There have been many changes in production agriculture over the last 20 years. The use of herbicide resistant crops has become common place in production agriculture. However, the release of crops resistant to auxin herbicides has brought more attention to the pesticide application process regardless of the type of pesticide applied. Moreover, controlling off-target movement of pesticides has become an integral part of the day to day farming tasks. The use of deposition aids when applied with water has been documented; however, the effect of deposition aids on pesticide application is not well understood. Based on these findings, selecting a deposition aid not only can be affected by the pesticide used but also the crop in question. Additionally, label restrictions on auxin herbicide application in auxin tolerant crops brings an additional problem to cotton growers. The use of insecticides in conjuction with herbicide applications has been commonplace for many growers across the cotton belt. However, smaller droplets have been utilized to increase coverage of these insecticides. Data presented in these findings suggest that larger droplets can still have good levels of efficacy and in some instances increase yield. The use of auxin tolerant crops allows for usage of addition POST herbicides to cotton; however, the effect of these tank mix applications on ctrop injury is not well understood. In both EnlistTM and Xtend® Flex cotton levels of injury were increased when glufosinate and S-metolachlor were applied in a tank mix. However, yield was not negatively impacted in either study.

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Orientador: Ulisses Rocha Antuniassi / Banca: Otavio Jorge Gricoli Abi Saab / Banca: Marco Antonio Gandolfo / Banca: Carlos Gilberto Raetano / Banca: Paulo Roberto Arbex Silva / Resumo: A alta demanda por agrotóxicos pelos sistemas de produção agrícola, aliada ao possível uso inadequado desses produtos, torna a deriva um dos maiores problemas potenciais da agricultura atual, e a escolha correta de adjuvantes pode ser uma das alternativas para minimizar os impactos negativos causados pela deriva nas pulverizações. Este trabalho foi desenvolvido com o objetivo de avaliar o efeito proporcionado por diferentes grupos de adjuvantes nas propriedades físicas e químicas das soluções, no espectro de gotas, bem como no potencial do risco de deriva quantificado em túnel de vento, como forma de auxiliar na escolha correta desses produtos para melhor utilização nas aplicações de agrotóxicos. Foram selecionados 18 adjuvantes comumente utilizados em misturas com agrotóxicos em pulverizações agrícolas, avaliando-se as propriedades físicas e químicas dos mesmos em soluções aquosas (viscosidade, densidade, tensão superficial e condutividade elétrica), o espectro de gotas e o potencial de deriva medido em túnel de vento. O experimento foi composto de 33 tratamentos, tendo a água como testemunha adicional, resultantes da diluição dos adjuvantes em diferentes concentrações, com três repetições. Para os ensaios em túnel de vento e análise de espectro de gotas foi utilizada uma ponta de pulverização XR8003 VK na pressão de 200 kPa, gerando um padrão de gotas médias. A deriva foi coletada no túnel de vento com fluxo de ar na velocidade de 2 m s-1. O corante Azul Brilhante a 0,6% (m v-1) foi utilizado como marcador para todas as soluções pulverizadas visando a quantificação da deriva por espectrofotometria. Os resultados mostraram que a adição de adjuvantes alterou as propriedades físicas e químicas das soluções aquosas em diferentes magnitudes, dependendo da concentração utilizada. Os surfatantes organosilicones... