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(129)Xe NMR of Mesoporous Silicas (open access)

(129)Xe NMR of Mesoporous Silicas

The porosities of three mesoporous silica materials were characterized with {sup 129}Xe NMR spectroscopy. The materials were synthesized by a sol-gel process with r = 0, 25, and 70% methanol by weight in an aqueous cetyltrimethylammonium bromide solution. Temperature dependent chemical shifts and spin lattice relaxation times reveal that xenon does not penetrate the pores of the largely disordered (r= 70%) silica. For both r = 0 and 25%, temperature dependent resonances corresponding to physisorbed xenon were observed. An additional resonance for the r = 25% sample was attributed to xenon between the disordered cylindrical pores. 2D NMR exchange experiments corroborate the spin lattice relaxation data which show that xenon is in rapid exchange between the adsorbed and the gas phase.
Date: April 23, 1999
Creator: Anderson, M.T.; Asink, R.A.; Kneller, J.M. & Pietrass, T.
Object Type: Article
System: The UNT Digital Library
15th Street News (Midwest City, Okla.), Vol. 28, No. 26, Ed. 1 Friday, April 23, 1999 (open access)

15th Street News (Midwest City, Okla.), Vol. 28, No. 26, Ed. 1 Friday, April 23, 1999

Newspaper from Rose State College in Midwest City, Oklahoma that includes national, local, and campus news along with advertising.
Date: April 23, 1999
Creator: Pace, Joshua
Object Type: Newspaper
System: The Gateway to Oklahoma History
[Acceptance into the Master of Arts in Art Education Program] (open access)

[Acceptance into the Master of Arts in Art Education Program]

An official letter from the UNT School of Visual Arts Admissions Committee, celebrating the applicant's success in securing admission to the Master of Arts in Art Education program. This personalized letter shares the joy of acceptance and provides crucial information about the next steps in the exciting journey ahead.
Date: April 23, 1996
Creator: unknown
Object Type: Letter
System: The UNT Digital Library
Activation and Micropore Structure Determination of Activated Carbon-Fiber Composites (open access)

Activation and Micropore Structure Determination of Activated Carbon-Fiber Composites

Previous work focused on the production of carbon fiber composites and subsequently activating them to induce adsorbent properties. One problem related to this approach is the difficulty of uniformly activating large composites. In order to overcome this problem, composites have been made from pre-activated fibers. The loss of surface area upon forming the composites after activation of the fibers was investigated. The electrical resistivity and strength of these composites were compared to those made by activation after forming. It was found that the surface area is reduced by about 35% by forming the composite from pre-activated fibers. However, the properties of the activated sample are very uniform: the variation in surface area is less than {+-}0.5%. So, although the surface area is somewhat reduced, it is believed that making composites from pre-activated fibers could be useful in applications where the BET surface area is not required to be very high. The strength of the composites produced from pre-activated fibers is lower than for composites activated after forming when the carbon burnoff is below 45%. For higher burnoffs, the strength of composites made with pre-activated fibers is as good or better. In both cases, there is a dramatic decrease in strength …
Date: April 23, 1999
Creator: Jagtoyen, M. & Derbyshire, F.
Object Type: Report
System: The UNT Digital Library
Advanced Reservoir Characterization in the Antelope Shale to Establish the Viability of C02 Enhanced Oil Recovery in California's Monterey Formation Siliceous Shales (open access)

Advanced Reservoir Characterization in the Antelope Shale to Establish the Viability of C02 Enhanced Oil Recovery in California's Monterey Formation Siliceous Shales

