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ICU 2009 Special Session 20: Microbubbles for therapy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19897219 [PubMed - as supplied by publisher] (Source: Ultrasonics)
Source: Ultrasonics - October 31, 2009 Category: Physics Authors: Manasseh R, Bouakaz A Tags: Ultrasonics Source Type: journals

Design and modeling of systems for ultrasonic detection and measurements. Short resume of the topics of SS23 session in ICU congress, for the presentation of especial issue ICU09.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19897217 [PubMed - as supplied by publisher] (Source: Ultrasonics)
Source: Ultrasonics - October 27, 2009 Category: Physics Authors: Ramos A Tags: Ultrasonics Source Type: journals

Improving the thermal dimensional stability of flexible polymer composite backing materials for ultrasound transducers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Novel ultrasound backing materials based on polymer composites with improved dimensional stability and low coefficient of thermal expansion are being developed and analyzed. For this purpose a filled epoxy resin (Stycast(1265)), a commonly used backing material, was considered reference material and polyurethane composites (PU(2305), PU(2350)) were proposed as better alternatives. When compared to the reference, the PU(2350) filled with a mixture of Al(2)O(3) and tungsten exhibited an approximately 15 times lower glassy transition temperature and a 2.5 time lower longitudinal thermal expansion at 20 degrees C. This ens...
Source: Ultrasonics - October 27, 2009 Category: Physics Authors: State M, Brands PJ, Vosse FN Tags: Ultrasonics Source Type: journals

Effect of an imperfect interface on the SH wave propagating in a cylindrical piezoelectric sensor.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Under harsh in situ conditions, the interface in piezoelectric sensors may be damaged mechanically and/or electrically. The damaged interface would in turn affect the electromechanical behaviors of the sensors. The purpose of the present work is to study the effect of the imperfect interface on SH wave propagating in a cylindrical piezoelectric sensor. The dispersion relations of SH wave are derived analytically and the phase velocity are obtained numerically. Parametric studies on the phase velocity indicate that the mechanical imperfection may reduce the phase velocity under certain circumstances; however, the electr...
Source: Ultrasonics - October 13, 2009 Category: Physics Authors: Li YD, Yong Lee K Tags: Ultrasonics Source Type: journals

Cavitation microstreaming and stress fields created by microbubbles.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cavitation microstreaming plays a role in the therapeutic action of microbubbles driven by ultrasound, such as the sonoporative and sonothrombolytic phenomena. Microscopic particle-image velocimetry experiments are presented. Results show that many different microstreaming patterns are possible around a microbubble when it is on a surface, albeit for microbubbles much larger than used in clinical practice. Each pattern is associated with a particular oscillation mode of the bubble, and changing between patterns is achieved by changing the sound frequency. Each microstreaming pattern also generates different shear stres...
Source: Ultrasonics - October 13, 2009 Category: Physics Authors: Collis J, Manasseh R, Liovic P, Tho P, Ooi A, Petkovic-Duran K, Zhu Y Tags: Ultrasonics Source Type: journals

Diversity of biomedical applications of acoustic radiation force.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This manuscript is a summary of the paper presented at the ICU'2009 on biomedical applications of acoustic radiation force with emphasis on emerging applications in microfluidics, biotechnology, biosensors and assessment of the skeletal system. In this brief overview of current and projected applications of radiation force, no detailed description of the experiments illustrating particular applications are given as this would result in a far different and longer paper. Various mechanisms of acoustic radiation force generations and their biomedical applications are considered. These mechanisms include: (a) change in the...
Source: Ultrasonics - October 12, 2009 Category: Physics Authors: Sarvazyan A Tags: Ultrasonics Source Type: journals

Laboratory singing sand avalanches.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Some desert sand dunes have the peculiar ability to emit a loud sound up to 110dB, with a well-defined frequency: this phenomenon, known since early travelers (Darwin, Marco Polo, etc.), has been called the song of dunes. But only in late 19th century scientific observations were made, showing three important characteristics of singing dunes: first, not all dunes sing, but all the singing dunes are composed of dry and well-sorted sand; second, this sound occurs spontaneously during avalanches on a slip face; third this is not the only way to produce sound with this sand. More recent field observations have shown that d...
Source: Ultrasonics - October 9, 2009 Category: Physics Authors: Dagois-Bohy S, Ngo S, Pont SC, Douady S Tags: Ultrasonics Source Type: journals

