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.
There are several known allotropes of oxygen. The most familiar is molecular oxygen (O 2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen.Another is the highly reactive ozone (O 3). Others include: 1  Atomic oxygen (O 1, a free radical).2  Singlet oxygen (O 2 *), either of two metastable states of molecular oxygen.ee also: Dioxygen in biological reactions. The common allotrope of elemental oxygen on Earth, O 2, is generally known as oxygen, but may be called dioxygen or molecular oxygen to distinguish it from the element itself.