The primary objective of this research is to conduct advanced reservoir characterization and modeling studies in the Antelope Shale reservoir. Characterization studies will be used to determine the technical feasibility of implementing a CO2 enhanced oil recovery project in the Antelope Shale in Buena Vista Hills Field. The Buena Vista Hills pilot CO2 project will demonstrate the economic viability and widespread applicability of CO2 flooding in fractured siliceous shale reservoirs of the San Joaquin Valley. The research consists of four primary work processes: Reservoir Matrix and Fluid Characterization; Fracture Characterization; Reservoir Modeling and Simulation; and CO2 Pilot Flood and Evaluation. Work done in these areas is subdivided into two phases or budget periods. The first phase of the project will focus on the application of a variety of advanced reservoir characterization techniques to determine the production characteristics of the Antelope Shale reservoir. Reservoir models based on the results of the characterization work will be used to evaluate how the reservoir will respond to secondary recovery and EOR processes. The second phase of the project will include the implementation and evaluation of an advanced enhanced oil recovery (EOR) pilot in the United Anticline (West Dome) of the Buena Vista Hills Field.
Date: April 23, 1998
Creator: Morea, Michael F.
Object Type: Report
System: The UNT Digital Library
Advanced reservoir characterization in the Antelope Shale to establish the viability of CO{sub 2} enhanced oil recovery in California`s Monterey Formation siliceous shales. Quarterly progress report, January 1--March 31, 1998 (open access)

Advanced reservoir characterization in the Antelope Shale to establish the viability of CO{sub 2} enhanced oil recovery in California`s Monterey Formation siliceous shales. Quarterly progress report, January 1--March 31, 1998

The primary objective of this research is to conduct advanced reservoir characterization and modeling studies in the Antelope Shale reservoir. Characterization studies will be used to determine the technical feasibility of implementing a CO{sub 2} enhanced oil recovery project in the Antelope Shale in Buena Vista Hills Field. The Buena Vista Hills pilot CO{sub 2} project will demonstrate the economic viability and widespread applicability of CO{sub 2} flooding in fractured siliceous shale reservoirs of the San Joaquin Valley. The research consists of four primary work processes: Reservoir Matrix and Fluid Characterization; Fracture Characterization; Reservoir Modeling and Simulation; and CO{sub 2} Pilot Flood and Evaluation. Work done in these areas is subdivided into two phases or budget periods. The first phase of the project focused on the application of a variety of advanced reservoir characterization techniques to determine the production characteristics of the Antelope Shale reservoir. Reservoir models based on the results of the characterization work will be used to evaluate how the reservoir will respond to secondary recovery and EOR processes. The second phase of the project will include the implementation and evaluation of an advanced enhanced oil recovery (EOR) pilot in the United Anticline (West Dome) of the Buena …
Date: April 23, 1998
Creator: Morea, M.F.
Object Type: Report
System: The UNT Digital Library
The AGS Booster high frequency rf system (open access)

The AGS Booster high frequency rf system

A high level rf system, including a power amplifier and cavity, has been designed and built for the AGS Booster. It covers a frequency range of 2.4 to 4.2 MHz and will be used to accelerate high intensity protons. Low intensity polarized protons and heavy ions, to the 1.5 GeV level. A total accelerating voltage of up to 90 kV will be provided by two cavities, each having two gaps. The internally cross coupled, pushpull cavities are driven by an adjacently located power amplifier. In order to accommodate beam intensities up to 0.75 {times} 10{sup 13} protons per bunch, a low plate resistance power tetrode is used. The tube anode is magnetically coupled to one of the cavity's two parallel cells. The amplifier is a grounded cathode configuration driven by a remotely located solid-state amplifier. It has been tested in the laboratory at full gap voltage with satisfactory results. 5 refs., 2 figs., 1 tab.
Date: April 23, 1991
Creator: Sanders, R.T.; Cameron, P.; Eng, W.; Goldman, M.A.; Jablonski, E.; Kasha, D. et al.
Object Type: Article
System: The UNT Digital Library
The Albany News (Albany, Tex.), Vol. 116, No. 46, Ed. 1 Thursday, April 23, 1992 (open access)

The Albany News (Albany, Tex.), Vol. 116, No. 46, Ed. 1 Thursday, April 23, 1992

Weekly newspaper from Albany, Texas that includes local, county, and state news along with extensive advertising.
Date: April 23, 1992
Creator: Lucas, Donnie A.
Object Type: Newspaper
System: The Portal to Texas History
The Albany News (Albany, Tex.), Vol. 122, No. 47, Ed. 1 Thursday, April 23, 1998 (open access)

