Hydrogen production from abundant renewable biomass would decrease reliance on crude oils, achieve nearly zero net greenhouse gas emissions, create more jobs, and enhance national energy security. Cell-free synthetic pathway biotransformation (SyPaB) is the implementation of complicated chemical reaction by the in vitro assembly of numerous enzymes and coenzymes that microbes cannot do. One of the largest challenges is the high cost and instability of enzymes and cofactors. To overcome this obstacle, strong motivations have driven intensive efforts in discovering, engineering, and producing thermostable enzymes. In this project, ribose-5-phosphate isomerase (RpiB), one of the most important enzymes in the pentose phosphate pathway, was cloned from a thermophile Thermotoga maritima, and heterologously expressed in Escherichia coli, purified and characterized. High-purity RpiB was obtained by heat pretreatment through its optimization in buffer choice, buffer pH, as well as temperature and duration of pretreatment. This enzyme had the maximum activity at 80°C and pH 6.5-8.0. It had a half lifetime of 71 h at 60°C, resulting in its turn-over number of more than 2 x108 mol of product per mol of enzyme. Another two thermostable enzymes glucose-6-phosphate dehydrogenase (G6PDH) and diaphorase (DI) and their fusion proteins G6PDH-DI and DI-G6PDH were cloned from Geobacillus stearothermophilus, heterologouely expressed in E. coli and purified through its His-tag. The individual proteins G6PDH and DI have good thermostability and reactivity. However, the presence of DI in fusion proteins drastically decreased G6DPH activity. However, a mixture of G6PDH and a fusion protein G6PDH-DI not only restored G6PDH activity through the formation of heteromultimeric network but also facilitated substrate channeling between DI and G6PDH, especially at low enzyme concentrations. My researches would provide important building blocks for the on-going projects: high-yield hydrogen production through cell-free enzymatic pathways and electrical energy production through enzymatic fuel cells. / Master of Science

Actor training, like the theatre in Brazil, has historically been a middle and upper class pursuit that followed European models, namely Stanislavski's system. Yet within Brazil there is a wealth of diverse cultures that are inherently theatrical and well suited for application in actor training. In this study I explore one such culture, the Afro Brazilian religion Umbanda. First, I examine its formation to illuminate how the religion itself performed (or served as a site for cultural interaction) throughout history. Then, I explore the practice of the religion both apart from and in relation to the theatre and Stanislavski's system. Using the archetypes of Umbanda as a base, I formulate a system of actor training that both allows access to a larger demographic of Brazilians, and also encourages cultural dialogue as an explicit part of acting process. I frame this study with two metaphors: anthropophagy, the notion of cannibalizing or consuming one culture by another; and, more specifically, the digestive tract. The anthropophagy movement in Brazil framed the country's thought throughout much of the 20th century; the digestive tract is a closer examination of the consuming process that epitomizes this system of actor training.

