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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.
61

ANÁLISE ECOTOXICOLÓGICA DA ACRILAMIDA UTILIZANDO UMA MICROALGA COMO ORGANISMO INDICADOR / ECOTOXICOLOGICAL ANALYSIS OF ACRYLAMIDE USING MICROALGAE AS INDICATOR ORGANISM

Nunes, Bárbara Werle 29 October 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Acrylamide is a water soluble monomer with a multitude of industrial and chemical applications. In polymeric form, which is also known as polyacrylamide, it may be used as a flocculant for water treatment. However, this monomer presents carcinogenic risk and it can cause changes in the endocrine system of living beings, it is also called endocrine disrupter. On the Ordinance of the Ministry of Health 2914/2011, it was established a maximum limit of 0.5 micrograms/L acrylamide for drinking water. However, there is no evidence in the literature on the detection of acrylamide in the drinking water. Thus, the study of the behavior of acrylamide as an environmental contaminant and carcinogen is of a great value to the public health. Thus, the main objective of this study was the analysis of the expected changes toxicology of acrylamide in different concentrations, using green algae as indicator organisms. The study was conducted through the following steps: (I) The structure of a study methodology, based on the references that are available and adapted for a consistent routine of work with the good laboratory conditions of the institution; (II) the performance of the ecotoxicological tests with algae, which are treated with polyacrylamide solution used in the municipality of Santa Maria Water Treatment Station - RS; (III) the performance of ecotoxicological tests with algae, treated with different concentrations of acrylamide; (Iv) the calculation of the sample cell biovolume (V) the analysis of chlorophyll "a" and (VI)the statistical analysis of the results and interpretation of the data of the research. The experiments were performed in the laboratory of sanitation- Lasam, from the Federal University of Santa Maria - UFSM from February to August 2014. The results demonstrated that it was possible to develop the ecotoxicological study with polyacrylamide, because it is a commercial substance that has no analytical purity, which led to no regular results, making it impossible to reproduce the tests. However, in the ecotoxicological analysis of acrylamide, the acrylamide results indicated that significantly inhibited the growth of algae, yielding 5.88 mg/L-1 as the concentration which inhibited 50% of the growth of the algal cells. Both the microscopic cell counting as the dosage of chlorophyll "a" was effective in the experimental biomass quantification. The most important outcome of the work consist in assessing changes in cell biovolume and phenotypic plasticity of the species D. quadricauda unprecedentedly parameters evaluated for exposure to acrylamide. The use of calculation of biovolume combined with cell counts proved quite useful for analyzing the results, showing the variation in cell size during the experiment. Phenotypic plasticity of gender has changed with exposure to acrylamide, which gives an important finding in the evaluation of toxicity. / A acrilamida é um monômero solúvel em água com uma infinidade de aplicações químicas e industriais. Na forma polimérica, também denominada de poliacrilamida, pode ser utilizada como floculante para o tratamento de água. Entretanto, esse monômero apresenta risco carcinogênico e causa alterações no sistema endócrino dos seres vivos, também denominado de desregulador endócrino. A Portaria do Ministério da Saúde 2914/2011 estabelece um limite máximo de 0,5 micrograma/L de acrilamida para água potável. Contudo, não há evidências na literatura sobre a detecção da acrilamida nas águas para consumo humano. Assim, o estudo do comportamento da acrilamida como um contaminante ambiental é de grande valia para a saúde pública. Desta forma, o objetivo principal deste estudo consistiu na análise das alterações toxicológicas esperadas da acrilamida, em distintas concentrações utilizando uma clorofícea como organismo indicador. O estudo foi realizado mediante as seguintes etapas: (I) Estruturação de uma metodologia de estudo, baseada nas referências bibliográficas disponíveis e adaptada para uma rotina de trabalho condizente com as condições laboratoriais da instituição; (II) Realização de ensaios ecotoxicológicos com algas, tratadas com solução de poliacrilamida utilizada na Estação de Tratamento de Água do município de Santa Maria RS; (III) Realização de ensaios ecotoxicológicos com algas, tratadas com distintas concentrações de acrilamida; (IV) Cálculo do biovolume celular das amostras; (V) Análise da concentração de clorofila a ; (VI) Análise da Plasticidade Fenotípica, (VII) Análise estatística dos resultados obtidos e interpretação dos dados. Os experimentos foram realizados no laboratório de engenharia do meio ambiente- LEMA, da Universidade Federal de Santa Maria UFSM, durante o período de fevereiro a agosto de 2014. Os resultados demonstraram que não foi possível desenvolver o estudo ecotoxicológico com a poliacrilamida, pelo fato de se tratar de uma substância comercial, que não possui pureza analítica, o que levou a resultados irregulares, tornando impossível a reprodução dos ensaios. Porém, na análise ecotoxicológica da acrilamida, os resultados indicaram que esta inibiu significativamente o crescimento das algas, obtendo-se 5,88 mg.L-1 como a concentração que inibiu 50% do crescimento das células algais. Tanto a contagem celular microscópica como a dosagem da clorofila a se mostraram eficientes na quantificação da biomassa do experimento. Os resultados mais importantes do trabalho consistem na análise das alterações do biovolume celular e da plasticidade fenotípica da espécie D. quadricauda, parâmetros ineditamente avaliados para a exposição à acrilamida. A utilização do cálculo do biovolume aliado à contagem celular se mostrou bastante proveitosa na análise dos resultados, demonstrando a variação do tamanho das células no decorrer do experimento. A plasticidade fenotípica do gênero sofreu alterações com a exposição à acrilamida, o que confere um achado importante na avaliação da toxicidade.
62

