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2009

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Articles 7441 - 7470 of 7616

Full-Text Articles in Physical Sciences and Mathematics

Historical Geography Of Yellagonga Regional Park, Western Australia, Susan Ujma Jan 2009

Historical Geography Of Yellagonga Regional Park, Western Australia, Susan Ujma

Theses : Honours

The principle aim of this study was to reconstruct the land use history of the Yellagonga Regional Park wetland landscape. Located approximately twenty kilometres north of Perth, covering about 1400 hectares, the Park lies within the North-West Corridor of the metropolitan area. This research, assisted by archival sources, demonstrates that prior to early European settlement the Yellagonga wetlands were quintessential summer hunting and gathering sites for the Nyoongar Aboriginal people. The wetlands were utilised for water, food gathering, hunting, corroborees and rituals that governed their tribal lives. Early European settlers, market gardeners, and later subdivision for urban development, have adversely …


Numerical Simulations Of The Impacts Of The Saharan Air Layer On Atlantic Tropical Cyclone Development, Donglian Sun, K. M. Lau, Menas Kafatos, Z. Boybeyi, G. Leptoukh, C. Yang, Ruixin Yang Jan 2009

Numerical Simulations Of The Impacts Of The Saharan Air Layer On Atlantic Tropical Cyclone Development, Donglian Sun, K. M. Lau, Menas Kafatos, Z. Boybeyi, G. Leptoukh, C. Yang, Ruixin Yang

Mathematics, Physics, and Computer Science Faculty Articles and Research

In this study, the role of the Saharan air layer (SAL) is investigated in the development and intensification of tropical cyclones (TCs) via modifying environmental stability and moisture, using multisensor satellite data, long-term TC track and intensity records, dust data, and numerical simulations with a state-of-the-art Weather Research and Forecasting model (WRF). The long-term relationship between dust and Atlantic TC activity shows that dust aerosols are negatively associated with hurricane activity in the Atlantic basin, especially with the major hurricanes in the western Atlantic region. Numerical simulations with the WRF for specific cases during the NASA African Monsoon Multidisciplinary Analyses …


The De Finetti Theorem For Test Spaces, Jonathan Barrett, Matthew S. Leifer Jan 2009

The De Finetti Theorem For Test Spaces, Jonathan Barrett, Matthew S. Leifer

Mathematics, Physics, and Computer Science Faculty Articles and Research

We prove a de Finetti theorem for exchangeable sequences of states on test spaces, where a test space is a generalization of the sample space of classical probability theory and the Hilbert space of quantum theory. The standard classical and quantum de Finetti theorems are obtained as special cases. By working in a test space framework, the common features that are responsible for the existence of these theorems are elucidated. In addition, the test space framework is general enough to imply a de Finetti theorem for classical processes. We conclude by discussing the ways in which our assumptions may …


A Terminological Matter: Paragenesis, Antigravitative Erosion Or Antigravitational Erosion?, Giancarlo Pasini Jan 2009

A Terminological Matter: Paragenesis, Antigravitative Erosion Or Antigravitational Erosion?, Giancarlo Pasini

International Journal of Speleology

In the speleological literature three terms are utilized to designate the “ascending erosion”: paragenesis (= paragénésis, coined in 1968), antigravitative erosion (= erosione antigravitativa, coined in 1966) and antigravitational erosion (wrong English translation of the Italian term erosione antigravitativa, utilized later on). The term paragenesis should be abandoned because of the priority of the term erosione antigravitativa - on the ground of the “law of priority” – and because of its ambiguous etimology. On the other hand, the term antigravitational erosion should be forsaken in favour of the term antigravitative erosion, given the meaning that the terms gravitation and gravity …


Lights And Shadows On The Conservation Of A Rock Art Cave: The Case Of Lascaux Cave, Fabiola Bastian, Claude Alabouvette Jan 2009

Lights And Shadows On The Conservation Of A Rock Art Cave: The Case Of Lascaux Cave, Fabiola Bastian, Claude Alabouvette

International Journal of Speleology

Lascaux Cave was discovered in 1940. Twenty years after the first microbial contamination signs appeared. In the last forty years the cave suffered different fungal invasions. Here we discuss the past, present and future of the cave and the conservation of its rock art paintings to the light of data obtained using culture-dependent and –independent methods.


