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Highlights A turbidity sensor module was investigated to monitor concentrations of pesticide mixtures in real time. A flow-through measurement platform was built to calibrate the turbidity sensor and determine its accuracy. Optimal location of the turbidity sensor was determined for monitoring in-line mixture concentrations. Spray mixture uniformity reached acceptable level for the premixing in-line injection system. Abstract. Monitoring mixture concentrations for precision pesticide spray systems in real time can assure the desired amount of chemicals distributed uniformly to target areas. An in-line turbidity sensor module was investigated to monitor concentrations of spray mixtures produced with a premixing in-line injection system developed for precision variable-rate orchard sprayers. The turbidity sensor was calibrated with simulated pesticides at concentrations ranging from 0% to 30.0%. A cubic polynomial regression model was established for the relationship between sensor output voltages and mixture concentrations. Sensors were mounted at three in-line locations to detect the mixture uniformity differences in the premixing in-line injection system. The module was found to have adequate precision and accuracy to measure concentrations of spray mixtures with simulated pesticides. Relative errors of the sensor were less than 4.70% and the sensor accuracy did not vary with mixture flow rates. Mounting the turbidity sensor downstream of the buffer tank in the premixing in-line injection system would be the optimal location to monitor spray mixture uniformity for variable-rate spray applications. At this location, the relative errors of measured mixture concentrations were between 0.12% and 3.70% which agreed with previous manual measurements. Therefore, there would be a great potential to integrate the in-line turbidity sensor into the variable-rate and even conventional constant-rate sprayers to achieve uniform spray applications in the target field. Keywords: Agitation, Mixture uniformity, Pesticide concentration, Sensor calibration, Variable-rate sprayer.

Highlights A commercial depth camera with a custom-designed graphical user interface was evaluated to detect tree canopy. Measurement variations under different indoor conditions were negligible for practical applications. Measurement errors ranged from 2.8% to 15.8%, which were acceptable for outdoor applications. Variation of crabapple canopy detection rate was less than 6% from sunrise to sunset. Abstract. To reduce crop protection product use and environmental impacts while maintaining application efficacy and convenience for applicators, an automatic variable rate sprayer coupled with a canopy detection sensor is required. A commercial depth camera was tested as a means of detecting the canopy of ornamental and tree crops for the sprayer. A custom-designed graphical user interface was developed to control the depth camera and save RGB and IR images and depth data to a local computer. Indoor evaluations showed that measurements could be influenced by the temperature and illumination; however, the influence was minimal, with a relative error of less than 1% and a maximum difference of 14 mm between the average measurements. The depth camera was able to detect a 31% to 72% area of a 20-mm wide target, and the rates went up 72% to 89% when the target width increased to 40 mm. The depth camera showed acceptable performance in detecting canopy contour changes and had measurement errors of 2.8% to 15.3% while detecting the distances to outdoor crabapple and oak trees. In addition, the depth camera detected tree canopy in various outdoor conditions from sunrise to sunset with reasonable accuracy (less than 10% of relative errors). In terms of measurement stability, the depth camera detected crabapple canopy with less than 6% variations under various illuminations between sunrise and sunset. The results suggested that the performance of the depth camera was adequate for detecting canopy under outdoor conditions for future variable-rate spray applications in ornamental and tree crop production. In addition, the study outlined the performance of the depth camera, which provided a guideline for future applications. Keywords: Machine Vision, Precision Agriculture, Specialty Crop, Stereo Vision, Variable Rate Application.

