Sonication Intensity Research Articles

Modelling ultrasonic cavitation onset in spiral-wound reverse osmosis modules

A model was developed to predict the onset of inertial cavitation within a spiral-wound reverse osmosis module sonicated along its axis from within its pressure vessel. The aim was to investigate the scalability of ultrasonic antifouling for reverse osmosis applications. The model employs a one-dimensional discretization to represent the module feed channel, calculating each element's pressure, flow rate, permeate flux, and sonication intensity. The Blake threshold assesses whether the pressure amplitude at each element is sufficient to produce inertial cavitation. When applied with parameters from a typical small-scale reverse osmosis module, the model identified a linear relationship between inlet pressure and inertial cavitation onset location, with a constant inlet flow rate and sonication power. With a sonication power of 120 W and a flow rate of 8.796 × 10−5 m3 s−1, the model predicted that inertial cavitation could be induced throughout the reverse osmosis module with inlet pressures ranging from 335 kPa to 355 kPa. While these pressures may be inefficient from a permeate production standpoint compared to standard operating pressure, they could be produced temporarily as part of a regular membrane cleaning operation. The model estimates the system's power consumption during cleaning to be 134.8 W, approximately equal to the estimated system energy requirements under recommended operating conditions of 134.3 W. This suggests that this technology could integrate effectively with existing reverse osmosis systems.

Ultrasonic-Assisted Extraction of Phenolic Compounds from Lonicera similis Flowers at Three Harvest Periods: Comparison of Composition, Characterization, and Antioxidant Activity.

Lonicera similis Hemsl. (L. similis) is a promising industrial crop with flowers rich in phenolic compounds. In this study, an ultrasound-assisted extraction (UAE) was designed to extract phenolic compounds from L. similis flowers (LSFs). A contrastive analysis on the phenolic compounds' yield and characterization and the antioxidant activity of the extracts at three harvest stages (PGS I, PGS II, and PGS III) are reported. The results indicate that the optimal conditions are a sonication intensity of 205.9 W, ethanol concentration of 46.4%, SLR of 1 g: 31.7 mL, and sonication time of 20.1 min. Under these optimized conditions, the TPC values at PGS I, PGS II, and PGS III were 117.22 ± 0.55, 112.73 ± 1.68, and 107.33 ± 1.39 mg GAE/g, respectively, whereas the extract of PGS I had the highest TFC (68.48 ± 2.01 mg RE/g). The HPLC analysis showed that chlorogenic acid, rutin, quercetin, isoquercitrin, and ferulic acid are the main components in the phenolic compounds from LSFs, and their contents are closely corrected with the harvest periods. LSF extracts exhibited a better antioxidant activity, and the activity at PGS I was significantly higher than those at PGS II and PGS III. The correlation analysis showed that kaempferol and ferulic acid, among the eight phenolic compounds, have a significant positive correlation with the antioxidant activity, while the remaining compounds have a negative correlation. Minor differences in extracts at the three harvest stages were found through SEM and FTIR. These findings may provide useful references for the optimal extraction method of phenolic compounds from LSFs at three different harvest periods, which will help to achieve a higher phytochemical yield at the optimal harvest stage (PGS I).

Towards an understanding of the mechanisms of therapeutic ultrasound on biomimetic models of cancer

