Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 96 for “"field gradient"”.
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Electric Field Gradient Focusing-UV Detection for Protein Analysis
<p>Electric field gradient focusing (EFGF) utilizes a hydrodynamic flow and an electric field gradient to focus and concentrate charged analytes and order them in a separation channel according to electrophoretic mobility. Elution can be achieved by decreasing the applied voltage or increasing the …
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Pulsed field gradient magnetic resonance measurements of lithium-ion diffusion
… and the resulting macroscopic transport. Gradient nuclear magnetic resonance measurements are a mature and effective means of investigating macroscopic transport phenomena and posses several advantages over competing measures of transport in ionic solids. However, short coherence times, …
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Polymer Microchips for Capillary Electrophoresis and Electric Field Gradient Focusing of Biomolecules
… of 43,000 theoretical plates. Electric field gradient focusing (EFGF), which uses a combination of pressure-driven flow and an electric field gradient to separate charged species according to their electrophoretic mobilities, was explored for protein analysis. Capillary-based EFGF …
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Crystal structure, electron density and chemical bonding in inorganic compounds studied by the Electric Field Gradient
… about the electron density is the electric field gradient (EFG). The EFG reflects local structural symmetry properties of the charge distribution surrounding a nucleus: the EFG is nonzero if the density deviates from cubic symmetry and therefore generates an inhomogeneous electric field at …
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Microscopic diffusion measurements with nanoporous materials: complementary benefits of infrared microimaging and pulsed field gradient NMR
… namely infrared (IR) microimaging and pulsed field gradient (PFG) NMR. The dissertation contains mainly five chapters. The first chapter introduces diffusion phenomena in general and concisely explains the importance and the current challenges of the investigation of molecular diffusion in …
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The measurement of the diffusion coefficient of water in poly (ethylene oxide) water solutions using a nuclear magnetic resonance pulsed field gradient technique
… as a function of concentration using a pulsed field gradient NMR technique, for values of the concentration of poly-ox in H2O from to 1.2 gm poly-ox/gm. Near zero poly-ox concentration, the slope of the D vs. concentration curve is quite large. As the concentration increases, the slope …
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Thermometry and cooling of ultracold atoms in an optical lattice
… was then studied in the presence of a magnetic field gradient and an optical lattice. The presence of a magnetic field gradient separated the atoms into regions of opposite spin, with a boundary region of mixed spin in the center. In the presence of an optical lattice, the width of this region …
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A study of the nuclear quadrupole resonance spectrum of beryllium in chrysoberyl
… and IX to determine the matrix elements of the field gradient tensors, 1 since there are two different sites.
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Applications of Nuclear Quadrupole Double Resonance Spectroscopy
… electric quadrupole moment Q with the electric field gradient (efg) produced at the nucleus by its local electronic environment. As a result, the NQR technique provides information on the ground state charge distribution in the vicinity of the quadrupolar nucleus.
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Electrochemically generating electric field gradients in the absence of buffer for membrane-free separations
… herein focuses on modulating the electric field within microelectrochemical devices for electrokinetic separations. Specifically, two new electrochemical approaches were investigated for forming electric field gradients which are useful for manipulating ion motion. The first method involved …
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Magnetically activated and guided isotope separation
… have found applications across an array of fields including medicine, basic science, and energy. Due to substantial maintenance and operating costs, the United States decommissioned the last of its calutrons in 1998, leading to demand for alternative methods of isotope separation. Our …
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Interaction of Nanoparticles with RF, AC, and Static Magnetic Fields in Thermal and Non-Thermal Cancer Therapy Applications
… cancer cell apoptosis by external magnetic fields. Nanoparticle based target specific rf hyperthermia is explored by designing an LCR resonator. Specific Absorption Rate (SAR) of the NPs are determined to quantify rf heat enhancement due to the presence of NPs. Interaction of all field …
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A Study of Dilute Aluminum and Vanadium Nmr in Alpha-Titanium and in Hydrogen Doped Alpha-Titanium (Knight Shift, Electron Distribution, Quadrupole Interaction, Anisotropic, Alloy(hcp))
… work, experimental parameters such as electric field gradient (EFG), axial anisotropic Knight shift K(,ax), and isotropic Knight shift are obtained. In addition to shedding light on certain features of bonding of V and Al in Ti, this information is used to discuss the trapping of hydrogen in …
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A nuclear magnetic resonance study of UNI₂AL₃
… A value for the asymmetry of the electric field gradient has also been determined for this material. In addition, the temperature dependence of the Knight shift was observed over the range of 6 to 300K.No significant temperature dependence was found over this range.
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Polymer dynamics in bulk, adsorbed and solution by NMR methods
… small molecules in polymer solutions by pulsed field-gradient proton nuclear magnetic resonance (PGSE ¹H NMR). The diffusion of solvents in polymer solutions is investigated. The diffusion of N-N, dimethylformamide in polystyrene is studied as a function of concentration and temperature. The …
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The Mössbauer effect in surface studies Fe57 on Ag
… as a quadrupole split pair of lines due to a field gradient normal to the surface of about -4 x 1016 volts/cm2 e The Fe in Ag experiment gave a single narrow line shifted at room temperature (.056 + .002) cm/sec with respect to iron in iron, a temperature gradient of line position -(7.5 ± 0.5) …
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Nuclear Magnetic Resonance Studies of Electrode and Electrolyte Materials for Li-Ion Batteries
… a solid electrolyte material, through pulse field gradient NMR.</p>
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High pressure carbon-13 NMR studies of dynamics in disordered systems
… allows a direct determination of the magnetic field gradient used in NMR diffusion studies.
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Nuclear magnetic resonance in single crystals of the dilute magnetic alloys: CuFe, CuCo, and CuNi
… these nuclei, called 63 satellites, occur at fields shifted from the much more intense Cumain resonance field when observed at a fixed frequency. Satellites were observed previously in these alloys in powdered samples only. The importance of these satellite resonances lies in the information …
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The Binding Pockets of QA and QB in the Photosynthetic Reaction Center of Rba. sphaeroides Probed by Pulsed EPR
… parameters are dependent on the electric field gradient at the nucleus of interest. Using these values, the two strongly coupled nitrogen nuclei were assigned to peptide and histidine for both quinone binding sites. The quadrupole asymmetry parameter was measureable only for the QA site …
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