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Faers MA, Sato Y, Hilz E, Lamprecht S, Dong J, Qi F, Ratschinski A, Peris G, Gaertzen O, Roechling A. Suspension Concentrate crop protection formulation design and performance for low spray volume and UAS spray application. PEST MANAGEMENT SCIENCE 2024; 80:220-234. [PMID: 37555611 DOI: 10.1002/ps.7707] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/23/2023] [Accepted: 07/31/2023] [Indexed: 08/10/2023]
Abstract
BACKGROUND Unmanned aerial systems (UAS) are providing interesting disruptive solutions for spray application of crop protection products with very-low spray volumes (VLV) down to 8 L/ha that offer improved sustainability through reduced water volumes and reduced soil compaction. However, the efficacy of products can be reduced by the significantly lower crop/plant spray coverage and formulation designs that can compensate for this are highly important here. RESULTS Suspension Concentrate (SC) formulations designed for VLV use containing and delivering low dose rates (g/ha) of organosilicone alkoxylate high-spreading surfactants were found to result in leaf coverage of VLVs comparable to those observed at higher spray volumes. High spreading was observed on textured leaf surfaces containing sub-micron sized epicuticular wax crystals. Greenhouse fungal disease studies showed enhanced efficacy with these SC formulations compared to standard SC formulations without these additives and maintained the observed increase in efficacy when applied at VLV. Alternatively, SC formulations without high spreading formulants but containing uptake promoting nonionic surfactants showed enhanced cuticle penetration through isolated cuticles at VLV in comparison to higher spray volumes, with coffee-ring spray deposit microstructures present at VLVs. Similarly, greenhouse studies showed enhanced efficacy that was maintained at VLV relative to SCs without these additives. CONCLUSION At VLVs, SC formulations applied at relatively low dose rates (g/ha) of formulants (adjuvants) enhancing spreading on the leaf surface and/or uptake of the active ingredient(s) maintained good spreading, uptake and biological efficacy in greenhouse studies overcoming the coverage limitations of SC formulations without these additives. This result is unexpected considering the low dose rate of adjuvants used. © 2023 Bayer AG. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
| | | | | | | | | | - Feng Qi
- Bayer Pte. Ltd, Paya Lebar, Singapore
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2
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Preventing the release of copper chlorophyllin from crop spray deposits on hydrophobic surfaces. J Colloid Interface Sci 2020; 582:1149-1157. [PMID: 32947098 DOI: 10.1016/j.jcis.2020.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/02/2020] [Accepted: 09/03/2020] [Indexed: 11/23/2022]
Abstract
The chlorophyll derivative copper chlorophyllin and related chlorins have promise as environmentally friendly agricultural chemicals, however, spray application is hindered by the propensity of dried spray deposits to wash off leaf surfaces during rain or irrigation. HYPOTHESIS Polyelectrolyte complexes formed between anionic carboxymethyl cellulose and cationic polyamidoamine-epichlorohydrin can prevent the release of copper chlorophyllin from dried spray deposits on leaf surfaces when exposed to water. EXPERIMENTS Sessile drops on parafilm and containing polyelectrolyte complex and copper chlorophyllin or Brilliant Sulfaflavine, an anionic water-soluble dye, were dried to form deposits that were physical models for crop spray drop deposits on hydrophobic leaf surfaces. Larger buffer drops were placed on the dried deposits and the release of copper chlorophyllin or the dye were measured. FINDINGS Copper chlorophyllin showed some immediate (burst) release upon exposure to buffer whereas the remainder was immobilized on the parafilm. By contrast, Brilliant Sulfaflavine displayed rapid release following square root time dependence, typical of a diffusion-controlled process. The unusual behavior of copper chlorophyllin is attributed to the presence of CuChl nanoparticles when dispersed in water. The nanoparticles are encased in the polyelectrolyte complex that adheres to parafilm. The fraction of the added copper chlorophyllin lost in the burst release can be controlled by varying the polyelectrolyte complex composition and concentration.
