Ultrasound Power Density Research Articles

Inactivation of Escherichia coli by Ultrasound Combined with Nisin

The aim of this study was to investigate the inactivation of nonpathogenic Escherichia coli in nutrient broth and milk through the use of either ultrasound (US) alone or US combined with nisin (US + nisin) treatments. The E. coli cells were treated at 0 to 55°C, 242.04 to 968.16 W/cm2 for 0 to 15 min. The results showed that the inactivation of E. coli by US and US + nisin increased when the temperature, US power density, and treatment time were increased. The inactivation kinetics of E. coli in nutrient broth by US and US + nisin both conformed to linear models. The largest reductions of 2.89 and 2.93 log cycles by US and US + nisin, respectively, were achieved at 968.16 W/cm2 and at 25°C for 15 min. The suspension media of the E. coli cells influenced the inactivation effect of US, while the growth phases of E. coli cells did not affect their resistance to US. Under all experiment conditions of this study, the differences between US and US + nisin in their respective inactivation effects on E. coli were not obvious. The results suggested that nisin had either no effect at all or a weak synergistic effect with US and that the E. coli cells were inactivated mainly by US, thus indicating that the inactivation of E. coli by US is an "all or nothing" event.

Improvements on the Stability and Vitamin Content of Acerola Juice Obtained by Ultrasonic Processing.

This work has examined the influence of ultrasonic processing on acerola juice and its influence in the stability of the juice and in the availability of vitamins B, C, E, and pro-vitamin A. The study has evaluated the changes in these quality parameters resulting from changes on ultrasonic power density, processing time and temperature. Ultrasound application increased the availability of pro-vitamin A and vitamins B3, B5, C and E in the juice by releasing them from the apoenzymes to which they are bound and by improving the homogeneity of the juice. The retention of the major vitamins in acerola juice (vitamins A and C) was higher when lower temperatures (10 to 20 °C) and mild ultrasound power density (2000 to 3000 W/L) were applied.

Comparison of ultrasound therapy and radial shock wave therapy in the treatment of venous leg ulcers - clinical, pilot study.

IntroductionVenous insufficiency and venous leg ulcers each year affect more and more people, especially in developed countries. The challenge of our time is to find an effective method of treating venous leg ulcers, which will further shorten treatment time and reduce the cost of treatment.AimTo compare the effects of treating venous leg ulcers using ultrasound therapy, radial shock wave therapy and standard care.Material and methodsGroup A consisted of 17 patients. Patients were treated with ultrasound therapy US power density 0.5 W/cm2, pulsed wave with a duty cycle of 1/5, and 1 MHz frequency. Group B consisted of 17 patients. Patients were treated with the radial shock wave R-ESWT using surface energy density 0.17 mJ/mm2, 100 impulses/cm2, frequency of 5 Hz and a pressure of 0.2 MPa. Group C (control group) consisted of 17 patients. Patients in this group received standard care: gauze dressing saturated in 0.9% sodium chloride and elastic bandages changed daily for 4 weeks.ResultsUltrasound therapy with 1 MHz and energy power density 0.5 W/cm2 for 4 weeks resulted in an average reduction of 68% of the area of ulceration. We used for venous leg ulcers 4-week treatment with radial shock wave therapy resulting in a 38% mean percentage reduction of the ulceration area. Standard care reduces the area of ulceration by only 16%.ConclusionsThe use of ultrasound therapy for the treatment of venous leg ulcers is more effective than the use of radial shock wave therapy or standard care alone.

Ultrasound assisted alkaline pretreatment to enhance enzymatic saccharification of grass clipping

