Application Of Ultrasonic Waves Research Articles

USEFULNESS OF AN ULTRASONIC SCALPEL TO HARVEST AND SKELETONIZE THE SUPERFICIAL TEMPORAL ARTERY FOR EXTRACRANIAL-INTRACRANIAL BYPASS SURGERY

A new method to harvest and skeletonize the superficial temporal artery (STA) using an ultrasonic scalpel is presented. The technique is simple and safe, and reduces bleeding. We also investigated histopathological changes in donor vessels and whether it is possible to shorten the time needed for STA harvesting using the ultrasonic scalpel. Between January 1, 2005, and December 31, 2007, 31 consecutive patients underwent STA and middle cerebral artery anastomosis surgery in our hospital. All patients underwent harvesting of both the frontal and parietal branches of the STA. STA harvesting using an ultrasonic scalpel was performed in 18 of the 31 patients. We compared the time needed for STA harvesting by dividing patients into 2 groups: a non-ultrasonic scalpel group and an ultrasonic scalpel group. We also examined the histopathological changes by application of ultrasonic waves on the STA in the 6 most recent patients. The mean time needed for STA harvesting was 84.2 +/- 14.1 minutes for the non-ultrasonic scalpel group and 55.1 +/- 15.2 minutes for the ultrasonic scalpel group. The ultrasonic scalpel group showed a significantly shorter harvesting time than the non-ultrasonic scalpel group (P < 0.01). No histopathological change was observed in any layers of the STA. Our data suggest that STA harvesting with the ultrasonic scalpel may be useful for STA-middle cerebral artery anastomosis surgery.

Effects of ultrasound on the performance improvement of wastewater microfiltration through a porous ceramic filter

Filtration under an ultrasonic field is a technique that is gaining importance in the wastewater treatment research field, not only due to its ability as a cleaning mechanism, but also as a filtration intensifier. The main objective of this research was the study of the influence of ultrasonic waves on the filtration of theoilfield wastewater (known as produced water) in order to increase the operation performance and filter medium regenerative effectiveness. A 0.016 m² hollow cylindrical porous ceramic filter was submitted to the filtration of produced water by two mechanisms: conventional filtration under vacuum and filtration under theinfluence of ultrasonic waves. Experiments were carried out using synthetic produced water by analyzing the variables oil and grease content (O&G) and total suspended solids (TSS) for each filtration run. Backwashing of the filter medium with distilled water was also performed to evaluate the regeneration efficiency. During conventional filtration, permeate flux decreased gradually, becoming stable around 0.06 cm³.cm-2.s-1. Furthermore, in the filtration assisted by ultrasound, the permeate flux was around 0.15 cm³.cm-2.s-1. Therefore, ultrasonic waves provided an increase of about 150% in the permeate flux. Moreover, the sonication improved filter medium regeneration effectiveness, even under conditions of high TSS and O&G contents. Taking into consideration the very positive results associated with the application of ultrasonicwaves, this filtration technique is likely to become an important industrial process.

A polymeric chip for micromanipulation and particle sorting by ultrasounds based on a multilayer configuration

A new polymer microchip is presented in this paper for separation and particle sorting in flowing suspensions. It includes a microchannel where a fluid-sample containing particles flows in parallel with another liquid. The working principle is based on an ultrasonic actuation on the cross-section of the chip, which behaves as a multilayer system. That part of the wave established within the channel includes a node of pressure strategically located within the collector fluid path, where the target particles collected to be extracted from their host sample. The use of a polymer as the constitutive material of the chip, new in this type of devices, allows a channel width somewhat larger than a quarter of a wavelength, which does not fit any of the conventional models but it represents an intermediate situation. The device has been fabricated by standard SU-8 photolithography using PMMA as substrate. In the experiments, polystyrene particles of 20 μm in diameter have been extracted from aqueous suspensions containing 6-μm sized particles by a strategic application of ultrasonic waves. A high efficiency of particle separation, over 95%, at different concentrations and flow rates, prove the feasibility of the device to carry out sorting processes on flowing suspensions.

