Investigation of the phase equilibria and phase transformations associated with the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} superconductor (open access)

Investigation of the phase equilibria and phase transformations associated with the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} superconductor

The solid solution region and reaction kinetics of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (2212) superconductor were examined as a function of temperature and oxygen partial pressure. Crystallization studies from the glassy and molten states were undertaken to determine the phase transformation and kinetics associated with the formation of 2212 and other competing phases. Crystallization of nominal 2212 glasses was found to proceed in two steps with the formation of Bi{sub 2}Sr{sub 2{minus}x}Ca{sub x}CuO{sub y} (2201) and Cu{sub 2}O followed by Bi{sub 2}Sr{sub 3{minus}x}Ca{sub x}O{sub y}, CaO, and SrO. The 2212 phase converts from the 2201 phase with increasing temperatures. However, its formation below 800 C was kinetically limited. At 800 C and above, a nearly full conversion to the 2212 phase was achieved after only one minute although considerably longer anneal times were necessary for the system to reach equilibrium. In low oxygen partial pressures, the solidus is reduced to approximately 750 C. Solidification studies revealed an eutectic structure separating the incongruently melting 2212/2201 phases at high oxygen partial pressures from the congruently melting Bi{sub 2}Sr{sub 3{minus}x}Ca{sub x}O{sub y} (23x) and Bi{sub 2}Sr{sub 2{minus}x}Ca{sub x}O{sub y} (22x) phases present at low oxygen partial pressures. During solidification in various oxygen …
Date: December 9, 1993
Creator: Holesinger, T.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Household vehicles energy consumption 1991 (open access)

Household vehicles energy consumption 1991

The purpose of this report is to provide information on the use of energy in residential vehicles in the 50 States and the District of Columbia. Included are data about: the number and type of vehicles in the residential sector, the characteristics of those vehicles, the total annual Vehicle Miles Traveled (VMT), the per household and per vehicle VMT, the vehicle fuel consumption and expenditures, and vehicle fuel efficiencies. The data for this report are based on the household telephone interviews from the 1991 RTECS, conducted during 1991 and early 1992. The 1991 RTECS represents 94.6 million households, of which 84.6 million own or have access to 151.2 million household motor vehicles in the 50 States and the District of Columbia.
Date: December 9, 1993
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Plasma enhanced chemical vapor deposition of ZrO{sub 2} thin films (open access)

Plasma enhanced chemical vapor deposition of ZrO{sub 2} thin films

Amorphous ZrO{sub 2} thin films were deposited in an inductively coupled PECVD system using a Zr {beta}-diketonate, Zr(C{sub 11}H{sub 19}O{sub 2}){sub 4}, as the precursor. The deposits were air annealed at 900C for 5 min to get pure, single phase, oriented, polycrystalline {alpha}-ZrO{sub 2}. Feasibility of using 2 different types of reactors was investigated. The inductively heated horizontal reactor depositions at 600C had a lower deposition rate and the films were non-uniform in thickness with a columnar structure. The resistively heated vertical reactor depositions at 350C had a higher deposition rate and the films were more uniform in thickness with a fine grained microstructure. The statistical design was demonstrated as an effective technique to analyze the effect of process conditions on the rate of deposition and relative (h00) orientation. The factorial design was used to quantify the two responses in terms of the process variables and their mutual interactions. The statistical design for rate of deposition was found to correlate with the trends observed in classical design.
Date: December 9, 1993
Creator: Saravanan, Kolandaivelu
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Viscosity measurements on clear liquids (open access)

Viscosity measurements on clear liquids

During the ITP cold chemical testing program, the efficiency of the benzene strippers will be measured and evaluated. Since the stripping efficiency is partially dependent upon the dynamic viscosity of the liquid phase, this property must be measured on samples taken during the test program. A procedure to measure the dynamic viscosity of salt solutions was developed from standard American Society of Testing and materials (ASTM) methods. The SRS procedure differs from the ASTM procedure and, therefore, a test program was initiated to determine its accuracy and precision. The results of these statistically designed tests are reported elsewhere, but supporting information on the experimental procedures, standards, and equipment are given in this report.
Date: February 9, 1993
Creator: Walker, D. D.
Object Type: Report
System: The UNT Digital Library
Detection of greenhouse-gas-induced climatic change. Progress report, 1 December 1992--30 June 1993 (open access)

Detection of greenhouse-gas-induced climatic change. Progress report, 1 December 1992--30 June 1993

