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ObjectiveFarmland consolidation for agricultural mechanization in hilly and mountainous areas can alter the landscape pattern, elevation, slope and microgeomorphology of cultivated land. It is of great significance to assess the ecological risk of cultivated land to provide data reference for the subsequent farmland consolidation for agricultural mechanization. This study aims to assess the ecological risk of cultivated land before and after farmland consolidation for agricultural mechanization in hilly and mountainous areas, and to explore the relationship between cultivated land ecological risk and cultivated land slope.MethodsTwenty counties in Tongnan district of Chongqing city was selected as the assessment units. Based on the land use data in 2010 and 2020 as two periods, ArcGIS 10.8 and Excel software were used to calculate landscape pattern indices. The weights for each index were determined by entropy weight method, and an ecological risk assessment model was constructed, which was used to reveal the temporal and spatial change characteristics of ecological risk. Based on the principle of mathematical statistics, the correlation analysis between cultivated land ecological risk and cultivated land slope was carried out, which aimed to explore the relationship between cultivated land ecological risk and cultivated land slope.Results and DiscussionsComparing to 2010, patch density (PD), division (D), fractal dimension (FD), and edge density (ED) of cultivated land all decreased in 2020, while meant Patch Size (MPS) increased, indicating an increase in the contiguity of cultivated land. The mean shape index (MSI) of cultivated land increased, indicating that the shape of cultivated land tended to be complicated. The landscape disturbance index (U) decreased from 0.97 to 0.94, indicating that the overall resistance to disturbances in cultivated land has increased. The landscape vulnerability index (V) increased from 2.96 to 3.20, indicating that the structure of cultivated land become more fragile. The ecological risk value of cultivated land decreased from 3.10 to 3.01, indicating the farmland consolidation for agricultural mechanization effectively improved the landscape pattern of cultivated land and enhanced the safety of the agricultural ecosystem. During the two periods, the ecological risk areas were primarily composed of low-risk and relatively low-risk zones. The area of low-risk zones increased by 6.44%, mainly expanding towards the northern part, while the area of relatively low-risk zones increased by 6.17%, primarily spreading towards the central-eastern and southeastern part. The area of moderate-risk zones increased by 24.4%, mainly extending towards the western and northwestern part, while the area of relatively high-risk zones decreased by 60.70%, with some new additions spreading towards the northeastern part. The area of high-risk zones increased by 16.30%, with some new additions extending towards the northwest part. Overall, the ecological safety zones of cultivated relatively increased. The cultivated land slope was primarily concentrated in the range of 2° to 25°. On the one hand, when the cultivated land slope was less than 15°, the proportion of the slope area was negatively correlated with the ecological risk value. On the other hand, when the slope was above 15°, the proportion of the slope area was positively correlated with the ecological risk value. In 2010, there was a highly significant correlation between the proportion of slope area and ecological risk value for cultivated land slope within the ranges of 5° to 8°, 15° to 25°, and above 25°, with corresponding correlation coefficients of 0.592, 0.609, and 0.849, respectively. In 2020, there was a highly significant correlation between the proportion of slope area and ecological risk value for cultivated land slope within the ranges of 2° to 5°, 5° to 8°, 15° to 25°, and above 25°, with corresponding correlation coefficients of 0.534, 0.667, 0.729, and 0.839, respectively.ConclusionsThe assessment of cultivated land ecological risk in Tongnan district of Chongqing city before and after the farmland consolidation for agricultural mechanization, as well as the analysis of the correlation between ecological risk and cultivated land slope, demonstrate that the farmland consolidation for agricultural mechanization can reduce cultivated land ecological risk, and the proportion of cultivated land slope can be an important basis for precision guidance in the farmland consolidation for agricultural mechanization. Considering the occurrence of moderate sheet erosion from a slope of 5° and intense erosion from a slope of 10° to 15°, and taking into account the reduction of ecological risk value and the actual topographic conditions, the subsequent farmland consolidation for agricultural mechanization in Tongnan district should focus on areas with cultivated land slope ranging from 5° to 8° and 15° to 25°.

Bladder paraganglioma (BPG) is a rare extra-adrenal pheochromocytoma with variable symptoms and easy to be misdiagnosed and mishandled. The aim of the study was to document the imaging features of BPG using computed tomography (CT) and magnetic resonance imaging (MRI).

