Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

LSU Doctoral Dissertations

Discipline
Keyword
Publication Year

Articles 1351 - 1380 of 1401

Full-Text Articles in Physical Sciences and Mathematics

Atomic And Electronic Structure Of Bulk Intermetallic And Heteroepitaxially Grown Surface Alloys, Orhan Kizilkaya Jan 2003

Atomic And Electronic Structure Of Bulk Intermetallic And Heteroepitaxially Grown Surface Alloys, Orhan Kizilkaya

LSU Doctoral Dissertations

It has been well documented that the surfaces of solids may differ from their bulk counterpart. The symmetry that a bulk possesses is broken at the surface. Due to this broken symmetry in the reduced dimension of the surface, the energetic of the surface also differs from the bulk counterpart. Reconstruction, charge redistribution, and surface alloying are phenomena that minimize the surface free energy. Surface properties of scientifically and technologically important bimetallic systems are the main focus of this dissertation. Specifically, surfaces of bulk alloy or heteroepitaxially grown metal-on-metal systems have been investigated primarily with two indispensable surface techniques, scanning …

Go to article

Diffusion Of A Rodlike Virus In Complex Solutions, Randall Charles Cush Jan 2003

Diffusion Of A Rodlike Virus In Complex Solutions, Randall Charles Cush

LSU Doctoral Dissertations

Entanglement phenomena in concentrated polymer solutions remain an interesting and challenging problem. It is still unclear how entanglement onset affects polymer chain motion at small distance scales. One way to study such motion is to follow the diffusion of a probe particle while increasing the concentration of the polymer. Many such studies have been done using probes ranging from linear and star polymers to various colloidal particles; however, relatively few studies have used rodlike probes. Rodlike probes are potentially more interesting due to the added information that may be gained by following rotational as well as translational diffusion. The anisotropic …

Go to article

Massively Parallel Molecular Dynamics Simulations Of Crack-Front Dynamics And Morphology In Amorphous Nanostructured Silica, Cindy Lynn Rountree Jan 2003

Massively Parallel Molecular Dynamics Simulations Of Crack-Front Dynamics And Morphology In Amorphous Nanostructured Silica, Cindy Lynn Rountree

LSU Doctoral Dissertations

Atomistic aspects of dynamic fracture in amorphous and nanostructured silica are herein studied via Molecular dynamics (MD) simulations, ranging from a million to 113 million atom system. The MD simulations were performed on massivelly parallel computers using highly efficient multi-resolution algorithms. Crack propagation in these systems is accompanied by nucleation and growth of nanometer scale cavities up to 20 nm ahead of the crack front. Cavities coalesce and merge with the advancing crack to cause mechanical failure. Recent AFM studies in silica glasses confirm this scenario of fracture [1]. The morphology of the fracture surfaces is studied by calculating the …

Go to article

The Extinction Properties Of Reddened Galactic Ob Sightlines, Lynne Angela Valencic Jan 2003

The Extinction Properties Of Reddened Galactic Ob Sightlines, Lynne Angela Valencic

LSU Doctoral Dissertations

A solid understanding of dust grains and their extinction properties is needed to better remove the effects of extinction from data and to comprehend the nature of the processes which modify grains. This requires a large sample of Galactic sightlines, extending far beyond the solar neighborhood, sampling not only a large volume of space but also a wide variety of environments. To fulfill this requirement, a database of sightlines toward 426 young, reddened stars was constructed using extinction curves based on IUE spectra. The curves were fit and the Fitzpatrick-Massa (FM) parameters were found. FM parameters allow for a quantitative …

Go to article

The Ecology Of Two Estuarine-Dependent Tonguefishes, The Blackcheek Tonguefish (Symphurus Plagiusa) And The Offshore Tonguefish (S. Civitatium), In Coastal Louisiana, Theodore Scott Switzer Jan 2003

The Ecology Of Two Estuarine-Dependent Tonguefishes, The Blackcheek Tonguefish (Symphurus Plagiusa) And The Offshore Tonguefish (S. Civitatium), In Coastal Louisiana, Theodore Scott Switzer

LSU Doctoral Dissertations

The pattern and process of wetland loss in coastal Louisiana has the potential to influence the distribution and abundance of fishes and macroinvertebrates that utilize inshore estuarine habitat as nurseries during their early life histories. Current management plans designed to stabilize marsh elevations, such as freshwater diversions, may also influence the distribution and abundance of estuarine-dependent nekton. Given the importance of nursery function of inshore estuaries in coastal Louisiana, it is of interest to explore the response of estuarine-dependent organisms to environmental gradients. To this end I examined the ecology of two sympatric tonguefishes, the blackcheek tonguefish (Symphurus plagiusa) and …