Therapeutic ultrasound is transforming the treatment of a range of malignancies in a non-invasive and non-systemic manner. Low-intensity ultrasound (LIUS) has been proposed to selectively eradicate cancer cells but the underlying biological mechanisms remains unknown. To gain an understanding of this phenomenon, 2D breast cancer monocultures were sonicated at varying acoustic intensities (0.1–0.5 W·cm−2) and excitation times (1–10 minutes). Additionally, 2D monocultures consisting of healthy cell lines were sonicated at varying acoustic intensities (0.1–0.5 W·cm−2) to determine any distinguishing biological responses. To begin recapitulating in vivo conditions, breast cancer cells were also seeded into 3D collagen hydrogels. At a 1 MHz frequency, 20% duty cycle, 100 Hz pulse repetition frequency, a significant drop in cancer cell viability is observed at a sonication intensity of 0.5 W·cm−2 and over 10 minute excitation time. Healthy counterparts subjected to the same parameters revealed no distinguishing effects. Sonication of breast cancer cells seeded in 3D collagen hydrogels revealed no effect in cell viability compared to non-sonicated controls. The acoustic wave propagation software OptimUS was used to determine the influence culturing plates have on ultrasound propagation, revealing these materials can significantly vary the acoustic field at frequencies relevant to LIUS.

Rheological properties of carboxymethyl cellulose (CMC) solution: Impact of high intensity ultrasound

Today sonication process is used as a new green tool with unique impacts on foods preservation and processing. Ultrasonic modification is an appropriate strategy to obtain good gums with useful physicochemical characteristics and molecular structure. This research aimed to analyze the impacts of sonication at different intensities (0, 75, and 150 W) and time (0, 5, 10, 15, and 20 min) on the viscosity and rheological characteristics of carboxymethyl cellulose (CMC) solution. The results confirmed that the apparent viscosity of CMC solution reduced from 0.030 to 0.021 Pa.s with increasing shear-rate from 12.2 s−1 to 134.5 s−1 (75 W for 10 min). Also, the apparent viscosity of CMC solution reduced from 0.028 to 0.019 Pa.s with enhancing the sonication time from 0 to 20 min (shear-rate = 61 s−1, 150 W). Various rheological equations were employed to fit the empirical values, and the results confirmed that the Power law model was the best fit to explain the flow behaviour of CMC solution. The consistency coefficient of CMC solution significantly reduced from 0.065 Pa.sn to 0.032 Pa.sn (p < 0.05) with enhancing sonication time from 0 to 20 min (75 W). Furthermore, the consistency coefficient of CMC solution decreased significantly (p < 0.05) while the ultrasonic power enhanced. Flow behaviour index of CMC solution enhanced significantly (p < 0.05) while the intensity and time of sonication enhanced.

A transducer positioning method for transcranial focused ultrasound treatment of brain tumors.

As a non-invasive method for brain diseases, transcranial focused ultrasound (tFUS) offers higher spatial precision and regulation depth. Due to the altered path and intensity of sonication penetrating the skull, the focus and intensity in the skull are difficult to determine, making the use of ultrasound therapy for cancer treatment experimental and not widely available. The deficiency can be effectively addressed by numerical simulation methods, which enable the optimization of sonication modulation parameters and the determination of precise transducer positioning. A 3D skull model was established using binarized brain CT images. The selection of the transducer matrix was performed using the radius positioning (RP) method after identifying the intracranial target region. Simulations were performed, encompassing acoustic pressure (AP), acoustic field, and temperature field, in order to provide compelling evidence of the safety of tFUS in sonication-induced thermal effects. It was found that the angle of sonication path to the coronal plane obtained at all precision and frequency models did not exceed 10° and 15° to the transverse plane. The results of thermal effects illustrated that the peak temperatures of tFUS were 43.73°C, which did not reach the point of tissue degeneration. Once positioned, tFUS effectively delivers a Full Width at Half Maximum (FWHM) stimulation that targets tumors with diameters of up to 3.72 mm in a one-off. The original precision model showed an attenuation of 24.47 ± 6.13 mm in length and 2.40 ± 1.42 mm in width for the FWHM of sonication after penetrating the skull. The vector angles of the sonication path in each direction were determined based on the transducer positioning results. It has been suggested that when time is limited for precise transducer positioning, fixing the transducer on the horizontal surface of the target region can also yield positive results for stimulation. This framework used a new transducer localization method to offer a reliable basis for further research and offered new methods for the use of tFUS in brain tumor-related research.