Experimental study of Love-wave immunosensors based on ZnO/LiTaO(3) structures.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Experimental study of Love-mode immunosensors based on structures of ZnO/36 degrees YX-LiTaO(3) is presented, in which the ZnO films with c-axis (002) orientation have been successfully grown on the 36 degrees YX-LiTaO(3) substrates by RF magnetron sputtering technique. Then the Love-mode immunosensors based on the ZnO/36 degrees YX-LiTaO(3) structures and monitoring antibody-antigen immunoreactions in aqueous solutions in real time are fabricated. The experimental results show that the optimal thickness of ZnO layers is about 1.20mum in the structures deposited on 36 degrees YX-LiTaO(3) substrates, which is much less ...
Source: Ultrasonics - October 9, 2009 Category: Physics Authors: Zhou FM, Li Z, Fan L, Zhang SY, Shui XJ Tags: Ultrasonics Source Type: journals

Ultrasound propagation in wet and airless non-consolidated granular materials.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper deals with an experimental description of the acoustic behaviour of non-consolidated granular materials submitted to static force. The aim of this work is to investigate the effect of a small amount of an interstitial fluid on the acoustic propagation. Measurements of the velocity and of the transmission of the coherent wave are performed for different values of the applied force. It is shown that the behaviour of the speed of the ultrasonic coherent wave according to pressure have a slope close to the one of the Hertz-Mindlin's model in the case of a dry medium. When a small amount of a low viscosity fluid ...
Source: Ultrasonics - October 7, 2009 Category: Physics Authors: Griffiths S, Rescaglio A, Melo F Tags: Ultrasonics Source Type: journals

Ultrasound-assisted microbubbles gene transfer in tendons for gene therapy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Our study aimed at evaluating the use of ultrasound-assisted microbubbles gene transfer in mice Achilles tendons. Using a plasmid encoding luciferase gene, it was found that an efficient and stable gene expression for more than two weeks was obtained when tendons were injected with 10mug of plasmid in the presence of 5x10(5) BR14 microbubbles with the following acoustic parameters: 1MHz, 200kPa, 40% duty cycle and 10min of exposure time. The rate of gene expression was 100-fold higher than that obtained with naked plasmid injected alone without ultrasound or with ultrasound in absence of microbubbles. The long term exp...
Source: Ultrasonics - October 7, 2009 Category: Physics Authors: Delalande A, Bureau MF, Midoux P, Bouakaz A, Pichon C Tags: Ultrasonics Source Type: journals

Wave guide imaging through Time Domain Topological Energy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Time Domain Topological Energy (TDTE), uses the reflected ultrasonic field recorded by an array of transducers placed on the boundary of the inspected medium. Two numerical determinations (forward and adjoint problems) of the acoustical field inside a reference medium are necessary to compute an image. Topological Energy is defined as a variation of topological sensitivity or gradient and comes from the field of mathematical optimisation. Recent developments for Non-Destructive Testing have shown the analogy with Time Reversal concepts. Time Reversal mirrors have been employed for various applications in a wide number ...
Source: Ultrasonics - October 4, 2009 Category: Physics Authors: Gibiat V, Sahuguet P Tags: Ultrasonics Source Type: journals

Modeling of flexible waveguides for ultrasonic vibrations transmission: Longitudinal and flexural vibrations of non-deformed waveguide.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The article presents the mathematical model allowing to investigate longitudinal and flexural vibrations of stepped flexible waveguides with transitional section without regard to various vibration modes interaction. The model uses original numerical-analytic calculations based on analytical solutions of the equation of waveguide steps vibrations and their continuous matching with numerical solution of the equation of transitional section vibrations. The proposed model can be considered as an initial approximation to the solution of the problem of flexible waveguides design, which makes it possible to determine and val...
Source: Ultrasonics - October 2, 2009 Category: Physics Authors: Stepanenko DA, Minchenya VT Tags: Ultrasonics Source Type: journals

Circumferential thermoelastic waves in orthotropic cylindrical curved plates without energy dissipation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this article, the propagation of guided thermoelastic waves in the circumferential direction of orthotropic cylindrical curved plates subjected to stress-free, isothermal boundary conditions is investigated in the context of the Green-Naghdi (GN) generalized thermoelastic theory (without energy dissipation). The coupled wave equations and heat conduction equation are solved by the Legendre orthogonal polynomial series expansion approach. The convergency of the method is discussed through a numerical example. The dispersion curves of thermal modes and elastic modes are illustrated simultaneously. Dispersion curves of...
Source: Ultrasonics - October 1, 2009 Category: Physics Authors: Jiangong Y, Bin W, Cunfu H Tags: Ultrasonics Source Type: journals

Hydrodynamic sono-voltammetry of ferrocene in [Tf(2)N](-) based ionic liquid media.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The present work deals with the hydrodynamic behavior of several room-temperature ionic liquids presenting the same bis(trifluoromethanesulfonyles)imide anion, associated with four different cations: 1-butyl-3-methylimidazolium, 1-octyl-3-methylimidazolium, N-trimethyl-N-propylammonium and 1-butyl-1-methylpyrrolidinium cations. Steady state voltammetry was used as an electrochemical technique to characterize mass transfer in both silent and sonicated conditions, using a rotating disk electrode. Results obtained in RTILs media are compared to those acquired in synthetic solutions of controlled viscosity, in order to dev...
Source: Ultrasonics - September 27, 2009 Category: Physics Authors: Costa C, Doche ML, Hihn JY, Bisel I, Moisy P, Lévêque JM Tags: Ultrasonics Source Type: journals

