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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

Sistemas adesivos a base de acrilamidas : síntese, caracterização e desenvolvimento / Acrylamides adhesive system : synthesis, characterization and development.

Rodrigues, Stefani Becker January 2016 (has links)
O objetivo deste estudo foi sintetizar e caracterizar monômeros metacrilamidas, desenvolver, caracterizar e avaliar as propriedades de sistemas adesivo convencional de três passos. Foram sintetizadas bis(metacrilamida)s e tris(metacrilamida) e caracterizadas por espectroscopia de Infravermelho por Transformada de Fourier (FTIR), Ressonância Magnética Nuclear (RMN) de 1H e 13C, por Cromatografia Líquida de Alta Eficiência com Espectrometria de Massas (UHPLC-QTOF-MS) e Calorimetria Exploratória Diferencial Modulada (MDSC). Quatro bis(metacrilamidas), (1) N,N’-(propane-1,3-diyl)bis(N-ethyl-2-methylacrylamide), (2) N,N’-(octane-1,8-diyl)bis(2-methylacrylamide), (3) N,N’-(butane-1,4-diyl)bis(2-methacrylamide) e (4) N,N’-(1,4 phenylene)bis(2-methylacrylamide)monômero (1), (2), (3) e (4), e uma tris(metacrilamida) TMA, foram sintetizadas. Pela análise de FTIR-ATR foram observadas as bandas correspondentes ao estiramento do grupo C=O (1660 cm-1), C=C (1610 cm-1), N-H (3300 cm-1) e C-N (1520 cm-1). As análises de RMN identificaram a presença das ligações duplas referentes aos grupos metacrilamidas em deslocamentos químicos entre 5,3 e 5,8 ppm para 1H e entre 120 e 140 ppm para 13C.Os valores de massa exata m/z foram: 267,2068, 281,2222, 225,1595, 245,1283 e 351,2385 g/mol para os monômeros (1), (2), (3), (4) e TMA, respectivamente. A cinética de polimerização do TMA e dos adesivos experimentais contendo 2-hidroxietil acrilamida (HEAA) ou 2-hidroxietil metacrilato (HEMA) com as seguintes formulações foram investigadas por meio de DSC-PCA, n=3: TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%, TMA50%/HEMA50%, BisGMA/HEAA/TMA e BisGMA/HEMA.Características e propriedades mecânicas das resinas adesivas BisGMA/HEAA/TMA e BisGMA/HEMA foram avaliadas por resistência coesiva (UTS, n=5), degradação em solvente (ΔKHN, n=5), ângulo de contato (n=5), microtração (μTBS, n=20) e análise de fratura. Um primer a base de acrilamidas foi desenvolvido (H2O/HEAA/AMPS) (2-acrylamida-2-methilpropano ácido sulfônico) para ser utilizado no grupo experimental com metacrilamidas. Os valores de pH e ângulo de contato do primer experimental foram comparados com o primer do ScotchBond Multi-purpose (grupo controle). O monômero (1) resultou em um monômero amarelo claro de baixa viscosidade, entretanto, não apresentou foto ou termopolimerização. A energia de ativação determinada pelo método de Kissinger foi – 165,8 kJmol-1; -182,7 kJmol-1 e -156,7 kJmol-1 para os monômeros (2), (3) e (4), respectivamente. Sistemas adesivos convencionais de três passos a base de metacrilamidas e a base de metacrilatos foram desenvolvidos. Resinas adesivas contendo somente HEAA e TMA (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%) apresentaram grau de conversão abaixo de 40% após 40 s de fotoativação. Alto grau de conversão (acima de 60%) só foi encontrado para as resinas adesivas BisGMA/HEAA/TMA e BisGMA/HEMA e sem diferença significativa entre elas, p>0,05. Os valores de UTS (BisGMA/HEMA- 67,7 ±5 MPa e BisGMA/HEAA/TMA- 60,5 ±7 MPa), μTBS (BisGMA/HEMA- 57 ± 14 MPa e BisGMA/HEAA/TMA- 53,1 ±15 MPa) e ângulo de contato (BisGMA/HEMA- 39,5 ±9 e BisGMA/HEAA/TMA- 46,7 ±15) não apresentaram diferença estatística, p>0.05. O primer experimental apresentou um valor pH mais baixo (2,7) bem como de ângulo