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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.
461

Molekularbiologische Charakterisierung von Häm-Thiolat- und DyP-type-Peroxidasen ausgewählter Basidiomyceten / Molecular biological charaterization of heme-thiolate and DyP-type peroxidases of selected basidiomycetes

Pecyna, Marek 08 December 2016 (has links) (PDF)
Peroxidasen des Typs ClassII sowie die Chlorperoxidase waren für mehrere Jahrzehnte die einzigen bekannten sekretorischen Hämperoxidasen aus Pilzen. Im Jahr 2004 wurde eine neue, ungewöhnliche Hämperoxidase aus dem Speisepilz Agrocybe aegerita isoliert und biochemisch charakterisiert. Diese Peroxidase, heute offiziell Unspezifische Peroxygenase (UPO, EC 1.11.2.1) genannt, vereint in sich Eigenschaften sowohl intrazellulärer Cytochrom-P450-Enzyme als auch klassischer extrazellulärer, pilzlicher Peroxidasen des Typs ClassII. In dieser Arbeit wurden für den UPO-Modellorganismus A. aegerita und für andere UPO-produzierende Pilze erstmals Nukleotidsequenzen der Enzyme ermittelt und phylogenetisch analysiert. Die Genome zweier Stämme von A. aegerita wurden sequenziert. Die Ergebnisse legen nahe, dass UPOs gemeinsam mit der Chlorperoxidase Vertreter einer phylogenetisch alten Protein-Superfamilie (Häm-Thiolat-Peroxidasen) darstellen, die in allen echten Pilzen (Eumycota) zu finden ist, aber in echten Hefen und einigen hefeartig wachsenden Basidiomyceten sekundär reduziert wurde. Die natürliche Funktion dieser extrazellulären Enzyme ist bislang unbekannt. Im Labor können UPOs ausschließlich unter Verwendung leguminosenhaltiger Kulturmedien induziert werden. Die induzierende Komponente aus Soja wurde in dieser Arbeit als proteinogen identifiziert. Eine zweite neue, extrazelluläre Hämperoxidase-Superfamilie ausserhalb der ClassII-Peroxidasen wurde im Totholz bewohnenden Pilz Bjerkandera adusta entdeckt. Die als DyP-type-Peroxidasen benannten Enzyme (DyP, EC 1.11.1.19) wurden später auch in anderen Pilzen gefunden, von denen in dieser Arbeit ebenso Nukleotidsequenzen erhalten wurden. Die phylogenetische Analyse ergab, dass pilzliche Sequenzen der DyP-type-Peroxidase-Superfamilie sehr ungleichmäßig sowie ausschließlich in den Genomen höherer Pilze (Dikarya) verteilt sind und vermutlich einen prokaryotischen Ursprung haben. Transkripte von UPO- und DyP-Genen wurden in nahezu allen untersuchten Laubstreuproben aus unterschiedlich stark genutzten Waldgebieten der Deutschen Biodiversitätsexploratorien nachgewiesen. Dies legt eine biologische Funktion dieser neuen Hämperoxidase-Superfamilien in entsprechenden Habitaten nahe. / For several decades ClassII peroxidases and chloroperoxidase have been the only known secretory heme peroxidases from fungi. In 2004, a novel heme peroxidase was isolated and characterized from the edible mushroom Agrocybe aegerita. This enzym, nowadays called unspecific peroxygenase (UPO, EC 1.11.2.1), combines characteristics of intracellular cytochrom P450 enzymes as well as extracellular classII fungal peroxidases. In the course of this PhD work, for the first time nuleotide sequences of UPO model organism A. aegerita as well as other UPO producing fungi were obtained and phylogenetically analyzed. The whole-genome sequences of two strains of A.aegerita were obtained. The results suggest that UPOs and the chloroperoxidase together represent a phylogenetically old protein superfamily (of heme-thiolate peroxidases) that is found in all true fungi (Eumycota), but is secondarily reduced in true yeasts and a few yeast-like growing basidiomycetes. The natural function of these enzymes remains unclear. In the laboratory, fungi secrete UPOs solely in legume-containing culture media. The eliciting component of the legume soybean has been determined as proteinogenic. A second novel heme peroxidase superfamily outside the classII peroxidases was discovered in deadwood inhabiting fungus Bjerkandera adusta. These so-called DyP-type peroxidases (DyP, EC 1.11.1.19) were later found expressed in several other fungi for which nucleotide sequences were obtained in this work, too. Phylogenetical analysis revealed that fungal DyP sequences are exclusively but very unequally distributed in genomes of higher fungi (Dikarya). Fungal DyP sequences are seemingly decended from prokaryotes. Transcripts encoding UPOs and DyPs were found in almost every sample of leave litter (derived from forests with different intensity of human usage) investigated. This suggests biological functions of these new heme peroxidase superfamilies in respective habitats.
462

