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27 pages, 14949 KiB  
Article
Experimental Study on Strength and Deformation Moduli of Columnar Jointed Rock Mass—Uniaxial Compression as an Example
by Zhenbo Xu, Zhende Zhu, Chao Jiang and Xiaobin Hu
Symmetry 2024, 16(10), 1380; https://doi.org/10.3390/sym16101380 (registering DOI) - 17 Oct 2024
Abstract
The irregular joint network unique to columnar joints separates the rock mass into several irregular polygonal prisms. Similar physical model specimens of columnar jointed rock mass (CJRM) were fabricated using a rock-like material. The effect of the irregularity of the joint network was [...] Read more.
The irregular joint network unique to columnar joints separates the rock mass into several irregular polygonal prisms. Similar physical model specimens of columnar jointed rock mass (CJRM) were fabricated using a rock-like material. The effect of the irregularity of the joint network was considered in the horizontal plane, and the effect of the dip angle of the joint network was considered in the vertical plane. The strength and deformation moduli of the specimen were investigated using uniaxial compression tests. A total of four failure modes of regular columnar jointed rock mass (RCJRM) and irregular columnar jointed rock mass (ICJRM) were identified through the tests. The peak stress of the irregular columnar jointed rock mass specimen is reduced by 56.65%. The strength and deformation moduli of RCJRM were greater than those of ICJRM, while the anisotropic characteristics of ICJRM were stronger. The failure mode of CJRM was determined by the dip angle. With the increase in the dip angle, the strength and deformation moduli of irregular columnar jointed rock mass are a symmetrical “V” type distribution, 45° corresponds to the minimum strength, and 30° obtains the minimum deformation modulus. With the increase in the irregularity coefficient, the strength and deformation moduli of CJRM decreased first and then increased gradually. When the irregularity coefficient is 0.1, the linear deformation modulus reaches the minimum value. When the irregularity coefficient is 0.7, the median deformation modulus reaches the minimum value. The fitting function proposed in the form of the cosine function managed to predict the strength value of CJRM and showed the strength of the anisotropic characteristics caused by the change in the dip angle. Compared with the existing physical model test results, it is determined that the strength of the specimen is positively correlated with the addition amount of rock-like material and the loading rate, and negatively correlated with the water consumption. Full article
(This article belongs to the Section Engineering and Materials)
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Figure 1

Figure 1
<p>Pictures of CJRM.</p>
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<p>Irregular polygon Voronoi diagrams.</p>
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<p>Normalized area and side length distribution of polygons.</p>
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<p>Specimen fabrication process.</p>
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<p>ICJRM specimens with different joint dip angles.</p>
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<p>Uniaxial compression test system and specimen loading diagram.</p>
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<p>Stress–strain curves of CJRM specimens.</p>
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<p>Stress–strain curves of CJRM specimens.</p>
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<p>The influence of the irregularity coefficient and the inclination angle on peak stress.</p>
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<p>Failure modes of RCJRM specimens with different dip angles.</p>
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<p>Failure modes of ICJRM specimens with different dip angles.</p>
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<p>Effect of the irregularity coefficient on the peak stress.</p>
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<p>Schematic diagram of the value-taking methods for the specimen deformation modulus.</p>
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<p>Effect of the dip angle on the deformation modulus.</p>
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<p>Effect of the irregularity coefficient on the deformation modulus.</p>
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<p>Specimen cracking evolution.</p>
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<p>Effect of the irregularity coefficient on the anisotropy ratio coefficient.</p>
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<p>Effect of the irregularity coefficient on the area of the anisotropy region. (<b>a</b>) Area of the anisotropy region when the irregularity coefficient was 0.1 (<math display="inline"><semantics> <mrow> <msub> <mi>χ</mi> <mrow> <mn>0.1</mn> </mrow> </msub> </mrow> </semantics></math>); (<b>b</b>) Areas of the anisotropy regions when the irregularity coefficients were 0.3 (<math display="inline"><semantics> <mrow> <msub> <mi>χ</mi> <mrow> <mn>0.3</mn> </mrow> </msub> </mrow> </semantics></math>), 0.5 (<math display="inline"><semantics> <mrow> <msub> <mi>χ</mi> <mrow> <mn>0.5</mn> </mrow> </msub> </mrow> </semantics></math>), and 0.7 (<math display="inline"><semantics> <mrow> <msub> <mi>χ</mi> <mrow> <mn>0.7</mn> </mrow> </msub> </mrow> </semantics></math>).</p>
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<p>Summary of the anisotropy index values. It is compared with the data in the references [<a href="#B11-symmetry-16-01380" class="html-bibr">11</a>,<a href="#B22-symmetry-16-01380" class="html-bibr">22</a>,<a href="#B24-symmetry-16-01380" class="html-bibr">24</a>,<a href="#B34-symmetry-16-01380" class="html-bibr">34</a>,<a href="#B37-symmetry-16-01380" class="html-bibr">37</a>,<a href="#B38-symmetry-16-01380" class="html-bibr">38</a>].</p>
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<p>Peak stress fitting curves.</p>
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<p>Comparison between the fitted values and the test values under the optimum fitting condition.</p>
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<p>MAPE values of the simplified fitting functions.</p>
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<p>Comparison between the fitted values and the test values under the simplified fitting condition.</p>
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<p>Comparison between the fitted values obtained by two fitting methods and test values.</p>
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31 pages, 18130 KiB  
Article
Research on Cattle Behavior Recognition and Multi-Object Tracking Algorithm Based on YOLO-BoT
by Lei Tong, Jiandong Fang, Xiuling Wang and Yudong Zhao
Animals 2024, 14(20), 2993; https://doi.org/10.3390/ani14202993 (registering DOI) - 17 Oct 2024
Abstract
In smart ranch management, cattle behavior recognition and tracking play a crucial role in evaluating animal welfare. To address the issues of missed and false detections caused by inter-cow occlusions and infrastructure obstructions in the barn environment, this paper proposes a multi-object tracking [...] Read more.