Optimization of sequential ultrasound-microwave assisted extraction of polyphenols-rich concrete from tuberose flowers through modelling

The polyphenols-rich concrete from tuberose flowers can be extracted by sequential ultrasound-microwave assisted extraction (UMAE). However, additional study is required to optimise the processing parameters of sequential UMAE of tuberose concrete. Therefore, in this work, we have focused on establishing the optimal conditions for sequential UMAE of concrete from tuberose flowers using the Response Surface Methodology (RSM) and Artificial Neural Network (ANN) model approach. The impact of different extraction conditions (microwave power (160–800 W), irradiation time (60–300 s), sonication intensity (200–600 W) and sonication time (360−840)) of sequential UMAE on the percent concrete yield from the fresh chopped tuberose flowers were investigated. The percent concrete yield (%), total phenols (mg/g) and antioxidant activity of concrete obtained were 92.28 ± 0.52%, 232.50 ± 0.46 mg/g and 54.48 ± 0.46%, respectively under optimized conditions of sonication power-300 W, microwave power-480 W, irradiation time-2.2 min and sonication time-10 min. The findings suggested that the RSM and ANN models may adequately describe the experimental data. However, ANN prediction is more accurate than the RSM model with a higher coefficient of determination (R2) (0.987 vs. 0.904) and lower mean squared error (1.385 vs. 1.65) and root mean squared error (1.177 vs. 1.284). Gas chromatography-mass spectrometry analyzed that the tuberose concrete was rich in benzyl benzoate (14.5%), trans-Farnesol (11.02%), indole (8.52%), eugenol (5.35%), isoeugenol (5.16%), methyl benzoate (2.17%), methyl anthranilate (2%).

Effects of basil seed and guar gums coatings on sensory attributes and quality of dehydrated orange slices using osmotic-ultrasound method

In this work, the effects of gum coating (basil seed and guar gums), ultrasonic power, sonication time, and sucrose concentration on the osmosis dehydration parameters (water loss, solid gain, and rehydration rate), sensory attributes, color changes, and surface shrinkage of dehydrated orange slices using osmotic-ultrasound method were studied. The moisture loss and sucrose gain increased when the ultrasonic duration and sucrose level increased. The edible coating reduced solids absorption, with the lowest sucrose absorption in the basil seed gum-coated slices. Also, the coating increased rehydration rate of dried orange slices, with the highest rehydration ratio in the basil seed gum-coated slices (225.91 %). Edible coating with basil seeds gum improved the sensorial attributes of dried orange slices. The total color difference (ΔE) and surface shrinkage of osmotic dehydrated, dried, and rehydrated orange slices decreased with edible coating pretreatment and increasing in the sonication intensity. As the ultrasound duration enhanced from 5 to 15 min, the average surface shrinkage values of dried and rehydrated orange slices increased from 22.74 % to 26.36 %, and 12.18 % to 15.50 %, respectively. The current work confirmed that the gum coating has the potential to enhance appearance quality and sensorial attributes of osmotic-ultrasound dehydrated orange slices.

Ultrasound-assisted preparation of faba bean protein isolate-Vitis vinifera L. polyphenol extract conjugates: Structural and functional characterization

The purpose of this study was to create conjugates between faba bean proteins (FP) and grape leaf polyphenols (GLP) utilizing an alkaline treatment assisted by sonication. The effects of sonication intensity on the binding of FP and GLP were investigated using scanning electron microscopy (SEM), Fourier Transform Infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). The SEM results revealed that sonication altered the structure of the solid material formed by dehydrating FP-GLP conjugates, with fragmented particles being observed in the powdered form. The FTIR results showed that sonication increased the β-sheet structure content while decreasing the α-helix and β-turn structure content. Sonication decreased the size of the FP-GLP conjugates, which was attributed to disruptive cavitation and shear forces. The magnitude of the zeta potential of the conjugates increased significantly after sonication, which suggested that it induced some chemical alterations of the functional groups on the proteins and/or polyphenols. The antioxidant and emulsifying activities of the conjugates were also altered appreciably by sonication. Overall, the effects of sonication depended on the degree of sonication used, which should therefore be optimized to obtain conjugates with the desired functional attributes. This study showed that sonication reduced the production time from 24 h to 10 min of FP-GLP conjugates and enhanced their antioxidant (increased DPPH and ABTS, 145.89% and 48.08%) and emulsifying properties might be beneficial as functional components in foods and other industrial items.

