Biological Monitoring Program for East Fork Poplar Creek (open access)

Biological Monitoring Program for East Fork Poplar Creek

In May 1985, a National Pollutant Discharge Elimination System (NPDES) permit was issued for the Oak Ridge Y-12 Plant. As a condition of the permit, a Biologicai Monitoring and Abatement Program (BMAP) was developed to demonstrate that the effluent limitations established for the Y-12 Plant protect the classified uses of the receiving stream (East Fork Poplar Creek; EFPC), in particular, the growth and propagation of aquatic life (Lear et al. 1989). A second objective of the BMAP is to document the ecological effects resulting from the implementation of a water pollution control program designed to eliminate direct discharges of wastewaters to EFPC and to minimize the inadvertent release of pollutants to the environment. Because of the compiex nature of the discharges to EFPC and the temporal and spatial variability in the composition of the discharges, a comprehensive, integrated approach to biological monitoring was developed. A new permit was issued to the Y-12 Plant on April 28, 1995 and became effective on July 1, 1995. Biological monitoring continues to be required under the new permit. The BMAP consists of four major tasks that reflect different but complementary approaches to evaluating the effects of the Y-12 Plant discharges on the aquatic integrity …
Date: October 15, 1998
Creator: Adams, S. M.; Christensen, S. W.; Greeley, M. S. Jr.; Hill, W. R.; Kszos, L. A.; McCarthy, J. F. et al.
Object Type: Report
System: The UNT Digital Library
Proton Decay Studies of the Light Lu, Tm and Ho Isotopes (open access)

Proton Decay Studies of the Light Lu, Tm and Ho Isotopes

A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {micro}sec. In this paper the authors present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu.
Date: October 15, 1998
Creator: Akovali, Y.; Batchelder, J. C.; Bingham, C. R.; Davinson, T.; Ginter, T. N.; Gross, C. J. et al.
Object Type: Article
System: The UNT Digital Library
Investigation of syngas interactions in alcohol synthesis catalyst (open access)

Investigation of syngas interactions in alcohol synthesis catalyst

The primary objectives of the project are to (a) synthesize, by controlled sequential and co-impregnation techniques, three distinct composition metal clusters (consisting of Cu-Co-Cr and Cu-Fe-Zn): rich in copper (Methanol selective), rich in ferromagnetic metal (Co or Fe-Hydrocarbon selective) and intermediate range (mixed alcohol catalysts); (b) investigate the changes in the magnetic character of the systems due to interaction with CO, through Zero-field Nuclear Magnetic Resonance (ZFNMR) study of cobalt and Magnetic character (saturation magnetization and coercive field) analysis of the composite catalyst of Vibrating Sample Magnetometry (VSM); (c) examine the changes in syngas adsorption character of the catalyst as the composition changes, by FTIR Spectroscopic analysis of CO stretching frequencies; (d) determine the nature and size of these intermetallic clusters by Scanning Electron Microscopy (SEM); and (e) perform catalytic runs on selected samples and analyze the correlations between the physical and chemical characteristics. The catalysts chosen have a greater promise for industrial application than the Rh and Mo based catalysts. Several groups preparing catalysts by synthetic routes have reported divergent results for activity and selectivity. Generally the research has followed an empirical path and less effort is devoted to analyze the mechanisms and the scientific basis. The primary intent …
Date: April 15, 1998
Creator: Akundi, M. A.
Object Type: Report
System: The UNT Digital Library
Dynamic Fiber Optic Sensors Under Intense Radioactive Environments (open access)