In smart ranch management, cattle behavior recognition and tracking play a crucial role in evaluating animal welfare. To address the issues of missed and false detections caused by inter-cow occlusions and infrastructure obstructions in the barn environment, this paper proposes a multi-object tracking method called YOLO-BoT. Built upon YOLOv8, the method first integrates dynamic convolution (DyConv) to enable adaptive weight adjustments, enhancing detection accuracy in complex environments. The C2f-iRMB structure is then employed to improve feature extraction efficiency, ensuring the capture of essential features even under occlusions or lighting variations. Additionally, the Adown downsampling module is incorporated to strengthen multi-scale information fusion, and a dynamic head (DyHead) is used to improve the robustness of detection boxes, ensuring precise identification of rapidly changing target positions. To further enhance tracking performance, DIoU distance calculation, confidence-based bounding box reclassification, and a virtual trajectory update mechanism are introduced, ensuring accurate matching under occlusion and minimizing identity switches. Experimental results demonstrate that YOLO-BoT achieves a mean average precision (mAP) of 91.7% in cattle detection, with precision and recall increased by 4.4% and 1%, respectively. Moreover, the proposed method improves higher order tracking accuracy (HOTA), multi-object tracking accuracy (MOTA), multi-object tracking precision (MOTP), and IDF1 by 4.4%, 7%, 1.7%, and 4.3%, respectively, while reducing the identity switch rate (IDS) by 30.9%. The tracker operates in real-time at an average speed of 31.2 fps, significantly enhancing multi-object tracking performance in complex scenarios and providing strong support for long-term behavior analysis and contactless automated monitoring. Full article
(This article belongs to the Section Cattle)
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Figure 1

Figure 1
<p>Schematic diagram of the cowshed. Camera 1, positioned near the entrance of the barn, is responsible for collecting behavioral data of the cattle in the blue area. Camera 2, located farther from the entrance, is responsible for collecting behavioral data of the cattle in the red area.</p>
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<p>Examples of cattle data in different activity areas: (<b>a</b>) morning scene, (<b>b</b>) well-lit environment, (<b>c</b>) light interference, (<b>d</b>) night scene, (<b>e</b>) outdoor activity area, and (<b>f</b>) indoor activity area. The time in the top-left corner of the image represents the capture time of the data.</p>
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<p>Analysis of the cattle behavior dataset: (<b>a</b>) analysis of cattle behavior labels, and (<b>b</b>) distribution of cattle count in each image.</p>
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<p>iRMB structure and C2f-iRMB structure.</p>
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<p>ADown downsampling structure.</p>
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<p>DyHead structure.</p>
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<p>Dynamic convolution. The “*” represents element-wise multiplication of each convolution output with its attention weight.</p>
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<p>The improved YOLOv8n network architecture.</p>
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<p>Flowchart for multi-object tracking of cattle.</p>
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<p>Schematic representation of the tracking process leading to object loss due to occlusion: The red solid line denotes the detection frame, while the yellow dashed line represents the predicted frame.</p>
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<p>Ablation experiment results.</p>
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<p>Comparison of algorithm improved cattle instance detection. In scenario 1, standing cattle are mistakenly detected as walking; in scenario 2, some behavioral features of lying cattle are missed and walking behavior is repeatedly detected; and in scenario 3, some features of walking behavior are missed.</p>
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<p>Variation curve of re-identification model accuracy.</p>
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<p>Comparison of the improved results of replacing DIoU, (<b>a</b>,<b>c</b>) denote the tracking results of the original algorithm, and (<b>b</b>,<b>d</b>) denote the tracking results of the improved algorithm. The green circle indicates the part of the target extending beyond the detection box, while the red circle indicates the detection box containing extra background information.</p>
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<p>Comparison between before and after the tracking algorithm improvement at frame 50, frame 652, and frame 916, respectively. The white dotted line in the image indicates the untracked object.</p>
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<p>Comparison between before and after the tracking algorithm improvement at frame 22, frame 915, and frame 1504, respectively. The white dotted line in the image indicates the untracked object.</p>
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<p>Performance comparison of tracking algorithms.</p>
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<p>Tracking results for multiple tracking algorithms. White dashed lines in the image indicate untracked objects, while red dashed lines indicate incorrectly tracked objects. The time in the top-left corner of the image represents the capture time of the data.</p>
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<p>Behavioral duration data from the herd are displayed in one minute, focusing on the incidence of the behavior (<b>a</b>) and the number of individual cattle (<b>b</b>). Expanded to the entire 10 min video (<b>c</b>) to fully demonstrate behavioral changes in the herd over time.</p>
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<p>Time series statistics for each cattle over a one-minute period. Four cattle with both active and quiet behavior were specifically chosen to demonstrate these variations. The numbers 2, 4, 7, and 10 indicate the scaling of the selected cattle IDS assigned by the model in the initial frame.</p>
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11 pages, 251 KiB  
Article
Insect Meal as a Dietary Protein Source for Pheasant Quails: Performance, Carcass Traits, Amino Acid Profile and Mineral Contents in Muscles
by Marian Flis, Piotr Czyżowski, Grzegorz Rytlewski and Eugeniusz R. Grela
Animals 2024, 14(20), 2992; https://doi.org/10.3390/ani14202992 (registering DOI) - 17 Oct 2024
Abstract
The aim of the study was to determine the effects of replacing soybean meal with insect meal on the body weight and the chemical composition of selected muscle groups of common pheasant females and males, including the mineral composition and the amino acid [...] Read more.
The aim of the study was to determine the effects of replacing soybean meal with insect meal on the body weight and the chemical composition of selected muscle groups of common pheasant females and males, including the mineral composition and the amino acid profile of the thigh and breast muscles. The study was conducted on three feeding groups, namely one control and two experimental groups. In the control group, plant feed components were used, which are commonly used to feed pheasants in confined breeding facilities. In the experimental groups, 100 g (group II) and 200 g (group III) portions of insect meal were introduced instead of the plant-protein components. The experiment used a preparation of insect larvae (Hermetia illucens) containing approximately 52% crude protein. The pheasant diet supplementation applied contributed to an increase in the proportion of muscles in the carcasses, with the highest effectiveness obtained for a 20% addition of insect meal. Lower and significant differences were noted in the feed conversion by birds from the experimental groups, as compared to the control group. The chemical composition of the birds’ muscles also changed. The experimental groups exhibited higher protein and fat contents and a lower water content. No significant changes in the amino acid profile or the mineral composition of the muscles were noted. The few exceptions concerned the methionine levels in both muscle groups and the isoleucine levels in the breast muscles. In most cases, the mineral composition did not vary significantly (p < 0.05). When supplementing the diet of breeding pheasants for improving meatiness, a 20% addition of insect meal is recommended, which affects the production effect of this trait while reducing feed consumption and maintaining the fatty acid profile. Full article
21 pages, 5379 KiB  
Article
Artificial Neural Network Modeling of the Removal of Methylene Blue Dye Using Magnetic Clays: An Environmentally Friendly Approach
by Asude Ates, Hülya Demirel, Esra Altintig, Dilay Bozdag, Yasin Usta and Tijen Over Ozçelik
Processes 2024, 12(10), 2262; https://doi.org/10.3390/pr12102262 (registering DOI) - 17 Oct 2024
Abstract
In this study, the effectiveness of Fe3O4-based clay as a cost-effective material for removing methylene blue (MB) dye from aqueous solutions was evaluated. The structural properties of the clay and Fe3O4-based clay were analyzed using [...] Read more.
