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This research project compares different chemical and spectroscopic techniques aimed at finding a quick and cheap replacement for the measurement of digestibility of phosphorus (P) in different inorganic feed additives for pigs. This research yielded a comparison of the digestibility of different feed additives. P digestibility was determined from in vivo studies of pigs. The animal feed in the in vivo studies contained P levels below the nutrient requirements. The basal diet was a corn soybean meal base. Assessment was performed on 6 different inorganic P sources, rock phosphate (tricalcium phosphate (TCP)), meat and bone meal (MBM), mono/dicalcium phosphate (MDCP) and three different dicalcium phosphates (DCPs). Eight pigs where selected and placed into separate pens. Two were given basal diets and the other 6 diets were randomly selected and supplied with the different inorganic P sources. P digestibility was calculated by difference. The apparent P digestibility of the sources were: TCP at 46 %, the MBM at 85 %, MDCP at 71 % and three DCPs ranged from 49 % to 73 %. This substantiated that the apparent P digestibility in the major inorganic sources of P is significantly less than 100%. The in vitro or chemical methods of assessing phosphorus availability in animal feed included the commonly used feed extraction methods of water solubility and 2 % citric acid. These two methods showed significant differences between each other. Other chemical methods used included calcium chloride, ammonium acetate, sodium bicarbonate extractions, and a double extraction using hydrochloric acid (HCl) followed by sodium bicarbonate. The chemical methods showed non-significant correlation coefficients when compared to in vivo P digestibility of the six phosphate ingredients used. Infra-red spectroscopy is now commonly used in feed production for many other nutritional tests. NIR, although being able to obtain an R2 above 0.999 for correlation curves and factor prediction curves, could not obtain a self prediction of the calcium phosphates due to the large Mahalanobis Distance. P digestibility predicted by MIR showed close agreement with the in vivo P digestibility. Again due to the small number of ingredients tested in the pig trial, the prediction of digestibility using MIR could only be compared to it self. Hence MIR can only be used as an estimate until more data can be obtained. The P31 SS-MAS-NMR indicated one of the DCPs was made up of 3 or more P compounds by displaying 3 major peaks. All the P chemical shifts from the faeces had different positions to the P peaks in the ingredients, indicating some sort of change in the P form. Overall the chemical methods were unable to predict P digestibility, and while the spectroscopic techniques showed promise, they still require more work to examine many more feed additives.Invitro, invivo, phosphorus, digestibility, swine, infra-red spectroscopy, solid state NMR

FERNANDES, César Rodrigues. Espectroscopias Raman e infravermelho em cristais de aminoácidos : os casos da L-valina e do ácido L-glutâmico. 2015. 264 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2015. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-04-09T21:07:04Z No. of bitstreams: 1 2015_tese_crfernandes.pdf: 8055322 bytes, checksum: 64f46f4716b7bda3f85f0cf3a7bab81d (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-04-10T20:43:31Z (GMT) No. of bitstreams: 1 2015_tese_crfernandes.pdf: 8055322 bytes, checksum: 64f46f4716b7bda3f85f0cf3a7bab81d (MD5) / Made available in DSpace on 2015-04-10T20:43:31Z (GMT). No. of bitstreams: 1 2015_tese_crfernandes.pdf: 8055322 bytes, checksum: 64f46f4716b7bda3f85f0cf3a7bab81d (MD5) Previous issue date: 2015 / Estudar o comportamento dos aminoácidos quando sujeitos a condições extremas de temperatura é o objetivo principal dessa tese. Na L-valina (C_5 H_11 NO_2) foram realizados experimentos de absorção infravermelha, enquanto que experimentos de espalhamento Raman foram realizados nas fases α e β do ácido L-glutâmico (C_5 H_9 NO_4). Para a L-valina, o experimento de infravermelho foi realizado em duas regiões espectrais: na primeira o intervalo analisado foi de ~10 a ~700 cm-1 (englobando a região do infravermelho distante – FAR-IR); na segunda, o intervalo