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Kratzert, Daniel. "Charge Density Distribution in Low-Valent Tetrels." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://hdl.handle.net/11858/00-1735-0000-001C-63A3-B.
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Niepötter, Benedikt. "Charge Density Analysis of Low-Valent Tetrels." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-0028-86C1-8.
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Niepötter, Benedikt [Verfasser], Dietmar [Akademischer Betreuer] Stalke, Sven [Akademischer Betreuer] Schneider, Ricardo A. [Akademischer Betreuer] Mata, Thomas Dr [Akademischer Betreuer] Waitz, Heidrun [Akademischer Betreuer] Sowa, and Francesca [Akademischer Betreuer] Fabbiani. "Charge Density Analysis of Low-Valent Tetrels / Benedikt Niepötter. Betreuer: Dietmar Stalke. Gutachter: Dietmar Stalke ; Sven Schneider ; Ricardo A. Mata ; Thomas Dr. Waitz ; Heidrun Sowa ; Francesca Fabbiani." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://d-nb.info/1082425621/34.
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Niepötter, Benedikt Verfasser], Dietmar [Akademischer Betreuer] Stalke, Sven [Akademischer Betreuer] Schneider, Ricardo A. [Akademischer Betreuer] Mata, Thomas Dr [Akademischer Betreuer] Waitz, Heidrun [Akademischer Betreuer] [Sowa, and Francesca [Akademischer Betreuer] Fabbiani. "Charge Density Analysis of Low-Valent Tetrels / Benedikt Niepötter. Betreuer: Dietmar Stalke. Gutachter: Dietmar Stalke ; Sven Schneider ; Ricardo A. Mata ; Thomas Dr. Waitz ; Heidrun Sowa ; Francesca Fabbiani." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:7-11858/00-1735-0000-0028-86C1-8-4.
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PETTERSSON, MARTIN, and DANIEL SWENSSON. "Stress Tetris." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-136131.
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The idea behind this project was to implement and study biofeedback features in the popular video game Tetris, using EDA (Electrodermal activity). The goal was to explore if it is possible to deliberately alter live EDA measurements using a Q-Sensor wristband along with the game. Our implementation can change the speed of the game according to the current EDA value of the player. The problem was studied by issuing a user test experiment along with a survey questioning how test subjects responded to the biofeedback features. Results seemed to show that manipulating EDA in our version of Tetris seems possible, although subjects could only alter EDA for shorter periods of time rather than manipulating a general value. More accurate results would require more work and knowledge than presented in this study.Tanken bakom detta projekt var att implementera och studera biofeedbackelement i det populära datorspelet Tetris genom att använda EDA (Electrodermal activity). Målet var att undersöka om det är möjligt att medvetet manipulera EDA-mätningar vid användandet av ett QSensor- armband tillsammans med spelet. Vår implementation kan ändra spelets hastighet beroende på vilket EDA-värde en spelare vid tillfället har. Problemet studerades genom att utföra ett användartest tillsammans med en fråge-enkät för att undersöka hur testpersoner svarade till biofeedback-elementen. Resultaten verkade visa att det kan vara möjligt att medvetet manipulera EDA-mätningar vid spelande av Tetris, dock kunde försökspersonerna bara förändra dessa mätningar under kortare perioder snarare än att påverka genomsnittsvärdet. Mer tillförlitliga resultat kräver betydligt mer arbete och kunskap än vad som framställs i denna rapport.
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Jantke, Laura-Alice [Verfasser]. "From Zintl Phases to Novel Tetrel Allotropes - Quantum Chemical Considerations of Zintl Phases and Zintl Clusters lead to Novel Tetrel Modifications / Laura-Alice Jantke." München : Verlag Dr. Hut, 2018. http://d-nb.info/1149579161/34.
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LÖVMAR, ANTON, and PER CLASSON. "Biofeedback med EDA i Tetris." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-136080.
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In a biofeedback system, data about the user’s physiological functions is measured and used as input for the system. EDA is a measurement of a persons stress and it is used in biofeedback systems. This essay is about measuring EDA with the Affectiva Q Sensor in the game Tetris. The relationship between EDA and the difficulty in the game has been analyzed, both through correlation analysis and curve fitting. In the game the difficulty can be controlled by implicit and explicit biofeedback, and this functionality has been used to see if users could learn to control their stress through explicit biofeedback. The result of the study was that there exists a corrrelation (the average correlation coefficient was 0.472) between EDA and difficulty. It was also shown that the players could not control their EDA with the help of explicit biofeedbackI biofeedback-system mäts och registreras data om användarens fysiologiska funktioner, för sedan kunna användas som indata till systemet. EDA är ett mått på hur stressad en person är och används i biofeedback-system. Denna uppsats handlar om att mäta EDA med hjälp av Affectiva Q Sensor i spelet Tetris. Sambandet mellan EDA och svårighetsgraden i spelet har undersökts, både med hjälp korrelationsanalys och kurvanpassning. I spelet kan svårighetsgraden styras med implicit och explicit biofeedback, och med denna funktionalitet har det testats det om det är möjligt för en spelare att kontrollera sin EDA med hjälp av den explicita feedbacken. Resultatet var att det finns en korrelation (medelvärdet för korrelationskoefficienten var 0.472) mellan EDA och svårighetsgrad, däremot kunde spelarna inte lära sig att kontrollera sin EDA (stress) när de spelade Tetris.
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Dürr, Ines Anne [Verfasser], and Caroline [Akademischer Betreuer] Röhr. "Binäre und ternäre Lanthan-Triel-Tetrel-ide : : Synthese, Kristallchemie und chemische Bindung." Freiburg : Universität, 2012. http://d-nb.info/1123470995/34.
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Spiekermann, Annette. "Untersuchungen zur Reaktivität der Zinti-Anionen der Tetrele in Lösung mit Gold-Verbindungen." kostenfrei, 2008. http://mediatum2.ub.tum.de/node?id=673766.
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Bergmark, Max. "Tetris: A Heuristic Study : Using height-based weighing functions and breadth-first search heuristics for playing Tetris." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168306.
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This paper studies the performance of height-based weighing functions and compares the results to using the commonly used non height-based weighing functions for holes. For every test performed, the heuristic methods studied in this paper performed better than the commonly used heuristic function. This study also analyses the effect of adding levels of prediction to the heuristic algorithm, which increases the average number of cleared lines by a factor of 85 in total. Utilising these methods can provide increased performance for a Tetris AI. The polynomic weighing functions discussed in this paper provide a performance increase without increasing the needed computation, increasing the number of cleared lines by a factor of 3. The breadth-first search provide a bigger performance increase, but every new level of prediction requires 162 times more computation. Every level increases the number of cleared lines by a factor of 9 from what has been observed in this study.
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Amundsen, Jonas Balgaard. "A comparison of feature functions for Tetris strategies." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26755.
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Finding optimal strategies for the game of Tetris is an interesting NP-complete problem that has attracted several AI researchers. Their approaches display subtle variations in the implementation details, with unclear relationships between these details and Tetris performance. This, combined with the absence of confidence intervals in most published results, makes the evaluation and comparison of Tetris strategies and optimization methods very difficult.To look furhter into this unclear relationship, we would re-create every environnment described in several publications. An evolutionary algorithm was executed within each environment to create an AI and their performance compared against each other. The scores differed \textit{substantially}. This suggests that some aspects of the Tetris environment greatly affects the potentially obtainable performance of an AI. We come to the unfortunate conclusion that nearly no results of existing publications can be used to compare optimization methods against each other in terms of suitability for Tetris due to this reason.
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Chang, Alice Ai-Yuan. "Models of common errors in a Tetris session." Thesis, Massachusetts Institute of Technology, 1990. https://hdl.handle.net/1721.1/128800.
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Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.Includes bibliographical references (leaf 71).
by Alice Ai-Yuan Chang.
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.
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Dorfling, Sasha-Lee. "Enantioselective transformations using tetrol as a chiral mediator." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/d1021195.
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(+)-(2R,3R)-1,1,4,4-Tetraphenylbutane-1,2,3,4-tetraol (TETROL) and its derivatives were reacted with varying molar ratios of titanium isopropoxide (2:1, 1:1 and 1:2 tetraol:titanium isopropoxide) in an attempt to prepare potential titanium-based tetraol catalysts for enantioselective transformations. In each case, infrared and HNMR spectra suggested that the product was formed. We tentatively proposed that the structure of the catalyst was a spiro-type, but we could not determine conclusively what its exact structure was, despite using numerous techniques at our disposal (molecular modelling calculations, H NMR and IR spectroscopy, thermal analyses, powder diffraction, and single crystal X-ray diffraction). The catalyst and derivatives thereof were able to act catalytically for the enantioselective additions of diethylzinc compounds to aldehydes. The effects of temperature and solvent were investigated, and toluene and -78 °C were selected as optimal from the results obtained. (The reaction could, however, not be maintained at this low temperature for extended periods due to the fact that we did not have, at our disposal, the correct equipment. Each 16 h reaction was thus allowed to reach room temperature in each case.) The selectivity for the product 1-phenylpropan-1-ol (when benzaldehyde was the starting aldehyde) varied depending on the nature of the aryl substituents of the titanium-based catalyst. Using 0.2 molar equivalents of the chiral titanates, the highest selectivity was 42 percent (e.e.), but only when excess Ti(O-i-Pr)4 had been added to the reaction mixture. This was achieved with the tetra(ortho-methoxyphenyl)-TETROLate derivative. TETROL and its derivatives were also successful in metal-free catalysis where higher conversions and selectivities were observed, compared to when these were complexed to titanium. The highest selectivity was 70 percent (e.e.), achieved with the tetra(ortho-methylphenyl)TETROL derivative.
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Chakraborty, Uttam [Verfasser]. "Multiple Bonds between Group 7 Transition Metals and Heavier Tetrel Elements (Ge–Pb) / Uttam Chakraborty." München : Verlag Dr. Hut, 2013. http://d-nb.info/1045125946/34.
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Mayer, Kerstin [Verfasser]. "Molecular Tetrel and Pentel Element Anions – Productive Source for Intermetalloid Clusters and Materials / Kerstin Mayer." München : Verlag Dr. Hut, 2019. http://d-nb.info/1198543019/34.
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Southern, Scott Alexander. "Investigations of Non-Covalent Carbon Tetrel Bonds by Computational Chemistry and Solid-State NMR Spectroscopy." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34408.
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Non-covalent bonds are an important class of intermolecular interactions, which result in the ordering of atoms and molecules on the supramolecular scale. One such type of interaction is brought about by the bond formation between a region of positive electrostatic potential (σ-hole) interacts and a Lewis base. Previously, the halogen bond has been extensively studied as an example of a σ-hole interaction, where the halogen atom acts as the bond donor. Similarly, carbon, and the other tetrel elements can participate in σ-hole bonds. This thesis explores the nature of the carbon tetrel bond through the use of computational chemistry and solid state nuclear magnetic resonance (NMR) spectroscopy.
