[New method of diagnosis by ultrasonic waves. Ultrasonic diagnosis of intracranial disease].
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Brain Diseases↗
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Results for “Ultrasonic Waves”
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[Physiochemical studies on the biologic effects of ultrasonic waves. II. Effect of ultrasonic waves on hydrogen ion concentration in inflamed tissue].
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Biological Products↗
[Physiochemical studies on the biologic effects of ultrasonic waves. I. Effect of ultrasonic waves on hydrogen ion concentration in healthy tissue].
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Biological Products↗
Ultrasonic wave fluctuations through tissue: an experimental pilot study.
The fundamental role of the assumption of plane wave ultrasonic propagation in attenuation and scattering measurements on soft tissues is discussed. The evidence for and against the validity of the assumption is shown to be inconclusive. An experimental procedure for direct assessment, by measurement of the ultrasonic amplitude and phase fluctuations occurring after an interrogating plane wave has passed through a tissue specimen, is described. The phase measurements impose significant demands on the mechanical precision, temperature stability and electronic timing capabilities of the measurement system. Measurements are reported on two specimens of fresh beef liver. One exhibited significant fluctuations of amplitude and phase which were reduced by 50% when the effects of thickness variations in the specimen were removed. The other specimen exhibited relatively small fluctuations. The feasibility of making such measurements has been demonstrated and the detailed features of the experimental procedure-which requires considerable care-have been outlined. Although more measurements are needed for definitive conclusions, these will require the development of a reliable technique for determining the presence of gaseous microbubbles in tissue in vitro. The preliminary conclusion that some samples of liver may exhibit low levels of wavefront disruption is consistent with recent evidence in the literature.
Animals↗
[Influence of ultrasonic waves and enzymes on antigenic properties of human erythrocytes. I. Ultrasonic waves].
In order to desintegrate the membranes and to isolate Rh antigens erythrocytes with well defined Rh patterns are treated with ultrasonic waves. The results of investigation of the homogenous sonicates allow the following tentative conclusions: The Rh antignes (C and E) are combined obviously with certain functional membrane areas of a given size. After sonication the activity of the sonicate to neutralize specific antibodies is greater than the activity of the same amount of untreated cells. It is supposed that this effect is caused by making accessible hidden antigens that are inaccessible in the intact membrane. Immunization of rabbits with the sonicates does not stimulate Rh-specific antibodies.
Antigen-Antibody Reactions↗
Determination of transport parameters in air-saturated porous materials via reflected ultrasonic waves.
An ultrasonic reflectivity method of evaluating the acoustic parameters of porous materials saturated by air (or any other gas) is discussed. The method is based on experimental detection of waves reflected at normal incidence by the first and second interface of the material. This method is based on a temporal model of direct and inverse scattering problems for the propagation of transient ultrasonic waves in a homogeneous isotropic slab of porous material with a rigid frame [Fellah et al., J. Acoust. Soc. Am. 113, 61-73 (2003)]. Generally, the conventional ultrasonic approach can be used to determine tortuosity, and viscous and thermal characteristic lengths via transmitted waves. Porosity cannot be estimated in transmitted mode because of its very weak sensitivity. First interface use of the reflected wave at oblique incidence leads to the determination of porosity and tortuosity [Fellah et al., J. Acoust. Soc. Am. 113, 2424-2433 (2003)] but this is not possible at normal incidence. Using experimental data of reflected waves by the first and second interface at normal incidence simultaneously leads to the determination of porosity, tortuosity, viscous and thermal characteristic lengths. As with the classic ultrasonic approach for characterizing porous material saturated with one gas, both characteristic lengths are estimated individually by assuming a given ratio between them. Tests are performed using weakly resistive industrial plastic foams. Experimental and numerical results, and prospects are discussed.
Journal Article↗
Novel modeling technique for the stator of traveling wave ultrasonic motors.
Traveling wave ultrasonic motors (TWUM) are a promising type of piezoelectric transducers, which are based on the friction transmission of mechanical propagating waves. These waves are excited on the stator by using high Q piezoelectric ceramics. This article presents a modeling strategy, which allows for a quick and precise modal and forced analysis of the stator of TWUM. First-order shear deformation laminated plate theory is applied to annular subdomains (super-elements) of the stator. In addition to shear deformations, the model takes into account the effect of rotary inertia, the stiffness contribution of the teeth, and the linear varying thickness of the stator. Moreover, the formulation considers a more realistic function for the electric field inside the piezoelectric ceramic, i.e., a linear function, instead of the generally assumed constant electric field. The Ritz method is used to find an approximated solution for the dynamic equations. Finally, the modal response is obtained and compared against the results from classical simplified models and the finite element method. Thus, the high accuracy and short computation times of the novel strategy were demonstrated.
Journal Article↗
An evaluation of effective radiuses of bulk-wave ultrasonic transducers as circular piston sources for accurate velocity measurements.