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Due to the high demand for pesticide by the agricultural systems and the possible inadequate use of the products, drift became one of the biggest concerns of the modern agriculture, and the correct use of adjuvants may be one of the possible alternatives to minimize the negative impact of spray operations. This study was developed to evaluate the effect of different adjuvants on physical and chemical properties of spray solutions, droplets spectra as well as drift potential measured in wind tunnel, aiming the correct choice of adjuvants to improve efficiency in pesticide application. For this purpose 18 commercially available agricultural spray adjuvants were selected including products usually mixed up with pesticides in the sprayer tank. The evaluation included physical and chemical properties of spray solutions (viscosity, density, surface tension and electric conductivity), droplets spectra and drift risk potential measured in wind tunnel. The experiment was set up with 33 treatments (solutions) obtained from 18 adjuvants used in different concentrations with 3 replications, including pure water as a standard. For wind tunnel tests and droplet spectra analysis it was used a Teejet XR8003 flat fan nozzles at 200 kPa (medium droplets) and all solutions were mixed up with a food color dye (Blue FDC) at 0,6% m v-1 for spectrophotometry analysis of drift deposits on the wind tunnel. The results showed that the addition of adjuvants changed physical and chemical properties of spray solutions in different magnitudes according to the product concentration. The organosilicon surfactants (Silwet 0.1% e 0.2% and BreakThru 0,1%) had the lowest values for surface tension, while the drift retardant based polymers (Define 0,06% e 0,12%) had the highest values for viscosity and density. There was high correlation between the Volume Median Diameter (VMD) and percentage of droplets smaller... (Completo abstract click electronic access below) / Doutor

Spray models are increasingly becoming the principal tools in the design and development of gas turbine combustors. Spray modeling requires a knowledge of the liquid atomization process, and the sizes and velocities of subsequently formed droplets as initial conditions. In order to have a better understanding of the liquid atomization process,the breakup characteristics of plane liquid sheets in co-flowing gas streams are investigated by means of linear and nonlinear hydrodynamic instability analyses. The liquid sheet breakup process is studied for initial sinuous and varicose modes of disturbance. It is observed that the sheet breakup occurs at half-wavelength intervals for an initial sinuous disturbance and at full-wavelength intervals for an initial varicose disturbance. It is also found that under certain operating conditions, the breakup process is dictated by the initial varicose disturbance compare to its sinuous counterpart. Further, the breakup process is studied for the combined mode and it is found that the sheet breakup occurs at half- or full-wavelength intervals depending on the proportion of the individual sinuous and varicose disturbances. In general, the breakup length decreases with the increase in the Weber number, gas-to-liquid velocity and density ratios. A predictive model of the initial droplet size and velocity distributions for the subsequently formed spray is also formulated here. The present model incorporates the deterministic aspect of spray formation by calculating the breakup length and the mass-mean diameter and the stochastic aspect by statistical means through the maximum entropy principle based on Bayesian entropy. The two sub-models are coupled together by the various source terms signifying the liquid-gas interaction and a prior distribution based on instability analysis, which provides information regarding the unstable wave elements on the two liquid-gas interfaces. Experimental investigation of the breakup characteristics of the liquid sheet is performed by a high speed CCD camera and the measurement of the initial droplet size and distributions is conducted by phase-Doppler interferometry. Good agreement of the theoretical breakup length with the experiment is obtained for a planar, an annular and a gas turbine nozzle. The predicted initial droplet size and velocity distributions show reasonably satisfactory agreement with experimental data for all the three types of nozzles. Hence this spray model can be utilized to predict the initial droplet size and velocity distributions in sprays, which can then be implemented as a front-end subroutine to the existing computer codes.

