Polyesteramides dérivés de la ε - caprolactone et d'acides aminés naturels

This thesis reports the synthesis and thermal and mechanical properties of random or quasi-alternating polyesteramides obtained from ε-caprolactone and natural aminoacids (β-alanine, glycine and α-alanine). The random polyesteramides were obtained by one-pot simultaneous ring-opening and polycondensation of the two monomers, while the alternating ones were prepared by polyesterification of hydroxy- and ester-terminated dimers, previously synthesized by reaction between ε-caprolactone and aminoacid esters. The structure and microstructure of these polyesteramides were studied by FTIR and 1D and 2D NMR spectroscopies. As expected, polyesteramides synthesized by the two-step method present a quasi-alternating structure, while those synthesized by the one-pot method are completely random. The study of their thermal properties by DSC and TGA shows that these polyesteramides are semi-crystalline and present a better thermal stability than poly(ε-caprolactone). For the random polyesteramides with β-alanine fractions greater than or equal to 50 mol-%, increasing β-alanine fractions leads to increasing Young's modulus and tensile strength, larger than those of poly(ε-caprolactone). The quasi-alternating polyesteramides exhibit thermal and mechanical properties well above than those of their random counterparts.Ce mémoire traite de la synthèse et des propriétés thermiques et mécaniques de polyesteramides statistiques et quasi-alternés obtenus à partir de l’ε-caprolactone et d'acides aminés naturels (β-alanine, glycine et α-alanine). Les polyesteramides statistiques ont été obtenus par ouverture de cycle et polycondensation simultanée des deux monomères par une méthode monotope, tandis que les polyesteramides quasi-alternés ont été élaborés par polyestérification d’un dimère à extrémités hydroxy et ester, préalablement synthétisé par réaction entre ε-caprolactone et ester d'acide aminé. La structure et la microstructure de ces polyesteramides ont été étudiées par spectroscopiques IRTF et RMN 1D et 2D. Les polyesteramides obtenus en deux étapes présentent, comme attendu, une forte tendance à l'alternance, alors que ceux obtenus par synthèse monotope sont complètement statistiques. L’étude des propriétés thermiques par DSC et ATG montre que ces polyesteramides sont semi-cristallins et qu'ils présentent une meilleure stabilité thermique que celle de la poly(ε-caprolactone). Les polyesteramides statistiques contenant des fractions croissantes en β-alanine et supérieures ou égales à 50 mol-% présentent des valeurs de module d’Young et de contrainte à la rupture en traction croissantes et plus élevées que celles de la poly(ε-caprolactone). Les polyesteramides quasi-alternés présentent une cristallinité et des propriétés mécaniques nettement supérieure à celles de leurs homologues statistiques

Polyesteramides derived from ε - caprolactone et natural aminoacids

Ce mémoire traite de la synthèse et des propriétés thermiques et mécaniques de polyesteramides statistiques et quasi-alternés obtenus à partir de l’ε-caprolactone et d'acides aminés naturels (β-alanine, glycine et α-alanine). Les polyesteramides statistiques ont été obtenus par ouverture de cycle et polycondensation simultanée des deux monomères par une méthode monotope, tandis que les polyesteramides quasi-alternés ont été élaborés par polyestérification d’un dimère à extrémités hydroxy et ester, préalablement synthétisé par réaction entre ε-caprolactone et ester d'acide aminé. La structure et la microstructure de ces polyesteramides ont été étudiées par spectroscopiques IRTF et RMN 1D et 2D. Les polyesteramides obtenus en deux étapes présentent, comme attendu, une forte tendance à l'alternance, alors que ceux obtenus par synthèse monotope sont complètement statistiques. L’étude des propriétés thermiques par DSC et ATG montre que ces polyesteramides sont semi-cristallins et qu'ils présentent une meilleure stabilité thermique que celle de la poly(ε-caprolactone). Les polyesteramides statistiques contenant des fractions croissantes en β-alanine et supérieures ou égales à 50 mol-% présentent des valeurs de module d’Young et de contrainte à la rupture en traction croissantes et plus élevées que celles de la poly(ε-caprolactone). Les polyesteramides quasi-alternés présentent une cristallinité et des propriétés mécaniques nettement supérieure à celles de leurs homologues statistiques.This thesis reports the synthesis and thermal and mechanical properties of random or quasi-alternating polyesteramides obtained from ε-caprolactone and natural aminoacids (β-alanine, glycine and α-alanine). The random polyesteramides were obtained by one-pot simultaneous ring-opening and polycondensation of the two monomers, while the alternating ones were prepared by polyesterification of hydroxy- and ester-terminated dimers, previously synthesized by reaction between ε-caprolactone and aminoacid esters. The structure and microstructure of these polyesteramides were studied by FTIR and 1D and 2D NMR spectroscopies. As expected, polyesteramides synthesized by the two-step method present a quasi-alternating structure, while those synthesized by the one-pot method are completely random. The study of their thermal properties by DSC and TGA shows that these polyesteramides are semi-crystalline and present a better thermal stability than poly(ε-caprolactone). For the random polyesteramides with β-alanine fractions greater than or equal to 50 mol-%, increasing β-alanine fractions leads to increasing Young's modulus and tensile strength, larger than those of poly(ε-caprolactone). The quasi-alternating polyesteramides exhibit thermal and mechanical properties well above than those of their random counterparts