Grass clipping, a cellulose-rich raw material, has great potential to produce biofuels, but must be firstly hydrolyzed to liberate fermentable sugars. In this study, grass clipping was pretreated with ultrasound (US), Ca(OH)2, NaOH, US-Ca(OH)2 and US-NaOH at relatively low temperature to enhance its enzymatic hydrolysis. The solubilization of hemicellulose and lignin, and crystallinity index of cellulose increased after US-alkaline pretreatment, leading to a significant increase of enzyme accessibility to cellulose. Compared with another four pretreatments, US-Ca(OH)2 pretreatment of grass clipping showed the best improvement for reducing sugar yield. X-ray diffraction (XRD) determination and scanning electron microscope (SEM) observation showed that the crystallinity index of grass clipping increased and the grass clipping surface suffered from serious erosion after US-Ca(OH)2 pretreatment. Then, the operating conditions of US-Ca(OH)2 pretreatment and enzymatic hydrolysis were systematically optimized, and the suitable operating conditions were as follows: US power density of 0.65W/ml, US pretreatment time of 30min, Ca(OH)2 concentration of 0.75%, pretreatment temperature of 75°C, enzyme loading of 125FPU/g, and hydrolysis time of 72h. The reducing sugar yield of grass clipping pretreated by US-Ca(OH)2 reached 414mg/g, increasing by 3.5 times compared with that of raw grass clipping. The US-Ca(OH)2 pretreatment of grass clipping at low temperature significantly enhanced the potential of grass clipping as a promising raw material to produce biofuels.

Sonochemical oxidation of piroxicam drug: effect of key operating parameters and degradation pathways

AbstractBACKGROUNDPiroxicam (PRX) is a non‐steroidal anti‐inflammatory drug (NSAID) commonly used to relieve pain and swelling of conditions like arthritis. PRX has been extensively detected in seawater, surface, and sewage waters worldwide and therefore its efficient treatment is an issue of emerging concern. In this work, the sonochemical degradation of PRX was investigated.RESULTSAll experiments were conducted at constant ultrasound frequency of 20 kHz while the following range of experimental conditions was investigated: initial PRX concentration 320–960 µg L‐1, ultrasound power density 20–60 W L‐1, temperature 20–60 °C, reaction time up to 60 min. The effect of different water matrices, namely surface water (SW), bottled water (BW), ultrapure water (UPW) and humic acid (HA) aqueous solution on process efficiency was also explored. It was found that PRX degradation reached 96% after only 10 min of treatment under the best conditions (i.e. [PRX]0 = 320 mg L‐1, 20 °C, 36 W L‐1) assayed. Power density could positively affect PRX degradation. Nevertheless, PRX degradation decreased when its initial concentration and the temperature of the bulk liquid was increased. PRX degradation was found to decrease, in different water matrices, in the order: UPW > 5 mg L‐1 HA > BW > 10 mg L‐1 HA > SW. High resolution mass spectrometry analysis revealed that 14 transformation by‐products (TBPs) were formed and subsequently degraded during treatment while the PRX degradation pathways were also elucidated.CONCLUSIONAt the optimal operating conditions assayed, PRX was efficiently degraded after about 10 min of sonochemical oxidation, thus rendering it a promising technology for the treatment of xenobiotics. © 2017 Society of Chemical Industry

Sonolysis and sono-Fenton oxidation for removal of ibuprofen in (waste)water

Two sonochemical processes were compared for the removal of ibuprofen in different water matrixes (distilled water and effluent from wastewater treatment plant). The effect of various operating parameters, such as pH (2.6–8.0), ultrasound power density (25–100W/L), sonication frequency (12–862kHz), addition of radical promoters (H2O2 and Fenton’s reagent) or scavengers (n-butanol and acetic acid), was evaluated.Sono-degradation of ibuprofen followed a first-order kinetic trend, whose rate constant increased with ultrasound density and frequency. For this hydrophobic and low volatile molecule, a free-radical mechanism at the bubble interface was established. Coupling ultrasound with Fenton reaction showed a positive synergy, especially in terms of mineralization yield, while adding H2O2 alone had no significant beneficial effect. Dedicated experiments proved this synergy to be due to the enhanced regeneration of ferrous ions by ultrasound.Efficacy of the sonolysis process was hampered in wastewater matrix, mainly as the consequence of higher pH increasing the molecule solubility. However, after convenient acidification, sono-Fenton oxidation results remained almost unchanged, indicating no significant radical scavenging effects from the effluent compounds.

