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Ultrasonic radiation

The suggested method is appropriately implemented at the practice. The cost and working hours of unit measurement of it is less than of any alternative method of destructive test and with respect to the authenticity inspection of Stress-Deformation the given method is inferior only to destructive testing. The method was successfully implemented while evaluation of service life of main pipe-lines sections and pressure vessels as well. Data of method and instrument are used as official data equally with ultrasonic, radiation, magnetic particles methods, adding them by the previously non available information about " fatigue " metalwork structure. [Pg.29]

Forced convection can be achieved in a variety of ways, e.g. by agitating the solution (stirring mechanically, sparging with gas bubbles, ultrasonic radiation, etc.) or by moving or rotating the metal electrode, and this will result in more rapid transport of the reacting species to the electrode than when the solution is unagitated. [Pg.1200]

The use of ultrasonic (US) radiation (typical range 20 to 850 kHz) to accelerate Diels-Alder reactions is undergoing continuous expansion. There is a parallelism between the ultrasonic and high pressure-assisted reactions. Ultrasonic radiations induce cavitation, that is, the formation and the collapse of microbubbles inside the liquid phase which is accompanied by the local generation of high temperature and high pressure [29]. Snyder and coworkers [30] published the first ultrasound-assisted Diels-Alder reactions that involved the cycloadditions of o-quinone 37 with appropriate dienes 38 to synthesize abietanoid diterpenes A-C (Scheme 4.7) isolated from the traditional Chinese medicine, Dan Shen, prepared from the roots of Salvia miltiorrhiza Bunge. [Pg.154]

Saunders, L, Perrin, J., and Gammack, D. B. (1962). Aqueous dispersion of phospholipid by ultrasonic radiation, J. Pharm. Pharmacol., 14, 567-572. [Pg.333]

Luche found that tin-mediated allylations can also be performed through ultrasonic radiation, instead of using aluminum powder and hydrobromic acid to promote the reaction.82,83 The use of a saturated aqueous NH4C1/THF solution, instead of water/THF, dramatically increased the yield. When a mixture of aldehyde and ketone was subjected to the reaction, highly selective allylation of the aldehyde was achieved. [Pg.231]

The highest surface activity of fraction A3 extracted from shale oil needs to be explored in detail in order to understand this very unique phenomena. The benchmark experiments performed by Lee et al. (22) in studies of dissociation phenomena of Stuart oil shale in an alkaline environment proved the formation of carboxylic acids as it was verified from GC results. In another study by Lee et al. (23), it was shown that the hydroxyl ions from an alkaline solution could decompose the silicate and aluminasilicate structures in oil shale samples, provided that ultrasonic radiation and electrolytic current were simultaneously applied. [Pg.383]

Since the ultrasonic radiating surface is not in direct contact with the reaction solution, the acoustic intensities are much lower than those of the direct immersion horn, and so homogeneous sonochemistry is often quite sluggish. On the other hand, there is no possibility of contamination from erosion of the titanium horn. [Pg.86]

Insertion of nano-materials into mesoporous materials-. Ultrasonic radiation has been used for the insertion of amorphous nano-sized catalysts into the mesopores. [Pg.594]

Because of the differential partitioning of hydroxide and phenoxide anions into organic solvents by quaternary ammonium cations, the catalysts generally have little effect on the Reimer-Tiemann reaction of phenols with dihalocarbenes [15]. Cetyltrimethylammonium bromide has been used in the two-phase dichloromethyl-ation of polysubstituted phenols (Scheme 7.21, Table 7.10) under Makosza s conditions [16,17] ring expansion of the reaction products provides an effective route to tropones. The rate of the reaction is enhanced by ultrasonic radiation [16]. [Pg.342]

Some years ago we studied the absorption of ultrasonic radiation in water solutions of phospholipid vesicles. Excess absorption was seen in a... [Pg.243]

Reformatsky reaction.6 Ultrasonic radiation is beneficial in the Reformatsky reaction. Yields are > 90%, and the rate is enhanced. Specially activated zinc is not necessary. However, iodine and potassium iodide are effective additives, possibly by suppressing enolization. The solvent of choice in this variation is dioxane. [Pg.642]

An alternative approach is to treat concentrate to reduce viscosity. Berk (18), using ultrasonic radiation, succeeded in lowering viscosity of 60° Brix concentrate to 25% of its initial level. Viscosity of 70° Brix concentrate prepared from this material was only 50% higher than that of untreated 60° Brix concentrate. Viscosity of 70° Brix concentrate prepared without ultrasonic treatment was nearly 8 times that of 60° Brix concentrate. Irradiation was more effective at an intermediate stage of concentration (e.g., 60° Brix) than after concentration to 70°Brix. [Pg.112]

Radiation grafting [83, 84, 85, 86, 87, 88, 89] is a very versatile and widely used technique by which surface properties of almost all polymers can be tailored through the choice of different functional monomers. It covers potential applications of industrial interest and particularly for achieving desired chemical and physical properties of polymeric materials. In this method, the most commonly used radiation sources are high-energy electrons, y-radiation, X-rays, U.V.-Vis radiation and, more recently, pulsed laser [90], infrared [91], microwave [92] and ultrasonic radiation [93]. Grafting is performed either by pre-irradiation or simultaneous irradiation techniques [94, 95]. In the former technique, free radicals are trapped in the inert atmosphere in the polymer matrix and later on the monomer is introduced into... [Pg.244]

Low energy initiation techniques [179, 180, 181] (near infrared, ultrasonic radiation and line tuneable pulse laser) have lately emerged to be better alternatives to the high-energy radiations (y-irradiation and e-beam). Laser-induced polymerisation of monomers have attracted significant attention in recent years generating a considerable literature published on both pulsed... [Pg.269]

