Volume Median Diameter Research Articles

Effects of sand grain roughness height on the performance of wind turbine blade section under extreme weather conditions

Wind turbine blades are prone to icing and their performance is affected significantly by the roughness caused by icing and erosion. Numerical models are constructed to simulate the effects of sand grain roughness on the mass of accreted ice and aerodynamic performance. The sand grain roughness height is considered by applying the NASA and Shin et al. models, and the cloud characteristics studied are the liquid water content (LWC), median volume diameter (MVD) and air temperature covering freezing drizzle and in-cloud icing conditions resulting in glaze ice and rime ice, respectively. The numerical model applied the multi-shot approach, and the effects of the number of shots on the ice accretion and aerodynamic performance was examined to determine the optimum number of shots which can be used in the simulation in order to minimize the computational time without affecting the accuracy. The relationship between the sand grain roughness height and aerodynamic performance is studied, revealing that the shallowest roughness heights cause less performance degradation. The mass of ice increases with increasing LWC from 0.05g/m3 to 0.3g/m3 and MVD from 20 µm to 100 µm, which results in a reduction in the lift-to-drag ratio (CL/CD).

Inhalable nano-structured microparticles for extracellular matrix modulation as a potential delivery system for lung cancer

The use of inhalable nanoparticulate-based systems in the treatment of lung cancer allows for efficient localized delivery to the lungs with less undesirable systemic exposure. For this to be attained, the inhaled particles should have optimum properties for deposition and at the same time avoid pulmonary clearance mechanisms. Drug delivery to solid tumors is furthermore challenging, due to dense extracellular matrix (ECM) formation, which hinders the penetration and diffusion of therapeutic agents. To this end, the aim of the current work is to develop an ECM-modulating nano-structured microparticulate carrier, that not only enables the delivery of therapeutic nanoparticles (NPs) to the lungs, but also enhances their intratumoral penetration. The system is composed of acetalated maltodextrin (AcMD) NPs embedded into a water-soluble trehalose/leucine matrix, in which collagenase was loaded with different mass concentrations (10 %, 30 % and 50 %). The collagenase-containing AcMD nano-structured microparticles (MPs) exhibited suitable median volume diameters (2.58 ± 1.35 to 3.01 ± 0.68 µm), hollow corrugated morphology, sufficient redispersibility, low residual moisture content (2.71 ± 0.17 % to 3.10 ± 0.20 %), and favorable aerodynamic properties (Mass median aerodynamic diameter (MMAD): 1.93 ± 0.06 to 2.80 ± 0.10 µm and fine particle fraction (FPF): 68.02 ± 6.86 % to 69.62 ± 2.01 %). Importantly, collagenase retained as high as 89.5 ± 6.7 % of its enzymatic activity after spray drying. MPs containing 10 % mass content of collagenase did not show signs of cytotoxicity on either human lung adenocarcinoma A549 cells or lung MRC-5 fibroblasts. The nanoparticle penetration was tested using adenocarcinoma A549/MRC-5 co-culture spheroid model, where the inclusion of collagenase resulted in deeper penetration depth of AcMD-NPs.

Knapsack air assisted electrostatic sprayer for agricultural formulations

An experimental prototype of a backpack-type rechargeable battery-powered air-assisted electrostatic sprayer was designed and tested for performance while preserving techno-commercial competence and affordability for India's marginal and small farmer communities. The designed prototype electrostatic sprayer achieved good levels of charge induction on the spray particles at various electrode potentials (1 to 12 kV). At a charging electrode potential of 9 kV and a nozzle discharge rate of 2 mL s−1, electrostatically charged spray had a maximum charge to mass ratio (CMR) of 1.79 mC kg−1. The Electric Ducted Fan (EDF) used for high velocity air assistance was capable of transporting charged spray droplets onto distant targets such as orchard trees and field crops with a spray throw of up to 5 m. The high-pressure atomization method produced fine droplets within a Volume Median Diameter (VMD) range of 90 to 100 µm, resulting in better charge induction and wrap-around effect. As the prototype features fewer moving mechanical components, reduced total noise and vibrations, it promises operator comfort in the long run while requiring less system maintenance. Environmental contamination can be minimized as the large quantity of harmful chemicals be prevented from drifting into the soil and nearby waterbodies. The competitive performance and lower investment could encourage majority of the Indian famers to upgrade with the developed air assisted electrostatic spraying system contributing to agro-socio-economic welfare.

