History of electrochemistry
In 1789, Franz Aepinus developed a device with the properties of a "condenser" (now known as a capacitor.) The Aepinus condenser was the first capacitor developed after the Leyden jar, and was used to demonstrate conduction and induction. The device was constructed so that the space between two plates could be adjusted, and the glass dielectric separating the two plates could be removed or replaced with other materials.
Bell Labs
In 1947, the transistor, probably the most important invention developed by Bell Laboratories, was invented by John Bardeen, Walter Houser Brattain, and William Bradford Shockley (and who subsequently shared the Nobel Prize in Physics in 1956). In 1947, Richard Hamming invented Hamming codes for error detection and correction. For patent reasons, the result was not published until 1950. In 1948, "A Mathematical Theory of Communication", one of the founding works in information theory, was published by Claude Shannon in the "Bell System Technical Journal". It built in part on earlier work in the field by Bell researchers Harry Nyquist and Ralph Hartley, but it greatly extended these. Bell Labs also introduced a series of increasingly complex calculators through the decade. Shannon was also the founder of modern cryptography with his 1949 paper "Communication Theory of Secrecy Systems".In 1952, William Gardner Pfann revealed the method of zone melting which enabled semiconductor purification and level doping.