The results of calculations of interaction energies and NMR parameters are reported for a series of model compounds exhibiting tetrel bonding from a methyl carbon to the oxygen and nitrogen atoms in a range of functional groups. The ¹³C chemical shift (𝛿iso) and the ¹ᶜ𝐽(¹³C,¹⁷O/¹⁵N) coupling across the tetrel bond are recorded as a function of geometry. The sensitivity of the NMR parameters to the non-covalent interaction is demonstrated via an increase in 𝛿iso and in |¹ᶜ𝐽(¹³C,¹⁷O/¹⁵N)| as the tetrel bond strengthens. There is no direct correlation between the NMR trends and the interaction energy curves; the energy minimum does not appear to correspond to a maximum or minimum chemical shift or J-coupling value.
Gauge-including projector-augmented wave density functional theory (DFT) calculations of 𝛿iso are reported for crystals which exhibit tetrel bonding in the solid state. Experimental 𝛿iso values for sarcosine, betaine and caffeine and their tetrel-bonded salts generally corroborate the computational findings. This work offers new insights into tetrel bonding and facilitates the incorporation of tetrel bonds as restraints in NMR crystallographic structure refinement.
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You, Tae-Soo. "Experimental and theoretical investigations in rare earth-triel-tetrel polar intermetallic systems composition-structure-properties relationships /." [Ames, Iowa : Iowa State University], 2008.
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O'Neill, Kevin John. "Induction and Transferral of Flow in the Game Tetris." Wright State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=wright1607267523632825.
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Pohl, Pieter Lourens. "Tetrol and derivatives: synthesis, host-guest properties and racemate resolutions." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/2879.
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In this study, we investigated the potential of a novel chiral host compound (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL) and its derivatives for use in racemate resolution using host-guest chemistry. The parent TETROL molecule is composed of a butane chain bearing a hydroxy functionality on each carbon, and two phenyl rings on each of the terminal carbons. The two internal carbon atoms are chiral. The syntheses of TETROL and derivatives were carried out by modifying the diester of naturally-occurring optically active tartaric acid using a variety of aromatic Grignard reagents. These included phenyl, anisyl, tolyl and naphthyl groups, as well as aromatic rings bearing fluoro and trifluoromethyl substitutents. The substituents on the aromatic rings were located in the ortho, meta or para positions. The so-obtained potential host compounds were investigated for their inclusion abilities by recrystallizing them from a number of potential chiral guest compounds such as 2- and 3-methylcyclohexanone, camphor, i-propanol and 2-butanol, as well as various achiral organic compounds. Host:guest ratios were determined by means of 1H-NMR spectroscopy. Of the hosts investigated, TETROL appeared to favour a host:guest ratio of 1:1 for all included compounds. It complexed with cyclic ketones such as cyclohexanone and derivatives, and also cyclic alcohols and amines like cyclohexanol and morpholine. TETROL, however, was not able to include short chain or branched chain alcohols such as i-propanol and 2-butanol. p-AnisylTETROL showed similar inclusion abilities to TETROL but, in addition, enclathrated i-propanol and 2-butanol. p-TolylTETROL showed a preference for the inclusion of alcohols over ketones. In general, the ortho-substituted aromatic derivatives of TETROL faired relatively poorly as hosts, with some exceptions. Of the hosts investigated, TETROL appeared to favour a host:guest ratio of 1:1 for all included compounds. It complexed with cyclic ketones such as cyclohexanone and derivatives, and also cyclic alcohols and amines like cyclohexanol and morpholine. TETROL, however, was not able to include short chain or branched chain alcohols such as i-propanol and 2-butanol. p-AnisylTETROL showed similar inclusion abilities to TETROL but, in addition, enclathrated i-propanol and 2-butanol. p-TolylTETROL showed a preference for the inclusion of alcohols over ketones. In general, the ortho-substituted aromatic derivatives of TETROL faired relatively poorly as hosts, with some exceptions. X-Ray data of the inclusion complexes indicated that a pair of 1,3-intramolecular hydrogen bonds was a significant stabilizing factor of the geometries of all the hosts. The guest was always held in the host crystal by means of a hydrogen bond with the host, where the host functioned as the hydrogen bond donor and the guest as the acceptor. There were a number of other inter- and intra-molecular contacts that further stabilized the inclusion complexes. A surprising feature of the inclusion of 3-methylcyclohexanone, as elucidated by X-ray analysis, was that its methyl group adopted the axial orientation, the higher energy conformation for these kinds of molecules, and a 3-alkylketone effect was proposed to be one of the reasons for this observation. Thermal data was used to assess the relative thermal stabilities of the complexes, and the results compared with features of the X-ray structures, in order to determine whether thermal stability is related in some way to the nature of the guest packing in the host crystal. the case of the racemic guests, complexes obtained were analysed using chiral GC-MS. TETROL preferred the R-enantiomers of 2- and 3-methylcyclohexanone (21.7% and 16.7% e.e.). The S-enantiomer of camphor was favoured but the e.e. was low (3.8%). p-AnisylTETROL had a preference for the S-enantiomer in the case of 2- and 3-methylcyclohexanone as well as 2-butanol (44.3%, 20.4% and 1.7% e.e., respectively). p-TolylTETROL could only successfully resolve 2-butanol (23.5% e.e. in favour of the R-enantiomer). o-TolylTETROL preferred the R-enantiomers of methyl phenyl sulfoxide (29.2% e.e.) and 2-butanol (21.5% e.e.). Overall, TETROL and its derivatives exhibited the ability to resolve racemic mixtures to some extent.
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Thiery, Christophe. "Itération sur les Politiques Optimiste et Apprentissage du Jeu de Tetris." Phd thesis, Université Henri Poincaré - Nancy I, 2010. http://tel.archives-ouvertes.fr/tel-00550081.
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Cette thèse s'intéresse aux méthodes d'itération sur les politiques dans l'apprentissage par renforcement à grand espace d'états avec approximation linéaire de la fonction de valeur. Nous proposons d'abord une unification des principaux algorithmes du contrôle optimal stochastique. Nous montrons la convergence de cette version unifiée vers la fonction de valeur optimale dans le cas tabulaire, ainsi qu'une garantie de performances dans le cas où la fonction de valeur est estimée de façon approximative. Nous étendons ensuite l'état de l'art des algorithmes d'approximation linéaire du second ordre en proposant une généralisation de Least-Squares Policy Iteration (LSPI) (Lagoudakis et Parr, 2003). Notre nouvel algorithme, Least-Squares λ Policy Iteration (LSλPI), ajoute à LSPI un concept venant de λ-Policy Iteration (Bertsekas et Ioffe, 1996) : l'évaluation amortie (ou optimiste) de la fonction de valeur, qui permet de réduire la variance de l'estimation afin d'améliorer l'efficacité de l'échantillonnage. LSλPI propose ainsi un compromis biais-variance réglable qui peut permettre d'améliorer l'estimation de la fonction de valeur et la qualité de la politique obtenue. Dans un second temps, nous nous intéressons en détail au jeu de Tetris, une application sur laquelle se sont penchés plusieurs travaux de la littérature. Tetris est un problème difficile en raison de sa structure et de son grand espace d'états. Nous proposons pour la première fois une revue complète de la littérature qui regroupe des travaux d'apprentissage par renforcement, mais aussi des techniques de type évolutionnaire qui explorent directement l'espace des politiques et des algorithmes réglés à la main. Nous constatons que les approches d'apprentissage par renforcement sont à l'heure actuelle moins performantes sur ce problème que des techniques de recherche directe de la politique telles que la méthode d'entropie croisée (Szita et Lőrincz, 2006). Nous expliquons enfin comment nous avons mis au point un joueur de Tetris qui dépasse les performances des meilleurs algorithmes connus jusqu'ici et avec lequel nous avons remporté l'épreuve de Tetris de la Reinforcement Learning Competition 2008.
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Thiéry, Christophe. "Itération sur les politiques optimiste et apprentissage du jeu de Tetris." Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10128/document.
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Cette thèse s'intéresse aux méthodes d'itération sur les politiques dans l'apprentissage par renforcement à grand espace d'états avec approximation linéaire de la fonction de valeur. Nous proposons d'abord une unification des principaux algorithmes du contrôle optimal stochastique. Nous montrons la convergence de cette version unifiée vers la fonction de valeur optimale dans le cas tabulaire, ainsi qu'une garantie de performances dans le cas où la fonction de valeur est estimée de façon approximative. Nous étendons ensuite l'état de l'art des algorithmes d'approximation linéaire du second ordre en proposant une généralisation de Least-Squares Policy Iteration (LSPI) (Lagoudakis et Parr, 2003). Notre nouvel algorithme, Least-Squares [lambda] Policy Iteration (LS[lambda]PI), ajoute à LSPI un concept venant de [lambda]-Policy Iteration (Bertsekas et Ioffe, 1996) : l'évaluation amortie (ou optimiste) de la fonction de valeur, qui permet de réduire la variance de l'estimation afin d'améliorer l'efficacité de l'échantillonnage. LS[lambda]PI propose ainsi un compromis biais-variance réglable qui peut permettre d'améliorer l'estimation de la fonction de valeur et la qualité de la politique obtenue. Dans un second temps, nous nous intéressons en détail au jeu de Tetris, une application sur laquelle se sont penchés plusieurs travaux de la littérature. Tetris est un problème difficile en raison de sa structure et de son grand espace d'états. Nous proposons pour la première fois une revue complète de la littérature qui regroupe des travaux d'apprentissage par renforcement, mais aussi des techniques de type évolutionnaire qui explorent directement l'espace des politiques et des algorithmes réglés à la main. Nous constatons que les approches d'apprentissage par renforcement sont à l'heure actuelle moins performantes sur ce problème que des techniques de recherche directe de la politique telles que la méthode d'entropie croisée (Szita et Lorincz, 2006). Nous expliquons enfin comment nous avons mis au point un joueur de Tetris qui dépasse les performances des meilleurs algorithmes connus jusqu'ici et avec lequel nous avons remporté l'épreuve de Tetris de la Reinforcement Learning Competition 2008This thesis studies policy iteration methods with linear approximation of the value function for large state space problems in the reinforcement learning context. We first introduce a unified algorithm that generalizes the main stochastic optimal control methods. We show the convergence of this unified algorithm to the optimal value function in the tabular case, and a performance bound in the approximate case when the value function is estimated. We then extend the literature of second-order linear approximation algorithms by proposing a generalization of Least-Squares Policy Iteration (LSPI) (Lagoudakis and Parr, 2003). Our new algorithm, Least-Squares [lambda] Policy Iteration (LS[lambda]PI), adds to LSPI an idea of [lambda]-Policy Iteration (Bertsekas and Ioffe, 1996): the damped (or optimistic) evaluation of the value function, which allows to reduce the variance of the estimation to improve the sampling efficiency. Thus, LS[lambda]PI offers a bias-variance trade-off that may improve the estimation of the value function and the performance of the policy obtained. In a second part, we study in depth the game of Tetris, a benchmark application that several works from the literature attempt to solve. Tetris is a difficult problem because of its structure and its large state space. We provide the first full review of the literature that includes reinforcement learning works, evolutionary methods that directly explore the policy space and handwritten controllers. We observe that reinforcement learning is less successful on this problem than direct policy search approaches such as the cross-entropy method (Szita et Lorincz, 2006). We finally show how we built a controller that outperforms the previously known best controllers, and shortly discuss how it allowed us to win the Tetris event of the 2008 Reinforcement Learning Competition
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Hwang, Daw-sen. "Projected equation and aggregation-based approximate dynamic programming methods for Tetris." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66033.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 65-67).