Current topics on sonoelectrochemistry.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sonoelectrochemistry is undergoing a reemerging activity in the last years with an increasing number of papers appearing in a wide range of peer review journals. Applied studies which cover environmental treatments, synthesis or characterization of nanostructures, polymeric materials synthesis, analytical procedures, films preparations, membrane preparations among other interesting applications have been reviewed. The revised fundamental analyses trying to elucidate the mechanism of the interactions between the ultrasound and electrical fields, are focused on test electrochemical processes, on the use of unconventional...
Source: Ultrasonics - September 26, 2009 Category: Physics Authors: González-García J, Esclapez MD, Bonete P, Hernández YV, Garretón LG, Sáez V Tags: Ultrasonics Source Type: journals

Surface acoustic waves in interaction with a dislocation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A surface acoustic wave can interact with dislocations that are close to the surface. We characterize this interaction and its manifestations as scattered surface acoustic waves for different orientations with respect to the surface of an edge dislocation. For dislocations that are parallel or perpendicular to the free surface, we present an analytical result for short dislocations with respect to the wave-length that reproduce qualitatively the main features observed for dislocations of various sizes. PMID: 19850312 [PubMed - as supplied by publisher] (Source: Ultrasonics)
Source: Ultrasonics - September 24, 2009 Category: Physics Authors: Maurel A, Pagneux V, Barra F, Lund F Tags: Ultrasonics Source Type: journals

Effective radiating area and beam non-uniformity ratio of ultrasound transducers at 5MHz, according to IEC 61689:2007.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper discloses results of measuring the effective radiating area (A(ER)) and the beam non-uniformity ratio (R(BN)) for US transducers at 5.0MHz. Measurements were carried out at Laboratory of Ultrasound of the Brazilian National Institute of Metrology, Standardization, and Industrial Quality. As reliability proof of system's adequacy, uncertainties were assessed. The calculation protocol was developed based on standard IEC 61689:2007. Type A uncertainty was estimated after four repetitions of the full procedure for the determination of A(ER) and R(BN), and Type B uncertainty was estimated from the mathematical mo...
Source: Ultrasonics - September 23, 2009 Category: Physics Authors: Costa-Félix RP, Alvarenga AV Tags: Ultrasonics Source Type: journals

Strategies for single particle manipulation using acoustic and flow fields.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Acoustic radiation forces have often been used for the manipulation of large amounts of micrometer sized suspended particles. The nature of acoustic standing wave fields is such that they are present throughout the whole fluidic volume; this means they are well suited to such operations, with all suspended particles reacting at the same time upon exposure. Here, this simultaneous positioning capability is exploited to pre-align particles along the centerline of channels, so that they can successively be removed by means of an external tool for further analysis. This permits a certain degree of automation in single part...
Source: Ultrasonics - September 22, 2009 Category: Physics Authors: Oberti S, Möller D, Neild A, Dual J, Beyeler F, Nelson BJ, Gutmann S Tags: Ultrasonics Source Type: journals

Limited-diffraction wave generation by approaching theoretical X-wave electrical driving signals with rectangular pulses.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The main interest of using limited diffracting waves is motivated by their potential applications in the enlargement of the field depth in acoustic imaging systems, under collimated conditions. In this work, an approach for simplifying the experimental arrangement, needed to generate limited diffracting waves, is proposed. The main idea is to approximate the theoretical X-wave electrical excitations by means of simple driving rectangular pulses. In order to optimize these driving signals in each array annulus, the L2 curve criterion is applied. The differences between theoretical X-wave signals and approximate driving ...
Source: Ultrasonics - September 19, 2009 Category: Physics Authors: Castellanos L, Calás H, Ramos A Tags: Ultrasonics Source Type: journals

Composition dependence of the elastic constants of beta-phase and (alpha+beta)-phase PdH(x).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have measured the composition and temperature dependence of the shear moduli C' and C(44) for two-phase (alpha+beta)- and single-phase beta-PdH(x). In the two-phase region, the alpha- and beta-phases are coherent. Here, the composition dependence of C(44) and C' deviate negatively from a Vegard-type volume average. We attribute the deviations to two effects: (1) the partly in-series arrangement of the precipitate and matrix phases, relative to the externally applied stress, and (2) thermally activated anelastic relaxations involving the rapid motion of H interstitial atoms, leading to slight changes in the shape of ...
Source: Ultrasonics - September 19, 2009 Category: Physics Authors: Safarik DJ, Schwarz RB, Paglieri SN, Quintana RL, Tuggle DG, Byler DD Tags: Ultrasonics Source Type: journals

