Physical Sciences and Mathematics Commons^™

The Effects Of Rapid Heating And Cooling On The Composition, Structure, And Superconducting Properties Of Bi-Sr-Ca-Cu-O Compounds, Qing Duan

Dissertations and Theses

Bulk and thin film samples of Bi₂₋[subscript x]Pb[subscript x]Sr₂Ca₂Cu₃O[subscript y] compounds were prepared by suitable methods. The thin film and bulk samples were exposed to argon gas at temperatures of about 2000 °C and pressures of about 300 atm. in a ballistic compressor (BC) and then cooled at a rate of about 10⁵ °C/sec. The samples before and after this treatment were examined and compared using a transmission electron microscope (TEM), a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS) , and an x-ray diffractometer (XRD). Resistance and magnetic susceptibility measurements were made to determine changes in superconducting temperature …

Correction Of Chromatic Aberration With An Electron Mirror, Michael Stewart Mauck

Dissertations and Theses

The theoretical basis for using electron mirrors as correctors of chromatic aberration is presented and an experimental verification of correction of chromatic aberration is demonstrated. A hyperbolic electrostatic electron mirror operating in its converging range and at unity magnification was used as a corrector. A novel separating system with deflections taking place at image planes was developed to implement the mirror without impairing the resolution. Correction was demonstrated in an electron optical probe system. The chromatic aberration was measured by means of the shadows cast by a fine mesh placed near the final image. The experimental method and equipment are …

Dynamic Nmr Study Of Bond Rotational Activation Parameters In Micelles, Dietmar A. Leitner

Dissertations and Theses

The behavior of surfactants in solution has been and still is of scientific, technological, and industrial interest. The micelle forming compounds sodium N-( octyloxycarbonyl)sarcosinate (NaOcSarc), and sodium N-(decyloxycarbonyl)sarcosinate (NaDecSarc) show in aqueous solution two ¹H NMR N-methyl peaks arising from a possible cis- or trans-conformation. The relative population of the N-methyl peaks depends mostly on the concentration of surfactant indicating micelle formation. Upon heating the two peaks start to coalesce and finally appear as one single peak. The temperature range in which this phenomenon occurs is from 25°C to 65°C. The primary interest of this study was to determine …

Compiling Ace For Distributed-Memory Machines, Jun Song

Dissertations and Theses

Distributed-memory machines offer a very high level of performance, flexibility and scalability. But the memory organization of this kind of machine determines that processes on different processors must communicate explicitly by sending and receiving messages. As a result, the programmer faces the enormously difficult task of detailed planning of algorithm-irrelevant, low-level communication issues. This level of programming resembles writing assembly programs for a sequential machine.

ACE is a message-passing language with abstract communication statements. It was defined by Dr. Jingke Li at Portland State University. The communication in ACE is still explicit, but it is abstracted to a higher level. …

Binary Mixtures Near Surfaces, Patrick Dunn

Dissertations and Theses

This paper presents an approach to modeling a binary mixture near a surf ace. The approach used is based on statistical mechanics. The Cluster Variation (CV) method is used to solve an Ising-like model with a cluster size of two (neighboring lattice points). The free energy of the system is expressed in terms of the probabilities of occurrences of particular clusters. The CV method is first developed for a homogeneous system which leads to a set of three non-linear partial differential equations. The surface boundary is then introduced and the CV method is developed for this system which leads to …

Flux Trapping In Superconducting Pellets, Andreas Straub

Dissertations and Theses

This research concerns the effects on samples of nominal composition Bil.8Pb0.2Sr2Ca2cu30y which were exposed to hot, dense argon in a ballistic compressor. The investigations were concentrated on two specimens which were exposed to hot, dense argon at about 1800 K (peak pressure 330 atm) and 1500 K (peak pressure 230 atm), respectively. Sample Bi #1 showed a completely melted surface structure after triple exposure in the ballistic compressor at 1800 K while the surface of sample Bi #7 was just partly melted after double exposure at 1500 K. Changes in flux trapping capability and qualitative Meissner effect were investigated in …

Proteolytic Modification Of The Ca²-Release Mechanism Of Sarcoplasmic Reticulum In Skeletal Muscle, Ute Goerke

Dissertations and Theses

Calcium ions are important mediators in the mechanism of contraction and relaxation of muscle fibers. Depolarization of sarcolemma and transverse tubule causes an increase of myoplasmic ca2+ concentration which induces contraction of the myofibrils. In skeletal muscle fibers, the intracellular Ca²⁺ concentraton is regulated by an extensive membrane system, the sarcoplasmic reticulum (SR). Ca²⁺-release from SR is initiated by depolarization of the transverse tubule via a process referred to as excitation-contraction coupling. The Ca²⁺ - release channel located in the junctional SR plays an important role in this mechanism.

