Ultrasound generation

The performances of ultrasound generated and detected by lasers offer a wide field of applications in industry, so that we will pursue research for the testing of very small strucmres which could only be examined by a contactless technique. 

Ultrasound. Liquid is fed over a surface vibrating at a frequency > 20 kHz. Fine atomization, small size, and low injection velocity. Low flow rate and need for ultrasound generator. 

An interesting way to retard catalyst deactivation is to expose the reaction mixture to ultrasound. Ultrasound treatment of the mixture creates local hot spots, which lead to the formation of cavitation bubbles. These cavitation bubbles bombard the solid, dirty surface leading to the removal of carbonaceous deposits [38]. The ultrasound source can be inside the reactor vessel (ultrasound stick) or ultrasound generators can be placed in contact with the wall of the reactor. Both designs work in practice, and the catalyst lifetime can be essentially prolonged, leading to process intensification. The effects of ultrasound are discussed in detail in a review article [39]. 

Equipment and reagents Ultrasound generator, pulse generator, photomultiplier tube, oscilloscope, light-insulated cabinet, rare gas source (e.g. argon), 3-ami-nophthalhydrazide (luminol), sodium hydroxide, alcohol or other volatile organic solutes. 

Such effects are likely to be important. The use of SP interactions to create bioinspired material properties (e.g., see Chap. 9) implies that the ultimate yield behavior of SP materials could depend on the mechanical response of supramolecular interactions. Paulusse and Sijbesma (2004) have also shown that ultrasound-generated shear stresses can mechanically tear apart coordination SPs, damage that is subsequently repaired during dynamic equilibration once the shear stresses are removed. The mechanical response of supramolecular interactions within materials has potentially important consequences in the context of self-repairing materials, where the mpture of sacrificial supramolecular interactions protects a permanent, underlying materials architecture. The dynamic repair of the SP component in... 

Some information is available on the mechanisms responsible for the direct or indirect effects exerted by ultrasound on antigen retrieval. Considerable heat is generated during ultrasound exposure, but the heat dissipates very quickly. Very rapid heat loss has misled some workers to state that ultrasound generates a mild increment in temperature (Portiansky and Gimeno, 1996). 

The authors also demonstrated that low-frequency ultrasound acts as a transcutaneous immunization adjuvant that eliminates the requirement of toxins to elicit an immune response. Delivery of as little as 1.3 p.g of tetanus toxoid by low-frequency ultrasound generated an immune response comparable to that induced by 10 pg subcutaneous injection. 

The initiation effect of ultrasound generating hydroxyl radicals in reaction medium as, e.g., during sonochemical oxidation of aldehydes has been widely studied but rarely utilized. 

The piezoelectric effect is another significant property of BaTiOj and oil ferrcelectrics. A change in the dimension of crystals is caused by the influence of electrical field and vice versa potential difference develops on the crystal surfat under the effect of an external mechanical stress. The phenomenon is made use in microphones, loudspeakers, oscillators for ultrasound generation, resonators frequency control, etc. 

A special type of agitation is due to cavitation. This is the formation of vapor cavities in a liquid by local negative pressures, and the subsequent collapse of these cavities. The latter phenomenon generates shock waves that can disrupt nearby particles. Cavitation can be induced by ultrasonic waves, and ultrasound generators are useful for making emulsions in small quantities. 

Manothermosonication (MTS), a combined treatment of heat and nltrasonnd nnder moderate pressure, is another alternative to conventional heat treatment in order to inactivate enzymes and microorganisms [120-122], The ultrasound generates the cavitation or bnbble implosion in the media. This implosion can cause inactivation of the enzyme and destrnction of microorganisms. The simultaneons pressnre treatment maximizes the intensity of the explosion, which increases the level of inactivation. The MTS technique avoids the adverse effects of elevated temperatures on quality and also resnlts in reduced energy requirements and therefore rednced costs. 

Tian JJ, Zhang Q, Han M. Distributed fiber-optic laser-ultrasound generation based on ghost mode of tilted fiber Bragg gratings. Opt Express 2013 21 6109-14. 

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