General analytical solution expressions for analyzing Langmuir-type kinetics of sonochemical degradation of nonvolatile organic contaminants in water

Detailed kinetic studies of the ultrasonic decomposition of contaminants in water are scarce. Most of the work has used a pseudo-first order kinetics law, which is unrealistic. The model based on a Langmuir-type mechanism has been shown to fit the sonolytic decomposition data well, especially by using the non-linear technique. To avoid unrealistic assumptions, general analytical solutions to a time-dependent non-linear Langmuir-type equation may be the appropriate method. In this work, the sonolytic oxidation of organic contaminants, i.e., naphthol blue black and furosemide, in water was analyzed using two general analytical solution expressions of the Langmuir-type kinetics model, which describe the pollutant concentration in water. The validity of the two general analytical solution expressions was tested under a diversity of operating conditions, such as initial substrate concentration and varying ultrasonication frequency and intensity. As the initial substrate concentration increased, the sonolytic oxidation kinetics decreased, while the initial ultrasonic decomposition rate increased and then plateaued. Consequently, a heterogeneous kinetics equation based on a Langmuir-type mechanism can be used to simulate the sono-decomposition process. The decomposition yield increased with increasing sonication intensity and decreasing frequency. The two analytical solution expressions seem to be in excellent agreement with the experimental results of the sonochemical decomposition of the nonvolatile organic contaminants tested for the different operating conditions examined. These expressions provide a valuable tool for the analysis and simulation of advanced sonochemical oxidation processes under various experimental conditions.

Integrated poultry waste management by co-digestion with perennial grass: Effects of mixing ratio, pretreatments, reaction temperature, and effluent recycle on biomethanation yield

This work aims to enhance the efficiency of integrated poultry waste management in bio-circular-green economy by maximizing the co-digestion of chicken manure and its digestate-grown biomass. In a series of batch assays, Napier grass (NG) was mixed with chicken manure (CM) at various proportions (100:0, 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100) to identify co-substrate synergism, followed by physiochemical conditioning (size reduction and ultrasonication) of NG before co-digestion. Results indicated that NG mix of at least 80% was required to gain a full methanation potential of the individual substrates; no synergistic ratio above unity was found. However, the combined effect of size reduction and sonication was found to markedly improve the co-substrate’s biodegradability by 88.7%. The findings were then used to run continuous co-digestion at various operating regimes. In optimal continuous co-digestion condition, NG particle size of 0.6–2.4 mm combined with sonication intensity at 1111 kJ/kgTS improved biomethanation yield as high as 106.3%. Sub-thermophilic digestion at 45 °C was shown to give a higher and more stable CH4 yield than at 55 °C. Finally, it was also found that recycling liquid effluent at 40% to replace freshwater in feed, although showed no significant difference in CH4 yield (α = 0.05), noticeably increased system buffer capacity. This optimized biodegradation regime could give co-digestion waste management a higher overall plant efficiency and economic return.