The effective radius of a bulk-wave ultrasonic transducer as a circular piston source, fabricated on one end of a synthetic silica (SiO2) glass buffer rod, was evaluated for accurate velocity measurements of dispersive specimens over a wide frequency range. The effective radius was determined by comparing measured and calculated phase variations due to diffraction in an ultrasonic transmission line of the SiO2 buffer rod/water-couplant/SiO2 standard specimen, using radio-frequency (RF) tone burst ultrasonic waves. Fourteen devices with different device parameters were evaluated. The velocities of the nondispersive standard specimen (C-7940) were found to be 5934.10 +/- 0.35 m/s at 70 to 290 MHz, after diffraction correction using the nominal radius (0.75 mm) for an ultrasonic device with an operating center frequency of about 400 MHz. Corrected velocities were more accurately found to be 5934.15 +/- 0.03 m/s by using the effective radius (0.780 mm) for the diffraction correction. Bulk-wave ultrasonic devices calibrated by this experimental procedure enable conducting extremely accurate velocity dispersion measurements.
Journal Article↗
The effect of ultrasonic waves in conducting polymer solution.
The effects of ultrasonic wave on the conducting polymer polyaniline dissolved in DMSO were observed. The UV-visible, infrared and NMR analysis show that the polymer undergo a redox and doping transition when the ultrasound wave interacts with the polymer dissolved into the solvent. The proposed mechanism to explain these effects is based on the solvent's hygroscopicity properties. The interaction with the ultrasonic wave, homolitically dissociates the water molecule producing radical species, and these species interact with the dissolved conducting polymer changing its oxidation and doped state. The resulting effects of that interaction are the modification of oxidation state of the conducting polymer and the decrease of the amount of water molecule in the solvent. From those results, we have proposed one straightforward method to eliminate water contamination in the solvent DMSO using ultrasonic waves.
Aniline Compounds↗
A methodology for structural health monitoring with diffuse ultrasonic waves in the presence of temperature variations.
Diffuse ultrasonic waves for structural health monitoring offer the advantages of simplicity of signal generation and reception, sensitivity to damage, and large area coverage; however, there are the serious disadvantages of no accepted methodology for analyzing the complex recorded signals and sensitivity to environmental changes such as temperature and surface conditions. Presented here is a methodology for applying diffuse ultrasonic waves to the problem of detecting structural damage in the presence of unmeasured temperature changes. This methodology is based upon the prediction and observation that the first order effect of a temperature change on a diffuse ultrasonic wave is a time dilation or compression. A multi-step procedure is implemented to (1) record a set of baseline waveforms from the undamaged specimen at temperatures spanning the expected operating range, (2) select a waveform from the baseline set whose temperature is the closest to that of a subsequently measured signal, (3) adjust this baseline waveform to best match the signal, and (4) calculate an error parameter between the signal and the adjusted waveform and compare this parameter to a threshold to determine the structural status. This procedure is applied to experimental data from aluminum plate specimens with artificial flaws. Probability of detection and the minimum flaw size detected are presented as a function of the size of the baseline waveform set. It is shown that a probability of detection of over 95% can be achieved with a small number of baseline waveforms.
Environmental Monitoring↗
Measurement of low-frequency ultrasonic wave in water using an acoustic fiber sensor.
An acoustic fiber sensor for measurement of ultrasonic waves, which used the approximate Raman-Nath diffraction effect where light diffraction waves were generated in an optical fiber by strain due to the ultrasonic waves, was proposed and examined. In order to characterize the acoustic fiber sensor as a basic study, measurements of low-frequency ultrasonic waves in water were examined using a step index fiber operating as a detection sensor. The results showed that characteristics of detected signals agreed with the theoretical prediction based on Fraunhofer diffraction. This indicates that our proposed fiber sensor can be used for the detection of low-frequency ultrasonic waves as well as the transmission of light diffraction signals.
Acoustics↗
A traveling wave ultrasonic motor of high torque.
A traveling wave ultrasonic motor of high torque with a new configuration is proposed in this paper. In the new design, a part of the motor serves as the stator. The rotor is the vibrator consisting of a toothed metal ring with piezoelectric ceramic bonded, which generates ultrasonic vibration. The rotor is in contact with the shell of motor and is driven by the friction between the rotor and the stator. This configuration not only removes the rotor in a conventional type of traveling wave ultrasonic motor but also changes the interaction between the rotor and the stator of the motor so that it improves the output performance of the motor. Although an electric brush is added to the ultrasonic motor, it is easy to be fabricated because of the low speed of motor. The finite element method was used to compute the vibration modes of an ultrasonic motor with a diameter of 100mm to optimize the design of the motor. A 9th mode was chosen as the operation mode with a resonance frequency about 25 kHz. According to the design, a prototype was fabricated. Its performance was measured. The rotation speed-torque curves for various frequencies were obtained. The result shows that its stall torque is greater than 4 Nm within a range of 400 Hz. This ultrasonic motor was used to drive the window glass of a mobile car and the result was satisfactory. In the further the research on the friction material between the stator and the rotor is under way to improve the efficiency of the ultrasonic motor.
Journal Article↗
[Study on the extraction of the active component in Atractylode macrocephala with ultrasonic wave technology optimized by the response surface method].
