• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 7
  • 1
  • 1
  • Tagged with
  • 23
  • 5
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Redox Active Ligands To Facilitate Reactivity From Redox Restricted Metals

Matthew C Hewitt (11197530) 29 July 2021 (has links)
The synthesis of metal-redox active ligand complexes is described, along with reactivity studies aimed at facilitating novel C-N bond forming reactions. A copper bis(iminosemiquinone) structure is characterized, analyzed and its reduction series are characterized and the reactivity of the Cu(II) bis(amidophenolate) analog is investigated with tosyl azide. The identification of the major reaction product and its characterization is detailed, with reaction sensitivities and heavily distorted x-ray diffraction single crystal structure generating a complex data set. The characterization of the isolated product is ongoing, with EPR studies aimed at identifying the radical nature of the complex. Unusual solvent effects and solubility issues have been noted with these initial EPR studies and more data is necessary before analysis can be properly attempted. An ytterbium bis(amidophenolate) complex was synthesized and its reactivity studied with aryl azides. Initial reactivities generate the first documented lanthanide tetrazenes in-lieu of the targeted ytterbium imido. Reactivities and characterization of these complexes support a stable, heavily ionic tetrazene-metal complex with no observed redox nature, UV light sensitivities, or imido azide-tetrazene equilibrium observed in various tetrazene transition metal complexes. Synthesis of a sterically blocked ytterbium imido was attempted, utilizing DMAP. Initial isolation was achieved with characterization and reactivity studies supporting the imido nature of the complex. The weak coordinating of the DMAP provided instability that proved in opposition to crystallization, however, so the imido could not be confirmed. Initial reactions using alternative steric hinderance from triphenylphosphine oxide and pyridine N-oxide prove promising to increasing the stability of the presumed ytterbium imido. Organic synthesis was performed generating a potential antibacterial agent. The synthesis of cyclopropenes was initiated as antagonists for ETR proteins in fruits and plants. The intermediates proved highly sensitive to harsh chemical conditions, which was overcome utilizing a tin-mediated Barbier allylation. The cyclopropene alcohol synthon was synthesized, though protecting group optimization is necessary.
22

Tecnologia de aplicação aérea e terrestre no controle da ferrugem alaranjada (Puccinia Kuehnni (W. KRÜGER) E.J. BUTLER) da cana-de-açúcar (Saccharum spp) / Aerial and ground application of phytosanitary products to control orange rust in sugarcane

