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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.
31

Análise das características estruturais do FAD em oxidorredutases

Silva, Rui Filipe Nogueira da 11 August 2015 (has links)
Submitted by Alison Vanceto (alison-vanceto@hotmail.com) on 2016-10-05T14:03:37Z No. of bitstreams: 1 DissRFNS.pdf: 7648197 bytes, checksum: 76ec1475a7603115854bee2c6dc347a5 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-10-05T18:42:34Z (GMT) No. of bitstreams: 1 DissRFNS.pdf: 7648197 bytes, checksum: 76ec1475a7603115854bee2c6dc347a5 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-10-05T18:42:42Z (GMT) No. of bitstreams: 1 DissRFNS.pdf: 7648197 bytes, checksum: 76ec1475a7603115854bee2c6dc347a5 (MD5) / Made available in DSpace on 2016-10-05T19:07:51Z (GMT). No. of bitstreams: 1 DissRFNS.pdf: 7648197 bytes, checksum: 76ec1475a7603115854bee2c6dc347a5 (MD5) Previous issue date: 2015-08-11 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / In this work, oxidoreductases of the glutathione reductase (GR), trypanothione reductase (TR) and sulfhydryl oxidase (SOX) sub-subclasses that are FAD (flavin adenine dinucleotide) dependent enzymes and contain a group with sulfur as a charge acceptor/donor near the FAD isoalloxazine region were studied. Oxidoreductases are enzymes capable of catalyzing redox reactions, thus requiring donor groups and acceptor groups of charges. FAD is a cofactor of the oxidoreductases and participates in the enzymatic catalysis, brokering the transfer of charges between ligands and the polypeptide chain of the proteins. The thiol groups and disulfide bonds existing in the enzymes are, in many instances, involved in these transfer of protons and electrons together with the FAD. The conformation of the isoalloxazine region of the FAD and the π interactions between the sulfur atoms and the flavin region were studied. The crystal structures of 180 oxidoreductases with FAD and disulfide bonds retrieved from the Protein Data Bank (PDB) were analyzed, which allowed to set up some relationships between the bond lengths of the disulfide bridge in proteins and in small molecules, to determine the existence of deformations of the isoalloxazine moiety of the FAD, to measure the SG-π interaction distances and realize some FAD features that help differentiate the GR, TR and SOX sub-subclasses. / Neste trabalho foram estudadas oxidorredutases das sub-subclasses glutationa redutases (GR), tripanotiona redutases (TR) e sulfidril oxidases (SOX) que são enzimas dependentes de FAD (flavina adenina dinucleotídeo) e contêm um grupo com enxofre como aceitador/doador de cargas, próximo à região isoaloxazina do FAD. As oxidorredutases são enzimas capazes de catalisar reações redox, necessitando, para tal, de grupos doadores e grupos aceitadores de cargas. O FAD é um cofator das oxidorredutases e participa na catálise enzimática, intermediando a transferência de cargas entre ligantes e a cadeia polipeptídica das proteínas. Os grupos tiol e as ligações dissulfeto existentes nas enzimas estão, em muitos casos, envolvidos nessas transferências de prótons e elétrons em conjunto com o FAD. Foi realizado o estudo da conformação da região isoaloxazina do FAD e de interações π entre os átomos de enxofre e a flavina do FAD. Foram analisadas 180 estruturas cristalográficas de oxidorredutases com FAD e ligações dissulfeto obtidas do Protein Data Bank (PDB) o que permitiu relacionar os comprimentos da ligação dissulfeto em proteínas e em pequenas moléculas, classificar deformações da isoaloxazina do FAD, determinar distâncias de interação SG-π e perceber caraterísticas do FAD que permitem diferenciar as sub-subclasses de GR, TR e SOX. / CNPq: 166636/2013-4
32

Modular Scaled Development Platform for Steering Algorithms using LEGO Mindstorms. / Modulär Skalbar Utvecklingsplattform för Styralgoritmer baserad på LEGO Mindstorms.