The aims of the US Department of Energy`s Carbon Dioxide Research Program are to improve assessments of greenhouse-gas-induced climatic change and to define and reduce uncertainties through selected research. The main research areas covered by this proposal are (b), First Detection and (c) Supporting Data. The project will also include work under area (a), Modeling: specifically, analysis of climate forcing factors, the development and refinement of transient response climate models, and the use of instrumental data in validating General Circulating Models (GCMs).
Date: July 9, 1993
Creator: Wigley, T. M. L. & Jones, P. D.
Object Type: Report
System: The UNT Digital Library
Optimization of neutron source (open access)

Optimization of neutron source

I consider here the optimization of the two component neutron source, allowing beam species and energy to vary. A simple model is developed, based on the earlier publications, that permits the optimum to be obtained simply. The two component plasma, with one species of hot ion (D{sup +} or T{sup +}) and the complementary species of cold ion, is easy to analyze in the case of a spatially uniform cold plasma, as to good approximation the total number of hot ions is important but not their spatial distribution. Consequently, the optimization can ignore spatial effects. The problem of a plasma with both types of hot ions and cold ions is rather more difficult, as the neutron production by hot-hot interactions is sensitive to their spatial distributions. Consequently, consideration of this problem will be delayed to a future memorandum. The basic model is that used in the published articles on the two-component, beam-plasma mirror source. I integrate the Fokker-Planck equation analytically, obtaining good agreement with previous numerical results. This simplifies the optimization, by providing a functional form for the neutron production. The primary result is expressed in terms of the power efficiency: watts of neutrons/watts of primary power. The latter includes …
Date: November 9, 1993
Creator: Hooper, E. B.
Object Type: Report
System: The UNT Digital Library
Applications of Micellar Enzymology to Clean Coal Technology. Twelfth Quarterly Report (open access)

Applications of Micellar Enzymology to Clean Coal Technology. Twelfth Quarterly Report

This project is designed to develop methods for precombustion coal remediation by implementing recent advances in enzyme biochemistry. The novel approach of this study is incorporation of hydrophilic oxidative enzymes in reverse micelles in an organic solvent. Enzymes from commercial sources or microbial extracts are being investigated for their capacity to remove organic sulfur from coal by oxidation of the sulfur groups, splitting of C-S bonds and loss of sulfur as sulfuric acid. Dibenzothiophene (DBT) and ethylphenylsulfide (EPS) are serving as models of organic sulfur-containing components of coal in initial studies. A goal of this project is to define a reverse micelle system that optimizes the catalytic activity of enzymes toward desulfurization of model compounds and ultimately coal samples. Studies by several groups (Martinek et al., 1981; Kabanov et al., 1988; Martinek, 1989; Verhaert et al., 1990) have shown that the surfactant AOT over a broad concentration range in organic solvents produces micelles, comparatively uniform in diameter, which incorporate hydrophilic enzymes. The activity (kcat) of certain enzymes in this system is higher than in aqueous solution. This surfactant is therefore being examined as a vehicle for enhancement of sulfoxidation reactions.
Date: March 9, 1993
Creator: Walsh, C. T.
Object Type: Report
System: The UNT Digital Library
Thermo-hydraulic analysis of superconducting toroidal-field magnets for the Tokamak Physics Experiment (open access)

Thermo-hydraulic analysis of superconducting toroidal-field magnets for the Tokamak Physics Experiment

The superconducting magnets in Fusion Reactors are subjected to pulsed, nuclear, and resistive heating. The thermo-hydraulic response of the helium forced-flow cooled conductors to the various heat sources is critical to magnet design and performance. Recently developed computer codes allow accurate modeling of conductor response and have been used as an aid to design of the toroidal field (TF) magnets for the Tokamak Physics experiment (TPX). We present results of design studies that determine the trade-off between double- and single-pancake helium flow configurations, the minimum-temperature margin, and the stability against rapid heat input. The results guide the choice and design of the liquid helium refrigerator.
Date: July 9, 1993
Creator: Wong, R. L.; Zbasnik, J. P. & Hassenzahl, W. V.
Object Type: Article
System: The UNT Digital Library
An external peer review of the U.S. Department of Energy`s assessment of ``damages and benefits of the fuel cycles: Estimation methods, impacts, and values``. Final report (open access)

An external peer review of the U.S. Department of Energy`s assessment of ``damages and benefits of the fuel cycles: Estimation methods, impacts, and values``. Final report

