No abstract

This study aims to prepare ultrasound-targeted glial cell-derived neurotrophic factor (GDNF) retrovirus-loaded microbubbles (M pLXSN-GDNF) to verify the properties of the microbubbles and to study the therapeutic effect of the GDNF retrovirus-loaded microbubbles combined with ultrasound (U) to open the blood–brain barrier (BBB) in a Parkinson’s disease (PD) model in rats, allowing the retrovirus to pass through the BBB and transfect neurons in the substantia nigra of the midbrain, thereby increasing the expression of GDNF. The results of western blot analysis revealed significant differences between U + MpLXSN-EGFP, U + M + pLXSN-GDNF, and M pLXSN-GDNF (P < 0.05) groups. After 8 weeks of treatment, the evaluation of the effect of increased GDNF expression on behavioral deficits in PD model rats was conducted. The rotation symptom was significantly improved in the U + MpLXSN-GDNF group, and the difference before and after treatment was significant (P < 0.05). Also, the content of dopamine and the number of tyrosine hydroxylase-positive (dopaminergic) neurons were found to be higher in the brain of PD rats in the U + M pLXSN-GDNF group than in the control groups. Ultrasound combined with GDNF retrovirus-loaded microbubbles can enhance the transfection efficiency of neurons in vivo and highly express the exogenous GDNF gene to play a therapeutic role in PD model rats.

For fans of a variable-cycle engine, a good aerodynamic performance over a wide range of rotating speeds is essential. However, when supersonic cascades designed for a high upstream Mach number operate under a low upstream Mach number, a starting problem may occur, which significantly decreases the aerodynamic performance of fan blades. As a result, the operating range of the supersonic cascades is severely limited. To solve the starting problem caused by the mismatch between geometry of supersonic cascades and upstream Mach number, a morphing supersonic cascade is developed. Thus, this study mainly focuses on the effect of the static deformation of supersonic cascades driven by smart materials on aerodynamic characteristics under a low upstream Mach number. To investigate this issue, numerous simulations are conducted on an S-type cascade by finite element method and computational fluid dynamics. As demonstrated by flow structure analysis, the morphing cascades are started under certain morphing configurations while the original cascade operates at nonstarted state. The results show that the deformation driven by smart materials alters the shock wave structures under a low upstream Mach number by adjusting key cascade geometric parameters. Specifically, the morphing cascades achieve 80% reduction of detached shock loss compared with the original cascades.