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Biodesulfurization of rubber materials

One of the most challenging problems in municipal waste treatment is the recycling of polymeric waste materials. The present study has demonstrated the applicability of biotechnological principles in the desulfurization of rubber using shake flask and Warburg respirometric techniques. In terms of oxygen uptake and specific rate of oxygen uptake, it was found that the mixed culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans was more efficient in this process than the individual pu… more

Date: January 1, 1990

Creator: Torma, A.E. (EG and G Idaho, Inc., Idaho Falls, ID (USA)) & Raghavan, D. (Illinois Univ., Urbana, IL (USA). Dept. of Materials Science and Engineering)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanisms for cleavage and intergranular embrittlement in Fe

The mechanism of cleavage in bcc Fe has been investigated with electronic structure calculations and compared to similar calculations modeling cleavage in other bcc materials (Li, Nb, Mo). It has been found in the BCC materials we have studied that those known to undergo (100) cleavage show enhancement of the density of states (DOS) on the virtual surface layer as the material is strained to failure. Using total energy calculations it is shown that there is a point of inflection (corresponding … more

Date: January 1, 1987

Creator: Eberhart, M.E.; MacLaren, J.M. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Dept. of Materials Science and Engineering & Los Alamos National Lab., NM (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Atomic structures and compositions of internal interfaces

This research program addresses fundamental questions concerning the relationships between atomic structures and chemical compositions of metal/ceramic heterophase interfaces. The chemical composition profile across a Cu/MgO {l brace}111{r brace}-type heterophase interface, produced by the internal oxidation of a Cu(Mg) single phase alloy, is measured via atom-probe field-ion microscopy with a spatial resolution of 0.121 nm; this resolution is equal to the interplanar space of the {l brace}222{… more

Date: March 1, 1992

Creator: Seidman, D.N. (Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering) & Merkle, K.L. (Argonne National Lab., IL (United States))

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Atomic structures and compositions of interfaces

This research program focuses on an experimental study of the structure and chemistry of metal/metal oxide internal interfaces; the latter are mainly created, although not exclusively, by internal oxidation of binary or ternary metal alloys that are solid-solution phases prior to the internal oxidation treatment. The principal research tools are transmission electron microscopy (TEM), high resolution microscopy (HREM), analytical electron microscopy (AEM) and atom-probe field-ion microscopy (AP… more

Date: September 1, 1990

Creator: Seidman, D.N. (Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering) & Merkle, K.L. (Argonne National Lab., IL (United States))

Item Type: Report

Partner: UNT Libraries Government Documents Department

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XRD (x-ray diffraction) and HREM (high resolution electron microscopy) studies of nanocrystalline Cu and Pd

Consolidated powders of nanocrystalline Cu and Pd have been studied by x-ray diffraction (XRD) and high resolution electron microscopy (HREM) as part of an investigation of the mechanical behavior of nanocrystalline pure metals. XRD line broadening measurements were made to estimate grain size, qualitative grain size distribution and average long range strains in a number of samples. Mean grain sizes range from 4--60 nm and have qualitatively narrow grain size distributions. Long range lattice … more

Date: December 1, 1990

Creator: Nieman, G. W.; Weertman, J. R. (Northwestern Univ., Evanston, IL (USA). Dept. of Materials Science and Engineering) & Siegel, R. W. (Argonne National Lab., IL (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Tensile strength and creep resistance in nanocrystalline Cu, Pd and Ag

Measurements of tensile strength and creep resistance have been made on bulk samples of nanocrystalline Cu, Pd and Ag consolidated from powders by cold compaction. Samples of Cu-Cu{sub 2}O have also been tested. Yield strength for samples with mean grains sizes of 5-80 nm and bulk densities on the order of 95% of theoretical density are increased 2--5 times over that measured in pure, annealed samples of the same composition with micrometer grain sizes. Ductility in the nanocrystalline Cu has e… more

Date: December 1, 1990

Creator: Nieman, G. W.; Weertman, J. R. (Northwestern Univ., Evanston, IL (USA). Dept. of Materials Science and Engineering) & Siegel, R. W. (Argonne National Lab., IL (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

[UNT Research Park Master Plan]

A presentation containing plans for the University of North Texas Research Park campus, including photographs, logistics information, and floor plans.

