Effect Of Ultrasonic Intensity Research Articles

Effect of ultrasonic intensity and intervals of ultrasonic exposure on efficiency of sonochemiluminescence in gel phantom for sonodynamic therapy

Sonodynamic treatment (SDT) is one of the non-invasive modalities for cancer treatment. In SDT, ultrasound, reactive oxygen species (ROS) generated from cavitation bubbles, and a sonosensitizer are used in combination. In this study, high-intensity focused ultrasound (HIFU) was employed as ultrasound to generate and oscillate cavitation bubbles. When cavitation bubbles oscillate and collapse, the gas inside the bubble is extremely compressed and heated, inducing ROS generation. The disadvantage of SDT is a long treatment time because of its smallness of a treatment region by a shot of HIFU. To overcome this, the effect of the intensity and interval of HIFU for oscillating cavitation bubbles was investigated by using luminol sonochemiluminescence and high-speed imaging. The results showed that a HIFU exposure sequence with an interval of 300 ms and a burst-wave intensity of 0.25 kW cm−2 improve the energy efficiency of ROS generation.

Preparation of graphene/PMMA composites with assistance of ultrasonic wave under supercritical CO2 conditions

The two-dimensional material graphene has many excellent physicochemical properties such as large specific surface area, high electron migration rate, good chemical properties, good thermal conductivity, high elastic modulus and mechanical strength that make it very valuable for theoretical research and application in the preparation of graphene/polymer composites. In this paper, the effects of ultrasonic intensity and reaction time on the molecular weight and yield of PMMA under supercritical CO2 conditions were investigated. It was found that there are threshold and optimal values of ultrasonic intensity for initiating the reaction in supercritical CO2 system. The threshold value is 150 W/cm2 and the optimal ultrasonic intensity value is 225 W/cm2. There is also an optimal value of ultrasonic initiation time for ultrasonic initiation polymerization. Combining the reaction yield and the molecular weight of the product, 2 h of ultrasonic initiation is a suitable initiation reaction time. Based on the synthesis of PMMA by ultrasonic excitation, the preparation of Graphene/PMMA composites by ultrasound assistance was also investigated. The TG and DTG characterization of PMMA and complex materials prepared by ultrasonic excitation showed that the radicals generated by ultrasonic excitation were uniformly distributed and did not generate unsaturated double bonded polymers. The electrical conductivity of the Graphene/PMMA composites prepared by ultrasonic excitation at a graphene content of 1 wt% increased to 1.13 × 10-1 S/cm, which is better than that of the Graphene/PMMA prepared by in situ polymerization. This may be attributed to the ultrasound-assisted supercritical CO2 fluid action that resulted in a more uniform distribution of Graphene mixed with PMMA in the prepared composites. Therefore, it is of important practical significance for the preparation of Graphene/PMMA composites by ultrasound-induced polymerization.

Effect of ultrasonic intensity on structure and properties of wheat starch-monoglyceride complex and its influence on quality of norther-style Chinese steamed bread

The effect of ultrasonic intensity on the wheat starch-monoglyceride complex (WSG) and the influence of WSG on the quality of steamed bread were investigated. With the increase of ultrasonic intensity, the complex index (CI) of the WSG first increased and then decreased. X-ray diffraction showed that with the addition of monoglycerides, the crystal type of starch changed from A-type to V-type. Fourier transform infrared spectroscopy showed that the absorption peak of the WSG was weaker than that of the control, and the characteristic peaks of the WSG complex appeared. Compared to native starch, the resistant starch (RS) content of WSG increased. When the ultrasonic intensity was 375 W, the CI value and RS content of WSG samples reached the maximum. WSG treated with 375 W of ultrasonic intensity was added to the steamed bread. The results showed that WSG addition decreased the specific volume and springiness of steamed bread, but dramatically increased its spread ratio, hardness, and chewiness. However, the excessive addition of WSG was not conducive to the quality of steamed bread. Flour blends with 5-10% WSG produced steamed bread with total scores comparable to the control flour. The results would provide new insights into starch under ultrasound treatment.

