With the rapid development of various technologies of satellite sensor, synthetic aperture radar (SAR) image has been an import source of data in the application of change detection. In this paper, a ...novel method based on a convolutional neural network (CNN) for SAR image change detection is proposed. The main idea of our method is to generate the classification results directly from the original two SAR images through a CNN without any preprocessing operations, which also eliminate the process of generating the difference image (DI), thus reducing the influence of the DI on the final classification result. In CNN, the spatial characteristics of the raw image can be extracted and captured by automatic learning and the results with stronger robustness can be obtained. The basic idea of the proposed method includes three steps: it first produces false labels through unsupervised spatial fuzzy clustering. Then we train the CNN through proper samples that are selected from the samples with false labels. Finally, the final detection results are obtained by the trained convolutional network. Although training the convolutional network is a supervised learning fashion, the whole process of the algorithm is an unsupervised process without priori knowledge. The theoretical analysis and experimental results demonstrate the validity, robustness, and potential of our algorithm in simulated and real data sets. In addition, we try to apply our algorithm to the change detection of heterogeneous images, which also achieves satisfactory results.
Background and Objectives
The COVID‐19 pandemic and control measures may have increased the risk of abusing addictive substances as well as addictive behaviors.
Methods
We present an initial online ...survey in 6416 Chinese about the relation between the COVID‐19 pandemic and addictive behavior in China.
Results
During the COVID‐19 pandemic, 46.8% of the subjects reported increased dependence on internet use, and 16.6% had longer hours of internet use. The prevalence (4.3%) of severe internet dependence rose up to 23% than that (3.5%) before the COVID‐19 pandemic occurred, and their dependence degree rose 20 times more often than being declined (60% vs 3%). Relapses to abuse from alcohol and smoking abstinence were relatively common at 19% and 25%, respectively. Similarly, 32% of regular alcohol drinkers and 20% of regular smokers increased their usage amount during the pandemic.
Conclusion and Scientific Significance
These three coping behaviors (internet, alcohol, and smoking) during this COVID‐19‐related crisis appear to have increased the risk for substance use disorders and internet addiction. (Am J Addict 2020;00:00–00)
Synthesis of ethanol from non-petroleum carbon resources via syngas (a mixture of H
and CO) is an important but challenging research target. The current conversion of syngas to ethanol suffers from ...low selectivity or multiple processes with high energy consumption. Here, we report a high-selective conversion of syngas into ethanol by a triple tandem catalysis. An efficient trifunctional tandem system composed of potassium-modified ZnO-ZrO
, modified zeolite mordenite and Pt-Sn/SiC working compatibly in syngas stream in one reactor can afford ethanol with a selectivity of 90%. We demonstrate that the K
-ZnO-ZrO
catalyses syngas conversion to methanol and the mordenite with eight-membered ring channels functions for methanol carbonylation to acetic acid, which is then hydrogenated to ethanol over the Pt-Sn/SiC catalyst. The present work offers an effective methodology leading to high selective conversion by decoupling a single-catalyst-based complicated and uncontrollable reaction into well-controlled multi-steps in tandem in one reactor.
The Ce-doped modified porous nanocrystalline PbO2 film electrode prepared by electrodeposition technology was used for electrochemical mineralization of environmentally persistent perfluorinated ...carboxylic acids (PFCAs) (∼C4–C8), i.e., perfluorobutanoic acid (PFBA), perfluopentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoheptanoic acid (PFHpA), and perfluorooctanoic acid (PFOA) in aqueous solution (100 mL of 100 mg L–1). The degradation of PFCAs follows pseudo-first-order kinetics, and the values of the relative rate constant (k) depend upon chain length k PFHpA (4.1 × 10–2 min–1; corresponding half-life 16.8 min) ≈ 1.1k PFOA ≈ 2.5k PFHxA≈ 6.9k PFPeA ≈ 9.7k PFBA. The carbon mineralization indices i.e., 1 – (TOCinsolution/TOCinPFCA,degraded) were 0.49, 0.70, 0.84, 0.91, and 0.95 for PFBA, PFPeA, PFHxA, PFHpA, and PFOA, respectively, after 90 min electrolysis. The major mineralization product, F–, as well as low amount of intermediate PFCAs with shortened chain lengths were detected in aqueous solution. By observing the intermediates and tracking the concentration change, a possible pathway of electrochemical mineralization is proposed as follows: Kolbe decarboxylation reaction occurs first at the anode to form the perfluoroalkyl radical, followed by reaction with hydroxyl radicals to form the perfluoroalkyl alcohol which then undergoes intramolecular rearrangement to form the perfluoroalkyl fluoride. After this, the perfluoroalkyl fluoride reforms perfluorinated carboxylic with shorter chain length than its origin by hydrolysis. This electrochemical technique could be employed to treat PFCAs (∼C4–C8) in contaminated wastewater.
•Thermal pretreatment had varying impacts on anaerobic digestion.•Expanded research scope and comprehensive conclusions are obtained.•Characteristics of digestion kinetic are pretreatment temperature ...dependent.•Thermal treatment temperature is recommended to be less than 120°C.
