Electron energies in metals (open access)

Electron energies in metals

The modern era of electron-electron interactions began a decade ago. Plummer's group initiated a program of using angular resolved photoemission to examine the band structure of the simple metals. Beginning with aluminum, and carrying on to sodium and potassium, they always found that the occupied energy bands were much narrower than expected. For example, the compressed energy bands for metallic potassium suggest a band effective mass of m* = 1.33m{sub e}. This should be compared to the band mass found from optical conductivity m*/m{sub e} = 1.01 {plus minus} 0.01. The discrepancy between these results is startling. It was this great difference which started my group doing calculations. Our program was two-fold. On one hand, we reanalyzed the experimental data, in order to see if Plummer's result was an experimental artifact. On the other hand, we completely redid the electron-electron self-energy calculations for simple metals, using the most modern choices of local-field corrections and vertex corrections. Our results will be reported in these lectures. They can be summarized as following: Our calculations give the same effective masses as the older calculations, so the theory is relatively unchanged; Our analysis of the experiments suggests that the recent measurements of band narrowing …
Date: July 10, 1991
Creator: Mahan, G.D. (Oak Ridge National Lab., TN (United States) Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy)
Object Type: Article
System: The UNT Digital Library
Investigation of PACVD protective coating processes using advanced diagnostics techniques (open access)

Investigation of PACVD protective coating processes using advanced diagnostics techniques

Coherent anti-Stokes Raman Spectroscopy (CARS) is used to study the plasma-assisted chemical vapor deposition (PACVD) of TiB{sub 2}. CARS is applied to the dominent species in an inductively coupled B{sub 2}H{sub 6}/Ar rf plasma. Axial concentration profiles of diborane and hydrogen are probed in the plasma. A five-step mechanism is developed. Photochemical initiation of the chemical reaction is considered. 16 refs, 5 figs.(DLC)
Date: July 10, 1992
Creator: Roman, W.C.
Object Type: Article
System: The UNT Digital Library
The CSMS (Configurable Seismic Monitoring System) Poorboy deployment: Seismic recording in Pinedale, Wyoming, of the Bullion NTS (Nevada Test Site) nuclear test under the verification provisions of the new TTBT protocol (open access)

The CSMS (Configurable Seismic Monitoring System) Poorboy deployment: Seismic recording in Pinedale, Wyoming, of the Bullion NTS (Nevada Test Site) nuclear test under the verification provisions of the new TTBT protocol

The Configurable Seismic Monitoring System (CSMS), developed at the Lawrence Livermore National Laboratory (LLNL) was deployed in a 13-m deep vault on the AFTAC facility at Pinedale, Wyoming to record the Bullion nuclear test. The purpose of the exercise was to meet all provisions of the new TTBT protocol on in-country seismic recording at a Designated Seismic Station (DSS). The CSMS successfully recorded the Bullion event consistent with and meeting all requirements in the new treaty protocol. In addition, desirable seismic system features not specified in the treaty protocol were determined; treaty protocol ambiguities were identified, and useful background noise recordings at the Pinedale site were obtained. 10 figs.
Date: July 10, 1990
Creator: Harben, P. E.; Rock, D. W. & Carlson, R. C.
Object Type: Report
System: The UNT Digital Library
Nuclear studies with intermediate energy probes. [Dept. of Physics, Univ. of Virginia] (open access)

Nuclear studies with intermediate energy probes. [Dept. of Physics, Univ. of Virginia]

Data from measurements at NIKHEF-K of the electro-production of neutral pions from the proton were completely analyzed and axe about to be submitted for publication. These results represent the first precise measurement of this fundamental process in the threshold region. The results are completely consistent with calculations based upon the Low Energy Theorems. Results from studies of a gas jet target in the electron storage ring of the Saskatchewan Accelerator Laboratory (SAL) have been fully analyzed and are being prepared for publication. An Internal Target Development Facility (ITDF), established at NIKHEF-K in a collaborative effort for the purpose of developing higher density gas jet targets suitable for use in electron rings, is operational. Diagnostic techniques are being evaluated in preparation for evaluating jet technology options. Our study of the calcium isotopes ([sup 42]C and [sup 44]C) is nearing completion. Both the electron and proton scattering data have been completely analyzed. Consistent proton and neutron transition densities have been extracted, and are being compared to corresponding results from pion scattering. Preparations for ([gamma],[pi][sup [minus]]) measurements at SAL have been completed, and data taking is about to commence.
Date: July 10, 1992
Creator: Norum, B.E.
Object Type: Report
System: The UNT Digital Library
Roles of additives and surface control in slurry atomization (open access)