The effect of ultrasonic intensity on physicochemical properties of Chinese fir

Cavitation intensity is affected by ultrasonic intensity (UI) and is a key parameter to describe experimental results during ultrasonic treatment. The relationship between the UI and physicochemical properties of Chinese fir was investigated. In this study, four frequencies (25, 28, 40, and 59kHz) were used at the same intensity of 240W and the same duration of 35min. The UI during the ultrasonic treatment was determined, and the chemical components were determined. The chemical structure, crystallinity, morphology, and extractives of wood were respectively analyzed by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and gas chromatography-mass spectrometry (GC-MS). The results showed that higher crystallinity was associated with a larger integrated area under the curve of the ultrasonic intensity (UIA). The largest UIA was observed at 25kHz, followed by those at 40, 59, and 28kHz. The relative content of hemicellulose was strongly affected by the ultrasonic treatment. No chemical reactions were observed in the wood, whereas the ultrasonic treatment affected the torus of the bordered pits and facilitated the migration of extractives. In general, the higher the UIA, the stronger the effect of the cavitation was. The most significant changes in the physicochemical properties were observed at 25kHz. The instantaneous ultrasonic intensity (IUI) changed over time, and the UIA was closely associated with changes in the physicochemical properties of the wood. The results of this study demonstrate that UI has a significant influence on the physicochemical properties of wood.

Effect of ultrasonic intensity on the conformational changes in citrus pectin under ultrasonic processing

In this study, the effects of ultrasonic intensity on conformational changes in aqueous citrus pectin solution under ultrasonic processing and its possible transition mechanism were investigated. The results demonstrated that higher ultrasonic intensity (104.7 W/cm2) caused larger alterations in the molecular and conformational parameters of the semiflexible pectin (Mark–Houwink relation exponent a: 0.820, conformational parameter α: 0.607, structural parameter ρ: 2.22) in aqueous solution. Meanwhile, the semiflexible chain of pectin became more flexible (a: 0.804, α: 0.601, ρ: 1.75) at higher ultrasonic intensity in aqueous solution, as was verified by atomic force microscopy. Moreover, conformational changes in pectin from semiflexible chains to flexible chains or even flexible coils (a: 0.791, α: 0.597, ρ: 1.70) could be attributed to the decreased degree of methoxylation and neutral sugars in side chains and the destruction of inter- and intramolecular hydrogen bonds under ultrasonic processing. Therefore, these results have important implications for understanding the ultrasonic modification of pectin.

Preparation and wear assessment of ultrasonic electrodeposited Ni–TiN thin films

In this study, pure Ni and Ni–TiN thin films were prefabricated from a reformative Watt nickel bath through ultrasonic electrodeposition (UE) under pulse current (PC) condition. The effects of ultrasonic intensity on surface morphology, microstructure and phase composition were evaluated through scanning electron microscopy (SEM), scanning probe microscopy (SPM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The Vickers hardness, the friction coefficient and the wear resistance of Ni and Ni–TiN thin films were also estimated. All SEM, SPM, and TEM results demonstrated that the Ni-TiN thin film obtained at the ultrasonic intensity of 30 W/cm2 had a fine, smooth and homogeneous surface morphology. The root-mean-square roughness (Rms) and arithmetic mean roughness (Ra) of the film with a surface area of 4.096 µm2 were 36.813 nm and 22.836 nm, respectively. Also, the mean diameters of Ni grains and TiN nanoparticles were approximately 46.7 nm and 23.2 nm, respectively. The XRD analysis indicated that the XRD patterns of the films prepared with different plating parameters had the same diffraction angle with the Ni phase except the diffraction intensity. Microhardness tests exhibited that the Ni film displayed the minimum microhardness value of 38.6 HV. Moreover, the Ni-TiN film obtained at the ultrasonic intensity of 30 W/cm2 acquired the maximum microhardness value of 912.1 HV. The wear behavior assessment demonstrated that the Ni-TiN film prefabricated at the ultrasonic intensity of 30 W/cm2 sustained the least weight loss, while the mean friction coefficient was approximately 0.39, thereby displaying the best wear resistance.

Ultrasound assisted, thermally activated persulfate oxidation of coal tar DNAPLs

The feasibility of ultrasound assisted, thermally activated persulfate for effective oxidation of twenty 2–6 ringed coal tar PAHs in a biphasic tar/water system and a triphasic tar/soil/water system were investigated and established. The results indicate that ultrasonic assistance, persulfate and elevated reaction temperature are all required to achieve effective oxidation of coal tar PAHs, while the heating needed can be provided by ultrasonic induced heating as well. Further kinetic analysis reveals that the oxidation of individual PAH in the biphasic tar/water system follows the first-order kinetics, and individual PAH oxidation rate is primary determined by the mass transfer coefficients, tar/water interfacial areas, the aqueous solubility of individual PAH and its concentration in coal tar. Based on the kinetic analysis and experimental results, the contributions of ultrasound, persulfate and elevated reaction temperature to PAHs oxidation were characterized, and the effects of ultrasonic intensity and oxidant dosage on PAHs oxidation efficiency were investigated. In addition, the results indicate that individual PAH degradability is closely related to its reactivity as well, and the high reactivity of 4–6 ringed PAHs substantially improves their degradability.

