Sonication Frequency Research Articles

Effects of various frequencies and powers of ultrasound on cleaning of flat sheet membrane during and after microfiltration

Membrane processing has found many applications in various industries as an advanced method of separating materials in liquid or gas. The greatest obstacle in using membrane filtration technology is fouling, particularly in porous membranes. The fouling phenomenon is the result of organic and inorganic materials depositing on the surface and pores of membrane. In this study, the effect of ultrasound frequency (37, 80 kHz, and tandem) and amplitude of sonication (30, 60, and 90%) were evaluated on flux recovery during and after microfiltration. Results showed that the 37 kHz and tandem frequencies significantly improved the permeate flux at earlier minutes, particularly when tandem frequency was applied. In addition, the permeate flux was increased as the sonication power increased. However, the interaction effects between frequency and sonication power showed that the ultrasound frequencies were more effective than sonication power on flux recovery. Furthermore, the calculation of fouling percentage showed that both low frequencies and high amplitude together significantly reduced the fouling agents during the cleaning process. However, there were no remarkable statistical effects among the same levels of sonication power during the cleaning process. The interaction effects of various frequencies and powers of ultrasound on cleaning membranes were evaluated and more cleaning efficiency was observed in comparison to sonication power when low frequency applied.

Effectiveness of localized ultrasound-targeted microbubble destruction with doxorubicin liposomes in H22 mouse hepatocellular carcinoma model

Objective: In order to increase local drug concentration and reduce systemic side effects of liver cancer chemotherapy, it is desirable to develop novel non-invasive technologies for drug targeting, such as ultrasound-targeted microbubble destruction (UTMD).Methods: H22 hepatocellular carcinoma (HCC) xenograft transplantation model was generated in UTMD study. BALB/c mice were randomly divided into six groups: doxorubicin HCl liposomal injection (DOX), DOX + US, UTMD, DOX + UTMD, H22 liver tumor control (CH control) and blank control group. The therapeutic schedule started on day 4 after tumor inoculation.Results: Average survival time of the animal model was approximately 18 d. The UTMD therapy parameters were optimized in the H22 mouse model to be: microbubble (MB) diameter, 2.30 ± 0.25 μm; MB density, 4.0 × 109 bubbles/ml; treatment dose, 0.2 ml per 20 g mouse body weight; sonication frequency, 1.3 MHz; and sonication power, 2.06 W/cm2. Mice treated with DOX + UTMD had the smallest tumor volume and weight (p < 0.001), and the highest tumor inhibition rate (p < 0.01), intratumoral DOX concentration (p < 0.001) and survival rate among all tumor-burden groups (p < 0.001). Cell viability in different treatment groups was also assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.Conclusion: An improved antitumor effect was observed with the combination therapy of DOX and UTMD, as compared with treatment with DOX, DOX + US or UTMD, which implicates a novel approach for HCC treatment.

Ultrasound-assisted enzymatic extraction (UAEE) of phytochemical compounds from mulberry (Morus nigra) must and optimization study using response surface methodology

A new method of ultrasound-assisted enzymatic extraction (UAEE) was applied to mulberry must treatment with processing variables of sonication frequency (FS), enzyme concentration (CE) and maceration time (TM) at constant temperature 20°C and pulse durations of 10s on and 5s off. A Box–Behnken Design (BBD) was used to investigate the main effect of the various variables on total phenolics (TPC), total flavonoids (TFC), total anthocyanins (TAC), lightest (L*) and Browning index (BI). The predicted model was found to be significant (p<0.05) with low standard error and high coefficients of determination (R2). The model was highly correlated to experimental results and this helped in the identification of the optimum operating conditions: FS=33.82kHz, CE=0.010% (v/w) and TM=11.58min, under which it predicted TPC=298.06mg/100ml; TFC=379.24mg/100ml; TAC=55.14mg/100ml; L*=3.51 and BI=1.19. The study shows that the UAEE could be employed to enhance the quality of must, reduce the time during the maceration process of juice or wine.