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Ando D, Fujisawa T. Metabolism of esfenvalerate in tomato plants ( Solanum lycopersicum). JOURNAL OF PESTICIDE SCIENCE 2020; 45:138-146. [PMID: 32913416 PMCID: PMC7453297 DOI: 10.1584/jpestics.d20-022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 06/10/2020] [Indexed: 06/11/2023]
Abstract
The metabolic fate of esfenvalerate (1), 14C-labeled at the chlorophenyl or phenoxyphenyl ring, in tomato plants was investigated by spraying it three times at 15 g/ha. The overall metabolic trend of 1 was similar in foliage and fruit. The applied 1 gradually penetrated into the foliage/fruit, and approximately 30% of the total radioactive residue (TRR) distributed within the plant. The applied radioactivity remained mostly intact on the plant surface, while its degradation proceeded via ester cleavage to produce two corresponding acids derived from the chlorophenyl and phenoxyphenyl moieties, followed by saccharide conjugation at the inner tissues (each <5%TRR). While 1 retained its optical configuration (2S,αS) on the plant surface and in the fruit, a very slight isomerization at the α-cyanobenzyl carbon occurred to form a (2S,αR) isomer in the foliage (≤1%TRR). The isomerization at another asymmetric carbon C2 in the isovaleric acid moiety did not proceed on/in the plant for 1 or its metabolite.
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Affiliation(s)
- Daisuke Ando
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 4–2–1 Takarazuka, Hyogo 665–8555, Japan
| | - Takuo Fujisawa
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 4–2–1 Takarazuka, Hyogo 665–8555, Japan
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Wang F, Hu Z, Abarca C, Fefer M, Liu J, Brook MA, Pelton R. Factors influencing agricultural spray deposit structures on hydrophobic surfaces. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.05.074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Schulz M, Keddie JL. A critical and quantitative review of the stratification of particles during the drying of colloidal films. SOFT MATTER 2018; 14:6181-6197. [PMID: 30024010 DOI: 10.1039/c8sm01025k] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
For a wide range of applications, films are deposited from colloidal particles suspended in a volatile liquid. There is burgeoning interest in stratifying colloidal particles into separate layers within the final dry film to impart properties at the surface different to the interior. Here, we outline the mechanisms by which colloidal mixtures can stratify during the drying process. The problem is considered here as a three-way competition between evaporation of the continuous liquid, sedimentation of particles, and their Brownian diffusion. In particle mixtures, the sedimentation of larger or denser particles offers one means of stratification. When the rate of evaporation is fast relative to diffusion, binary mixtures of large and small particles can stratify with small particles on the top, according to physical models and computer simulations. We compare experimental results found in the scientific literature to the predictions of several recent models in a quantitative way. Although there is not perfect agreement between them, some general trends emerge in the experiments, simulations and models. The stratification of small particles on the top of a film is favoured when the colloidal suspension is dilute but when both the concentration of the small particles and the solvent evaporation rate are sufficiently high. A higher particle size ratio also favours stratification by size. This review points to ways that microstructures can be designed and controlled in colloidal materials to achieve desired properties.
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Affiliation(s)
- M Schulz
- Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, England, UK.
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Makepeace DK, Fortini A, Markov A, Locatelli P, Lindsay C, Moorhouse S, Lind R, Sear RP, Keddie JL. Stratification in binary colloidal polymer films: experiment and simulations. SOFT MATTER 2017; 13:6969-6980. [PMID: 28920986 DOI: 10.1039/c7sm01267e] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
UNLABELLED When films are deposited from mixtures of colloidal particles of two different sizes, a diverse range of functional structures can result. One structure of particular interest is a stratified film in which the top surface layer has a composition different than in the interior. Here, we explore the conditions under which a stratified layer of small particles develops spontaneously in a colloidal film that is cast from a binary mixture of small and large polymer particles that are suspended in water. A recent model, which considers the cross-interaction between the large and small particles (Zhou et al., Phys. Rev. Lett., 2017, 118, 108002), predicts that stratification will develop from dilute binary mixtures when the particle size ratio (α), initial volume fraction of small particles (ϕS), and Péclet number are high. In experiments and Langevin dynamics simulations, we systematically vary α and ϕS in both dilute and concentrated suspensions. We find that stratified films develop when ϕS is increased, which is in agreement with the model. In dilute suspensions, there is reasonable agreement between the experiments and the Zhou et al. MODEL In concentrated suspensions, stratification occurs in experiments only for the higher size ratio α = 7. Simulations using a high Péclet number, additionally find stratification with α = 2, when ϕS is high enough. Our results provide a quantitative understanding of the conditions under which stratified colloidal films assemble. Our research has relevance for the design of coatings with targeted optical and mechanical properties at their surface.