YANG, GEPENG, ADOLFSSON, JONATHAN January 2019 (has links)
The topic of the thesis is to build physically similar systems to simulate behaviors of real-life heavy-duty vehicles using LEGO Mindstorms as hardware platform and Buckingham π theorem as theoretical basis for the parameter scaling. The thesis work includes software and hardware system design and theoretical research in order to prove a newly proposed concept: Using LEGO to build a scaled model of real-life vehicles with specific similar physical properties. To implement the work described above, scaled models were built with LEGO and a software and hardware system was developed for controlling the scaled model. Tests were performed both on real-life vehicles and scaled models. A generalized mathematical model for the vehicle was derived in order to interpret the behaviors of the vehicle in a scientific way. Then, test results of both real-life vehicles and the corresponding scaled model were compared with the mathematical model in order to investigate if they have similar behaviors. Finally it was concluded that the scaled model built with LEGO Mindstorms combined with Buckingham π theorem could calculate the speed and turning radius of the physically similar real-life vehicle with an average accuracy of 94.68% within low speed, conservatively speaking. For further investigation and research, similar research could be performed with higher speeds to generalize the conclusions and results. / Uppsatsen ämnar till att bygga ett fysiskt likvärdigt system, som simulerar beteendet av verkliga tunga fordon, med LEGO Mindstorms som hårdvaruplattform och med Buckingham П teoremet som teoretisk grund from skalning av parametrar. Arbetet inkluderar mjukvaru- och hårdvarusystemdesign samt teoretisk forskning för att kunna bevisa ett nyligen föreslaget koncept: Att använda LEGO för att bygga en skalad modell av verkliga fordon med specifika likartade fysiska egenskaper. För att implementera det ovan föreslagna arbetet, byggdes skalade modeller i LEGO samt ett kombinerat hård- och mjukvarusystem för att styra den skalade modellen. Tester utfördes på både riktiga lastbilar samt de skalade modellerna. För att kunna identifiera parametrar samt simulera och tyda fordonens beteende så adapterades en generell matematisk modell. Testresultaten för på verkliga samt motsvarande skalade modeller jämfördes med den matematiska modellen för att påvisa om beteendet är likartat. Till sist drogs slutsatsen att den skalade modellen bygg med LEGO Mindstorms och parameterskalad med hjälp av Buckingham П teoremet kunde beräkna skalningsfaktorn av hastighet samt svängradie för det fysiskt likartade fordonet med en tillförlitlighet på 94.68%, konservativt räknat. Detta gäller för låga hastigheter och som fortsatt forskning skulle en liknande studie med starkare och snabbare motorer genomföras för att generalisera slutsatserna och resultaten.
33

Crystal structures of monohydrate and methanol solvate compounds of {1-[(3,5-bis{[(4,6-dimethylpyridin-2-yl)amino]methyl}-2,4,6-triethylbenzyl)amino]cyclopentyl}methanol

Stapf, Manuel, Seichter, Wilhelm, Mazik, Monika 17 April 2024 (has links)
In the title monohydrate compound, 1a, and the methanol solvate compound, 1b, the tri­ethyl­benzene derivative, C35H51N5O, has three functionalized side arms and three ethyl groups, the former being located on one side of the central benzene ring, while the latter are directed to the opposite side. Both the crystals are constructed of structurally similar dimers of 1:1 host–guest complexes held together by N—H...O and O—H...N hydrogen bonds, and in 1a additionally by O—H...O hydrogen bonds. The structure of 1b contains additional highly disordered solvent mol­ecules. Thus, the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON was used to generate a modified data set, in which the contribution of the disordered mol­ecules to the structure amplitudes is eliminated. These solvent mol­ecules are not considered in the reported chemical formula.
34

Bluetooth Enhanced Data Rate Baseband Modeling and Implementation

Zou, Lei January 2006 (has links)
<p>The main issue of this thesis is making the behaviour model of Bluetooth EDR (enhanced data rate) baseband signal processing. This Bluetooth baseband project is part of the soft defined radio project at electrical engineering department, Linköping University.</p><p>In this project, both the basic rate and EDR model were built and simulated. The GFSK and π/4 DQPSK digital modulation and demodulation were implemented in C code. The BER was tested to evaluate the demodulation results. Furthermore, the error correction (FEC) and the error checking (HEC,CRC) were also implemented according to the Bluetooth standards. The CRC flag was detected to test the payload demodulation results.</p><p>Especially, GFSK and π/4 DQPSK specifications have to be combined with each other at sample rate of ADC.</p><p>Finally, the basic rate and EDR model were simulated to measure the BER and CRC performance.</p><p>From the simulation results, the receiver filter, synchronization and channel condition were three key points in this Bluetooth EDR system implementation.</p><p>So we get further understanding about the Bluetooth system specification and DSP implementation methods.</p>
35

