Where does amniotic fluid come from?

How did NASA get their cameras to work in the cold on the moon? How does a cordless electric toothbrush charge itself? What is adult respiratory distress syndrome? Where does the amniotic fluid around a baby come from? Why are Olympic races run anticlockwise? Why is sunscreen advised even on cloudy days? What is more accurate, my speedometer, or the speed recorded by my GPS? And why do my sunglasses make LCD displays look strange? This week Dr Chris takes on more of your science questions...