No description available.

No description available.

No description available.

No description available.

No description available.

Repairing injured nervous systems requires the ability to regenerate axons and to guide growing axons to their targets. To achieve guidance, mechanistic studies in physiological axon guidance in developing neurons will be critical. It is known that the growth cone, the structure at the leading edge of developing axons, responds to chemical and mechanical cues in the environment to steer the axon to its target, and chemotropic cues have been well characterized. However, the mechanotransduction pathways involved in axon guidance are currently not well understood. Photoacoustics offers a means for mechanical stimulation of neurons that can be used to study axon guidance by mechanotransduction. Compared to other methods, photoacoustics offers a non-genetic, extremely high spatial precision method for neuron stimulation that works by converting pulsed light energy into ultrasound waves by light absorption and subsequent thermal expansion and contraction of the photoacoustic material. In this thesis, photoacoustic stimulation of neuronal growth cones was used to study axon guidance mechanisms. First, a photoacoustic device that was previously developed in this lab was fabricated by applying a photoacoustic composite material coating to the tip of an optical fiber. This device was used for targeting the growth cones of Xenopus laevis primary embryonic neurons in vitro, and subsequent growth patterns were analyzed using optical microscopy with a custom-built quantitative model for measuring growth rates and directional changes. Calcium imaging by Fluo-4 fluorescent dye was used to show successful activation of mechanotransduction pathways. This thesis offers the first evidence that photoacoustic stimulation of growth cones is possible and sets up future research to explore axon guidance by mechanotransduction using photoacoustic stimulation.

<p>With the world of technology constantly advancing, there will always be a need to improve the source of energy providing the power in a number of applications.<br />Supercapacitors, specifically, have become important power components for cell phones, laptops, and, more recently, electric and hybrid vehicles. In order to increase the efficiency ofsupercapacitors, novel structures must be investigated to increase surface area, which is one key to the energy storage mechanism of supercapacitors. By<br />infiltrating the open cells of high porosity nickel foam with sintered filamentary nickel<br />plaque, a unique, high surface area structure with high porosity has been produced. The mechanical properties of the resulting structure are a compromise of the two constituents; nickel foam and nickel plaque. The nickel foam provides ductility, and the nickel plaque provides strength and stiffuess, with a final composite structure that averages a yield strength of 1.87 MPa, a UTS of 2.25 MPa, an elastic Modulus of 515 MPa, and an average percent elongation of 7.6%. As the relative density of the composite increases, the strength and modulus both increase, while the percent elongation decreases. This high surface area, high porosity material could serve as a viable substrate for a thin coating, which would provide the electrical properties of a supercapacitor.</p> / Master of Applied Science (MASc)

No description available.

No description available.

No description available.