analisado foi de 370 a 4000 cm-1 (englobando a região conhecida como infravermelho médio: MID-IR). Nos experimentos Raman no ácido L-glutâmico, o intervalo espectral entre ~15 e ~4000 cm-1 foi estudado. Nos experimentos de infravermelho, o parâmetro termodinâmico temperatura assumiu valores de 100 K até 300 K espaçados por 20 K. Nos experimentos Raman conseguiu-se um espaçamento de 50 K com a temperatura variando de 18 a 300 K, tanto para a fase α como para a fase β. Na fase β, diversas geometrias de espalhamento foram utilizadas, enquanto que para a fase α somente uma geometria de espalhamento foi analisada. Da análise dos espectros da L-valina foram observados surgimentos e desaparecimentos de modos na região do infravermelho distante (FAR-IR). Um modo de rede localizado em 103 cm^(-1), desdobra-se em dois modos de maneira rápida, e diferente do que seria esperado pela evolução espectral ω x T. Situação inversa, ocorre quando dois modos colapsam em 163 cm^(-1) e, interessantemente, à mesma temperatura que no desdobramento: ~120K. Nas mesmas condições outros dois modos, em ~211 cm^(-1) e em ~216 cm^(-1) se reduzem a um único modo em ~214 cm^(-1). Um pico em ~190 cm-1 desaparece no intervalo 100-120 K. Nesse intervalo também podemos verificar grandes desvios da linearidade das frequências dos modos em 147 cm^(-1), 196 cm^(-1), 225 cm^(-1) e 305 cm^(-1). Mais ainda, os modos vibracionais em 154cm^(-1) e 214 cm^(-1) apresentam descontinuidade (nesse caso, verificadas entre 120 e 160 K). Isso sugere não se tratar de simples mudanças conformacionais, posto que tais ocorrências (desdobramentos, desaparecimentos e fortes não linearidades dos modos) se dão num intervalo particular de temperatura. Pode-se concluir daí que o cristal sofre uma transição de fase estrutural a partir de 120 K, se completando a 100 K. Observe-se que para a região MID, a L-valina não apresenta alterações espectrais significativas: as frequências dos modos no geral são lineares, constantes e sem descontinuidades. As medidas Raman na forma β do ácido L-glutâmico resultaram num número constante de modos de vibração na região dos modos da rede durante todo o resfriamento, o que foi interpretado como estabilidade do material. Entretanto, houve colapso (eg.:~500 cm-1, 200 K, Z(XX)Z; três bandas tornaram-se duas) e surgimento (eg.: ~930 cm-1, 120 K, Z(XX)Z; uma banda torna-se duas) de bandas em outras regiões do espectro. Tais ocorrências foram interpretadas como alteração do ambiente da molécula (~930 cm-1), efeito de “aliasing” dificultando o ajuste por lorentzianas (eg.: ~1070 cm-1), e mudança de conformação. Por não estarem associados a levantamentos nem incrementos de degenerescência, tais comportamentos sugerem estabilidade do ácido L-glutâmico na forma β. Os espectros Raman obtidos para a fase α do ácido L-glutâmico se apresentaram completamente regulares: modos lineares, sem descontinuidades nas frequências nem mudança no número de modos. A partir de todos os resultados obtidos, procurou-se entender que fatores determinam a estabilidade de um cristal de aminoácido. A análise do comportamento desta família de materiais mostra três “níveis” de estabilidade (i) estáveis (e.g.: ácido L-glutâmico e L-isoleucina), (ii) microtransições conformacionais (complexo comportamento vibracional, e.g.: L-alanina) e (iii) cristais que sofrem transição de fase estrutural (e.g.: L-valina e L-leucina). Fatores como ordenamento de cadeias laterais, forças de van der Waals e comprimento médio das ligações de hidrogênio (d ̅_LH) podem influenciar na estabilidade destas estruturas cristalinas. Entretanto, observando somente os comprimentos médios das ligações de hidrogênio (d ̅_LH) foi possível inferir uma relação entre esse valor e a estabilidade: L-valina e taurina sofrem transição (〖d ̅_LH〗_(L-val)=2.92 Å, 〖d ̅_LH〗_tau=2.90 Å), L-alanina ⇒ micro-transição conformacional (〖d ̅_LH〗_(L-ala)=2.83 Å) e ácido L-glutâmico estável (〖d ̅_LH〗_(L-glu(α))=2.771 Å, 〖d ̅_LH〗_(L-glu(β))=2.798 Å). Nota-se que: 〖d ̅_LH〗_(L-glu(α,β))<〖d ̅_LH〗_(L-ala)<〖d ̅_LH〗_(L-val),〖d ̅_LH〗_tau. A L-treonina constitui exceção, pois é estável embora possua 〖d ̅_LH〗_(L-treo)=2.86 Å. Outras técnicas experimentais (e.g.: difração e espalhamento de nêutrons) são sugeridas para serem utilizadas futuramente na abordagem deste problema.

