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In Situ Monitoring of the Antibacterial Activity of a Copper–Silver Alloy Using Confocal Laser Scanning Microscopy and pH Microsensors
摘要： The antibacterial efficacy of a copper–silver alloy coating under conditions resembling build up of dry surface bacterial biofilms is successfully demonstrated according to US EPA test methods with a ≥99.9% reduction of test organisms over a 24 h period. A tailor-made confocal imaging protocol is designed to visualize in situ the killing of bacterial biofilms at the copper–silver alloy surface and monitor the kinetics for 100 min. The copper–silver alloy coating eradicates a biofilm of Gram-positive bacteria within 5 min while a biofilm of Gram-negative bacteria are killed more slowly. In situ pH monitoring indicates a 2-log units increase at the interface between the metallic surface and bacterial biofilm; however, the viability of the bacteria is not directly affected by this raise (pH 8.0–9.5) when tested in buffer. The OH? production, as a result of the interaction between the electrochemically active surface and the bacterial biofilm under environmental conditions, is thus one aspect of the contact-mediated killing of the copper–silver alloy coating and not the direct cause of the observed antibacterial efficacy. The combination of oxidation of bacterial cells, release of copper ions, and local pH raise characterizes the antibacterial activity of the copper–silver alloy-coated dry surface.
关键词： bacterial biofilms,confocal laser scanning microscopy,copper–silver alloy,electroplating,antibacterial activity
更新于2025-09-11 14:15:04
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Structural 3D Reconstruction of Indoor Space for 5G Signal Simulation with Mobile Laser Scanning Point Clouds
摘要： 3D modelling of indoor environment is essential in smart city applications such as building information modelling (BIM), spatial location application, energy consumption estimation, and signal simulation, etc. Fast and stable reconstruction of 3D models from point clouds has already attracted considerable research interest. However, in the complex indoor environment, automated reconstruction of detailed 3D models still remains a serious challenge. To address these issues, this paper presents a novel method that couples linear structures with three-dimensional geometric surfaces to automatically reconstruct 3D models using point cloud data from mobile laser scanning. In our proposed approach, a fully automatic room segmentation is performed on the unstructured point clouds via multi-label graph cuts with semantic constraints, which can overcome the over-segmentation in the long corridor. Then, the horizontal slices of point clouds with individual room are projected onto the plane to form a binary image, which is followed by line extraction and regularization to generate ?oorplan lines. The 3D structured models are reconstructed by multi-label graph cuts, which is designed to combine segmented room, line and surface elements as semantic constraints. Finally, this paper proposed a novel application that 5G signal simulation based on the output structural model to aim at determining the optimal location of 5G small base station in a large-scale indoor scene for the future. Four datasets collected using handheld and backpack laser scanning systems in di?erent locations were used to evaluate the proposed method. The results indicate our proposed methodology provides an accurate and e?cient reconstruction of detailed structured models from complex indoor scenes.
关键词： mobile laser scanning,point clouds,5G signal simulation,3D reconstruction,indoor modelling
更新于2025-09-11 14:15:04
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[Advances in Ecological Research] Mechanisms underlying the relationship between biodiversity and ecosystem function Volume 61 || Terrestrial laser scanning reveals temporal changes in biodiversity mechanisms driving grassland productivity
摘要： Biodiversity often enhances ecosystem functioning likely due to multiple, often temporarily separated drivers. Yet, most studies are based on one or two snapshot measurements per year. We estimated productivity using bi-weekly estimates of high-resolution canopy height in 2 years with terrestrial laser scanning (TLS) in a grassland diversity experiment. We measured how different facets of plant diversity (functional dispersion [FDis], functional identity [PCA species scores], and species richness [SR]) predict aboveground biomass over time. We found strong intra- and inter-annual variability in the relative importance of different mechanisms underlying the diversity effects on mean canopy height, i.e., resource partitioning (via FDis) and identity effects (via species scores), respectively. TLS is a promising tool to quantify community development non-destructively and to unravel the temporal dynamics of biodiversity-ecosystem functioning mechanisms. Our results show that harvesting at estimated peak biomass—as done in most grassland experiments—may miss important variation in underlying mechanisms driving cumulative biomass production.