Development of new highly conjugated molecules and their application in the field of renewable energy and biomaterials / Développement de nouvelles molécules hautement conjuguées et leurs applications dans le domaine des énergies renouvelables et des biomatériaux

Bessi, Matteo 06 December 2018 (has links)
Ces dernières années, les matériaux fonctionnels hybrides ont commencé à être employés pour des applications de la haute technologie, allant des senseurs bio/médicaux, à la production d’énergie renouvelable. Pour cette raison, ils sont devenus le centre de plusieurs études dans le domaine des sciences des matériaux. Simultanément, des molécules conjuguées ont été examinée intensément à cause de leurs propriétés venant de leurs longs systèmes π, allant de la possibilité de conduire l’électricité, à leur capacité d’absorber la lumière dans une grande fenêtre spectrale. Le travail de cette thèse se concentre sur l’introduction de tels systèmes dans deux sortes de matériaux hybrides, les dispositifs photovoltaïques pour la production d’électricité (en particuliers les cellules solaires à pigment photosensible) et de carburants alternatifs (hydrogène), et pour les hydrogels biocompatibles sensibles aux stimuli (capables de conduire l’électricité et de réagir sous irradiation), et sur l’étude de leur influence sur les caractéristiques du matériau final. / In recent years hybrid functional materials began to be employed in a series of technologically advanced applications spanning from bio/medical sensors, to renewable energy generation. For this reason, they became the focus of several studies in the field of materials science. At the same time, conjugated molecules have also been intensively investigated, due to the properties arising by the presence of long π-conjugated systems, from the possibility to conduct electricity to the ability to absorb light in a wide range of wavelengths. This PhD work focused on the introduction of such systems in two different kinds of hybrid materials, namely photovoltaic devices for the production of electricity (in particular Dye Sensitzed Solar Cells) and alternative fuels (hydrogen), and biocompatible stimuli-responsive hydrogels (capable to conduct electricity and to react upon irradiation), and on the study of their influence on the characteristics of the final material.
463

Aqueous dye sensitized solar cells

Risbridger, Thomas Arthur George January 2013 (has links)
Dye sensitized solar cells (DSSCs) have typically been produced using organic liquids such as acetonitrile as the electrolyte solvent. In real world situations water can permeate into the cell through sealing materials and is also likely to be introduced during the fabrication process. This is a problem as the introduction of water into cells optimized to use an organic solvent tends to be detrimental to cell performance. In this work DSSCs which are optimized to use water as the main electrolyte solvent are produced and characterized. Optimization of aqueous DSSCs resulted in cells with efficiencies up to 3.5% being produced. In terms of characterization, it is generally seen in this work that aqueous DSSCs produce a lower photocurrent but similar photovoltage compared to DSSCs made using acetonitrile and reasons for this are examined in detail. The decreased ability of the aqueous electrolyte to wet the nanoporous TiO2 compared to an acetonitrile electrolyte is found to be a key difficulty and several possible solutions to this problem are examined. By measuring the photocurrent output of aqueous cells as a function of xy position it can be seen that there is some dye dissolution near to the electrolyte filling holes. This is thought to be linked to pH and the effect of 4-tert-butylpyridine and may also decrease the photocurrent. It is found that there is little difference between the two types of cells in terms of the conduction band position and the reaction of electrons in the semiconductor with triiodide in the electrolyte, explaining the similarity in photovoltage. By altering the pH of the electrolyte in an aqueous cell it is found to be possible to change the TiO2 conduction band position in the DSSC. This has a significant effect on the open circuit voltage and short circuit current of the cell, though the pH range available is limited by the fact that dye desorbs at high pH values.
464

