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Interface stability and defect formation during crystal growth (open access)

Interface stability and defect formation during crystal growth

Unidirectional solidification experiments have been carried out in organic crystals with the aim of improving our knowledge on the effects of constraints on the interface morphology and to increase our understanding of the growth of anisotropic materials. The experimental information shows that lateral constraints such as a sharp change in the cross-sectional area in the solid liquid interface path, can produce important changes in the microstructure if the interface morphology is planar, cellular or dendritic. The study of anisotropic materials cover several topics. It is first shown that slight anisotropy does not influence the dendrite tip selection criterion. This conclusion is obtained from the analysis of the relationship between tip radius and velocity for dendrites growing under the steady state condition for two different materials, CBr{sub 4} and C{sub 2}Cl{sub 6}, which have different surface energy anisotropy values. The values of the dendrite operating parameters {sigma}* are compared with the predictions of the solvability theory and the morphological stability theory. The experiments show better agreement with the latter theory. Critical experiments have been designed and carried out to find the response functions which determine the composition and temperature of the interface as a function of velocity in faceted materials. The …
Date: January 8, 1991
Creator: Fabietti, L.M.R.
System: The UNT Digital Library
Gas-phase generations and rearrangement of silathiones, R sub 2 Si=S (open access)

Gas-phase generations and rearrangement of silathiones, R sub 2 Si=S

Three routes are explored for the generation of silathiones: (1) the retroene elimination of propene from allythiodimethylsilane and 1-allythio-1-hydrido-1,2,2,2-tetramethylsilane; (2) the reaction of silylene, Me{sub 2}Di, with carbon disulfide which is thought to form a transient 3-membered ring with CS{sub 2} and the elimination of carbon disulfide to produce diethylsilathione; and (3) the beta-elimination of bis(trimethylsilythio)dimethylsilane. All these methods are explored in some detail. A second example of a silathione-silylene isomerization was observed in the pyrolysis of 1,1-bis(trimethylsilythio)-1,2,2,2-tetramethyldisilane. 89 refs., 5 figs., 10 tab. (BM)
Date: January 8, 1991
Creator: Kim, Chong Bok.
System: The UNT Digital Library
Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers (open access)

Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers

This is a progress report on the second period of activities associated with the DOE grant to the Physics Department of the University of Utah, starting on April 1st, 1991, on photocarrier dynamics, electronic defects and morphology of conducting polymers using the photomodulation spectroscopy. During the second period of this grant we have achieved impressive results and have started new studies, to be completed during the grant continuation period of the third year. We will describe our progress according to the material studied, since this is the best method to summarize our accomplishments. We have used a variety of techniques in our studies such as: CW photomodulation, photomodulation in the femtosecond and picosecond time ranges, CW resonant Raman scattering, transient photoinduced Raman scattering, electro-absorption, degenerate four-wave mixing and the newly technique of spin dependent photomodulation. These techniques have been used to obtain the transient electronic response of the studied conducing polymers.
Date: October 8, 1991
Creator: Vardeny, Z. V.
System: The UNT Digital Library
[Assessment of effects of surfactants in a heavy oil reservoir] (open access)

[Assessment of effects of surfactants in a heavy oil reservoir]

During the past three months we have carefully negotiated a joint venture to implement a pilot for testing the two enhanced oil recovery processes developed at CLD Technology, Inc. The technical staff at CLD Technology, Inc. has decided to model the heavy oil reserve on the Cantleberry Lease, the Jasmin oil field in Kern County, California. Staff members have designed a new sand pack to represent one-eighth (1/8) of a one, ten-acre, five-spot well pattern that will represent the sands of the Cantleberry lease. All calculated parameters are listed in Table 1. The 3-dimensional scaled physical model design represents a typical Cantleberry steamflood pattern. The design of the model will allow the creation of zones identical to those in the Cantleberry lease which will represent the shale break between the Cantleberry A'' and B'' sands. The last 3-dimensional scaled physical model experiment, needed to design the pilot, is ready to go awaiting continuous funding from the DOE.
Date: April 8, 1991
Creator: Kostura, J.A.
System: The UNT Digital Library
[Assessment of effects of surfactants in a heavy oil reservoir]. Third quarterly report, March 30, 1991 (open access)