Roles of additives and surface control in slurry atomization

Airblast atomization of micronized coal water slurry is carried out using twin-fluid jet atomizers of various distributor designs. Drop size and size distribution are measured using the laser diffraction technique. We found that the atomized drop sizes of micronized coal water slurries substantially decrease as the atomizing air pressure exceeds a threshold value. We also found that the atomized drop size, represented by the mass median diameter (MMD) can be described by the wave mechanism-based models in terms of three non-dimensional groups, namely, slurry-to-air mass ratio, the Weber number, and the Ohnesorge number. 11 refs.
Date: July 10, 1990
Creator: Tsai, S.C.
Object Type: Report
System: The UNT Digital Library
Refining of fossil resin flotation concentrate from Western coal. Second quarterly final report, April 1, 1993--June 30, 1993 (open access)

Refining of fossil resin flotation concentrate from Western coal. Second quarterly final report, April 1, 1993--June 30, 1993

Ultimate analysis was conducted for the fossil resin concentrate and results obtained are given in Table 2. Based on these results and other results from spectroscopic analysis it appears that the fossil resin from the Wasatch Plateau coal field consists mainly of aliphatic components and partially aromatized multicyclic terpenoids with a few oxygen functional groups. As compared with the parent high volatile bituminous coal, the resin has higher hydrogen and carbon content, low oxygen, nitrogen, and sulfur contents, and relatively low aromaticity. The values of the acid number and iodine number indicate that the fossil resins from the Wasatch Plateau coal field contain only a modest amount of oxygen functional groups and unsaturated carbon-carbon double-bonds in their molecular structures. Fossil resin is a complex mixture of sesquiterpenoids and the solubility of these resin compounds depends on the type of solvent used. The determination of the extractable resin content in the resin concentrate by different solvents provides an important control variable for selective solvent refining and purification. The data generated during preliminary solvent extraction tests are especially important for process design, control of the refined resin quality and prediction of the refined resin products. In this work, the extractable resin content …
Date: July 10, 1993
Creator: Jensen, G. F. & Miller, J. D.
Object Type: Report
System: The UNT Digital Library
Increased IMP dehydrogenase gene expression in solid tumor tissues and tumor cell lines (open access)

Increased IMP dehydrogenase gene expression in solid tumor tissues and tumor cell lines

IMP dehydrogenase, a regulatory enzyme of guanine nucleotide biosynthesis, may play a role in cell proliferation and malignancy. To assess this possibility, we examined IMP dehydrogenase expression in a series of human solid tumor tissues and tumor cell lines in comparison with their normal counterparts. Increased IMP dehydrogenase gene expression was observed in brain tumors relative to normal brain tissue and in sarcoma cells relative to normal fibroblasts. Similarly, in several B- and T-lymphoid leukemia cell lines, elevated levels of IMP dehydrogenase mRNA and cellular enzyme were observed in comparison with the levels in peripheral blood lymphocytes. These results are consistent with an association between increased IMP dehydrogenase expression and either enhanced cell proliferation or malignant transformation.
Date: July 10, 1992
Creator: Collart, F. R.; Chubb, C. B.; Mirkin, B. L. & Huberman, E.
Object Type: Report
System: The UNT Digital Library
Enhanced oil recovery utilizing high-angle wells in the Frontier Formation, Badger Basin Field, Park County, Wyoming. Quarterly technical progress report, 1 March 1993--30 June 1993 (open access)

Enhanced oil recovery utilizing high-angle wells in the Frontier Formation, Badger Basin Field, Park County, Wyoming. Quarterly technical progress report, 1 March 1993--30 June 1993

Sierra Energy Company`s targeted goals during the third quarter of this Cooperative Agreement included the following objectives from the Statement of Work: in Phase 2A, completion of subtask 2.1.2--acquire best possible field data in the 3-D seismic program; and initiation of Subtask 2.1.3--process acquired 3-D seismic data. Technical progress is described for these tasks.
Date: July 10, 1993
Creator: Fortmann, R. G. & Walker, J. P.
Object Type: Report
System: The UNT Digital Library
D0 Silicon Upgrade: End Calorimeter Transfer Bridge Modification (open access)

