Differential synthetic aperture radar interferometry (D-InSAR) has been applied in permafrost environments to detect surface deformation caused by freeze-thaw processes in the active layer and ...underlying permafrost. The effectiveness of Sentinel-1 InSAR in monitoring ground surface deformation over continuous permafrost terrain above the treeline has been proven. The heterogeneous landscape and developed vegetation cover increase the difficulty of applying D-InSAR in sub-Arctic discontinuous permafrost terrain. The potential of Sentinel-1 InSAR in such an environment has not been fully explored. In this study, we explore the capabilities and limitations of applying Sentinel-1 time series data for monitoring surface deformation over discontinuous permafrost terrain. The interferometric coherence time series from September 2016 to April 2018 were analyzed over typical landscapes in discontinuous permafrost environments and their thaw subsidence curves are revealed by the small-baseline subset (SBAS) InSAR technique. The seasonal thaw subsidence in the summer of 2017 was in the range of 15–80 mm in the study area. The land cover types with thaw subsidence magnitudes from low to high are exposed land, peatland, lichen–low shrub, lichen-dominated and wetland low vegetation. The difference in displacement pattern between lichen-dominated and wetland-low vegetation-dominated permafrost terrains is especially clear at the end of the thawing stage, in September and October. The differences in thaw subsidence magnitude and pattern reveal the influence of the soil water content in the active layer and permafrost properties on the thaw subsidence patterns. We also compared the Sentinel-1 retrieved cumulative displacement with the X-band TerraSAR-X and L-band ALOS PALSAR results. The difference of retrieved deformation magnitude using the three sensors is amplified when shrubs are more developed. The findings indicate that Sentinel-1 time series with a 6-day or 12-day span work well over discontinuous permafrost terrain above the tree line (i.e., tundra, tundra wetlands and less developed shrub-tundra environments) during the thawed season, but the results and accuracy are not promising over developed shrub-tundra and, especially forest-tundra environments.
•Determination of the applicability of Sentinel-1 in monitoring surface deformation over discontinuous permafrost terrain.•Description of C-band coherence time series over various landscape types in discontinuous permafrost terrain.•Retrieval of thaw subsidence curves over six landcover types in temporal detail.•Comparison of displacements derived from C-band Sentinel-1 data, X-band TerraSAR-X data and L-band ALOS PALSAR data.
This article presents an olfactory-based navigation algorithm for using a mobile robot to locate an odor source in a turbulent flow environment. We analogize the odor source localization as a ...reinforcement learning problem. During the odor plume tracing process, the belief state in a partially observable Markov decision process model is adapted to generate a source probability map that estimates possible odor source locations, and a hidden Markov model is employed to produce a plume distribution map that premises plume propagation areas. Both source and plume estimations are fed to the robot, and a decision-making approach based on fuzzy inference is designed to dynamically fuse information from two maps and to balance the exploitation and exploration of the search. After assigning the fused information to reward functions, a value iteration based path planning algorithm is presented to solve for the optimal action policy. Comparing to other commonly used olfactory-based navigation algorithms, such as moth-inspired and Bayesian inference methods, simulation results show that the proposed method is more intelligent and efficient.
In this work, we explore the competition between magnetic catalysis effect and chiral rotation effect in a general parallel electromagnetic field within the effective Nambu–Jona-Lasinio model. For a ...given electric field E at zero temperature, the mass gap shows three different features with respect to an increasing magnetic field B: increasing monotonically, decreasing after increasing, and decreasing monotonically. By making use of strong magnetic field approximation, we illuminate that this is due to the competition between catalysis effect and chiral rotation effect induced both by the magnetic field, and a critical electric field eEc=86.4 MeV is found beyond which the mass gap will eventually decrease at large B. As only large magnetic field is relevant for the derivation, the critical electric field does not depend on the temperature T or chemical potential μ.
Low availability of nitrogen (N) is often a major limiting factor to crop yield in most nutrient-poor soils. Arbuscular mycorrhizal (AM) fungi are beneficial symbionts of most land plants that ...enhance plant nutrient uptake, particularly of phosphate. A growing number of reports point to the substantially increased N accumulation in many mycorrhizal plants; however, the contribution of AM symbiosis to plant N nutrition and the mechanisms underlying the AM-mediated N acquisition are still in the early stages of being understood. Here, we report that inoculation with AM fungus Rhizophagus irregularis remarkably promoted rice (Oryza sativa) growth and N acquisition, and about 42% of the overall N acquired by rice roots could be delivered via the symbiotic route under N-NO₃⁻ supply condition. Mycorrhizal colonization strongly induced expression of the putative nitrate transporter gene OsNPF4.5 in rice roots, and its orthologs ZmNPF4.5 in Zea mays and SbNPF4.5 in Sorghum bicolor. OsNPF4.5 is exclusively expressed in the cells containing arbuscules and displayed a low-affinity NO₃⁻ transport activity when expressed in Xenopus laevis oocytes. Moreover, knockout of OsNPF4.5 resulted in a 45% decrease in symbiotic N uptake and a significant reduction in arbuscule incidence when NO₃⁻ was supplied as an N source. Based on our results, we propose that the NPF4.5 plays a key role in mycorrhizal NO₃⁻ acquisition, a symbiotic N uptake route that might be highly conserved in gramineous species.
