Low temperature fuel cells like proton exchange membrane fuel cells (PEMFC) are expected to play a crucial role in the future hydrogen economy, especially for transportation applications. These electrochemical devices offer significantly higher efficiency compared to conventional heat engines. However, use of exotic and expensive platinum as the electrocatalyst poses serious problems for commercial viability. In this regard, there is an urgent need to develop low-platinum or non-platinum electrocatalysts with electrocatalytic activity for the oxygen reduction reaction (ORR) superior or comparable to that of platinum. This dissertation first investigates non-platinum, palladium-based alloy electrocatalysts for ORR. Particularly, Pd-M (M = Mo and W) alloys are synthesized by a novel thermal decomposition of organo-metallic precursors. The carbon-supported Pd-M (M = Mo, W) electrocatalyts are then heat treated up to 900 oC in H2 atmosphere and investigated for their phase behavior. Cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements reveal that the alloying of Pd with Mo or W significantly enhances the catalytic activity for ORR as well as the stability (durability) of the electrocatalysts. Additionally, both the alloy systems exhibit high tolerance to methanol, which is particularly advantageous for direct methanol fuel cells (DMFC). The dissertation then focuses on one-pot synthesis of carbon-supported multi-metallic Pt-Pd-Co nanoalloys by a rapid microwave-assisted solvothermal (MW-ST) method. The multi-metallic alloy compositions synthesized by the MW-ST method show much higher catalytic activity for ORR compared to their counterparts synthesized by the conventional borohydride reduction method. Additionally, a series of Pt encapsulated Pd-Co nanoparticle electrocatalysts are synthesized by the MW-ST method and characterized to understand their phase behavior, surface composition, and electrocatalytic activity for ORR. Finally, the dissertation focuses on carbon-supported binary Pt@Cu and ternary PtxPd1-x@Cu “core-shell” nanoparticles synthesized by a novel galvanic displacement of Cu by Pt4+ and Pd2+ at ambient conditions. Structural characterizations suggest that the Pt@Cu nanoparticles have a Pt-Cu alloy layer sandwiched between a copper core and a Pt shell. The electrochemical data clearly point to an enhancement in the activity for ORR for the Pt@Cu “core-shell” nanoparticle electrocatalysts compared to the commercial Pt electrocatalyst, both on per unit mass of Pt and per unit active surface area basis. The increase in activity for ORR is ascribed to electronic modification of the outer Pt shell by the Pt-Cu alloy core. However, incorporation of Pd to obtain PtxPd1-x@Cu deteriorates the activity for ORR. / text

<p> This work was initiated with a view to elucidating the hitherto little-studied thermolysis of esters of oxalic acid. A number of symmetrical diesters were synthesized and several were investigated thoroughly by use of product studies, kinetic methods and kinetic isotope-effect measurements. Both preparative and pyrolytic procedures and results are recorded. The literature regarding previous studies of the effect of heat on oxalate esters is surveyed, and a review of the principles and uses of the investigative methods employed is presented. The results are discussed in the light of more recent work and both general and specific mechanisms for oxalate thermolysis are suggested.</p> / Thesis / Doctor of Philosophy (PhD)

Two-dimensional electrophoretic protein profiles of in vivo and in vitro propagated T.pallidum subsps. pallidum Nichols strain were analyzed and compared. This comparative analysis revealed two in vitro synthesized, cytoplasmic cylinder-associated polypeptides with molecular masses 29.5 and 34.7 kDa, pI 5.62, and one in vitro "lost" polypeptide with molecular mass 34.7 kDa, pI 5.34. integral membrane proteins of in vitro and in vivo propagated T. pallidum was identified by phase partitioning with the nonionic Triton X-114, and twelve outer membrane-associated, antigenic proteins were identified in western blots probed with pooled human secondary syphilitic sera. The solubilization of the outer membrane of T. pallidum with Triton X-114 were monitored by electron microscopy. Treatment of freshly harvested 35S labeled T. pallidum with 1% Triton X-114 resulted in solubilization of the outer membrane and reduction of the diameter of the treponemes from .14 +/- .02 micrometers to .095 +/- .003 micrometers. Examination of thin sections of untreated organisms showed integrity of outer and cytoplasmic membranes. In contrast, thin sections of Triton X-114-treated trponemes showed integrity of the cytoplasmic membrane but the loss of the outer membrane. The cytoplasmic cylinders generated by detergent treatment retained their periplasmic flagella, as judged by electron microscopy and immunoblotting. Integral membrane proteins of Treponema phagedenis were also identified by phase partitioning with Triton X-114, and sizteen cross-reactive, outer membrane-associated, outer membrane-associated, antigenic polypeptides were identified in western blots probed with pooled human secondary syphilitic sera. The results of this study indicate that tow-dimensional protein profiles of in vivo and in vitro propagated T.pallidum are almost identical except for the differences mentioned. This results also indicate that 1% Triton X-114 selectively solubilizes the outer membrane, and the antigenic hydrophobic proteins present in the detergent phrase are located exclusively in the outer membrane.

