Bituminous materials, pavement design, and composite materials.
Bituminous or asphaltic materials are the most widely used materials in highway and airfield pavements. Dr. Bell's recent research has included investigation of effects of moisture and aging on the properties of aspha lt mixtures, and the relationship of asphalt composition to the performance of asphalt pavements.
Field Validation of Aging Procedures for Asphalt-Aggregate Mixtures, C.A. Bell, J.J. Fellin, and A.J. Wieder, Journal of Association of Asphalt Paving Technologists, Vol. 63, 1994, pp. 45-80.
Evaluation of Asphalt-Aggregate Mixture Aging by Dynamic Mechanical Analysis, Y. Ab-Wahab, D. Sosnovske, C.A. Bell, and P. Ryus. Transportation Research Board, 1993.
The Role of Asphalt and Aggregate in the Aging of Bituminous Mixtures, D. Sosnovske, Y. Ab-Wahab and C.A. Bell. Transportation Research Board, 1993.
Aging of Asphalt-Aggregate Mixtures, C.A. Bell, Y. Ab-Wahab, J.E. Kliewer, D. Sosnovske and A. Weider. Proceedings, 7th International Conference on the Structural Design of Asphalt Pavements, Vol. 2, Nottingham, U.K., August 16-20, 1992.
Pavement Design and Materials, Past, Present and Future, J.P. Mahoney and C.A. Bell. Moderators Report, Proceedings, 7th International Conference on the Structural Design of Asphalt Pavements, Vol. 5, Nottingham, U.K., August 16-20, 1992.
Construction materials; asphalt, cements, aggregates and portland cements.
The stress-strain behavior of construction materials is extremely important if pavement deterioration is to be slowed. Tests performed on these modulus include modulus and fatigue tests, tensile strength creep behavio r, water susceptibility tests, compressive strength and facture properties. The testing procedures require electrohydraulic test systems and accurate response (deflection, strain) measuring systems.
Open-Graded Emulsion Mixtures: 25 Years of Experience, (with E. Richardson, I.J. Huddleston, and N. Jackson). Prepared for 6th International Conference on Low Volume Roads, Transportation Research Board, March 1994.
Evaluation of Rutting Potential of Oregon Mixes, (with D. Sosnovske and R. Leahy). AAPT Journal, March 1994.
Mezclas aburtas en frio: 25 aĖos de experiencia, Carreteros, pp. 76-84, March-April 1994. SHRP Binder Rheology Tests and Mixture Properties, (with I.L. Jamieson and R.B. Leahy). Prepared for Symposium on Fundamental Properties of Bituminous Materials, Institute of Asphalt Technology, October 1994.
Framework for Performance-Based Approach to Mix Design and Analysis, (With R.B. Leahy, C.L. Monismith, and F. Finn). Prepared for the Annual Meeting of AAPT, December 1994.
Performance-Related Testing of Stone Mastic Asphalt, (With M.N. Partl, T.S. Vinson, and K. Younger). Prepared for the Annual Meeting of AAPT, December 1994.
SHRP Performance-Based Binder Specifications and Mixture Properties, (With I.L. Jamieson, R.B. Leahy, and C.L. Monismith). Journal Eurobitume, December 1994.
Chemical reaction engineering, high temperature materials.
Dr. Kimura’s interests include applications of fluidization technologies to mass production of high temperature materials. He built a high temperature fluidized-bed reactor system that can be operated at temperatures up to 1500 deg. C. His research group has successfully produced silicon nitride in the fluidized-bed reactor, operated at temperatures in the range of 1200-1400 deg. C. The fluidized-bed process has proven to be the most innovative method that can reduce the production cost of this material to at least one-third of the current cost. His research group is now challenging fine powder fluidization, which will enable a further cost reduction of silicon nitride. He is al so looking into the possiblity of developing a continuous fluidized-bed process for the production of nanophase silicon nitrdie and silicon carbide. Dr. Kimura’s research activities also include the fluidized-bed nitridation of metal powders which can be consolidated into high, uniform nitrogen concentration solid compacts. It has been found that the concentration of nitrogen in stainless steel powd ers can be controlled in the range of 0.1-10% in mass. Dr. Kimura has devoted himself to research to gain an insight into the intrinsic kinetics and mechanisms of gas-solid reactions, which are essential for the optimum design of fluidized-bed reactors.
Mechanism of Nitridation of Silicon Powder in a Fluidized-Bed Reactor, (with J. Koike). Accepted by J. Am. Ceram. Soc.
Use fo Two-Phase Standards of Unknown Composition to Determine Calibration Constants for Powder XRD by Linear Regression, (with Z. Jovanovic). J. Am. Ceram. Soc. 77, 2226 (1994).
Effects of Hydrogen and Temperature on the Kinetics of FLuidized-Bed Nitridation of Silicon, (With Z. Jovanovic and O. Levenspiel). J. Am. Ceram. Soc. 77, 186 (1994).
Particulate Reaction Engineering, (with L.S. Fan, J. Rathman, A.G. Dastidor, and A.W. Weimer). Chem. Eng. Prog. 90(4), 55 (1994).
Fluidization and Entrainment of Difficult-to-Fluidize Fine Powder Mixed with Easy-to-Fluidize Large Particles, (with Y.D. Liu). Powder Technology 75, 189 (1993).
Vibrating Beds of Fine Particles—Estimation of Interparticle Forces from Expansion and Pressure Drop Experiments, (with E. Jareiz and O. Levenspiel). Powder Technology 72, 23 (1992).
Chemical vapor deposition, plasma etching, plasma-enhanced chemical vapor deposition.
Primary interests focus on thin film materials processing. Chemical enginineering sciences such as transport, reaction kinetics and thermodynamics are applied to the deposition, etching and modification of thin films. Current projects include (1) halide-transport chemical vapor deposition (HTCVD) and atomic layer epitaxy (ALE) of electroluminescent (EL) phosphors for flat panel display applications, (2) netural chemistry and ion bombardment in glow discharge plasma etching and deposition of dieletrics, and (3) corrosion and cathodic protection in reinforced concrete bridges.
A Simple Model for the Etching of Photoresist with Plasma-Generated Reactants, M.D. Koretsky and J.A. Reimer, J. Appl. Phys. 72, 5081 (1992).
Anomalous Etch Rates of Photoresist with Argon Dilution of CF4/O2 Plasma Afterglows, M.D. Koretsky and J.A. Reimer, Appl. Phys. Lett. 59, 1547 (1991).
Evaluation of the Performance of Reference Electrodes Embedded in Reinforced Concrete, M.D. Koretsky, F. Abooameri and J.C. Westall, FHWA Report #SP&R 5294 (1995).
electronic structure in highly correlated solids.
Dr. Loeser's research is aimed at the development of new techniques for treating electronic structure in highly correlated solids. The methods are based on a family of model hamiltonians (called subhamiltonians) in w hich particles are assigned auxiliary degrees of freedom. These extra coordinates simulate quantal effects within a pseudo-classical model of partioned point charges. Subhamiltonian methods are parameter-free, and very simple from a computational standp oint. First-row transition metal oxides are being utilized to test the algorithms. Reasonable estimates for Coulomb penalties, charge transfer energies, and hopping integrals are obtained for these materials. Particularly important is the fact that the re is no systematic bias against the ionic contributor states, because dynamic correlation, polarization, and relaxation effects are all modeled reasonably well. Finite cluster calculations are planned in order to study charge carrier motions and interac tions in these and other highly correlated solids.
Correlated electronic structure models suggested by the large-dimension limit, J. G. Loeser, J. H. Summerfield, A. L. Tan, and Z. Zheng. J. Chem. Phys. 100, 5036-5053 (1994).
Scaling and interpolation for dimensionally generalized electronic structure, M. Lopez-Cabrera, A. L. Tan, and J. G. Loeser. J. Phys. Chem. 97, 2467-2478 (1993).
Large-D limit for metallic hydrogen. J. G. Loeser. In Dimensional Scaling in Chemical Physics, ), pp. 389-427, D. R. Herschbach, J. Avery, and O. Goscinski (Eds.), Kluwer, Dordrecht Netherlands (1993).
Opto-electronic materials and devices; design and fabrication of diode lasers, and photodetectors, picosecond semiconductor components.
Optical electronics is a rapidly growing field. The high speed, low noise capabilities of optoelectronic devices make them particularly attractive for very high speed communications, signal processing and sensing appl ications. Current research is directed toward developing new diode lasers in the visible and near IR wavelength regions using "molecularly engineered" MBE materials. Limiting mechanisms to device speed are being investigated as are other materials and typ es of detectors. Infrared photodetectors for the 8-12mm region are important for night vision applications. HgCdTe photoconductive detectors are also being studied to understand and improve their performance.
MBE HEMT-Compatible Diode Lasers, (with J. Ebner, J.E. Lary and G.W. Eliason). ESSDERC 90, 20th European Solid State Device Research Conf., Nottingham, England, 10-13 Sept. 1990, pp. 401-404.
Strained Layer In GaAs GRIN-SCH Lasers Grown by MBE, (with J.T. Ebner and J.R. Arthur). Proc. of Quantum Wells for Optics and Optoelectronics Topical Meeting, Salt Lake City, Utah, March 1989.
Undoped and Chromium-Doped Semi-Insulating GaAs Photoconductive Detectors, (with G. Schumm). Sol.St. Elect., 30:109-112 (1987).
InP/InGaAs Double Heterostructure Bipolar Transistors Grown by MBE, (with P. Schuitemaker, P.A. Claxton, J.S. Roberts and P. Houston). Electr. Lett., 15:781-783 (1986).
The Origin of a Hole-like Capacitance DLTS peak in Ion-Implanted GaAs, F.H. Yang, S.J.T. Owen and T.K. Plant. (1984) In Semi-Insul. III-V Materials Conference, Kah-Nee-Ta, OR, pp. 470-474 (D.C. Look and J.S. Blakemore, eds.); Shiva Publishing, Nantwich, U K.
Epitaxial growth and characterization of semiconductor materials, processing, characterization, modeling and radiation reliability of semiconductor devices.
Current research projects: Radiation physics and reliability issues in nanoscale III-V heterostructure devices (funded by the Air Force Office of Scientific Research); Spice models for SiGe Heterojunction Bipolar Transistors; Characterization of Si wafers (funded by Mitsubishi Silicon America).
A. Bandyopadhyay, S. Subramanian, S. Chandrasekhar, A.G. Dentai and S.M. Goodnick, "Degradation of DC Characteristics of InGaAs/InP Single Heterojunction Bipolar Transistors Under Electron Irradiation," IEEE Trans. Electron Devices 46 (5), 840-849 (1999).
A. Bandyopadhyay, S. Subramanian, S. Chandrasekhar, A.G. Dentai and S.M. Goodnick, "Degradation of InGaAs/InP Double Heterojunction Bipolar Transistors Under Electron Irradiation," IEEE Trans. Electron Devices 46 (5), 850-858 (1999).