We investigate the influence of rotation on the dynamical chiral symmetry breaking in strongly interacting matter. We develop a self-consistent Bogoliubov-de Gennes-like theoretical framework to ...study the inhomogeneous chiral condensate and the possible chiral vortex state in rotating finite-size matter in four-fermion interacting theories. We show that for sufficiently rapid rotation in 2+1 dimensions, the ground state can be a chiral vortex state, a type of topological defect in analogy to superfluids and superconductors. The vortex state exhibits pion condensation, providing a new mechanism to realize pseudoscalar condensation in strongly interacting matter.
In this study, methacryloxyhexyl triphenylphosphonium bromide (Br-MHP), a quaternary phosphonium salt monomer, was synthesized and then poly-acrylate emulsion with various Br-MHP contents was ...prepared through seed emulsion polymerization. The chemical structure of Br-MHP and chemical composition of Br-MHP containing poly-acrylate emulsion were characterized by 1H NMR, 13C NMR, LC-MS and FT-IR, respectively. Effects of Br-MHP content on the stability of emulsion polymerization and micro-structure of the latex particles were investigated. The micro-morphology of the polymer film was observed by SEM. The film performances such as hardness, adhesive, water absorption ratio, thermal stability and antibacterial property were studied. The surface element composition of Br-MHP containing poly-acrylate film was characterized by XPS. The results show that Br-MHP monomer and poly-acrylate emulsion with various Br-MHP contents can be successfully prepared. With the increase of Br-MHP content, the emulsion polymerization stability increases while particle size of latex particles decreases. Besides, the prepared emulsions show excellent storage stability and mechanical stability. The prepared Br-MHP containing poly-acrylate films also present excellent film properties. As the content of Br-MHP increases, the water absorption ratio of the co-polymer film increases, while hardness and thermal stability decreases. Moreover, XPS result show that the quaternary phosphonium salt group is enrich on the polymer film surface, therefore, the Br-MHP containing poly-acrylate resin presents 99.99 % antibacterial efficiency against S. aureus and E. coli when Br-MHP content is only 1 wt% and 2 wt%, respectively.
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•An antibacterial quaternary phosphonium salt monomer with unsaturated double bond (Br-MHP) was synthesized and characterized.•Br-MHP was covalently incorporated into the poly-acrylate polymer chain structures by emulsion polymerization.•The prepared Br-MHP containing poly-acrylate emulsion presents excellent stability properties•The Br-MHP containing poly-acrylate emulsion presents excellent and durable antibacterial property.
Directional water self‐transport plays a crucial role in diverse applications such as biosensing and water harvesting. Despite extensive progress, current strategies for directional water ...self‐transport are restricted to a short self‐driving distance, single function, and complicated fabrication methods. Here, a lubricant‐infused heterogeneous superwettability surface (LIHSS) for directional water self‐transport is proposed on polyimide (PI) film through femtosecond laser direct writing and lubricant infusion. By tuning the parameters of the femtosecond laser, the wettability of PI film can be transformed into superhydrophobic or superhydrophilic. After trapping water droplets on the superhydrophilic surface and depositing excess lubricant, the asymmetrical wetting ridge drives water droplets by an attractive capillary force on the LIHSS. Notably, the maximum droplet self‐driving distance can approach ≈3 mm, which is nearly twice as long as the previously reported strategies for direction water self‐transport. Significantly, it is demonstrated that this strategy makes it possible to achieve water self‐transport, anti‐gravity pumping, and chemical microreaction on a tilted LIHSS. This work provides an efficient method to fabricate a promising platform for realizing directional water self‐transport.
Inspired by nature, a strategy for directional water self‐transport is proposed on a lubricant‐infused heterogeneous superwettability surface, which is fabricated via femtosecond laser direct writing and lubricant infusion. The water droplet on the sample surface can be transported to the trapped droplet by an asymmetrical wetting ridge. This work extends the applications of multifunctional slippery surfaces and directional water self‐transport.
This article employs a plate with V-shape ribs inside a tube as turbulator to augment the heat transfer rate. The utilized vortex generators are double-winglets arranged in a V-shape placed on both ...sides of the plate. The proposed system's suggested working fluids are water-based hybrid nanofluids, including Al
O
-Cu/water, Cu-CuO/water, and Cu-TiO
/water. This work involves a numerical evaluation of the effects of the type and volume concentration of the examined hybrid nanofluids on the enhancement of heat transfer. The experimental results are used to validate the numerical model. It is worth mentioning that all the obtained numerical results are compared with the simple tube, without any turbulator (vortex generator) and in the presence of water instead of the hybrid nanofluids. Based on the numerical results, it can be concluded that all employed hybrid nanofluids showed improved thermal performance compared to pure water. Furthermore, the differences between the models are more substantial for higher Reynolds numbers than for lower Reynolds numbers. In Re = 30,000, the Cu-TiO
/water exhibits the lowest thermal performance improvement (augmentation of about 0.3%), while the Cu-CuO/water at Re = 50,000 exhibits the largest thermal performance improvement (augmentation of approximately 5.7%), in the case of ∅
= ∅
= 0.5%. For ∅
= ∅
= 1%, the Cu-TiO
/water at Re = 30,000 has the lowest thermal performance improvement (augmentation of around 1.1%), while the Cu-CuO/water at Re = 50,000 has the most thermal performance improvement (augmentation of roughly 8.7%). According to the augmentation of around 2.8% at Re = 30,000 for Cu-TiO
/water and approximately 10.8% at Re = 50,000 for Cu-CuO/water, the thermal performance increase in the scenario of ∅
= ∅
= 1.5% is the lowest. In Conclusion, the Cu-CuO/water hybrid nanofluid with a volume concentration of ∅
= ∅
= 1.5% has the greatest thermal performance value of all the hybrid nanofluids studied.
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