New Formulation to Accelerate the Degradation of Pesticide Residues: Composite Nanoparticles of Imidacloprid and 24-Epibrassinolide.

Pest control effectiveness and residues of pesticides are contradictory concerns in agriculture and environmental conservation. On the premise of not affecting the insecticidal effect, the pesticide residues in the later stage should be degraded as fast as possible. In the present study, composite nanoparticles in a double-layer structure, consisting of imidacloprid (IMI) in the outer layer and plant hormone 24-epibrassinolide (24-EBL) in the inner layer, were prepared by the W/O/W solvent evaporation method using Eudragit RL/RS and polyhydroxyalkanoate as wall materials. The release of IMI in the outer layer was faster and reached the maximum within 24 h, while the release of 24-EBL in the inner layer was slower and reached the maximum within 96 h. The contact angle of the composite nanoparticles was half that of the 5% IMI emulsifiable concentrate (EC), and the deposition of composite nanoparticles on rice was twice that of 5% IMI EC, which increased the pesticide utilization efficiency. Compared with the common pesticide, 5% IMI EC, the insecticidal effect of the composite nanoparticles was stronger than that of planthoppers, with a much lower final residue amount on rice after 21 days. The composite nanoparticles prepared in this study to achieve sustained release of pesticides and, meanwhile, accelerate the degradation of pesticide residues have a strong application potential in agriculture for controlling pests and promoting crop growth.

Multi-walled Carbon Nanotubes Remediate the Phytotoxicity of Quinclorac to Tomato.

In order to remediate the phytotoxicity of quinclorac to tomato by multi-walled carbon nanotubes (MWCNTs), the adsorption of quinclorac to MWCNTs was monitored and the effect of MWCNTs on the phytotoxicity of quinclorac to tomato in soil were studied. The results showed that the Linear equation and Freundlich equation can well fit the adsorption isotherm of quinclorac in the soil containing MWCNTs. The adsorption of quinclorac in soil was significantly enhanced by the addition of MWCNTs; the Kd of soil (1% MWCNTs) was 28.7 times of pure soil. The quinclorac had an obvious inhibitory effect on the growth of tomatoes; serious phytotoxicity was also induced even at the lowest concentration of 0.025 mg/kg. With the MWCNTs content in soil increased to 0.5% and 1%, the phytotoxicity of quinclorac to tomatoes decreased significantly, and the height and fresh weight of tomatoes were even higher than those of the control group, indicating that MWCNTs can promote the growth of tomato. These results provide a reference for resolving the problem of phytotoxicity induced by residual herbicides in farmland.

The effects of polyethersulfone and Nylon 6 micromembrane filters on the pyraclostrobin detection: adsorption performance and mechanism.

Adsorption of test substances on micromembrane filters during sample pretreatment before qualitative and quantitative analysis has greatly affected the accuracy of the measurement. In the present study, it was found that the adsorption rate of pyraclostrobin reached 77.7-100% when water samples of pyraclostrobin (1 mL) were filtered with polyethersulfone (PES) and Nylon 6 filters. Therefore, the adsorption mechanisms were investigated from the kinetics, isotherms, and thermodynamics of the pyraclostrobin adsorption process, combined with attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. The results showed that PES accorded with second-order adsorption kinetics and Nylon 6 with first-order adsorption kinetics, and the correlation coefficient R2 was 0.98. The adsorption behavior of the two micromembranes followed the linear isothermal model, indicating that the adsorption process was through monolayer adsorption. Thermodynamic study showed that the adsorption of pyracoethyl on PES membrane was spontaneous endothermic, while that on Nylon 6 was spontaneous exothermic. The π-π electron-donor-acceptor (EDA) between pyraclostrobin and PES may promote the adsorption of PES to pyraclostrobin, and hydrogen bonding between pyraclostrobin and Nylon 6 micromembrane may be involved in the adsorption. Our study also proved that the adding 60% methanol and iodine solution (2 mmol/L) was an effective strategy to reduce the adsorption effects and to increase the accuracy of the detection.

Can the multi-walled carbon nanotubes be used to alleviate the phytotoxicity of herbicides in soils?