Pidoplitchkoviella Terricola – An Interesting Fungus From The Domica Cave (Slovakia), Alena Nováková Jan 2009

Pidoplitchkoviella Terricola – An Interesting Fungus From The Domica Cave (Slovakia), Alena Nováková

International Journal of Speleology

The microfungus Pidoplitchkoviella terricola – until now it was known only as Kirilenko´s specimen isolated from Quercus robur rhizosphere in Ukraine - was found in earthworm casts in the Domica Cave, NP Slovak Karst, Slovakia. A description and microphotographs of this strain are provided in this article.


Microbial Communities And Associated Mineral Fabrics In Altamira Cave, Spain, Soledad Cuezva, Sergio Sanchez-Moral, Cesareo Saiz-Jimenez, Juan Carlos Cañaveras Jan 2009

Microbial Communities And Associated Mineral Fabrics In Altamira Cave, Spain, Soledad Cuezva, Sergio Sanchez-Moral, Cesareo Saiz-Jimenez, Juan Carlos Cañaveras

International Journal of Speleology

Evidences of microbial colonizations were observed in Altamira Cave, Spain. These consisted of distinct small coloured colonies, both on walls and ceiling, mainly located in the area near the cave entrance, which progressed until reaching the Polychromes Hall. The colonizations were characterized by a high morphological and microstructural variability and related to biomineralization processes. Two main types of CaCO3 deposits were related to the colonies: rosette- or nest-like aggregates of rhombohedral calcite crystals, and spheroid to hemispheroid CaCO3 elements. Colonies distribution seems to be controlled by microenvironmental conditions inside the cavity. The areas of the cave showing higher …


The Association Between Bubble Trails And Folia: A Morphological And Sedimentary Indicator Of Hypogenic Speleogenesis By Degassing, Example From Adaouste Cave (Provence, France), Philippe Audra, Ludovic Mocochain, Jean-Yves Bigot, Jean-Claude Nobécourt Jan 2009

The Association Between Bubble Trails And Folia: A Morphological And Sedimentary Indicator Of Hypogenic Speleogenesis By Degassing, Example From Adaouste Cave (Provence, France), Philippe Audra, Ludovic Mocochain, Jean-Yves Bigot, Jean-Claude Nobécourt

International Journal of Speleology

Bubble trails are subaqueous features in carbonate caves, which are made by the corrosion of ascending carbon dioxide bubbles. Folia are calcite deposits resembling inverted rimstone dams in saturated pools. Based on morphological studies in Adaouste Cave (Provence, France) and on studies elsewhere in the world, we propose a new genetic model for folia, close to the model of Green (1991). The association of bubble trails and folia, occurring on overhanging walls, is interpreted to be an indicator of hypogenic degassing occurring just below the water table. The association is the result of juxtaposed processes composed of corrosion along bubble …


Ultraviolet Radiation Sensitivity In Cave Bacteria: Evidence Of Adaptation To The Subsurface?, Jessica R. Snider, Caitlin Goin, Robert V. Miller, Penelope J. Boston, Diana E. Northup Jan 2009

Ultraviolet Radiation Sensitivity In Cave Bacteria: Evidence Of Adaptation To The Subsurface?, Jessica R. Snider, Caitlin Goin, Robert V. Miller, Penelope J. Boston, Diana E. Northup

International Journal of Speleology

We hypothesize that a reduced capacity to withstand or repair cellular damage from ultraviolet radiation may be present in cave-adapted microorganisms that never experience such conditions. However, a small number of previous studies have shown that some subsurface bacteria do not show greater sensitivity to ultraviolet radiation (UVR) than surface bacteria. To estimate UVR sensitivity in cave bacteria, bacterial isolates were collected from Carlsbad Cavern, New Mexico, U.S.A., and percent survival following exposure to various UVC and UVA radiation doses was determined. Cave bacteria from Left Hand Tunnel in Carlsbad Cavern and surface bacteria from soil and rocks above Carlsbad …


