There are two models of protein folding that are currently being confirmed: 1  The diffusion collision model, in which a nucleus is formed, then the secondary structure is formed, and finally these secondary structures are collided together and pack tightly together.
ATT Validity Dates. 1  Each ATT is valid for a period of time specified by the BON/RB (the average length of an ATT is 90 days). 2  Once the BON/RB has declared you eligible to test and you receive your ATT, you must test within the validity dates on the ATT.
1 Call NCLEX Candidate Services if you've lost your ATT or if you have not received your ATT two weeks after registering. 2  The ATT contains the authorization number, candidate identification number and an expiration date. 3  These validity dates cannot be extended for any reason.