de contato (18,5 ±5) em relação ao comercial (pH-4 e θ-33,5 ±4). A síntese proposta para os monômeros (1), (2), (3), (4) e TMA foi caracterizada nesse trabalho. Um primer somente com acrilamidas foi desenvolvido e a presença do novo monômero TMA na resina adesiva BisGMA/HEAA permitiu a formulação de um sistema adesivo convencional de três passos sem a presença do monômero HEMA. / The aim of this study was synthesized and characterizes methacrylamides monomers, development, characterizer and evaluated the properties of 3-step etch-and-rise adhesive system. Bis(methacrylamide)s and tris(methacrylamide) were synthesized. The monomer structures were confirmed by 1H and 13C Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR-ATR), Ultra-high liquid chromatography quadrupole time of flight mass spectrometry (UHPLC-QTOF-MS) and modulated differential scanning calorimetry (mDSC). Four bis(methacrylamide)s monomers (1) N,N’-(propane-1,3-diyl)bis(N-ethyl-2-methylacrylamide), (2) N,N’-(octane-1,8-diyl)bis(2-methylacrylamide), (3) N,N’-(butane-1,4-diyl)bis(2-methacrylamide) and (4) N,N’-(1,4 phenylene)bis(2-methylacrylamide) and one tris(methacrylamide), TMA, were synthesized. All IR spectra of the monomers showed the C=C axial deformation at 1610 cm-1. The 1H NMR spectra the olefinic hydrogens were observed at 5.3 an 5.8 ppm and in the 13C NMR, the vinylic carbons at 120 and 140 ppm. The exact m/z values were: 267.2068, 281.2222, 225.1595, 245.1283 and 351.2385 g/mol for monomers (1), (2), (3), (4) and TMA respectively. Monomer (1) not presented photo (DSC-PCA) or thermal polymerization. The activation energy determined using Kissinger methodology was: - 165.8 kJmol-1; -182.7 kJmol-1 and -156.7 kJmol-1 for monomers (2), (3) and (4), respectively. 3-step adhesive systems with methacrylamides and methcrylates were development. Kinetics of photopolymerization of TMA and experimental adhesive resin containing 2-hydroxyethylacrylamide (HEAA) or 2-hydroxyethylmethacrylate (HEMA) in the following formulations: (TMA 33%/HEAA 66%, TMA 50%/HEAA 50%, TMA66%/HEAA33%, TMA50%/HEMA50%, BisGMA66%/HEAA24%/TMA10% and BisGMA66%/HEMA33%) were investigated through DSC-PCA. Characteristics and mechanical properties for BisGMA 66%/HEAA 24%/TMA 10% and BisGMA 66%/HEMA 33% adhesives were evaluated with ultimate tensile strength (UTS, n=5), softening in solvent (ΔKHN, n=5), contact angle (n=5), microtensile bond strength (μTBS, n=20) and failure analysis. A primer was also formulated with H2O/HEAA/AMPS (2-acrylamido-2-methylpropane sulfonic acid) and the pH and contact angle value were verified and compared to commercial ScotchBond primer. Adhesive resin with HEAA and TMA (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%) showed lower conversion and polymerization rate after 40 s of light activation. Higher conversion (up to 60%) was found for BisGMA/HEAA/TMA and BisGMA/HEMA adhesive resin without significant difference between adhesive resin, p>0.05. UTS (BisGMA/HEMA- 67.7 ±5 MPa e BisGMA/HEAA/TMA- 60.5 ±7 MPa), immediate μTBS (BisGMA/HEMA- 57 ± 14 MPa e BisGMA/HEAA/TMA- 53.1 ±15 MPa), ΔKHN (BisGMA/HEMA- 56 ± 7 e BisGMA/HEAA/TMA- 64 ±4) and contact angle (BisGMA/HEMA- 39.5 ±9 e BisGMA/HEAA/TMA- 46.7 ±15) showed no statistical difference, p>0.05. The experimental primer presented more acidity pH (2.7) and lower contact angle (18.5 ±5) when compared to commercial primer (pH- 4 e θ- 33.5 ±4). A new acrylamide based-primer was formulated and the presence of the new tris(methacrylamide) monomer (TMA) was enable the preparation of a 3-step etch-and-rise adhesive system without HEMA monomer.
12

