<p>The Fenna-Matthews-Olson (FMO) complex is a photosynthetic pigment-protein complex that has been the subject of study of decades of research, both experimental and theoretical. The FMO complex is small enough that computational modeling is feasible, while the rich excitonic interactions between the pigments give rise to absorption and circulardichroism (CD) spectra with many interesting details. This makes FMO an excellent testing ground for new predictive modeling techniques.</p> <p><br></p> <p>In this work we model the FMO complex from first-principles, wherein the only input is the X-ray crystal structure of the protein. We compute steady-state absorption and CD spectra of wild-type (WT) FMO as well as two mutants, Y16F and Q198V, in which amino acid residues near pigment 3 and pigment 7 are replaced respectively. CD spectra contain extra structural information and thus provide another avenue of investigation into the electronic properties of the FMO complex. We find that while there are large structural changes in the mutants, not all of the structural changes produce significant spectral changes. We conclude that the primary contributor to the spectral changes in Y16F is the breaking of a hydrogen bond between the nearby tyrosine and pigment 3. On the other hand, the spectral changes in Q198V are due to a collection of effects cancelling one another out to varying degrees, all induced by widespread structural changes as a result of the mutation.</p> <p><br></p> <p>We then perform time-resolved absorption and CD spectroscopy measurements on WT, Y16F, and Q198V FMO to provide a high quality set of experimental data against which the first-principles spectra can be validated. We find that in order to accurately model the triplet energy transfer dynamics in FMO two effects must be accounted for in the modeling: (1) the Stark shift caused by the rotation of the bacteriochlorophyll’s permanent dipole moment upon entering a triplet state, and (2) decays must be modeled as Boltzmann populations rather than individual pigments.</p>

Dehydrogenation is the catalytic process of removing hydrogen from a saturated hydrocarbon to produce an olefin. Olefins are important feedstocks for the petrochemical industry and can potentially be used to produce fuels through oligomerization. Alloys containing an active metal such as platinum and palladium and a non-catalytic metal offer improved selectivity towards the olefin. This body of work seeks to further the understanding of how heteroatomic bonds in alloys change the rate and selectivity of alloy catalysts used for dehydrogenation.In the first study, a series of Pt-V bimetallic catalysts are synthesized, which are highly selective propane dehydrogenation catalysts. The bimetallic nature of the nanoparticles was verified by in-situX-ray Absorption Spectroscopy(XAS)and the formation of the Pt3V alloy phase was shown by in-situ synchrotronX-ray Diffraction(XRD). A reduction-oxidation differenceXASmethod was used to examine the surface stoichiometry and found that a shell layer of the alloy phase forms when the particles are platinum rich. Electronic modification of Pt was studied by Pt L3edgeX-ray Absorption Near Edge Structure(XANES),X-ray Photoelectron Spectroscopy(XPS), Resonant Inelastic X-ray Scattering (RIXS)andDensity FunctionalTheory(DFT). The spectral changes observed were shown to be due to changes in the energy of the filled and unfilled 5d density of states, and not due to electron transfer. The electronic modifications cause a weakening of adsorbate binding and destabilization of deeply dehydrogenated hydrocarbons, which contributes to the dehydrogenation selectivity.In the second study, alloys between palladium and five different promoters were synthesized and tested as propane dehydrogenation catalysts.The structure ofthe alloy catalysts was characterized by in-situ XAS and in-situ synchrotron XRD.Zinc and indium form alloy structures with site isolated palladium, while gallium, iron and manganese do not. All of the alloys have improved propane dehydrogenation selectivity compared to monometallic palladium. The propylene production turnover rate of the alloys increased by almost an order of magnitude compared to monometallic Pd, but among the alloys the turnover ratesonly varied by a factor of two despite the different structures and electronic modifications inherent to each phase. The site isolated alloys had higher propylene selectivity than those that were not site isolated. The site isolated alloys showed strongerelectronic modification: both in binding strengths and in Pd projected Density of States (pDOS)by DFT than did the non-site isolated alloys. The commonly used computational selectivity descriptor for dehydrogenation, which is the difference in energy between alkene desorption and alkene C-H bond activation energy correctly predicts that the site isolated alloys will have high selectivity but shows weaker trends for alloys without site isolation. A modified selectivity descriptor, involving the C-C bond breaking barrier in the adsorbed alkyne more accurately reflects the high selectivity of the non-site isolated alloys.In a third study,RIXS and XPSare used to examine trends in the electronic modification of platinum alloys with transition metal and post transition metal promoters. All alloys show an increase in the energy transfer maximum, showing that alloying modifies energy the filled and unfilled density of states. The increase in the energy transfer maximum in platinum alloys with 3d metals islargerfor early transition metals, which by DFT show larger shifts in the d-band center. The post transition elements showsignificantlylarger shifts than to the transition elements, partially due to the lack of orbital overlap between the valence p orbitals and Pt 5d orbitals. Platinum has the same number of valence d electrons regardless of promoter or structure, and redistribution of the 5d electron energy brought about by heteroatomic bonds leads to the observed electronic modifications. The positive binding energy shifts measured by XPS reflect these energy changes, which occur due to changes in the Fermi energy of the alloy, initial state effects and intra and extra atomic relaxation (final state effects). The calculated initial state effect shift is correlated to descriptors of the valence d band, such as the d band center.