Study of application of ultrasonic wave to injection molding

AbstractWe have developed an ultrasonic injection molding (UIM) system, which applies ultrasonic waves to injection molding, as a precision injection molding technology. Molding of optical lenses showed that the lens weight increased when the ultrasonic wave was applied immediately after the resin was filled into a cavity. Results showed that, by applying ultrasonic waves, oscillatory flow was generated inside the cavity and consequently the weight of the lens was increased. The surface finish of the molded lens was also significantly improved in UIM when compared with that in conventional molding. The part of shrinkage during the packing and holding stages was suppressed by the oscillatory flow provided by the ultrasonic vibration. Because of ultrasonic energy absorption, local heating was generated inside the resin, resulting in the formation of oscillatory flow during packing and holdingstages. Local heating, occurring especially between molten and skin layers, reduces the skin layer's deformation resistance. Consequently, replication during the packing and holding stages is facilitated by the UIM. Moreover, evaluation of the residual optical strain of concave lens revealed that the strain was much lower in UIM than in conventional molding. The decreased strain was attributed to the local heat generation by the ultrasonic waves. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Effect of Ultrasonic Waves on the Formation of TiO&lt;sub&gt;2&lt;/sub&gt; Nanotubes by Electrochemical Anodization of Titanium in Glycerol and NH&lt;sub&gt;4&lt;/sub&gt;F

The present work describes the anodic growth of self-organized TiO2 nanotubes (TiNT) on titanium samples in an electrolyte containing 3% NH4F and 5% H2O in glycerol. Two stages anodization were proceeded. Initially, the potential was ramped from 0V to 30, 40 and 60 V. In the second stage the potential was held at the given potential up to 5 hrs. The application of ultrasonic waves during anodization was found to increase the reaction rates as it decreased the concentration gradient of the anodization products around the electric double layer. This resulted in high current and faster growth rates of the nanotubes. The diameters of the TiNT created under ultrasonic wave condition were found to be smaller than the corresponding TiNT created under magnetic stirring. However, the morphology of the TiNT was badly affected as a result of surface perturbation resulting from heterogeneity in surface energy density. A better route for good looking TiNT is to grow them under magnetically stirred solution followed by cleaning by sonication in deionized water for 30 seconds. Increasing the anodization potential from 30 to 60 V increased the dimensions of the TiNT from around 90 nm to around 150 nm, respectively. [DOI: 10.1380/ejssnt.2009.84]

Ultrasonic Field Effects on Corona Discharge in Air

The application of ultrasonic waves on corona discharge causes the existence of pressure gradients in the discharge gap. According to Meek's criterion, formation of streamers in the discharge and therefore the discharge profile is affected by these pressure gradients. We calculated the distribution of ultrasonic pressure in the interelectrode gap and we demonstrated experimentally that the discharge profile is affected by this ultrasonically induced pressure distribution.

Application of ultrasonic waves in activation of microcrystalline cellulose

AbstractIn this work, microcrystalline cellulose (MCC) was activated with ultrasonic waves. The influences of ultrasonic treatment on the changes of supramolecular structures and morphology structure were studied by WAXS and SEM. The accessibility of the MCC was characterized by water retention value (WRV) and specific surficial area. The influence of ultrasonic treatment on the reactivity of MCC was investigated through the reaction of MCC being oxidized into 2,3‐diadehyde cellulose (DAC) by periodate sodium. The mechanism of the reactivity change of ultrasonically treated MCC was examined. The results showed that the degree of crystallinity of MCC decreased and the degree of polymerization showed little change after treatment with ultrasonic waves. The morphologial variation of the treated MCC was significant when compared with the untreated MCC, which contribute to the improvement of accessibility. The aldehyde content of DAC prepared from ultrasonically treated MCC was improved from 64.19 to 85.00%, indicating that the regioselective oxidation reactivity of MCC was significantly improved. The aldehyde content was found to first increase with time of ultrasonic treatment to a point, and then decrease as time progressed. In addition, the aldehyde content was found to increase with an increase in ultrasonic power. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

An approach to design a high power piezoelectric ultrasonic transducer

Application of ultrasonic waves has been considerably progressed during the last decade and piezoelectric ceramics have had a common use as the driving source of such waves. However, there is not enough documented information on design and technology of manufacturing a high power ultrasonic transducer. In this paper, an attempt has been made to analyze the stress produced along the oscillating PZT employed ultrasonic head by applying the principles of acoustic wave propagation. Then, based on such analysis, general principles of PZT transducer design, excited by a DC-biased alternating electrical source, has been derived and finally a typical such transducer has been designed, manufactured and tested. By employing finite element modal analysis, the resonance frequency of the transducer was determined and compared with the experimental results. It was concluded that, the constitutive piezoelectric equations referred to in most sources and books are not valid for analyzing the acoustical dynamic stress in ultrasonic transducers. Instead, the analysis should be done with considering the dynamic behavior (elastic, damping and Inertia factors) of the problem.