In this study, the effectiveness of Fe3O4-based clay as a cost-effective material for removing methylene blue (MB) dye from aqueous solutions was evaluated. The structural properties of the clay and Fe3O4-based clay were analyzed using SEM, XRF, BET, XRD, FTIR, and TGA techniques. In this research, the effects of various aspects, such as adsorbent amount, contact time, solution pH, adsorption temperature, and initial dye concentration, on the adsorption of Fe3O4-based clay are investigated. The experiments aimed at understanding the adsorption mechanism of Fe3O4-based clay have shown that the adsorption kinetics are accurately described by the pseudo-second order kinetic model, while the equilibrium data are well represented by the Langmuir isotherm model. The maximum adsorption capacity (qm) was calculated as 52.63 mg/g at 25 °C, 53.48 mg/g at 30 °C, and 54.64 mg/g at 35 °C. All variables affecting the MB adsorption process were systematically optimized in a controlled experimental framework. The effectiveness of the artificial neural network (ANN) model was refined by modifying variables such as the quantity of neurons in the latent layer, the number of inputs, and the learning rate. The model’s accuracy was assessed using the mean absolute percentage error (MAPE) for the removal and adsorption percentage output parameters. The coefficient of determination (R2) values for the dyestuff training, validation, and test sets were found to be 99.40%, 92.25%, and 96.30%, respectively. The ANN model demonstrated a mean squared error (MSE) of 0.614565 for the training data. For the validation dataset, the model recorded MSE values of 0.99406 for the training data, 0.92255 for the validation set, and 0.96302 for the test data. In conclusion, the examined Fe3O4-based clays offer potential as effective and cost-efficient adsorbents for purifying water containing MB dye in various industrial settings. Full article
(This article belongs to the Section Environmental and Green Processes)
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Figure 1

Figure 1
<p>Explicit formula of MB dyestuff.</p>
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<p>SEM images: (<b>a</b>) clay, (<b>b</b>) C-Fe<sub>3</sub>O<sub>4</sub> before adsorption, and (<b>c</b>) C-Fe<sub>3</sub>O<sub>4</sub> after adsorption.</p>
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<p>TGA-DTA analysis data: (<b>a</b>) raw clay and (<b>b</b>) C-Fe<sub>3</sub>O<sub>4</sub>.</p>
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<p>(<b>a</b>) Clay (<b>b</b>) C-Fe<sub>3</sub>O<sub>4</sub> (<b>c</b>) X-ray diffraction image of C-Fe<sub>3</sub>O<sub>4</sub> after adsorption.</p>
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<p>(<b>a</b>) Clay (<b>b</b>) before adsorption C-Fe<sub>3</sub>O<sub>4</sub> (<b>c</b>) C-Fe<sub>3</sub>O<sub>4</sub> FTIR spectrum after adsorption.</p>
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<p>ANN model.</p>
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<p>(<b>a</b>) Influence of initial pH on C-Fe<sub>3</sub>O<sub>4</sub> adsorption (MB concentrations of 50, 100, and 200 mg/L; adsorbent dosage of 0.1 g/L; the temperature at 25 °C; and adsorption duration of 60 min). (<b>b</b>) The effect of contact time on C-Fe<sub>3</sub>O<sub>4</sub> adsorption (MB concentration: 50, 100, and 200 mg/L; adsorbent amount: 0.1 g/L; temperature: 25 °C). (<b>c</b>) The impact of adsorbent quantity on C-Fe<sub>3</sub>O<sub>4</sub> adsorption (MB concentration, 50, 100, and 200 mg/L; contact time, 60 min; temperature, 25 °C).</p>
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<p>(<b>a</b>) Artificial neural network with a 5-15-1 structure, (<b>b</b>) validation performance, and (<b>c</b>) training parameters. (<b>d</b>) Comparison of percent removal estimation output with actual output, (<b>e</b>) histogram graph, and (<b>f)</b> regression plots.</p>
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<p>(<b>a</b>) Artificial neural network with a 5-15-1 structure, (<b>b</b>) validation performance, and (<b>c</b>) training parameters. (<b>d</b>) Comparison of percent removal estimation output with actual output, (<b>e</b>) histogram graph, and (<b>f)</b> regression plots.</p>
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<p>Langmuir isotherm model of C-Fe<sub>3</sub>O<sub>4</sub> (<b>a</b>): 25 °C, (<b>b</b>): 30 °C, (<b>c</b>): 35 °C.</p>
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<p>Freundlich isotherm model of K-Fe<sub>3</sub>O<sub>4</sub> (<b>a</b>): 25 °C, (<b>b</b>): 30 °C, (<b>c</b>): 35 °C.</p>
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<p>(<b>a</b>) Pseudo-first order kinetics of the adsorption of 25 °C MB with C-Fe<sub>3</sub>O<sub>4</sub>; (<b>b</b>) pseudo-second order kinetics.</p>
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<p>(<b>a</b>) Temperature effect on the adsorption of MB on C-Fe<sub>3</sub>O<sub>4</sub> (contact time: 60 min, pH: 7, adsorbent amount: 0.5 g 100 mL<sup>−1</sup>); (<b>b</b>) Van’t Hoff plot for the adsorption of MB dyestuff onto C-Fe<sub>3</sub>O<sub>4</sub> (adsorbent amount 0.2 g/L, pH 7, solution volume 100 mL and stirring speed 250 rpm).</p>
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<p>MB on C-Fe<sub>3</sub>O<sub>4</sub> after six recovery cycles.</p>
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21 pages, 3450 KiB  
Article
Field Trial with Vaccine Candidates Against Bovine Tuberculosis Among Likely Infected Cattle in a Natural Transmission Setting
by Ximena Ferrara Muñiz, Elizabeth García, Federico Carlos Blanco, Sergio Garbaccio, Carlos Garro, Martín Zumárraga, Odir Dellagostin, Marcos Trangoni, María Jimena Marfil, Maria Verónica Bianco, Alejandro Abdala, Javier Revelli, Maria Bergamasco, Adriana Soutullo, Rocío Marini, Rosana Valeria Rocha, Amorina Sánchez, Fabiana Bigi, Ana María Canal, María Emilia Eirin and Angel Adrián Cataldiadd Show full author list remove Hide full author list
Vaccines 2024, 12(10), 1173; https://doi.org/10.3390/vaccines12101173 (registering DOI) - 17 Oct 2024
Abstract
Background/Objectives: Vaccines may improve the control and eradication of bovine tuberculosis. However, the evaluation of experimental candidates requires the assessment of the protection, excretion, transmission and biosafety. A natural transmission trial among likely infected animals was conducted. Methods: Seventy-four male heifers [...] Read more.
Background/Objectives: Vaccines may improve the control and eradication of bovine tuberculosis. However, the evaluation of experimental candidates requires the assessment of the protection, excretion, transmission and biosafety. A natural transmission trial among likely infected animals was conducted. Methods: Seventy-four male heifers were randomly distributed (five groups) and vaccinated subcutaneously with attenuated strains (M. bovis Δmce2 or M. bovis Δmce2-phoP), a recombinant M. bovis BCG Pasteur (BCGr) or M. bovis BCG Pasteur. Then, they cohoused with a naturally infected bTB cohort under field conditions exposed to the infection. Results: A 23% of transmission of wild-type strains was confirmed (non-vaccinated group). Strikingly, first vaccination did not induce immune response (caudal fold test and IFN-gamma release assay). However, after 74 days of exposure to bTB, animals were re-vaccinated. Although their sensitization increased throughout the trial, the vaccines did not confer significant protection, when compared to the non-vaccinated group, as demonstrated by pathology progression of lesions and confirmatory tools. Besides, the likelihood of acquiring the infection was similar in all groups compared to the non-vaccinated group (p > 0.076). Respiratory and digestive excretion of viable vaccine candidates was undetectable. To note, the group vaccinated with M. bovis Δmce2-phoP exhibited the highest proportion of animals without macroscopic lesions, compared to the one vaccinated with BCG, although this was not statistically supported. Conclusions: This highlights that further evaluation of these vaccines would not guarantee better protection. The limitations detected during the trial are discussed regarding the transmission rate of M. bovis wild-type, the imperfect test for studying sensitization, the need for a DIVA diagnosis and management conditions of the trials performed under routine husbandry conditions. Re-vaccination of likely infected bovines did not highlight a conclusive result, even suggesting a detrimental effect on those vaccinated with M. bovis BCG. Full article
(This article belongs to the Section Veterinary Vaccines)
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Figure 1

Figure 1
<p>Timeline of the trial. A schematic timeline illustrating the most relevant intervention and sampling points, types of samples and techniques used to monitor the animals prior to the necropsy. mpv: months pre-vaccination. dpv: days post-vaccination. dprv: days post re-vaccination. TST: tuberculin skin test, IGRA: Interferon-Gamma release assay, MAP: <span class="html-italic">Mycobacterium avium</span> subsp. <span class="html-italic">Paratuberculosis</span>, ELISA: Enzyme-Linked Immunosorbent assay, CFT: caudal fold test, PCR: Polymerase Chain Reaction, bTB: bovine tuberculosis.</p>
Full article ">Figure 2
<p>(<b>A</b>). Prevalence of animals positive to the caudal fold test (CFT) in each group at the different sampling times. (<b>B</b>). Percentage of positive animals to the interferon-gamma release assay (IGRA). Kruskal–Wallis test and Dunn’s post test. * Prevalence that differed significantly between the studied groups, <span class="html-italic">p</span> &lt; 0.05. The dotted vertical line and gray arrow indicate the day of the re-vaccination. (<b>C</b>,<b>D</b>). Incidence of positivity for both CFT and IGRA, respectively, represented by the Kaplan–Meier analysis. TST: Tuberculin skin test. Dpv: days post vaccination. Dprv: days post re-vaccination. IFNg: Interferon gamma.</p>
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<p>Scatter plot showing the OD readouts for Interferon Gamma Release Assay (IGRA) detected in cattle from the different groups under study at 75 days post vaccination (dpv), 42, 144 and 249 days post re-vaccination (dprv) when stimulated with PPDA (<b>A</b>), PPDB (<b>B</b>) and FP (<b>C</b>). The dotted horizontal line represents the cut-off of 0.1, above which is considered a positive OD value and below which is negative. Kruskal–Wallis Test and Dunn’s post test. *, <span class="html-italic">p</span> &lt; 0.05; **, <span class="html-italic">p</span> &lt; 0.1; *** <span class="html-italic">p</span> &lt; 0.001.</p>
Full article ">Figure 3 Cont.
