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Materials Science and Engineering Faculty Research & Creative Works

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Articles 271 - 300 of 326

Full-Text Articles in Ceramic Materials

Incommensurate One-Dimensional Fluctuations In Yba2⁢Cu3⁢O6.93, Herbert A. Mook, Pengcheng Dai, Kamel Salama, Dominic Lee, Fatih Dogan, Gabriel Aeppli, Andrew T. Boothroyd, Mark E. Mostoller Jul 1996

Incommensurate One-Dimensional Fluctuations In Yba2⁢Cu3⁢O6.93, Herbert A. Mook, Pengcheng Dai, Kamel Salama, Dominic Lee, Fatih Dogan, Gabriel Aeppli, Andrew T. Boothroyd, Mark E. Mostoller

Materials Science and Engineering Faculty Research & Creative Works

A novel neutron scattering technique has been utilized to discover one-dimensional fluctuations with a very sharply defined modulation period of 16.65⁢Å along the b⁡(a) direction in YBa2⁢Cu3⁢O6.93. The fluctuations are found to be absent in the reduced oxygen compound YBa2⁢Cu3⁢O6.15. The wave vector of the fluctuations is consistent with accepted values of 2⁢kF for the Cu-O chains.


Incommensurate One-Dimensional Fluctuations In Yba2cu3o6.93, Herbert A. Mook, Pengcheng Dai, K. Salama, D. Lee, Fatih Dogan, G. Aeppli, A. T. Boothroyd, M. E. Mostoller Jul 1996

Incommensurate One-Dimensional Fluctuations In Yba2cu3o6.93, Herbert A. Mook, Pengcheng Dai, K. Salama, D. Lee, Fatih Dogan, G. Aeppli, A. T. Boothroyd, M. E. Mostoller

Materials Science and Engineering Faculty Research & Creative Works

A novel neutron scattering technique has been utilized to discover one-dimensional fluctuations with a very sharply defined modulation period of 16.65 Å along the ba direction in YBa2Cu3O6.93. The fluctuations are found to be absent in the reduced oxygen compound YBa2Cu3O6.15. The wave vector of the fluctuations is consistent with accepted values of 2kF for the Cu-O chains.


Q Dependence Of Self-Energy Effects Of The Plane Oxygen Vibration In Yba2cu3o7, D. Reznik, Bernard Keimer, Fatih Dogan, Ilhan A. Aksay Sep 1995

Q Dependence Of Self-Energy Effects Of The Plane Oxygen Vibration In Yba2cu3o7, D. Reznik, Bernard Keimer, Fatih Dogan, Ilhan A. Aksay

Materials Science and Engineering Faculty Research & Creative Works

We have measured the temperature dependence of the peak position and linewidth of the 42.5 meV phonon branch in a twinned single crystal of YBa2Cu3O7 as a function of wave vector q. In the (100)/(010) direction in the Brillouin zone, considerable softening and broadening occur below the superconducting transition temperature Tc at some values of q. We observe an order of magnitude smaller softening and no linewidth broadening for q in the (110) / (1⁢1⁢0-) direction. Possible implications of these findings for the symmetry of the superconducting order parameter are …


Phonon And Magnetic Neutron Scattering At 41 Mev In Yba2cu3o7, Hung Fai Fong, Bernard Keimer, Pw Anderson, D. Reznik, Fatih Dogan, Ilhan A. Aksay Jul 1995

Phonon And Magnetic Neutron Scattering At 41 Mev In Yba2cu3o7, Hung Fai Fong, Bernard Keimer, Pw Anderson, D. Reznik, Fatih Dogan, Ilhan A. Aksay

Materials Science and Engineering Faculty Research & Creative Works

We report inelastic neutron scattering measurements at excitation energies ħ⁢w∼41 meV in YBa2Cu3O7. We separate magnetic and phonon contributions to the scattering cross section by a detailed analysis of the momentum dependence of the scattered intensity. The previously reported broad peak around q = (π/a,π/a) in the normal state can be entirely accounted for by a phonon which primarily involves vibrations of the in-plane oxygen. Magnetic scattering centered around 41 meV and q = (π/a,π/a) appears in the superconducting state only. Theoretical implications of …


