945 resultados para Anionic Surfactants
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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A novel, easily renewable nanocomposite interface based on layer-by-layer (LbL) assembled cationic/anionic layers of carbon nanotubes customized with biopolymers is reported. A simple approach is proposed to fabricate a nanoscale structure composed of alternating layers of oxidized multiwalled carbon nanotubes upon which is immobilized either the cationic enzyme organophosphorus hydrolase (OPH; MWNT−OPH) or the anionic DNA (MWNT−DNA). The presence of carbon nanotubes with large surface area, high aspect ratio and excellent conductivity provides reliable immobilization of enzyme at the interface and promotes better electron transfer rates. The oxidized MWNTs were characterized by thermogravimetric analysis and Raman spectroscopy. Fourier transform infrared spectroscopy showed the surface functionalization of the MWNTs and successful immobilization of OPH on the MWNTs. Scanning electron microscopy images revealed that MWNTs were shortened during sonication and that LbL of the MWNT/biopolymer conjugates resulted in a continuous surface with a layered structure. The catalytic activity of the biopolymer layers was characterized using absorption spectroscopy and electrochemical analysis. Experimental results show that this approach yields an easily fabricated catalytic multilayer with well-defined structures and properties for biosensing applications whose interface can be reactivated via a simple procedure. In addition, this approach results in a biosensor with excellent sensitivity, a reliable calibration profile, and stable electrochemical response.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The Asian rust currently is the main disease of soybean culture, having as characteristics the difficult control, by start at the bottom of plants where penetration of the droplets is harder. The fine droplets has been used with the intention of improve the penetration and increase efficiency of agrochemicals, but that are losses by drift easily. New products have been developed to increase deposition of the drops at targets. The aim of this work was evaluate the TA- 35 capacity to improving the deposition of fungicides spray solution with or without mineral oil by aerial and ground applications. Was used a factorial 3x2, three spray solutions composed by Priori Xtra (concentrated suspension of azoxystrobin 200 g L-1 + cyproconazole 80 g L-1 ) mixed with adjuvants, Nimbus (emulsifiable concentrate containing aliphatic hydrocarbons 428 g L-1 ) and TA-35 (soluble concentrate containing sodium lauryl ether sulfate, surfactants, sequestering agents and emulsifiers), in aerial and ground applications. In ground applications was used 50 L ha-1 , TXA 8002 VS spray nozzles and on aerials was used 15 L ha-1 , Turboaero atomizer, both applying fine droplets. Was utilized the Brilliant Blue (FD & C n. 1) tracer to determine the deposits. There were used glass slides as targets to collect spray droplets. After to extract the tracer of the targets using distilled water, the samples were analyzed by spectrophotometry, thereby was possible quantify the tracer deposited on each glass slide. A study to evaluate possible losses of the tracer by degradation or retention also was done. The comparative analysis of treatments was done by statistical method "Confidence Interval for Differences Between the Averages" with 95% of confidence degree (IC95%). There was degradation or retention of the tracer between the processes of application of the droplets and the processing of the samples. The deposition averages with the presence of TA-35 were greatest for both sprayers however, there were not significant differences among the treatments. The viability of TA-35 use may consider other parameters or complementary studies.
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The aim of this work was to evaluate the effect of the addition of different surfactants in physical and chemical properties of spray solutions, droplets spectra and drift potential on agricultural spraying. The surfactants and concentrations (v v-1) were: Haiten (0.1%), Antideriva and Intec (0.05% and 0.1%). The following characteristics were analyzed: surface tension, viscosity, density and electric conductivity. The droplet size spectrum was determined by a laser particle analyzer (Mastersizer S®, version 2.15) including measurements of volume medium diameter (VMD), the percent of droplets below 50 and 100 μm (V50 e V100) and index span. In order to estimate the drift potential, a series of wind tunnel tests were performed with a Teejet XR 8003 flat fan nozzle at 200 kPa (medium droplets) used to apply the spray solutions containing water, the adjuvants and a food color dye (Brilliant blue FD & C no 1) at 0,6% m v-1. The drift was collected on nylon strips transversally fixed along the tunnel at different distances from the nozzle and different high from the bottom part of the tunnel. Drift deposits were evaluated by spectrophotometry. The results showed that the addition of adjuvants changed physical and chemical properties of spray solutions in different magnitudes according to the surfactant. Surfactants changed the droplet spectrum and drift potential, indicating that higher VMD and smaller V100 induced higher percentage of drift.