Le travail développé dans cette thèse concerne un type particulier de sources de positrons utilisant le rayonnement de canalisation dans un cristal ainsi que d’autres effets cristallins observes le long des axes du cristal ; ces effets produisent un grand nombre de photons qui, à leur tour, génèrent un grand nombre de paires e+e- dans une cible amorphe. Les photons et les paires sont créés dans deux cibles différentes séparées par une certaine distance permettant l’installation d’un aimant pour dévier les particules chargées avant la cible amorphe. Une telle source est appelée source hybride de positrons ; elle a été choisie par le CERN pour le projet CLIC. Ce type de sources présente de réels avantages par rapport aux cibles conventionnelles qui ont une grande emittance ainsi qu’un niveau important de dépôt d’énergie dans la cible.Apres un rappel des phénomènes physiques qui concernent notre étude, des simulations détaillées utilisant d’une part le programme de V .Strakhovenko pour les effets cristallins et d’autre part le code GEANT4 pour la génération des positrons conduisent à une description complète pour les photons et les positrons avec, notamment, les espaces de phase longitudinal et transverse, le spectre en énergie, la distribution temporelle,.. Nous avons particulièrement insiste sur deux points : d’abord sur les dispositifs de capture des positrons -après la cible- qui sont essentiels pour avoir de bons rendements de positrons acceptes et ensuite sur la densité de l’énergie déposée dans la cible qui représente un paramètre important pour la survie des cibles. En ce qui concerne le premier point, trois dispositifs de capture ont été étudiés : le système adiabatique (AMD), le système quart d’onde (QWT) et la lentille de lithium. Pour le deuxième point qui concerne l’énergie déposée et l’échauffement de la cible, on a cherché à optimiser la densité d’énergie déposée en diminuant son maximum (PEDD) ; l’énergie moyenne déposée a aussi été optimisée en utilisant une solution spéciale pour le convertisseur : un convertisseur granulaire forme de petites sphères, comme cela avait été considéré précédemment pour les usines à neutrinos. Des résultats très prometteurs nous ont conduits à envisager la source hybride de positrons avec un convertisseur granulaire comme une solution au difficile problème d’ILC. Cette solution est étudiée moyennant une transformation des impulsions du faisceau avant la cible, comme cela avait été envisage par l’équipe du KEK. Le transport du faisceau de positrons au-delà du solénoïde a été étudié avec la première partie de l’optique quadrupolaire. / The research work carried out for this PhD is concerning a special kind of positron source using channeling radiation and other crystal effects in an axially oriented crystal to generate a high number of photons which create, subsequently, a large number of pairs in an amorphous target. Photon generation and pair creation are developing in two targets separated by some distance allowing a sweeping magnet to get off the charged particles away from the amorphous converter. Such a scheme is called an hybrid positron source and has been adopted for the CLIC baseline. This kind of sources present big advantages with respect to the conventional sources where large emittance and important heat deposition are met. After some recall on the physical phenomena of interest for our study, detailed simulations are worked out using a special program dealing with crystal effects from Prof. Strakhovenko and the GEANT4 code; these tools led to a complete description of the positron source concerning the photons from one side and the positrons, from the other side, for which the main characteristics have been determined: transverse and longitudinal phase space, energy spectrum, time distribution,…Emphasis has been put on two points: first the matching devices capturing the positrons after the target which are essential for good accepted yields and the energy deposition density which is an important question for the reliability of the targets. Concerning the former point, three matching devices have been studied and their features compared: the Adiabatic Matching Device (AMD) largely used or considered for the positron sources, the Quarter Wave Transformer (QWT) and also the Lithium lens. For the latter point, related to the energy deposition and heating of the targets, we have tried to optimize the energy deposition density lowering its maximum value (PEDD); the average heat deposition has also been optimized using special converter material in granular shape, as considered for the neutrino factories. Very promising results allowed us to consider the hybrid positron source as an alternative to the difficult case of ILC; a special scheme for the transformation of the ILC beam pulses has been used, after KEK proposition. The positron beam transport has also been studied in the first part of the positron pre-accelerator including the solenoid and the first part of the quadrupole channel.

Fluid migration behind the cased holes is an important problem for oil and gas industry both considering short terms and long terms after cementing operation. For many reasons like high formation pressures, high shrinkage rate of cement slurry while setting, lack of mechanical seal, channeling due to cement slurry setting profile, hydrocarbon migration may occur and lead expensive recompletion operations and sometimes abandonment. Solutions to this problem vary including high density-low fluid loss cement slurry or right angle cement setting profile. During this study, the effect of &ldquo / free water&rdquo / which is the basic quality property of API G class cement, on fluid migration potential has been tested for different samples and in combination with different physical conditions. For this study API G class cements have been used. In order to justify the quality of each cement sample standard API G class quality tests were conducted. Moreover, as a main instrument &ldquo / Static Gel Strength Analyzer&rdquo / is used to measure the static gel strength of cement slurry and how long it takes to complete transition time. Bolu cement, Nuh cement, and Mix G cement samples were tested according to their free fluid values which are %2.5, %5, %3.12 respectively, and it is found that the Bolu cement with lowest free fluid content has the lowest potential for fluid migration. As a conclusion, fluid migration through behind the cased hole is a major threat for the life of the well. Appropriate cement slurry system may easily defeat this threat and lead cost saving well plans. Key words: Fluid migration, fluid loss, transition time, channeling, right angle, API G class cement, free water, high formation pressure