Photoelectrochemical studies of dye-sensitized solar cells using organic dyes

Marinado, Tannia January 2009 (has links)
The dye-sensitized solar cell (DSC) is a promising efficient low-cost molecular photovoltaic device. One of the key components in DSCs is the dye, as it is responsible for the capture of sunlight. State-of-the-art DSC devices, based on ruthenium dyes, show record efficiencies of 10-12 %. During the last decade, metal-free organic dyes have been extensively explored as sensitizers for DSC application. The use of organic dyes is particularly attractive as it enables easy structural modifications, due to fairly short synthetic routes and reduced material cost. Novel dye should in addition to the light-harvesting properties also be compatible with the DSC components. In this thesis, a series of new organic dyes are investigated, both when integrated in the DSC device and as individual components. The evaluation methods consisted of different electrochemical and photoelectrochemical techniques. Whereas the light-harvesting properties of the dyes were fairly easily improved, the behavior of the dye integrated in the DSC showed less predictable photovoltaic results. The dye series studied in Papers II and IV revealed that their dye energetics limited vital electron-transfer processes, the dye regeneration (Paper II) and injection quantum yield (Paper IV). Further, in Papers III-VI, it was observed that different dye structures seemed to alter the interfacial electron recombination with the electrolyte. In addition to the dye structure sterics, some organic dyes appear to enhance the interfacial recombination, possibly due to specific dye-redox acceptor interaction (Paper V). The impact of dye sterical modifications versus the use of coadsorbent was explored in Paper VI. The dye layer properties in the presence and absence of various coadsorbents were further investigated in Paper VII. The core of this thesis is the identification of the processes and properties limiting the performance of the DSC device, aiming at an overall understanding of the compatibility between the DSC components and novel organic dyes. / QC 20100730
465

Hybrid cell for harvesting multiple-type energies

Xu, Chen 21 May 2012 (has links)
An abundance of energy in our environment exists in the form of light, thermal, mechanical (e.g., vibration, sonic waves, wind, and hydraulic), magnetic, chemical, and biological. Harvesting these forms of energy is of critical importance for solving long-term energy needs and the sustainable development of the planet. However, conversion cells for harvesting solar energy and mechanical energy are usually independent entities that are designed and built following distinct physical principles. The effective and complementary use of such energy resources whenever and wherever one or all of them are available demands the development of innovative approaches for the conjunctional harvesting of multiple types of energy using an integrated structure/material. By combining solar and mechanical energy-harvesting modules into a single package for higher energy conversion efficiency and a more effective energy recovery process, the research has designed and demonstrated a hybrid cell for harvesting solar and mechanical energy. The results of the research show that we can fully utilize the energy available from our living environment by developing a technology that harvests multiple forms of both solar and mechanical energy 24 hours a day. As the proposed research represents a breakthrough in the innovation of energy harvesting, it should pave the way toward building a new field called "multi-type hybrid" energy harvesting.
466

Uncooled Infrared Photon Detection Concepts and Devices

Piyankarage, Viraj Vishwakantha Jayaweera 23 March 2009 (has links)
This work describes infrared (IR) photon detector techniques based on novel semiconductor device concepts and detector designs. The aim of the investigation was to examine alternative IR detection concepts with a view to resolve some of the issues of existing IR detectors such as operating temperature and response range. Systems were fabricated to demonstrate the following IR detection concepts and determine detector parameters: (i) Near-infrared (NIR) detection based on dye-sensitization of nanostructured semiconductors, (ii) Displacement currents in semiconductor quantum dots (QDs) embedded dielectric media, (iii) Split-off band transitions in GaAs/AlGaAs heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors. A far-infrared detector based on GaSb homojunction interfacial workfunction internal photoemission (HIWIP) structure is also discussed. Device concepts, detector structures, and experimental results discussed in the text are summarized below. Dye-sensitized (DS) detector structures consisting of n-TiO2/Dye/p-CuSCN heterostructures with several IR-sensitive dyes showed response peaks at 808, 812, 858, 866, 876, and 1056 nm at room temperature. The peak specific detectivity (D*) was 9.5E+10 Jones at 812 nm at room temperature. Radiation induced carrier generation alters the electronic polarizability of QDs provided the quenching of excitation is suppressed by separation of the QDs. A device constructed to illustrate this concept by embedding PbS QDs in paraffin wax showed a peak D* of 3E+8 Jones at ~540 nm at ambient temperature. A typical HEIWIP/HIWIP detector structures consist of single (or multiple) period(s) of doped emitter(s) and undoped barrier(s) which are sandwiched between two highly doped contact layers. A p-GaAs/AlGaAs HEIWIP structure showed enhanced absorption in NIR range due to heavy/light-hole band to split-off band transitions and leading to the development of GaAs based uncooled sensors for IR detection in the 2 5 μm wavelength range with a peak D* of 6.8E+5 Jones. A HIWIP detector based on p-GaSb/GaSb showed a free carrier response threshold wavelength at 97 µm (~3 THz)with a peak D* of 5.7E+11 Jones at 36 μm and 4.9 K. In this detector, a bolometric type response in the 97 - 200 µm (3-1.5 THz) range was also observed.
467

Towards new π-conjugated systems for photovoltaic applications / Vers de nouveaux systèmes π-conjugués pour des applications photovoltaïques