Made available in DSpace on 2014-06-11T19:25:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-05-22Bitstream added on 2014-06-13T19:12:25Z : No. of bitstreams: 1 menegazzo_lm_me_ilha.pdf: 652340 bytes, checksum: 7cd3c65c7db0577bbe66236ac50269ff (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho propõe o estudo do grau de conversão e de dureza de três resinas fotoativadas Fill Magic, TPH Spectrum e Te-Econom, em função do tempo de exposição e do tipo de fonte de luz. Foram utilizadas quatro fontes diferentes, sendo duas halógenas e duas baseadas em LED. O grau de conversão foi avaliado de espectros de absorção no infravermelho próximo e a dureza através de testes Vickers. Cinco amostras de 10 mm de diâmetro e 2 mm de espessura foram preparadas para cada tempo de exposição e tipo de fonte. Após exposição à luz, todas as amostras foram mantidas durante 7 dias em ambiente escuro antes de serem utilizadas para obtenção de espectros e serem submetidas ao teste de dureza. Os espectros foram obtidos em um espectrômetro Nexus 670 da Nicolet e a microdureza Vickers foi obtida com um microdurômetro HMV - 2T da Shimadzu. Os resultados mostraram que o grau de conversão aumenta com o tempo de exposição para fontes com densidade de potência menor que 233 mW/cm2. Não foi observada diferença significativa no grau de conversão nas amostras irradiadas com fontes halógena e LED, ambas com densidade de potência maior que 233 mW/cm2. Não foi possível estabelecer uma relação entre dureza e o tempo de exposição ou a densidade de potência. Entre as resinas, a FM é a que apresentou melhores valores de grau de conversão e a Te-Econom de dureza. / The aim of this study was to evaluate the degree of conversion and hardness of three photo-activated composites (Fill Magic, TPH Spectrum and Te-Econom) as a function of exposure time and type of light source. As visible light source were utilized four different units, two halogen and two light-emitting diodes (LED). The conversion degree was evaluated by near-infrared spectroscopy and the hardness by Vickers tests. Five samples of 10 mm diameter and 2 mm thickness were prepared for each exposure time and light source. The spectra were obtained in a Nexus 670 Nicolet spectrometer and the hardness in a HMV - 2T micro hardness tester (Shimadzu). These measurements were performed after 7 days dark storage. The results showed that the degree of conversion increases with the exposure time for the light units with power density smaller than 233 mW/cm2. No significant differences were observed in degree of conversion in samples irradiated with halogen and LED units, both with power density larger than 233 mW/cm2. There is not correlation between the conversion degree and the micro hardness for all studied composites. The highest values for conversion degree and hardness were obtained with the Fill Magic and Te-Econom composites, respectively.

Orientador: João Carlos Silos Moraes / Banca: Marco Antonio Utrera Martines / Banca: Paulo Henrique dos Santos / Resumo: Este trabalho propõe o estudo do grau de conversão e de dureza de três resinas fotoativadas Fill Magic, TPH Spectrum e Te-Econom, em função do tempo de exposição e do tipo de fonte de luz. Foram utilizadas quatro fontes diferentes, sendo duas halógenas e duas baseadas em LED. O grau de conversão foi avaliado de espectros de absorção no infravermelho próximo e a dureza através de testes Vickers. Cinco amostras de 10 mm de diâmetro e 2 mm de espessura foram preparadas para cada tempo de exposição e tipo de fonte. Após exposição à luz, todas as amostras foram mantidas durante 7 dias em ambiente escuro antes de serem utilizadas para obtenção de espectros e serem submetidas ao teste de dureza. Os espectros foram obtidos em um espectrômetro Nexus 670 da Nicolet e a microdureza Vickers foi obtida com um microdurômetro HMV - 2T da Shimadzu. Os resultados mostraram que o grau de conversão aumenta com o tempo de exposição para fontes com densidade de potência menor que 233 mW/cm2. Não foi observada diferença significativa no grau de conversão nas amostras irradiadas com fontes halógena e LED, ambas com densidade de potência maior que 233 mW/cm2. Não foi possível estabelecer uma relação entre dureza e o tempo de exposição ou a densidade de potência. Entre as resinas, a FM é a que apresentou melhores valores de grau de conversão e a Te-Econom de dureza. / Abstract: The aim of this study was to evaluate the degree of conversion and hardness of three photo-activated composites (Fill Magic, TPH Spectrum and