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1
Johnston, Simon Richard. "Characterisation of basic lead(II) and tin(II) compounds from aqueous systems." Thesis, Brunel University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294510.
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Watson, Thomas Francis. "Tin Oxide Cluster Assembled Films: Morphology and Gas Sensors." Thesis, University of Canterbury. Physics and Astronomy, 2009. http://hdl.handle.net/10092/3160.
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In this thesis, investigations into fabricating tin oxide hydrogen gas sensors from films assembled by the deposition of tin clusters are reported. The tin clusters were formed in a UHV compatible cluster apparatus by DC magnetron sputtering and inert gas aggregation. Through SEM imaging, it was found that the morphology of tin cluster assembled films deposited onto silicon nitride substrates was highly coalesced. The coalescence between the clusters was significantly reduced by reacting the clusters with nitrogen before they were deposited. This resulted in granular films with a grain size close to that of the deposited clusters. The coalesced and granular tin films were used to fabricate tin oxide conducti-metric gas sensors. This was done by depositing the tin films onto gold contacts and then oxidising them by baking them at 250°C for 24 hours. The sensors were tested using a purpose built gas test rig. It was found that the sensors with the granular film morphology were much more sensitive to 500 ppm, 1000 ppm, and 5000 ppm of hydrogen at 200°C in ambient air with zero humidity. This was attributed to the smaller grain size and the larger surface area of the granular films.
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Machell, Jonathan Charles. "Structural and synthetic studies of compounds containing tin and the noble metals." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253417.
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Adolph, Marcus [Verfasser], Thomas [Akademischer Betreuer] Möller, and Tim [Akademischer Betreuer] Laarmann. "Cluster-light interaction and imaging of cluster growth processes / Marcus Adolph. Gutachter: Thomas Möller ; Tim Laarmann. Betreuer: Thomas Möller." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/1067386351/34.
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Quinan, Paulo Gustavo. "Engenharia de requisitos de stakeholders de sistemas de TIC na gestão do trabalho colaborativo do API.nano." Universidade do Estado de Santa Catarina, 2013. http://tede.udesc.br/handle/handle/48.
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Previous issue date: 2013-12-16Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
More than ever organizations are linking themselves in networks, and governments, aware of what can be gained with those connections, are developing incentives to foster its development. In Florianópolis, the promulgation of the Law of Innovation defined incentives to the formation of organizational networks, called Arranjos Promotores de Inovação (API). With that, the city s first API, the API.nano, started to be developed by CERTI, which invited LabGes/ESAG/UDESC to define the API s management and governance system, containing the system s business process mapping. In this context, this thesis details the development of a stakeholders requirement engineering of ICT systems capable of supporting the collaborative activities of the API.nano s organizations based in the process mapping developed. Supported by the literature about clusters of innovation, computer-supported cooperative work and requirement engineering, the research is divided in two phases. The first one constituted in the coding of the activities of the process mapping, which allowed their classification in 11 collaborative characteristics. Afterwards, a interpretative requirement analysis of the relationships exposed by the coding ensued. As a result, 30 stakeholders requirements were elicited. These requirements can the base for the definition of a ICT systems ecology capable of satisfying the collaborative work support technological needs of the API.
Cada vez mais organizações vem se ligando em redes, e os governantes, cientes dos ganhos obtidos com estas ligações, criam incentivos para fomentar seu desenvolvimento. Em Florianópolis, a promulgação da Lei da Inovação criou incentivos para a formação de redes organizacionais chamadas pela lei de Arranjos Promotores de Inovação (API). Com isso, o primeiro API da cidade, o API.nano, começou a ser desenvolvido pela Fundação CERTI, que convidou o LabGes/ESAG/UDESC a definir o sistema de gestão e governança do API, contendo um mapeamento de processos de negócio do sistema. Neste contexto, esta dissertação detalha o desenvolvimento de uma engenharia de requisitos de stakeholder de sistemas de TIC capazes de auxiliar as atividades colaborativas das organizações do API.nano com base no mapeamento de processos desenvolvido. Fundamentada pela literatura sobre clusters de inovação, sistemas de TIC no trabalho colaborativo e engenharia de requisitos, a pesquisa se dividiu em duas etapas. A primeira consistiu numa codificação das atividades do mapeamento de processos, que permitiu a classificação das atividades em 11 características colaborativas. Em seguida, uma análise de requisitos interpretativa foi realizada nas relações expostas pela codificação. Como resultado, 30 requisitos de stakeholders foram propostos. Estes requisitos podem servir de base para a definição de uma ecologia de sistemas de TIC capaz de satisfazer as necessidades tecnológicas de suporte do trabalho colaborativo do API.
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Süß, Tim [Verfasser], and auf der Heide Friedhelm [Akademischer Betreuer] Meyer. "Parallel real-time rendering using heterogeneous PC clusters / Tim Süß. Betreuer: Friedhelm Meyer auf der Heide." Paderborn : Universitätsbibliothek, 2011. http://d-nb.info/1036510972/34.
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Matsutsu, Molefi. "Pt and Pt-Pd cluster interaction with graphene and TiO₂ based supports: A DFT study." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22922.
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Density functional theory (DFT) calculations have been performed to gain insight into the role of defects present on the surface of graphene and TiO₂ based supports on supported metal clusters. The clusters considered are a Pt₃₈ cluster and a bimetallic Pt₃₂Pd₆ alloy. The defects considered on graphene based supports are monovacancy defective graphene, OH and COOH functionalised graphene. The defects considered on TiO₂ based supports are a partially reduced TiO₂(110) surface with a surface oxygen bridge vacancy and hydroxylated TiO₂(110) surface with surface OH groups. The defect free graphene and TiO₂ surfaces were also considered. For both the Pt₃₈ and Pt₃₂Pd₆ cluster, and on both defect containing graphene and TiO₂ (except on hydroxylated TiO₂(110) surface) the binding of the clusters is enhanced relative to binding on the defect free supports. Enhanced binding at the defects imply that the clusters are bound strongly to the support and thus less likely to detach from the support material relative to binding on the defect free supports. Therefore, the defects may improve the durability of the catalyst by limiting particle detachment. The electronic properties of the cluster are modified differently depending on the identity of the defect present on the support. On the graphene based supports, OH functionalisation is expected to result in weaker binding energy of adsorbate molecules, whereas COOH functionalisation is expected to result in stronger binding energy of adsorbates for the supported Pt₃₈ cluster. This is due to different shifts in d-band centre of the facets on the cluster supported on these supports. Therefore, it can be expected that the Pt₃₈ cluster supported on OH functionalised graphene will be more tolerant to poison molecules. This is due to reduced binding strength of adsorbates on OH functionalised graphene compared to adsorption on COOH functionalised graphene. For the Pt₃₂Pd₆ cluster the OH and COOH functional groups do not appreciably modify the d-band centre of the facets available to reactants, and thus is expected not to significantly modify the binding strength of adsorbate molecules relative to binding on the free unsupported Pt₃₂Pd₆ cluster. The binding energy of adsorbate molecules on the Pt₃₈ cluster supported on defect containing TiO₂ is expected to be stronger than on the Pt₃₈ cluster supported on defective graphene based supports, due to higher extent of upward shift of the d-band centre of the exposed facets. The enhanced binding energy of adsorbates on the Pt₃₈ cluster supported on TiO₂ supports may be detrimental to catalyst durability and activity. This can be due to strong binding of poison molecules and reaction intermediates which maybe too strongly bound on the surface such that they cannot participate in further reaction steps. Overall it might turn out that the functionalised graphene based supports are better support materials over the TiO₂ based materials for particular reactions. The Nb-doped partially reduced TiO₂(110) surface attaches the Pt₃₂Pd₆ cluster strongly to the support compared to the functionalised graphene supports. Furthermore, the binding energy of adsorbate molecules is expected to be weaker on the Pt₃₂Pd₆ cluster supported on the Nbdoped partially reduced TiO₂(110) surface compared to the functionalised graphene supports. This might be beneficial as poison molecules may be weakly bound to the cluster resulting in high resistance to poisoning which can also have a positive effect on catalyst activity. In addition to enhancing binding of the cluster to the support and affecting the binding energy of adsorbates on the supported clusters, some of the defects can also alter the ordering pattern of Pd and Pt atoms within the Pt₃₂Pd₆ cluster. OH functionalised graphene and Nbdoped partially reduced TiO₂(110) surface result in segregation of Pd towards the clustersupport interface, thereby exposing more Pt atoms at the surface facets of the cluster. The modified arrangement of Pt and Pd atoms may result in modification of the reactivity of the Pt₃₂Pd₆ cluster. The results of this study indicate that the defects can play a vital role in determining the activity and durability of the catalyst. By having the right combination of defects on the support material, the durability and catalytic activity of the catalyst can be fine-tuned simultaneously. This can lead to better design of catalysts.