Herbicides are commonly used globally. However, residual herbicides in soils for ages often result in phytotoxicity and serious yield loss to subsequent crops. In this paper, the multi-walled carbon nanotubes (MWCNTs) were utilized to amend the herbicide polluted soil, and the adsorption performance of herbicides to MWCNTs amended soil was studied. Results indicate efficient alleviation of herbicide-induced phytotoxicity to rice and tobacco due to MWCNTs amendment. When 0.4% MWCNTs were applied, the concentration of sulfentrazone that inhibited the same rice height by 50% (IC50) increased to more than 3 times that of pure soil. When the MWCNTs were used to alleviate the phytotoxicity of quinclorac to tobacco, the MWCNTs not only alleviated the phytotoxicity of quinclorac but also promoted the growth of tobacco. The MWCNTs amended soil significantly increased the adsorption of herbicide to soil than biochar. The soil microbial analysis shows that MWCNTs had no significant effect on soil microbial community diversity, but the long-term exposure to MWCNTs could change the structure of the soil microbial community. Above all, our results highlighted the potential implication of the MWCNTs to ensure crop production by promoting crop growth and reducing the residual bioavailability of herbicides.

Inversion of the physical properties of seafloor surface sediments based on AUV sub-bottom profile data in the northern slope of the South China Sea.

Based on the seafloor reflection coefficient obtained from autonomous underwater vehicle (AUV) sub-bottom profile survey data of the northern slope of the South China Sea, combined with the sample test data of seafloor surface sediments, we use the Biot-Stoll model to establish the equations relating the seafloor reflection coefficient to the porosity, density, and mean grain size of the sediments at the dominant frequency of 5 kHz (the dominant frequency of the AUV sub-bottom profiler). The physical property parameters such as the porosity, density, and mean grain size of seafloor surface sediments are further inverted. Comparison of inversion results with measured results shows that the overall deviation ratios of the inverted mean grain size, porosity, and density of the surface sediments are in the ranges of - 13.56 to 14.44%, - 6.15 to 8.06%, and - 10.85 to 0.46%, respectively. Among them, the mean grain size directly reflects the size of seafloor sediment particles, and the particles are finer in deeper water. Overall, the inversion results are basically consistent with the measured values and thus can well reflect the variation characteristics of the physical properties of seafloor surface sediments.

Clinical application of planar puncture template-assisted computed tomography-guided percutaneous biopsy for small pulmonary nodules.

AIMS: The aims of this study were to evaluate the clinical application of planar puncture template (PPT) in computed tomography (CT)-guided percutaneous needle lung biopsy. SUBJECTS AND METHODS: A total of 56 patients with small pulmonary nodules who received CT-guided percutaneous lung biopsy assisted by PPT were included in the study. Five steps were included in the study: fixing position, CT scanning and designing needle pathway, installing navigation system and template, puncturing fixation needle, and performing biopsy needle insertion and biopsy. The success rate of puncture, pathological results, and complications were analyzed. In addition, the factors that influenced the success rate and complications were analyzed. RESULTS: Biopsy was successfully completed in all 56 patients. The nodule diameter was 0.45-3 cm. The fixation needle technique was applied in 47 cases. Biopsy was performed 1 time in 50% of patients and 2 times in 38% of patients. For pathology, only one case showed no positive result, with a puncture success rate of 98%. The diagnostic rate of malignant tumor was 73%. For complications, the incidence of needle tract bleeding was 68%, the incidence of pneumothorax was 30%, and the thoracic drainage was required in two patients. Hemoptysis was observed in two cases. Univariate analysis: The nodule size was related to both the rate of 1-time biopsy and incidence of complications. Smaller nodule was relevant to lower rate of 1-time biopsy (P = 0.01) and higher incidence of complications (P < 0.05). The fixation needle was related to 1-time biopsy rate. The 1-time biopsy rate was significantly higher in patients with fixation needle than those without fixation needle (P = 0.001). Meanwhile, no significant difference was observed in the incidence of complications in different number of fixation needles (P > 0.05). CONCLUSIONS: PPT-assisted lung biopsy technology can provide high success rate and low complication incidence. It would be helpful to make the puncture procedures more standard for better clinical applications.