Ankylosing spondylitis. Ankylosing spondylitis (AS) is a type of arthritis in which there is long term inflammation of the joints of the spine. Typically the joints where the spine joins the pelvis are also affected. Occasionally other joints such as the shoulders or hips are involved. Eye and bowel problems may also occur.
The allotropes of carbon. Three forms (or 'allotropes') of pure carbon are diamond, graphite and buckminster fullerene (or 'buckyballs'). In all three allotropes the carbon atoms are joined by strong covalent bonds but in such different arrangements that the properties of the allotropes are very different.he allotropes of carbon. Three forms (or 'allotropes') of pure carbon are diamond, graphite and buckminster fullerene (or 'buckyballs'). In all three allotropes the carbon atoms are joined by strong covalent bonds but in such different arrangements that the properties of the allotropes are very different.
Carbon has two  naturally occurring pure forms (allotropes), which are graphite and  diamond.  Graphite is a silver  grey powder which consists of planes of carbon atoms a â¦ rranged in  interlocking hexagons. There are two kinds of bonds within the  sheets, covalent and delocalised.harcoal-a form of non-crystalline carbon   Graphite-crystalline carbon-known as 'pencil llead' (although there is no lead in it!). In graphit, the atoms are joined t â¦ ogether in flat sheets.   Diamond-crystalline carbon with the carbon atoms arranged differently from graphite-in a huge 3d matrix.