Chimie des acrylamides chiraux : nouvelles méthodologies et application à la synthèse de nouvelles architectures moléculaires / Chemistry of chiral acrylamides : new methodologies and application to the synthesisof new molecular architectures

Gratais, Alexandre 03 October 2014 (has links)
Les réactions permettant la création de liaisons carbone-carbone sont des outils essentiels dans le domaine de la synthèse organique. Elles permettent d'accéder à des structures de plus en plus complexes. Cependant le contrôle de ces réactions en utilisant des partenaires hautement fonctionnalisés reste un enjeu majeur.Le développement de nouvelles méthodologies de synthèse basées sur la réactivité des acrylamides chiraux dérivés d'acides aminés est étudié dans ces travaux. Une nouvelle version de la réaction d'alkylation de pyrroles de type Friedel-Crafts a été développée en utilisant le caractère électrophile d'acrylamides chiraux hautement fonctionnalisés. Le pyrrole peut être monoalkylé ou dialkylé de façon sélective conduisant à de nouvelles structures hétérocycliques portant des enchaînements peptidiques pouvant contenir jusqu'à quatre résidus d'acides aminés. Les acrylamides chiraux portant un motif allyltriméthylsilane conjugué ont été utilisés comme nouveaux réactifs permettant des réactions d'allylation hautement diastéréosélectives et chimiospécifiques vis-à-vis d'aldéhydes. L'extension de cette méthodologie aux aldéhydes α- aminés a été réalisée et permet un accès aisé à des structures analogues des acides γ-aminés. / Reactions allowing carbon-carbon bond creation are essential tools in the field of organic synthesis. These reactions are used to access to more and more complex structures. However their control in the case of highly functionnalized partners is still a serious concern.Development of new methodologies based on the reactivity of aminoacid derivating chiral acrylamides is reported. A new version of pyrrole alkylation reaction was developed using the electrophilic behaviour of highly functionnalized chiral acrylamides. Pyrrole can be selectivly monoalkylated or dialkylated leading to new heterocyclic structures bearing peptidic sequences containing up to four aminoacids residues. Chiral acrylamides bearing a conjuguated allyltrimethylsilane moiety have been used as new reagent in highly diastereoselective and chemospecific towards aldehydes allylation reactions. This methodology was extended to α-aminoaldehydes allowing easy access to γ-aminoacidsanalogues.
13

Synthesis of <sup>11</sup>C-labelled Alkyl Iodides : Using Non-thermal Plasma and Palladium-mediated Carbonylation Methods

