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  • 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.
11

Avaliação de material alternativo para uso como adsorvente na extração em fase sólida de resíduos de pesticidas em estipe de coqueiro (Cocos nucifera L)

Jesus, Jemmyson Romário de 18 February 2014 (has links)
The coconut (Cocos nucifera L) is a rich source of nutrient and as well as other plants is under attack from different types of pests and diseases, causing losses to producers. Pesticide use remains the primary control strategy and combat pests and diseases in agricultural crops. However, the excessive and indiscriminate use of these products can cause serious harm to human health and the environment due to the high toxicity these products. In Brazil, until now no stipulated values of maximum residue limits (MRLs) for pesticides in coconut crops. Similarly, there is little information about the degree of contamination. Therefore analytical methodologies must be developed for the determination of pesticide residues in coconut cultivation, aiming to ensure human health. Thus, this work proposes a methodology to determine residue of bromopropylate, clofentezine, coumaphos, difenoxuron, diniconazole, fenvalerate, flumetralin, flumeturon, teflubenzuron in greens stipe, appling the matrix solid phase dispersion (MSPD) and liquid chromatography with diode array detector (LC-DAD) for analysis. In this study we evaluated the best sorbent/solvent combinations (using silica, Florisil, neutral alumina, C18 and coordination polymers [Zn(BDC)(H2O)2]n, [Zn(BDC)0.99(NH2-BDC)0.01)(H2O)2]n, [Zn(BDC)0.95(NH2-BDC)0.05)(H2O)2]n, [Zn(BDC)0.90(NH2-BDC)0.10)(H2O)2]n/acetonitrile), the best ratio of sample/ adsorbent mass, as volume of the elution solvent used for extraction were evaluated. Among the investigated combinations, the system comprising 0.25 g of stem, 1 g of neutral alumina and 5 mL of acetonitrile was the most efficient in recovery resulting from 70 and 93%, with relative standard between 1.6% and 10%, in the levels of concentration 0.04, 0.08, 0.2, 0.4, 2.0, 3.0; 4.0 ìg g-1. The linearity was above 0.9991 and the limits of detection between 0.01 and 0.05 ìg g-1 and quantification 0.05 and 0.2 ìg g-1. Among the polymeric phases, the [Zn(NH2BDC)0.1(BDC)0.9(H2O)2]n was most eficiente in the extraction of bromopropylate, clofentezine, coumaphos, difenoxuron, diniconazole, fenvalerate, flumetralin, flumeturon and teflubenzuron. / O coqueiro (Cocos nucifera L.) e uma rica fonte de nutrientes e, assim como outras plantas e alvo de ataque de diferentes tipos de pragas e doencas, causando prejuizos aos produtores. O uso de pesticidas continua sendo a principal estrategia de controle e combate de pragas e doencas nas plantacoes agricolas. No entanto, o uso excessivo e indiscriminado desses produtos podem ocasionar serios danos a saude humana e ao ambiente, devido a elevada toxicidade desses produtos. No Brasil, ate o momento, nao ha valores estipulados de limites maximos de residuos (LMR) para pesticidas na cocoicultura. Do mesmo modo, ha pouca informacao quanto ao grau de contaminacao. Portanto metodologias analiticas tem de ser desenvolvidas para determinacao de residuos de pesticidas na cultura de coqueiro, com intuito de assegura essencialmente a saude humana. Nesse sentido, esse trabalho propoe uma metodologia que determine residuo de bromopropilato, clofentezina, cumafos, difenoxurom, diniconazol, fenvalerato, flumetralina, flumeturom, teflubenzurom em estipe de coqueiro, fazendo uso da tecnica de DMFS para extracao e CL-DAD para analise. Nesse estudo foram avaliados as melhores combinacoes sorvente/solvente (utilizando silica gel, Florisil, alumina neutra, C18, e polimeros de coordenacao [Zn(BDC)(H2O)2]n, [Zn(BDC)0,99(NH2-BDC)0,01)(H2O)2]n, [Zn(BDC)0,95(NH2-BDC)0,05)(H2O)2]n, [Zn(BDC)0,90(NH2-BDC)0,10)(H2O)2]n/acetonitrila). Avaliou-se a melhor relacao de massa amostra/adsorvente, alem do volume do solvente de eluicao utilizado para extracao. Dentre as combinacoes avaliadas, o sistema constituido de 0,25 g de estipe, 1 g de alumina neutra e 5 mL de acetonitrila foi o mais eficiente resultando em recuperacao entre 70 e 93% com precisao entre 1,6% e 10% nos niveis de concentracao 0,04, 0,08, 0,2, 0,4, 2,0, 3,0; 4,0 Êg g-1. As linearidades foram acima de 0,9991 e os limites de deteccao foram entre 0,01 e 0,05 Êg g-1 e de quantificacao entre 0,05 e 0,2 Êg g-1. Entre as fases polimericas estudadas, o [Zn(NH2BDC)0,1(BDC)0,9(H2O)2]n foi o mais eficiente na recuperacao de bromopropilato, clofentezina, cumafos, difenoxurom, diniconazol, fenvalerato, flumetralina, flumeturom e teflubenzurom.
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12