The Albany News (Albany, Tex.), Vol. 122, No. 47, Ed. 1 Thursday, April 23, 1998

Weekly newspaper from Albany, Texas that includes local, county, and state news along with extensive advertising.
Date: April 23, 1998
Creator: Lucas, Donnie A.
Object Type: Newspaper
System: The Portal to Texas History
Altus Times (Altus, Okla.), Vol. 68, No. 97, Ed. 1 Monday, April 23, 1990 (open access)

Altus Times (Altus, Okla.), Vol. 68, No. 97, Ed. 1 Monday, April 23, 1990

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1990
Creator: Lomenick, Rick
Object Type: Newspaper
System: The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 91, No. 34, Ed. 1 Tuesday, April 23, 1991 (open access)

Altus Times (Altus, Okla.), Vol. 91, No. 34, Ed. 1 Tuesday, April 23, 1991

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1991
Creator: Lomenick, Rick
Object Type: Newspaper
System: The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 92, No. 35, Ed. 1 Thursday, April 23, 1992 (open access)

Altus Times (Altus, Okla.), Vol. 92, No. 35, Ed. 1 Thursday, April 23, 1992

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1992
Creator: Lomenick, Rick
Object Type: Newspaper
System: The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 93, No. 35, Ed. 1 Friday, April 23, 1993 (open access)

Altus Times (Altus, Okla.), Vol. 93, No. 35, Ed. 1 Friday, April 23, 1993

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1993
Creator: Lomenick, Rick
Object Type: Newspaper
System: The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 95, No. 34, Ed. 1 Sunday, April 23, 1995 (open access)

Altus Times (Altus, Okla.), Vol. 95, No. 34, Ed. 1 Sunday, April 23, 1995

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1995
Creator: Lomenick, Rick
Object Type: Newspaper
System: The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 96, No. 34, Ed. 1 Tuesday, April 23, 1996 (open access)

Altus Times (Altus, Okla.), Vol. 96, No. 34, Ed. 1 Tuesday, April 23, 1996

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1996
Creator: Lomenick, Rick
Object Type: Newspaper
System: The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 97, No. 35, Ed. 1 Wednesday, April 23, 1997 (open access)

Altus Times (Altus, Okla.), Vol. 97, No. 35, Ed. 1 Wednesday, April 23, 1997

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1997
Creator: Cole, Carol
Object Type: Newspaper
System: The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 99, No. 35, Ed. 1 Thursday, April 23, 1998 (open access)

Altus Times (Altus, Okla.), Vol. 99, No. 35, Ed. 1 Thursday, April 23, 1998

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1998
Creator: Cole, Carol
Object Type: Newspaper
System: The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 100, No. 31, Ed. 1 Friday, April 23, 1999 (open access)

Altus Times (Altus, Okla.), Vol. 100, No. 31, Ed. 1 Friday, April 23, 1999

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date: April 23, 1999
Creator: Cole, Carol
Object Type: Newspaper
System: The Gateway to Oklahoma History
The Alvin Advertiser (Alvin, Tex.), Ed. 1 Wednesday, April 23, 1997 (open access)

The Alvin Advertiser (Alvin, Tex.), Ed. 1 Wednesday, April 23, 1997

Weekly newspaper from Alvin, Texas that includes local, state, and national news along with advertising.
Date: April 23, 1997
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
Alvin Sun-Advertiser (Alvin, Tex.), Vol. 104, No. 74, Ed. 1 Sunday, April 23, 1995 (open access)

Alvin Sun-Advertiser (Alvin, Tex.), Vol. 104, No. 74, Ed. 1 Sunday, April 23, 1995

Weekly newspaper from Alvin, Texas that includes local, state, and national news along with advertising.
Date: April 23, 1995
Creator: Schwind, Jim & Mohon, Wendy
Object Type: Newspaper
System: The Portal to Texas History
The Alvin Sun (Alvin, Tex.), Vol. 102, No. 110, Ed. 1 Friday, April 23, 1993 (open access)