Conditioning is an important step in harvesting alfalfa hay, as squeezing and bending alfalfa stems can break down the stem fibers and accelerate the drying rate of alfalfa. The quality of alfalfa hay is directly affected by the conditioning effect. The finite element method (FEM) can quantitatively analyze the interaction relationship between alfalfa and conditioning rollers, which is of great significance for improving conditioning effects and optimizing conditioning systems. The accuracy of material engineering parameters directly affects the simulation results. Due to the small diameter and thin stem wall of alfalfa, some of its material parameters are difficult to measure or have low measurement accuracy. Based on this background, this study proposed a method for calibrating the finite element parameters of thin-walled plant stems. By conducting radial tensile, shear, bending, and radial compression tests on alfalfa stems and combining with the constitutive relationship of the material, the range of engineering parameters for the stems was preliminarily obtained. By conducting a Plackett–Burman experiment, the parameters that affect the maximum shearing force of stems were determined, including Poisson's ratio in the isotropic plane, radial elastic modulus, and the sliding friction coefficient between the alfalfa stem and steel plate. By conducting the steepest ascent experiment and Box–Behnken experiment, the optimal values of Poisson's ratio, radial elastic modulus, and sliding friction coefficient were obtained to be 0.42, 28.66 MPa, and 0.60, respectively. Finally, the double-shear experiment, radial compression experiment, and conditioning experiment were used to evaluate the accuracy of the parameters. The results showed that the average relative error between the maximum shear and the measured value was 0.88%, and the average relative error between the maximum radial contact force and the measured value was 2.13%. In the conditioning experiment, the load curve showed the same trend as the measured curve, and the simulation results could demonstrate the stress process and failure mode of alfalfa stems. The modeling and calibration method can effectively predict the stress and failure of alfalfa during conditioning. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cells (PEMFCs) have been considered by many countries and enterprises because of their cleanness and efficiency. However, due to their high cost and low platinum utilization rate, the commercialization process of PEMFC is severely limited. The cathode catalyst layer (CCL) plays an important role in manipulating the performance and lifespan of PEMFCs, which makes them one of the most significant research focuses in this community. In the CCL, the intrinsic activity and stability of the catalysts determine the performance and lifetime of the catalyst layer. In this paper, the composition and working principle of the PEMFC and cathode catalyst layer are briefly introduced, focusing on Pt-based catalysts for oxygen reduction reactions (ORRs). The research progress of Pt-based catalysts in the past five years is particularly reviewed, mainly concentrating on the development status of emerging Pt-based catalysts which are popular in the current research field, including novel concepts like phase regulation (intermetallic alloys and high-entropy alloys), interface engineering (coupled low-Pt/Pt-free catalysts), and single-atom catalysts. Finally, the future research and development directions of Pt-based ORR catalysts are summarized and prospected. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to verify the feasibility and short-term prognosis of prostatectomy without biopsy. Materials and Methods: Patients with a rising PSA level ranging from 4 to 30 ng/mL were scheduled for multiparametric (mp) MRI and 18F-labeled prostate-specific membrane antigen (PSMA) positron emission tomography (PET). Forty-seven patients (cT2N0M0) with Prostate Imaging Reporting and Data System ≥ 4 and molecular imaging PSMA score ≥ 2 were enrolled. All candidates underwent robot-assisted laparoscopic radical prostatectomy without biopsy. Prostate cancer detection rate, index tumors localization correspondence rate, positive surgical margin, complications, postoperative hospital stay, and PSA level in a 6-week postoperative follow-up visit were collected. Results: All the patients with positive mpMRI and PSMA PET were diagnosed with clinically significant prostate cancer. A total of 80 lesions were verified as cancer by pathology, of which 63 cancer lesions were clinically significant prostate cancer. Fifty-one lesions were simultaneously found by mpMRI and PSMA PET. A total of 23 lesions were invisible on either image, and all lesions were ≤ International Society of Urological Pathology 2 or ≤ 15 mm. Forty-five (95.7%) index tumors found by mpMRI combined with PSMA PET were consistent with pathology. Nine patients reported positive surgical margin. Conclusions: Biopsy-free prostatectomy is safe and feasible for patients with evaluation strictly by mpMRI combined with 18F-PSMA PET/CT. [ABSTRACT FROM AUTHOR]

Background: Venous tumor thrombus (VTT) consistency of renal cell carcinoma (RCC) is an important consideration in nephrectomy plus thrombectomy. However, evaluation of VTT consistency through preoperative MR imaging is lacking. Purpose: To evaluate VTT consistency of RCC through intravoxel incoherent motion‐diffusion weighted imaging (IVIM‐DWI) derived parameters (Dt, Dp, f, and ADC) and the apparent diffusion coefficient (ADC) value. Study Type: Retrospective. Population: One hundred and nineteen patients (aged 55.8 ± 11.5 years, 85 male) with histologically‐proven RCC and VTT who underwent radical resection. Field Strength/Sequences: 3.0‐T; two‐dimensional single‐shot diffusion‐weighted echo planar imaging sequence at 9 b‐values (0–800 s/mm2). Assessment: IVIM parameters and ADC values of the primary tumor and the VTT were calculated. The VTT consistency (friable vs. solid) was determined through intraoperative findings of two urologists. The accuracy of VTT consistency classification based on the individual IVIM parameters of primary tumors and of VTT, and based on models combining parameters, was assessed. Type of operation, intra‐operative blood loss, and operation length were recorded. Statistical Tests: Shapiro–Wilk test; Mann–Whitney U test; Student's t‐test; Chi‐square test; Receiver operating characteristic (ROC) analysis. Statistical significance level was P < 0.05. Results: Of the enrolled 119 patients, 33 patients (27.7%) had friable VTT. Patients with friable VTT were significantly more likely to experience open surgery, have significantly more intraoperative blood loss, and significantly longer operative duration. The area under the ROC curve (AUC) values of Dt of the primary tumor and VTT in classifying VTT consistency were 0.758 (95% CI 0.671–0.832) and 0.712 (95% CI 0.622–0.792), respectively. The AUC value of the model combining Dp and Dt of VTT was 0.800 (95% CI 0.717–0.868). Furthermore, the AUC of the model combining Dp and Dt of VTT and Dt of the primary tumor was 0.886 (95% CI 0.814–0.937). Conclusion: IVIM‐derived parameters had the potential to predict VTT consistency of RCC. Evidence Level: 3 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]