A. Shatalov, S. Subramanian, S. Chandrasekhar, A.G. Dentai and S.M. Goodnick, "Electron Irradiation Effects in Polyimide passivated InGaAs/InP Single Heterojunction Bipolar Transistors, accepted for presentation in IEEE Nuclear and Space Radiation Effects Conference, Norfolk, Virginia, July 1999.
A. Bandyopadhyay, S. Subramanian, S. Chandrasekhar and S.M. Goodnick, "Degradation of InGaAs/InP Heterojunction Bipolar Transistors Under High energy electron Irradiation," 1998 IEEE International Reliability Physics Symposium Proceedings, IEEE Catalog No. 98CH36173, pp. 98–102.
D.W. Schulte, S. Subrmanian, L. Ungier, H.M. Yoo, U. Venkateswaran and J.R. Arthur, "Substrate orientation dependence of carbon doping of GaAs using CBr4 source in molecular beam epitaxy," J. Vac. Sci. Technol. B 16 (3), 1356-1360 (1998).
S. Subramanian, A. Sarkar, L. Ungier and S.M. Goodnick, "Integrity of III-V Heterojunction Devices Under Gamma Irradiation," IEEE Tans. Nucl. Sci. .44, 1862 (1997).
S. Sinha, B.M. Arora, S. Subramanian, D. Schulte, and L. Ungier, "Photoreflectance and photoluminescence spectroscopy of low temperature GaAs grown by Molecular Beam epitaxy," J. Appl. Phys. 79, 427 (1996).
S. Subramanian, D. Schulte, L. Ungier, P. Zhao, T.K. Plant, and J.R. Arthur, "A high gain, modulation-doped 1.3 mm photodetector using low-temperature MBE-grown GaAs," Electron Device Lett. 16 (1), 20 (1995).
D. Schulte, S. Subramanian, L. Ungier, K. Bhattacharyya, and J.R. Arthur, "Mobility of two-dimensional electron gas on low-temperature MBE-grown GaAs," J. Electron. Mater. 24, 359 (1995).
D. Schulte, S. Subramanian, L. Ungier, and J.R. Arthur, "Photoluminescence from modulation doped AlGaAs/low-temperature-MBE-grown-GaAs heterostructures," J. Appl. Phys. 78, 1210 (1995).
Microwave circuits and devices, computational electromagnetics and solid-state devices.
Professor Tripathi's current research activities deal primarily with the development of analytical, numerical and experimental techniques to characterize various circuit elements in hybrid and monolithic microwave circ uits and high frequency interconnects and electronic packages. Active projects include the development of CAD tools for the design of microwave components and circuits; the study of coupled active and nonlinear distributed parameter systems for applicatio ns in MMIC's and optical devices, modeling and design of interconnections in high speed digital circuits including VLSI's and novel solid state devices.
Optoelectronics: Technology and Applications, co-editor with K. Shenai and A. Selvarajan. SPIE Press Book, 1993, pp. 332.
Equivalent Circuit Modelling of Interconnects from Time Domain Measurements, (with J. Jong and B. Janko). IEEE Trans. Components Hybrids and Manuf. Technology, pp. 119-126, February 1993.
Calibration Methods for Time Domain Network Analysis, L. Hayden and V.K. Tripathi. IEEE Trans. Microwave Theory and Techniques, pp. 415-420, March 1993.
An Extended Matrix Method for Nonlinear Directional Couplers, (with H.S. Chang). Optical Engineering, pp. 735-738, April 1993.
Modal Analysis of Discontinuities in Diffused Optical Waveguides, (with A. Weisshaar). IEEE Trans. Light Wave Technology, pp. 593-602, May 1992.
Application of Generalized Inverses to Efficient Computation of MIMIC Structures, (with M.A. Thorburn). Intl. Jour. of Microwave and Millimeter Wave Computer-Aided Engineering, pp. 248-252, October 1992.
Time Domain Characterization and Analysis of Dispersive Dissipative Interconnects, (with N. Orhanovic). IEEE Trans. Circuits and Systems, November 1992.
Theory and noninvasive investigation of defect dynamics in semiconductor materials. Materials science theory of electronic materials, and of concrete development of solar energy.
Material science of electronic materials, particularly of semiconductors. Relation of thermochemical history of sample to its electronic and optical properties. Defect concentration. Defect migration and interactive crystal growth of semiconductors, Monte Carlo simulation of these processes on microcomputers. Cathodic protection of steel reinforced concrete with solar energy.
Defeating Compensation in Wide Gap Semiconductors by Growing in H that is Removed by Low Temperature De-Ionizing Radiation, J.A. Van Vechten, J.D. Zook, R.D. Horning and B. Goldenberg. Jpn. J. Appl. Phys. Vol. 31, pp. 3662-3662 (1992).
The Effect of Vacancies Grown into Silicon on Gold Diffusion, R.K. Graupner, J.A. Van Vechten, P. Harwood and T.K. Monson. Mat. Res. Soc. Symp. Proc. Vol. 262, pp. 537-542 (1992).
Characterization of point defect generation at silicon surfaces using gold diffusion, R.K. Graupner, J.A. Van Vechten and P. Harwood. J. Vac. Sci. Technol. B 10(4), July/August 1992, pp. 1852-1855.
Surface Treatment Effects on Atomic Diffusion in S: Explained Without Self Interstitials, J.A. Van Vechten, U. Schmid and Q.S. Zhang. J. Elec. Matrl., 20:431 (1991).
Vidsim - A Monte Carlo Program for the simulation of Atomic Diffusion in Diamond and Zinc-Blende Structures, U. Schmid, N.C. Myen and J.A. Van Vechten. Computer Physics Commun. 58:329 (1990).
Atomic Diffusion with Strain and Injection, J.A. Van Vechten. Mat. Res. Soc. Symp. Proc., 184:165 (1990).
Vacancy First and Second Neighbor hopping at a Compound Semiconductor Interface -- Insights from Computer Simulation, J.A. Van Vechten and U. Schmid. J. Vac. Sci. Technol. B7:827 (1989).
Mössbauer Spectra and the DX-Contre Complex in AlGaAs, J.A. Van Vechten. J. Phys. Condens. Matter 1:5171 (1989).
Resolving Defect Mega-Controversy by Giga-Event Monte Carlo Simulation of the Macro-Consequences of Atom-level Assumptions on Micro-computers at Nano-Cost, J.A. Van Vechten, U. Schmid and N.C. Meyers. (A Plenary invited talk at the Int. Conf. on Science a nd Technol. of Defect Control on Semiconductors) Jpn. J. Anal. Phys. (1989).
Modeling of Luminescence Phase Delay for Non-destructive characterization of Si Wafers, D. Guidotti, J.S. Batchelder, A. Finkel, P.D. Gerber and J.A. Van Vechten. J. Appl. Physics 66:2542 (1989).
A Simple Man's View of the Passivation of Semiconductors, J.A. Van Vechten. (A plenary invited talk at the 6th int. Symposium on Passivity) Solid State Electronics Suppl. (1989).
Flat-panel electroluminescent displays; fabrication, characterization, and modeling of electronic materials and devices.
Current research involves the fabrication, characterization and modeling of ac thin film electroluminescent display devices.
Evidence for Band-to-Band Impact Ionization in Evaporated ZnS:Mn Alternating-Current Thin-Film Electroluminescent Devices,” W.M. Ang, S. Pennathur, L. Pham, J.F. Wager, S.M. Goodnick, and A.A. Douglas. J. Appl. Phys. 77, 2719 (1995).
Electrical Characterization of Blue Electroluminescent Devices, L.V. Pham, J.F. Wager, S.S. Sun, E. Dickey, R.T. Tuenge, and C.N. King. In: Advanced Flat Panel Display Technologies, edited by P.S. Friedman. SPIE Proceedings 2174, 190-199 (1994).
Alternating-Current Thin-Film Electroluminescent Devices with Multiple Dielectric Layers, J.H. Ruy, S. Lim, and J.F. Wager. Thin Solid Films 248, 63-68 (1994).
Aging Studies of Atomic Layer Epitaxy ZnS:Mn Alternating-Current Thin-Film Electroluminescent Devices, A. Abu-Dayah and J.F. Wager, J. Appl. Phys. 75, 3593-3598 (1994).
Rugate Filters Grown by Plasma-Enhanced Chemical Vapor Deposition, S. Lim, J.H. Ryu, J.F. Wager, and T.K. Plant. Thin Solid Films 245, 141-145 (1994).
Evidence for Space Charge in Atomic Layer Epitaxy ZnS:Mn Alternating-Current Thin-Film Electroluminescent Devices, A.A. Douglas, J.F. Wager, D.C. Morton, J.B. Koh, and C.P. Hogh. J. Appl. Phys. 73, 296-299 (1993).
Monte Carlo Simulation of Electron Transport in Alternating-Current Thin-Film Electroluminescent Devices, K. Bhattacharyya, S.M. Goodnick, and J.F. Wager. J. Appl. Phys. 73, 3390-3395 (1993).
Thermodynamics and Kinetics of Vacancy Self-Compensation in Wide Band Gap Semiconductors, J.F. Wager. Phil. Mag. A 67, 897-904 (1993).
Aging Studies of ZnS:Mn Alternating-Current Thin-Film Electroluminescent Devices, J.D. Davidson, J.F. Wager, and S. Kobayashi. J. Appl. Phys. 74, 5575-5581 (1993).
Hot Electron Luminescence in ZnS:Mn Alternating-Current Thin-Film Electroluminescent Devices, A.A. Douglas, J.F. Wager, D.C. Morton, J.B. Koh, and C.P. Hogh. Appl. Phys. Lett. 63, 231-233 (1993).
Internal Charge-Phosphor Field Characteristics of Alternating-Current Thin-Film Electroluminescent Devices, A. Abu-Dayah, S. Kobayashi, and J.F. Wager. Appl. Phys. Lett. 62, 744-746 (1993).
Current research includes bulk metallic glasses, thermodynamics and kinetics of metastable phase formation, composites, interface reactions, nucleation and phase separation.
Metal plasticity, solid-state joining, phase diagrams.
The plasticity research has recently emphasized investigating the details of the microstructural evolution in metals and alloys deformed to ultra-large strains at higher temperatures. This work is providing new insigh ts into the basic mechanisms of high temperature plasticity as well as establishing methods to produce materials with new and useful microstructures. The solid-state joining research is currently determining the mechanism of various stress-states. The p hase diagram work emphasized assessment of existing diagrams, thermodynamic analysis of phase equiibria and the construction of new diagrams.