Changes of vertical distribution of Microcystis colonies driven by short-term rainfall: Disappearance and reformation of surface bloom

Global climate warming and human activities have increased the magnitude and frequency of Microcystis surface blooms, posing significant threats to freshwater ecosystems and human health over recent decades. Heavy rainfall events have been reported to cause the disappearance of these blooms. Although some studies have employed turbulence models to analyze the movement characteristics of Microcystis colonies, the impact of rainfall is complex, comprehensive investigations on their vertical migration induced by short-term rainfall are still necessary. Utilizing monitoring data from eutrophic ponds and controlled simulation experiments, this study examines the short-term impacts of rainfall on the vertical distribution of Microcystis in the water column. Our findings indicate that rainfall contributes to the disappearance of Microcystis blooms by reducing the quantity of small to medium-sized colonies (0–100 μm) at the surface, subsequently decreasing the overall Microcystis biomass. As rainfall intensity increases, larger colonies migrate deeper into the water column. At a rainfall threshold of 666 mm, the difference in the median volume diameter (DV50) of Microcystis colonies between the surface and bottom reaches a minimal value of 3.09%. Post-rainfall, these colonies rapidly ascend, aggregate into larger formations, and re-establish surface blooms. The greater the rainfall, the smaller the resultant Microcystis biomass, albeit with larger aggregated colony sizes. When rainfall exceeds 222 mm, the recovery rate of surface Microcystis biomass remains below 100%, decreasing to 19.48% at 666 mm of rainfall, while the median volume diameter (DV50) of the colonies increases to 139.07% of its pre-rainfall level. Furthermore, compared to pre-rainfall conditions, the photosynthetic activity of the surface Microcystis colonies was enhanced and the secretion of EPS was increased under heavy rainfall conditions. Our results identify a critical response time of 30 min for Microcystis colonies to rainfall, after which the response ceases to intensify. These insights are crucial for predicting post-rain Microcystis bloom dynamics and aiding management authorities in timely interventions.

Supercooled large droplet size distribution effects on airfoil icing: A numerical investigation based on a new coupled Eulerian method

Supercooled large droplets (SLDs) under natural icing conditions have the characteristics of easy deformation in motion and easy splashing on impact, and a bimodal droplet size distribution that has received less attention. The modified form of the Rosin-Rammler function was improved to achieve a more accurate nonlinear fitting of the SLD distribution curve. The droplet size distribution was divided into non-equipartition continuous multiple components. The drag source term of each component was coupled with the overall droplet size distribution, and the Eulerian equations of each component of SLDs were solved simultaneously. A new coupled Eulerian method for non-equipartition continuous multi-size droplets was proposed to simulate the impact characteristics of SLDs, and the SLD collection coefficients were validated. Effects of the ratio between the number of large and small droplet components and the number of all components on the simulation results were investigated to select a better combination based on stable convergence calculation steps and the calculation time. This new method was added to the multi-step icing numerical method, and the accuracy and robustness of the method in icing shape prediction were verified based on the freezing drizzle, median volume diameter < 40 μm (FZDZ, MVD < 40 μm) icing condition. Airfoil icing characteristics based on the bimodal and monomodal distribution were compared, and the icing shapes at the leading edge were similar. Still, the upper and lower limits of the icing shapes with the bimodal distribution were nearer to the trailing edge and the ice layer was thicker there.

Design and experimental research of air-assisted nozzle for pesticide application in orchard.

This article reports the design and experiment of a novel air-assisted nozzle for pesticide application in orchard. A novel air-assisted nozzle was designed based on the transverse jet atomization pattern. This article conducted the performance and deposition experiments and established the mathematical model of volume median diameter (D50) and liquid flow rate with the nozzle design parameters. The D50 of this air-assisted nozzle ranged from 52.45 μm to 113.67 μm, and the liquid flow rate ranged from 142.6 ml/min to 1,607.8 ml/min within the designed conditions. These performances meet the low-volume and ultra-low-volume pesticide application in orchard. The droplet deposition experiment results demonstrated that the droplet coverage distribution in different layers and columns is relatively uniform, and the predicted value of spray penetration (SP) numbers SPiA , SPiB , and SPiC (i = 1, 2, and 3) are approximately 70%, 60%, and 70%, respectively. The droplet deposits on the foliage of the canopy (inside and outside) uniformly bring benefit for plant protection and pesticide saving. Compared with the traditional air-assisted nozzle that adopts a coaxial flow atomization pattern, the atomization efficiency of this air-assisted nozzle is higher. Moreover, the nozzle air pressure and liquid flow rate are considerably lower and greater than the traditional air-assisted nozzle, and these results proved that this air-assisted nozzle has great potential in orchard pesticide application. The relationship between the D50 and nozzle liquid pressure of this air-assisted nozzle differs from that of traditional air-assisted nozzles due to the atomization pattern and process. While this article provides an explanation for this relationship, further study about the atomization process and mechanism is needed so as to improve the performance.

