Spray Concentration Research Articles

Flower and pod development, grain-setting characteristics and grain yield in Chinese milk vetch (Astragalus sinicus L.) in response to pre-anthesis foliar application of paclobutrazol.

The number of grains per unit land area is the most important grain yield component in Chinese milk vetch. Flower and pod survival seem to be critical determinants of grain number, which is related to the number of fertile flowers and pods during the anthesis period. Flower and pod growth are frequently considered the key determinants to establish grain number. The objective of this study was to explore the influences of paclobutrazol on flower and pod development, grain-setting characteristics and grain yield in Chinese milk vetch under different concentrations of foliar spray and try to explore the physiological regulatory mechanisms. Field experiments were carried out during the 2017-2018 and 2018-2019 growing seasons at the Dayuzhuang experimental field. The experiment involved the Chinese milk vetch cultivar "Xinzi No. 1" and six levels of foliar application of paclobutrazol, 0, 200, 300, 400, 500, and 600 mg L-1, in treatments CK, T1, T2, T3, T4, and T5, respectively. Foliar spray was applied once, at the squaring stage. In comparison with the CK treatment, all of the paclobutrazol treatments yielded, to various degrees, increased values of the number of inflorescences per unit area, number of pods per unit area, grain-setting rate of pods, and number of grains per pod in all six inflorescence layers, with the largest increases observed in the T3 treatment. In the T3 treatment compared with the CK treatment, from the first to sixth inflorescence layers, the number of inflorescences per unit area was increased by 34.07-58.97%, the number of pods per unit area was increased by 39.69-68.35%, the grain number per pod was increased by 44.31-53.69%, and the grain-setting rate of pods was increased by 1.84-4.89%. An analysis of yield composition revealed that the paclobutrazol spray treatment had little impact on the grain weight of Chinese milk vetch. The correlations between the concentration of paclobutrazol spray and the grain yield of Chinese milk vetch reached a significant level. Grain yield was highest at the paclobutrazol concentration of 373.10 mg/L. The inflorescence contents of gibberellic acid 3 (GA3), indole-3-acetic acid (IAA), and abscisic acid (ABA) were reduced, whereas that of cytokinin (CTK) was increased, by foliar application of paclobutrazol (400 mg L-1, T3 treatment) relative to CK treatment during the stages of flowers and pods developing into grains.

Effect of foliar iron sulfate on the fruit growth and quality of pineapple (Ananas comosus cv. Yellow Mauritius) planted in lateritic soil in Leizhou Peninsula

Leizhou Peninsula in South China is facing a serious water shortage problem because of the special regional and geological conditions. As a kind of low water requirement crop, pineapple has been popular in lateritic soil. However, the physical characteristics of Lateritic soil such as too cohesive, impervious, low content of organic matter, and seasonal arid often bring some problem to pineapple cultivation. Seasonal iron deficiency can be easily observed from April to July. The effect of foliar spray of iron sulfate (with concentration of 0, 0.5%, 0.75%, 1%) on the fruit growth and quality of pineapple cv. Yellow Mauritius were studied in this research. Results showed that there were no significant difference (p>0.05) on the fruit weight, longitudinal diameter, transverse diameter among all the treatment. 0.75% treatment increased the fruit weight to 6.08% and decreased crown weight significantly. Both 0.75% and 1% iron sulfate treatment not only enhanced vitamin C extremely significantly, but also improved the aroma quality significantly with the increase of total esters, especially in the content of hexanoic acid methyl ester, 3-(methyl tio) propanoic acid methyl ester and 2-methylbutanoic acid methyl ester. The content of these 3 esters above were all extremely significantly higher than control, which means much stronger pleasant aroma. Hence, 0.75% was the optimal concentration of foliar spray with iron sulfate in pineapple cv. Yellow Mauritius.