D0 Silicon Upgrade: End Calorimeter Transfer Bridge Modification

During the assembly of major components into the D0 Detector, a transfer bridge was required to move the North-End Calorimeter from the clean room,over the cable bridge and onto the north sidewalk of the assembly hall. This experiment is now at the beginning stages of the next phase, namely the upgrade of this Detector for future physics research. A major piece of this upgrade is the installation of a solenoid magnet into the Central Calorimeter. In order to accomplish this, the South End Calorimeter has to be removed from the detector and the North End Calorimeter must be moved an additional 20-inch from its nominal open position (total 60-inch movement). The South End Calorimeter will be removed from the detector using the equipment designed for its installation. The calorimeter will be staged on the south sidewalk during the installation of the solenoid magnet and the central tracking systems. The North End Calorimeter is moved 60-inch to give more space between calorimeters during magnet, tracker and cable installation work. This movement will allow the calorimeter to remain coupled to the cryo system. However, this movement requires an extension be added to the center beam. This extension will support the rear wheels …
Date: July 10, 1996
Creator: Stredde, H.J.
Object Type: Report
System: The UNT Digital Library
Chemical and thermal stability of refrigerant-lubricant mixtures with metals (open access)

Chemical and thermal stability of refrigerant-lubricant mixtures with metals

This report presents completed sealed tube stability test results for the following eight refrigerant/lubricant mixtures: R-22/mineral oil; R-124/alkylbenzene; R-134a/pentaerythritol (PE) ester (mixed acid); R- 134a/PE (branched acid); R-134a/ PE (100 cSt viscosity); R- 142b/alkylbenzene; R-143a/ PE (branched acid); R-152a/alkylbenzene. Partial results are shown for an additional eight refrigerant-lubricant mixtures. Though work is in progress, no data are available at this point in time for the five remaining test mixtures. Reported are: visual observations on aged sealed tubes, gas chromatographic analyses on the vapor phase contents of the tubes, chloride ion contents of HCFC containing mixtures or fluoride ion contents of HFC mixtures, and total acid number values and infrared analysis results for mixtures containing ester lubricants.
Date: July 10, 1992
Creator: Huttenlocher, D. F.
Object Type: Report
System: The UNT Digital Library
Design, Analysis, and Spacecraft Integration of RTGs for CRAF and Cassini Missions (open access)

Design, Analysis, and Spacecraft Integration of RTGs for CRAF and Cassini Missions

This report consists of two parts. Part 1 describes the development of novel analytical methods needed to predict the BOM performance and the subsequent performance degradation of the mutually obstructed RTGs for the CRAF and Cassini missions. Part II applies those methods to the two missions, presents the resultant predictions, and discusses their programmatic implications.; The results indicate that JPL's original power demand goals could have been met with two standard GPHS RTGs for each mission. However, JPL subsequently raised both the power demand profile and the duration for both missions, to the point where two standard RTGs could no longer provide the desired power margin. Each mission can be satisfied by adding a third RTG, and in the case of the Cassini mission the use of three RTGs appears to be unavoidable. In the case of the CRAF mission, there appears to be a possibility that modest modifications of the RTGs' design and/or operating scheme and meet the missions' power demand without the addition of a third RTG. The potential saving in cost and schedule pressure prompted Fairchild to undertake a study of various obvious and not-so-obvious stratagems, either singly or in combination, to determine whether they would make …
Date: July 10, 1991
Creator: Schock, Alfred; Or, Chuen T & Noravian, Heros
Object Type: Report
System: The UNT Digital Library
Development and testing of industrial scale, coal fired combustion system, Phase 3. Second quarterly technical progress report, April 1, 1992--June 30, 1992 (open access)

Development and testing of industrial scale, coal fired combustion system, Phase 3. Second quarterly technical progress report, April 1, 1992--June 30, 1992

In the second quarter of calendar year 1992, work continued on Task 1.1. ``DESIGN MODIFICATIONS TO THE 20 MMBTU/HR AIR COOLED COMBUSTOR AND BOILER COMPONENTS``. This consisted of specifying and designing the changes needed to prepare the 20 MMBtu/hr air cooled combustor at the Tampella boiler house site in Williamsport, PA. In depth review of the technical status of the combustor showed that no major design changes were necessary in order to implement the effort of task 2 testing and part of the task 3 testing. Among the major planned changes eliminated were replacement of the inlet swirl air flow section of the combustor. The major changes undertaken were to improve the coal and sorbent injection into the combustor; refurbishing various components and controls systems such as the stack particle scrubber and temperature probes; automating key elements of the combustor, such as the slag tap, upgrading the computer control and automatic data acquisition; and upgrading the long duration capability of the exit nozzle. To support this effort advanced analytical modeling was used to provide guidance for the design changes. A multi-dimensional computer code was used to analyze the combustor performance for different combustor stoichiometries and geometry. A heat transfer analysis …
Date: July 10, 1992
Creator: Zauderer, B.
Object Type: Report
System: The UNT Digital Library
Programming Robots with Associative Memories (open access)

