in the presence of 10 mg/L of humic acid or bicarbonate, the apparent kinetic constant decreased from 0.0423 ± 0.004 min−1 to about 0.03 ± 0.002 min−1. The rate in secondary effluent was 3.3 times lower than in ultrapure water due to the complexity of the actual matrix. Six transformation products were identified via high resolution LC-MS during the sonochemical oxidation of 3 mg/L Dex in ultrapure water. The presence of polyethylene or polystyrene microplastics slightly enhanced DEX sonodegradation. The effect of ultrasound irradiation at 71 W/L for 60 min on the microplastics surfaces was inconsiderable.

Combined use of microbubbles of various sizes and single-transducer dual-frequency ultrasound for safe and efficient inner ear drug delivery.

We have previously applied ultrasound (US) with microbubbles (MBs) to enhance inner ear drug delivery, with most experiments conducted using single-frequency, high-power density US, and multiple treatments. In the present study, the treatment efficacy was enhanced and safety concerns were addressed using a combination of low-power-density, single-transducer, dual-frequency US (I SPTA= 213 mW/cm2) and MBs of different sizes coated with insulin-like growth factor 1 (IGF-1). This study is the first to investigate the drug-coating capacity of human serum albumin (HSA) MBs of different particle sizes and their drug delivery efficiency. The concentration of HSA was adjusted to produce different MB sizes. The drug-coating efficiency was significantly higher for large-sized MBs than for smaller MBs. In vitro Franz diffusion experiments showed that the combination of dual-frequency US and large MB size delivered the most IGF-1 (24.3± 0.47 ng/cm2) to the receptor side at the second hour of treatment. In an in vivo guinea pig experiment, the efficiency of IGF-1 delivery into the inner ear was 15.9 times greater in animals treated with the combination of dual-frequency US and large MBs (D-USMB) than in control animals treated with round window soaking (RWS). The IGF-1 delivery efficiency was 10.15 times greater with the combination of single-frequency US and large size MBs (S-USMB) than with RWS. Confocal microscopy of the cochlea showed a stronger distribution of IGF-1 in the basal turn in the D-USMB and S-USMB groups than in the RWS group. In the second and third turns, the D-USMB group showed the greatest IGF-1 distribution. Hearing assessments revealed no significant differences among the D-USMB, S-USMB, and RWS groups. In conclusion, the combination of single-transducer dual-frequency US and suitably sized MBs can significantly reduce US power density while enhancing the delivery of large molecular weight drugs, such as IGF-1, to the inner ear.

Scaling up continuous ultrasound-assisted extractor for plant extracts by using spinach leaves as a test material

The ultrasound-assisted extraction (UAE) process of chlorophylls (a, b) and carotenoids in aqueous ethanol solutions from spinach leaves was upscaled from a batch laboratory reactor to a continuous modular flow-cell of pilot scale. The extraction in the laboratory scale was organized in a loop reactor, where pulp was circulated between a stirred vessel and the ultrasound reactor. The pilot scale extraction was made in a novel continuous tubular flow-cell reactor. The analysis of the experimental data proved that the ultrasound application provided a better extraction yield. In the laboratory scale, the application of ultrasound (24 kHz and 2500 W/L) showed the 2.6-fold higher maximum extraction yield compared to non-sonicated conventional solvent extraction. In the pilot scale, the effect was less significant (1.9-fold), due to smaller ultrasound power density (25 kHz and 1500 W/L). The scale-up of the UAE was based on equal extraction yield at both scales. The scale-up revealed that 2.5-fold higher volume-specific ultrasound power is required in the pilot scale to reach the yield obtained in the laboratory scale reactor.

Multi-mode S-type ultrasound-assisted protein extraction from walnut dregs and in situ real-time process monitoring

This study aimed to investigate the impact of multi-mode S-type ultrasound treatment on the protein extraction level of walnut dregs. The structural properties of the walnut protein (WP) were characterized, and the correlation between protein structure and extraction level was analyzed. The in situ real-time monitoring model for the ultrasound-assisted WP extraction process was established by a miniature fiber near-infrared (NIR) spectrometer. Results showed that the protein yield, purity, and comprehensive extraction index (CEI) of extracted WP were 71.07 %, 72.69 %, and 71.72, respectively, under optimal conditions (dual-frequency 20/28 kHz, ultrasonic treatment duration 30 min, and ultrasound power density 120 W/L). The secondary structure of extracted WP displayed that the proportion of α-helix and β-sheet reduced, while the contents of β-turn and random coil increased after ultrasonic treatment. Besides, sonication decreased the disulfide bond content and increased free sulfhydryl (-SH) and surface hydrophobicity compared to the control. The microstructures of WP confirmed that appropriate sonication could unfold the protein aggregates and reduce the particle size. The extraction level of WP is positively correlated with the -SH content (p < 0.01). The quantitative prediction model of Si-PLS for -SH content in the ultrasound-assisted WP extraction process was established and performed a good correction and prediction performance (Rc = 0.9736; RMSECV = 0.446 μmol/L; Rp = 0.9342; RMSEP = 0.807 μmol/L). This study exploited a high-efficiency way for the WP extraction industry, and provided theoretical support for the development of the intelligent system in industrial protein extraction process.

