scispace - formally typeset
Search or ask a question

Showing papers in "Ultrasonics in 1992"


Journal ArticleDOI
TL;DR: A theoretical model is developed for some acoustic properties, particularly the scatter and absorption, of this contrast agent, considering the individual microspheres as air bubbles surrounded by a thin shell, and it is concluded that the model correlates well with these acoustic measurements.

512 citations


Journal ArticleDOI
TL;DR: In this article, the Undatim Sonoreactor probe system is used to reproduce chemical reactions performed in ultrasonic baths. But the results of some model reactions performed using the newly developed UndatIM Sonoreact probe system have sometimes proved difficult to reproduce, due to a failure of the original report to specify the exact sonication conditions, e.g., the frequency of ultrasonic irradiation, the precise power entering the reaction system, the geometry of the reaction vessel, the presence of a bubbled gas or even the temperature of the reacted reaction.

417 citations


Journal ArticleDOI
TL;DR: Application of ultrasound to biotechnology is relatively new, but several processes that take place in the presence of cells or enzymes are activated by ultrasonic waves.

199 citations


Journal ArticleDOI
TL;DR: In this paper, the problems of scaling up successful sonochemical reactions from the point of view of reaction conditions and equipment available both on the laboratory and large scale are addressed from the perspective of ultrasonic processing and chemical reactors.

140 citations


Journal ArticleDOI
TL;DR: The main hindrance to the adoption of sonochemistry by industry is a lack of knowledge of the large scale equipment that is currently available and the way in which it operates as mentioned in this paper.

109 citations


Journal ArticleDOI
TL;DR: The data taken suggest that in determining the ultrasonic attenuation coefficient at these frequencies, the amount of material in a given bone section is significantly less important than the distribution of that material.

104 citations


Journal ArticleDOI
TL;DR: In this article, an amorphous iron powder is formed from the enormous heating and cooling rates generated during acoustic cavitation, which can be used to drive a variety of chemical reactions.

98 citations


Journal ArticleDOI
TL;DR: Low intensity ultrasound is a powerful analytical technique for investigating the physico-chemical properties of many biological and non-biological materials and will prove a useful addition to the existing analytical techniques used to characterize fats and oils.

93 citations


Journal ArticleDOI
TL;DR: The frequency scanning ultrasonic pulse echo reflectometer (FSUPER) as discussed by the authors is a device which can be used to measure the ultrasonic velocity, attenuation coefficient and specific acoustic impedance of liquid samples as a function of frequency.

70 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of ultrasonic irradiation at different frequencies, i.e. 20, 40, 60 and 80 kHz, on the activation of a model chemical reaction (iodide to iodine oxidation) has been investigated.

63 citations


Journal ArticleDOI
TL;DR: In this paper, ultrasonic Rayleigh and Lamb waves have been used to reconstruct tomographic images of defects within metallic samples through immersion techniques, Rayleigh waves are used for the identification of surface structures on thick samples, while Lamb waves were used to detect structures in thin sheets.

Journal ArticleDOI
TL;DR: In this paper, the effect of cavitation bubble collapse is considered and it is shown that in low intensity acoustic fields Cavitation Bubble collapse is of low probability and that local melting of metal particles on collision under ultrasonic waves is impossible.

Journal ArticleDOI
TL;DR: In this paper, the attenuation of ultrasound in wood over a range of frequencies and angle of incidence with respect to the three principal elastic directions of the material is described, and the influence was considered on velocity.

Journal ArticleDOI
TL;DR: In this paper, polystyrene microspheres (9 μm diameter) in air-saturated aqueous suspension were subjected to standing-wave fields over a range of pressure amplitudes at frequencies of 1.02 and 3.14 MHz.

Journal ArticleDOI
TL;DR: In this article, the sensitivity of inversion algorithms for recovering the elastic constants of moderately anisotropic solids using only ultrasonic longitudinal wavespeed data measured for various directions in a medium is discussed.

Journal ArticleDOI
TL;DR: In this article, the stiffness matrix of PEEK-carbon fiber composite samples is measured by immersion and contact ultrasonic methods, and three anisotropic models are tested: orthotropic, hexagonal and quadratic.

Journal ArticleDOI
TL;DR: In this article, a major phenomenon which occurs during the sonication of a system is the promotion of single electron transfers, which characterize true sonochemical processes, but this agitation role is more complex than generally assumed and various parameters can be of importance.

Journal ArticleDOI
TL;DR: An introductory description of the main phenomena connected with ultrasonic induced cavitation is given in this article, which mainly describes the motion of microbubbles present in a cavitating liquid, and the sonolysis of carbon tetrachloride is described in aqueous solutions of potassium iodide.

Journal ArticleDOI
TL;DR: This paper introduces an alternative method of obtaining frequency diversity wherein raised-cosine bandpass filters with flat-tops are recommended for use, and Experimental results are provided to demonstrate the advantages of the raised- cosine filters over Gaussian filters.

Journal ArticleDOI
TL;DR: In this paper, selected organic chemical reactions accelerated by ultrasound are discussed from the fields of acid-catalysed reactions (Friedel-Crafts-type), of the functionalization of sugars and of the heterocyclic chemistry (azoles).

Journal ArticleDOI
TL;DR: In this paper, an ultrasonic imaging system based on a direct time-space reconstruction algorithm has been developed, where radio-frequency signals are collected along a linear synthetic aperture with point sources and receivers in separate positions.

Journal ArticleDOI
TL;DR: In this article, it was shown that acoustically-induced gas bubbles carry a negative electric charge and for micrometre-sized bubbles they estimate the field to be about 7 × 105 V m−1.

Journal ArticleDOI
TL;DR: It is shown that the shell model of a cell adequately describes the attenuation in red blood cell suspensions, and the contribution of viscous drag losses to the sound attenuation decreases with frequency.

Journal ArticleDOI
TL;DR: This paper investigates the classification of ultrasonic inspection data using a backpropagation (BP) neural network and it is found that 95% of all the signals with flaws are classified correctly by the unsupervised BP net.

Journal ArticleDOI
TL;DR: In this article, the tris- (2,2′-bipyridine) ruthenium (II) dication in aqueous oxalate and in acetonitrile is substantially enhanced by simultaneous irradiation with 40-60 kHz ultrasound.

Journal ArticleDOI
TL;DR: In this article, a systematic and quantitative study of diethyl maleate-diethyl fumarate induced isomerization has been performed in CCl4 using different inert gases, different initiators and various experimental conditions.

Journal ArticleDOI
J. Lindley1
TL;DR: In this paper, the effects of ultrasound in the areas of catalyst/reagent preparation, catalyst activation and reaction with substrate are discussed in relation to recent results from our laboratories and from the literature.

Journal ArticleDOI
TL;DR: In this article, the phase velocity in anisotropic media is calculated from appropriate time delay measurements, and the relationship between phase velocity and ultrasonic transit time measurements is investigated for typical experimental geometries.

Journal ArticleDOI
TL;DR: In this paper, the radiation of an ultrasonic transducer intended for use in synthesized aperture focussing technique (SAFT) applications is analyzed. And the results of numerical modelling are presented in terms of three-dimensional plots.

Journal ArticleDOI
TL;DR: In this paper, the transient radiation of an ultrasonic transducer intended for use in synthesized aperture focussing technique (SAFT) applications is analyzed and the influence of various particle velocity distributions on the spatial-temporal structure of the sound field is evaluated.