The determination of airborne redox-active compounds (ARC) is essential for monitoring adverse environmental changes and understanding the potential impact on human health. With the exception of relying on the common total organic carbon (TOC) analyzer and dithiothreitol (DTT) assay, there is currently no easy-to-use method for quantitative assessment. Herein, a compatible and easy-to-use colorimetric sensing strategy was developed for on-site ARC quantification. This approach integrated a plasmonic sensing system, where the ARC-induced gold nanoparticles (AuNPs) reduction, localized surface plasmon resonance (LSPR), and the light-mediated photochemistry collaborated to achieve a limit of detection (LOD) at 0.05 μg∙mm−2 on the filters. Distinguished from the abovementioned methods, the ARC content can be directly determined by in-situ monitoring the colorimetric reaction on the sampling quartz filters (QF) without additional sample pre-treatment. Apart from utilizing the standard benchtop photodetector (e.g., UV–VIS spectrophotometer), the colorimetric images of AuNP@QF samples could also be imaged by a smartphone camera in a sealed box and analyzed through a smartphone-based application to read the RGB (Red, Green, Blue) values for ARC quantification. The good correlation between the results using the spectrophotometer and smartphone validate the applicability of the AuNP sensor. The smartphone-based method was then deployed to test real-world aerosols collected from Zurich, Bern and Rigi and the results of ARC exhibited a positive correlation with that of PM10. With the advantages of low-cost, easy-operation and no need for pre-treatment, this smartphone-based plasmonic system holds great potential for rapid and portable ARC detection and corresponding air quality assessment.
Motivation: Multiple sclerosis (MS) is characterized by diverse metabolic alterations. 1H-MRSI provides a unique capability for non-invasive mapping of neurometabolites but is often limited in resolution, scanning time, and brain coverage. Goal(s): Our goal was to demonstrate the feasibility of high-resolution whole-brain 1H-MRSI for characterizing metabolic alterations in MS. Approach: 3D 1H-MRSI scanning using SPICE technology (scan time: 10 minutes, resolution: 2×3×3 mm3, FOV: 240×240×120 mm3) was performed on 44 MS patients. Results: N-acetylaspartate (NAA), myo-inositol (mI), creatine, and choline levels altered among different lesion types and peri-plaque regions. NAA and mI/NAA differentiated RRMS and PMS patients in association with clinical scores. Impact: High-resolution whole-brain 1H-MRSI provides a promising tool for non-invasive metabolic imaging to characterize MS pathophysiology.
Airborne hyperspectral imaging plays an increasingly important role in environmental monitoring. However, due to the limitations of the acquisition conditions, there are uneven radiation and chromatic aberrations in the mosaic data. Accurate preprocessing of the original data is the premise of qualitative and quantitative remote sensing. In this study, we proposed a comprehensive radiation distortion correction method that integrates radiation attenuation difference correction, topographic correction, and multi-strip images consistency adjustment (RA-TOC-CA). First, the radiation attenuation equation was constructed by combining the viewing geometry, terrain, and the elevation difference between the UAV and the ground to eliminate the radiation attenuation difference of pixels acquired at the different instantaneous field of view (IFOV). Second, an improved kernel-driven BRDF model was built combining terrain information and illumination-viewing (flight attitude and sensor IFOV) geometry to eliminate the radiation unevenness and BRDF distortion caused by topography. Third, adjusting the reflectance of multi-strip images according to the homonymous points’ reflectance of adjacent strips should be equal, eliminating the radiation differences between multiple strips. Based on multi-strip airborne hyperspectral images collected in the Shaanxi province of China, the correction results of the RA-TOC-CA method were compared with those of the SCS+C and Minnaert+SCS methods regarding various evaluation criteria. The results showed that SCS+C and Minnaert+SCS can reduce the topographic effect but cannot eliminate the reflectance difference at the edges of adjacent images, and SCS+C overcorrects the reflectance. RA-TOC-CA weakened the topographic effects and brightness gradient, which was physically stable and generalizable. Compared with previous studies, RA-TOC-CA provided a complete radiation distortion correction method for airborne hyperspectral images and had a solid theoretical basis. This study introduces an effective method for radiation distortion correction of airborne hyperspectral images and provides technical support for large-scale applications of hyperspectral images.