Some Observations During In-situ Reversed Deformation Experiments of Aluminum Single Crystals Using the X-Y Method, M.E. Kassner, M.A. Wall and A.W. Sleeswyk. Scripta Met. et Mater., 25:1701 (1991)
On the Nucleation and Growth of Cavities in Constrained Silver, M.E. Kassner, M.C. Tolle, G.A. Henshall, R.S. Rosen and J.W. Elmer. Metall. Trans. 24A, 1993, p. 1877.
The Role of Low Angle (Subgrain Boundary) and High Angle (Grain Boundary) Interfaces on 5- and 3-Power Law Creep, M.E. Kassner. Mater. Sci. and Eng. 166, 1993 pp. 81-88.
The Effect of Primary Alpha, Nickel and Chromium on the Creep Properties of Ti 6242, K.E. Thiehsen, M.E. Kassner, J. Pollud, D.R. Hiatt and B. Bristow. Metall. Trans. 24A, 1993 pp. 1819-1826.
Dynamic Restoration Mechanism in Al-5.8 at % Mg Deformed to Large Strains in the Solute Drag Regime, G.A. Henshall, M.E. Kassner and H.J. McQueen. Metall. Trans. 23A, 1992, pp. 881-889.
Mechanics of solids, composite materials, fracture, finite-element analysis.
The mechanical properties of composite materials are strongly dependent on their internal structure; i.e. the geometric and strength properties of the reinforcing particles or fibers. The objective of this research is to develop theoretical models that incorporate the effects of constituent properties and can be used for predicting the stiffness and fracture strength of composite materials. The development of these models will serve as a guide to the optimization of the composite material's microstructure for a specified structural task.
R. Nuzzo, C. Duke, K. Chaffee, M. Kassner, and R. Pitts, The Impact of Surface Processing on the Fabrication and Performance of Thin-Film, Multiplayer Solar Collectors. Critical Rev. in Surface Chemistry 3, 67-80 (1993).
R.S. Rosen, D.G. Stearns, M.A. Viliardos, M.E. Kassner, S.P. Vernon, and Y. Cheng, Silicide Layer Growth Rates in Mo/Si Multilayers. Appl. Optics 32, 6975-6980 (1993).
M.E. Kassner, J. Pollard, E. Evangelista, and E. Cerri, Restoration Mechanisms in Larege-Strain Deformation of High Purity Aluminum at Ambient-Temeprature, and the Determination of the Existence of “Steady State.” Acta Metall. Mater. 42, 3223-3230 (1994) .
M.A. Delos-Reyes and M.E. Kassner, Reproducibility of Small-Strain Creep Tests of Ti 6242. J. Mater. Eng. and Perf. 3, 722-725 (1994).
M.E. Kassner, The Nb-Th (Niobium-Thorium) System. J. Phase Equiquilibria 15, 561-563 (1994).
M.C. Tolle and M.E. Kassner, Mechanisms of Ductile Fracture in Pure Silver uner High-Triaxial Stress States. Acta Metall. et Mater. 43, 287-297 (1995).
M.C. Tolle, M.E. Kassner, E. Cerri, and R.S. Rosen, Mechanical Behavior and Microstructure of Au-Ni Brazes. Metall. and Mater. Trans. 26A, 941-948 (1995).
Applied superconductivity, cryogenic materials, electrical, magnetic, thermal and mechanical properties measurements.
Improvement of the critical properties of superconductors for technological applications requires a broad understanding of the relationship between the micro-structure and the critical properties. Of particular intere st for applications involving superconductors carrying large currents is the problem of flux pinning. This is an important research area in both the new high Tc and the conventional low Tc metallic superconducting systems. The research is focused on cri tical current/microstructure/processing interdependences and seeks to improve the critical current of superconductors by improved processing.
Mechanical Behavior of Fine Filament Nb-Ti as a Function of Processing, Z. Guo and W.H. Warnes. IEEE Trans. Applied Superconductivity, 3(1), 1022 (1993).
Evaluation of Cu:SC Ratio Measurements by Chemical Etching, Electrical Resistivity, and Image Analysis, T. Pyon, W.H. Warnes and M. Siddall. IEEE Trans. Applied Superconductivity, 3(1), 1018 (1993).
Extended Measurements of the Resistive Critical Current Transition, G. Narang and W.H. Warnes. IEEE Trans. Applied Superconductivity, 3(1), 1269 (1993).
Cable Degradation of SSC Strand, W.H. Warnes, W. Dai, J. Seuntjens and D.W. Capone II. Adv. in Cryogenic Engineering -- Materials, 38:Plenum Press, NY (1992).
Shape Measurements of the Resistive Transition in SSC Strand, W.H. Warnes and W. Dai. Adv. in Cryogenic Engineering -- Materials, 38:Plenum Press, NY (1992).
Room Temperature Mechanical Properties of Nb-Ti/Cu Superconducting Composites, H. Liu and W.H. Warnes. Adv. in Cryogenic Engineering -- Materials, 38:Plenum Press, NY (1992).
Filament and Critical Current Degradations in Extracted Strands of SSC Cable, J.M. Seuntjens, D.W. Capone II and W.H. Warnes. Supercollider 3, Plenum Press, NY (1992).
Principles of Superconductivity, W.H. Warnes. In Metals Handbook, 10th edition, Volume 2, Properties and Selection: Nonferrous Alloys, Special-Purpose Materials and Pure Metals, ASM International pp. 1030-1042, (1990).
Notch Impact Properties and Variable Temperature Fracture Characterization of MIM Ne-Ni Alloys, Powder Metallurgy: Key to Advanced Materials Technology, W.H. Warnes, P. Bhave and C. Kim. ASM International, Vancouver, B.C., Canada, August (1990).
Micro-mechanical and thermophysical properties of materials, composites, metrology, spacecraft components and structures.
Dimensional stability is of concern to designers and users of many precision instruments such as optical and electronic components and structures. While composite materials offer unique properties for the application s, they also provide theoretical and measurement challenges. Research emphasis is on the use of laser interferometry to study microyielding and thermal expansion of advanced alloys, ceramics and glasses as well as composites. Current research includes t ime-dependent processes, such as diffusion, stress relaxation and creep.
Polymer Matrix Composites: Moisture Effects and Dimensional Stability pp. 279-323 in "International Encyclopedia of Composites" Vol. 4, S.M. Lee, Editor, VCH Publishers, Inc., (1991).
Creep in Composites, pp. 511-521 in "International Encyclopedia of Composites" Vol. 1. S.M. Lee, Editor, VCH Publishers, Inc. (1990).
Low Expansion Materials, Chapter 6.3 in "Handbook of Applied Thermal Design" E.C. Guyer, Editor, McGraw Hill Book Co. (1989).
The Synthesis and Fabrication of Ceramics for Special Applications: Preparation of Boron Nitride, Vol. 17 of "Inorganic Reactions and Methods" J.J. Zirchkermann, A.P. Hagen, Editor, VCH Publishers, Inc. (1989).
Radiation Effects on the Physical Properties of Low-Expansion-Coefficient Glasses and Ceramics, E.G. Wolff, P.L. Higbe et al, J. Am. Ceram. Soc., Vol. 71:7:796-802 (1988).
Thermal Expansion in Metal/Lithia Alumina-Silica Composites, Int. J. of Thermophysics, Vol. 9:2:221-232 (1988).
Prediction of the Microyield Strength of Polymer Matrix Composites, E.G. Wolff and S.T. Crane. J. Comp. Tech. & Res., Vol. 10(4):165-172 (1988).
Stiffness-Thermal Expansion Relationships in High Modulus Carbon Fibers, E.G. Wolff. J. Composite Materials, Vol. 21:81-97 (1987).
High-temperature oxide growth, microgravity materials processing, materials for advanced nuclear reactors.
Materials compatibility and wicking rate studies have been conducted to evaluate various working fluid/liner materials combinations for fabric composite radiators for space applications. Extended burnup in existing n uclear power reactors requires an understanding of the high temperature growth of oxides on zircalloy fuel rod cladding. Analysis has been performed to better understand the mechanisms of growth at the oxide/cladding interface and to model the thermal ch aracteristics of the cladding. A thawing experiment has been developed for flight on a Johnson Space Center KC-135 aircraft to evaluate void formation during phase changes under constrained, microgravity conditions. Studies also continue on materials to be used for advanced space nuclear reactor systems and in fusion reactor concepts.
An Experimental Comparison of Wicking Abilities of Fabric Materials for Heat Pipe Applications (with T.S. Marks). Proceedings 9th Symposium on Space Nuclear Power Systems, M.S. El-Genk and M.D. Hoover eds., American Institute of Physics, 1992.
Materials Compatibility Issues for Fabric Composite Radiators (with T.S. Marks) Proceedings 9th Symposium on Space Nuclear Power Systems, M.S. El-Genk and M.D. Hoover eds., CONF 910116, American Institute of Physics, 1991.
Lithium Hydroxide Accelerated Oxidation of Zircalloy-4, (with J.A. VanWinkle and M.A. McGuire). Trans American Nuclear Society, V60:549-550, San Francisco, CA, November 1989.
Design of a Laboratory Autoclave to Evaluate the Oxidation Rate of Fuel Cladding Under Isothermal and Thermal Gradient Conditions, (with M.A. McGuire). Proc. Third International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactor. G.J. Theus and J.R. Weeks, eds., The Metallurgical Society, 1988.
Alkaline paper making, pulping of straw, synthesis of novel graft copolymers of cellulose and characterization of pulp and paper by carbohydrate analysis.
Development of high strength synthetic polymer-cellulose composite plastics will require new methods to form graft copolymers. Methods to accomplish this are being developed using classical organic chemistry technique s. The methods must be expanded so grafting onto the surfaces of fibers in high yields is possible without damaging the fibers themselves. By this method, the use of cellulose fibers in molded plastics will greatly increase. The use of straw, which is now burned in open field burning, by the pulp and paper industry is quite possible in certain grades of paper. Paper making under alkaline conditions is becoming widespread in the industry. Problems with sizing and retention, however, are numerous. We are developing methods to circumvent these problems.
The application of durable press treatment to bleached softwood kraft handsheets, D. Horie and C.J. Biermann. Tappi J. 77(8):135-140 (1994).
Essentials of Pulping and Papermaking, C.J. Biermann. Academic Press, San Diego, 1993.
Consistency and temperature correction for Canadian Standard freeness with chemical pulps, C.J. Biermann, R. Sundrani and J.L. Hull. Tappi J. 76(5):147-152 (1993).
Rosin Sizing with Polyamine Mordants from pH 3 to 10, C.J. Biermann. TAPPI J. 75(5):166-171 (1992).
The Effect of fungal pretreatment on the strength and optical properties of soft and hardwood kraft pulps, B.E. Dawson-Andoh, J.J. Morrell, C.J. Biermann and J.L. Hull. TAPPI J. 74(10):187-189 (1991).