High-power ultrasonic system for the enhancement of mass transfer in supercritical CO(2) extraction processes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Oil is an important component of almonds and other vegetable substrates that can show an influence on human health. In this work the development and validation of an innovative, robust, stable, reliable and efficient ultrasonic system at pilot scale to assist supercritical CO(2) extraction of oils from different substrates is presented. In the extraction procedure ultrasonic energy represents an efficient way of producing deep agitation enhancing mass transfer processes because of some mechanisms (radiation pressure, streaming, agitation, high amplitude vibrations, etc.). A previous work to this research pointed out th...
Source: Ultrasonics - September 19, 2009 Category: Physics Authors: Riera E, Blanco A, García J, Benedito J, Mulet A, Gallego-Juárez JA, Blasco M Tags: Ultrasonics Source Type: journals

Characterization of HIFU transducers designed for sonochemistry application: Cavitation distribution and quantification.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Acoustic field distribution was determined in HIFU sonoreactors as well as localization of cavitation activity by crossing different techniques: modeling, hydrophone measurements, laser tomography and SCL measurements. Particular care was taken with quantification of this last technique by pixels or photon counting. Cavitation bubbles generated by HIFU are mainly located on the outer layer of the propagation cone in the post-focal zone. Greatest acoustic activity is not located at the geometrical focal, but corresponds to a high concentration of bubbles zone. On the contrary, the main sonochemical activity shifts sligh...
Source: Ultrasonics - September 19, 2009 Category: Physics Authors: Hallez L, Touyeras F, Hihn JY, Klima J, Guey JL, Spajer M, Bailly Y Tags: Ultrasonics Source Type: journals

Impact of acoustic pressure on ambient pressure estimation using ultrasound contrast agent.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Local blood pressure measurements provide important information on the state of health of organs in the body and can be used to diagnose diseases in the heart, lungs, and kidneys. This paper presents an approach for investigating the ambient pressure sensitivity of a contrast agent using diagnostic ultrasound. The experimental setup resembles a realistic clinical setup utilizing a single array transducer for transmit and receive. The ambient pressure sensitivity of SonoVue (Bracco, Milano, Italy) was measured twice using two different acoustic driving pressures, which were selected based on a preliminary experiment. To...
Source: Ultrasonics - September 19, 2009 Category: Physics Authors: Andersen KS, Jensen JA Tags: Ultrasonics Source Type: journals

The role of energy density and acoustic cavitation in shock wave lithotripsy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this study was to analyze the influence of cavitation and energy density on stone fragmentation. A research lithotripter was used to expose a large set of artificial kidney stones to shock waves varying different parameters. Hundreds of pressure records were used to calculate the energy density of the lithotripter at different settings. Results indicate that energy density is a crucial parameter and that better SWL treatment outcomes could be obtained placing the calculus at a prefocal position. PMID: 19819511 [PubMed - as supplied by publisher] (Source: Ultrasonics)
Source: Ultrasonics - September 19, 2009 Category: Physics Authors: Loske AM Tags: Ultrasonics Source Type: journals

Axial vibration characteristics of a cylindrical, radially polarized piezoelectric transducer with different electrode patterns.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A circular cylindrical piezoelectric transducer with radial polarization is proposed. The axial vibration characteristics of the transducer are studied by three different methods: analytical calculation, FEM simulation and experiment. The symmetric and asymmetric excitation conditions are discussed in the Haskins and Walsh model. For the resonance frequencies of the transducer, the results from the above three methods coincide well with each other. For the vibration amplitude, there are some deviations between the FEM simulation and measurement results; some possible reasons for this are discussed. The influence of the...
Source: Ultrasonics - September 18, 2009 Category: Physics Authors: Sun D, Wang S, Hata S, Shimokohbe A Tags: Ultrasonics Source Type: journals

2D array design based on Fermat spiral for ultrasound imaging.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The main challenge faced by 3D ultrasonic imaging with 2D array transducers is the large number of elements required to achieve an acceptable level of quality in the images. Therefore, the optimisation of the array layout, in order to reduce the number of active elements in the aperture, has been a research topic in the last years. Nowadays, array technology has made viable the production of 2D arrays with larger flexibility on elements size, shape and position, allowing to study other configurations different to the classical matrix organisation, such as circular, archimedes spiral or polygonal layout between others. ...
Source: Ultrasonics - September 18, 2009 Category: Physics Authors: Martínez-Graullera O, Martín CJ, Godoy G, Ullate LG Tags: Ultrasonics Source Type: journals