Study on influence of turbulence intensity on blade airfoil icing mass & aerodynamic performance

Wind is an emerging renewable energy resource, but more useful in cold regions. With the increasing threat of climate change and global warming, the unpredictability of wind energy patterns has been affected. With continual threats from extremes and uncertainties, icing on wind turbines has been noted to grow affecting aerodynamic performance. The effect of turbulence intensity at its impact on aerodynamic performance was numerically done using ANSYS Fluent and FENSAP ICE software. Conditions considered for the study included turbulence intensities, median volume diameter (MVD), liquid water content (LWC), angle of attack, and ambient temperature for 180 min. The study's conditions aimed at providing a wide range of effects covering the in-cloud icing and freezing drizzle. The mass of ice increased with an increase in LWC when it increased from 0.05 g/m3 to 0.3 g/m3, and MVD with 1000 μm compared to 40 μm, but when temperature decreased led to an increase from −1 °C to −15 °C. Increasing the angle of attack led to reduced aerodynamic performance with stall angle occurring at α = 0–18°. An increase in the turbulence intensity from 0.01 % to 50 % resulted in decreased CL/CD.

Exploring the statistical characteristics of coastal winter precipitation measured using a Parsivel2 disdrometer: A case study in North Carolina

A drop size distribution (DSD) of a precipitation event is a key characteristic and plays a critical role in quantitative precipitation estimation. In this study, DSD datasets were collected by a Parsivel2 disdrometer in Elizabeth City, North Carolina, U.S. from October 2021 to April 2022. The microphysical and statistical characteristics of the DSD were examined. For this period, the contribution of small raindrops (< 1 mm) to the total number concentration (Nt) was the largest, while the contribution of large raindrops (3―8 mm) to Nt was the smallest. As expected, large raindrops had the largest impact on rain rate (R), liquid water content (W), and radar reflectivity factor (Z), while small raindrops had the least. The shape of the averaged DSDs was similar for different rain rates while the width of the raindrop concentration spectrum increased as rain rates increased. The average mass-weighted diameter Dm (log10Nw, generalized intercept parameter) value for all rain events was found to be 1.11 mm (4.54), while for stratiform rains Dm was 1.18 mm (4.65), and for convective rains, it was 0.89 mm (4.17). The empirical relationships between rain intercept parameter (N0) vs shape factor (μ), μ vs slope factor (Λ), log10Nw vs median volume diameter (D0), D0 vs R, R vs kinetic energy (KE), and Z―R relationship were also derived. These findings are useful for design of rainfall simulators and for better understanding erosive properties of rainfall that contribute to contaminant fate and transport.

Fine excipient materials in carrier-based dry powder inhalation formulations: The interplay of particle size and concentration effects

The contributions of fine excipient materials to drug dispersibility from carrier-based dry powder inhalation (DPI) formulations are well recognized, although they are not completely understood. To improve the understanding of these contributions, we investigated the influences of the particle size of the fine excipient materials on characteristics of carrier-based DPI formulations. We studied two particle size grades of silica microspheres, with volume median diameters of 3.31 μm and 8.14 μm, as fine excipient materials. Inhalation formulations, each composed of a lactose carrier material, one of the fine excipient materials (2.5% or 15.0% w/w), and a drug (fluticasone propionate) material (1.5% w/w) were prepared. The physical microstructure, the rheological properties, the aerosolization pattern, and the aerodynamic performance of the formulations were studied. At low concentration, the large silica microspheres had a more beneficial influence on the drug dispersibility than the small silica microspheres. At high concentration, only the small silica microspheres had a beneficial influence on the drug dispersibility. The results reveal influences of fine excipient materials on mixing mechanics. At low concentration, the fine particles improved deaggregation and distribution of the drug particles over the surfaces of the carrier particles. The large silica microspheres were associated with a greater mixing energy and a greater improvement in the drug dispersibility than the small silica microspheres. At high concentration, the large silica microspheres kneaded the drug particles onto the surfaces of the carrier particles and thus impaired the drug dispersibility. As a critical attribute of fine excipient materials in carrier-based dry powder inhalation formulations, the particle size demands robust specification setting.

