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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.
1

Descrição de um fóssil de Eira barbara (Carnivora, Mustelidae) do Pleistoceno final (Bacia do Acre) e morfologia comparada do sincrânio de E. barbara recente: implicações paleobiogeográficas, geográficas e taxonômicas / Description of a fossil of Eira barbara (Carnivora, Mustelidae) from the Late Pleistocene (Acre Basin) and comparative morphology of the sincranium of extant E. barbara: paleobiogeographic, geographic and taxonomic implications

Lopes, Paulo Ricardo Mendonça 28 April 2016 (has links)
A espécie recente Eira barbara (Mustelidae, Carnivora) possui uma distribuição geográfica desde o México até o norte da Argentina. É um importante táxon a ser estudado como modelo anatômico dentre os mustelídeos, assim como um importante modelo para uma melhor compreensão e entendimento sobre a diversificação dos Mustelidae. Atualmente, os registros fósseis de E. barbara na América do Sul são bastante escassos e restritos às idades pleistocênicas, sendo que os estudos destes fósseis são frequentemente desprovidos de maiores esforços para realização de descrições morfológicas detalhadas e de estudos paleobiogeográficos. Assim como os estudos dos fósseis de E. barbara são limitados, constatou-se que o mesmo cenário é observado quanto aos estudos sobre a morfologia e biogeografia da espécie. Desta forma, o presente trabalho se propôs a: realizar uma revisão de todos os registros da espécie e de uma forma geral, contribuir para um melhor conhecimento sobre a morfologia sincraniana e sobre a história biogeográfica e paleobiogeográfica de E. barbara. Para tanto, os seguintes objetivos foram propostos: estudo e redescrição detalhada do fóssil UFAC-PV 036, proveniente do Pleistoceno final do Alto Rio Juruá do sudoeste da Amazônia Brasileira; descrição sincraniana comparada de estruturas morfológicas externas e internas, analisando caracteres intraespecíficos da espécie E. barbara; realização de análises multivariadas a fim de investigar variações geográficas sob o uso de caracteres craniométricos de E. barbara entre os diferentes biomas brasileiros. A revisão dos registros fósseis foi de grande importância para o estabelecimento dos verdadeiros registros de Eira na América do Sul e a redescrição de UFAC-PV 36 contribui para o melhor conhecimento morfológico e paleobiogeográfico da espécie. A descrição morfológica comparada do sincrânio de E. barbara contribui de forma significativa para o conhecimento sobre a morfologia da espécie bem como, a descrição de caracteres intraespecíficos proporcionam caracteres mais apropriados em matrizes morfológicas, fornecendo maior robustez nas análises filogenéticas futuras. Este trabalho propõe que E. barbara não possui diferenças craniométricas estatisticamente significativas entre os biomas brasileiros, porém, E. barbara caracteriza-se aqui como uma espécie dimórfica, na qual os machos possuem estruturas cranianas relativamente maiores do que as fêmeas. / The recent species Eira barbara (Mustelidae, Carnivora) has a geographic distribution from Mexico to northern Argentina. It is an important taxon to be studied as an anatomical model for the mustelids, as well as an important model for a better understanding of the diversification of the Mustelidae. Currently, the fossil record of E. barbara in South America is scarce and restricted to the Pleistocene, while the studies of these fossils frequently lack greater efforts to perform detailed morphological descriptions and paleobiogeographic studies. Besides limited studies of fossil E. barbara, it was established that the same scenario is seen for the studies on the morphology and biogeography of the species. Thus, this work proposed to: perform a review of all records of the species and, in general, to contribute to a better understanding of the sincranian morphology and the biogeographic and paleobiogeographic studies of E. barbara. In order to achieve this, the following objectives were proposed: study and detailed redescription of the fossil UFAC PV-036 from the Late Pleistocene of Upper Juruá River of the southwest of Brazilian Amazon; compared sincranian description of external and internal morphological structures, analyzing intraspecific characters of extant E. barbara; performance of multivariate analysis to investigate geographical variations on the use of craniometric characters of E. barbara between different Brazilian biomes. The review of the fossil record was of great importance for the establishment of the actual records of the species in South America, while the redescription of UFAC PV-36 contributes to a better anatomical and paleobiogeographic knowledge of the species. The morphological description of the sincranium of E. barbara contribute significantly to the knowledge of the morphology of the species, as much as the description of intraspecific variation provides more appropriate morphological characters in matrices, providing greater robustness in futures phylogenetic analysis. This work proposes that E. barbara does not have statistically significant craniometric differences among Brazilian biomes; however, E. barbara is characterized here as a dimorphic species in which the males have cranial structures relatively larger than the females.
2