Determining entrepreneurial knowledge and intentions of international students studying in Turkey

Bu çalışmanın amacı, Türkiye'de öğrenim gören uluslararası öğrencilerin girişimcilik niyetlerini ölçmektir. Üniversite öğrencilerinin, özellikle de uluslararası öğrencilerin girişimcilik niyetlerini etkileyen ana faktörleri araştırmak ve üniversitede girişimcilik niyetlerini teşvik eden koşulların oluşturulması için önerilerde bulunmaktadır. Bu çalışmada, nicel yöntem kullanılmıştır, nicel araştırma için anket tekniğinden faydalanılmıştır. Veri toplama için Türkiye'deki üniversitelerde okuyan uluslararası öğrenciler evren olarak belirlenmiş, bu evrenden kolayda örnekleme yöntemi ile 380 öğrenci örneklem olarak seçilmiştir. Hipotezleri test etmek için SPSS ve AMOS istatistik paket programları kullanılmıştır. Çalışmada frekans analizleri, yüzde analizleri, fark analizleri, güvenirlik ve geçerlik analizleri, korelasyon ve regresyon analizleri yapılarak, toplanan veriler analiz edilmiştir. Bu çalışma dört bölümden oluşmaktadır. Birinci bölümde çalışmanın konusu ve amacı hakkında giriş bölümü yer almaktadır. İkinci bölümde uluslararası öğrenciler, girişimcilik temel kavramlar, girişimcilik bilgisi ve niyeti ile ilgili yapılmış çalışmalardan bahsedilmiştir. Üçüncü bölümde ise çalışmanın araştırma yöntem ve metodolojisi, araştırmacı verilerin analizi ele almıştır. Son bölümde ise çalışmanın sonuçları ve öneriler yer almaktadır. Bu çalışmanın sonuçları, Türkiye'deki uluslararası öğrenciler arasında tatmin edici düzeyde girişimcilik niyeti olduğunu göstermiştir. Genel olarak, araştırma modeli anlamlıdır ve özellikle girişimcilik bilgisi üniversite öğrencilerinin girişimcilik niyetleri üzerinde oldukça etkilidir. Bu çalışma girişimcilik eğitiminin öğrencilerin girişimcilik niyeti üzerinde etkili olan en önemli faktör olduğunu ortaya koymuştur. Bu nedenle, üniversite müfredatlarında girişimcilik eğitiminin geliştirilmesi şiddetle tavsiye edilmektedir.The aim of this study is to measure the entrepreneurial intentions of international students studying in Turkey. It recommends investigating the main factors affecting the entrepreneurial intentions of university students, especially international students, and creating conditions that encourage entrepreneurial intentions at the university. In this study, a quantitative method was used, questionnaire technique was used for quantitative research. for data collection, international students studying at universities in Turkey were determined as the universe, and 380 students were selected as a sample from this universe by convenience sampling method. SPSS and AMOS statistical packages were used to test the hypotheses. in the study, the collected data were analyzed by performing frequency analysis, percentage analysis, difference analysis, reliability and validity analysis, correlation, and regression analysis. This study consists of four parts. in the first chapter, there is an introduction about the subject and purpose of the study. the second part mentions studies on international students, entrepreneurship basic concepts, entrepreneurship knowledge and intention. In the third part, the research study's research method and methodology and the researcher data analysis cussed. in the last section, the results and recommendations of the study are included. This study's results showed a satisfactory level of entrepreneurial intention among international students in Turkey. Overall, the research model is meaningful and entrepreneurial knowledge in particular is highly influential on university students' entrepreneurial intentions. This study revealed that entrepreneurship education is the most important factor influencing students' entrepreneurial intention. Therefore, the development of entrepreneurship education in university curricula is highly recommended

Méthodologie pour l’implémentation du recensement national du cheptel animal en République de Djibouti

La Direction de la Statistique et des Études Démographiques (DISED) et la Direction de l’Élevage et des Services Vétérinaires (DESV) avec l’appui technique de la FAO à Djibouti (à travers le TCP/DJI/3501) ont développé d’une façon  participative une méthodologie pour le recensement du cheptel animal en République de Djibouti. Cette méthodologie a été élaborée en prenant en compte les avis des leaders d’opinion clés et des experts techniques locaux ainsi que la documentation scientifique existante dans ce domaine.La méthodologie propose l’utilisation du relevé aérien pour l’identification des emplacements des ménages éleveurs et l’estimation de leurs effectifs ainsi que de la taille et de la composition de leurs troupeaux en fournissant les coordonnées GPS. Le relevé aérien permettra également d’identifier et de fournir les coordonnées géographiques de tous les points d’eau. L’agent recenseur va interviewer le chefde ménage de chaque exploitation d’élevage identifiée. La technique « boule de neige » sera utilisée pour accélérer l’identification des ménages éleveurs.Mots-clés: méthodologie, recensement du bétail Djibout

Random and quasi-alternating polyesteramides deriving from \varepsilon-caprolactone and β-alanine

International audienc

Quasi-alternating polyesteramides from \varepsilon-caprolactone and α-amino acids

International audienc

Random polyesteramides based on \varepsilon-caprolactone and glycine

International audienc