In this study, batch tests were performed to evaluate the effects of different thermal pretreatment temperatures (55–160°C) and durations (15–120min) on the anaerobic digestion of kitchen waste (KW). Two commonly used approaches, namely the modified Gompertz model and the approach developed by Koch and Drewes, were applied to assess the effects of the different pretreatment parameters on the biomethane yield, lag time and hydrolysis rate constant via data fitting. The subsequent anaerobic digestion of KW pretreated at 55–120°C presented greater efficiency, and longer treatment durations resulted in increased methane production and higher hydrolysis rate constants. These findings were obtained due to the lower nutrient loss observed in KW treated at lower temperature treatments compared with that found with higher temperature treatments. In general, the effects of thermal pretreatment on the lag phase and hydrolysis rate differed depending on the treatment parameters leading to the variations in the KW compositions. The soundness of the two model results was evaluated, and higher statistical indicators (R2) were found with the modified Gompertz model than with the approach developed by Koch and Drewes.
In this work, a novel 3D graphene framework/Bi nanoparticle (GF/BiNP) film was fabricated with a facile preparation route. 3D graphene framework with porous structures was electrochemically reduced ...and in situ assembled on the electrode, and BiNPs with tunable morphologies were highly dispersed on the framework by a chemical reduction. Newly-designed 3D GF/BiNP film possessed a significantly large active area, fast electron transfer ability, high mass transfer efficiency, and excellent structure stability and binding strength on electrode. To demonstrate its superior ability, electrochemical sensors for the assay of heavy metal ions were constructed. As a result, a simultaneous assay of Pb2+ and Cd2+ with ultralow detection limits (0.02 μg L−1 of Pb2+ and 0.05 μg L−1 of Cd2+, S/N = 3) and a wide linear range from 1 to 120 μg L−1 was achieved. Meanwhile, a separate analysis of Zn2+ was performed to get optimum responses, in which a low detection limit of 4.0 μg L−1 (S/N = 3) with a linear range from 40 to 300 μg L−1 was observed, confirming the versatility of the GF/BiNP film in the detection of heavy metal ions. Moreover, excellent repeatability, reproducibility and stability, and reliable assays in real water samples were realized with constructed sensors. Due to its convenient preparation, favorable structures and excellent properties, prepared 3D GF/BiNP film will find great potential for advanced applications in environment, biomedicine and energy systems.
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•A novel 3D graphene framework/Bi nanoparticle (GF/BiNP) film is prepared.•Porous graphene framework is in situ assembled on the electrode.•BiNPs with tunable morphologies are highly dispersed on the framework.•Newly-designed 3D GF/BiNP film possesses excellent properties.•Sensitive electrochemical sensors for Pb2+, Cd2+ and Zn2+ are constructed.
Object detection has made significant progress in many real-world scenes. Despite this remarkable progress, the common use case of detection in remote sensing images remains challenging even for ...leading object detectors, due to the complex background, objects with arbitrary orientation, and large difference in scale of objects. In this paper, we propose a novel rotation detector for remote sensing images, mainly inspired by Mask R-CNN, namely RADet. RADet can obtain the rotation bounding box of objects with shape mask predicted by the mask branch, which is a novel, simple and effective way to get the rotation bounding box of objects. Specifically, a refine feature pyramid network is devised with an improved building block constructing top-down feature maps, to solve the problem of large difference in scales. Meanwhile, the position attention network and the channel attention network are jointly explored by modeling the spatial position dependence between global pixels and highlighting the object feature, for detecting small object surrounded by complex background. Extensive experiments on two remote sensing public datasets, DOTA and NWPUVHR -10, show our method to outperform existing leading object detectors in remote sensing field.
An unprecedented arylboration of unactivated terminal alkenes, featuring 1,n‐regioselectivity, has been achieved by nickel catalysis. The nitrogen‐based ligand plays an essential role in the success ...of this three‐component reaction. This transformation displays good regioselectivity and excellent functional‐group tolerance. In addition, the incorporation of a boron group into the products provides substantial opportunities for further transformations. Also demonstrated is that the products can be readily transformed into pharmaceutically relevant molecules. Unexpectedly, preliminary mechanistic studies indicate that although the metal migration favors the α‐position of boron, selective and decisive bond formation is favored at the benzylic position.
An unprecedented arylboration of unactivated terminal alkenes, featuring 1,n‐regioselectivity (n>2), has been achieved by nickel catalysis. An array of valuable alkylboronic esters are prepared with this method. Mechanism studies indicate that a nickel migration and a selective bond‐formation step are involved in this reaction.
The gas evolution effects on the electrolytic voltage under large current density in zero-gap alkaline water electrolyzer are investigated with specifically designed segmented electrodes and ...electrochemical measurements. 4 possible influencing pathways from gas evolution to electrolysis performance are summarized and quantified respectively for the first time. It is found that the impact of gas evolution behaviors on electrolytic voltage at up to 0.5 A/cm2 is below 50 mV, or 4% of total overpotential. Electrolysis voltage is split up to demonstrate the contribution of gas evolution induced impedance in ohmic and activate overpotentials.
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•Summary of 4 pathways from gas evolution behavior to electrolytic performance.•Quantification of each gas evolution behavior effect on electrolytic voltage.•Reveal the proportion of gas evolution contribution in total overpotential.
1,1-Diarylalkanes are important structural frameworks which are widespread in biologically active molecules. Herein, we report a reductive relay cross-coupling of alkyl bromides with aryl bromides by ...nickel catalysis with a simple nitrogen-containing ligand. This method selectively affords 1,1-diarylalkane derivatives with good to excellent yields and regioselectivity.
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