HighlightsTwelve industrial PWM valves were investigated to manipulate high-pressure agricultural hollow-cone nozzles.Modulation frequencies ranged between 5 and 50 Hz and duty cycles between 10% and 100%.Upstream and downstream pressure profiles were used to determine maximum duty cycle ranges.Two out of 12 PWM valves could be potentially used for future variable-rate orchard sprayer designs.Abstract. Integration of high-speed pulse-width-modulation (PWM) solenoid valves into variable-rate orchard sprayers is needed to accurately regulate spray outputs for matching changes in plant canopy structure characteristics. Capability of 12 PWM valves to modulate hollow-cone nozzles for variable-rate applications was investigated with PWM frequencies of 5 to 50 Hz and duty cycles of 10% to 100%. The PWM valves were assembled on a laboratory spray system with a hollow-cone disc-core nozzle of 2.84 L min-1 flow capacity operated at 1380 kPa pressure. The upstream and downstream pressures on the PWM valves were recorded and analyzed to determine the maximum functional duty cycle ranges and maximum PWM frequency at which the PWM valves could manipulate the nozzle functionally. Test results showed that there were noticeable differences in the modulation capability among the 12 PWM valves due to their design differences. Two out of 12 valves were able to manipulate the hollow-cone nozzles with duty cycles ranging from 30% or 40% to 70% at the modulation frequency of 40 Hz. These two PWM valves performed the highest capability among the 12 valves to manipulate the hollow-cone nozzle. As a result, these two valves would be selected for future investigations on their flow rate modulation accuracy and droplet size distributions before they could be recommended for adaptation in the variable-rate orchard sprayers. Keywords: Duty cycle, Flow control, Orchard sprayer, Pesticide, Precision farming, Pulse width modulation.

New spraying systems embedded with different technologies have been developed for pesticide application in 3D crops. However, while applied to specific tree crops, the potential spray drift mitigation for advanced spraying systems needs to be classified due to the great variability of spray equipment and canopy structure. Here a precision spraying system was developed and compared with two typical spraying systems (conventional system, optimized system following the best management practices) for the applied volume/pesticide and spray drift in an apple orchard at two growth stages following the ISO22866-2005 protocol. Compared to the conventional system, the other two advanced systems significantly reduced the amount of ground drift (>60%) at most of the sampling distances at the growth stage BBCH 72, while the precision system demonstrated the best drift mitigation (57.3% reduction) at the stage BBCH 99. For the airborne drift, a remarkable drift reduction was also achieved with the two advanced systems. Specifically, the optimized spraying system exhibited a drift reduction by approximately 80% at the first growth stage, and the precision application demonstrated its considerable advantages in minimizing drift loss for the sparse canopy at the stage BBCH 99. Moreover, the saving of applied volume/pesticide was achieved by 12% with the optimized system and 43% with the precision system. This study revealed the necessity and prospect of the advanced spraying systems to reduce the environmental contamination and health risk from pesticide applications in fruit tree production. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 773718 (OPTimised Integrated pest Management for precise detection and control of plant diseases in perennial crops and open-field vegetables, www.optima-h2020.eu). Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.

HighlightsInduction charging of water droplets by an ESS showed greatest CMRs using an 80° tapered edge flat spray nozzleCMR of 0.578 mC kg-1 achieved with a water mass flow rate of 0.397 kg min-1 and an applied voltage of -11.6 kVChanges in water conductivity did not significantly affect measured droplet CMRsAbstract. Particulate matter (PM) is a prominent air pollutant in poultry facilities. One promising technology for PM mitigation in poultry facilities is the electrostatic spray scrubber (ESS). However, there is a significant lack of information on the charging characteristics of an ESS to promote efficient droplet charging and poultry PM collection. This study quantified the effects of applied voltage, water mass flow rate, water conductivity, and spray pattern on the charge-to-mass ratio (CMR) of droplets charged by a ring-shape electrode during induction. Voltages from -5 to -14 kV were applied to a 100 mm diameter, cylindrical copper electrode ring to charge droplets sprayed from different nozzles using 80° hollow cone, 80° tapered edge flat, and 110° tapered edge flat spray patterns. It was found that CMRs increased with greater negative voltages up to a point, after which greater negative voltages would decrease the CMR. A similar trend was observed for the effects of water mass flow rate on CMR. Water conductivity showed inconsistent effects on CMR across spray patterns and was deemed a statistically significant but practically insignificant factor. The 80° tapered edge flat spray pattern was found to produce the greatest CMRs. A linear regression model (R2 = 0.865) was developed and optimized to find the ESS configuration resulting in the greatest droplet CMR. The optimal CMR was 0.578 mC kg-1, produced using an 80° tapered edge flat spray nozzle at a water mass flow rate of 0.397 kg min-1, a conductivity of 0.05 S m-1, and an applied voltage of -11.6 kV. Keywords: Droplet charging, Electrostatic scrubber, Electrostatic sprayer, ESS, Induction charging, Spray charging, Spray nozzle.