Ultrasonication-Assisted Hydrothermal Synthesis of Ultralong TiO2 Nanotubes

Abstract Ultralong titanate nanotubes were synthesized by treating general anatase TiO2 in alkaline solution using a facile sonication-assisted hydrothermal method. The as-synthesized products via sonication and sonication-hydrothermal treatment were characterized by SEM, TEM, OM and XRD. The effects of sonication power, sonication frequency and sonication temperature on the morphology and the crystal structure of the products were investigated. The results show that in the range of ultrasonic power (200, 300, 400, 500 W) and frequency (20, 40, 80 kHz), titanium dioxide particles were swelled in alkali aqueous solution to get the hedgehog flocculent intermediate products by ultrasonic irradiation when the ultrasonic temperature was equal or higher than 60 °C; several tens of microns long titanate nanotubes were achieved using the intermediate products as raw materials under the mild hydrothermal conditions of 90 °C and 5 h. The possible formation mechanism for ultralong titanate nanotubes was also discussed. The hedgehog floccules synthesized by sonication play an important role to synthesize the several tens of micrometers long nanotubes.

Sonoelectrocatalytic decomposition of methylene blue using Ti/Ta2O5–SnO2 electrodes

Sonoelectrochemical decomposition of organic compounds is a developing technique among advanced oxidation processes (AOPs). It has the advantage over sonication alone that it increases the efficiency of the process in terms of a more rapid decrease in chemical oxygen demand (COD) and in total organic carbon (TOC) and accelerates electrochemical oxidation which normally requires a lengthy period of time to achieve significant mineralisation. Moreover the use of an electrocatalytic electrode in the process further accelerates the oxidation reaction rates. The aim of this study was to improve the decomposition efficiency of methylene blue (MB) dye by sonoelectrochemical decomposition using environmentally friendly and cost-effective Ti/Ta2O5–SnO2 electrodes. Decolourisation was used to assess the initial stages of decomposition and COD together with TOC was used as a measure of total degradation. The effect of a range of sonication frequencies 20, 40, 380, 850, 1000 and 1176kHz at different powers on the decolourisation efficiency of MB is reported. Frequencies of 850 and 380kHz and the use of higher powers were found more effective towards dye decolourisation. The time for complete MB degradation was reduced from 180min using electrolysis and from 90min while carrying out sonolysis to 45min when conducting a combined sonoelectrocatalytic experiments. The COD reduction of 85.4% was achieved after 2h of combined sonication and electrolysis which is a slightly higher than after a single electrolysis (78.9%) and twice that of sonolysis (40.4%). A dramatic improvement of mineralisation values were observed within 2h of sonoelectrocatalytic MB degradation. The TOC removal efficiency increased by a factor of 10.7 comparing to sonication alone and by a factor of 1.5 comparing to the electrolytic process. The energy consumption (kWh/m3) required for the complete degradation of MB was evaluated.

Ultrasound‐induced nucleation in microcellular polymers

ABSTRACTIn this study, microcellular Acrylonitrile–Butadiene–Styrene foams with high cell density and expansion ratio has been manufactured using ultrasound‐induced nucleation technique in solid‐state batch foaming process. Influence of sonication time, sonication frequency, and ultrasound power were found very crucial in designing of cellular morphology. The initial 10 s of ultrasound exposure was found to influence the foam morphology critically. Longer periods of ultrasound exposure developed foams with lower average cell size as compared to foams developed with lesser ultrasound exposure time. Higher sonication power resulted in foams with uniform morphology and higher cell densities as compared to foams developed with lower sonication intensities. Finally, the ultrasonic frequency was also found to influence the morphology intensely. Low frequency sonication resulted in foams with uniform cell distribution, whereas high frequency sonication developed bimodal microcellular type of microstructure. The results coherently demonstrate that with the advent of ultrasonic waves, the energy barrier for cell nucleation swiftly decreases which enhances the cell density in the final foamed product. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40742.

Investigating the sonophoresis effect on the permeation of diclofenac sodium using 3D skin equivalent

Ultrasound temporally increases skin permeability by altering stratum corneum SC function (sonophoresis). The objective of this study was to evaluate the effect of variable ultrasound conditions on the permeation of diclofenac sodium DS with range of physicochemical properties through EpiDerm™. Permeation studies were carried out in vitro using Franz diffusion cell. HPLC method was used for the determination of the concentration of diclofenac sodium in receiving compartment. Parameters like ultrasound frequency, application time, amplitude, and mode of sonication and distance of ultrasound horn from skin were investigated, and the conditions where the maximum enhancement rate obtained were determined. Application of ultrasound enhanced permeation of diclofenac sodium across EpiDerm™ by fivefolds. The most effective enhancing parameters were power sonication of 20kHz frequency, 20% amplitude at continuous mode for 5min.

