High-resolution real-space imaging of nanoparticle surfaces is desirable for better understanding of surface composition and morphology, molecular interactions at the surface, and nanoparticle ...chemical functionality in its environment. However, achieving molecular or sub-molecular resolution has proven to be very challenging, due to highly curved nanoparticle surfaces and often insufficient knowledge of the monolayer composition. Here, we demonstrate sub-molecular resolution in scanning tunneling microscopy imaging of thiol monolayer of a 5 nm nanoparticle Ag374 protected by tert-butyl benzene thiol. The experimental data is confirmed by comparisons through a pattern recognition algorithm to simulated topography images from density functional theory using the known total structure of the Ag374 nanocluster. Our work demonstrates a working methodology for investigations of structure and composition of organic monolayers on curved nanoparticle surfaces, which helps designing functionalities for nanoparticle-based applications.
•We present a dynamic model to predict runway WFD with wind effects.•The model is well validated with measured data from a dedicated physical model.•We evaluate the influencing factors’ effects on ...runway drainage and WFD.•We develop an empirical formula to predict runway risk area.
The runway water film depth (WFD) and its drainage have direct impact on hydroplaning risk and, consequently, aircraft operational safety. Understanding its relationship with weather and runway conditions can help manage such risk due to WFD. Thus, this study develops an empirical formula to correlate runway risk area with its influencing factors using a dataset generated by a comprehensive rainfall-runoff dynamic model. The model incorporates a wind speed induced stress and is validated with physical experiment collected data. The simulation and observation showed good agreement, verifying the model's capability to reasonably well simulate the WFD distribution on intricate grooved surfaces at the millimetre level, with the consideration of wind effects. Then, this study performs 456 numerical experiments at the lateral prototype scale considering various rainfall intensity, wind speed, runway deterioration area, and groove depth. The impact of these factors on the peak WFD and the runway risk area is quantitatively analysed. The proposed empirical formula and developed dynamic model enables accurate assessment and prediction of the runway risk area under extreme weather conditions for better management of potential hydroplaning.
Ultrathin superconducting films are the basis of superconductor devices. van der Waals (vdW) NbSe2 with noncentrosymmetry exhibits exotic superconductivity and shows promise in superconductor ...electronic devices. However, the growth of inch-scale NbSe2 films with layer regulation remains a challenge because vdW structural material growth is strongly dependent on the epitaxial guidance of the substrate. Herein, a vdW self-epitaxy strategy is developed to eliminate the substrate driving force in film growth and realize inch-sized NbSe2 film growth with thicknesses from 2.1 to 12.1 nm on arbitrary substrates. The superconducting transition temperature of 5.1 K and superconducting transition width of 0.30 K prove the top homogeneity and quality of superconductivity among all of the synthetic NbSe2 films. Coupled with a large area and substrate compatibility, this work paves the way for developing NbSe2 superconductor electronics.
The sheetlike BiOI/rodlike Bi5O7I photocatalysts were prepared through an in situ crystallization method of BiOI with different pH values under alkaline condition. All the physicochemical properties ...of samples were tested by chemical characterization analysis. The results showed that the different preparation conditions of BiOI photocatalysts presented different microstructures under different pH values. When the value of pH increased from 8 to 14, the morphology of the sample gradually changed from sheetlike to rodlike. It was found that the formation of heterostructures can be constructed between sheetlike BiOI and rodlike Bi5O7I photocatalysts. Also, the photocatalytic ability of photocatalysts was tested via removing Hg0 under visible-light irradiation. All heterostructure photocatalysts exhibited outstandingly enhanced performance under the light-emitting diode (LED) lamp irradiation without any sacrificial agents in the environment. It was demonstrated that sample Bi-11.0 showed high activity in removing mercury, and the removal efficiency reached up to 63%, which improved the mercury-removal efficiency about 66.7% compared with Bi-8.0. The prominent photocatalytic performance was attributed to the internal electric field of different morphologies and the heterojunction between sheetlike BiOI and rodlike Bi5O7I, which impeded the recombination of photoelectron and hole (e––h+) pairs. This Article provides a new prospect for designing efficient photocatalysts to deal with heavy metal pollution and other environmental problems.