The need for better assessments of the ``external`` benefits and costs of environmental effects of various fuel cycles was identified during the development of the National Energy Strategy. The growing importance of this issue was emphasized by US Department of Energy (DOE) management because over half of the states were already pursuing some form of social costing in electricity regulation and a well-established technical basis for such decisions was lacking. This issue was identified as a major area of controversy--both scientifically and politically--in developing energy policies at the state and national level. In 1989, the DOE`s Office of Domestic and International Energy Policy commissioned a study of the external environmental damages and benefits of the major fuel cycles involved in electric power generation. Over the next 3-year period, Oak Ridge National Laboratory and Resources for the Future conducted the study and produced a series of documents (fuel cycle documents) evaluating the costs of environmental damages of the coal, oil, natural gas, biomass, hydroelectric, and nuclear fuel cycles, as well as the Background Document on methodological issues. These documents described work that took almost 3 years and $2.5 million to complete and whose implications could be far reaching. In 1992, the …
Date: August 9, 1993
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Engineering study of tank leaks related to hydraulic retrieval of sludge from tank 241-C-106. Revision 1 (open access)

Engineering study of tank leaks related to hydraulic retrieval of sludge from tank 241-C-106. Revision 1

This study evaluates hydraulic retrieval (sluicing) of the waste in single-shell tank 241-C-106 with respect to the likelihood of tank leaks, gross volumes of potential leaks, and their consequences. A description of hydraulic retrieval is developed to establish a baseline for the study. Leak models are developed based on postulated leak mechanisms to estimate the amount of waste that could potentially leak while sluicing. Transport models describe the movement of the waste constituents in the surrounding soil and groundwater after a leak occurs. Environmental impact and risk associated with tank leaks are evaluated. Transport of leaked material to the groundwater is found to be dependent on the rate of recharge of moisture in the soil for moderate-sized leaks. Providing a cover over the tank and surrounding area would eliminate the recharge. The bulk of any leaked material would remain in the vicinity of the tank for remedial action.
Date: June 9, 1993
Creator: Lowe, S. S.; Carlos, W. C.; Irwin, J. J.; Khaleel, R.; Kline, N. W.; Ludowise, J. D. et al.
Object Type: Report
System: The UNT Digital Library
The Department of Energy Nevada Test Site Remote Area Monitoring System (open access)

The Department of Energy Nevada Test Site Remote Area Monitoring System

The Remote Area Monitoring System was developed by Los Alamos National Laboratory (LANL) for DOE test directors at the Nevada Test Site (NTS) to verify radiological conditions are safe after a nuclear test. In the unlikely event of a venting as a result of a nuclear test, this system provides radiological and meteorological data to Weather Service Nuclear Support Office (WSNSO) computers where mesoscale models are used to predict downwind exposure rates. The system uses a combination of hardwired radiation sensors and satellite based data acquisition units with their own radiation sensors to measure exposure rates in remote areas of the NTS. The satellite based data acquisition units are available as small, Portable Remote Area Monitors (RAMs) for rapid deployment, and larger, Semipermanent RAMs that can have meteorological towers. The satellite based stations measure exposure rates and transmit measurements to the GOES (Geostationary Operational Environmental Satellite) where they are relayed to Direct Readout Ground Stations (DRGS) at the NTS and Los Alamos. Computers process the data and display results in the NTS Operations Coordination Center. Los Alamos computers and NTS computers are linked together through a wide area network, providing remote redundant system capability. Recently, LANL, expanded the system to …
Date: June 9, 1993
Creator: Sanders, L. D. & Hart, O. F.
Object Type: Article
System: The UNT Digital Library
Cold Mass Support System for he D0 Solenoid (open access)

Cold Mass Support System for he D0 Solenoid

The support system is designed to support the gravitational, magnetic, and thermal contraction loads associated with the cold mass weighing 1.46 metric tons (3210 Ibm). The loading constraints are listed in Table 1. The support system consists of axial members (axial supports) to provide longitudinal stiffness and nearly tangential members (radial supports) to provide radial stiffness. The members connect the outer support cylinder to the flat annular bulkheads of the vacuum vessel. See Figures 1 through 3 for additional details on the supports. Six axial compression-tension supports are located on the chimney end of the cryostat only. Six radial tension supports are located on each end. Both types of members are fabricated of Inconel 718 and have a design safety factor of 4 on the ultimate strength at 300 K. The axial supports are also designed for a buckling safety factor of 4 for the operating loads. Shipping stops will be installed to prevent the axial supports from going into compression during transportation. Axial and radial contraction of the coil support cylinder is accommodated by spherical bearings on both ends ofeach support member.
Date: August 9, 1993
Creator: Squires, B.
Object Type: Report
System: The UNT Digital Library
Strength Test on Optical Fibers to be Used in VLPC (open access)