Chevrier, Michèle 15 September 2016 (has links)
Le développement des énergies renouvelables est aujourd’hui devenu un enjeu mondial majeur comme alternative aux énergies fossiles dans la production d'énergie. Parmi elles, l’énergie solaire est considérée comme la source la plus prometteuse, permettant de couvrir l’ensemble des besoins énergétiques liés à l’activité humaine. Les cellules photovoltaïques les plus performantes aujourd’hui, entre 16 et 18 % en modules, sont composées de silicium, un semi-conducteur inorganique. Cependant, leur coût de production élevé a nécessité le développement de matériaux alternatifs moins couteux. Parmi les voies explorées, les cellules solaires organiques ont émergé comme une alternative prometteuse pour produire l’électricité à faible coût. Le sujet de cette thèse s’intègre dans ce contexte de recherche. Deux types de cellules solaires ont été étudiés : les cellules à hétérojonction en volume (BHJ) et sensibilisées au colorant (DSSCs). Le courant photogénéré repose généralement (i) dans les cellules BHJ, sur le transfert entre de charge entre un polymère donneur et un accepteur d’électrons (fullerène), tels que le couple poly(3-hexyl)thiophène (P3HT) et [6,6]-phényl-C61-butanoate de méthyle (PCBM), et (ii) dans les DSSCs, la sensibilisation de la surface d’un semi-conducteur inorganique tel que l’oxyde de titane par un colorant et la présence d’un électrolyte, jouant le rôle de médiateur redox. Bien qu’ayant atteint des rendements de photoconversion respectifs de 5 et 13 %, ces cellules nécessitent des améliorations pour une commercialisation à grande échelle. Tout d’abord, les performances des cellules BHJ à base de P3HT sont considérablement limitées par sa faible absorption, ne couvrant pas la globalité du spectre solaire. Afin de palier ce problème, nous avons combiné le P3HT avec des chromophores, i.e. des porphyrines, ayant une absorption plus étendue. Ensuite, pour assurer une meilleure extraction des charges au sein du dispositif, une couche interfaciale cathodique à base de polyélectrolytes pi-conjugués a été ajoutée. Enfin, des colorants extraits de la biomasse ont été préparés afin de remplacer les colorants coûteux à base de ruthénium. En outre, les électrolytes liquides étant volatils et corrosifs, ce qui limite considérablement la stabilité des DSSCs, des électrolytes solides à base de polymères ont été étudiés comme alternative. / Among renewable energies, the sunlight has by far the highest theoretical potential to meet the worldwide need in energy. Photovoltaic devices are thus currently the subject of intense research for low-cost conversion of sunlight into electrical power. In particular, organic photovoltaics have emerged as an interesting alternative to produce electricity due to their low manufacturing cost compared to silicon solar cells, their mechanical flexibility and the versatility of the possible chemical structures. In this dissertation, we focused our research on the development of new organic pi-conjugated materials for organic solar cells applications. Two types of solar cells have been studied during this work: bulk heterojunction and dye-sensitized solar cells. The charge transfer leading to the photocurrent is usually based on (i) a polymer donor and a fullerene acceptor in BHJ solar cells, such as the widely studied poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) materials and (ii) a metal oxide (titanium oxide) sensitized with a dye and an electrolyte in DSSCs. Despite power conversion efficiencies have reached 5 and 13 % respectively for these two types of devices, they still display several drawbacks that limit their commercialization. P3HT displays a narrow absorption of the solar spectrum thus limiting the conversion efficiency. To overcome this limitation, we combined P3HT with chromophores, i.e. porphyrins, having an extending absorption. Then, to ensure better charge transfer and extraction within the device, a cathode interfacial layer based on cationic pi-conjugated polyelectrolytes was added. Finally, dyes extracted from the biomass (chlorophyll a derivatives) were synthesized to replace the expensive ruthenium dyes in DSSCs. Since liquid electrolytes are volatile and corrosive, which considerably limit the DSSCs stability, solid polymer electrolytes were also developed as an alternative.
468

Molekularbiologische Charakterisierung von Häm-Thiolat- und DyP-type-Peroxidasen ausgewählter Basidiomyceten