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Potier, François. "Réticulation dynamique de polymères par des nanobriques inorganiques : nouveaux matériaux hybrides autoréparants et thermoformables." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066323/document.
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Le cluster d’étain [(BuSn)12O14OH6]AMPS2 a servi de nanobrique pour l’élaboration de matériaux auto-réparants et themoformables. Le matériau hybride synthétisé est un élastomère capable de récupérer l’ensemble de ses propriétés mécaniques après avoir subi un endommagement mécanique, allant de la fissure de quelques μm à un endommagement drastique. En plus d’être réparable le matériau est recyclable, ce qui est un comportement exceptionnel pour un élastomère. Les liaisons ioniques entre le cœur du cluster et ses ligands qui connectent entre elles les chaînes macromoléculaires sont à la fois suffisamment fortes pour permettre de réticuler les chaînes et d’atteindre les propriétés d’un élastomère et suffisamment labiles pour permettre au réseau d’être dynamique. Les propriétés mécaniques des matériaux ont été évaluées mettant en évidence la nature dynamique du réseau à l’échelle macroscopique. La RMN DOSY a permis de mettre en évidence la dynamique dans le réseau à l’échelle moléculaire confirmant le rôle du cluster. Afin d’obtenir des matériaux avec des modules mécaniques élevés, des copolymères constitués de blocs rigides de polystyrène et de blocs souples de poly(acrylate de n-butyle) au sein duquel le cluster fonctionnel a été incorporé assurant la réticulation dynamique du matériau ont été synthétisé par polymérisation RAFT . Ces systèmes possèdent des propriétés de réparation thermostimulée, de thermoformage et peuvent être recyclés, contrairement aux élastomères thermoplastiques conventionnels. Cette stratégie de synthèse permet d’augmenter le module élastique G’ de 0,1 MPa pour l’élastomère à 500 MPa pour les copolymères tout en conservant un caractère dynamiqueA butyltin oxo-cluster macrocation, [(BuSn)12O14(OH)6]AMPS2, has been chosen as the Nano Building Block to create self-healing and malleable materials. The functional ligands enable the cluster to ionically cross-link poly(n-butyl acrylate) chains. The resulting hybrid material is an elastomer possessing properties which enable it to recover from damages: from a few μm depth cut to a dramatic failure. In addition, this material is recyclable, which is an exceptional property for an elastomer. The origin of the dynamic behavior is the ionic interaction between the cluster core and its ligands which are connected by macromolecular chains. Such interactions are strong enough to cross-link the polymer and consequently exhibit rubber-like elasticity behavior as well as render it labile enough to allow dynamic bond recombination leading to a dynamic network. Mechanical properties of the material (DMTA, Tensile Tests, and Relaxation Tests) have been evaluated and verify the macroscopic dynamic nature of the network. DOSY NMR experiments demonstrate the molecular dynamic of the networks, attesting the key role of the cluster. Concentrating on the development of high mechanical modulus materials with dynamic network, copolymers using hard blocks made of polystyrene and soft blocks of poly(n-butyl acrylate) which are cross-linked by the cluster have been synthetized. Such materials have thermo-stimulated healing properties, can be recycled, and are malleable, which is not the case for conventional thermoplastics. This synthesis strategy enables to raise the elastic modulus of the elastomer from 0.1 MPa to 500 MPa while maintaining the co-polymers dynamic properties
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Anders, Peter. "Formation and evolution of star clusters in interacting galaxies." Doctoral thesis, [S.l.] : [s.n.], 2006. http://webdoc.sub.gwdg.de/diss/2006/anders.
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Santos, Acassio Rocha. "Estudo de clusters met?licos de alum?nio-s?dio, alum?niopot?ssio, alum?nio-l?tio e s?dio-l?tio pelas abordagens de algoritmos gen?ticos, c?lculos qu?nticos e an?lise topol?gica." PROGRAMA DE P?S-GRADUA??O EM QU?MICA, 2017. https://repositorio.ufrn.br/jspui/handle/123456789/23542.
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O estudo te?rico de clusters met?licos tem despertado um interesse consider?vel, devido ? possibilidade de criar novas ligas de materiais em nanoescala, as chamadas "nanoligas". Pesquisas sobre nanoligas desempenham papel significativo na Ci?ncia de Materiais, pois, entre seus objetivos mais importantes, est?o o de prever a estabilidade das estruturas, seus modos de crescimento, bem como o de auxiliar a interpreta??o de medidas espectrosc?picas e outras medi??es experimentais. Nesse contexto, um grande n?mero de m?todos foi relatado nos ?ltimos anos para a otimiza??o do m?nimo global de grupos at?micos e moleculares, sendo um dos mais utilizados atualmente o do Algoritmo Gen?tico (doravante, GA), o qual baseia-se em princ?pios relacionados a processos evolutivos, em operadores inspirados na Teoria da Evolu??o e na Gen?tica, isto ?, na recombina??o, muta??o e sele??o natural. Particularmente, o GA com a implementa??o do potencial Gupta tem se mostrado eficiente na busca de solu??es ??timas? em problemas de otimiza??o de clusters met?licos. Esta disserta??o ? composta por cap?tulos de introdu??o, de metodologia, de abordagem te?rica (Cap. 1, 2 e 3); e tamb?m por cap?tulos que cont?m artigos sobre o tema proposto (Cap. 4, 5 e 6). No primeiro artigo (Cap. 4), analisaram-se clusters bimet?licos AlxNay (x+y?55) por meio da aplica??o do GA com a implementa??o do potencial Gupta. Com base tamb?m na aplica??o do GA, no segundo cap?tulo (Cap. 5) foram estudados clusters de AlxLiy e AlxKy (x+y ? 55). Em ambos os trabalhos, para elevar a efici?ncia do GA, introduziu-se mais dois operadores: o Aniquilador e o Hist?ria. Ao serem comparadas as estruturas obtidas por meio do GA com potencial Gupta para clusters de alum?nio puro, l?tio puro e alum?nio-l?tio com resultados recentes da literatura, verificou-se que para os sistemas Al2, Al3, Al6, Al8, Al9, Li5, Li6, Li7, Al1Li5, Al1Li7 e Al1Li8 as geometrias obtidas foram muito semelhantes ?quelas resultantes de c?lculos de funcional de densidade e ab initio[como CCSD(T)]. No terceiro artigo (Cap. 6), analisou-se um novo algoritmo gen?tico qu?ntico (Q-GA) para pequenos sistemas de clusters NaxLiy com (x+y ? 10). Constatou-se que o Q-GA apresenta maior efici?ncia na busca do m?nimo global em rela??o ao GA com o potencial Gupta. Isso porque o primeiro utiliza m?todo qu?ntico, enquanto o segundo usa um m?todo cl?ssico. Por ser mais preciso, o Q-GA possui uma abrang?ncia menor. Neste artigo, al?m de c?lculos ab inito, tamb?m foram realizados c?lculos topol?gicos a partir da Teoria Qu?ntica de ?tomos em Mol?culas (QTAIM) para as estruturas Na1Li5, Na2Li4, Na3Li3, Na4Li2 e Na5Li1, obtidas pelo Q-GA. Nessas estruturas, chama a aten??o o fato de n?o haver caminho de liga??o envolvendo diretamente os metais, sendo unidos por pseudo?tomos, com exce??o do Na5Li1. Algumas intera??es at?micas n?o foram indicadas pelo caminho de liga??o e sua an?lise foi feita pelo ?ndice de deslocaliza??o (DI). No sistema Na1Li5, os pares at?micos Na1-Li2 e Na1-Li6 t?m as intera??es mais fortes (e equivalentes ? do sistema NaLi) de todos os pares Na-Li de todos clusters NaxLiy(x+y=6); ao mesmo tempo, os outros pares Na-Li t?m intera??es dez vezes mais fracas do que aquelas do sistema NaLi. As intera??es Na-Na dos clusters Na4Li2 e Na5Li1 s?o as mais fortes quando comparadas com sistemas puros. Por fim, verificou-se que a f?rmula do grau de degeneresc?ncia do ?ndice de aromaticidade D3BIA e a carga at?mica indicaram que os ?tomos de l?tio mais pr?ximo ao ?tomo de s?dio transferem carga para esse ?ltimo.
