High Ultrasonic Energy Research Articles

Research and optimum selection of coupling agent materials in ultrasonic measurement

In the detection of metal defects by ultrasonic Lamb waves, the commonly used medical coupling agent is volatile, poor stability, and the coupling effect is easily affected. It is vital to find the coupler materials with better performance. This paper develops sodium alginate hydrogel and acrylamide hydrogel with higher curing degree, and compares them with deionized water and medical coupling agent. At the same time, epoxy glue and organic silicone, which commonly used as adhesives in the aerospace field are selected for performance research. Firstly, analyzing FTIR spectra of the three hydrogels. The results showed that the hydrogel composition are correct and subsequent experiments are reliable. Secondly, the performance characteristics of 6 couplings are studied from 5 aspects of acoustic impedance, ultrasonic energy transfer efficiency, stability, temperature characteristics and oxidation resistance. The results show that the acrylamide gel developed in this paper has higher viscosity and stability than the medical coupling agent, and has a wider application. Based on the five performance studies, it can be concluded that in the measurement environment of long-term fixed sensors in the industrial and aerospace fields, organic silicone can not only play the role of bonding sensors and insulation, but have the advantages of strong stability, high ultrasonic energy transfer efficiency, temperature tolerance, oxidation resistance, etc. It is the optimal coupling material in ultrasonic testing for complex environments. The research in this paper provides a reference for the selection of optimal coupling agent materials for more complex applications, which has important engineering significance.

Cement Composites with Graphene Nanoplatelets and Recycled Milled Carbon Fibers Dispersed in Air Nanobubble Water.

The individual effect of nano- and micro-carbon-based fillers on the mechanical and the electrical properties of cement paste were experimentally examined in this study. The objective of the study was to separately examine the effects of size and morphology (platelets and fibers) of nano- and micro-reinforcement. Three different sizes of Graphene Nanoplatelets (GNPs), at contents of 0.05% and 0.20% and recycled milled carbon fibers (rCFs), at various dosages from 0.1–2.5% by weight of cement, were incorporated into the cementitious matrix. GNPs and rCFs were dispersed in water with air nanobubbles (NBs), an innovative method that, compared to common practice, does not require the use of chemicals or high ultrasonic energy. Compressive and bending tests were performed on GNPs- and rCFs-composites. The four-wire-method was used to evaluate the effect of the conductive fillers on the electrical resistivity of cement paste. The compressive and flexural strength of all the cementitious composites demonstrated a considerable increase compared to the reference specimens. Improvement of 269.5% and of 169% was observed at the compressive and flexural strength, respectively, at the GNPs–cement composites incorporating the largest lateral size GNPs at a concentration of 0.2% by weight of cement. Moreover, the rCFs–cement composites increased their compressive and flexural strength by 186% and 210%, respectively, compared to the reference specimens. The electrical resistivity of GNPs- and rCFs-composite specimens reduced up to 59% and 48%, respectively, compared to the reference specimens, which proves that the incorporation of GNPs and rCFs can create a conductive network within the cementitious matrix.

Nanoparticle sizing by focused-beam dynamic ultrasound scattering method

When nanoparticles in Brownian motion in liquid are irradiated with ultrasonic waves in the megahertz frequency range, scattering from the particles occurs, albeit at a very low intensity. The diffusion coefficient and the corresponding particle size can be calculated by analyzing the time correlation function of the ultrasound pulses. Since ultrasonic waves with long wavelengths in comparison with the particle size are unfavorable for detecting such small particles, increasing the energy of the ultrasonic waves is a primary solution. Increasing the energy, conversely, causes an unexpected acoustic flow. Consequently, a method using a strong ultrasound pulse while suppressing this acoustic flow field is required. In this study, we apply (1) a focused transducer with high ultrasonic energy, (2) a high-frequency sensor enhancing scattering performance, and (3) a short pulse repetition time to achieve high-speed and high-precision nanoparticle measurement while confining the sample in a narrow space to eliminate the acoustic flow. This enables direct tracking of nanoparticle motion by observing diffusive motion without perturbation particle dynamics. We specifically investigated a suspension of silica particles with a hydrodynamic radius of 15 nm and also achieved particle size discrimination in mixtures. The time correlation analysis using megahertz ultrasound pulses also takes advantage of ultrasonic waves’ inherent advantages, such as high-speed, high-precision particle size analysis in the submicron range beyond the wavelength of visible light.

