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.
Allotropes are different forms of the same element. Different bonding arrangements between atoms result in different structures with different chemical and physical properties. Allotropes occur only with certain elements, in Groups 13 through 16 in the Periodic Table.This distribution of allotropic elements is illustrated in Figure 1.ifferent bonding arrangements between atoms result in different structures with different chemical and physical properties. Allotropes occur only with certain elements, in Groups 13 through 16 in the Periodic Table. This distribution of allotropic elements is illustrated in Figure 1.