Poly(vinylidene fluoride) membranes by an ultrasound assisted phase inversion method

Poly(vinylidene fluoride) (PVDF) membranes were prepared by an ultrasound assisted phase inversion process. The effect of ultrasonic intensity on the evolution of membrane morphology with and without the addition of pore former LiCl during precipitation process was comprehensively investigated. Besides the inter-diffusion between the solvent and nonsolvent, the ultrasonic cavitation was thought to have significant influences on phase inversion and the resultant membrane morphology. The mutual diffusion between water and solvent during the ultrasound assisted phase inversion process was measured. The crystalline structure was detected by wide angle X-ray diffractometer (WAXD). The thermal behavior was studied by differential scanning calorimeter (DSC). The mechanical strength, forward and reverse water flux, rejection to bovine serum albumin (BSA) and pepsin were also investigated. By the ultrasound assisted phase inversion method, ultra-filtration membrane was successfully prepared, which exhibited more preferable morphology, better mechanical property and more favorable permeability without sacrificing the rejection and thermal stability.

Ultrasonic-assisted manufacturing processes: Variational model and numerical simulations

We present a computational study of ultrasonic assisted manufacturing processes including sheet metal forming, upsetting, and wire drawing. A fully variational porous plasticity model is modified to include ultrasonic softening effects and then utilized to account for instantaneous softening when ultrasonic energy is applied during deformation. Material model parameters are identified via inverse modeling, i.e. by using experimental data. The versatility and predictive ability of the model are demonstrated and the effect of ultrasonic intensity on the manufacturing process at hand is investigated and compared qualitatively with experimental results reported in the literature.

Effect of Ultrasonic Intensity on the Degradation of Phenol Solution

Effect of ultrasonic intensity on the degradation of phenol solution is investigated by changing the nominal ultrasonic power, ultrasonic frequency and the position of reactor. The actual ultrasonic intensity (I) that reaches reactor is measured by ultrasonic power measuring meter. It can be found that the ultrasonic intensity varies with ultrasonic parameters. With the nominal power input improving from 60 W to 150 W, the ultrasonic intensity rises from 0.21 W•cm-2 to 1.06 W•cm-2 and the degradation rate of phenol solution (η) increases from 21.7% to 43.7%. However, when I reaches the highest value of 1.71 W•cm-2 at the frequency of 100 kHz, η decreases to the lowest value of 21.5%. The ultrasonic intensity distribution is uneven in the ultrasonic bath and η increases with an increase of I in the vertical direction. The ultrasonic degradation of phenol solution is affected by ultrasonic intensity, but η doesn’t definitely increase with an increase of ultrasonic intensity.

Ultrasonic induced grafting of maleic anhydride onto polypropylene in melt state

This paper presented a model study on maleic anhydride (MAH) grafted polypropylene (PP) performed in melt state through ultrasonic initiation without any chemical initiator and solvent. The structures of PP-g-MAH were characterized by FTIR and 13C NMR and the mechanism were discussed. The graft degree (G) was determined by titration using a solution of organic base tetra-butyl ammonium hydroxide (TBAOH) in ethanol, and the effects of ultrasonic intensity, MAH concentration and styrene (St) on G and graft efficiency (G E ) of MAH were investigated. Results showed that MAH was successfully grafted onto the PP chain and the optimum conditions for grafting were at an ultrasonic intensity of 300 W with a MAH concentration of 25 wt.%, and the maximum G of MAH of 3.34 wt.% was obtained when the molar ratio of St to MAH was 1:1. DSC and XRD were also employed to determine the thermodynamic performance and crystalline structures of the products.

Effect of high-intensity ultrasonic field on process of semi-continuous casting for AZ80 magnesium alloy billets

Under the high-intensity ultrasonic field, AZ80 magnesium alloy was semi-continuously cast. The effects of ultrasonic intensity on the as-cast microstructures and mechanical properties were investigated. The results show that the microstructures of the alloy cast under high-intensity ultrasonic field are fine and uniform, and the grains are equiaxed, rose-shaped or globular with an average size of 257 μm. High-intensity field significantly decreases the grain size, changes the morphologies of the β-Mg17Al12 phases and reduces their area fraction. It is also shown that a proper increase in ultrasonic intensity is helpful to obtain fine, uniform and equiaxed as-cast microstructures. The optimum ultrasonic parameters are that frequency is 20 kHz and ultrasonic intensity is 1 368 W. The mechanical tests show that the mechanical properties of the as-cast AZ80 magnesium alloy billets cast under ultrasonic field are greatly improved, and with increasing the ultrasonic intensity, the mechanical properties of the entire alloy billets are much higher and more uniform than those of the alloy without ultrasonic field.