Dynamic Fiber Optic Sensors Under Intense Radioactive Environments

A liquid mercury target will be used as the neutron source for the proposed Spallation Neutron Source facility. This target is subjected to bombardment by short-pulse, high-energy proton beams. The intense thermal loads caused by interaction of the pulsed proton beam with the mercury create an enormous rate of temperature rise ({approximately}10{sup 7} K/s) during a very brief beam pulse ({approximately } 0.5 {micro}s). The resulting pressure waves in the mercury will interact with the walls of the mercury target and may lead to large stresses. To gain confidence in the mercury target design concept and to benchmark the computer design codes, we tested various electrical and optical sensors for measuring the transient strains on the walls of a mercury container and the pressures in the mercury. The sensors were attached on several sample mercury targets that were tested at various beam facilities: Oak Ridge Electron Linear Accelerator, Los Alamos Neutron Science Center-Weapons Neutron Research, and Brookhaven National Laboratory's Alternating Gradient Synchrotron. The effects of intense background radiation on measured signals for each sensor are described and discussed. Preliminary results of limited tests at these facilities indicate that the fiber optic sensors function well in this intense radiation environment, whereas …
Date: October 15, 1998
Creator: Allison, S. W.; Earl, D. D.; Haines, J. R. & Tsai, C. C.
Object Type: Article
System: The UNT Digital Library
A sparse superlinearly convergent SQP with applications to two-dimensional shape optimization. (open access)

A sparse superlinearly convergent SQP with applications to two-dimensional shape optimization.

Discretization of optimal shape design problems leads to very large nonlinear optimization problems. For attaining maximum computational efficiency, a sequential quadratic programming (SQP) algorithm should achieve superlinear convergence while preserving sparsity and convexity of the resulting quadratic programs. Most classical SQP approaches violate at least one of the requirements. We show that, for a very large class of optimization problems, one can design SQP algorithms that satisfy all these three requirements. The improvements in computational efficiency are demonstrated for a cam design problem.
Date: April 15, 1998
Creator: Anitescu, M.
Object Type: Article
System: The UNT Digital Library
Enzyme catalysts for a biotechnology-based chemical industry. Quarterly progress report, September 29--December 28, 1997 (open access)

Enzyme catalysts for a biotechnology-based chemical industry. Quarterly progress report, September 29--December 28, 1997

The goal of this research is to engineer enzymes to be efficient and economically attractive catalysts for the chemical industry. The author is attempting to demonstrate generally-applicable approaches to enzyme improvement as well as develop specific catalysts for potential industrial application. In this report attention is focused on random mutagenesis of pNB esterase -- improved activity and stability. The most thermostable esterases obtained by sequential random mutagenesis (6H7) and random mutagenesis plus recombination (6sF9) each contain 9 amino acid mutations and a number of silent mutations, relative to the wild-type sequence. Eight of the mutations are present in both genes, for a total of ten potentially adaptive mutations. Because several of these mutations occurred in the same generation, it is difficult to identify the mutations responsible for the increases in activity and stability. In order to aid in this identification, the thermostable genes were recombined with the wild-type gene, in hopes of removing neutral mutations. The gene from the first-generation variant, with five amino acid substitutions was also recombined with wild-type.
Date: January 15, 1998
Creator: Arnold, F.H.
Object Type: Report
System: The UNT Digital Library
Low-(18)O Silicic Magmas: Why Are They So Rare? (open access)

Low-(18)O Silicic Magmas: Why Are They So Rare?