Go to article

On The Geometry And Topology Of Moduli Spaces Of Multi-Polygonal Linkages, Michael Edward Holcomb Jan 2003

On The Geometry And Topology Of Moduli Spaces Of Multi-Polygonal Linkages, Michael Edward Holcomb

LSU Doctoral Dissertations

The geometric, topological, and symplectic properties of moduli spaces (spaces of configurations modulo rotations and translations) of polygonal linkages have been studied by Kapovich, Millson, and Kamiyama, et. al. One can form a polygonal linkage by taking two free linkages and identifying initial and terminal vertices. This can be generalized so that one takes three free linkages and identifies initial and terminal vertices. Then one obtains a linkage which contains multiple polygons, any two of which have shared edges. The geometric and topological properties of moduli spaces of these multi-polygonal linkages are studied. These spaces turn out to be compact …

Go to article

Constraint Preserving Boundary Conditions For The Linearized Einstein Equations, Gioel Calabrese Jan 2003

Constraint Preserving Boundary Conditions For The Linearized Einstein Equations, Gioel Calabrese

LSU Doctoral Dissertations

The successful construction of long time convergent finite difference schemes approximating highly gravitating systems in general relativity remains an elusive task. The presence of constraints and the introduction of artificial time-like boundaries contribute significantly to the difficulty of this problem. Whereas in the absence of boundaries the Bianchi identities ensure that the constraints vanish during evolution provided that they are satisfied initially, this is no longer true when time-like boundaries are introduced. In this work we consider the linearization around the Minkowski space-time in Cartesian coordinates of the generalized Einstein-Christoffel system and analyze different kinds of boundary conditions that are …

Go to article

Genome Analysis: Mutation Analysis Using Near Infrared Laser-Induced Fluorescence (Nir-Lif) And Single Molecule Detection In Microfluidic Devices, Musundi Ben Wabuyele Jan 2003

Genome Analysis: Mutation Analysis Using Near Infrared Laser-Induced Fluorescence (Nir-Lif) And Single Molecule Detection In Microfluidic Devices, Musundi Ben Wabuyele

LSU Doctoral Dissertations

A number of genotyping methods have been developed for mutation analysis, each of which has its own unique advantage. DNA amplification via polymerase chain reaction (PCR) provides an unlimited supply of material for subsequent genetic analysis even in case where only a single copy of the DNA molecule is present in the sample. Research presented in this dissertation first examines the efficiency of in vitro amplification of single copy DNA with subsequent sequencing analysis of PCR product. The PCR products (amplicons) were investigated for possible alteration, distortions or mutations due to the amplification process. The sequencing data for single copy …

Go to article

Group Theoretical Approach To Pairing And Non-Linear Phenomena In Atomic Nuclei, Kristina D. Launey Jan 2003

Group Theoretical Approach To Pairing And Non-Linear Phenomena In Atomic Nuclei, Kristina D. Launey

LSU Doctoral Dissertations

The symplectic sp(4) algebra provides a natural framework for studying proton-neutron (pn) and like-nucleon pairing correlations as well as higher-J pn interactions in nuclei when protons and neutrons occupy the same shell. While these correlations manifest themselves most clearly in the binding energies of 0+ ground states, they also have a large effect on the spectra of excited isobaric analog 0+ states. With a view towards nuclear structure applications, a fermion realization of sp(4) is explored and its q-deformed extension, sp(4)q, is constructed for single and multiple shells. The su(2)(q) substructures that enter are associated with isospin symmetry and with …

Go to article

Barium And Lithium In Foraminifera: Glacial-Interglacial Changes In The North Atlantic, Jenney M. Hall Jan 2002

Barium And Lithium In Foraminifera: Glacial-Interglacial Changes In The North Atlantic, Jenney M. Hall

LSU Doctoral Dissertations

The trace element content of calcareous foraminifera provides a powerful tool to the study of glacial-interglacial changes in the physical and chemical properties of the ocean. Foraminifera incorporate barium in direct proportion to its concentration in seawater. Using barium as a nutrient proxy, Ba/Ca in benthic Planulina wuellerstorfi is used to reconstruct changes in thermocline ventilation and mid-depth circulation in the North Atlantic during the last glacial and deglacial time. Rivers are concentrated in barium compared to surface seawater. Therefore, barium in planktonic Neogloboquadrina pachyderma is used to identify deglacial meltwater in the Arctic Ocean. Foraminiferal Li/Ca was analyzed to …

Go to article

Molecular Dynamics Simulations Of Adhesion And Nanoidentation Of Gallium Arsenide, Francis Brent Neal, Jr. Jan 2002

Molecular Dynamics Simulations Of Adhesion And Nanoidentation Of Gallium Arsenide, Francis Brent Neal, Jr.