U.S. Patent 4,891,404. Biodegradable graft copolymers. Issued January 2, 1990.
Analysis of carbohydrates by GLC and MS, C.J. Biermann, and G.D. McGinnis, editors. CRC Press, Boca Raton, Florida (1989).
Process analysis, process modeling, process control, quality control, optical scanning, dielectric scanning.
Research is devoted to solving forest products problems through the development of computer-aided manufacturing techniques that are primarily modeling and scanning related. Current modeling projects include an analys is of log bucking in the woods versus at the mill, a 3-dimensional log breakdown optimization model, a microcomputer-based sawmill simulation program, evaluation of cutting yields from unedged red alder lumber, and grade clipping of softwood veneer. Curr ent scanning research includes optimizing wood processing through optical scanning research, improving lumber size control through on-line optical scanning, measuring surface roughness using a laser scatter/optical imaging technique, determining the spect ral reflectance of wood surface features, a performance evaluation of segmentation algorithms on wood surface features, and dielectric scanning for defects on wood surfaces.
Classifying wood-surface features using dichromatic reflection, A.G. Maristany, P.K. Lebow, C.C. Brunner, D.A. Butler and J.W. Funck. SPIE Vol. 1836 pp. 56-64 (1992), SPIE - The International Society for Optical Engineering, Bellingham, WA.
Measuring surface roughness on wood: a comparison of laser scatter and stylus tracing approaches, J.W. Funck, J.B. Forrer, D.A. Butler, C.C. Brunner and A.G. Maristany. SPIE Vol. 1821 pp. 173-184 (1992).
An adaptive image preprocessing algorithm for defect detection in Douglas-fir veneer, D.A. Butler, J.W. Funck and C.C. Brunner. Forest Products Journal 43(5):57-60.
An evaluation of color spaces for detecting defects in Douglas-fir veneer, C.C. Brunner, A.G. Maristany, D.A. Butler, D. VanLeuween and J.W. Funck. Industrial Metrology 2(3/4):169-184 (1992).
Using image analysis for lumber size control measurements, J.W. Funck, J.A. Gaber and F. Aslam. Industrial metrology 2(3/4):237-252 (1992).
Wood anatomy, wood quality, stem physiology, physiological ecology.
Research is related to the variation in anatomical properties of wood within an individual tree, between different trees and between species. Professor Gartner's research seeks to understand how that anatomical variat ion affects the function of the stem for the living tree, and the function of the wood for human uses. Many tree species produce juvenile wood near the center of the tree, which has inferior properties of warp, shrinkage, modulus of elasticity and streng th. By further understanding the role of that juvenile wood in plant physiology, Professor Gartner hopes to help predict the management techniques that will minimize the amount of juvenile wood produced. Also, surveys of lesser-known tree species to det ermine the presence and quality of juvenile wood will help to more efficiently match forest materials to their appropriate uses.
Patterns of xylem variation within a tree and their hydraulic and lmechanical consequences. In: Plant Stems: Physiology and Functional Morphology, B.L. Gartner, editor, pp. 125-149. Academic Press, San Diego (1995).
Wind-shelters as safe sites for establishment of Lupinus arboreus, a coastal species. Madrono 42, 1-11 (1995).
Root biomechanics and whole-plant allocation patterns: responses of tomato plants to steam flexure. Journal of Experimental Botany 45, 1647-1654 (1994).
Seasonal Variation of Urushiol Content in Poison Oak, (with C. Wasser, E. Rodriguez and W.L. Epstein). Am. J. of Contact Dermatitis, 4, 1-4 (1993).
Structural Stability and Architecture of Vines vs. Shrubs of Poison Oak, Toxicodendron diversilobum. Ecology 72, 2005-2015 (1991).
Relative Growth Rates of Vines and Shrubs of Western Poison Oak, Toxicodendron diversilobum (Anacardiaceae), Am. J. Botany 10, 1345-1353 (1991).
Stem Hydraulic Properties of Vines vs. Shrubs of Western Poison Oak, Toxicodendron diversilobum, Oecologia 87, 180-189 (1991).
Reserve Economy of Vines, H.A. Mooney and B.L. Gartner. In Biology of Vines, F.E. Putz and H.A. Mooney, eds., pp. 161-179, Cambridge University Press (1991).
Theoretical and experimental studies addressing problems in wood mechanics and engineering aimed towards the application of wood and wood-based composite materials, use of computerized data acquisition and control sy stems for destructive and/or non-destructive testing of wood structural systems, computer-aided analysis and design, development of reliability based design procedures for wood structures.
Metal-plate-connected joints under different loading conditions, R. Gupta. Submitted to Wood and Fiber Science (1993).
Mechanical properties for lumber of Dahurian larch, R. Gupta, R.L. Ethington and D.W. Green. Extended Abstract, Technical Forum presentation, FPS meeting (1993).
Resistance distributions of a metal plate connected wood truss, R. Gupta and K.G. Gebremedhin. Forest Products Journal, 42(7/8):11-16 (1992).
Destructive testing of metal plate connected wood truss joints, R. Gupta and K.G. Gebremedhin. Journal of Structural Engineering, 116(7):1971-1982 (1990).
An expert system for optimizing computer aided design of post frame buildings, K.G. Gebremedhin, S.S. Jagdale and R. Gupta. Journal of Applied Engineering in Agriculture, 5(3):447-452 (1989).
Development of new engineered composites from oriented natural and synthetic fibers. Mathematical simulation of rheological behavior, heat and mass transfer and adhesion kinetics within viscoelastic/hygroscopic por ous media (to model hot pressing of composites). Development of techniques for material characterization (physical properties).
Three broad areas of interactive processes affecting the formation of composites are being investigated. These are heat and mass transfer (with phase change), rheological behavior and strength development of adhesive bonds. Parameters of interest include temperature, moisture content, vapor pressure, and bond strength distributions within composites during the hot-pressing process. Orientation of fibers is being affected magnetically; spatially oriented molded comp onents are thereby being developed. Other research is devoted to studies of the relationship between composite fine structure and properties. This includes the use of computerized image scanning, x-ray scanning and time-lapse photography as specimens ar e deformed. Instrumentation for material characterization and process control is also being developed (permeability, hygroscopicity, viscoelasticity adhesion reactivity.)
Some Physical Transformations that Occur During the Cure of Thermosetting Adhesive-to-Wood Bonds, P.E. Humphrey. Proc. Wood Adhesives in 1990, Pub. Forest Res. Soc. and U.S. Forest Service, Madison WI.
Bonding Kinetics of Thermosetting Adhesive Systems used in Wood-Based Composites: The Combined Effect of Temperature and Moisture Content, P.E. Humphrey and Shan Ren. J. Adhesion Science and Technology. Vol. 3, 5:397:413, 1989.
The Hot Pressing of Dry-Formed Wood-Based Composites, P.E. Humphrey, A.J. Bolton and P.K. Kavvouras. Parts I through VI. Holzforschung. Ending *Part VI with Vol. 43(6):406-410, 1989.
A Technique to Evaluate the Bonding Reactivity of Thermosetting Adhesives, P.E. Humphrey and D. Zavala. J. Testing and Evaluation (A.S.T.M.). Vol. 17, 6:323-328, Nov. 1989.
An Automated Bonding Device, P.E. Humphrey. PATENT No. 5, 176, 028; January 5, 1993.
Wood adhesives, molecular structure, composite properties.
The program is aimed at improved forest products utilization by using current forest products residues to make new polymers and materials for the future. Improved and advanced adhesive systems based on renewable mate rials as a replacement for petro-chemical based adhesives is one aspect.
GPC of Natural procyandin oligomers and polymers, Y. S. Bae, L.Y. Foo, and J.J. Karschesy. Holzforschung. 48, 4-6 (1994).
Sulfonation of procyanidin polymers: Evidence of intramolecular rearragement and aromatic ring substitution. Y. S. Bae, J.C.S. Malan, and J.J. Karschesy. Holzforschung. 48, 119-123 (1994).
R.F. Gonzalez-Laredo and J.J. Karchesy, Polyphenols of Douglas-fir bark: Structures, reactions and significance. Ubamari, 31, 19-40 (1994).
R.F. Gonzalez-Laredo and J.J. Karchesy, Structure and significance of natural diarylheptanoids. Ubamari, 32, 15-31 (1994).
Comparison of the inhibitory effects of monomeric, dimeric, and trimeric prcyanidins on the biochemical markers of skin tumor promotion in mouse epidermis in vivo, H.U. Gali, E.M. Perchellet, Z.M. Gao, J.J. Karchesy, and J.P. Perchellet, Planta Medica. 60 , 235-239 (1994).
Reaction of catechin with N-hydroxymethylacetaminde: A first model for cross-linking PVA co-polymers with tannins, K.A. Wallace and J.J. Karchesy, Holzforschung (accepted).
J.J. Karchesy, “Structures and transformations of Douglas-fir bark polyphenols,” General Tech. Report SO-104, USDA, Research and Applications of Chemical Sciences in Forestry, 19-26 (1994).
Carbohydrates, polysaccharides, condensed tannins, bark chemicals.
Research involves to the isolation and characterization of adhesive components from tree barks. Tree barks contain as much as 20 percent of their dry weight in the form of polymers containing phenolic functional grou ps. These polymers react with formaldehyde to produce excellent adhesives with properties related to phenol-formaldehyde polymers. These natural polyphenolic polymers could replace part, or all, of the costly phenol in present phenol-formaldehyde resins or could be used in the synthesis of new adhesive systems. Research also includes molecular weight analyses of wood cellulose by size exclusion chromatography.
Determination of Carbohydrates in Wood Pulp Products, M.L. Laver and K.P. Wilson. Tappi J. 76(6):155-159 (1993).
The characterization of Charcoal and High-Density Carbon Pellets Produced from Douglas-fir Bark, M.A. Ali, M.L. Laver, C.J. Biermann, R.L. Krahmer and R.D. Sproull. Appl. Biochem. and Biotech., 24/25:75-86 (1990).
The Utilization of Douglas-Fir Bark for the Production of Oxalic Acid and High Density Carbon Pellets, A.M. Aslam, R.D. Sproull, M.L. Laver and C.J. Biermann. Appl. Biochem. and Biotech., 20/21:135-148 (1989).
Ferulic Acid Esteres from Bark of Pseudotsuga menziesii, M. Laver and H.H-L. Fang. J. Agr. and Food Chem. 27:114-116 (1989).
Solute Rejection in the Ultra Filtration of Polydisperse Organics from Natural Products, W.J. Fredericks, Jr., K.P. Wilson, M. Laver and S.A. Singuefield. Chem. and Engr. Commun. 68:197-221 (1989).
High Performance Liquid Chromatography (HPLC) of Carbohydrates, G.D. McGinnis, M.L. Laver and C.J. Biermann. In Analysis of Carbohydrates by GLC and MS, C.J. Biermann and G.D. McGinnis. Eds. CRC Press, Boca Raton, FL (1988).
