[Effects of enriched environment and impoverished environment on learning and memory ability of manganese-exposed mice].

OBJECTIVE: To investigate the effects of enriched environment and impoverished environment on the learning and memory ability of manganese-exposed mice and the mechanism. METHODS: Forty female Kunming mice were randomly and equally divided into 4 group: control group (CG), standard environment and manganese exposure group (SEG), enriched environment and manganese exposure group (EEG), and impoverished environment and manganese exposure group (IEG). The mouse model of manganese poisoning was established by intraperitoneal injection of manganese chloride. The learning and memory ability was tested by Morris water maze. The expression of cAMP response element-binding protein (CREB) in area CA1 of the hippocampus was measured by immunohistochemistry. RESULTS: In place navigation test, the SEG had a significantly longer escape latency than the CG (P < 0.05), and the EEG had a significantly shorter escape latency than the SEG (P < 0.05); there was no significant difference in escape latency between IEG and SEG (P > 0.05). In spatial probe test, the EEG had a significantly greater number of platform crossings than the SEG (P < 0.05), and the IEG had a significantly smaller number of platform crossings than the SEG (P < 0.05). The expression of CREB in area CA1 of the hippocampus was significantly lower in IEG and SEG than in CG (P < 0.05), and it was significantly higher in EEG than in SEG (P < 0.05). CONCLUSION: In the enriched environment, the learning and memory ability of manganese-exposed mice can be improved, which may be due to the increased expression of CREB in the hippocampus.

Assessment on the declining degree of farmland shelter forest in a desert oasis based on LiDAR and hyperspectrum imagery.

We examined the growth decline and health status of farmland protective forest belt (Populus alba var. pyramidalis and Populus simonii shelterbelts) in Ulanbuh Desert Oasis by using airborne hyperspectral and ground-based LiDAR to collect the hyperspectral images and point cloud data of the whole forest belt respectively. Through correlation analysis and stepwise regression analysis, we constructed the evaluation model of the decline degree of farmland protection forest with the spectral differential value, vegetation index, and forest structure parameters as independent variables and the tree canopy dead branch index of the field survey as dependent variables. We further tested the accuracy of the model. The results showed that the evaluation accuracy of the decline degree of P. alba var. pyramidalis and P. simonii by LiDAR method was better than that by hyperspectral method, and that the evaluation accuracy of the combined LiDAR and hyperspectral method was the highest. Using the LiDAR method, hyperspectral method, the combined method, the optimal model of P. alba var. pyramidalis was all light gradient boosting machine model, with the overall classification accuracy being 0.75, 0.68, 0.80, and Kappa coefficient being 0.58, 0.43, 0.66, respectively. The optimal model of P. simonii was random forest model, random forest model, and multilayer perceptron model, with the overall classification accuracy being 0.76, 0.62, 0.81, and Kappa coefficient being 0.60, 0.34, 0.71, respectively. This research method could accurately check and monitor the decline of plantations.

Biomechanical analysis of fixation strength at different nailing angles for femoral neck fracture with insufficient reduction.

To analyze the fixation strength of cannulated screws fixation in the treatment of femoral neck fracture with posterior tilt due to insufficient reduction. Two sets of digital models of anatomical reduction and 15° tilting reduction were established by CT data. Each group of models was modeled with two different fixation methods. One fixation method was fixed according to the standard cannulated screws recommended by AO. Another fixation method is to tilt the screw posterior tilt 15°. The final four groups of models were obtained: AO principle nailing posterior tilt model (Group A), posterior direction nailing posterior tilt model (Group B), AO principle nailing anatomic reduction model (Group C) and posterior direction nailing anatomic reduction model (Group D). The maximum displacement of the fracture end, the maximum Von-Mises stress and the stress distribution of the internal fixation were compared among the four groups. Four groups of models were established on artificial bone by 3D printing guide plate technology. The 600 N pressure test and yield test were performed on a biomechanical machine. The finite element and biomechanical models showed that groups B and C were more stable than groups A and D. The stability of group B was not worse than that of group C. When the femoral neck fracture produces a posterior tilt, a posterior reduction is allowed. The change of AO screw to posterior tilting screw fixation has more powerful advantages. No posterior tilt or posterior reduction, AO screw placement is still required.

Three-dimensional model construction and wind simulation of different tree species in farmland shelter.

Protective forests are the ecological barriers of oases in arid sand areas and can effectively prevent and control wind and sand hazards. The structural characteristics of individual trees, as the basic unit of protective forests, are the key factors affecting the protective benefits. With the typical leafless tree species of Ulan Buh Desert oasis, i.e., Populus alba var. pyramidalis, Populus nigra var. thevestina, and Populus popularis, as the research objects, and by using the ground-based LiDAR and through computational fluid dynamics (CFD), we fully explored the structural characteristics of individual trees and their surrounding aerodynamic characteristics on the basis of real 3D models. We further established the relationship between structural parameters of individual trees and wind field index. The results showed that combining AdQSM and MeshLab to build tree models had high accuracy. The wind field around the individual trees could be roughly divided into six regions, including the attenuation zone of the windward side of the plant, the acceleration zone at the top of the plant, the eddy zone, the calm zone, the transition zone, and the recovery zone of leeward side of the plant. The pressure field around individual trees showed a gradual change of high pressure on the windward side to low pressure on the leeward side. Horizontally, in the range of 20% to 50% reduction in relative wind speed, the effective protection distances were 0.21H-1.51H, 0.20H-0.91H, and 0.25H-1.64H (H was the corresponding tree height) for P. alba var. pyramidalis, P. nigra var. thevestina, and P. popularis, corresponding to effective protection areas of 18-294, 15-227, and 18-261 m2, respectively. The maximum wind speed decay rate in the vertical direction was at 0.3H height for P. alba var. pyramidalis and P. popularis, and was reflected at 0.5H height for P. nigra var. thevestina. The correlation and stepwise regression analysis of the single tree structure parameters with the wind field indicators clearly indicated that optical porosity and volume porosity dominated the protection effect. Among the wind field factors, the best regression models related to the porous coefficient were screened for three factors, including diameter at breast height, tree surface area, and optical porosity. The regression variables screened for effective protection distance and effective protection area differed among the classes.