Programming Robots with Associative Memories

Today, there are several drawbacks that impede the necessary and much needed use of robot learning techniques in real applications. First, the time needed to achieve the synthesis of any behavior is prohibitive. Second, the robot behavior during the learning phase is � by definition � bad, it may even be dangerous. Third, except within the lazy learning approach, a new behavior implies a new learning phase. We propose in this paper to use self-organizing maps to encode the non explicit model of the robot-world interaction sampled by the lazy memory, and then generate a robot behavior by means of situations to be achieved, i.e., points on the self-organizing maps. Any behavior can instantaneously be synthesized by the definition of a goal situation. Its performance will be minimal (not evidently bad) and will improve by the mere repetition of the behavior.
Date: July 10, 1999
Creator: Touzet, C.
Object Type: Article
System: The UNT Digital Library
Beam Profile Measurement at 30 GeV Using Optical Transition Radiation (open access)

Beam Profile Measurement at 30 GeV Using Optical Transition Radiation

We present results of measurements of spot size and angular divergence of a 30 GeV electron beam through use of optical transition radiation (OTR). The OTR near field pattern and far field distribution are measured as a function of beam spot size and divergence at wavelengths of 441, 532, and 800 nm, for both the single and double foil configurations. Electron beam spot sizes of 50 {micro}m rms have been resolved, demonstrating the utility of OTR for measurement of small beam spot sizes of high energy (30 GeV) electron beams. Two-foil interference was clearly observed and utilized electron beam angular divergences of {approximately} 100 {micro}rad.
Date: July 10, 1999
Creator: Whittum, David H
Object Type: Report
System: The UNT Digital Library
Optical scatter as a diagnostic tool for studying bulk defects which cause laser damage in conventional and rapid growth KP and DKDP (open access)

Optical scatter as a diagnostic tool for studying bulk defects which cause laser damage in conventional and rapid growth KP and DKDP

Single crystals of KH{sub 2}PO{sub 4} (KDP) and (D{sub x}H{sub 1-x}){sub 2}PO{sub 4} (DKDP) will be used for frequency conversion and as part of a large aperture optical switch in the proposed National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL). These crystals must have good optical properties and high laser damage thresholds. Currently these crystals have a lower laser damage threshold than other optical materials in the laser chain which has forced designers to limit the output fluence of the NIF in order to avoid damaging the crystals. Furthermore, while more efficient frequency conversion schemes are being explored both theoretically and experimentally, the advantages of these schemes can not be fully realized unless the damage thresholds of the conversion crystals are increased. Over the past decade, LLNL has generated an extensive data base on the laser damage in KDP and DKDP crystals both at the first and third harmonics of Nd-YAG. While the damage thresholds of these crystals have increased over this time period due, in part, to better filtration of the growth solution, the damage thresholds of the best crystals are still far below what is expected from theoretical limits calculated from the band structure of …
Date: July 10, 1995
Creator: Woods, B.; Runkel, M. & Yan, M.
Object Type: Article
System: The UNT Digital Library
Advanced cell technology for high performance Li-A1/FeS{sub 2} secondary batteries. (open access)

Advanced cell technology for high performance Li-A1/FeS{sub 2} secondary batteries.

In early 1993. Argonne National Laboratory (ANL) initiated a major R and D effort to develop bipolar Li-Al/LiCl-LiBr-KBr/FeS{sub 2} batteries for electric vehicles, targeting the USABC Long-Term Goals. Significant advancements were achieved in the areas of (i) chemical purity, (ii) electrode and electrolyte additives, and (iii) peripheral seals. It was determined that key chemical constituents contained undesirable impurities. ANL developed new chemical processes for preparing Li{sub 2}S, FeS, and CoS{sub 2} that were >98.5% pure. We evaluated a large variety of electrode and electrolyte additives for reducing cell area specific impedance (ASI). Candidate positive electrode additives offered increased electronic conductivity, enhanced reaction kinetics, and/or improved porous electrode morphology. CoS{sub 2}, CuFeS{sub 2}, MgO, and graphite (fibers) were identified as the most beneficial impedance-reducing positive electrode additives. Although electronically conductive carbon and graphite additives produced measurable ASI reductions in the negative electrode, they degraded its structural integrity and were deemed impractical. Lil and LiF were identified as beneficial electrolyte additives, that enhance positive electrode kinetics. ANL refined its baseline metal/ceramic peripheral seal and increased its strength by a factor of three (achieving a safety factor >10). In parallel, ANL developed a high-strength advanced metal/ceramic seal that offers appreciable cost reductions.
Date: July 10, 1998
Creator: Henriksen, G. L.
Object Type: Article
System: The UNT Digital Library
A Kinetic-fluid Model (open access)

