The Internet of Things (IoT) is growing rapidly and brings great convenience to humans. But it also causes some security issues which may have negative impacts on humans. Trust management is an ...effective method to solve these problems by establishing trust relationships among interconnected IoT objects. In this paper, we propose an adaptive trust model based on recommendation filtering algorithm for the IoT systems. The utilization of sliding window and time decay function when calculating direct trust can greatly accelerate the convergence rate of trust evaluation.
We design a recommendation filtering algorithm to effectively filter out bad recommendations and minimize the impact of malicious objects. An adaptive weight is developed to better combine direct trust and recommendation trust into synthesis trust so as to adapt to the dynamically hostile environment. In the simulation experiments, we compare our adaptive trust model with three related models: TBSM, NRB and NTM. The experimental results indicate that our trust model converges fast and the mean absolute error is always less than 0.05 when the proportion of malicious nodes is from 10% to 70%. The comparative experiments further verify the effectiveness of our trust model in terms of accuracy, convergence rate and resistance to trust related attacks.
The Lhasa River is the largest and most important tributary of the Yarlung Tsangpo River on the Tibetan Plateau, China. It is an important source of drinking water and irrigation for the inhabitants ...living in the watershed. Despite the increasing focus on water chemistry, the ecological risk assessment (ERA) caused by heavy metals to aquatic organisms in the Lhasa River has not been performed before. Based on the documented monitoring data for heavy metals, the species sensitivity distributions (SSDs) method was applied in this study. The potential ecological risks induced by eight major heavy metals (including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), lead (Pb), and zinc (Zn)) in the Lhasa River to four typical categories of freshwater organisms, including insects, crustaceans, fish, and mollusks, were assessed in different water periods (e.g., high, normal, and low water-periods). Results suggested that the downstream part of the Lhasa River and the Meldromarchu and Tölungchu tributaries are the principal zones for the high aquatic ecological risks. For most of the monitoring sites, the ecological risks decreased in the following order: high-water period > normal-water period > low-water period. During the high-water period, Cu had the highest ecological risks for all selected species. For the insects, the ecological risks were quite low (< 1%) throughout the year. These results suggested that particular attention should be paid to the contamination of certain heavy metals (e.g., Cu and Cr) in the future water management in the Lhasa River.
Nonmissile intracranial penetrating injury (IPI) in pediatric population is rare. Here, we report the exceedingly rare case of a 5-month-old infant sustained by a metallic clothes fork penetrating ...into his left forehead. The little baby was identified to carry a traumatic hemorrhagic shock, and a multidisciplinary team (MDT) was immediately established response for whole-course evaluation and decision-making. Computed tomography revealed that the clothes fork had impaled into the left frontal bone and brain parenchyma with about 3.2 cm inside the cranial vault. The infant underwent emergency surgery, and the clothes fork was removed jointly by MDT members under general anesthesia in the retrograde direction. His recovery was uneventful and was followed up 2 years without growth and developmental abnormality. As an extremely rare entity with distinct age-related characteristics, a MDT approach is a best choice and effective strategy to manage infant nonmissile IPI, including preoperative management, surgical treatment, and even following rehabilitation.
The effect of induction chemotherapy on oral cancer is controversial owing to inconsistent results. However, the efficacy of induction chemotherapy is closely related to locoregional recurrence, ...distant metastasis, and overall survival after the treatment. A pseudotargeted metabolomics revealed that metabolites involved in glycolysis and amino acid metabolism were inversely regulated in patients with different chemotherapy responses, and most fatty acids, steroids, and antioxidant substances were up-regulated in all patients after the treatment. Among the metabolites, lactic acid, glucose, glutamic acid, aspartic acid, leucine, and glycerol were remarkably associated with induction chemotherapy efficacy. Subsequently, lactic acid, glutamic acid, and aspartic acid were defined as potential biomarkers of the suitability and efficacy of induction chemotherapy. Our results show that 100.0 and 84.37% of patients with different chemotherapy efficacy were correctly identified in the training and test sets, respectively. Moreover, patient suitability for treatment was correctly predicted for 100.0, 81.25, and 100.0% of patients in the training, test, and external validation sets, respectively. In conclusion, metabolites related to glycolysis, redox homeostasis, and anabolic progress were indicative of induction chemotherapy efficacy both pre- and post-chemotherapy and beneficial for outcome evaluation and prediction. These results illustrate the potentials of metabolomics in personalized induction chemotherapy.