<p>Scatter plot showing the OD readouts for Interferon Gamma Release Assay (IGRA) detected in cattle from the different groups under study at 75 days post vaccination (dpv), 42, 144 and 249 days post re-vaccination (dprv) when stimulated with PPDA (<b>A</b>), PPDB (<b>B</b>) and FP (<b>C</b>). The dotted horizontal line represents the cut-off of 0.1, above which is considered a positive OD value and below which is negative. Kruskal–Wallis Test and Dunn’s post test. *, <span class="html-italic">p</span> &lt; 0.05; **, <span class="html-italic">p</span> &lt; 0.1; *** <span class="html-italic">p</span> &lt; 0.001.</p>
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<p>(<b>A</b>). Macroscopic lesion score. (<b>B</b>). Microscopic lesion score of each animal from the different groups.</p>
Full article ">
17 pages, 8979 KiB  
Article
Action Recognition in Videos through a Transfer-Learning-Based Technique
by Elizabeth López-Lozada, Humberto Sossa, Elsa Rubio-Espino and Jesús Yaljá Montiel-Pérez
Mathematics 2024, 12(20), 3245; https://doi.org/10.3390/math12203245 (registering DOI) - 17 Oct 2024
Abstract
In computer vision, human action recognition is a hot topic, popularized by the development of deep learning. Deep learning models typically accept video input without prior processing and train them to achieve recognition. However, conducting preliminary motion analysis can be beneficial in directing [...] Read more.
In computer vision, human action recognition is a hot topic, popularized by the development of deep learning. Deep learning models typically accept video input without prior processing and train them to achieve recognition. However, conducting preliminary motion analysis can be beneficial in directing the model training to prioritize the motion of individuals with less priority for the environment in which the action occurs. This paper puts forth a novel methodology for human action recognition based on motion information that employs transfer-learning techniques. The proposed method comprises four stages: (1) human detection and tracking, (2) motion estimation, (3) feature extraction, and (4) action recognition using a two-stream model. In order to develop this work, a customized dataset was utilized, comprising videos of diverse actions (e.g., walking, running, cycling, drinking, and falling) extracted from multiple public sources and websites, including Pexels and MixKit. This realistic and diverse dataset allowed for a comprehensive evaluation of the proposed method, demonstrating its effectiveness in different scenarios and conditions. Furthermore, the performance of seven pre-trained models for feature extraction was evaluated. The models analyzed were Inception-v3, MobileNet-v2, MobileNet-v3-L, VGG-16, VGG-19, Xception, and ConvNeXt-L. The results demonstrated that the ConvNeXt-L model yielded the most optimal outcomes. Furthermore, using pre-trained models for feature extraction facilitated the training process on a personal computer with a single graphics processing unit, achieving an accuracy of 94.9%. The experimental findings and outcomes suggest that integrating motion information enhances action recognition performance. Full article
(This article belongs to the Special Issue Deep Neural Networks: Theory, Algorithms and Applications)
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<p>The proposed method for HAR based on the analysis of motion features.</p>
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<p>Diagram illustrating the operation of the FairMOT algorithm used to track people.</p>
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<p>Diagram depicting the methodology employed by FairMOT for the monitoring of individuals, accompanied by the delineated bounding boxes for the extraction of the subject engaged in the observed actions.</p>
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<p>Diagram illustrating the outcomes of the optical flow and pose estimation processes, as well as the results of integrating the motion features.</p>
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<p>Block diagram that illustrates the proposed feature extraction process for this work.</p>
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<p>Block diagram of the proposed HAR classification model.</p>
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<p>The distribution of the videos in the dataset according to the source from which they were extracted.</p>
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<p>The sample videos obtained from the Pexels, NTU RGB+D, and MixKit websites.</p>
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<p>The distribution of the videos is presented according to the class of membership and source of origin.</p>
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<p>Graph of the loss during training with four classes of the dataset and its respective confusion matrix. (<b>a</b>) Loss. (<b>b</b>) Confusion matrix.</p>
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<p>Graph of the loss during training with five classes of the dataset and its respective confusion matrix. (<b>a</b>) Loss. (<b>b</b>) Confusion matrix.</p>
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20 pages, 962 KiB  
Article
Fast Global and Local Semi-Supervised Learning via Matrix Factorization
by Yuanhua Du, Wenjun Luo, Zezhong Wu and Nan Zhou
Mathematics 2024, 12(20), 3242; https://doi.org/10.3390/math12203242 (registering DOI) - 16 Oct 2024
Abstract
Matrix factorization has demonstrated outstanding performance in machine learning. Recently, graph-based matrix factorization has gained widespread attention. However, graph-based methods are only suitable for handling small amounts of data. This paper proposes a fast semi-supervised learning method using only matrix factorization, which considers [...] Read more.
