Ammonia-oxidizing archaea (AOA) are some of the most abundant microorganisms in the ocean and play a key role in nitrogen ...

Ocean microbes can use urea when ammonium is scarce. This helps them survive in poor waters and reshapes our view of the nitrogen cycle.

Doctors order a blood urea nitrogen (BUN) test to measure the amount of urea nitrogen in your blood. It helps them see how well your kidneys are working. A BUN test measures how much blood urea ...

Stress, smoking, diet, exercise, and weight can change your menstrual cycle. Irregular periods during puberty can be normal, but see a healthcare provider if they last over two years. Perimenopause ...