Date: 2002-09-08~

Item Type: Presentation

Location: 33.254593 -97.152661

Partner: UNT Libraries Special Collections

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Diffuse scattering studies as a tool for characterizing the local order structure and for obtaining pairwise interaction energies

Diffuse scattering is a mature method for characterizing the local order structure of alloy systems. An extension of such structural investigations, for alloys at equilibrium, allows one to obtain pairwise interaction energies. Having experimental pairwise interaction energies for the various coordination shells offers one the potential for more realistic Monte Carlo modelling of alloy systems as they relax toward equilibrium. The diffuse scattering method and the recovery of the interaction en… more

Date: January 1, 1992

Creator: Epperson, J.E. (Argonne National Lab., IL (United States)); Chen, H. & Anderson, J.P. (Illinois Univ., Urbana, IL (United States). Dept. of Materials Science and Engineering)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Miniaturized disk-bend testing and microstructure of 3. 8 MeV Zr sup 3+ irradiated Zr sub 3 Al

The mechanical behavior of Zr{sub 3}Al irradiated with 3.8 MeV Zr{sup 3+} ions has been investigated using a miniaturized disk bend test (MDBT). The samples tested were 3 mm in diameter and either nominally 100 or 250 {mu}m thick. They were irradiated at 250{degree}C to peak doses varying from 0.0041 to 2 displacements per atom (dpa). The yield stresses, {sigma}{sub y}, of the thin specimens were independent of dose, within experimental error, and comparable to that of unirradiated Zr{sub 3}Al.… more

Date: January 1, 1990

Creator: Chen, F.C.; Ardell, A.J. (California Univ., Los Angeles, CA (USA). Dept. of Materials Science and Engineering) & Pedraza, D.F. (Oak Ridge National Lab., TN (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Microstructure and properties of alumina-whisker-reinforced tetragonal zirconia polycrystal matrix composites

With the increasing demand of today's technology, there is a growing need for high temperature materials with improved fracture toughness. Whisker-reinforced ceramic composites are materials with potentially high fracture toughness. Many whisker-matrix systems are possible, but the choices for toughened composites are limited by such considerations as chemical compatibility and thermal expansion mismatch. In view of the high fracture toughness of tetragonal zirconia polycrystals (TZP) matrix, m… more

Date: January 1, 1991

Creator: Roberts, J.M.; Singh, J.P. (Argonne National Lab., IL (USA)) & Scattergood, R.O. (North Carolina State Univ., Raleigh, NC (USA). Dept. of Materials Science and Engineering)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Ion mixing of semiconductor layered-structures

This research is a collaborative program between the University of California at San Diego and Cornell University to investigate the phenomenon of ion mixing in semiconductor layered structures. The research effort also involves interactions with Oak Ridge National Laboratory under the Surface Modification and Characterization Collaborative Research Center Program. During the current period of investigation, we investigated parameters that could affect ion-mixing rates in semiconductors. We fou… more

Date: January 1, 1991

Creator: Lau, S.S. (California Univ., San Diego, La Jolla, CA (United States)) & Mayer, J.W. (Cornell Univ., Ithaca, NY (United States). Dept. of Materials Science and Engineering)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Is K[sub 3]C[sub 60] a line phase

We present x-ray diffraction evidence that K[sub I]C[sub 60] with x as low as 1.6 exhibits phase-pure fcc structures over some temperature range. These results have implications for the equilibrium binary phase diagram, and for the possibility of testing the hypothesis that fullerene superconductors are doped Mott-Hubbard insulators.