Eriksson, Jonas January 2006 (has links)
<p>Compounds labelled with <sup>11</sup>C (<i>β</i><sup>+</sup>, t<sub>1/2</sub> = 20.4 min) are used in positron emission tomography (PET), which is a quantitative non-invasive molecular imaging technique. It utilizes computerized reconstruction methods to produce time-resolved images of the radioactivity distribution in living subjects. </p><p>The feasibility of preparing [<sup>11</sup>C]methyl iodide from [<sup>11</sup>C]methane and iodine via a single pass through a non-thermal plasma reactor was explored. [<sup>11</sup>C]Methyl iodide with a specific radioactivity of 412 ± 32 GBq/µmol was obtained in 13 ± 3% decay-corrected radiochemical yield within 6 min via catalytic hydrogenation of [<sup>11</sup>C]carbon dioxide (24 GBq) and subsequent iodination, induced by electron impact. </p><p>Labelled ethyl-, propyl- and butyl iodide was synthesized, within 15 min, via palladium-mediated carbonylation using [<sup>11</sup>C]carbon monoxide. The carbonylation products, labelled carboxylic acids, esters and aldehydes, were reduced to their corresponding alcohols and converted to alkyl iodides. [1-<sup>11</sup>C]Ethyl iodide was obtained via palladium-mediated carbonylation of methyl iodide with a decay-corrected radiochemical yield of 55 ± 5%. [1-<sup>11</sup>C]Propyl iodide and [1-<sup>11</sup>C]butyl iodide were synthesized via the hydroformylation of ethene and propene with decay-corrected radiochemical yields of 58 ± 4% and 34 ± 2%, respectively. [1-<sup>11</sup>C]Ethyl iodide was obtained with a specific radioactivity of 84 GBq/mmol from 10 GBq of [<sup>11</sup>C]carbon monoxide. [1-<sup>11</sup>C]Propyl iodide was synthesized with a specific radioactivity of 270 GBq/mmol from 12 GBq and [1-<sup>11</sup>C]butyl iodide with 146 GBq/mmol from 8 GBq. </p><p>Palladium-mediated hydroxycarbonylation of acetylene was used in the synthesis of [1-<sup>11</sup>C]acrylic acid. The labelled carboxylic acid was converted to its acid chloride and subsequently treated with amine to yield <i>N-</i>[<i>carbonyl</i>-<sup>11</sup>C]benzylacrylamide. In an alternative method, [<i>carbonyl</i>-<sup>11</sup>C]acrylamides were synthesized in decay-corrected radiochemical yields up to 81% via palladium-mediated carbonylative cross-coupling of vinyl halides and amines. Starting from 10 ± 0.5 GBq of [<sup>11</sup>C]carbon monoxide, <i>N-</i>[<i>carbonyl</i>-<sup>11</sup>C]benzylacrylamide was obtained in 4 min with a specific radioactivity of 330 ± 4 GBq/µmol. </p>
14

Synthesis of 11C-labelled Alkyl Iodides : Using Non-thermal Plasma and Palladium-mediated Carbonylation Methods

Eriksson, Jonas January 2006 (has links)
Compounds labelled with 11C (β+, t1/2 = 20.4 min) are used in positron emission tomography (PET), which is a quantitative non-invasive molecular imaging technique. It utilizes computerized reconstruction methods to produce time-resolved images of the radioactivity distribution in living subjects. The feasibility of preparing [11C]methyl iodide from [11C]methane and iodine via a single pass through a non-thermal plasma reactor was explored. [11C]Methyl iodide with a specific radioactivity of 412 ± 32 GBq/µmol was obtained in 13 ± 3% decay-corrected radiochemical yield within 6 min via catalytic hydrogenation of [11C]carbon dioxide (24 GBq) and subsequent iodination, induced by electron impact. Labelled ethyl-, propyl- and butyl iodide was synthesized, within 15 min, via palladium-mediated carbonylation using [11C]carbon monoxide. The carbonylation products, labelled carboxylic acids, esters and aldehydes, were reduced to their corresponding alcohols and converted to alkyl iodides. [1-11C]Ethyl iodide was obtained via palladium-mediated carbonylation of methyl iodide with a decay-corrected radiochemical yield of 55 ± 5%. [1-11C]Propyl iodide and [1-11C]butyl iodide were synthesized via the hydroformylation of ethene and propene with decay-corrected radiochemical yields of 58 ± 4% and 34 ± 2%, respectively. [1-11C]Ethyl iodide was obtained with a specific radioactivity of 84 GBq/mmol from 10 GBq of [11C]carbon monoxide. [1-11C]Propyl iodide was synthesized with a specific radioactivity of 270 GBq/mmol from 12 GBq and [1-11C]butyl iodide with 146 GBq/mmol from 8 GBq. Palladium-mediated hydroxycarbonylation of acetylene was used in the synthesis of [1-11C]acrylic acid. The labelled carboxylic acid was converted to its acid chloride and subsequently treated with amine to yield N-[carbonyl-11C]benzylacrylamide. In an alternative method, [carbonyl-11C]acrylamides were synthesized in decay-corrected radiochemical yields up to 81% via palladium-mediated carbonylative cross-coupling of vinyl halides and amines. Starting from 10 ± 0.5 GBq of [11C]carbon monoxide, N-[carbonyl-11C]benzylacrylamide was obtained in 4 min with a specific radioactivity of 330 ± 4 GBq/µmol.
15