LOW-180 silicic magmas are reported from only a small number of localities (e.g., Yellowstone and Iceland), yet petrologic evidence points to upper crustal assimilation coupled with fractional crystallization (AFC) during magma genesis for nearly all silicic magmas. The rarity of 10W-l `O magmas in intracontinental caldera settings is remarkable given the evidence of intense 10W-l*O meteoric hydrothermal alteration in the subvolcanic remnants of larger caldera systems. In the Platoro caldera complex, regional ignimbrites (150-1000 km3) have plagioclase 6180 values of 6.8 + 0.1%., whereas the Middle Tuff, a small-volume (est. 50-100 km3) post-caldera collapse pyroclastic sequence, has plagioclase 8]80 values between 5.5 and 6.8%o. On average, the plagioclase phenocrysts from the Middle Tuff are depleted by only 0.3%0 relative to those in the regional tuffs. At Yellowstone, small-volume post-caldera collapse intracaldera rhyolites are up to 5.5%o depleted relative to the regional ignimbrites. Two important differences between the Middle Tuff and the Yellowstone 10W-180 rhyolites elucidate the problem. Middle Tuff magmas reached water saturation and erupted explosively, whereas most of the 10W-l 80 Yellowstone rhyolites erupted effusively as domes or flows, and are nearly devoid of hydrous phenocrysts. Comparing the two eruptive types indicates that assimilation of 10W-180 material, combined with …
Date: October 15, 1998
Creator: Balsley, Steven D. & Gregory, Robert T.
Object Type: Article
System: The UNT Digital Library
Designs Studies of Low-Aspect Ratio Quasi-Omnigenous Stellarators (open access)

Designs Studies of Low-Aspect Ratio Quasi-Omnigenous Stellarators

Significant progress has been made in the development of new modest-size compact stellarator devices that could test optimization principles for the design of a more attractive reactor. These are 3 and 4 field period low-aspect-ratio quasi-omnigenous (QO) stellarators based on an optimization method that targets improved confinement, stability, ease of coil design, low-aspect-ratio, and low bootstrap current.
Date: October 15, 1998
Creator: Batchelor, D. B.; Carreras, B. A.; Hirshman, S. P.; Lynch, V. E.; Sanchez, R.; Spong, D. A. et al.
Object Type: Article
System: The UNT Digital Library
Comparison of Analytical and Experimental Effectiveness of Four-Row Plate-Fin-Tube Heat Exchangers with Water, R-22, and R-410A (open access)

Comparison of Analytical and Experimental Effectiveness of Four-Row Plate-Fin-Tube Heat Exchangers with Water, R-22, and R-410A

The analytical solutions of heat exchanger effectiveness for four-row crcmilow, cross-countertlow and cross-paralleltlow have been derived in the recent study. The main objective of this study is to investigate the etlkct of heat exchawger tlow conllguration on thermal performance with refrigerant mixtures. Difference of heat exchanger effectiveness for all flow arrangements relative to an analytical many-row solution has been analyzed. A comparison of four-row cross cou~ltet-ilow heat exchanger effectiveness between analytical solutions and experimental data with water, R-22, and R-4 10A is presented.
Date: November 15, 1998
Creator: Baxter, V. D.; Chen, T. D. & Conklin, J. C.
Object Type: Article
System: The UNT Digital Library
Decontamination of Radionuclides from Concrete During and After Thermal Treatment (open access)

Decontamination of Radionuclides from Concrete During and After Thermal Treatment

The objective was to clarify from the theoretical viewpoint the mechanical, diffusional, thermodynamic and electromagnetic aspects of the decontaminations problem, by means of developing a powerful computational model to evaluate the effect of a very rapid heating regime on the on the contaminated concrete walls or slabs. The practical objective was to assess the feasibility of the microwave heating scheme envisaged and determine its suitable parameters such as power and duration. This objective was complementary to, but separate from, the chemical and nuclear aspects of long-time processes that led to the contamination and various conceivable alternative methods of decontamination which were investigated by Dr. Brian Spalding of Oak Ridge National Laboratory, with whom the start-up phase of this project was coordinated.
Date: September 15, 1998
Creator: Bazant, Z. P.
Object Type: Report
System: The UNT Digital Library
An Efficient Molecular Dynamics Scheme for Predicting Dopant Implant Profiles in Semiconductors (open access)

An Efficient Molecular Dynamics Scheme for Predicting Dopant Implant Profiles in Semiconductors

