Ultrasound technique

Fig. 25. An example of Doppler color flow mapping, a real-time ultrasound technique that displays the dynamics of blood flow in color along with static tissue information in black and white. The image shows the record of a leaky mitral valve during systole.

Ultrasonic irradiation of a liquid leads to the generation of cavitation phenomenon which comprised of unique reaction fields in addition to physical and mechanical effects the formation of micro-meter sized bubbles, formation of bubbles with high temperature and high pressure conditions, formation of shock waves, and strong micro-stirring effects are produced. Table 5.1 shows representative ultrasound techniques to synthesize inorganic and metal nanoparticles and nanostructured materials. 

Table 5.1 Representative ultrasound techniques to synthesize inorganic and metal nanoparticles and nanostructured materials...

Carbon disulphide should not be used as the solvent for alkylation of fS-diketones, as the carbanion reacts preferentially with the solvent to generate the dithiocarboxyl-ate derivative, which undergoes mono- and dialkylation (Scheme 6.9) [95]. Ketene thioacetals have also been isolated from acetophenones (60-80%) and cyclopenta-diene (80%) using an ultrasound technique in carbon disulphide [96] and, in a similar manner, pyrazol-5-ones form pyrazole-4-dithiocarboxylic esters [97]. 

Lipid microparticles and nanopellets for oral use were first described by Speiser [11]. Nanopellets are prepared by dispersing melted lipids with high-speed mixers or via ultrasound techniques. Lipospheres developed by Domb are also prepared from dispersed lipids by stirring and sonication [12]. These preparations may contain a high degree of microparticles, which thus excludes an intravenous injection. For other routes of application (e.g., peroral administration), these microparticles might not be a serious problem. Furthermore, the dispersions may be contaminated by metal shed. With optimized conditions, however, mean particles sizes of 1(X) to 200 nm are possible [13]. 

Gonadotropins are used to treat infertility in women with potentially functional ovaries who have not responded to other treatments. The therapy is designed to simulate the normal menstrual cycle as far as is practical. A common protocol is daily injections of menotropins for 9 to 12 days, until estradiol levels are equal to that in a normal woman, followed by a single dose of hCG to induce ovulation. Two problems with this treatment are risks of ovarian hyperstimulation and of multiple births. Ovarian hyperstimulation is characterized by sudden ovarian enlargement associated with an increase in vascular permeability and rapid accumulation of fluid in peritoneal, pleural, and pericardial cavities. To prevent such occurrences, ovarian development is monitored during treatment by ultrasound techniques and by measurements of serum levels of estradiol. 

Cho, B., Irudayaraj, J., and Bhardwaj, M. C. (2001). Rapid measurement of physical properties of Cheddar cheese using a non-contact ultrasound technique. Am. Soc. Agric. Eng. 44, 1759-1762. 

Surprisingly, zinc has been inserted directly into C—F bonds using ultrasound techniques, and in the presence of metal salts, e.g. SnCl2. The reactivity of the system appears to depend at least partly on the electron affinity of the aromatic system, because hexa-fluorobenzene is relatively unreactive in the process [57] (Figure 10.16). 

A major complication of intravenous infusion is thrombophlebitis, which is a principle limitation of peripheral parenteral nutrition. Its precise pathogenesis is unclear, but venospasm has been proposed as the most likely cause. However, in a study with ultrasound techniques to monitor vein caliber, there was no evidence to support this hypothesis, although thrombophlebitis was observed (10). The author suggested that the initiating event may be venous endothelial trauma, caused by the venepuncture itself, abrasion at the catheter tip, or the delivery of the feeding solution. 

The acceleration of substitution reactions with azides using ultrasound techniques (Scheme 31) has not yet been investigated in detail. Activated primary halides react with trimethylsilyl azide (TMS-A) under particularly mild and absolutely neutral conditions (Scheme 31). Secondary and tertiary cyclic halides were treated with TMS-A/SnCU in CH2CI2 or CHCI3 to yield the corresponding azido compounds." Very impressive results with yields of about 90% were in this case reported in the adamantane and diamantane series." High solubility in organic solvents is also noticed with acetyl azide, which, prepared in situ, has also been used for azide syntheses. The scope of this reaction has still to be determined, however." Hassner noticed nearly quantitative yields of azides when alkyl halides (or tosyl-ates) were treated with polymeric quaternary ammonium azides. 

Ultrasound extraction (sonication) is based on the conversion of AC current at 50/60 Hz into electrical energy at 20 kHz and its transformation in mechanical vibrations. Due to the cavity, microscopical vapor bubbles are formed and, after implosion, they produce strong shockwaves into the sample. For isolating the (semi)volatile organic compounds, the liquid-liquid ultrasound technique is applied to samples such as soils, sediments, coal, etc. The process is also useful for the biological materials destruction (Loconto, 2001). Sonication extraction is faster than Soxhlet extraction (30-60 min per sample) and allows extraction of a large amount of sample with a relatively low cost, but it still uses about as much solvent as Soxhlet extraction, is labor intensive, and filtration is required after extraction. 

Ceria was loaded on mesoporous titania by deposition precipitation (DP) method. Before deposition, the mesoporous material was suspended in water by ultrasound technique. Ceria was deposited by precipitation of Ce(N03)3 6H2O with Na2C03 at 60 °C and pH 9.0. Analytical grade chemicals were used in the support preparation. The precipitate was aged in a course of 1 h at the same temperature, filtered and washed carefully until absence of N03 ions. The sample was dried under vacuum at 80 °C and calcined in air at 400 °C for 2 h. Ceria modifying additive is 20 wt.%. The sample was labeled as CeMTi. 

Flg.1. Measurements during the cultivation of recombinant E. coli K-12 MF cells in a 60-1 working volume air lift tower loop reactor without gene expression using SE9 antifoam agent (AFA) [50,51]. a Variation in the mean bubble velocity. Bubble velocity measured in situ by an ultrasound Doppler technique. AFA added to the medium, b Variation in the specific interfacial area (m ) measured in situ by an ultrasound technique... 

Ultrasound in Intussusception 199 Ultrasound Technique 199 Assessment for Reducibility 199 Non-operative Reduction of Intussusception 201... 

Science for Materials in the Frontier of Centuries Advantages and Challenges, International Conference, Kyiv, Ukraine, Nov. 4-8,2002, Vol. 1, ed. V.V. Skorokhod, Frantsevich Institute for Problems of Materials Science of National Academy of Science of Ukraine, Kiev, Ukraine, 2002 R 300 M.D. Glinchuk, V.V. Laguta and l.P. Bykov, New Generation of the Materials for Sensors, Actuators and Ultrasound Technique on the Base of Ferroelectric Relaxors , p. 28... 

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