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Affiliation(s)
- D K Makepeace
- Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, UK.
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7
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Howard MP, Nikoubashman A, Panagiotopoulos AZ. Stratification Dynamics in Drying Colloidal Mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3685-3693. [PMID: 28349690 DOI: 10.1021/acs.langmuir.7b00543] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Stratification in binary colloidal mixtures was investigated using implicit-solvent molecular dynamics simulations. For large particle size ratios and film Péclet numbers greater than unity, smaller colloids migrated to the top of the film, while big colloids were pushed to the bottom, creating an "inverted" stratification. This peculiar behavior was observed in recent simulations and experiments conducted by Fortini et al. [ Phys. Rev. Lett. 2016 , 116 , 118301 ]. To rationalize this behavior, particle size ratios and drying rates spanning qualitatively different Péclet number regimes were systematically studied, and the dynamics of the inverted stratification were quantified in detail. The stratified layer of small colloids was found to grow faster and to larger thicknesses for larger size ratios. Interestingly, inverted stratification was observed even at moderate drying rates where the film Péclet numbers were comparable to unity, but the thickness of the stratified layer decreased. A model based on dynamical density functional theory is proposed to explain the observed phenomena.
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Affiliation(s)
- Michael P Howard
- Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States
| | - Arash Nikoubashman
- Institute of Physics, Johannes Gutenberg University Mainz , Staudingerweg 7, 55128 Mainz, Germany
| | - Athanassios Z Panagiotopoulos
- Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States
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8
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Zhang C, Zhao X, Lei J, Ma Y, Du F. The wetting behavior of aqueous surfactant solutions on wheat (Triticum aestivum) leaf surfaces. SOFT MATTER 2017; 13:503-513. [PMID: 27934995 DOI: 10.1039/c6sm02387h] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In this research the wetting behavior of agro-surfactant solutions (Triton X-100, SDS, DTAB) on wheat leaf surfaces have been investigated based on the surface free energy, surface tension, and the contact angle. The results show that the contact angle of those surfactant solutions keeps constant with low adsorption at interfaces below 1 × 10-5 mol L-1. With the increase in concentration, the contact angles of Triton X-100 decrease sharply because the adsorption of molecules at solid-liquid interfaces (ΓSL') is several times greater than that at liquid-air interfaces (ΓLV). With regards to SDS and DTAB, the contact angle also decreases but is even larger than 90° above the CMC, while the ratio of ΓSL' to ΓLV is about 1.20, demonstrating that the Gibbs surface excess is related to the structure of surfactant molecules. Obviously, besides the properties of wheat leaf surfaces and surfactant solutions, the wetting behavior mainly depends on their noncovalent interactions. Among these, the hydrophobic interaction is the main force promoting molecules to adsorb on the surface, with the assistance of the Lifshitz-van der Waals interactions and the electrostatic interactions. According to the mechanism of their wetting behavior on plant surfaces, the recipe of pesticide formulation can be adjusted with better wettability to reduce its loss, consequently improving pesticide utilization and decreasing environmental contamination.
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Affiliation(s)
- Chenhui Zhang
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, P. R. China.
| | - Xin Zhao
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, P. R. China.
| | - Jinmei Lei
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, P. R. China.
| | - Yue Ma
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, P. R. China.
| | - Fengpei Du
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, P. R. China.