Open-pit coal mining plays an important role in supporting national economic development; however, it has caused ecological problems and even seriously impacted regional ecological stability. Given the importance of maintaining ecological stability in semi-arid coal mining areas, this study used a coupling coordination degree approach based on the structural and functional state transition model (SFSTM) to evaluate the spatio–temporal variation of ecological stability from 2002 to 2017 by using MODIS and Landsat datasets in the semi-arid open-pit coal mining area. Besides, random points were created for different ecological stability levels (containing natural areas, coal mining areas, and reclamation areas) and segment linear regression was conducted to determine the structural change threshold for negative state transitions based on mining and positive state transitions based on reclamation. Furthermore, the impact factors of ecological stability were analyzed. Results showed that ecological stability fluctuated significantly over 16 years, showing a trend of first increasing and then decreasing. It was found that precipitation and temperature were the key natural factors affecting ecological stability, and mining activities constituted the dominant factor. The average perturbation distances to ecological stability from mining activities in the west, southwest, and east mining groups were 7500, 5500, and 8000 m, respectively. SFSTM is appliable to the coal mining ecosystem. Quantitative models of ecological stability response can help resolve ambiguity about management efficacy and the ecological stability results facilitate iterative updating of knowledge by using monitoring data from coal mining areas. Moreover, the proposed ecological structural threshold provides a useful early warning tool, which can aid in the reduction of ecosystem uncertainty and avoid reverse transformations of the positive state in the coal mining areas.
The soluble fraction of atmospheric transition metals is particularly associated with health effects such as reactive oxygen species compared to total metals. However, direct measurements of the soluble fraction are restricted to sampling and detection units in sequence burdened with a compromise between time resolution and system bulkiness. Here, we propose the concept of aerosol-into-liquid capture and detection, which allowed one-step particle capture and detection via the Janus-membrane electrode at the gas-liquid interface, enabling active enrichment and enhanced mass transport of metal ions. The integrated aerodynamic/electrochemical system was capable of capturing airborne particles with a cutoff size down to 50 nm and detecting Pb(II) with a limit of detection of 95.7 ng. The proposed concept can pave the way for cost-effective and miniaturized systems, for the capture and detection of airborne soluble metals in air quality monitoring, especially for abrupt air pollution events with high airborne metal concentrations (e.g., wildfires and fireworks).
The Beirut port explosion in 2020 released a huge amount of chemicals including ammonium nitrate, however, the long-term effects of the explosion on air quality and public health remain unclear. In this study, particulate matter (PM10) samples were collected in Beirut, Lebanon 1 month and 3 months after the explosion. The average concentrations of main anions measured in 2020 (one and three months after the explosion) were compared with those in 2009–2015 by calculating the percentage of difference, and the average concentrations of cations and anions in September (one month after the explosion) and November (three months after the explosion) 2020 were also compared to identify any abnormal values, indicating insignificant effects on the post-explosion PM in terms of component concentrations. That is, PM and gases directly induced by the explosion might be subject to rapid atmospheric transport and deposition. Hence, the results imply that investigations of the chemical contaminations in soil and water are urgently needed. Long-term monitoring is necessary to avoid subsequent air pollution caused by possible particle resuspension. The continuous demolition and reconstruction after the explosion are possibly the main long-term effect of the Beirut port explosion, causing an elevated concentration of PM2.5 at ground level 400% higher than the recommended concentrations (15 µg m–3 for 24-hour mean). Protective measures must be taken to reduce the exposure risks by controlling the PM release from demolition and construction, traffic, and diesel generators. The cancer risk in Beirut based on PAHs measurements in 2021 was also estimated and discussed.
This study aims to elucidate the historical justification for protection and restoration efforts in China while also examining the theoretical underpinnings of ecological conservation and restoration. Utilizing a literature review method, logical reasoning method, and inductive summarizing method, the historical and theoretical frameworks of territorial spatial ecological conservation and restoration are elucidated, leading to the following conclusions: (1) The ecological protection and restoration of national land space represents an advanced form of land remediation; however, they differ in terms of objects, principles, goals, and measures. (2) Territorial space ecological protection and restoration is historically unavoidable due to the current phase of societal development, driven by the natural environment and the necessity to establish an ecological civilization. (3) To implement territorial spatial ecological protection and restoration effectively and rationally, it is essential to comprehend its systematicity, territoriality, dynamics, and scientificity. By clarifying its historical and theoretical rationale, we can achieve a deeper understanding of its current relevance. This can effectively inform practical efforts in territorial spatial ecological protection and restoration.
Passive acoustic monitoring is an increasingly important tool for whale research. Accurately detecting the end-point of whale whistle is an essential task in the study of marine mammal calls. However, the detection accuracy of the beluga whistle is reduced due to the non-stationary burst pulse interference in the marine environment. In this paper, an unsupervised two-stage beluga whistle end-point detection method is proposed to solve the above problem. Based on the high Q-factor wavelet decomposition, a rough whistle detection method is proposed to remove the silent time and the low intensity pulse. On this basis, local density adaptive spectral clustering is designed to further distinguish whistle and strong pulse interference based on the sparsity difference in time-frequency domain. The performance of the detector is tested with real signals of beluga whales, and its F 1-score is calculated. The result shows that the detector is obviously better than the traditional whistle detectors under the background of burst pulse interferences, and has higher robustness. In the future, the presented method is supposed to be applied for detecting whistles of some other whale species.
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