HighlightsCrop production practices, spray drift control, and sprayer productivity affect spray penetration into dense crop canopies.Question is raised whether airflows near foliar surfaces or within the canopy can assist spray penetration under windy conditions.Current structural descriptions of canopies do not accommodate droplet trajectories to improve spray application.New nozzle tip designs, sensors, and air-assisted spraying need tuning to improve spray penetration and deposition.Abstract. The objective of this study was to review representative publications for improved knowledge of spraying dense field crop canopies to augment the current understanding of the interaction between target foliage characteristics, spray practices, and the environment. Emphasis was placed on measured deep-canopy spray deposits made by full-scale sprayers and studies of airflow within and around crop canopies. Airflow could act as a spray droplet carrier and/or indicator of the internal canopy structure that restricts droplet penetration. High variation in natural airflows was noted in several studies. Crop canopy descriptions for spray studies were generally limited to overall canopy/row dimensions, descriptions of individual plant structures, leaf shapes, and leaf area index. Few studies evaluated the internal canopy “openness” with characteristic shape and size of internal volumes that would accommodate spray droplet trajectories. There have been significant increases in available spray tip designs with multiple orifices, discharge configurations, and droplet sizes that offered the applicator many choices. Advanced sprayer technologies ranging from nozzle control to sensor navigation are available, provided that suitable algorithms can be developed in a timely manner that pertain to a wide variety of spray and crop conditions. The air-assist technique provides a dynamic alternative to traditional over-the-top sprays for increasing spray penetration and deposit, advocating that the specifics of air discharge, spray droplet sizes, and canopy structure can be integrated. The complexity of the spraying process needs an extensive collaborative effort of many stakeholders to develop solutions for sprays to penetrate foliage that is subject to diseases and pests. Keywords: Air-assisted sprayer, Airflow, Boom sprayer, Canopy openness, Droplet trajectory, Foliar canopy, Foliar density, Row crops, Spray blockage, Spray coverage, Spray deposit, Spray nozzles.

Highlights A LiDAR-guided automatic airflow control system for precision sprayers was developed. Three models were built to measure the amount of airflow required for apple trees. The study confirmed that adjusting the fan inlet could control airflow penetration into tree canopies. Results suggest that the system can reduce spray drift and off-target losses. Abstract. The airflow discharged from orchard airblast sprayers is a primary component for successfully carrying spray droplets to the target trees. Because of the variation in orchard tree canopies, control of the airflow to minimize off-target loss during spray application is essential. An automatic airflow control system for precision sprayers was developed to maximize spray droplet coverage on targets and minimize off-target loss while considering the tree canopy densities. The primary component of the system was an iris damper, which was designed as a retrofit attachment on the fan inlet of a three-point airblast intelligent sprayer. A 3D light detection and ranging (LiDAR) sensor was installed at the top of the sprayer to acquire the tree canopy data. A motor was employed to control the damper opening with a micro-controller. To develop the models required for automatic airflow control, field experiments were conducted at three canopy density orchards with different cultivars (GoldRush, Gala, and Fuji). A total of 15 trees (five trees from each cultivar) were randomly selected, and five different damper openings (openings 1, 2, 3, 4, and 5) were tested for each tree. Opening 1 represented the same air inlet as a traditional precision airblast sprayer, while openings 2, 3, 4, and 5 were the sequentially reduced air inlets of the sprayer. A canopy density measurement algorithm was scripted to measure the canopy point density of individual trees. Three models were built to show relationships between (1) tree canopy point densities and airflows; (2) canopy densities and damper openings; and (3) damper opening and motor steps. The combination of the two models (2 & 3) was used to assess the amount of airflow required for a specific canopy density. Field validations for medium and high-density trees showed that the system achieved adequate spray penetration at the top, middle, bottom, back-left, and back-right positions of the tree sections and reduced off-target loss at the ground and edge of next row sections using openings 4 and 2, respectively. However, the mechanical motion of the damper required 3 s to move from minimum to maximum opening, so the average canopy density was recommended to control the airflow. The overall results suggested that the automatic airflow control system could reduce spray drift and off-target losses and improve spray application efficiency in orchards. Keywords: Automation, Canopy sensing, Fan inlet, Precision spraying, Variable rate application.