Hybrid hydrogels as model nanocomposites : reinforcement mechanisms by analogy with filled rubbers / Hydrogels hybrides en tant que nanocomposites modèles : mécanismes de renforcement par analogie avec les élastomères chargés

Le Gulluche, Anne-Charlotte 25 July 2019 (has links)
Les hydrogels sont des matériaux intrinsèquement mous, fragiles et élastiques, majoritairement composes d'eau. Leur capacité unique à interagir avec leur environnement se traduit par une grande variation de leur volume initial et en font l'objet d'applications variées dans de nombreux domaines tels que le secteur biomédical, l'industrie agro-alimentaire et cosmétique. Plus récemment, des hydrogels ont été développés pour des secteurs de pointe comme la robotique ou l'ingénierie tissulaire, permettant d'élargir le spectre d'utilisation de la matière molle en tant que matériau structurel. De ce fait, la conception d'hydrogels mécaniquement performants représente un enjeu majeur au développement futur de ces applications.L'élaboration de matériaux nanocomposites incorporant des nanocharges à un réseau organique réticule de façon covalente s'est avérée une stratégie de renfort efficace. Le renforcement dépend alors des interactions existantes entre le polymère et les charges ainsi que de l'état de dispersion des nanoparticules au sein du réseau. Des hydrogels hybrides, à base de poly(N-alkylacrylamides) et de nanoparticules de silice ont ainsi été mis au point, démontrant une amélioration significative des propriétés mécaniques (déformation à la rupture, capacités d'autoréparation). Ce phénomène est attribué à l'adsorption réversible du polymère à la surface des nanoparticules. Si les propriétés viscoélastiques de ces composés ont été largement étudiées, peu de travaux ont été effectués sur la caractérisation et la quantification des interactions à l'interface solide/liquide. De même, le comportement au delà du domaine linéaire ne reste que peu étudié à ce jour. La première partie de ces travaux a été dédiée à la synthèse de chaines linéaires de poly- (acrylamide) (PAAm) et poly(N,N-dimethylacrylamide) (PDMA) ainsi qu'à l'étude de leurs capacités d'adsorption sur la silice tout en contrôlant la chimie de surface des nanoparticules. Cela a permis de mettre en évidence le peu d'affinité du PAAm envers la surface de silice, justifiant ainsi son emploi en tant que monomère « inerte ». En second lieu, il s'est agi de moduler les interactions entre le polymère et la silice au sein des hydrogels hybrides en substituant le polymère interagissant avec l'adsorbat (PDMA) par un polymère peu apte à s'adsorber sur la silice (PAAm). La structure de ces composés ainsi que leur comportement mécanique ont été explorés avec un intérêt marqué pour le domaine non linéaire. Le rôle de l'adsorption dans le renfort mécanique a ainsi été confirmé et plus précisément l'importance des groupements silanols à la surface de la silice. La contribution de l'état d'agrégation des nanoparticules sur la structure et les propriétés mécaniques ont ensuite été étudiés. Le comportement non-linéaire aux grandes déformations des hydrogels synthétisés a notamment été investigué par des expériences de rhéologie aux grandes amplitude de cisaillement (LAOS), permettant une caractérisation plus poussée des mécanismes de renfort, par analogie avec les élastomères chargés / Hydrogels are soft and elastic solid materials mainly composed of water. Owing to their ability to interact with their environment through drastic volume change, hydrogels already find a wide range of applications, as superabsorbants, in pharmaceutics as drug delivery systems and more recently, as sensors and actuators, widening even more the possible use of soft materials as structural or load-bearing materials. Hence, providing gels with high mechanical performances is of major importance to meet these demanding applications. Efficient toughening can be achieved by combining inorganic and organic materials linked by physical and/or chemical interactions. In such nanocomposite materials, the reinforcement depends on the interactions between the polymer and the filler and of the dispersion state of the fillers, allowing to reach the full extent of reinforcement. Hybrid hydrogels based on poly(N-alkylacrylamide) and nanosilica demonstrating great mechanical reinforcement at large strain as well as self-healing capabilities were designed by Hourdet and Marcellan . The drastic improvement of the mechanical behavior is attributed to the reversible adsorption of the polymer onto silica surface. Viscoelastic properties of such hybrids gels have been extensively studied but few studies were carried out to understand and quantify the interactions at the solid/liquid interface. Likewise, the behavior beyond viscoelastic regime of such materials remains scarcely investigated. A first part of this study focused on the synthesis and the adsorption behavior of linear polymer chains of polyacrylamides, more precisely poly(acrylamide) (PAAm), poly(N,N-dimethylacrylamide) (PDMA) onto silica nanoparticles with controlled surface chemistry. It evidenced the non-interacting behavior of PAAm towards silica surface, justifying its choice as a non-interacting polymer. A second part dealt with the modulation of particle/polymer interactions in hybrid gels either by substituting the interacting monomer (DMA) with a non-interacting one (AAm) or by tuning the surface chemistry of the nanoparticles. Then, the study of their structure and mechanical properties was conducted with a special focus on the non-linear behavior. The role of polymer adsorption for gel reinforcement was evidenced and more specifically the importance of the silanol groups at the silica surface for PDMA/silica interactions. The contribution of the dispersion state of silica on the structure and the mechanical response of hydrogels was then addressed and the non-linear domain of the resulting hydrogels was investigated using Large Amplitude Oscillatory Shear experiments. The impact of the chosen monomer and of the dispersion state of the fillers was investigated at large strain, allowing a more precise analysis of the reinforcement mechanisms, by analogy with filled elastomers
16