Date: January 1, 1993

Creator: Zhu, Q.; Fischer, J.E. (Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering) & Cox, D.E. (Brookhaven National Lab., Upton, NY (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Atomic structures and compositions of internal interfaces. [Produced by internal oxidation of alloys]

This research program addresses fundamental questions concerning the relations between atomic structures and compositions of homophase and heterophase interfaces. Metal/ceramic heterophase interfaces are created via the process of internal oxidation of metallic alloys. The interfaces are studied via a combination of conventional transmission electron microscopy, high resolution electron microscopy, field-ion microscopy and atom probe microscopy. The latter technique is employed to chemically se… more

Date: May 10, 1993

Creator: Seidman, D.N. (Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering) & Merkle, K.L. (Argonne National Lab., IL (United States). Materials Science Div.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Dynamical simulation of dislocation microstructure

We report the development of a computer simulation technique to model the motion of a large number of mutually interacting dislocations under the influence of an applied stress. The dislocation motion is simulated using a method akin to molecular dynamics except that dislocation coordinates are employed instead of atomic coordinates. The formation of dislocation substructure is studied as a function of applied stress and density and the resulting spatial distribution of dislocations is analyzed… more

Date: January 1, 1989

Creator: Gulluglo, A.; Srolovitz, D.J.; LeSar, R.; Lomdahl, P.S. (Michigan Univ., Ann Arbor, MI (USA). Dept. of Materials Science and Engineering & Los Alamos National Lab., NM (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Modeling of transformation toughening in brittle materials

Results from modeling of transformation toughening in brittle materials using a discrete micromechanical model are presented. The material is represented as a two-dimensional triangular array of nodes connected by elastic springs. Microstructural effects are included by varying the spring parameters for the bulk, grain boundaries, and transforming particles. Using the width of the damage zone and the effective compliance (after the initial creation of the damage zone) as measures of fracture to… more

Date: January 24, 1992

Creator: LeSar, R.; Rollett, A.D. (Los Alamos National Lab., NM (United States)) & Srolovitz, D.J. (Michigan Univ., Ann Arbor, MI (United States). Dept. of Materials Science and Engineering)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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In-situ observations of high temperature surface processes on. alpha. -alumina bulk crystals

Reflection electron microscopy (REM) was applied to image in-situ the dynamic changes of atomic-height steps on the surfaces of {alpha}-alumina bulk crystals heated to high temperatures. Atomic diffusion, desorption and adsorption processes on cleaved {alpha}-alumina (012) surfaces were directly observed at temperatures of 1470 to 1670 K. The surface started to show visible structural changes at 1470--1520 K. The main surface process appears to be atomic desorption, which creates large, flat va… more

Date: January 1, 1990

Creator: Wang, Z.L. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Materials Science and Engineering) & Bentley, J. (Oak Ridge National Lab., TN (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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In situ characterization of interfacial and bulk properties of lithium polymer batteries using 4-probe DC techniques

The use of transient and steady-state 4-probe techniques for the evaluation of the limitations to performance in solid-state electrochemical devices is described. The application of sequential, bipolar square-wave current pulses to a solid polymer cell with two internal reference electrodes allows separation of the polarization behavior of the various components of the cell, and indicates the rate limiting processes in the cell. Careful design of the experimental cell and appropriate selection … more

Date: November 1, 1992

Creator: Liu, Meilin (Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering); Visco, S. J. & De Jonghe, L. C. (Lawrence Berkeley Lab., CA (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Flow behavior of Ti-24Al-11Nb at high strain rates

The deformation and crack initiation behavior of Ti-24Al-11Nb has been examined over a temperature range of 298 to 923 K and for strain rates from 10{sup {minus}4}/s to 10{sup 2}/s. Tests performed in compression indicate much lower strain hardening at 10{sup 2}/s than at either 10{sup {minus}1}/s or 10{sup {minus}4}/s at all temperatures. Associated with this behavior is the occurrence of non-uniform, localized deformation bands at 10{sup 2}/s. An analysis indicates that adiabatic deformation … more

Date: January 1, 1990

Creator: Harbison, L.S.; Koss, D.A. (Pennsylvania State Univ., University Park, PA (USA). Dept. of Materials Science and Engineering) & Bourcier, R.J. (Sandia National Labs., Albuquerque, NM (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Living in a Materials World: Materials Science Engineering Professional Development for K-12 Educators