Spray models are increasingly becoming the principal tools in the design and development of gas turbine combustors. Spray modeling requires a knowledge of the liquid atomization process, and the sizes and velocities of subsequently formed droplets as initial conditions. In order to have a better understanding of the liquid atomization process,the breakup characteristics of plane liquid sheets in co-flowing gas streams are investigated by means of linear and nonlinear hydrodynamic instability analyses. The liquid sheet breakup process is studied for initial sinuous and varicose modes of disturbance. It is observed that the sheet breakup occurs at half-wavelength intervals for an initial sinuous disturbance and at full-wavelength intervals for an initial varicose disturbance. It is also found that under certain operating conditions, the breakup process is dictated by the initial varicose disturbance compare to its sinuous counterpart. Further, the breakup process is studied for the combined mode and it is found that the sheet breakup occurs at half- or full-wavelength intervals depending on the proportion of the individual sinuous and varicose disturbances. In general, the breakup length decreases with the increase in the Weber number, gas-to-liquid velocity and density ratios. A predictive model of the initial droplet size and velocity distributions for the subsequently formed spray is also formulated here. The present model incorporates the deterministic aspect of spray formation by calculating the breakup length and the mass-mean diameter and the stochastic aspect by statistical means through the maximum entropy principle based on Bayesian entropy. The two sub-models are coupled together by the various source terms signifying the liquid-gas interaction and a prior distribution based on instability analysis, which provides information regarding the unstable wave elements on the two liquid-gas interfaces. Experimental investigation of the breakup characteristics of the liquid sheet is performed by a high speed CCD camera and the measurement of the initial droplet size and distributions is conducted by phase-Doppler interferometry. Good agreement of the theoretical breakup length with the experiment is obtained for a planar, an annular and a gas turbine nozzle. The predicted initial droplet size and velocity distributions show reasonably satisfactory agreement with experimental data for all the three types of nozzles. Hence this spray model can be utilized to predict the initial droplet size and velocity distributions in sprays, which can then be implemented as a front-end subroutine to the existing computer codes.

In mass spectrometry an electrospray is commonly used as an ion source. At high sample flow rates a sheath co-flow of gas around the electrospray emitter is employed. The co-flow of gas reduces contamination and increases signal sensitivity in the mass spectrometer’s results. This work characterizes the operation of an electrospray with co-flowing air for various operating conditions. It is found that a co-flowing air has a negligible effect on droplet size for the spindle and cone jet modes while it only reduces the droplet size marginally in the unstable mode. In the high flow rate unstable mode, the addition of air seems to have no real effect on droplet size. In summary, the electrospray with co-flowing air produces a denser and more focused spray with similar droplet size and distribution than that of the un-nebulized spray. This explains why using co-flowing air in mass spectrometry applications improves the signal quality, since it allows for the focusing of droplets produced into the inlet and also aids in the breakup of larger droplets.

In mass spectrometry an electrospray is commonly used as an ion source. At high sample flow rates a sheath co-flow of gas around the electrospray emitter is employed. The co-flow of gas reduces contamination and increases signal sensitivity in the mass spectrometer’s results. This work characterizes the operation of an electrospray with co-flowing air for various operating conditions. It is found that a co-flowing air has a negligible effect on droplet size for the spindle and cone jet modes while it only reduces the droplet size marginally in the unstable mode. In the high flow rate unstable mode, the addition of air seems to have no real effect on droplet size. In summary, the electrospray with co-flowing air produces a denser and more focused spray with similar droplet size and distribution than that of the un-nebulized spray. This explains why using co-flowing air in mass spectrometry applications improves the signal quality, since it allows for the focusing of droplets produced into the inlet and also aids in the breakup of larger droplets.