The theoretical study of metal clusters has drawn considerable interest due to the possibility of creating new alloys from materials in nanoscale, the so-called "nanoalloys". Research on nanoalloys has had an important role in materials science, since, among some of its most relevant objectives, we may find the prediction of stability in structures, their manners of growth and further assistance in the interpretation of spectroscopic and other experimental measures. In this context, several methods have been reported in the last few years towards the global minimum optimization of atomic and molecular groups, where the Genetic Algorithm (henceforth GA) is currently considered one of the most used methods, whilst based on principles related to evolutionary processes as well as operators inspired by the Theory of Evolution and Genetics, i. e., by recombination, mutation and natural selection. The GA method in particular, and altogether with the implementation of the Gupta potential, has become efficient in the search for ?optimal? solutions for optimization problems in metallic clusters. The present dissertation is composed of chapters consisting of introduction, methodology and theoretical considerations (Chap. 1, 2 and 3), as well as of chapters containing articles on the proposed subject (Chap. 4, 5 and 6). In the first article (Chap. 4), we may find the analysis of AlxNay (x + y ? 55) bimetallic clusters through the Genetic Algorithm method with the implementation of the Gupta potential. Also based on the GA application, in the following chapter (Chap. 5) we may find a study regarding AlxLiy e AlxKy (x+y ? 55) clusters. In both works, in order to improve GA efficiency, two additional operators have been introduced: Annihilator and History. By being compared to structures obtained by means of GA with Gupta potential for pure aluminum, pure lithium and aluminum-lithium clusters in recent results from literature, it has been verified that, regarding systems Al2, Al3, Al6, Al8, Al9, Li5, Li6, Li7, Al1Li5, Al1Li7 e Al1Li8, the obtained geometries were very similar to those resulting from density functional and ab initio calculations [such as CCSD(T)]. In the third chapter (Chap. 6), we analyzed a new quantum genetic algorithm (QGA) for small cluster systems NaxLiy with (x+y ? 10). It has been observed that Q-GA presents an improved efficiency towards a global minimum regarding the GA with the Gupta potential. That has been the case since the former uses the quantum method, while the latter uses a classic method. More specifically, the Q-GA has a narrower scope. In this article, besides ab initio calculations, topological calculations were performed as well, grounded on the Quantum Theory of Atoms in Molecules (QTAIM) for the structures Na1Li5, Na2Li4, Na3Li3, Na4Li2 e Na5Li1 obtained by the Q-GA. In these structures, it is evident that there is no bonding path between the metals, since they are bonded by pseudo atoms, with the exception of the Na5Li1. Some of the atomic interactions have not been suggested by the bonding path, being their analysis performed according to the delocalization index (DI). In the Na5Li1 system, the atomic pairs Na1-Li2 and Na1-Li6 have the strongest interactions (equivalent to the NaLi system) of all Na-Li pairs in all of the NaxLiy (x+y=6) clusters; concurrently, other Na-Li pairs bear interactions ten times weaker than those from the NaLi system. The Na-Na interactions from the clusters Na4Li2 e Na5Li1 are stronger when compared to pure systems. Finally, it has been verified that the degree of degeneracy formula of the aromaticity index D3BIA and the atomic charge suggest that the lithium atoms that are closer to the sodium atom transfer charge to the latter.
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Berkesten, Hägglund Patrik. "An Experimental Study on Global TurbineArray Eects in Large Wind Turbine Clusters." Thesis, KTH, Mekanik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202630.
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It is well known that the layout of a large wind turbine cluster aects the energyoutput of the wind farm. The individual placement and distances betweenturbines will in uence the wake spreading and the wind velocity decit. Manyanalytical models and simulations have been made trying to calculate this, butstill there is a lack of experimental data to conrm the models. This thesis isdescribing the preparations and the execution of an experiment that has beenconducted using about 250 small rotating turbine models in a wind tunnel. Theturbine models were developed before the experiment and the characteristicswere investigated. The main focus was laid on special eects occurring in largewind turbine clusters, which were named Global Turbine Array Eects.It was shown that the upstream wind was little aected by a large windfarm downstream, even though there existed a small dierence in wind speedbetween the undisturbed free stream and the wind that arrived to the rstturbines in the wind farm. The dierence in wind speed was shown to beunder 1% of the undisturbed free stream. It was also shown that the densityof the wind farm was related to the reduced wind velocity, with a more densefarm the reduction could get up to 2.5% of the undisturbed free stream at theupstream center turbine. Less velocity decit was observed at the upstreamcorner turbines in the wind farm.When using small rotating turbine models some scaling requirements hadto be considered to make the experiment adaptable to reality. It was concludedthat the thrust coecient of the turbine models was the most important parameterwhen analysing the eects. One problem discussed was the low Reynoldsnumber, an eect always present in wind tunnel studies on small wind turbinemodels.A preliminary investigation of a photo measuring technique was also performed,but the technique was not fully developed. The idea was to take oneor a few photos instantaneously and then calculate the individual rotationalspeed of all the turbine models. It was dicult to apply the technique becauseof uctuations in rotational speed during the experiment, therefore thecalculated values could not represent the mean value over a longer time period.
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Holch, Tim Lukas [Verfasser]. "Exploring the γ-ray sky around the stellar cluster Westerlund 2 with the H.E.S.S. Experiment / Tim Lukas Holch." Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1228333351/34.
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Halloran, Kevin T. "Exploring the Role of Large Clusters of Branched Aliphatic Residues on the Folding Free Energy Landscape of (βα)8 TIM Barrel Proteins." eScholarship@UMMS, 2011. http://escholarship.umassmed.edu/gsbs_diss/935.
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(βα)8 TIM barrel proteins are one of the most common structural motifs found in biology. They have a complex folding free energy landscape that includes an initial off-pathway intermediate as well as two on-pathway intermediates. The formation of these intermediates is hypothesized to be driven by large clusters of the branched chain amino acids, isoleucine, leucine, and valine (ILV).
All-atom MD simulations and circular dichroism experiments on polar mutants of the hydrophobic clusters of α-Trp synthase, a TIM barrel protein, revealed the importance of dehydrating the clusters on intermediate states. Custom, single-piece microfluidic chips were interfaced with small angle x-ray scattering and time resolved FRET experiments to monitor the role of a large ILV cluster on the microsecond timescale in a second TIM barrel protein, sIGPS. Dimensional analysis of the initial misfolded intermediate showed an ILV cluster was responsible for the initiation of structure in the intermediate. Early structure formation in the ILV cluster was confirmed by coarse grained simulations. Native state hydrogen exchange experiments were used to probe the higher energy species that are in equilibrium with the native state. Results from the NMR experiment complement the kinetic studies as the core of stability found by NMR mapped back to the same region of the ILV cluster that was found to initiate folding.
When taken together, the results show the importance of hydrophobic clusters on the entire free energy surface of TIM barrel proteins.
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Halloran, Kevin T. "Exploring the Role of Large Clusters of Branched Aliphatic Residues on the Folding Free Energy Landscape of (βα)8 TIM Barrel Proteins." eScholarship@UMMS, 2017. https://escholarship.umassmed.edu/gsbs_diss/935.
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(βα)8 TIM barrel proteins are one of the most common structural motifs found in biology. They have a complex folding free energy landscape that includes an initial off-pathway intermediate as well as two on-pathway intermediates. The formation of these intermediates is hypothesized to be driven by large clusters of the branched chain amino acids, isoleucine, leucine, and valine (ILV).
All-atom MD simulations and circular dichroism experiments on polar mutants of the hydrophobic clusters of α-Trp synthase, a TIM barrel protein, revealed the importance of dehydrating the clusters on intermediate states. Custom, single-piece microfluidic chips were interfaced with small angle x-ray scattering and time resolved FRET experiments to monitor the role of a large ILV cluster on the microsecond timescale in a second TIM barrel protein, sIGPS. Dimensional analysis of the initial misfolded intermediate showed an ILV cluster was responsible for the initiation of structure in the intermediate. Early structure formation in the ILV cluster was confirmed by coarse grained simulations. Native state hydrogen exchange experiments were used to probe the higher energy species that are in equilibrium with the native state. Results from the NMR experiment complement the kinetic studies as the core of stability found by NMR mapped back to the same region of the ILV cluster that was found to initiate folding.
When taken together, the results show the importance of hydrophobic clusters on the entire free energy surface of TIM barrel proteins.