Te-Econom) as a function of exposure time and type of light source. As visible light source were utilized four different units, two halogen and two light-emitting diodes (LED). The conversion degree was evaluated by near-infrared spectroscopy and the hardness by Vickers tests. Five samples of 10 mm diameter and 2 mm thickness were prepared for each exposure time and light source. The spectra were obtained in a Nexus 670 Nicolet spectrometer and the hardness in a HMV - 2T micro hardness tester (Shimadzu). These measurements were performed after 7 days dark storage. The results showed that the degree of conversion increases with the exposure time for the light units with power density smaller than 233 mW/cm2. No significant differences were observed in degree of conversion in samples irradiated with halogen and LED units, both with power density larger than 233 mW/cm2. There is not correlation between the conversion degree and the micro hardness for all studied composites. The highest values for conversion degree and hardness were obtained with the Fill Magic and Te-Econom composites, respectively. / Mestre

Implication de l’oxygénation cérébrale dans les limitations à l’exercice musculaire des personnes non-entraînées et sportifs d’endurance. L’objectif général de ce travail était de déterminer si l’oxygénation cérébrale était un facteur de la limitation à l’exercice de type aérobie. Dans un premier temps, nous nous sommes attachés à étudier le rôle de l’oxygénation cérébrale mesurée par la Spectroscopie dans le proche Infra-Rouge (NIRS) dans la limitation de l’exercice progressif maximal en rampe. Nous avons montré l’existence d’un seuil de déclin de l’oxygénation cérébrale associé au point de compensation respiratoire (RCP). L’amélioration de la performance avec une supplémentation d’O2 était liée au décalage de ce seuil à de plus hautes intensités d’exercice chez des sujets actifs (étude 1). Dans un second temps, nous avons montré que ce seuil de déclin de l’oxygénation, retrouvé aussi chez des sportifs entraînés en endurance apparaîssait à de plus hautes intensités d’exercice que chez des sujets non-entraînés (étude 2). Enfin, nous avons déterminé l’impact de l’hypoxémie artérielle induite par l’exercice (HIE) des sportifs d’endurance sur l’oxygénation cérébrale au cours d’un exercice maximal en rampe et d’un exercice de temps limite à charge constante. Nous avons ainsi montré que l’oxygénation cérébrale était augmentée avec la HIE suggérant un effet compensatoire à l’hypoxémie artérielle au cours de l’exercice progressif maximal en rampe. Ceci, n’existait pas au cours de l’exercice de temps limite ne supportant pas l’implication de l’oxygénation cérébrale dans ce type d’exercice (étude 3). Ces travaux ont donc mis en évidence l’implication de l’oxygénation cérébrale dans la limitation de l’exercice maximal en rampe chez des sujets actifs et des sportifs entraînés en endurance présentant ou pas une HIE. Toutefois, elle ne semble pas être un facteur majeur de limitation de l’exercice de temps limite. / Involvement of cerebral oxygenation in muscular exercice limitation in untrained and trained endurance men. A decrease in oxygen availability in the brain could be a physiological mechanism limiting aerobic fitness. We first studied the role of cerebral oxygenation measured by Near Infra-Red Spectroscopy (NIRS ) in maximal cycle ramp exercise limitation. We showed a cerebral oxygenation threshold decline associated with respiratory compensation point (RCP). This threshold appeared for higher exercise intensities -related to performance improvement with hyperoxia in untrained endurance men (study 1). Secondly , we showed that the cerebral oxygenation threshold in athletes occurred for higher sub-maximal exercise intensities than untrained (study 2). Finally , we determined the involvement of exercise-induced arterial hypoxemia (EIH) in endurance athletes on cerebral oxygenation during maximal cycle ramp exercice and exercice time to exhaustion. We showed that cerebral oxygenation was improved by EIH suggesting a compensatory effect of EIH during the maximal cycle ramp. This did not occur during exercise time to exhaustion, and does not support the involvment of cerebral oxygenation in this type of exercise (study 3). This work has therefore highlighted the involvement of cerebral oxygenation in maximal cycle ramp exercice limitation in untrained and trained endurance men with or without EIH. However, it was unlikely been the major factor limiting the exercise time to exhaustion.