Enhanced remediation of a real HCH-polluted soil by the synergetic alkaline and ultrasonic activation of persulfate

The desorption of hydrophobic organic compounds (HOCs) and limited mass transfer in soil systems is a significant challenge for efficient soil remediation by oxidation treatments. The utilization of sonochemistry is a promising technology to enhance the decontamination of HOCs-polluted soils. In this work, ultrasound (US) was coupled to NaOH for activating persulfate (PS) to enhance the remediation of a real soil polluted with hexachlorocyclohexanes (HCHs) (ΣHCHs = 404 mg kg−1).Batch experiments (mass aqueous/soil ratio, VL/WS = 2) were performed to evaluate the effect of US on HOCs desorption and oxidation. Moreover, the influence of US power (0–245 W, corresponding to 0–91 W L-1 of US power density) and the initial oxidant concentration (CPS = 10–60 g L-1) on pollutants abatement, dechlorination degree, and oxidant consumption have been studied. Scanning electron microscopy (SEM) images verified that the US facilitates the breakdown of soil aggregates, enhancing the desorption of trichlorobenzenes (TCBs) (generated from HCHs alkaline hydrolysis) from the soil. Moreover, their subsequent oxidation is favouring because of higher radical species concentrations and the temperature rise. An increase in the US power up to 165 W accelerates the production rate of radicals, improving the pollutants’ degradation. The difference between pollutant oxidation and dechlorination decreases with increasing US power, associated with a lower concentration of intermediate chlorinated compounds. In the same way, the initial oxidant concentration plays a fundamental role in the remediation treatment. At the selected operating conditions (CPS = 60 g L-1, NaOH/PS = 2, 165 W), a pollutants degradation and dechlorination of 0.94 and 0.74, respectively, were achieved in just 3 h of reaction time.

Enhancing the Efficacy of Microwave Blanching-cum-black Mould Inactivation of Whole Garlic (Allium sativum L.) Bulbs Using Ultrasound: Higher Inactivation of Peroxidase, Polyphenol Oxidase, and Aspergillus niger at Lower Processing Temperatures.

The freshly harvested whole garlic bulbs require the inactivation of peroxidase (POD), polyphenol oxidase (PPO), and Aspergillus niger. However, the conventional hot water blanching and modern pretreatment like ultrasound (US) and microwave (MW) cannot individually inactivate both the enzymes and Aspergillus niger to the desired levels without compromising the quality of the garlic due to either of the higher process temperatures (> 85 °C) or prolonged treatment times. Therefore, a two-stage sequential US followed by MW pretreatment for garlic bulbs was developed for simultaneous inactivation of POD, PPO, and Aspergillus niger to the desired levels and overcome the individual pretreatment drawbacks. The separate experiments were conducted for US and MW pretreatment using central composite design, and optimization was carried out using response surface methodology. When temperature constraint was considered during optimization, the US was able to reduce POD, PPO, and Aspergillus niger by 80.87%, 93.80%, and 2.60 logs, respectively, whereas MW reduced POD, PPO, and Aspergillus niger by 77.84%, 77.04%, and 1.90 logs, respectively. The US treatment (58.43 WL−1 ultrasound power density for 40 min with an initial bath temperature of 60 °C) followed by MW treatment (3 Wg−1 MW power density for 120 s) resulted in 90.37% POD and 92.38% PPO inactivation with 2.62 log reduction in Aspergillus niger. The maximum temperature reached in US + MW process was 83 °C which ensured no severe thermal damage to the garlic bulbs. The scanning electron microscopic images indicated that ultrasonication induced the porous structure in garlic and helped microwaves increase the product temperature rapidly and achieve the higher inactivation of enzymes and Aspergillus niger. Thus, the US was found to be enhancing the efficacy of the MW heating process.