Strength Test on Optical Fibers to be Used in VLPC

The objective is to determine the strength of the optical fibers to be used in the VLPC cassette. Strength tests were done on optical fibers that are to be used in the VLPC cassette. A number of the fibers will hang vertically and support a suspended copper isotherm. Concern was expressed over whether one fiber could support the entire weight of the isotherm (8 ounces) if uneven shrinkage of the fibers occurs at cryogenic temperatures. The fibers have a polystyrene core and testing done at room temperature showed that one fiber can support the isotherm with a factor of safety of 13.2 before fracture will occur from a uniaxial load. Data in Cryogenic Engineering by Scott shows that the strength of plastics increases (although polystyrene is not listed) as they are cooled. Two tests done to the fibers with liquid nitrogen support this. The safety factor of 13.2 will only increase at cryogenic temperatures. These results were determined through three tests whose summaries are given.
Date: February 9, 1993
Creator: Olis, D.
Object Type: Report
System: The UNT Digital Library
Cartan calculus on quantum Lie algebras (open access)

Cartan calculus on quantum Lie algebras

A generalization of the differential geometry of forms and vector fields to the case of quantum Lie algebras is given. In an abstract formulation that incorporates many existing examples of differential geometry on quantum spaces we combine an exterior derivative, inner derivations, Lie derivatives, forms and functions au into one big algebra, the ``Cartan Calculus.``
Date: December 9, 1993
Creator: Schupp, P.; Watts, P. & Zumino, B.
Object Type: Article
System: The UNT Digital Library
Characterization of the organic-sulfur-degrading enzymes. [Quarterly] technical report, September 1, 1992--November 30, 1992 (open access)

Characterization of the organic-sulfur-degrading enzymes. [Quarterly] technical report, September 1, 1992--November 30, 1992

The immediate objective of this project is to characterize and purify the enzymes involved in degrading organic sulfur in coal from two well characterization organic sulfur degrading strains, of Rhodococces rhodochorous IGTS8 and K3B. We believe that characterization and purification of these enzymes may provide valuable information that will lead to developing or isolating better strains for desulfurization of coal. Our recent results imply that the IGTS8 enzymes are firmly attached to the cell wall. For coal desulfurization it is better to have a microorganism that can secrete its desulfurization enzymes into the medium. The enzymes could permeate into coal much better than a bacterial cell. We seek that the isolation of a mutant of IGTS8 which can release the desulfurization enzymes in the cultural medium. During this period, we carried out more electron microscope analysis of IGTS8 and related species. These strains grow very poorly in DBT medium as well as in medium containing high sulfate concentration. Cells used for EM analysis were cultured in rich medium with glucose but found that there is no protruding structures on the cells of R. rhodochorous 184 and 13808. We believe that we should also examine the 183 and 13808 cells that …
Date: March 9, 1993
Creator: Ho, N. W. Y.
Object Type: Report
System: The UNT Digital Library
Fundamental mode rf power dissipated in a waveguide attached to an accelerating cavity (open access)

Fundamental mode rf power dissipated in a waveguide attached to an accelerating cavity

An accelerating RF cavity usually requires accessory devices such as a tuner, a coupler, and a damper to perform properly. Since a device is attached to the wall of the cavity to have certain electrical coupling of the cavity field through the opening. RF power dissipation is involved. In a high power accelerating cavity, the RF power coupled and dissipated in the opening and in the device must be estimated to design a proper cooling system for the device. The single cell cavities of the APS storage ring will use the same accessories. These cavities are rotationally symmetric and the fields around the equator can be approximated with the fields of the cylindrical pillbox cavity. In the following, the coupled and dissipated fundamental mode RF power in a waveguide attached to a pillbox cavity is discussed. The waveguide configurations are (1) aperture-coupled cylindrical waveguide with matched load termination; (2) short-circuited cylindrical waveguide; and (3) E-probe or H-loop coupled coaxial waveguide. A short-circuited, one-wavelength coaxial structure is considered for the fundamental frequency rejection circuit of an H-loop damper.
Date: February 9, 1993
Creator: Kang, Y. W.
Object Type: Report
System: The UNT Digital Library
Mixed Waste Working Group report (open access)

