Diversifying Top-κRoutes with Spatial Constraints

Trip recommendation has become increasingly popular with the rapid growth of check-in data in location-based social networks.Most existing studies focused only on the popularity of trips.In this paper,we consider further the usability of trip recommendation results through spatial diversification.We thereby formulate a new type of queries named spatial diversified top-κroutes(SDκR)query.This type of queries finds k trip routes with the highest popularity,each of which starts at a given starting point,consumes travel time within a given time budget,and passes through points of interest(POIs)of given categories.Any two trip routes returned are diversified to a certain degree defined by the spatial distance between the two routes.We show that the SDkR problem is NP-hard.We propose two precise algorithms to solve the problem.The first algorithm starts with identifying all candidate routes that satisfy the query constraints,and then searches for theκ-route combination with the highest popularity.The second algorithm identifies the candidate routes and builds up the optimalκ-route combination progressively at the same time.Further,we propose an approximate algorithm to obtain even higher query efficiency with precision bounds.We demonstrate the effectiveness and efficiency of the proposed algorithms on real datasets.Our experimental results show that our algorithms find popular routes with diversified POI locations.Our approximate algorithm saves up to 90%of query time compared with the baseline algorithms.

Efficient polysulfides conversion on Mo_(2)CT_(x)MXene for highperformance lithium–sulfur batteries

The severe shuttle effect and sluggish redox kinetics of polysulfides hinder the application of lithium–sulfur batteries.Herein,delaminated Mo_(2)CT_(x) MXene nanosheets are derived by chemical etching approach and further applied as a sulfur host for sulfur spheres(S@Mo_(2)CT_(x)).In the MXene encapsulated architecture,the external MXene nanosheets not only immobilize the soluble polysulfides by strong chemical adsorption but also efficiently catalyze the liquid–liquid conversion and liquid–solid nucleation process of lithium polysulfides.In addition,the S@Mo_(2)CT_(x) electrode delivered fast charge and lithium-ion transport due to the superior electric conductivity and low lithiumion diffusion energy barrier of MXene nanosheets.As a result,the S@Mo_(2)CT_(x) electrode exhibits a high reversible capacity of 918 mAh·g^(-1) at 1.0C with good cycling stability and a high areal capacity of 7.0 mAh·cm^(-2) with sulfur loading of 7.4 mg·cm^(-2) under a lean electrolyte condition.

A Trick to Control the Bleeding in Cardiovascular Surgery

When accidental bleeding happens on the posterior wall of vena cava during the procedure of vena cava cannulation [Figure l a], two pieces of thymus gland tissue around 2 cm × 1 cm were taken as the mattress tips, and these two pieces of tissue were put aside the bottom of vena cava, then use Prolene （Ethicon, Somerville, N J, USA） to pass through the interspace under the posterior wall to make a mattress suture [Figure 1 b and c]. Knot is tied with adequate tension to eliminate any obvious bleeding and to achieve complete hemostasis [Figure l d]. In some cases, additional mattress sutures are needed to stop bleeding.