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9
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Webster GR, Bisset NB, Cahill DM, Jones P, Killick A, Hawley A, Boyd BJ. Kinetic Resolution of the Interactions between Agrochemical Products and Adjuvant Systems upon Mixing. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:6139-6147. [PMID: 27460332 DOI: 10.1021/acs.jafc.6b01673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The addition of an adjuvant to a pesticide usually occurs in a mix-tank, before spray application to the crop. Their interaction is potentially crucial to overall efficacy but has received little attention from a physical-chemical perspective. Study was undertaken by laser diffraction, Raman spectroscopy, and small-angle X-ray scattering to resolve these physical processes. It was shown that migration of the pesticide into the adjuvant droplet occurred in all cases studied. The level of transfer was dependent upon adjuvant level, adjuvant solubility, and surfactant level. For suspension pesticides, dissolution of crystallites within the droplet occurred to a degree limited by solubility. The results directly demonstrate the transfer of the pesticide into the adjuvant carrier. This indicates that for emulsion-based pesticides, application to the target is likely as a homogeneously mixed droplet, whereas for suspension pesticides, solubility may limit transfer and dissolution, leading to heterogeneity in the applied particles.
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Affiliation(s)
- Graham R Webster
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Nicole B Bisset
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - David M Cahill
- School of Life and Environmental Sciences, Deakin University , Geelong Campus at Waurn Ponds, Victoria 3217, Australia
| | - Peter Jones
- Victorian Chemicals Pty., 83 Maffra Street, Coolaroo, Victoria 3048, Australia
| | - Andrew Killick
- Victorian Chemicals Pty., 83 Maffra Street, Coolaroo, Victoria 3048, Australia
| | - Adrian Hawley
- SAXS/WAXS Beamline, Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Ben J Boyd
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
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10
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Fortini A, Martín-Fabiani I, De La Haye JL, Dugas PY, Lansalot M, D'Agosto F, Bourgeat-Lami E, Keddie JL, Sear RP. Dynamic Stratification in Drying Films of Colloidal Mixtures. PHYSICAL REVIEW LETTERS 2016; 116:118301. [PMID: 27035324 DOI: 10.1103/physrevlett.116.118301] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Indexed: 05/27/2023]
Abstract
In simulations and experiments, we study the drying of films containing mixtures of large and small colloidal particles in water. During drying, the mixture stratifies into a layer of the larger particles at the bottom with a layer of the smaller particles on top. We developed a model to show that a gradient in osmotic pressure, which develops dynamically during drying, is responsible for the segregation mechanism behind stratification.
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Affiliation(s)
- Andrea Fortini
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, Universitätsstraße 30, D-95447 Bayreuth, Germany
| | | | - Jennifer Lesage De La Haye
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Pierre-Yves Dugas
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Muriel Lansalot
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Franck D'Agosto
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Elodie Bourgeat-Lami
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Joseph L Keddie
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - Richard P Sear
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
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11
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Eales AD, Routh AF. Elimination of Coffee-Ring Formation by Humidity Cycling: A Numerical Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:505-511. [PMID: 26694638 DOI: 10.1021/acs.langmuir.5b03827] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Periodically switching between evaporation and condensation, or "humidity cycling", has potential for controlling the film shape that results from volatile droplets containing a nonvolatile material. It does not require adaptation of material properties nor the introduction of an external field to achieve a change in film shape. It was shown experimentally by Doi and coworkers [Kajiya et al. Langmuir 2010, 26, pp 10429-10432] that ring-shaped deposits can be removed through careful selection of the atmospheric conditions. We present a model, based on lubrication theory, that can predict the final film shape resulting from the humidity cycling process. We confirm that the refluidization of gelled regions during condensation and the subsequent inward flow is the mechanism responsible for the improved profiles. Furthermore, we find that an increase in the time spent condensing to that spent evaporating results in flatter films and that an optimal humidity cycling frequency exists.