Design and analysis of timber structures and composite structural materials.
Professor Leichti is involved with the mechanics of composite systems and materials in structural applications with a special emphasis on wood. The theories of anisotropic elasticity, viscoelasticity, and probability play important roles in his studies of long-range reliability of wood composites in dynamic environmental conditions. He is using finite element methods, strength theories, and closed-form solutions for problems of continuum mechanics. Professor Leicht i is also the editor of Wood Design Focus - The Newsletter of Contemporary Wood Engineering.
Straight, single-tapered composite I-beams of orthotropic materials, R.J. Leichti and C.H. Yoo. Journal of Materials in Civil Engineering, in press.
In the literature: inspection of existing timber structures, R.J. Leichti. Wood Design Focus, 2(4):20-21 (1991).
Finite-element model of a nonlinear intercomponent connection in light-frame wood structures, K.M. Groom and R.J. Leichti. pp4.346-4.353. In 1991 International Timber Engineering Conference, Vol.4 (1991). September 2-5, London, England Timber Research and Development Association, United Kingdom.
A nonlinear finite-element model for wood-frame stud walls, B. Kasal, M. Wang and R.J. Leichti. P.3.325-4.332. In 1991 International Timber Engineering Conference, Vol.4 (1991). September 2-5, London England Timber Research and Development Association, Un ited Kingdom.
Prefabricated wood composite I-beams: a literature review, R.J. Leichti, R.H. Falk and T.L. Laufenberg. Wood and Fiber Science, 22(1):62-79 (1990).
Prefabricated wood I-joists: an industry overview, R.J. Leichti, R.H. Falk and T.L. Laufenberg. Forest Products Journal, 40(3):15-20 (1990).
Comparative performance of long-term loaded wood composite I-beams and sawn lumber, R.J. Leichti and R.C. Tang. Wood and Fiber Science, 21(2):142-154 (1989).
Engineered wood products, timber engineering science, structural mechanical connections.
Understanding the mechanical properties of wood and wood-based products; the development of new technology and methods for structural design with specific wood products. Within the first area, the focus is on the inf luence of intrinsic and processing-imposed characteristics such as anatomy, growth defects, moisture content, and preservative treatment on the strength and stiffness of solid wood products in structural sizes. Particular emphasis is on statistical mecha nical connections and reliability-based design methods. Analytical and empirical models of connection response are used to develop performance estimates using stochastic descriptors.
Strength of end-notched wood beams: a critical fillet hoop stress approach, G.C. Foliente and T.E. McLain. Wood and Fiber Science 24(2):168-180 (1992).
Strength of wood beams with filleted interior notches, B. Zalph and T.E. McLain. Wood and Fiber Science 24(2):204-215 (1992).
Design of notched wood beams, G.C. Foliente and T.E. McLain. J. Structural Engineering, Vol. 118, No. 9, pp. 2407-2420 (1992).
Strength of lag screw connections, T.E. McLain. J. Structural Engineering, Vol. 118, No. 10, pp. 2855-2871 (1992).
Performance of nailed-bolted connections, T.E. McLain. Forest Products Journal 42(7/8):70-72 (1992).
LRFD for Engineered wood structures -- connection behavioral equations, T.E. McLain, L.A. Soltis, D.G. Pollock, Jr. and T.L. Wilkinson. J. Structural Engineering 19(10), 3024-3038 (1993).
Reinforcement of wood pallets with metal connector plates, J.W. Clarke, T.E. McLain, M.S. White and P.A. Araman. Forest Products Journal 43(11), 70-76 (1994).
Performance of oak strip flooring systems under changing environmental conditions, T.E. McLain. Forest Products Journal 44(5), 54-61 (1995).
Service life of wood species.
Research is directed toward improving the performance of wood and wood-based materials, including composites, by developing a better understanding of the mechanisms of wood deterioration, identifying technologies for e ffectively penetrating wood materials with preservatives, and developing methods for arresting deterioration of wood in structures. Recent studies include developing methods for deposition of biocides using supercritical carbon dioxide as the carrier. T he goal of this work is the complete protection of various wood-based materials without adverse effects of mechanical properties of the finished product..
Interactions of ammoniacal copper zinc arsenate (ACZA) with Douglas-fir, S.T. Lebow and J.J. Morrell. Wood and Fiber Science 27, 105-118 (1995)
Process for removing chemical preservatives from wood using supercritical fluid extraction, S.T. Levien, J.J. Morrell, S. Kumar, and E. Sahle-Demessie. U.S. Patent No. 5,364,475, Washington, DC (1994).
The effects of chromated copper arsenate and ammoniacal copper zinc aresnate on shear strength development of phenolic resin to sitka spurce bonds. T.R.N. Prasad, P.E Humphrey, and J.J. Morrell. Wood and Fiber Science 26, 223-228 (1994)
Assessing biocide effects on wood decay fungi using protoplasts, C. Rui and J.J. Morrell. Wood and Fiber Science 26, 205-211 (1994).
Relationship between incipient decay, strength and chemical composition of Douglas-fir heartwood, J.E. Winandy and J.J. Morrell. Wood and Fiber Science 25(3), 278 (1993).
Composites from recycled wood fiber and recycled plastic; industrial and groundwater wastewater treatment; sonic enhancement of wood treatment processes; chemical modification of wood.
Dr. Simonsen studies wood treatment products with a view to improving the environmental acceptability of wood preservatives and other wood treatments; wood/plastic composites as alternative materials to treated wood; the environmental remediation of existing problem sites in the wood treating industry and elsewhere; the treatment of industrial wastewater to improve water quality; wood treatment processes with a goal of improving their effectiveness and efficiency.
Wood-based composites, adhesives, fracture, solid mechanics, wood physics, nondestructive testing.
Professor Wilson studies the design, fabrication and testing of wood-based composites in order to optimize strength, stiffness, durability and creep resistance. He uses solid mechanics to predict properties of compos ite materials from consideration of its components. In addition, he has an active program in nondestructive testing using ultrasonics, gamma- and x-rays, and lasers to determine the material properties of wood-based materials during processing or in-serv ice. These experimental methods combined with solid mechanics analysis can be used to predict strength of wood materials such as composites, veneer, lumber and utility poles. He also studies nonconventional drying techniques such as the use of radio fre quency and heat pumps.
Application of Heat Pump Dehumidifiers, A Case Study: Drying of Lumber at Diamond Wood Products, J.B. Wilson. Bonneville Power Administration Report, U.S. Department of Energy, DOE/BP-92758-1 (1991).
Comparison of video and X-ray for scanning wood density, M.L. Clauson and J.B. Wilson. Forest Prod. J., 41:3 (1991).
Analysis of the Fluidized Bed Drying of Wood Particles, M.R. Milota and J.B. Wilson. Wood and Fiber Science, 22(2):193-203 (1990).
Nondestructive Evaluation of Wood Utility Poles In-service, J.B. Wilson. In Proceeding of ESMO-90., IEEE Toronto, Canada, June, pp. 73-77 (1990).
Radio-Frequency Drying of Wood Veneer - Commercial Use, J.B. Wilson. J. of Microwave Power and Electromagnetic Energy, 24(2):67-73 (1989).
An Overview of Nondestructive Testing, J.B. Wilson. Wood Pole Conference Proceeding, Portland, OR. pp. 47-51, (October 1988).
Dynamics of fluids and polymers.
Recent research has employed simple impulsive models as an aid to understand transport, reactive and equilibrium properties of complex fluids. Areas of current interest include: 1) transport properties of nonspherica l molecules in condensed phases, and equilibrium and structural properties of liquids and liquid crystals.
Second virial coefficients for nonspherical molecules: a convex peg in a round hole, G.T. Evans and E.B. Smith. Molec. Phys., 74, 79-84 (1991).
A van der Waals theory of nematic liquid crystals: a convex peg in a round hole potential, B. Tjipto-Margo and G.T. Evans. Molec. Phys., 74, 85-101 (1991).
Transport coefficients of hard nonspherical bodies: a kinetic theory approach, G.T. Evans. Molec. Phys., 74, 775-784 (1991).
Vibrational energy transfer and pair dynamics in liquids: a kinetic theory study, G.T. Evans and P.A. Madden, Molec. Phys., 74, 1171-1193 (1991).
The Frank constants of nematic liquid crystals: the convex peg in a round hole potential, G. Tjipto-Margo, G.T. Evans, M.P. Allen and D. Frenkel, J. Phys. Chem., 96, 3942-3928 (1992).
Liquid crystal smectic A phases and issues of geometry, G.T. Evans. Molec. Phys., 76, 1359-1374 (1992).
Hard body models for chiral nematic liquid crystals, G.T. Evans. Molec. Phys., 77, 969-981 (1992).
Steric Effects and Cones of Reaction in Gas Phase Reactions, M. Esposito and G.T. Evans. J. Chem. Phys., 97, 4846-4858 (1992).
Fiber optic chemical sensors, fluorescence and chemiluminescence measurements, chemical speciation, kinetics-based measurements.
Professor Ingle's research is concerned with developing instrumentation and methodology for determination of trace metals and organic species in environmental, clinical and industrial samples. Special emphasis is plac ed on combining spectrometric, electrochemical and separation techniques to determine specific chemical forms (e.g., oxidation states) of metals, and remote-sensing techniques based on fiber optics.
Chemiluminescence During the Oxidation of Alcohols by Permanganate: Determination of Ethanol in Gin, S.I. Montalvo and J.D. Ingle, Jr. Talanta, 40, 167-172 (1993).
Optimization of Atomic Fluorescence Measurements with a Microcomputer-Based Time-Multiplex Multiple-Slit Spectrometer, S. Ghaffari and J.D. Ingle, Jr. Talanta, 39, 749-757 (1992).
Fluorometric Kinetic Method for the Determination of Total Ascorbic Acid with o-Phenylenediamine, H.K. Chung and J.D. Ingle, Jr. Anal. Chim. Acta, 243, 89-95 (1991).
Detection and Correction of Multiplicative Interferences in Single-Line Flow Injection Analysis with Fluorescence Detection, H.K. Chung and J.D. Ingle, Jr., Anal. Chem., 62:2541-2547 (1990).
Design and Evaluation of a Dual Multichannel Detector Spectrometer for Simultaneous Molecular Absorption and Luminescence Measurements, C. Yappert, M.W. Schuyler and J.D. Ingle, Jr., Anal. Chem., 61:593-600 (1989).
Automated Two-Column Ion Exchange System for Determination of the Speciation of Trace Metals in Natural Waters, Y. Liu and J.D. Ingle, Jr., Anal. Chem., 61:525-529 (1989).
Monitoring and Compensating for Between-run Temperature and pH Variations in Kinetics-based Determinations, G.L. Campi and J.D. Ingle, Jr., Anal. Chim. Acta, 224:275-287 (1989).