Comparison of three methods including temperature, H2O2/ascorbic acid/sonication, and nitrous acid treatments for overcoming the inhibitory effect of heparin on DNA amplification in realtime-PCR

Heparin molecules have an inhibitory effect on DNA amplification by binding to the majority of DNA-interacting proteins. Different physical, chemical, and enzymatic methods have been used to degrade and depolymerize heparins in biomedical investigations. In this study, we aimed to evaluate some heparin degradation methods to eliminate the inhibitory effect of heparin on DNA amplification. Here, we report highly efficient, simple, and convenient methods to eliminate the heparin inhibitory effect on DNA amplification by treatments including temperature, nitrous acid, and H2O2/ascorbic acid/sonication. Further, treatment conditions including temperature degree and duration of treatments, the concentration of ascorbic acid, and intensity of sonication were reviewed. Target DNAs were extracted using the phenol-chloroform method. DNA concentrations and purity were analyzed before and after each treatment by Nanodrop spectrophotometry. DNA amplifications were attempted using a commercially available realtime-PCR mastermix. We found that the inhibitory behavior of heparin was well eliminated after the 85 °C/2 h, 65 °C/2 h, nitrous acid (pH = 3), and H2O2/ascorbic acid/sonication treatments, respectively. The further analyses indicated that the application of nitrous acid in pH = 1.5 and H2O2/ascorbic acid/sonication in higher ascorbic acid concentrations and sonication intensities lead to failure in DNA amplification due to the degradation of target sequences. From our experience, simple heat treatments or at the next level using nitrous acid and H2O2/ascorbic acid/sonication have enabled the detection and quantification of virus infection in heparin blood samples. These approaches may enable researchers to utilize blood taken in heparin tubes for genome amplification and diagnostic purposes.

Design of polymeric nanoparticles for oral delivery of capreomycin peptide using double emulsion technique: Impact of stress conditions

Peptides are short polymers of amino acids that are unstable at drastic conditions including highly acidic or highly alkaline media, high temperature and high shear forces. Polymeric nanoparticles as carrier for peptides are the most desirable formulation in pharmaceutical field than other colloidal systems because of their stability in biological environment. Two different biodegradable polymers were chosen to formulate nanoparticles as carriers for capreomycin sulfate (CMS) peptide. Chitosan was selected as a water soluble polymer, while, poly(lactic-co-glycolic) acid (PLGA) polymer is soluble in organic solvents. Double emulsion solvent evaporation technique was used in the formulation of the nanoparticles. This method required applying of thermal, mechanical and chemical stresses that could have impact on peptide degradation that should be considered in the design of nanoparticles. Many formulation factors for polymeric nanoparticles optimization were tested including: probe sonication intensity and time, homogenization speed, pH of dispersion media, drug:polymer ratios, type and concentration of crosslinking agents and concentration of the stabilizer. Controlling these factors with monitoring of peptide degradation allowed to optimize polymeric nanoparticles having the smallest possible particle sizes (343.7–1656.5 nm) with the highest entrapment efficiencies (17.30–62.30%). The produced polymeric nanoparticles were tested for in vitro drug release in phosphate buffer pH 6.8. Different CMS release profiles were observed (15.52–72.44%) where PLGA NPs showed significant slower release compared with that of chitosan NPs.

Incorporation of white tea extract in nano-liposomes: optimization, characterization, and stability.

In the present study, an extraction method affected by sonication intensity (40%, 70% and 100%), sonication time (5, 10 and 15 min) and different solvents (ethanol, methanol and a combination of ethanol/methanol) was optimized to extract the white tea with the greatest polyphenolic compounds using a response surface methodology. To prepare the nano-liposomal vesicles, phospholipids and cholesterol in various proportions (60:0, 40:20, 30:30 and 20:40) were applied based on thin-film hydration and ultrasound method. The nano-capsules enriched in bioactive compounds were examined through particle characteristics, encapsulation efficiency, morphological analysis, thermal properties and Fourier transform infrared spectroscopy. The observations showed that the extraction yield highly depended on the type of solvent with varying permeability, sonication time and power. The highest total phenolic content (68.38 mg GA g-1 ) and free radical scavenging activity (77.65%) were observed for the following optimal conditions: 70% for sonication intensity, 15 min for sonication time and methanol as solvent. Characteristics of nanoliposomes within a compositional ratio of lecithin/cholesterol (40:20) and with a zeta potential of -56 ± 0.01 mV, as well as white tea extract (WTE) samples with an average particle diameter of 82.20 ± 0.08, microencapsulation efficiency of 76.5% ± 0.081, polydispersity index of 0.06 ± 0.02 and span value of 0.69 ± 0.03. are used as the optimal formulation for microencapsulation of antioxidant WTE. The results demonstrated an increment in thermal stability of liposomal WTE samples compared to other samples. The findings of the present study indicated that nano-liposomes comprise an effective technology for coating the WTE, as well as to increasing its stability and thermal properties. © 2021 Society of Chemical Industry.

