twenty percent by mass of this material. And, then just to visually see the gradients, what I've done for this demonstration is added a blue dye that will let us visually see it because otherwise everything looks transparent as we fill our scaffold test system. This is our mold which is cut from pieces of Teflon and a glass slide. Here is a piece of Teflon 3 millimeters in thickness and then cut this into dimensions of six centimeters by six centimeters and we build a little hole at the ...