Effects of Ultrasound Working Parameters on the Ultrasonic Power Density Some Neglected Problems in the Application of Ultrasound Bath

Ultrasound has been widely employed in food industry, while some of its working parameters are usually neglected to be described in its application, which caused the difficulty of reproducing and comparing the results obtained by different groups. So it is definitely not sufficient to simply state the ultrasound conditions such as ultrasound power, frequency and temperature, additionally, other parameters including the geometry of the reaction vessel, vessel distance, initial temperature of water, ultrasonic power density and positions used for fixing vessel are also very important for the actual/practical ultrasound power delivered to the targeted solution. Considering these facts, the above-mentioned factors were systematically conducted to study their effects on the actual ultrasound power, i.e. ultrasound power density for achieving maximum benefit, as a result, to highlight the importance of fully describing the ultrasound working parameters about its application.As expected, the results confirmed our assumption that nearly all the studied parameters did have a great influence on the actual ultrasound power density dissipated into the targeted solution, excluding vessel position. In a word, this research would make this paper valuable to the scientific community, underline the importance of these neglected or rejected problems in the application of ultrasound bath, and persuade the readers to give some more thoughts to these issues.

Ultrasound-assisted extraction of fructans from agave (Agave tequilana Weber var. azul) at different ultrasound powers and solid-liquid ratios

The effects of ultrasound-assisted extraction (UAE) at different ultrasound power densities (UPDs; 40, 80, and 120 mW/mL) and solid:liquid (S:L) ratio (1:2, 1:3, and 1:6) on the extraction of carbohydrates from Agave tequilana plant of different ages were evaluated. Extracts obtained (6- and 7-year-old plant) were analyzed in the yield of carbohydrates (YC), fructan (FRU) content, simple sugars, fructan profile and the average degree of polymerization (DPn). UPD, S:L ratio, and plant age all affected YC, FRU, and DPn. Maximum YC and FRU were obtained from the older agave with UPD and S:L ratio of 120 mW/mL and 1:6, respectively; while glucose, fructose, and sucrose were highly released from the younger plant. Agave of 7-year-old presented the highest DPn. Fructan degradation occurred at high UPD, increasing the simple sugars and decreasing the DPn. Thermal-traditional extraction without sonication caused more fructan degradation; and overall, ultrasound enhanced fructan extraction and minimized fructan damage, representing a technological alternative for fructan extraction from agave.

Effects of ultrasound pretreatment on enzymolysis of sodium caseinate protein: Kinetic study, angiotensin-converting enzyme inhibitory activity, and the structural characteristics of the hydrolysates

Effects of ultrasound frequency and power density on enzymolysis of sodium caseinate (NaCas) and on the structure of the protein hydrolysate were studied. Enzymolysis kinetics, angiotensin-I converting enzyme (ACE) inhibitory activity, atomic force microscopy (AFM), scanning electron microscopy (SEM), intrinsic fluorescence and the circular dichroism (CD) were determined. Ultrasound significantly (p < .05) increased the degree of hydrolysis (DH), conversion rates of protein, ACE inhibitory activity and the apparent breakdown rate (kA) but decreased the apparent constant (kM). AFM revealed that sonication increased the protein particles diameters, and Rq and Ra values. Fluorescence spectra and SEM images show increases in surface areas of NaCas. CD spectra revealed increases in β-sheet, β-turn and random coil by 20, 5.33 and 5.91%, respectively, and decreased α-helix by 8.82%. Overall, ultrasound successfully improved enzymolysis of NaCas and release more ACE inhibitory activity due to the increases in specific surface area of protein molecule. Practical applications NaCas is a functional ingredient widely used in foods industry, that is, it has beneficial effects on lowering blood pressure by producing ACE inhibitory peptides. Effects of ultrasound frequency and power density were performed to improve the enzymolysis of NaCas and the release of ACE inhibitory peptides. The mechanism of ultrasound on releasing of ACE inhibitory peptides was studied by monitoring the changes in protein structure. Generally, sonication remarkably provided a good reference about the enzymolysis of NaCas and the ACE inhibitory activity in polypeptides industries.

