1. Thus atactic polystyrene is amorphous but isotactic polystyrene is semi-crystalline.

2. Polyacetadehyde may exist in atactic, syndiotactic and isotactic forms.

3. Polyacetaldehyde may exist in atactic, syndiotactic and isotactic forms.

4. Results showed that head-tail addition and atactic structure were dominant in polyether microstructure.

5. The hard non-elastic atactic copolymer with methyl methacrylate as main component consists of methyl methacrylate and monomer capable of copolymerizing with it.

6. Isotactic diad decreases with the increase of radiation dose . Meanwhile, atactic and syndiotactic diad increases.

7. Those with a random distribution of configuration are termed atactic.

8. Neoplastic cells hae large column, irregular form, lining up in atactic shape.