Sonication Period Research Articles

Synthesis of Carbon Nanotube Through Sonochemical Process Under Ambient Conditions

A sonochemical method was used to synthesize carbon nanotube (CNT) in the presence of dichlorobenzene and ZnCl2 under ambient conditions. Structural characterizations were carried out using Raman spectroscopy, X-ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS) which confirmed successful formation of CNT. Thermogravimetric analysis shows reduction in amorphous carbon with increase in the sonication period. Morphological studies using field emission scanning electron microscope (FE-SEM) and High resolution transmission electron microscopy (HR-TEM) reveals the formation of combination of single and multiwall carbon nanotubes. The electronic band structural characterization using Ultra violet-visible-near infrared spectroscopy (UV-Vis/NIR) confirms the existence of metallic and semiconducting carbon nanotubes.

Determination of cavitation bubble lifetimes using bubble-bubble coalescence data

The effect that surface-active solutes, such as aliphatic alcohols and sodium dodecylsulfate, have on the extent of bubble coalescence in liquids under different sonication conditions has been investigated by measuring the volume change of the solution following a period of sonication. The data obtained led to the conclusion that SDS does not reach equilibrium adsorption level at the bubble/solution interface. On this basis, a method is proposed for estimating nonequilibrium surface excess values for solutes that do not fully equilibrate with the bubble/solution interface during sonication. For the case of SDS in the presence of excess NaCl, the method was further employed to estimate the maximum lifetime of bubbles in a multibubble field. Data obtained from this study suggests that an acoustic bubble in a multibubble field has a finite lifetime, and that this lifetime decreases with increasing applied frequency, ranging from up to 0.35 ± 0.05 ms for 213 kHz to 0.10 ± 0.05 ms for 1062 kHz. These estimated lifetimes equate to a bubble in a multibubble field undergoing an upper limit of 50-200 oscillations over its lifetime for applied acoustic frequencies between 200 kHz and 1 MHz.

Sonochemical Synthesis of Poly (Methyl Acrylate)

Polymers are prepared by various methods. The method of preparation plays an important role in deciding many of the physical properties of polymers. In this work Poly (Methyl Acrylate), PMA, is synthesized by free radical addition polymerization in the presence a monomer, an initiator under the influence of ultrasound. Methyl Acrylate (E-Merck, India) of proper strength is mixed with aqueous sodium peroxodisulphate solution of known strength and the time of passage of ultrasound is varied in steps of 30 minutes and 10 samples of solid PMA are obtained for 10 different periods of passage of ultrasound. Solid PMA samples are purified and air-dried under clean environment. TGA, DTA measurements are done on all the 10 PMA samples. The thermal stability of PMA with the change in the time of passage of ultrasound is discussed quantitatively. The thermal stability of PMA, synthesized sonochemically shows better results over the thermal method of synthesis. However in this paper we report the measurements made on PMA samples synthesized at 30 and 300 minutes sonication periods respectively.

Nondestructive DNA extraction from blackflies (Diptera: Simuliidae): retaining voucher specimens for DNA barcoding projects

A nondestructive, chemical-free method is presented for the extraction of DNA from small insects. Blackflies were submerged in sterile, distilled water and sonicated for varying lengths of time to provide DNA which was assessed in terms of quantity, purity and amplification efficiency. A verified DNA barcode was produced from DNA extracted from blackfly larvae, pupae and adult specimens. A 60-second sonication period was found to release the highest quality and quantity of DNA although the amplification efficiency was found to be similar regardless of sonication time. Overall, a 66% amplification efficiency was observed. Examination of post-sonicated material confirmed retention of morphological characters. Sonication was found to be a reliable DNA extraction approach for barcoding, providing sufficient quality template for polymerase chain reaction amplification as well as retaining the voucher specimen for post-barcoding morphological evaluation.