Low-energy X-rays in the range 10 - 50 keV have a wide application. One important application in radiological diagnostics is mammography, whereas, in radiotherapy, they are used for irradiation of superficial tumours, in brachytherapy and photon activation therapy. The importance of soft X-rays for fundamental radiobiological research is based on the fact, that all species of ionizing radiation produce a wide spectrum of secondary electrons, mainly responsible for the primary damage to be transformed into an observable radiobiological effect. By variation of the primary soft X-ray energy, a variation in the secondary electron spectra and therefore in the local energy deposition is provided. However, up to now no definitive conclusions about the relative biological effectiveness (RBE) of soft X-rays can be made due to its dependence on the photon energy, biological endpoint and dose range and the consequent large spread of the published data. The superconducting electron linear accelerator of high brilliance and low emittance (ELBE) at the Forschungszentrum Rossendorf with an electron energy up to about 40 MeV is used, among all, to generate X-rays in a wide energy range. One method for production of intensive, quasi-monochromatic X-rays in the energy range 10 - 100 keV tunable in energy, is by channeling of electrons in a perfect crystal. This X-ray source has many advantages over the most widespread X-ray source, which is the X-ray tube. Although the physical basis of the channeling effect has been previously investigated, the feasibility of an X-ray source based on channeling radiation (CR) for radiobiological studies has been for the first time theoretically and experimentally studied and a dedicated CR source built and optimised in the frame of this thesis. CR has been theoretically characterised in order to estimate its applicability for radiobiological studies. A good agreement between the theoretical predictions and the measured data has been found. The intrinsic properties of the CR source have led to the conclusion that monochromatisation is necessary. A monochromator based on HOPG mosaic crystals, was designed and manufactured. The dosimetrical methods have been investigated at the CR source as well as at an X-ray tube. Absolute dose measurements using an ionisation chamber and spectral dose distribution determination using semiconductor detectors have been performed. In addition, an unconventional system based on thermally stimulated exoelectron emission (TSEE) detectors, allowing to measure dose in a small volume and in the real cell environment has been tested and has proven itself appropriate in a variable dose range and in a liquid environment, in cases where reproducible laboratory conditions are provided. The biological endpoints clonogenic cell survival and micronucleus induction have been optimised for two established cell lines. The human mammary epithelial cells MCF-12A have been chosen due to the importance of RBE of soft X-rays for determination of risk from mammography. On the other hand, the use of the widespread mouse fibroblast cell line NIH/3T3 allows to compare the results with previously published data. The influence of the specific irradiation procedure at ELBE on the control level of cell survival and micronucleus induction has been tested and an irradiation system was developed and constructed. In addition, the RBE for soft X-rays was determined by X-ray tube irradiation at the Medical Department of Technische Universität Dresden. The RBE of 10 kV and 25 kV X-rays relative to 200 kV X-rays was determined. The RBE was found to be in the range from 1.0 to 1.4, depending on the used radiation quality, cell line and the biological endpoint, in agreement with previously published data for the same radiation qualities. These results confirm that systematical studies of RBE dependence on photon energy at the ELBE CR source are necessary and feasible.