Simultaneous determination of the ultrasound velocity and the thickness of solid plates from the analysis of thickness resonances using air-coupled ultrasound.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A method that combines transmission of air-coupled ultrasound pulses through solid plates and amplitude and phase spectral analysis is presented. In particular, the method analyzes the first thickness resonance of the plates. The purpose is to determine, simultaneously, velocity and attenuation coefficient of the ultrasounds in the material and the thickness of the plate. This is especially useful when thickness can not be measured independently. The method is successfully applied to soft membranes, biological samples and FRP composites. PMID: 19819512 [PubMed - as supplied by publisher] (Source: Ultrasonics)
Source: Ultrasonics - September 18, 2009 Category: Physics Authors: Gómez Álvarez-Arenas TE Tags: Ultrasonics Source Type: journals

Simplified formulae to investigate flexural vibration characteristics of piezoelectric tubes in ultrasonic micro-actuators.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Based on the Rayleigh energy theory combining with Timoshenko beam model, the flexural vibration characteristics of piezoelectric tubes in ultrasonic micro-actuators are investigated. Additionally, the simplified formulae are derived to study the fundamental flexural resonance frequencies of the piezoelectric tubes with free-free ends and cantilevers. By changing the sizes of the tubes and the mass loads at the free ends, the variations of the flexural resonance frequencies of the piezoelectric tubes and cantilevers are calculated theoretically. To verify accuracy of the simplified formulae, by changing the lengths of ...
Source: Ultrasonics - September 17, 2009 Category: Physics Authors: Zhang H, Zhang SY, Fan L Tags: Ultrasonics Source Type: journals

Influence of temperature variations on the entropy and correlation of the Grey-Level Co-occurrence Matrix from B-Mode images.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this work, the feasibility of texture parameters extracted from B-Mode images were explored in quantifying medium temperature variation. The goal is to understand how parameters obtained from the gray-level content can be used to improve the actual state-of-the-art methods for non-invasive temperature estimation (NITE). B-Mode images were collected from a tissue mimic phantom heated in a water bath. The phantom is a mixture of water, glycerin, agar-agar and graphite powder. This mixture aims to have similar acoustical properties to in vivo muscle. Images from the phantom were collected using an ultrasound system tha...
Source: Ultrasonics - September 12, 2009 Category: Physics Authors: Alvarenga AV, Teixeira CA, Ruano MG, Pereira WC Tags: Ultrasonics Source Type: journals

Non-destructive imaging using the time domain topological energy method.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The time domain topological gradient has recently been presented as a promising technique for imaging of complex structures [N. Dominguez, et al., Wave Motion 42 (1) (2005) 31-52], showing results obtained on simulated data. The method relies on the adequate combination of two computed ultrasonic fields, one forward and one adjoint. The adjoint field, that carries the information about the defects, is analogous to a time reversal operation. The forward field plays the role of a "photographic developer". The great interest of the method is that the time reversal operation is not done experimentally but numerically, allo...
Source: Ultrasonics - September 2, 2009 Category: Physics Authors: Dominguez N, Gibiat V Tags: Ultrasonics Source Type: journals

Resonant-ultrasound spectroscopy for studying annealing effect on elastic constant of thin film.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper, we study the elastic property of thin films using resonant-ultrasound spectroscopy (RUS). RUS determines the elastic constants of a solid from its resonance frequencies of free vibration. There were two problems to be solved for applying RUS to thin films: accurate measurement of the resonance frequencies and mode identification of each resonance frequency. We solve these problems using the tripod needle transducers and the laser-Doppler interferometry (LDI). In this paper, we describe the RUS/LDI measurement setup we developed, and show the relationship between the elastic constant and annealing tempera...
Source: Ultrasonics - August 31, 2009 Category: Physics Authors: Nakamura N, Nakashima T, Oura S, Ogi H, Hirao M Tags: Ultrasonics Source Type: journals

Nanocomposite cerium oxide polymer matching layers with adjustable acoustic impedance between 4 MRayl and 7 MRayl.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A new class of materials for ultrasonic matching layers is presented. The materials consist of nanoscale cerium oxide particles in an epoxy functionalized organic inorganic hybrid polymer matrix. The cerium oxide agglomerates to particles with 20nm diameters. The content of particles in the polymer matrix could be increased to 75wt.% which corresponds to 37vol.%. The most technical important piezoelectrical ceramics have an acoustic impedance of about 30 MRayl, to improve coupling into water or biological tissue with an acoustic impedance of about 1.5 MRayl a matching layer should have an acoustic impedance of about 6....
Source: Ultrasonics - August 31, 2009 Category: Physics Authors: Tiefensee F, Becker-Willinger C, Heppe G, Herbeck-Engel P, Jakob A Tags: Ultrasonics Source Type: journals

