Este trabalho apresenta uma parte introdutória que descreve os conceitos básicos da determinação de estruturas cristalinas e, na parte experimental, a determinação da estrutura cristalina e molecular, por difração de raios-X, de dois compostos de coordenação contendo cobre: catena-tri-µ-cloro-µ-[trans-1,2-bis(4-piridil)eteno]cobre(I): Sistema cristalino monoclínico; grupo espacial P21/c; a=3,7819(1); b=15,0582(9); c=10,8742(6) Å; B=96,284(4)º; Z= 4 moléculas por cela unitária; V=615,55(5) Å3; Dc=2,040 Mg.m-3. Os índices de discordância finais são: Robs=0,0465 ; Rall=0,1367 com GOF=1,13 para 1243 reflexões observadas (I>2Sigma(I)) e 83 parâmetros refinados. µ-oxalato-µ-[trans-1,2-bis(piridil)eteno]cobre(II): Sistema cristalino triclínico; grupo espacial P ; a=8,7948(5); b=9,0228(5); c=5,5172(3) Å; Alfa=108,860(3), Beta=109,895(3), Gama=97,572(3)º; Z= 2 moléculas por cela unitária; V=374,92(4) Å3; Dc=1,469 Mg.m-3. Os índices de discordância finais são: Robs=0,0567, Rall=0,1544 com GOF=1,08 para 1694 reflexões observadas (I>2Sigma(I)) e 97 parâmetros refinados. Estes complexos são produtos da reação entre oxalato de potássio e cloreto de cobre(II) dihidratado. A síntese foi feita na presença de etanol e água utilizando o trans-1,2-bis(4-piridil)eteno (bpe) como ligante. Os compostos formados são cristalinos e estáveis ao ar. / This work presents a brief description about the basic concepts of X-ray crystallography and the experimental part contains the crystal and molecular structure determination of coordination compounds with copper , by X-ray diffraction. Catena-tri-µ-chloro-µ-[trans-1,2-bis(4-pyridyl)ethene]copper(I): monoclínic system, space group P21/c; a=3.7819(1); b=15.0582(9); c=10.8742(6) Å; B=96.284(4) º; Z=4; V=615.55(5) Å3; Dc=2.040 Mg.m-3. The final disagreement indices are: Robs=0.0465; Rall=0.1367; GOF=1.13 to 1243 observed reflections (I>2Sigma(I)) and NPAR=83. µ-oxalate-µ-[trans-1,2-bis(pyridyl)ethene]copper(II): triclinic system, space group P ; a=8.7948(5); b=9.228(5); c=5.5172(3) Å; Alfa =108.860(3), Beta =109.895(3), Gama=97.572(3) º; Z=2; V=374.92(4) Å3; Dc=1.469 Mg.m-3. The final disagreement indices are: Robs=0.0567; Rall=0.1544; GOF=1.08 to 1694 observed reflections (I>2Sigma(I)) and NPAR=97. These complexes are products in the reaction with potassium oxalate and copper(II) chloride dihydrate. The synthesis was made in presence of ethanol and water, using the trans-1, 2-bis(4-pyridyl)ethene (bpe) as ligand. The obtained compounds they are crystalline and the stable.