LSU Doctoral Dissertations

The purpose of this dissertation is to investigate the nanoscale hardness of gallium arsenide thin films and the elastic-plastic behavior of gallium arsenide under an indenter. These investigations were carried out using molecular dynamics (MD) simulations. The simulations are based on interatomic potentials that accurately reproduce many properties of bulk GaAs. The MD simulations performed required scalable and efficient algorithms for implementation on large parallel computers. Nanoindentation simulations were performed using an ideal indenter that was held rigid during the simulation. To reduce the transient effects due to loading, the traversal of the indenter was interrupted periodically to allow the …

Go to article

Techniques To Explore Time-Related Correlation In Large Datasets, Sumeet Dua Jan 2002

Techniques To Explore Time-Related Correlation In Large Datasets, Sumeet Dua

LSU Doctoral Dissertations

The next generation of database management and computing systems will be significantly complex with data distributed both in functionality and operation. The complexity arises, at least in part, due to data types involved and types of information request rendered by the database user. Time sequence databases are generated in many practical applications. Detecting similar sequences and subsequences within these databases is an important research area and has generated lot of interest recently. Previous studies in this area have concentrated on calculating similitude between (sub)sequences of equal sizes. The question of unequal sized (sub)sequence comparison to report similitude has been an …

Go to article

Group Automorphisms And The Decomposition Of Plancherel Measures, David Slay Jan 2002

Group Automorphisms And The Decomposition Of Plancherel Measures, David Slay

LSU Doctoral Dissertations

In this paper, a natural action of the automorphisms of a group on the space of irreducible unitary representations is used to decompose the Plancherel measure on the dual space as an integral of measures on homogeneous spaces. Explicit decompositions are obtained for the cases of free 2 and 3-step nilpotent Lie groups. These results are obtained using direct integral decompositions, induced representations, the Mackey Machine, and measure theory on homogeneous spaces.

Go to article

Nonlinear Dynamics In Nuclear Structure, Guergana Stoianova Stoitcheva Jan 2002

Nonlinear Dynamics In Nuclear Structure, Guergana Stoianova Stoitcheva

LSU Doctoral Dissertations

New collective coordinates that describe the deformation of atomic nuclei in terms of solitary waves (rotons) that are solutions of an underlying nonlinear liquid drop dynamics are introduced. The rotons, which are highly localized surface excitations, are shown to be intelligent states of an underlying angular momentum algebra, and furthermore, to adiabatically decouple from the rotational motion of the nucleus. An expansion of the roton profile in terms of surface multipoles shows that although the quadrupole mode (&lambda= 2) dominates, there are significant contributions from other even multipoles with &lambda= 4, 6, 8, etc. The picture of nuclear deformation that …

Go to article

Sediment Transport In Wind-Exposed Shallow, Vegetated Aquatic Systems, Allen Michael Teeter Jan 2002

Sediment Transport In Wind-Exposed Shallow, Vegetated Aquatic Systems, Allen Michael Teeter

LSU Doctoral Dissertations

Ecosystems with submersed vegetation are relatively shallow, physically stable and of moderate hydrodynamic energy. Submersed vegetation affect hydrodynamic friction for currents and waves resulting in increased overall frictional loss. Seagrasses shelter the sediment bed and reduce wind-wave resuspension. Bed sheltering factors were estimated from previous flume data on Laguna Madre seagrass species. Data from Laguna Madre indicate that total suspended material levels for bare areas are about an order of magnitude higher than some areas with submersed vegetation. Waves in Laguna Madre at depths less than 2 m were found to be smaller than those expected for the same non-dimensional …

Go to article

Synthesis And Study Of New Materials For The Visual Detection Of Biomolecules, Ming He Jan 2002