Power Ultrasound-Assisted Impregnation of Apple Cubes with Vitamin B12

This work explores the use of ultrasound (US) as a means of intensifying the impregnation of apple cubes with vitamin B12 (cyanocobalamin). The effect of different US power densities (90 and 200 WL−1) and treatment times (5, 10, and 15 min) was evaluated, on vitamin load, vitamin stability, and physicochemical and microstructural properties of the fruit matrix. The US enhanced the impregnation producing high cyanocobalamin content products (0.12–0.19 mg vitamin/g db.). Vitamin losses in the sonication medium due to US application were not significant. Impregnated samples exhibited higher moisture and lower soluble solids with respect to the untreated fruit. Changes in chromatic coordinates were well correlated to vitamin uptake. Only at the highest treatment intensities (200 WL−1, 10, and 15 min) was a marked softening observed, which agreed with the microstructural changes observed in fruit tissues. Results permit US-assisted impregnation to be considered a promising technology in the preparation of vitamin B12 fortified apple cubes.

Wireless electrical stimulation of the vagus nerves by ultrasound-responsive programmable hydrogel nanogenerators for anti-inflammatory therapy in sepsis

Electroceuticals based on electrical stimulation of the vagus nerves shows great promise for therapeutic application in a variety of diseases and clinical conditions. The exploration of new generation neurostimulators with programmable, battery-free, and minimally invasive features is an emerging research field. Herein, we present wireless-powered battery-free vagus nerves stimulators based on implantable high-performance hydrogel nanogenerators (HENG) which can be driven by programmable ultrasound pluses remotely, and demonstrate the successful application of HENG in vagus nerves stimulation for the anti-inflammatory therapy in sepsis. The HENG is developed on the basis of polyacrylamide/graphene conductive hydrogels as a new kind of liquid-based triboelectric nanogenerators. With the device size of 1.5 cm × 1.5 cm × 1 mm and the ultrasound power density of 0.3 W/cm2, the short-circuit current generated by the HENG is measured to be 1.6 mA, which is comparable to the output current of commercial bulky neurostimulators. With the systemic inflammatory produced by endotoxin as a model, the alternating current pulse stimulation of the vagus nerves by the ultrasound-responsive HENG shows great effectiveness in the inhibition of pro-inflammatory cytokines. This work provides a novel strategy for the development of implantable soft high-performance nanogenerators as programmable battery-free neurostimulators for wireless electrical stimulation of the nerve systems.

On line continuous chemical synthesis of ferrate(VI): Enhanced yield and removal of pollutants

This paper presents a new process to synthesize ferrate(VI) (FeVIO4−2) continuously through the oxidation of ferric ion (Fe3+) by hypochlorite (OCl-) under alkaline condition. Synthesis was performed under different experimental conditions ([OH-] = 5.0 – 16.0 M, and T = 20 – 45 °C) to obtain optimum yield of ferrate(VI). Under the most favorable condition (i.e., ([Fe3+] = 0.10 M, [OCl-]: [Fe3+] = 10.0, [OH-] = 10.0 M, and T = 40 °C), the yield of ferrate(VI) in the newly designed reactor increased by about 11% in 60 min compared to conventional reactor (or increased in [FeO42-] from 4.0 × 10−2 M to 4.5 × 10−2 M). The rapid mixing under flow condition in the closed coil of the new reactor improved the reaction efficiency and yield. When [Fe3+] was varied in the range from 0.10 to 0.20 M in the reactor under the same condition, the optimum concentration of Fe3+ was at 0.16 M, which increased the concentration of FeO42- to 6.8 × 10−2 M. Applying ultrasound power density (5.0–25.0 W/L) in the reaction process further increased the yield by about 12% (or increased [FeO42-] from 6.8 × 10−2 M without ultrasound to 7.6 × 10−2 M at 15.0 W/L). Overall, operating the newly designed reactor under ultrasound could increase the concentration of synthesized ferrate(VI) from 4.0 × 10−2 M to 7.6 × 10−2 M. At pH 7.0, the prepared ferrate(VI) completely removed atrazine (ATZ), sulfachloropyridazine (SCP), ibuprofen (IBP), and naproxen (NAP)) in water.