Study of Carbon Brush and Slip-Ring System Abrasion From Electric Contact Friction Under Special Environments

In a marine environment, the working conditions for carbon brush and slip-ring system are complicated, leading to carbon brush abrasion and a shortened replacement cycle. A research and experiment platform using a salt spraying tester has been established to study abrasion on the carbon brush and slip-ring system of a Doubly-fed machine. We conducted tests on the carbon brush and slip-ring system contact current, contact pressure, concentration of salt spray, and the experimental temperature. The improved Coulomb-viscous friction model was adopted for modelling the carbon brush abrasion. The contact current, contact pressure, salt spray concentration and temperature were introduced as the test conditions for the forecast model, and the unknown model parameters were identified through the least square method. MATLAB was utilized to fit the nonlinear model parameters using the carbon brush abrasion prediction model results. The residual error plot and test data fitting indicated that the prediction model could effectively forecast the carbon brush abrasion loss under various conditions.

The stronger, the better? A natural experiment on the effects of pepper spray concentration levels

PurposeOleoresin capsicum (OC) spray has proven to be a relatively effective tool to subdue resistant or aggressive subjects without causing major and permanent injuries. Several products are available to law enforcement organizations and sprays with higher concentrations are sold as more effective, despite the lack of empirical evidence. This article aims to test the proposition that more concentrated OC sprays are more effective in a policing context.Design/methodology/approachTo test this proposition, retrospective data on police interventions that had occurred (N = 1,019) were used. Concentrations were divided in three levels: level 1 sprays (containing up to 0.49% of major capsaicinoids), level 2 sprays (from 0.5% to 0.99%) and level 3 sprays (between 1 and 1.33%). Propensity scores were calculated to estimate the average effect of concentration level on effectiveness, while controlling for confounding factors.FindingsLevel 1 and level 2 sprays were found to be similar in terms of effectiveness, but level 3 sprays were found to be more likely to have an immediate effect but were also related to higher chances that decontamination was needed after use.Originality/valueWhile several studies of the effectiveness of OC spray in general have been conducted in the past, this is one of the few to differentiate types of OC sprays according to their concentration level. As such, it aims to provide guidance to police organizations who must choose among a variety of products.

Glyphosate Toxicity to Native Nontarget Macrophytes Following Three Different Routes of Incidental Exposure.

ABSTRACTA major goal of invasive plant management is the restoration of native biodiversity, but effective methods for invasive plant control can be harmful to native plants. Informed application of control methods is required to reach restoration goals. The herbicide glyphosate, commonly applied in invasive plant management, can be toxic to native macrophytes. Our study assessed the response of 2 macrophytes that are endangered in our study area (Ammannia robusta and Sida hermaphrodita) to glyphosate concentrations that mimic incidental exposure from nearby invasive plant control: spray drift of 4 × 10−7% to 5% glyphosate; pulse and continuous immersion in water containing 2 to 41 µg/L glyphosate; and rhizosphere contact with 5%‐glyphosate‐wicked invasive plants. We assessed macrophyte sensitivity at 14‐d postexposure, and quantified abundance of arbuscular mycorrhizal fungi. Glyphosate spray concentrations as low as 0.1% reduced macrophyte growth. Ammannia was more sensitive overall to glyphosate spray than Sida, although sensitivity varied among measured endpoints. Conversely, macrophytes were not affected by immersion in low concentrations of glyphosate or rhizosphere contact with a glyphosate‐wicked plant. Likewise, arbuscular mycorrhizal fungi abundance in roots was similar among glyphosate‐sprayed and control plants. Based on our results, we recommend that invasive plant managers reduce risks to native nontarget plants through implementing measures that limit off‐target spray drift, and consider the feasibility of more targeted applications, such as with wick equipment. Integr Environ Assess Manag 2021;17:597–613. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC)

Potential effect of bio-surfactants on sea spray generation in tropical cyclone conditions