Optimisation of sludge disruption by sonication

This study presents an examination on the correlation of sonication operating condition, sludge property, formation and behaviour of cavitation bubbles in sludge disruption under low-frequency ultrasound sonication. The influence of sonication time, sonication density, type of sludge and solids content on the disruption was evaluated. The most vigorous particle disruption was achieved in the initial period of sonication, which subsided subsequently. The explosive effect was likely due to the rapid cavitation arising from powerful transient bubbles generated in fractions of microseconds. A rating for the type of sludge was derived based on the finding that particles in secondary sludge were more readily disrupted than both primary sludge and mixed sludge. While sonication density exhibited the most significant role in cavitation bubble formation and behaviour, particle disruption could be optimised for energy input by sonicating at higher sonication density and shorter sonication time. Based on theoretical consideration, it was deduced that within an optimum sludge solids content ranging between 2.3% and 3.2%, superior particle disruption could be accomplished within a minute for secondary sludge sonicated at a density of 0.52 W/mL. Useful guidelines for sonication system installation, equipment protection and process reliability could be established from knowledge derived from a good understanding on the influence of solids content on sludge sonication.

Biodegradation of four phthalate esters in sludge

This study investigated the effects of ultrasonic pretreatment and various treatments on the aerobic degradation of four phthalic acid esters (PAEs) such as diethyl phthalate (DEP), benzyl butyl phthalate (BBP), di- n-butyl phthalate (DBP) and di-(2-ethyl hexyl)phthalate (DEHP) in sludge. The effect on PAE degradation of treating sludge with a 20 min sonication period at a power level of 0.1 W ml −1 was evaluated. The degradation rates of the four PAEs were DBP > BBP > DEP > DEHP. Degradation rate constants ( k 1) and half-lives ( t 1/2) for the four PAEs (50 mg kg −1) ranged from 0.182 to 0.379 day −1 and 1.8 to 3.8 days, respectively. The optimal pH for PAE degradation in sludge was 7.0 at 30 °C. PAE degradation was enhanced by the addition of yeast extract, brij 30 or brij 35 and inhibited by the addition of hydrogen peroxide. Our results show that a combination of ultrasonic pretreatment and biodegradation can effectively remove PAE from sludge.

Study of the Coalescence of Acoustic Bubbles as a Function of Frequency, Power, and Water-Soluble Additives

The effect that surface-active solutes, such as aliphatic alcohols and sodium dodecyl sulfate (SDS), have on the extent of bubble coalescence in liquids under different sonication conditions has been investigated by measuring the volume change of the solution following a period of sonication. In general, the adsorption of surface-active solutes onto the bubble surface retards bubble coalescence. Within the limitations of the measurement method and the systems studied, bubble coalescence does not appear to be dependent on the applied acoustic power. Also, varying the applied acoustic frequency has a minimal effect on the extent of bubble coalescence in systems where long-range electrostatic repulsion between bubbles, imparted by the adsorbed surface-active solutes, dominates. However, when short-range steric repulsion (or other short-range repulsive forces) is the primary factor in inhibiting bubble coalescence, the dependence on the applied acoustic frequency becomes apparent, with less coalescence inhibition at higher frequencies. It is also concluded that SDS does not reach an equilibrium adsorption level at the bubble/solution interface under the sonication conditions used. On the basis of this conclusion, a method is proposed for estimating nonequilibrium surface excess values for solutes that do not fully equilibrate with the bubble/solution interface during sonication. For the case of SDS in the presence of excess NaCl, the method was further employed to estimate the maximum lifetime of bubbles in a multibubble field. It was concluded that an acoustic bubble in a multibubble field has a finite lifetime, and that this lifetime decreases with increasing applied frequency, ranging from up to 0.35 +/- 0.05 ms for 213 kHz to 0.10 +/- 0.05 ms for 1062 kHz. These estimated lifetimes equate to a bubble in a multibubble field undergoing an upper limit of 50-200 oscillations over its lifetime for applied ultrasound frequencies between 200 kHz and 1 MHz.

A kinetic study of the effect of ultrasound power on the sonohydrolysis of tetraethyl orthosilicate

A kinetic study of the ultrasound-stimulated and acid-catalyzed sonohydrolysis of tetraethyl orthosilicate (TEOS) in solventless TEOS–water heterogeneous mixtures was carried out by means of a calorimetric method as a function of the ultrasound power. The hydrolysis reaction starts in acidulated heterogeneous water–TEOS mixtures after an induction period under ultrasonic stimulation. The ultrasound power seems to play a role on the dynamical coupling of the system originating a continuum upward shifting of the base line during the induction period of sonication. The rate in which the base line is upward shifted diminishes with the power. The best coupling between the ultrasound and the reactant heterogeneous mixtures for this experimental setup was found to occur at 50 W, for which the gelation time was found to be a minimum. The kinetics of the heterogeneous TEOS sonohydrolysis was studied on the basis of a dissolution and reaction modeling. The heterogeneous reaction pathway as deduced from the kinetic study was drawn in a ternary diagram as a function of the ultrasound power.