Measurement of droplets characteristics of UAV based spraying system using imaging techniques and prediction by GWO-ANN model

Modern agriculture relies on pesticides to increase crop yields, but these chemicals are also hazardous. Although conventional sprayers were designed for effective pest management, they nonetheless pollute the environment and endanger operators' health. Unmanned aerial vehicle (UAV)-based sprayers overcome the aforesaid problem and can precisely target the areas that need treatment and difficult to reach for human operators. This study evaluated a UAV-based spraying system in a cotton field, employing imaging techniques such as Laser Droplet Analyzer, Deposit Scan, ImageJ, and Drop leaf. Furthermore, the system was optimized using response surface methodology, and deposition predictive analysis was conducted using a hybrid GWO-ANN approach. The volume median diameter, number median diameter, relative span, and uniformity coefficient were in the range of 95–248 µm, 65–174 µm, 0.8–1.7 %, and 1.3–1.7 %, respectively. Optimizing the working speed (3.3 m/s), working height (1.0 m), and discharge rate (2.0 L/min) resulted in a droplet density of 50.3 droplets/cm2, deposition of 0.20 µL/cm2, and coverage of 9.27 %. The GWO-ANN prediction model yielded R2, RMSE, and MAE values of 0.878, 0.01729, and 0.01368, respectively. Optimizing operational parameters through multiple measurement techniques enhance flexibility and effectiveness of UAV-based spraying system, facilitating wider deployment in remote agricultural areas for agrochemical applications.

Influence of temperature on the process of preparing homogenised magnesium-zinc alloy spherical powders using the relative vacuum method

The production of magnesium-zinc (Mg-Zn) alloy spherical powders is complex and expensive. As they have extensive applications in a wide variety of fields including military manufacturing, aerospace, and biomedicine, there is an urgent need to explore new production processes for Mg-Zn alloy spherical powders. In this study, 5 wt% homogenised Mg-Zn alloy spherical powder was prepared using the relative vacuum method. The effects of the insulation time, maximum temperature, and heating rate on the morphology, size distribution, and particle size of the Mg-Zn alloy spherical powder were investigated. The results indicated that the insulation time had the greatest influence on the particle size of the spherical powder, whereas the maximum temperature and heating rate had significant impacts on the alloy composition. When the insulation time was 10 min the maximum temperature was 1150 °Cand the heating rate was 15 min, the prepared Mg-Zn alloy spherical powder exhibited a full morphology without satellite particles, uniform composition, narrow size distribution, and a volume median diameter (VMD) of 17.62 μm. The research findings provide a new production process for Mg-Zn alloy spherical powders and establish a foundation for studying the specific effects of temperature on the production of Mg-Zn alloy spherical powders using the relative vacuum method.

A parametric study on the effect of liquid water content and droplet median volume diameter on the ice distribution and anti-icing heat estimation of a wind turbine airfoil

This study uses an icing model, combining heat transfer with fluid flow and considering the roughness effect, to investigate the influence of liquid water content (LWC) and droplet median volume diameter (MVD) on the ice distribution and anti-icing heat estimation of a wind turbine blade airfoil through the numerical approach. The findings indicate that the simulated ice distribution can have excellent agreement with experimental data. Owing to variations of droplet collection efficiency and heat flux, the increase in LWC and MVD will amplify the fluctuations in ice accretion distribution, which will be prone to ice horns. Owing to high LWC increasing water film flow range, the jumping point of anti-icing heat flux is closer to the trailing edge. Owing to large MVD increasing droplet collection efficiency, the quantity of ice accumulation through solidification ascends to demand higher anti-icing heat flux. The peak anti-icing heat flux is more evidently influenced by LWC than that by MVD, due to the variations in heat flux, induced by water film evaporation and solidification. The findings offer valuable insights into the flow and heat transfer physics for wind turbine anti/de-icing design.