Made available in DSpace on 2014-06-11T19:28:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-11Bitstream added on 2014-06-13T19:58:11Z : No. of bitstreams: 1 iost_car_me_botfca.pdf: 1768880 bytes, checksum: 15165f8112f914fcc04feae599644f1d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Este trabalho teve como objetivo avaliar o efeito de adjuvantes sobre algumas propriedades de soluções aquosas, como tamanho de gotas, tensão superficial dinâmica e ângulo de contato das gotas em diferentes superfícies, natural e artificial, bem como avaliar o efeito desses produtos sobre a deposição e a deriva utilizando como alvo três espécies de plantas daninhas (Euphorbia heterophylla, Ipomoea grandifolia e Brachiaria plantaginea). Seis formulações de adjuvantes (Antideriva®, Uno®, Pronto 3®, Li-700®, Supersil® e Silwet L-77®) foram avaliadas em soluções aquosas contendo a dose recomendada do produto comercial e o dobro dela. As avaliações de tamanho de gotas foram feitas com três diferentes pontas de pulverização (AXI 110 015, 110 02 e 110 03) por um equipamento a laser (Mastersizer, Malvern) na pressão de trabalho de 414 kPa. Os ângulos de contato formados pelas gotas em duas superfícies, uma hidrofílica (vidro) e outra hidrofóbica (óxido de alumínio), foram obtidos por análise de imagens capturadas por uma câmera digital. As avaliações de deposição e deriva das soluções aquosas associadas ou não aos adjuvantes e contendo o traçador azul brilhante (0,15% v/v), foram feitas sobre diferentes espécies vegetais, e com o auxílio de coletores laterais (placas de Petri). A quantificação do traçador foi por feita espectrofotometria. A tensão superficial dinâmica e o ângulo de contato formado sobre as superfícies adaxiais das folhas foram medidos por um tensiômetro. Em relação ao tamanho de gotas, o adjuvante Antideriva, com dobro da dose recomendada, foi o que apresentou os menores valores percentuais de volume de gotas com diâmetro menor que 100 µm e os maiores DMV, para todas as pontas em teste. As soluções que proporcionaram as maiores... / The aim of this work is to evaluate the effect of adjuvants on droplet size, dynamic surface tension and contact angle formed by the water drops in different surfaces, as well as evaluating the adjuvants effect on the deposit and the spray drift using three species of plants (Euphorbia heterophylla, Ipomoea grandifolia e Brachiaria plantaginea). We studied six adjuvants formulations (Antideriva , Uno , Pronto 3 , Li- 700 , Supersil and Silwet L-77 ) in water solution using the dosage recommended by the manufacturer and twice that dose. The droplet size of three different nozzles (AXI 110 015, 110 02 and 110 03), for a constant pressure of 414 kPa, were evaluated by a laser system. The contact angles of the drops in two surfaces (hydrophilic and hydrophobic) were obtained by the analysis of images captured by a digital camera. The evaluation of deposition and spray drift deposition of the solutions containing brilliant-blue dye (0.15 % v/v) were carried out in different plant species. The solutions were collected laterally using Petri dishes, and the brilliant-blue dye content quantified by absorption spectroscopy. The dynamic surface tension and the angle formed on the surfaces of the leaves were measured by a tensiometer. Regarding the droplet size, for all the nozzles tested the adjuvant Antideriva with twice the recommended dose presented the lowest percentage of spray volume in droplets with diameters smaller than 100µm, and highest VMD. The solutions that provided the highest reductions in the dynamic surface tension and the smallest contact angle were the ones with the adjuvants Silwet L-77 and Supersil for both appraised doses. The largest deposit average for I. grandifolia was obtained by using Uno with double of the dose; for B. ...(Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:31:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-07Bitstream added on 2014-06-13T19:20:42Z : No. of bitstreams: 1 oliveira_rb_dr_botfca.pdf: 2430018 bytes, checksum: 83351333d3d9c8a67f6e396d9780730d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A alta demanda por agrotóxicos pelos sistemas de produção agrícola, aliada ao possível uso inadequado desses produtos, torna a deriva um dos maiores problemas potenciais da agricultura atual, e a escolha correta de adjuvantes pode ser uma das alternativas para minimizar os impactos negativos causados pela deriva nas pulverizações. Este trabalho foi desenvolvido com o objetivo de avaliar o efeito proporcionado por diferentes grupos de adjuvantes nas propriedades físicas e químicas das soluções, no espectro de gotas, bem como no potencial do risco de deriva quantificado em túnel de vento, como forma de auxiliar na escolha correta desses