Complex sentence: The gray was named after the British physicist Louis Harold Gray, a pioneer in the field of measurement of radium radiation and X-rays and their effects on living tissue, and was adopted as part of International System of Units in 1975.
Split into simpler sentences: The gray was named after British physicist Louis Harold Gray, a pioneer in the field of X-ray and radium radiation measurement, and their effects on living tissue. It was adopted as part of the International System of Units in 1975.