Despite significant improvement in computational and observational capabilities, predicting intensity and intensification of major tropical cyclones remains a challenge. In 2017 Hurricane Maria intensified to a Category 5 storm within 24 h, devastating Puerto Rico. In 2019 Hurricane Dorian, predicted to remain tropical storm, unexpectedly intensified into a Category 5 storm and destroyed the Bahamas. The official forecast and computer models were unable to predict rapid intensification of these storms. One possible reason for this is that key physics, including microscale processes at the air-sea interface, are poorly understood and parameterized in existing forecast models. Here we show that surfactants significantly affect the generation of sea spray, which provides some of the fuel for tropical cyclones and their intensification, but also provides some of the drag that limits intensity and intensification. Using a numerical model verified with a laboratory experiment, which predicts spray radii distribution starting from a 100 μm radius, we show that surfactants increase spray generation by 20–34%. We anticipate that bio-surfactants affect heat, energy, and momentum exchange through altered size distribution and concentration of sea spray, with consequences for tropical cyclone intensification or decline, particularly in areas of algal blooms and near coral reefs, as well as in areas affected by oil spills and dispersants.

Responses of leaf gas exchange attributes, photosynthetic pigments and antioxidant enzymes in NaCl-stressed cotton (Gossypium hirsutum L.) seedlings to exogenous glycine betaine and salicylic acid

BackgroundApplication of exogenous glycine betaine (GB) and exogenous salicylic acid (SA) mitigates the adverse effects of salinity. Foliar spraying with exogenous GB or SA alleviates salt stress in plants by increasing leaf gas exchange and stimulating antioxidant enzyme activity. The effects of foliar application of exogenous GB and SA on the physiology and biochemistry of cotton seedlings subjected to salt stress remain unclear.ResultsResults showed that salt stress of 150 mM NaCl significantly reduced leaf gas exchange and chlorophyll fluorescence and decreased photosynthetic pigment quantities and leaf relative water content. Foliar spray concentrations of 5.0 mM exogenous GB and 1.0 mM exogenous SA promoted gas exchange and fluorescence in cotton seedlings, increased quantities of chlorophyll pigments, and stimulated the antioxidant enzyme activity. The foliar spray also increased leaf relative water content and endogenous GB and SA content in comparison with the salt-stressed only control. Despite the salt-induced increase in antioxidant enzyme content, exogenous GB and SA in experimental concentrations significantly increased the activity of glutathione reductase, ascorbate peroxidase, superoxide dismutase, catalase and peroxidase, and decreased malondialdehyde content under salt stress. Across all experimental foliar spray GB and SA concentrations, the photochemical efficiency of photosystem II (FV/FM) reached a peak at a concentration of 5.0 mM GB. The net photosynthetic rate (Pn) and FV/FM were positively correlated with chlorophyll a and chlorophyll b content in response to foliar spraying of exogenous GB and SA under salt stress.ConclusionsWe concluded, from our results, that concentrations of 5.0 mM GB or 1.0 mM SA are optimal choices for mitigating NaCl-induced damage in cotton seedlings because they promote leaf photosynthesis, increase quantities of photosynthetic pigments, and stimulate antioxidant enzyme activity. Among, 5.0 mM GB and 1.0 mM SA, the best performance in enhancing endogenous GB and SA concentrations was obtained with the foliar application of 1.0 mM SA under salt stress.

Foliar nitrogen supply enhances the recovery of photosynthetic performance of cold-stressed coffee (Coffea arabica L.) seedlings

