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In this study, the oxygen reduction activity of PrBaCo2O5+δ (PBC) double perovskite is remarkably enhanced by rationally tuning the calcination temperatures of the cathode precursor for solid oxide fuel cells (SOFCs). Effects of the calcination temperatures on the phase structure, microstructure, surface area and oxygen reduction reaction (ORR) activity of PBC cathode is systematically investigated. The cathode with optimized calcination temperature (900 °C, PBC-900) shows excellent activity and stability for ORR at 600 °C in terms of area specific resistances (ASRs). A distinctive low ASR of 0.068 Ω cm2 is obtained at 600 °C for PBC-900, which is 92.6%, 34.6% and 15.0% lower than PBC-800, PBC-1000 and PBC-1100, respectively. After operating for 250 h in air at 600 °C, the ASR value of PBC-900 is not significantly reduced. Furthermore, a single cell with PBC-900 cathode delivers attractive peak power density of 1.60 W cm−2 at 600 °C. The present study suggests that the ORR activity of PBC cathode can be greatly boosted by rationally tailoring the calcination temperatures, which may bring new avenue for the design of highly active cathodes for SOFCs.

In the petrochemical industry, multiphase flow, including oil–water two-phase stratified laminar flow, is more common and can be easily obtained through mathematical analysis. However, there is limited mathematical analytical model for the simulation of oil–water flow under turbulent flow. This paper introduces a two-dimensional (2D) numerical simulation method to investigate the pressure gradient, flow field, and oil–water interface height of a pipeline cross-section of horizontal tube in an oil–water stratified smooth flow. Three Reynolds average N–S equation models (k−ε, k−ω, SST k−ω) are involved to simulate oil–water stratified smooth flow according to the finite volume method. The pressure gradient and oil–water interface height can be computed according to the given volume flow rate using the iteration method. The predicted result of oil–water interface height and velocity profile by the model fit well with several published experimental data, except that there is a large error in pressure gradient. The SST k−ω turbulence model appears higher accuracy for simulating oil–water two-phase stratified flow in a horizontal pipe.

The anti-rutting and anti-cracking performance of asphalt mixtures are a pair of contradictions that are difficult to coordinate. In order to ensure the rutting resistance of asphalt mixture to meet the requirements of the specification, while improving its deformation capacity and crack resistance. Based on the mortar performance, the Anti-rutting and High Ductility Asphalt Mixture with excellent anti-rutting performance and deformation performance was designed in this paper. With the filler-asphalt ratio as the control index, SBS modified asphalt and SHV modified asphalt was selected to design five asphalt mortars with different filler-asphalt ratios of 0, 0.5, 1.0, 1.5, 2.0. Variation laws of mortar technical indicators were investigated by rotational viscosity test, cone penetration test, and BBR test. Asphalt mixtures were prepared and a rutting test and small beam bending test were carried out to ensure the consistency of the mixture skeleton state by grouting molding. The influence of the mortar performance index on the road performance of the mixture was evaluated by conducting correlation analysis, and then an anti-rutting and high-ductility asphalt mixture was proposed based on mortar performance. The obtained results showed that the technical indicators of asphalt mortar had a good correlation with the filler-asphalt ratio, and the developed regression model could be used to determine the correlation and design of the mortars. The technical performance index of mortar was found to be directly correlated with the road performance index of the mixture. The developed anti-rutting and high-ductility asphalt mixture not only had good anti-rutting performance but also had good deformation capacity and cracking resistance. Its anti-rutting performance could meet the specification requirements, and the maximum flexural strain could reach 7161 μe. The performance of asphalt mortar determines the road performance of the mixture. The rutting resistance and cracking resistance of the mixture could be coordinated by designing asphalt mortar to improve its comprehensive road performance. To guarantee that the dynamic stability of the mixture met the required specifications and the deformation ability was good, the critical value of each technical index of asphalt mortar was recommended.

This paper investigates the gas phase, including bubbles' and gas pockets' migration and evolution in gas-liquid flow in the pipelines, where the safe operation is severely influenced by the gas accumulations. To investigate the formation, as well as location and amount of these gas accumulations, a new transient model applied with the Population Balance Model (PBM), gas pockets capturing and tracking model are proposed, which are discretized and calculated in the collocated multi-grid with Eulerian-Lagrangian coupling scheme. The flow field of the pipeline is modeled with the Eulerian scheme, while the bubbles' migration, gas pockets' capturing and tracking can be modeled in the Lagrangian mesh. To couple the description of bubble-dimension and that of pipe-dimension, the Rayleith-Plesset equation and the Smooth Particle Hydrodynamics (SPH) are applied, thus, the changeable characteristics of bubbles along the pipes can be described. Based on that, the bubbles' transition to the gas pocket under specific conditions can be predicted. And the subsequent capturing and tracking process will work with the help of the collocated multi-grid, which provides the accurate and parallel calculation. The relative parameters are extracted from the published experimental data, and the simulation results are in good agreement with the measured results. Meanwhile, the case studies show the model has the prediction ability of the gas phase's migration and evolution, as well as the formation and location of gas accumulations in the pipeline.

