Preparation of high molecular weight polyvinyl alcohol by emulsifier-free emulsion polymerization

In this report, high molecular weight polyvinyl alcohol (PVA) was prepared by emulsifier-free emulsion polymerization, using the redox initiator of potassium persulfate (KPS) / N,N-dimethyl ethanolamine (DMEA). The structure and property of PVA were studied by using ubbelohde viscometer, fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy (1H-NMR), X-ray Diffraction (XRD), differential scanning calorimeter (DSC) and thermo gravimetric analysis (TGA). The results showed that the viscosity-average degree of polymerization (DP) of PVA 7506, which was much higher than that of PVA commonly used in industrial production. The syndiotacticity and crystallinity of PVA was 54.2 % and 35.6 %, respectively

Giant rashba splitting of confined Te chains in nanotubes: the size-, chirality-, and type- effects of nanotubes

Understanding the coupling between one-dimensional (1D) materials and their protective materials is essential for developing nanodevices. Herein, we investigate the effect of the size, chirality, and type of nanotubes [such as carbon/boron nitride nanotubes (CNTs/BNNTs)] on the atomic and electronic structures of confined Te chains using density functional theory. We find that the optimal configurations of the Te chains confined in CNTs/BNNTs depend strongly on the size of the nanotubes but weakly on their chirality and type. Furthermore, the Te@BNNTs exhibit giant Rashba splitting with a Rashba constant of up to 2.65 eV Å, while the Te@CNTs show no splitting. This is mainly due to the large bandgap of the BNNTs, as well as the enhanced symmetry breaking of the Te chains when confined. Our findings provide a basis for the design of nano spin devices through protective materials

Method of 3D Voxel Prescription Map Construction in Digital Orchard Management Based on LiDAR-RTK Boarded on a UGV

Precision application of pesticides based on tree canopy characteristics such as tree height is more environmentally friendly and healthier for humans. Offline prescription maps can be used to achieve precise pesticide application at low cost. To obtain a complete point cloud with detailed tree canopy information in orchards, a LiDAR-RTK fusion information acquisition system was developed on an all-terrain vehicle (ATV) with an autonomous driving system. The point cloud was transformed into a geographic coordinate system for registration, and the Random sample consensus (RANSAC) was used to segment it into ground and canopy. A 3D voxel prescription map with a unit size of 0.25 m was constructed from the tree canopy point cloud. The height of 20 trees was geometrically measured to evaluate the accuracy of the voxel prescription map. The results showed that the RMSE between tree height calculated from the LiDAR obtained point cloud and the actual measured tree height was 0.42 m, the relative RMSE (rRMSE) was 10.86%, and the mean of absolute percentage error (MAPE) was 8.16%. The developed LiDAR-RTK fusion acquisition system can generate 3D prescription maps that meet the requirements of precision pesticide application. The information acquisition system of developed LiDAR-RTK fusion could construct 3D prescription maps autonomously that match the application requirements in digital orchard management

A Path Planning System for Orchard Mower Based on Improved A* Algorithm

The application of intelligent mobile robots in agriculture has emerged as a new research frontier, with the integration of autonomous navigation technology and intelligent agricultural robots being the key to the widespread adoption of smart agricultural machinery. This paper investigates comprehensive coverage path planning for tracked lawnmowers within orchard environments and addresses challenges related to task allocation and battery life. Firstly, in this study, the motion model of the tracked lawnmower was initially simplified based on assumptions about the orchard environment. Force analyses were conducted on each of its motion mechanisms. For the known orchard environment, a grid-based mapping technique was employed to model the orchard environment. Then, in order to improve the algorithm speed and reduce the number of turns during the lawnmower’s traversal, the A* search algorithm was enhanced by combining the method of robot cluster traversal in the orchard environment. Finally, the improved method was simulated and verified in the MATLAB platform to investigate the influence of the number of lawnmower clusters on the path planning in the connected and non-connected orchards. Furthermore, two sets of on-site field trials were meticulously designed to validate the reliability, practicality, and efficacy of the simulation experiments