A Kinetic-fluid Model

A nonlinear kinetic-fluid model for high-beta plasmas with multiple ion species which can be applied to multiscale phenomena is presented. The model embeds important kinetic effects due to finite ion Larmor radius (FLR), wave-particle resonances, magnetic particle trapping, etc. in the framework of simple fluid descriptions. When further restricting to low frequency phenomena with frequencies less than the ion cyclotron frequency the kinetic-fluid model takes a simpler form in which the fluid equations of multiple ion species collapse into single-fluid density and momentum equations and a low frequency generalized Ohm's law. The kinetic effects are introduced via plasma pressure tensors for ions and electrons which are computed from particle distribution functions that are governed by the Vlasov equation or simplified plasma dynamics equations such as the gyrokinetic equation. The ion FLR effects provide a finite parallel electric field, a perpendicular velocity that modifies the ExB drift, and a gyroviscosity tensor, all of which are neglected in the usual one-fluid MHD description. Eigenmode equations are derived which include magnetosphere-ionosphere coupling effects for low frequency waves (e.g., kinetic/inertial Alfven waves and ballooning-mirror instabilities).
Date: July 10, 1998
Creator: Cheng, C. Z. & Johnson, Jay R.
Object Type: Report
System: The UNT Digital Library
Electrostatic comb drive for vertical actuation (open access)

Electrostatic comb drive for vertical actuation

The electrostatic comb finger drive has become an integral design for microsensor and microactuator applications. This paper reports on utilizing the levitation effect of comb fingers to design vertical-to-the-substrate actuation for interferometric applications. For typical polysilicon comb drives with 2 {micro}m gaps between the stationary and moving fingers, as well as between the microstructures and the substrate, the equilibrium position is nominally 1-2 {micro}m above the stationary comb fingers. This distance is ideal for many phase shifting interferometric applications. Theoretical calculations of the vertical actuation characteristics are compared with the experimental results, and a general design guideline is derived from these results. The suspension flexure stiffnesses, gravity forces, squeeze film damping, and comb finger thicknesses are parameters investigated which affect the displacement curve of the vertical microactuator. By designing a parallel plate capacitor between the suspended mass and the substrate, in situ position sensing can be used to control the vertical movement, providing a total feedback-controlled system. Fundamentals of various capacitive position sensing techniques are discussed. Experimental verification is carried out by a Zygo distance measurement interferometer.
Date: July 10, 1997
Creator: Lee, A. P., LLNL
Object Type: Article
System: The UNT Digital Library
Mechanisms and enhancement of flame stabilization. [Progress report] (open access)

Mechanisms and enhancement of flame stabilization. [Progress report]

None
Date: July 10, 1990
Creator: Law, C. K.
Object Type: Report
System: The UNT Digital Library
Nuclear studies with intermediate energy probes. Annual performance report (open access)

Nuclear studies with intermediate energy probes. Annual performance report

Data from measurements at NIKHEF-K of the electro-production of neutral pions from the proton were completely analyzed and axe about to be submitted for publication. These results represent the first precise measurement of this fundamental process in the threshold region. The results are completely consistent with calculations based upon the Low Energy Theorems. Results from studies of a gas jet target in the electron storage ring of the Saskatchewan Accelerator Laboratory (SAL) have been fully analyzed and are being prepared for publication. An Internal Target Development Facility (ITDF), established at NIKHEF-K in a collaborative effort for the purpose of developing higher density gas jet targets suitable for use in electron rings, is operational. Diagnostic techniques are being evaluated in preparation for evaluating jet technology options. Our study of the calcium isotopes ({sup 42}C and {sup 44}C) is nearing completion. Both the electron and proton scattering data have been completely analyzed. Consistent proton and neutron transition densities have been extracted, and are being compared to corresponding results from pion scattering. Preparations for ({gamma},{pi}{sup {minus}}) measurements at SAL have been completed, and data taking is about to commence.
Date: July 10, 1992
Creator: Norum, B. E.
Object Type: Report
System: The UNT Digital Library
Chemical and thermal stability of refrigerant-lubricant mixtures with metals. Quarterly report, 1 April 1992--30 June 1992 (open access)

