The occurrence of corona discharge in ultra-high-voltage direct current transmission lines results in the generation of space charge, which significantly affects the nearby electromagnetic ...environment. To investigate the micro-physical mechanisms of discharge and provide better guidance for the calculation of the ground ion current density and total electric field, a method based on the theory of the transport of diluted species is proposed. This method enables the visualization and analysis of the movement process of space charge in air medium, as well as the calculation of the total electric field below the transmission lines. To validate the effectiveness of this algorithm, experimental tests of the total electric field are conducted on actual transmission lines. The experimental results demonstrate that the algorithm not only highlights the evident differences in the transient microscopic processes between positive and negative corona discharges but also accurately calculates the total electric field below the transmission lines. In addition, considering the weather conditions in the Chongqing region, relevant recommendations are provided under the influence of wind speed, aiming to offer protection guidelines for individuals engaged in activities near transmission lines.
Context
Ferroelectric ceramic polymer composites have become the preferred electrocaloric materials due to their light weight and high polarization strength. But the mechanical properties were ...desired to be improved. In this study, the polyvinylidene fluoride trifluoro ethylene chloride (PVTC) and barium titanate (BT) composites were prepared, and the microstructure and mechanical properties were investigated by molecular dynamics simulations and experiments. It was found that with the increase of BT ceramic content in the composites, the yield stress is significantly reduced, which can be reduced by 16.07%. By comparing with the experimental data, the agglomeration and stress mechanism of the composites were proposed.
Method
The microstructure of the composite was analyzed using radial distribution function, self-diffusion coefficient, and glass transition temperature. The agglomeration mechanism of the composite was revealed from the microscopic point of view, and the rationality of the agglomeration behavior was verified by experiments. The calculations were performed by Material Studio 2019 software and the COMPASS force field was adopted.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Instance segmentation has been developing rapidly in recent years. Mask R-CNN, a two-stage instance segmentation approach, has demonstrated exceptional performance. However, the masks are still very ...coarse. The downsampling operation of the backbone network and the ROIAlign layer loses much detailed information, especially from large targets. The sawtooth effect of the edge mask is caused by the lower resolution. A lesser percentage of boundary pixels leads to not-fine segmentation. In this paper, we propose a new method called Boundary Refine (BRefine) that achieves high-quality segmentation. This approach uses FCN as the foundation segmentation architecture, and forms a multistage fusion mask head with multistage fusion detail features to improve mask resolution. However, the FCN architecture causes inconsistencies in multiscale segmentation. BRank and sort loss (BR and S loss) is proposed to solve the problems of segmentation inconsistency and the difficulty of boundary segmentation. It is combined with rank and sort loss, and boundary region loss. BRefine can handle hard-to-partition boundaries and output high-quality masks. On the COCO, LVIS, and Cityscapes datasets, BRefine outperformed Mask R-CNN by 3.0, 4.2, and 3.5 AP, respectively. Furthermore, on the COCO dataset, the large objects improved by 5.0 AP.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Thiosulfate oxidation by microbes has a major impact on global sulfur cycling. Here, we provide evidence that bacteria within various Roseobacter lineages are important for thiosulfate oxidation in ...marine biofilms. We isolate and sequence the genomes of 54 biofilm-associated Roseobacter strains, finding conserved sox gene clusters for thiosulfate oxidation and plasmids, pointing to a niche-specific lifestyle. Analysis of global ocean metagenomic data suggests that Roseobacter strains are abundant in biofilms and mats on various substrates, including stones, artificial surfaces, plant roots, and hydrothermal vent chimneys. Metatranscriptomic analysis indicates that the majority of active sox genes in biofilms belong to Roseobacter strains. Furthermore, we show that Roseobacter strains can grow and oxidize thiosulfate to sulfate under both aerobic and anaerobic conditions. Transcriptomic and membrane proteomic analyses of biofilms formed by a representative strain indicate that thiosulfate induces sox gene expression and alterations in cell membrane protein composition, and promotes biofilm formation and anaerobic respiration. We propose that bacteria of the Roseobacter group are major thiosulfate-oxidizers in marine biofilms, where anaerobic thiosulfate metabolism is preferred.
