Ultrasound low-intensity

Low-intensity ultrasound uses power levels (typically < 1 W cm 2) that are considered to be so small that the ultrasonic wave causes no physical or chemical alterations in the properties of the material through which the wave passes, i.e. it is nondestructive. However,... 

Ultrasonically assisted extraction is also widely used for the isolation of effective medical components and bioactive principles from plant material [195]. The most common application of low-intensity ultrasound is as an analytical technique for providing information about the physico-chemical properties of foods, such as in the analysis of edible fats and oils (oil composition, oil content, droplet size of emulsions, and solid fat content) [171,218]. Ultrasonic techniques are also used for fluids characterisation [219]. 

Xie B, Wang L, Liu H (2008) Using low intensity ultrasound to improve the efficiency of biological phosphorus removal. Ultrason Sonochem 15 775-781... 

Low intensity ultrasound has also been applied to the Simmons-Smith cyclopropanation of olefins with zinc-diiodomethane (237). This reaction normally will not occur without activation of mossy Zn with I2 or Li, and was difficult to scale-up due to delayed initiation. Yields upon sonication are nearly quantitative, activation of the Zn is unnecessary, and no delayed exotherms are observed. In reactions with another class of organic dihalides, ultrasonic irradiation of Zn with a,a -dibromo-o-xylene has proved a facile way to generate an o-xylylene-like species [Eq. (49)],... 

The Cannizzaro reaction under heterogeneous conditions (solid-liquid) using calcined barium hydroxide as base is greatly accelerated by low intensity ultrasound (cleaning... 

This maximum is thought, from viscosity and enthalpy of mixing studies (Fig. 5.42), to be due to the formation of a H-bonded monomer-water complex. Previous investigations of the solvolysis of 2-chloro-2-methylpropane had led us to conclude that low intensity ultrasound (< 2 W cm ) was capable of destroying H-bonds and if this were... 

Adler, J., Spurna, V., and Hrazoira, I. 1988. The effect of low intensity ultrasound on mammalian cell cultures. Studia Biophysica 128 13-20. 

Wang, Q., Tolkach, A., and Kulozik, U. (2006). Quantitative assessment of thermal denaturation of bovine a-lactalbumin by low-intensity ultrasound in comparison to HPLC and DSC. J. Agric. FoodChem. 54, 6501-6506. 

Low intensity ultrasound as a probe to elucidate the relative follicular contribution to total transdermal absorption. Pharm. Res. 1998, 15, 85-92. 

Generally, low intensity ultrasound can increase the activity of enzymes and immobilized enzymes, or can improve the metabolism of cells by the improvement of mass transfer to substrates. One example is the enzymatic decomposition of mandelonitrile by mandelonitrile lyase in di-isopropyl ether which has been accelerated 10-fold by ultrasound [66], The mandelonitrile lyase was not denatured by 30 kHz operating at 0.5 W cm-2 and pulsed at 15 s per min. 

Most recently, low-intensity ultrasound has been used to enhance gene transfection by liposome.139 In this study, ultrasound exposure (1 MHz, 0.4 W/cm2) for 60 seconds enhanced transfection of naked or liposome-complexed luciferase reporter plasmid into cultured porcine vascular smooth muscle and endothelial cells. These results with liposome-complexed reporter plasmid are similar to those of Unger et al., who showed that relatively low levels of ultrasound energy (0.5 W/ cm2) enhanced gene expression.140 In these two studies, ultrasound exposure did... 

Ultrasound is used in a variety of industrial applications, with a very wide range of objectives. Low-intensity ultrasound (with typically /process control and nondestructive testing of products (Knorr et al., 2004 Leemans and Destain, 2009), whereas high-intensity ultrasound (with I of 10-1000 Wcm ) is applied to intensify processes, such as the inactivation of microorganisms (Lee et al., 2009), homogenization (Wu et al., 2001a), or drying (Mulet et al., 2003 see also Chapter 8 of this volume). These very different applications underline the fact that the parameters of ultrasound and its interaction with a product must be well understood in order to allow successful process development. 

As pointed out, the characteristics of ultrasonic waves applied in a medium determine the effects produced. So, there are ultrasound applications that use low ultrasound intensities (<1 Wcm ) and high frequencies (>1 MHz) which do not affect the medium significantly. In these cases, the change in the characteristics of ultrasound waves traveling through the medium is used to determine the medium s properties. As they constitute a nondestructive inspection technique, low-intensity ultrasound applications have been the subject of intensive research and development over the past few years (Benedito et al., 2002 Benedito et al, 2004 Ninoles et al., 2011). 

L. B. Peril, T. Kondo, Y. Tabuchi, R. Ogawa, Q.-L. Zhao, T. Nozaki, T. Yoshida, N. Kudo and K. Tachibana, Biomolecular effects of low-intensity ultrasound apoptosis, sonotransfection, and gene expression, Japan. J. Appl. Phys., 2007, 46, 4435-4440. 

Ploug H, Jorgensen BB (1998) A net-jet flow system for mass transfer and microsensor studies of sinking a egates. Mar Ecol Prog Ser 176 270-290 Qian Z, Stoodley P, Pitt WG (1996) Effect of low-intensity ultrasound upon biofilm structure from confocal scanning microscopy observation. Biomaterials 17 1975-1980... 

Irrechukwu, O. N., P.-C. Lin. et al. 2010. Magnetic resonance studies of macromolecular content in engineered cartilage treated with pulsed low-intensity ultrasound. Tissue Eng Part A 17(3-4) 407-415. 

Ultrasound is typically classified into two categories low-intensity ultrasound, frequently in the MHz range that is used in materials sciences and medical imaging applications, and lower frequency high-intensity ultrasound in the kHz range... 

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