The TTL output stage is a rather complicated pushâpull circuit known as a totem-pole output (the transistors, diode, and resistor in the right-most slice of this TTL logic gate circuit). It sinks currents better than it sources current.
The theory for spontaneous generation refers to the idea that life can produced from nonliving things. Lazzaro Spallanzani proposed in his experiement that air was necessary for spontaneous generation.
The theory that he was exposed to at the University of Padua was a new theory that was proposed by Nicolaus Copernicus which stated that the Earth and all the other planets revolved around the sun. Also Gaileo's observations with his new telescope made him believe Copernicus's heliocentric theory.