Impacts Of Alterations Of Organic Inputs On The Bacterial Community Within The Sediments Of Wind Cave, South Dakota, Usa, Marisa K. Chelius, Guy Beresford, Howard Horton, Meghan Quirk, Greg Selby, Rodney T. Simpson, Rodney Horrocks, John C. Moore Jan 2009

Impacts Of Alterations Of Organic Inputs On The Bacterial Community Within The Sediments Of Wind Cave, South Dakota, Usa, Marisa K. Chelius, Guy Beresford, Howard Horton, Meghan Quirk, Greg Selby, Rodney T. Simpson, Rodney Horrocks, John C. Moore

International Journal of Speleology

Wind Cave (WICA) in the Black Hills of South Dakota, like many mostly dry caves in temperate regions is an energy-starved system. The biotic communities that reside in these systems are low in diversity and simple in structure, and sensitive to changes in external inputs of organic matter. Caves open to tourist traffic offer an opportunity to study the impacts of organic matter amendments in the form of human and rodent hair and dander, clothing lint, material from rodent activity (nesting materials and feces), and algal growth in and around artificial lighting. This study reports on the impacts of carbon …


Cryogenic Cave Carbonates From The Cold Wind Cave, Nízke Tatry Mountains, Slovakia: Extending The Age Range Of Cryogenic Cave Carbonate Formation To The Saalian, Karel Žák, Helena Hercman, Monika Orvošová, Ivana Jačková Jan 2009

Cryogenic Cave Carbonates From The Cold Wind Cave, Nízke Tatry Mountains, Slovakia: Extending The Age Range Of Cryogenic Cave Carbonate Formation To The Saalian, Karel Žák, Helena Hercman, Monika Orvošová, Ivana Jačková

International Journal of Speleology

Cold Wind Cave, located at elevations ranging between 1,600 and 1,700 m a. s. l. in the main range of the Nízke Tatry Mountains (Slovakia), is linked in origin with the adjacent Dead Bats Cave. Together, these caves form a major cave system located within a narrow tectonic slice of Triassic sediments. Both caves have undergone complex multiphase development. A system of sub-horizontal cave levels characterized by large, tunnel-like corridors was formed during the Tertiary, when elevation differences surrounding the cave were less pronounced than today. The central part of the Nízke Tatry Mountains, together with the cave systems, was …


Guanophilic Fungi In Three Caves Of Southwestern Puerto Rico, Ángel M. Nieves-Rivera, Carlos J. Santos-Flores, Frank M. Dugan, Thomas E. Miller Jan 2009

Guanophilic Fungi In Three Caves Of Southwestern Puerto Rico, Ángel M. Nieves-Rivera, Carlos J. Santos-Flores, Frank M. Dugan, Thomas E. Miller

International Journal of Speleology

Fifty species of guanophilic (bat guano-loving) fungi were isolated from field-collected samples within three caves in southwestern Puerto Rico; most were mitosporic fungi (23 species). The caves studied were Cueva La Tuna (Cabo Rojo), Cueva de Malano (Sistema de Los Chorros, San Germán), and Cueva Viento (El Convento Cave-Spring System, Guayanilla-Peñuelas). The most conspicuous fungus by far was the zygomycete Circinella umbellata (Mucorales). Circinella umbellata dominated the bat guano incubation chambers (Petri dishes lined with sterile filter paper moistened with sterile water) at ambient laboratory conditions. Nineteen species of basidiomycetes (e.g., Ganoderma cf. resinaceum, Geastrum cf. minimum, Lepiota …


Productivity-Diversity Relationships From Chemolithoautotrophically Based Sulfidic Karst Systems, Megan L. Porter, Annette Summers Engel, Thomas C. Kane, Brian K. Kinkle Jan 2009