Aerial spraying for downy mildew control in grapevines using a remotely piloted aircraft

Downy mildew is a major problem for grape growers, as this disease is difficult to control. Synthetic fungicides are used to treat downy mildew with handheld backpack and tractor sprayer applications, with high chemical exposure by operators. As important tools for maximising yield, application technologies must be studied to optimise control efficiency. The objective of this study was to evaluate the efficiency of fungicide spray application using Remotely Piloted Aircraft (RPA) for the control of downy mildew in grapevine, with different spray volumes. The study was divided into two experiments using 4 vine lines, 10 blocks and 5 treatments with different mixture volumes: Experiment 1 with RPA application of 5 mixture volumes - 0, 22, 44, 66, and 88 L ha−1; Experiment 2 with RPA application of 3 mixture volumes - 44, 66, and 88 L ha−1 and a backpack application of one mixture volume - 800 L ha−1. Coverage percentage, droplet density and volume median diameter (VMD) were evaluated. Downy mildew severity on grapevine leaves was assessed using visual analysis and a diagrammatic scale. The application of 44 L ha−1 provided the greatest coverage and droplet density in the upper and middle strata; however, the backpack application had a better droplet distribution than the RPA application. Treatments of 44 L ha−1 with RPA and backpack application (800 L ha−1) provided the best disease control. In the trellis system, RPA application must be improved because of the low coverage in the lower parts of the plant, and further studies with different spray nozzles and application heights are needed.

Microfluidics produced ATRA-loaded PLGA NPs reduced tuberculosis burden in alveolar epithelial cells and enabled high delivered dose under simulated human breathing pattern in 3D printed head models

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), is second only to COVID-19 as the top infectious disease killer worldwide. Multi-drug resistant TB (MDR-TB) may arise because of poor patient adherence to medications due to lengthy treatment duration and side effects. Delivering novel host directed therapies (HDT), like all trans retinoic acid (ATRA) may help to improve drug regimens and reduce the incidence of MDR-TB. Local delivery of ATRA to the site of infection leads to higher bioavailability and reduced systemic side effects. ATRA is poorly soluble in water and has a short half-life in plasma. Therefore, it requires a formulation step before it can be administered in vivo. ATRA loaded PLGA nanoparticles suitable for nebulization were manufactured and optimized using a scalable nanomanufacturing microfluidics (MF) mixing approach (MF-ATRA-PLGA NPs). MF-ATRA-PLGA NPs demonstrated a dose dependent inhibition of Mtb growth in TB-infected A549 alveolar epithelial cell model while preserving cell viability. The MF-ATRA-PLGA NPs were nebulized with the Aerogen Solo vibrating mesh nebulizer, with aerosol droplet size characterized using laser diffraction and the estimated delivered dose was determined. The volume median diameter (VMD) of the MF-ATRA-PLGA NPs was 3.00 ± 0.18 μm. The inhaled dose delivered in adult and paediatric 3D printed head models under a simulated normal adult and paediatric breathing pattern was found to be 47.05 ± 3 % and 20.15 ± 3.46 % respectively. These aerosol characteristics of MF-ATRA-PLGA NPs supports its suitability for delivery to the lungs via inhalation. The data generated on the efficacy of an inhalable, scalable and regulatory friendly ATRA-PLGA NPs formulation provides a foundation on which further pre-clinical testing can be built. Overall, the results of this project are promising for future research into ATRA loaded NPs formulations as inhaled host directed therapies for TB.

Experimental study of the influence factors of the droplet size of rotary nozzles during manned helicopter spraying operations

The droplet size significantly affects the performance of aerial spraying operations. Thus, it is crucial to develop rotary nozzles for helicopter spraying operations and analyze the influence of droplet size. We conducted a calibration test of the nozzle rotation speed to analyze the effects of air velocity, blade installation angle, hub diameter, and blade length on the rotation speed. The results showed that the rotation speed increased with an increase in air velocity and nozzle diameter and decreased with an increase in the blade angle. The rotation speed of three types of rotary nozzles was measured in the range of 576–15 358 r/min. A high-speed wind tunnel test was conducted to determine the droplet size of the rotary nozzles at different rotation speeds, spray flow rates, and hub mesh numbers. The influence degree of the three factors on the droplet size was rotation speed > spray flow rate > mesh number. The multiple linear regression equation of the volume median diameter (VMD) of the droplet size was obtained. The droplet size obtained from wind tunnel and flight tests at 5000 and 7000 r/min was compared. The droplet size was in the range of 148.56–259.39 μm and was slightly larger under wind tunnel conditions than during the flight test. The relative width of the droplet spectrum was small for both test methods, indicating that the droplet size distribution of the three rotary nozzles was uniform. Finally, the spray nozzles were used for insect control in forest areas and achieved a control efficiency of 94.6. This study provides a reference for optimizing the operating parameters of spraying nozzles and improving the performance of helicopter-based low-volume spraying operations.