Matrix factorization has demonstrated outstanding performance in machine learning. Recently, graph-based matrix factorization has gained widespread attention. However, graph-based methods are only suitable for handling small amounts of data. This paper proposes a fast semi-supervised learning method using only matrix factorization, which considers both global and local information. By introducing bipartite graphs into symmetric matrix factorization, the technique can handle large datasets effectively. It is worth noting that by utilizing tag information, the proposed symmetric matrix factorization becomes convex and unconstrained, i.e., the non-convex problem minx(1x2)2 is transformed into a convex problem. This allows it to be optimized quickly using state-of-the-art unconstrained optimization algorithms. The computational complexity of the proposed method is O(nmd), which is much lower than that of the original symmetric matrix factorization, which is O(n2d), and even lower than that of other anchor-based methods, which is O(nmd+m2n+m3), where n represents the number of samples, d represents the number of features, and mn represents the number of anchors. The experimental results on multiple public datasets indicate that the proposed method achieves higher performance in less time. Full article
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<p>Links between samples and anchors, where <math display="inline"><semantics> <msub> <mi>x</mi> <mn>1</mn> </msub> </semantics></math>–<math display="inline"><semantics> <msub> <mi>x</mi> <mn>7</mn> </msub> </semantics></math> represent the seven samples and <math display="inline"><semantics> <msub> <mi>u</mi> <mn>1</mn> </msub> </semantics></math>–<math display="inline"><semantics> <msub> <mi>u</mi> <mn>4</mn> </msub> </semantics></math> represent the four anchors.</p>
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<p>Clustering performance with different labeled samples on (<b>a</b>) COIL20 dataset, (<b>b</b>) YaleB dataset, (<b>c</b>) COIL100 dataset, (<b>d</b>) USPS dataset, (<b>e</b>) MNIST dataset, and (<b>f</b>) Letters dataset.</p>
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<p>Sensitivity of FGLMF on (<b>a</b>) COIL20 dataset, (<b>b</b>) YaleB dataset, (<b>c</b>) COIL100 dataset, (<b>d</b>) USPS dataset, (<b>e</b>) MNIST dataset, and (<b>f</b>) Letters dataset.</p>
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<p>Sensitivity of FGLMF on (<b>a</b>) COIL20 dataset, (<b>b</b>) YaleB dataset, (<b>c</b>) COIL100 dataset, (<b>d</b>) USPS dataset, (<b>e</b>) MNIST dataset, and (<b>f</b>) Letters dataset.</p>
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<p>Accuracy vs. time of FGLMF with different anchors on (<b>a</b>) COIL20 dataset, (<b>b</b>) YaleB dataset, (<b>c</b>) COIL100 dataset, (<b>d</b>) USPS dataset, (<b>e</b>) MNIST dataset, and (<b>f</b>) Letters dataset.</p>
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<p>Accuracy vs. time of FGLMF with different anchors on (<b>a</b>) COIL20 dataset, (<b>b</b>) YaleB dataset, (<b>c</b>) COIL100 dataset, (<b>d</b>) USPS dataset, (<b>e</b>) MNIST dataset, and (<b>f</b>) Letters dataset.</p>
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<p>Bases generated by FGLMF. The first row is COIL20, the second is YaleB, the third is COIL100, the fourth is USPS, the fifth is MNIST, and the sixth is Letters.</p>
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<p>Adjacency matrix on COIL20 dataset: (<b>a</b>) bipartite graph generated by Equation (3); (<b>b</b>) full adjacency matrix generated by bipartite using Equation (6); (<b>c</b>) normalized full adjacency matrix generated by Gaussian kernel.</p>
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<p>Convergence curve on (<b>a</b>) COIL20 dataset, (<b>b</b>) USPS dataset, (<b>c</b>) COIL100 dataset, (<b>d</b>) USPS dataset, (<b>e</b>) MNIST dataset, and (<b>f</b>) Letters dataset.</p>
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58 pages, 950 KiB  
Review
Comprehensive Assessment of the Impact of Green Roofs and Walls on Building Energy Performance: A Scientific Review
by Yara Nasr, Henri El Zakhem, Ameur El Amine Hamami, Makram El Bachawati and Rafik Belarbi
Energies 2024, 17(20), 5160; https://doi.org/10.3390/en17205160 (registering DOI) - 16 Oct 2024
Abstract
Abstract: Sustainability and energy efficiency are now two pivotal goals that society aims towards. Green roofs and facades have gained significant attention in this direction for innovative, sustainable solutions for enhancing building energy performance. With a focus on sustainable urban development and energy-efficient [...] Read more.
Abstract: Sustainability and energy efficiency are now two pivotal goals that society aims towards. Green roofs and facades have gained significant attention in this direction for innovative, sustainable solutions for enhancing building energy performance. With a focus on sustainable urban development and energy-efficient building practices, this study delves into the intricate relationship between these green infrastructure elements and the overall energy dynamics of constructed environments. Furthermore, a range of case studies from diverse geographical locations are presented to provide valuable insights into their practical implications as emerging technologies that contribute to improved insulation, reduced heat transfer, regulating indoor temperatures, and mitigation of urban heat island effects, thus reducing the need for artificial heating and cooling and optimizing overall energy consumption. This comprehensive review serves as a dataset for understanding and highlighting all the research findings of the numerical and experimental investigations invested in the field of greenery systems to encourage their integration, which is crucial for combating climate change and pollution. Previous research is often focused on isolated, short-term, or single-climate analyses of consumption; therefore, by providing an inclusive description of their practical benefits in both temperate and extreme climates, the gap in previous articles is tackled. Full article
(This article belongs to the Section B: Energy and Environment)
12 pages, 249 KiB  
Article
Factors Affecting the Sustainability of Corporates in Polluting Sectors
by Raminta Vaitiekuniene, Kristina Sutiene and Rytis Krusinskas
Sustainability 2024, 16(20), 8970; https://doi.org/10.3390/su16208970 (registering DOI) - 16 Oct 2024
Abstract
Corporate sustainability performance is gaining ever greater importance. The negative impact of climate change is manifested through heavy air, water and soil pollution. Polluting sectors, as the major players, are characterized by large amounts of emissions, waste and consumption of resources, and therefore [...] Read more.
Corporate sustainability performance is gaining ever greater importance. The negative impact of climate change is manifested through heavy air, water and soil pollution. Polluting sectors, as the major players, are characterized by large amounts of emissions, waste and consumption of resources, and therefore have a larger negative impact on the environment. Companies operating in polluting sectors are recognized globally as the main sources of greenhouse gas emissions; thus, their performance is widely debated. Despite their character, such companies strive for higher profitability, better financial performance and operational efficiency. However, higher financial resources create the potential for innovation investments in companies. It is widely accepted that research and experimental development (R&D) expenditures enable new business ideas, models, products, services, and processes. However, while pursuing sustainability targets, financial results could be directed towards sustainability performance. The purpose of this paper is to analyze how the financial and innovation results of companies in polluting sectors interact with sustainability performance scores. For it, we have identified three essential pillars of sustainability: environmental, governance, and social. Using ordinary least squares (OLS) regressions, models were developed for each pillar of sustainability, including corporate financial performance indicators and R&D expenditures. The obtained results provide the insights that a company operating in polluting sector size and turnover significantly interacts with all pillars of sustainability. However, we also found that the corporate debt ratio, earnings ratio, and current liquidity have a significant relation only with environmental and social sustainability indicators. Full article
10 pages, 903 KiB  
Article
The Effect of Pine Wood Thickness on the Freezing and Heating Process in Warm-Air Drying
by Ivan Klement, Tatiana Vilkovská and Peter Vilkovský
Appl. Sci. 2024, 14(20), 9464; https://doi.org/10.3390/app14209464 (registering DOI) - 16 Oct 2024
Abstract
Wood is subject to various environmental conditions during its processing, with temperatures being one of the most relevant to the material’s behaviour. The heating process during drying is crucial for both the final quality of the dried wood and heat consumption. As the [...] Read more.
Wood is subject to various environmental conditions during its processing, with temperatures being one of the most relevant to the material’s behaviour. The heating process during drying is crucial for both the final quality of the dried wood and heat consumption. As the first stage of the drying process, it is essential to achieve adequate overheating in the middle of the thickness without causing damage. The present article focuses on the influence of pine wood thickness on the freezing process and heating during the warm-air drying process. Similarity theory was applied to the theoretical calculation of the time to heat the frozen wood, where Fourier and Biot’s criteria were used. The calculated times were confirmed by experimental measurements. Theoretical calculations of heating time for frozen wood align with measured values for larger thicknesses. For smaller thicknesses (<50 mm), the heating time was shown as unnecessarily long. The results showed that wood thickness significantly affected both freezing and heating processes. Specifically, the thickness of the samples had a notable impact on the heating of frozen samples, only after changing the water gradient in the wood from solid to liquid state. The optimal solution would be if the time and course of heating were regulated according to the actual measured temperature in the centre of the wood. Full article
(This article belongs to the Special Issue Advances in Wood Processing Technology: 2nd Edition)
14 pages, 2925 KiB  
Article
Immobilization and Kinetic Properties of ß-N-Acetylhexosaminidase from Penicillium oxalicum
by Vladimír Štefuca, Mária Bláhová, Helena Hronská and Michal Rosenberg
Catalysts 2024, 14(10), 725; https://doi.org/10.3390/catal14100725 (registering DOI) - 16 Oct 2024
Abstract
The application of immobilized enzymes often plays a key role in successfully implementing an economically feasible biocatalytic process at an industrial scale. Designing an immobilized biocatalyst involves solving several tasks, from the selection of the carrier and immobilization method to the characterization of [...] Read more.
