What is the name of the structure that comprises a circular channel located deep in the corneo-scleral junction (limbus)?

The canal of Schlemm is located deep in the corneo-scleral junction. The canal of Schlemm is the channel that drains the aqueous humor from the anterior chamber, along with the trabecular meshwork. The aqueous humor is secreted by the ciliary body then flows to the posterior chamber, then goes out of the pupil to the anterior chamber then will drain in the canal of Schlemm. 

Mass of the molecules diffusing: Heavier molecules move more slowly therefore they diffuse more slowly. The reverse is true for lighter molecules. Temperature Higher temperatures increase the energy and therefore the movement of the molecules, increasing the rate of diffusion.