5G. Magnetic Materials 5G20. Magnet Domains & Magnetization 5G20.70 Electromagnet 5G50. Temperature and Magnetism 5G30.20 Paramagnetism of Liquid Oxygen 5G50.50 Meissner Effect: Superconducting Disk and Magnet 5G50.50 Superconducting Train on a Mobius Track