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Senmartí, Senmartí Xavier. "Ingenierías tecnológicas versus ingenierías multimedia: estudio de perfiles aplicando la metodología de sistemas consistentes de clústeres." Doctoral thesis, Universitat Ramon Llull, 2010. http://hdl.handle.net/10803/9153.
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El present treball de recerca tracta de determinar las diferencies acadèmiques existents entre els estudiants d'enginyeries purament tecnològiques i els d'enginyeria multimèdia, que combina tecnologia amb continguts de l'àrea d'humanística i ciències socials. En particular, es restringeix al cas dels plans d'estudi de La Salle, que estan emmarcats en l'àmbit de las tecnologies de la informació i la comunicació, el seu sistema de tutories, l'evolució dels alumnes durant el curs i el rendiment manifestat en les diferents proves d'avaluació.Davant del poc rendiment de proves estadístiques de correlació i factorització, la novetat metodològica d'aquesta tesi consisteix en la creació d'una metodologia denominada Sistemes consistents de clústers. Aquesta metodologia realitza estudis d'evolució de clústers mitjançant diverses mesures. Es diferencia d'estudis tipus clústers dinàmics per la seva visió transversal i no longitudinal de les variables que han evolucionat en el temps i, a més, considera uns estats de referència separats en el temps, per la qual cosa es basa en un sistema discret de mesures.
La metodologia dels Sistemes consistents de clústers redueix el problema de l'evolució dels clústers resultants en mesures successives, a un problema de cadenes de Markov i a proves simples de significació (Chi quadrat), per tant es pot exportar a recerques de ciències socials al poder ser explicat en termes de proves estadístiques habituals en les recerques d'aquest tipus.
El resultat de la tesi ens mostra com la dinàmica evolutiva dels estudiants d'enginyeries anomenades "tecnològiques pures" és totalment diferent dels estudiants de multimèdia. S'obtenen sistemes de clústers completament diferents encara que comparteixen certa evolució comú a causa de la intervenció correctora i assistencial del Centre en el seu sistema de tutories. De la recerca resulten també directrius per a l'assistència a l'estudiant en aquestes titulacions i es constaten algunes sospites pel que fa al procediment d'aprenentatge que fins ara eren només conjectures.
La presente investigación trata de determinar las diferencias académicas existentes entre los estudiantes de ingenierías puramente tecnológicas y los de ingeniería multimedia, que combina tecnología con contenidos del área de humanística y ciencias sociales. En particular, se restringe al caso de los planes de estudio de La Salle, que están enmarcados en el ámbito de las tecnologías de la información y la comunicación, su sistema de tutorías, la evolución de los alumnos durante el curso y el rendimiento manifestado en las diferentes pruebas de evaluación.
Ante el poco rendimiento de pruebas estadísticas de correlación y factorización, la novedad metodológica de esta tesis consiste en la creación de una metodología denominada Sistemas consistentes de clústeres. Dicha metodología realiza estudios de evolución de clústeres a lo largo de diversas mediciones. Se diferencia de estudios tipo clústeres dinámicos por su visión transversal y no longitudinal de las variables que han evolucionado en el tiempo y, además, considera unos estados de referencia separados en el tiempo, por lo que se basa en un sistema discreto de mediciones.
La metodología de los Sistemas consistentes de clústeres reduce el problema de la evolución de los clústeres resultantes en mediciones sucesivas, a un problema de cadenas de Markov y a pruebas simples de significación (Chi cuadrado), por lo que puede exportarse en investigaciones de ciencias sociales al poder ser explicado en términos de pruebas estadísticas habituales en las investigaciones de este tipo.
El resultado de la tesis nos muestra como la dinámica evolutiva de los estudiantes de ingenierías llamadas "tecnológicas puras" es totalmente diferente de los estudiantes de multimedia. Se obtienen sistemas de clústeres completamente diferentes aunque comparten cierta evolución común debida a la intervención correctora y asistencial del centro en su sistema de tutorías. De la investigación resultan también directrices para la asistencia al estudiante en estas titulaciones y se constatan algunas sospechas sobre el procedimiento de aprendizaje que hasta ahora eran sólo conjeturas.
The aim of the present research work is to determine the academic differences between technological-engineering students and multimedia students, who combine technology with humanistic and social contents. It specifically involves La Salle study plans, which are focused on information and communication technologies, their tutorial system and the students evolution and their academic performance along the year.
Looking at the low performance of correlation and factorization statistical tests, this thesis presents an innovation in methodology that consists in what is called Systems of clusters. This methodology performs tests in clusters evolution through different kind of measures. The difference between them and dynamic clusters is caused by the transversal and not by the longitudinal vision of the variables that have evolved through time and, moreover, it considers a reference status separately from time, so it is based on a discreet system of measures.
The high potential of this methodology is the advantage of reducing the problem of clusters evolution that comes from successive measures to a problem of Markov chain and simple test of signification (Chi-square), so there is the open possibility to export it to social research as it is possible to be explained in terms of statistical methods usually used in these research fields.
The thesis results show that the dynamic evolution of engineering students of the strong technological branch is totally different from multimedia students. The Systems of clusters obtained are completely different, even though they share some common evolution due to the corrective and mentoring intervention of the University in their tutorial system. From the research, it is also important to highlight the directives obtained in order to assist the student in the degree and some suspects about the learning process are confirmed.
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Ferreira, Antonio Cesar. "CORRECAO DO POTENCIAL MUFFIN-TIN: ANTISITIO EM GaAs." Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-08062015-155921/.
Full textAbstract:
Devido à inconfiabilidade do modelo EM-X?, no cálculo da energia total, consideramos uma correção na densidade de carga \"muffin-tin\". Com esta correção podemos ajustar a energia total, a partir de parâmetros definidos na teoria. O objetivo deste trabalho é o estudo da curva da energia total associada ao estado excitado do sistema GaAs: AsGa, quando o átomo substitucional de As se desloca na direção . Partindo de cálculos de primeiros princípios (LARGE UNIT CELL APPROACH), reproduzimos a curva da energia total do estado fundamental. A partir dos parâmetros encontrados na correção não \"muffin-tin\" da densidade de carga, calculamos a curva do estado excitado utilizando o conceito de estado de transição de Slater. Nossos resultados mostraram que o efeito Jahn-TeIler não ocorre para defeitos tipo antisítio. Vimos também que a curva do comportamento dos autovalores com o deslocamento do átomo substitucional, está de acordo com cálculos recentes encontrados na literatura.Since total energy calculations within the Multiple Scattering-X? model are not reliable, a non \"muffin-tin\" correction to the charge density has been considered. With this correction the total energy can be adjusted through parameters defined in the theory. The aim of this work is to study the total energy curve of the excited state of the GaAs: AsGa system when the arsenic substitutional atom is displaced in the direction. As a first step, the ground-state total energy curve obtained from first-principles calculations (LARGE UNIT CELL APPROACH) was reproduced. From the parameters found for the non \"muffin-tin\" charge density corrections, we have calculated the excited-state total energy curve by using the Slater transition-state concept. Our results show that the Jahn-Teller effect is not expected to occur for antisite-like defects. Moreover, the obtained behavior of the eigenvalues with displacement of the substitutional atom is in fairly good agreement with recent theoretical calculations found in the literature.
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Baba, Haj Samer [Verfasser], Klaus [Akademischer Betreuer] Jurkschat, and Stefanie [Gutachter] Dehnen. "Functionalized organotin compounds as synthons for tin-containing heterocycles and periphery functionalized organotinoxo clusters / Samer Baba Haj. Betreuer: Klaus Jurkschat. Gutachter: Stefanie Dehnen." Dortmund : Universitätsbibliothek Dortmund, 2015. http://d-nb.info/1102268992/34.
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Yang, Chi-Ta. "Interplays of CO2, Subnanometer Metal Clusters, and TiO2: Implications for Catalysis and CO2 Photoreduction." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5805.
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This research is motivated by two significant challenges facing the planet: reducing the emission of CO2 to the atmosphere and production of sustainable fuels by harnessing solar energy. The main objective of this work is the study of promising photocatalysts for CO2 reduction. DFT modeling of CO2, subnanometer Ag&Pt clusters, and anatase TiO2 (101) surface is employed to gain fundamental understanding of the catalytic process, followed by validation using a guided experimental endeavor. The binding mechanism of CO2 on the surface is investigated in detail to gain insights into the catalytic activity and to assist with characterizing the photocatalyst. For CO2 photoreduction, the cluster induced sub-bandgap and the preferred adsorbate in the first and key step of the CO2 photoreduction are explored.