Synthesis And Study Of New Materials For The Visual Detection Of Biomolecules, Ming He

LSU Doctoral Dissertations

The visual determination of saccharides has been of interest for well over a century. Sugars are a relatively challenging class of compounds to analyze. They exhibit great structural similarity as well as transparency in the visible region. The sensing of specific saccharides could aid the monitoring of disease or industrial fermentation products. Herein I present new methods allowing for simple and rapid visual detection of sialic acid, fructose and a homologous series of prototypical neutral oligosaccharides, the linear maltodextrins, containing up to seven glucose residues. The new methods allow for selective color detection of fructose in a large excess of …

Go to article

Synthesis, Characterization, And Applications Of Novel Pseudostationary Phases In Micellar Capillary Electrophoresis For Separation Of Chiral And Archiral Compounds H[Electronic Resource], Cevdet Akbay Jan 2002

Synthesis, Characterization, And Applications Of Novel Pseudostationary Phases In Micellar Capillary Electrophoresis For Separation Of Chiral And Archiral Compounds H[Electronic Resource], Cevdet Akbay

LSU Doctoral Dissertations

The research presented in this dissertation involves the synthesis, characterization, and the use of novel surfactants, including both micelles and vesicles, as pseudostationary phases in micellar capillary electrophoresis (MCE) for the separation of achiral and chiral compounds. Separation of environmental pollutants such as 2 to 6-ring polycyclic aromatic hydrocarbons (PAHs) was achieved using poly(sodium undecylenic sulfate). A baseline separation of all 16 PAHs was possible for the first time in MCE by a single-surfactant system. In addition, a surfactant with a phosphated head group, i.e., di(2-ethylhexyl)phosphate (DEHP), was also introduced as a novel pseudostationary phase for separation of 21 weakly …

Go to article

Experience-Based Language Acquisition: A Computational Model Of Human Language Acquisition, Brian Edward Pangburn Jan 2002

Experience-Based Language Acquisition: A Computational Model Of Human Language Acquisition, Brian Edward Pangburn

LSU Doctoral Dissertations

Almost from the very beginning of the digital age, people have sought better ways to communicate with computers. This research investigates how computers might be enabled to understand natural language in a more humanlike way. Based, in part, on cognitive development in infants, we introduce an open computational framework for visual perception and grounded language acquisition called Experience-Based Language Acquisition (EBLA). EBLA can “watch” a series of short videos and acquire a simple language of nouns and verbs corresponding to the objects and object-object relations in those videos. Upon acquiring this protolanguage, EBLA can perform basic scene analysis to generate …

Go to article

Complexity And Heuristics In Ruled-Based Algorithmic Music Composition, Nigel Gwee Jan 2002

Complexity And Heuristics In Ruled-Based Algorithmic Music Composition, Nigel Gwee

LSU Doctoral Dissertations

Successful algorithmic music composition requires the efficient creation of works that reflect human preferences. In examining this key issue, we make two main contributions in this dissertation: analysis of the computational complexity of algorithmic music composition, and methods to produce music that approximates a commendable human effort. We use species counterpoint as our compositional model, wherein a set of stylistic and grammatical rules governs the search for suitable countermelodies to match a given melody. Our analysis of the complexity of rule-based music composition considers four different types of computational problems: decision, enumeration, number, and optimization. For restricted versions of the …

Go to article

Mixed-Symmetry Shell-Model Calculations In Nuclear Physics, Vesselin Gueorguiev Gueorguiev Jan 2002

Mixed-Symmetry Shell-Model Calculations In Nuclear Physics, Vesselin Gueorguiev Gueorguiev

LSU Doctoral Dissertations

Advances in computer technologies allow calculations in ever larger model spaces. To keep our understanding growing along with this growth in computational power, we consider a novel approach to the nuclear shell model. The one-dimensional harmonic oscillator in a box is used to introduce the concept of an oblique-basis shell-model theory. By implementing the Lanczos method for diagonalization of large matrices, and the Cholesky algorithm for solving generalized eigenvalue problems, the method is applied to nuclei. The mixed-symmetry basis combines traditional spherical shell-model states with SU(3) collective configurations. We test the validity of this mixed-symmetry scheme on 24Mg and …

Go to article

X-Ray Spectroscopy Of Geometrically Constrained Systems, Edward Earl Doomes Jan 2002