In this thesis, we survey approximate dynamic programming (ADP) methods and test the methods with the game of Tetris. We focus on ADP methods where the cost-to- go function J is approximated with [phi]r, where [phi] is some matrix and r is a vector with relatively low dimension. There are two major categories of methods: projected equation methods and aggregation methods. In projected equation methods, the cost-to-go function approximation [phi]r is updated by simulation using one of several policy-updated algorithms such as LSTD([lambda]) [BB96], and LSPE(A) [B196]. Projected equation methods generally may not converge. We define a pseudometric of policies and view the oscillations of policies in Tetris. Aggregation methods are based on a model approximation approach. The original problem is reduced to an aggregate problem with significantly fewer states. The weight vector r is the cost-to-go function of the aggregate problem and [phi] is the matrix of aggregation probabilities. In aggregation methods, the vector r converges to the optimal cost-to-go function of the aggregate problem. In this thesis, we implement aggregation methods for Tetris, and compare the performance of projected equation methods and aggregation methods.
by Daw-sen Hwang.
S.M.
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Mahmoudi, Ghodrat, Damir A. Safin, Mariusz P. Mitoraj, Mojtaba Amini, Maciej Kubicki, Thomas Doert, Franziska Locherer, and Michel Fleck. "Anion-driven tetrel bond-induced engineering of lead(II) architectures with N′-(1-(2-pyridyl)ethylidene)nicotinohydrazide: experimental and theoretical findings." Royal Society of Chemistry, 2016. https://tud.qucosa.de/id/qucosa%3A30311.
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The evaluation of N′-(1-(2-pyridyl)ethylidene)nicotinohydrazide (HL) as a linker for the PbII tagged extended structures is described. The reaction of Pb(ClO4)2 or Pb(OAc)2 with HL in MeOH at 60 °C and room temperature, respectively, leads to heteroleptic complexes {[PbL]ClO4}n·nH2O and [PbL(OAc)]2, while the same reaction of Pb(ClO4)2 with HL at 60 °C in the presence of two equivalents of NaOAc or NaNO2 leads to heteroleptic complexes {[Pb(HL)(OAc)]ClO4}n and [PbL(NO2)]n, respectively. Using Pb(NO3)2 as a source of PbII in the same reaction with HL and two equivalents of NaN3 or NaNCS at room temperature yields [PbLN3]n and [Pb2(HL)2(NO3)2(NCS)2], respectively. The room temperature reaction of Pb(NO3)2 with HL in the presence of two equivalents of NaClO4 leads to the transformation of the parent ligand to its perchlorate salt [H2L]ClO4. In all the obtained PbII structures, HL or its deprotonated form L acts both as a chelating and a bridging ligand. The nature of the inorganic anion also influences the final structure. In all complexes the PbII center exhibits a hemidirected coordination geometry with all the covalent bonds being concentrated on one hemisphere of the coordination sphere with the closest approach of two atoms on the other side varying from 151° to 232°. The sterically available PbII ion participates in tetrel bonding as evidenced from the detailed structural analysis of the described complexes. As a result of tetrel bonding, the structures of all the six compounds can be extended to a higher dimensional framework, which is further stabilized by π⋯π stacking interactions between the aromatic rings. The DFT based charge and energy decomposition (ETS-NOCV) calculations are performed in order to shed light on the nature of non-covalent interactions that determine the stability of the obtained structures.
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Mahmoudi, Ghodrat, Damir A. Safin, Mariusz P. Mitoraj, Mojtaba Amini, Maciej Kubicki, Thomas Doert, Franziska Locherer, and Michel Fleck. "Anion-driven tetrel bond-induced engineering of lead(II) architectures with N′-(1-(2-pyridyl)ethylidene)nicotinohydrazide: experimental and theoretical findings." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-224307.
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The evaluation of N′-(1-(2-pyridyl)ethylidene)nicotinohydrazide (HL) as a linker for the PbII tagged extended structures is described. The reaction of Pb(ClO4)2 or Pb(OAc)2 with HL in MeOH at 60 °C and room temperature, respectively, leads to heteroleptic complexes {[PbL]ClO4}n·nH2O and [PbL(OAc)]2, while the same reaction of Pb(ClO4)2 with HL at 60 °C in the presence of two equivalents of NaOAc or NaNO2 leads to heteroleptic complexes {[Pb(HL)(OAc)]ClO4}n and [PbL(NO2)]n, respectively. Using Pb(NO3)2 as a source of PbII in the same reaction with HL and two equivalents of NaN3 or NaNCS at room temperature yields [PbLN3]n and [Pb2(HL)2(NO3)2(NCS)2], respectively. The room temperature reaction of Pb(NO3)2 with HL in the presence of two equivalents of NaClO4 leads to the transformation of the parent ligand to its perchlorate salt [H2L]ClO4. In all the obtained PbII structures, HL or its deprotonated form L acts both as a chelating and a bridging ligand. The nature of the inorganic anion also influences the final structure. In all complexes the PbII center exhibits a hemidirected coordination geometry with all the covalent bonds being concentrated on one hemisphere of the coordination sphere with the closest approach of two atoms on the other side varying from 151° to 232°. The sterically available PbII ion participates in tetrel bonding as evidenced from the detailed structural analysis of the described complexes. As a result of tetrel bonding, the structures of all the six compounds can be extended to a higher dimensional framework, which is further stabilized by π⋯π stacking interactions between the aromatic rings. The DFT based charge and energy decomposition (ETS-NOCV) calculations are performed in order to shed light on the nature of non-covalent interactions that determine the stability of the obtained structures.
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Hames, Tim. "Playing Tetris with porphyrins : the synthesis of porphyrinic materials for self-sssembly studies." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37990/.
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This thesis focuses on the synthesis of porphyrinic materials for self-assembly studies. It begins with the synthesis of a large number of ‘building block’ molecules, terminated with bromo-, alkyne- and TMS- groups. These molecular building blocks are combined to form porphyrin compounds also terminated with bromo- alkyne- and TMS- groups at carefully selected positions. A series of porphyrin arrays inspired by the computer game Tetris was designed to be synthesised from these porphyrin units. The Tetris compounds are comprised of four square-like tetraphenylporphyrin (TPP) units, linked together with alkyne bridges to create arrays shaped like the T, I, L/J, S/Z and O Tetriminos. The NMR spectroscopy of the Tetris compounds is thoroughly explored to highlight the slight structural differences between the molecules. The synthesis of two bromoaryl-terminated porphyrin dimers for ultimate incorporation into covalent organic frameworks (COFs) is also described. The X-ray diffraction data collected showed that crystals grown were of trifluoroacetic acid (TFA) salts of the target compounds. The presence of the TFA anions resulted in significant distortion of the porphyrin ring which is described in full. Finally, the synthesis of a series of poly(acetylene) anthracene dimer compounds that have potential use in the field of organic electronics has also been explored. The electrochemical and fluorescence properties of the molecules across the series are investigated and the crystal structures are described.
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Skorka-Brown, Jessica. "Cognitive processes in craving : from the laboratory to the real world." Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3227.
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Elaborated Intrusion (EI) Theory posits that craving involves mental imagery in the same sensory modalities as the craved substance or activity. Visual imagery predominates, therefore craving should selectively interfere with performance on visual task, and conversely visual tasks should interfere with craving. This thesis reports tests of this prediction, both in the laboratory and real-world settings, to provide a basis for designing practical tasks for interfering with cravings in a natural environment. Contrary to predictions, experiments 1 and 2 showed no effect of craving on visual or verbal task performance. There were, however, effects of task performance on craving in experiment 2. Experiment 3 found that playing Tetris reduced craving relative to a no-task control (watching a load screen), but was no more effective than digit recall or counting in ones. Experiments 4 and 5 both compared the effects of visual pattern recall with digit recall, with contradictory results. Experiment 4 showed an effect of low load visual task on craving, but not verbal; whereas Experiment 5 found no impact of either task. Overall, the findings are consistent with the assumption that craving involves controlled cognitive processes, but do not clearly support or disprove the hypothesis that visual processes are key. Experiment 6 focussed on interfering with naturally occurring cravings in a laboratory setting. Playing the computer game Tetris reduced cravings compared to a no task control. The final study of this thesis examined cravings in a natural environment. Participants were lent an iPod with either a questionnaire-only task, or a task with the questionnaire and Tetris installed on it. They were prompted by SMS to complete the task at pseudo-random intervals across the day over the course of a week. Mixed effects regression and multilevel growth curve modelling showed that Tetris was effective at decreasing naturally occurring cravings in a natural environment but the binary measure used, did not find a reduction in indulgence rates, however other more sensitive measures may. In contrast to the literature reviewed, the findings from this thesis are more consistent with craving involving general cognitive effort rather than modality-specific processes. Games such as Tetris appear to have potential as take-home tasks in future research and to help people manage their cravings.
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Hoff, Miriam Schifferli. "Pensamento dial?tico e poss?veis em um jogo computadorizado." Pontif?cia Universidade Cat?lica de Campinas, 2001. http://tede.bibliotecadigital.puc-campinas.edu.br:8080/jspui/handle/tede/407.
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Previous issue date: 2001-08-31Within a Piagetian and a micro genetic approach, it was investigated the dialectic thought and the construction of possibilities in the solution and comprehension of a computer game. A previous study with a group of adolescents, made up of 40 boys and 26 girls from 6th. to 8th. grades, showed personalized preferences, without a group tendency and linked to complex games. The need for non-experienced subjects in such games and for starting studies making use of a simpler game, led to the research of Tetris solution by two female university students. The procedure, which was individual and videotaped, consisted of a 4-proof pre-evaluation of possibilities, 9 sessions using Tetris (more than 30 games and about 10-hour filming per person) and 3 self-evaluations (after session-1; before sessions 4 and 9). The pre-evaluation revealed a formal level of thought for both subjects. A quantitative analysis showed great progress of the subjects: throughout the sessions, there was a fall in the average number of games, associated to long lasting games, to a larger production of lines and to a larger punctuation, with the advance from the building of unitary to double, triple and quadruple lines. The micro genetic analysis demonstrated the presence of equilibration as well as the dynamic of dialectic constructions and dialectic thoughts underlying the procedural and conceptual schemes. Although the final solutions have achieved a III-Level (Subject 1) and a II-III Level (Subject 2), there were initial possibilities and more elementary mistakes than it was hypothesized to people who had formal thought. On the other hand, the constructed interdependences, both initial and global, comprised larger complexity and scope than it was foreseen. The obtained results suggested that, when solving the Tetris, it was as if the subjects were remaking the cognitive evolution course, projecting their progress to the top level of their cognitive structures or tending to this level.