Alves, Thales Cassemiro 26 February 2016 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / A aplicação de produtos fitossanitários no setor sucroenergético, até recentemente, estava focada sobretudo no controle de plantas infestantes. Com o surgimento epidêmico da ferrugem alaranjada da cana-de-açúcar, causada pelo fungo Puccinia kuehnii, as aplicações de fungicidas tornaram-se necessárias nas variedades suscetíveis. Porém, poucos estudos concernentes à tecnologia de aplicação são encontrados na literatura, especialmente em relação à aplicação aérea e aos efeitos promovidos na fisiologia das plantas. Este trabalho objetivou estudar as diferentes formas de aplicação de fungicidas na cana-de-açúcar, variedade SP81-3250, no que se refere a deposição de calda, controle da doença, produtividade e efeitos fisiológicos. Executaram-se duas aplicações de fungicidas dos grupos químicos Estrobilurinas e Triazóis nas unidades experimentais. Nas aplicações aéreas, utilizaram-se duas taxas de aplicação (30 e 40 L ha-1) e três orientações dos bicos na barra de pulverização (135º, 0º e 90º em relação à linha de voo), sendo avaliado apenas na segunda aplicação o ângulo de 90o, considerado como padrão aéreo da Usina Vale do Tijuco. Já na aplicação terrestre, utilizaram-se taxa de aplicação de 200 L ha-1 e pontas de pulverização de jato plano com indução de ar (AI11004-VS). Esse procedimento, considerado como padrão terrestre da referida Usina, foi avaliado apenas na primeira aplicação. Dividiu-se a pesquisa em duas partes. Na primeira, avaliaram-se as deposições da calda no dossel superior da cultura e as perdas para o solo, por meio da adição à calda do traçador Azul Brilhante para ser quantificado por absorbância em espectrofotometria. Além disso, conduziu-se um estudo do espectro de gotas por meio da avaliação dos impactos em papéis hidrossensíveis, quantificou-se a severidade da doença nas folhas a partir de um programa de análise de imagens digitalizadas e mensurou-se a biometria da cana-de-açúcar. Já na segunda parte da pesquisa, foram realizadas avaliações de trocas gasosas com analisador de gás IRGA e da quantidade de clorofilas a e b com um clorofilômetro. Os dados foram analisados usando o teste T de Student, para amostras independentes, a 0,05 de significância. A aplicação aérea com menor volume de calda (de 30 L ha-1) proporcionou deposição de calda fungicida e produtividade maiores que as da aplicação com 40 L ha-1. A angulação dos bicos de pulverização na barra da aeronave voltados para trás, de forma a produzir gotas maiores, não interferiu no resultado da aplicação, demonstrando ser uma alternativa viável para a redução de deriva. A aplicação aérea com gotas finas e médias proporcionou maior deposição de calda nas folhas de cana-de-açúcar e menor perda para o solo, em comparação com a aplicação terrestre com gotas extremamente grossas. A aplicação de fungicida gerou incrementos de produtividade superiores a 20 t ha-1, independentemente da forma de aplicação, podendo alcançar 40 t ha-1 com aplicações aéreas. A aplicação aérea proporcionou, em geral, melhores taxas fotossintéticas em relação à aplicação terrestre, com melhor desempenho da fotossíntese e maior concentração das clorofilas a e b no limbo foliar. Não foram detectadas diferenças nas trocas gasosas entre as aplicações aéreas nas distintas condições operacionais de taxa de aplicação e angulação do bico de pulverização na barra. / The application of phytosanitary products in the sugar and ethanol industry has usually targeted pest control. With the epidemic rise in orange rust in sugarcane, caused by fungus Puccinia kuehnii, applications of fungicides are now necessary to protect susceptible varieties. However, few studies have focused on the impacts of the application technology, especially regarding the aerial application and its effects on the plant physiology. This study investigated the different forms of application of fungicides in sugarcane variety SP81-3250 and their association with spray deposition, disease control, productivity, and plant physiology. Experimental units received two different applications of fungicides of the chemical groups strobilurin and triazole. Aerial applications were performed using two different volume rates (30 and 40 L ha-1) and spray bar nozzles in three different angles (135°, 0° and 90 ° to the flight line). The 90° angle, the aerial standard used at sugar factory Usina Vale do Tijuco, was assessed at the second application only. Ground applications were performed using rates of 200 L ha-1 and flat fan spray nozzles with air induction (AI11004-VS). This procedure, used as the ground standard in the sugar factory, was measured in the first application only. The research was divided into two parts. In the first part, spray deposition in the upper canopy and losses to soil were assessed using tracer Brilliant Blue for absorbance spectrophotometry. It addition, sugarcane biometrics was measured, droplet spectrum was analyzed through the assessment of impacts on water sensitive paper, and disease severity on leaves was quantified using a digital image analysis software program. In the second part, gas exchange was assessed using gas analyzer IRGA, and the amount of chlorophyll a and b was measured using a chlorophyll meter. Data were analyzed using Student’s t test for independent samples, with significance set at 0.05. Aerial application with lower volume rates (30 L ha-1) provided greater deposition of fungicide and greater productivity than the application with 40 L ha-1. The angle of the spray nozzles facing backwards in the plane bar, so as to produce larger droplets, did not influence the application result, and thus, proved to be a viable alternative to reduce drift. Aerial applications with fine and medium droplets provided higher spray deposition on sugarcane leaves and less loss to soil compared to ground applications with extremely coarse droplets. Fungicide application generated increases in productivity of over 20 t ha-1, regardless of application form, reaching 40 t ha-1 with aerial applications. Aerial application provided generally better photosynthetic rates compared to ground application, with better photosynthesis performance and higher concentration of chlorophyll a and b in the leaf blade compared to ground application. No differences were found in gas exchange across the air applications in different operating conditions for volume rates and angles of the spray bar nozzle. / Dissertação (Mestrado)
23

Intoxicações por agroquímicos no Brasil: análise temporal das características epidemiológicas. / Intoxications by agrochemicals in Brazil: temporal analysis of epidemiological characteristics.