Pecyna, Marek 30 May 2016 (has links)
Peroxidasen des Typs ClassII sowie die Chlorperoxidase waren für mehrere Jahrzehnte die einzigen bekannten sekretorischen Hämperoxidasen aus Pilzen. Im Jahr 2004 wurde eine neue, ungewöhnliche Hämperoxidase aus dem Speisepilz Agrocybe aegerita isoliert und biochemisch charakterisiert. Diese Peroxidase, heute offiziell Unspezifische Peroxygenase (UPO, EC 1.11.2.1) genannt, vereint in sich Eigenschaften sowohl intrazellulärer Cytochrom-P450-Enzyme als auch klassischer extrazellulärer, pilzlicher Peroxidasen des Typs ClassII. In dieser Arbeit wurden für den UPO-Modellorganismus A. aegerita und für andere UPO-produzierende Pilze erstmals Nukleotidsequenzen der Enzyme ermittelt und phylogenetisch analysiert. Die Genome zweier Stämme von A. aegerita wurden sequenziert. Die Ergebnisse legen nahe, dass UPOs gemeinsam mit der Chlorperoxidase Vertreter einer phylogenetisch alten Protein-Superfamilie (Häm-Thiolat-Peroxidasen) darstellen, die in allen echten Pilzen (Eumycota) zu finden ist, aber in echten Hefen und einigen hefeartig wachsenden Basidiomyceten sekundär reduziert wurde. Die natürliche Funktion dieser extrazellulären Enzyme ist bislang unbekannt. Im Labor können UPOs ausschließlich unter Verwendung leguminosenhaltiger Kulturmedien induziert werden. Die induzierende Komponente aus Soja wurde in dieser Arbeit als proteinogen identifiziert. Eine zweite neue, extrazelluläre Hämperoxidase-Superfamilie ausserhalb der ClassII-Peroxidasen wurde im Totholz bewohnenden Pilz Bjerkandera adusta entdeckt. Die als DyP-type-Peroxidasen benannten Enzyme (DyP, EC 1.11.1.19) wurden später auch in anderen Pilzen gefunden, von denen in dieser Arbeit ebenso Nukleotidsequenzen erhalten wurden. Die phylogenetische Analyse ergab, dass pilzliche Sequenzen der DyP-type-Peroxidase-Superfamilie sehr ungleichmäßig sowie ausschließlich in den Genomen höherer Pilze (Dikarya) verteilt sind und vermutlich einen prokaryotischen Ursprung haben. Transkripte von UPO- und DyP-Genen wurden in nahezu allen untersuchten Laubstreuproben aus unterschiedlich stark genutzten Waldgebieten der Deutschen Biodiversitätsexploratorien nachgewiesen. Dies legt eine biologische Funktion dieser neuen Hämperoxidase-Superfamilien in entsprechenden Habitaten nahe.:Abkürzungsverzeichnis 1 1. Einleitung 5 2. Theoretische Grundlagen 7 2.1. Hämperoxidasen 7 2.1.1. Häm – Pigment des Lebens 7 2.1.2. Mechanismus der Hämperoxidase-vermittelten Katalyse 10 2.1.3. Systematik 16 2.2. Häm-Thiolat-Peroxidasen 36 2.3. DyP-type-Peroxidasen 38 3. Anliegen der Arbeit 41 4. Material und Methoden 43 4.1. Organismen 43 4.2. Chemikalien 53 4.3. Methoden 55 4.3.1. Kultivierung 55 4.3.2. Nukleinsäure-Isolation und cDNA-Synthese 56 4.3.3. PCR 57 4.3.4. Klonierung und DNA-Sequenzierung 62 4.3.5. Protein-Sequenzierung 62 4.3.6. Sequenzierungsstrategien 63 4.3.7. Genomsequenzierungen 73 4.3.8. Transkriptomsequenzierung 76 4.3.9. Phylogenetische Analysen 77 4.3.10. Vorhersage von Gen- und Protein-Eigenschaften 79 4.3.11. Photometrische Enzymaktivitätsmessung 80 4.3.12. Proteinkonzentrationsbestimmung 83 4.3.13. SDS-PAGE 83 4.3.14. Hämperoxidasen in der Streuschicht von Laubwäldern 83 4.3.15. UPO-Induktionsversuche 85 4.3.16. Partielle Charakterisierung sekretierter Peptidasen im Sojamedium 