Com uma abordagem piagetiana e microgen?tica, investigou-se o pensamento dial?tico e a constitui??o de poss?veis na resolu??o e compreens?o de um jogo computadorizado. Um estudo pr?vio com adolescentes, 40 meninos e 26 meninas de 6? a 8? s?ries, mostrou prefer?ncias personalizadas, sem tend?ncia grupal e ligadas a jogos complexos. A necessidade de sujeitos inexperientes nestes jogos e de estudos iniciais com um jogo mais elementar levou ? pesquisa do processo resolutivo do Tetris por duas universit?rias. O procedimento, individual e filmado, incluiu pr?-avalia??o com 4 provas de poss?veis, 9 sess?es com o Tetris (mais de 30 jogos e cerca de 10 h de v?deo por sujeito) e 3 autoavalia??es (ap?s a sess?o-1; antes das sess?es 4 e 9). A pr?-avalia??o revelou n?vel formal de pensamento para os dois sujeitos. Uma an?lise quantitativa mostrou acentuado progresso dos sujeitos: ao longo das sess?es, queda no n?mero m?dio de jogos, associada ? sua maior dura??o, maior produ??o de linhas e maior pontua??o, com avan?o da forma??o de linhas unit?rias para compostas (duplas, triplas e qu?druplas). A an?lise microgen?tica da resolu??o indicou a presen?a de equilibra??o e da din?mica de constru??es dial?ticas e pensamento dial?tico, subjacentes aos esquemas procedurais e conceituais. Embora as solu??es finais tenham sido de N?vel-III (Sujeito 1) e N?vel II-III (Sujeito 2), ocorreram poss?veis iniciais e erros mais elementares do que o hipotetizado para sujeitos com pensamento formal. De outro lado, as interdepend?ncias criadas, iniciais como globais, comportaram abrang?ncia e complexidade maiores do que o previsto. Pelos dados obtidos, ao resolverem o Tetris, os sujeitos como que refizeram o percurso da evolu??o cognitiva, com seu progresso projetado at? o patamar de suas estruturas cognitivas ou tendendo a este patamar.
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James, Ella L. "Exploring the use of Tetris as a post-trauma 'cognitive vaccine' : from memory consolidation to reconsolidation." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:39cf0ad2-f214-495e-a39f-fdaff4e882e8.
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Re-experiencing trauma in the form of intrusive, image-based memories (here referred to as flashbacks) is a hallmark symptom of Post-Traumatic Stress Disorder (PTSD). There are successful treatments available for full-blown PTSD; however, these can only be administered one month post trauma. There are limited interventions that can be administered to reduce flashbacks in the early aftermath of trauma. The overarching aim of this thesis was to use an experimental psychopathology approach, the trauma film paradigm, to investigate the reduction of flashbacks post-trauma using the cognitive task, Tetris. Chapter 1 provides a literature review of experimental research that has used the trauma film paradigm. Chapter 2 reviews experimental work on disrupting memory reconsolidation in humans. Chapter 3 details pilot work on the development of an experimental protocol based upon these literature reviews. Experiment 1 (Chapter 4) investigated disrupting reconsolidation for a 24 hour old analogue trauma (aversive film material) using the cognitive task, Tetris. A procedure designed to disrupt flashback reconsolidation (a memory reactivation task for the film followed by playing the computer game Tetris) was compared with a no-task Control. Compared to Control, those in the Tetris condition reported fewer flashbacks to the film in an intrusion diary across the subsequent week and on convergent measures of flashback frequency. Experiment 2 (Chapter 5) provided a test of replication for findings from Experiment 1, in addition to extending findings by dismantling the procedure’s component parts. Participants who underwent Tetris only (without memory reactivation) or memory reactivation (without Tetris) did not demonstrate a reduction in flashbacks and were comparable to the no-task control condition. Both a memory reactivation task plus Tetris in combination were critical for reducing subsequent flashbacks for a consolidated memory for a trauma film. Experiment 3 (Chapter 6) tested whether playing Tetris could help disrupt flashback memories for an analogue trauma (film) if administered prior to film viewing, relative to a no-task control condition. Results showed that playing Tetris before a trauma film did not reduce flashbacks, as demonstrated via an intrusion diary and convergent flashback measures. Chapters 7 reviews email feedback relating to playing Tetris after experiencing real-life adversity from members of the public. Chapter 8 explores a form of treatment for trauma in a NHS, complex patient setting. Chapter 9 discusses the findings from all chapters with reference to their implications and limitations, and new directions for future research. Overall, findings using analogue trauma suggest that memory reactivation followed by playing Tetris may be promising for development as a post-trauma ‘cognitive vaccine’ to disrupt the both the consolidation and potential reconsolidation of flashback memories.
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Mitzinger, Stefan Martin Jürgen [Verfasser], and Stefanie [Akademischer Betreuer] Dehnen. "Synthesis and Derivatisation of Hetero-Atomic Zintl Anions and Multi-Metallic Clusters of the Tetrel and Pentel Elements / Stefan Martin Jürgen Mitzinger ; Betreuer: Stefanie Dehnen." Marburg : Philipps-Universität Marburg, 2018. http://d-nb.info/1156461707/34.
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Kratzert, Daniel [Verfasser], Dietmar [Akademischer Betreuer] Stalke, George M. [Akademischer Betreuer] Sheldrick, Herbert W. [Akademischer Betreuer] Roesky, Inke [Akademischer Betreuer] Siewert, Heidrun [Akademischer Betreuer] Sowa, and Thomas [Akademischer Betreuer] Waitz. "Charge Density Distribution in Low-Valent Tetreles / Daniel Kratzert. Gutachter: Dietmar Stalke ; George M. Sheldrick ; Herbert W. Roesky ; Inke Siewert ; Heidrun Sowa ; Thomas Waitz. Betreuer: Dietmar Stalke." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://d-nb.info/1044414162/34.
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Kratzert, Daniel Verfasser], Dietmar [Akademischer Betreuer] Stalke, George M. [Akademischer Betreuer] Sheldrick, Herbert W. [Akademischer Betreuer] Roesky, Inke [Akademischer Betreuer] Siewert, Heidrun [Akademischer Betreuer] [Sowa, and Thomas [Akademischer Betreuer] Waitz. "Charge Density Distribution in Low-Valent Tetreles / Daniel Kratzert. Gutachter: Dietmar Stalke ; George M. Sheldrick ; Herbert W. Roesky ; Inke Siewert ; Heidrun Sowa ; Thomas Waitz. Betreuer: Dietmar Stalke." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://nbn-resolving.de/urn:nbn:de:gbv:7-11858/00-1735-0000-001C-63A3-B-6.
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Altun, Yasemin. "Addition Of Carbonyl Compounds To The Cyclic Olefins: Synthesis Of Cyclitols." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12610117/index.pdf.
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ABSTRACT
ADDITION OF CARBONYL COMPOUNDS TO THE CYCLIC OLEFINS: SYNTHESIS OF CYCLITOLS
Altun, Yasemin
M.S., Department of Chemistry
Supervisor: Prof. Dr. Metin Balci
October 2008, 160 pages
Cyclitols have attracted a great deal of attention in recent years owing to biological activities exhibited by them and also their usefulness in the synthesis of other natural products and pharmaceuticals. Carbasugars are also a derivative of cyclitols and they are cyclic monosaccharide analogues which posses –
CH2OH group in their structure. In this study, novel synthetic strategies leading to cyclitol derivatives were investigated and the synthesis of tetraol (72) and pentaol (73) derivatives containing &
#8211
CH2OH group were achieved successfully. Moreover, by the use of manganese(III) acetate oxidation reactions having considerable synthetic utilities in organic chemistry we developed new synthetic methodologies for the cyclitol derivatives. 1,3- and 1,4-Cyclohexadiene (71 and 10) were synthesized from easily available starting materials in order to be used as key compounds. The use of manganese(III) acetate oxidation reaction provides the creation of &
#8211
CH2OH group and one of the hydroxyl groups and the remaining hydroxyl groups were introduced into the key compounds by the use of singlet oxygen reaction. As a result of this, we had considerable advance in the synthesis of cyclitol derivatives.
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Siggelkow, Lisa [Verfasser], Thomas F. [Akademischer Betreuer] Fässler, and Wolfgang [Akademischer Betreuer] Domcke. "Synthesis, Characterization and Computational Studies of Binary and Ternary Intermetallic Compounds in the Systems Alkaline Earth Metal, Transition Metal, Tetrel Element / Lisa Siggelkow. Gutachter: Wolfgang Domcke. Betreuer: Thomas F. Fässler." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1029350175/34.
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Zhong, Yang. "Tetrisskolan." Thesis, KTH, Arkitektur, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231053.
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Tetrisskolan är en F-6-skola för drygt 420 elever, belägen i Henriksdal i Stockholm.Skolans titel kommer från det dess arkitektur ursprungligen är inspirerat av - pusselspel, framförallt Tetris. Valet av just Tetris var främst för att utforska segmentens former och se vad de kunde skapa för rum, både i plan och sektion. Tetris segment består alla av fyra kvadrater och därför valde jag att utgå från ett rutnät för att experimentera med planskisser samt volym. I rutnätet användes huvudsakligen måttet 3.7 x 3.7 m, men även 1.85 x 1.85 m och 0.925 x 0.925 m för att göra planerna mer yteffektiva. Skolbyggnaden består alltså av kuber i de dimensionerna. Färgvariationen på Tetris-figurerna var också en stor inspiration, både interiört och exteriört. Jag ville skapa en färgglad och lekfull miljö för barnen. Med hjälp av pusselteman kan de också påverka barnens logiska samt analytiska tänkande positivt. Dessutom blir det också en stor kontrast till tomten som annars kan uppfattas som oattraktiv då den är belägen precis bredvid en motorväg. Dock har den också många bra kvalitéer som till exempel att det redan finns en befintlig lekplats där, bra med kollektivtrafik samt nära till vatten (Henriksdalshamnen) och omgivningen annars är väldigt trevlig.Tetris School is a pre- and primary school for about 420 pupils, located at Henriksdal in Stockholm.The school’s architecture was inspired by puzzle games, mostly Tetris. The choice of using Tetris was to explore the shapes of the games’ segments and discover what kinds of space they could create, both in plans and sections. The segments consists of four squares, therefore I chose to use a grid to experiment with the plans and volumes.The squares used in the grid had mostly the measurements 3.7 x 3.7 m, but also 1.85 x 1.85 m and 0.925 x 0.925 m to make it more space efficient. Cubes in these three dimensions form the whole school building. Another big inspiration from the Tetris game was the color variations, which were used both in the interior and exterior, creating a playful surrounding for the pupils. Applying puzzle themes like this may affect their logical and analytical thinking positively. The pop of colors also make a big contrast to the site which can be perceived as an unattractive place because of the highway next to it. But the site also has good qualities like an already existing playground, efficient infrastructure, public transportation and water (Henriksdalshamnen) nearby. And the surrounding environment is overall very favorable.
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TIBÚRCIO, Viviane Pereira. "Avaliação do teor de ácido graxo das microalgas Pediastrum tetras e Scenedesmus acuminatus sob fótico e térmico para produção de biodiesel." Universidade Federal de Campina Grande, 2014. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/530.