Evaluation of Remotely Piloted Aircraft for Agricultural Spraying in Corn Cultivation in the Brazilian Savannah

This study aimed to evaluate the quality of application using both RPA and ground techniques in corn cultivation using different spray nozzles in Brazilian savannah (Cerrado). The experiment was conducted using a completely randomized design, with four treatments and eight repetitions. The treatments involved two methods of application: aerial (RPA, 10 L ha-1) and ground (backpack sprayer, 100 L ha-1); and two types of nozzles: the standard flat fan nozzle XR 11001 and the air induction flat fan nozzle AirMix 11001. To study the quality of the application, the deposition was evaluated using a tracer and spectrophotometry, and the droplet spectrum, evaluated through the analysis of water-sensitive paper. Furthermore, a study on application quality was conducted using the Statistical Process Control methodology. The results demonstrated that with RPA, the deposition was higher, and the AirMix 11001 nozzle also stood out in this variable. No non-random behavior was observed in the deposition. Ground application showed the best performance in terms of target coverage and droplet density. The XR 11001 nozzle resulted in a higher droplet density. Overall, the XR11001 nozzle and the RPA application showed smaller volume median diameters (VMDs), indicating a higher potential for drift, which should be taken into account. Given the results obtained, it can be stated that the use of RPAs for agricultural spraying is viable for application.

Emission and capture characteristics of Chinese cooking-related fine particles.

Cooking can emit high concentrations of particles and gaseous pollutants. Cooking has contributed to the major source of indoor air pollutants, especially for particle pollutants in residential buildings. Many studies already analyzed the emission characteristics of Chinese cooking-related UFPs and PM2.5, while less for the fine particle size distributions. Currently, the fine particle emission characteristics of Chinese cooking need to be further investigated, since the mass size distribution of Chinese cooking is dominated by fine particles. This study determined the emission characteristics of PM1 and fine particles from three Chinese cooking methods. The capture efficiencies of particles were also measured by a modified indirect approach, including the impact of particle decay. The results showed that stir-fried vegetable and pan-fried meat dishes generated more fine particles at 0.542-1.5 μm. Besides, pan-fried and deep-fried meat dishes produce a higher generation of PM1. The fine particles (0.542-10 μm) number-based and volume-based size distributions of six dishes both presented a monodisperse behavior. The cooking methods are not a sensitive factor to the volume frequency of fine particle ranging from 0.542 to 10 μm. The averaged volume median and mode diameter for six typical Chinese dishes are 2.5 μm and 3.3 μm, respectively. The Sauter and DeBroukere mean diameter is 4.7 μm and 5.6 μm, respectively. The decay of fine particles increases with the particle diameter. The impact of particle decay on capture efficiency for 2-3 μm particles is about 5%. The capture efficiencies of pan-fried and deep-fried meat dishes are lower than that of vegetable dishes. In contrast, the capture efficiency for stir-fried meat dishes is higher than that of vegetable dishes. The capture efficiency for PM1 and 0.542-5 μm particles from six typical Chinese dishes were 60-90% on the IEC recommended exhaust flowrate.

Atomization Characteristics of a Hollow Cone Nozzle for Air-Assisted Variable-Rate Spraying