The authors present a highly efficient molecular dynamics scheme for calculating the concentration profile of dopants implanted in group-IV alloy, and III-V zinc blende structure materials. The program incorporates methods for reducing computational overhead, plus a rare event algorithm to give statistical accuracy over several orders of magnitude change in the dopant concentration. The code uses a molecular dynamics (MD) model, instead of the binary collision approximation (BCA) used in implant simulators such as TRIM and Marlowe, to describe ion-target interactions. Atomic interactions are described by a combination of 'many-body' and screened Coulomb potentials. Inelastic energy loss is accounted for using a Firsov model, and electronic stopping is described by a Brandt-Kitagawa model which contains the single adjustable parameter for the entire scheme. Thus, the program is easily extensible to new ion-target combinations with the minimum of tuning, and is predictive over a wide range of implant energies and angles. The scheme is especially suited for calculating profiles due to low energy, large angle implants, and for situations where a predictive capability is required with the minimum of experimental validation. They give examples of using their code to calculate concentration profiles and 2D 'point response' profiles of dopants in crystalline …
Date: September 15, 1998
Creator: Beardmore, K.M. & Gronbech-Jensen, N.
Object Type: Article
System: The UNT Digital Library
Magnetic anisotropy and its microstructural origin in epitaxially grown SmCo thin films. (open access)

Magnetic anisotropy and its microstructural origin in epitaxially grown SmCo thin films.

Microstructural features and magnetic behavior of epitaxially grown SmCo thin films with very high in-plane anisotropy are presented. Transmission electron microscopy was used to characterize the microstructure while magnetic measurements were performed using dc and SQUID magnetometers. Two substrate orientations were studied, i.e., MgO(100)/Cr(100)/SmCo(11{bar 2}0) and MgO(110)/Cr(211)/SmCo(1{bar 1}00). In the former, the SmCo(11{bar 2}0) film shows a bicrystalline microstructure, whereas in the latter, a uniaxial one is observed. Both microstructure consist of grains with a mixture of SmCo{sub 3} , Sm{sub 2}Co{sub 7} and SmCo{sub 3} polytypoids. A deviation from the c-axes was observed in the in-plane anisotropy of the SmCo(11{bar 2}0) thin film. A strong exchange interaction between the grains would, in principle, explain the observed deviation. On the other hand, both SmCo(11{bar 2}0) and (1{bar 1}00) thin films show very high coercivity values with pinning-type characteristics. Possible coercivity mechanisms related to intergranular exchange interactions and local variation in magnetocrystalline anisotropy constants are discussed.
Date: April 15, 1998
Creator: Benaissa, M.
Object Type: Article
System: The UNT Digital Library
TAE Saturation of Alpha Particle Driven Instability in TFTR (open access)

TAE Saturation of Alpha Particle Driven Instability in TFTR

A nonlinear theory of kinetic instabilities near threshold [H.L. Berk, et al., Plasma Phys. Rep. 23, (1997) 842] is applied to calculate the saturation level of Toroidicity-induced Alfvén Eigenmodes (TAE) and be compared with the predictions of (delta)f method calculations [Y. Chen, Ph.D. Thesis, Princeton University, 1998]. Good agreement is observed between the predictions of both methods and the predicted saturation levels are comparable with experimentally measured amplitudes of the TAE oscillations in TFTR [D.J. Grove and D.M. Meade, Nucl. Fusion 25, (1985) 1167].
Date: September 15, 1998
Creator: Berk, H. L.; Chen, Y.; Gorelenkov, N. N. & White, R. B.
Object Type: Report
System: The UNT Digital Library
Cryogenic D-T fuel layers formed in 1mm spheres by beta-layering (open access)