Philosophiae Doctor - PhD / With the rapid rise in energy demand and ever-escalating environmental hazards, the need for transition from fossil fuel to renewable energy sources is of paramount importance, requiring better and efficient energy storage devices such as supercapacitors. Supercapacitors are energy storage devices with high power density and long cycle life, but relatively low energy density when compared to batteries. New and advanced electrode materials are required to improve the energy density requirements of next-generation supercapacitors. However, the search for new types of active materials to be used as supercapacitors' electrodes continues to be a tough challenge. Herein, ruthenium antimony oxide (RuSbO) and ruthenium antimony oxide graphene (RuSbO-G) were synthesized via the microwave-assisted method for the first time and tested as a possible electrode material for an asymmetric supercapacitor. Graphene oxide prepared by modified Hummer’s method was exfoliated at low temperature and used for the synthesis of RuSbO-G. / 2025

<p> A series of 2-substituted Δ^3-1,3,4-oxadiazolines (i) were synthesized by oxidation of the corresponding hydrazones with lead-tetraacetate in alcohol, eq A. (See Diagram A in Thesis)</p> <p> These oxadiazolines, upon thermolysis, generated carbonyl ylide intermediates (ii). These ylides are known to undergo fragmentation into carbenes and carbonyl compounds, eq B. (See Diagram B in Thesis)</p> <p> A new series of products were found from the thermolysis of these types of oxadiazolines, ester azines iv and v. A possible mechanism for the formation of these ester azines involves carbene attack on the oxadiazoline to give an azomethine imine intermediate (iii) which can subsequently rearrange to give the azines and carbonyl compounds, eq C. (See Diagram C in Thesis)</p> <p> This mechanism is supported by the observation that the overall yields of ester azines rise with increasing initial concentration of oxadiazoline whereas the yield of propene, a rearrangement product of dimethyl carbene, falls with increasing initial concentration of oxadiazoline.</p> <p> The ester azines (R=CH3, CH2CH3 and CH(CH3)2) were found to be uniconfigurational and the E-configuration was assigned to ester azine iv and the E,E-configuration was assigned to ester azine v. Ester azines (R=C(CH3)3) were found to exist as configurational isomers. Equilibration studies were carried out on these ester azines and the thermodynamic parameters ΔG°, ΔH° and ΔS° were found for equilibration shown in eq D. (See Diagram D in Thesis)</p> <p> Changing the R' substituent of i to OCH2CCl3 or OCH2CF3 did not stop fragmentation of the derived ylide. Ester azines were found from the thermolysis of these oxadiazolines also. They were found to be uniconfigurational and were assigned the E-configuration.</p> / Thesis / Master of Science (MSc)