Made available in DSpace on 2015-05-14T13:00:17Z (GMT). No. of bitstreams: 1 parte1.pdf: 2218079 bytes, checksum: 8c3306b1c24bd11212cd191d547b9f95 (MD5) Previous issue date: 2011-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Turnera subulata Sm., popularly known as Chanana or flor-do-Guaruja , is a Brazilian medicinal plant belonging to the family Turneraceae. In Brazil this family is represented by two genera, Piriqueta and Turnera, being Turnera the most representative. The Genus Turnera is characterized by the presence of terpenoids, flavonoids, steroids, benzenoids, alkaloids and lipids. Aiming at contributing to the chemical profile of the family Turneraceae and considering the absence of data in literature about the chemical constitution of the species Turnera subulata, the latter was submitted to a phytochemical study to isolate its chemical constituents, through usual chromatographic methods, and after identifying them by means of spectroscopic methods such as IR and 1H and 13C NMR, with the add of two-dimensional techniques. Six constituents were isolated through this phytochemical study with Turnera subulata: Phaeophytin purpurin 18 phytyl ester (Ts-5); Phaeophytin (a) (Ts-1); 132- hydroxy - (132-S)- Phaeophytin (a) (Ts-2); Phaeophytin (b) (Ts-4) and mixture of steroids sitosterol-3- O-D-glucopyranoside and Stigmasterol-3-O-&#946;-D-glucopyranoside (Ts-3). / Turnera subulata Sm, conhecida popularmente como chanana ou flor-do-Guarujá , é uma espécie da família Turneraceae. No Brasil esta família é representada pelos gêneros, Piriqueta e Turnera, sendo Turnera o mais representativo, com cerca de 80 espécies. Este Gênero é caracterizado pela presença de terpenóides, flavonóides, esteróides, benzenóides, alcalóides e lipídios. Visando contribuir com o perfil químico da família Turneraceae e tendo em vista a ausência de dados na literatura acerca da constituição química da espécie Turnera subulata Sm, esta foi submetida a um estudo fitoquímico para o isolamento de seus constituintes químicos, através dos métodos cromatográficos usuais, e posterior caracterização estrutural dos mesmos, utilizando-se os métodos espectroscópicos de IV e RMN 1H e 13C uni e bidimensionais. Deste estudo pioneiro com Turnera subulata foram isolados e identificados seis constituintes: Feofitina Purpurina 18 fitil éster (Ts-5); Feofitina (a) (Ts-1); 132-hidroxi- (132-S)-feofitina (a) (Ts-2); Feofitina (b) (Ts-4) e uma mistura dos esteróides glicosilados sitosterol-3-O-D-glicopiranosídeo e estigmasterol-3-O-&#946;-D-glicopiranosídeo (Ts-3).

The aim of this diploma thesis is to study to the influence of compost addition to soil humic substances extracted from blackland luvicsol. Humic substances extracted from soil and from compost were characterized by titration with potentiometrical and conductival indication, UV-VIS, FT-IR and 3D EEM fluorescential spectroscopy. Compost in amount of 124, 239 and 478 t/ha was applicated and manured into dept of 150 mm at blackland luvicsol. The main aim of thesis was the appraisal of compost influence into fluorescent attributes of soil HS and localization of fluorescent peaks at excitation emission spectrums. Next part of diploma thesis was focused on the study of spectroscopic attributes of soil HS and compost by UV-VIS and infrared spectroscopy with Fourier transformation. Humic substances were characterized by humifical index E4/E6 and transmissional vibratile spectrums. The last aim of diploma thesis were the characterization of soil HS extracts and compost by acidimetral titration. For each sample was calculated value of H+ ionts amount of substance from measured titrational curves.