High frame-rate ultrasound RF data acquisition has been proved to be critical for novel cardiovascular imaging techniques, such as high-precision myocardial elastography, pulse wave imaging (PWI), ...and electromechanical wave imaging (EWI). To overcome the frame-rate limitations on standard clinical ultrasound systems, we developed an automated method for multi-sector ultrasound imaging through retrospective electrocardiogram (ECG) gating on a clinically used open architecture system. The method achieved both high spatial (64 beam density) and high temporal resolution (frame rate of 481 Hz) at an imaging depth up to 11 cm and a 100% field of view in a single breath-hold duration. Full-view imaging of the left ventricle and the abdominal aorta of healthy human subjects was performed using the proposed technique in vivo. ECG and ultrasound RF signals were simultaneously acquired on a personal computer (PC). Composite, full-view frames both in RF- and B-mode were reconstructed through retrospective combination of seven small (20%) juxtaposed sectors using an ECG-gating technique. The axial displacement of the left ventricle, in both long-axis and short-axis views, and that of the abdominal aorta, in a long-axis view, were estimated using a RF-based speckle tracking technique. The electromechanical wave and the pulse wave propagation were imaged in a cineloop using the proposed imaging technique. Abnormal patterns of such wave propagation can serve as indicators of early cardiovascular disease. This clinical system could thus expand the range of applications in cardiovascular elasticity imaging for quantitative, noninvasive diagnosis of myocardial ischemia or infarction, arrhythmia, abdominal aortic aneurysms, and early-stage atherosclerosis.
The ecological integrity and biodiversity of steppes were destroyed under the long-term and high-intensity development of open-pit coal mines in China, causing desertification, steppe degradation, ...landscape function defect, and so on. As a source of species maintenance and dispersal, an ecological source is a key area for preservation in order to restore the ecological security pattern of the larger landscape. The purpose of this study was to establish a landscape key area recognition model to identify the landscape key areas (LKA) surrounding an open pit coalmine located in semi-arid steppe. This study takes the Yimin open pit mining area as a case study. We assessed Landsat 5 Thematic Mapper (TM) and Landsat 8 Operational Land Imager (OLI) remote sensing images taken during the peak season of vegetation growth from July to August in 1999, 2006, 2011, and 2017. From these images, we identified the main landscape types and vegetation coverage grades in order to identify the ecological land. Next, we applied the three indices of Importance of Patch Connectivity, Habitat Quality, and Ecosystem Service Value to calculate the comprehensive results that identify ecological land. Finally, the ecological land quality results of different years are superimposed and averaged, and then Very Important Patch (VIMP), Important Patch (IMP), and General Patch (GEP) areas were used for LKA extraction. Our results showed LKA to cover 177.35 km2, accounting for 20.01% of the total study area. The landscape types identified as LKA are primarily grassland (47.37%), wetland (40.27%), and shrubland (11.88%), indicating that landscape type correlates strongly with its value as a landscape key area. The proposed landscape key area recognition model could enrich the foundations for ecological planning and ecological security pattern construction in order to support ecological protection and restoration in semi-arid steppe areas affected by coal mining.
On the gradual implementation of the new medical education reform and thoroughly applying the Educational Development Plan and the Health Care System Reform, the teaching mode of medical discipline ...will be changed gradually by following the law of medical education and meeting the need to boost the medical education reform. Meanwhile, the changing life-style prompts the traditional dispensing mode for Chinese traditional medicine to various modes. This changing put forward higher requirement for medicine- related professionals During the process of Chinese medicine teaching, the only method which can fulfill the new need for graduates of Chinese medicine and qualified medicine personals is to change the traditional teaching mode to the new ones which can arose the enthusiasm of working and learning by the traditional medicine students.