Descrição de um fóssil de Eira barbara (Carnivora, Mustelidae) do Pleistoceno final (Bacia do Acre) e morfologia comparada do sincrânio de E. barbara recente: implicações paleobiogeográficas, geográficas e taxonômicas / Description of a fossil of Eira barbara (Carnivora, Mustelidae) from the Late Pleistocene (Acre Basin) and comparative morphology of the sincranium of extant E. barbara: paleobiogeographic, geographic and taxonomic implications

Paulo Ricardo Mendonça Lopes 28 April 2016 (has links)
A espécie recente Eira barbara (Mustelidae, Carnivora) possui uma distribuição geográfica desde o México até o norte da Argentina. É um importante táxon a ser estudado como modelo anatômico dentre os mustelídeos, assim como um importante modelo para uma melhor compreensão e entendimento sobre a diversificação dos Mustelidae. Atualmente, os registros fósseis de E. barbara na América do Sul são bastante escassos e restritos às idades pleistocênicas, sendo que os estudos destes fósseis são frequentemente desprovidos de maiores esforços para realização de descrições morfológicas detalhadas e de estudos paleobiogeográficos. Assim como os estudos dos fósseis de E. barbara são limitados, constatou-se que o mesmo cenário é observado quanto aos estudos sobre a morfologia e biogeografia da espécie. Desta forma, o presente trabalho se propôs a: realizar uma revisão de todos os registros da espécie e de uma forma geral, contribuir para um melhor conhecimento sobre a morfologia sincraniana e sobre a história biogeográfica e paleobiogeográfica de E. barbara. Para tanto, os seguintes objetivos foram propostos: estudo e redescrição detalhada do fóssil UFAC-PV 036, proveniente do Pleistoceno final do Alto Rio Juruá do sudoeste da Amazônia Brasileira; descrição sincraniana comparada de estruturas morfológicas externas e internas, analisando caracteres intraespecíficos da espécie E. barbara; realização de análises multivariadas a fim de investigar variações geográficas sob o uso de caracteres craniométricos de E. barbara entre os diferentes biomas brasileiros. A revisão dos registros fósseis foi de grande importância para o estabelecimento dos verdadeiros registros de Eira na América do Sul e a redescrição de UFAC-PV 36 contribui para o melhor conhecimento morfológico e paleobiogeográfico da espécie. A descrição morfológica comparada do sincrânio de E. barbara contribui de forma significativa para o conhecimento sobre a morfologia da espécie bem como, a descrição de caracteres intraespecíficos proporcionam caracteres mais apropriados em matrizes morfológicas, fornecendo maior robustez nas análises filogenéticas futuras. Este trabalho propõe que E. barbara não possui diferenças craniométricas estatisticamente significativas entre os biomas brasileiros, porém, E. barbara caracteriza-se aqui como uma espécie dimórfica, na qual os machos possuem estruturas cranianas relativamente maiores do que as fêmeas. / The recent species Eira barbara (Mustelidae, Carnivora) has a geographic distribution from Mexico to northern Argentina. It is an important taxon to be studied as an anatomical model for the mustelids, as well as an important model for a better understanding of the diversification of the Mustelidae. Currently, the fossil record of E. barbara in South America is scarce and restricted to the Pleistocene, while the studies of these fossils frequently lack greater efforts to perform detailed morphological descriptions and paleobiogeographic studies. Besides limited studies of fossil E. barbara, it was established that the same scenario is seen for the studies on the morphology and biogeography of the species. Thus, this work proposed to: perform a review of all records of the species and, in general, to contribute to a better understanding of the sincranian morphology and the biogeographic and paleobiogeographic studies of E. barbara. In order to achieve this, the following objectives were proposed: study and detailed redescription of the fossil UFAC PV-036 from the Late Pleistocene of Upper Juruá River of the southwest of Brazilian Amazon; compared sincranian description of external and internal morphological structures, analyzing intraspecific characters of extant E. barbara; performance of multivariate analysis to investigate geographical variations on the use of craniometric characters of E. barbara between different Brazilian biomes. The review of the fossil record was of great importance for the establishment of the actual records of the species in South America, while the redescription of UFAC PV-36 contributes to a better anatomical and paleobiogeographic knowledge of the species. The morphological description of the sincranium of E. barbara contribute significantly to the knowledge of the morphology of the species, as much as the description of intraspecific variation provides more appropriate morphological characters in matrices, providing greater robustness in futures phylogenetic analysis. This work proposes that E. barbara does not have statistically significant craniometric differences among Brazilian biomes; however, E. barbara is characterized here as a dimorphic species in which the males have cranial structures relatively larger than the females.
3