Thesis (PhD(Agric) (Horticulture))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Plums with good taste, aroma and eating quality lead to repeat purchases and sustained demand. Taste includes non-volatile compounds, e.g. sugars and acids, and has been well researched to meet the consumers’ preferences. Plum aroma, however, has not enjoyed the same attention. Limited literature is available on the aroma of Japanese plums and none could be found on the effects of relatively long cold storage on the profiles. The main aim of this study is to investigate the changes in aroma compounds of Japanese plums throughout maturation and ripening and the effects of commercial cold storage regimes. Near infra-red (NIR) spectroscopy was also evaluated as a non-destructive method to determine plum quality parameters aimed at minimising sample variability. In Paper 1, NIR spectroscopy was used to develop prediction models for total soluble solid (TSS), total acidity (TA), sugar-to-acid ratio, firmness and weight in three cultivars (Pioneer, Laetitia and Angeleno) and a multi-cultivar model. Samples were collected for seven consecutive weeks and repeated over two seasons. TSS results showed excellent predictability (R2 = 0.817-0.955; RMSEP= 0.453-0.610 % Brix) but the TA models did not perform well. The sugar-to-acid ratio models had results comparable to that of TSS. Both the firmness and weight models had acceptable results. The models of ‘Pioneer’ and ‘Laetitia’ had a better predictability capacity than the ‘Angeleno’ model. Although the multi-cultivar models outperformed the single cultivar models on R2 values it had higher prediction errors. The robustness of all the TSS, TA and firmness models is high in terms of seasonality, range and cultivar. Papers 2 and 3, the main focus of the study, are concerned with the aroma profile dynamics of Japanese plums. HS-SPME was used in both papers to extract the aroma compounds followed by GC-TOFMS for separation and identification. In Paper 2, the aroma volatile compounds of three cultivars (Pioneer, Laetitia and Angeleno) were determined for a seven week period including samples from three maturity stages (immature, harvest and tree-ripe). A total of 35 compounds were identified of which ten were generic. Each cultivar had five unique compounds resulting in different aroma profiles for each of the maturity stages and distinct separation patterns using discriminant analysis. The study was extended in Paper 3 where the aroma volatile compounds of six cultivars (Pioneer, Sapphire, Laetitia, Songold, Larry Anne and Angeleno) and one plumcot (Flavor King) were determined at three functional stages (commercial harvest, tree-ripe fruit and cold stored fruit). A total of 62 compounds were identified and classified into three groups (‘unique’ (31), ‘generic’ (11) and ‘frequent’ (20)) based on their frequency of occurrence. The aroma profiles of ‘Larry Anne’ and ‘Flavor King’ are the most affected by cold storage conditions and ‘Pioneer’ appears to be the least affected. All the cultivars have significantly different aroma profiles at all three of the functional stages with ‘Sapphire’, ‘Larry Anne’ and ‘Flavor King’ showing the largest differences. ‘Flavor King’, a plumcot, presented a ripe aroma profile that was much diverged from that of the true plums. / AFRIKAANSE OPSOMMING: Pruime met ‘n goeie smaak, aroma en eetkwaliteit lei tot herhaalde verkope en volhoubare aanvraag. Smaak sluit die nie-vlugtige stowwe (suikers en sure) in en is goed nagevors om die verbruikersvoorkeure te bevredig. Pruim aroma het egter nie dieselfde aandag geniet nie. Daar is beperkte literatuur beskikbaar wat handel oor die aroma van Japanese pruime en geen kon gevind word oor die effekte van lang koelopberging op die aromaprofiele nie. Die hoof doel van hierdie studie is om die veranderinge in die aromatiese komponente van Japanese pruime te ondersoek tydens die volwassewording- en rypwordingsprosesse asook die effekte van kommersiele koelopberging. Naby infrarooi (NIR) spektroskopie is ook geevalueer as ‘n nie-destruktiewe manier om pruim kwaliteitsparameters te bepaal met die doel om monstervariasie te beperk. In Artikel 1 is NIR spektroskopie gebruik om voorspellingsmodelle vir totale oplosbare suikers (TOS), totale suur (TS), suiker-tot-suur verhouding, fermheid en gewig te bepaal in drie kultivars (Pioneer, Laetitia en Angeleno) asook ‘n multi-kultivar model. Monsters is vir sewe opeenvolgende weke versamel en herhaal oor twee seisoene. TOS resultate toon uitstekende voorspelbaarheid (R2 = 0.817-0.955; RMSEP= 0.453-0.610 % Brix) maar TS modelle het egter