The Alvin Sun (Alvin, Tex.), Vol. 102, No. 110, Ed. 1 Friday, April 23, 1993

Semiweekly newspaper from Alvin, Texas that includes local, state, and national news along with advertising.
Date: April 23, 1993
Creator: Schwind, Jim & Kramer, Mark
Object Type: Newspaper
System: The Portal to Texas History
Amorphization of Laves-Phase Precipitates in Zircaloy-4 by Neutron Irradiation (open access)

Amorphization of Laves-Phase Precipitates in Zircaloy-4 by Neutron Irradiation

Examination of corrosion coupons by transmission electron microscopy after their exposure in the Idaho Advanced Test Reactor (ATR) has broadened the Zircaloy-4 precipitate-amorphization database and validated a new kinetic model for previously unavailable values of temperature and fast-neutron flux. The model describes the amorphization of Zr(Fe,Cr){sub 2} intermetallic precipitates in zirconium alloys as a dynamic competition between radiation damage and thermal annealing that leaves some iron atoms available for flux-assisted diffusion to the zirconium matrix. It predicts the width of the amorphous zone as a function of neutron flux (E>1 MeV), temperature, and time. In its simplest form, the model treats the crystalline/amorphous and precipitate/matrix interfaces as parallel planes, and its accuracy decreases for small precipitates and high fluence as the amorphous-zone width approaches precipitate dimensions. The simplest form of the model also considers diffusion to be rate-determining. This is an accurate approximation for steady-state conditions or slow changes in flux and temperature, but inappropriate for the analysis of faster transients. The paper addresses several difficulties inherent in measuring amorphous-zone width, and utilizes the expanded database to evaluate the improvements in predictive accuracy available through both conversion of the model to spherical coordinates and extension of its time dependency.
Date: April 23, 1999
Creator: Peters, H. R.; Taylor, D. F. & Yang, Walter J. S.
Object Type: Article
System: The UNT Digital Library
Appalachian Clean Coal Technology Consortium: Technical progress report, October 1--December 31, 1995 (open access)

Appalachian Clean Coal Technology Consortium: Technical progress report, October 1--December 31, 1995

In the dewatering project, two different approaches are taken. One approach involves displacing the water on the surface of coal by a hydrophobic substance that can be readily recovered and recycled. This novel concept, referred to as the Hydrophobic Dewatering (HD) process, is based on improved understanding of the surface chemistry of dewatering. The other approach is to use disposable dewatering substances in mechanical dewatering. The objectives of the proposed work are (1) to test the HD process on a variety of coals from the Appalachian coal fields, and (2) to identify suitable dewatering reagents that would enable mechanical dewatering to reduce the moisture to the levels satisfactory to electrical utilities and other coal users. The objective of the spiral separation project is to use computer modeling to develop better, more efficient spiral designs for coal cleaning. The fully-developed model will predict spiral performance based on variations in spiral profile, flow rate, and pitch. Specific goals are to: (1) design spirals capable of making separations at a specific gravity of 1.5, and (2) broaden the size range at which spirals make effective separations.
Date: April 23, 1996
Creator: unknown
Object Type: Report
System: The UNT Digital Library
An Apparatus for the Direct Measurement of Collimator Transverse Wakefields (open access)

An Apparatus for the Direct Measurement of Collimator Transverse Wakefields

The design of the NLC Beam Delivery System requires a firmer understanding of the effects of collimators on short, intense bunches than is presently available. We describe an experiment to directly measure these effects through use of a dedicated apparatus located at the 1.19 GeV point in the SLAC Linac. The apparatus consists of an outer vacuum vessel and an interchangeable insertion containing up to 5 distinct collimator apertures. The insertion is capable of remote-controlled translation, allowing the collimator apertures to be misaligned relative to the electron beam without changing the incoming beam orbit; the wakefield deflection is then measured by observing the change in the outgoing orbit on 32 beam position monitors. The parameters of the apertures have been selected to allow confirmation of the scaling laws for collimator wakefields, and to strongly enhance either the geometric or resistive wall contribution of each aperture. Details of the apparatus design, the aperture parameters, and the experimental program are discussed.
Date: April 23, 1999
Creator: Tenenbaum, Peter G
Object Type: Report
System: The UNT Digital Library