Electro-Kinetic Degradation of Diesel Originated from a Costal Crude Oil Terminal

: The present study evaluated the effect of the integration of electro-kinetic (EK) oxidation with sonication degradation of diesel in a hydrocarbon contaminated wastewater. The effect of operational parameters including initial pH (3 - 9), sonication (100 - 300 W), voltage (0.5 - 3 V/cm), and reaction time (60 - 150 min) were studied consecutively. The highest total petroleum hydrocarbon (TPH) destruction rate of 40% was achieved at pH 5. Also, increasing the sonication intensity up to 300 W improved the removal rate to 70%. The pseudo-first-order kinetic model was selected due to higher correlation coefficient. Considering the obtained integration of EK oxidation with sonication is a viable and efficient technology for treatment of diesel contaminated wastewaters.

Synthesis of Nanoparticles Fully Made of Hemoglobin with Antioxidant Properties: A Step toward the Creation of Successful Oxygen Carriers.

Transfusion of donor red blood cells (RBCs) is a crucial and widely employed clinical procedure. However, important constraints of blood transfusions include the limited availability of blood, the need for typing and cross-matching due to the RBC membrane antigens, the limited storage lifetime, or the risk for disease transmission. Hence, a lot of effort has been devoted to develop RBC substitutes, which are free from the limitations of donor blood. Despite the potential, the creation of hemoglobin (Hb)-based oxygen carriers is still facing important challenges. To allow for proper tissue oxygenation, it is essential to develop carriers with high Hb loading since Hb comprises about 96% of the RBCs' dry weight. In this work, nanoparticles (NPs) fully made of Hb are prepared by the desolvation precipitation method. Several parameters are screened (i.e., Hb concentration, desolvation ratio, time, and sonication intensity) to finally obtain Hb-NPs with a diameter of ∼568 nm and a polydispersity index (PDI) of 0.2. A polydopamine (PDA) coating is adsorbed to prevent the disintegration of the resulting Hb/PDA-NPs. Due to the antioxidant character of PDA, the Hb/PDA-NPs are able to deplete two harmful reactive oxygen species, namely, the superoxide radical anion and hydrogen peroxide. Such antioxidant protection also translates into minimizing the oxidation of the entrapped Hb to nonfunctional methemoglobin (metHb). This is a crucial aspect since metHb conversion also results in inflammatory reactions and dysregulated vascular tone. Finally, yet importantly, the reported Hb/PDA-NPs are also both hemo- and biocompatible and preserve the reversible oxygen-binding and releasing properties of Hb.

Development of a Pressure Control System According to Paste Rheology for Ultrasound Processing in Industrial Olive Oil Extraction