Mixed Waste Working Group report

The treatment of mixed waste remains one of this country`s most vexing environmental problems. Mixed waste is the combination of radioactive waste and hazardous waste, as defined by the Resource Conservation and Recovery Act (RCRA). The Department of Energy (DOE), as the country`s largest mixed waste generator, responsible for 95 percent of the Nation`s mixed waste volume, is now required to address a strict set of milestones under the Federal Facility Compliance Act of 1992. DOE`s earlier failure to adequately address the storage and treatment issues associated with mixed waste has led to a significant backlog of temporarily stored waste, significant quantities of buried waste, limited permanent disposal options, and inadequate treatment solutions. Between May and November of 1993, the Mixed Waste Working Group brought together stakeholders from around the Nation. Scientists, citizens, entrepreneurs, and bureaucrats convened in a series of forums to chart a course for accelerated testing of innovative mixed waste technologies. For the first time, a wide range of stakeholders were asked to examine new technologies that, if given the chance to be tested and evaluated, offer the prospect for better, safer, cheaper, and faster solutions to the mixed waste problem. In a matter of months, the …
Date: November 9, 1993
Creator: unknown
Object Type: Report
System: The UNT Digital Library
The superfluid Stirling refrigerator, a new method for cooling below 0.5 K (open access)

The superfluid Stirling refrigerator, a new method for cooling below 0.5 K

A new subkelvin refrigerator, the superfluid Stirling cycle refrigerator, uses a working fluid of {sup 3}He-{sup 4}He mixture in a Stirling cycle. The thermodynamically active components of the mixture are the {sup 3}He, which behaves like a Boltzman gas, and the phonon-roton gas in the {sup 4}He. The superfluid component of the liquid is inert. Two refrigerators have been built and temperatures of 340 mK have been achieved.
Date: April 9, 1993
Creator: Brisson, J. G.; Kotsubo, V. & Swift, G. W.
Object Type: Article
System: The UNT Digital Library
Quantum groups, non-commutative differential geometry and applications (open access)

Quantum groups, non-commutative differential geometry and applications

The topic of this thesis is the development of a versatile and geometrically motivated differential calculus on non-commutative or quantum spaces, providing powerful but easy-to-use mathematical tools for applications in physics and related sciences. A generalization of unitary time evolution is proposed and studied for a simple 2-level system, leading to non-conservation of microscopic entropy, a phenomenon new to quantum mechanics. A Cartan calculus that combines functions, forms, Lie derivatives and inner derivations along general vector fields into one big algebra is constructed for quantum groups and then extended to quantum planes. The construction of a tangent bundle on a quantum group manifold and an BRST type approach to quantum group gauge theory are given as further examples of applications. The material is organized in two parts: Part I studies vector fields on quantum groups, emphasizing Hopf algebraic structures, but also introducing a ``quantum geometric`` construction. Using a generalized semi-direct product construction we combine the dual Hopf algebras A of functions and U of left-invariant vector fields into one fully bicovariant algebra of differential operators. The pure braid group is introduced as the commutant of {Delta}(U). It provides invariant maps A {yields} U and thereby bicovariant vector fields, casimirs and …
Date: December 9, 1993
Creator: Schupp, P.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Interlock and control systems for a sector at the APS (open access)

Interlock and control systems for a sector at the APS

This report describes some basic elements of the various Interlock and Control Systems associated with the Front Ends and Beamlines. Some systems serve only the Front Ends; other serve both the Front Ends and the Beamlines, while the Experimental Controls are for the Beamlines only. Specific system requirements and design specifications are not in the scope of this report. They will be presented in the descriptions of the Experimental Floor Personnel Safety System (XF-PSS or, more often, PSS) and Equipment Protection System (XF-EPS or EPS), which will expand on the overview presented here. The main focus here is on the PSS and EPS in the context of their interactions and interface to the Storage Ring Access Control Interlock System (ACIS), and Ring Controls. The other systems are only mentioned to make the cross section complete. This paper is the first in series of three reports that jointly provide a full description of sector interlocks. The second report describes the PSS, and the third -- the EPS.
Date: September 9, 1993
Creator: Friedman, N.
Object Type: Report
System: The UNT Digital Library
Characteristics of a High Energy {mu sup +}{mu sup -} Collider Based on Electro-Production of Muons (open access)

