Impact of interstitial flow on cartilage matrix synthesis and NF-kB transcription factor mRNA expression in a novel perfusion bioreactor.

This work is focused on designing an easy-to-use novel perfusion system for articular cartilage (AC) tissue engineering and using it to elucidate the mechanism by which interstitial shear upregulates matrix synthesis by articular chondrocytes (AChs). Porous chitosan-agarose (CHAG) scaffolds were synthesized and compared to bulk agarose (AG) scaffolds. Both scaffolds were seeded with osteoarthritic human AChs and cultured in a novel perfusion system with a medium flow velocity of 0.

Uniformly valid solution for acoustic propagation in weakly tapered circular waveguides: liquid jet example.

The propagation of ultrasound down laminar liquid jets has potential applications to the stimulation of liquid drop production [J. B. Lonzaga, C.

Liquid jet response to internal modulated ultrasonic radiation pressure and stimulated drop production.

Experimental evidence shows that a liquid jet in air is an acoustic waveguide having a cutoff frequency inversely proportional to the jet diameter. Ultrasound applied to the jet supply liquid can propagate within the jet when the acoustic frequency is near to or above the cutoff frequency. Modulated radiation pressure is used to stimulate large amplitude deformations and the breakup of the jet into drops.

Hysteresis and mode coupling in capillary bridge oscillations: observations.

We investigate nonlinear axisymmetric oscillations of capillary bridges in a Plateau tank of density-matched liquids. The liquids are selected to have unusually small kinematic viscosities. Large amplitude oscillations are excited by applying oscillating Maxwell stresses.

Active electrostatic control of liquid bridge dynamics and stability.

Stabilization of cylindrical liquid bridges beyond the Rayleigh-Plateau limit has been demonstrated in both Plateau-tank experiments and in short-duration low gravity on NASA KC-135 aircraft using an active electrostatic control method. The method controls the (2,0) capillary mode using an optical modal-amplitude detector and mode-coupled electrostatic feedback stress. The application of mode-coupled stresses to a liquid bridge is also a very useful way to study mode dynamics.

Manipulation of fluid objects with acoustic radiation pressure.

Conditions are summarized for manipulating and stabilizing fluid objects based on the acoustic radiation pressure of standing waves. Examples include (but are not limited to) liquid drops, gas bubbles in liquids, and cylindrical liquid bridges. The emphasis is on situations where the characteristic wavelength of the acoustic field is large in comparison to the relevant dimension of the fluid object.

Observation of the enhanced backscattering of light by the end of a tilted dielectric cylinder owing to the caustic merging transition.

The scattering of light by obliquely illuminated circular dielectric cylinders was previously demonstrated to be enhanced by a merger of Airy caustics at a critical tilt angle. [Appl. Opt.