OBJECTIVE: To create Atractylode macrocephala inspissation decoction pieces. The effect of ultrasonic wave on extraction of the active components in A. macrocephala was studied in a water solution. METHOD: The factors including the ratio of material to liquid, ultrasonic power, ultrasonic time, soaking time, particle size etc, were studied. The best extraction method was found through the response surface method. RESULT: The best extraction method was found as follows: the granularity of material 0.1 mm, the repetition times of ultrasonic process 3 times, the soaking time before the ultrasonic process 30 min, the ratio of liquid to material 10:1, the soaking time after the ultrasonic process 2.6 h, the time of the ultrasonic wave 15.5 min, the power of the ultrasonic wave 531 W, the rate of reservation of active components 88.5%, the rate of inspissation 1.6. CONCLUSION: The ultrasonic wave can used in the extraction of the active components in A. macrocephala and a model equation that can be used to predict the experiment was get through the response surface method.
Atractylodes↗
Phase-transfer catalysis and ultrasonic waves. I. Cannizzaro reaction.
The aim of this work is to study the effect of an ultrasonic wave on the Cannizzaro reaction catalyzed by a phase-transfer catalyst. The reaction of benzaldehyde with potassium hydroxide was chosen as the reference reaction. The kinetics of the reaction was followed by the amount of benzoic acid which is well characterized and easily isolatable. Investigations were made on variables such as the kind of aldehyde, the phase-transfer catalyst, the temperature and the frequency of ultrasonic wave. As the phase-transfer catalyst depends strongly on mass transfer between two phases, it is well understood that ultrasonic waves have a greater efficiency of interface mixing than conventional agitation. The results showed that an ultrasonic wave of 20 kHz dramatically accelerates on the reaction.
Journal Article↗
Ultrasonic wave properties in the particle compounded agarose gels.
Ultrasonic wave properties (attenuation and velocity) in the particle compounded agarose gels have been experimentally studied in the range from 1 to 30 MHz. The particles used were talc, glass beads and graphite. The effects of size and volume concentration of particles were clearly observed as changes of ultrasonic wave properties. Applying the Urick's theory for viscous liquid suspensions, the specific curves of velocity in the gels were observed as a function of a beta, where a is the radius of the particles and beta is described by angular frequency omega, density rho and fluid viscosity eta. This indicates that the particle behavior in the gels seems to be similar with that in the viscous fluid. The estimated eta in the gels was higher than that of the free water, showing the high viscosity in the gels.
Journal Article↗
Modeling the propagation of ultrasonic waves in the interface region between two bonded elements.
An important task in nondestructive materials evaluation is the development of techniques to characterize the bond quality of adherent joints. Binding forces are nonlinear and cause a nonlinear modulation of transmitted and reflected ultrasonic waves. As a consequence, the higher harmonics generated by an insonified monochromatic wave give information about the adhesive bonds. The local binding forces in thin bonded interfaces can be obtained by the amplitudes of the ultrasonic waves of the insonified frequency and its higher harmonics as transmitted through the interface. Additional phase measurements may enable one to obtain the evaluation of the full hysteretic cycle of the interaction force. In order to gain a deeper understanding of the interface region and to improve the technique, numerical simulations of the ultrasonic wave propagation through specimens of two bonded elements can be used. A simple model based on the local interaction simulation approach (LISA) is described in this contribution, and a comparison between the results of the simulations and the experimental data is presented. Besides its intrinsic relevance for NDE, the problem considered in this paper may be very useful to analyze and test models for the simulation of ultrasonic wave propagation in nonclassical nonlinear mesoscopic elastic materials.
Journal Article↗
Effect of ultrasonic waves on the heat resistance of Bacillus spores.
The effect of ultrasonic treatment on the heat resistance of Bacillus spores differs widely both with the species and the strain tested. Ultrasonic waves do not affect the heat resistance of some strains, whereas they greatly reduce that of other strains of the same species. The heat-sensitizing effect of ultrasonic waves is more pronounced when short heating periods are used. Ultrasonic treatment does not seem to affect the "Z value".
Bacillus cereus↗
Noncontact detection of ultrasonic waves using fiber optic Sagnac interferometer.
This paper describes a fiber optic sensor suitable for noncontact detection of ultrasonic waves. This sensor is based on the fiber optic Sagnac interferometer, which has a path-matched configuration and does not require active stabilization. Quadrature phase bias between two interfering laser beams in the Sagnac loop is applied by controlling the birefringence using a fiber polarization controller. A stable quadrature phase bias can be confirmed by observing the interferometer output according to the change of phase bias. Additional signal processing is not needed for the detection of ultrasonic waves using the Sagnac interferometer. Ultrasonic oscillations produced by conventional ultrasonic piezoelectric transducers were successfully detected, and the performance of this interferometer was investigated by a power spectrum analysis of the output signal. Based on the validation of the fiber optic Sagnac interferometer, noncontact detection of laser-generated surface waves was performed. The configured Sagnac interferometer is very effective for the detection of small displacement with high frequency, such as ultrasonic waves used in conventional nondestructive testing (NDT).
Journal Article↗