nie so goed gevaar nie. Die suiker-tot-suur verhoudingsmodelle se resultate was vergelykbaar met die van TOS. Beide die fermheid- en gewigsmodelle het aanvaarbare resultate opgelewer. Die modelle vir ‘Pioneer’ en ‘Laetitia’ het ‘n beter voorspelbaarheidskapasiteit getoon as die van ‘Angeleno’. Alhoewel die multi-kultivar model beter presteer het as die enkel kultivar modelle op die R2-waardes was daar meer voorspellingsfoute. Hoe robuustheid is gevind i.t.v. seisoene, datagrense en kultivar vir al die TOS, TA en fermheidsmodelle. Artikels 2 en 3, die fokuspunt van die studie, handel oor die dinamika van die aromaprofiel van Japanese pruime. HS-SPME is in beide artikels gebruik on die aromatiese verbindings te ekstraeer gevolg deur GCTOFMS vir skeiding en identifikasie. In Artikel 2 is die aromatiese stowwe van drie kultivars (Pioneer, Laetitia en Angeleno) bepaal vir sewe opeenvolgende weke en sluit monsters van drie volwassenheidsstadiums in (onvolwasse, oes en boom-rypgemaakte pruime). ‘n Totaal van 35 verbindings is geidentifiseer waarvan tien as generies beskou kan word. Elke kultivar het vyf unieke komponente gehad en het gelei tot verskillende aromaprofiele vir elk van die volwassenheidsstadiums en diverse skeidingspatrone tydens die gebruik van diskriminant analise. Die studie is uitgebrei in Artikel 3 waartydens die aromatiese vlugtige stowwe van ses kultivars (Pioneer, Sapphire, Laetitia, Songold, Larry Anne en Angeleno) en een plumcot (Flavor King) bepaal is tydens drie funksionele stadiums (oes, boom-rypgemaak en koelopgebergde pruime). ‘n Totaal van 62 verbindings is geidentifiseer en in drie groepe geklassifiseer (‘uniek’ (31), ‘generies’(11) en ‘gereeld’ (20)) gebaseer op voorkomsfrekwensie. Die aromaprofiele van ‘Larry Anne’ en ‘Flavor King’ is die meeste deur die koelopberging geaffekteer en ‘Pioneer’ die minste. Al die kultivars het kenmerkend verskil t.o.v. hul aromaprofiele in al drie die funksionele groepe en ‘Sapphire’, ‘Larry Anne’ en ‘Flavor King’ het die grootste verskille getoon. ‘Flavor King’, die plumcot, het ook ‘n ryp aromaprofiel gehad wat baie van die van die egte pruime verskil het.

Nous avons étudiés des fils quantiques dopés de semi-conducteurs gravés par spectroscopie de diffusion Raman. Nous avons observés les excitations du gaz d'électrons. Celles-ci présentent des règles de sélection différentes de celles établies pour les systèmes bi-dimensionnels. Nous avons montré théoriquement qu'elles proviennent de la modification de la structure du champ électromagnétique local provoquée par la géométrie particulière des fils gravés. Pour cela nous avons dû calculer le champ local et l'introduire dans la section efficace de diffusion Raman pour en déduire les règles de sélection de toutes les excitations. Cela a permis de déterminer sans équivoque la nature des excitations qui sont des plasmons. Aucune excitations à une particule ni fluctuations de densité de spin n'a été observées. Nous avons étudié l'évolution continue des dispersions de ces plasmons lorsque la largeur du fil est réduite de 1 micromètre à 30 nm. Jusqu'à 60 nm, celles-ci sont en très bon accord avec les résultats d'un modèle hydrodynamique. Au dessous de 60 nm, la comparaison avec un modèle RPA s'impose. Le plasmon intra-bande dispersif est observé jusqu'à 45 nm, largeur en dessous de laquelle les spectres Raman sont dominés par des excitations localisées qui nécessitent une analyse ultérieure pour en déterminer clairement leur nature. Nous montrons à l'aide du modèle RPA que nous avons atteint la limite quantique pour un fil de largeur 55 nm. Une gamme étroite de fils dont les largeurs sont comprises entre 55 nm à 45 nm permet donc l'étude de gaz strictement unidimensionnel.<br />Nous avons cherché à déterminer la contribution de la forte illumination dans les conclusions précédentes. Nous avons utilisé pour cela la spectroscopie de magnéto-transmission infra-rouge qui ne modifie pas les conditions d'équilibre du gaz d'électrons. Une largeur critique de 130 nm a été extraite, en dessous de laquelle nous n'avons plus aucun signe de la présence d'électrons libres. La comparaison des mesures Raman et infra-rouge a permis l'établissement et la validation d'un modèle microscopique du potentiel de confinement présent dans les fils. Enfin nous avons fabriqués des échantillons de géométries plus complexes. L'observation et l'analyse par diffusion Raman des plasmons dans ces fils a montré que nous pouvions contrôler la géométrie du potentiel confinant les électrons et a mis en évidence des effets nouveaux tels que le repliement et le confinement de plasmons unidimensionnels.