In 1842, Christian Doppler discovered that the wavelength of sound is a function of the receiver s movement. The transmitter of a Doppler flowmeter projects an ultrasonic beam into the flowing stream and detects the reflected frequency, which is shifted in proportion to stream velocity. The difference between the transmitted and reflected velocities is called the beat frequency, and its value relates to the velocity of the reflecting surfaces (solid particles and gas bubbles) in the process stream. For accurate readings it is important that the ultrasonic radiation be reflected from a representative portion of the flow stream. The main advantage of Doppler meters is their low cost, which does not increase with pipe size, whereas their main limitation is that they are not suitable for the measurement of clean fluids or gases. [Pg.435]

As shown in Figure 9.7, Aoki et al. [34] were able to explain why the mean diameter of the ag omerates first decreased and then increased, with increased exposure time to the ultrasonic radiation at power levels above that necessary for cavity formation. These results show the competitive nature of the two processes (deag omeration and ag omeration) taking place in the viltrasonic bath. This increase in particle size is real in that observations of the particle size without... [Pg.377]

Ultrasonic radiation of perfluoroalkyl iodides may be used to form zinc reagents which undergo standard reactions (Figure 10.13). [Pg.371]

The US bath Is the most widely available laboratory source of ultrasonic radiation. Small cleaning baths are Inexpensive. [Pg.15]

The capabilities of ultrasonic radiation forces for manipulating suspended particles have been the subject of a broad spectrum of experimental research. The effectiveness of particle-liquid separation by ultrasonic radiation forces depends on the acoustic distribution in a standing-wave field. In a US standing wave, suspended particles of appropriate... [Pg.153]

Radiation and Electrocution—Radiation and electrocntion are sometimes used to kill pests in a limited area. The electric screens in snch places as outdoor restaurants and amnsement parks are used to attract and electrocute a variety of nocturnal insect pests. Ionizing radiation is used to sterilize pests by destroying reprodnctive tissues, and ultrasonic radiation is used to kill pests in some prodncts. [Pg.83]

Jana, A.K. Agarwal, S. Chatteijee, S.N. Ultrasonic radiation induced hpid peroxidation in hposomal membrane. Radiat. Environ. Biophys. 1986, 25, 309-314. [Pg.986]

Analytical chemistry is one of the chemical areas where ultrasonic radiation has been only infrequently used. This auxiliary technique could be a powerful aid in the acceleration of various steps of the analytical process. [Pg.43]

Nanostructured LaNiOs was prepared by co-precipitation under ultrasonic radiation [120], Using various characterization methods and evaluation of catalytic activity, the effects of ultrasound on the structural properties and catalytic activity of LaNiOs were studied. The TEM showed that the ultrasound could cause a decrease in the particle size. The average particle size of LaNiOs prepared by sonochemistry is 20 nm. The specific surface area of LaNiOs is 11.27 m g h Ultrasound could lead to increased surface oxide content and surface crystal oxygen vacancies. The TPR result showed that the LaNi03 prepared by sonochemistry has a lower reduction temperature and a higher ratio of surface oxygen to crystal oxygen. The evaluation of catalytic activity showed that ultrasound could increase the catalytic activity of LaNiOs for NO decomposition. [Pg.143]

The values of acoustic power obtained were correlated with the values of oscillation amplitude of an ultrasonic radiator. The latter were obtained using feedback detectors and valve voltmeter. In the following experiments, the values of feedback voltage give an opportunity to indicate the values of acoustic power at which the melt starts to cavitate. A decrease in acoustic power introduced in the... [Pg.107]

The numeric multiplier 2 in Eq. (11) reflects the fact that the total period of operation consists of two successive treatments with an interruption. Such mode of the treatment is due to the kinetics of the degassing process when bubbles formed in a cavitation field must have time to coagulate and rise to the melt surface. From this point of view, continuous ultrasonic radiation may hamper the process and decrease its efficiency. [Pg.127]

Ultrasonic nebulization This has been applied since the early work on ICP-AES [151], Both nebulizer types where the sample liquid flows over the nebulizer transducer crystal and types where the ultrasonic radiation (at 1 MHz frequency) is focussed through a membrane on the standing sample solution have been used. When applying aerosol desolvation the power of detection of ICP-AES can be improved by a factor of 10 by using ultrasonic nebulization. This specifically applies to elements such as As, Cd and Pb, which are of environmental interest. However, because of the limitations discussed in Section 3.2, the approach is of particular use in the case of dilute analytes such as in water analysis [150]. Additional fine detailed development, however, is regularly carried out, as with ICP-AES the process is crucial for elements such as Cd, As and Pb for which threshold values in fresh water samples can just still be measured reliably with this type of sample introduction. Such a development is the microultrasonic nebulizer (pUSN) operated with argon carrier gas, as described by Tarr et al. [410]. [Pg.228]


See other pages where Ultrasonic radiation is mentioned: [Pg.97]    [Pg.1048]    [Pg.387]    [Pg.151]    [Pg.179]    [Pg.576]    [Pg.146]    [Pg.148]    [Pg.806]    [Pg.1527]    [Pg.1639]    [Pg.447]    [Pg.246]    [Pg.270]    [Pg.138]    [Pg.23]    [Pg.49]    [Pg.268]    [Pg.979]    [Pg.372]    [Pg.184]    [Pg.465]    [Pg.264]    [Pg.1165]   
See also in sourсe #XX -- [ Pg.687 ]




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Ultrasonic radiation effects, temperature

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