One remedy for a deficiency of vitamin B12 for the elderly is a regular injection of this important nutrient. The vitamin B12 injection dose depends on factors such as gender and age.
Hydrogen bonds happen in alcohols. As a matter of fact, any molecule that contains a hydrogen atom attached to an atom of nitrogen or oxygen is capable of such a bond. Ethanol is one such alcohol that features hydrogen bonds. Ammonia is an example of hydrogen bonding. In the case of ammonia, however, the hydrogen bond happens to be relatively weak.
Both of these atoms can form a hydrogen bond with oxygen atoms of different water molecules. Every water molecule can be hydrogen bonded with up to three other water molecules (See Fig. 3-7). However, because hydrogen bonds are weaker than covalent bonds, in liquid water they form, break, and reform easily. Thus, the exact number of hydrogen bonds formed per molecule varies.