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A busca por alternativas energéticas viáveis, de baixo custo, sustentáveis e que possam substituir o uso de combustíveis fósseis tem aumentado. Neste contexto, os biocombustíveis derivados de microalgas torna-se uma opção promissora quer seja do ponto de vista econômico como do ponto de vista ambiental. Os cultivos de microalgas produzem elevada quantidade de biomassa em curto tempo e não requerem extensas áreas para sua produção como acontece com a cana de açúcar utilizada para a produção de etanol, ou a soja, no caso do biodiesel. Este trabalho teve o propósito de caracterizar o potencial de produção de ácidos graxos de microalgas isoladas da região semiárida do estado da Paraíba mantidas em cultivo monoespecífico no banco de culturas de microalgas do LARBIM/UFPB e selecionar espécies potencialmente produtoras desses compostos visando cultivá-las em diferentes condições de estresse com o propósito de incrementar o rendimento final dos ácidos graxos de interesse à produção de biodiesel. Os cultivos foram desenvolvidos utilizando os meios Zarrouk e WC em câmara de cultura a 25°C±1ºC dotada de sistema de iluminação, com fotoperíodo de 12 horas. Foram estudadas 12 cepas incluídas em 7 espécies representantes dos grupos das cianobactérias e clorofíceas. A quantificação de ácidos graxos de cada uma das microalgas estudadas, foi determinado por cromatografia a gás. Duas espécies Pediastrum tetras (D121WC) e Scenedesmus acuminatus (D115WC) apresentaram teores de ácidos graxos 802,1% em relação a soja 211,1% em relação a soja, respectivamente. Por essa razão essas espécies foram cultivadas em diferentes condições de estresse nas mesmas condições de temperatura e fotoperíodo, utilizando-se estresses fótico, térmico e nutricional. Ao final de cada experimento foram determinadas para cada condição testada, os teores de protrínas, lipídeos e carbiodratos. As curvas de crescimento foram acompanhas por medida de fluorescência in vivo, em triplicatas, e todos os parâmetros de crescimento foram analisados para cada espécie testada. Observou-se maior taxa de divisão celular por dia na espécie D112Z (0,71 divisão/dia). Os teores de ácidos graxos na cepa D121WC aumentaram mais do que o dobro sob a condição de estresse fótico. Já para a espécie D115WC ocorreu um aumento no rendimento de ácido graxo ao condiciona-la a estresse térmico de 590,8% em relação à soja. Apesar das duas espécies testadas (Pediastrum tetras e Scenedesmus acuminatus) serem potencialmente importantes para a produção de biodiesel, evidenciase que suas respostas fisiológicas às condições de estresse não são as mesmas.
The search for viable energy alternatives, low cost, sustainable and can replace the use of fossil fuels has increased. In this context, biofuels derived from microalgae become a promising option either from the economic point of view as from the environmental point of view. The cultivation of microalgae produce higher amount of biomass in a short time and require large areas for their production as with sugarcane used for ethanol production, or soybean in the case biodiesel. This study aimed to characterize the potential for production of fatty acids from microalgae isolated from the semiarid region of the state of Paraiba kept growing in monospecific cultures of microalgae bank of LARBIM / UFPB and select potentially producing species of these compounds in order to grow them different stress conditions in order to increase the final yield of the fatty acids of interest for biodiesel production. The cultures were developed using the means Zarrouk and toilet in a growth chamber at 25 ° C ± 1 ° C equipped with lighting system, with a photoperiod of 12 hours. 12 strains included representatives of groups of cyanobacteria and green algae were studied in seven species. The quantification of each fatty microalgae studied acids was determined by gas chromatography. Two species Pediastrum tetras (D121WC) and Scenedesmus acuminatus (D115WC) showed levels of fatty acids 802.1% compared to 211.1% in soybeans compared to soybean, respectively. Therefore these species were grown under different conditions of stress under the same conditions of temperature and photoperiod, using photic, thermal and nutritional stresses. At the end of each experiment were determined for each condition tested, the levels of proteins, lipids and carbohydrates. The growth curves were avidly by measuring in vivo fluorescence in triplicate, and all growth parameters were analyzed for each species tested. Observed a higher rate of cell division per day in D112Z (0.71 divisions / day) species. The levels of fatty acids in strain D121WC increased more than twice on condition of photic stress. As for the species D115WC was an increase in the yield of fatty acid to condition it to heat stress of 590.8% compared to soybean. Although the two potentially important for the production of biodiesel tested species (Pediastrum tetras and Scenedesmus acuminatus) are, it is evident that their physiological responses to stress conditions are not the same.
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Burton, Simon Mark. "The effect of environmental factors and hormone treatments on ovulation rate and spawning success in cardinal tetras, Paracheirodon axelrodi (Pisces: Characidae)." Thesis, Rhodes University, 1998. http://hdl.handle.net/10962/d1005117.
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Cardinal tetras, Paracheirodon axelrodi (Pisces: Characidae), are among the most popular tropical ornamental fish in the world. Millions of cardinal tetras are removed from their natural habitat, the upper tributaries of the Rio Negro in Brazil, each year and exported to North America and Europe where they are abundantly available at low cost. This, combined with the fact that they do not spawn freely in captivity has excluded any incentive to culture this fish on a commercial scale in these areas. However, the demand for cardinal tetras in South Africa is high, but their availability is limited to sporadic imports of wild caught fish which has resulted in an increase in their relative value. Thus, there is an appreciable incentive to investigate methods for inducing this species to reproduce in captivity. Information on methods for inducing spawning would form an integral part of a potential production plan for the culture of this species in South Africa. This study consisted of a number of experiments designed to investigate factors related to the spawning of cardinal tetras in captivity. The first series of experiments investigated the effect of variables such as the water chemistry of the experimental system, the sex ratio of the fish, the effect of conditioning and the effect of different spawning media on spawning success. The second series of experiments tested the effects of various environmental stimuli or hormonal treatments on spawning in cardinal tetras. Environmental stimuli tested included a rise in temperature, a rise in water level and a fresh rain water flush. Hormonal treatments included feeding GnRHa enriched brine shrimps to the fish or the application of hormone injections (hypophysation). Neither environmental stimuli nor brine shrimp enrichment induced cardinals to spawn in a repeatable manner. The same was true for hypophysation, but in this case a low incedence of ovulation of injected females was observed. Oocytes from ovulated and non-ovulated females were examined under a microscope and from this it was determined that cardinal tetras are group synchronous spawners, containing two distinct cohorts of oocytes in the ovary. The effect of a number of environmental stimuli on ovulation rate in cardinal tetras were then tested but did not induce ovulation in any females. A series of three experiments was performed investigating the effect of conditioning the sexes together on ovulation rate and spawning success. Conditioning the sexes together had no effect on spawning success, but a significantly higher ovulation rate was observed in females that vvere conditioned together with males. Male cardinals did not follow this trend and lost condition when conditioned together with females. The next experiment tested if pheromones from red serpae tetras, Hyphessobrycon serpae, could be used to induce ovulation and spawning in cardinal tetras. This was found not to be the case. The final series of experiments tested the effect of Aquaspawn® enriched Artemia on ovulation rates in female cardinal tetras. Aquaspawn® is a water soluble preparation of GnRHa and dopamine. Aquaspawn® enriched Artemia were found to be effective for inducing female cardinal tetras to ovulate. However, the results from this method of enrichment were not entirely reliable and further research is warranted. Finally, a protocol for evaluating spawning in topical, freshwater egg-laying fish was proposed, based on the results from this study. The advantages and disadvantages of such a protocol were discussed.
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Weitz, Selwyn Herbert. "The synthesis and analysis of (2R,3R)-1,1,4,4- tetraphenylbutane-1,2,3,4-tetraol (tetrol) and derivatives, and a study of their host potential." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/3735.
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This investigation focussed on the inclusion and resolution ability of (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL), studies on the stoichiometry of its derivatives and the formation of inclusion compounds for single crystal analysis. The guest compounds that featured in the main study were cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone. It was found that 3- and 4-methylcyclohexanone were trapped in their energetically unfavourable axial conformations in the inclusion crystal. Resolution experiments proved that (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol can be used as a resolving agent for 2- and 3-methylcyclohexanone, with ee values of 13% and 22%, respectively (according to the method of Hiemstra), in favour of the R-enantiomer. Single crystal X-ray diffraction (SCXRD) studies, however, showed that 2-methylcyclohexanone was resolved with an ee of 30% in R. An ee of 56% in R was obtained for 3-methylcyclohexanone. Enantiomer enrichment of 2-methylcyclohexanone was achieved in basic medium (ee of 18% according to the method of Hiemstra) and showed that by using the host in either half or double the molar ratio of the guest, a higher ee was obtained than for a 1:1 ratio. The following TETROL derivatives were also synthesized and their stoichiometries with various guest compounds were determined: (2R,3R)-1,1,4,4-tetra(naphthalen-1-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(naphthalen-2-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-anisyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-tolyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(m-tolyl)butane-1,2,3,4-tetraol and; (2R,3R)-1,1,4,4-tetra(o-tolyl)butane-1,2,3,4-tetraol.
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Cantekin, Seda. "The Development Of The Novel Synthesis For Conduritols." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607609/index.pdf.
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Conduritols have attracted a great deal of attention in recent years owing to biological activities exhibited by them and also their usefulness in the synthesis of other natural products and pharmaceuticals. Conduritols show interesting inhibitor activity for some glycosidases and serve as important intermediates in the synthesis of inositols. In this study, novel synthetic strategies leading to highly functionalized cyclohexene derivative containing an aromatic ring, namely phenyl-substituted conduritol was achieved successfully for the first time. As the starting material, substituted benzoquinone derivative, biphenyl-2-ol was used. Bromination of one double bond followed by the reduction of the carbonyl groups served the desired skeleton. Further substitution of the bromine atoms and functionalization of the remaining double bond opened up an entry for the synthesis of substituted conduritol and inositol derivatives. Moreover, by the use of hydroquinone as a starting material we developed new synthetic methodologies for the synthesis of another conduritol derivative, bromo-substituted conduritol for the first time. Oxidation of hydroquinone to the corresponding quinone followed by the bromination of one double bond gave the desired product. After the reduction of the carbonyl groups and protection of the hydroxyl groups, the key compound for the synthesis of bromo-substituted conduritol was obtained. As a result, we enabled to synthesize new conduritol derivatives and we had considerable advance for the synthesis of other conduritol derivatives, inositols and quercitols.
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Mir, Morro Bartomeu. "Studies on the formation of i-motif structures at neutral pH. Use of cytidine analogues and importance of minor groove tetrads on mini i-motifs stabilization." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668126.
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Given the increasing interest in i-motif structures, obtaining such structures as well as detailed structural information under physiological conditions have become hot topics in the structural biology field. In this context, the main objectives of this thesis are focused on the design and detailed characterization of several oligonucleotide sequences that may form stable i-motif structures at neutral pH. The starting point is the mini i-motif structure, extensively studied in the research group that exhibits unusual high pH and thermal stability. These are dimeric structures stabilized by the formation of two hemiprotonated C:C+ base pairs capped at both ends by minor groove G:T:G:T tetrads. With the aim of getting deeper insights in this type of structures and enhance their stability at physiological conditions, different approaches were followed.
A first strategy consisted in the incorporation of a neutral analogue of protonated cytidine (pseudoisocytidine, psC) occupying specific positions of the motif. The 3H-tautomer of psC, thanks to the extra hydrogen-bond donor, can form neutral base pairs completely isomorphic to hemiprotonated C:C+ pairs. psC was incorporated in different positions of dimeric mini i-motifs and in the telomeric sequence (HT0). The effect of the incorporation of psC depends on its position in the structure, being in most cases destabilizing. Neutral psC:C base pairs stabilize i-motifs at neutral pH, but the stabilization only occurs when psC:C base pairs are located at the ends of intercalated C:C+ stacks. Structural and stability data on the incorporation of pseudocytidine in i-motifs suggest that positively charged base pairs in the core of the structure are necessary to stabilize this non-canonical DNA structure.