Cold-stressed leaves possess an elevated risk of photodamage due to an inefficient photosynthetic apparatus during winter conditions. Recovery of cold-stressed coffee seedlings treated with different concentrations of nitrogen applied as foliar urea sprays [control (0), 5, 10, 20, and 40 mM], was investigated under optimum growth chamber conditions (25/20°C) for three months. Concentrations of nitrogen and photosynthetic pigments in the leaves increased with increasing concentration of the foliar sprays up to 20 mM. This was accompanied with a recovery of the photosynthetic apparatus and increased net carbon assimilation rate. In addition, 10 and 20 mM-treated plants also had the highest maximal efficiency of PSII compared to their lower or higher nitrogen concentration treated counterparts. Conversely, these plants contained lower concentrations of 5-caffeoylquinic acid, mangiferin, trigonelline, and caffeine than control plants. We concluded therefore that foliar sprays of the appropriate nitrogen concentration were adequate for recuperating the photosynthetic apparatus and improved the photosynthetic performance of the cold-stressed coffee seedlings.

EFFECT OF SOIL COVERAGE WITH ORGANIC MULCHING AND SPRAYING WITH SEAWEED EXTRACT ON SOME VEGETATIVE AND PRODUCTIVE TRAITS OF CUCUMBER GROWN IN GREENHOUSES

The experiment was carried out to investigate the effect of soil coverage with organic mulching and spraying with seaweed extract in some vegetative and productive characteristics of Cucumber planted under plastic houses. The study was included two factors: the first factor was organic soil coverings which divided into Control: without coverage (M0), Coverage of wheat straw (M1), Coverage of Sawdust (M2) and Coverage of Corn cobs (M3) while the second factor was represented by three concentrations of seaweed extract (0, 1, 2 ) g.L-1 (F0, F1, F2 respectively). The experiment was Randomized Complete Block Design RCBD with three replicates as a factorial experiment (4 x 3). The experiment included 12 treatments and 36 units, each unit includes 8 plants. The obtained results were analyzed by SAS program and the averages were compared by the Duncan Multipliers test at a probability level of 5%. The present results showed that the Soil coverings with wheat straw (M1) recorded a significant increase in plant length, number of leaves, relative chlorophyll quantity, number of fruits, fruit weight, plant yield and total yield with mean values195.60 cm/plant-1 ,47.89leaf/plant-1 , 41.19 SPAD,29.00 fruit,80.20g/fruit -1 , 2.320 g/plant-1 ,3.897 kg/plant-1 respectively. While the seaweed extract had a significant effect in most studied traits, spraying at (1 g/L-1 ) F1 gave the highest rate of plant length, number of leaves, fruit weight, and total soluble solids content (T.S.S) was197.10 cm/plant-1 . 48.08 leaf/plant-1 . 71.30 g/fruit -1 , 3.300% respectively, the concentration of spray (2 g/ L-1 ) F2 exceeded the number of fruits, plant yield, and total yield. Additionally, the interaction between spraying with a concentration of seaweed extract (1 g/ L-1 ) F1 and soil cover with wheat straw (M1) significantly increased plant height, number of leaves, and relative amount of chlorophyll and fruit weight.

Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols

Abstract. Cloud–radiation interactions over the Southern Ocean are not well constrained in climate models, in part due to uncertainties in the sources, concentrations, and cloud-forming potential of aerosol in this region. To date, most studies in this region have reported measurements from fixed terrestrial stations or a limited set of instrumentation and often present findings as broad seasonal or latitudinal trends. Here, we present an extensive set of aerosol and meteorological observations obtained during an austral summer cruise across the full width of the Southern Ocean south of Australia. Three episodes of continental-influenced air masses were identified, including an apparent transition between the Ferrel atmospheric cell and the polar cell at approximately 64∘ S, and accompanied by the highest median cloud condensation nuclei (CCN) concentrations, at 252 cm−3. During the other two episodes, synoptic-scale weather patterns diverted air masses across distances greater than 1000 km from the Australian and Antarctic coastlines, respectively, indicating that a large proportion of the Southern Ocean may be periodically influenced by continental air masses. In all three cases, a highly cloud-active accumulation mode dominated the size distribution, with up to 93 % of the total number concentration activating as CCN. Frequent cyclonic weather conditions were observed at high latitudes and the associated strong wind speeds led to predictions of high concentrations of sea spray aerosol. However, these modelled concentrations were not achieved due to increased aerosol scavenging rates from precipitation and convective transport into the free troposphere, which decoupled the air mass from the sea spray flux at the ocean surface. CCN concentrations were more strongly impacted by high concentrations of large-diameter Aitken mode aerosol in air masses which passed over regions of elevated marine biological productivity, potentially contributing up to 56 % of the cloud condensation nuclei concentration. Weather systems were vital for aerosol growth in biologically influenced air masses and in their absence ultrafine aerosol diameters were less than 30 nm. These results demonstrate that air mass meteorological history must be considered when modelling sea spray concentrations and highlight the potential importance of sub-grid-scale variability when modelling atmospheric conditions in the remote Southern Ocean.