Les composés à commutation électronique constituent une large famille de systèmes particulièrement prometteuse, notamment pour le stockage de l’information à l’échelle moléculaire. Parmi ces composés, les analogues du bleu de Prusse cobalt-fer (ABP AxCoFe) sont des polymères inorganiques formés d’enchaînements Co-N≡C-Fe pouvant présenter deux états électroniques CoII(HS)-N≡C-FeIII(BS) et CoIII(BS)-N≡C-FeII(BS) (HS : haut spin ; BS : bas spin) aux propriétés structurales et électroniques bien distinctes. La transition électronique entre ces deux états peut être contrôlée de manière réversible par une grande variété de paramètres chimique (insertion de cations alcalins) et physiques (température, pression, irradiation). Ces propriétés de photo-commutation sont particulièrement intéressantes pour le développement de mémoires optiques à l’échelle moléculaire.Afin de comprendre les propriétés électroniques des ABP AxCoFe, nous nous sommes intéressés à l’interaction entre les centres métalliques via le pont cyanure dans l’enchaînement Co-N≡C-Fe, aussi bien sur un plan expérimental (mise en œuvre de techniques d’analyse reposant sur l’utilisation du rayonnement synchrotron) que théorique (modélisation ab initio de type post-Hartree-Fock). Nous avons également étudié la nature de l’interaction, démontrée expérimentalement, entre les cations alcalins et le réseau bimétallique formé par les enchaînements Co-N≡C-Fe. Finalement, la pertinence du modèle à deux états, habituellement utilisé pour rendre compte des propriétés électroniques des systèmes commutables, est discutée, avec la mise en évidence de multistabilités au sein des ABP AxCoFe. Ce travail propose ainsi une étude la plus complète possible des phénomènes électroniques rencontrés dans ces systèmes. / Electronically switchable compounds constitute a wide family of very promising systems, especially in the field of data storage at a molecular scale. Amongst these compounds, cobalt-iron Prussian blue analogues (AxCoFe PBAs) are inorganic polymers based on Co-N≡C-Fe linkages that may exhibit two CoII(HS)-N≡C-FeIII(LS) and CoIII(LS)-N≡C-FeII(LS) (HS: high spin; LS: low spin) electronic states with very different structural and electronic properties. Electronic transition in between these two states can be reversibly controlled by a large variety of both chemical (insertion of alkali cations) and physical (temperature, pressure, irradiation) parameters. These photo switching properties are extremely appealing for the development of optical memory devices at the molecular scale.In order to understand the electronic properties of AxCoFe PBAs, the interaction occurring between the metallic centres through the cyanide bridge in the Co-N≡C-Fe linkages was investigated both at an experimental (use of synchrotron-radiation-based analytic techniques) and a theoretical (post-Hartree-Fock ab initio modelling) levels. The nature of the experimentally-demonstrated interaction between the alkali cations and the bimetallic network, made of the Co-N≡C-Fe linkages, was also studied. Finally, the relevance of the two-state model, usually invoked to account for the electronic properties of switchable systems, is discussed, as multistabilities are evidenced in PBAs. This work therefore offers study of the electronic phenomena occurring in such systems as comprehensive as possible.

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-05-15T19:57:24Z No. of bitstreams: 1 TeseCOF.pdf: 3178869 bytes, checksum: cfad2da3f19b56d42e09c4a472158572 (MD5) / Approved for entry into archive by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-02-01T10:55:05Z (GMT) No. of bitstreams: 1 TeseCOF.pdf: 3178869 bytes, checksum: cfad2da3f19b56d42e09c4a472158572 (MD5) / Approved for entry into archive by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-02-01T10:55:19Z (GMT) No. of bitstreams: 1 TeseCOF.pdf: 3178869 bytes, checksum: cfad2da3f19b56d42e09c4a472158572 (MD5) / Made available in DSpace on 2018-02-01T11:06:54Z (GMT). No. of bitstreams: 1 TeseCOF.pdf: 3178869 bytes, checksum: cfad2da3f19b56d42e09c4a472158572 (MD5) Previous issue date: 2016-06-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Type 2 diabetes mellitus (DM) is responsible for quality of life reduction due its negative impact in the physical exercise capacity. The impairment of cardiopulmonary fitness and lower values in oxygen uptake in exercise tests has been associated with factors related with diabetes complications. Phototherapy is a resource largely utilized due it action in biological systems and it may be adjuvant to exercise to improve muscular efficiency and increase aerobic capacity. Thus, the question if this resource may be benefit to populations with DM. Therefore, we proposed a study protocol randomized, double-blind, placebo