Este trabalho apresenta uma parte introdutória que descreve os conceitos básicos da determinação de estruturas cristalinas e, na parte experimental, a determinação da estrutura cristalina e molecular, por difração de raios-X, de dois compostos de coordenação contendo cobre: catena-tri-µ-cloro-µ-[trans-1,2-bis(4-piridil)eteno]cobre(I): Sistema cristalino monoclínico; grupo espacial P21/c; a=3,7819(1); b=15,0582(9); c=10,8742(6) Å; B=96,284(4)º; Z= 4 moléculas por cela unitária; V=615,55(5) Å3; Dc=2,040 Mg.m-3. Os índices de discordância finais são: Robs=0,0465 ; Rall=0,1367 com GOF=1,13 para 1243 reflexões observadas (I>2Sigma(I)) e 83 parâmetros refinados. µ-oxalato-µ-[trans-1,2-bis(piridil)eteno]cobre(II): Sistema cristalino triclínico; grupo espacial P ; a=8,7948(5); b=9,0228(5); c=5,5172(3) Å; Alfa=108,860(3), Beta=109,895(3), Gama=97,572(3)º; Z= 2 moléculas por cela unitária; V=374,92(4) Å3; Dc=1,469 Mg.m-3. Os índices de discordância finais são: Robs=0,0567, Rall=0,1544 com GOF=1,08 para 1694 reflexões observadas (I>2Sigma(I)) e 97 parâmetros refinados. Estes complexos são produtos da reação entre oxalato de potássio e cloreto de cobre(II) dihidratado. A síntese foi feita na presença de etanol e água utilizando o trans-1,2-bis(4-piridil)eteno (bpe) como ligante. Os compostos formados são cristalinos e estáveis ao ar. / This work presents a brief description about the basic concepts of X-ray crystallography and the experimental part contains the crystal and molecular structure determination of coordination compounds with copper , by X-ray diffraction. Catena-tri-µ-chloro-µ-[trans-1,2-bis(4-pyridyl)ethene]copper(I): monoclínic system, space group P21/c; a=3.7819(1); b=15.0582(9); c=10.8742(6) Å; B=96.284(4) º; Z=4; V=615.55(5) Å3; Dc=2.040 Mg.m-3. The final disagreement indices are: Robs=0.0465; Rall=0.1367; GOF=1.13 to 1243 observed reflections (I>2Sigma(I)) and NPAR=83. µ-oxalate-µ-[trans-1,2-bis(pyridyl)ethene]copper(II): triclinic system, space group P ; a=8.7948(5); b=9.228(5); c=5.5172(3) Å; Alfa =108.860(3), Beta =109.895(3), Gama=97.572(3) º; Z=2; V=374.92(4) Å3; Dc=1.469 Mg.m-3. The final disagreement indices are: Robs=0.0567; Rall=0.1544; GOF=1.08 to 1694 observed reflections (I>2Sigma(I)) and NPAR=97. These complexes are products in the reaction with potassium oxalate and copper(II) chloride dihydrate. The synthesis was made in presence of ethanol and water, using the trans-1, 2-bis(4-pyridyl)ethene (bpe) as ligand. The obtained compounds they are crystalline and the stable.

Plusieurs études ont rapporté l’influence de la pression d’hydrogène, plus précisément la concentration réelle en hydrogène dissous dans le milieu réactionnel, sur l’énantiosélectivité des réactions d’hydrogénations catalytiques intervenant des catalyseurs à base de rhodium. Cependant, l’identification de l’étape ou les étapes enantiodéterminantes ou limitantes ainsi que l’explication de l’effet de la pression d’hydrogène sur cet étape, exigent la détermination des constantes cinétiques de chaque étape élémentaire. Ce projet de recherche vise une telle détermination en combinant deux études expérimentale et théorique. Dans un premier temps, un système catalytique présentant deux effets opposés de la pression de l’hydrogène en fonction de la nature du substrat, a été identifié : un effet néfaste avec le M-acrylate (MAA) et un effet bénéfique avec l’E-emap. Ensuite, deux études ont été menées sur les réactions d’hydrogénation de ces deux substrats par le Rh(I) /(R,R)-Me-BPE. L’étude cinétique expérimentale est basée sur le modèle cinétique proposé par Halpern dans le but d’estimer les paramètres cinétiques des différentes étapes élémentaires, alors que celle théorique consiste à étudier les différents chemins réactionnels possibles par calcul DFT en utilisant le logiciel de modélisation Gaussian 03. L’exploitation des résultats obtenus a permis de revisiter les concepts clés de la catalyse d’hydrogénation asymétrique et de mener une discussion par rapport à la fiabilité des méthodes théoriques à prévoir l’expérience. / Several studies brought back the influence of the hydrogen pressure, more precisely the real hydrogen concentration dissolved in solution, on the enantioselectivity of the catalytic asymmetric hydrogenation for rhodium based catalysts. However to identify the enantiodetermining step(s), and to gain some further understanding on the hydrogen pressure-enantioselectivity relationship, the determination of the kinetic constants is required. We have thus embarked a project aiming such determination by coupling experimental work and theoretical chemistry. Two studies were undertaken on the asymmetric hydrogenation of both substrates by the Rh (I)/ (R,R)-Me-bpe catalyst. The experimental kinetic work study is based on the kinetic model suggested by Halpern in order to estimate the parameters kinetic of each elementary step, whereas that theoretical, consists in studying the various possible pathways by DFT calculation using the software of modelling Gaussian 03. The analysis of the obtained results made it possible to revisit the concepts’ key of the catalytic asymmetric hydrogenation and to hold a discussion about the reliability of the theoretical methods to envisage the experiment.