Efekat akutnog izlaganja peroralno unetog akrilamida na histološke strukture želuca pacova soja Wistar / The effect of acute exposure to orally ingested acrylamide on histological structure of stomach in Wistar rats

Ilić Sabo Jelena 04 July 2016 (has links)
<p>Akrilamid je toksična hemijska supstanca koja ima vrlo &scaron;iroku primenu u hemijskoj industriji, a 2002. godine otkriveno je njegovo prisustvo u namirnicima bogatim skrobom koje se pripremaju na visokim temperaturama. U poslednjh desetak godina primećen je veliki porast gastrointestinalnih tegoba u ljudskoj populaciji. Cilj istraživanja bio je ispitati patohistolo&scaron;ke promene u tkivu želuca pacova soja Wistar izazvanih peroralnim aplikovanjem akrilamida i na taj način povući paralelu sa mogućim gastrointestinalnim tegobama nastalim kao posledica konzumiranja hrane bogate akrilamidom. U istraživanju je ispitivano 6 grupa od po 5 eksperimentalnih životinja (pacovi soja Wistar). Dve kontrolne grupe kojima je peroralno aplikovana destilovana voda i koje su žrtvovane posle 24h i 72h; dve eksperimentalne kojima je peroralno aplikovan akrilamid u dnevnoj dozi od 25 mg/kg i koje su žrtvovane posle 24h i 72h; dve eksperimentalne grupe kojima je peroralno aplikovan akrilamid u dnevnoj dozi od 50 mg/kg i koje su žrtvovane posle 24h i 72h. Na histolo&scaron;kom materijalu tkiva želuca primenjena je kvalitativna histolo&scaron;ka analiza pod svetlosnim mikroskopom, semikvantitativna procena tipa mucina u epitelnim ćelijama sluznice želuca, prisustvo limfocita i granulocita u sluznici želuca, stereolo&scaron;ka merenja pojedinih kompartmana zida želuca, linearna merenja broja i veličine ganglijskih ćelija u Maissner-ovom i Auerbach-ovom nervnom pleksusu, kao i broj mastocita u lamini propriji sluznice i podsluznici želuca. Dobijene vrednosti merenih parametara su potom statistički obrađene. Nastale promene na tkivu želuca pacova soja Wistar se ogledaju u vidu blagog direktnog o&scaron;tećenja povr&scaron;nog epitela sa propratnom blagom inflamatornom reakcijom i blagom degranulacijom mastocita. U Maissner-ovom i Auerbach-ovom nervnom pleksusu su smanjene volumenske gustine nervnih vlakana i ganglijskih ćelija, kao i broj i veličina ganglijskih ćelija. Direktno toksično delovanje na epitel dovodi do posledične obnove epitela, te je potvrđeno prisustvo nezrelijih oblika mukoproduktivnih ćelija koje sadrže kisele, AB pozitivne mucine. Ispitani inflamatorni i degenerativni parametri pokazuju pozitivnu korelaciju u odnosu na dozu i/ili dužinu ekspozicije akrilamidu. Primena akrilamida peroralno pokazala je da postoje patohistolo&scaron;ke promene na tkivu želuca u vidu direktnog toksičnog o&scaron;tećenja epitela, inflamatorne reakcije i o&scaron;tećenja nervnih pleksusa. Poznavanjem mehanizma delovanja ove toksične materije moguće je primeniti adekvatnu prevenciju u ishrani i izvr&scaron;iti odgovarajući izbor terapijskih metoda.