Radiolabeled Protein Composition And Method For Radiation Synovectomy, D. E. Day, Gary J. Ehrhardt, Kurt R. Zinn Apr 1995

Radiolabeled Protein Composition And Method For Radiation Synovectomy, D. E. Day, Gary J. Ehrhardt, Kurt R. Zinn

Materials Science and Engineering Faculty Research & Creative Works

A radiolabeled protein composition adapted for radiation therapy which comprises a radioisotope and a protein material containing about 6 or more percent amino acids which have a sulfhydryl-containing side chain. A method for carrying out radiation synovectomy of arthritic joints. Rhenium radiolabeled protein micro- spheres are administered which contain cysteine and other amino acids. A method for radiolabeling a protein composition whereby the composition is treated with a reducing agent capable of reducing disulfides to sulfhydryls prior to radiolabeling.


Vortex Lattice Symmetry And Electronic Structure In Yba2cu3o7, Bernhard Keimer, Wan Y. Shih, Ross W. Erwin, Jeffrey W. Lynn, Fatih Dogan, Ilhan A. Aksay Dec 1994

Vortex Lattice Symmetry And Electronic Structure In Yba2cu3o7, Bernhard Keimer, Wan Y. Shih, Ross W. Erwin, Jeffrey W. Lynn, Fatih Dogan, Ilhan A. Aksay

Materials Science and Engineering Faculty Research & Creative Works

We report a small angle neutron scattering study of the vortex lattice in YBa2Cu3O7 in magnetic fields of 0.5≤ H ≤5 T applied along and close to the c axis. Over the entire field range, the vortices form an oblique lattice with two nearly equal lattice constants and an angle of 73° between primitive vectors. Numerical calculations suggest that variations of the superconducting order parameter near the vortex core are important in stabilizing this structure. An analysis that accounts for the fourfold symmetry of the vortex core qualitatively explains both the symmetry and the orientation …


Nature Of The Ferroelectric Phase Transition In Pbtio3, Noam Sicron, B. Ravel, Y. Yacoby, Edward A. Stern, Fatih Dogan, John J. Rehr Nov 1994

Nature Of The Ferroelectric Phase Transition In Pbtio3, Noam Sicron, B. Ravel, Y. Yacoby, Edward A. Stern, Fatih Dogan, John J. Rehr

Materials Science and Engineering Faculty Research & Creative Works

We have measured quantitatively the temperature dependence of the local distortions of PbTiO3 crystals below and above the structural ferroelectric phase transition, using x-ray absorption fine-structure (XAFS) measurements. Two probe atoms, Pb and Ti, were used. The results were analyzed by fitting parametrized theoretical XAFS spectra to the experimental results. These measurements provide quantitative ‘‘distortion parameters’’ defined as the difference between the distance of the probe to its nearest neighbor measured in the actual structure and that in a centrosymmetric structure with the same unit cell dimensions. At low temperatures the Pb-edge spectra were fit using four shells and included …


Microspheres For Radiation Therapy, D. E. Day, Gary J. Ehrhardt Apr 1994

Microspheres For Radiation Therapy, D. E. Day, Gary J. Ehrhardt

Materials Science and Engineering Faculty Research & Creative Works

Microspheres for radiation therapy of a mammal which have a non-radioactive isotope which emits beta or gamma radiation of therapeutic intensity upon being irradiated. The microspheres also contain elements which do not become radioactive upon irradiation. The chemical durability of the microspheres is such that they do not release a significant amount of radiation emitting radioisotope into the mammal’s system upon administration. Microspheres containing phosphorus or yttrium; and carbon, nitrogen, fluorine, sodium, magnesium, aluminum, silicon, potassium, vanadium, manganese, gallium, niobium, iodine and/or lead.