Recent research has demonstrated how ultrasound can benefit the industrial processing of olive paste before oil extraction. However, the absence of a device for controlling pressure inside the sonication cell is a major hindrance to its application. To address this problem, a pneumatic device with a programmable logic controller was implemented to automatically adjust pressure in the sonication cell according to a preset value: its functionality was tested in industrial oil extraction. An experiment was conducted to compare device performance when applied to olive batches with different solid/liquid ratios and differing rheology. The control system adjusted the flow section of the valve at the outlet of the sonication cell and the mass flow rate of the feed pump in order to maintain the pressure preset by the operator. Results indicate that the pressure was 3.0 ± 0.2 bar, 3.5 ± 0.2 bar, and 4.0 ± 0.2 bar when the set point was 3.0 bar, 3.5 bar, and 4.0 bar, respectively: there was thus no significant difference between controlled and set values. This indicates that the device is able to control pressure inside the sonication cell with a maximum deviation of 0.2 bar. In this case, the sonication intensity was stabilized at 135 W/cm2, 150 W/cm2, and 165 W/cm2 at 3.0 bar, 3.5 bar, and 4.0 bar, respectively. This study presents an advancement in ultrasound applications for industrial olive oil extraction: optimal pressure control in the sonication cell.

Particle Size and Crystal Habit Modification of Active Pharmaceutical Ingredient Using Cooling Sonocrystallization: A Case Study of Probenecid

AbstractThis study uses a cooling sonocrystallization process to recrystallize an active pharmaceutical ingredient, probenecid, and to improve the crystal qualities such as crystal habit and particle size characteristics. To screen the appropriate solvent system, solubility data of probenecid in organic solvent are measured, reported, and correlated by van't Hoff equation. According to the measured solubilities and data acquired from literature, sonocrystallization experiments using solvents with acceptable theoretical recovery are performed. Owing to the satisfactory throughput, yield, and crystal qualities, ethanol is finally decided as the appropriate solvent system. The effect of operating parameters in sonocrystallization including the solution concentration, sonication intensity, sonication duration, and cooling rate using ethanol as the solvent is further studied. With applying power ultrasound, probenecid crystals with narrow size distribution, regular crystal habit, and mean size around 15 µm are successfully produced. Finally, crystal form and spectroscopic property of sonocrystallized sample and probenecid as received from the supplier are compared and confirmed consistent from the analytical results of powder X‐ray diffractometer and Fourier transform infrared spectroscopy.

Tailoring the size of ultrasound responsive lipid-shelled nanodroplets by varying production parameters and environmental conditions

Liquid perfluorocarbon nanodroplets (NDs) are an attractive alternative to microbubbles (MBs) for ultrasound-mediated therapeutic and diagnostic applications. ND size and size distribution have a strong influence on their behaviour in vivo, including extravasation efficiency, circulation time, and response to ultrasound stimulation. Thus, it is desirable to identify ways to tailor the ND size and size distribution during manufacturing. In this study phospholipid-coated NDs, comprising a perfluoro-n-pentane (PFP) core stabilised by a DSPC/PEG40s (1,2-distearoyl-sn-glycero-3-phosphocholine and polyoxyethylene(40)stearate, 9:1 molar ratio) shell, were produced in phosphate-buffered saline (PBS) by sonication. The effect of the following production-related parameters on ND size was investigated: PFP concentration, power and duration of sonication, and incorporation of a lipophilic fluorescent dye. ND stability was also assessed at both 4 °C and 37 °C. When a sonication pulse of 6 s and 15% duty cycle was employed, increasing the volumetric concentration of PFP from 5% to 15% v/v in PBS resulted in an increase in ND diameter from 215.8 ± 16.8 nm to 408.9 ± 171.2 nm. An increase in the intensity of sonication from 48 to 72 W (with 10% PFP v/v in PBS) led to a decrease in ND size from 354.6 ± 127.2 nm to 315.0 ± 100.5 nm. Increasing the sonication time from 20 s to 40 s (using a pulsed sonication with 30% duty cycle) did not result in a significant change in ND size (in the range 278–314 nm); however, when it was increased to 60 s, the average ND diameter reduced to 249.7 ± 9.7 nm, which also presented a significantly lower standard deviation compared to the other experimental conditions investigated (i.e., 9.7 nm vs. > 49.4 nm). The addition of the fluorescent dye DiI at different molar ratios did not affect the ND size distribution. NDs were stable at 4 °C for up to 6 days and at 37 °C for up to 110 min; however, some evidence of ND-to-MB phase transition was observed after 40 min at 37 °C. Finally, phase transition of NDs into MBs was demonstrated using a tissue-mimicking flow phantom under therapeutic ultrasound exposure conditions (ultrasound frequency: 0.5 MHz, acoustic pressure: 2–4 MPa, and pulse repetition frequency: 100 Hz).

