Herein we report the synthesis, X-ray structure determination, and conformational analysis of a novel class of heteroatom-modified peptidomimetics, which we shall call "oxyazapeptides". Substituting the typical native N-C(α) bond with an O-N(α) bond creates a completely new, previously unknown family of peptidomimetics, which are hydrolytically stable and display very interesting conformational behavior. Force field calculations revealed that the barrier to rotation around the O-N(α) bond in oxyazapeptides is five times lower than that around the N-N(α) bond in azapeptides. Also, conformational analysis supported by X-ray suggests that the oxyaza moiety can effectively induce β-turns, which can make the newly discovered oxyazapeptide scaffold a useful tool for drug discovery and for design of biologics.

Purpose Airline scheduling is an extremely complex process. Moreover, disruption in a single flight may damage the entire schedule tremendously. Using an efficient recovery scheduling strategy is vital for a commercial airline. The purpose of this paper is to present an integrated aircraft and crew recovery plans to reduce delay and prevent delay propagation on airline schedule with the minimum cost. Design/methodology/approach A mixed-integer linear programming model is proposed to formulate an integrated aircraft and crew recovery problem. The main contribution of the model is that recovery model is formulated based on individual flight legs instead of strings. This leads to a more accurate schedule and better solution. Also, some important issues such as crew swapping, reassignment of aircraft to other flights as well as ground and sit time requirements are considered in the model. Benders’ decomposition approach is used to solve the proposed model. Findings The model performance is also tested by a case including 227 flights, 64 crew, 56 aircraft and 40 different airports from American Airlines data for a 24-h horizon. The solution achieved the minimum cost value in 35 min. The results show that the model has a great performance to recover the entire schedule when disruption happens for random flights and propagation delay is successfully limited. Originality/value The authors confirm that this is an original paper and has not been published or under consideration in any other journal.

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Oxyazapeptides: Synthesis, Structure Determination, and Conformation Analysis. -Substituting the typical native N-C α bond with an O-N α bond, completely new, previously unknown peptidomimetics are created, which are hydrolytically stable and display very interesting conformational behavior. Force field calculations reveal that the barrier to rotation around the O-N α bond is five times lower than that around the N-N α bond in azapeptides. It is also shown by conformational analysis that the oxyaza moiety can effectively induce β-turns, which can make the newly discovered oxyazapeptide scaffold a useful tool for drug discovery and to design biologics. -(BISWAS, S.; ABO-DYA, N. E.; OLIFERENKO, A.; KHIABANI, A.; STEEL, P. J.; ALAMRY, K. A.; KATRITZKY*, A. R.; J. Org. Chem. 78 (2013) 17, 8502-8509, http://dx.doi.org/10.1021/jo401234g ; Dep. Chem., Univ. Fla., Gainesville, FL 32611, USA; Eng.) -S. Adam 52-209