The Effect of Ultrasonic Liposuction Energy Levels on Fat Graft Viability.

The use of fat obtained from ultrasound-assisted liposuction is popular. However, no study has considered the effect of different energy levels on fat grafts. We hypothesized that different ultrasonic energy levels could change the fat graft viability. Both flanks of 15 CD1 nude mice (30 experimental areas) were used, with experimental areas randomly distributed into five groups. Using different energy settings, fat grafts were obtained from a patient's abdominoplasty material and applied to the mouse flank regions. Device settings were intermittent mode with 50% vibration amplitude in group 1, continuous mode with 50% vibration amplitude in group 2, intermittent mode with 90% vibration amplitude in group 3, and continuous mode with 90% vibration amplitude in group 4. The control group was grafted with fat obtained via the conventional method. After 6 weeks, all mice were sacrificed, and fat grafts were excised. Sections were stained with hematoxylin-eosin, Masson's trichrome, and anti-perilipin A antibody. The perilipin A immunostaining result was lowest in group 4, indicating the lowest viable cell count (p < 0.01). There was no significant difference between groups for the other parameters (p > 0.05). High ultrasonic energy may affect fat graft survival. If fat injection is planned, avoiding high energy settings (our recommendation is not to exceed 16 Watts.) should be considered. We also recommend increasing the vibration amplitude rather than switching from intermittent to continuous mode in body parts that are relatively resistant to liposuction. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Ultrasound-assisted theophylline polymorphic transformation: Selective polymorph nucleation, molecular mechanism and kinetics analysis

In this paper, the ultrasound-assisted solvent-mediated polymorphic transformation of theophylline was explored in detail. The induction time and reconstruction time were significantly decreased by ultrasound, thereby decreasing the total transformation time and promoting the transformation process. The ultrasound-promoted efficiency of nucleation was different in three alcoholic solvents, which was difficult to explain by traditional kinetic effects. To resolve the above confusion, binding energies calculated by Density Functional Theory were applied to explore the relationship between the ultrasound-promoted efficiency of nucleation and solute–solvent interactions. Then, a possible molecular self-assembly nucleation pathway affected by ultrasound was proposed: the ultrasound could change and magnify the crucial effect of the specific sites of solute–solvent interactions in the nucleation process. Finally, the transformation kinetics with different effective ultrasonic energies was quantitatively analyzed by Avrami-Erofeev model, indicating that the dissolution element in the rate-limiting step was gradually eliminated by higher ultrasonic energy. Fortunately, the elusive crystal form V could be easily obtained by the ultrasound-assisted polymorph transformation. This proved to be a robust method to produce high purity form V of theophylline. The outcome of this study demonstrated that the proper ultrasonic irradiation had the potential to produce specific polymorphs selectively.

Self-cleaning of SiO2-TiO2 coating: Effect of sonochemical synthetic parameters on the morphological, mechanical, and photocatalytic properties of the films

Among the different properties of the hydrophobic semiconductor surfaces, self-cleaning promoted by solar illumination is probably one of the most attractive from the technological point of view. The use of sonochemistry for nanomaterials' synthesis has been recently employed for the associated shorter reaction times and efficient route for control over crystal growth and the management of the resulting material's photocatalytic properties. Moreover, the sol–gel method coupled to sonochemistry modifies the chemical environment, with reactive species such as •OH and H2O2, which yield a homogeneous synthesis. Therefore, in the following investigation, the sol–gel method was coupled to sonochemistry to synthesize a SiO2@TiO2 composite, for which the sonochemical amplitude of irradiation was varied to determine its effect on the morphology and mechanical and self-cleaning properties. SEM and AFM characterized the samples of SiO2@TiO2 composite, and while the micrographs indicate that a high ultrasonic energy results in an amorphous SiO2@TiO2 composite with a low rugosity, which was affected in the determination of the contact angle on the surface. On the other hand, FTIR analysis suggests a significant change in both SiO2-SiO and SiO2-TiO2 chemical bonds with changes in vibrations and frequency, corroborating an important influence of the sonochemical energy contribution to the hydrolysis process. Raman spectroscopy confirms the presence of an amorphous phase of silicon dioxide; however, the vibrations of TiO2 were not visible. The evaluation of hydrophobic and self-cleaning properties shows a maximum of ultrasonic energy needed to improve the contact angle and rhodamine B (RhB) removal.