Polypropylene and Natural Rubber based Thermoplastic Vulcanizates by Electron Induced Reactive Processing

Mondal, Manas 28 October 2013 (has links) (PDF)
Thermoplastic Vulcanizates (TPVs) are itself a commercially high valued group of polymer blend. They render technological properties of conventional vulcanized elastomers with the ease of thermoplastic melt (re)processability. With ever growing market, TPVs have got plenty of applications among various fields. Here, the technological properties of these TPVs were tailored according to the purpose by interplaying physical parameters of polymers and advanced high energy electron technology. Electron irradiation, though a well-known technique for cross-linking in polymer industry, is only restricted to final product treatment. We take it to the next level by coupling a conventional internal mixer and a high energy electron accelerator. Polypropylene (PP) and natural rubber (NR) based TPVs have been prepared using this new reactive processing technology, named Electron Induced Reactive Processing (EIReP). Various electron treatment parameters were explored to maximize technological properties of TPVs. Effects of various polyfunctional monomers (PFM) were also studied. In an endeavor to develop a potential method for customization, deep insights of macroscopic and microscopic structure of these TPVs were presented with the help of various advanced scientific characterization techniques. Commonly faced difficulties like viscosity mismatch, cure rate mismatch, and incompatibility due to different molecular structures were furnished along with plausible solutions. Investigation of phase inversion from co-continuous matrix to thermoplastic matrix was dealt with special care as it helps to understand structure property correlation for all TPVs. To make the whole effort relevant, at the end of this thesis a summary of various technological properties has been given for the newly processed and commercially available TPVs.
4

Polypropylene and Natural Rubber based Thermoplastic Vulcanizates by Electron Induced Reactive Processing: Polypropylene and Natural Rubber based Thermoplastic Vulcanizates by Electron Induced Reactive Processing

Mondal, Manas 26 September 2013 (has links)
Thermoplastic Vulcanizates (TPVs) are itself a commercially high valued group of polymer blend. They render technological properties of conventional vulcanized elastomers with the ease of thermoplastic melt (re)processability. With ever growing market, TPVs have got plenty of applications among various fields. Here, the technological properties of these TPVs were tailored according to the purpose by interplaying physical parameters of polymers and advanced high energy electron technology. Electron irradiation, though a well-known technique for cross-linking in polymer industry, is only restricted to final product treatment. We take it to the next level by coupling a conventional internal mixer and a high energy electron accelerator. Polypropylene (PP) and natural rubber (NR) based TPVs have been prepared using this new reactive processing technology, named Electron Induced Reactive Processing (EIReP). Various electron treatment parameters were explored to maximize technological properties of TPVs. Effects of various polyfunctional monomers (PFM) were also studied. In an endeavor to develop a potential method for customization, deep insights of macroscopic and microscopic structure of these TPVs were presented with the help of various advanced scientific characterization techniques. Commonly faced difficulties like viscosity mismatch, cure rate mismatch, and incompatibility due to different molecular structures were furnished along with plausible solutions. Investigation of phase inversion from co-continuous matrix to thermoplastic matrix was dealt with special care as it helps to understand structure property correlation for all TPVs. To make the whole effort relevant, at the end of this thesis a summary of various technological properties has been given for the newly processed and commercially available TPVs.
5