Fabrication of Layer-By-Layer Self-Assembled Drug Delivery Platform for Prednisolone

In present study, Layer-by-Layer (LbL) self-assembly technology was successfully adopted for encapsulation of Prednisolone (PDL) in polyelectrolyte microcapsules (PEM) for sustained release. We report use of high frequency sonication to form PDL nanocrystals from PDL, which were subsequently coated with polyanions and polycations. The developed formulation was evaluated using scanning electron microscopy (SEM), zeta potential, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), in vitro dissolution and diffusion studies. The in vitro drug release study demonstrated decreased PDL release with an increase in number of coatings. The PDL release can be tailored by formulating it in form of PEM.

Performance and kinetic evaluation of the semi-continuous anaerobic digestion of sunflower oil cake pretreated with ultrasound

A study of the semi-continuous anaerobic digestion of sunflower oil cake previously sonicated (at a specific energy of 24,000 kJ/kg TS, constant sonication frequency of 20 kHz and ultrasonic power of 120 W) was carried out in laboratory-scale completely stirred tank reactors at mesophilic temperature (35°C). Two anaerobic inocula were used: a mixture of flocculant biomass (I) from a full-scale anaerobic reactor treating waste activated sludge and a granular inoculum (II) from an industrial UASB reactor treating brewery wastewater. Soluble COD (CODs) removal efficiencies ranged between 67.7% and 70.1% and between 61.3% and 67.7% at hydraulic retention times (HRTs) of between 24–10 days for inoculum I and 24–8 days for inoculum II. However, for HRTs lower than 8 days and 6.7 days, equivalent to organic loading rates (OLRs) higher than 2.62 and 3.15 g COD/(L·d), respectively, a sudden decrease in the CODs removal efficiency was observed in both cases. In any case, inoculum II allowed for a more stable and efficient operation for a wider range of both OLRs and HRTs, permitting an appropriate and reliable operation for OLRs as high as 3.15 g COD/(L·d) and HRTs as low as 6.7 days. The methane production rates achieved with inoculum II were always higher than those reached with inoculum I. The overall methane yield obtained with inoculum II was 13% higher than that achieved with inoculum I. In addition, this value was 1.9 times higher than the methane yield obtained with untreated (non-sonicated) SuOC. A second-order kinetic model was found to be adequate to fit the experimental results obtained for the two inocula used. The kinetic constant obtained with inoculum I was 3.5 times higher than that achieved with inoculum II.

Dual-frequency ultrasound activation of nanomicellar doxorubicin in targeted tumor chemotherapy

This study investigated the therapeutic effect of dual-frequency sonication (3MHz and 28kHz) at low intensity levels in combination with micellar doxorubicin in the treatment of a tumor model of spontaneous breast adenocarcinoma in Balb/c mice. We used sonication frequencies 28kHz and 3MHz and their dual combinations in the progressive wave mode to enhance acoustic cavitation. Then, the antitumor effect of the simultaneous dual-frequency ultrasound (28kHz and 3MHz) at low intensity levels in combination with doxorubicin and micellar doxorubicin injection was investigated in a spontaneous model of breast adenocarcinoma in Balb/c mice. Sixty-three tumor-bearing mice were randomly divided into seven groups: control, sham, sonication with dual frequency, doxorubicin without sonication, doxorubicin with dual-frequency sonication, micellar doxorubicin without sonication, and micellar doxorubicin with dual-frequency sonication. The tumor volume change relative to the initial volume, tumor growth inhibition ratio, the required times for each tumor to reach two (T 2) and five (T 5) times its initial volume, and survival period were the tumor growth delay parameters which were calculated and recorded at various times after treatment. The results of the combination of frequencies 28kHz (0.04W/cm(2)) and 3MHz (2.00W/cm(2)) showed remarkable enhancement of the cavitation activity compared with single-frequency sonication (P<0.05). The micellar doxorubicin injection with sonication group showed a significant difference in the relative volume percent parameter compared with the other groups (P<0.05). Additionally, the T 2 and T 5 times in the micellar doxorubicin with sonication group were significantly higher than in the other groups (P<0.05). Also, the survival period of the mice in the micellar doxorubicin with sonication group was significantly longer than in the other groups (P<0.05). These findings were verified histopathologically. This study shows that simultaneous combined dual-frequency ultrasound sonication in continuous mode is effective in producing cavitation activity at low intensity. We conclude that dual-frequency sonication with micellar doxorubicin injection extends survival in a murine breast adenocarcinoma model.

