Usually, the egg will be implanted between 6 to 12 days of egg retrieval. After five days of embryo transfer, the egg reaches blastocyst stage. For accuracy, you need to county the day of retrieval as day 0.
A motor car engine is an Internal Combustion Engine (ICE). Energy is created by burning either diesel or petrol in a combustion chamber. In such an engine, the energy is transferred from the pistons moving up and down at high speeds. This up-down motion is converted to a rotary motion through the crankshaft and axle.
Your engine is kind of like a little planet, or an organism -- a biosphere that must maintain numerous delicate balances just to survive. Your engine uses air and fuel just like your body does, oxidizing the fuel to produce usable energy. But air is a difficult thing to control; it changes in density by atmospheric pressure and heat, and it speeds up or slows down according to the shape of the channels it flows through.