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Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
The most common childhood diseases include croup, chickenpox, ear infections, flu, pneumonia, ringworm, respiratory syncytial virus, scabies, head lice, and asthma.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.