With oil and gas exploitation developing towards deep-water fields, the extreme, low-temperature, and high-pressure environments are ideal for hydrate formation in subsea pipelines. Hydrate formation, growth, aggregation, and deposition in the flowlines substantially increase the hydrate blockage risk, necessitating the assessment and clarification of this process. This work employed computational fluid dynamics (CFD) and the discrete element method (DEM) to perform several numerical simulations using Fluent and EDEM to study the hydrate blockage process caused by aggregation and deposition. A three-dimensional model of a solid-liquid pipeline containing hydrate particles was established, which considered the cohesion force between the hydrate particles and the adhesion force between the hydrate particles and pipe wall. Two simulation strategies were implemented. The first simulated the hydrate blockage process using a throttling element, which assumed hydrate depositions on the pipeline wall. The second studied the impact of the collision between upstream and downstream hydrate aggregates. The critical hydrate blockage state was roughly defined based on the hydrate volume fraction and pressure drop changes during the hydrate aggregate collision process. These results represented the initial work for simulating the hydrate blockage process via combined CFD-DEM by considering the bidirectional interaction between the continuous water phase and discrete hydrate particles. These preliminary findings provided theoretical support for studying the hydrate blockage mechanism to solve the hydrate flow assurance issue in the subsea pipelines.

This paper investigated the bubble migration and evolution during gas-liquid flow in oil-pipelines. Multi-scale bubbles migrated in the pipe while interacting with each other, causing coalescence and disintegration. The bubbles collided and coalesced, forming a new air pocket in the downward inclined pipe that blocked the transportation of both the gas and liquid phases. Consequently, the buoyance weakened the migration ability of the bubbles, which is known as re-coalescence. To investigate, a new transient model applied with the population balance model (PBM), and Eulerian-Lagrangian coupling scheme is proposed. The complex flow field was modeled using the Eulerian scheme, while the migration of the bubbles was designed in the Lagrangian mesh. Furthermore, the PBM was employed to describe the multi-scale bubble interaction and migration. Smooth particle hydrodynamics were applied to connect the bubble-dimension and pipe-dimension descriptions. Therefore, the bubble fraction could be described to predict the re-coalescence of air pockets. The required unknown model parameters were extracted from the published experimental data, while the simulation results corresponded well with the measured results. During the simulation, the effect of the liquid Froude number and pipe inclination on the size distribution of the multi-scale bubbles were investigated. The results indicated that an increase in the pipe inclination and liquid Froude number improved the bubble migration capacity, leading to a broader distribution of bubbles of all sizes.

Precise pulmonary nodule segmentation from computed tomography (CT) images can contribute a lot for both clinical and research purposes while the variability of pulmonary nodules can make it difficult to perform an accurate and robust segmentation. We propose an encoder-decoder architecture which takes great advantages from convolutional neural networks and attains state-of-the-art results on the public LIDC-IDRI dataset. Our proposed method achieves an average Dice-coefficient score of 90.56% and an average surface distance of 0.13 millimeters on a five-fold cross-validation, which surpasses all the present pulmonary nodule segmentation methods on the LIDC-IDRI dataset. Besides, our method is extremely time-efficient with an average time of less than 20 milliseconds segmenting a single nodule using a modern GPU.

The strength and shape of aggregates significantly affect the internal skeleton structure (ISS) of the asphalt mixtures, which affects the service life of asphalt pavement. ISS is a critical factor that decides the load transfer path in the asphalt mixture. To improve the performance of the asphalt mixture, three aggregates Granite, Diabase, and Limestone with different strengths and shapes were used. Two-dimensional image processing was used to acquire the ISS including contact properties, distribution and orientation of aggregates. Marshall, wheel tracking and three-point bending beam tests were carried out to evaluate the relationship between skeleton indexes with mechanical properties. Results indicated that the coarse aggregate voids filling method could obtain mineral gradations with the same volume combinations for the three aggregates. The crushing value, loss-angles value, roundness, and flakiness index have an excellent relationship with contact characteristics, showing that strength and shape significantly affect the ISS of the asphalt mixture. The results of Marshall, rutting, and bending stiffness modulus are consistent with the internal structural index, proving that low-temperature and high-temperature performance of asphalt mixture are directly affected by aggregate contact properties. There is a weak linear relationship of strength parameters with mechanical properties because Diabase is three times stronger than Granite but has a lower performance demonstrating that the strength of aggregate has a minimal effect on the performance and stability of the asphalt mixture. The results obtained in this study could be used to improve the utilization efficiency of aggregate.