A second approach focused on exploring the compatibility of i-motif structures with other reported minor groove tetrads. The effect of different minor groove tetrads in i-motifs was studied in the context of short linear and cyclic oligonucleotides, affording dimeric mini i-motifs, but also in longer sequences that may form monomeric mini i-motif structures. The results show that the mini i-motif is compatible with different type of minor groove tetrads and a stability ranking could be established: G:C:G:T ≥ G:C:G:C >> G:T:G:T, exhibiting monomeric structures enhanced stability. Interestingly, a consensus sequence was outlined based on the results obtained for the set of mini i-motif-forming sequences. The mapping of this sequence throughout the human genome by bioinformatics analysis revealed a statistical prevalence. The distribution found for these sequences is not random, being much more frequent in regulatory regions
Finally, a fluorescent cytidine analogue (1,3-diaza-2-oxophenoxazine, tCo), capable to hybridize as a cytosine and maintaining the ability to form Watson-Crick as well as hemiprotonated base pairs, was tested as an internal probe for the characterization of local environments within i-motif structures. NMR spectroscopy indicated both types of hybridization (tCo:C+ and G:tCo) are compatible with the mini i-motif structure at neutral pH. Interestingly, the fluorescence signal of tCo suffers a sever quenching when forming an hemiprotonated base pair, compared to the very little quenching that shows upon WC hybridization. Hence, tCo was successfully used as fluorescent probe for monitoring conformational transitions between different species of tCo-containing sequences. Moreover, when replacing a cytosine residue involved in a C:C+ pair, the favorable stacking between tCo and G:C base pairs from the capping minor groove assemblies provokes enhanced stability of the structure against both pH and temperature. Very remarkably, the visualization of mini i-motif structures in cellular media was accomplished by confocal fluorescence microscopy after the successful transfection of HeLa cells with tCo-containing oligonucleotides.En el marc de les estructures no canòniques dels àcids nucleics i les seves possibles implicacions biològiques, aquesta tesi te com a objectiu principal l’obtenció i caracterització estructural d’estructures i- motif que siguin estables a pH neutre. El punt de partida és l’estructura mini i-motif, un tipus de motiu que presenta una inusual elevada estabilitat front pH i temperatura. Es tracta d’una estructura dimèrica estabilitzada per la formació de dos parells hemiprotonats C:C+ que interaccionen per apilament amb dues tètrades G:T:G:T de solc menor que actuen de tapa de l’estructura. Per a aprofundir en l’estudi d’aquest tipus de motius i augmentar-ne la seva estabilitat a pH fisiològic, diferents aproximacions s’han dut a terme. En la primera aproximació, s’ha explorat la incorporació d’un anàleg neutre de citidina protonada (pseudoisocitidina, psC), capaç de formar parells neutres isomòrfics als parells hemiprotonats C:C+. Els estudis realitzats demostren que l’efecte de la psC en depèn fortament de la posició dins l’estructura. La formació de parells hemiprotonats al centre de l’estructura és fonamental i la formació de parells neutres només és tolerada pels parells terminals, produint-se en aquest cas una certa estabilització. Una segona línia de treball s’ha centrat en explorar la compatibilitat d’estructures i-motif amb altres tètrades de solc menor. S’han estudiat diferents seqüències, lineals i cícliques, que donarien lloc a estructures mini i-motif amb diferents associacions de nucleobases a les tètrades. Els estudis demostren que el mini i-motif és compatible amb diferents tètrades de solc menor i s’ha pogut establir el següent rànquing d’estabilitat G:C:G:T ≥ G:C:G:C >> G:T:G:T. Cal destacar que, la seqüència consens per aquest tipus d’estructures s’ha determinat que és prevalent al genoma humà. Finalment, s’ha incorporat un anàleg de citidina fluorescent (1,3-diaza-2-oxofenoxazina, tCo), substituint citosines en posicions especifiques de l’estructura. Els resultats demostren que tCo actua de forma eficient com a sonda local per a monitoritzar transicions conformacionals i que, en posicions específiques te un efecte força positiu en l’estabilitat tèrmica del motiu. Aquest fet ha permès utilitzat un d’aquests derivats per a visualitzar el plegament de l’estructura en medi cel·lular.
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Stegmaier, Saskia [Verfasser], Thomas F. [Akademischer Betreuer] Fässler, Hubert [Akademischer Betreuer] Schmidbaur, and Karsten [Akademischer Betreuer] Reuter. "Clusters and Networks of Tetrel Elements and Late d Block Metals in Ternary Intermetallic Phases with Alkali and Alkaline Earth Metals / Saskia Stegmaier. Gutachter: Thomas F. Fässler ; Hubert Schmidbaur ; Karsten Reuter. Betreuer: Thomas F. Fässler." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1051935032/34.
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Castillo, Rodrigo. "Synthesis of silicon- and germanium-rich phases at high-pressure conditions." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-207708.
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The main focus of the present work was the Ge-rich part of the binary Ba – Ge system, in which by inspecting the behavior of the clathrate-I Ba8Ge43 under pressure, several new phases were found. The new phases in this system have the following compositions: BaGe3 (with two modifications), BaGe5, BaGe5.5 and BaGe6, therefore they are quite close in composition range: 75% - ~85% at. Ge.
Concerning the conditions required for the synthesis of each phase, several combinations of temperature and pressure were employed in order to find a stability range. It was possible to establish such a formation range for all phases. In some cases two phases were found for a given conditions and in many other cases three or more phases were found to coexist. Thus, the stability range of pressure and temperature for single phase formation turned out to be very narrow.
By inspecting of some structural features, for instance the interatomic distances, it is found that the average of the Ge – Ge distances change in line with the composition, i.e. the shorter contacts belong to BaGe6 while the longer distances are present in BaGe3 (both modification). An opposite trend is observed for the calculated density of each phase (neglecting the tI32 form of BaGe3): the lower density is found for BaGe3 and the denser compound is found to be BaGe6. Of course this is not coincidence, since due to the Ge content, BaGe6 has the largest molar mass. Similarly, by examining the density as a function of the interatomic distance. In such case, the denser compound is characterized by shorter Ge – Ge contacts, while the less dense phase holds the longest Ge – Ge contacts. This is in agreement with the building motifs within each crystal structure: columns in BaGe3 (open framework) passing through layers in BaGe5, ending in a three-dimensional network (closed framework) in BaGe6.
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Decout, Samuel. "Effets des patrons d'organisation spatiale du paysage sur l'habitat d'une espèce animale à gestion conservatoire : le cas de l'habitat de reproduction du tétras-lyre (Tetrao tetrix L. ) dans un contexte d'expansion des aulnaies vertes (Alnus alnobetula (Ehrh. ) C. Koch)." Université Joseph Fourier (Grenoble), 2007. http://www.theses.fr/2007GRE10066.
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Dans les Alpes du Nord françaises, les populations de tétras-Iyre sont menacées par la fermeture du paysage induite par la colonisation d'espèces ligneuses sur les pâturages abandonnés. Parmi ces espèces, l'aulne vert est considérée comme une menace majeur pour la conservation de l'habitat d reproduction du galliforme. Dans ce contexte, il est nécessaire de mieux connaître les effets de l'organisation spatiale de l'aulne vert sur l'occurrence des tétras-lyre afin de mieux maîtriser cette dynamique d'embuissonnement à l'échelle d'une gestion locale de cet habitat de reproduction. Ainsi, cette thèse s'est attachée dans un premier temps à mettre en évidence que l'occurrence du galliforme peut être prédite à l'aide d'indicateurs spatialisés relatifs à la structure du paysage induite par la distribution de l'aulne vert sur une étendue occupée au sein de son habitat de reproduction. En effet, des données de présence-absence du galliforme issues d'un échantillonnage systématique ont été combinées à une analyse d'organisation spatiale de l'aulne vert. Ceci a permis d'évaluer l'effet de certains indices paysagers sur la probabilité de présence du galliforme à l'aide de modèles de régression logistique. Nos résultats ont principalement montré que les poules de tétas-lyre sont sensibles à l'organisation spatiale de l'aulne vert alors que ce n'est pas le cas pour les coqs. Plus précisément, le taux de recouvrement de l'aulne vert, le nombre de patchs d'aulne vert et la somme des longueurs de lisières d'aulne vert sort apparus comme étant des prédicteurs significatifs de l'occurrence des poules. Ces trois prédicteurs ont ensuite été utilisés pour construire des modèles spatialement explicites décrivant l'occupation de l'espace par les poules en fonction d'une carte de distribution de l'aulne vert. Après validation des prédictions des modèles, le modèle le plus pertinent et le plus valide pour prédire l'occurrence des poules est celui utilisant la somme des longueurs de lisières associée au taux de recouvrement de l'aule vert. D'autre part, ce modèle a été combiné à un modèle de simulation de. La mise en évidence d'un lien entre des patrons paysagers et l'occupation de l'espace par les poules à une échelle fine suggère quhtégrer des indices paysagers spatialisés dans un modèle spatial et temporel devrait permettre de développer un outil d'aide à la gestion locale de l 'habitat du galliforme reposant sur une approche d'écologie du paysageLn the Northern French Alps, black grouse (Tetrao tetrix L. ) is threatened by landscape closing induced by the colonization ofligneous species on abandoned pastures. Among these species, green aider (Alnus alnobetula (Ehrh. ) C. Koch) is a major con cern fœ the conservation ofblack grouse reproduction habitat. Thus, it is necessary to get a better understanding of the effects of green aider spatial organization on black grouse occurrence i order to control these colonization at the local scale of action pans in favour of the reproduction habitat. This phD firstly focuses on bringing out that black grouse occurrence can be predicted by the means of spatialised indicators in relation to landscape structure induced by green alder. Lndeed, presenc(). Absence data from a systematic sampling were combined with a landscape analysis of green aider spatial organisation. This allowed to assess the effect ofsome landscape indices on black grouse probability of presence by using logistic regression. Our main results showed that females are influenced by green aider whereas it is not the case for the malesEspecially, green aider cover, green aider patches density and green aider total edge are significant predictors of females occurrence. Then, these three predictors were used for designing spatially explicit models describing the spatial occupation of black grouse females in relation to a green aider distribution map. Once the models prediction were validated, the more efficient and validated model appeared to be u!lig green aider total edge and cover. More over, this model were combined to a green aider dynamic of colonization model by the use of a stochastic cellular automatonB: this way, we managed to simulate the evolution in time and space of female occurrencein relation to the evolution of landscape patterns induced by green aider. The demonstrated link between landscape patterns and black grouse females spatial occupation at a fine scale argues that the use of landscape pattern index in a spatially ex pl icit model should allow to develop a tool for assessing action plans in favour of black grouse habitat conservation based on landscape ecology approach
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Suarez, Juan M. "Emotional Intelligence and its Link to Aggressive Cognition and Aggressive Affect Generated by Violent Video Game Use of Male Undergraduates." Xavier University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=xavier1452010918.