[Assessment of effects of surfactants in a heavy oil reservoir]. Third quarterly report, March 30, 1991

During the past three months we have carefully negotiated a joint venture to implement a pilot for testing the two enhanced oil recovery processes developed at CLD Technology, Inc. The technical staff at CLD Technology, Inc. has decided to model the heavy oil reserve on the Cantleberry Lease, the Jasmin oil field in Kern County, California. Staff members have designed a new sand pack to represent one-eighth (1/8) of a one, ten-acre, five-spot well pattern that will represent the sands of the Cantleberry lease. All calculated parameters are listed in Table 1. The 3-dimensional scaled physical model design represents a typical Cantleberry steamflood pattern. The design of the model will allow the creation of zones identical to those in the Cantleberry lease which will represent the shale break between the Cantleberry ``A`` and ``B`` sands. The last 3-dimensional scaled physical model experiment, needed to design the pilot, is ready to go awaiting continuous funding from the DOE.
Date: April 8, 1991
Creator: Kostura, J. A.
System: The UNT Digital Library
D-Zero Collider Detector CC Initial Vacuum Pumping Preparation and Procedure (open access)

D-Zero Collider Detector CC Initial Vacuum Pumping Preparation and Procedure

The initial vacuum pumping of the fully loaded cryostats immediately upon completing the minimum head welding necessary for the cryostat vacuum loading is important to (1) water removal, (2) high vapor pressure (micron level) outgassing, (3) helium mass spectrometer leak checking sensitivity, and (4) a less well understood concern for LAr background contamination. The CC pumping preparation and procedure that has been utilized is recorded here. Recommendations are incorporated in italics and in context to improve the EC vacuum preparations and pumping performance. The estimated pumping loads of large assemblies of (G10) water laden modules are calculated in EN 270. The predicted and experienced water pumping period was ca. 45 days. The cryopump specifically designed to serve this purpose is described in EN 291. These notes are recommended background reading for this work.
Date: April 8, 1991
Creator: Wu, J.
System: The UNT Digital Library
(Contaminated soil) (open access)

(Contaminated soil)

The traveler attended the Third International Conference on Contaminated Soil, held in Karlsruhe, Germany. The Conference was a status conference for worldwide research and practice in contaminated soil assessment and environmental restoration, with more than 1500 attendees representing over 26 countries. The traveler made an oral presentation and presented a poster. At the Federal Institute for Water, Soil and Air Hygiene, the traveler met with Dr. Z. Filip, Director and Professor, and Dr. R. Smed-Hildmann, Research Scientist. Detailed discussions were held regarding the results and conclusions of a collaborative experiment concerning humic substance formation in waste-amended soils.
Date: January 8, 1991
Creator: Siegrist, Robert L.
System: The UNT Digital Library
Design of slurry reactor for indirect liquefaction applications. Quarterly technical progress report, January 1991--March 1991 (open access)

Design of slurry reactor for indirect liquefaction applications. Quarterly technical progress report, January 1991--March 1991

The objective of this project is to design a conceptual slurry reactor for two indirect liquefaction applications; production of methanol and production of hydrogen fuels via Fischer-Tropsch route. The work will be accomplished by the formulation of reactor models for both the processes and use computer simulation. Process data, kinetic and thermodynamic data, heat and mass transfer data and hydrodynamic data will be used in the mathematical models to describe the slurry reactor for each of the two processes. The cost of current vapor phase reactor systems will be compared with cost estimated for the slurry reactor systems. For the vapor phase systems, upstream and downstream processing equipments may have to be included during cost analysis for a meaningful cost comparison.
Date: April 8, 1991
Creator: Prakash, A. & Bendale, P. G.
System: The UNT Digital Library
Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers. Progress report (open access)

Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers. Progress report

This is a progress report on the second period of activities associated with the DOE grant to the Physics Department of the University of Utah, starting on April 1st, 1991, on photocarrier dynamics, electronic defects and morphology of conducting polymers using the photomodulation spectroscopy. During the second period of this grant we have achieved impressive results and have started new studies, to be completed during the grant continuation period of the third year. We will describe our progress according to the material studied, since this is the best method to summarize our accomplishments. We have used a variety of techniques in our studies such as: CW photomodulation, photomodulation in the femtosecond and picosecond time ranges, CW resonant Raman scattering, transient photoinduced Raman scattering, electro-absorption, degenerate four-wave mixing and the newly technique of spin dependent photomodulation. These techniques have been used to obtain the transient electronic response of the studied conducing polymers.
Date: October 8, 1991
Creator: Vardeny, Z. V.
System: The UNT Digital Library
D0 Collider Detector LINDE, East Chicago (LAr Contractor) Trip Report (open access)

D0 Collider Detector LINDE, East Chicago (LAr Contractor) Trip Report

East Chicago is capable of processing air at a 6-7E6 SCFH rate. They can produce as much as 1.2E6 SCFH 02 and 4.5 SCFH N2 (not coincidently) with a peak product efficiency of 85-86% (product to total Intake). The general area demand has been as high as 10E6, as low as 4.5E6, and is currently 8E6 SCFH totaI product. The plant is really four plants in one. At anyone time one or more plants can be down for maintenance and the others online and delivering to the pipe line that distributes their product to nearby steel plants, and to the liquid reservoirs (perlite insulated tanks) of 160, 160 and 200 E6 SCF. At the time of our visit two plants were down and two were on line. The following describes the characteristics of one of the four plants. The cycle requires a base compressor (Brown Boveri, 22,600 hp) that pumps to 90-100 psig, and a booster compressor (Clark, 14,000 hp) that pumps to 300 psig. Filter houses (ca. 20-ft x 20-ft) feed the suctions and the discharge is scrubbed by dual, molecular sieve, beds 0 300 psi (6-8 hour cycle time). The beds are provided with dust blow down and …
Date: February 8, 1991
Creator: Dixon, K.; Krempetz, K.; Mulholland, G.T.; Urbin, J. & /Fermilab
System: The UNT Digital Library
Finite. beta. and nonlocal calculation of collisionless and dissipative drift instabilities (open access)

Finite. beta. and nonlocal calculation of collisionless and dissipative drift instabilities

Collisionless and dissipative drift waves, driven by gradients in the plasma density and/or temperatures, are believed to dominate or at least influence the transport properties of a variety of plasma confinement devices. In a study begun in reference to transport in the Field Reversed Configuration (FRC), we have developed a theory of these waves in a high {beta} plasma, including the effect of perturbed flow in the direction of the plasma density. This study was a natural extension of previous calculations; the {beta} = 1 nature of the FRC makes a proper treatment of high {beta} effects vital to an understanding of that device. In the course of this study we have obtained a comprehensive dispersion relation which shows clearly how the numerical dissipative drift wave instabilities evolve in wavenumber as {beta} increases. A major finding from this is that the effect of finite {beta} begins to dominate long before {beta} {yields} 1; the expansion parameter is {beta}f(k, a{sub i}, K, {omega}, L{sub n}) where f can be substantially greater than 1, depending on the wavenumber of the wave parallel to the magnetic field (K), the wavenumber parallel to the particle drifts (k), the wave frequency ({omega}), the strength of …
Date: April 8, 1991
Creator: Krall, Nicholas A.
System: The UNT Digital Library
Japan-U.S. Global Partnership: Implications of the Postponement of the President's November 1991 Trip to Japan (open access)

Japan-U.S. Global Partnership: Implications of the Postponement of the President's November 1991 Trip to Japan

Both the Bush Administration and the new Japanese Government headed by Prime Minister Kiichi Miyazawa had given considerable importance to the President,s planned trip to Tokyo in late November, now postponed in the interest of attending to domestic concerns.
Date: November 8, 1991
Creator: Cronin, Richard P.
System: The UNT Digital Library