Low-energy X-rays in the range 10 - 50 keV have a wide application. One important application in radiological diagnostics is mammography, whereas, in radiotherapy, they are used for irradiation of superficial tumours, in brachytherapy and photon activation therapy. The importance of soft X-rays for fundamental radiobiological research is based on the fact, that all species of ionizing radiation produce a wide spectrum of secondary electrons, mainly responsible for the primary damage to be transformed into an observable radiobiological effect. By variation of the primary soft X-ray energy, a variation in the secondary electron spectra and therefore in the local energy deposition is provided. However, up to now no definitive conclusions about the relative biological effectiveness (RBE) of soft X-rays can be made due to its dependence on the photon energy, biological endpoint and dose range and the consequent large spread of the published data. The superconducting electron linear accelerator of high brilliance and low emittance (ELBE) at the Forschungszentrum Rossendorf with an electron energy up to about 40 MeV is used, among all, to generate X-rays in a wide energy range. One method for production of intensive, quasi-monochromatic X-rays in the energy range 10 - 100 keV tunable in energy, is by channeling of electrons in a perfect crystal. This X-ray source has many advantages over the most widespread X-ray source, which is the X-ray tube. Although the physical basis of the channeling effect has been previously investigated, the feasibility of an X-ray source based on channeling radiation (CR) for radiobiological studies has been for the first time theoretically and experimentally studied and a dedicated CR source built and optimised in the frame of this thesis. CR has been theoretically characterised in order to estimate its applicability for radiobiological studies. A good agreement between the theoretical predictions and the measured data has been found. The intrinsic properties of the CR source have led to the conclusion that monochromatisation is necessary. A monochromator based on HOPG mosaic crystals, was designed and manufactured. The dosimetrical methods have been investigated at the CR source as well as at an X-ray tube. Absolute dose measurements using an ionisation chamber and spectral dose distribution determination using semiconductor detectors have been performed. In addition, an unconventional system based on thermally stimulated exoelectron emission (TSEE) detectors, allowing to measure dose in a small volume and in the real cell environment has been tested and has proven itself appropriate in a variable dose range and in a liquid environment, in cases where reproducible laboratory conditions are provided. The biological endpoints clonogenic cell survival and micronucleus induction have been optimised for two established cell lines. The human mammary epithelial cells MCF-12A have been chosen due to the importance of RBE of soft X-rays for determination of risk from mammography. On the other hand, the use of the widespread mouse fibroblast cell line NIH/3T3 allows to compare the results with previously published data. The influence of the specific irradiation procedure at ELBE on the control level of cell survival and micronucleus induction has been tested and an irradiation system was developed and constructed. In addition, the RBE for soft X-rays was determined by X-ray tube irradiation at the Medical Department of Technische Universität Dresden. The RBE of 10 kV and 25 kV X-rays relative to 200 kV X-rays was determined. The RBE was found to be in the range from 1.0 to 1.4, depending on the used radiation quality, cell line and the biological endpoint, in agreement with previously published data for the same radiation qualities. These results confirm that systematical studies of RBE dependence on photon energy at the ELBE CR source are necessary and feasible.

The dissociation of fast hydrogen and nitrogen molecular ions with kinetic energies ranging from 200 to 2000 eV/atom is studied for grazing collisions with various fcc metal surfaces. Within this energy range, the dissociation is either caused by electron capture into antibonding molecular states or by vibrational and rotational excitation. In contrast to hydrogen, nitrogen is chemically inert and interacts mainly elastically with the surfaces; thus there is no dissociation via electron capture. The processes of vibrational and rotational excitation are simulated using a molecular dynamics simulation with interaction potentials based on density functional theory. The comparison with the data obtained from Time-Of-Flight experiments reveals that an additional electronic effect has to be taken into account: The intramolecular bond of the molecules is softened due to electronic screening during the interaction with the surface. Hence, the softened molecules are more likely to dissociate through elastic collisions with surface atoms. The dissociation of hydrogen at low energies on metallic surfaces is dominated by electronic processes. An analysis of the kinetic energy distributions of the scattered dissociation products reveals information about the energy which is released during the dissociation process. The model of electronically induced dissociation is clearly confirmed by this method. However, an increasing contribution of additional mechanical processes becomes apparent at higher energies.

No description available.

No description available.

No description available.