Dérivés organométalliques d'hélicènes : modulation des propriétés chiroptiques

Emmanuel, Anger 05 October 2012 (has links) (PDF)
De nouveaux dérivés organométalliques d'hélicènes à base de platine et de ruthénium ont été préparés et leurs propriétés photophysiques ont été étudiées. Dans un premier chapitre bibliographique, nous nous sommes intéressés aux différents travaux réalisés depuis plus de 60 ans sur les hélicènes et leurs propriétés originales. Par la suite, les différentes applications dans lesquelles les hélicènes ont été étudiés sont décrites. Le deuxième chapitre est focalisé sur la description d'une nouvelle famille d'hélicènes, les platinahélicènes. Ces platinahélicènes ont la particularité d'être phosphorescents à température ambiante grâce à la présence du cycle orthoplatiné. La synthèse, les propriétés photophysiques et chiroptiques de cinq platinahélicènes sont reportées dans ce chapitre. Le troisième chapitre s'intéresse à l'évolution des propriétés photophysiques et chiroptiques lorsque l'on utilise la réactivité du platine. Des platinahélicènes de degrés d'oxydation différents ainsi que l'assemblage hétérochiral et homochiral de deux platinahélicènes sont reportés dans ce chapitre. L'isomérisation de l'assemblage hétérochiral en assemblage homochiral a été étudiée. Le quatrième chapitre traite de l'hydroruthénation d'hélicènes fonctionnalisés par une ou deux fonctions alcynes. Il en résulte la formation de ruthénium-vinyl-hélicènes. Ces complexes ont la particularité d'être électroactifs. La synthèse ainsi que l'étude des propriétés physiques, chiroptiques, électrochimiques et spectro-électrochimiques de ces complexes sont reportés dans ce chapitre. La fonction d'interrupteur moléculaire chiral de ces composés a aussi pu être mise en évidence.
36

Cosmological Results and Implications in Effective DGP

Chow, Lik-Neng Nathan January 2009 (has links)
We study a simple extension of the decoupling limit of boundary effctive actions for the Dvali-Gabadadze-Porrati model, by covariantizing the π lagrangian and coupling to gravity in the usual way. This extension agrees with DGP to leading order in Mpl^−1 , and simplifies the cosmological analysis. It is also shown to softly break the shift symmetry, while still being consistent with solar system observations. The generally covariant equations of motion for π and the metric are derived, then the cosmology is developed under the Cosmological Principle. Three analytic solutions are found and their stability is studied. Interesting DGP phenomenology is reproduced, and we consider one of the stable solutions. The cosmological analogue of the Vainshtein effect is reproduced and the effective equation of state, w_π, is shown to be bounded by −1 from above. This solution is additionally shown to be an attractor solution in an expanding universe. We evolve π numerically and reproduce these properties, and show that the universe will go through a contraction phase, due to this π field. We then place a constraint on r_c ≥ 10^29 cm, given recent WMAP5 data. This lower bound on r_c gives an upper bound on the anomalous perihelion precession of the moon ∼ 1 × 10^−13, 2 orders of magnitude below current experimental precision.
37

Cosmological Results and Implications in Effective DGP

Chow, Lik-Neng Nathan January 2009 (has links)
We study a simple extension of the decoupling limit of boundary effctive actions for the Dvali-Gabadadze-Porrati model, by covariantizing the π lagrangian and coupling to gravity in the usual way. This extension agrees with DGP to leading order in Mpl^−1 , and simplifies the cosmological analysis. It is also shown to softly break the shift symmetry, while still being consistent with solar system observations. The generally covariant equations of motion for π and the metric are derived, then the cosmology is developed under the Cosmological Principle. Three analytic solutions are found and their stability is studied. Interesting DGP phenomenology is reproduced, and we consider one of the stable solutions. The cosmological analogue of the Vainshtein effect is reproduced and the effective equation of state, w_π, is shown to be bounded by −1 from above. This solution is additionally shown to be an attractor solution in an expanding universe. We evolve π numerically and reproduce these properties, and show that the universe will go through a contraction phase, due to this π field. We then place a constraint on r_c ≥ 10^29 cm, given recent WMAP5 data. This lower bound on r_c gives an upper bound on the anomalous perihelion precession of the moon ∼ 1 × 10^−13, 2 orders of magnitude below current experimental precision.
38

Hétérométallocènes et espèces divalentes Nhétérocycliques du groupe 14 (Ge, Sn)