Effects of Ultrasonic Waves on Vapor-Liquid Equilibrium of an Azeotropic Mixture

Azeotropic and extractive distillation techniques used to separate azeotropic mixtures are among the most challenging separation processes in the chemical industry. In this work, an innovative distillation technique which employed ultrasonic waves was proposed to intensify the conventional multi-column azeotropic distillation method into a single-column alternative. The effects of ultrasonic intensity on the vapor-liquid equilibrium (VLE) of methyl-tert-butyl-ether (MTBE)-methanol was investigated at 50, 100, 200, and 250 W/A·cm2 and at a fixed frequency of 40 kHz. Studies were also done to examine the effects of ultrasonic frequency on the VLE data at 25 and 68 kHz frequencies. It was found that ultrasonic waves at 50 W/A·cm2 intensity and 25 kHz frequency gave the highest relative volatility (α) at 2.654 and completely eliminated the MTBE-methanol azeotrope, thereby allowing highly pure MTBE to be recovered in just a single distillation column. The results revealed that ultrasonic waves had the potential to favorably manipulate α, and hence, the VLE of an azeotropic mixture.

Combined Ultrasonic and Enzymatic Debridement of Necrotic Eschars in an Animal Model

Several methods are used to debride burn eschars, however, most are ineffective for ischemic eschars. We investigated a novel combination of enzymatic and ultrasonic debridement for ischemic eschars. A previously described ischemic flap model in rats was used to compare the time to flap debridement or perforation of enzymatic (Debrase, a derivative of bromelain), ultrasonic, or combined debridement (Hybrid Debridement Technology). We also evaluated the effects of ultrasonic intensity, probe size, probe housing, and operation mode (pulsatile vs. continuous) on the time to full eschar perforation. Ultrasonic and enzymatic debridement alone did not result in flap perforation even after 15 minutes. Combined ultrasonic and enzymatic debridement resulted in flap perforation within 2 to 5 minutes in the four flap zones (P < 0.001 for all four flap zones compared with ultrasound alone). The most rapid debridement was observed with an ultrasonic intensity of 3.2 W/cm, applied using a 4.9 cm probe. The temperature elevation associated with ultrasonication was controlled by perfusion of fresh Debrase solution and alternating the ultrasound energy. Combination of ultrasonic and enzymatic debridement of ischemic flap eschars in rats with Debrase is more rapid and effective than either method alone.

Ultrasonic irradiation-induced degradation of low-concentration bisphenol A in aqueous solution

The treatment of bisphenol A (BPA)-contaminated water has attracted great interest recently. In this contribution, ultrasound (US) was applied to remove low-concentration BPA in aqueous solution at the frequency of 20 kHz, and the effects of ultrasonic intensity and ozone on BPA removal were evaluated for the first time. Considering the coexistence of halomethanes and BPA in chlorinated drinking water, BPA was degraded under US in the presence of CCl 4. In addition, the main intermediates resulting from BPA ultrasonic degradation were identified by gas chromatography–mass spectrometry. On the basis of these studies, OH radical induced oxidation was identified as the major destruction pathway during BPA sonolysis.

Kinetics of Solvent-Free C-Alkylation of Phenylacetonitrile Using Ultrasonic Irradiation

The C-alkylation of phenylacetonitrile in a solvent-free liquid–liquid system using phase transfer catalysis under ultrasonic irradiation was investigated. The effects of ultrasonic intensity, inner diameter of the reactor and concentrations of the phase transfer catalyst as well as the potassium hydroxide on the reaction rate were examined. The ultrasonic intensity had an optimum value for the reaction rate. The effect of the ultrasound to promote the reaction was attributed to the extremely large interfacial area between the two liquid phases. The high intensity ultrasound generated a large number of cavitation bubbles in the vicinity of the surface of the ultrasonic horn tip. Those bubbles prevented the acoustic stream induced by ultrasound from propagating to the bottom of the reactor, so that not many emulsion drops existed in the reactor, and the reaction rate was low. The reaction rate using ultrasonic irradiation was much faster than that using mechanical agitation. The reactor with smaller inner diameter produced a faster reaction rate. The reaction rate increased with the concentrations of TBAHS and potassium hydroxide.