Effect of Power Ultrasound on Wettability and Collector-Less Floatability of Chalcopyrite, Pyrite and Quartz

Numerous studies have addressed the role of ultrasonication on floatability of minerals macroscopically. However, the impact of acoustic waves on the mineral hydrophobicity and its physicochemical aspects were entirely overlooked in the literature. This paper mainly investigates the impact of ultrasonic power and its time on the wettability and floatability of chalcopyrite, pyrite and quartz. For this purpose, contact angle and collectorless microflotation tests were implemented on the ultrasonic-pretreated and non-treated chalcopyrite, pyrite and quartz minerals. The ultrasonic process was carried out by a probe-type ultrasound (Sonopuls, 20 kHz and 60 W) at various ultrasonication time (0.5–30 min) and power (0–180 W) while the dissolved oxygen (DO), liquid temperature, conductivity (CD) and pH were continuously monitored. Comparative assessment of wettabilities in the presence of a constant low-powered (60 W) acoustic pre-treatment uncovered that surface of all three minerals became relatively hydrophilic. Meanwhile, increasing sonication intensity enhanced their hydrophilicities to some extent except for quartz at the highest power-level. This was mainly related to generation of hydroxyl radicals, iron-deficient chalcopyrite and elemental sulfur (for chalcopyrite), formation of OH and H radicals together with H2O2 (for pyrite) and creation of SiOH (silanol) groups and hydrogen bond with water dipoles (for quartz). Finally, it was also found that increasing sonication time led to enhancement of liquid temperature and conductivity but diminished pH and degree of dissolved oxygen, which indirectly influenced the mineral wettabilities and floatabilities. Although quartz and pyrite ultrasound-treated micro-flotation recoveries were lower than that of conventional ones, an optimum power-level of 60–90 W was identified for maximizing chalcopyrite recovery.

Graphene/PVA buckypaper for strain sensing application

Strain sensors in the form of buckypaper (BP) infiltrated with various polymers are considered a viable option for strain sensor applications such as structural health monitoring and human motion detection. Graphene has outstanding properties in terms of strength, heat and current conduction, optics, and many more. However, graphene in the form of BP has not been considered earlier for strain sensing applications. In this work, graphene-based BP infiltrated with polyvinyl alcohol (PVA) was synthesized by vacuum filtration technique and polymer intercalation. First, Graphene oxide (GO) was prepared via treatment with sulphuric acid and nitric acid. Whereas, to obtain high-quality BP, GO was sonicated in ethanol for 20 min with sonication intensity of 60%. FTIR studies confirmed the oxygenated groups on the surface of GO while the dispersion characteristics were validated using zeta potential analysis. The nanocomposite was synthesized by varying BP and PVA concentrations. Mechanical and electrical properties were measured using a computerized tensile testing machine, two probe method, and hall effect, respectively. The electrical conducting properties of the nanocomposites decreased with increasing PVA content; likewise, electron mobility also decreased while electrical resistance increased. The optimization study reports the highest mechanical properties such as tensile strength, Young’s Modulus, and elongation at break of 200.55 MPa, 6.59 GPa, and 6.79%, respectively. Finally, electrochemical testing in a strain range of ε ~ 4% also testifies superior strain sensing properties of 60 wt% graphene BP/PVA with a demonstration of repeatability, accuracy, and preciseness for five loading and unloading cycles with a gauge factor of 1.33. Thus, results prove the usefulness of the nanocomposite for commercial and industrial applications.