Biological effects of combined ultrasound and cisplatin treatment on ovarian carcinoma cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The effects of low-power ultrasound, the anti-cancer drug cisplatin, and their combined application were studied in two lines of human ovarian carcinoma cells, A2780 and A2780cis. Four modes of treatment were used: exposure to ultrasonic field, application of cisplatin, exposure to ultrasound followed by cisplatin, and presence of cisplatin followed by exposure to application ultrasound. Ultrasound was used at intensities of 0.5W/cm(2) and 1.0W/cm(2) for 10min, cisplatin was applied at concentrations of 1muM and 6muM per cell suspension treated in A2780 and cisplatin-resistant A2780cis cells, respectively. The results ...
Source: Ultrasonics - August 18, 2009 Category: Physics Authors: Bernard V, Skorpíková J, Mornstein V, Slaninová I Tags: Ultrasonics Source Type: journals

Elastic guided wave propagation in a periodic array of multi-layered piezoelectric plates with finite cross-sections.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we present a model study of guided wave dispersion and resonance behavior of an array of piezoelectric plates with arbitrary cross-sections. The objective of this work is to analyze the influence of the geometry of an element of a 1D-array ultrasound transducer on generating multi-resonance frequency so as to increase the frequency bandwidth of the transducers. A semi-analytical finite-element (SAFE) method is used to model guided wave propagation in multi-layered 1D-array ultrasound transducers. Each element of the array is composed of LiNbO(3) piezoelectric material with rectangular or subdiced cross-secti...
Source: Ultrasonics - August 12, 2009 Category: Physics Authors: Cortes DH, Datta SK, Mukdadi OM Tags: Ultrasonics Source Type: journals

Two-dimensional simulation of the single-sided air-coupled ultrasonic pitch-catch technique for non-destructive testing.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Non-contact air-coupled ultrasonic inspection of materials using single-sided access offers interesting possibilities for the development of in-line non-destructive testing (NDT) systems. This contribution reports observations and simulations obtained from a single-sided air-coupled pitch-catch configuration. The pitch-catch technique involves a set-up in which transmitter and receiver are located at the same side of the test object. Sound waves, reflected once or multiple times from the back-wall of the object or refracted by a discontinuity, are recorded and analyzed for visualization. The feasibility of the techniqu...
Source: Ultrasonics - August 11, 2009 Category: Physics Authors: Delrue S, Van Den Abeele K, Blomme E, Deveugele J, Lust P, Matar OB Tags: Ultrasonics Source Type: journals

A method for crack sizing using Laser Doppler Vibrometer measurements of Surface Acoustic Waves.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The goal of non-destructive testing (NDT) is to determine the position and size of structural defects, in order to measure the quality and evaluate the safety of building materials. Most NDT techniques are rather complex, however, requiring specialized knowledge. In this article, we introduce an experimental method for crack detection that uses Surface Acoustic Waves (SAWs) and optical measurements. The method is tested on a steel beam engraved with slots of known depth. A simple model to determine the cracks size is also proposed. At the end of the article, we describe a possible application: fatigue crack sizing on a...
Source: Ultrasonics - August 8, 2009 Category: Physics Authors: Longo R, Vanlanduit S, Vanherzeele J, Guillaume P Tags: Ultrasonics Source Type: journals

Measurement of tortuosity in aluminum foams using airborne ultrasound.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The slow compressional wave in air-saturated aluminum foams was studied by means of ultrasonic transverse transmission method over a frequency range from 0.2MHz to 0.8MHz. The samples investigated have three different cell sizes or pores per inch (5, 10 and 20ppi) and each size has three aluminum volume fractions (5%, 8% and 12% AVF). Phase velocities show minor dispersion at low frequencies but remain constant after 0.7MHz. Pulse broadening and amplitude attenuation are obvious and increase with increasing ppi. Attenuation increases considerably with AVF for 20ppi foams. Tortuosity ranges from 1.003 to 1.032 and incre...
Source: Ultrasonics - August 6, 2009 Category: Physics Authors: Le LH, Zhang C, Ta D, Lou E Tags: Ultrasonics Source Type: journals

Mode-switching: A new technique for electronically varying the agglomeration position in an acoustic particle manipulator.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Acoustic radiation forces offer a means of manipulating particles within a fluid. Much interest in recent years has focussed on the use of radiation forces in microfluidic (or "lab on a chip") devices. Such devices are well matched to the use of ultrasonic standing waves in which the resonant dimensions of the chamber are smaller than the ultrasonic wavelength in use. However, such devices have typically been limited to moving particles to one or two predetermined planes, whose positions are determined by acoustic pressure nodes/anti-nodes set up in the ultrasonic standing wave. In most cases devices have been designed...
Source: Ultrasonics - August 3, 2009 Category: Physics Authors: Glynne-Jones P, Boltryk RJ, Harris NR, Cranny AW, Hill M Tags: Ultrasonics Source Type: journals