Sono-biostimulation of aerobic digestion: a novel approach for sludge minimization

BACKGROUND For the first time, low intensity ultrasonication was applied to stimulate biological activities during aerobic digestion of municipal waste activated sludge (AS). Specific oxygen uptake rate (SOUR) analysis was performed to investigate the sono-biostimulation effects on AS activity. RESULTS The greatest improvement of 60% in SOUR was observed at sonication density and irradiation time of 0.2 W mL-1 and 60 s, respectively. A subsequent batch aerobic digestion study showed 74% reduction in total chemical oxygen demand (TCOD) and volatile suspended solids (VSS) after 12 days of aerobic digestion, with 127% and 112% improvement in TCOD and VSS removal, respectively, in comparison with the control reactor. The sono-biostimulation effects on AS lasted 6 h and completely disappeared within 8 h after sonication stopped. CONCLUSIONS The sonication density, irradiation time and volume and frequency of sludge sonication were observed to play important roles in bio-stimulation and the subsequent aerobic digestion process. Intermittent sonication protocol for 60 s every 8 h was the best treatment condition to improve aerobic digestion efficiency. © 2013 Society of Chemical Industry

Variation in ultrasonic frequency and time as pre-treatments to air-drying of carrot

Vegetable drying is an alternative method to curb post harvest decay of vegetables and a process to produce dried vegetables, which can be directly consumed or used as ingredients for the preparation of soups, stews, baby foods, cakes, puddings, and many other foods. In this study, the effect of ultrasound frequency and sonication time as pre-treatment prior to air drying at 70°C at an air velocity of 0.5 m/s, on carrot drying kinetics, flavour, colour, and non-enzymatic browning was investigated using a 3-level factorial response surface method. The result showed that an increase in sonication frequency and time did not significantly increase moisture diffusivity but in comparison with the control, water diffusivity increased after ultrasound application and the overall drying time was reduced. Application of the ultrasound pre-treatment in distilled water resulted in water gain and sugar loss, indicating that the ultrasonic pre-treatment can be an important step to produce low sugar content dried products. The brightness and redness to yellowness values of the ultrasonically pre-treated dried carrots were better than those without ultrasound application. In comparison with the flavour of the control, the ultrasound pre-treated samples recorded higher flavour response signals, indicating that the application of ultrasound improved the flavour of the dried carrot. The variation in sonication frequency and time did not significantly affect the non-enzymatic browning index of the dried products but were better than the control.

Variation in ultrasonic frequency and time as pre-treatments to air-drying of carrot

Vegetable drying is an alternative method to curb post harvest decay of vegetables and a process to produce dried vegetables, which can be directly consumed or used as ingredients for the preparation of soups, stews, baby foods, cakes, puddings, and many other foods. In this study, the effect of ultrasound frequency and sonication time as pre-treatment prior to air drying at 70°C at an air velocity of 0.5 m/s, on carrot drying kinetics, flavour, colour, and non-enzymatic browning was investigated using a 3-level factorial response surface method. The result showed that an increase in sonication frequency and time did not significantly increase moisture diffusivity but in comparison with the control, water diffusivity increased after ultrasound application and the overall drying time was reduced. Application of the ultrasound pre-treatment in distilled water resulted in water gain and sugar loss, indicating that the ultrasonic pre-treatment can be an important step to produce low sugar content dried products. The brightness and redness to yellowness values of the ultrasonically pre-treated dried carrots were better than those without ultrasound application. In comparison with the flavour of the control, the ultrasound pre-treated samples recorded higher flavour response signals, indicating that the application of ultrasound improved the flavour of the dried carrot. The variation in sonication frequency and time did not significantly affect the non-enzymatic browning index of the dried products but were better than the control.