Productivity-Diversity Relationships From Chemolithoautotrophically Based Sulfidic Karst Systems, Megan L. Porter, Annette Summers Engel, Thomas C. Kane, Brian K. Kinkle

International Journal of Speleology

Although ecosystems thriving in the absence of photosynthetic processes are no longer considered unique phenomena, we have yet to understand how these ecosystems are energetically sustained via chemosynthesis. Ecosystem energetics were measured in microbial mats from active sulfidic caves (Movile Cave, Romania; Frasassi Caves, Italy; Lower Kane Cave, Wyoming, USA; and Cesspool Cave, Virginia, USA) using radiotracer techniques. We also estimated bacterial diversity using 16S rRNA sequences to relate the productivity measurements to the composition of the microbial communities. All of the microbial communities investigated were dominated by chemolithoautotrophic productivity, with the highest rates from Movile Cave at 281 g …


Sediment Flushing In Mystic Cave, West Virginia, Usa, In Response To The 1985 Potomac Valley Flood, James J. Van Gundy, William B. White Jan 2009

Sediment Flushing In Mystic Cave, West Virginia, Usa, In Response To The 1985 Potomac Valley Flood, James J. Van Gundy, William B. White

International Journal of Speleology

The great November 5, 1985 Potomac Valley flood was responsible for the release of 1800 m3 of alluvial and colluvial sediment from the walls of the entrance doline of Mystic Cave. Flood waters were sufficiently powerful to flush the entire mass of sediment not only into the cave but through the cave. Remnants of the sediment mass in the form of sand bars and a few cobbles wedged in speleothems were the only evidence in the cave that the huge mass of sediment had moved through. The sediment moved as a suspended mass in water moving at peak velocities …


Annual And Transient Signatures Of Gas Exchange And Transport In The Castañar De Ibor Cave (Spain), Angel Fernandez-Cortes, Sergio Sanchez-Moral, Soledad Cuezva, Juan Carlos Cañaveras, Rafael Abella Jan 2009

Annual And Transient Signatures Of Gas Exchange And Transport In The Castañar De Ibor Cave (Spain), Angel Fernandez-Cortes, Sergio Sanchez-Moral, Soledad Cuezva, Juan Carlos Cañaveras, Rafael Abella

International Journal of Speleology

The large microclimatic stability is a basic characteristic of the subterranean karst systems and causes a high sensitivity to changes in environmental conditions. High-accuracy monitoring of Castañar de Ibor cave (Spain) determined the temporal evolution of the aerodynamic processes and ventilation rate by tracking CO2 and 222Rn levels over a twelve-month period. This cave is characterized by a very stable microclimate, with high and relatively constant radon content (the mean value is 32200 Bq/m3, roughly, and the standard deviation is 7600 Bq/m3) and a moderate and quite stable CO2 concentration (the mean value is …


Dynamics And Rheology Of Biaxial Liquid Crystal Polymers, Sarthok K. Sircar Jan 2009

Dynamics And Rheology Of Biaxial Liquid Crystal Polymers, Sarthok K. Sircar

Theses and Dissertations

In this thesis we derive a hydrodynamical kinetic theory to study the orientational response of a mesoscopic system of nematic liquid crystals in the presence of an external flow field. Various problems have been attempted in this direction. First, we understand the steady-state behavior of uniaxial LCPs under an imposed elongational flow, electric and magnetic field respectively. We show that (1) the Smoluchowski equation can be cast into a generic form, (2) the external field is parallel to one of the eigenvectors of the second moment tensor, and (3) the steady state probability density function is of the Boltzmann type. …


On The Dynamics Of Quasi-Self-Matings Of Generalized Starlike Complex Quadratics And The Structure Of The Mated Julia Sets, Ross Flek Jan 2009

On The Dynamics Of Quasi-Self-Matings Of Generalized Starlike Complex Quadratics And The Structure Of The Mated Julia Sets, Ross Flek