Evaluation Of Yba,Cu,O,_, Bulk Superconductors For High Field Magnet Applications, K. Y. Blohowiak, D. F. Garrigus, T. S. Luhman, K. E. Mccrary, M. Strasik, I. A. Aksay, Fatih Dogan, W. B. Hicks, J. Liu, M. Sarikaya Mar 1993

Evaluation Of Yba,Cu,O,_, Bulk Superconductors For High Field Magnet Applications, K. Y. Blohowiak, D. F. Garrigus, T. S. Luhman, K. E. Mccrary, M. Strasik, I. A. Aksay, Fatih Dogan, W. B. Hicks, J. Liu, M. Sarikaya

Materials Science and Engineering Faculty Research & Creative Works

Processing of YBCO single crystals was carried out by solidification of semi-liquid YBCO composition using a seeding technique. Microstructural characterization of the pinning centers was investigated by transmission electron microscopy. Characterization of single crystals was carried out, relating grain size and shape to the corresponding flux profiles. Current densities were calculated based on measured trapped fields. Once circulating currents were established, flux pumping and quenching experiments were conducted. These large single crystals will be incorporated into electromagnetic forming devices for use in the military and commercial aircraft manufacturing and service industries.


Evaluation Of Yba2cu3o7-X Bulk Superconductors For High Field Magnet Applications, K. Y. Blohowiak, D. F. Garrigus, T. S. Luhman, K. E. Mccrary, M. Strasik, Ilhan A. Aksay, Fatih Dogan, W. B. Hicks, J. Liu, M. Sarikaya Mar 1993

Evaluation Of Yba2cu3o7-X Bulk Superconductors For High Field Magnet Applications, K. Y. Blohowiak, D. F. Garrigus, T. S. Luhman, K. E. Mccrary, M. Strasik, Ilhan A. Aksay, Fatih Dogan, W. B. Hicks, J. Liu, M. Sarikaya

Materials Science and Engineering Faculty Research & Creative Works

Processing of YBCO single crystals was carried out by solidification of semi-liquid YBCO composition using a seeding technique. Microstructural characterization of the pinning centers was investigated by transmission electron microscopy. Characterization of single crystals was carried out, relating grain size and shape to the corresponding flux profiles. Current densities were calculated based on measured trapped fields. Once circulating currents were established, flux pumping and quenching experiments were conducted. These large single crystals will be incorporated into electromagnetic forming devices for use in the military and commercial aircraft manufacturing and service industries.


Inclined-Field Structure, Morphology, And Pinning Of The Vortex Lattice In Microtwinned Yba2cu3o7, B. Keimer, F. Doǧan, I. A. Aksay, R. W. Erwin, J. W. Lynn, M. Sarikaya Jan 1993

Inclined-Field Structure, Morphology, And Pinning Of The Vortex Lattice In Microtwinned Yba2cu3o7, B. Keimer, F. Doǧan, I. A. Aksay, R. W. Erwin, J. W. Lynn, M. Sarikaya

Materials Science and Engineering Faculty Research & Creative Works

A detailed small-angle neutron scattering study of the vortex lattice in a single crystal of YBa2Cu3O7 was made for a field of 0.5 tesla inclined at angles between 0 and 80 degrees to the crystalline c axis. The vortex lattice is triangular for all angles, and for angles less than or equal to 70 degrees its orientation adjusts itself to maximize the pinning energy to densely and highly regularly spaced twin planes. These observations have important implications for the microscopic flux-pinning mechanism, and hence for the critical current achievable in YBa2Cu3O7. For large angles (about 80 degrees) the vortex lattice …


Tensile Fatigue Behaviour Of Tightly Woven Carbon/Carbon Composites, A. Ozturk, Robert E. Moore Jan 1992

Tensile Fatigue Behaviour Of Tightly Woven Carbon/Carbon Composites, A. Ozturk, Robert E. Moore