Application of Ultrasonic Waves as a Priming Technique for Accelerating and Enhancing the Germination of Barley Seed: Optimization of Method by the Taguchi Approach

In this study the effects of different intensities and exposure time of ultrasound on barley seed have been investigated to determine the optimal conditions for accelerating germination. For optimization, the Taguchi approach was used. The germination rates and/or yield of the treated sample seed were compared with those of the untreated seed germinated under normal conditions. The seeds were treated with ultrasonic energy (input power 20-90% of 460W) and were exposed to three time periods ranging from 5 to 15 min. It was found that germination of the treated barley seed was increased about 1.042-1.065 times compared with that of the untreated seed. The ultrasonic treatment proved to be efficient in reducing the germination period by 30-45%. It was concluded that priming of seeds with ultrasound was effective in improving water uptake and germination. The data presented in this paper suggest that the increase in final germination percentage, together with the reduced germination period in treated seeds, may be due to the action of ultrasound and that it led to an improved hydration process with concurrent shell fragmentation.

A comparative study of ultrasonic cavitation and Fenton's reagent for bisphenol A degradation in deionised and natural waters

Bisphenol A (BPA), a xenobiotic that exhibits endocrine disrupting action can be found in surface water. Its complete elimination can be obtained by advanced oxidation processes, notably upon the application of ultrasonic waves. In order to evaluate the feature of ultrasound relevance and the involvement of the hydroxyl radical in the BPA sonochemical degradation, ultrasound action was compared to Fenton's reaction in the cases of deionised acidic water (pH 3) and natural water (pH 7.6, main ions concentration: Ca 2+ = 486 mg L −1, Na + = 9.1 mg L −1, Cl − = 10 mg L −1, SO 4 2− = 1187 mg L −1, HCO 3 − = 402 mg L −1). Ultrasound was performed at 300 kHz and 80 W. Fenton's process was operated using ferrous sulphate (100 μmol L −1) and continuous H 2O 2 addition at the rate as it is produced when sonication is applied in water in absence of substrate. Experiments carried out in deionised water show that both processes exhibit identical BPA elimination rate and identical primary intermediates. Main chemical pathways involve reactions with OH radical. Chemical oxygen demand (COD) and total organic carbon (TOC) analyses show that the Fenton's process is slightly more efficient than ultrasonic treatment for the removal of BPA by-products in the case of deionised water. Experiments conducted in natural water evidenced the inhibition of the Fenton process while the ultrasound action was not hampered.

すき間を有する SUS304 ステンレス鋼の腐食挙動に及ぼす超音波印加の影響

Anodic polarization testing of SUS304 stainless steel with crevice was carried out in an aqueous solution of 3.5 mass%NaCl at a potential increasing at a constant rate of 0.33 mV/s. When the current density reached 10, 12 or 50 A/m2, the potential was kept at a constant value for a constant period. When an ultrasonic wave (UW) was applied to the specimen during the holding period of the potential, the current density on the specimen surface was compared to that without the application of UW. Crevice corrosion and pitting corrosion were found on the specimen after the polarization test. The corrosion of specimen was largely decreased when UW was applied to the specimen. The current density almost synchronized with the cyclic application and stop of UW. The suppression of crevice corrosion and pitting corrosion in the specimen is attributed to the decrease in the enrichment of hydrogen ions and chloride ions in the crevice or pits by the stirring effect of UW.