This study reports unexpected strong longitudinal structures from Global Navigation Satellite System (GNSS) derived total electron content (TEC) observations in the low-latitude ionosphere over Asia. ...The observations during 2019–2020 show diverse patterns in the zonal difference of regional TEC, even under geomagnetically quiet conditions. The TEC in the northern hemisphere occasionally exhibits drastic zonal gradients. The intense regional gradients in TEC span a longitudinal extent of about 20°. The higher values may appear on the east or the west side. Strong zonal gradients may appear in all seasons, regardless of geomagnetically quiet or active conditions. The 15 December 2019 and 16 March 2020 cases depict an intense zonal differences cluster in the narrow latitudinal band of 16°N to 28°N, spanning a regional scale smaller than the normal longitudinal structures. In contrast, the Global Ionospheric Maps (GIMs) with a longitudinal resolution of 5° show a much flatter zonal picture. Such intense and regional-scale zonal structures in the low-latitude ionosphere call for a high zonal resolution of GIMs in terms of better geographically distributed observations. Notably, no counterpart regional structures are found at the conjugated points in the southern hemisphere during the two cases. Although the physical drivers are not certain, the appearance only in the northern hemisphere possibly excludes the dominant contribution to forming the regional structures from the equatorial electric field.
Abstract Structured catalysts coatings exhibit excellent performance on non‐adiabatic gas–solid process, deriving from their enhanced heat and mass transfer properties. However, the coating catalysts ...prepared by traditional hydrothermal method of zeolite encapsulating noble metal are prone to spalling, especially under conditions of large flow rate and high temperature. Herein, we prepared PtZn clusters encapsulated in silicalite‐1 zeolite coating on stainless steel with high bonding strength by an improved in situ growth method. The optimized catalyst exhibited ultra‐thin, uniform, continuous, and high degree of crosslinking, thereby enhancing mass transfer and thermal stability. In propane dehydrogenation reaction, the optimized PtZn@S‐1‐R showed a high specific activity of 14.7 mol Pt −1 s −1 and a propylene selectivity above 99% at 600°C with a high weight hourly space velocity of 120 h −1 . The metal‐encapsulated zeolite coating catalysts broaden the application avenue for heterogeneous catalysis with great application prospects.
Structured catalysts coatings exhibit excellent performance on non‐adiabatic gas–solid process, deriving from their enhanced heat and mass transfer properties. However, the coating catalysts prepared ...by traditional hydrothermal method of zeolite encapsulating noble metal are prone to spalling, especially under conditions of large flow rate and high temperature. Herein, we prepared PtZn clusters encapsulated in silicalite‐1 zeolite coating on stainless steel with high bonding strength by an improved in situ growth method. The optimized catalyst exhibited ultra‐thin, uniform, continuous, and high degree of crosslinking, thereby enhancing mass transfer and thermal stability. In propane dehydrogenation reaction, the optimized PtZn@S‐1‐R showed a high specific activity of 14.7 molC3H6 molPt−1 s−1 and a propylene selectivity above 99% at 600°C with a high weight hourly space velocity of 120 h−1. The metal‐encapsulated zeolite coating catalysts broaden the application avenue for heterogeneous catalysis with great application prospects.