Plusieurs études ont rapporté l'influence de la pression d'hydrogène, plus précisément la concentration réelle en hydrogène dissous dans le milieu réactionnel, sur l'énantiosélectivité des réactions d'hydrogénations catalytiques intervenant des catalyseurs à base de rhodium. Cependant, l'identification de l'étape ou les étapes enantiodéterminantes ou limitantes ainsi que l'explication de l'effet de la pression d'hydrogène sur cet étape, exigent la détermination des constantes cinétiques de chaque étape élémentaire. Ce projet de recherche vise une telle détermination en combinant deux études expérimentale et théorique. Dans un premier temps, un système catalytique présentant deux effets opposés de la pression de l'hydrogène en fonction de la nature du substrat, a été identifié : un effet néfaste avec le M-acrylate (MAA) et un effet bénéfique avec l'E-emap. Ensuite, deux études ont été menées sur les réactions d'hydrogénation de ces deux substrats par le Rh(I) /(R,R)-Me-BPE. L'étude cinétique expérimentale est basée sur le modèle cinétique proposé par Halpern dans le but d'estimer les paramètres cinétiques des différentes étapes élémentaires, alors que celle théorique consiste à étudier les différents chemins réactionnels possibles par calcul DFT en utilisant le logiciel de modélisation Gaussian 03. L'exploitation des résultats obtenus a permis de revisiter les concepts clés de la catalyse d'hydrogénation asymétrique et de mener une discussion par rapport à la fiabilité des méthodes théoriques à prévoir l'expérience.

In order to achieve state-of-the-art performance for part-of-speech(POS) tagging, the traditional systems require a significant amount of hand-crafted features and data pre-processing. In this thesis, we present a discriminative word embedding, character embedding and byte pair encoding (BPE) hybrid neural network architecture to implement a true end-to-end system without feature engineering and data pre-processing. The neural network architecture is a combination of bidirectional LSTM, CNNs, and CRF, which can achieve a state-of-the-art performance for a wide range of sequence labeling tasks. We evaluate our model on Universal Dependencies (UD) dataset for English, Spanish, and German POS tagging. It outperforms other models with 95.1%, 98.15%, and 93.43% accuracy on testing datasets respectively. Moreover, the largest improvements of our model appear on out-of-vocabulary corpora for Spanish and German. According to statistical significance testing, the improvements of English on testing and out-of-vocabulary corpora are not statistically significant. However, the improvements of the other more morphological languages are statistically significant on their corresponding corpora.

This bachelor's thesis in Computer Science explores the efficiency of an incremental re-tokenization algorithm in the context of BPE-trained SentencePiece models used in natural language processing. The thesis begins by underscoring the critical role of tokenization in NLP, particularly highlighting the complexities introduced by modifications in tokenized text. It then presents an incremental re-tokenization algorithm, detailing its development and evaluating its performance against a full text re-tokenization. Experimental results demonstrate that this incremental approach is more time-efficient than full re-tokenization, especially evident in large text datasets. This efficiency is attributed to the algorithm's localized re-tokenization strategy, which limits processing to text areas around modifications. The research concludes by suggesting that incremental re-tokenization could significantly enhance the responsiveness and resource efficiency of text-based applications, such as chatbots and virtual assistants. Future work may focus on predictive models to anticipate the impact of text changes on token stability and optimizing the algorithm for different text contexts.