关键词： functional diversity,functional identity,ecosystem functioning,Biodiversity,species richness,grassland,terrestrial laser scanning
更新于2025-09-11 14:15:04
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A Simple and Rapid Staining Technique for Sex Determination of Trichinella Larvae Parasites by Confocal Laser Scanning Microscopy
摘要： The roundworms of Trichinella genus are worldwide distributed and their prevalence in nature is high. Trichinella genus parasites are the causative agents of foodborne zoonosis trichinellosis. The main prevention and control of the infection are meat inspection by the magnetic stirrer method for the detection of Trichinella larvae in muscle samples. The treatment can be effective if the parasite is discovered early in the intestinal phase. Once the Trichinella larva has reached the muscle tissue, the parasite remains therein and there is no treatment for this life cycle stage. The Trichinella species is dioecious with separate male and female individuals. The developed staining technique that uses confocal laser scanning microscopy (CLSM) displays sufficient results for Trichinella larvae examination and this protocol is applicable to study the internal and external structures and for the sex determination of T. britovi and T. spiralis larvae samples. In the present study, a luminescent derivative was synthesized and used for staining of T. spiralis and T. britovi larvae samples for the examination by CLSM. Various fixatives, such as AFA, 70% ethanol, and Bouin’s and Carnoy’s solutions were tested for sample preparation. The synthesized luminescent compound demonstrates best visualization results for samples fixed in Bouin’s fixative.
关键词： benzanthrone dye,fixatives,confocal laser scanning microscopy,Trichinella larvae sex determination,Bouin’s fixative
更新于2025-09-11 14:15:04
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Tree crown segmentation based on a tree crown density model derived from Airborne Laser Scanning
摘要： This letter describes a new algorithm for automatic tree crown delineation based on a model of tree crown density, and its validation. The tree crown density model was first used to create a correlation surface, which was then input to a standard watershed segmentation algorithm for delineation of tree crowns. The use of a model in an early step of the algorithm neatly solves the problem of scale selection. In earlier studies, correlation surfaces have been used for tree crown segmentation, involving modelling tree crowns as solid geometric shapes. The new algorithm applies a density model of tree crowns, which improves the model’s suitability for segmentation of Airborne Laser Scanning (ALS) data because laser returns are located inside tree crowns. The algorithm was validated using data acquired for 36 circular (40 m radius) field plots in southern Sweden. The algorithm detected high proportions of field-measured trees (40–97% of live trees in the 36 field plots: 85% on average). The average proportion of detected basal area (cross-sectional area of tree stems, 1.3 m above ground) was 93% (range: 84–99%). The algorithm was used with discrete return ALS point data, but the computation principle also allows delineation of tree crowns in ALS waveform data.
关键词： Tree crown segmentation,tree crown density model,Airborne Laser Scanning,forest mapping,watershed segmentation
更新于2025-09-11 14:15:04
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AdTree: Accurate, Detailed, and Automatic Modelling of Laser-Scanned Trees
摘要： Laser scanning is an effective tool for acquiring geometric attributes of trees and vegetation, which lays a solid foundation for 3-dimensional tree modelling. Existing studies on tree modelling from laser scanning data are vast. However, some works cannot guarantee sufficient modelling accuracy, while some other works are mainly rule-based and therefore highly depend on user inputs. In this paper, we propose a novel method to accurately and automatically reconstruct detailed 3D tree models from laser scans. We first extract an initial tree skeleton from the input point cloud by establishing a minimum spanning tree using the Dijkstra shortest-path algorithm. Then, the initial tree skeleton is pruned by iteratively removing redundant components. After that, an optimization-based approach is performed to fit a sequence of cylinders to approximate the geometry of the tree branches. Experiments on various types of trees from different data sources demonstrate the effectiveness and robustness of our method. The overall fitting error (i.e., the distance between the input points and the output model) is less than 10 cm. The reconstructed tree models can be further applied in the precise estimation of tree attributes, urban landscape visualization, etc. The source code of this work is freely available at https://github.com/tudelft3d/adtree.
关键词： point cloud,precision forestry,laser scanning,tree modelling
更新于2025-09-11 14:15:04
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A deterministic-stochastic identification and modelling method of discrete fracture networks using laser scanning: Development and case study
摘要： The intelligent identification of and information extraction from discontinuities in fractured rock masses is crucial for the construction of a 3D fracture network model. A Deterministic-Stochastic Identification and Modelling (DSIM) method for use with discrete fracture networks is proposed using laser scanning technology. The identification of and information extraction from discontinuities is carried out using point cloud data processing by analyzing the outcrop characteristics of the joints and bedding planes visible on the surfaces of the rock mass. For joints, their orientations are extracted using a region growing algorithm, while their sizes are fitted using the Gauss function. For bedding planes, their orientations and sizes are extracted from the 3D point cloud and real image data in a semi-automatic manner. Afterwards, a constrained circle algorithm is applied to restrict the spatial size and shape of the polygonal fractures. In this way, the DSIM method is developed, which conforms to the outcrop characteristics of the bedding planes and joints. From the perspectives of the geometry and geostatistics of discrete fractures, complex discontinuities in 3D space are grouped and spatial density distribution functions are formulated. A corresponding program is compiled to identify and model discrete fracture networks. Finally, a case study was carried out in the Hejing Limestone Mine, Guangxi, China. The proposed DSIM method was validated with real site data and numerical verifications. In addition, the case study also demonstrates that the DISM method can effectively reduce the uncertainty in the identification and modelling of discrete fracture networks (DFN).