Modified phacoemulsification plus goniosynechialysis compared with conventional surgery for cataract and glaucoma.

Optic nerve damage and visual impairment caused by glaucoma affect 66.8 million people worldwide, and causing bilateral blindness in 6.7 million people. Surgery is the main method for the treatment of cataract with glaucoma. In recent years, clinicians have increasingly paid attention to and applied phacoemulsification and intraocular lens implantation combined with goniosynechialysis for the treatment of cataract with angle-closure glaucoma. However, for patients with complicated cataract, the high ultrasonic energy of traditional phacoemulsification can largely damage the corneal endothelium. Modified phacoemulsification (lower ultrasonic energy) and intraocular lens implantation have now achieved certain efficacy. The efficacy and safety of modified phacoemulsification plus goniosynechialysis compared with conventional surgery for cataract and glaucoma was investigated. A total of 125 patients who underwent goniosynechialysis combined with phacoemulsification and intraocular lens implantation were enrolled in the control group, while 179 patients treated by modified phacoemulsification and intraocular lens implantation combined with goniosynechialysis were enrolled in the research group. The visual acuity and intraocular pressure were observed before and 6 months after surgery in both groups, and the incidence of complications was analyzed. After treatment, there were more patients with visual acuity of 0.2–0.4 and >0.4 in the research group than in the control group (P<0.05). The incidence of corneal edema and anterior chamber inflammation was lower in the research group than in the control group (both P<0.05), while the preoperative and postoperative intraocular pressure, central anterior chamber depth, angle-opening distance, and peripheral iridocorneal adhesions were not significantly different between the two groups (all P>0.05). Modified phacoemulsification and intraocular lens implantation plus goniosynechialysis for cataract with glaucoma can better improve the visual acuity, as well as effectively reduce corneal edema and anterior chamber inflammation.

Effect of carbon nanotube length on the piezoresistive response of poly (methyl methacrylate) nanocomposites

Multiwall carbon nanotubes (MWCNTs) were systematically fragmented using high density ultrasonic energy and used as fillers of a poly (methyl methacrylate) matrix (PMMA). MWCNT fragmentation was confirmed by scanning electron microscopy and atomic force microscopy. Dedicated MWCNT length measurements yielded a log-normal statistical distribution, with mean value of 1.33 μm for the as-received MWCNTs and 0.66 μm for the fragmented MWCNTs. Higher electrical percolation threshold and lower electrical conductivity were obtained for MWCNT/PMMA composites (0.01–1 wt.% MWCNT concentration) using the fragmented MWCNTs. Higher electro-mechanical (piezoresistive) sensitivity under tensile tests was measured for PMMA nanocomposites with fragmented MWCNTs, which was explained by a competition of mechanisms related to the MWCNT length.

ULTRASONIC EFFECT ON ELECTRIC SPARK FORMING AND DEVELOPMENT IN ELECTROACOUSTIC SPRAYING

Introduction. The electroacoustic application of wear-resistance coatings is studied. The work objective is to obtain a mathematical model of the ultrasonic effect on the formation and development of an electric spark occurring in the process of the electroacoustic sputtering.Materials and Methods. The effect of ultrasonic vibrations on the processes occurring during the formation and development of a spark discharge is analyzed; the equations of continuity, energy motion and transfer, with the ultrasonic field contribution are considered. Factors affecting the thermal conductivity and electrical conductivity of strongly ionized gas are studied. Research Results. When obtaining the model, it was assumed that the heat removal from the channel is carried out by a “clear emitter”. Then, for the channel region, a self-similar solution is made: pressure, temperature and density are constant over the cross-section, and velocity is proportional to the radius. A mathematical model that describes the processes occurring in the spark channel with the ultrasonic field energy effect is obtained.Discussion and Conclusions. On the basis of the developed model, it is specified that under the ultrasonic radiation effect, the radius and temperature of the spark channel increase, and conditions of the double ionization under high ultrasonic energy are created.