Materials Science and Engineering Faculty Research & Creative Works

The tensile fatigue behavior of a tightly woven carbon/carbon composite was investigated as a function of stress level. Load-controlled fatigue tests were performed in tension-tension mode with a stress ratio, R, of 0.1 under ambient laboratory conditions. Results of composite behavior are discussed in terms of the relationship of the stress/strain behavior to the fatigue life of these composites as well as the effects of applied stress levels. It is shown that these composites exhibit good resistance to cyclic loading. No fatigue failures were obtained after 106 cycles when the maximum tensile load in the fatigue cycle is less than …


Sol-Gel Derived, Air-Baked Indium And Tin Oxide Films, Douglas M. Mattox Sep 1991

Sol-Gel Derived, Air-Baked Indium And Tin Oxide Films, Douglas M. Mattox

Materials Science and Engineering Faculty Research & Creative Works

A sol-gel derived, transparent, electrically conducting tin-doped In2O3 film system has been developed which only requires air baking. The films approximate the properties of sputtered and hot-sprayed films but are simpler and less expensive to apply by dipping and spinning procedures. Substrate sodium interference was seen to be minimal. © 1991.


Composition And Method For Radiation Synovectomy Of Arthritic Joints, D. E. Day, Gary J. Ehrhardt Aug 1991

Composition And Method For Radiation Synovectomy Of Arthritic Joints, D. E. Day, Gary J. Ehrhardt

Materials Science and Engineering Faculty Research & Creative Works

A method for preparing nonradioactive microspheres adapted for radiation synovectomy of arthritic joints in a mammal involves forming the microspheres by doping a biodegradable glass material which may be lithium or potassium silicate, lithium or potassium aluminosilicate, lithium or potassium aluminoborate, lithium or potassium germanate or lithium or potassium alumino- germanate with an isotope which may be samarium, holmium, erbium, dysprosium, rhemium or yttrium so that the isotope is chemcially dissolved in and distributed uniformly throughout the glass material. The doped glass material is then treated with an acid wash to produce a thin layer on the surface thereof and …


Composition And Method For Radiation Synovectomy Of Arthritic Joints, D. E. Day, Gary J. Ehrhardt Apr 1991

Composition And Method For Radiation Synovectomy Of Arthritic Joints, D. E. Day, Gary J. Ehrhardt

Materials Science and Engineering Faculty Research & Creative Works

Radioactive microspheres for radiation synovectomy of arthritic joints in a mammal comprises a biodegradable glass material and a beta radiation emitting radioisotope chemically dissolved in and distributed substantially uniformly throughout the glass material. The biodegradable glass material may be lithium silicate, lithium aluminosilicate, lithium aluminoborate, lithium germa- nate, lithium aluminogermanate, potassium silicate, potassium aluminosilicate, potassium aluminoborate, potassium germanate or potassium aluminogermanate and the beta radiation emitting radioisotope may be samarium-153, holmium-166, erbium-169, dysprosium-165, rhenium-186, rhenium-188 or yttrium-90. Method for preparing such microspheres and for carrying out radiation synovectomy of arthritic joints utilizing such microspheres are also disclosed.


Radioactive Glass Microspheres, D. E. Day, Gary J. Ehrhardt Apr 1991

Radioactive Glass Microspheres, D. E. Day, Gary J. Ehrhardt

Materials Science and Engineering Faculty Research & Creative Works

A radioactive microsphere for radiation therapy of a mammal comprising a biologically compatible glass material containing a beta or gamma emitting radioisotope distributed substantially uniformly throughout the glass. Advantageously, the radioisotope is produced by irradiation of the microsphere.