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Ménoni, Emmanuel. "Ecologie et dynamique des populations du Grand Tetras dans les Pyrénées, avec des références spéciales à la biologie de la reproduction chez les poules. Quelques applications à sa conservation : [thèse soutenue sur un ensemble de travaux]." Toulouse 3, 1991. http://www.theses.fr/1991TOU30243.
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Les travaux portent sur une population stable de grand tetras de haute-garonne et utilisent egalement des resultats recueillis dans d'autres forets des pyrenees centrales et dans une population declinante des pyrenees orientales. Ils furent realises de 1984 a 1991, a partir d'analyses de l'habitat, de decomptes annuels, printaniers, estivaux et hivernaux, de l'analyse des tableaux de chasse et de radiopistage. Avant les accouplements, les poules defendent un territoire de nidification, au plus pres des bons habitats a nichee. Le nombre de poules reproductrices est relie a la disponibilite de ces bons habitats, et semble regulier celui des coqs chanteurs. Dans les pyrenees centrales, il existe une segregation marquee des milieux par rapport a ceux des adultes. Cela permet de mettre en evidence que les places de chant s'installent en fonction d'un compromis entre l'attraction des coqs par les zones de reproduction des poules, et leurs propres exigences spatiales. Le taux de reproduction annuel est fluctuant, et en moyenne assez faible, mais suffisant pour assurer le maintien des effectifs, en fonction des taux de pertes et de mortalite calcules. Son determinisme et celui de ses fluctuations sont etudies, ainsi que differents aspects de l'ethologie des nichees, en particulier le comportement maternel des poules. Les mouvements (emigration ou immigration) entre forets voisines sont tres importants dans la dynamique des populations. Les fluctuations annuelles des effectifs d'adultes s'expliquent par celles du succes de la reproduction et des pertes naturelles ou dues a la chasse, mais plus encore par des mecanismes de regulation dependants de la densite. Grace aux connaissances acquises dans ces travaux, on a recherche l'impact de quelques activites humaines (chasse - exploitation forestiere ski)
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Meier, Katrin. "Hochdruck–Hochtemperatur–Synthese und Charakterisierung tetrelreicher Seltenerdmetallverbindungen und Darstellung von Ba8Ga16±xGe30∓x mittels Spark–Plasma–Sinterverfahren." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-105084.
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In dieser Dissertation wird die Darstellung tetrelreicher Seltenerdmetall–Verbindungen in den Systemen SE:Tt (SE = La, Nd, Sm, Gd, Tb, Ho, Lu; Tt = Si, Ge) und die Charakterisierung ihrer Eigenschaften beschrieben. Diese Verbindungen, welche mittels der Hochdruck–Hochtemperatur–Methode dargestellt wurden, zeigen neuartige Verknüpfungsmuster in der Tetrel–Partialstruktur. Neben der Charakterisierung der Verbindungen hinsichtlich der thermischen Stabilität und der physikalischen Eigenschaften bei Normaldruck wurde bei den Germanium–reichen Seltenerdmetall–Verbindungen eine Untersuchung der Veränderungen der Kristallstruktur bei Variation des Drucks oder der Temperatur vorgenommen. Die dargestellten Seltenerdmetall–Trisilicide SESi3 (SE = Gd, Ho, Lu) kristallisieren tetragonal isotyp zu YbSi3. LuSi3 zeigt Supraleitung mit Tc = 7.0 K. In den Systemen Gd–Si und SE–Ge (SE = La, Nd, Sm, Gd, Tb) wurden die Verbindungen GdSi5 und SEGe5 (SE = La, Nd, Sm, Gd, Tb) synthetisiert. Sie kristallisieren orthorhombisch isotyp zu LaGe5. Durch in–situ Röntgenbeugungsexperimente bei erhöhten Temperaturen kann die Existenz metastabiler Germanium–ärmerer Verbindungen SE2Ge9 (SE = Nd, Sm) nachgewiesen werden. Es handelt sich um Defektvarianten der Verbindungen SEGe5 (SE = Nd, Sm). Die strukturelle Verwandtschaft zum Aristotyp SEGe5 wird anhand einer Gruppe–Untergruppe–Beziehung aufgezeigt. Eine alternative Synthesemethode zur Darstellung tetrelreicher Verbindungen mit Gerüststrukturen bei extremen Reaktionsbedingungen stellt das Spark–Plasma–Sinterverfahren (SPS) dar. Die Darstellung der Clathratphase Ba8Ga16±xGe30∓x (x = 0, 1) erfolgte mittels SPS aus den Precursoren BaGa2±x (x = 0, 0.125) und Germanium. Die Untersuchungen der thermoelektrischen Eigenschaften zeigen, dass durch Variation der nominellen Zusammensetzung sowohl n–leitende als auch p–leitende Eigenschaften erhalten werden könnenIn this thesis the synthesis of tetrel–rich rare–earth metal compounds in the systems RE:Tt (RE = La, Nd, Sm, Gd, Tb, Ho, Lu; Tt = Si, Ge) and the characterization of their properties is described. These compounds, synthesized by means of high–pressure high–temperature method, show new structural motifs in the tetrel partial structure. The compounds were characterized with respect to their thermal stability and their physical properties at ambient pressure. In addition, the changes in the crystal structure of the germanium-rich rare–earth metal compounds by variation of pressure or temperature were investigated. The synthesized rare–earth trisilicides SESi3 (SE = Gd, Ho, Lu) crystallize tetragonal, isotypic to YbSi3. LuSi3 is a superconductor with Tc = 7.0 K. In the systems Gd–Si and SE–Ge (SE = La, Nd, Sm, Gd, Tb) the compounds GdSi5 and SEGe5 (SE = La, Nd, Sm, Gd, Tb) were synthesized. They crystallize orthorhombic isotypic to LaGe5. Using in-situ high–temperature X-ray experiments the metastable germanium-poorer compounds SE2Ge9 (SE = Nd, Sm) could be observed. These compounds are defect variants of the pentagermanides SEGe5 (SE = Nd, Sm). The structural relationship to the aristotype SEGe5 is given via a group-subgroup relation. An alternative synthesis route for the preparation of tetrel–rich compounds with framework structures at extreme reaction conditions is the spark plasma sintering method (SPS). The clathrate phase Ba8Ga16±xGe30∓x (x = 0, 1) was synthesized from the precursors BaGa2±x (x = 0, 0.125) and germanium by means of SPS. The investigation of the thermoelectric properties shows, that through variation of the nominal composition both n-type and p-type conduction properties can be obtained
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Hübner, Julia-Maria. "Beiträge zu Verbindungen von Silicium und Germanium mit Erdalkali- und Seltenerdmetallen unter Druck." 2020. https://tud.qucosa.de/id/qucosa%3A74482.
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Der Schwerpunkt der vorliegenden Arbeit lag auf der Synthese neuer binärer tetrelreicher Silicide und Germanide der Erdalkali- und Seltenerdmetalle. Die Verbindungen wurden unter Hochdruck-Hochtemperaturbedingungen mit einer Vielstempelpresse bei Drücken bis 15 GPa und Temperaturen bis 1500 K synthetisiert und umfassend charakterisiert.
Im Rahmen dieser Arbeit konnten binäre Silicide und Germanide der Erdalkali- und Seltenerdmetalle, basierend auf der Analyse der auftretenden Strukturmotive, insbesondere in der anionischen Teilstruktur, und der Anzahl der homoatomaren Tetrel-Tetrel-Bindungen, klassifiziert werden. Sieben Gruppen können unterschieden werden: Strukturen mit dichtesten Packungen, isolierten Atomen und Tt2-Hanteln (und Vierecken), isolierten Polyanionen, Ketten und Bändern, Schichten und Netzwerken. Die letzte Gruppe kann weiter in die Untergruppen dreidimensionaler Netzwerke ohne unterscheidbare Polyanionen, mit unterscheidbaren Polyanionen und aus unterscheidbaren kondensierten Käfigen in der anionischen Teilstruktur eingeteilt werden.
Bei den Verbindungen dieser Arbeit handelt es sich im Falle derer mit einer 1:3 Zusammensetzung um atomare Anordnungen mit kubisch dichtester Packung oder Schichtstrukturen. Die siliciumreicheren Verbindungen sind den Käfigverbindungen zuzuordnen. In den binären Systemen M-Tt (M = Ba, Sm, Lu) konnten die Tritetrele SmGe3, LuGe3 und BaSi3 erhalten werden. SmGe3 besitzt eine neue 2×2×2-Überstruktur des kubisch primitiven Cu3Au-Typs. Temperaturabhängige Messungen der magnetischen Suszeptibilität und des spezifischen elektrischen Widerstands zeigen metallisches Verhalten. LuGe3 ist isotyp zu DyGe3 und besitzt Ketten und Doppelschichten in der anionischen Ge-Teilstruktur. Messungen der magnetischen Suszeptibilität, der spezifischen Wärmekapazität und des spezifischen elektrischen Widerstands zeigen den Übergang in einen supraleitenden Zustand unterhalb einer Temperatur von 3.3(3) K. Um die Ge-Ketten mit im Vergleich zu elementaren Germanium langen Abständen dGe-Ge an Pulver- und Einkristalldaten näher zu charakterisieren, ist LuGe (FeB-Typ) mit dem Strukturmotiv eindimensionaler Germaniumketten als Referenzverbindung synthetisiert worden. Der Abstand in der eindimensionalen Germaniumkette steht in guter Übereinstimmung zu demjenigen in LuGe3 sowie zahlreicher weiterer Silicide und Germanide mit diesem Strukturmotiv. Die Bindungsanalyse der Ge-Ketten hat homoatomare Wechselwirkungen der Germaniumatome sowie heteroatomare Interaktionen unter Beteiligung von mehreren Lutetium- und Germaniumatomen ergeben. Im Falle von LuGe konnten sogar Hinweise auf Metall-Metall-Wechselwirkungen gefunden werden. Wechselwirkungen zwischen fünf Atomen konnten auch zwischen den Ge-Ketten und Lu in LuGe3 und zwischen dem jeweiligen Metallatom und den Tetrelschichten in BaSi3 bzw. -doppelschichten in LuGe3 gefunden werden. BaSi3 zeigt eine einzigartige atomare Anordnung, die als Deformationsvariante des CaGe3-Typs aufgefasst werden kann. Die Temperaturabhängigkeit des spezifischen elektrischen Widerstands und Messungen der magnetischen Suszeptibilität deuten auf metallisches Verhalten hin.