Rapid online determination of feed concentration in nitroguanidine spray drying process by near infrared spectroscopy

This work investigated the feasibility of using near-infrared (NIR) spectroscopy to rapidly online detect the feed concentration of nitroguanidine (NQ) in order to ensure the uniformity and stability of the NQ feed during the spray drying process. A Fourier transform NIR spectrometer with a detector installed on the NQ slurry pipeline was used to collect original spectra of NQ samples with different concentrations. Standard normal variate was used to preprocess the original spectra, and a quantitative model with 7 factors of feed concentration was established by partial least squares regression in the spectral wavenumber ranges of 6890–6444 cm−1 and 5126–4236 cm−1. The determination coefficients of calibration and prediction (Rc2,Rp2) were 0.9945 and 0.9880, the root mean square errors of calibration and prediction (RMSEC, RMSEP) were 0.111 and 0.157, and the residual predictive deviation (RPD) values of calibration and prediction were 13.5 and 9.18, respectively. The established model was applied to detect the feed concentration of 8 other samples, and the difference between the near-infrared prediction values and the traditional measured values was only 0.29%. The results indicate the excellent predictive performance and repeatability of the model and provide new insights into the NIR spectroscopy rapid online detection of the feed concentration of NQ during spray drying process.

EFFECT OF HUMIC ACID SPRAY ON GROWTH CHARACTERISTICS OF WHEAT VARIETIES

A field experiment conducted in 2018-2019 in the Nile district Iraq according split split plot. The varieties as main treatment (Baghdad 2 and Sham 6), spraying dates (elongation stage, endothelium stage and flowering stage) sub treatment while the humic acid concentrations occupied (3,1.5,0 cm3. L-1) as sub treatment. The differences were significant between different treatments. The variety Baghdad 2 was significantly superior in traits, plant height, number of branches, spikes, grains per spike and. weight of grain. The total yield of grains was 9.13 ton. ha -1. The spraying dates showed significant differences, as the spraying at flowering stage was better in most characteristics, area of ​​the flag leaf, spike length, number of grains/ pike-, weight of grain.gm, and total yield Spray at the endometrium stage resulted in maximum height, spike, while spray at the highest value in the variety number of beaches reached 434.79 beach.m2, the number of spikes.m2 380.21 spike.m2. The humic acid concentrations showed a significant difference. The humic acid as the resulted in maximum plant height, area of ​​flag, number of tillersperm2, spike length, number of spikes per m2, the number of grains per spike, weight of 1000grain and the total yield of grains. The interaction between the varieties and the spraying dates C and S, the combination C2 + S3 was superior to the size of the flag leaf area cm2, weight 1000grain.gm and the total yield of grains ton. ha-1. 36.74 cm2, 8.60cm, 37.83 g, 9.97 ton. ha-1. While the combination C2 + S3 outperformed the area of ​​the flag leaf and gave an average of 36.74 cm2 and the combination C2 + S1 outperformed the number of spikes.m2, and gave the highest average of 382.18 spike. m2, while the combination C1 + S3 only outperformed the number of grains and gave the highest average of 65.72grain. Spike -1 The results of the bilateral interaction between the varieties and the fertilizer spraying concentrations C + F indicated the presence of a significant effect among the combinations, as the combination C2 + F3 was superior to the plant height of 106.56 cm, number of spikes.m2 381.22, weight of 1000grain, 37.69 gm, and the total grain yield ton. ha-1 9.40 ton. ha-1. C1 + F3 combination outperformed the spike length. Cm and it gave 8.97 and the results of the research showed that there were significant differences for the bilateral interaction between appointment and concentration S + F, and the combination S3 + F3 was superior in the following characteristics to the number of grains. Spike -1 weight 1000grain. The total grain yield is 67.90grain. spike-1 and 37.32 gm, 9.60 ton. ha-1. The combination S2 + F3 excelled in the height of the plant only and gave 105.20 cm.