Fragmentation of DNA by Sonication: Figure 1.

INTRODUCTIONDNA fragmentation is often necessary prior to library construction or subcloning for DNA sequencing. This protocol describes a method for DNA fragmentation by sonication. During sonication, DNA samples are subjected to hydrodynamic shearing by exposure to brief periods of sonication. DNA that has been sonicated for excessive periods of time is extremely difficult to clone. Most sonicators will not shear DNA to a size of less than 300-500 bp, and it is tempting to continue sonication until the entire DNA population has been reduced in size. However, the yield of subclones is usually greater if sonication is stopped when the fragments of the target DNA first reach a size of ~700 bp.

Isothermal titration calorimetric study of calcium association to lipid bilayers: influence of the vesicle preparation and composition

The association of Ca2+ ions with phospholipid bilayers was investigated using isothermal titration calorimetry. The study reveals that the binding enthalpy of these cations to bilayers formed with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) depends strongly on the method of preparation of the unilamellar vesicles. Extruded vesicles lead to an exothermic association, whereas sonicated ones lead to an endothermic association. In the later case, the calorimetric signal is sensitive to the length of the sonication period. It is proposed that a reorganization of the lipid bilayers under stress, obtained with sonicated small unilamellar vesicles, contributes to the calorimetric signal upon the titration with Ca2+. The analysis of the titrations indicates that, as expected, the nature of the association of Ca2+ with negatively charged phospholipid bilayers is essentially of electrostatic nature. Using a Scatchard approach, it is found that bilayers become saturated in Ca2+ approximately when the electroneutrality of the bilayer interface is reached. Moreover, the affinity constant was reduced by the increase of the ionic strength of the aqueous buffer. It was found that the intrinsic binding constant of Ca2+ to membranes containing 30 and 50 mol% of POPG was about 11 mM-1, in a MES buffer containing 10 mM NaCl, at pH 5.6.

The measurement of thermal diffusivity in poly(methyl acrylate) by photoacoustic technique

AbstractIt is suggested that when a polymer is synthesized from a monomer and an added initiator in the presence of ultrasound, the process may produce polymers with predetermined structures and physical properties. An attempt is made to measure thermal diffusivity. Poly(methyl acrylate) (PMA) is synthesized using monomer methyl acrylate and an added initiator peroxodisulfate in the presence of ultrasound of frequency 35 kHz and power 100 W/cm2 at 50°C for various known sonication periods. PMA is obtained as a colorless, semitransparent solid. The solid PMA is cut into thin wafers in a highly symmetric direction to have uniform sizes. PMA samples are synthesized for 11 different sonication periods. These PMA samples are use to study their thermal diffusivity (α) by photoacoustic (PA) technique. Thermal diffusivity is calculated by measuring the amplitude and phase of the PA signal separately. A plot of the sonication period versus thermal diffusivity obtained from amplitude measurements of PMA indicates that there is an increase in thermal diffusivity from 2 × 10−6 to 4.7 × 10−6 m2/s when sonication period is increased from 30 to 330 min in steps of 30 min. The same trend is seen in a plot between sonication period and thermal diffusivity when the thermal diffusivity is calculated by PA phase measurements. There is a small difference in the experimental values obtained by the two measurements. Dependence of thermal diffusivity of PMA on ultrasonic sonication is discussed in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 3756–3760, 2006

HDLs in apoA-I transgenic Abca1 knockout mice are remodeled normally in plasma but are hypercatabolized by the kidney

Patients homozygous for Tangier disease have a near absence of plasma HDL as a result of mutations in ABCA1 and hypercatabolize normal HDL particles. To determine the relationship between ABCA1 expression and HDL catabolism, we investigated intravascular remodeling, plasma clearance, and organ-specific uptake of HDL in mice expressing the human apolipoprotein A-I (apoA-I) transgene in the Abca1 knockout background. Small HDL particles (7.5 nm), radiolabeled with (125)I-tyramine cellobiose, were injected into recipient mice to quantify plasma turnover and the organ uptake of tracer. Small HDL tracer was remodeled to 8.2 nm diameter particles within 5 min in human apolipoprotein A-I transgenic (hA-I(Tg)) mice (control) and knockout mice. Decay of tracer from plasma was 1.6-fold more rapid in knockout mice (P < 0.05) and kidney uptake was twice that of controls, with no difference in liver uptake. We also observed 2-fold greater hepatic expression of ABCA1 protein in hA-I(Tg) mice compared with nontransgenic mice, suggesting that overexpression of human apoA-I stabilized hepatic ABCA1 protein in vivo. We conclude that ABCA1 is not required for in vivo remodeling of small HDLs to larger HDL subfractions and that the hypercatabolism of normal HDL particles in knockout mice is attributable to a selective catabolism of HDL apoA-I by the kidney.

