Ultrasound pretreatment

Topical gene therapy acquires the penetration of a large complex to or through the skin. Ultrasound pretreatment of the skin will increase its permeability and permit the delivery of... 

High-power ultrasound has the potential to increase the pore volume and to reduce the crystallinity of cellulosic biomass. The effect of ultrasound pretreatment on the microstructure of alkaline-pretreated corn stover is shown in Figures 14.5a and b. The pretreated stover sample showed significant disruption of the cell wall (Figure 14.5b). Thermal and chemical pretreatments (acid) make the cellulose more accessible to enzyme by opening up cleavage sites. Such pretreatments however, also... 

Nitayavardhana, S., Rakshit, S.K., Grewell, D., Pometto III, A.L., van Leeuwen, J., and Khanal, S.K. 2008. Ultrasound pretreatment of cassava chip slurry to enhance sugar release for subsequent ethanol production. Biotechnology and Bioengineering, 101(3) 487 96. 

Figure 3. Dissimilar grit-size dependence of diamond nucleation densities on substrate surface pretreatments, (a) Nucleation density versus inverse abrasive paste mean-size used in polishing pretreatment.(b) Nucleation density versus single-particle mean-size used in ultrasounding pretreatment solid squares Ref. 317, blank squares Ref. 322, solid circles Ref. 323. (Reproduced with permission.)...

BenabdaUah El-Hadj T, Dosta J, Marquez-Serrano R, Mata-Alvarez J (2007) Effect of ultrasound pretreatment in mesophilic and thermophilic anaerobic digestion with emphasis on naphthalene and pyrene removal. Water Res 41 87-94... 

The most common method to extract xylan is the alkaline extraction. Several pretreatment methods can be used in association in order to break the covalent bonds that exist between xylan and other carbohydrates during the extraction (Wang Zhang, 2006). A number of articles studied the use of ultrasound on the xylan extraction. Hromadkova and coworkers reported that 36.1% of xylan was extracted from corn cobs with 5% NaOH solution at 60°C for 10 min of ultrasonication in comparison with 31.5% of xylan in the classical extraction. Both extractive methods yielded xylan with immunogenic properties (Hromadkova et al., 1999). 

Peterson and Scarrah 165) reported the transesterification of rapeseed oil by methanol in the presence of alkaline earth metal oxides and alkali metal carbonates at 333-336 K. They found that although MgO was not active for the transesterification reaction, CaO showed activity, which was enhanced by the addition of MgO. In contrast, Leclercq et al. 166) showed that the methanolysis of rapeseed oil could be carried out with MgO, although its activity depends strongly on the pretreatment temperature of this oxide. Thus, with MgO pre-treated at 823 K and a methanol to oil molar ratio of 75 at methanol reflux, a conversion of 37% with 97% selectivity to methyl esters was achieved after 1 h in a batch reactor. The authors 166) showed that the order of activity was Ba(OH)2 > MgO > NaCsX zeolite >MgAl mixed oxide. With the most active catalyst (Ba(OH)2), 81% oil conversion, with 97% selectivity to methyl esters after 1 h in a batch reactor was achieved. Gryglewicz 167) also showed that the transesterification of rapeseed oil with methanol could be catalyzed effectively by basic alkaline earth metal compounds such as calcium oxide, calcium methoxide, and barium hydroxide. Barium hydroxide was the most active catalyst, giving conversions of 75% after 30 min in a batch reactor. Calcium methoxide showed an intermediate activity, and CaO was the least active catalyst nevertheless, 95% conversion could be achieved after 2.5 h in a batch reactor. MgO and Ca(OH)2 showed no catalytic activity for rapeseed oil methanolysis. However, the transesterification reaction rate could be enhanced by the use of ultrasound as well as by introduction of an appropriate co-solvent such as THF to increase methanol solubility in the phase containing the rapeseed oil. 

Several systematic errors were investigated, mainly related to the sample pretreatment steps (microwave acid digestion, ultrasound acid leaching and slurry sampling), calibration mode and number of repeats. Experimental designs and principal components were used... 

C. Pena-Farfal, A. Moreda-Pineiro, A. Bermejo-Barrera, P. Bermejo-Barrera, H. Pinochet-Cancino and I. De-Gregori-Henriquez, Ultrasound bath-assisted enzymatic hydrolysis procedures as sample pretreatment for multielement determination in mussels by inductively coupled plasma atomic emission spectrometry, Anal. Chem., 76(13), 2004, 3541-3547. 

Tezel et al. [54] have demonstrated a significant IgG response and activation of Langerhans cells in the epidermis to a model vaccine, tetanus toxoid, after pretreatment with a 20 kHz, 100 J/cm2 ultrasound in BALB/c mice. 

Combined application of ultrasound and iontophoresis also has practical implications. The combination of ultrasound and electric current offers a twofold higher enhancement than that offered by each of them individually under the same conditions. Since ultrasonic pretreatment reduces skin resistivity, a lower voltage is required to deliver a given current during iontophoresis compared to that in controls. This should result in lower power requirements as well as possibly less skin irritation [71]. 

Katz, N.P., et al. 2004. Rapid onset of cutaneous anesthesia with EMLA cream after pretreatment with a new ultrasound-emitting device. Anesth Analg 98 371. 

At present, UV/H2O2 technology is totally commercialized. The method can be sensibly improved by combination with ultrasound [30] or by pretreatment with ozone [31]. The combination UV/H2O2/O3 has also been proposed, as we will see later. 

Source Data from Bunrith, S. waste activated sludge. 2008. Anaerobic digestibility of ultrasound and chemically pretreated Master s thesis, Asian Institute of Technology. ... 

Misused terms in relation to ultrasound-assisted solid sample pretreatment... 

Ultrasound assistance can be provided before and (or) during analysis. In those techniques which do not involve any electron exchange at the solution-electrode interface, US is normally applied prior to analysis in order to activate the electrode surface and hence in the absence of sample in electron-exchange processes, US can be applied as a pretreatment, but also during analysis. In the latter case, US can be applied during the measurement step and, in stripping techniques, during deposition of the analyte of interest on the electrode, either electrochemically or by physisorption. 

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