The application of immobilized enzymes often plays a key role in successfully implementing an economically feasible biocatalytic process at an industrial scale. Designing an immobilized biocatalyst involves solving several tasks, from the selection of the carrier and immobilization method to the characterization of the kinetic properties of the immobilized enzyme. In this study, we focused on the kinetic properties of free and immobilized ß-N-acetylhexosaminidase (Hex), a promising enzyme for application in the field of biotechnology, especially for the synthesis of bioactive carbohydrates. Hex was immobilized via covalent binding in methacrylate particles. The effect of immobilizing Hex from Penicillium oxalicum into porous particles on kinetic properties was investigated, and mathematical and experimental modeling showed that the kinetic behavior of the enzyme was significantly influenced by diffusion in the particles. Along with the study on kinetics, a simple method was developed to investigate the reversible inhibition of the immobilized enzyme in a continuous-flow system. The method is suitable for application in cases where a chromogenic substrate is used, and here it was applied to demonstrate the inhibitory effects of N-acetyl-glucosaminyl thiazoline (NAG-thiazoline) and O-(2-Acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenyl carbamate ((Z)-PugNAc) on Hex. Full article
(This article belongs to the Section Biocatalysis)
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<p>Progress curves of enzymatic hydrolysis of 4NPGlcNAc catalyzed by free hexosaminidase. Points correspond to experimental data, and lines represent data calculated from the Michaelis–Menten equation with uncompetitive substrate and non-competitive product inhibition. Initial substrate concentrations (in mmol/dm<sup>3</sup>): (<b>A</b>): 2.0; (<b>B</b>): 1.5; (<b>C</b>): 1.0; (<b>D</b>): 0.5; (<b>E</b>): 0.4; and (<b>F</b>): 0.3.</p>
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<p>The evaluation of reaction kinetics with crushed particles was compared using different models. <b>Left</b> panel: Michaelis–Menten model with uncompetitive substrate inhibition and non-competitive product inhibition; <b>Right</b> panel: Simple Michaelis–Menten kinetics. Initial substrate concentrations (mmol/dm<sup>3</sup>): 0.2 (•); 0.7 (✱); 1.0 (■); 1.5 (▲); and 2.0 (▼).</p>
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<p>Reaction kinetics with intact immobilized enzyme particles. Comparison of experimental data (points) and data calculated from Michaelis–Menten kinetics, including mass transfer effects (solid lines). Initial substrate concentrations (mmol/dm<sup>3</sup>): 0.25 (▲); 0.4 (■); 0.7 (✱); 1.0 (•).</p>
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<p>Influence of the position of the boundary of immobilized Hex on the best RSS obtained by non-linear regression.</p>
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<p>Evolution of substrate concentration profiles in the immobilized Hex particle during the reaction.</p>
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<p>Evolution of substrate concentration profiles in the immobilized Hex particles, assuming particle radii of 50 μm (<b>left</b> panel) and 20 μm (<b>right</b> panel).</p>
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<p>Experimental setup for measuring the kinetics of immobilized Hex with infinite recirculation of the reaction mixture.</p>
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<p>The continuous flow system used for measuring the activity of immobilized Hex.</p>
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19 pages, 1606 KiB  
Article
Rural Road Extraction in Xiong’an New Area of China Based on the RC-MSFNet Network Model
by Nanjie Yang, Weimeng Di, Qingyu Wang, Wansi Liu, Teng Feng and Xiaomin Tian
Sensors 2024, 24(20), 6672; https://doi.org/10.3390/s24206672 - 16 Oct 2024
Abstract
High-resolution remote sensing imagery, reaching meter or sub-meter levels, provides essential data for extracting and identifying road information. However, rural roads are often narrow, elongated, and have blurred boundaries, with textures that resemble surrounding environments such as construction sites, vegetation, and farmland. These [...] Read more.
High-resolution remote sensing imagery, reaching meter or sub-meter levels, provides essential data for extracting and identifying road information. However, rural roads are often narrow, elongated, and have blurred boundaries, with textures that resemble surrounding environments such as construction sites, vegetation, and farmland. These features often lead to incomplete extraction and low extraction accuracy of rural roads. To address these challenges, this study introduces the RC-MSFNet model, based on the U-Net architecture, to enhance rural road extraction performance. The RC-MSFNet model mitigates the vanishing gradient problem in deep networks by incorporating residual neural networks in the downsampling stage. In the upsampling stage, a connectivity attention mechanism is added after dual convolution layers to improve the model’s ability to capture road completeness and connectivity. Additionally, the bottleneck section replaces the traditional dual convolution layers with a multi-scale fusion atrous convolution module to capture features at various scales. The study focuses on rural roads in the Xiong’an New Area, China, using high-resolution imagery from China’s Gaofen-2 satellite to construct the XARoads rural road dataset. Roads were extracted from the XARoads dataset and DeepGlobe public dataset using the RC-MSFNet model and compared with some models such as U-Net, FCN, SegNet, DeeplabV3+, R-Net, and RC-Net. Experimental results showed that: (1) The proposed method achieved precision (P), intersection over union (IOU), and completeness (COM) scores of 0.8350, 0.6523, and 0.7489, respectively, for rural road extraction in Xiong’an New Area, representing precision improvements of 3.8%, 6.78%, 7.85%, 2.14%, 0.58%, and 2.53% over U-Net, FCN, SegNet, DeeplabV3+, R-Net, and RC-Net. (2) The method excelled at extracting narrow roads and muddy roads with unclear boundaries, with fewer instances of omission or false extraction, demonstrating advantages in complex rural terrain and areas with indistinct road boundaries. Accurate rural road extraction can provide valuable reference data for urban development and planning in the Xiong’an New Area. Full article
(This article belongs to the Section Sensor Networks)
17 pages, 7777 KiB  
Article
The Nephroprotective Effect of Punica granatum Peel Extract on LPS-Induced Acute Kidney Injury
by Sena Sahin Aktura, Kazim Sahin, Levent Tumkaya, Tolga Mercantepe, Atilla Topcu, Esra Pinarbas and Zihni Acar Yazici
Life 2024, 14(10), 1316; https://doi.org/10.3390/life14101316 - 16 Oct 2024
Abstract
Sepsis is an exaggerated immune response resulting from systemic inflammation, which can damage tissues and organs. Acute kidney injury has been detected in at least one-third of patients with sepsis. Sepsis-associated acute kidney injury increases the risk of a secondary infection. Rapid diagnosis [...] Read more.