Chemical and thermal stability of refrigerant-lubricant mixtures with metals. Quarterly report, 1 April 1992--30 June 1992

This report presents completed sealed tube stability test results for the following eight refrigerant/lubricant mixtures: R-22/mineral oil; R-124/alkylbenzene; R-134a/pentaerythritol (PE) ester (mixed acid); R- 134a/PE (branched acid); R-134a/ PE (100 cSt viscosity); R- 142b/alkylbenzene; R-143a/ PE (branched acid); R-152a/alkylbenzene. Partial results are shown for an additional eight refrigerant-lubricant mixtures. Though work is in progress, no data are available at this point in time for the five remaining test mixtures. Reported are: visual observations on aged sealed tubes, gas chromatographic analyses on the vapor phase contents of the tubes, chloride ion contents of HCFC containing mixtures or fluoride ion contents of HFC mixtures, and total acid number values and infrared analysis results for mixtures containing ester lubricants.
Date: July 10, 1992
Creator: Huttenlocher, D. F.
Object Type: Report
System: The UNT Digital Library
Summary of Mini-Workshop on UAL and CESR, LHC, RHIC lattice description (open access)

Summary of Mini-Workshop on UAL and CESR, LHC, RHIC lattice description

None
Date: July 10, 1997
Creator: Pilat, F.; Malitsky, N.; Talman, R.; Tepikian, S.; Trahern, G. & Wei, J.
Object Type: Report
System: The UNT Digital Library
Colloids in Groundwater: Their mobilization, subsurface transport, and sorption affinity for toxic chemicals (open access)

Colloids in Groundwater: Their mobilization, subsurface transport, and sorption affinity for toxic chemicals

Our originally stated objectives included: (1) development of a quantitative source function for colloid mobilization to groundwater, and (2) assessment of the most important colloidal phases to which nonpolar compounds sorb. We have been pursuing a series of studies to elucidate the roles of colloidal phases in subsurface environments. Most notably, we have discovered the critical role of secondary cementitious phases like goethite. We developed a new procedure for measuring surface iron oxides'' which is a great improvement over earlier methodologies. Currently, we are developing a unifying model with which we can predict the mobilization of colloids to groundwater flowing through such porous media. Also, we have been able to show that groundwater samples contain colloidal phases in sufficient quantities and of suitable properties to enhance the mobile load of toxic compounds like polycyclic aromatic hydrocarbons. Finally, we have synthesized our varied field investigations from sites in Massachusetts, New Jersey, Delaware, Nevada, Connecticut, and New York to yield a protocol for other researchers interested in evaluating colloids in groundwater. These accomplishments are discussed in more detail below. Through these efforts, we have become increasingly convinced of the central role played by colloidal phases in numerous subsurface phenomena controlling contaminant fates.
Date: July 10, 1992
Creator: Gschwend, P. M.
Object Type: Report
System: The UNT Digital Library
Colloids in Groundwater: Their mobilization, subsurface transport, and sorption affinity for toxic chemicals. Annual Technical Progress Report (open access)

Colloids in Groundwater: Their mobilization, subsurface transport, and sorption affinity for toxic chemicals. Annual Technical Progress Report

Our originally stated objectives included: (1) development of a quantitative source function for colloid mobilization to groundwater, and (2) assessment of the most important colloidal phases to which nonpolar compounds sorb. We have been pursuing a series of studies to elucidate the roles of colloidal phases in subsurface environments. Most notably, we have discovered the critical role of secondary cementitious phases like goethite. We developed a new procedure for measuring ``surface iron oxides`` which is a great improvement over earlier methodologies. Currently, we are developing a unifying model with which we can predict the mobilization of colloids to groundwater flowing through such porous media. Also, we have been able to show that groundwater samples contain colloidal phases in sufficient quantities and of suitable properties to enhance the mobile load of toxic compounds like polycyclic aromatic hydrocarbons. Finally, we have synthesized our varied field investigations from sites in Massachusetts, New Jersey, Delaware, Nevada, Connecticut, and New York to yield a protocol for other researchers interested in evaluating colloids in groundwater. These accomplishments are discussed in more detail below. Through these efforts, we have become increasingly convinced of the central role played by colloidal phases in numerous subsurface phenomena controlling contaminant fates.
Date: July 10, 1992
Creator: Gschwend, P. M.
Object Type: Report
System: The UNT Digital Library