Highlights Developed a stereo vision spray controller with a single board computer for precision sprayers. Developed algorithms to process stereo vision data, calculate spray volumes, and activate spray nozzles. Developed a graphical user interface to embed algorithms and operate the controller. Controller detected target volume and sprayed target in real time at various travel speeds before target was on spray area. The spray controller consumed 111 to 141 ms to acquire and process data and determine spray output. Abstract. Under laboratory conditions, a variable rate spray controller using stereo vision as a target detection sensor was developed and evaluated with moving spray targets at travel speeds ranging from 3.2 to 8.0 km h-1. The controller detected the target with a resolution of 480 pixels (vertical) × 640 pixels (horizontal) at a frame rate of 5 Hz and modulated spray nozzles at 10 Hz based on the analysis results of the stereo vision data. A customized graphical user interface was developed to operate the controller, display incoming data, and control other components. Evaluations of the controller with a flat, 3-dimensional box column and artificial tree targets with travel speeds ranging from 3.2 to 8.0 km h-1 showed that the controller consistently activated the nozzles 158.7 to 293.6 ms before the spray target arrived on the spray axis. The controller was also capable of repeatedly detecting the volume of the spray target with variations less than 12% for the same target at one travel speed, although it measured the volume generally higher than the manually calculated volume by as much as 33%, which resulted from duplicate target detection between detection cycles of the controller. These duplicated detections caused the overapplications of as much as 38%, although the controller repeatedly discharged spray volumes with variations less than 11% for the same target at the same travel speed. On average, the spray controller required 111.2 to 140.7 ms for data processing in one detection cycle, from image acquisition to activating spray nozzles for travel speeds ranging from 3.2 to 8.0 km h-1, with the potential to reduce this further. The developed controller would provide an economical and versatile platform for future variable rate sprayers with the benefits of stereo vision technology. Keywords: Automation, Crop protection, Precision Agriculture, Pesticide, RealSenseTM.

HighlightsVolumetric diameters DV0.1, DV0.5, and DV0.9 for PWM-controlled hollow-cone nozzles were investigated.Droplet sizes were influenced greatly by nozzle size, operating pressure, duty cycle, and slightly by PWM valve type.Volume fractions were reported for droplets smaller than 100 µm, between 100 and 300 µm, and greater than 300 µm.Measured droplet sizes were classified as different categories based on the ASABE standard 572.3.Abstract. Integration of variable-rate disc-core nozzles in orchard sprayers is the optimal solution to achieve precision spray applications of agrochemicals; however, little information is available on the droplet size distribution and classification for these hollow-cone nozzles. Investigations were performed for the comprehensive understanding of spray droplet size spectrum discharged from hollow-cone nozzles which were manipulated with pulse width modulation (PWM) valves to produce variable flow rates. Test variables included five disc-core hollow-cone nozzle sizes (D2-DC25, D2-DC45, D4-DC25, D4-DC45, and D5-DC25), two 10-Hz PWM valve designs, five operating pressures (276, 414, 552, 689, and 827 kPa), and 10 duty cycles (DUCs) ranging from 10% to 100% at 10% intervals. Droplet diameters were measured with a laser imaging particle system. Volumetric diameters (DV0.1, DV0.5, and DV0.9) varied greatly with the nozzle orifice size, operating pressure, and DUC, and varied slightly by PWM valve type. Higher operating pressures and larger nozzles generated droplets with more consistent size distributions across DUCs from 10% to 100%. The differences in relative spans among DUCs increased with the nozzle size increase and the operating pressure decrease. Droplet size classifications from very fine to coarse, based on ASABE 572.3 standard definitions, varied with the nozzle size and operating pressure but were similar for two PWM valve designs at all DUCs. Spray volume fractions also varied with the droplet size range, DUC and pressure. For droplets smaller than 100 µm, the volume fraction remained relatively consistent or slightly decreased as DUC increased, but increased as the pressure increased. In comparison, the fraction increased as both DUC and pressure increased for droplets between 100 and 300 µm and decreased for the portion of droplets greater than 300 µm. As a result, the discovered information would be implemented for the improvement of precision variable-rate spray systems equipped with PWM valves. Keywords: Atomization, Droplet diameter, Orchard sprayer, Precision agriculture, Variable rate.