Modifizierung der Werkstoffeigenschaften von Polypropylen-Kompositen durch eine Hochtemperatur-Elektronenbehandlung / Modification of material properties of polypropylene composites by high temperature electron beam treatment

Volke, Sebastian 24 February 2011 (has links) (PDF)
Polypropylene (PP) is a common thermoplastic and frequently adapted permanently with increasing requirements by adding fillers as well as reinforcing materials. Because of incompatibility of non-polar PP and polar inorganic filler, resulting composites are brittle which has a detrimental effect on the desired properties. Improvements in mechanical properties can be reached by compatibilization, creating of chemical couplings between phases and by increasing of inhomogeneity. Thus, maleic anhydride grafted PP is used as well as reactive processing of PP in presence of peroxide radical initiators. The temperature dependence of peroxide decay as well as the dependence of radical generation rate on time are two disadvantages of peroxide induced reactive processing. Modification of polymers with high energy electron treatment is also well known and used to form parts (after) molding as well as raw materials (pellets, powders, fibers) in solid state and at room temperature. The spatially and temporally precise input of energy is used to produce desired material properties on radical-induced chemical reactions. Coupling of high energy electron modification of polymers and melt mixing offers a new possibility of reactive processing. In this case, radical generation is independent of temperature, can be easily controlled by beam current and kept constant over time. Absence of any crystallinity, high reaction rates as well as intensive macromolecular mobility and intensive mixing are reasons to expect novel structures and properties. Electron beam induced reactive processing is a novel technique where chemical reactions are induced by spatial and temporal precise energy input via high energy electrons under dynamic conditions of melt mixing. This method gives the possibility to increase surface energy of polypropylene (PP) effectively as well as to generate chemical couplings between filler and PP. The process was applied to a proved system consisting of PP (38 wt%), magnesium hydroxide (MH) (60 wt%), triallyl cyanurate (TAC) (2 wt%). This composite system was successful tested in peroxide induced conventional reactive processing. Absorbed dose imparted per rotation of rotors is a new parameter controlling mechanical properties of polymer composites. Improved properties were found in tensile strength (150 %), elongation at break (175 %), and impact strength (175 %). It can be shown that chemical couplings are generated during electron induced reactive processing in comparison to only compatibilized material.
6

Modifizierung der Werkstoffeigenschaften von Polypropylen-Kompositen durch eine Hochtemperatur-Elektronenbehandlung