Metal array fabrication based on ultrasound-induced self-assembly of metalated dipeptides

Pd- and Pt-bound bis-metalated peptides were synthesised by the condensation of Pd- or Pt-aldimine-complex-bound glutamic acids to afford the four possible metal isomers of bis-Pd and bis-Pt-homometalated dipeptides and PdPt- and PtPd-heterometalated dipeptides without metal disproportionation. Ultrasound-induced self-assembly of these bis-metalated peptides proceeded effectively to afford supramolecular gels that displayed well-ordered metal arrays. The formation of parallel β-sheet type aggregates through interpeptide amide-amide hydrogen bonding was confirmed by IR, scanning electron microscopy (SEM), and synchrotron X-ray diffraction analyses (WAXS and SAXS). The mechanism of the ultrasound-induced self-assembly of the metalated dipeptides was elucidated via kinetic and association experiments by (1)H NMR, in which ultrasound-triggered dissociation of intramolecular hydrogen bonds between the chloride ligands of the Pd- and Pt-complexes and amides initially occurred. This was followed by the formation of intermolecular amide-amide hydrogen bonds, which afforded the corresponding oligomeric peptide self-assembly as the nucleus for supramolecular aggregation. The observed first-order relationship of the gelation rate versus the sonication frequency suggested that the microcavitation generated under sonication conditions acted as a crucial trigger and provided a reaction field for efficient self-assembly.

The relationship between dissolution, gas oversaturation and outgassing of solutions determined by Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS)

The addition of a solute to a solvent is known to reduce the solubility of dissolved gases in solution which leads to gas oversaturation and outgassing of the solvent. The importance of the processes involved have received relatively little attention due to a limited capacity to elucidate their effects in real time. Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS) is a recently introduced acoustic approach which can monitor changes in the compressibility of a solvent due to outgassing. BARDS spectra show that a time dependent and quantitative reduction in gas oversaturation, following the dissolution of a simple salt, takes place over several hours. It is shown how vigorous agitation quickly equilibrates a solution, post dissolution, by removing gas oversaturation consistently. The level of oversaturation can be elucidated by further dissolving a marker compound into a solution consecutively. BARDS spectra indicate that the dissolution of a compound produces a consistent and quantifiable oversaturation of a solvent and a consistent and quantifiable outgassing. Low frequency sonication in an immersion bath is also shown to play no significant role in removing gas oversaturation post dissolution.

Low frequency and intensity ultrasound induces apoptosis of brain glioma in rats mediated by caspase-3, Bcl-2, and survivin

Low frequency and intensity ultrasound (LFU) sonication can selectively induce brain tumor cell apoptosis without damaging neural cells, while also enhancing drug delivery to brain tumors. To explore the underlying mechanisms of related pathways in LFU-induced apoptosis, we investigated the expression of proteins associated with LFU-induced apoptosis. C6 cells were used for in vitro experiments and C6 tumor-bearing rats were used during in vivo experiments. 3-[4.5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide; thiazolyl blue (MTT) assay was used to detect C6 cell viability in vitro. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) analysis was used to check the apoptotic cells, and they were counted and analyzed both in vitro and in vivo. Transmission electron microscopy (TEM) was used to illustrate the ultrastructure of apoptotic nuclei of cancer cells in vivo. The expressions of caspase-3, Bcl-2, and survivin proteins were assessed by immunofluorescence, immunohistochemistry and Western blot analysis in vivo. C6 cell viability decrease was statistically significant; the numbers of apoptotic C6 cells in the LFU sonication groups were higher than those in the control group both in vitro and in vivo. The expression of caspase-3 increased, yet the expressions of Bcl-2 and survivin decreased significantly 6h after LFU sonication, compared with the control group in vivo. This study suggests that LFU can induce apoptotsis in vitro and in vivo, and that three signaling proteins, caspase-3, Bcl-2, and survivin, might be involved in LFU-induced apoptosis.

