The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles a...The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles and surrounding tissues.Therefore, the cavitation dynamics and resultant mechanical stress of two-interacting bubbles in the viscoelastic tissues are numerically investigated, especially focusing on the effects of the adjacent bubble. The results demonstrate that the mechanical stress is highly dependent on the bubble dynamics. The compressive stress and tensile stress are generated at the stage of bubble expansion and collapse stage, respectively. Furthermore, within the initial parameters examined in this paper, the effects of the adjacent bubble will distinctly suppress the radial expansion of the small bubble and consequently lead its associated stresses to decrease. Owing to the superimposition of two stress fields, the mechanical stresses surrounding the small bubble in the direction of the neighboring bubble are smaller than those in other directions. For two interacting cavitation bubbles, the suppression effects of the nearby bubble on both the cavitation dynamics and the stresses surrounding the small bubble increase as the ultrasound amplitude and the initial radius of the large bubble increase, whereas they decrease with the inter-bubble distance increasing. Moreover, increasing the tissue viscoelasticity will reduce the suppression effects of the nearby bubble, except in instances where the compressive stress and tensile stress first increase and then decrease with the tissue elasticity and viscosity increasing respectively. This study can provide a further understanding of the mechanisms of cavitation-associated mechanical damage to the adjacent tissues or cells.展开更多
目的:探讨术前应用地塞米松对腹腔镜全子宫切除手术术后恶心、呕吐(PONV)发生率的影响。方法:收治择期行腹腔镜全子宫切除患者60例,随机分为A组和B组,各30例。A组用地塞米松,B组用昂丹司琼。结果:相比B组,A组患者术后6～24 h PONV发生...目的:探讨术前应用地塞米松对腹腔镜全子宫切除手术术后恶心、呕吐(PONV)发生率的影响。方法:收治择期行腹腔镜全子宫切除患者60例,随机分为A组和B组,各30例。A组用地塞米松,B组用昂丹司琼。结果:相比B组,A组患者术后6～24 h PONV发生率及术后24 h总的PONV发生率显著降低(P<0.05)。结论:术前2 h应用地塞米松能显著降低术后24 h PONV发生率,其效果优于术中应用昂丹司琼。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.11904042)the Natural Science Foundation of Chongqing,China (Grant No.cstc2019jcyj-msxmX0534)the Science and Technology Research Program of Chongqing Municipal Education Commission,China (Grant No.KJQN202000617)。
文摘The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles and surrounding tissues.Therefore, the cavitation dynamics and resultant mechanical stress of two-interacting bubbles in the viscoelastic tissues are numerically investigated, especially focusing on the effects of the adjacent bubble. The results demonstrate that the mechanical stress is highly dependent on the bubble dynamics. The compressive stress and tensile stress are generated at the stage of bubble expansion and collapse stage, respectively. Furthermore, within the initial parameters examined in this paper, the effects of the adjacent bubble will distinctly suppress the radial expansion of the small bubble and consequently lead its associated stresses to decrease. Owing to the superimposition of two stress fields, the mechanical stresses surrounding the small bubble in the direction of the neighboring bubble are smaller than those in other directions. For two interacting cavitation bubbles, the suppression effects of the nearby bubble on both the cavitation dynamics and the stresses surrounding the small bubble increase as the ultrasound amplitude and the initial radius of the large bubble increase, whereas they decrease with the inter-bubble distance increasing. Moreover, increasing the tissue viscoelasticity will reduce the suppression effects of the nearby bubble, except in instances where the compressive stress and tensile stress first increase and then decrease with the tissue elasticity and viscosity increasing respectively. This study can provide a further understanding of the mechanisms of cavitation-associated mechanical damage to the adjacent tissues or cells.
文摘目的:探讨术前应用地塞米松对腹腔镜全子宫切除手术术后恶心、呕吐(PONV)发生率的影响。方法:收治择期行腹腔镜全子宫切除患者60例,随机分为A组和B组,各30例。A组用地塞米松,B组用昂丹司琼。结果:相比B组,A组患者术后6～24 h PONV发生率及术后24 h总的PONV发生率显著降低(P<0.05)。结论:术前2 h应用地塞米松能显著降低术后24 h PONV发生率,其效果优于术中应用昂丹司琼。
