광속의 국제 단위로, 1칸델라의 균일한 광원으로부터 단위 입체각당 방출되는 빛의 양.
The SI unit of luminous flux, equal to the amount of light emitted per second in a unit solid angle of one steradian from a uniform source of one candela.
예문:
"The efficiency of a light bulb is measured by how many lumens it produces per watt."
"This high-end projector features a brightness of 5,000 lumens for clear daylight viewing."
혈관이나 내장과 같은 생물체의 관 모양 또는 속이 빈 구조 내부의 중앙 공간.
The central cavity or open space within a tubular or hollow structure of an organism, such as a blood vessel or intestine.
예문:
"Atherosclerosis causes plaque to build up and narrow the lumen of the arteries."
"The nutrients are absorbed through the lining of the intestinal lumen into the bloodstream."
식물 세포 또는 틸라코이드와 같은 세포 소기관 내부의 공간.
The internal space or cavity within a plant cell or a cellular organelle like the thylakoid.
예문:
"During photosynthesis, protons are pumped into the thylakoid lumen to create a gradient."
"In mature wood cells, the lumen is often empty as the living protoplasm has disappeared."