HighlightsSimple low-cost microcontroller-based device was developed to measure ASP® 602 concentrations of residue samples from ISO 22368 tests.Sensitivity analysis showed the device was able to detect ASP® 602 concentrations as low as 22.5 ppm depending on sample variations.Various prediction models were built from the output of the device and validated to understand their accuracy and measurement variations.Logarithmic prediction model showed approximation errors from 3.9% to 19.7% with CV of 7.7% to 19.8% for the ASP® 602 concentration range from 0 to 250 ppm.Abstract.A simple microcontroller-based device with operating software was developed for analyzing samples from ISO 22368 sprayer cleanout tests. The device could measure ASP® 602 concentrations of residue samples from the sprayer cleanout tests with measurement variations, a coefficient of variations (CV), less than 4%. Sensitivity analysis of the device carried out to understand the measurement limits, and the results showed that the limit of quantification of the device was 22.5 ppm with sample variations which was sufficient for assaying residue samples from ISO 22368 tests. The measurement variations of the device were also affected by homogeneity of the samples. Several prediction models were developed with the device outputs, and prediction accuracy (approximation error) and measurement variations (CV) of the models were validated with additional ASP® 602 samples. The prediction results from the models had a wide range of approximation errors and the results showed approximation errors from 2.6% to 26.2% with CV from 3.0% to 33.4% with the models for a prediction ranges from 0 to above 500 ppm, while considering the results above limit of quantification. The models for a prediction range from 0 to 250 ppm showed the error from 3.9% to 19.7% with CV from 7.5% to 27.5%, under the same consideration. The logarithmic prediction model with the prediction range from 0 to 250 ppm showed most acceptable performance in terms of approximation error and CV that were less than 20%, when considering the results within limit of quantification. Keywords: Kaolin Clay , ISO Standard, Photodiode, Spectrophotometer, Spraying equipment.

Electrostatic sprayers can be an option for increasing the effectiveness of treatments and reducing pesticide consumption, but it still requires more verifications, especially in orchards. The spray deposition performances of three different electrostatic sprayers design were compared for apple tree pesticide application, all of them used with the electrostatic system activated and disactivated, as conventional spray application. Despite designs of particular type sprayers were unique, no significant differences were observed in the normalized deposition and droplets density between the conventional and electrostatic spray methods of the same sprayer, but differences were found between the vertical boom and the pneumatic sprayer in terms of coverage. The normalized deposition values of the three sprayers were very similar, ranging between 1.0 and 1.5¿µg¿cm-2. However, the vertical boom sprayer produced the highest spray coverage, followed by the multi-fan sprayer. In general, the measured values of coverage and deposit obtained were in the three cases similar, independently on the use or not of the electrostatic device, being the sprayer type more affecting parameter rather than the electrostatic charging system. Differences in spray deposition qualities on apple trees were observed among three types of sprayers, but were not for the same sprayer with and without activation of the electrostatic charging system. Appropriate design of orchard sprayers according to the canopy structure seems to be more effective rather than the implementation of electrostatic spray charge system to achieve the European challenge of 50% reduction of pesticides by 2030.