</p> / <p>Acrylamide is a toxic chemical substance with wide implementation in chemical industry. In 2002 it was discovered the presence of acrylamide in foods rich in starch which are prepared at high temperatures. In the last ten years there is a large increase in gastrointestinal illnesses in human population. The aim of this study was to investigate the histopathological changes in the gastric tissue in Wistar rats induced with injection of oral acrylamide and thus draw a parallel with possible gastrointestinal problems arising as a result of the consumption of foods rich in acrylamide. The research was carried out 6 groups of 5 experimental animals (Wistar rats). Two control groups that are orally concomitant application of distilled water and which were sacrificed after 24h and 72h; two experimental groups which are orally administrated acrylamide in a daily dose of 25 mg / kg and that were sacrificed after 24h and 72h; two experimental groups which were orally administrated acrylamide in a daily dose of 50 mg / kg and that were sacrificed after 24h and 72h. On histological gastric tissue material is applied qualitative histological analysis by light microscopy, semi-quantitative assessment of the type of mucin in epithelial cells of the stomach lining, the presence of lymphocytes and granulocytes in gastric mucosa, stereological measurements of individual compartments of the stomach wall, linear measuring the number and size of ganglion cells in the Maissner and Auerbach&#39;s nerve plexus, and the number of mast cells in the lamina propria of the mucosa and in the submucosis of the stomach. Obtained values of measured parameters were statistically processed. Histological changes in the stomach tissue of Wistar rats are seen as a direct slight damage of the surface epithelium, with accompanynig mild inflammatory reaction and the degranulation of mast cells. The Meissner&#39;s and Auerbach&#39;s nerve plexus decreased volume density of nerve fibers and ganglion cells, as well as the number and size of the ganglion cells. Directly toxic effect on epithelium leads to the result of the reconstruction of the epithelium, which is confirmed by the presence of immature form of mucoproductive cells which contain acid, AB positive mucins. Examined inflammatory and degenerative parameters show a positive correlation with respect to dose and / or a time of exposition to acrylamide. Acrylamide oral application revealed that there are histologic changes in the stomach tissue in the form of a direct toxic damage to the epithelium, inflammatory reaction and damage to the nerve plexus. Knowing the mechanism of action of these toxic substances allows to apply adequate prevention in nutrition and make an appropriate choice of therapeutic methods.</p>
17