The therapeutic efficacy of neurological agents is severely limited, because large compounds do not cross the blood-brain barrier (BBB). Focused ultrasound (FUS) sonication in the presence of ...microbubbles has been shown to temporarily open the BBB, allowing systemically administered agents into the brain. Until now, polydispersed microbubbles (1-10 ¿m in diameter) were used, and, therefore, the bubble sizes better suited for inducing the opening remain unknown. Here, the FUS-induced BBB opening dependence on microbubble size is investigated. Bubbles at 1-2 and 4-5 ¿m in diameter were separately size-isolated using differential centrifugation before being systemically administered in mice ( n = 28). The BBB opening pressure threshold was identified by varying the peak-rarefactional pressure amplitude. BBB opening was determined by fluorescence enhancement due to systemically administered, fluorescent-tagged, 3-kDa dextran. The identified threshold fell between 0.30 and 0.46 MPa in the case of 1-2 ¿m bubbles and between 0.15 and 0.30 MPa in the 4-5 ¿m case. At every pressure studied, the fluorescence was greater with the 4-5 ¿m than with the 1-2 ¿m bubbles. At 0.61 MPa, in the 1-2 ¿m bubble case, the fluorescence amount and area were greater in the thalamus than in the hippocampus. In conclusion, it was determined that the FUS-induced BBB opening was dependent on both the size distribution in the injected microbubble volume and the brain region targeted.
Focused ultrasound (FUS) is hereby shown to noninvasively and selectively deliver compounds at pharmacologically relevant molecular weights through the opened blood-brain barrier (BBB). A complete ...examination on the size of the FUS-induced BBB opening, the spatial distribution of the delivered agents and its dependence on the agent's molecular weight were imaged and quantified using fluorescence microscopy. BBB opening in mice (n=13) was achieved in vivo after systemic administration of microbubbles and subsequent application of pulsed FUS (frequency: 1.525MHz, peak-rarefactional pressure in situ: 570 kPa) to the left murine hippocampus through the intact skin and skull. BBB-impermeant, fluorescent-tagged dextrans at three distinct molecular weights spanning over several orders of magnitude were systemically administered and acted as model therapeutic compounds. First, dextrans of 3 and 70 kDa were delivered trans-BBB while 2000 kDa dextran was not. Second, compared with 70 kDa dextran, a higher concentration of 3 kDa dextran was delivered through the opened BBB. Third, the 3 and 70 kDa dextrans were both diffusely distributed throughout the targeted brain region. However, high concentrations of 70 kDa dextran appeared more punctated throughout the targeted region. In conclusion, FUS combined with microbubbles opened the BBB sufficiently to allow passage of compounds of at least 70 kDa, but not greater than 2000 kDa into the brain parenchyma. This noninvasive and localized BBB opening technique could, thus, provide a unique means for the delivery of compounds of several magnitudes of kDa that include agents with shown therapeutic promise in vitro but whose in vivo translation has been hampered by their associated BBB impermeability. (E-mail: ek2191@columbia.edu).
Marine biofilms are a collective of microbes that can grow on many different surfaces immersed in marine environments. Estimating the microbial richness and specificity of a marine biofilm community ...is a challenging task due to the high complexity in comparison with seawater. Here, we compared the resolution of full-length 16S rRNA gene sequencing technique of a PacBio platform for microbe identification in marine biofilms with the results of partial 16S rRNA gene sequencing of traditional Illumina PE250 platform. At the same time, the microbial richness, diversity, and composition of adjacent seawater communities in the same batch of samples were analyzed. Both techniques revealed higher species richness, as reflected by the Chao1 index, in the biofilms than that in the seawater communities. Moreover, compared with Illumina sequencing, PacBio sequencing detected more specific species for biofilms and less specific species for seawater. Members of Vibrio, Arcobacter, Photobacterium, Pseudoalteromonas, and Thalassomonas were significantly enriched in the biofilms, which is consistent with the previous understanding of species adapted to a surface-associated lifestyle and validates the taxonomic analyses in the current study. To conclude, the full-length sequencing of 16S rRNA genes has probably a stronger ability to analyze more complex microbial communities, such as marine biofilms, the species richness of which has probably been under-estimated in previous studies.
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