Free Radical Reactions
Mostrando 1-12 de 52 artigos, teses e dissertações.
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1. Synthesis and characterization of isoprene oligomers to compare different production chemical processes
Abstract Three methods to obtain isoprene oligomers were evaluated: chemical degradation of non-vulcanized coagulated natural rubber; chemical degradation of natural rubber latex; and oligomerization of the isoprene monomer. The products were characterized by infrared spectrometry (FTIR), nuclear magnetic resonance (NMR) and size-exclusion chromatography (S
Polímeros. Publicado em: 18/03/2019
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2. New copolymer of acrylamide with allyl methacrylate and its capacity for the removal of azo dyes
The copolymerization reactions of Acrylamide (AA) with the different mole ratios of allyl methacrylate (AMA) such as 25/75, 50/50 and 75/25 were studied by radical polymerization under argon atmosphere using 2,2’-Azobis (isobutyronitri1e) (AIBN) as initiator. The copolymers were characterized with Fourier transform infrared spectroscopy (FTIR) and thermogr
Polímeros. Publicado em: 2015-04
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3. Caracterização de espécies paramagnéticas em sementes por ressonância paramagnética eletrônica
Paramagnetic species were characterized in the seeds of radish wild, rice, mustard, wheat, oats, sorghum, sunflower, soybean, cotton, beans, maize and barley by EPR (Electron Paramagnetic Resonance). Some paramagnetic species present in the soil were also investigated, such as goethite, hematite, magnetite, and ferrihydrite. EPR experiments were performed at
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 01/03/2012
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4. Síntese e caracterização de padrão de poliestireno para cromatografia de permeação em gel através da polimerização via radical livre controlada mediada por radicais nitróxidos / Synthesis and characterization of polystyrene standard for gel permeation chromatography using nitroxide mediated radical polymerization (NMRP)
A Cromatografia de Permeação em Gel ou "Gel Permeation Chromatography (GPC), também conhecida como Cromatografia de Exclusão por Tamanho ou "Size Exclusion Chromatography" (SEC) é uma das técnicas analíticas mais utilizadas para separação e caracterização de polímeros naturais e sintéticos, copolímeros e proteínas, fornecendo informações dis
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 08/08/2011
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5. Identification, quantification and antioxidant characterization of flavonoids and vitamin C in fruit jellies / Identificação, quantificação e caracterização antioxidante de flavonoides e vitamina C presentes em geleias de frutas
The aims of this study were improving and validate methods to analyze ascorbic acid and flavonoids in fruit jellies. The identification and quantification of ascorbic acid occurred in three ways: (1) a colorimetric method, using the 2,6-dichlorophenolindophenol, (2) a method using the High Performance Liquid Chromatography and, (3) a method by Capillary Elec
Publicado em: 2010
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6. Immediate radical fang mark ablation may allow treatment of japanese viper bite without antivenom
Administration of antivenom is currently the standard treatment for snake envenomation. However, it can sometimes cause anaphylactic reactions including urticaria, bronchospasm and hypotension. Furthermore, it may also provoke life-threatening complications, even though the mortality rate is less than 1%. In this study, we present a new treatment - immediate
Journal of Venomous Animals and Toxins including Tropical Diseases. Publicado em: 2009
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7. Mecanistic Studies of Reactions involving Tellurium Compounds and Synthetic Application of Chalcogenide Compounds / Estudo de mecanismos de reações envolvendo compostos de telúrio e aplicações sintéticas de compostos calcogenados
The first experimental evidence for the formation of an organic tellurium-centered radical (RTe center dot, R = Ph or nBu groups) during the hydrotelluration of alkenes and alkynes is provided. The radicals were detected by electronic paramagnetic ressonance (EPR), using DBNBS (3,5-dibromo-4-nitrosobenzene-sulfonate) as the spin trap. The radical adducts (DB
Publicado em: 2009
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8. Suplementação com vitaminas, um fator complicador ou benéfico para portadores ou não de Alzheimer durante o processo de envelhecimento?
Aging is an experience every human being shares, but not always understands. The nature of aging process has been target for numerous speculations. Suggested possibilities include: change in the DNA code, reduction of protein synthesis, macromolecules links, auto-attack to immune system and damage caused by oxidative reactions. Evidences accumulated indicate
Publicado em: 2009
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9. Simulation of styrene polymerization reactors: kinetic and thermodynamic modeling
A mathematical model for the free radical polymerization of styrene is developed to predict the steady-state and dynamic behavior of a continuous process. Special emphasis is given for the kinetic and thermodynamic models, where the most sensitive parameters were estimated using data from an industrial plant. The thermodynamic model is based on a cubic equat
Brazilian Journal of Chemical Engineering. Publicado em: 2008-06
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10. Homopolimerização e copolimerização via radical livre controlada por radicais nitroxidos / Nitroxide mediated radical homopolymerization and copolymerization
Controlled/living radical polymerization (CLRP) is one of the most rapidly developing areas of polymer science and engineering. The ability to prepare well-defined block and graft copolymers, gradient and periodic copolymers, stars, combs, polymer networks, end-functional polymers and many other materials by free-radical mechanisms is perhaps the main reason
Publicado em: 2008
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11. Reduction of molecular oxygen in aqueous solutions through modifying electrodesmethodology / Redução de oxigênio molecular em soluções aquosas através da metodologia de modificação de eletrodos
This work consisted in testing the viability of investigations into the electrochemical generation and identification of free radicals involved in advanced oxidative processes. In these studies, a technique which is rarely used for the electrochemical generation and identification of free radicals at organothiole-modified electrodes, electrochemical impedanc
Publicado em: 2007
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12. Desenvolvimento de um modelo matematico mais rigoroso para polimerização radicalar controlada mediada por radicais nitroxido de estireno / Development of more detailed mathematics model for nitroxide mediated living free radical polymerization (NMRP)
Living Free-Radical Polymerization (LFRP) has been target of much attention in the last years, because it allows getting polymers with a highly controlled microstructure, with narrow distribution of the average molecular weights and polydispersity (PDI) close to unit, and with complex molecular structures (e.g. pure block copolymers), with different architec
Publicado em: 2007