Flexible pressure sensors can be used in human–computer interaction and wearable electronic devices, but one main challenge is to fabricate capacitive sensors with a wide pressure range and high ...sensitivity. Here, we designed a capacitive pressure sensor based on a bionic cheetah leg microstructure, validated the benefits of the bionic microstructure design, and optimized the structural feature parameters using 3D printing technology. The pressure sensor inspired by the cheetah leg shape has a high sensitivity (0.75 kPa–1), a wide linear sensing range (0–280 kPa), a fast response time of roughly 80 ms, and outstanding durability (24,000 cycles). Furthermore, the sensor can recognize a finger-operated mouse, monitor human motion, and transmit Morse code information. This work demonstrates that bionic capacitive pressure sensors hold considerable promise for use in wearable devices.
•Guidance of intensity on depth estimation is emphasized for its sharp edge•Multi-scale superpixels and fast windows are used to solve large but sparse noisy data•Cost function is modified to balance ...between smoothness and preserving details•Results show accurate depth estimation of long-rang targets in photon-starved regime
Long-range lidar systems usually record large but extremely sparse data cubes. It is a great challenge to estimate accurate depth images of the photon-starved regime with fewer memory requirements and lower computational complexity. An intensity-guided method is introduced to estimate the depth image by using temporal-spatial correlation of the reflected signals. Multi-scale superpixels and fast time-domain windows are established in the preprocessing step, leading to smaller data cubes with reduced empty and noisy pixels. To strike a balance between smoothness and preserving sharp edges, the fast-converging alternating direction method of multipliers (ADMM) is used in the modified cost function to estimate depth images. Experimental results show that the proposed method yields better depth estimates than other state-of-the-art methods, especially for long-rang targets of field experiments with a low signal return level of ∼1 photon per pixel.
Geological disasters refer to adverse geological phenomena that occur under the influence of natural or human factors and cause damage to human life and property. Establishing prevention and control ...zones based on geological disaster risk assessment results in land planning and management is crucial for ensuring safe regional development. In recent years, there has been an increase in extreme rainfall events, so it is necessary to conduct effective geological hazard and risk assessments for different extreme rainfall conditions. Based on the first national geological disaster risk survey results, this paper uses the analytic hierarchy process (AHP) combined with the information method (IM) to construct four extreme rainfall conditions, namely, 10-year, 20-year, 50-year, and 100-year return periods. The susceptibility, hazard, vulnerability, and risk of geological disasters in the Laoshan District in eastern China are evaluated, and prevention and control zones are established based on the evaluation results. The results show that: (1) There are 121 collapse geological disasters in Laoshan District, generally at a low susceptibility level. (2) A positive correlation exists between extreme rainfall and hazards/risks. With the rainfall condition changing from a 10-year return period to a 100-year return period, the proportion of high-hazard zones increased from 20% to 41%, and high-risk zones increased from 31% to 51%, respectively. The Receiver operating characteristic (ROC) proved that the assessment accuracy was acceptable. (3) Key, sub-key, and general prevention zones have been established, and corresponding prevention and control suggestions have been proposed, providing a reference for geological disaster prevention and early warning in other regions.
High-resolution real-space imaging of nanoparticle surfaces is desirable for better understanding of surface composition and morphology, molecular interactions at the surface, and nanoparticle ...chemical functionality in its environment. However, achieving molecular or sub-molecular resolution has proven to be very challenging, due to highly curved nanoparticle surfaces and often insufficient knowledge of the monolayer composition. Here, we demonstrate sub-molecular resolution in scanning tunneling microscopy imaging of thiol monolayer of a 5 nm nanoparticle Ag
protected by tert-butyl benzene thiol. The experimental data is confirmed by comparisons through a pattern recognition algorithm to simulated topography images from density functional theory using the known total structure of the Ag
nanocluster. Our work demonstrates a working methodology for investigations of structure and composition of organic monolayers on curved nanoparticle surfaces, which helps designing functionalities for nanoparticle-based applications.
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