Polímero eletrólito derivado de goma de cajueiro para uso como floculante no tratamento de efluentes

Klein, Jalma Maria January 2015 (has links)
Neste trabalho, um polímero eletrólito derivado de goma de cajueiro graftizada com poliacrilamida (GC-g-PAM) foi desenvolvido para uso como floculante no tratamento de águas. Foi investigado o efeito da concentração de acrilamida e do iniciador persulfato de potássio, da energia de micro-ondas e de ultrassom sobre a eficiência da reação, produtividade e viscosidade intrínseca dos copolímeros GC-g-PAM. As matérias-primas e os copolímeros graftizados foram caracterizados por espectroscopia de infravermelho, ressonância magnética nuclear, análise termogravimétrica, calorimetria exploratória diferencial e espalhamento de luz dinâmico. A síntese realizada por ultrassom permitiu a obtenção de copolímeros graftizados com elevada eficiência de grafting e viscosidade intrínseca, em curto período de tempo. Os copolímeros obtidos com baixa concentração de iniciador (1,90×10−4 mol e 2,85×10−4 mol) apresentaram raio hidrodinâmico 1,5 vezes maior do que o raio da goma de cajueiro devido à graftização de cadeias longas de poliacrilamida nas cadeias da goma de cajueiro. A estrutura química dos copolímeros graftizados afetou positivamente o desempenho destes quando utilizados como floculante no processo de floculação. Os copolímeros GC-g-PAM apresentaram eficiência superior a 90% na remoção da turbidez de suspensão aquosa de caulim, usada como referência, bem como em água de abastecimento in natura. A grande vantagem dos floculantes GC-g-PAM reside no fato destes apresentarem cadeia macromolecular biodegradável e cadeias laterais menores do que a cadeia principal da poliacrilamida comercial, não biodegradável, utilizada como floculante. O uso do floculante derivado da goma de cajueiro para recuperação e purificação de águas, em detrimento do floculante sintético, visa a longo prazo diminuir o impacto ambiental causado pelo acúmulo de floculante sintético no lodo, já que esse não é biodegradável. / In this work a polymer electrolyte derived from cashew gum with polyacrylamide (GC-g-PAM) was developed for use as a flocculant in water treatment. The effect of concentration of acrylamide and potassium persulfate initiator, as well as microwave and ultrasound energy over the grafting efficiency, productivity, and intrinsic viscosity of copolymers GC-g-PAM were investigated. The raw materials and grafted copolymers were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and dynamic light scattering. The synthesis performed with ultrasound allowed the achievement of grafted copolymer with high grafting efficiency and intrinsic viscosity, in a short reaction time. The copolymers obtained at low initiator concentration (1.90×10−4 mol and 2.85×10−4 mol) presented a hydrodynamic radius 1.5 times larger than the one from cashew gum due to grafting of long chains of polyacrylamide onto cashew gum backbone. The chemical structure of grafted copolymers affected positively the performance of flocculants when they were used in flocculation processes. The turbidity removal of copolymer GC-g-PAM in kaolin suspension, used as reference, and in water treatment was higher than 90%. The great advantage of flocculants GC-g-PAM lies in the fact that they show biodegradable macromolecular chain with branches that are shorter than polyacrylamide commercial, non-biodegradable, used as a flocculant. The use of flocculant derived from cashew gum for water purification and recovery, instead of synthetic flocculant, in long term will decrease the environmental impact caused by the accumulation of synthetic flocculant in the sludge, since it is non-biodegradable.
63