China has undergone significant urban growth and industrialization over the last 30 years and its incredible development continues to move ahead at an increasingly rapid pace. In terms of urban expansion, China has just recently surpassed the world’s average urbanization rate of 50%, as it moves its massive population from rural to urban areas at an astonishing speed. It’s massive population and fast urbanizing speed aside, China is also unique in terms of its socio-political system and historical-cultural context: it is a hybrid of government planning and market forces. Since it encompasses a large part of the global population and has had a vastly different urbanization experience than that of Western countries, around which most theories are based, studying China’s urbanization is an opportunity to contribute to the field of urban studies in an unprecedented manner. However, these differences also make it difficult to develop a comprehensive study of China’s urban system since the predominant theories in the field are best suited to Western cities. This research rises to this challenge by systematically studying the relationship between the socioeconomic and biophysical processes in the Chinese urban system to understand the interaction between human and physical factors, and the landscape patterns that result from these interactions. This complex urban system is examined using a hierarchical, top-down approach. At the highest level is a Macro-scale analysis of the national urban system, followed by a study of the regional urban system: the JingJinJi Metropolitan Area at the Meso-scale, and finally a Micro-scale examination with a focus on the city of Beijing. Since urban systems develop over both time and space, the urban system is analyzed spatio-temporally on all three levels. Research at the national scale is composed of two parts. First, the challenges and opportunities of China’s urban development since the foundation of the People’s Republic of China in 1949 are investigated in a general context. The institutional barriers that impede the management and continuation of China’s urban development are also discussed. Rank-size Analysis and satellite images are used to present the structural transitions of city scaling and urban clusters. These changes come with a series of challenges that are also iterated and discussed. This is followed by an analysis of the spatial distribution and transition patterns of China’s urban system using Centrographic Analysis, particularly since the post-1979 reforms. Second, the Macro-scale research focuses on a study of the urban hierarchy that is based on inter-city interactions as determined by the Synthesized Gravity Model (SGM). Under this model socioeconomic variables are synthesized and represented by the Influential Factor, while the Function Distance is derived from a Network Analysis that is based on multiple transportation methods. As an improvement on the conventional Gravity Model (GM), the SGM is used to accurately establish and represent the nodal structure of China’s urban system, the evolution of its hierarchical structure, and the relationships that exist between the nodal structure and socioeconomic factors. The results based on the SGM indicate that China’s national urban system is characterized by the emergence of urban clusters with stronger inter-city interactions since the 1990s. However, development among cities within certain urban clusters is not even, although the general pattern indicates a lessening inequality among cities. Spatially, while most cities at the top of the hierarchy are located in the east of China, cities in the middle and west of the country are also gaining higher positions in the hierarchy over time. On the Meso-scale, the applicability of the Cellular Automata (CA)-based SLEUTH model for regional urban growth pattern is studied through a focus on the JingJinJi Metropolitan Area (Beijing-Tianjin-Hebei). By integrating socioeconomic factors into a modified SLEUTH model, the urban growth dynamics and future development scenarios of the area are simulated and predicted. The results based on the CA model show that this region is characterized by a dynamic development pattern with high spreading and breeding growth rules that relies greatly on the growing transportation systems. It also allows for the projection of three possible future urban growth scenarios, each occurring under different environmental and development conditions, showing the future urban growth with or without further intervention. This research confirms that four factors play essential roles in the formulation of the urban growth mechanism of the JingJinJi Metropolitan Area: Urban policies, Industry restructuring, Rural-urban migration, and Reclassification of urban boundaries. The Micro-scale study of Beijing is conducted from two perspectives: the social and natural. The social aspect adopts the factorial ecology approach to identify the social landscape patterns and the factors that have shaped Beijing’s social space in 1990 and 2000. The social mosaic has experienced a significant change due to suburbanization, resulting in a more dynamic and complex internal structure since the 2000s. From a natural perspective, Beijing’s physical landscape patterns are extracted by processing remotely sensed images that have the same temporal span. The physical change through landscape metrics demonstrates that Beijing’s expansion has generated a more complex and fragmented land use/cover pattern. Meanwhile, transportation systems play a significant role in urban expansion, although the expansion across the space (zonal rings and directional sectors) is not even. Finally, the relationship between the social and physical landscapes is quantitatively defined by the Geographically Weighted Regression (GWR) technique, using physical landscape metrics as dependent variables and social areas as independent variables. The GWR is able to demonstrate the relationship between the social and physical landscapes at this level: as a city’s social mosaic becomes more varied over time it results in the fragmentation of that city’s physical space.

