a c m s i g c o m m ABSTRACTVirtualizing and sharing networked resources have become a growing trend that reshapes the computing and networking architectures. Embedding multiple virtual networks (VNs) on a shared substrate is a challenging problem on cloud computing platforms and large-scale sliceable network testbeds.In this paper we apply the Markov Random Walk (RW) model to rank a network node based on its resource and topological attributes. This novel topology-aware node ranking measure reflects the relative importance of the node. Using node ranking we devise two VN embedding algorithms. The first algorithm maps virtual nodes to substrate nodes according to their ranks, then embeds the virtual links between the mapped nodes by finding shortest paths with unsplittable paths and solving the multi-commodity flow problem with splittable paths. The second algorithm is a backtracking VN embedding algorithm based on breadth-first search, which embeds the virtual nodes and links during the same stage using node ranks. Extensive simulation experiments show that the topology-aware node rank is a better resource measure and the proposed RW-based algorithms increase the long-term average revenue and acceptance ratio compared to the existing embedding algorithms.

during cycling. These problems mainly result from arbitrary diffusion and thus uncontrollable deposition of intermediate lithium polysulfides (LiPSs) on the electrode surface during the solid-liquid-solid phase transfer process. [3][4][5] For enhanced anchoring strength for polar LiPSs, recently, various polar materials which have inherent adsorption ability for LiPSs such as heteroatoms-doping carbon, [6,7] polymer, [8] and metal oxides/ nitrides/sulfides, [9][10][11][12][13][14][15][16][17] have been applied on sulfur electrode. Owing to favorable sulfur-host interaction, the shuttle effect is effectively suppressed and the sulfur electrochemistry is facilitated. However, these materials only suppress the thermodynamic diffusion of LiPSs derived by the concentration gradient between cathode and electrolyte. In fact, the inherently andante reaction kinetics of LiPSs is also responsible for the shuttle effect. Aimed at the issue, recently, Arava and co-workers have first proposed the electrocatalytic approach to enhance the phase transfer kinetics of LiPSs by using catalytic metals such as Au, Pt, and Ni. [18,19] Next, the concept is extended to conductive compounds such as TiN, TiC, and CoS 2 . [20][21][22] However, the interaction of these materials with LiPSs is not very strong to mitigate the thermodynamic diffusion, moreover, the cost and preparation of these materials are high-price and complex. [21,23] Therefore, to pursue low-cost material that takes full account of both thermodynamic and kinetic dissolution of LiPSs is more effective for the practical application of LSBs.Inspired by graphene-related researches, other low-cost 2D layered materials especially transition metal sulfide/selenide (TMS) have attracted much attention in energy storage in the past years. [24] Owing to the polar feature, 2D TMS is thought to have strong bonding ability for LiPSs. [25][26][27] Moreover, according to a series of reports, the layer thickness of 2D TMS is readily regulated and various 3D structures with high surface area are easily obtained. [24] This provides abundant chemical adsorption sites to decrease the thermodynamic diffusion of LiPSs. In fact, 2D TMS have already showed the catalysis effect on solar cells, photocatalysis, and hydrogen evolution process. [28,29] This is The intrinsic polysulfides shuttle, resulting from not only concentrationgradient diffusion but also slow conversion kinetics of polysulfides, bears the primary responsibility for the poor capacity and cycle stability of lithiumsulfur batteries (LSBs). Here, it is first presented that enriched edge sites derived from vertical standing and ultrathin 2D layered metal selenides (2DLMS) can simultaneously achieve the thermodynamic and kinetic regulation for polysulfides diffusion, which is systematically elucidated through theoretical calculation, electrochemical characterization, and spectroscopic/microscopic analysis. When employed to fabricate compact coating layer of separator, an ultrahigh capacity of 1338.7 mA h g −1 is delivered after 100 cy...

The synergistic design of cathode region was conducted to minimize the shuttle effect of polysulfides and decrease the loading of inactive components in order to acquire high-energy-density lithium-sulfur (Li-S) batteries. The well-designed cathode region presented two special characteristics: one was the intertwined nanofibers interlayer based on ultrafine TiO nanocrystal uniformly embedded within N-doping porous carbon; the other was the lightweight and three-dimensional current collector of fibrous cellulose paper coated by reduced graphene oxide. In consequence, the decent reversible capacity of 874.8 mA h g was acquired at 0.1 C with a capacity retention of 91.83% after 100 cycles. Besides, the satisfactory capacity of 670 mA h g was delivered after 300 cycles at 1 C with the small decay rate of only 0.08%. Because of higher capacity and lower loading of inactive component in cathode region, the energy density of cell increased more than five times compared with unmodified cell. Moreover, to further enhance the energy density, the high-sulfur-loading electrode was fabricated. A good areal capacity of 4.27 mA h cm was retained for the cell with the active material of 4 mg cm and the cycle stability was also well-maintained. In addition, due to the flexibility of interlayer and current collector, Li-S full cell (in pouch cell format) was easily curved. Therefore, the synergistic design for cathode region, which combines the flexible and mass-produced interlayer and current collector together, provides an effective access to Li-S batteries with high energy density and flexibility for practical application.

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Rationale:In this report, a combination of socket-shield technique (SST) and platelet-rich fibrin (PRF) technique was used for immediate implant placement on a fractured central incisor. During the follow-up visit, cone beam computed tomography (CBCT) and clinical observation were used to evaluate the preservation outcome of peri-implant bone and gingiva.Patient concerns:The patient was a 28-year-old healthy female patient who desired her fractured 21 to be replaced with an implant-supported single crown; the fractured 21 comprised a post-core crown with insufficient residual bone at the labial site.Diagnosis:The root of 21 exhibited a complex root fracture; the labial portion of the alveolar ridge was thin (<1 mm) and partial ankylosis of the residual root was observed.Interventions:Modified SST was applied to the labial portion of the residual root. The implant was placed immediately at the lingual site of the retained socket-shield root fragment; PRF was the placed in the gap between the root fragment and the implant. Final prosthodontic treatment was performed at 24 weeks after implant placement.Outcomes:Clinical examination and CBCT scanning at various follow-up visits time showed that the periodontal tissue was well- preserved. At 6 months after surgery, the average horizontal and vertical peri-implant bone resorption was 0.4 mm; a follow-up visit at 18 months post-loading indicated that peri-implant tissue was well preserved by the shield-technique and no significant peri-implant tissue resorption was displayed.Lesson Subsections:In cases of anterior teeth with intact but insufficient residual alveolar ridge, the SST with PRF may be effective for preservation and maintenance of stable peri-implant tissue.