Stimuli Responsive Barrier Materials for Breathable, Chemically-Protective Wearable Fabrics

January 2020 (has links)
abstract: As experiencing hot months and thermal stresses is becoming more common, chemically protective fabrics must adapt and provide protections while reducing the heat stress to the body. These concerns affect first responders, warfighters, and workers regularly surrounded by hazardous chemical agents. While adapting traditional garments with cooling devices provides one route to mitigate this issue, these cooling methods add bulk, are time limited, and may not be applicable in locations without logistical support. Here I take inspiration from nature to guide the development of smart fabrics that have high breathability, but self-seal on exposure to target chemical(s), providing a better balance between cooling and protection. Natural barrier materials were explored as a guide, focusing specifically on prickly pear cacti. These cacti have a natural waxy barrier that provides protection from dehydration and physically changes shape to modify surface wettability and water vapor transport. The results of this study provided a basis for a shape changing polymer to be used to respond directly to hazardous chemicals, swelling to contain the agent. To create a stimuli responsive material, a novel superabsorbent polymer was synthesized, based on acrylamide chemistry. The polymer was tested for swelling properties in a wide range of organic liquids and found to highly swell in moderately polar organic liquids. To help predict swelling in untested liquids, the swelling of multiple test liquids were compared with their thermodynamic properties to observe trends. As the smart fabric needs to remain breathable to allow evaporative cooling, while retaining functionality when soaked with sweat, absorption of water, as well as that of an absorbing liquid in the presence of water were tested. Micron sized particles of the developed polymer were deposited on a plastic mesh with pore size and open area similar to common clothing fabric to establish the proof of concept of using a breathable barrier to provide chemical protection. The polymer coated mesh showed minimal additional resistance to water vapor transport, relative to the mesh alone, but blocked more than 99% of a xylene aerosol from penetrating the barrier. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2020
64

Self-Assembled Polymer Materials : From Amphiphile Design to Nanostructure Control / 自己組織化高分子材料 : 両親媒性分子の設計からナノ構造制御へ

Kimura, Yoshihiko 24 November 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22846号 / 工博第4786号 / 新制||工||1748(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 大内 誠, 教授 竹中 幹人, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
65

Stratégia eliminácie akrylamidu v cereálnych produktoch / A strategy of acrylamide elimination in cereal foods

Belková, Renáta January 2010 (has links)
Acrylamide is a carcinogenic substance generated in heat processed food stuff, where the temperature increases over 120 °C. The main acrylamide precursors are carbonyl compounds and the amino acid asparagine. In this diploma work, possible elimination strategies were observed in a bread matrix with an addition of inorganic salts into the basic powder formulation for home bread making. Samples were analyzed from the point of view of acrylamide content as well as their physico-chemical properties and sensory evaluation too. Results show, that the addition of inorganic salts hasn`t expected considerable elimination impact as in the case of model samples. It has been shown the importance of fermentation process, whereas was the amount of acrylamide in bread without yeast added almost 14times higher. The addition of CaCl2 in bread mixture improved the organoleptic quality of final product, as proved in sensory evaluation with simultaneus positive effect on acrylamide reduction in bread.
66