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Affiliation(s)
- Adam D Eales
- Department of Chemical Engineering, University of Cambridge , Cambridge CB2 3RA, United Kingdom
| | - Alexander F Routh
- Department of Chemical Engineering, University of Cambridge , Cambridge CB2 3RA, United Kingdom
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12
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Forster WA, Kimberley MO. The contribution of spray formulation component variables to foliar uptake of agrichemicals. PEST MANAGEMENT SCIENCE 2015; 71:1324-34. [PMID: 25354847 DOI: 10.1002/ps.3934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 10/06/2014] [Accepted: 10/26/2014] [Indexed: 05/19/2023]
Abstract
BACKGROUND The objective of the present study was to determine the contribution of the active ingredient (AI) and surfactant, and their concentrations, to the foliar uptake of agrichemicals, and to examine the physical properties that would need to be included in a model for foliar uptake. RESULTS All spray formulation component variables significantly affected uptake, explaining 73% of the deviance. The deviance explained by each factor ranged from 43% (AI concentration nested within AI) to 5.6% (surfactant). The only significant interaction was between AI and surfactant, explaining 15.8% of the deviance. Overall, 90% of the deviance could be explained by the variables and their first-order interactions. CONCLUSIONS Uptake increased with increasing lipophilicity of the AI at concentrations below those causing precipitation on the leaf surface. AI concentration had a far greater (negative) effect on the uptake of the lipophilic molecule epoxiconazole. The uptake of 2-deoxy-D-glucose (DOG) and 2,4-dichlorophenoxyacetic acid (2,4-D) increased with increasing hydrophile-lipophile balance (HLB) of the surfactant, the effect of HLB being far greater on the hydrophilic molecule DOG. However, the differences observed in epoxiconazole uptake owing to the surfactant were strongly positively related to the spread area of the formulation on the leaf surface. For all AIs, uptake increased in a similar manner with increasing molar surfactant concentration.
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Annangudi SP, Myung K, Avila Adame C, Gilbert JR. MALDI-MS Imaging Analysis of Fungicide Residue Distributions on Wheat Leaf Surfaces. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:5579-5583. [PMID: 25830667 DOI: 10.1021/es506334y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Improved retention and distribution of agrochemicals on plant surfaces is an important attribute in the biological activity of pesticide. Although retention of agrochemicals on plants after spray application can be quantified using traditional analytical techniques including LC or GC, the spatial distribution of agrochemicals on the plants surfaces has received little attention. Matrix assisted laser desorption/ionization (MALDI) imaging technology has been widely used to determine the distribution of proteins, peptides and metabolites in different tissue sections, but its application to environmental research has been limited. Herein, we probed the potential utility of MALDI imaging in characterizing the distribution of three commercial fungicides on wheat leaf surfaces. Using this MALDI imaging method, we were able to detect 500 ng of epoxiconazole, azoxystrobin, and pyraclostrobin applied in 1 μL drop on the leaf surfaces using MALDI-MS. Subsequent dilutions of pyraclostrobin revealed that the compound can be chemically imaged on the leaf surfaces at levels as low as 60 ng of total applied in the area of 1 μL droplet. After application of epoxiconazole, azoxystrobin, and pyraclostrobin at a field rate of 100 gai/ha in 200 L water using a track sprayer system, residues of these fungicides on the leaf surfaces were sufficiently visualized. These results suggest that MALDI imaging can be used to monitor spatial distribution of agrochemicals on leaf samples after pesticide application.
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Affiliation(s)
- Suresh P Annangudi
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
| | - Kyung Myung
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
| | - Cruz Avila Adame
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
| | - Jeffrey R Gilbert
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
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14
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Talbot EL, Yang L, Berson A, Bain CD. Control of the particle distribution in inkjet printing through an evaporation-driven sol-gel transition. ACS APPLIED MATERIALS & INTERFACES 2014; 6:9572-9583. [PMID: 24889140 DOI: 10.1021/am501966n] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A ring stain is often an undesirable consequence of droplet drying. Particles inside evaporating droplets with a pinned contact line are transported toward the periphery by radial flow. In this paper, we demonstrate how suspensions of laponite can be used to control the radial flow inside picoliter droplets and produce uniform deposits. The improvement in homogeneity arises from a sol-gel transition during evaporation. Droplets gel from the contact line inward, reducing the radial motion of particles and thus inhibiting the formation of a ring stain. The internal flows and propagation of the gelling front were followed by high-speed imaging of tracer particles during evaporation of the picoliter droplets of water. In the inkjet nozzle, the laponite network is broken down under high shear. Recovery of the low shear viscosity of laponite suspensions was shown to be fast with respect to the lifetime of the droplet, which was instrumental in controlling the deposit morphology. The radial and vertical particle distributions within dried deposits were measured for water droplets loaded with 1 and 5 wt % polystyrene spheres and various concentrations of laponite. Aggregation of the polystyrene spheres was suppressed by the addition of colloidal silica. The formulation can be tuned to vary the deposit profile from a ring to a pancake or a dome.