Spectrochemical Analysis, J.D. Ingle, Jr. and S.R. Crouch. Prentice Hall, NJ (1988), pp. 1-608.
Experimental Comparison of Single- and Double-Fiber Configurations for Remote Fiber Optic Fluorescence Sensing, J. Louch and J.D. Ingle, Jr., Anal. Chem., 60:2537-2540 (1988).
Preparation and study of new and unique solid-state inorganic materials. Single-crystal X-ray diffraction, powder X-ray and neutron diffraction, luminescence spectroscopy, band structure calculations.
Solid-state lasers are the foundation for much of modern research and industrial development; as such, greater demands are being placed on their performance characteristics. We have initiated several projects in the synthesis of new materials of interest as new lasing media that should offer higher power, greater tuneability, improved efficiency and new ranges of wavelength. Many of the materials under investigation are also of general interest as new phosphors or n onlinear optical materials.
“Borates: Solid State Chemistry,” D. Keszler. In Encyclopedia of Inorganic Chemistry, ed. J. K. Burdett, Wiley, New York (1994).
The Framework Structure of BaBe2(BO3)2, K. I. Schaffers and D. Keszler. Inorg. Chem. 33, 1201-1204 (1994
Triangulated Polyhedra in the Borate Li14Be5B(BO3)9, J. Luce, K. I. Schaffers, and D. Keszler. Inorg. Chem. 33, 2453-2455 (1994).
The Buetschliite Derivative K2Zr(BO3)2, . Akella and D.A. Keszler. Inorg. Chem. 33, 1554-1555 (1994).
Structure of InBO3 , J.R. Cox and D.A. Keszler. Acta Crystallogr., Sect. C 50, 1857-1859 (1994).
New Borate Structures for NLO Applications, D.A. Keszler, A. Akella, K.I. Schaffers, and T. Alekel III . Mat. Res. Soc. Symp. Proc., Vol. 329, pp. 15-22, B.H.T. Chai, S. A. Payne, T.Y. Fan, A. Cassanho, and T.H. Allik (Eds.), Materials Research Society, P ittsburgh, PA (1994).
Structure of Sr3Sc(BO3)3, P.D. Thompson and D.A. Keszler. Chem. Mater. 6, 2005-2007 (1994).
Polymer/solid nanocomposites, intercalation chemistry, electrosynthesis, battery chemistry, fluorine chemistry.
Research examines the chemical and electrochemical synthesis of new inorganic solids and polymers. Special emphasis is placed on materials with interesting and useful electrical properties such as intercalation compo unds, polymer electrolytes and reversible polymerization electrodes.
Formation of a Photoluminescent Surface on n-Si by Irradiation Without an Externally Applied Potential, Z. Zhang, M. Lerner, T. Alekel and D. Keszler. J. Electrochem Soc., 1993, 140, L97.
Generation of a Photoluminescent Coating by the Electrochemical Oxidation of n-Si in Anhydrous Hydrogen Fluoride, Z. Zhang, M. Lerner, T. Alekel and D. Keszler. Chem. Mater., 1993, 4, 749.
Structural and Electrical Characterization of Layered Nanocomposites of Na-Montmorillonite and Polyethers, J. Wu and M. Lerner. Chem. Mater., 1993, 5, 835.
Characterization of a Stoichiometric Range of Poly(ethylene oxide)-Sodium Salt Complexes by Differential Scanning Calorimetry and 23Na NMR, J. Lemmon, R. Kohnert and M. Lerner. Macromol., 1993, 26, 2767.
Electrochemical Oxidation of Graphite Fluorides using Transition Fluorometallate Salts in Anhydrous Hydrogen Fluoride, J. Lemmon and M. Lerner. Electrochem. Soc., 1993, 140, 742.
Synthesis of Planar-Sheet Graphite Fluorides using Transition Fluormetallate Salts in Anhydrous Hydrogen Fluoride, J. Lemmon and M. Lerner. Carbon, 1993, 31, 437.
STM of the (010) Surface of Orthorhombic Phosphorus, S. Yau, T. Moffat, A. Bard, Z. Zhang and M. Lerner. Chem. Phys. Let., 1992, 198, 383.
Effect of Salt Concentration on the Ionic Conductivity of Amorphous Poly(ethylene oxide)-Sodium Salt Complexes. J. Lemmon and M. Lerner. Macromolecules, 1992, 25, 2907.
The Use of Polysulfides and Copolymeric Disulfides in the Li/PEO/SRPE Battery System, M. Doeff, M. Lerner, S. Visco and L. DeJonghe. Electrochem. Soc., 1992, 139(8), 20775
Dimensional continuation methods; correlation effects in electronic structure.
Current work is directed toward applications of a new method for the approximate treatment of electron correlation. The method, which is size-consistent and not parameterized, can be used to investigate large or exte nded systems not amenable to treatment by other available techniques, and is currently being used to assess correlation effects in heavy atoms and in metallic hydrogen. The new method is complementary to both post-Hartree-Fock and density functional tech niques, and means for linking it with these more familiar approaches are also being explored. A related method has been developed for treating many-body effects in classical hard-body fluids; this is being use to extend virial series to higher order, and to investigate metastable fluid phases.
Large-D limit for metallic hydrogen, J.G. Loeser. In Dimensional Scaling in Chemical Physics, D.R. Herschbach, et. al., editors pp. 389-427 (Kluwer, 1993).
Scaling and interpolation for dimensionally generalized electronic structure, M. Lopez-Cabrera, A.L. Tan and J.G. Loeser. J. Phys. Chem. 97:2467-78 (1993).
Dimensional interpolation of hard sphere virial coefficients, J.G. Loeser, Z. Zhen, S. Kais and D.R. Herschbach. J. Chem. Phys., 95:4525-4544 (1991).
Nonlinear laser Raman spectroscopy, molecular spectroscopy of transient species, studies of molecules and plasmas at extreme temperatures.
This research involves the application of new, sensitive optical methods for obtaining spectra of species present in "hostile" samples such as flames, plasma discharges or condensing expansions. The results give deta iled information about molecular identities, structures, concentrations and reactions. Part of the work deals with energy transfer processes in gases and in simple solid materials.
Coherent Raman Study of the Formation and Phase Transitions of Acetylene Nanoclusters, K.H. Lee, N.E. Triggs, and J.W. Nibler. J. Phys. Chem 98, 4382-4388 (1994)
266 nm CH3I Photodissociation: CH3 Spectra and Population Distributions by Coherent Raman Spectroscopy, M. Zahedi, J.A. Harrison, and J.W. Nibler. J. Chem. Phys. 100 (1993).
Coherent Raman Observations of Factor Group Splittings and Lattice Vibrations in Nanocrystals Formed in Supersonic Expansions, K.H. Lee, K.W. Brown, N.E. Triggs, A.D. Richardson, N.E. Rich and J.W. Nibler. J. Chem. Phys. 98, 10100-1 (1993).
Use of Seeded Nd:YAG Lasers for High Resolution Spectroscopy, J.A. Harrison, M. Zahedi and J.W. Nibler. Optics Lett. 18, 149-151 (1993).
High Resolution Rotational and u3 Coherent Raman Spectra of C2H6, A. Al-Kahtani, S. Montero and J.W. Nibler. J. Chem. Phys. 98, 101-109 (1993).
High Resolution Study of the u1 Vibration of CH3 by Coherent Raman Photofragment Spectroscopy, N.E. Triggs, M. Zahedi, J.W. Nibler, P. DeBarber and J. Valentini. J. Chem. Phys. 96, 1822 (1992).
Coherent Raman Spectroscopy: Techniques and Recent Applications, J.W. Nibler. In Applied Laser Spectroscopy, M. Inguscio and W. Demtroder, eds. NATO Advanced Study Institute Series B: Physics Vol. 241, pp. 313-328, Plenum, New York (1990).
Stimulated Raman Probing of Supercooling and Phase Transitions in Large Nitrogen Clusters Formed in Free Jet Expansions, R.D. Beck, M.F. Hineman and J.W. Nibler. J. Chem. Phys. 92, 7068-7078 (1990).
Synthesis of polybenzimidazoles and high performance polymers.
New monomers are being prepared which will be used to synthesize new polybenzimidazoles. The major objective is to find cost-effective ways to prepare such polymers with desirable manufacturing characteristics and im proved properties for specialty applications.
Synthesis of Polybenzimidazoles with Ether and Sulphone Links, R.W. Thies, G.R. Collins and D.L. Cook. Proc. Oregon Acad. Sci. 1993, 29, 17.
Synthesis of Polybenzimidazoles With Flexible Links, R.W. Thies, G.R. Collins, C.K. Wellborne, C.B. Svendsen, A.A. Ross, S.D. Grimes and D. Azmus. Proc. Oregon Acad. Sci. 1992, 28.
Synthesis of 2, 2'-Bis(4-(3,4-diaminophenoxy)phenyl)propane and Its Polymerization, R.W. Thies, G.R. Collins, T. Sekin, C.K. Wellborne, C.B. Svendsen, A.R. Ross and S.D. Grimes. Macromolecules 1992, 25, 1207.
Ring-expansion Methods for Synthesis of Large-ring Hormone Analogs, R.W. Thies, J. Pierce, S.T. Yue, E. Sansui and P.C. Tjoa. Proc. Oregon Acad. Sci. 1990, 26.
Synthesis of Substituted Benzo, Medium-sized Ring Compounds, R.W. Thies and C. James. Proc. Oregon Acad. Sci. 1988, 24, 17.
Preparation of Polybenzimidazoles, R.W. Thies and T. Seckin. Proc. Oregon Acad. Sci. 1988, 24, 16.
Surface chemistry- structure and bonding at surfaces of solids and liquids; application to transport of pollutants in soils and to heterogeneous catalysis.
Dr. Watson's principal research projects are (i) modelling the adsorption and transport of pollutants in soils using well-defined oxide surfaces; (ii) determination of the composition and orientation of molecules at liquid surfaces; (iii) studies of the surface chemistry involved in catalytic production of fuels; and (iv) determination of atomic structure of oxide surfaces
“Scanning tunnelling microscopy on pressed powders", Z. Zhang, M.M. Lemer, V.J. Marty and P.R. Watson, Lantamuir, 8. 369-371, (1992)
"Surface structure of the disordered Cl/Ti(OOOI) system determined by diffuse low-energy electron diffraction", C-S. Ri and P.R. Watson, Journal of Vacuum Science and Technology, AIO, 2535-2539, (1992).
"The adsorption and thermal desorption of chlorine from GaAs(100) surfaces: implications for electron-induced etching", S.M. Mokler, P.R. Watson, L. Ungier and J.R. Arthur, Journal of Vacuum Science and Technolojzy, B 10, 23 71-23 77, (1992).