Spray characteristics of direct injection injectors with different nozzle configurations under flash-boiling conditions

This investigation utilized four gasoline direct injection (GDI) injectors with different nozzle lengths and step hole diameters to analyze the influences of nozzle structure on the superheated plume and spray collapse under different superheat degrees. The spray behaviors of were recorded by using high-speed shadowgraphs. In addition, the spray concentration distribution, spray development, and spray swelling characteristics under different superheat conditions were analyzed. The experimental results showed that hole length and step hole diameter affected the widths of the spray plumes, which then affected the spray characteristics. Wider spray plumes enhance plume interactions and promote reduced spray penetration. This causes spray to enter the transition regime at a lower degree of superheat. In addition, the transition regime exhibits better spray characteristics than the subcooled and flare flash boiling regimes. Injector with smaller hole length and larger step hole diameter exhibits stronger adaptability while utilizing the remarkable spray characteristics in the transition regime, owing to the greater length of the spray transition regime.

Experimental investigation of the ignition process in a separated dual-swirl spray flame

Centrally staged lean premixed pre-evaporation combustion technology has been used in aero engines for its capability in effectively reducing NOx emissions while still providing stable flames. Previous work has shown the “ignition delay” phenomenon in the forced ignition process, revealing that the burner ignition process is complex and needs further exploration. In this work, the spark ignition and flame kernel propagation in a centrally staged optical model combustor are experimentally investigated to further illustrate the interaction between random kernel motion and flow statistics from the perspective of timescales and kernel propagations. Stochasticity involved in each individual phases of the whole ignition is obtained via repeated high-speed imaging tests. Timescales of the successful ignition processes are analyzed in a statistical method, revealing the time randomness of ignition phases. Spatial probability of the flame kernel propagation in turbulent sprays is calculated and analyzed with the combination of time-averaged flow and spray distribution. The flame projected area evolutions show that the burner ignition phase can be further divided into three phases: flame propagation, flame residence and flame growth. Three modes of ignition failure are identified during the burner ignition phase. The flame residence phase features a special period of spark ignition with low light emissions from the highly wrinkled flame kernel in the center, which is the “ignition delay” before the growth of flame. Timescales of ignition stages involve stochasticity and the flame growth phase has a higher proportion in the whole process. Statistical analysis of the flame kernel spatial position shows that in turbulent spray the flame kernel has a greater probability of propagating to the region with low axial velocity, low shear strain rate, and appropriate spray concentration.

Optimization on Maltodextrin Concentration and Inlet Spray Drying Temperature in Producing Edamame (Glycine max L. Merr.) Milk Powder: Nutritional and Microbiological Profile

Edamame powdered milk products have not produced on an industrial scale until the present. It is an excellent opportunity to develop nutrient-rich edamame to become a product with a high global market demand. The production of edamame milk powder has essential factors that contribute to sensory attributes, there is a concentration of maltodextrin as a filler and also encapsulating agent and inlet temperature of spray drying inlet for producing milk powder. The research aims to determine the optimal concentration of maltodextrin and inlet spray drying temperature to produce edamame milk powder based on the response of sensory analysis. Based on the results of the study, the concentration of maltodextrin 129.91 g/L (12.99%) and the spray dryer temperature 131°C were the optimal factor points of the sensory attribute responses analyzed using a nine-scale Hedonic Scale Scoring. Color with response 8.5, aroma 8.25, taste 7.8, and texture 8.35. The optimal product has a moisture content of 2.31 ± 0.04%, total dissolved solids of 19.89 ± 0.02% °Brix, the solubility of 95.23 ± 0.38%, and yield of 24.25%.