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Pós-graduação em Engenharia Mecânica - FEG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The development of nanostructured materials have aroused great interest of the industries all over the country, since they enable the development of devices that can be used as gate insulators on silicon transistors, electrochromic devices, solid electrolyte oxygen sensors and as a photoluminescent materials . In this project, it is proposed to investigate the optical properties of CeO2 modified with rare earth Er processed in hydrothermal-microwave. The synthesis of one-dimensional nanostructures (1D) was measured from dilute aqueous solutions of acids and salts of starting reagents in the presence of chemical basis, after these aqueous solutions were processed on hydrothermal-microwave to particle growth. The particles obtained after processing were characterized by X-ray Diffraction, Rietveld Analysis and Raman Spectroscopy. The particle morphology was observed by scanning electron microscopy with field emission gun. The synthesis of 1D nanostructures are evaluated for different surfactants and starting precursors (ceria different salts), pH, temperature and pressure which can modify the morphology of the nanostructures. Combining laboratory experiments and theoretical calculations it was desired to understand the organization of the nanoparticles and their resulting structure. Strict control of chemical homogeneity, crystal structure, microstructure and interaction of the CeO2 cluster with different surfactants using the Hartree-Fock method, was intended to obtain properties compatible with their use in catalysts and optical devices. The use of mineralizer agent KOH and 8 minutes of processing time synthesis conditions were chosen to evaluate the effect of Er dopant. It has been proved that this doping with rare earth increases the photoluminescent properties of the compound obtained without change the structural and morphological propreties of ceria
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Crop depredation by red-winged blackbirds (Agelaius phoeniceus) causes serious economic losses to agricultural crops each year in both Canada and the United States. The concentration of vulnerable, monocultural crops, particularly corn, during periods when large flocks of blackbirds congregate in roosting areas prior to migration has invariably led to heavy feeding pressure (Stone et al., 1972; Wiens and Dyer, 1975; Tyler et al., 1978). Efforts to reduce damage levels by mechanical and chemical dispersal agents have been largely unsuccessful, at least in terms of a long-term solution to the problem. Recently, the lethal control of blackbird populations using surfactants has been proposed. However, the potential repercussions of the removal of substantial numbers of birds from northern breeding areas are virtually unknown (Robertson et al., 1978). Much of the research dealing with the feeding ecology of red-winged blackbirds has been limited to fall and winter periods when large aggregations of birds are actively involved in crop depredation (Goddad, 1969; Williams, 1976; Dolbeer et al., 1978) or pose a potential health hazard (Monroe and Cronholm, 1976). However, what is not known is the degree to which the removal of deleterious weed seed and insect pests cited in several studies (Bird and Smith, 1964; Mott et al., 1972; Robertson et al., 1978) might be of potential value to agriculture. The issue of whether the benefits derived from redwing foraging compensate for the negative aspects associated with crop depredation and health hazards remains largely unresolved. The present study attempted to evaluate the pest status of this species using diet information derived from food habits analysis conducted during the residency of red- winged blackbirds in a northern breeding area. By determining how the feeding ecology of red-winged blackbirds varies on a seasonal basis, among different breeding habitats and between sexes, we hoped to determine more realistically which segments of the population might be responsible for the greatest benefits or detriments and, thereby, more accurately evaluate the economic impact of the species as a whole. To achieve this aim, the study provides an accurate description of the common insects and weed pests utilized by redwings. By determining the relative proportions of those items known to be detrimental, we hoped to illustrate, at least qualitatively, the degree to which redwing foraging is comprised of both beneficial and harmful components.
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The development of nanostructured materials have aroused great interest of the industries all over the country, since they enable the development of devices that can be used as gate insulators on silicon transistors, electrochromic devices, solid electrolyte oxygen sensors and as a photoluminescent materials . In this project, it is proposed to investigate the optical properties of CeO2 modified with rare earth Er processed in hydrothermal-microwave. The synthesis of one-dimensional nanostructures (1D) was measured from dilute aqueous solutions of acids and salts of starting reagents in the presence of chemical basis, after these aqueous solutions were processed on hydrothermal-microwave to particle growth. The particles obtained after processing were characterized by X-ray Diffraction, Rietveld Analysis and Raman Spectroscopy. The particle morphology was observed by scanning electron microscopy with field emission gun. The synthesis of 1D nanostructures are evaluated for different surfactants and starting precursors (ceria different salts), pH, temperature and pressure which can modify the morphology of the nanostructures. Combining laboratory experiments and theoretical calculations it was desired to understand the organization of the nanoparticles and their resulting structure. Strict control of chemical homogeneity, crystal structure, microstructure and interaction of the CeO2 cluster with different surfactants using the Hartree-Fock method, was intended to obtain properties compatible with their use in catalysts and optical devices. The use of mineralizer agent KOH and 8 minutes of processing time synthesis conditions were chosen to evaluate the effect of Er dopant. It has been proved that this doping with rare earth increases the photoluminescent properties of the compound obtained without change the structural and morphological propreties of ceria
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)