It is found that TiO2-supported Pt octamers offer key advantages for CO2 photoreduction: 1. by providing additional stable adsorption sites for favored CO2 species in the first step, and 2. by aiding in CO2- anion formation. Electronic structure analysis suggests these factors arise primarily from the hybridization of the bonding molecular orbitals of CO2 with d orbitals of the Pt atoms. Also, structural fluxionality is quantified to investigate geometry dependent (3D-2D) CO2 adsorption. Geometric information, electronic information, and C-O bond breaking tendency of adsorbed CO2 species are proposed to connect to experimental observables (IR frequency). The CO2 adsorption sites on supported Pt clusters are also identified using IR as the indicator. A cluster-induced CO2 dissociation to CO pathway is also discovered. Finally, experimental work including dendrimer-encapsulated technique, TPD, and UV-Vis is performed to validate the computational results, the availability of adsorption sites and CO2 binding strength on supported Pt clusters.
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Westgaard, Hilde Kristin, and Petter Lexander. "Klyngeinitiativ i Hedmark : Praktiske tilnærminger til klyngeinitiativ og utvikling av regionale innovasjonssystem - og graden av behov for management i ulike staider av prosessen. To eksempler fra Hedmark Fylke." Thesis, Karlstad University, Faculty of Economic Sciences, Communication and IT, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-488.
Full textAbstract:
Innlandet har flere klyngeinitiativ som blir fulgt opp og utviklet i regi av virkemiddelapparatet, herunder også Kunnskapsparkene. Kunnskapsparken Hedmark har bioforedling og kulturnæringer som fokusområder. I denne avhandlingen har vi valgt å presentere og belyse utfordringer knyttet til utviklingen av to ulike klyngeinitiativ, en på anvendt bioteknologi og en på musikk (pop/rock). Begge klyngeinitiativ er initiert og har sitt hovedsete i Hedmark, med tilknyttede aktører i Oppland, men også i andre regioner.
Fokuset på å utvikle regionale næringsklynger bunner først og fremst i behovet for at næringsaktører og FoU miljø i større grad samarbeider og samhandler for å øke konkurransekraften. Ved å initiere fellesprosjekter bidrar man til å øke verdiskapingen i regionen, konsekvensen blir at man løfter ulike fagmiljø til å bli mer attraktive og man kan slik lettere rekruttere ny arbeidskraft, flere studenter og på alle måter skape merverdi. Et regionalt klyngeinitiativ går aktivt inn i prosessen med å fjerne barrierer mellom de ulike aktørene, så som mellom næring og høgskole/universitet. Det handler om å smelte sammen ulike kulturer og synliggjøre verdien av samarbeid med tanke på synergier og økt nasjonal og internasjonal konkurransekraft. Målsettingen vil da være å bli en lærende region, dvs. et innovasjonssystem der alle barrierer er fraværende og kommunikasjonsflyten derved er svært god. Slik kan man ta ut merverdien og skape et godt innovasjonsmiljø.
Denne avhandlingen knytter arbeidet med klyngeutvikling opp til relevant teori og belyser slik de utfordringer man står overfor, systemisk og praktisk. I begynnelsen av utviklingsprosessen ligger det en forventning om sterkt offentlig engasjement, i forhold til ledelse og koordinering samt finansiering. Gjennom å gradvis få tettere dialog med de ulike næringsaktørene og evt. et FoU miljø ligger det en forventning om at næringsaktørene gradvis går inn mer aktivt i klyngeutviklingen, både med menneskelige ressurser og kapital. Forankringen hos de ulike aktørene og det å alliere seg med en respektert person som kan snakke varmt om klyngeprosessen er en kritisk suksessfaktor. Etter hvert som klyngeutviklingen blir mer kjent, forstått og akseptert kan klyngefasilitatoren rette blikket utover, fra det regionale til det nasjonale og etter hvert det internasjonale miljø.
I Norge finnes det to hovedprogrammer for klyngeutvikling, Arena og Norwegian Centres of Expertise. Arena er ment for de mer umodne miljøene, mens NCE programmet er tiltenkt de klyngene som har størst vekstpotensial og som gjør seg gjeldende i et internasjonalt marked. Denne avhandlingen presenterer to case; BIOINN som har avsluttet sin programperiode som Arenaprosjekt og nå står på egne ben på regionale offentlige og private midler, samt musikk-klyngen i Hedmark som er i tidlig fase i utviklingen, men har et stort potensial og er i god driv. Kravet til ledelse varierer i forhold til hvilket utviklingstrinn klyngen er i, og arbeidets grad av suksess er gjerne knyttet til at man ikke slipper fokus og er i aktiv dialog med alle aktørene. Man må kontinuerlig være på post og drive aktiv markedsføring, motiveringsarbeid og på ulike måter holde trykket og entusiasmen oppe.
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Haga, Tim [Verfasser], Eva-Maria [Akademischer Betreuer] [Gutachter] Feichtner, and Josephine [Gutachter] Yu. "On Polytopes Arising in Cluster Algebras & Finite Frames / Tim Haga. Betreuer: Eva-Maria Feichtner. Gutachter: Eva-Maria Feichtner ; Josephine Yu." Bremen : Staats- und Universitätsbibliothek Bremen, 2016. http://d-nb.info/1106374606/34.
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Razumovskiy, Vsevolod. "Thermodynamic and kinetic properties of Fe-Cr and TiC-ZrC alloys from Density Functional Theory." Doctoral thesis, KTH, Materialteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96285.
Full textAbstract:
The complete and accurate thermodynamic and kinetic description of any systemis crucialfor understanding and predicting its properties. A particular interest is in systemsthat are used for some practical applications and have to be constantly improved usingmodification of their composition and structure. This task can be quite accuratelysolved at a fundamental level by density functional theory methods. Thesemethods areapplied to two practically important systems Fe-Cr and TiC-ZrC.The elastic properties of pure iron and substitutionally disordered Fe-Cr alloy are investigatedas a function of temperature and concentration using first-principles electronicstructurecalculations by the exact muffin-tin orbitals method. The temperature effectson the elastic properties are included via the electronic, magnetic, and lattice expansioncontributions. It is shown that the degree of magnetic order in both pure iron andFe90Cr10 alloy mainly determines the dramatic change of the elastic anisotropy of thesematerials at elevated temperatures. A peculiarity in the concentration dependence ofthe elastic constants in Fe-rich alloys is demonstrated and related to a change in theFermi surface topology.A thermodynamic model for the magnetic alloys is developed from first principles andapplied to the calculation of bcc Fe-Cr phase diagram. Various contributions to the freeenergy (magnetic, electronic, and phonon) are estimated and included in the model. Inparticular, it is found that magnetic short range order effects are important just abovethe Curie temperature. The model is applied for calculating phase equilibria in disorderedbcc Fe-Cr alloys. Model calculations reproduce a feature known as a Nishizawahorn for the Fe-rich high-temperature part of the phase diagram.The investigation of the TiC-ZrC system includes a detailed study of the defect formationenergies and migration barriers of point defects and defect complexes involvedin the diffusion process. It is found, using ab initio atomistic simulations of vacancymediateddiffusion processes in TiC and ZrC, that a special self-diffusion mechanism isoperative for metal atom diffusion in sub-stoichiometric carbides. It involves a noveltype of a stable point defect, a metal vacancy ”dressed” in a shell of carbon vacancies.It is shown that this vacancy cluster is strongly bound and can propagate through thelattice without dissociating.QC 20120604
HERO-M
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Flückiger, Leonie [Verfasser], Thomas [Akademischer Betreuer] Möller, and Tim [Akademischer Betreuer] Laarmann. "Dynamics of single clusters in intense light pulses studied with ion spectroscopy and light scattering / Leonie Flückiger. Betreuer: Thomas Möller. Gutachter: Thomas Möller ; Tim Laarmann." Berlin : Technische Universität Berlin, 2015. http://d-nb.info/1077818696/34.
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Oelze, Tim Günter [Verfasser], Maria [Akademischer Betreuer] Krikunova, Maria [Gutachter] Krikunova, and Marcel [Gutachter] Mudrich. "Untersuchung der photoinduzierten Dynamik in Clustern sowie Pulslängenbestimmung am FEL mittels THz-Lichtfeld-Streaking / Tim Günter Oelze ; Gutachter: Maria Krikunova, Marcel Mudrich ; Betreuer: Maria Krikunova." Berlin : Technische Universität Berlin, 2020. http://d-nb.info/1218595515/34.