傳統上，派屈網路分類的方式是依照區域結構分成"簡單網"、"非對稱選擇網"， "擴充自由選擇網"，"自由選擇網"，"標記圖形網"，"狀態機"。最近我們將派屈網路依照全域結構的分類方式分成兩類：同步選擇網及非同步選擇網。 同步選擇網的結構不同於其它的分類方式，不但可以作派屈網的分類，而且可以因此決定網路的性質如：boundedness、liveness、reversibility等。 在一個同步選擇網中，任何一個沒有bridge的handle必定是一個TT-或PP-路徑；同步選擇網也可以分解成許多T-components或P-components；同步選擇網是非常值得研究的題目，如果一個派屈網不屬於同步選擇網，這個派屈網很可能有設計上的錯誤如unbounded或deadlock。 / Traditionally Petri nets (PN) are classified, based on local structures (input and output set of transitions or places), into simple nets, asymmetric choice nets, extended free choice nets, free choice nets, mark graphs and state machines. We categorize ordinary Petri nets into two lasses: SNC and non-SNC based on global structure. Unlike other class of Petri nets, the structure of SNC nets not only classify the nets, but also determine the properties of the nets such as boundedness, liveness, reversibility, …etc. In an SNC, any prime handle must be either a TT-or PP-path. SNC nets is declared to be largest (than Free Choice) set of nets that are covered by both T-components and P-components. SNC nets is interesting because if a designed PN is not an SNC, then most likely it suffers from design errors of deadlocks or unbounded. SNC nets is both structurally live and bounded. However, it may not be live or reversible. This thesis presents the conditions of liveness and rsibility. An algorithm is developed to detect SNC nets which based on a useful mechanism called S-Matrix to records the structure relationship between any two PSP's. Further, we will also provide algorithms to check the SNC nets to be live and irreversible.

China has undergone significant urban growth and industrialization over the last 30 years and its incredible development continues to move ahead at an increasingly rapid pace. In terms of urban expansion, China has just recently surpassed the world’s average urbanization rate of 50%, as it moves its massive population from rural to urban areas at an astonishing speed. It’s massive population and fast urbanizing speed aside, China is also unique in terms of its socio-political system and historical-cultural context: it is a hybrid of government planning and market forces. Since it encompasses a large part of the global population and has had a vastly different urbanization experience than that of Western countries, around which most theories are based, studying China’s urbanization is an opportunity to contribute to the field of urban studies in an unprecedented manner. However, these differences also make it difficult to develop a comprehensive study of China’s urban system since the predominant theories in the field are best suited to Western cities. This research rises to this challenge by systematically studying the relationship between the socioeconomic and biophysical processes in the Chinese urban system to understand the interaction between human and physical factors, and the landscape patterns that result from these interactions. This complex urban system is examined using a hierarchical, top-down approach. At the highest level is a Macro-scale analysis of the national urban system, followed by a study of the regional urban system: the JingJinJi Metropolitan Area at the Meso-scale, and finally a Micro-scale examination with a focus on the city of Beijing. Since urban systems develop over both time and space, the urban system is analyzed spatio-temporally on all three levels. Research at the national scale is composed of two parts. First, the challenges and opportunities of China’s urban development since the foundation of the People’s Republic of China in 1949 are investigated in a general context. The institutional barriers that impede the management and continuation of China’s urban development are also discussed. Rank-size Analysis and satellite images are used to present the structural transitions of city scaling and urban clusters. These changes come with a series of challenges that are also iterated and discussed. This is followed by an analysis of the spatial distribution and transition patterns of China’s urban system using Centrographic Analysis, particularly since the post-1979 reforms. Second, the Macro-scale research focuses on a study of the urban hierarchy that is based on inter-city interactions as determined by the Synthesized Gravity Model (SGM). Under this model socioeconomic variables are synthesized and represented by the Influential Factor, while the Function Distance is derived from a Network Analysis that is based on multiple transportation methods. As an improvement on the conventional Gravity Model (GM), the SGM is used to accurately establish and represent the nodal structure of China’s urban system, the evolution of its hierarchical structure, and the relationships that exist between the nodal structure and socioeconomic factors. The results based on the SGM indicate that China’s national urban system is characterized by the emergence of urban clusters with stronger inter-city interactions since the 1990s. However, development among cities within certain urban clusters is not even, although the general pattern indicates a lessening inequality among cities. Spatially, while most cities at the top of the hierarchy are located in the east of China, cities in the middle and west of the country are also gaining higher positions in the hierarchy over time. On the Meso-scale, the applicability of the Cellular Automata (CA)-based SLEUTH model for regional urban growth pattern is studied through a focus on the JingJinJi Metropolitan Area (Beijing-Tianjin-Hebei). By integrating socioeconomic factors into a modified SLEUTH model, the urban growth dynamics and future development scenarios of the area are simulated and predicted. The results based on the CA model show that this region is characterized by a dynamic development pattern with high spreading and breeding growth rules that relies greatly on the growing transportation systems. It also allows for the projection of three possible future urban growth scenarios, each occurring under different environmental and development conditions, showing the future urban growth with or without further intervention. This research confirms that four factors play essential roles in the formulation of the urban growth mechanism of the JingJinJi Metropolitan Area: Urban policies, Industry restructuring, Rural-urban migration, and Reclassification of urban boundaries. The Micro-scale study of Beijing is conducted from two perspectives: the social and natural. The social aspect adopts the factorial ecology approach to identify the social landscape patterns and the factors that have shaped Beijing’s social space in 1990 and 2000. The social mosaic has experienced a significant change due to suburbanization, resulting in a more dynamic and complex internal structure since the 2000s. From a natural perspective, Beijing’s physical landscape patterns are extracted by processing remotely sensed images that have the same temporal span. The physical change through landscape metrics demonstrates that Beijing’s expansion has generated a more complex and fragmented land use/cover pattern. Meanwhile, transportation systems play a significant role in urban expansion, although the expansion across the space (zonal rings and directional sectors) is not even. Finally, the relationship between the social and physical landscapes is quantitatively defined by the Geographically Weighted Regression (GWR) technique, using physical landscape metrics as dependent variables and social areas as independent variables. The GWR is able to demonstrate the relationship between the social and physical landscapes at this level: as a city’s social mosaic becomes more varied over time it results in the fragmentation of that city’s physical space.