Dissertations, Theses, and Capstone Projects

It has been shown that, in many cases, Julia sets of complex polynomials can be "glued" together to obtain a new Julia set homeomorphic to a Julia set of a rational map; the dynamics of the two polynomials are reflected in the dynamics of the mated rational map. Here, I investigate the Julia sets of self-matings of generalized starlike quadratic polynomials, which enjoy relatively simple combinatorics. The points in the Julia sets of the mated rational maps are completely classified according to their topology. The presence and location of buried points in these Julia sets are addressed. The interconnections between …


Microscopic Fungi Isolated From The Domica Cave System (Slovak Karst National Park, Slovakia). A Review, Alena Nováková Jan 2009

Microscopic Fungi Isolated From The Domica Cave System (Slovak Karst National Park, Slovakia). A Review, Alena Nováková

International Journal of Speleology

A broad spectrum, total of 195 microfungal taxa, were isolated from various cave substrates (cave air, cave sediments, bat droppings and/or guano, earthworm casts, isopods and diplopods faeces, mammalian dung, cadavers, vermiculations, insect bodies, plant material, etc.) from the cave system of the Domica Cave (Slovak Karst National Park, Slovakia) using dilution, direct and gravity settling culture plate methods and several isolation media. Penicillium glandicola, Trichoderma polysporum, Oidiodendron cerealis, Mucor spp., Talaromyces flavus and species of the genus Doratomyces were isolated frequently during our study. Estimated microfungal species diversity was compared with literature records from the same …


Export Of Terrestrial Dissolved Organic Matter Along A River To Ocean Transect Of The Lower Chesapeake Bay Investigated By Advanced Analytical Techniques, Rachel Leigh Sleighter Jan 2009

Export Of Terrestrial Dissolved Organic Matter Along A River To Ocean Transect Of The Lower Chesapeake Bay Investigated By Advanced Analytical Techniques, Rachel Leigh Sleighter

Chemistry & Biochemistry Theses & Dissertations

Ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) has proved essential for the complete separation of the thousands of peaks present in natural organic matter (NOM), a complex assemblage of organic molecules present in water, soils, and sediments. An improved understanding of its composition is crucial to understand how pollutants interact with NOM and how NOM cycles through global carbon cycles.

Optimizing the acquisition and handling of the FTICR mass spectra is the first step to obtaining high quality data. A simple method to internally calibrate the peaks in the complex spectra, using naturally present fatty …


Biogenic Tracers Through The Holocene On The Alaskan Shelf, Carie A. Curry Jan 2009

Biogenic Tracers Through The Holocene On The Alaskan Shelf, Carie A. Curry

OES Theses and Dissertations

Dramatic environmental changes in the Arctic Ocean have been observed for the last two decades including changing the amount of sea ice thickness and extent, and increased river discharge. In order to put these and other current day observations into historical context and perhaps reveal mechanisms controlling them, a suite of paleo-proxies were used to analyze two high resolution cores collected on the 2005 HOTRAX expedition. The goals of this research were: (1) develop an analytical method for determining biogenic calcite, (2) identify the major sources of biogenic matter into the system over the Holocene, and (3) assemble the history …


Ecology Of Neotropical Arboreal Snakes And Behavior Of New World Mollusk-Eating Snakes, Julie M. Ray Jan 2009

Ecology Of Neotropical Arboreal Snakes And Behavior Of New World Mollusk-Eating Snakes, Julie M. Ray

Biological Sciences Theses & Dissertations

The Neotropics is a biologically diverse region that provides man opportunities for ecological and behavioral studies. I utilized the speciose ophidian fauna of central Panama to explore the general ecology of arboreal snakes, the defensive behaviors of the snake community, and the diet of mollusk-eating snakes. I studied arboreal species to understand interspecilic relationships in several morphometric characters and to examine preferences in habitat. There were significant morphometric differences in relative length of jaw, mass, tail length, and size at midbody. The arboreal realm was partitioned among species by distance to ground, distance to water, and diameter of the perch. …


On The Dynamics Of Quasi-Self-Matings Of Generalized Starlike Complex Quadratics And The Structure Of The Mated Julia Sets, Ross Flek Jan 2009