Sepsis is an exaggerated immune response resulting from systemic inflammation, which can damage tissues and organs. Acute kidney injury has been detected in at least one-third of patients with sepsis. Sepsis-associated acute kidney injury increases the risk of a secondary infection. Rapid diagnosis and appropriate initiation of antibiotics can significantly reduce mortality and morbidity. However, microorganisms are known to develop resistance to antibiotics. Estimations indicate that the annual casualties caused by microbial resistance will surpass cancer fatalities by 2050. The prevalence of bacterial infections and their growing antibiotic resistance has brought immediate attention to the search for novel treatments. Plant-derived supplements contain numerous bioactive components with therapeutic potential against a variety of conditions, including infections. Punica granatum peel is rich in phenolic compounds. The purpose of this study was to determine the anti-inflammatory and anti-bacterial properties of P. granatum peel extract (PGPE) on lipopolysaccharide (LPS)-induced acute kidney injury. Experimental groups were Control, LPS (10 mg/kg LPS, intraperitoneally), PGPE100, and PGPE300 (100 and 300 mg/mL PGPE via oral gavage, respectively, for 7 days). According to biochemical results, serum blood urea nitrogen (BUN), creatinine (Cr) and C-reactive protein (CRP), kidney tissue thiobarbituric acid reactive substances (TBARS), and reduced glutathione (GSH) levels significantly decreased in the PGPE groups compared to the LPS group. Histopathological and immunohistochemical findings revealed that toll-like receptor 4 (TLR4) level and nuclear factor kappa B (NF-κB) expression increased in the LPS group compared to the Control group. In addition, the anti-Gram-negative activity showed a dose-dependent effect on Acinetobacter baumannii, Escherichia coli, and Pseudomonas aeruginosa with the agar well diffusion method and the minimal inhibitory concentration (MIC). The MIC value was remarkable, especially on A. baumannii. We conclude that PGPE has the potential to generate desirable anti-bacterial and anti-inflammatory effects on LPS-induced acute kidney injury in rats. Full article
(This article belongs to the Special Issue Bioactive Natural Compounds: Therapeutic Insights and Applications)
17 pages, 4527 KiB  
Article
Performance of Cobalt-Doped C3N5 Electrocatalysis Nitrate in Ammonia Production
by Boyu Liang, Yueqi Wu, Jing Han, Wenqiang Deng, Xinyao Zhang, Runrun Li, Yan Hong, Jie Du, Lichun Fu and Runhua Liao
Coatings 2024, 14(10), 1327; https://doi.org/10.3390/coatings14101327 - 16 Oct 2024
Abstract
In this experiment, C3N5 was synthesized by pyrolysis of 3-amino-1,2,4 triazole material, and then 1% Co-C3N5, 3% Co-C3N5, 5% Co-C3N5, 7% Co-C3N5, and 9% [...] Read more.
In this experiment, C3N5 was synthesized by pyrolysis of 3-amino-1,2,4 triazole material, and then 1% Co-C3N5, 3% Co-C3N5, 5% Co-C3N5, 7% Co-C3N5, and 9% Co-C3N5 were synthesized by varying the mass ratio of cobalt chloride to C3N5 by stirring and ultrasonic shaking. SEM, XPS, and XRD tests were performed on the synthesized materials. The experimental results showed that Co atoms were successfully doped into C3N5. The electrocatalytic reduction experiments were performed to evaluate their NH3 yields and electrochemical properties. The results showed that the ammonia yield obtained by the electrolysis of the 9% Co-C3N5 catalyst as the working electrode in a mixed electrolytic solution of 0.1 mol/L KNO3 and 0.1 mol/L KOH for 1 h at a potential of −1.0 V vs. RHE was 0.633 ± 0.02 mmol∙h−1∙mgcat−1, and the Faraday efficiency was 65.98 ± 2.14%; under the same experimental conditions, the ammonia production rate and Faraday efficiency of the C3N5 catalyst were 0.049 mmol∙h−1∙mgcat−1 and 16.41%, respectively, and the ammonia production rate of the C3N5 catalyst was nearly 13-fold worse than the 9% Co-C3N5, which suggests that Co can improve the Faraday efficiency and ammonia yield of the electrocatalytic reduction of NO3. This is due to the strong synergistic effect between the cobalt and C3N5 components, with C3N5 providing abundant and homogeneous sites for nitrogen coordination and the Co-N species present in the material being highly efficient active sites. The slight change in current density after five trials of 9% Co-C3N5 and the decrease in ammonia yield by about 12% in five repetitions of the experiment indicate that 9% Co-C3N5 can be recycled and work stably in electrocatalytic reactions and has good application prospects. Full article
(This article belongs to the Special Issue Advanced Materials for Electrocatalysis and Energy Storage)
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<p>NH<sub>4</sub><sup>+</sup> standard mass concentration profile.</p>
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<p>XRD diffractograms of C<sub>3</sub>N<sub>5</sub> and Co-C<sub>3</sub>N<sub>5</sub> for each doping ratio.</p>
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<p>(<b>a</b>) FT-IR comparison between C<sub>3</sub>N<sub>5</sub> and composites; (<b>b</b>) T-IR magnification of both 1% Co-C<sub>3</sub>N<sub>5</sub> and 9% Co-C<sub>3</sub>N<sub>5.</sub></p>
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<p>(<b>a</b>) XPS full spectrum of C<sub>3</sub>N<sub>5</sub>, 1% Co-C<sub>3</sub>N<sub>5</sub> and 3% Co-C<sub>3</sub>N<sub>5</sub>; (<b>b</b>) XPS full spectrum of 5% Co-C<sub>3</sub>N<sub>5</sub>, 7% Co-C<sub>3</sub>N<sub>5</sub> and 9% Co-C<sub>3</sub>N<sub>5</sub>; (<b>c</b>) C1s spectrum of 1% Co-C<sub>3</sub>N<sub>5</sub>, 3% Co-C<sub>3</sub>N<sub>5</sub> and 9% Co-C<sub>3</sub>N<sub>5</sub>; (<b>d</b>) N1s spectrum of 1% Co-C<sub>3</sub>N<sub>5</sub>, 3% Co-C<sub>3</sub>N<sub>5</sub> and 9% Co-C<sub>3</sub>N<sub>5</sub>; (<b>e</b>) Co2p spectrum of 1% Co-C<sub>3</sub>N<sub>5</sub>, 3% Co-C<sub>3</sub>N<sub>5</sub> and 9% Co-C<sub>3</sub>N<sub>5.</sub></p>
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<p>(<b>a</b>) Scanning electron microscope image of C<sub>3</sub>N<sub>5</sub>; (<b>b</b>) scanning electron microscope image of Co-C<sub>3</sub>N<sub>5</sub>; (<b>c</b>) copper element distribution of Co-C<sub>3</sub>N<sub>5.</sub></p>
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<p>(<b>a</b>) Scanning electron microscope image of C<sub>3</sub>N<sub>5</sub>; (<b>b</b>) scanning electron microscope image of Co-C<sub>3</sub>N<sub>5</sub>; (<b>c</b>) copper element distribution of Co-C<sub>3</sub>N<sub>5.</sub></p>
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<p>9% Co-C<sub>3</sub>N<sub>5</sub> energy-dispersive spectrum.</p>
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<p>LSV plot of catalysts possessing electrocatalytic nitrate activity in electrolytes.</p>
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<p>(<b>a</b>) Plot of NH<sub>3</sub> yield rate and Faraday efficiency of catalysts at −0.5~−1.0V vs. RHE potentials; (<b>b</b>) comparison of NH<sub>3</sub> yield rate of catalysts; (<b>c</b>) comparison of Faraday efficiency of catalysts; (<b>d</b>) NH<sub>3</sub> yield rate of catalysts at −0.8 V vs. RHE potentials.</p>
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<p>(<b>a</b>) Plot of NH<sub>3</sub> yield rate and Faraday efficiency of 9% Co-C<sub>3</sub>N<sub>5</sub> at −1.0 V vs. RHE potential cycling test repeated 5 times; (<b>b</b>) Plot of LSV of 9% Co-C<sub>3</sub>N<sub>5</sub> at −1.0 V vs. RHE potential test repeated 5 times.</p>
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<p>(<b>a</b>) Comparison of LSV before and after 12 h of electrolysis of 9% Co-C<sub>3</sub>N<sub>5</sub> at −1.0 V vs. RHE potential; (<b>b</b>) Comparison of NH<sub>3</sub> yield rate and Faraday efficiency before and after 12 h of electrolysis of 9% Co-C<sub>3</sub>N<sub>5</sub> at −1.0 V vs. RHE potential.</p>
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19 pages, 12975 KiB  
Article
Enhancing Real-Time Visual SLAM with Distant Landmarks in Large-Scale Environments
by Hexuan Dou, Xinyang Zhao, Bo Liu, Yinghao Jia, Guoqing Wang and Changhong Wang
Drones 2024, 8(10), 586; https://doi.org/10.3390/drones8100586 - 16 Oct 2024
Abstract
The efficacy of visual Simultaneous Localization and Mapping (SLAM) diminishes in large-scale environments due to challenges in identifying distant landmarks, leading to a limited perception range and trajectory drift. This paper presents a practical method to enhance the accuracy of feature-based real-time visual [...] Read more.