89 5. Ergebnisse 91 5.1. Häm-Thiolat-Peroxidasen 91 5.1.1. Sequenzen 91 5.1.2. Phylogenetische Analyse 110 5.1.3. UPO-Geninventar und UPO-Aktivität im Agrocybe-aegerita-Multispezieskomplex 113 5.1.4. Physiologie der UPO-Bildung in A. aegerita TM-A1 116 5.2. DyP-type-Peroxidasen 126 5.2.1. Sequenzen charakterisierter Enzyme 126 5.2.2. Sequenzen hypothetischer Enzyme 130 5.2.3. Phylogenetische Analyse 135 5.3. Genom- und Transkriptomsequenzierung von A. aegerita TM-A1 und AaN 137 5.4. Hämperoxidasen in Umweltproben 142 6. Diskussion 143 6.1. Sekretorische Peroxidasen aus Pilzen 143 6.2. Häm-Thiolat-Peroxidasen 144 6.2.1. UPO-Geninventar und -expression im Agrocybe-aegerita-Multispezieskomplex 147 6.2.2. Induktion der Unspezifischen Peroxygenase in A. aegerita TM-A1 150 6.2.3. Biologische Funktion 152 6.2.4. Phylogenetik 154 6.2.5. Cytochrom-P450-Enzyme 159 6.2.6. Ein Vorschlag zur Nomenklatur 165 6.3. DyP-type-Peroxidasen 166 6.3.1. Differentiell exprimierte Isoenzyme 166 6.3.2. Hypothetische Sequenzen 168 6.3.3. Biologische Funktion 168 6.3.4. Prokaryotischer Ursprung pilzlicher DyP-type-Peroxidasen 169 6.3.5. DyPs sind Teil der strukturellen CDE-Superfamilie 170 6.3.6. Heterologe Expression 171 7. Ausblick 173 8. Thesen 177 Literaturverzeichnis 179 A. Peptidsequenzen 225 B. Genspezifische Oligonukleotide 231 C. Verbreitung von HTP-Sequenzen 241 D. Verbreitung von DyP-Sequenzen 255 E. Charakterisierte ClassII-Peroxidasen 261 F. ClassII-Aktivitäten in Reinkulturen 267 G. Physiologie von A. aegerita TM-A1 in Sojamedien 271 H. Einfluss der Soja-Inhaltsstoffe auf die UPO-Produktion in A. aegerita TM-A1 275 I. Inhaltsstoffe von Sojamedien 283 J. Transkriptomanalyse A. aegerita TM-A1 285 K. Bakterielle DyP-type-Peroxidasen 289 L. Publikationen 293 Danksagung 371 Rechtliche Erklärungen 373 / For several decades ClassII peroxidases and chloroperoxidase have been the only known secretory heme peroxidases from fungi. In 2004, a novel heme peroxidase was isolated and characterized from the edible mushroom Agrocybe aegerita. This enzym, nowadays called unspecific peroxygenase (UPO, EC 1.11.2.1), combines characteristics of intracellular cytochrom P450 enzymes as well as extracellular classII fungal peroxidases. In the course of this PhD work, for the first time nuleotide sequences of UPO model organism A. aegerita as well as other UPO producing fungi were obtained and phylogenetically analyzed. The whole-genome sequences of two strains of A.aegerita were obtained. The results suggest that UPOs and the chloroperoxidase together represent a phylogenetically old protein superfamily (of heme-thiolate peroxidases) that is found in all true fungi (Eumycota), but is secondarily reduced in true yeasts and a few yeast-like growing basidiomycetes. The natural function of these enzymes remains unclear. In the laboratory, fungi secrete UPOs solely in legume-containing culture media. The eliciting component of the legume soybean has been determined as proteinogenic. A second novel heme peroxidase superfamily outside the classII peroxidases was discovered in deadwood inhabiting fungus Bjerkandera adusta. These so-called DyP-type peroxidases (DyP, EC 1.11.1.19) were later found expressed in several other fungi for which nucleotide sequences were obtained in this