Influence mechanisms of textile-dyeing sludge characteristics on degradation of anilines by integrated ultrasound-permanganate treatment

In order to support the use of integrated ultrasound-Mn(VII) for the removal of anilines, this study investigated for the first time the influence of the sludge characteristics on the reaction kinetics of target anilines including o-toluidine, p-chloroaniline, 2-methoxy-5-methylaniline, and 2,4,5-trimethylaniline. The results indicated that with a KMnO4 dosage of 1 mM and an ultrasound power density of 0.90 W cm−3, 68.85%, 85.53%, and 78.50% of anilines can be removed from textile sludge plant 1, 2, and 3. Higher removal efficiency of anilines was achieved at a lower pH value, smaller particle size, and more negative ζ-potential. The target anilines exhibited substantial reactivity toward Mn(VII) with the maxima of second-order rate constants at a pH value near their pKa values for o-toluidine (0.80 M−1s−1 at pH 4), p-chloroaniline (0.65 M−1s−1 at pH 4), 2-methoxy-5-methylaniline (0.45 M−1s−1 at pH 4), and 2,4,5-trimethylaniline (0.34 M−1s−1 at pH 5). Moreover, the biodegradability of textile-dyeing sludge was greatly enhanced by integrated ultrasound-Mn(VII) treatment. This integrated treatment was proposed as an effective method for the disposal of anilines in textile-dyeing sludge.

Treatment effects of lysozyme-shelled microbubbles and ultrasound in inflammatory skin disease

Acne vulgaris is the most common skin disorder, and is caused by Propionibacterium acnes (P. acnes) and can induce inflammation. Antibiotic therapy often needs to be administered for long durations in acne therapy, which results in extensive antibiotic exposure. The present study investigated a new treatment model for evaluating the antibacterial effects of lysozyme (LY)-shelled microbubbles (MBs) and ultrasound (US)-mediated LY-shelled MBs cavitation against P. acnes both in vitro and in vivo, with the aims of reducing the dose and treatment duration and improving the prognosis of acne vulgaris. In terms of the in vitro treatment efficacy, the growth of P. acnes was inhibited by 86.08 ± 2.99% in the LY-shelled MBs group and by 57.74 ± 3.09% in the LY solution group. For US power densities of 1, 2, and 3 W/cm2 in the LY-shelled MBs group, the growth of P. acnes was inhibited by 95.79 ± 3.30%, 97.99 ± 1.16%, and 98.69 ± 1.13%, respectively. The in vivo results showed that the recovery rate on day 13 was higher in the US group with LY-shelled MBs (97.8 ± 19.8%) than in the LY-shelled MBs group (90.3 ± 23.3%). Our results show that combined treatments of US and LY-shelled MBs can significantly reduce the treatment duration and inhibit P.-acnes-induced inflammatory skin diseases.

Ultrasound Microbubble Contrast Agents Promote Transdermal Drug Delivery

This report discusses a new development in the use of ultrasound (US) microbubble contrast agents on transdermal drug delivery. In clinical applications, microbubbles serve as imaging agents to enhance the contrast of ultrasound images via intravenous injection. Different degrees of microbubble oscillation due to distinct acoustic fields can elicit various degrees of cavitation. Inertial cavitation can enhance the permeability in the surrounding tissues, increase vessel wall permeability, and promote drug entry from blood into cytosol or matrix, whereas stable cavitation can slightly increase tissue permeability without causing any harm. At present, most ultrasound contrast agents are designed for injection into blood vessels, nevertheless, microbubbles with different condition parameters are highly correlated with efficiency in transdermal permeation. As for applications in a transdermal drug delivery, we also used microbubbles at a given concentration in combination with ultrasound to widen intercellular spaces, thereby successfully enhancing the in vivo delivery of arbutin across the skin. In order for liquid-phase microbubbles to be conveniently applied to skin surface, our team modified the medium surrounding the microbubbles at the optimum concentration from liquid to gel. Moreover, it is found that under the same ultrasound power density, microbubbles of larger particle sizes can extend the penetration depths of dye at the phantom surface. Recently, US-mediated drug-coated microbubble cavitation for enhancing hair growth, the treatment of inflammatory skin diseases, and wound healing both in vitro and in vivo have been investigated by our group.

Ultrasound-assisted fluidized bed drying of paddy: Energy consumption and rice quality aspects

ABSTRACTSeveral studies have been conducted on equipping conventional fluidized bed with some technologies to increase drying efficiency and its performance. The objective of this study was to investigate the influence of high-power ultrasound (HPU) on fluidized bed drying of paddy in terms of drying kinetics, grain quality (percentage of cracked kernels and bending strength of grain kernels), and specific energy consumption (SEC). To decrease the initial moisture content of paddy from 26.5 ± 0.5% (kg/kg, d.b) to the final moisture content of 13 ± 0.5% (kg/kg, d.b), the experiments were conducted in a factorial design at three levels of ultrasound power densities (11.1, 14.6, and 18.7 kW/m3), four levels of frequencies (20, 25, 28, and 30 kHz), and three levels of drying air temperatures (30, 40, and 50°C). Application of HPU in conjunction with conventional fluidized bed drying led in 23% decrease in drying time as well as improvement in grain quality, in terms of percentage of cracked kernels and bending strengths. In addition, SEC reduced approximately by 22%, as HPU applied at selected drying condition.