Phase Separation In Glasses, N. J. Kreidl Mar 1991

Phase Separation In Glasses, N. J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

The detection, acceptance and further investigation of glass-glass phase separation was closely connected with the development of methods making detection possible, such as electron microscope technique pioneered and exploited by Werner Vogel, to whom this paper is dedicated on the occasion of his 65th birthday. Structures are not always found in agreement with rules derived from thermodynamic principles, and also depend on thermal history, as well as mode of preparation. The phenomenon is exemplified in many glass-forming systems. Among more recent applications are the control of crystallization by preceding phase separation as in glass-ceramics and semiconductor-doped glasses for non-linear optics. …


Recent Applications Of Glass Science, Norbert J. Kreidl Aug 1990

Recent Applications Of Glass Science, Norbert J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

Recent, often exciting, applications of glass science include solid state batteries, electronic switches and memories, electrophotography, solar cells, microspheres for optical strengthening and medical uses, novel glass ceramics such as machinable and bioactive materials, solder glasses, composites, sol-gel glasses, gradient index optics, communication fibers, sensors, non-linear and active optics, and, perhaps, digital optics. The large field of special coatings is not covered in this review. © 1990.


Composition And Method For Radiation Synovectomy Of Arthritic Joints, D. E. Day, Gary J. Ehrhardt Dec 1989

Composition And Method For Radiation Synovectomy Of Arthritic Joints, D. E. Day, Gary J. Ehrhardt

Materials Science and Engineering Faculty Research & Creative Works

Radioactive microspheres for radiation synovectomy of arithmetic joints in a mammal comprise a biodegradable glass material and a beta radiation emitting radioisotope chemically dissolved in and distributed substantially uniformly throughout the glass material. The biodegradable glass material may be lithium silicate, lithium aluminosilicate, lithium aluminoborate, lithium germa- nate, lithium aluminogermanate, potassium silicate, potassium aluminosilicate, potassium, aluminoborate, potassium germanate or potassium aluminogermanate and the beta radiation emitting radioisotope may be samarium-153, holmium-166, erbium-169, dysprosium-165, rhenium-186, rhenium-188 or yttrium-90. Methods for preparing such microspheres and for carrying out radiation synovectomy of arthritic joints utilizing such microspheres are also disclosed.


Glass Microspheres, D. E. Day, Gary J. Ehrhardt Dec 1988

Glass Microspheres, D. E. Day, Gary J. Ehrhardt

Materials Science and Engineering Faculty Research & Creative Works

A radioactive microsphere for radiation therapy of a mammal comprising a biologically compatible glass material containing a beta or gamma emitting radioisotope distributed substantially uniformly throughout the glass. Advantageously, the radioisotope is produced by irradiation of the microsphere.


Discussion Of "Lime-Enhanced Reduction Of Sulfide Concentrates: A Thermodynamic Discussion", Arthur E. Morris, Harry Flynn Dec 1986

Discussion Of "Lime-Enhanced Reduction Of Sulfide Concentrates: A Thermodynamic Discussion", Arthur E. Morris, Harry Flynn

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.


Glass Experiments In Space, Norbert J. Kreidl Jan 1986

Glass Experiments In Space, Norbert J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

Current and potential glass research under microgravity includes studies of minimum cooling rate, homogeneous nucleation, diffusion, surface tension and enrichment, fining without buoyancy, avoidance of liquid phase separation, gel synthesis, composites and uniform micro balloons. The experiments do not just anticipate space fabrication but will also provide information and innovation encouraging advanced processing on earth. © 1986.


Reply, Paul W. Angel, Chandra S. Ray, Delbert E. Day Jan 1986

Reply, Paul W. Angel, Chandra S. Ray, Delbert E. Day

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.


Preface, Delbert E. Day, Günther H. Frischat Jan 1983

Preface, Delbert E. Day, Günther H. Frischat

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.