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Dixon, Richard. "STM studies of semiconducting metal oxides." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365728.
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Schumacher, Stefan [Verfasser], Thomas [Akademischer Betreuer] Michely, Tim O. [Akademischer Betreuer] Wehling, and Heiko [Akademischer Betreuer] Wende. "Structure, Magnetism, and Binding of Novel Two-Dimensional Materials: Europium-Intercalated Graphene, Cluster Lattices, and Polar Oxide Bilayers / Stefan Schumacher. Gutachter: Thomas Michely ; Tim O. Wehling ; Heiko Wende." Köln : Universitäts- und Stadtbibliothek Köln, 2014. http://d-nb.info/1058946226/34.
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Landauro, Saenz Carlos V. "Influence of spectral fine structure on the electronic transport of icosahedral quasicrystals." Doctoral thesis, Universitätsbibliothek Chemnitz, 2002. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200200892.
Full textAbstract:
Die Spektrale Leitfaehigkeit ikosaedrischer
Approximanten zeigt Feinstrukturen (100 meV) die
das besondere elektronische Transportverhalten der
Quasikristalle und Approximanten erklaeren
koennen. Der Ursprung diese spektralen
Feinstrukturen liegt im Zusammenwirken der
typischen mehrkomponentigen Atomcluster des
Systems. Das Konzept stellt Struktur und
chemische Dekoration auf der Laengenskala der
Cluster ueber ausgedehnte Quasiperiodizitaet.
Ab-initio Methode mit und ohne periodische
Randbedingungen werden hier angewendet,
um das Zusammenwirken der Cluster fuer niedere
Approximanten ikosaedrischer Quasikristalle zu
untersuchen. Deshalb werden die Linearen
Muffin-Tin Orbitale in einem Superzellenkonzept,
die Tight-Binding Linearen Muffin-Tin Orbitale in
einem Cluster-Rekursionsverfahren und die
Landauer/Buettiker-Methode in dieser
Arbeit eingesetzt.
Auf der Grundlage der ab-initio Ergebnisse werden
spektrale Modelle (Lorentz-Funktionen) fuer den
spektralen spezifischen Widerstand gebildet.
Der Uebergang zum Quasikristall erfolgt durch
Skalierung der Modellparameter auf der Grundlage
der gemessenen Thermokraft. Die optische
Leitfaehigkeit und die Temperaturverlaeufe des
Widerstandes, der Thermokraft, des
Hall-Koeffizienten und der elektronischen
Waermeleitfaehigkeit einiger ikosaedrischer
Systeme werden so durch je zwei Lorentz-Funktionen
beschrieben.
Wir zeigen, dass die Transportanomalien zusammen
mit den spektralen Feinstrukturen empfindlich vom
Subsystems des jeweils aktiven
Uebergangsmetallsabhaengen (Orientierung und
Dekoration der ikosaedrischen Cluster).
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Leonhardt, Christian. "Zinnalkoxide als Präkursoren für zinnhaltige Nanokomposite." Doctoral thesis, Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-218790.
Full textAbstract:
In der vorliegenden Arbeit wird die Synthese von neuartigen Zinn(II)alkoxiden, deren Potential für die Zwillingspolymerisation und die Darstellung von zinnhaltigen organisch-anorganischen Nanokompositen beschrieben. Partielle Hydrolyse der Zinn(II)alkoxide führt zur Bildung von fünf- und sechskernigen Zinnoxidoclustern, die eine gute Löslichkeit in organischen polaren Lösungsmitteln besitzen. Eine Nachbehandlung der durch Zwillingspolymerisation erhaltenen Hybridmaterialien unter reduzierenden Bedingungen (Ar/H2) liefert Nanokomposite bestehend aus Zinnnanopartikeln eingebettet in eine Kohlenstoff/Siliziumdioxid-Matrix. Weiterhin werden verschiedene metallhaltige Additive wie z.B. Carboxylate in der Zwillingspolymerisation verwendet und deren Eignung zur Darstellung von zinnhaltigen Nanokompositen sowie zur Legierungsbildung mit Zinn im Nanokomposit untersucht. Mit ausgewählten Materialien werden elektrochemische Messungen durchgeführt, wobei deren potentieller Einsatz als Anodenmaterial für Lithiumionen-Batterien geprüft wird (Kooperation BASF SE, Research Performance Materials GMV/P). Die Charakterisierung der neu synthetisierten Verbindungen und Nanokomposite erfolgt unter anderem mittels Einkristallröntgenstrukturanalyse, Röntgenpulverdiffraktometrie, NMR-Spektroskopie, Infrarotspektroskopie, Elektronenmikroskopie sowie thermischen Analysemethoden
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Le, Lay Luc. "Mise en forme et etude de filaments supraconducteurs a base de phases de chevrel." Rennes 1, 1988. http://www.theses.fr/1988REN10126.
Full textAbstract:
Elaboration et etude de filaments pbmo::(6)s::(8) et snmo::(6)s::(8) et des massifs de ces memes materiaux. Etude des comportements mecanique, chimique et supraconducteur des massifs. Optimisation de la composition de la poudre d'un brin monofilamentaire en fonction des dopants, de la stoechiometrie et de la nature des poudres de base. Optimisation des traitements des filaments: des traitements a haute temperature (950**(o)c a 1000**(o)cpounds et pendant des durees relativement courtes (0,5 a 2 h) permettent d'obtenir les meilleurs resultats de densites de courant critique. Realisation de bobinettes permettant d'atteindre des densites de courant critique de 10**(8) a/m**(2) a 14 t
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Fischer, Tim [Verfasser]. "Untersuchung von massenselektierten Clustern mittels VUV-Lasern : Photoelektronenspektroskopie massenselektierter Cluster mit Lasern extrem kurzer Wellenlänge / vorgelegt von Tim Fischer." 2008. http://d-nb.info/991050894/34.
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Verdugo, Olivares Miguel Anibal. "The star formation activity from the centers to the outskirts in intermediate redshift clusters." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-0006-B46C-5.
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Zebrowski, Jeffrey Paul. "Synthesis and characterization of mixed-transition metal carbonyl clusters and nickel-germanium and nickel-tin carbonyl clusters." 1990. http://catalog.hathitrust.org/api/volumes/oclc/23438555.html.
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Birkholz, Axel. "Embedded-Cluster-Simulationen zur Struktur von Ti3[plus]-Polaronen und Sauerstoff-Leerstellen in BaTiO3." Doctoral thesis, 2000. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2000090843.
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In der vorliegenden Arbeit wurde mit Hilfe von Embedded-Cluster-Simulationen die Struktur einiger typischer
Defektzentren des technologisch vielversprechenden Perowskitkristalls BaTiO3 untersucht.
Embedded-Cluster-Simulationen bestehen aus einer quantenmechanischen ab-initio Beschreibung eines begrenzten
Cluster-Bereiches aus ca. 20-30 Ionen entweder in Hartree-Fock-Theorie oder in Dichtefunktionaltheorie. Zur
Simulation der Kristallumgebung wird der Cluster in ein mit klassischen Potentialmethoden beschriebenes
Punktladungsfeld eingebettet. Zur Erfassung elektronischer Polarisierungsanteile bietet sich hierfür das Schalenmodell
an.
Zunächst wurde das Verfahren auf das experimentell gut bekannte Ti3+-Jahn-Teller-Polaron angewendet. Es ergab
sich eine gute Übereinstimmung mit den Resultaten aus vorherigen Elektronenspinresonanz-Untersuchungen. Der
Energiegewinn durch die Ankopplung an die totalsymmetrische Atmungsmode des Gitters und durch den zusätzlichen
symmetriereduzierenden Jahn-Teller-Effekt sowie der Vergleich mit dem Energiegewinn durch Bandbildung ergab eine
geringfügige Begünstigung des polaronischen Zustands von ca. 0.1-0.2 eV. Ebenso konnte gezeigt werden, daß die dem
Jahn-Teller-Polaron zuzuordnende Ladungsdichte auf mehrere benachbarte Titan-Ionen delokalisiert ist (intermediäres
Polaron).
Nach einer Reduktionsbehandlung werden in der ESR weitere axiale Zentren mit Ti3+-Charakter beobachtet, die bisher
durch den Elektroneneinfang an einem Ti4+-Ion in der Nachbarschaft von Sauerstoff-Leerstellen (Ti3+-VO)
interpretiert wurden. Aus den beobachteten g-Werten wird weiterhin ein Orbital mit t2-Symmetrie gefolgert. In
Embedded-Cluster-Simulationen wird dagegen für das Ti3+-VO-Zentrum ein elektronischer Grundzustand mit
e-Symmetrie gefunden. Auch eine aus der ESR vermutete Anlagerung von Akzeptoren führte nicht zu einem t2-artigen
Grundzustand.
