Here, a mild and general oxidative radical relay carbocyclization reaction with 2‐arylbenzoimidazoles and cyclic ethers is reported. This method provides an efficient access to a wide range of structurally diverse benzimidazo[2,1‐a]isoquinoline‐6(5H)‐ones under metal‐free conditions. The wide substrate scope, good functional group tolerance, and scale‐up operation of this method are expected to promote its potential applications in biotechnology and pharmacy.magnified image

Good understanding of power loss in a high frequency synchronous buck converter is important for design optimization of both power MOSFET and circuit itself. Most of the MOSFET power losses are relatively easy to quantify. The exception is the power loss associated with Cdv/dt induced turn on of the low-side MOSFET (synchronous rectifier). This paper characterizes the Cdv/dt induced power loss in two ways. First, detailed device characterization, in-circuit testing, and modeling are used for a comparative loss calculation. This method requires specialized test equipment and is rather complicated and time consuming. A simple method is then introduced to very accurately quantify the Cdv/dt loss. With this method, the impacts of the Cdv/dt power loss on synchronous buck converters at different operation conditions can be readily assessed. The impacts of Cdv/dt induced turn on different applications are addressed.

Many applications call for high step-up dc-dc converters that do not require isolation. Some dc-dc converters can provide high step-up voltage gain, but with the penalty of either an extreme duty ratio or a large amount of circulating energy. DC-DC converters with coupled inductors can provide high voltage gain, but their efficiency is degraded by the losses associated with leakage inductors. Converters with active clamps recycle the leakage energy at the price of increasing topology complexity. A family of high-efficiency, high step-up dc-dc converters with simple topologies is proposed in this paper. The proposed converters, which use diodes and coupled windings instead of active switches to realize functions similar to those of active clamps, perform better than their active-clamp counterparts. High efficiency is achieved because the leakage energy is recycled and the output rectifier reverse-recovery problem is alleviated.

A trans diacyloxylation of indoles is accomplished by employing PhI(OAc)(2) as the oxidant. A broad range of functional groups are well tolerated. Both the electronic properties of the N-protecting groups of indoles and the acidity of the reaction media play important roles in the selectivity of indole acyloxylation reactions.

Against the background of population aging and economic downturn, the sustainability of pension systems has aroused great concern for governments across the world. To better reflect the pressure of pension payments in the changing context, the paper aims to forecast the annual pension gap of the public pension system for urban employees in China. By the use of Cohort-component population projections and stochastic projection models, the distribution of flow-based annual pension gap in the next fifty years are estimated under basic assumptions. The results show that the pension gap continues to exist from 2017 and keeps expanding until 2070 without any policy reform. Sensitivity analyses of demographics and various combinations of policy parameters on the distribution of future pension gaps are displayed. Wider pension coverage with lower policy threshold is more likely to face larger long-term pension gap.