On The Dynamics Of Quasi-Self-Matings Of Generalized Starlike Complex Quadratics And The Structure Of The Mated Julia Sets, Ross Flek

Dissertations, Theses, and Capstone Projects

It has been shown that, in many cases, Julia sets of complex polynomials can be "glued" together to obtain a new Julia set homeomorphic to a Julia set of a rational map; the dynamics of the two polynomials are reflected in the dynamics of the mated rational map. Here, I investigate the Julia sets of self-matings of generalized starlike quadratic polynomials, which enjoy relatively simple combinatorics. The points in the Julia sets of the mated rational maps are completely classified according to their topology. The presence and location of buried points in these Julia sets are addressed. The interconnections between …


Supporting Protocols For Structuring And Intelligent Information Dissemination In Vehicular Ad Hoc Networks, Filip Cuckov Jan 2009

Supporting Protocols For Structuring And Intelligent Information Dissemination In Vehicular Ad Hoc Networks, Filip Cuckov

Electrical & Computer Engineering Theses & Dissertations

The goal of this dissertation is the presentation of supporting protocols for structuring and intelligent data dissemination in vehicular ad hoc networks (VANETs). The protocols are intended to first introduce a structure in VANETs, and thus promote the spatial reuse of network resources. Segmenting a flat VANET in multiple cluster structures allows for more efficient use of the available bandwidth, which can effectively increase the capacity of the network. The cluster structures can also improve the scalability of the underlying communication protocols. The structuring and maintenance of the network introduces additional overhead. The aim is to provide a mechanism for …


A Subspace Projection Methodology For Nonlinear Manifold Based Face Recognition, Praveen Sankaran Jan 2009

A Subspace Projection Methodology For Nonlinear Manifold Based Face Recognition, Praveen Sankaran

Electrical & Computer Engineering Theses & Dissertations

A novel feature extraction method that utilizes nonlinear mapping from the original data space to the feature space is presented in this dissertation. Feature extraction methods aim to find compact representations of data that are easy to classify. Measurements with similar values are grouped to same category, while those with differing values are deemed to be of separate categories. For most practical systems, the meaningful features of a pattern class lie in a low dimensional nonlinear constraint region (manifold) within the high dimensional data space. A learning algorithm to model this nonlinear region and to project patterns to this feature …


High-Performance Broadcast And Multicast Protocols For Multi-Radio Multi-Channel Wireless Mesh Networks, Jun Wang Jan 2009

High-Performance Broadcast And Multicast Protocols For Multi-Radio Multi-Channel Wireless Mesh Networks, Jun Wang

Electrical & Computer Engineering Theses & Dissertations

Recently, wireless mesh networks (WMNs) have attracted much attention. A vast amount of unicast, multicast and broadcast protocols has been developed for WMNs or mobile ad hoc networks (MANETs). First of all, broadcast and multicast in wireless networks are fundamentally different from the way in which wired networks function due to the well-known wireless broadcast/multicast advantage. Moreover, most broadcast and multicast protocols in wireless networks assume a single-radio single-channel and single-rate network model, or a generalized physical model, which does not take into account the impact of interference. This dissertation focuses on high-performance broadcast and multicast protocols designed for multi-radio …


Interconnections Of Nonlinear Systems Driven By L₂-Itô Stochastic Processes, Luis A. Duffaut Espinosa Jan 2009

Interconnections Of Nonlinear Systems Driven By L₂-Itô Stochastic Processes, Luis A. Duffaut Espinosa

Electrical & Computer Engineering Theses & Dissertations

Fliess operators have been an object of study in connection with nonlinear systems acting on deterministic inputs since the early 1970's. They describe a broad class of nonlinear input-output maps using a type of functional series expansion, but in most applications, a system's inputs have noise components. In such circumstances, new mathematical machinery is needed to properly describe the input-output map via the Chen-Fliess algebraic formalism. In this dissertation, a class of L2-Itô stochastic processes is introduced specifically for this purpose. Then, an extension of the Fliess operator theory is presented and sufficient conditions are given under which …


Quirky, Not Quacky: Quantum Computing For Librarians, Jill Cirasella Jan 2009

Quirky, Not Quacky: Quantum Computing For Librarians, Jill Cirasella

Publications and Research

This slideshow introduces librarians and non-scientists to the relatively young field of quantum computing.