work, too. Phylogenetical analysis revealed that fungal DyP sequences are exclusively but very unequally distributed in genomes of higher fungi (Dikarya). Fungal DyP sequences are seemingly decended from prokaryotes. Transcripts encoding UPOs and DyPs were found in almost every sample of leave litter (derived from forests with different intensity of human usage) investigated. This suggests biological functions of these new heme peroxidase superfamilies in respective habitats.:Abkürzungsverzeichnis 1 1. Einleitung 5 2. Theoretische Grundlagen 7 2.1. Hämperoxidasen 7 2.1.1. Häm – Pigment des Lebens 7 2.1.2. Mechanismus der Hämperoxidase-vermittelten Katalyse 10 2.1.3. Systematik 16 2.2. Häm-Thiolat-Peroxidasen 36 2.3. DyP-type-Peroxidasen 38 3. Anliegen der Arbeit 41 4. Material und Methoden 43 4.1. Organismen 43 4.2. Chemikalien 53 4.3. Methoden 55 4.3.1. Kultivierung 55 4.3.2. Nukleinsäure-Isolation und cDNA-Synthese 56 4.3.3. PCR 57 4.3.4. Klonierung und DNA-Sequenzierung 62 4.3.5. Protein-Sequenzierung 62 4.3.6. Sequenzierungsstrategien 63 4.3.7. Genomsequenzierungen 73 4.3.8. Transkriptomsequenzierung 76 4.3.9. Phylogenetische Analysen 77 4.3.10. Vorhersage von Gen- und Protein-Eigenschaften 79 4.3.11. Photometrische Enzymaktivitätsmessung 80 4.3.12. Proteinkonzentrationsbestimmung 83 4.3.13. SDS-PAGE 83 4.3.14. Hämperoxidasen in der Streuschicht von Laubwäldern 83 4.3.15. UPO-Induktionsversuche 85 4.3.16. Partielle Charakterisierung sekretierter Peptidasen im Sojamedium 89 5. Ergebnisse 91 5.1. Häm-Thiolat-Peroxidasen 91 5.1.1. Sequenzen 91 5.1.2. Phylogenetische Analyse 110 5.1.3. UPO-Geninventar und UPO-Aktivität im Agrocybe-aegerita-Multispezieskomplex 113 5.1.4. Physiologie der UPO-Bildung in A. aegerita TM-A1 116 5.2. DyP-type-Peroxidasen 126 5.2.1. Sequenzen charakterisierter Enzyme 126 5.2.2. Sequenzen hypothetischer Enzyme 130 5.2.3. Phylogenetische Analyse 135 5.3. Genom- und Transkriptomsequenzierung von A. aegerita TM-A1 und AaN 137 5.4. Hämperoxidasen in Umweltproben 142 6. Diskussion 143 6.1. Sekretorische Peroxidasen aus Pilzen 143 6.2. Häm-Thiolat-Peroxidasen 144 6.2.1. UPO-Geninventar und -expression im Agrocybe-aegerita-Multispezieskomplex 147 6.2.2. Induktion der Unspezifischen Peroxygenase in A. aegerita TM-A1 150 6.2.3. Biologische Funktion 152 6.2.4. Phylogenetik 154 6.2.5. Cytochrom-P450-Enzyme 159 6.2.6. Ein Vorschlag zur Nomenklatur 165 6.3. DyP-type-Peroxidasen 166 6.3.1. Differentiell exprimierte Isoenzyme 166 6.3.2. Hypothetische Sequenzen 168 6.3.3. Biologische Funktion 168 6.3.4. Prokaryotischer Ursprung pilzlicher DyP-type-Peroxidasen 169 6.3.5. DyPs sind Teil der strukturellen CDE-Superfamilie 170 6.3.6. Heterologe Expression 171 7. Ausblick 173 8. Thesen 177 Literaturverzeichnis 179 A. Peptidsequenzen 225 B. Genspezifische Oligonukleotide 231 C. Verbreitung von HTP-Sequenzen 241 D. Verbreitung von DyP-Sequenzen 255 E. Charakterisierte ClassII-Peroxidasen 261 F. ClassII-Aktivitäten in Reinkulturen 267 G. Physiologie von A. aegerita TM-A1 in Sojamedien 271 H. Einfluss der Soja-Inhaltsstoffe auf die UPO-Produktion in A. aegerita TM-A1 275 I. Inhaltsstoffe von Sojamedien 283 J. Transkriptomanalyse A. aegerita TM-A1 285 K. Bakterielle DyP-type-Peroxidasen 289 L. Publikationen 293 Danksagung 371 Rechtliche Erklärungen 373
469