Functionalization of high density polyethylene in melt state through ultrasonic initiation and its effect on mechanical properties of glass fiber reinforced composites

Functionalization reaction of high density polyethylene (HDPE) with γ-methacryloxy-propyltrimethoxysilane (MAS) or with MAS and MAH performed in melt state through ultrasonic initiation by a laboratory-scale ultrasonic extruding reactor was studied in this paper. The effect of ultrasonic intensity on the percentage of grafting and melt flow rate of the functionalized products was investigated. The results show that by imposing ultrasonic vibration during melt-extruding process, the scission of HDPE chain bonds can be caused to form macroradicals, the functionalization reaction of HDPE with MAS or with MAS and MAH can be realized. The percentage of grafting and the melt flow rate of the functionalized products depend upon the ultrasonic intensity and reaction temperature. The fuctionalization reaction of HDPE with MAS can be promoted by adding a second grafting monomer MAH. The ultrasonic-induced products have a higher reactivity with the coupling agents coated on the surface of glass fibers, the mechanical properties of the composite improved by the ultrasonic induced product are higher than that of by peroxide initiated product and the mechanical properties of HDPE/GF composite modified by HDPE-g-MAH-MAS are higher than that of by HDPE-g-MAH. The SEM experimental results indicate that an oriented crystal layer exists between the interface of glass fiber and the HDPE matrix, the interfacial bonding strength is the determining factor of the formation of the oriented crystal layer.

Functionalization of polyolefins with maleic anhydride in melt state through ultrasonic initiation

The functionalization reaction of high-density polyethylene (HDPE), linearly low-density polyethylene (LLDPE), polypropylene (PP) and EPDM rubber with maleic anhydride (MAH) in melt state through ultrasonic initiation was studied. The effect of ultrasonic intensity on the percentage of grafting, viscosity–average molecular weight, melt flow rate and gel content of the functionalized products were investigated by means of chemical titration, Fourier-transform infra-red spectroscopy (FT-IR), intrinsic viscosity and melt flow rate, etc. The molecular structures of the functionalized products prepared via ultrasonic initiation and via peroxide initiation were characterized by 1H NMR spectroscopy. The results show that the functionalization reaction of HDPE, LLDPE and EPDM with MAH can be realized by ultrasonic initiation. This reaction mainly consists of the chain scission under ultrasonic irradiation, the end chain reaction of the produced macroradicals with MAH, and the terminated reaction of the produced succinyl radicals with the macroradicals or H* radicals through recombination or dismutation. The functionalized product through ultrasonic initiation mainly consists of the products containing an anhydride ring attached to the chain terminus. And the products prepared through peroxide initiation mainly contain an anhydride ring grafted on the side chain.

Liquid-phase adsorption and desorption of phenol onto activated carbons with ultrasound

The effect of 48-kHz ultrasound on the adsorption and desorption of phenol from aqueous solutions onto coconut shell-based granular activated carbons was studied at 25 °C. Experiments were performed at different carbon particle sizes (1.15, 2.5, 4.0 mm), initial phenol concentrations (1.06–10.6 mol/m 3), and ultrasonic powers (46–133 W). Regardless of the absence and presence of ultrasound, the adsorption isotherms were well obeyed by the Langmuir equation. When ultrasound was applied in the whole adsorption process, the adsorption capacity decreased but the Langmuir constant increased with increasing ultrasonic power. According to the analysis of kinetic data by the Elovich equation, it was shown that the initial rate of adsorption was enhanced after sonication and the number of sites available for adsorption was reduced. The effect of ultrasonic intensity on the initial rate and final amount of desorption of phenol from the loaded carbons using 0.1 mol/dm 3 of NaOH were also evaluated and compared.

Degradation kinetics of polystyrene and EPDM melts under ultrasonic irradiation

The ultrasonic degradation of polystyrene (PS) and ethylene–propylene diene monomer (EPDM) melts was conducted in a specially designed reactor. A degradation model of polymer melts was proposed to explain the ultrasonic degradation, and degradation of polymer melts is treated as a mechanochemical process. Ultrasonic degradation kinetics obeys the equations: M t = M ∞ + A ⅇ − k t or [ η ] t = [ η ] ∞ + ( [ η ] 0 − [ η ] ∞ ) ⅇ − k t . The experimental results show that the molecular weight or intrinsic viscosity of polymer melts decreased with ultrasonic irradiation time and approached a limiting value, below which no further degradation took place. Different from ultrasonic degradation of polymer solutions, the scission of chains in polymer melts is random in the initial stage, and then non-random. FTIR spectra of samples ultrasonically treated and untreated confirmed that the initial product of ultrasonic degradation in polymer melts is a macroradical. The effects of ultrasonic intensity and reaction temperature on degradation of PS and EPDM melts were also investigated. The significant results showed that the degradation rate, the limiting value and degradation extent are correlated greatly with the experimental conditions.