Production of tung oil epoxy resin using low frequency high power ultrasound

Epoxy resins made from vegetable oils are an alternative to synthesize epoxy resins from renewable sources. Tung oil is rich in α -eleostearic fatty acid, which contains three double bonds producing epoxy resins with up to three epoxy groups per fatty acid. This work studied the production of tung oil epoxy resin using hydrogen peroxide as an oxidizing agent and acetic and formic acid as percarboxylic acid precursors, applying low frequency high power ultrasound. This study evaluated the effects of ultrasound power density, hydrogen peroxide concentration, acetic acid concentration, and formic acid concentration on the yield into epoxy resin, selectivity, and by-products formation. Application of ultrasound was carried out using a 19 kHz probe ultrasound (horn ultrasound) with a 1.3 cm diameter titanium probe, 500 W nominal power, 2940 W L−1 maximum effective power density applied to the reaction mixture. Ultrasound technology yielded up to 85% of epoxy resin in 3 h of reaction. The use of formic acid resulted in a slightly lower oil conversion than acetic acid but with a much higher selectivity towards epoxidized tung oil. However, using acetic acid resulted in the production of high-value by-products, such as 2-heptenal and 2,4-nonadienal. The ultrasound-assisted epoxidation showed to be particularly efficient when applied to oils containing conjugated double-bonds.

Roles of free radical on the formation of acetaldehyde in model wine solutions under different ultrasound parameters: A key bridge-link compound for red wine coloration during ageing

In order to explore the effects of ultrasound on the formation of acetaldehyde and its mechanism in model wine solutions, ultrasound conditions and free radicals were investigated by response surface methodology and electron paramagnetic resonance spectroscopy (EPR), respectively. The results indicate that ultrasound does induce the production of acetaldehyde with the maximum amount under the conditions of ultrasound power density 0.2 W/cm2, 48 min and 32 °C. The hydroxyl radicals and the 1-hydroxyethyl free radicals are the main initiator and precursor for acetaldehyde, respectively. Furthermore, the stronger the 1-hydroxyethyl free radicals captured by EPR, the lower the formation of acetaldehyde. In addition, the content of Fe2+and ethanol also exerted a certain influence on the acetaldehyde formation. In conclusion, ultrasound does promote the production of acetaldehyde in the model wine solutions, which is beneficial for well understanding the mechanism of ultrasound in modifying the wine color and accelerating ageing.

Ultrasound-assisted electromembrane extraction with supported semi-liquid membrane

Electromembrane extraction (EME), involving the migration of charged analytes across a supported liquid membrane (SLM) with an external power supply, is a promising sample preparation method in analytical chemistry. However, the presence of boundary double layers at the SLM/solution interfaces often restricts extraction efficiency. To avoid this, the current work proposed an ultrasound-assisted EME (UA-EME) method based on a novel type of supported semi-liquid membrane (SsLM). The characterizations showed that the SsLM was stable under ultrasound conditions. Ultrasound was found to reduce the boundary double layers and thus increase the mass transfer. Major operational parameters in UA-EME including ultrasound power density, temperature, applied voltage and extraction time were optimized with haloperidol, fluoxetine, and sertraline as model analytes. Under the optimal conditions, extraction recoveries of model analytes in water samples were in the range of 66.8%–91.6%. When this UA-EME method was coupled with LC-MS/MS for detection of the target analytes in human urine samples, the linear range of the analytical method was 10–1000 ng mL−1, with R2 > 0.997 for all analytes. The limits of detection (LOD) and limits of quantification (LOQ) were in the range of 1.7–2.1 ng mL−1 and 5.7–6.7 ng mL−1, respectively. The UA-EME expands the application field of ultrasound chemistry and will be very important in development of stable and fast sample preparation systems in the future.

Mathematical Modelling of Ultrasound-Assisted Extraction Kinetics of Bioactive Compounds from Artichoke By-Products.

Valorization of an artichoke by-product, rich in bioactive compounds, by ultrasound-assisted extraction, is proposed. The extraction yield curves of total phenolic content (TPC) and chlorogenic acid content (CAC) in 20% ethanol (v/v) with agitation (100 rpm) and ultrasound (200 and 335 W/L) were determined at 25, 40, and 60 °C. A mathematical model considering simultaneous diffusion and convection is proposed to simulate the extraction curves and to quantify both temperature and ultrasound power density effects in terms of the model parameters variation. The effective diffusion coefficient exhibited temperature dependence (72% increase for TPC from 25 °C to 60 °C), whereas the external mass transfer coefficient and the equilibrium extraction yield depended on both temperature (72% and 90% increases for TPC from 25 to 60 °C) and ultrasound power density (26 and 51% increases for TPC from 0 (agitation) to 335 W/L). The model allowed the accurate curves simulation, the average mean relative error being 5.3 ± 2.6%. Thus, the need of considering two resistances in series to satisfactorily simulate the extraction yield curves could be related to the diffusion of the bioactive compound from inside the vegetable cells toward the intercellular volume and from there, to the liquid phase.