Advances in materials science are fundamental to technological developments and have broad societal impacs. For example, a cellular phone is composed of a polymer case, liquid crystal displays, LEDs, silicon chips, Ni-Cd batteries, resistors, capacitors, speakers, microphones all of which have required advances in materials science to be compacted into a phone which is typically smaller than a deck of cards. Like many technological developments, cellular phones have become a ubiquitous part of … more

Date: June 1, 2011

Creator: Seifert, Anne & Nadelson, Louis

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Superconducting Super Collider silicon tracking subsystem research and development

The Alamos National Laboratory Mechanical Engineering and Electronics Division has been investigating silicon-based elementary particle tracking device technology as part of the Superconducting Super Collider-sponsored silicon subsystem collaboration. Structural, materials, and thermal issues have been addressed. This paper explores detector structural integrity and stability, including detailed finite element models of the silicon wafer support and predictive methods used in designing with adv… more

Date: December 1, 1990

Creator: Miller, W.O.; Thompson, T.C.; Ziock, H.J. (Los Alamos National Lab., NM (USA)) & Gamble, M.T. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Dept. of Materials Science and Engineering)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Low temperature OMCVD of thin rhodium films

Thin, highly reflective rhodium films with metal compositions greater than 98% (elemental weight percentage) have been deposited by chemical vapor deposition using Rh(allyl){sub 3} (allyl = {eta}{sup 3}-C{sub 3}H{sub 5}) in the presence of a hydrogen plasma. Uniform, crystalline films that adhere well to several types of substrates result from depositions at temperatures as low as 150{degrees}C. Depositions using H{sub 2} (no plasma), or an argon plasma yields material that is amorphous, contai… more

Date: January 1, 1992

Creator: Laia, J.R.; Sattelberger, A.P.; Smith, D.C. (Los Alamos National Lab., NM (United States)) & DeSantis, J.C. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Correlation between the elastic-shear-instability-mechanism and empirical criteria for irradiation-induced amorphization

In an attempt to correlate the shear instability mechanism with empirical criteria for irradiation-induced amorphization, shear moduli of an A{sub 3}B-type fcc crystal were calculated as a function of the chemical long range order parameter (S) using a Morse potential. The shear moduli were found to decrease with decreasing S. When the depth and the curvature of the A-B potential were changed while keeping the A-A and B-B potentials constant, the magnitude of the decrease in shear moduli is gre… more

Date: September 1, 1990

Creator: Koike, J. (Los Alamos National Lab., NM (USA)); Okamoto, P.R.; Rehn, L.E. (Argonne National Lab., IL (USA)) & Meshii, M. (Northwestern Univ., Evanston, IL (USA). Dept. of Materials Science and Engineering)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Impurity-defect complexes in hydrogenated amorphous silicon

The two most outstanding features observed for dopants in hydrogenated amorphous silicon (a-Si:H) -- a shift in the Fermi level accompanied by an increase in the defect density and an absence of degenerate doping -- have previously been postulated to stem from the formation of substitutional dopant-dangling bond complexes. Using first-principles self-consistent pseudopotential calculation in conjunction with a supercell model for the amorphous network and the ability of network relaxation from … more

Date: November 1, 1990

Creator: Yang, L.H. (Argonne National Lab., IL (USA)); Fong, C.Y. (California Univ., Davis, CA (USA). Dept. of Physics) & Nichols, C.S. (Cornell Univ., Ithaca, NY (USA). Dept. of Materials Science and Engineering)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ion mixing of semiconductor layered-structures

In the previous period of investigation, we have established the basic ion mixing (IM) characteristics for semiconductor layered structures, in that there is a temperature dependent and a temperature independent regime in ion-mixing of III-V semiconductor systems such as the InGaAs/InP and the AlGaAs/GaAs systems and the Ge/Si system. During the current period of investigation, we investigated parameters that could affect ion-mixing rates in semiconductors. We found that the use of shallow dopa… more

Date: January 1, 1992

Creator: Lau, S.S. (California Univ., San Diego, La Jolla, CA (United States). Dept. of Electrical and Computer Engineering); Mayer, J.W. & Hall, B. (Cornell Univ., Ithaca, NY (United States). Dept. of Materials Science and Engineering)

Item Type: Report

Partner: UNT Libraries Government Documents Department