Real-time on-line ultrasonic monitoring for bubbles in ceramic 'slip' in pottery pipelines.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
When casting ceramic items in potteries, liquid 'slip' is passed from a settling tank, through overhead pipelines, before being pumped manually into the moulds. It is not uncommon for bubbles to be introduced into the slip as it passes through the complex piping network, and indeed the presence of bubbles is a major source of financial loss to the ceramics industry worldwide. This is because the bubbles almost always remain undetected until after the ceramic items have been fired in a kiln, during which process bubbles expand and create unwanted holes in the pottery. Since there it is usually an interval of several hou...
Source: Ultrasonics - July 23, 2009 Category: Physics Authors: Yim GT, Leighton TG Tags: Ultrasonics Source Type: journals

Low dimensional optimization for in vivo real-time porcine liver motion estimation using ultrasound imaging.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study presents a contribution to the tracking of a moving target during high-intensity focused ultrasound (HIFU) treatment. Indeed, HIFU has proved to be highly efficient in inducing homogeneous and reproducible tumor destruction by thermal coagulation necrosis. However, accurate targeting of human abdominal tumors is difficult to maintain due to the motion induced by breathing. An algorithm is presented to track a region of interest of fixed size in a sequence of images. This algorithm was evaluated on synthetic data and on in vivo sequences of ultrasound liver images acquired using 12MHz ultrasound imaging probe at ...
Source: Ultrasonics - July 23, 2009 Category: Physics Authors: Fehrenbach J, Masmoudi M, Melodelima D Tags: Ultrasonics Source Type: journals

In-vivo validation of fast spectral velocity estimation techniques.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Spectrograms in medical ultrasound are usually estimated with Welch's method (WM). WM is dependent on an observation window (OW) of up to 256 emissions per estimate to achieve sufficient spectral resolution and contrast. Two adaptive filterbank methods have been suggested to reduce the OW: Blood spectral Power Capon (BPC) and the Blood Amplitude and Phase EStimation method (BAPES). Ten volunteers were scanned over the carotid artery. From each data set, 28 spectrograms were produced by combining four approaches (WM with a Hanning window (W.HAN), WM with a boxcar window (W.BOX), BPC and BAPES) and seven OWs (128, 64, 32...
Source: Ultrasonics - July 22, 2009 Category: Physics Authors: Hansen KL, Gran F, Pedersen MM, Holfort IK, Jensen JA, Nielsen MB Tags: Ultrasonics Source Type: journals

Angular and axial evaluation of superficial defects on non-accessible pipes by wavelet transform and neural network-based classification.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper an effective procedure that allows evaluating the dimensions of corrosive flaws on non-accessible pipes is presented. The method is based on the propagation of ultrasound waves, analyzing the informative content of echoes reflected by defects. The approach exploits the properties of the wavelet transform to represent signals by a reduced form. The coefficients of this representation are selected properly by making use of a filter method followed by a genetic algorithm and, then, they feed a neural network classifier which evaluates the dimensions of defects on the pipe under test. Numerical results show l...
Source: Ultrasonics - July 13, 2009 Category: Physics Authors: Acciani G, Brunetti G, Fornarelli G, Giaquinto A Tags: Ultrasonics Source Type: journals

An efficient sound speed estimation method to enhance image resolution in ultrasound imaging.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Most of clinical ultrasound imaging systems use a pre-determined sound speed, mostly 1540m/s, in transmit- and receive-beamforming while actual sound speed varies depending on tissue composition and temperature. Sound speed errors, particularly in receive-beamforming, lead to resolution degradation and sensitivity loss in ultrasound imaging. In this paper, we propose a sound speed estimation method in which an optimal sound speed, the speed that makes the echo signal delays at the transducer elements be best matched to the theoretical delays, is estimated by maximizing the beamformed echo signal amplitude with respect ...
Source: Ultrasonics - July 6, 2009 Category: Physics Authors: Cho MH, Kang LH, Kim JS, Lee SY Tags: Ultrasonics Source Type: journals

Single-element ultrasonic transducer modeling using a hybrid FD-PSTD method.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In a recent publication [E. Filoux, S. Callé, D. Certon, M. Lethiecq, F. Levassort, Modeling of piezoelectric transducers with combined pseudospectral and finite-difference methods, J. Acoust. Soc. Am. 123 (6) (2008) 4165-4173], a new finite-difference/pseudospectral time-domain (FD-PSTD) algorithm was presented and used to model the generation of acoustic waves by a piezoelectric resonator and their propagation in the structure and the surrounding water. In this paper, the model has been extended to simulate the two-dimensional behaviour of a complete single-element transducer, composed of the resonator, a backin...
Source: Ultrasonics - June 29, 2009 Category: Physics Authors: Filoux E, Levassort F, Callé S, Certon D, Lethiecq M Tags: Ultrasonics Source Type: journals