Standardized Diagnostic Workup and Patient-Centered Decision Making for Surgery and Neck Dissection Followed by Risk-Factor Adapted Adjuvant Therapy Improve Loco-Regional Control in Local Advanced Oral Squamous Cell Carcinoma

Wichmann, Gunnar, Pavlychenko, Mykola, Willner, Maria, Halama, Dirk, Kuhnt, Thomas, Kluge, Regine, Gradistanac, Tanja, Fest, Sandra, Wald, Theresa, Lethaus, Bernd, Dietz, Andreas, Wiegand, Susanne, Zebralla, Veit 30 March 2023 (has links)
Background: Standardized staging procedures and presentation of oral squamous cell carcinoma (OSCC) patients in multidisciplinary tumor boards (MDTB) before treatment and utilization of elective neck dissection (ND) are expected to improve the outcome, especially in local advanced LAOSCC (UICC stages III–IVB). As standardized diagnostics but also increased heterogeneity in treatment applied so far have not been demonstrated to improve outcome in LAOSCC, a retrospective study was initiated. Methods: As MDTB was introduced into clinical routine in 2007, 316 LAOSCC patients treated during 1991-2017 in our hospital were stratified into cohort 1 treated before (n=104) and cohort 2 since 2007 (n=212). Clinical characteristics, diagnostic procedures and treatment modality of patients were compared using Chi-square tests and outcome analyzed applying Kaplan-Meier plots and log-rank tests as well as Cox proportional hazard regression. Propensity scores (PS) were used to elucidate predictors for impaired distant metastasis-free survival (DMFS) in PS-matched patients. Results: Most patient characteristics and treatment modalities applied showed insignificant alteration. Surgical treatment included significantly more often resection of the primary tumor plus neck dissection, tracheostomy and percutaneous endoscopic gastrostomy tube use. Cisplatin-based chemo-radiotherapy was the most frequent. Only insignificant improved disease- (DFS), progression- (PFS) and event-free (EFS) as well as tumor-specific (TSS) and overall survival (OS) were found after 2006 as local (LC) and locoregional control (LRC) were significantly improved but DMFS significantly impaired. Cox regression applied to PS-matched patients elucidated N3, belonging to cohort 2 and cisplatin-based chemo-radiotherapy as independent predictors for shortened DMFS. The along chemo-radiotherapy increased dexamethasone use in cohort 2 correlates with increased DM. Conclusions: Despite standardized diagnostic procedures, decision-making considering clear indications and improved therapy algorithms leading to improved LC and LRC, shortened DMFS hypothetically linked to increased dexamethasone use had a detrimental effect on TSS and OS.
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