Dynamic analysis of the microbial communities and metabolome of healthy banana rhizosphere soil during one growth cycle

Background The banana-growing rhizosphere soil ecosystem is very complex and consists of an entangled network of interactions between banana plants, microbes and soil, so identifying key components in banana production is difficult. Most of the previous studies on these interactions ignore the role of the banana plant. At present, there is no research on the the micro-ecological environment of the banana planting growth cycle. Methods Based on high-throughput sequencing technology and metabolomics technology, this study analyzed the rhizosphere soil microbial community and metabolic dynamics of healthy banana plants during one growth cycle. Results Assessing the microbial community composition of healthy banana rhizosphere soil, we found that the bacteria with the highest levels were Proteobacteria, Chloroflexi, and Acidobacteria, and the dominant fungi were Ascomycota, Basidiomycota, and Mortierellomycota. The metabolite profile of healthy banana rhizosphere soil showed that sugars, lipids and organic acids were the most abundant, accounting for about 50% of the total metabolites. The correlation network between fungi and metabolites was more complex than that of bacteria and metabolites. In a soil environment with acidic pH, bacterial genera showed a significant negative correlation with pH value, while fungal genera showed no significant negative correlation with pH value. The network interactions between bacteria, between fungi, and between bacteria and fungi were all positively correlated. Conclusions Healthy banana rhizosphere soil not only has a stable micro-ecology, but also has stable metabolic characteristics. The microorganisms in healthy banana rhizosphere soil have mutually beneficial rather than competitive relationships

Obstacle Avoidance and Profile Ground Flight Test and Analysis for Plant Protection UAV

In recent years, with the further development of agricultural aviation technology, the plant protection UAV has been widely used, especially in some agricultural environments with limited operating conditions due to its advantages of high efficiency, environmental protection and safety guarantee. A plant protection UAV generally flies at low altitude during operation. However, the low altitude operation environment, such as farmland and mountainous areas, is relatively complex, and is faced with many types of obstacles, proposing higher requirements for obstacle avoidance and the profiling system of a plant protection UAV. In order to test the obstacle avoidance and profiling performance of the commercialized plant protection UAV at this stage and explore the performance boundary of obstacle avoidance and profiling of the UAV, EAVISION E-A2021 and XAG P80, the flagship models of the plant protection UAV manufacturer on the market, were hereby selected as the experimental test objects in the paper. Firstly, the obstacle avoidance and profiling test scheme of plant protection UAVs is designed; then, the above two UAVs are adopted for corresponding tests, and the test data are discussed based on the analysis of software and hardware technology; finally, the practical application status of different obstacle avoidance and profiling technologies of plant protection UAVs is clarified, and the shortcomings of obstacle avoidance and profiling technology of plant protection UAVs on the market are summarized, providing a reliable reference for the future development of plant protection UAVs

NODULES WITH ACTIVATED DEFENSE 1 is required for maintenance of rhizobial endosymbiosis in Medicago truncatula

The symbiotic interaction between legume plants and rhizobia results in the formation of root nodules, in which symbiotic plant cells host and harbor thousands of nitrogen-fixing rhizobia. Here, a Medicago truncatula nodules with activated defense 1 (nad1) mutant was identified using reverse genetics methods. The mutant phenotype was characterized using cell and molecular biology approaches. An RNA-sequencing technique was used to analyze the transcriptomic reprogramming of nad1 mutant nodules. In the nad1 mutant plants, rhizobial infection and propagation in infection threads are normal, whereas rhizobia and their symbiotic plant cells become necrotic immediately after rhizobia are released from infection threads into symbiotic cells of nodules. Defense-associated responses were detected in nad1 nodules. NAD1 is specifically present in root nodule symbiosis plants with the exception of Morus notabilis, and the transcript is highly induced in nodules. NAD1 encodes a small uncharacterized protein with two predicted transmembrane helices and is localized at the endoplasmic reticulum. Our data demonstrate a positive role for NAD1 in the maintenance of rhizobial endosymbiosis during nodulation