The Effect Of Dielectric Friction On The Rate Of Charge Separation In Type Ii Znse/Cds Semiconductor Nanorods, Alexander N. Tarnovsky, Nishshanka N. Hewa-Kasakarage, Patrick Z. El-Khoury, Nickolas Schmall, Maria Kirsanova, Alexander Nemchinov, Alexey Bezryadin, Mikhail Zamkov Jan 2009

The Effect Of Dielectric Friction On The Rate Of Charge Separation In Type Ii Znse/Cds Semiconductor Nanorods, Alexander N. Tarnovsky, Nishshanka N. Hewa-Kasakarage, Patrick Z. El-Khoury, Nickolas Schmall, Maria Kirsanova, Alexander Nemchinov, Alexey Bezryadin, Mikhail Zamkov

Chemistry Faculty Publications

The effect of dielectric friction on the rate of charge separation in type II ZnSe/CdS semiconductor nanorods has been investigated using picosecond transient absorption spectroscopy. The spatial separation of an excited electron-hole pair was estimated from the redshift in band edge absorption corresponding to the decrease in the exciton binding energy. The present study identifies a considerable effect of the solvent polarity on the rate of charge separation in semiconductor heterostructures, which should be taken into account when selecting nanorod caging media, such as solvents or polymer matrices. © 2009 American Institute of Physics.


Radiative Recombination Of Spatially Extended Excitons In (Znse/Cds)/Cds Heterostructured Nanorods, Nishshanka N. Hewa-Kasakarage, Maria Kirsanova, Alexander Nemchinov, Nickolas Schmall, Patrick Z. El-Khoury, Alexander N. Tarnovsky, Mikhail Zamkov Jan 2009

Radiative Recombination Of Spatially Extended Excitons In (Znse/Cds)/Cds Heterostructured Nanorods, Nishshanka N. Hewa-Kasakarage, Maria Kirsanova, Alexander Nemchinov, Nickolas Schmall, Patrick Z. El-Khoury, Alexander N. Tarnovsky, Mikhail Zamkov

Chemistry Faculty Publications

We report on organometallic synthesis of luminescent (ZnSe/CdS)/CdS semiconductor heterostructured nanorods (hetero-NRs) that produce an efficient spatial separation of carriers along the main axis of the structure (type II carrier localization). Nanorods were fabricated using a seeded-type approach by nucleating the growth of 20-100 nm CdS extensions at [000 +/- 1] facets of wurtzite ZnSe/CdS core/shell nanocrystals. The difference in growth rates of CdS in each of the two directions ensures that the position of ZnSe/CdS seeds in the final structure is offset from the center of hetero-NRs, resulting in a spatially asymmetric distribution of carrier wave functions along the …


Structural Studies Of Biopolymers Using Computer Simulations, Optical And Magnetic Spectroscopy, Subhasish Chatterjee Jan 2009

Structural Studies Of Biopolymers Using Computer Simulations, Optical And Magnetic Spectroscopy, Subhasish Chatterjee

Dissertations, Theses, and Capstone Projects

Biopolymers are essential components of numerous natural and synthetic macromolecular assemblies. In the present study, the structural properties of biopolymers ranging from fungal melanins to synthetic nucleic acids were investigated using spectroscopic methods and theoretical modeling. (1) Computational modeling and molecular dynamics simulations were used to study the structural properties of a short single-stranded (ss) DNA. The dependence of the conformational stability and flexibility of the ssDNA on the thermodynamic conditions of the system was demonstrated. (2) Time-resolved fluorescence spectroscopy involving an organic donor-quencher pair was utilized to study the conformational properties of Y-shaped DNA. Results highlighted the different distances …