X-Ray Spectroscopy Of Geometrically Constrained Systems, Edward Earl Doomes

LSU Doctoral Dissertations

Hard X-rays (2 KeV or greater) are used as spectroscopic tools in the characterization of chemical systems. X-ray absorption near edge structure (XANES) spectroscopy is used to characterize multiple groups of chemicals in a systematic fashion. This thesis focuses on chemical systems that in some context have geometrical constraints on their structure. They include self-assembled n-alkanethiol monolayers that are tethered to silver substrates, cyclic sulfides, and (Bis(diphenylphosphino) alkane tetracarbonyl metal complexes. The study of n-alkanethiol monolayers on Ag(111) contains the first observation in the literature of an anomalous resonance in the 18 carbon monolayer. A new interpretation of a subthreshold …

Go to article

Scientific And Management Perspectives In Wetland Groundwater Hydrology, Lorna Veronica Inniss Jan 2002

Scientific And Management Perspectives In Wetland Groundwater Hydrology, Lorna Veronica Inniss

LSU Doctoral Dissertations

Wetland groundwater hydrology was investigated at different spatial scales to assess the usefulness of the information to coastal managers. Specific objectives were to: (1) review studies related to coastal groundwater discharge, evaluating techniques and identifying controls; (2) understand regional trends in groundwater flow along the U.S. East and Gulf coasts; (3) evaluate the applicability of naturally occurring radioisotopes as indicators of groundwater in a shallow deltaic system; and (4) evaluate groundwater-surface water exchange within Barataria Basin, Louisiana. Results of the review confirmed discharge estimates vary over several orders of magnitude, due to differences in precipitation and tidal prisms. In addition, …

Go to article

Fabricating Microfluidic Devices In Polymers For Bioanalytica Applications, Sean M. Ford Jan 2002

Fabricating Microfluidic Devices In Polymers For Bioanalytica Applications, Sean M. Ford

LSU Doctoral Dissertations

The research presented in this document focuses on the fabrication, characterization and application of microfluidic systems fabricated in poly(methyl methacrylate) (PMMA) with the emphasis focused on the fabrication processing steps. Microfluidic devices were produced in PMMA using X-ray lithography. The fabrication methods investigated were sacrificial mask, polyimide membrane mask and embossing techniques. PMMA microfluidic devices fabricated using X-ray lithography were characterized using scanning electron microscopy (SEM) and optical microscopy, while analytical techniques such as electroosmotic flow determination, separations, and fluorescent microscopy were used to characterize fluid transport in these devices. A novel method for the heat annealing of PMMA to …

Go to article

Precursors For Copper Chemical Vapor Deposition, Muna Bufaroosha Jan 2002

Precursors For Copper Chemical Vapor Deposition, Muna Bufaroosha

LSU Doctoral Dissertations

The main objective of this study was to synthesize precursors that are capable of producing copper films of high quality by chemical vapor deposition (CVD). We investigated some copper(I) and copper(II) complexes as precursors for chemical or photochemical vapor deposition. In chapter 2, we synthesized a series of Cu(hfac)2(amine) adducts, where hfac- is hexafluoroacetylacetonate and the amines are: dimethylamine, isopropylamine, allylamine, pyrrolidine, and piperidine. The efficiency of these adducts compared to Cu(hfac)2(H2O) as Cu-CVD precursors was examined under hydrogen. We found that among these amine adducts, Cu(hfac)2(allylamine)2 gave the best …

Go to article

Mode Specific Photoionization Dynamics In Polyatomic Molecules, Gerald Jeffery Rathbone Jan 2002

Mode Specific Photoionization Dynamics In Polyatomic Molecules, Gerald Jeffery Rathbone

LSU Doctoral Dissertations

The work presented in this dissertation presents new work on polyatomic photoionization. In these investigations, the broad range behavior of both allowed and forbidden vibrational modes in linear triatomic systems were studied to understand mode specific aspects of photoionization. The current study is made possible by the experimental strategy of exploiting high resolution photoelectron spectroscopy and the high brightness of third generation synchrotron radiation sources. The data is taken typically tens of eV’s past the ionization potential. The strategy that I employ is to probe alternative vibrational modes which are frequently affected differently following resonant ionization. Such vibrationally resolved data …

Go to article

Capillary And Microdevice Electrophoretic Tools For Genetic Analyses: Heteroduplex Analysis For Tuberculosis Drug Susceptibility And Ligase Detection Reaction For Colorectal Cancer Detection, Gloria Thomas Jan 2002