INFLUENCE OF SODIUM SALTS ON THE SWELLING AND RHEOLOGY OF HYDROPHOBICALLY CROSSLINKED, NON-IONIC HYDROGELS DETERMINED BY QCM-D

Zhang, Mengxue 16 July 2019 (has links)
No description available.
67

Relation entre l'exposition à l'acrylamide par l'alimentation, les marqueurs de dose interne et les cassures à l'ADN lymphocytaire chez des adolescents montréalais

Brisson-Gauthier, Benjamin 19 April 2018 (has links)
L'acrylamide (AA) est une substance cancérigène formée lors de la cuisson à haute température d'aliments à forte teneur en amidon comme les frites et croustilles. Les objectifs de cette étude étaient d'établir une relation entre l'apport alimentaire en AA et les biomarqueurs de dose interne, ainsi qu'entre ces derniers et les cassures à l'ADN lymphocytaire, un biomarqueur d'effet génotoxique précoce, chez des adolescents montréalais. Deux cent adolescents âgés de 10 à 17 ans habitant Montréal, au Canada, ont été recrutés. Leurs caractéristiques sociodémographiques et leurs habitudes de vie ont été documentées par questionnaire. Les concentrations d'AA et de ses metabolites ont été mesurées dans 195 échantillons d'urine (collectés sur une période de 12 h) à l'aide d'un chromatographe en phase liquide couplé à un spectromètre de masse en tandem (LC-MS/MS). Les niveaux d'adduits à l'hémoglobine ont aussi été mesurés par LC-MS/MS dans 165 échantillons sanguins. Les cassures à l'ADN lymphocytaire ont été mesurées par le test des comètes en conditions alcalines à partir de 130 échantillons. Les deux principaux metabolites urinaires étaient le N-acétyl-cystéine-S-propionamide (NACP) et le NACP-sulfoxyde (NACP-S), avec des concentrations moyennes respectives de 31,2 et 14,2 umol/mol de creatinine (moyennes géométriques). Les concentrations moyennes de AAVal (adduit de l'acrylamide avec la valine) et GAVal (adduit du glycidamide, un metabolite de l'AA, avec la valine) étaient respectivement de 45,4 et 45,6 pmol/ g de globine. Ces deux adduits ont été détectés dans tous les échantillons à des niveaux similaires à ceux mesurés chez des Américains du même groupe d'âge. Les analyses multivariées ont révélées que la somme des concentrations urinaires de NACP et NACP-S est associée avec l'apport alimentaire moyen de AA durant les deux jours précédent les prélèvements (p < 0,0001) tandis que la somme des niveaux d'adduits AAVal et GAVal est associée à l'apport alimentaire journalier moyen durant le mois précédent les prélèvements (p < 0,0001) ainsi qu'au tabagisme passif (p < 0,05). Les biomarqueurs d'exposition n'étaient pas corrélés aux cassures à l'ADN lymphocytaire. Les concentrations urinaires de NACP et de NACP-S reflètent l'exposition récente à l'acrylamide, alors que niveaux des adduits AAVal et GAVal reflètent une exposition à plus long terme. L'exposition à l'AA chez ce groupe d'adolescents ne semble pas suffisamment élevée pour induire des dommages à l'ADN lymphocytaire.
68

Electrophysiologic detection of the neurotoxic effects of acrylamide and 2,5-hexanedione in rats

