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Incidence of cavitation in the fragmentation process of extracorporeal shock wave lithotriptors (1994)

Rink, K. ; Delacrétaz, G. ; Pittomvils, G. ; [et al.]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 64 (1994), S. 2596-2598

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ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: The fragmentation mechanism occurring in extracorporeal shock wave lithotripsy (ESWL) is investigated using a fiber optic stress sensing technique. With our technique, we demonstrate that cavitation is a major cause of fragmentation in ESWL procedures. When a target is placed in the operating area of the lithotriptor, two shock waves are detected. The first detected shock wave corresponds to the incoming shock wave generated by the lithotriptor. The second shock wave, detected some hundreds of microseconds later, is generated in situ. It results from the collapse of a cavitation bubble, formed by the reflection of the incoming shock wave at the target boundary. This cavitation induced shock wave generates the largest stress in the target area according to our stress sensing measurements.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.111537

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Tyrosine group behaviour in bovine α-lactalbumin as revealed by its Raman effect (1987)

Dael, H. ; Lafaut, J. P. ; Cauwelaert, F.

Springer

European biophysics journal 14 (1987), S. 409-414

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ISSN: 1432-1017

Keywords: Raman spectroscopy ; α-lactalbumin ; tyrosine ; protein conformation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Physics

Notes: Abstract Side group behaviour is often used for conformational studies of proteins. We have performed Raman spectroscopic measurements on the tyrosine groups of bovine α-lactalbumin. The 850/830 cm-1 doublet intensity ratio is a direct measure of the negative charge state of the phenolic oxygen and of the tyrosine environment. pH measurements confirm the existence of an acid conformer of BLA, that is comparable to, but clearly distinguishable from the apo-conformer. Following the Siamwiza theory, the Tyr groups in this partially unfolded state are situated in a more hydrophobic environment. Observation of Tyr groups behaviour in the denaturated states obtained by thermal or chemical treatment leads us to the same conclusion. However, the behavior of tryptophan groups is quite different. In an unfolded sate, the Trp residues are mostly exposed to the solvent. The stabilizing role of Ca2+ and Na+ ions in BLA is also investigated.