In den binären Systemen Mg-Si und Sr-Si sind siliciumreiche Verbindungen mit kondensierten Käfigen in der anionischen Teilstruktur gefunden worden. Die Bestimmung der Kristallstruktur von MgSi5 mittels Elektronendiffraktion hat die Grundlage für die Phasenbestimmung im Prozess der Syntheseoptimierung gebildet, was die Synthese von für Röntgendiffraktionsexperimente geeigneten Einkristallen ermöglicht hat. Die Kristallstruktur von MgSi5 (Raumgruppe Cmme) stellt einen neuen Typ eines Netzwerks vierbindiger Siliciumatome dar, welche Si15-Käfige um die Magnesiumatome bildet. Zwei Arten kleinerer Si8-Käfige bleiben leer. Die atomaren Wechselwirkungen werden durch zwei-Zentren-Bindungen innerhalb des Siliciumnetzwerks charakterisiert. Zusätzlich gibt es Wechselwirkungen unter Beteiligung von mehreren Magnesium- und Siliciumatomen in den großen Käfigen. Die Verbindung ist diamagnetisch. Sr8Si46 ist isotyp zu Na8Si46 (Clathtrat-I). Die Charakterisierung der Struktur ist an Pulver- und Einkristalldaten durchgeführt worden. Die Bindungsanalyse zeigt neben konventionellen kovalenten Bindungen innerhalb des Siliciumnetzwerks zusätzliche Wechselwirkungen zwischen mehreren Strontium- und Siliciumatomen in den Käfigen. Physikalische Messungen belegen den Übergang in den supraleitenden Zustand bei Temperaturen unterhalb von 3.8(3) K. Bei Normaldruck zersetzen sich die Hochdruckphasen, mit Ausnahme von LuGe, exotherm in Randphasen, die im jeweiligen Phasendiagramm stabil sind, und belegen damit ihren metastabilen Charakter.
Die systematische Analyse von Zusammensetzungen und Tetrelkonnektivitäten in Polyanionen binärer tetrelreicher Silicide und Germanide der Erdalkali- und Seltenerdmetalle hat eine Vielfalt von Motiven ergeben, deren Elektronenbilanz den klassischen Elektronenzählregeln nicht entspricht. Solche Grenzfälle zwischen Zintl-Phasen und intermetallischen Verbindungen können wichtige Einsichten in die chemische Bindung und Bausteine für die Entwicklung neuer Konzepte liefern. Diese Betrachtungen haben tetrelreiche Verbindungen mit der Zusammensetzung MTtx (M = Erdalkali- oder Seltenerdmetall, Tt = Si, Ge, x ≥ 3) als interessantes Arbeitsgebiet offenbart. Die Synthese dieser Verbindungen bedarf häufig Hochdruck-(Hochtemperatur)-Bedingungen. Während metallreiche Verbindungen meist dicht gepackte Strukturen aufweisen, in denen ionische Wechselwirkungen eine große Rolle spielen, wird die Bedeutung kovalenter Wechselwirkungen in tetrelreichen Verbindungen mit der Zusammensetzung MTtx (M = Erdalkali- oder Seltenerdmetall, Tt = Si, Ge, x ≥ 3) beispielsweise durch die Ähnlichkeit der normierten Volumina zu denen der entsprechenden Tetrele beleuchtet. Diese kovalenten Wechselwirkungen gehen meist mit metallischer Leitfähigkeit und in einigen Fällen mit Supraleitung einher. Zahlreiche dieser tetrelreichen Verbindungen überschreiten den Gültigkeitsbereich der 8-N-Regel und weisen keine elektronenpräzise Elektronenbilanz gemäß dem Zintl-Konzept auf. Die Untersuchung der interatomaren Abstände, Koordination und der chemischen Bindung schafft die Grundlage für die Entwicklung eines Konzepts zum Verständnis von Verbindungen, die sich an der Grenze zwischen Zintl-Phasen und intermetallischen Verbindungen befinden. Die Analyse der chemischen Bindung hat für die untersuchten Verbindungen Elektronenpaare offenbart, die in einem isolierten Molekül freien Elektronenpaaren entsprechen würden und die zu Wechselwirkungen zwischen der anionischen Partialstruktur und den Metallatomen beitragen.:Danksagung I
1. Einleitung 1
2. Grundlagen 3
2.1. Bindungskonzepte in polaren intermetallischen Phasen 3
2.1.1. Zintl-Klemm-Konzept 3
2.1.2. Quantenchemische Berechnungen zur Analyse der chemischen Bindung 4
2.2. Einfluss von Hochdruck- und Hochtemperaturbedingungen auf Materie 6
2.2.1. Hochdruck-Hochtemperaturmethoden im Überblick 8
2.2.2. Thermodynamische und kinetische Betrachtungen 10
2.2.3. Strukturelle Phasenumwandlungen unter Druck 12
2.2.4. Hochdruckmodifikationen der Tetrele 13
3. Methodik 15
3.1. Präparative Methoden 15
3.1.1. Edukte 15
3.1.2. Ausgangsverbindungen 15
3.1.3. Hochdruck-Hochtemperatur-Synthese 16
3.2. Charakterisierung 22
3.2.1. Thermische Analyse 22
3.2.2. Pulverröntgendiffraktometrie 22
3.2.3. Einkristallröntgendiffraktometrie 23
3.2.4. Chemische Analyse 23
3.2.5. Dichtebestimmung 24
3.2.6. Metallographische Analyse 24
3.2.7. Transmissionselektronenmikroskopie 25
3.2.8. Kernspinresonanzspektroskopie 26
3.2.9. Quantenchemische Berechnungen 27
3.2.10. Physikalische Eigenschaften 28
4. Ergebnisse 33
4.1. Strukturelle Klassifikation binärer Silicide und Germanide mit Erdalkaliund
Seltenerdmetallen 33
4.2. SmGe3 38
4.2.1. Synthese 38
4.2.2. Charakterisierung 38
4.3. LuGe 45
4.3.1. Darstellung 45
4.3.2. Charakterisierung 45
4.4. LuGe3 51
4.4.1. Synthese 51
4.4.2. Charakterisierung 52
4.5. BaSi3 62
4.5.1. Darstellung 62
4.5.2. Charakterisierung 62
4.6. MgSi5 72
4.6.1. Synthese 72
4.6.2. Charakterisierung 73
4.7. Sr8Si46 80
4.7.1. Präparation 80
4.7.2. Charakterisierung 80
4.8. Diskussion 91
4.8.1. Dichteste Packung in SmGe3 91
4.8.2. Ketten in LuGe und LuGe3 93
4.8.3. Schichten in BaSi3 und LuGe3 94
4.8.4. Kristallchemischer Vergleich von dichtesten Packungen, isolierten
Polyanionen, Ketten und Schichten in Tritetreliden 95
4.8.5. Käfigverbindungen MgSi5 und Sr8Si46 101
5. Vergleichende Diskussion binärer Silicide und Germanide der Erdalkali- und
Seltenerdmetalle 105
6. Zusammenfassung 113
Literaturverzeichnis 117
Abkürzungs- und Symbolverzeichnis 153
Abbildungsverzeichnis 157
Tabellenverzeichnis 167
Publikationen 169
Lebenslauf 171
Beiträge zu dieser Arbeit 173
A. Anhang 175
A.1. Grundlagen 175
A.1.1. Hochdruckmodifikationen der Tetrele 175
A.1.2. Bekannte binäre Silicide und Germanide mit Erdalkali- und Seltenerdmetallen 175
A.2. Methodik 179
A.2.1. Edukte 179
A.3. Ergebnisse 179
A.3.1. Sm3Ge5 179
A.3.2. SmGe3 181
A.3.3. MgSi5 181
A.4. Vergleichende Diskussion der binären Silicide und Germanide dieser Arbeit 182
B. Anhang 183
B.1. Ergebnisse 183
B.1.1. SmGe3 183
B.1.2. LuGe 185
B.1.3. LuGe3 188
B.1.4. BaSi3 192
B.1.5. MgSi5 195
B.1.6. Sr8Si46 203
Eidesstattliche Erklärung 210
47
Auer, Henry, Robert Schlegel, Oliver Oeckler, and Holger Kohlmann. "Structural and Electronic Flexibility in Hydrides of Zintl Phases with Tetrel–Hydrogen and Tetrel–Tetrel Bonds." 2017. https://ul.qucosa.de/id/qucosa%3A33408.
Full textAbstract:
The hydrogenation of Zintl phases enables the formation of new structural entities with main group elementhydrogen bonds in the solid state. The hydrogenation of SrSi, BaSi and BaGe yields the hydrides SrSiH5/3-x, BaSiH5/3-x and BaGeH5/3-x. The crystal structures show a six-fold superstructure compared to the parent Zintl phase and were solved by a combination of X-ray, neutron and electron diffraction and the aid of DFT calculations. Layers of connected HSr4 (HBa4) tetrahedra containing hydride ions alternate with layers of infinite single- and double-chain polyanions, where hydrogen atoms are covalently bound to silicon and germanium. The idealized formulae AeTtH5/3 (Ae = alkaline earth, Tt = tetrel) can be rationalized with the Zintl-Klemm concept according to (Ae2+)3(TtH-)(Tt2H2-)(H-)3, where all Tt atoms are three-binding. The non-stoichiometry (SrSiH5/3-x, x = 0.17(2); BaGeH5/3-x, x = 0.10(3)) can be explained by additional π-bonding of the Tt chains.
48
Kaye, Blaize Michael. "Tetris and mental rotation." Thesis, 2013. http://hdl.handle.net/10413/9301.
Full textAbstract:
Research has shown a possible causative link between playing the popular videogame
Tetris and improvements in Mental Rotation performance. The aim of the
present study was to address a question about an aspect of Tetris expertise that
had not yet been factored into any of the existing work on Tetris and Mental
Rotation. David Kirsh and Paul Maglio (1994) have shown that skilled Tetris
players appear to use physical actions as substitutes for, or compliments to,
mental operations. This is hypothesised to include physically rotating game
pieces instead of Mentally Rotating them. The specific question we sought to
address in the present study was whether these physical substitutes for mental
operations, which Kirsh and Maglio call epistemic actions, have an effect on
Tetris' efficacy as a Mental Rotation training task.
In order to address this research question, three groups of subjects were administered
tests of Mental Rotation ability before and after a five week training
period. The training period consisted of a total of five, hour long, laboratory
sessions - evenly spaced across the training period - in which each of the
three groups were required to play an assigned video-game. The results showed
that a group of subjects (N=13) who received Tetris training on the version of
the game that made epistemic actions involving rotation impossible showed no
greater Mental Rotation performance gains when their results were compared to
a group of subjects (N=13) trained using a Standard version of Tetris. This suggests
that the occurence of epistemic actions does not have an impact on Tetris'
efficacy as a Mental Rotation training task. Further, neither of these two groups
showed greater Mental Rotation performance gains than the non-Tetris control
group (N=14), a result which suggests that, at least under some circumstances,
Tetris training fails to impart Mental Rotation performance gains any greater
than what can be expected due to retest effects.Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2013.
49
Brzustowski, John. "Can you win at TETRIS?" Thesis, 1992. http://hdl.handle.net/2429/3263.
Full textAbstract:
TETRIS is a popular video game in which you try to fill rows in a rectangular well using a sequence of tetrominoes chosen by the machine. Each time you succeed in filling a row, it is deleted from the well. Your game ends when you have stacked pieces up to the top of the well. I build a model of TETRIS and analyze the worst-case scenario, in which the machine is treated as an adversary. I say you have a winning strategy when you can make your game last indefinitely. I construct winning strategies for some subsets of the TETRIS pieces, and prove that none exists for some others. Finally, I compare these analytic results to some empirical average-case data that I obtain from a passive survey of TETRIS players.
50
Spiekermann, Annette [Verfasser]. "Untersuchungen zur Reaktivität der Zintl-Anionen der Tetrele in Lösung mit Gold-Verbindungen / Annette Spiekermann." 2008. http://d-nb.info/994915926/34.
Full text