Síntese de 3-alcoxiacrilamidas a partir de tricloroacetil enol éteres / Synthesis of 3-alkoxy acrylamides from trichloroacetil enol ethers

Mello, Débora Lombe de 24 February 2012 (has links)
This work reports a effective method for the preparation of a series of the new 3-alkoxy acrylamides of general formula R3HNC(O)CR1=CR2(OR), where R/ R1/ R2 = Et/H/H, Me/H/Me, -(CH2)2-/H, -(CH2)3-/H; R3 = Allyl, n-Pr, Bn, Phenetyl. However, the 3-alkoxy acrylamides where R/ R1/ R2 = Et/H/H/, Me/H/Me, R3 = Bn, have already been described in the literature. The 3-alkoxy acrylamides were obtained through three reaction steps. The first step, β-alkoxyvinyl trichloroacetyl ketones were synthesized through the acylation of enolethers using trichloroacetyl chloride as the acylating agent. In the second step, β-alkoxyvinyl trichloroacetyl ketones were converted to the corresponding β-alkoxyvinyl carboxylic acids from a basic hydrolysis using a 1 M sodium hydroxide solution. In the third step, β-alkoxyvinyl carboxylic acids were treated with thionyl chloride, using toluene as solvent, leading to the corresponding acyl chlorides intermediaries, which were not isolated. The acyl chlorides were reacted with primary amines such as allylamine, propylamine, benzylamine, and phenethylamine under basic catalysis of triethylamine, furnishing a new series of 3-alkoxy acrylamides in good yields of 48-90%. The 3-alkoxy acrylamides obtained in this study were identified by 1H and 13C Nuclear Magnetic Resonance spectroscopy, Mass spectroscopy and Elemental analysis. Keywords: 3-alkoxy acrylamides, β-alkoxyvinyl carboxylic acids, β-alkoxyvinyl trichloroacetyl ketones, acyl chlorides, amines / Este trabalho apresenta um método eficiente para preparação de uma série inédita de 3-alcoxiacrilamidas de fórmula geral R3HNC(O)CR1=CR2(OR), onde R/ R1/R2 = Et/H/H, Me/H/Me, -(CH2)2-/H, -(CH2)3-/H; R3 = Alil, n-Pr, Bn, Fenetil. Sendo que as 3-alcoxiacrilamidas onde R/ R1/ R2 = Et/H/H, Me/H/Me, R3 = Bn, já foram descritas anteriormente na literatura. As 3-alcoxiacrilamidas foram obtidas através de três etapas reacionais, sendo que a primeira etapa constitui-se da acilação dos enol éteres, utilizando cloreto de tricloroacetila como agente acilante. Na segunda etapa as β-alcoxivinil tricloroacetil cetonas sintetizadas anteriormente, foram convertidas aos respectivos ácidos β-alcoxivinil carboxílicos a partir da hidrólise básica (utilizando solução de NaOH 1 M). Na terceira etapa, os ácidos β-alcoxivinil carboxílicos foram submetidos à reação com cloreto de tionila, utilizando tolueno como solvente, formando como intermediários os cloretos ácidos, os quais não foram isolados. Posteriormente, esses cloretos ácidos foram submetidos á reação de substituição nucleofílica, utilizando diferentes aminas alquílicas primárias (alilamina, propilamina, benzilamina, fenetilamina) como nucleófilo, sob catálise básica de trietilamina, promovendo assim, a síntese da série inédita das 3-alcoxiacrilamidas com bons rendimentos de 48-90%. As 3-alcoxiacrilamidas obtidas neste trabalho foram identificadas através de técnicas de Ressonância Magnética Nuclear de Hidrogênio, Ressonância Magnética Nuclear de Carbono-13, Espectrometria de Massas e Análise elementar.

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