Effect of Ultrasonic Wave on the Growth of Corrosion Pits on SUS304 Stainless Steel

Anodic polarization testing of SUS304 stainless steel was carried out in an aqueous solution of 3.5 mass% NaCl at a potential increasing at a constant rate of 20 mV/min. When the current density reached 2, 10 or 50 A/m 2 within the pitting corrosion region, the potential was kept at a constant value for 600 s at each current density. The ultrasonic wave (UW) was applied to the specimen from the beginning of test or just after the current density reached one of these constant values. The current density in these cases was compared with that without the application of UW. The results indicated that when the UW was applied from the beginning of test the current density was not affected by the application of UW in both the cathode and passive regions, but the increase in current density was suppressed by UW when the potential was kept at the constant value after the current density reached 10 or 50 A/m 2 . Also when the UW was applied just after the current density reached 2, 10 or 50 A/m 2 and the potential was kept at the constant value, the increase rate of current density was reduced by the application of UW. At the same time, the number and size of pits were decreased by the application of UW. The reason for the decrease in pitting corrosion was considered to be that UW destroyed the corrosion product on pits and the stirring effect of UW decreased the concentration of hydrogen and chloride ions in the pits, which accelerated the formation of a passive film on the pit wall. [doi:10.2320/matertrans.48.1017]

SUS304ステンレス鋼における腐食ピットの成長挙動におよぼす超音波印加の影響

Anodic polarization testing of SUS304 stainless steel was carried out in an aqueous solution of 3.5%NaCl at a potential increasing at a constant rate of 20 mV/min. When the current density reached 2, 10 or 50 A/m2 within the pitting corrosion region, the potential was kept at a constant value for 600 s at each current density. An ultrasonic wave (UW) was applied to the specimen from the beginning of test or just after the potential reached one of these constant values. The current density in these cases was compared with that without the application of UW. The results indicated that when the UV was applied from the beginning of test the current density was not affected by the application of UW in both the cathode and passive regions, but it was decreased when the potential was kept at the constant value after the current density reached 10 or 50 A/m2. Also when the UW was applied after the current density reached 2, 10 or 50 A/m2 and the potential was kept at the constant value, the current density was decreased by the application of UW. At the same time, the number and size of pits were decreased by the application of UW. The reason for the decrease in pitting corrosion was considered to be that UW destroyed the corrosion product on pits and the stirring effect of UW decreased the concentration of hydrogen and chloride ions in the pits, which accelerated the formation of a passive film on the pit wall.

High temperature ultrasonic transducers for imaging and measurements in a liquid Pb/Bi eutectic alloy

In some nuclear reactors or accelerator-driven systems (ADS) the core is intended to be cooled by means of a heavy liquid metal, for example, lead-bismuth (Pb/Bi) eutectic alloy. For safety and licensing reasons, an imaging method of the interior of ADS, based on application of ultrasonic waves, has thus to be developed. This paper is devoted to description of developed various ultrasonic transducers suitable for long term imaging and measurements in the liquid Pb/Bi alloy. The results of comparative experimental investigations of the developed transducers of different designs in a liquid Pb/Bi alloy up to 450 degrees C are presented. Prototypes with different high temperature piezoelectric materials were investigated: PZT, bismuth titanate (Bi4Ti3O12), lithium niobate (LiNbO3), gallium orthophosphate (GaPO4) and aluminum nitride (A1N). For acoustic coupling with the metal alloy, it was proposed to coat the active surface of the transducers by diamond like carbon (DLC). The radiation robustness was assessed by exposing the transducers to high gamma dose rates in one of the irradiation facilities at SCK x CEN. The experimental results proved that the developed transducers are suitable for long-term operation in harsh conditions.

Joining of alumina ceramics to metals

The application of ultrasonic waves enhanced the wetting of alumina by Zn–Al filler alloy. Alumina ceramic was brazed to different metals such as Ti, Ni, Nb, Fe, and AISI 304 stainless steel using the Zn–5 mass-%Al brazing filler alloy. Different reaction products were formed at the alumina–metal interfaces, including solid solutions and intermetallic compounds. The alumina–Nb joint exhibited the highest bond strength value among the different couples, because Nb produces the lowest residual stress among the alumina–metal joints. The high mismatch in thermal expansion coefficient between the brazing filler and the AISI 304 stainless steel yielded the lowest bond strength among the joints.