Effects of ultrasonic vibration on performance and microstructure of AZ31 magnesium alloy under tensile deformation

Ultrasonic vibration can reduce the forming force, decrease the friction in the metal forming process and improve the surface quality of the workpiece effectively. Tensile tests of AZ31 magnesium alloy were carried out. The stress–strain relationship, fracture modes of tensile specimens, microstructure and microhardness under different vibration conditions were analyzed, in order to study the effects of the ultrasonic vibration on microstructure and performance of AZ31 magnesium alloy under tensile deformation. The results showed that the different reductions of the true stress appeared under various ultrasonic vibration conditions, and the maximum decreasing range was 4.76%. The maximum microhardness difference among the 3 nodes selected along the specimen was HV 10.9. The fracture modes, plasticity and microstructure of AZ31 magnesium alloy also were affected by amplitude and action time of the ultrasonic vibration. The softening effect and the hardening effect occurred simultaneously when the ultrasonic vibration was applied. When the ultrasonic amplitude was 4.6 μm with short action time, the plastic deformation was dominated by twins and the softening effect was dominant. However, the twinning could be inhibited and the hardening effect became dominant in the case of high ultrasonic energy.

Effect of ultrasound-enhanced fat separation on whey powder phospholipid composition and stability

Fat from freshly pasteurized liquid whey was partially separated by gravity for 5, 10, and 30min, with and without simultaneous application of ultrasound. Ultrasound treatments were carried out at 400 and 1,000 kHz at different specific energy inputs (23–390 kJ/kg). The fat-enriched top layers (L1) and the fat-depleted bottom layers (L2) were separately removed and freeze-dried. Nonsonicated and sonicated L2 powders were stored for 14d at ambient temperature to assess their oxidative stability. Creaming was enhanced at both frequencies and fat separation increased with higher ultrasonic energy, extended sonication, or both. The oxidative volatile compound content decreased in defatted whey powders below published odor detection threshold values for all cases. Sonication had a minor influence on the partitioning of phospholipids with fat separation. The current study suggested that ultrasonication at high frequency enhanced fat separation from freshly pasteurized whey while improving whey powder oxidative stability.

An Assessment of Risk of Fracture During Wirebond Over Active Circuits on ULK Dies

Mechanical integrity of the dielectric stack is challenged by the trend toward porous, lower dielectric constant interlayer dielectric (ILD) materials. During copper wirebonding over active circuits, the fracture of ultralow-k (ULK) dielectrics is a significant reliability challenge due to both the impact load and the high ultrasonic energy transmitted to the ILD stack. Thus, there is a need to assess the propensity of the ILD to fracture under the wirebonding process conditions. In this paper, a numerical investigation of the risk of fracture in ULK dies due to the Cu wirebonding process is presented. A recently developed computational technique for modeling cracks using behavioral approximations built directly on the geometrical model (enriched isogeometric analysis), as opposed to the analysis of a meshed geometry, is adopted to model damage in the ULK stacks. The cohesive damage induced in the ILD stack during the process steps, which is a measure of the risk of crack initiation, is used as an indicator of the reliability risk. The damage accumulation during the Cu wirebonding process is estimated to identify weak interfaces and potential sites for crack nucleation as well as damage nucleation patterns. Furthermore, the critical process condition at which crack nucleation is likely is identified by analyzing the damage induced during the impact and ultrasonic excitation stages. Also, representative ILD stack designs with varying Cu percentage are compared to assess the relative risk of fracture.