Preparation of Biodiesel Using Ultrasonication Energy and its Performance in CI Engine

Fatty acid methyl ester (FAME), a renewable liquid biofuel popularly known as biodiesel, is emerging as a suitable replacement to common diesel fuel (CDF) in unmodified Compression Ignition (CI) engine. Present article reports the development of a process to reduce the operating cost during the conversion of vegetable oil to biodiesel through the application of ultrasound energy. Around 98% yield of FAME could be achieved with low reaction parameters such as methanol-oil molar ratio, catalyst concentration, reaction time, and temperature. The optimum condition for the maximum 98% yield was 1.0 wt% of NaOH catalyst, 5:1 methanol: oil molar ratio and temperature 55°C under a sonication frequency of 20 kHz. With these reaction parameters the conversion occurred in just 5 minutes. The FAME obtained was purified in an effective way by water washing followed by passing over a bed of silica gel. The purified FAME was subjected to the evaluation of its fuel characteristics in a four-stroke, single-cylinder CI engine, which could operate with variable compression ratio. The engine performance study revealed that lower blends of biodiesel up to B20 could be an efficient fuel for an unmodified CI engine.

Ultrasound-Assisted Extraction of Syringin from the Bark of Ilex rotunda Thumb Using Response Surface Methodology

In this work, a rapid extraction method based on ultrasound-assisted extraction (UAE) of syringin from the bark of Ilex rotunda Thumb using response surface methodology (RSM) is described. The syringin was analyzed and quantified by high performance liquid chromatography coupled with UV detection (HPLC-UV). The extraction solvent, extraction temperature and extraction time, the three main factors for UAE, were optimized with Box-Behnken design (BBD) to obtain the highest extraction efficiency. The optimal conditions were the use of a sonication frequency of 40 kHz, 65% methanol as the solvent, an extraction time of 30 min and an extraction temperature of 40 °C. Using these optimal conditions, the experimental values agreed closely with the predicted values. The analysis of variance (ANOVA) indicated a high goodness of model fit and the success of the RSM method for optimizing syringin extraction from the bark of I. rotunda.

Dual-frequency ultrasound for designing two dimensional catalyst surface: Reduced graphene oxide–Pt composite

Few-layered reduced graphene oxide–Pt composites are prepared using a combination of two ultrasound frequencies at 20kHz and 211kHz. Such a unique dual frequency arrangement operating in tandem, yields large exfoliated graphene sheets with platinum nanoparticles dispersed on them. The extent of reduction achieved by the use of this dual frequency sonication arrangement is evaluated by XPS, IR, and Raman spectroscopies. Transmission electron and atomic force microscopies confirm the morphology of resulting assemblies to be bi- and single layered sheets. These composites show good electrocatalytic activity towards methanol oxidation.

WE‐A‐217A‐08: Modeling of Thermal Effects in Antivascular Ultrasound Therapy from Contrast Enhanced Ultrasound Images

Purpose: To study the role of intravascular microbubble‐induced heating resulting from in‐vivo low‐intensity sonication of solid tumors using contrast‐enhanced ultrasound images. Methods: Solid tumors are modeled as a compressible inhomogeneous medium that consists of a network of micro‐blood vessels in a microenvironment of cells and interstitial fluids through which microbubbles flow. A mathematical model based on the Penne Bioheat equation was used to calculate the microbubble‐enhanced temperature increase during sonication of solid tumors. This mathematical framework was applied to contrast‐enhanced ultrasound images to simulate the in‐vivo conditions of antivascular ultrasound therapy. Results: The results show that the presence of microbubbles causes local heating in the tumor at the locations of the microbubbles in the image. The temperature initially increases rapidly initially as a function of time and then levels off. The temperature elevation calculated as a function of sonication frequency, show that, the maximum temperature change occurs near the resonance frequency of the microbubbles. The mathematical simulations also show that as the flow rate increases, the temperature elevation decreases. Conclusions: Our results show that microbubbles circulating in the blood provide a mechanism for delivering acoustic energy at the location of the microbubbles. Since previous experimental studies show that sonication of intravascular microbubbles disrupt tumor microvessels, antivascular ultrasound treatment has the potential for treating patients with cancer.