Ultrasound in Biomedical Engineering: Ultrasound Microbubble Contrast Agents Promote Transdermal Permeation of Drugs

This report discusses a new development in the use of ultrasound microbubble contrast agents on transdermal drug delivery. The medium surrounding the microbubbles at the optimum concentration from liquid to gel can be modified and it can still achieve the same enhancement for transdermal drug permeation as liquid medium. It was also found that under the same ultrasound power density, microbubbles of larger particle sizes can extend the penetration depths of dye at the phantom surface.

Degradation of aromatic amines in textile-dyeing sludge by combining the ultrasound technique with potassium permanganate treatment

This paper reports, for the first time, a combined technique of ultrasound (US) with KMnO4 degradation of aromatic amines in a textile-dyeing sludge. The reaction mechanisms and the degradation kinetics of aromatic amines at various operating parameters (KMnO4 dosage, US power density and pH) were systematically examined by the combined system of US-KMnO4. The results indicated that there was a synergistic effect between US and KMnO4, as US greatly enhanced KMnO4 in the degradation of aromatic amines and exhibited apparent sludge disintegration and separated pollutants from the sludge. In addition to accelerating the Mn(VII) reaction with pollutants in the filtrate, US also caused Mn(VII) to enter the porous sludge and sufficiently facilitated the reaction of the strongly absorbed aromatic amines. The combined treatment of US-KMnO4 was effective in the degradation of aromatic amines in textile-dyeing sludge. On average, 58.7% of monocyclic anilines, 88.3% of other forms of aromatic amines, and 24.0% of TOC were removed under the optimal operating conditions of a KMnO4 dosage of 12mM, an US power density of 1.80W/cm3 and pH 5. The present study proposed US-KMnO4 treatment as a practical method for the disposal of aromatic amines in textile-dyeing sludge.

Fabrication and morphology tuning of graphene oxide nanoscrolls.

Here we report the synthesis of graphene oxide nanoscrolls (GONS) with tunable dimensions via low and high frequency ultrasound solution processing techniques. GONS can be visualized as a graphene oxide (GO) sheet rolled into a spiral-wound structure and represent an alternative to traditional carbon nano-morphologies. The scrolling process is initiated by the ultrasound treatment which provides the scrolling activation energy for the formation of GONS. The GO and GONS dimensions are observed to be a function of ultrasound frequency, power density, and irradiation time. Ultrasonication increases GO and GONS C-C bonding likely due to in situ thermal reduction at the cavitating bubble-water interface. The GO area and GONS length are governed by two mechanisms; rapid oxygen defect site cleavage and slow cavitation mediated scission. Structural characterization indicates that GONS with tube and cone geometries can be formed with both narrow and wide dimensions in an industrial-scale time window. This work paves the way for GONS implementation for a variety of applications such as adsorptive and capacitive processes.

Intensification of degradation of methomyl (carbamate group pesticide) by using the combination of ultrasonic cavitation and process intensifying additives

In the present work, the degradation of methomyl has been carried out by using the ultrasound cavitation (US) and its combination with H2O2, Fenton and photo-Fenton process. The study of effect of operating pH and ultrasound power density has indicated that maximum extent of degradation of 28.57% could be obtained at the optimal pH of 2.5 and power density of 0.155W/mL. Application of US in combination with H2O2, Fenton and photo-Fenton process has further accelerated the rate of degradation of methomyl with complete degradation of methomyl in 27min, 18min and 9min respectively. Mineralization study has proved that a combination of US and photo-Fenton process is the most effective process with maximum extent of mineralization of 78.8%. Comparison of energy efficiency and cost effectiveness of various processes has indicated that the electrical cost of 79892.34Rs./m3 for ultrasonic degradation of methomyl has drastically reduced to 2277.00Rs./m3, 1518.00Rs./m3 and 807.58Rs./m3 by using US in combination with H2O2, Fenton and photo-Fenton process respectively. The cost analysis has also indicated that the combination of US and photo-Fenton process is the most energy efficient and cost effective process.