Made available in DSpace on 2015-05-14T13:00:16Z (GMT). No. of bitstreams: 1 parte1.pdf: 1831171 bytes, checksum: 228d3280be1b514141d6d1e465f701b6 (MD5) Previous issue date: 2011-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Medicinal plants are an alternative therapy for the prevention and cure of disease since the beginning of humanity. This relationship is so intimate that mingles with the own evolution of man. Brazil has a great diversity on plants that possess non-researched medicinal potential and are promising sources of therapeutic and pharmacological innovations. The Rubiaceae family is considered the biggest one of the order Gentianales, presenting around 637 genera and 10,700 species. The species Richardia grandiflora (Cham. & Schltdl.) Steud., known popularly as ervanço , poaia or ipeca-mirim , has ethnopharmacological indications to use as decoction against hemorrhoids and as vermifuge. Aiming at contributing to the chemotaxonomic study of the the family Rubiaceae and considering the small amount of data in literature about the chemical constitution of the species Richardia grandiflora, the latter was submitted to a phytochemical study to isolate its chemical constituents, through usual chromatographic methods, and after identifying them by means of spectroscopic methods such as IR and 1H and 13C NMR, besides comparison with literature data. Three constituents were isolated through this phytochemical study: oleanolic acid, ursolic acid, unpublished in the species, and 132-hydroxy-(132-S)-phaeophytin (a), isolated for the first time from the genre. / As plantas medicinais constituem uma alternativa terapêutica para a prevenção e cura de doenças desde o início da humanidade. Tal relacionamento é tão íntimo que se confunde com a própria evolução do homem. O Brasil tem grande diversidade de plantas com potenciais medicinais, não-pesquisadas, e que são promissoras fontes de inovações terapêuticas e farmacológicas. A família Rubiaceae, considerada a maior da ordem Gentianales, possui cerca de 637 gêneros e 10.700 espécies. A espécie Richardia grandiflora (Cham. & Schltdl.) Steud., conhecida popularmente como ervanço, poaia ou ipeca-mirim, tem indicações etnofarmacológicas para uso contra hemorróidas e como vermífugo na forma de decocto. Visando a contribuir com o estudo quimiotaxonômico da família Rubiaceae e tendo em vista a pouca quantidade de dados na literatura acerca da constituição química da espécie Richardia grandiflora, esta foi submetida a um estudo fitoquímico para o isolamento de seus constituintes químicos, através dos métodos cromatográficos usuais, e posterior identificação estrutural dos mesmos, utilizando-se os métodos espectroscópicos de IV e RMN 1H e 13C, além de comparações com modelos da literatura. Deste estudo foram isolados e identificados três constituintes: o ácido oleanólico, o ácido ursólico, inéditos na espécie, e a 132-hidroxi- (132-S)-feofitina (a), inédita no gênero.

Antioxidant properties and some other characteristics of selected organic and conventional products (wine, spelt flours) were evaluated in view of their potential utilization as markers suitable for food unambiguous differentiation according to the affiliation to production system. Beside these, study of fruit juices stability during storage in dependence on different technological procedures of juice processing was performed. In both cases, combination of dominantly EPR and UV/VIS spectroscopy but also other methods (e.g., HPLC, AAS, electrophoresis) was applied to evaluate the stability and antioxidant properties of selected samples. Statistical methods, especially methods of multivariate statistics were used to assess the influence of production and technological-processing operations on antioxidant status of foods and their selected characteristics. Qualitative analysis of Slovak and foreign organic and conventional wines proved that their antioxidant properties are influenced by production system, vintage and variety. On the basis of statistical analysis, descriptors of AAE, kTEMPOL and %RS were selected as the most powerful markers for Slovak organic and conventional wines discrimination. The discrimination of white and red organic and conventional wines possessed 100% and 95.2% correctness, respectively. High correctness of differentiation of Slovak and foreign wines was also achieved. Monitored descriptors of antioxidant activity of spelt flours varied in dependence on season, origin, variety, production system and depend also on way of spelt treatment, although this effect is not so significant. It was also confirmed that the type of extraction agent substantially affects the composition of extracts including polyphenols and flavonoids concentration, affecting thus also their antioxidant activity. Mixture of 50% ethanol/water was selected as the most promising extraction system. Although the results of individual spectroscopic assays revealed high variability and often ambiguous trends, the differences found were sufficient for successful differentiation of both wines and spelt flour samples according to the selected criteria by multivariate statistical processing of the data. Influence of changes in technological procedures of fruit juice processing (nitrogen atmosphere application, utilization of caps with oxygen scavengers) on radical-scavenging properties of 100% pineapples juices with pieces of pineapple and 100% orange juices with pulp was assessed as well. Results obtained proved that antioxidant activity of juices varied in dependence on storage conditions (temperature, storage time, light exposure) and depends also on origin, variety and quality of fruit used. However, the application of nitrogen atmosphere and active packaging materials is not sufficient enough to eliminate the oxidation reactions in juices, but changes in antioxidant activity are better predictable. It can be concluded that EPR spectroscopy could be effectively applied for wines and spelt flours differentiation according to the way of production and to assess the stability of food products, either alone or in combination of UV/VIS spectroscopy and the other methods, utilizing multivariate statistics for processing of experimental data.