"Adsorption site and the role of substrate reconstruction for the Mo(I 10) p(2x2)-S system", J. Toofan, G. R. Tinseth and P.R. Watson, Journal of Vacuum Science and Technology, A12, 22462249 (1994).
"A new image processing method for extracting integrated intensities from LEED diffraction spots", J. Toofan and P.R. Watson, Review of Scientific Instruments, 65, 3382-3387 (1994).
"Atlas of Surface Structures: Volume IA", P.R. Watson, M.A. Van Hove and K. Hermann, Journal of Physical and Chemical Reference Data Special Monograph No. 5, American Chemical Society/American Physical Society, 907 pp, ISBN 1-56396-413-9.
"Atlas of Surface Structures: Volume IB", P.R. Watson, M.A. Van Hove and K. Hermann. Journal of Physical and Chemical Reference Data Special Monograph No. 5, American Chemical Society/American Physical Society, 352 pp, ISBN 1-56396-414-7.
Electrochemistry, oxide aqueous electrolyte interface chemistry.
The properties of the interface between oxides and aqueous electrolytes are being studied. The questions addressed are relevant to the development of chemically sensitive semiconductor devices, properties of oxide co lloids and oxide catalysts, and corrosion. Experiments are conducted with colloidal suspensions of oxides and semiconductor-oxide electrodes. Questions addressed include the structure of the electric double layer, the dependence of interfacial potential difference on electrolyte composition, and the specific absorption of ions.
Adsorption of Organic Cations to Natural Materials, B. Brownawell, H. Chen, J. Collier and J. Westall. Environ. Sci. Technol., 24:1234-1241 (1990).
The Distribution of LiCl, NaCl, KCl, HCl, MgCl2, and CaCl2 between Octanol and Water, J.C. Westall, C.A. Johnson and W. Zhang. Environ. Sci. Technol., 24:1803-1810 (1990).
Distribution of Hydrophobic Inogenic Organic Compounds between Octanol and Water: Organic Acids, C.T. Jafvert, J.C. Westall, E. Grieder, R.P. Schwarzenbach. Environ. Sci. Technol., 24:1795-1803 (1990).
Distribution of Hydrophobic Inogenic Organic Compounds between Octanol and Water: Organic Bases, C.A. Johnson and J.C. Westall. Environ. Sci. Technol., 24:1869-1875 (1990).
Reactions at the Oxide Solution Interface: Chemical and Electrostatic Models, J. C. Westall. In ACS Symposium Series No. 323, American Chemical Society, Washington, (1986).
The Influence of pH and Ionic Strength on the Aqueous-Nonaqueous Distribution of Chlorinated Phenols, J.C. Westall, C. Leuenberger and R. Schwarzenbach. Environ. Sci. Technol., 19:193-198 (1985).
Kinetics and Mechanism of Dissolution of Bayerite in HNO3-HF Solutions at 298.2, K.K. Pulfer, P. Schindler, R. Grauer and J.C. Westall. J. Coll. Interface Sci. 101:554-560 (1984).
Probability theory and mathematical modelling of physical processes.
The main focus of Dr. Waymire's research is in the development of mathematical methods for understanding large systems of interacting components; e.g., ferromagnetic spin systems, river networks and network flows, prec ipitation systems.
Quantized energy cascade and log-Poisson statistics in fully developed turbulence, Z. S. She and E. Waymire. Phys. Rev. Letters 74(2), 262-265 (1995).
A general decomposition theory for random cascades, E. Waymire and S. Williams. Bulletin of American Mathematical Society 31(2), 216-222 (1994).
A statistical analysis of mesoscale rainfall as a random cascade, V.K. Gupta and E. Waymire. Jouranl of Applied Meterology 32, 251-267 (1993).
Multifractal dimensions and scaling exponents for strongly bounded random cascades, R. Holley and E. Waymire. Annals of Applied Probability 2(4), 819-845 (1992).
On a symmetry of turbulence, S. Peckham and E. Waymire. Comm. in Math. Physics 147, 365-370 (1992).
A large deviation rate and central limit theoreum for Horton ratios, S. Xi Wang and E. Waymire. SIAM J. of Discrete Math., 4:575-588 (1991).
On weighted heights of random trees, R. Durrett, H. Kesten and E. Waymire. J. Theor. Probability 4:223-237 (1991).
An extension of the method of images for a construction of reflecting diffusions, R. Bhattacharya and E. Waymire. Probability, Statistics and Design of Experiments, 157-164 (1990).
Multiscaling properties of spatial rainfall and river flow distributions, E.C. Waymire and V.K. Gupta. J. Geophys. Res., 95(D3):1999-2010 (1990).
Tree dependent extreme values: Exponential Case, E.C. Waymire, V. Gupta and O. Mesa. Journal of Applied Probability, 27:1-10 (1990).
Book: Stochastic Processes with Applications. Wiley & Sons, Publ. Co., Feb., (1990), R.N. Bhattacharya and E.C. Waymire.
Infinite divisibility of a Bethe lattice Ising model, (with C. Glaffig). Journal of Statistical Physics, 47(1/2):185-192 (1987).
Diode lasers, frequency noise in diode lasers, tunable diode laserheterodyne spectroscopy.
Coherence of diode lasers.
Diode Laser Noise Spectroscopy of Rubidium (with D. H. McIntyre, J. Cooper, and R. Walser), Opt. Lett. 18, 1816-1818 (1993).
Tunable Diode laser Heterodyne Spectroscopy of Atmospheric Oxygen (with R. J. McLean, P. Hannaford, and P. L. Dyson), Opt. Lett. 18, 1675-1677.
Processing and materials properties at elevated temperatures. Magnetism. Hyperfine experimental techniques (NMR, NQR, g-g correlation spectroscopy). Research on metals, semiconductors, ceramics and superconductor s.
Microscopic structure and dynamic properties of metals, ceramics, semiconductors and superconductors are investigated by nuclear hyperfine experimental methods, often at elevated temperatures or pressures. Structure of dopant/defect complexes, diffusion and trapping of lattice defects and dynamic properties and metastable structure near phase transformations are topics of current interest. Cerium oxide, zirconium oxide, hafnium oxide, yttrium-barium-copper oxide, bo ron carbide, niobium-tin, gallium arsenide, cadmium telluride and experimental steels are materials presently being studied. Experimental techniques include Perturbed Angular Correlation (PAC) spectroscopy, Mössbauer spectroscopy, Nuclear Magnetic Resona nce (NMR), Nuclear Quadrupolar Resonance (NQR), and magnetic susceptibility.
High temperature NMR study of intrinsic defects in GaAs, W.-M. Han, J.A. Gardner and W.W. Warren, in Proceedings of the 16th International Conference: Defects in Semiconductors 16, Lehigh University, Pennsylvania, eds. G. Davies, G.G. DeLeo and M. Stavola , Tans. Tech. Publications 1991, 971-978.
PAC spectroscopy of electronic ceramics, J.A. Gardner, R. Wang, R. Schwenker, W.E. Evenson, R.L. Rasera and J.A. Sommers. In Proceedings of XXVI Zakopane School on Physics: Condensed Matter Studies by Nuclear Methods, eds. J. Stanek and A.T. Pedziwiatr, W orld Scientific Publ. Co. 1991 p. 72-87.
PAC analysis of defect motion by Blume's stochastic model for I=5/2 electric quadrupole interactions, W.E. Evenson, J.A. Gardner, R. Wang, H.-T. Su and A.G. McHale. Hyperfine Interactions 62:283-300 (1991).
Structural and electronic properties of indium-doped YBa2Cu3Os, G. Weidlich, M. Goelz, R. Wang, W. Evenson, J.A. Gardner, D.A. Keszler, J.A. Sommers and J.E. Ostenson. J. Mater. Res., 6:446-449 (1991).
Perturbed angular correlations of impurity interactions in a cubic host metal: Hf in Nb, W.H. Warnes and J.A. Gardner. Phys. Rev. B, 40:4276-4280 (1989).
Shock waves in condensed matter, intact capture of hypervelocity particles in underdense media.
Experimental/theoretical work concerning the physics of hypervelocity impact in condensed matter. Use of the Vertical Gun Range Facility at NASA's Ames Research Center to simulate capture of interplanetary material. Goal: to determine the characteristics needed by collector media for successful intact capture of cometary coma material.
Effect of Void-Size Distribution on the Hugonist State at Low Shock Pressures, D.J. Griffiths, D.J. Buettner and P. Tsou. J. Appl. Phys. 70:4790-4796 (1991).
Mesostructural Influence on the Hugonist State of Underdense Media at Low Shock Pressures, D.J. Griffiths, D.J. Buettner and P. Tsou. Bull. Am. Phys. Soc., 36:1844 (1991).
Comet Coma Sample Return: Theoretical consideration of collector response for intact capture, D.J. Griffiths. Jet Propulsion Laboratory, Caltech, Report No. JPL D-6237 (1989).
Critical Behavior of Amorphous Gd0.70Pd0.30H0.20, D.J. Griffiths, G. Gold, B. Boucher and R. Tourbot. J. Phys. F: Met. Phys. 18, 993-1000 (1988).
Nonlinear optical phenomena, surface coherent Raman spectroscopy, surface and interfacial structure and dynamics.
The research is concentrated in two programs. The first is based upon the development and use of nonlinear optical phenomena for studies of the structures and photo-initiated dynamics of surfaces and interfaces. The second is concerned with the investigation of the nonlinear optical properties of organic and inorganic materials.
Third-order susceptibility sensors of partially ordered systems, T.L. Mazely and W.M. Hetherington III. J. Chem. Phys. 87(4), 1962 (1987).
CARS Spectrum of O2-formed by the trapping of photo-generated electrons on a ZnO surface, W.M. Hetherington III, W.M.L.P. Wijekoon and E.W. Koenig. Chem. Phys. Lett. 134(3), 203 (1987).
Ethylene Adsorption on ZnO: CARS spectroscopy with Optical Waveguides, W.M.K.P. Wijekoon, Z.Z. Ho and W.M. Hetherington III. J. Chem. Phys. 86(8), 4384 (1987).
Calculations of electronic, magnetic and structural properties of solids. Fundamentals of density functional theory.
Very precise electronic structure calculations have become possible with the recent increase in computer power. Present day precision in sufficient to bring experiment and theory in good agreement and to make reliabl e theoretical predictions. We investigate the electronic structure of zirconia, which is an important compound in high temperature applications. These calculations are challenging because of the large size of the unit cell. Other work focuses on effect s related to the magnetic anisotropy of materials, which needs high precision due to the small differences in energy involved.
Electronic structure of cubic and tetragonal zirconia, H.J.F. Jansen. Phys. Rev. B., 43(9):7267 (1991).
Electronic structure of face-centered tetragonal iron, S.S. Peng and H.J.F. Jansen. Journ. of Appl. Physics 67:4567 (1990).
