Enhancement of aerodynamic performance of a bristled wing by elliptic cylinders.

Enhancing the aerodynamic performance of bristled wings is an important topic for small flying robotics. This paper numerically investigates this situation at very low Reynolds numbers by using elliptic cylinders as the bristles instead of circular cylinders. Optimal configuration of the bristled wing with five elliptic cylinders is obtained, which corresponds to the maximum lift. The results show that, compared with the case of circular cylindrical bristles, the aerodynamic performance of the elliptical bristles can be enhanced effectively. The enhancement can be more significant as the aspect ratio of the ellipses increases and the gap width decreases. The bristled wing generates more lift compared to a flat-plate wing with a length five times that of the major axis of an ellipse. For the cases that the attack angleαfor the whole wing is equal to those for the elliptical bristlesθ, the optimal attack angle for ellipses maximizing the total lift force of the five-bristle model is between 40° and 45°. Forα ≠θwith the Reynold numberRe≪ 0.1, the optimal ellipse attack angle is between 40° and 45°. Forα ≠θwithRe∼ 1, the optimal ellipse attack angle deviates heavier from the range between 40° and 45° at someαvalues and reaches approximately 32° atα= 20°. This paper can lay a foundation for optimal design of small flying robotics and enhancement of flow through porous structures in future.

Minocycline inhibits smooth muscle cell proliferation, migration and neointima formation after arterial injury.

The tetracyclines are antimicrobials that also inhibit expression of certain matrix metalloproteinases (MMPs). We conducted a series of experiments to determine if minocycline could inhibit MMP expression and limit human aortic smooth muscle cell (SMC) proliferation and migration. Analysis of SMC proliferation was performed after cells were grown in minocycline-incubated media. SMC migration activity was assayed in a micro-Boyden chamber. Western blotting revealed that minocycline reduced SMC production of MMP-2 in a dose dependent manner. Increasing doses of minocycline progressively reduced SMC proliferation to 49% of control values and limited SMC migration to 15% of control. When administered to rats with balloon injured carotid arteries, intraperitoneal doses of minocycline (70-100 mg/kg) reduced neointima formation by 76%, but were associated with liver toxicity. Higher doses were lethal and lower doses were ineffective. Minocycline, applied to injured arteries in a pluronic gel with a low pH, was also ineffective. In summary, minocycline lowers MMP-2 expression, reduces SMC proliferation and migration, and inhibits neointimal hyperplasia, but its efficacy is limited by systemic toxicity.