Abstract: A circuit board and an electronic device having the circuit board that includes a ceramic sintered body, a through conductor and a metal wiring layer. The ceramic sintered body includes a through hole penetrating from a first main surface to a second main surface thereof. The through conductor is in the through hole and has first and second ends. The metal wiring layer covering the first end and electrically connected to the through conductor. The through conductor includes: a first portion having a hollow cylinder shape, in contact with an inner wall of the through hole and extending from the first end to the second end; and a second portion having a columnar shape and disposed inside the first portion. The second portion has an average grain size of the metal larger than that in the first portion.

Abstract: A method of producing reverse transcriptase, which comprises isolating a fraction containing retrovirus from a tissue culture fluid supernatant of retrovirus producing cells which are able to grow and propagate in vitro, treating said fraction at least once by sucrose density gradient centrifugation to thereby obtain a purified retrovirus, and extracting reverse transcriptase from said purified retrovirus.

Abstract: A system for utilizing audio frequency wiring circuits at drive-in theaters to transmit radio frequency signals to patron automobile radio receivers with increased efficiency and a reduction in radiation of the radio frequency signals. The system employs impedance matching networks, coupling networks and termination networks to enable the audio frequency wiring circuits to operate as transmission lines.

Abstract: A drive-in movie theater audio system provides sound to the patrons over their car radios and connects to each radio through a novel lead-in which couples the car radio antenna to a transmission bus connected to a central broadcast band transmitter. The lead-in employs a pair of elongated wire sections supported parallel to one another to capacitively couple the broadcast band signal to the car antenna.