Cryogenic D-T fuel layers formed in 1mm spheres by beta-layering

Solid D-T fuel smoothly layered on the interior of spherical capsules is required for all inertial confinement fusion ignition target designs. One process for forming these layers, beta-layering, has been studied in surrogate geometries such as open cylinders or tori to allow accurate characterization of the DT surfaces. We present the first results from beta layering in 1 mm spherical containers, such as will be used in upcoming Omega experiments. These results are also directly relevant to ignition capsules for the National Ignition Facility. We find that layers can form with roughness as small as 1.2 microns rms, and that results are strongly dependent upon freezing rate as well as layer thickness.
Date: October 15, 1998
Creator: Bernat, T. P.; Burmann, J.; Collins, G. W.; Kozioziemski, B.; Mapoles, E. R.; Pipes, J. et al.
Object Type: Article
System: The UNT Digital Library
In-Situ Tritium Beta Detector (open access)

In-Situ Tritium Beta Detector

The objectives of this three-phase project were to design, develop, and demonstrate a monitoring system capable of detecting and quantifying tritium in situ in ground and surface waters, and in water from effluent lines prior to discharge into public waterways. The tritium detection system design is based on measurement of the low energy beta radiation from the radioactive decay of tritium using a special form of scintillating optical fiber directly in contact with the water to be measured. The system consists of the immersible sensor module containing the optical fiber, and an electronics package, connected by an umbilical cable. The system can be permanently installed for routine water monitoring in wells or process or effluent lines, or can be moved from one location to another for survey use. The electronics will read out tritium activity directly in units of pico Curies per liter, with straightforward calibration. In Phase 1 of the project, we characterized the sensitivity of fluor-doped plastic optical fiber to tritium beta radiation. In addition, we characterized the performance of photomultiplier tubes needed for the system. In parallel with this work, we defined the functional requirements, target specifications, and system configuration for an in situ tritium beta detector …
Date: April 15, 1998
Creator: Berthold, J. W. & Jeffers, L. A.
Object Type: Report
System: The UNT Digital Library
Phase 1 Final Report for In-Situ Tritium Beta Detector (open access)

Phase 1 Final Report for In-Situ Tritium Beta Detector

The objectives of this three-phase project were to design, develop, and demonstrate a monitoring system capable of detecting and quantifying tritium in situ in ground and surface waters, and in water from effluent lines prior to discharge into public waterways. The tritium detection system design is based on measurement of the low energy beta radiation from the radioactive decay of tritium using a special form of scintillating optical fiber directly in contact with the water to be measured. The system consists of the immersible sensor module containing the optical fiber, and an electronics package, connected by an umbilical cable. The system can be permanently installed for routine water monitoring in wells or process or effluent lines, or can be moved from one location to another for survey use. The electronics will read out tritium activity directly in units of pico Curies per liter, with straightforward calibration. In Phase 1 of the project, we characterized the sensitivity of fluor-doped plastic optical fiber to tritium beta radiation. In addition, we characterized the performance of photomultiplier tubes needed for the system. In parallel with this work, we defined the functional requirements, target specifications, and system configuration for an in situ tritium beta detector …
Date: April 15, 1998
Creator: Berthold, J. W. & Jeffers, L. A.
Object Type: Report
System: The UNT Digital Library
Numerical experiments on the probability of seepage intounderground openings in heterogeneous fractured rock (open access)

Numerical experiments on the probability of seepage intounderground openings in heterogeneous fractured rock

An important issue for the performance of underground nuclear waste repositories is the rate of seepage into the waste emplacement drifts. A prediction of this rate is particularly complicated for the potential repository site at Yucca Mountain, Nevada, because it is located in thick, unsaturated, fractured tuff formations. Underground opening in unsaturated media might act as capillary barriers, diverting water around them. In the present work, they study the potential rate of seepage into drifts as a function of the percolation flux at Yucca Mountain, based on a stochastic model of the fractured rock mass in the drift vicinity. A variety of flow scenarios are considered, assuming present-day and possible future climate conditions. They show that the heterogeneity in the flow domain is a key factor controlling seepage rates, since it causes channelized flow and local ponding in the unsaturated flow field.
Date: April 15, 1998
Creator: Birkholzer, J.; Li, G.; Tsang, C. F. & Tsang, Y.
Object Type: Report
System: The UNT Digital Library
[Support of theoretical high energy physics research at the Supercomputer Computations Research Institute]. Final report, September 30, 1992--July 31, 1997 (open access)