Determination of Manganese and Lead in Roadside Soil Samples by FAAS with Ultrasound Assisted Leaching

An Ultrasonic Leaching Method (ULM) was developed for the analysis of manganese and lead on roadside soil samples in order to assess the pollution from motor vehicle exhaust. The variations in analyte recoveries by sonication periods were investigated and optimum recovery conditions were determined. The leachates of the soil samples, Mn and Pb, were analyzed by flame atomic absorption spectrometry (FAAS). The recoveries of ULM were tested by comparing the results with those of the conventional extraction method (CE) for Mn and Pb. With regard to the dissolution process, higher recoveries were obtained using ULM than with CE in a relatively shorter time. The precision of the method was found to be 1.9–3.7% for Pb and 4.6–8.4% for Mn (n = 4), as the average in terms of relative standard deviation (RSD%) depended on the analyte element concentrations and the nature of the samples. Using the ULM-FAAS method, significant results were obtained for Mn and Pb as vehicle exhaust pollutants. The pollution factors (PFs) obtained for Mn and Pb correlated mainly with vehicle exhaust emissions in different parts of Sivas and partly with some specific environmental conditions.

Ultrasonic dehalogenation and toxicity reduction of trichlorophenol

The study focussed on the effect of ultrasonic frequency and co-pollutants on dechlorination and toxicity reduction of a toxic model pollutant, i.e. 2,3,5-trichlorophenol (TCP). The effect of ultrasonic frequency on TCP degradation and chloride formation was studied at 41, 206, 360, 618, 1068, and 3217 kHz. Most efficient ultrasonic dechlorination was achieved at 360 kHz. The degradation of TCP and adsorbable organic halogens followed pseudo-first-order rate kinetics. Toxicity in the bioluminescence test increased during the initial sonication period, indicating the temporary formation of more toxic reaction products. Subsequently, toxicity was significantly reduced. Dehalogenation efficiency decreased in the presence of the hydrophobic radical scavenger t-butanol, whereas hydrophilic co-pollutants such as acetate or glucose did not interfere with ultrasonic dechlorination and toxicity reduction. After ultrasonic pre-treatment, a fast biodegradation of the remaining organic pollutants was observed. In conclusion, the results demonstrate the potential of integrated ultrasonic/biological approaches for the treatment of wastewaters containing toxic pollutants.

Chromium(III) determination with 1,5-diphenylcarbazide based on the oxidative effect of chlorine radicals generated from CCl4 sonolysis in aqueous solution.

Oxidation of Cr(III) during sonication in carbonated aqueous solutions saturated with CCl4 leads to the quantitative formation of Cr(VI) and provides a simple and rapid method for spectrophotometric chromium determination with 1,5-diphenylcarbazide. The key to this method is the production of chlorine radicals when aqueous solution saturated with CCl4 is exposed to ultrasonic waves of 40 kHz. The effects of sonication period, CCl4 solution volume, acidity, and interferences were discussed. The time required for a single determination is lower than 2 min. The relative standard deviation obtained for aqueous solutions with 1 microg of Cr was < 2% (N = 10) and the calculated detection limit (3sigma) was 5 ng of Cr.

Sonochemical synthesis of mesoporous transition metal and rare earth oxides

Straight-extended layered mesostructures based on transition metal (Fe, Cr) and rare earth (Y, Ce, La, Sm, Er) oxides are synthesized by sonication for 3 h. After a longer period of sonication (6 h), hexagonal mesostructures based on Y- and Er-oxides are obtained. The surface areas of the Y-based hexagonal mesophases before and after extraction are 46.5, 256 m 2/g, respectively. For Er-based hexagonal mesophases, the surface areas before and after extraction are 157 and 225 m 2/g. The pore sizes after extraction are 5.0 and 2.2 nm for Y- and Er-based mesophases, respectively. Hexagonal mesostructures are also obtained for Zr-based material after sonication for 3 h and the hexagonal structure is still maintained after calcinations at 400 °C for 4 h, although the surface area is only 35 m 2/g.