Als Modell, welches mit der ESR kompatibel ist, wurde dagegen ein Elektroneneinfang in der Nachbarschaft von
Akzeptoren ohne die Annahme einer VO gefunden (Ti3+-O2--A+). Im Rahmen von Schalenmodellrechnungen wurde die
tendenzielle Möglichkeit der Stabilität solch einer Konfiguration gezeigt und in Embedded-Cluster-Simulationen die
Jahn-Teller-Aufspaltung berechnet, die in guter Übereinstimmung mit den in der ESR gefundenen liegt.
Der Grund, weshalb der theoretisch erwartete Elektroneneinfang in e-Symmetrie in der Nachbarschaft einer VO in der
ESR nicht beobachtet wird, wird in einem Einfang von zwei Elektronen an der VO vermutet. In der Simulation dieses
sogenannten Bipolarons ergab sich durch die Ankopplung an das äußere Gitter eine deutliche Reduktion der effektiven
Elektron-Elektron Wechselwirkung auf einige Zehntel eV, so daß in weitergehenden Rechnungen mit einem größeren
Cluster und einem besseren Basissatz eine Bipolaronen-Bildung möglich erscheint.In this thesis several typical defect centres in the technologically important perovskite BaTiO3 have been analysed using the embedded-cluster approach. The embedded-cluster-approach consists of a quantum mechanical simulation of an inner cluster region of about 20-30 atoms or ions either with the Hartree-Fock theory or with the Density-Functional theory. The simulation of the crystal environment is realized by embedding the cluster in a point-charge field which is treated by means of classical potential methods. In order to take electronic polarization effects into account the shell-model is used. At first we simulated the experimentally well-known Ti3+ - Jahn-Teller polaron. A good agreement with previous EPR measurements has been found. The energy gained by coupling to the breathing-mode of the surrounding lattice and by the additional symmetry-reducing Jahn-Teller effect in comparison with the energy gain related to delocalization showed a small preference of the polaronic state of 0.1-0.2 eV. In addition a slight delocalization of the polaronic charge over several neighbouring Ti-ions was found (intermediate polaron). After a reduction treatment further axial centres of Ti3+-type were found with EPR, which have been interpreted as an electron capture at a Ti-ion near an oxygen vacancy (Ti3+-VO). Because of the measured g-values the polaronic orbital was expected to have t2-like symmetry. In contrast, the embedded cluster simulations revealed a ground-state with e-character. Even an electron trapping near a repulsive acceptor (Ti3+-VO - A+) did not have the proposed t2 ground state symmetry. In agreement with the experimental expectations, we suggest a model consisting of an electron with t2 symmetry captured near an acceptor without taking into account an oxygen vacancy (Ti3+-O2--A+). Using shell-model calculations the stability of such a complex could be shown. In embedded cluster simulations the Jahn-Teller splittings were found to be in good agreement with the experimentally observed ones. A possible explanation for the non-observability of the theoretically proposed Ti-centres with e-symmetry near the oxygen vacancy could be the existence of neutral vacancies, i.e. capture of two electrons near the vacancy. In simulations of this so called bipolaron we showed that the effective electron-electron interaction is effectively reduced by coupling to the crystal lattice to some tenths of eV, so that a stable bipolaronic state seems to be possible. Further calculations with a larger cluster and a larger basis set need to be done in the future.
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Wu, Hsin-Yi, and 吳新怡. "Synthesis and Development of Tin Clusters Applied to Extreme Ultraviolet Photoresists." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/pf6dt5.
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Lilly, Thomas. "Exploring the formation histories of galaxies - globular clusters and beyond." Doctoral thesis, 2007. http://hdl.handle.net/11858/00-1735-0000-0006-B46B-7.
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Birkholz, Axel [Verfasser]. "Embedded-Cluster-Simulationen zur Struktur von Ti3+-Polaronen und Sauerstoff-Leerstellen in BaTiO3 / von Axel Birkholz." 1998. http://d-nb.info/961691158/34.
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Fu, Jui-Hung, and 傅睿紘. "Development and Improvement of Extremely Ultraviolet Photoresist Containing Twelve, Six, Four and Other Tin Clusters." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/62h6ey.
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Handy, Brent Edward. "Highly-dispersed, alumina-supported metal particles prepared from the PT₁₅(C0)₃₀²⁻cluster compound tin and platinum-tin morphologies on alumina and graphite /." 1988. http://catalog.hathitrust.org/api/volumes/oclc/18690605.html.
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Thesis (Ph. D.)--University of Wisconsin--Madison, 1988.Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 283-292).
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Correia, Manuel Mendes. "Modelo de apoio à decisão para utilização de tic na otimização da recolha de resíduos recicláveis." Master's thesis, 2016. http://hdl.handle.net/10071/14003.
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A gestão de resíduos vive atualmente um paradigma de otimização dos seus processos, onde
as tecnologias de informação e comunicação (TIC) têm um papel cada vez mais preponderante. No entanto, os custos associados à utilização das TIC nos processos de recolha de resíduos
são ainda muito elevados, logo é necessário elaborar estratégias para uma integração mais
sustentável dessas tecnologias nesta indústria.
No presente trabalho propõe-se um modelo de apoio à decisão de monitorização em tempo
real das quantidades de resíduos recicláveis depositadas nos ecopontos tendo em vista a otimização das suas rotas de recolha. Dado o custo elevado de monitorizar todos os ecopontos
com recurso às TIC, o modelo desenvolvido baseia-se na análise de agrupamentos de ecopontos com características semelhantes, efetuando a monitorização de uma amostra de cada cluster em detrimento da monitorização de todos os ecopontos. A incerteza associada à extrapola-
ção dos dados das amostras para o total dos clusters leva à necessidade de se realizar uma
análise de risco com recurso à simulação de Monte Carlo para poder avaliar eficazmente os
benefícios desta solução. O modelo desenvolvido foi aplicado e validado com os dados cedidos por uma empresa realWaste management addresses nowadays a paradigm of optimizing its processes in order to follow up efficiently the growth of recyclable waste production using at the same time information and communication technologies (ICT). The costs associated to the implementation of ICT in the processes of waste collection, even if enabling an optimization of the processes, are high, hence it is necessary to develop strategies to a sustainable integration of those technologies in that industry. In the present work it is proposed a decision support model regarding the monitoring of recyclable waste containers with ICT aiming to the optimization of the collection routes. The model is based on the grouping of similar containers into clusters, and then monitoring a sample of each cluster, instead of monitoring all containers. The uncertainty associated to the extrapolation of data from the samples to the clusters implies that a risk analysis (with Monte Carlo simulation) must be carried out in order to effectively assess the benefits of the decision support model when applied to a real case
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薛嘉哲. "The Relationships among Identification Industrial Cluster,Motivational Orientations,and Entrepreneurs'Innovative Behaviors:An Empirical Study on Tie-Wei Township Horticultural Industry." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/36163328849726022835.
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碩士國立彰化師範大學
工業教育與技術學系
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Abstract This study explored the relationship among identification of industrial clustering, intrinsic- and extrinsic- motivation, and innovation behavior. First, we purpose higher identification of industrial clustering inducing innovative behavior. Second, we posited the positive relationship between intrinsic motivation and innovative behavior. Moreover, higher extrinsic motivation results in lower innovative behavior. We use questionnaire to collected data from Tian-wei Township clustering of horticultural industry. We match operators of horticultural industry and agent, total match questionnaires is 300. After data collection, we employ hierarchical regression to analysis 261 valid match questionnaires between operators of horticultural industry and agent. The result shows that the relationship between identification of industrial clustering and innovative behavior is positively. And also, we found intrinsic motivation positive related to innovative behavior. Besides, intrinsic motivation also moderates the relationship between identification of industrial clustering and innovative behavior. The other side, we also found that extrinsic motivation positively related to innovative behavior. But we test the moderating effect of extrinsic motivation on identification of industrial clustering and innovative behavior, it is not significant. Finally, we suggest managerial implication and future research as following content. Key words：identification of industrial clustering, intrinsic- and extrinsic- motivation, innovation behavior
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Oliveira, Tiago André Gonçalves Félix de. "Estimação de Modelos de Adopção e Difusão de Tecnologias de Informação e Comunicação em Portugal." Master's thesis, 2006. http://hdl.handle.net/10362/6740.
