Tham khảo tài liệu 'hydrodynamics advanced topics part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 106 Hydrodynamics - Advanced Topics It is known from Bagratashvili et al. 2006 that the mechanical action on cartilages in the hertz frequency range actively stimulates the synthesis of collagen and proteoglycans even at relatively small amplitudes. The above estimations show that the pressure on biotissue provided by the vapor-gas bubbles can reach tens of kilopascals. In accordance with Buschmann et al. 1995 Millward-Sadler Salter 2004 such pressures in the hertz frequency range can lead to regenerative processes in cartilage owing to the activation of the interaction of the extracellular matrix with the mechanoreceptors of chondrocytes integrins . Laser-induced generation of bubbles microjets Note an interesting phenomenon in the experiments on the generation of bubbles in the vicinity of the blackened tip surface of the fiber in the water cell bubble microjets can be generated at a laser power of less than 3 W Fig. 11 Yusupov et al. 2010 . The lengths of the microjets Fig. 11a which always start in the immediate vicinity of the fiber tip reach several millimeters the transverse sizes normally range from 10 to 50 pm and the sizes of the bubbles that form the jets range from several to ten microns. The lifetime of the microjets ranges from a few fractions of a second to tens of seconds. A microjet that emerges at a certain spot on the tip surface remains attached to this spot and exhibits bending relative to the mean position. Bubble microjets didn t use to be continuous from start to end the discontinuities used to appear on them which used to restore quite often. The observations show Yusupov et al. 2010 that the discontinuities are always related to the hydrodynamic perturbations and are caused by relatively large bubbles that move in the vicinity of the microjet. The appearance of quite a large bubble attached to the fiber tip caused the bubble microjet bending around large bubble Fig. 11b . Thus we conclude that two conditions must be satisfied for the .