Study and Design of a DC-DC Converter for Third Generation Solar Cells

Lange, Sturla January 2018 (has links)
The perceived battery capacity of battery-powered devices can be increased by harvesting energy from readily available sources. Third generation solar cells are a good candidate for this purpose since they can be integrated with these battery-powered devices and harvest power from diffused light. For a single third generation solar cell to be useful in the context of charging a Lithium based battery, the voltage must be increased tenfold. To increase this perceived battery capacity as much as possible, efficiency is crucial. In this thesis, DCDC converter topologies and designs are studied from a system design perspective. The specifications of a converter suitable for interfacing Dye-Sensitised Solar Cells with Lithium batteries are described and a market research is conducted based on those specifications. A comparison of the available commercial solutions is presented, highlighting the most suitable options. However, none of the commercial solutions met the specifications to the full extent. The design process of two DC-DC converters is presented, one is a Boost converter operating in Continuous Conduction Mode and the other is a Boost converter operating in Discontinuous Conduction Mode. A comparison of the two designs highlights the advantages of operating the Boost converter in Discontinuous Conduction Mode when interfaced with a Dye-Sensitised Solar Cell. The design with a Boost converter operating in Discontinuous Conduction Mode has an efficiency of 80.3 % and is capable of tracking the Maximum Power Point of the Dye-Sensitised Solar Cell. / Den uppfattade batterikapaciteten hos batteridrivna enheter kan ökas genom att skörda energi från lättillgängliga källor. Tredje generationens solceller är en bra kandidat för detta ändamål eftersom de kan integreras med dessa batteridrivna enheter och skörda ström från spritt ljus. För att en enda tredje generationens solcell ska vara användbar i samband med laddning av ett litiumbaserat batteri måste spänningen ökas tiofaldigt. För att öka denna uppfattade batterikapacitet så mycket som möjligt är effektiviteten avgörande. I denna avhandling studeras topologier och strategier för DC-DC-omvandlare från ett systemdesignperspektiv. Specifikationerna för en omvandlare som är lämplig för att ansluta Dye-sensitized solceller med litiumbatterier beskrivs och en marknadsundersökning utförs utifrån dessa specifikationer. En jämförelse av de tillgängliga kommersiella lösningarna presenteras och belyser de lämpligaste alternativen. Ingen av de kommersiella lösningarna uppfyllde emellertid specifikationerna i sin helhet. Designprocessen för två DC-DComvandlare presenteras, en Boost-omvandlare som arbetar i kontinuerligt ledande läge och en Boost-omvandlare som arbetar i diskontinuerligt ledande läge. En jämförelse av de två designerna belyser fördelarna med att driva Boost-omvandlaren i diskontinuerligt ledningsläge när den kopplats till en färgkänslig solcell. Konstruktionen med en Boostomvandlare som arbetar i diskontinuerlig ledningsläge har en effektivitet på 80.3 % och kan spåra den maximala effektpunkten för solcellen.
470

Ultrafast photodynamics of ZnO solar cells sensitized with the organic indoline derivative D149

Rohwer, Egmont Johann 04 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The initial charge transfer from dye molecules' excited states to the conduction band of a semiconductor, after absorption of visible light by the former, is critical to the performance of Dye sensitized Solar Cells (DSC). In a ZnO-based DSC sensitized by the organic indoline derivative D149, the dynamics associated with charge transfer are investigated with femtosecond transient absorption spectroscopy. The time-resolved measurement of the photo-initiated processes reveal electron transfer rates corresponding to excited state lifetimes of 100s of fs, consistent with previously measured high absorbed photon to current conversion efficiencies. The photo-electrode measured as an isolated system shows decay times of bound electrons in excited states of the dye to be ~150 fs and shows the subsequent emergence of absorption bands of the oxidized molecules. When the I-/I-3 redox couple is added to the system, these excited state lifetimes change and are found to be dependent on the cation in the electrolytic solution. Small cations like Li+ reduce the excited state lifetime to sub-100 fs, whilst larger cations like the organic tetrabutylammonium result in longer lifetimes of 240 fs. The action of the electrolyte can be observed by the reduced lifetime of the oxidized dye molecules' absorption bands. The effect of operating parameters and changes in the production protocol of the DSC on the primary charge injection are also investigated and reported on. / AFRIKAANSE OPSOMMING: Die aanvanklike ladingsoordrag vanuit kleurstofmolekules' opgewekte toestande tot in die leidingsband van 'n halfgeleier, na absorpsie van sigbare lig deur eersgenoemde, is van kritiese belang vir die uitset van halfgeleier-gebaseerde sonkragselle wat met kleurstowwe vir absorpsie verhoging, gebind is. In hierdie werk word hierdie proses en verwante fotodinamika in die geval van 'n ZnO sonkragsel gekleur met indolien D149 ondersoek d.m.v femtosekonde-tydopgelosde absorpsiespektroskopie. Hierdie metings onthul elektron-oordragstempos wat ooreenstem met lewenstye van opgewekte toestande in die orde van 100 fs. Hierdie is met voorheen-bepaalde hoë foton-tot-stroom omskakelingsdoeltreffendheid ooreenkomstig. Die foto-elektrode, as geïsoleerde sisteem beskou, toon afvalstye van gebonde elektrone in opgewekte toestande van ~150 fs, en die gevolglike opkoms van absorpsie deur geoksideerde molekules word waargeneem. As die I-/I-3 redoks oplossing tot die sisteem bygevoeg word, verander die opgewekte toestande se afvalstye en toon 'n katioon-afhanklikheid. Klein katioone soos Li+ verkort die afvalstye tot onder 100 fs, terwyl groter katioone soos die organiese tetra-butielammonium langer afvalstye (240 fs) tot gevolg het. Die werking van die elektrolitiese oplossing kan waargeneem word deur die verkorte lewenstyd van die absorpsiebande wat aan die geoksideerde molekules toegeken is. Die uitwerking van operasionele parameter asook veranderinge in die produksie protokol op die primêre ladingsoordrag word ondersoek en verslag daarop word gelewer.

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