Dual-ion (oxygen ion and proton) conducting electrolyte BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) is one of the most commonly used electrolyte materials for proton conducting fuel cells (PCFCs). Here, we improve conducting property and performance of BZCYYb electrolyte through simply introducing B-site cation deficiency. Dual-ion conductivities for Ba(Zr0.1Ce0.7Y0.1Yb0.1)0.95O3-δ (BZCYYb-0.95) electrolyte are improved to a large extent as 2.5 times protonic conductivity (4.6 × 10−2 S cm−1 at 700 °C) and 6.3 times oxygen ionic conductivity (1.2 × 10−2 S cm−1 at 900 °C) compared to BZCYYb electrolyte. Low-temperature (1350 °C) sinterability of BZCYYb-0.95 is achieved for the higher concentration of defect compared to the original material (BZCYYb, 1500 °C). Meanwhile, a cell with the BZCYYb-0.95 electrolyte illustrates prominent power density of 794 mW cm−2 at 650 °C, superior to the cell with BZCYYb (643 mW cm−2) at the same condition. The collaborative diffusions of dual-ion via two different conducting mechanisms enhance the cell performance with BZCYYb-0.95 electrolyte. The cell voltage and power density actually have no observable performance degradation during the course of the 300-h test. Therefore, it indicates the dual-ion diffusions of BZCYYb-0.95 electrolyte as the promising future for practical application.

SummaryAnthropogenic conversion of natural wetlands into artificial wetland habitats has produced complex wetland landscapes worldwide. In this study we investigated the responses of migratory and wintering waterbirds to five artificial wetland habitats (aquaculture ponds, paddyfields, irrigation canals, open water reservoirs and saltpans) within a novel natural-artificial wetland landscape, Yellow River Delta (YRD), eastern China from October 2007 to May 2008. The results showed that almost all bird community indicators in the YRD natural wetlands were higher than those in adjacent artificial wetlands. Across the landscape, natural wetlands remained most important for all waterbird guilds, and more than 90% of waterbird populations were dependent on these habitats. Artificial wetlands mainly provided a secondary role, supporting about 70% of waterbird species (including six species that reached 1% of their global or biogeographical flyway populations), but with distinctive functional capacity for specific waterbird guilds in different artificial wetlands. The conservation value of artificial wetlands is often ephemeral, mainly during autumn, for specific migratory waterbirds and complements that of remaining areas of natural wetlands. Therefore, the utilisation patterns of artificial wetlands are highly temporal and the majority of species are dependent on areas of natural wetland. A comprehensive study of the inter-seasonal and inter-annual variations in these different habitats and dependence by the various guilds in the YRD is required to enable the true value of these habitats to be understood. We suggest that the conservation of artificial wetlands should not be at the expense of natural wetlands, which should remain the priority for wetland landscape management. Management to maintain the existing artificial wetlands for migrating and wintering water birds should target habitat features that are absent or limited in natural wetlands thus increasing the carrying capacity of the YRD landscape.

Habitat restoration can help mitigate the extensive loss and degradation of estuarine and coastal wetlands that have consequently eroded the integrity of many migratory flyways and wintering habitat for waterbird populations. Assessing the impact of restoration strategies however relies on empirical data on waterbird community distribution patterns across natural and restored wetland components. We conducted habitat and waterbird surveys across six natural and restored wetland regions in the Yellow River Delta Nature Reserve (YRDNR), eastern China, between 2007 and 2009. We recorded 93 waterbird species, including populations of 21 global conservation importance species. Community composition was stratified into distinctive clusters with compositional structure changing across these natural, modified and restored wetland components. NMDS ordination revealed that waterbird communities in restored wetlands were significantly different from those in natural and modified wetland components. Community distribution patterns were strongly influenced by environmental gradients (most noticeably salinity), water-level regulation, vegetation composition and differences in protected status. We found marked temporal patterns in waterbird community composition, which may be predictable for the different wetland components across the YRDNR landscape. Our study highlights the conservation benefits of restoring smaller wetland components in improving the ecological integrity of the wider wetland landscape mosaic for waterbird populations. A more coherent and intensive landscape management of water-level regulation and restoration of salinity gradients will be fundamental for wetland and waterbird conservation throughout the YRDNR.

Despite abundant research that has been carried out on the potential health benefits of pu-erh tea, no consensus till now, has been reached on which constituent is mainly responsible for its bioactivity. In this work, the aqueous extract (AE) and its fraction enriched with active constituents were prepared from pu-erh tea, and their bioactivities were investigated. It was found that tea polyphenols (TP), tea polysaccharides (TPS), caffeine (Caf), protein (Pro), amino acids (AA) were accumulated in several fractions after solvent extraction despite not being separated completely. Meanwhile, 95% ethanol precipitate (EP) and ethyl acetate fraction (EF) possessed remarkable antioxidant activity and potent inhibitory effects against α-glycosidase in vitro. Furthermore, all the extracts (50 mg/kg BW) showed a significant (p0.05) effect on postprandial hyperglycemia in diabetic mice as compared with a model group, and the suppression of EP was not significantly (p0.05) different from that of acarbose at the same dosage (50 mg/kg BW), which indicate that these fractions could be developed as potential anti-diabetic agents.