Towell, Todd L. 23 June 2009 (has links)
Brain stem auditory evoked potentials (BAEP) and somatosensory evoked potentials (SEP), recorded from subcutaneously placed electrodes in anesthetized rats, were used to detect the neurotoxic effects of acrylamide and 2,5-hexanedione. Sixty adult male rats were equally divided into four groups: acrylamide (20 mg/kg/day), 2,5-hexanedione (350 mg/kg/day), food restricted and control. Brain stem auditory evoked potentials and somatosensory evoked potentials were recorded on weeks 0,1,2 and 3 of treatment. SEP waveforms were considerably more variable than BAEP results. Mean latencies in the control, food restricted and acrylamide groups were similar for the entire three weeks. A nonsignificant increase was seen in the mean latencies in the 2,5-hexanedione group. Brain stem auditory evoked potential latencies recorded on the pretreatment week were compared to each successive week within a treatment group. The control group had small but statistically significant prolongations in the latencies of wave II on weeks 2 and 3, and latencies III and IV on week 3. Results from the food restricted group were not statistically different at any time. The acrylamide group had prolongations in latency II and IV by week 3 of treatment. Latencies of all waveforms from the 2,5-hexanedione group were significantly longer than pretreatment values on weeks 2 and 3. Mean latencies of the two consistently identified somatosensory evoked potential waves (Pl, Nl) recorded from the contralateral cortex on the pretreatment week were comparable to values reported in the literature. Brain stem auditory evoked potentials recorded from subcutaneously placed electrodes in anesthetized rats can detect the neurotoxic effects of acrylamide and 2,5-hexanedione. Lack of significant differences in the food restricted group indicates the observed effects in the groups receiving neurotoxicant were not related to weight loss. Differences in the control group were of small magnitude and variance and therefore may be statistically but not biologically significant. / Master of Science
69

Highly-branched poly(N-isopropyl acrylamide)s with core-shell morphology below the lower critical solution temperature

Plenderleith, R.A., Swift, Thomas, Rimmer, Stephen 10 March 2014 (has links)
Yes / Highly-branched poly(N-isopropyl acrylamide)s in water pass through coil-to-globule transitions. Using calorimetry and the colour change of a solvatochromic dye within the polymer, we show that some compositions have biphasic core–shell morphologies, with globular cores and open coil shells. The two-phase structure is favoured by increased branching and arises because the chain ends penetrate only to a limited degree into the polymer coil.
70

Polyethers and polyamide-3 synthesis by monomer activated anionic polymerization / Polymérisation anionique par activation du monomère pour la synthèse de polyéthers et de polyamide-3

Roos, Kevin 15 December 2015 (has links)
Ces travaux de thèse traitent de la polymérisation anionique combinée à deux méthodologies différentes d’activation du monomère visant à contrôler les réactivités des monomères et/ou des espèces actives lors de la propagation pour la synthèse de polyéthers et de polyamide-3. L’étude de nouveaux systèmes efficaces d’amorçage/propagation à base de magnésium et d’aluminium pour la polymérisation anionique par ouverture de cycles des époxydes substitués est présentée. Deux types de polyéthers réticulables ont également été synthétisés par l’utilisation de bromure de tétraoctylammonium et de triisobutyl-aluminium. Dans le premier cas, l’objectif est d’incorporer des fonctions furane pendantes le long des chaînes polyéthers. Dans le second cas il s’agit d’introduire des doubles liaisons au sein même du squelette polyéther. Les réticulations ont ensuite été effectuées thermiquement par le biais d’une chimie réversible de type Diels-Alder entre groupement furane et maléimide pour le premier cas et par vulcanisation pour le deuxième. Enfin, une étude menant à une compréhension mécanistique a été conduite sur la synthèse de polyamide-3 en masse par polymérisation par transfert d’hydrogène à partir de l’acrylamide. / The studies presented in this thesis report on the use of the anionic polymerization with two different methodologies of monomer activation aiming to control the reactivity of monomers and/or growing species for the synthesis of polyethers and polyamide-3. New magnesium/aluminium active systems efficient for the anionic ringopening polymerization of substituted epoxides are proposed and developed. Cross-linkable polyethers were also synthesized by using the combination of tetraoctylammonium bromide with triisobutylaluminum. Furan groups or double bonds were introduced as pendant or inchain functions respectively in polyether-based materials. The so-formed polymers were cross-linked using reversible Diels-Alder reaction between furan and maleimide, and vulcanization for the double bonds. Finally, we investigated the mechanism of the hydrogentransfer polymerization of acrylamide in bulk conditions as a sustainable route to get polyamide-3.

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