Within the framework of an Institutional Partnership of the Alexander von Humboldt Foundation, the Budker Institute of Nuclear Physics Novisibirsk (BINP) and Forschungszentrum Dresden-Rossendorf worked together in a joint project devoted to the research at the coupled GDT-SHIP facility of the BINP with the focus on the study of plasma phenomena within the SHIP mirror section. The project began at July 1st, 2005 and ended on August 30th, 2008. It included work packages of significant theoretical, computational and analyzing investigations. The focus of this final report is on the presentation of results achieved whereas the work that was done is described briefly only. Chapter 2 illustrates the GDT-SHIP facility and describes shortly the planned topics of the SHIP plasma research. Chapter 3 explains the main extensions and modifications of the Integrated Transport Code System (ITCS) which were necessary for the calculations of the fast ion and neutral gas particle fields in SHIP, describes briefly the scheme of computations and presents significant results of pre-calculations from which conclusions were drawn regarding the experimental program of SHIP. In chapter 4, the theoretical and computational investigations of self-organizing processes in two-component plasmas of the GDT-SHIP device are explained and the results hitherto achieved are presented. In chapter 5, significant results of several experiments with moderate and with enhanced plasma parameters are presented and compared with computational results obtained with the ITCS. Preparing neutron measurements which are planned for neutron producing experiments with deuterium injection, Monte Carlo neutron transport calculations with the MCNP code were also carried out. The results are presented. Finally, from the results obtained within the joint research project important conclusions are drawn in chapter 6.

Recent studies have shown that even highly-proficient Spanish-English bilinguals, who acquired their second language (L2) in childhood and have little or no foreign accent in English, may require more acoustic information than monolinguals in order to identify English vowels and may have more difficulty than monolinguals in understanding speech in noise or reverberation (Mayo, Florentine, and Buus, 1997; Febo, 2003). One explanation that may account for this difference is that bilingual listeners use acoustic cues for vowel identification differently from monolinguals (Flege, 1995).In this study, we investigated this hypothesis by comparing bilingual listeners use of acoustic cues to vowel identification to that of monolinguals for six American English vowels presented under listening conditions created to manipulate the acoustic cues of vowel formant dynamics and duration. Three listener groups were tested: monolinguals, highly proficient bilinguals, and less proficient bilinguals. Stimulus creation included recording of six target vowels (/i, I, eI, E, ae, A/) in /bVd/ context, spoken in a carrier phrase by four American monolinguals (two females, two males). Six listening conditions were created: 1) whole word, 2) isolated vowel, 3) resynthesized with no change, 4) resynthesized with neutralized duration, 5) resynthesized with flattened formants, and 6) resynthesized with flattened formats and neutralized duration. The resynthesized stimuli were created using high-fidelity synthesis procedures (Straight; Kawahara, Masuda-Katsuse, and Cheveigne 1998) and digital manipulation. A six-alternative forced choice listening task was used. The main experiment was composed of 240 isolated vowel trials and 48 whole word trials.