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Affiliation(s)
- Emma L Talbot
- Department of Chemistry, Durham University , Durham DH1 3LE, United Kingdom
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15
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Routh AF. Drying of thin colloidal films. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:046603. [PMID: 23502077 DOI: 10.1088/0034-4885/76/4/046603] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
When thin films of colloidal fluids are dried, a range of transitions are observed and the final film profile is found to depend on the processes that occur during the drying step. This article describes the drying process, initially concentrating on the various transitions. Particles are seen to initially consolidate at the edge of a drying droplet, the so-called coffee-ring effect. Flow is seen to be from the centre of the drop towards the edge and a front of close-packed particles passes horizontally across the film. Just behind the particle front the now solid film often displays cracks and finally the film is observed to de-wet. These various transitions are explained, with particular reference to the capillary pressure which forms in the solidified region of the film. The reasons for cracking in thin films is explored as well as various methods to minimize its effect. Methods to obtain stratified coatings through a single application are considered for a one-dimensional drying problem and this is then extended to two-dimensional films. Different evaporative models are described, including the physical reason for enhanced evaporation at the edge of droplets. The various scenarios when evaporation is found to be uniform across a drying film are then explained. Finally different experimental techniques for examining the drying step are mentioned and the article ends with suggested areas that warrant further study.
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Affiliation(s)
- Alexander F Routh
- BP Institute and Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK.
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D'Aquino S, Palma A, Angioni A, Schirra M. Residue levels and efficacy of fludioxonil and thiabendazole in controlling postharvest green mold decay in citrus fruit when applied in combination with sodium bicarbonate. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:296-306. [PMID: 23256745 DOI: 10.1021/jf304081z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The curative and protective activity of sodium bicarbonate (SBC) at 1% alone or in combination with fludioxonil (FLU), thiabendazole (TBZ), or FLU and TBZ together, between 50 and 600 mg/L, was evaluated on fruit of different citrus species and cultivars. Fruits were either artificially inoculated with a resistant (TBZ-r) or sensitive (TBZ-s) strain of Penicillium digitatum or not inoculated and incubated at 20 °C and 90% relative humidity (RH) for 7 days (incubated fruit) or stored at 1.5 °C for 21 days plus 7 days of simulated marketing conditions at 20 °C and 60% RH. The effectiveness of these treatments was related with treatment-induced changes of epicuticular wax morphology, the mode of distribution of SBC, TBZ, and FLU on the fruit surface, and FLU and TBZ fruit residue levels. SBC alone showed a weak activity against both strains of P. digitatum. Both TBZ and FLU were very effective at all rates used, and their activity markedly increased when combined together or with SBC, even at concentrations of 50-150 mg/L. Fruit treated with SBC either alone or in combination with TBZ and/or FLU increased weight loss, although no treatment damage was detected. Residue levels of TBZ generally increased when TBZ was combined with FLU and/or SBC, whereas those of FLU slightly increased only in treatment where FLU was combined with TBZ and SBC. Initial residues of TBZ and FLU when applied at 600 mg/L were around 2 and 1 mg/kg, respectively, several times below the lowest MRLs set by most important citrus-producing countries. In treatments with SBC or SBC plus TBZ or FLU, SEM observation of the fruit surface showed a smoothing of cuticular wax platelets' surface, whereas ESEM micrographs showed irregular spots of salt deposits of roundish to irregular shape. The apparently uneven distribution of SBC or SBC plus TBZ or FLU or SBC plus TBZ and FLU on fruit might in part reduce the potential beneficial effects of SBC or of fungicide-SBC mixtures.