QUEIROZ, Paulo Roberto. 04 June 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-06-04T15:19:55Z No. of bitstreams: 1 PAULO ROBERTO QUEIRÓS - DISSERTAÇÃO PPGSA PROFISSIONAL 2016..pdf: 918901 bytes, checksum: 6b56904527605057f88b6008ef2a279f (MD5) / Made available in DSpace on 2018-06-04T15:19:55Z (GMT). No. of bitstreams: 1 PAULO ROBERTO QUEIRÓS - DISSERTAÇÃO PPGSA PROFISSIONAL 2016..pdf: 918901 bytes, checksum: 6b56904527605057f88b6008ef2a279f (MD5) Previous issue date: 2016 / O agronegócio no Brasil tem causado importantes transformações no território, com impactos significativos sobre a saúde humana em função da intensa utilização de agrotóxicos. Dentre estes impactos sobre a saúde humana, um dado preocupante é o aumento da incidência de intoxicação por agrotóxico (agrotóxico e agrotóxico de uso agrícola) em todo o país. O objetivo do estudo é analisar a incidência de intoxicações por agrotóxicos e as características epidemiológicas no Brasil, no período de 2001 a 2014. Trata-se de um estudo ecológico, de séries temporais, bem como descritivo. Os dados foram submetidos a tratamento estatístico através do modelo de regressão polinomial, teste MannWhitney e Teste Kruskal-Wallis, para estas análises, foi adotado um nível de significância de 5%. Utilizou-se também, análise estatística descritiva simples. A análise dos dados foi realizada pelo programa SPSS 20.0®. Foram notificados 80.069 casos de intoxicação por agrotóxico no período de 2001 a 2014, apresentando um crescimento linear exponencial de intoxicação por agrotóxico nesta população, cuja taxa de intoxicação foi de 0.377. No período, as Regiões Sul e Centro-Oeste apresentaram as maiores taxas de intoxicação. Em relação ao comportamento da circunstância da intoxicação, houve relação significativa para a tentativa de suicídio. Quanto à intoxicação por agrotóxico de uso agrícola, foram notificados 25.106 casos no período de 2007 a 2014. Neste período, houve um crescimento linear significativo de intoxicação por agrotóxico de uso agrícola nesta população, cuja taxa de intoxicação foi de 0.1644. No período, houve comportamento heterogêneo entre as taxas de incidência por unidades federativas, todavia, as taxas indicam crescimento por todas as regiões do Brasil. Das dimensões sócio-demográficas, a maioria das intoxicações ocorreram no Brasil em vitimas na faixa etária 20-59 anos (74,7%), sexo masculino (71,0%.), de pele branca (43,8%), zona urbana (54,1%), com apenas o ensino fundamental (42,4%). Para os aspectos relacionados à intoxicação, a maioria das intoxicações por agrotóxicos de uso agrícola no Brasil indicou a circunstância tentativa de suicídio (38,2 %), cura sem sequela (82,3%) e a exposição aguda-única (78,7%). Nesse sentido, o país precisa aprimorar as políticas voltadas a intoxicação por agrotóxico desenvolvendo medidas eficazes para a prevenção e diagnóstico precoce das pessoas intoxicadas. Em longo prazo, cabe desenvolver novos estudos para compreender se as medidas tomadas foram eficazes para reduzir as tendências e percentuais apontadas neste estudo. / Brazilian’s agribusiness has caused important transformation around the country, with significant impacts on human health due to the big use of pesticides. Among these impacts due the human health, the increased toxicity about pesticides (pesticides and agricultural pesticides) in Brazil is concerning. The objective of this study is to analyze the incidence of pesticide poisoning and epidemiological characteristics in Brazil, from 2001 to 2014. This is an ecological study, time series, as described. Data were analyzed statistically by polynomial regression model, Mann-Whitney test and Kruskal-Wallis test. These analyzes it adopted a 5% significance level. Also it was used descriptive statistical analysis simple. For the processing of the data was used SPSS 20.0® program. 80,069 cases of pesticide poisoning were reported in the period 2001-2014, with an exponential linear growth of poisoning by pesticides in this population, whose poisoning rate was 0.377. During the period, the South and the Midwest had the highest intoxication rates. Regarding the behavior of the condition of intoxication, there was a significant relationship to the suicide attempt. As for the pesticide poisoning of farm sweat, 25,106 cases were reported from 2007 to 2014. During this period, there was a significant linear growth of poisoning by pesticides for agricultural use in this population, whose poisoning rate was 0.1644. That moment, there were divergent behavior between the incidence rates for federal units, however, the rates show growth in all regions of Brazil. Sociodemographic dimensions, most poisonings occurred in Brazil in victims aged 20-59 years (74.7%), male (71.0%.), White skin (43.8%), area urban (54.1%), just primary education (42.4%). The analysis of socio-demographic dimensions of Regions indicated most of intoxication of victims of pesticide use in agriculture in the age group 20-59 years old in the Southeast (74.8%), male in the Southeast Region (72.7% ). Brown-skinned individuals were more frequent in the North, Northeast and Midwest while, in the Southeast and South, there was a higher percentage for white skinned individuals, urban exposure zone (55.7%) in the Southeast and elementary school (56.3%) in the South. For aspects related to intoxication, most poisonings from pesticide poisoning in Brazil indicated the circumstance suicide attempt (38.2%), healing without sequelae (82.3%) and acute-single exposure (78.7%). The evaluation of aspects related to poisoning by pesticide use in agriculture by Region indicated the attempted suicide as the most frequent in the Northeast (60.5%), without sequel healing in the South (87.7%) and acute-single in Southeast (76.6%). Therefore, the country needs to improve policies to poisoning by pesticides, developing effective measures for the prevention and early diagnosis of intoxicated people. In the future, it must be developing new studies to understand if the measures taken have been effective in reducing the tendencies and percentages cited in this study.

Page generated in 0.059 seconds