Total energy calculations for ZrO2, H.J.F. Jansen and J.A. Gardner. Physica B 150:10 (1988).
Magnetic anisotropy in density functional theory, H.J.F. Jansen. Phys. Rev. B. 38, 8022 (1988).
Hyperfine interactions in ferromagnets and rare earth magnets; angular correlations, nuclear orientation and nuclear magnetic resonance at ultralow temperatures.
The orientation of nuclear spins at temperatures below 0.01 Kelvin serves to probe both nuclear properties and the atomic environment, including the hyperfine coupling of the nucleus and electrons. Using this techniq ue, in combination with gamma-ray angular correlations and nuclear magnetic resonance, we are developing systematic information on the hyperfine magnetic fields experienced by various dilute impurities in ferromagnetic hosts and also electric field gradie nts in crystalline environments.
Gamma-Ray Angular Correlations in the Decays of 109Pd and 111Pd, D.E. Brown and K.S. Krane. Nucl. Phys. A 489 100-110 (1988).
Nuclear Orientation and Nuclear Structure, K.S. Krane. Hyperfine Interactions 43:3-14 (1988).
UNISOR On-Line Nuclear Orientation Facility, I.C. Girit et al., Hyperfine Interactions 43:151-156 (1988).
On-Line Nuclear Orientation, K.S. Krane. Nuclear Instruments and Methods in Physical Research, B26:452-462 (1987).
On-Line Nuclear Orientation Study of 184Au, Y. Xu, K.S. Krane, M.A. Gummin, J.L. Wood, M.M. Jarrio, J.B. Breitenbach, E.F. Zganjar, D. Rupnik, H.K. Carter, P.F. Mantica, Jr. and B.E. Zimmerman. Hyperfine Interactions 75, 481 (1992).
Shape Coexistence and Electric Monopole Transitions in 184Pt, Y. Xu, K.S. Krane, M.A. Gummin, M. Jarrio, J.L. Wood, E.F. Zganjar and H.K. Carter. Phys. Rev. Letters 68, 3853 (1992).
Nuclear Structure Studies of 187Ir via On-Line Nuclear Orientation, M.A. Gummin, K.S. Krane, Y. Xu, T. Lam, E.F. Zganjar, J.B. Breitenbach, B.E. Zimmerman, H.K. Carter and P.F. Mantica, Jr. Hyperfine Interactions 75, 447 (1992).
Recent Developments in On-Line Nuclear Orientation: Review and Summary, K.S. Krane. Hyperfine Interactions 75, 545 (1992).
Laser spectroscopy, laser cooling and trapping of neutral atoms.
Diode lasers provide a compact and efficient source of coherent radiation that can be used for atomic spectroscopy. Efforts are focused on frequency stabilization of diode lasers and their use in experiments to cool and trap neutral atoms. Very cold atoms are used for experiments to study atomic interferometry and long range atom-atom interactions.
Interferometric Frequency Measurement of 130Te2 Reference Transitions at 486 nm, D.H. McIntyre, W.M. Fairbank, Jr., S.A. Lee, T.W. Hänsch and E. Riis. Phys. Rev. A, 41:4632 (1990).
Optically Stabilized Narrow Linewidth Semiconductor Laser for High Resolution Spectroscopy, A. Hemmerich, D.H. McIntyre, C. Zimmerman, T.W. Hänsch and E. Riis. Phys. Rev. A, 41:4632 (1990).
Second Harmonic Generation and Optical Stabilization of a Diode Laser in an External Ring Resonator, A. Hemmerich, D.H. McIntyre, C. Zimmerman and T.W. Hänsch. Phys. Rev. A39:4591 (1989).
A Blue Dye Laser with Sub-KiloHertz Stability, R. Kallenbach, C. Zimmerman, D.H. McIntyre, T.W. Hänsch and R.G. DeVoe. Opt. Commun. 70:56 (1989).
Laser Spectroscopy of Very Simple Atoms, D.H. McIntyre. Comments At. Mol. Phys. 21:295 (1988).
High temperature superconductivity, low temperature physics.
Magnetic and transport properties of thin films of various high temperature superconductors are studied to determine the nature of vortex motion in these extreme type II superconductors. There is a thin-film depositi on system producing high-quality YBa2Cu3O7 samples for use in these measurements. We also incorporate radioactive tracers into the films so that the technique of perturbed angular correlation spectroscopy can be applied to reveal details of the film stru cture and growth mechanism.
Precise determination of the Cooper pair mass, J. Tate and B. Cabrera, Phys. Rev. B 42, 7885-7893 (1990).
The resistive transition of superconducting Nd2-xCexCuO4-( films", J. Tate and B. A. Hermann, Physica C 193, 207-211 (1992).
Study of phonon pulse propagation in silicon and the effect of N-processes", M. Obry, J. Tate, P. Berberich, and H. Kinder. In Phonon Scattering in Condensed Matter VII, Springer Series in Solid State Sciences, Vol. 112, p. 84, M. Meissner and R. O. Poh l (Eds.), Springer, Berlin (1993).
Incorporation of hyperfine probes into the thin-film superconductor YBa2Cu3O7-( during deposition, D. W. Tom, R. Platzer, J.A. Gardner and J. Tate. Appl. Phys. Lett. 63, 3224-3226 (1993).
Field dependence of the current-voltage characteristics of thin-film YBaCuO at low magnetic fields": J. Roberts, B. A. Hermann, G. Karapetrov, D. W. Tom, A. Spofford, and J. Tate. Physica B 194-196, 1889 (1994).
Scaling of voltage-current characteristics of thin-film YBaCuO at low magnetic fields", J.JM.J. Roberts, B. Brown, B.A. Hermann, and J. Tate. Phys. Rev. B. 49, 6890 (1994).
Scaling of thin-film NdCeCuO resistivity-current isotherms at low fields: implications for vortex phase transitions and universality", J. M. Roberts, B. Brown, J. Tate, X. X. Xi, and S. N. Mao. Accepted for publication in Phys. Rev. B (1995).
Enhanced flux creep in BiSrCaCuO thin films, G. Karapetrov and J. Tate, submitted to Phys. Rev. B (1995).
High temperature microscopic structure of of YBa2Cu3Ox studied by 111In/Cd time differential g-g perturbed angular correlation spectroscopy, R. Schwenker, A Fssel, D. Tom, R. Platzer, J. Tate, J.JA. Gardner, W. E. Evenson, and J. A. Somers. In preparatio n (1995).
Nuclear magnetic studies of high Tc superconducting oxides, high temperature electronic materials, defects in semiconductors and electronically conducting fluids.
Nuclear magnetic resonance (NMR) is a highly local, atomic scale probe of the local magnetic fields and electric field gradients in condensed matter. NMR is used to study spin fluctuations in superconducting oxides, microscopic electron transport at high temperatures, structure and local dynamic properties of defects in semiconductors, electron localization, etc.
Nuclear Resonance Properties of YBa2Cu3O6+x Superconductors, R.E. Walstedt and W.W. Warren, Jr. Science 248, 1082 (1990).
Absence of Magnetic Pair Breaking in Zn-Doped YBa2Cu3O7, R.E. Walstedt, R.F. Bell, L.F. Schneemeyer, J.V. Waszczak, W.W. Warren, Jr., R. Dupree and A. Gencten. Phys. Rev. B 48, 10646 (1993).
NMR Study of Sodium Dispersed in Zeolites, G. Schäfer, W.W. Warren, Jr., P. Anderson, and P.P. Edwards. J. Non-Crystall. Solids 156,803 (1993).
Magnetic Susceptibility of Cs and Rb from the Vapor to the Liquid Phase, R. Redmer and W.W. warren, Jr. Phys. Rev. B 48, 14892 (1993).
Negative Thermal Expansion and Phase Transitions in the ZrV2-xPxO7 Series, V. Korthuis, N. Khosrovani, A.W. Sleight, N. Roberts, R. Dupree, and W.W. Warren, Jr., Chem. Mater. 7, 412 (1995).
The mechanism responsible for high temperature superconductivity remains an open question. Attempts to limit the range of possibilities lie, in part, in discovering the symmetry of the superconducting order parameter. The de Haas-van Alphen effect is now known to exist even in the superconducting state, i.e. for fields below the critical field Hc2 (see Ref. 6). Details of the theory which relate the amplitude of dHvA signals in the superconducting state to order parameter anisotropy are being investigated with the ultimate goal of producing a useful deconvolution method for mapping order parameter symmetry in superconductors.
Comment on de Haas-van Alphen amplitudes in heavy electron compounds, A. Wasserman and M. Springford. J. Phys. C. 21, 2779-81 (1988).
An asymptotically exact mean field approach for Hubbard X-operators, A.C. Hewson and A. Wasserman. J. Phys.: Condensed Matter I, 403-06 (1989).
Theory of de Haas-van Alphen effect for heavy Fermion alloys, A. Wasserman, M. Springford and A.C. Hewson. J. Phys.: Condensed Matter I, 2669-76 (1989).
De Haas-van Alphen effect in a marginal Fermi liquid, A. Wasserman and M. Springford. J. Phys.: Condensed Matter 3, 5335 (1991).
Evidence for the Anderson lattice model from dHvA studies in CeCu6, M. Hunt, P. Meeson, P-A. Probst, M. Springford and A. Wasserman. J. Magnetism and Magnetic Materials 108, 127 (1992).
dHvA effect in the vortex state of a type II superconductor, A. Wasserman and M. Springford. Physica B (in press, 1993).
Spectroscopic characterization of fiber microstructures and fiber degradation mechanisms.
My research interests include two major areas: (1) study the natural pigments from colored cotton fibers and (2) use microwave radiation for the disinfestation of mildew infected textiles.
Chen, H.-L., Jakes, K.A., and Foreman, D.W. "Preservation of Archaeological Cellulosic Fibers Through Mineralization," J. Archaeol. Sci. (1998), in press.
Chen, Hsiou-Lien, Jakes, K.A. and Foreman, D.W. "SEM, EDS, and FTIR Examination of Archaeological Mineralized Plant Fibers," Textile Res. J. 66 (4), 219-224 (1996).
Chen, H.-L., Foreman, D.W., and Jakes, K.A. X-Ray Diffractometric Study of Archaeological Mineralized Plant Fiber Microstructure," in Archaeological Chemistry: Organic, Inorganic, and Biochemical Analysis, ACS Symp. Series 625, American Chemical Society, Washington DC (1996)."
Chen, H.-L. and Noel, C.J. "Experimental Methods for the Analysis of Dye Desorption," Textile Chemist and Colorist, 27 (2) (1995).
Jakes, K.A., Chen, H.-L., and Sibley, L.R. "Toward the Development of a Classification System for Plant Fibers," Ars Textrina, 20 (1993).