Effects of Amplitude on Carbon Nanotube Nanowelding

Electrophoretic deposition was used to deposite carbon nanotubes (CNTs) on Ti-coated silicon wafers. The effects of amplitude on the CNT nanowelding were studied. The results show that CNTs are compacted and bonded with Ti at the amplitude of 30%. At higher amplitude (60% and 80%), CNTs are cut short or even destructed due to the higher ultrasonic energy and shear force. Applying nanowelding to CNT field effect transistor, the on-off ratio and transconductance are enhanced significantly at the welding amplitude of 30%.

COD fractionation and denitrification potential of sonicated waste activated sludge liquids

This study characterized sonicated waste activated sludge (WAS) liquids as a possible carbon source for nitrogen removal. In this context, the effect of sonication density on chemical oxygen demand (COD) and nitrogen release was determined by particle size distribution (PSD) analysis and anoxic batch experiments. The increase in ultrasonic density from 0.8 W/mL to 1.6 W/mL had a slight impact on the soluble COD/total COD ratio. The high ultrasonic energy input increased the solubilization of nitrogenous organic substances and resulted in a low COD/TKN (total Kjeldahl nitrogen) ratio, which is not appropriate for nutrient removal systems. The change in ultrasonic power had a significant effect on COD fractionation of sonicated WAS liquid. The COD fraction at the size ranges higher than 1600 nm decreased from 44% to 3% as the energy input increased. The increase in specific energy raised the COD fraction, at the size ranges of<2 nm, from 11% to 23%.The PSD-based COD fractionation showed that increasing the sonication density markedly changed the size distribution. The anoxic batch tests indicated that the specific denitrification rate of sonicated WAS liquid was in the range of that reported for the slowly biodegradable fraction of the domestic wastewater and higher than those reported for agro-food wastewater.

Retraction Note: Enhancement of bio-sludge gravitational thickening with weak ultrasound

Gravitational thickening is the prevailing method to reduce bio-sludge volume though the process is slow and usually requires addition of polyelectrolyte(s). This paper investigated the potential benefits of sonication on enhancing the bio-sludge gravitational thickening with very low energy dose, thereby called “weak ultrasound”. Results showed that weak sonication significantly changed the bio-sludge settleability and the main mechanism was release of the loosely bound extracellular polymeric substances. The changes were strongly influenced by power density and sonication duration. Low frequency was better but the difference was insignificant. Weak sonication (<680 kJ/kg DS) improved the sludge gravitational thickening while high ultrasonic energy deteriorated the process. Considering both the sludge thickening efficiency and energy consumption, the optimum conditions were 0.15 W/ml, 7 s and 25 kHz. Under such conditions, the energy dose was only 155 kJ/kg DS, much lower than literature reports and the sludge settling time shortened from the original 24 to 12 h. Weak sonication could substitute expensive polyelectrolyte coagulant for bio-sludge thickening. Combination of weak sonication and polyelectrolyte could further reduce the settling time to 6 h. The final water content of the thickened bio-sludge was not changed after sonication or polyelectrolyte addition.

Enhancement of sludge gravitational thickening with weak ultrasound

Gravitational thickening is the prevailing method to reduce sludge volume but the process is slow and usually requires addition of polyelectrolyte(s). This paper investigated the potential benefits of sonication on enhancing the sludge gravitational thickening with very low energy dose, so called “weak ultrasound”. Results showed that weak sonication significantly changed the sludge settlability and the main mechanism was release of the loosely bounded extracellular polymeric substances. The changes in sludge behaviors by sonication were strongly influenced by power density and sonication duration. Lower sound frequency was slightly better than higher frequency. Weak sonication (<680 kJ·kg−1 DS) improved the sludge gravitational thickening while high ultrasonic energy deteriorated the process. Considering both the sludge thickening efficiency and energy consumption, the optimum conditions were 0.15W·mL−1, 7 s, and 25 kHz. Under such conditions, the energy dose was only 155 kJ·kg−1 DS, much lower than literature reports, and the sludge settling time was shortened from 24 h to 12 h. Weak sonication could substitute expensive polyelectrolyte coagulant for sludge thickening. Combination of weak sonication and polyelectrolyte could further reduce the settling time to 6 h. The final water content of the thickened sludge was not changed after sonication or polyelectrolyte addition.

