Most of previous studies optimize maintenance time window scheduling problem under a given train schedule, leading to a relatively poor quality of maintenance time window schedule, increasing the influence on traffic assignment. In order to reduce the negative effects on maintenance schedule and improve the utilization of railway resources, we consider integrating maintenance time window scheduling and train timetabling. In this way, more reasonable maintenance time window schedule can be obtained. We propose a mixed integer programming model and in particular we focus on the characteristics of the problem, including the speed limits affected by maintenance tasks on a double-track railway line. The benefits of the proposed integrated optimization model are demonstrated by numerical experiments.@en

An aqueous chemoenzymatic cascade reaction combining Pd-catalyzed C-C formation and enzymatic C=C asymmetric hydrogenation (AH) was developed for enantioselective synthesis of tertiary α-aryl cycloketones in good yields and excellent enantioselectivities. The stereopreference of the enzyme in AH of α-aryl cyclohexenones was studied. An enantiocomplementary enzyme was obtained by site-directed mutation.@en