Ultrasound Methods

The weld depths penetration for gold-nickel alloy and tantalum cylinders have been well controlled by an entirely contactless ultrasound method. Nevertheless, the development of signal and image processing will allow to increase the resolution of the ultrasonic images. Moreover, in order to be able to size quite well the lacks of weld penetration, the simulation of the interaction beam-defect is presently developed in our laboratory. 

Welding is easy using thermal processes, possible with ultrasound methods but impossible with the high-frequency technique. 

Particle size reduction may be achieved with different kinds of miUing equipment such as media miUs. Alternatively, flow impingement or ultrasound methods can be used for dispersion. Some of the pigments can also be dissolved in certain solvents and reprecipitated as extremely fine particles. AU of these processes generate a considerable amount of fresh surface. If unstabilized, these surfaces collapse back together and particle size reduction... 

Now, since the ultrasound method gives the difference of the hydration numbers, while the compressibility method gave the sum, individual values can be calculated (Table 2.7). 

It would be a tremendous loss if palpation and percussion of the liver and spleen were inadequately learned, inappropriately performed and no longer mastered as a basic examination technique for interpretative purposes on account of ultrasound methods. 

Pettier and Suslick [38] have recently developed an ultrasound method for enhancing the reactivity of calcium in the reduction of aromatic hydrocarbons. Under the action of ultrasound the reductions proceed more quickly (xlO) and require less metal than reactions conducted with an efficient mechanical stirrer. In addition, selective reduction of aromatic hydrocarbons could be accomplished by addition of specific alcohols under the action of ultrasound at ambient temperature. 

The kinetics of formation and disintegration of micelles has been studied for about thirty years [106-130] mainly by means of special experimental methods, which have been proposed for investigation of fast chemical reaction in liquids [131]. Most of the experimental methods for micellar solutions study the relaxation of small perturbations of the aggregation equilibrium in the system. Small perturbations of the micellar concentration can be generated by either fast mixing of two solutions when one of them does not contain micelles (method of stopped flow [112]), or by a sudden shift of the equilibrium by instantaneous changes of the temperature (temperature jump method [108, 124, 129, 130]) or pressure (pressure jump method [1, 107, 116, 122, 126]). The shift of the equilibrium can be induced also by periodic compressions or expansions of a liquid element caused by ultrasound (methods of ultrasound spectrometry [109-111, 121, 125, 127]). All experimental techniques can be described by the term relaxation spectrometry [132] and are characterised by small deviations from equilibrium. Therefore, linearised equations can be used to describe various processes in the system. 

Investigation of ERC by dielectric and ultrasound methods [138] detected three relaxation transitions. The low-temperature transition (220-246 K at 10 -10 Hz) is related to the molecular mobility of the polyacrylonitrile butadiene. Relaxation transitions related to molecular mobility, either in the boundary layer between the rubber and the resin or in the regions of structure formed in the course of the cross-linking, correspond to higher temperatures. But, as this paper points out, the higher-temperature relaxation transitions do not appear in the frequency dependences. They can be detected only in the dependence of the modulus of elasticity on the temperature. 

In order to evaluate the performance of the three selected methods, wheat blank samples spiked at 50 (Xg/kg were treated, applying the three procedures showing the obtained results. It can be observed that the best results were obtained when QuEChERS procedure was used, allowing the extraction of more than 80 compounds with suitable recoveries (70-120%) and relative standard deviation (RSD) lower than 20%. When the ultrasound method was applied, more than 80 compounds were extracted, but only 36 compounds, including all the mycotoxins and biopesticides assayed in this study, were quantitatively extracted, whereas this approach was not suitable for most of the selected pesticides. Finally, an intermediate situation was obtained when the procedure described by Mol et al. was applied. More than 50 compounds were extracted with recoveries ranging from 70% to 120% and RSD values lower than 20%. 

In addition, the functional changes in penile blood flow as seen in erectile dysfunction can be studied appropriately with color Doppler ultrasound methods. 

Elastic constants of bulk crystalline materials are commonly measured by means of the ultrasound method where sound velcities in specific crystallographic orientations are monitored (( )). For example, the case of a cubic crystal for which the longitudinal wave speed along the [100] direction is a/cii/p, where p is the density of the crystal. Likewise, the shear wave speed along the [100] direction is p. The speed of the longitu-... 

The points B and X correspond to the first and second heart sounds. They are synchronous with the maximal deflection at the apex and the closure of the aortic valve, respectively. In some cases the identification of the B point location is difficult because the characteristic upstroke that provides a marker of this point is not always pronounced [3]. The E point is defined by the peak of dZidt curve which reflects the maximal derivative in the impedance. Ultrasound method measurements confirm that the E point may be associated with the maximal velocity of the heart ejection [4]. For ICG the first maximum (i.e. E-wave) is related to the systolic phase of the cardiac cycle and the second maximum with a smaller amplitude (O-wave) is related to the diastolic phase. The amplitude of the E-wave is proportional to the SV, and the am-... 

Yamazaki H, Saitoh S, Seki H et al (1999) Peroneal nerve palsy caused by intraneural ganglion. Skeletal Radiol 28 52-56 Yashar AA, Adler RS, Grady-Benson JC et al (1996) An ultrasound method to evaluate polyethylene component wear in the knee replacement arthroplasty. Am J Orthop 25 702-704... 

A one-pot three-component condensation reaction of aldehydes 51, malononitrile 108, and thiophenols 109 in the presence of boric acid as the catalyst has been achieved in aqueous medium by conventional heating or ultrasonic irradiation affording 2-amino-3,5-dicarbonitrile-6-thiopyridines 110 (Scheme 36) [92]. The products are obtained in almost same yield under conventional and ultrasound method. However, the reaction time decreases from 25 to 50 min under thermal condition to 8-15 min under ultrasonic irradiation. 

ZrO(C)C2H5)4, modifying Paal-Knorr method assisted by an ultrasonic cleaner bath (intensity of 0.35 W/cm ) in an open vessel at 40 C (Scheme 6). The traditional protocol reported yields between 50% and 60% on stirring for 3 days at room temperature in the absence of catalyst. The ultrasound method using ZrC showed better yields (98%) in lesser time frame (7 min). 

Conventional Method Ultrasound Method Conventional Method Ultrasound Method... 

Another example of application of MW and ultrasound methods is the one-pot, tandem oxidation of cyclic alcohols to their respective lactones using KHSO5 (potassium peroxy-monosulfate) as oxidant and an IL as a solvent (Scheme 51). Ultrasound and MW irradiation reduced the reaction time for the cyclohexanol oxidation by Oxone , catalyzed by a TEMPO nitroxyl radical, in the presence of tetrabutylammonium bromide (TBAB) in [bmimjppj (bmim= l-butyl-3-methylimidazolium), from 8, using normal heating, to 5 and 0.5 h, respectively, with similar yields of ca. 80%. A new class of ILs with peroxymonosulphate anions was also synthesized and employed in the model oxidation. ... 

Fig. 7 Thickness comparison between the juCT and ultrasound methods for the cancellous core layer within the ROI...

Fei(CO)9/Ultrasound Method of Complexation. The reaction of Fe2(CO)9 with sensitive dienes can be promoted by ultrasound (eq 11). Syntheses of a variety of tricarbonyKri -diene)iron(O) complexes (16) use the convenient high-yielding sonication method. ... 

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