controlled to evaluate the acute effect of light emitting diode (LED) in cardiorespiratory and hemodynamic adjustments of moderate exercise in cycloergometer, as well as, in lactate and glucose levels pre and post intervention and after exercise in men aged between 45 and 64 years, with DM and health. Then, two studies were performed. In the study 1 it was evaluated the acute effect of phototherapy (LED-150J) in two groups: DM group (DMG) and health group (HG) (n=16 and n=9, respectively). The groups were paired by age and body mass index. The LED reduced significantly the glucose levels in DMG after exercise and do not affect the lactate levels, cardiorespiratory and hemodynamic adjustments of aerobic exercise in both groups. Our results suggest that LED in combination with moderate exercise decrease acutely the glucose levels in adult subjects with DM. The study 2 aimed evaluate the acute effect of two different doses of phototherapy. Participated in this study two groups of men with DM: LED-150J (n=16) and LED-300J (n=17). The LED-150J reduced the levels of glucose after exercise. The LED-300J increased the lactate levels after exercise in effective session compared with placebo. Any doses changed the cardiorespiratory and hemodynamic adjustments. This study demonstrated that the phototherapy with LED using the 300J dose did not improved the parameters studied and the 150J dose improved the glycaemia and should be used in combination with other therapies for the hyperglycemia management in individuals with DM. The general conclusion of this thesis is that our findings suggest that phototherapy associated with moderate physical exercise have therapeutic potential to control glycaemia in DM, however, further studies should be conducted investigating the dose window and dose-response capable to change acutely the cardiopulmonary and hemodynamic adjustments and lactate levels. / O diabetes mellitus tipo 2 (DM) é responsável por redução significativa na qualidade de vida devido ao seu impacto negativo na capacidade de realização de exercícios físicos. A diminuição do condicionamento cardiopulmonar e os menores valores de consumo de oxigênio pico em testes de exercício têm sido associados com múltiplos fatores envolvidos nas complicações do diabetes. A fototerapia é um recurso que tem sido utilizado devido sua ação nos sistemas biológicos, podendo ser um coadjuvante do exercício na melhora da eficiência do trabalho muscular e aumento da capacidade aeróbia. Por isso, levantou-se a questão de que tal recurso poderia beneficiar populações com DM. Assim, foi proposto um protocolo experimental aleatorizado e duplo-cego visando avaliar o efeito agudo da fototerapia com diodos emissores de luz (LED) nos ajustes cardiorrespiratórios e hemodinâmicos ao exercício moderado em cicloergômetro, bem como nas concentrações de lactato e glicose sanguíneas pré e pós intervenção e após o exercício físico em homens com DM e saudáveis, com idade entre 45 e 64 anos. A partir deste protocolo dois estudos foram realizados. No estudo 1 foi avaliado o efeito agudo da fototerapia (LED-150J) em dois grupos: grupo com DM (GDM, n=16) e grupo saudável (GS, n=9). Os grupos foram pareados por idade e índice de massa corpórea. O LED reduziu significativamente as concentrações de glicose no GDM após o exercício em cicloergômetro e não afetou os níveis de lactato e os ajustes cardiorrespiratórios e hemodinâmicos em ambos os grupos. Nossos resultados sugerem que o LED em combinação com o exercício moderado reduz de forma aguda os níveis de glicose em homens adultos com DM. No estudo 2 objetivou-se avaliar o efeito agudo de duas diferentes doses de fototerapia. Participaram desse estudo dois grupos de homens com DM: LED-150J (n=16) e LED-300J (n=17). O LED-150J reduziu as concentrações de glicose após o exercício físico e o LED-300J aumentou os níveis de lactato após o protocolo de exercício na fototerapia efetiva em comparação com a fototerapia placebo. Nenhuma das dosagens avaliadas modificou significativamente os ajustes cardiopulmonares e hemodinâmicos avaliados. Este estudo mostrou que a fototerapia por meio de LED na dosagem de 300J não causou melhora nos parâmetros estudados enquanto a dosagem de 150J melhorou a glicemia, podendo ser utilizada como recurso adjuvante no controle da hiperglicemia em indivíduos com DM. Como conclusão geral, nossos achados sugerem que a fototerapia associada ao exercício moderado tem potencial terapêutico no controle da glicemia do DM, no entanto, mais estudos são necessários para estabelecer a janela terapêutica e a dose-resposta capaz de modificar de forma aguda os ajustes cardiopulmonares e hemodinâmicos, assim como os níveis de lactato. / FAPESP: 2013/08183-7 / FAPESP: 2015/20512-1 / FAPESP: BEPE 2013/07953-3