Meridional and vertical variations of the water vapour isotopic composition in the marine boundary layer over the Atlantic and Southern Ocean

Abstract. Stable water isotopologues (SWIs) are useful tracers of moist diabatic processes in the atmospheric water cycle. They provide a framework to analyse moist processes on a range of timescales from large-scale moisture transport to cloud formation, precipitation and small-scale turbulent mixing. Laser spectrometric measurements on research vessels produce high-resolution time series of the variability of the water vapour isotopic composition in the marine boundary layer. In this study, we present a 5-month continuous time series of such ship-based measurements of δ2H and δ18O from the Antarctic Circumnavigation Expedition (ACE) in the Atlantic and the Southern Ocean in the time period from November 2016 to April 2017. We analyse the drivers of meridional SWI variations in the marine boundary layer across diverse climate zones in the Atlantic and Southern Ocean using Lagrangian moisture source diagnostics and relate vertical SWI differences to near-surface wind speed and ocean surface state. The median values of δ18O, δ2H and deuterium excess during ACE decrease continuously from low to high latitudes. These meridional SWI distributions reflect climatic conditions at the measurement and moisture source locations, such as air temperature, specific humidity and relative humidity with respect to sea surface temperature. The SWI variability at a given latitude is highest in the extratropics and polar regions with decreasing values equatorwards. This meridional distribution of SWI variability is explained by the variability in moisture source locations and its associated environmental conditions as well as transport processes. The westward-located moisture sources of water vapour in the extratropics are highly variable in extent and latitude due to the frequent passage of cyclones and thus widen the range of encountered SWI values in the marine boundary layer. Moisture loss during transport further contributes to the high SWI variability in the extratropics. In the subtropics and tropics, persistent anticyclones lead to well-confined narrow easterly moisture source regions, which is reflected in the weak SWI variability in these regions. Thus, the expected range of SWI signals at a given latitude strongly depends on the large-scale circulation. Furthermore, the ACE SWI time series recorded at 8.0 and 13.5 m above the ocean surface provide estimates of vertical SWI gradients in the lowermost marine boundary layer. On average, the vertical gradients with height found during ACE are -0.1‰m-1 for δ18O, -0.5‰m-1 for δ2H and 0.3 ‰ m−1 for deuterium excess. Careful calibration and post-processing of the SWI data and a detailed uncertainty analysis provide a solid basis for the presented gradients. Using sea spray concentrations and sea state conditions, we show that the vertical SWI gradients are particularly large during high wind speed conditions with increased contribution of sea spray evaporation or during low wind speed conditions due to weak vertical turbulent mixing. Although further SWI measurements at a higher vertical resolution are required to validate these findings, the simultaneous SWI measurements at several heights during ACE show the potential of SWIs as tracers for vertical mixing and sea spray evaporation in the lowermost marine boundary layer.

