DETERMINING THE ACOUSTIC FIELD DISTRIBUTION OF ULTRASONIC MULTI-ELEMENT PROBES

The paper presents a universal method of determining the distribution of acoustic field of multi-element probes designed for applications in ultrasound transmission tomography (UTT). This method allows us to calculate the acoustic field for different sectors of the probe with assigned geometry of elementary transducers' location. The idea is to sum acoustic fields generated by all elementary transducers with the use of geometrical transformations of coordinates of location of the discussed points of the acoustic field against each of the transducers. In order to verify the calculation results measurements of acoustic field distribution were also carried out for selected sectors of these probes. On the basis of an analysis of calculation results the size of electronically switched transmitting sector was optimized (in the sense of the number of concurrently radiating elementary transducers) for a linear and a ring ultrasonic multi-element probes from the point of view of their use for visualizing the inside of a biological structure by means of UTT. acoustic field; ultrasonic multi-element probes; piezoelectric transducers; ultrasound transmission tomograph

Microbiome symbionts and diet diversity incur costs on the immune system of insect larvae.

Communities of symbiotic microorganisms that colonize the gastrointestinal tract play an important role in food digestion and protection against opportunistic microbes. Diet diversity increases the number of symbionts in the intestines, a benefit that is considered to impose no cost for the host organism. However, less is known about the possible immunological investments that hosts have to make in order to control the infections caused by symbiont populations that increase because of diet diversity. Using taxonomical composition analysis of the 16S rRNAV3 region, we show that enterococci are the dominating group of bacteria in the midgut of the larvae of the greater wax moth (Galleria mellonella). We found that the number of colony-forming units of enterococci and expressions of certain immunity-related antimicrobial peptide (AMP) genes such as Gallerimycin, Gloverin, 6-tox, Cecropin-D and Galiomicin increased in response to a more diverse diet, which in turn decreased the encapsulation response of the larvae. Treatment with antibiotics significantly lowered the expression of all AMP genes. Diet and antibiotic treatment interaction did not affect the expression of Gloverin and Galiomicin AMP genes, but significantly influenced the expression of Gallerimycin, 6-tox and Cecropin-D. Taken together, our results suggest that diet diversity influences microbiome diversity and AMP gene expression, ultimately affecting an organism's capacity to mount an immune response. Elevated basal levels of immunity-related genes (Gloverin and Galiomicin) might act as a prophylactic against opportunistic infections and as a mechanism that controls the gut symbionts. This would indicate that a diverse diet imposes higher immunity costs on organisms

Computer model of acoustic link in a pipe with a flowing gas medium. Part I: Perturbation of ultrasonic transducer directivity pattern

The paper presents an aeroacoustic range equation which makes it possible to elaborate a computer model of ultrasonic link in air for static conditions. The model was made in form of a computer program called KML. Extending the static model, a simulation of uItrasonic wave propagation in a pipeline with flowing air for different profiles of laminar and turbulent flow and different link parameters was performed. The simulation made it possible to work out a computer model of an acoustic link in flowing gas. The model as a computer program can be used to calculate disturbance of ultrasonic beam rays shape and directivity pattem perturbation. Directivity pattem of ultrasonic transmitting transducer, deformed by flowing medium, becomes non-axial symmetric. As a result of the flow, ultrasonic beam rays are curvilinear and the source directivity pattern depends on rectilinearly measured distance

Some problems of ultrasonic and laser cutting of biological structures

The paper presents the influence of the laser and ultrasonic cutter on biological structures and some problems bound up with the applications of lasers and ultrasounds in surgery. The advantages and disadvantages of contact and noncontact applications of the Nd:YAG laser were presented as well as the usefulness of the ultrasonic cutter for selective cutting of various tissues. The benefits resulting from a combination of the two technologies were discussed, and initial tests of the laser-ultrasonic cutter operation were performed, pointing to the possibility of improving the cutting of biological structures

A Study of Interaction of Ultrasonic and Optical Wave in Optical Fiber Using the Air Gap

There exist some possibilities for simultaneous delivery of laser radiation and ultrasounds of low frequency and high intensity: introducing ultrasound oscillations in the optical fiber by the rigid connection of the fiber to the vibrating element and non-contact influence of the ultrasonic wave on the laser beam. The article presents the results of Matlab simulations and experimental studies of influence of the ultrasonic wave on the laser beam. A role of the air gap, and its influence on laser- ultrasonic transmission in optical fiber was examined. Advantages and disadvantages of both solutions of interaction of ultrasonic and optical waves in, e.g., surgical applications are discussed

FORCES DUE TO DIFFRACTION OF SOUND WAVE ON SMALL-DIAMETER CYLINDRICAL PARTICLES

In the paper we investigate the problem of diffraction of plane sound wave on small-diameter rigid cylindrical particles of arbitrary orientation. We estimate amplitudes of force and torque due to the diffraction phenomena. Some predictions are made concerning the acoustic radiation force on such particles.Nous avons analysé la théorie de l'action d'un champ acoustique stationnaire sur des particules en forme de cylindre. On observe deux effets de la pression de radiation : une réorientation des cylindres parallèlement aux plans d'onde et un regroupement des cylindres dans les plans nodaux de pression acoustique. Nous avons essayé de trouver une expression : 1° de la force par tels cylindres en fonction de l'angle ; 2° de la couple en fonction de l'angle

Computer model of acoustic link in a pipe with a flowing gas medium. Part II: Accuracy improvement ot medium flow velocity determination

While constructing medium flow velocity meters with the use of the ultrasonic method, it is assumed, that the deviation of the ultrasonic beam caused by medium flow, is insignificant. The assumption seems to be correct, because the average flow velocity is usually much smaller than the ultrasonic wave velocity in a medium. Basing on the assumption, we can use a known expression, which makes it possible to calculate an average medium flow velocity through run-time measurement from the transmitter to the receiver and in an opposite direction. In the paper, it is shown, that the average flow velocity determined in this way, using the computer model of acoustic link in a pipe with a flowing gas medium, is measured with a significant error. This error depends on the flow pipe diameter, the transducer diameters and the means of placing the transducers in the pipe. Properly modifying the expression for ultrasonic run-time through flowing gas medium and taking into account the means of transducer placing in the pipe, we can eliminate the error related to the measurement geometry and we can find an optimum ultrasonic wave propagation angle

Transmission of Ultrasonic Waves Via Optical Silica Glass Fiber Doped by 7.5% of TiO2 with the Use of Power Sandwich Transducer

The possibility of acoustic wave propagation in optical waveguides creates new prospects for simultaneous transmission of laser beams and ultrasonic waves. Combined laser-ultrasonic technology could be useful in e.g. surgical treatment. The article presents the results of experimental studies of transmission of ultrasonic wave in optical fibres, the core of which is doped by 7.5% of TiO2, using a sandwichtype transducer. It also presents amplitude characteristics of an ultrasonic signal propagated in the optical fibre. Authors studied the effect which the length of the fibre has on the achieved output signal amplitudes. They presented the relation of the output signal amplitude from a capacitive sensor to the power applied to the sandwich-type transducer. The obtained results were compared with the results produced when using an optical fibre with a core doped by 3% of GeO2, in order to select optical fibre suitable for simultaneous transmission of ultrasonic waves and laser rays