Nursery producers are challenged with growing a wide range of species with little to no detectable damage from insects or diseases. Growing plants that meet consumer demand for aesthetics has traditionally meant routine pesticide application using the most time-efficient method possible, an air-blast sprayer, despite its known poor pesticide application efficiency. New variable-rate spray technology allows growers to make more targeted applications and reduce off-target pesticide loss. In this study, a prototype laser-guided variable-rate sprayer was compared with a traditional air-blast sprayer. Pesticide volume, spray application characteristics, and the control of powdery mildew were evaluated over the course of two growing seasons. Spray application characteristics were assessed using water-sensitive cards (WSCs) and DepositScan software. This prototype sprayer reduced pesticide volume by an average of 54% across both years despite being tested against a low rate (−1). In 2016, the conventional sprayer had more than double the deposit density on target WSCs among distal trees than the variable-rate sprayer; however, within proximal trees, there was no difference between the two sprayer types. In 2017, when the trees were larger, within both the distal and proximal trees, the conventional sprayer had greater deposit density on target WSCs than the variable-rate sprayer. In 2016, coverage on target WSCs was nearly 7-fold greater with the conventional treatment than with the variable-rate treatment. In 2017, when trees were larger, there was greater coverage on target WSCs in proximal trees (3.8%) compared with those in distal trees (1.0%) regardless of the sprayer type. This variable-rate spray technology provided acceptable control of powdery mildew severity on individual branches and whole trees and maintained the incidence of powdery mildew to levels comparable to that occurring among trees sprayed with a traditional air-blast sprayer. Therefore, the variable-rate spray technology has the potential to effectively control disease, dramatically reduce the pesticide footprint, and preserve natural resources such as ground and surface water, soil, and beneficial insects found within and around nurseries.

Particulate matter (PM) emissions constitute a major air pollution concern for commercial poultry production facilities. Recently, the electrostatic precipitator (ESP) has emerged as a promising technology for mitigation of poultry PM. However, further optimisation of ESP design, operation scale, and operating parameters is necessary for improved PM removal efficiencies and practical applications in poultry facilities. In this study, a comprehensive model of the poultry PM collection process in a simulated ESP module was developed using COMSOL software. The model simulated airflow characteristics, electric field and space charge development, particle charging, and particle trajectory tracking of both PM10 and PM2.5. Wire-plate ESP configurations with varying design parameters, such as number of wire electrodes and plate separation distance, were simulated using the COMSOL model at an inlet air velocity of 2.0 m s−1 to identify the optimal configuration for development of ESP physical prototypes. The model was validated by laboratory testing of a prototype ESP within a wind tunnel under three sets of ventilation conditions representing hot, warm, and cold weather, respectively. The prototype ESP exhibited PM10 collection efficiencies of 90.8%, 97.1%, and 99.0% in hot, warm, and cold weather conditions, respectively. The observed PM2.5 collection efficiencies under these respective conditions were 86.9%, 94.4%, and 97.8%. This COMSOL model can be used as an inexpensive alternative to developing physical prototypes when evaluating ESP designs for PM mitigation in poultry facilities.

Various faults will occur in the power grid during operation, among which the system short-circuit fault is the most common. The introduction of the photovoltaic system has changed the structure of the power grid. The power grid is no longer the original single-source radial structure, but becomes a dual-end or multi-end power grid, thus changing the size, direction, and duration of fault current. It is helpful to study the current output characteristics of photovoltaic systems in a short circuit for the study of the power grid. Therefore, this paper builds a grid-connected photovoltaic generator model on the DigSILENT simulation tool to study the output characteristics in a short circuit. The models are simulated under different conditions of three-phase short circuit, two-phase short circuit, and single-phase short circuit. Through analysis, it is concluded that the current characteristics of distributed generation with a power electronic interface are related to the design of the interface and the control method of an interface when a short circuit occurs.

Droplet charging is an effective method to enhance dust removal efficiency using an electrostatic spray scrubber (ESS). However, effects of the materials and dimensions of different electrodes on droplet charging efficiency have not been studied systematically. In this study, ring-shaped electrodes were selected to test effects of three types of electrode materials (copper, stainless steel, and graphite) with various dimensions on droplet charging efficiency. A Faraday pail charge measurement device was used to measure the droplet charge generated by the electrodes. A reduced factorial design with four factors was used in this study to investigate the charging efficiency affected by the factors. The four factors tested were electrode material, electrode diameter, nozzle height, and applied voltage. A 304L stainless steel electrode was found to achieve higher droplet charge-to-mass ratio (CMR) values than identically shaped electrodes made from either copper or graphite. The optimal stainless steel electrode inner diameter was 100 mm. The 304L stainless-steel electrode with this optimal diameter and a height of 45 mm achieved the highest mean CMR of 0.435 ± 0.002 mC kg

