Detecting compromised accounts caused by phone number recycling on e-commerce platforms: taking Meituan as an example

Phone number recycling(PNR)refers to the event wherein a mobile operator collects a disconnected number and reassigns it to a new owner.It has posed a threat to the reliability of the existing authentication solution for e-commerce platforms.Specifically,a new owner of a reassigned number can access the application account with which the number is associated,and may perform fraudulent activities.Existing solutions that employ a reassigned number database from mobile operators are costly for e-commerce platforms with large-scale users.Thus,alternative solutions that depend on only the information of the applications are imperative.In this work,we study the problem of detecting accounts that have been compromised owing to the reassignment of phone numbers.Our analysis on Meituan's real-world dataset shows that compromised accounts have unique statistical features and temporal patterns.Based on the observations,we propose a novel model called temporal pattern and statistical feature fusion model(TSF)to tackle the problem,which integrates a temporal pattern encoder and a statistical feature encoder to capture behavioral evolutionary interaction and significant operation features.Extensive experiments on the Meituan and IEEE-CIS datasets show that TSF significantly outperforms the baselines,demonstrating its effectiveness in detecting compromised accounts due to reassigned numbers.

Preparation of porous semi-IPN temperature-sensitive hydrogel-supported nZVI and its application in the reduction of nitrophenol

Nanoscale zero-valent iron(n ZVI) particles supported on a porous, semi-interpenetrating(semi-IPN), temperature-sensitive composite hydrogel(PNIPAm-PHEMA). n ZVI@PNIPAmPHEMA, was successfully synthesized and characterized by FT-IR, SEM, EDS, XRD and the weighing method. The loading of nZVI was 0.1548 ± 0.0015 g/g and the particle size was30–100 nm. NZVI was uniformly dispersed on the pore walls inside the PNIPAm-PHEMA.Because of the well-dispersed n ZVI, the highly porous structure, and the synergistic effect of PNIPAm-PHEMA, nZVI@PNIPAm-PHEMA showed excellent reductive activity and wide p H applicability. 95% of 4-NP in 100 m L of 400 mg/L 4-NP solution with initial p H 3.0–9.0 could be completely reduced into 4-AP by about 0.0548 g of fresh supported n ZVI at 18–25 °C under stirring(110 r/min) within 45 min reaction time. A greater than 99% 4-NP degradation ratio was obtained when the initial p H was 5.0–9.0. The reduction of 4-NP by nZVI@PNIPAm-PHEMA was in agreement with the pseudo-first-order kinetics model with Kobsvalues of 0.0885–0.101 min-1.NZVI@PNIPAm-PHEMA was able to be recycled, and about 85% degradation ratio of 4-NP was obtained after its sixth reuse cycle. According to the temperature sensitivity of PNIPAmPHEMA, n ZVI@PNIPAm-PHEMA exhibited very good storage stability, and about 88.9%degradation ratio of 4-NP was obtained after its storage for 30 days. The hybrid reducer was highly efficient for the reduction of 2-NP, 3-NP, 2-chloro-4-nitrophenol and 2-chloro-4-nitrophenol. Our results suggest that PNIPAm-PHEMA could be a good potential carrier, with n ZVI@PNIPAm-PHEMA having potential value in the application of reductive degradation of nitrophenol pollutants.

Positive remediation on sedimentary P by combination of capping with calcium hydroxide and oxidation with perhydrol

The capping is called passive remediation because the sedimentary P was released and then immobilized by the capping materials.However,the release depends on the environmental conditions.Therefore,a hypothesis was proposed that the oxidant was used to accelerate sedimentary P release and the capping material was used to capture those released P.It is positive remediation to reduce sedimentary P amount.The results show that soluble reactive phosphorus(SRP)concentration in the overlying water and pore water increased and then decreased gradually under the combination of sodium percarbonate(SPC)and Ca(OH)_(2),similar as that under the capping with single Ca(OH)_(2).The sedimentary P amount was reduced considerably and P concentration in the capping layer increased obviously after 60 days,compared with the capping with single Ca(OH)_(2).All these indicated that oxidation improved the sedimentary P release and the released P was captured and immobilized by the capping material of Ca(OH)_(2).However,the acceleration of sedimentary P release due to the oxidation is obviously different from the traditional mechanism that the oxic condition in the sediment is favor of the immobilization on sedimentary P.It is attributed to the oxidizability of?OH from SPC.The reduction of mobile-P and the increase of Ca-P under the combined use are observed.This is similar as traditional mechanism of oxic condition.It is sure that positive remediation reduced sedimentary P amount,resulting in the decrease of P release risk in a long time.