The Lhasa River basin is the economic and population center of Tibet and has abundant resources. Due to its harsh weather condition, high elevation, and inconvenient accessibility, few studies have ...focused on heavy metal distributions in this region. In the present study, to investigate the dissolved trace metal pollution and its controlling factors, 57 water samples from the Lhasa River and its tributaries were collected during three water flow regimes in 2016. The data on the dissolved fraction revealed that the Lhasa River basin appeared to have no to low pollution levels. However, the Lhasa River water showed alkaline characteristics which may affect the presence of heavy metal elements in a dissolved fraction. The concentration of heavy metal elements in colloidal or particulate matter therefore needs attention. Multivariate analyses were performed to determine the significant relationship between the data and to identify controlling factors for dissolved heavy metals in the study area. The results suggested that Mn, Cd, Cu, and Zn originated from a natural geological background, whereas Pb originated from mining drainage and As was influenced by geothermal flows. The concentration of dissolved heavy metals in the Meldromarchu tributary was greatly affected by the mining drainage water, while that in the Tölungchu tributary was greatly influenced by the geothermal water sources. This paper provides the first comprehensive analysis of dissolved heavy metal pollution characteristics and the controlling factors of pollution during the three different water flow regimes of the Lhasa River basin.
The porosity and pore structure of anode support plays an important role in fuel gas diffusion of protonic ceramic fuel cells (PCFCs). In this study, the PCFC with Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ ...(BZCYYb) anode substrate with finger-like straight pore and reasonable flexural strength was successfully prepared by a one-step phase inversion tape casting, spin coating and co-firing technologies. The peak power density of single cell reaches 0.77 W cm-2 at 700 °C using 3 % H2O humidified hydrogen as the fuel, which is significantly higher than the single cell prepared by typical dry-pressing method. It is found that the improvement is attributed to the optimization of anode mass transfer process with open-straight hole according to the relaxation time distribution (DRT) analysis of polarization resistance. Meanwhile, the single cell prepared by one-step phase inversion tape casting shows no significant degradation after a 100 h stability test at 650 °C or short thermal-cycling test. The results indicate that the fabrication of straight hole via phase inversion tape casting is an effective way to facilitate the transfer of fuel gas and eliminate the concentration polarization loss.
•The PCFC is successfully prepared by one-step phase inversion tape casting and co-firing technology.•The mass transfer of anode is significantly improved compared with dry-pressing approach.•The single cell shows no significant degradation within 100 h test.
The oxygen electrode-supported reversible solid oxide cell (RSOC) has demonstrated distinguishing advantages of fuel flexibility, shorter gas diffusion path and more choices for fuel electrode ...materials. However, there are serious drawbacks including the difficulty of co-firing the oxygen electrode and electrolyte, and the inefficient electrochemical performance. In this study, a (La0.8Sr0.2)0.95MnO3-δ (LSM) supported RSOC with the configuration of La0.6Sr0.4Fe0.9Sc0.1O3-δ (LSFSc)-YSZ/YSZ/CuNi–CeO2-YSZ is fabricated by tape casting, co-sintering and impregnation technologies. The single cell is evaluated at both fuel cell (FC) and electrolysis cell (EC) mode. Significant maximum power density of 436.0 and 377 mW cm−2 is obtained at 750 °C in H2 and CH4 fuel atmospheres, respectively. At electrolysis voltage of 1.3 V and 50% steam content, current density of −0.718, −0.397, −0.198 and −0.081 A cm−2 is obtained at 750, 700, 650 and 600 °C respectively. Much higher electrolysis performance than FC mode is exhibited probably due to the optimized electrodes with increased triple phase boundary (TPB) area and faster gas diffusion (oxygen and steam) and electrochemical reactions for water splitting. Additionally, the short-term stability of single cell in H2 and CH4 are also studied.
•A LSM oxygen-electrode-supported RSOC is fabricated by tape casting, co-sintering and impregnation techniques.•Significant power density of 436.0 and 377 mW/cm−2 is obtained at 750 °C using H2 and CH4 as fuel respectively.•Good electrolysis performance of −0.718 A cm−2 at 1.3 V with 50% H2O is achieved at 750 °C.•Short-term stability of single cell in H2 and CH4 fuel is evaluated at 600 °C.