Ultrasonic-assisted ozone oxidation process for sulfamethoxazole removal: impact factors and degradation process

In this study, sulfamethoxazole (SMX) degradation was investigated using an ultrasonic-assisted ozone oxidation process (UAOOP). The influencing factors of ozone concentration, pH, initial SMX concentration, ultrasound power density, and radical scavenger were studied. It was proved that ultrasound application enhanced ozonation function for SMX degradation. Color change of the water during the oxidation process was found to be corresponding to SMX concentration decay in wastewater. The results indicated that SMX degradation followed a pseudo-first-order kinetic model under experimental operating conditions. SMX degradation rate increased with ozone concentration, pH, and ultrasound power density, and was inversely proportional to the initial SMX concentration. Although the direct and indirect oxidation of ozone simultaneously existed in the UAOOP system, the direct oxidation was the predominant way. Meanwhile, the biological toxicity of the solution was weakened and biological oxygen demand/chemical oxygen demand ratio increased from 0 to 0.54. It was indicated that the UAOOP system was efficient to treat SMX wastewater and promote biodegradability for further biological treatment.

Sono-activated persulfate oxidation of bisphenol A: Kinetics, pathways and the controversial role of temperature

The sonochemical degradation of bisphenol A (BPA) in the presence of sodium persulfate (SPS) was investigated at 20kHz. Experiments were performed at 110–450μg/L BPA and 1–100mg/L SPS concentration and an ultrasound power density between 4 and 60W/L. The liquid bulk temperature was either kept constant at 30°C or left uncontrolled and gradually increased up to 80°C. BPA degradation occurs due to the combined action of hydroxyl radicals generated by the ultrasound and sulfate radicals generated by SPS sonolysis and this was confirmed with experiments with methanol and t-butanol as radical scavengers. Considerable thermal SPS activation can also occur at increased temperatures (60–80°C) although the enhanced formation of sulfate radicals is compensated by a decrease in sonochemical activity. Kinetics can be approached by a pseudo-first order expression with the apparent rate constant decreasing with increasing BPA concentration; this implies that the actual order is below first. The rate increases with increasing power density and SPS concentration and decreases at alkaline conditions (i.e. pH=9) and in the presence of inorganic and organic constituents (e.g. bicarbonate, humic acid etc) typically found in environmental matrices.Liquid chromatography time of flight mass spectrometry (LC–TOF–MS) analysis revealed the formation of twelve transformation by-products that accompany BPA sonodegradation in the presence of SPS. Based on their evolution profiles, a reaction mechanism is proposed consisting of two major pathways: (i) hydroxylation that can occur mainly in the aromatic ring through HO, SO4− radical attack and to a lesser extent in methyl groups, through hydrogen abstraction by HO radicals, with subsequent O2 addition, and (ii) scission of the bond between the isopropylidene carbon and the phenyl group.

Understanding the mechanism of ultrasound on the synthesis of cellulose/Cu(OH)2/CuO hybrids

Understanding the mechanism of ultrasound from metal hydroxide to oxides via an ultrasound irradiation method is of great importance for broadening and improving their synthesis and industrial applications. The purpose of this article was to explore the mechanism of ultrasound on the synthesis of cellulose/Cu(OH)2/CuO hybrids. The influences of various reaction parameters including the volume of H2O2, heating method, pulse mode of ultrasound irradiation, sonication time, and power density on the cellulose/Cu(OH)2/CuO hybrids were investigated in detail by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectra (EDS), thermogravimetric analysis (TGA), and derivative thermogravimetry (DTG). The experimental results indicated that all the parameters have effects on the cellulose/Cu(OH)2/CuO hybrids, power density had an effect on the phase transformation of Cu(OH)2 to CuO, and the addition of H2O2 played an important role in the shape of cellulose hybrids, which provided an indirect evidence on the H2O2-induced oxidation route for the transformation process from Cu(OH)2 to CuO during the ultrasound irradiation process. These results maybe direct the synthesis and potential applications of cellulose hybrids in the near future.