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Front Surface Tandem Filters using Sapphire (Al2O3) Substrates for Spectral Control in thermophotovoltaic Energy Conversion Systems (open access)

Front Surface Tandem Filters using Sapphire (Al2O3) Substrates for Spectral Control in thermophotovoltaic Energy Conversion Systems

None
Date: February 28, 2005
Creator: Rahmlow, T. D., Jr.; Lazo-Wasem, J.; Gratrix, E.; Fourspring, P. & DePoy, D.
System: The UNT Digital Library
Plasma and Ion Sources in Large Area Coatings: A Review (open access)

Plasma and Ion Sources in Large Area Coatings: A Review

Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductortype large area (single wafer or batch processing with {approx} 1000 cm{sup 2}) and in-line web and glass-coating-type large area (> 10{sup 7} m{sup 2} annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.
Date: February 28, 2005
Creator: Anders, Andre
System: The UNT Digital Library
NMR Detection Using Laser-Polarized Xenon as a DipolarSensor (open access)

NMR Detection Using Laser-Polarized Xenon as a DipolarSensor

Hyperpolarized Xe-129 can be used as a sensor to indirectly detect NMR spectra of heteronuclei that are neither covalently bound nor necessarily in direct contact with the Xe atoms, but coupled through long-range intermolecular dipolar couplings. In order to reintroduce long-range dipolar couplings the sample symmetry has to be broken. This can be done either by an asymmetric sample arrangement, or by breaking the symmetry of the spin magnetization with field gradient pulses. Experiments are performed where only a small fraction of the available Xe-129 magnetization is used for each point, so that a single batch of xenon suffices for the point-by-point acquisition of a heteronuclear NMR spectrum. Examples with H-1 as analyte nucleus show that these methods have the potential to obtain spectra with a resolution that is high enough to determine homonuclear J couplings. The applicability of this technique with remote detection is discussed.
Date: February 28, 2005
Creator: Granwehr, Josef; Urban, Jeffry T.; Trabesinger, Andreas H. & Pines, Alexander
System: The UNT Digital Library
Distributed Breadth-First Search with 2-D Partitioning (open access)

Distributed Breadth-First Search with 2-D Partitioning

None
Date: February 28, 2005
Creator: Chow, Edmond; Henderson, Keith & Yoo, Andy
System: The UNT Digital Library
Anodic polymerization of vinyl ethylene carbonate in Li-Ion battery electrolyte (open access)

Anodic polymerization of vinyl ethylene carbonate in Li-Ion battery electrolyte

A study of the anodic oxidation of vinyl ethylene carbonate (VEC) was conducted with post-mortem analysis of reaction products by ATR-FTIR and gel permeation chromatography (GPC). The half-wave potential (E1/2) for oxidation of VEC is ca. 3.6 V producing a resistive film on the electrode surface. GPC analysis of the film on a gold electrode produced by anodization of a commercial Li-ion battery electrolyte containing 2 percent VEC at 4.1 V showed the presence of a high molecular weight polymer. IR analysis indicated polycarbonate with alkyl carbonate rings linked by aliphatic methylene and methyl branches.
Date: February 28, 2005
Creator: Chen, Guoying; Zhuang, Guorong V.; Richardson, Thomas J.; Gao, Liu & Ross Jr., Philip N.
System: The UNT Digital Library