The efficacy of visual Simultaneous Localization and Mapping (SLAM) diminishes in large-scale environments due to challenges in identifying distant landmarks, leading to a limited perception range and trajectory drift. This paper presents a practical method to enhance the accuracy of feature-based real-time visual SLAM for compact unmanned vehicles by constructing distant map points. By tracking consecutive image features across multiple frames, remote map points are generated with sufficient parallax angles, extending the mapping scope to the theoretical maximum range. Observations of these landmarks from preceding keyframes are supplemented accordingly, improving back-end optimization and, consequently, localization accuracy. The effectiveness of this approach is ensured by the introduction of the virtual map point, a proposed data structure that links relational features to an imaginary map point, thereby maintaining the constrained size of local optimization during triangulation. Based on the ORB-SLAM3 code, a SLAM system incorporating the proposed method is implemented and tested. Experimental results on drone and vehicle datasets demonstrate that the proposed method outperforms ORB-SLAM3 in both accuracy and perception range with negligible additional processing time, thus preserving real-time performance. Field tests using a UGV further validate the efficacy of the proposed method. Full article
(This article belongs to the Section Drone Design and Development)
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Figure 1
<p>Triangulation of a spatial point. The uncertainty of triangulation is represented by the gray area. The case illustrated on the right has a shorter baseline <span class="html-italic">b</span> and/or a smaller parallax angle <math display="inline"><semantics> <mi>θ</mi> </semantics></math>, resulting in greater uncertainty in the localization of <math display="inline"><semantics> <mi mathvariant="normal">P</mi> </semantics></math>.</p>
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<p>Extending the perception range to the maximum by utilizing features from keyframes beyond the local mapping range.</p>
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<p>The relationship between the perception ranges of the camera and the structure of the matrix <math display="inline"><semantics> <msub> <mi mathvariant="bold-italic">H</mi> <mrow> <mi>C</mi> <mi>P</mi> </mrow> </msub> </semantics></math>. The case in (<b>a</b>) has shorter perception range, with <math display="inline"><semantics> <msub> <mi mathvariant="bold-italic">H</mi> <mrow> <mi>C</mi> <mi>P</mi> </mrow> </msub> </semantics></math> represented as (<b>b</b>). While the case in (<b>c</b>) has longer perception range, with <math display="inline"><semantics> <msub> <mi mathvariant="bold-italic">H</mi> <mrow> <mi>C</mi> <mi>P</mi> </mrow> </msub> </semantics></math> augmented by the commonly observed landmarks <math display="inline"><semantics> <msub> <mi mathvariant="script">P</mi> <mrow> <mi>a</mi> <mi>b</mi> <mi>c</mi> </mrow> </msub> </semantics></math>, represented as (<b>d</b>). Note that many of the block matrices in dark blue remain zero due to the absence of observation between corresponding camera pose <math display="inline"><semantics> <msub> <mi mathvariant="bold-italic">C</mi> <mi>i</mi> </msub> </semantics></math> and landmark <math display="inline"><semantics> <msub> <mi mathvariant="bold-italic">P</mi> <mi>j</mi> </msub> </semantics></math>.</p>
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<p>A diagram of a virtual map point. (i) The virtual map point <math display="inline"><semantics> <mi mathvariant="normal">V</mi> </semantics></math> is constructed from features matched from two adjacent frames. (ii) As the camera moves, features and back-projected rays in subsequent frames are associated with <math display="inline"><semantics> <mi mathvariant="normal">V</mi> </semantics></math>, allowing for the calculation of the maximum parallax angle. (iii) The spatial coordinates of <math display="inline"><semantics> <mi mathvariant="normal">V</mi> </semantics></math> are triangulated when the parallax angle exceeds the threshold <math display="inline"><semantics> <msub> <mi>θ</mi> <mi>th</mi> </msub> </semantics></math>. (iv) Subsequently, a map point <math display="inline"><semantics> <mi mathvariant="normal">P</mi> </semantics></math> is constructed from <math display="inline"><semantics> <mi mathvariant="normal">V</mi> </semantics></math>, inheriting the observation relationships with frames ranging from <math display="inline"><semantics> <msub> <mi mathvariant="normal">F</mi> <mn>0</mn> </msub> </semantics></math> to <math display="inline"><semantics> <msub> <mi mathvariant="normal">F</mi> <mi>i</mi> </msub> </semantics></math>.</p>
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<p>An overview of the proposed SLAM system. The management of virtual map points is integrated into the “Local Mapping” thread of ORB-SLAM3.</p>
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<p>Keyframe trajectory comparison between ORB-SLAM3 (ORB3) and the proposed method (MOD) alongside groundtruth (GT) from the top view in sequences of (<b>a</b>) EuRoC Machine Hall 05, (<b>b</b>) KITTI 00, (<b>c</b>) KAIST 32, (<b>d</b>) KAIST 27, (<b>e</b>) KAIST 33, (<b>f</b>) KAIST 39 and (<b>g</b>) UZH MAV during the dataset test.</p>
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<p>The distribution of triangulation depth of map points in dataset tests: (<b>a</b>) Comparison between ORB-SLAM3 (ORB3) and the proposed method (MOD); (<b>b</b>) comparison between normal map points and map points converted from virtual map points within the proposed method.</p>
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<p>The observation on map points in the 2776th frame of the sequence KAIST 26 by (<b>a</b>) ORB-SLAM3 and (<b>b</b>) the proposed method, and in the 2979th frame by (<b>c</b>) ORB-SLAM3 and (<b>d</b>) the proposed method, with normal map points denoted in green and converted virtual map points denoted in red.</p>
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<p>Comparison of statistics on mean tracking time across the dataset and field tests between ORB-SLAM3 (ORB) and the proposed method (MOD).</p>
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<p>(<b>a</b>) The experimental platform on a wheeled robot. Intel D435i collects the monocular image sequence and ComNav M100 offers groundtruth. (<b>b</b>) A sample of collected image sequences, which contains parts of distant landmarks. The sequences are collected in campus scenes of (<b>c</b>) yard, (<b>d</b>) road and (<b>e</b>) park. Location: Science Park, Harbin Institute of Technology.</p>
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<p>Keyframe trajectory comparison between ORB-SLAM3 (ORB3) and the proposed method (MOD) alongside groundtruth (GT) from the top view in scenes of a (<b>a</b>) yard, (<b>b</b>) road and (<b>c</b>) park during the field test.</p>
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<p>The distribution of triangulation depth of map points in field tests: (<b>a</b>) Comparison between ORB-SLAM3 (ORB3) and the proposed method (MOD); (<b>b</b>) comparison between normal map points and map points converted from virtual map points within the proposed method.</p>
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