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Affiliation(s)
- Salvatore D'Aquino
- Institute of Sciences of Food Production, National Research Council, Traversa La Crucca 3, Regione Baldinca, 07100 Sassari, Italy.
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Influence of surface orientation on the organization of nanoparticles in drying nanofluid droplets. J Colloid Interface Sci 2012; 377:456-62. [DOI: 10.1016/j.jcis.2012.03.024] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 03/08/2012] [Accepted: 03/09/2012] [Indexed: 11/18/2022]
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Hunsche M, Noga G. Effects of relative humidity and substrate on the spatial association between glyphosate and ethoxylated seed oil adjuvants in the dried deposits of sessile droplets. PEST MANAGEMENT SCIENCE 2012; 68:231-9. [PMID: 21800411 DOI: 10.1002/ps.2250] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 05/31/2011] [Accepted: 06/07/2011] [Indexed: 05/31/2023]
Abstract
BACKGROUND In recent years, several studies have shown the impact of adjuvants on the characteristics of herbicide deposits on leaf surfaces. Until now, most studies have addressed the distribution of active ingredients (AIs), whereas few experiments have focused on the location of the adjuvants. The objective of this study was a systematic examination of the particle distribution profile of both the AI (glyphosate, Gly) and the adjuvants after the application of sessile microdroplets on hydrophobic (Teflon) and hydrophilic (glass and aluminium) model surfaces. RESULTS The association degree (AD) was surface dependent and specific for the tested adjuvants. In general, the rather hydrophobic adjuvant RSO 5 showed decreasing AD with Gly at increasing relative humidity (RH) levels. The rather hydrophilic RSO 60 adjuvant displayed higher AD between the compounds at a higher RH. A high concentration of the adjuvant reduced the AD for both of the RSO adjuvants evaluated. CONCLUSION The combination of surface properties, the type of adjuvant and the relative humidity determines the degree of association between Gly and the adjuvants. The present results suggest that the interaction between the AI and an adjuvant determines whether spatial separation occurs, whereas physical processes (e.g. capillary particle movement, inward and outward Marangoni flows and the evaporation rate) are decisive for the extent of the separation. Coffee-ring structures were formed exclusively with the adjuvant+Gly mixtures, whereas Gly alone formed either one big deposit or several small islands distributed within the droplet footprint.
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Affiliation(s)
- Mauricio Hunsche
- University of Bonn, Institute of Crop Science and Resource Conservation-Horticultural Sciences, Bonn, Germany.
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Sopeña F, Maqueda C, Morillo E. Formulation affecting alachlor efficacy and persistence in sandy soils. PEST MANAGEMENT SCIENCE 2009; 65:761-768. [PMID: 19350536 DOI: 10.1002/ps.1750] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
BACKGROUND The development of controlled-release formulations of alachlor to extend the period of weed control was studied. This extended duration reduces the need for high herbicide application rates that could lead to environmental contamination. For this purpose, the influence of formulation, as well as the influence of soil characteristics, on alachlor efficacy and persistence in soil of a commercial formulation (CF) and different ethylcellulose microencapsulated formulations (MEFs) was evaluated. RESULTS Higher alachlor rates yielded an enhanced initial herbicidal activity. The prolonged release of alachlor provided by the MEFs resulted in a higher herbicidal efficacy and a longer period of weed control compared with the effects of CF in the two soils tested (at 40 days after treatment, oat growth inhibition for CF and MEFs was 1.96% and 93.5% respectively). Soil characteristics strongly influenced alachlor efficacy and weed control by MEFs. The highest alachlor efficacy and persistence were observed in the soil with lowest microbial activity and clay and organic matter content. CONCLUSIONS The use of MEFs can be advantageous because they permit the maintenance of the desired concentration of the herbicide in the soil for longer periods of weed control.
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Affiliation(s)
- Fátima Sopeña
- Institute of Natural Resources and Agrobiology (CSIC), Apdo 1052, 41080 Seville, Spain.
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