Characteristics of a High Energy {mu sup +}{mu sup -} Collider Based on Electro-Production of Muons

We analyze the design of an high energy {mu}{sup +}{mu}{sup -} collider based on electro-production of muons. We derive an expression for the luminosity in terms of analytic formulae for the electron-to-muon conversion efficiency and the electron beam power on the production target On the basis of studies of self-consistent sets of collider parameters under 'realistic' ('optimistic') assumptions about available technology with beam cooling, we find the luminosity limited to 10{sup 27} m{sup -2}s{sup -1} (10{sup 28} m{sup -2}s{sup -1}). We also identify major technological innovations that will be required before {mu}{sup +}{mu}{sup -} colliders can offer sufficient luminosity (10{sup 30} cm{sup -2}s{sup -1}) for high energy physics research.
Date: January 9, 1993
Creator: Barletta, W. A. & Sessler, Andrew M.
Object Type: Article
System: The UNT Digital Library
Viscosity measurements on clear liquids (open access)

Viscosity measurements on clear liquids

During the ITP cold chemical testing program, the efficiency of the benzene strippers will be measured and evaluated. Since the stripping efficiency is partially dependent upon the dynamic viscosity of the liquid phase, this property must be measured on samples taken during the test program. A procedure to measure the dynamic viscosity of salt solutions was developed from standard American Society of Testing and materials (ASTM) methods. The SRS procedure differs from the ASTM procedure and, therefore, a test program was initiated to determine its accuracy and precision. The results of these statistically designed tests are reported elsewhere, but supporting information on the experimental procedures, standards, and equipment are given in this report.
Date: February 9, 1993
Creator: Walker, D. D.
Object Type: Report
System: The UNT Digital Library
Fundamental mode rf power dissipated in a waveguide attached to an accelerating cavity (open access)

Fundamental mode rf power dissipated in a waveguide attached to an accelerating cavity

An accelerating RF cavity usually requires accessory devices such as a tuner, a coupler, and a damper to perform properly. Since a device is attached to the wall of the cavity to have certain electrical coupling of the cavity field through the opening. RF power dissipation is involved. In a high power accelerating cavity, the RF power coupled and dissipated in the opening and in the device must be estimated to design a proper cooling system for the device. The single cell cavities of the APS storage ring will use the same accessories. These cavities are rotationally symmetric and the fields around the equator can be approximated with the fields of the cylindrical pillbox cavity. In the following, the coupled and dissipated fundamental mode RF power in a waveguide attached to a pillbox cavity is discussed. The waveguide configurations are (1) aperture-coupled cylindrical waveguide with matched load termination; (2) short-circuited cylindrical waveguide; and (3) E-probe or H-loop coupled coaxial waveguide. A short-circuited, one-wavelength coaxial structure is considered for the fundamental frequency rejection circuit of an H-loop damper.
Date: February 9, 1993
Creator: Kang, Y.W.
Object Type: Report
System: The UNT Digital Library
Applications of Micellar Enzymology to Clean Coal Technology (open access)

Applications of Micellar Enzymology to Clean Coal Technology

This project is designed to develop methods for precombustion coal remediation by implementing recent advances in enzyme biochemistry. The novel approach of this study is incorporation of hydrophilic oxidative enzymes in reverse micelles in an organic solvent. Enzymes from commercial sources or microbial extracts are being investigated for their capacity to remove organic sulfur from coal by oxidation of the sulfur groups, splitting of C-S bonds and loss of sulfur as sulfuric acid. Dibenzothiophene (DBT) and ethylphenylsulfide (EPS) are serving as models of organic sulfur-containing components of coal in initial studies. A goal of this project is to define a reverse micelle system that optimizes the catalytic activity of enzymes toward desulfurization of model compounds and ultimately coal samples. Studies by several groups (Martinek et al., 1981; Kabanov et al., 1988; Martinek, 1989; Verhaert et al., 1990) have shown that the surfactant AOT over a broad concentration range in organic solvents produces micelles, comparatively uniform in diameter, which incorporate hydrophilic enzymes. The activity (kcat) of certain enzymes in this system is higher than in aqueous solution. This surfactant is therefore being examined as a vehicle for enhancement of sulfoxidation reactions.
Date: March 9, 1993
Creator: Walsh, C. T.
Object Type: Report
System: The UNT Digital Library