关键词： constrained circle algorithm,discrete fracture network (DFN),3D laser scanning,deterministic-stochastic,discontinuity identification
更新于2025-09-11 14:15:04
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A new 3D laser-scanning and GPS combined measurement system
摘要： Terrestrial laser scanning (TLS) is widely used because of its ability to quickly acquire high-density and high-precision 3D image and topographic data. However, it can only acquire independent coordinate system points, which restricts its application in large-scale deformation monitoring. In this study, we constructed a measurement system to acquire global coordinate point cloud data by combining TLS and GPS (Global Positioning System). The coordinate values of retro-re?ective targets could be acquired in different coordinate systems, the GPS coordinate and the TLS station coordinate, synchronously. Our experiments showed that, after registration with the homonymy points acquired by 30-min short-baseline differential GPS using the ICP algorithm, the positional accuracy of the TLS retro-re?ective target center in the global coordinate was better than 10 mm. This high precision meets, for instance, the requirements of coal mining subsidence monitoring. We used our new combined measurement system to acquire and process the point cloud data of a frame structure. The measurements demonstrated the practicability and robustness of the new measurement system.
关键词： ICP,Differential GPS,Data fusion,Terrestrial laser scanning
更新于2025-09-11 14:15:04
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Estimating Stand Age from Airborne Laser Scanning Data to Improve Models of Black Spruce Wood Density in the Boreal Forest of Ontario
摘要： Spatial models that provide estimates of wood quality enable value chain optimization approaches that consider the market potential of trees prior to harvest. Ecological land classification units (e.g., ecosite) and structural metrics derived from Airborne Laser Scanning (ALS) data have been shown to be useful predictors of wood quality attributes in black spruce stands of the boreal forest of Ontario, Canada. However, age drives much of the variation in wood quality among trees, and has not been included as a predictor in previous models because it is poorly represented in inventory systems. The objectives of this study were (i) to develop a predictive model of mean stem age of black spruce-dominated stands, and (ii) refine models of black spruce wood density by including age as a predictor variable. A non-parametric model of stand age that used a k nearest neighbor (kNN) classification based on a random forests (rf) distance metric performed well, producing a root mean square difference (RMSD) of 15 years and explaining 62% of the variance. The subsequent random forests model of black spruce wood density generated from age and ecosite predictors was useful, with a root mean square error (RMSE) of 59.1 kg·m?3. These models bring large-scale wood quality prediction closer to becoming operational by including age and site effects that can be derived from inventory data.
关键词： predictive modeling,forest stand age,LiDAR,boreal forest,wood density modeling,black spruce,forest resource inventory,Airborne Laser Scanning (ALS),k-Nearest Neighbor
更新于2025-09-11 14:15:04
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A comparison of UAV laser scanning, photogrammetry and airborne laser scanning for precision inventory of small-forest properties
摘要： This study addresses the use of multiple sources of auxiliary data from unmanned aerial vehicles (UAVs) and airborne laser scanning (ALS) data for inference on key biophysical parameters in small forest properties (5–300 ha). We compared the precision of the estimates using plot data alone under a design-based inference with model-based estimates that include plot data and the following four types of auxiliary data: (1) terrain-independent variables from UAV photogrammetric data (UAV-SfM); (2) variables obtained from UAV photogrammetric data normalized using external terrain data (UAV-SfMDTM); (3) UAV-LS and (4) ALS data. The inclusion of remotely sensed data increased the precision of DB estimates by factors of 1.5–2.2. The optimal data sources for top height, stem density, basal area and total stem volume were: UAV-LS, UAV-SfM, UAV-SfMDTM and UAV-SfMDTM. We conclude that the use of UAV data can increase the precision of stand-level estimates even under intensive ?eld sampling conditions.
关键词： UAV,laser scanning,photogrammetry,forest inventory,precision forestry,ALS
更新于2025-09-11 14:15:04