Theoretical design of a spherically sectioned phased array for ultrasound surgery of the liver

Goal: The theoretical explantion of the limits of an array transducer to coagulate large tissues volumes. Methods: A theoretical model is used to illustrate the focal limitations of a spherically sectioned array designed for the treatment of deep seated tissue, e.g. liver. The design optimizes the acoustic dose as a function of the focal depth and available acoustic aperture with the goal of coagulating large volumes in a single sonication period. A quantitative measure of the possible region of focal necrosis is modeled as a function of array parameters with the limiting criteria being near field heating and patient pain. Results: Acoustic simulations show that the maximum distance to produce continuous necrosis between foci in a multiple focus pattern and in a temporally multiplexed pattern is approximately 50% larger than the distance needed between sequential foci. Conclusion: Multiple focus patterns or rapidly scanned single foci are significantly advantageous to sequential sonications of a single focus transducer.

Factors influencing the encapsulation of thioguanine in DRV liposomes

Thioguanine, a chemotherapeutic drug employed in the treatment of leukemia, is, like other amphiphilic drugs, very permeant and presents a high ability to escape from the liposomal membrane. For this reason, it is very important to know which parameters can enhance the relatively low encapsulation of thioguanine. In this way, the influence of four factors (pH, content of cholesterol, charge of lipids, and time of sonication) on the encapsulation of such drug in dehydration-rehydration liposomes was studied using a 2 4 factorial design. In this study, the maximal encapsulation efficiency obtained was 14.07 mmol/mol of lipid and time of sonication was the unique factor whose influence on the encapsulation was statistically significant ( P < 0.05). The energy input concomitant to higher periods of sonication seems to facilitate the entrapment of the drug into the bilayer. Among the two-way interactions, time charge and pH-charge presented levels of significance less than 0.05. In liposomes with negative charge (10% phosphatidic acid), time of sonication barely influenced on the encapsulation, but in stearylamine-containing liposomes, higher times of sonication were necessary to achieve a better yield of encapsulation. More complex was the effect of the pH-charge interaction. At pH 4.7, liposomes with phosphatidic acid favoured the encapsulation, while at pH 7.4, liposomes with stearylamine encapsulated more drug. The different extent of encapsulation in the function of pH and charge only could be explained by the different charge born by the positive and negative liposomes depending on the pH.

Preparation and characterization of cytarabine-loaded w/o/w multiple emulsions

Cytarabine-loaded w/o/w multiple emulsions were prepared using nonionic surfactants of the Tween and Span types, and characterized by studying the osmotic behavior. The effect of the sonication period on the entrapment efficiency, droplet size and emulsion stability was investigated. The entrapment efficiency was up to 79% and was not affected by the loading dose. The size of droplets decreased with increase in the second sonication time. It was found that the oil layer of multiple emulsion droplets including the hydrophobic fatty acid tails of surfactants behaves as a water-permeable membrane between two aqueous phases of w/o/w multiple emulsion. The combination of Tween 20/80 and Span 20/80 as a hydrophilic and lipophilic surfactant system produced the most stable multiple emulsion. The release study showed that the multiple emulsion containing cytarabine in the internal aqueous phase was stable, exhibiting a prolonged release pattern.

Ultrasound Effects on Cerium, Praseodymium, and Terbium Oxides

The behavior of intermediate higher rare earth oxides, such as Pr6O11 and Tb4O7, and Ce1-xPrxO2 compounds as powders has been studied by a new experimental procedure. They have been subjected to ultrasound irradiation (20 kHz) during immersion in a 5% dilute acetic acid solution. Pure PrO2 and TbO2 oxides (yield 100%) can be formed within sonication periods of 7-8 and 15-24 hr, respectively (instead of 3 days and 1 month through classical methods). Electron microscopic images and granulometry measurements show that the grain size has decreased greatly after sonication. The results are discussed in terms of cavitation phenomena and of chemical species (H2, O2, HO2, OH, H2O2,…) formed during sonolysis of water and acetic acid.