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An increasing number of location-based service providers are taking the advantage of cloud computing by outsourcing their Point of Interest (POI) datasets and query services to third-party cloud service providers (CSPs), which answer various location-based queries from users on their behalf. A critical security challenge is to ensure the integrity and completeness of any query result returned by CSPs. As an important type of queries, a location-based skyline query (LBSQ) asks for the POIs not dominated by any other POI with respect to a given query position, i.e., no POI is both closer to the query position and more preferable with respect to a given numeric attribute. While there have been several recent attempts on authenticating outsourced LBSQ, none of them support the shortest path distance that is preferable to the Euclidian distance in metropolitan areas. In this paper, we tackle this open challenge by introducing AuthSkySP, a novel scheme for authenticating outsourced LBSQ under the shortest path distance, which allows the user to verify the integrity and completeness of any LBSQ result returned by an untrusted CSP. We confirm the effectiveness and efficiency of our proposed solution via detailed experimental studies using both real and synthetic datasets. 

The first phthalocyanine-manganese–oxo intermediate was successfully generated by visible-light photolysis of chlorate or nitrite manganese( iii ) precursors, and its reactivity towards organic substrates was kinetically probed and compared with other related porphyrin-metal–oxo intermediates. 

Bis‐carbonylimidazolide (BCI) functionalization enables an efficient synthetic strategy to generate high molecular weight segmented nonisocyanate polyurethanes (NIPUs). Melt phase polymerization of ED‐2003 Jeffamine_,4,4′‐methylenebis(cyclohexylamine), and a BCI monomer that mimics a 1,4‐butanediol chain extender enables polyether NIPUs that contain varying concentrations of hard segments ranging from 40 to 80 wt. %. Dynamic mechanical analysis and differential scanning calorimetry reveal thermal transitions for soft, hard, and mixed phases. Hard segment incorporations between 40 and 60 wt. % display up to three distinct phases pertaining to the poly(ethylene glycol) (PEG) soft segmentT_g, melting transition, and hard segmentT_g, while higher hard segment concentrations prohibit soft segment crystallization, presumably due to restricted molecular mobility from the hard segment. Atomic force microscopy allows for visualization and size determination of nanophase‐separated regimes, revealing a nanoscale rod‐like assembly of HS. Small‐angle X‐ray scattering confirms nanophase separation within the NIPU, characterizing both nanoscale amorphous domains and varying degrees of crystallinity. These NIPUs, which are synthesized with BCI monomers, display expected phase separation that is comparable to isocyanate‐derived analogues. This work demonstrates nanophase separation in BCI‐derived NIPUs and the feasibility of this nonisocyanate synthetic pathway for the preparation of segmented PU copolymers.

 

Organic chemical structures can be encoded as a simple musical phrase.