Capillary And Microdevice Electrophoretic Tools For Genetic Analyses: Heteroduplex Analysis For Tuberculosis Drug Susceptibility And Ligase Detection Reaction For Colorectal Cancer Detection, Gloria Thomas

LSU Doctoral Dissertations

The traditional format of electrophoresis, the slab gel, is quickly being replaced by capillary and microdevice platforms, which offer improvements in cost, resolution, speed, quantitation and automation in genetic analyses. These techniques also employ a variety of separation matrices while the slab gel is limited to agarose and polyacrylamide. The research presented here explores the use of these electrophoretic formats for the detection of single nucleotide mutations using two genetic models associated with human disease. Slab gel based heteroduplex analysis (HDA), a popular mutation scanning method, uses a specially designed universal heteroduplex generator (UHG) containing controlled variation to enhance the …

Go to article

A Monotone Follower Control Problem With A Nonconvex Functional And Some Related Problems, Jamiiru Luttamaguzi Jan 2002

A Monotone Follower Control Problem With A Nonconvex Functional And Some Related Problems, Jamiiru Luttamaguzi

LSU Doctoral Dissertations

A generalized one-dimensional monotone follower control problem with a nonconvex functional is considered. The controls are assumed to be nonnegative progressively measurable processes. The verification theorem for this problem is presented. A specific monotone follower control problem with a nonconvex functional is then considered in which the diffusion term is constant. The optimal control for this problem, which is explicitly given, can be viewed as tracking a standard Wiener process by a non anticipating process starting at 0. For some parameters values, the value function for this monotone follower control problem is shown to be C2 and for other …

Go to article

On The Stabilization And Regularization Of Rational Approximation Schemes For Semigroups, Simone Flory Jan 2002

On The Stabilization And Regularization Of Rational Approximation Schemes For Semigroups, Simone Flory

LSU Doctoral Dissertations

In this work we discuss consistency, stability and convergence of rational approximation methods for strongly continuous semigroups on Banach spaces. The Lax-Chernoff theorem shows that in this setting consistency and stability assumptions are necessary to obtain strong uniform convergence of approximation methods. We investigate rational approximation methods for strongly continuous semigroups and their consistency properties, with special emphasis on A-stable methods and Padé-type approximations. In particular, we discuss the stability and convergence properties of these schemes, including the stability of the well-known and widely used Backward-Euler and Crank-Nicolson Schemes. Furthermore, we modify stabilization techniques developed by Hansbo, Larsson, Luskin, Rannacher, …

Go to article

Fast Scalable Visualization Techniques For Interactive Billion-Particle Walkthrough, Xinlian Liu Jan 2002

Fast Scalable Visualization Techniques For Interactive Billion-Particle Walkthrough, Xinlian Liu

LSU Doctoral Dissertations

This research develops a comprehensive framework for interactive walkthrough involving one billion particles in an immersive virtual environment to enable interrogative visualization of large atomistic simulation data. As a mixture of scientific and engineering approaches, the framework is based on four key techniques: adaptive data compression based on space-filling curves, octree-based visibility and occlusion culling, predictive caching based on machine learning, and scalable data reduction based on parallel and distributed processing. In terms of parallel rendering, this system combines functional parallelism, data parallelism, and temporal parallelism to improve interactivity. The visualization framework will be applicable not only to material simulation, …

Go to article

Artificial Peptides Containing Ca,A- Disubstituted Amino Acids: Synthesis, Conformational Studies, And Application As Β-Strand Mimics, Yanwen Fu Jan 2002

Artificial Peptides Containing Ca,A- Disubstituted Amino Acids: Synthesis, Conformational Studies, And Application As Β-Strand Mimics, Yanwen Fu

LSU Doctoral Dissertations

Short peptides containing Cα,α-dipropylglycine (Dpg) at alternating sequence positions were synthesized and examined for conformational behavior. Peptide assembly was performed using Fmoc-solid-phase chemistry where the coupling with PyAOP could be significantly enhanced at elevated temperature. Circular dichroism (CD) and NMR conformational studies revealed that incorporation of Dpg residues induced folded structures into peptides. It was observed that Dpg residues adopted helical conformation in a helix-promoting sequence. The resulting helical structure was comprised of consecutive β-turns whose structure was stabilized by salt bridge in aqueous solution. In this study, the preparation of sterically and polyfunctional Cα,α-disubstituted amino …

Go to article

First Prev Next Last