The Synthesis And Chemistry Of N-Chlorosulfenylaziridines, Michael Claude Hare

Dissertations and Theses

Thiazyl chloride, the monomer of trichlorotrithiazene, reacts with fluorinated olefins to form N-chlorosulfenylaziridines. Four members of this new class of compounds have been prepared. Fluorine NMR, carbon-13 NMR, mass spectrometry, infrared spectroscopy, and elemental analysis have been used to characterize these compounds.

Studies Of Ecological Factors That Affect The Population And Distribution Of The Western Gray Squirrel In Northcentral Oregon, Susan Ann Foster

Dissertations and Theses

The western gray squirrel (Sciurus griseus griseus Ord) occur only in the Pacific states and in a small corner of extreme western Nevada. Field studies of aspects of the ecology of the most widely distributed subspecies of western gray squirrel (S. griseus) were conducted at three sites in the ponderosa pine-Oregon white oak zone on the eastern slopes of Mt. Hood, Wasco County, Oregon, between 1981 and 1989. From 1981 through 1987, a Hunter Cooperation Program provided remains of squirrels shot during the annual late summer-early autumn hunting season. Other data were gathered through capture and release studies, radiotelemetry, and …

Theoretical And Experimental Evaluation Of Hysteresis In Atmospheric Chemistry, Theodore Alan Haigh

Dissertations and Theses

This treatise is a recapitulation of the theoretical and experimental study of hysteresis in atmospheric kinetics. The original problem arose from a theoretical study of a series of reactions for clean air. Upon evaluation a bistable equilibrium was predicted. The steady-state analysis had delineated a metastable region for the set of reactions. This bounded region is the hysteresis that this research project evaluated.

Regional Tectonic Deformation Of The Northern Oregon Coast As Recorded By Pleistocene Marine Terraces, Richard Alan Mulder

Dissertations and Theses

Pleistocene marine terraces of the northern Oregon coast are an important factor in understanding the tectonics and paleoseismicity of the central Cascadia subduction zone. The lowest marine terrace, tentatively correlated to 80,000 year old Whiskey Run terrace of southern Oregon, is intermittently exposed in the present day sea cliff along an 80 km section of coastline between Tillamook Head and Cape Kiwanda. Terrace sediments consist largely of fine material such as clay, silt and fine sand with several locations containing large amounts of gravel derived from nearby headlands and steep bedrock hills. The terrace sediments are interpreted to be deposited …

Preparation Of Electron Donor And Acceptor Molecules For Porphyrin Derivatization, Christoph Hoefler

Dissertations and Theses

Porphyrins derivatized with electron donating and electron withdrawing groups can be used for artificial photosynthesis. Four new compounds, two electron donors and two electron acceptors, have been synthesized for prospective porphyrin linkages.

Mineralogy, Geochemistry, And Dispersal Of Opaque Oxides On The Continental Shelf Of The Cascadia Margin, Kommajosyula Subramanya Ravi

Dissertations and Theses

Opaque oxide minerals (ilmenite, chromite, and magnetite) in sands from the Oregon continental shelf have been studied to establish the provenance, dispersal, and grade of potential shelf placer deposits. The study area extends southward from offshore of the Columbia River in northern Oregon to the Klamath River in northern California.

Nonlinear Dynamics In Oscillating Waterfalls, Michael Schumann

Dissertations and Theses

The concern of this thesis was to investigate the nonlinear dynamics inherent in oscillating waterfalls.

Adsorption Of Halogenated Phenolate Ions To Egg-Phosphatidylcholine Vesicles, Andreas Blochel

Dissertations and Theses

In this study, parameters for the adsorption of several halogenated phenolate ions to egg-phosphatidylcholine vesicles have been determined by microelectrophoresis.

Stratigraphy And Structure Of The Southeast Part Of The Portland Basin, Oregon, Kenneth E. Lite Jr.

Dissertations and Theses

The southeast part of the Portland Basin has been previously described by other investigators. However, little detailed information existed on the depositional relationships between the units, the various sedimentary fades, or the origin of many of the units.