Ondas ultra-sônicas de alta freqüência causam disfunção endotelial em artérias coronárias caninas epicárdicas

Application of ultrasound energy by an endarterectomy probe can facilitate the removal of atheromatous plaque, but the effect of this procedure on surrounding vessel structure and function is still a matter of experimental investigations. To determine whether ultrasound energy impairs the production of nitric oxide or damages vascular smooth muscle function, isolated canine epicardial coronary artery segments were exposed to either high (25 W) or low (0-10 W) ultrasonic energy outputs, for 15 seconds, using an endarterectomy device prototype. After exposure, segments of epicardial coronary artery were studied in organ chambers. The following drugs were used: adenosine diphosphate (ADP), acetylcholine (Ach) and sodium fluoride (NaF) to study endothelium-dependent relaxation and sodium nitroprusside (SNP) and isoproterenol to evaluate endothelium-independent relaxation. Application of high ultrasonic energy power impaired endothelium-dependent relaxation to ADP (10(-9)-10(-4) M), Ach (10(-9)-10(-4) M) and NaF (0.5-9.5 mM) in epicardial coronary arteries. However, low ultrasound energy output at the tip of the probe did not alter the endothelium-dependent relaxation (either maximal relaxation or EC50) to the same agonists. Vascular smooth muscle relaxation to isoproterenol (10(-9)-10(-5) M) or SNP (10(-9)-10(-6) M) was unaltered following exposure to either low or high ultrasonic energy outputs. These experiments currently prove that ultrasonic energy changes endothelial function of epicardial coronary arteries at high power. However, ultrasound does not alter the ability of vascular smooth muscle of canine epicardial coronary arteries to relax.

Characterisation of aluminium alloy 6061 for the ultrasonic consolidation process

Ultrasonic consolidation (UC) is a freeform fabrication technique developed for the layered fabrication of metal parts. The process uses a high intensity ultrasonic energy source to induce combined static and oscillating shear forces within layers of metal foil to produce solid-state bonds. This paper will consider control parameter optimisation and surface preparation issues, for the production of aluminium alloy 6061 specimens. It will assess weld quality through both mechanical testing and optical observation. Aluminium 6061 specimens were successfully welded by the UC machine using both unprepared and surface prepared foils. In the unprepared specimens, thick oxide films exist along the whole specimen length of the weld interface. Results showed that the dynamic interfacial stresses, generated under UC conditions, compact the oxide layer to form brittle, ceramic bonds at the weld interface. A simple cleaning procedure increased metallurgical bonds, within the weld interface, by up to 45%. A general process window was produced for 6061 alloy based on a combination of the peel test data and microstructural analysis.

The Removal of Submicron Particles in Liquid-Based Cleaning

Megasonic cleaning is one of the most widely used wet-cleaning processes in the semiconductor, hard disk and flat panel display industries. Presented results involve different and new techniques for introducing the high frequency ultrasonic energy in the cleaning bath. The effects of power, temperature and time on the removal efficiency of Si3N4 particles in the size range from 0.1 μm to 1.0 μm from silicon wafers are presented. Results show that removal efficiencies near 100% for silicon nitride particles using deionized water could be achieved under the right conditions. The megasonic input power has a greater effect on the removal efficiency than does temperature.

Apparatus for applying high frequency ultrasonic energy to cleaning and etching solutions

An improved apparatus for coupling ultrasonic energy from piezoelectric transducers to a liquid medium for use in cleaning or etching processes. The apparatus includes a vibration coupling plate which may be partially immersed in the liquid medium, while the upper, nonimmersed end of the plate is configured to support a pair of piezoelectric transducers disposed at 45 degree angles with respect to the lengthwise axis of the plate. The beams of ultrasonic mechanical wave energy are therefore reflected back and forth from the side edges of the plate and dispersed over a wider angle in the liquid.