[Support of theoretical high energy physics research at the Supercomputer Computations Research Institute]. Final report, September 30, 1992--July 31, 1997

The research primarily involved lattice field theory simulations such as Quantum Chromodynamics (QCD) and the Standard Model of electroweak interactions. Among the works completed by the members of the lattice group and their outside collaborators in QCD simulations are extensive hadronic spectrum computations with both Wilson and staggered fermions, and calculations of hadronic matrix elements and wavefunctions. Studies of the QCD {beta} function with two flavors of Wilson fermions, and the study of a possible flavor-parity breaking phase in QCD with two flavors of Wilson fermions have been completed. Studies of the finite temperature behavior of QCD have also been a major activity within the group. Studies of non-relativistic QCD, both for heavy-heavy mesons and for the heavy quark in heavy-light mesons have been done. Combining large N analytic computations within the Higgs sector of the standard model and numerical simulations at N = 4 have yielded a computation of the upper bound of the mass of the Higgs particle, as well as the energy scale above which deviations from the Standard Model may be expected. A major research topic during the second half of the grant period was the study of improved lattice actions, designed to diminish finite lattice …
Date: December 15, 1998
Creator: Bitar, Khalil M.; Edwards, Robert G.; Heller, Urs M. & Kennedy, Anthony D.
Object Type: Report
System: The UNT Digital Library
MCFC component development at ANL. (open access)

MCFC component development at ANL.

Argonne National Laboratory is developing advanced cathode and electrolyte components for the molten carbonate fuel cell (MCFC). Working in support of the MCFC developers, the goal of this effort is to extend the life of the MCFC cell and to improve its performance.
Date: September 15, 1998
Creator: Bloom, I.
Object Type: Article
System: The UNT Digital Library
Design review report: 200 East upgrades for Project W-314, tank farm restoration and safe operations (open access)

Design review report: 200 East upgrades for Project W-314, tank farm restoration and safe operations

This Design Review Report (DRR) documents the contractor design verification methodology and records associated with project W-314`s 200 East (200E) Upgrades design package. The DRR includes the documented comments and their respective dispositions for this design. Acceptance of the comment dispositions and closure of the review comments is indicated by the signatures of the participating reviewers. Project W-314 is a project within the Tank Waste Remediation System (TWRS) Tank Waste Retrieval Program. This project provides capital upgrades for the existing Hanford tank farm waste transfer, instrumentation, ventilation, and electrical infrastructure systems. To support established TWRS programmatic objectives, the project is organized into two distinct phases. The initial focus of the project (i.e., Phase 1) is on waste transfer system upgrades needed to support the TWRS Privatization waste feed delivery system. Phase 2 of the project will provide upgrades to support resolution of regulatory compliance issues, improve tank infrastructure reliability, and reduce overall plant operating/maintenance costs. Within Phase 1 of the W-314 project, the waste transfer system upgrades are further broken down into six major packages which align with the project`s work breakdown structure. Each of these six sub-elements includes the design, procurement, and construction activities necessary to accomplish the specific …
Date: April 15, 1998
Creator: Boes, K.A.
Object Type: Report
System: The UNT Digital Library
Light Machines Operator Performance Support System (open access)

Light Machines Operator Performance Support System

The objective of this project was to create a multimedia operator performance support system (OPSS) shell that would provide a framework for delivering appropriate information to the student/novice machine tool user just when needed and in the most appropriate form. In addition, the program was designed so that it could be expanded and further developed by Light Machines personnel. The expertise of AlliedSignal Federal Manufacturing and Technologies (ASFM and T) in the areas of performance support system design and multimedia creation was employed to create the most user-friendly graphical user interface (GUI) while providing access to key topical areas. Light Machines provided a subject matter expert from their technical services group in order to provide the needed information for structuring the OPSS shell. They also provided a Benchman VMC 4000 machine tool at the ASFM and T New Mexico location as well as specific instruction on the safe and effective use of that machine tool.
Date: June 15, 1998
Creator: Bohley, M.C.
Object Type: Report
System: The UNT Digital Library
Application of system simulation for engineering the technical computing environment of the Lawrence Livermore National Laboratorie (open access)