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Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Estatística e Gestão de InformaçãoActualmente é consensual que as Tecnologias de Informação e Comunicação (TIC) têm um efeito significativo na produtividade das empresas. No entanto, esta contribuição só pode ser efectivada se, e quando, as novas TIC forem amplamente difundidas e utilizadas. Compreender os factores determinantes da adopção e difusão é uma questão fundamental, não só para os economistas, mas também para a sociedade em geral. Com esta dissertação pretendemos contribuir para uma melhor compreensão dos factores determinantes da adopção e difusão das TIC nas empresas portuguesas, bem como do nível de utilização.(...)Nowadays it is consensual that Information and Communication Technologies (ICT) have a significant effect in the productivity of firms. However, this contribution can only be accomplished if, and when, the new ICT are widely spread and used. To understanding the determinants of adoption and diffusion is a fundamental question, not only for economists, but also for society in general. With this thesis we intend to contribute to a better understanding of the determinants of adoption and diffusion of ICT in Portuguese firms, as well as of the level of use.(...)
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Assadollahzadeh, Behnam. "A systematic search for the global minimum structures of Cs, Sn and Au clusters and corresponding electronic properties : a thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Massey University, Albany, New Zealand." 2007. http://hdl.handle.net/10179/1407.
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Clusters of atoms or molecules form the building blocks of nanoscience and are regarded as a new type of material, as they constitute a bridge between microscopic and macroscopic forms of matter. The experimental and quantum theoretical study of structures, chemical and physical properties and reactivities of nanoclusters represents an innovative and very active field of research, which has resulted in a wide range of applications. Independent of the model used to describe the bonding in these clusters, one of the prime objectives is to find the geometrical arrangement of the atoms or molecules, for a given cluster size, which corresponds to the lowest energy on the potential energy hyper-surface, the global minimum. In order to find such an arrangement, a density functional theory based genetic algorithm code, which is rooted in the Darwinian evolution concept of the survival of the fittest, is developed and utilized to systematically search for the global minimum isomers of homo-nuclear clusters consisting of up to twenty atoms of cesium, tin, gold and of nine atoms of copper. The performance of this algorithm is excellent as numerous energetically lower-lying cluster isomers (compared to those reported in the literature) are found. Extensive valence basis sets together with energy-consistent scalar-relativistic pseudopotentials are employed to optimize the geometry of these clusters and to calculate their electronic properties accurately at the density functional level of theory. Moreover, in collaboration with the Technische Universit??t Darmstadt, the mean static polarizability of tin clusters are measured by a beam deflection method. The qualitative agreement between measured and calculated dipole moments and static electric dipole polarizabilities of tin clusters up to twenty atoms is satisfactory, thus confirming the accuracy of the theoretical models used in this work. Furthermore, the performance of density functional theory in the field of metallophilicity is investigated for dimeric and trimeric [X-M-PH3] compounds (X = Cl, Br, I; M = Cu, Ag, Au) and it is found that the metallophilicity decreases down the group 11 elements of the periodic table of elements.
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Fritz, Alexander. "The Dependence of the Evolution of Early-Type Galaxies on their Environment." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-B594-0.
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Leonhardt, Christian. "Zinnalkoxide als Präkursoren für zinnhaltige Nanokomposite." Doctoral thesis, 2016. https://monarch.qucosa.de/id/qucosa%3A20640.
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In der vorliegenden Arbeit wird die Synthese von neuartigen Zinn(II)alkoxiden, deren Potential für die Zwillingspolymerisation und die Darstellung von zinnhaltigen organisch-anorganischen Nanokompositen beschrieben. Partielle Hydrolyse der Zinn(II)alkoxide führt zur Bildung von fünf- und sechskernigen Zinnoxidoclustern, die eine gute Löslichkeit in organischen polaren Lösungsmitteln besitzen. Eine Nachbehandlung der durch Zwillingspolymerisation erhaltenen Hybridmaterialien unter reduzierenden Bedingungen (Ar/H2) liefert Nanokomposite bestehend aus Zinnnanopartikeln eingebettet in eine Kohlenstoff/Siliziumdioxid-Matrix. Weiterhin werden verschiedene metallhaltige Additive wie z.B. Carboxylate in der Zwillingspolymerisation verwendet und deren Eignung zur Darstellung von zinnhaltigen Nanokompositen sowie zur Legierungsbildung mit Zinn im Nanokomposit untersucht. Mit ausgewählten Materialien werden elektrochemische Messungen durchgeführt, wobei deren potentieller Einsatz als Anodenmaterial für Lithiumionen-Batterien geprüft wird (Kooperation BASF SE, Research Performance Materials GMV/P). Die Charakterisierung der neu synthetisierten Verbindungen und Nanokomposite erfolgt unter anderem mittels Einkristallröntgenstrukturanalyse, Röntgenpulverdiffraktometrie, NMR-Spektroskopie, Infrarotspektroskopie, Elektronenmikroskopie sowie thermischen Analysemethoden
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Cummings, Jennifer Ann. "D-Aminoacylases and Dipeptidases within the Amidohydrolase Superfamily: Relationship Between Enzyme Structure and Substrate Specificity." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-9021.
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Approximately one third of the genes for the completely sequenced bacterial genomes have an unknown, uncertain, or incorrect functional annotation. Approximately 11,000 putative proteins identified from the fully-sequenced microbial genomes are members of the catalytically diverse Amidohydrolase Superfamily. Members of the Amidohydrolase Superfamily separate into 24 Clusters of Orthologous Groups (cogs). Cog3653 includes proteins annotated as N-acyl-D-amino acid deacetylases (DAAs), and proteins within cog2355 are homologues to the human renal dipeptidase. The substrate profiles of three DAAs (Bb3285, Gox1177 and Sco4986) and six microbial dipeptidase (Sco3058, Gox2272, Cc2746, LmoDP, Rsp0802 and Bh2271) were examined with N-acyl-L-, N-acyl-D-, L-Xaa-L-Xaa, L-Xaa-D-Xaa and D-Xaa-L-Xaa substrate libraries. The rates of hydrolysis of the library components were determined by separating the amino acids by HPLC and quantitating the products. Gox1177 and Sco4986 hydrolyzed several N-acyl-D-amino acids, especially those where the amino acid was a hydrophobic residue. Gox1177 hydrolyzed L-Xaa-D-Xaa and N-acetyl-D-amino acids with similar catalytic efficiencies (~10⁴ M⁻¹s⁻¹). The best substrates identified for Gox1177 and Sco4986 were N-acetyl-D-Trp and N-acetyl-D-Phe, respectively. Conversely, Bb3285 hydrolyzed N-acyl-D-Glu substrates (kcat/Km ⁹́⁸ 5 x 10⁶M⁻¹s⁻¹) and, to a lesser extent, L-Xaa-D-Glu dipeptides. The structure of a DAA from A. faecalis did not help explain the substrate specificity of Bb3285. N-methylphosphonate derivatives of D-amino acids were inhibitors of the DAAs examined. The structure of Bb3285 was solved in complex with the N-methylphosphonate derivative of D-Glu or acetate/formate. The specificity of Bb3285 was due to an arginine located on a loop which varied in conformation from the A. faecalis enzyme. In a similar manner, six microbial renal dipeptidase-like proteins were screened with 55 dipeptide libraries. These enzymes hydrolyzed many dipeptides but favored L-D dipeptides. Respectable substrates were identified for proteins Bh2271 (L-Leu-D-Ala, kcat/Km = 7.4 x 10⁴ M⁻¹s⁻¹), Sco3058 (L-Arg-D-Asp, kcat/Km = 7.6 x 10⁵ M⁻¹s⁻¹), Gox2272 (L-Asn-D-Glu, kcat/Km = 4.7 x 10⁵ M⁻¹s⁻¹), Cc2746 (L-Met-D-Leu, kcat/Km = 4.6 x 10⁵ M⁻¹s⁻¹), LmoDP (L-Leu-D-Ala, kcat/Km = 1.1 x 10⁵ M⁻¹s⁻¹), Rsp0802 (L-Met-D-Leu, kcat/Km = 1.1 x 10⁵ M⁻¹s⁻¹). Phosphinate mimics of dipeptides were inhibitors of the dipeptidases. The structures of Sco3058, LmoDP and Rsp0802 were solved in complex with the pseudodipeptide mimics of L-Ala-D-Asp, L-Leu-D-Ala and L-Ala-D-Ala, respectively. The structures were used to assist in the identification of the structural determinants of substrate specificity.