produtos para melhor utilização nas aplicações de agrotóxicos. Foram selecionados 18 adjuvantes comumente utilizados em misturas com agrotóxicos em pulverizações agrícolas, avaliando-se as propriedades físicas e químicas dos mesmos em soluções aquosas (viscosidade, densidade, tensão superficial e condutividade elétrica), o espectro de gotas e o potencial de deriva medido em túnel de vento. O experimento foi composto de 33 tratamentos, tendo a água como testemunha adicional, resultantes da diluição dos adjuvantes em diferentes concentrações, com três repetições. Para os ensaios em túnel de vento e análise de espectro de gotas foi utilizada uma ponta de pulverização XR8003 VK na pressão de 200 kPa, gerando um padrão de gotas médias. A deriva foi coletada no túnel de vento com fluxo de ar na velocidade de 2 m s-1. O corante Azul Brilhante a 0,6% (m v-1) foi utilizado como marcador para todas as soluções pulverizadas visando a quantificação da deriva por espectrofotometria. Os resultados mostraram que a adição de adjuvantes alterou as propriedades físicas e químicas das soluções aquosas em diferentes magnitudes, dependendo da concentração utilizada. Os surfatantes organosilicones... / Due to the high demand for pesticide by the agricultural systems and the possible inadequate use of the products, drift became one of the biggest concerns of the modern agriculture, and the correct use of adjuvants may be one of the possible alternatives to minimize the negative impact of spray operations. This study was developed to evaluate the effect of different adjuvants on physical and chemical properties of spray solutions, droplets spectra as well as drift potential measured in wind tunnel, aiming the correct choice of adjuvants to improve efficiency in pesticide application. For this purpose 18 commercially available agricultural spray adjuvants were selected including products usually mixed up with pesticides in the sprayer tank. The evaluation included physical and chemical properties of spray solutions (viscosity, density, surface tension and electric conductivity), droplets spectra and drift risk potential measured in wind tunnel. The experiment was set up with 33 treatments (solutions) obtained from 18 adjuvants used in different concentrations with 3 replications, including pure water as a standard. For wind tunnel tests and droplet spectra analysis it was used a Teejet XR8003 flat fan nozzles at 200 kPa (medium droplets) and all solutions were mixed up with a food color dye (Blue FDC) at 0,6% m v-1 for spectrophotometry analysis of drift deposits on the wind tunnel. The results showed that the addition of adjuvants changed physical and chemical properties of spray solutions in different magnitudes according to the product concentration. The organosilicon surfactants (Silwet 0.1% e 0.2% and BreakThru 0,1%) had the lowest values for surface tension, while the drift retardant based polymers (Define 0,06% e 0,12%) had the highest values for viscosity and density. There was high correlation between the Volume Median Diameter (VMD) and percentage of droplets smaller... (Completo abstract click electronic access below)

The body of literature on the impact of emulsion particle size on oxidation rates is unclear. This could be because emulsions are typically polydisperse and the oxidation rate of individual droplets is impossible to discern. Flow cytometry is a technique for studying individual cells and their subpopulations using fluorescence technologies. It is possible that individual emulsion droplets could also be characterized by flow cytometry as a novel approach for studying lipid oxidation. Typical emulsion droplets are too small to be visualized by flow cytometer, so emulsions were prepared to have droplets > 2 μm; weighting agent and xanthan gum were added to minimize creaming during storage. A radical-sensitive lipid-soluble fluorescence probe (BODIPY665/676) was added to the lipid used to prepare the emulsion so that the susceptibility of individual emulsion droplets could be determined. The results showed that in a polydisperse emulsion system, small droplets were oxidized faster than large droplets. Using mixtures of emulsions with and without prooxidants, it was possible to see the transfer of prooxidants between droplets, a process that is influenced by surfactant and salt concentrations. For example, surfactants micelles can transfer prooxidants to neighboring non-oxidized droplets and cause fluorescence loss when surfactant concentration was higher than critical micelle concentration (CMC). Transfer of prooxidants was promoted by adding NaCl and free fatty acid which could be attributed to the lower CMC. This study showed the potential for applying flow cytometry on oxidation of individual emulsion droplets.