Volke, Sebastian 09 February 2011 (has links)
Polypropylene (PP) is a common thermoplastic and frequently adapted permanently with increasing requirements by adding fillers as well as reinforcing materials. Because of incompatibility of non-polar PP and polar inorganic filler, resulting composites are brittle which has a detrimental effect on the desired properties. Improvements in mechanical properties can be reached by compatibilization, creating of chemical couplings between phases and by increasing of inhomogeneity. Thus, maleic anhydride grafted PP is used as well as reactive processing of PP in presence of peroxide radical initiators. The temperature dependence of peroxide decay as well as the dependence of radical generation rate on time are two disadvantages of peroxide induced reactive processing. Modification of polymers with high energy electron treatment is also well known and used to form parts (after) molding as well as raw materials (pellets, powders, fibers) in solid state and at room temperature. The spatially and temporally precise input of energy is used to produce desired material properties on radical-induced chemical reactions. Coupling of high energy electron modification of polymers and melt mixing offers a new possibility of reactive processing. In this case, radical generation is independent of temperature, can be easily controlled by beam current and kept constant over time. Absence of any crystallinity, high reaction rates as well as intensive macromolecular mobility and intensive mixing are reasons to expect novel structures and properties. Electron beam induced reactive processing is a novel technique where chemical reactions are induced by spatial and temporal precise energy input via high energy electrons under dynamic conditions of melt mixing. This method gives the possibility to increase surface energy of polypropylene (PP) effectively as well as to generate chemical couplings between filler and PP. The process was applied to a proved system consisting of PP (38 wt%), magnesium hydroxide (MH) (60 wt%), triallyl cyanurate (TAC) (2 wt%). This composite system was successful tested in peroxide induced conventional reactive processing. Absorbed dose imparted per rotation of rotors is a new parameter controlling mechanical properties of polymer composites. Improved properties were found in tensile strength (150 %), elongation at break (175 %), and impact strength (175 %). It can be shown that chemical couplings are generated during electron induced reactive processing in comparison to only compatibilized material.:1 Einleitung 6 2 Stand der Technik 8 2.1 Werkstoffeigenschaften von Polypropylen-Kompositen 8 2.1.1 Polypropylen 8 2.1.2 Füll- und Verstärkungsstoffe 10 2.1.3 Phasengrenze und Phasenmorphologie 12 2.1.3.1 Füllstoffmodifizierung 15 2.1.3.2 PP-Modifizierung 16 2.1.3.3 Mehrkomponentensysteme 17 2.1.3.4 Ansätze aus anderen Werkstoffsystemen 18 2.2 Reaktive Aufbereitung 19 2.3 Polymermodifizierung mit energiereichen Elektronen 22 2.3.1 Einordnung und Wechselwirkungsmechanismen 22 2.3.2 Einfluss von Polymerstruktur und G-Wert 25 2.3.3 Steuerparameter 26 2.3.3.1 Parameter der chemischen Umgebung 26 2.3.3.2 Parameter der Elektronenmodifizierung 28 2.3.4 Bestrahlung von Polypropylen 32 2.3.5 Bestrahlung von partikelgefüllten Thermoplastkompositen 33 2.3.6 Bestrahlung von Füll- und Verstärkungsstoffen 33 2.4 Zusammenfassung Stand Technik 34 3 Zielstellung 37 4 Aufgabenstellung 39 5 Experimentelles 40 5.1 Anlagentechnik 40 5.1.1 Stationäre Behandlung 40 5.1.2 Elektronen induzierte reaktive Aufbereitung 41 5.1.2.1 Aufbau u. Funktionsweise 41 5.1.2.2 Parameter der Elektronen induzierten reaktiven Aufbereitung 42 5.1.2.3 Dosimetrie 44 5.2 Probenherstellung 45 5.2.1 Materialien 45 5.2.2 Aufbereitung 45 5.2.3 Prüfkörperherstellung 46 5.3 Modifizierungsparameter 47 5.4 Vorgehensweise 49 5.5 Analytische Methoden 51 5.5.1 Zugversuch 51 5.5.2 Schlagbiegeversuch (nach Charpy) 52 5.5.3 Größenausschlusschromatographie (SEC) 54 5.5.4 Dynamische Differenzkalorimetrie (DSC) 55 5.5.5 Laserbeugungsspektrometrie 57 5.5.6 Rasterelektronenmikroskopie (REM) 58 5.5.7 Fourier-Transmissions-Infrarot-Spektroskopie (FTIR) 58 5.5.8 Dynamische Kontaktwinkelmessung 59 5.5.9 Schmelzerheologische Untersuchungen von Polymerschmelzen 60 5.5.9.1 Ungefüllte Polymerschmelzen 62 5.5.9.2 Partikelgefüllte Polymerschmelzen 63 6 Ergebnisse 68 6.1 Mechanische Kompositeigenschaften 68 6.2 Matrixpolymersysteme PP und PPTAC 69 6.3 Partikelgröße und -verteilung 75 6.4 Kompatibilität 77 6.5 Phasenkopplung 82 6.6 Inhomogenität 86 6.7 Einfluss verschiedener Prozessparameter auf die mechanischen Eigenschaften 87 6.7.1 Dosis 88 6.7.2 Elektronenenergie 90 6.7.3 Bestrahlungsdauer 91 6.7.4 Aufbereitungszeit 93 6.7.5 Dosisleistung im Modifizierungsvolumen 96 7 Zusammenfassung 98 8 Ausblick 100 9 Anhang 104 10 Literaturverzeichnis 112 11 Abkürzungsverzeichnis 115

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