High frequency shear horizontal plate acoustic wave devices.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It has been shown recently that shear horizontal acoustic waves propagating in piezoelectric plates whose thickness h is much less than the acoustic wavelength lambda possess a number of attractive properties for use in sensor and signal processing applications. In order to exploit the potential benefits of these waves, however, one needs to fabricate devices on very thin plates. We have developed a suitable fabrication method which can be used to realize devices on such thin plates. In this method, the device is first fabricated on a plate of normal thickness (approximately 500mum) and the substrate is then lapped fro...
Source: Ultrasonics - June 8, 2009 Category: Physics Authors: Vohra G, Joshi SG, Zaitsev BD, Kuznetsova IE, Teplykh AA Tags: Ultrasonics Source Type: journals

A feasibility study of temperature rise measurement in a tissue phantom as an alternative way for characterization of the therapeutic high intensity focused ultrasonic field.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The feasibility that temperature field measurements in vitro as an alternative way to characterize the high intensity focused ultrasound (HIFU) field used in therapeutic applications has been explored in a phantom study. Thermocouples (copper-constantan, diameter 0.125mm) are embedded in a phantom filled with tissue mimicking material that simulates the thermal and acoustic properties of soft-tissue. The temperature rises as a function of ultrasound exposure time near the focus of a HIFU transducer (1.1MHz, active radius a=32mm, geometric focal length=62mm) of various acoustic powers up to 30W are measured and compared...
Source: Ultrasonics - June 5, 2009 Category: Physics Authors: Chen D, Fan T, Zhang D, Wu J Tags: Ultrasonics Source Type: journals

Signal-to-noise ratio enhancement based on wavelet filtering in ultrasonic testing.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In ultrasonic non-destructive testing of materials with a coarse-grained structure the scattering from the grains causes backscattering noise, which masks flaw echoes in the measured signal. Several filtering methods have been proposed for improving the signal-to-noise ratio. In this paper we present a comparative study of methods based on the wavelet transform. Experiments with stationary, discrete and wavelet packet de-noising are evaluated by means of signal-to-noise ratio enhancement. Measured and simulated ultrasonic signals are used to verify the proposed de-noising methods. For comparison, we use signal-to-noise...
Source: Ultrasonics - June 5, 2009 Category: Physics Authors: Matz V, Smid R, Starman S, Kreidl M Tags: Ultrasonics Source Type: journals

Lamb wave detection of limpet mines on ship hulls.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper describes the use of ultrasonic guided waves for identifying the mass loading due to underwater limpet mines on ship hulls. The Dynamic Wavelet Fingerprint Technique (DFWT) is used to render the guided wave mode information in two-dimensional binary images because the waveform features of interest are too subtle to identify in time domain. The use of wavelets allows both time and scale features from the original signals to be retained, and image processing can be used to automatically extract features that correspond to the arrival times of the guided wave modes. For further understanding of how the guided w...
Source: Ultrasonics - June 5, 2009 Category: Physics Authors: Bingham J, Hinders M, Friedman A Tags: Ultrasonics Source Type: journals

Towards classification of the bifurcation structure of a spherical cavitation bubble.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, the nonlinear dynamics of a bubble oscillator was treated numerically and the simulations were proceeded with bifurcation diagrams. The calculated bifurcation diagrams were compared in an attempt to classify the bubble dynamic characteristics when varying the control parameters. The comparison reveals distinctive bifurcation patterns as a consequence of driving the systems with unequal ratios of R(0)lambda (where R(0) is the bubble initial radius and lambda is the wavelength of the driving ultrasonic wave). Results indicated that systems having the equal ratio of R(0)lambda, share remarkable similarities in ...
Source: Ultrasonics - June 5, 2009 Category: Physics Authors: Behnia S, Sojahrood AJ, Soltanpoor W, Sarkhosh L Tags: Ultrasonics Source Type: journals

Dynamic properties of an omni-directional piezoelectric motor for precision position control.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A piezoelectric motor capable of omni-directional movements has been developed to apply for robot joints, eyes, and precision positioning stage. The piezoelectric actuator has a simple structure of a cone type consisting of two piezoelectric ring-typed ceramics with electrodes divided into four segments and stainless steel elastic bodies. Before manufacturing the piezoelectric motor, the admittance characteristics and displacements of the actuator as a function of frequency were simulated. Elliptical motions of the actuator were created at several frequencies between the longitudinal and transverse resonance frequencie...
Source: Ultrasonics - May 31, 2009 Category: Physics Authors: Jung WS, Kang CY, Paik DS, Vasiljev PE, Kim JD, Yoon SJ Tags: Ultrasonics Source Type: journals