Factors Influencing The Production Rate And Quality Of Lead Sinter, John R. Knoepke, Hung Yang Tsai, Arthur E. Morris Mar 1982

Factors Influencing The Production Rate And Quality Of Lead Sinter, John R. Knoepke, Hung Yang Tsai, Arthur E. Morris

Materials Science and Engineering Faculty Research & Creative Works

The sintering characteristics of a typical Missouri lead concentrate were determined for two types of raw sinter mix: conventionally prepared and pelletized. The important sintering characteristics are sulfur elimination, sinter strength, production rate of sinter, permeability of the sinter bed, and bed temperature. These characteristics were analyzed statistically, and are described by an empirical model, in which proportion of returns, moisture content, air flow, bed height, size distribution of returns, and ignition time are the independent variables. The characteristics of a conventionally prepared sinter mix are most strongly affected by the moisture content of the raw mix. The characteristics of …


Glass Surfaces Then And Now, Norbert J. Kreidl Jan 1982

Glass Surfaces Then And Now, Norbert J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

A reservoir of efficient instrumentation capable of detailed and quantitative exploration of glass surface features is now available in the face of the recognition of their crucial importance for both surface and bulk properties as well as performance. Yet it may be instructive to glance at what had been learned about glass surfaces by investigators before the advent of these intricate tools. Among such earlier findings are the recognition of the altered composition and structure of the surface layer, the extension of this disturbance to considerable depth, the effect of surface structure on adsorption, adhesion, wetting, finishing, etc. and on …


Conduction Polarization In Sodium Germanate Glasses, Akira Doi, D. E. Day May 1981

Conduction Polarization In Sodium Germanate Glasses, Akira Doi, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

Only one thermally stimulated depolarization current (TSDC) peak was found in germanate glasses containing from 0.19 to 32.5 mol% Na20, whereas comparable silicate glasses exhibit two such peaks. Equations are developed showing that the distortion of the equilibrium Na+-ion distribution by an applied electrical field produces a polarization in general agreement with the observed TSDC peak. It is proposed that the TSDC peak is due to dc conduction.


Discussion Of "Gas Composition, Temperature, And Pressure Measurements In A Lead Blast Furnace", Arthur E. Morris, John R. Knoepke Jun 1980

Discussion Of "Gas Composition, Temperature, And Pressure Measurements In A Lead Blast Furnace", Arthur E. Morris, John R. Knoepke

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.


The System Mgo‐Mgcl2‐H2o At 23°C, Ladawan Urwongse, Charles A. Sorrell Jan 1980

The System Mgo‐Mgcl2‐H2o At 23°C, Ladawan Urwongse, Charles A. Sorrell

Materials Science and Engineering Faculty Research & Creative Works

Solubilities of MgO in aqueous HC1 solutions at 23°±3°C were measured and combined with analyses of neat magnesium oxychloride cements, cured in sealed containers, to construct an equilibrium phase diagram for the system MgO‐MgCl2‐H2O. Specific gravities and acidities of solutions saturated with MgO and relative humidities of vapor phases over sealed samples were measured and combined with XRD data to define the compositions in equilibrium with two crystalline phases. Studies of relative reaction rates indicated that the 5–1–8 phase crystallizes more rapidly than the 3·1·8 phase and that cements near the 3·1·8 composition react rapidly with atmospheric CO …


Phase Relations In Magnesium Oxysulfate Cements, Ladawan Urwongse, Charles A. Sorrell Jan 1980

Phase Relations In Magnesium Oxysulfate Cements, Ladawan Urwongse, Charles A. Sorrell

Materials Science and Engineering Faculty Research & Creative Works

Solubilities of MgO in H2SO4 solutions were measured and X‐ray analyses of over 100 neat cement samples were used to construct an isothermal phase diagram for the system MgO‐H2SO4‐H2O at 23°±3°C. The phases MgO, Mg(OH)2, 3Mg(OH)2 MgSO4·8H2O (3·1·8), MgSO4·7H2O, MgSO4·6H2O, and MgSO4·H2O were stable at 23°C. The phases Mg(OH)2· MgSO4·5H2O (1·1·5) and MgSO4·4H2O were observed but are considered to be metastable, resulting …