Mcheik, A. 12 January 2007 (has links) (PDF)
Ce travail concerne l'étude de nouvelles espèces divalentes du groupe 14 (germanium et étain). Il s'agissait de développer de nouvelles stratégies de stabilisation (structures de type ferrocène ou complexation intramoléculaire) et de contrôler la réactivité des centres des divalents.<br />Le premier chapitre porte sur l'étude des premiers hétérobimétallocènes comprenant un métal de transition et un élément du groupe 14 reliés par des cyclopentadiényles. Une étude physicochimique approfondie (RMN multi noyaux, 1H, 13C, 119Sn, spectrométrie de masse et étude structurale par diffraction des rayons X) a permis de mettre en évidence la structure p-liée coudée très particulière de ces métallocènes du groupe 14. Les premiers tests de réactivité (réaction avec des électrophiles, réaction par transfert monoélectronique) ont confirmé que l'introduction de groupement ferrocényle induisait non seulement une forte stabilisation mais également une réactivité particulière du métal 14 en facilitant le départ du ligand. Ces particularités pourraient en faire de bons précurseurs de nanoparticules de germanium ou d'étain.<br />Dans le deuxième chapitre, nous avons tenté la stabilisation des germylènes Nhétérocycliques qui sont les analogues des carbènes d'Arduengo par l'introduction d'un groupement ferrocényle soit directement sur l'atome d'azote soit par l'intermédiaire d'un groupement méthylène. Alors que les cycloadduits sont facilement obtenus à partir de dichlorures de germanium IV, seules les formes polymères ont été observées en série de métal 14 divalent.<br />Dans les troisième et quatrième chapitres, nous avons développé une extension de cette étude à des ligands offrant des possibilités de complexation intramoléculaire et de délocalisation électronique. Dans un premier temps, nous avons montré la stabilisation de germylène et stannylène par le ligand aminotroponate et pu accéder aux premiers digermylènes à ligand di-aminotroponate et di-aminotroponiminate pontés. Des effets stabilisants comparables ont été observés à partir des derniers ligands utilisés, les anilidoiminates.<br />Une étude physiscochimique et structurale approfondie de tous ces nouveaux composés a mis en évidence une parfaite délocalisation électronique sur les ligands ce qui laisse envisager une électrophilie accrue du métal 14 divalent. Cependant, ils conservent leur caractère divalent comme le montre leur réaction avec une ortho-quinone. Une réaction inédite d'échange avec la trichlorophosphine permet d'accéder aux dichlorophosphines correspondantes qui sont des précurseurs potentiels de phosphinidènes.
39

SOLUTION AND SOLID STATE INTERACTIONS BETWEEN IONIC π-SYSTEMS

Chen, Jing 01 January 2006 (has links)
Although attractive interactions between π systems (π-π interaction) have been known for many years, understanding of its origin is still incomplete. Quantitative measuring of π-stacking is challenging due to the weak nature of the π-π interaction. This dissertation aims at elucidating a quantitative conformational analysis by NMR ring current anisotropy of an organic compound capable of intramolecular π-stacking in solution and studying charge effects on the stacking of π-systems. This dissertation offers four contributions to the area. (1) A general approach to four-state, conformational analysis based on the magnetic anisotropy of molecules undergoing fast dynamic exchange is described. (2) Study unveiled the importance of charges in the conformation of a dication in the solution. (3) Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized and studied. (4) Study unveiled ionic π-systems preferred face-to-face stacking due to strong cation-π and anion-cation attractions. A general protocol for the application of magnetic anisotropy to quantitative multi-state conformational analysis of molecules undergoing fast conformational exchange was suggested in the current study. The reliability of this method of conformational analysis was checked by the mass balance. VT-NMR was also conducted to study the enthalpic parameters. This technique can be further used to study canonical interactions such as ion pairing, hydrogen boning, and molecular recognition. In the current study, dependence of the probe conformations on the dispersive interactions at the aromatic edges between solvent and probes was tested by conformational distributions of the fluorinated derivatives (2b and 2c) of the probe molecule (1a). Solution and solid studies of these molecules put the previous conclusion drawn by the Cammers group in question. Current studies show that the dispersive interaction at the aromatic edge could not be the predominant force on the conformational changes in the probe molecule 1a during the fluoroalkanol perturbation. This study indicated that charges might be important in the formation of the folding conformations in the solution and solid state of 1a, 2b, and 2c. A contribution of this thesis was to prepare and study a conformational model that lacked charges. The previous molecules were charged. The solid-state structures of pyridinium-derived aromatic rings from the CSD (Cambridge Structural Database) were studied to investigate the π-π interaction between cationic π-systems in solid state. Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized to study the π-π interaction between two aromatic rings that carried opposite charges. This study showed that the interaction between ionic π-systems can be enhanced by cation-π and anion-cation attractions. The stackings of these π-systems introduce more overlap, closer packing and stronger atomic contact than that of the solid states of comparable neutral species. Cation-π and anion-cation attractions are synergistic in aromatic salts.
40

Bluetooth Enhanced Data Rate Baseband Modeling and Implementation

Zou, Lei January 2006 (has links)
The main issue of this thesis is making the behaviour model of Bluetooth EDR (enhanced data rate) baseband signal processing. This Bluetooth baseband project is part of the soft defined radio project at electrical engineering department, Linköping University. In this project, both the basic rate and EDR model were built and simulated. The GFSK and π/4 DQPSK digital modulation and demodulation were implemented in C code. The BER was tested to evaluate the demodulation results. Furthermore, the error correction (FEC) and the error checking (HEC,CRC) were also implemented according to the Bluetooth standards. The CRC flag was detected to test the payload demodulation results. Especially, GFSK and π/4 DQPSK specifications have to be combined with each other at sample rate of ADC. Finally, the basic rate and EDR model were simulated to measure the BER and CRC performance. From the simulation results, the receiver filter, synchronization and channel condition were three key points in this Bluetooth EDR system implementation. So we get further understanding about the Bluetooth system specification and DSP implementation methods.

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