Application of system simulation for engineering the technical computing environment of the Lawrence Livermore National Laboratorie

This report summarizes an investigation performed by Lawrence Livermore National Laboratory� s (LLNL) Scientific Computing & Communications Department (SCCD) and the Garland Location of Raytheon Systems Company (RSC) from April through August.1998. The study assessed the applicability and benefits of utilizing System Simulation in architecting and deploying technical computing assets at LLNL, particularly in support of the ASCI program and associated scientific computing needs. The recommendations and other reported findings reflect the consensus of the investigation team. The investigation showed that there are potential benefits to performing component level simulation within SCCD in support of the ASCI program. To illustrate this, a modeling exercise was conducted by the study team that generated results consistent with measured operational performance. This activity demonstrated that a relatively modest effort could improve the toolset for making architectural trades and improving levels of understanding for managing operational practices. This capability to evaluate architectural trades was demonstrated by evaluating some of the productivity impacts of changing one of the design parameters of an existing file transfer system. The use of system simulation should be tailored to the local context of resource requirements/limitations, technology plans/processes/issues, design and deployment schedule, and organizational factors. In taking these matters into …
Date: September 15, 1998
Creator: Boyd, V.; Edmunds, T.; Minuzzo, K.; Powell, E. & Roche, L.
Object Type: Report
System: The UNT Digital Library
Evaluation of Reservoir Wettability and its Effect on Oil Recovery. (open access)

Evaluation of Reservoir Wettability and its Effect on Oil Recovery.

We report on the first year of the project, `Evaluation of Reservoir Wettability and its Effect on Oil Recovery.` The objectives of this five-year project are (1) to achieve improved understanding of the surface and interfacial properties of crude oils and their interactions with mineral surfaces, (2) to apply the results of surface studies to improve predictions of oil production from laboratory measurements, and (3) to use the results of this research to recommend ways to improve oil recovery by waterflooding. During the first year of this project we have focused on understanding the interactions between crude oils and mineral surfaces that establish wetting in porous media. As background, mixed-wetting and our current understanding of the influence of stable and unstable brine films are reviewed. The components that are likely to adsorb and alter wetting are divided into two groups: those containing polar heteroatoms, especially organic acids and bases; and the asphaltenes, large molecules that aggregate in solution and precipitate upon addition of n-pentane and similar agents. Finally, the test procedures used to assess the extent of wetting alteration-tests of adhesion and adsorption on smooth surfaces and spontaneous imbibition into porous media are introduced. In Part 1, we report on …
Date: January 15, 1998
Creator: Buckley, J. S.
Object Type: Report
System: The UNT Digital Library
Atomic Structure and Properties of Extended Defects in Silicon (open access)

Atomic Structure and Properties of Extended Defects in Silicon

The Z-contrast technique represents a new approach to high-resolution electron microscopy allowing for the first time incoherent imaging of materials on the atomic scale. The key advantages of the technique, an intrinsically higher resolution limit and directly interpretable, compositionally sensitive imaging, allow a new level of insight into the atomic configurations of extended defects in silicon. This experimental technique has been combined with theoretical calculations (a combination of first principles, tight binding, and classical methods) to extend this level of insight by obtaining the energetic and electronic structure of the defects.
Date: October 15, 1998
Creator: Buczko, R.; Chisholm, M.F.; Kaplan, T.; Maiti, A.; Mostoller, M.; Pantelides, S.T. et al.
Object Type: Article
System: The UNT Digital Library