Background Emerging evidences have highlighted the roles of neutrophils, as the major host microenvironment component, in the development of hepatocellular carcinoma (HCC). Neutrophils extracellular traps (NETs) produced in the infection can strengthen the behavior of cancer metastasis. Here, we investigated the roles of NETs in HCC metastasis and further explore the underlying mechanism of how NETs interact with cancer. Methods The neutrophils were isolated from whole blood of HCC patients and used to evaluate the formation of NETs. NET markers were detected in tissue samples, plasma and cell climbing slice. Mouse models were used to evaluate the roles of NETs in HCC metastasis in vivo, and the corresponding mechanisms were explored using in vivo and in vitro assays. Results An increase in the release of NETs in patients with HCC, particularly those with portal vein tumor thrombosis (PVTT). The presence of NETs in HCC tumor tissues closely correlated with a poor prognosis. Functionally, the invasion ability of HCC cells was enhanced by co-culture with HCC neutrophils, through NETs formation, while the neutrophils from a healthy donor (HD) exhibited the inhibition of the invasion ability. Furthermore, we observed an enhanced ability of forming NETs in neutrophils from HCC patients in vitro, especially patients with PVTT or extra-hepatic metastasis. An in-vivo animal study demonstrated that neutrophils of HCC facilitated the metastatic behavior towards the lung. The further mechanistic investigation unveiled that HCC cells-derived cytokine IL-8 triggered NETs formation in an NADPH oxidase-dependent manner, and NETs-associated cathepsin G (cG) promoted HCC metastasis in vitro as well as vivo. Clinically, the expression of the cG protein in tumor tissues displayed a close correlation with the disease prognosis of HCC patients. Conclusion Our findings implicated that the induction of NETs by HCC cells is a critical metastasis-supporting cancer-host interaction and that NETs may serve as an immune-based potential therapeutic target against HCC progression.

HighlightsRetention and spread of droplets with seven adjuvants were investigated on flat leaves.Surface tension of spray solutions, leaf wettability, and roughness strongly affected droplet retention and spread.Complete droplet retention occurred on hydrophilic leaves with all adjuvants and concentrations.High retention and spread on superhydrophobic leaves were achieved with the organo-silicone adjuvant.No retention occurred on superhydrophobic leaf surfaces with the hydrocolloid polymer adjuvant.Abstract. To optimize spray application efficiency, it is necessary to understand how the addition of adjuvants modifies the deposition properties of spray droplets on leaf surfaces due to variations in adhesive characteristics, such as roughness and wettability. Retention and spread of droplets with seven commercially available adjuvants were tested and compared at different concentrations. Tests were conducted with three leaf surfaces ranging in roughness and wettability from very smooth and hydrophilic to very rough and superhydrophobic. The adjuvants were formulated with non-ionic surfactant, crop oil, seed oil, organo-silicone, hydrocolloid polymer, or combinations of these agents as primary ingredients. Droplets of approximately 340 µm diameter were emitted from a streamed mono-sized generator. Droplet impact and spread were recorded with a 3D imaging system consisting of three high-speed digital cameras and analyzed using 3D motion analysis software. Retention and spread were determined by comparing droplet liquid volumes and droplet cross-sectional areas before and after impact, respectively. The surface tension of spray solutions and wettability of leaf surfaces strongly affected droplet retention. Droplets with lower surface tension were more likely to achieve high retention than those with higher surface tension. Droplet retention generally decreased with increasing leaf roughness-wettability. All droplets with and without adjuvants achieved 100% retention on the hydrophilic leaf surface. Addition of non-ionic, oil, or organo-silicone based adjuvants in the spray solution improved droplet retention on hydrophobic leaves, while the organo-silicone based adjuvant achieved the highest retention on superhydrophobic leaf surfaces. Droplet retention with the hydrocolloid polymer adjuvant was generally comparable to the other six adjuvants on the hydrophilic leaves and on the hydrophobic leaves with intermediate roughness and wettability but failed to achieve any retention on the superhydrophobic leaves. To improve droplet retention and adhesion, selection of adjuvants representing the non-ionic, oil, organo-silicone, blended, or hydrocolloid-based additives for enhancing spray solution performance must comply with the leaf surface characteristics. Keywords: Droplet rebound, High-speed imaging, Leaf wettability, Pesticide droplet deposition, Topography parameters.