During variable-rate spraying in orchards, the atomization characteristics and distribution of droplets in and out of the target area can be affected by the sprayer pressure. In this study, a variable-rate spraying control system test bench was designed, and a hollow cone nozzle QY82.317.22 was selected. The droplet atomization characteristics, including volume median diameter (Dv0.5), the relative span of the droplet spectrum, and droplet velocity at different spray pressures, were studied at distances ranging from 0.4 to 2.4 m from the nozzle orifice with an air velocity of 10 m/s at the nozzle orifice position. The effects of longitudinal distance, transverse distance, and spray pressure on Dv0.5, relative span, and droplet velocity were analysed by multiple linear regression analysis, and the regression model was established. The experimental results show that at a longitudinal distance of 1.8 m, Dv0.5 ranges from 120 to 150 μm, meeting the requirements for optimal droplet size for controlling crawling pests and plant diseases on crop leaves; and the relative span is 1.2, indicating a wide droplet spectrum. At different pressure conditions, Dv0.5 decreases as pressure increases. Through multiple linear regression analysis, the longitudinal distance, the transverse distance, and the spray pressure have high significance for Dv0.5 and the droplet velocity. The longitudinal distance and the transverse distance have a highly significant effect on the relative span. In this study, the mathematical relational model of droplet characteristics at different spatial positions and different pressures was established, providing an agricultural reference for predicting the droplet characteristics at different spatial positions to achieve the best application effect. This model is conducive to the effective use of pesticides and reduces environmental pollution.

Sensitivity of Pharmacokinetics to Differences in the Particle Size Distribution for Formulations of Locally Acting Mometasone Furoate Suspension-Based Nasal Sprays.

To assess bioequivalence of locally acting suspension-based nasal sprays, the U.S. FDA currently recommends a weight-of-evidence approach. In addition to in vitro and human pharmacokinetic (PK) studies, this includes a comparative clinical endpoint study to ensure equivalent bioavailability of the active pharmaceutical ingredient (API) at the site of action. The present study aimed to assess, within an in vitro/in vivo correlation paradigm, whether PK studies and dissolution kinetics are sensitive to differences in drug particle size for a locally acting suspension-based nasal spray product. Two investigational suspension-based nasal formulations of mometasone furoate (MF-I and MF-II; delivered dose: 180 μg) differed in API particle size and were compared in a single-center, double-blind, single-dose, randomized, two-way crossover PK study in 44 healthy subjects with oral charcoal block. Morphology-directed Raman spectroscopy yielded volume median diameters of 3.17 μm for MF-I and 5.50 μm for MF-II, and dissolution studies showed that MF-II had a slower dissolution profile than MF-I. The formulation with larger API particles (MF-II) showed a 45% smaller Cmax and 45% smaller AUC0-inf compared to those of MF-I. Systemic bioavailability of MF-I (2.20%) and MF-II (1.18%) correlated well with the dissolution kinetics, with the faster dissolving formulation yielding the higher bioavailability. This agreement between pharmacokinetics and dissolution kinetics cross-validated both methods and supported their use in assessing potential differences in slowly dissolving suspension-based nasal spray products.

Seasonal variation of microphysical characteristics for different rainfall types in the Tianshan Mountains of China

Three-year (2020−2022) raindrop size distribution (DSD) measurements from a second-generation PARSIVEL disdrometer deployed at Zhaosu, which is located in the Tianshan Mountains of China, are analyzed to investigate the seasonal variability of microphysical characteristics of two types of rainfall. Rainfall at Zhaosu is classified as stratiform rainfall and convective rainfall in the normalized intercept parameter–median volume diameter (log10Nw–D0) and log10Nw–mass-weighted mean diameter (log10Nw–Dm) spaces, respectively. Both stratiform rainfall and convective rainfall samples in the log10Nw–D0 space are more than three times those in the log10Nw–Dm space, accompanied by smaller mean rainfall rate (R). Rainfall in summer (spring) has the lowest (highest) concentration of small-size raindrops, while rainfall in fall (summer) has the lowest (highest) concentration of mid- and large-size raindrops, accompanied by the largest (smallest) mean Dm and D0 values and the smallest (largest) mean log10Nw values in summer (spring). Convective rainfall exhibits more significant seasonal variation in microphysical parameters and DSD than stratiform rainfall, whether in the log10Nw–D0 space or the log10Nw–Dm space. The convective rainfall in spring is more like maritime cluster, whereas that in summer is more like continental cluster in the log10Nw–Dm space. Furthermore, in the log10Nw–D0 and log10Nw–Dm spaces, localized relationships of radar reflectivity factor – R (Z–R) and shape parameter – slope parameter (μ–∧) are derived across seasons for different rainfall types. The results indicate that there are significant seasonal variations in the microphysical characteristics of rainfall in the Tianshan Mountains of China for the two rainfall types. This study further emphasizes that different classification schemes for rainfall types can lead to significant differences in the characteristics of DSD, Z–R, and μ–∧ relationships for different rainfall types.