Enhanced relaxation of SiGe layers by He implantation supported by in situ ultrasonic treatments

Helium implantation-enhanced strain relaxation of SiGe layers grown pseudomorphically on Si substrates is an interesting alternative for the creation of strained Si CMOS structures. Here we demonstrate the application of additional in situ ultrasonic treatment (UST) during He ion implantation for the formation of relaxed Si 0.8Ge 0.2 buffer layers. By Raman spectroscopy and X-ray diffraction we show increased relaxation of the SiGe layers under the influence of UST. A rectangular dislocation network with a high dislocation density of about 10 9–10 10 cm −2 concentrated near the interface between the SiGe layer and the Si substrate is shown by TEM for 100 nm SiGe/Si heterostructures after heat treatment at 750 °C, 60 s. Application of ultrasonic waves during He implantation keeps a low surface roughness of about 0.5 nm.

Ultra-toughened Al2O3–TiC–Co ceramic

Abstract Al 2 O 3 and TiC powders in microscale have been coated with a uniform cobalt layer by electroless plating technique under application of ultrasonic wave. Co-coated Al 2 O 3 and TiC powders were then hot-pressed into Al 2 O 3 –TiC–Co ceramic by sintering at 1600 °C and 30 MPa for 30 min in vacuum. Results demonstrate that the uniformly distributed Co-phase improved the interfacial bonding of ceramic grains significantly in comparison with Al 2 O 3 –TiC (AT30) ceramic and our previous research. The fracture toughness of the new Al 2 O 3 –TiC–Co ceramic reaches the value as large as 11.28 MPa m 1/2 ; meanwhile the hardness and bending strength are greatly improved as well. The fracture surface morphology of the Al 2 O 3 –TiC–Co ceramic sample shows the characteristics of intergranular fracture.

Effect of Thermoultrasonication on Salmonella enterica Serovar Enteritidis in Distilled Water and Intact Shell Eggs

The combined effects of simultaneous application of ultrasonic waves and heat treatment (thermoultrasonication) on the survival of a strain of Salmonella enterica Enteritidis was studied in both distilled water and intentionally contaminated intact eggs immersed in water. Although minor differences were observed between parameters obtained for thermoultrasonic treatment of bacteria suspended in water and those attached to the shell egg, the thermoultrasonication effects were considered to be of the same level in the range of temperatures assayed (52 to 58°C). This combined process presented a clearly higher killing effect than the heat treatment alone. It decreased the decimal reduction times (D-values) by 80 to 55%, respectively, in the range of temperatures for heat treatment when the organism was suspended in water, which means a 99.5% reduction (5D to >2D) of the original bacterial load versus a 90% reduction for the heat treatment alone. The practical implications of the phenomenon are discussed.

Investigation into the ultrasonic setting of glass ionomer cements Part II Setting times and compressive strengths

Glass ionomer cements (GICs) are formed by the reaction of an ion leachable alumino-silicate glass with an aqueous solution of poly (alkenoic acid), PAA. Water is used as the reaction medium [1]. A two-stage setting reaction occurs, resulting in a cement consisting of residual glass particles embedded in a hydrogel polysalt matrix [2]. During the first stage the material is susceptible to water uptake and during the second it is susceptible to dehydration. For example, when GICs are stored in water after an initial set of 15 min, a surface softening occurs, which may be caused by an inhibition of the setting reaction in a superficial layer of the cement [3]. This short-term relationship with water restricts the potential of GICs for healthcare applications. It is for this reason that resin modified GICs (RMGICs) were developed. These materials, conventional GICs into which an organic, photo-polymerisable monomer has been incorporated [4], can be command set by the application of an intense light source. However, RMGICs have drawbacks related to the presence of both non-polymerised monomer and the resin itself [5, 6]. Rapid setting is important both for providing resistance to attack from moisture in the mouth and improving wear resistance, but an alternative method to light-curing which does not require the incorporation of additional chemicals would be beneficial. The application of ultrasonic waves has long been used for setting cement in the building industry, and so studies were performed to utilise the same method for setting dental cements [7]. Most dental clinics have ultrasonic capability as it is used for de-scaling teeth. The effects of applying ultrasonic waves to the surface of the cement include a reduction in both porosity and mean glass particle size (due to breaking up of agglomerates), an improvement in the packing of the glass particles and a decrease in the mean molecular weight of the PAA [8]. Whilst it is not possible to further explain the curing mechanism at this stage, this work will determine the extent to which ultrasound affects the setting times and mechanical properties of a series of hand mixed and mechanically triturated GICs.

Fundamentals and Applications of Ultrasonic Waves

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