Formation and explosion characteristics of methanol spray droplets in confined space

In order to improve the standard testing method of droplet explosion, the droplet formation process and explosion characteristics of methanol were experimentally studied in the 20 L spherical spray testing system, under different ambient pressures, injection pressures and concentrations. The results show that the increasing of injection pressure is more likely to cause the methanol to break into tiny droplets, leading the explosion limit range of methanol droplets broadened. The increasing of ambient pressure would change the explosion limit range of methanol droplet, and can effectively inhibit the explosion accident caused by methanol leakage. When the ambient pressure is 0.1 MPa, and the injection pressure is 2.1 MPa, with the spray concentration of methanol is 356.4 g/m3, the droplet size of the methanol is 2.5 μm. The maximum explosive pressure, the maximum explosion pressure rising rate and the laminar burning rate are the highest at this inflection point. Small droplets (1−15 μm) are more easily ignited by external energy, and the transient physical and chemical reactions are more rapid and violent during explosion. Larger droplets (more than 22 μm) will cause ignition difficult. However, after the ignition is successful, the explosion characteristics increase with the increasing of methanol droplet concentration, showing an approximate linear rule. At this time, the influence of droplet size of methanol on the above explosion characteristics can be neglected. The results could be helpful to understand the law of droplet explosion, improve the testing method and safety design.

Constraining the Surface Flux of Sea Spray Particles From the Southern Ocean

AbstractModeling the shortwave radiation balance over the Southern Ocean region remains a challenge for Earth system models. To investigate whether this is related to the representation of aerosol‐cloud interactions, we compared measurements of the total number concentration of sea spray‐generated particles within the Southern Ocean region to model predictions thereof. Measurements were conducted from a container laboratory aboard the R/V Tangaroa throughout an austral summer voyage to the Ross Sea. We used source‐receptor modeling to calculate the sensitivity of our measurements to upwind surface fluxes. From this approach, we could constrain empirical parameterizations of sea spray surface flux based on surface wind speed and sea surface temperature. A newly tuned parameterization for the flux of sea spray particles based on the near‐surface wind speed is presented. Comparisons to existing model parameterizations revealed that present model parameterizations led to overestimations of sea spray concentrations. In contrast to previous studies, we found that including sea surface temperature as an explanatory variable did not substantially improve model‐measurement agreement. To test whether or not the parameterization may be applicable globally, we conducted a regression analysis using a database of in situ whitecap measurements. We found that the key fitting parameter within this regression agreed well with the parameterization of sea spray flux. Finally, we compared calculations from the best model of surface flux to boundary layer measurements collected onboard an aircraft throughout the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES), finding good agreement overall.

Meteorological and flight altitude effects on deposition, penetration, and drift in pineapple aerial spraying

AbstractIt is difficult for the handheld/backpack or ground machinery to spray pineapple plant fields because the plant profile is relatively inaccessible. In this situation, unmanned aerial vehicles (UAVs) are a good choice for easy access and no physical damage to the crops. Aerial spray quality and optimum application parameter settings can be influenced by many factors such as UAV type, UAV operating parameters, meteorological conditions, crop growth period, and pest species. The objective of this study was to investigate the effects of different meteorological conditions and UAV operating height on the spray application in pineapple fields. There were five treatments involving three UAV operating heights. Mylar cards, water‐sensitive papers, and airborne concentrations of spray were sampled at various locations from −10 to 50 m downwind of the edge of the sprayed blocks. The results indicated that as the wind speed increased, the swath location was displaced 2 to 4 m, the percent area coverage uniformity changed along with the spray penetration capacity, and the 90% of total measured drift distance varied from 3.7 to 46.5 m. The test results again proved that droplet size and wind speed were significant factors in spray transport and impacted the UAV spray quality.

On the near wake structure of a supersonic coaxial gas-liquid jet

The work is devoted to a complex experimental study of the near wake of supersonic coaxial gas-liquid jets with a high concentration of the dispersed phase. At the various liquid flow rates, wave structure of a gas phase was visualized, droplet velocity profiles were obtained by the LDA method, and the spray concentration was measured. The effect of the liquid phase on the supersonic underexpanded jet was studied, in particular, a change in the general wave structure, Mach disk transformation, etc. A gas velocity profile was obtained in a two-phase core of a gas-liquid jet by the method of droplet velocity profile correction taking into account their velocity relaxation.