Review of U.S. Neutrino Factory Studies (open access)

Review of U.S. Neutrino Factory Studies

We summarize the status of the two U.S. feasibility studies carried out by the Neutrino Factory and Muon Collider Collaboration (NFMCC) along with recent improvements to Neutrino Factory design developed during the American Physical Society (APS) Neutrino Physics Study. Suggested accelerator topics for the International Scoping Study (ISS) are also indicated.
Date: August 23, 2005
Creator: Zisman, Michael S.
Object Type: Article
System: The UNT Digital Library
PIMC Simulation of Ps Annihilation: From Micro to Mesopores (open access)

PIMC Simulation of Ps Annihilation: From Micro to Mesopores

Path Integral Monte Carlo (PIMC) can reproduce the results of simple analytical calculations in which a single quantum particle is used to represent positronium within an idealized, spherical pore. Our calculations improve on this approach by explicitly treating the positronium as a two-particle e{sup -}, e{sup +} system interacting via the Coulomb interaction. We study the lifetime and the internal contact density, {kappa}, which controls the self-annihilation behavior, for positronium in model spherical pores, as a function of temperature and pore size. We compare the results with both PIMC and analytical calculations for a single-particle model.
Date: August 23, 2005
Creator: Bug, A. R. & Sterne, P. A.
Object Type: Article
System: The UNT Digital Library
Nanometer-scale imaging and pore-scale fluid flow modeling inchalk (open access)

Nanometer-scale imaging and pore-scale fluid flow modeling inchalk

For many rocks of high economic interest such as chalk,diatomite, tight gas sands or coal, nanometer scale resolution is neededto resolve the 3D-pore structure, which controls the flow and trapping offluids in the rocks. Such resolutions cannot be achieved with existingtomographic technologies. A new 3D imaging method, based on serialsectioning and using the Focused Ion Beam (FIB) technology has beendeveloped. FIB allows for the milling of layers as thin as 10 nanometersby using accelerated Ga+ ions to sputter atoms from the sample surface.After each milling step, as a new surface is exposed, a 2D image of thissurface is generated. Next, the 2D images are stacked to reconstruct the3D pore or grain structure. Resolutions as high as 10 nm are achievableusing this technique. A new image processing method uses directmorphological analysis of the pore space to characterize thepetrophysical properties of diverse formations. In addition to estimationof the petrophysical properties (porosity, permeability, relativepermeability and capillary pressures), the method is used for simulationof fluid displacement processes, such as those encountered in variousimproved oil recovery (IOR) approaches. Computed with the new methodcapillary pressure curves are in good agreement with laboratory data. Themethod has also been applied for visualization of the fluid distributionat various saturations …
Date: August 23, 2005
Creator: Tomutsa, Liviu; Silin, Dmitriy & Radmilovich, Velimir
Object Type: Article
System: The UNT Digital Library
A QSAR for the Mutagenic Potencies of Twelve 2-Amino-trimethylimidazopyridine Isomers: Structural, Quantum Chemical,and Hydropathic Factors (open access)

A QSAR for the Mutagenic Potencies of Twelve 2-Amino-trimethylimidazopyridine Isomers: Structural, Quantum Chemical,and Hydropathic Factors

An isomeric series of heterocyclic amines related to one found in heated muscle meats was investigated for properties that predict their measured mutagenic potency. Eleven of the 12 possible 2-amino-trimethylimidazopyridine (TMIP) isomers were tested for mutagenic potency in the Ames/Salmonella test with bacterial strain TA98, and resulted in a 600-fold range in potency. Structural, quantum chemical and hydropathic data were calculated on the parent molecules and the corresponding nitrenium ions of all of the tested isomers to establish models for predicting the potency of the unknown isomer. The regression model accounting for the largest fraction of the total variance in mutagenic potency contains four predictor variables: dipole moment, a measure of the gap between amine LUMO and HOMO energies, percent hydrophilic surface, and energy of amine LUMO. The most important determinants of high mutagenic potency in these amines are: (1) a small dipole moment, (2) the combination of b-face ring fusion and N3-methyl group, and (3) a lower calculated energy of the {pi} electron system. Based on predicted potency from the average of five models, the isomer not yet synthesized and tested is expected to have a mutagenic potency of 0.84 revertants/{micro}g in test strain TA98.
Date: April 23, 2005
Creator: Knize, M G; Hatch, F T; Tanga, M J; Lau, E V & Colvin, M E
Object Type: Article
System: The UNT Digital Library
Reconstructing Past Ocean Salinity ((delta)18Owater) (open access)

Reconstructing Past Ocean Salinity ((delta)18Owater)

Temperature and salinity are two of the key properties of ocean water masses. The distribution of these two independent but related characteristics reflects the interplay of incoming solar radiation (insolation) and the uneven distribution of heat loss and gain by the ocean, with that of precipitation, evaporation, and the freezing and melting of ice. Temperature and salinity to a large extent, determine the density of a parcel of water. Small differences in temperature and salinity can increase or decrease the density of a water parcel, which can lead to convection. Once removed from the surface of the ocean where 'local' changes in temperature and salinity can occur, the water parcel retains its distinct relationship between (potential) temperature and salinity. We can take advantage of this 'conservative' behavior where changes only occur as a result of mixing processes, to track the movement of water in the deep ocean (Figure 1). The distribution of density in the ocean is directly related to horizontal pressure gradients and thus (geostrophic) ocean currents. During the Quaternary when we have had systematic growth and decay of large land based ice sheets, salinity has had to change. A quick scaling argument following that of Broecker and Peng …
Date: November 23, 2005
Creator: Guilderson, T. P. & Pak, D. K.
Object Type: Book
System: The UNT Digital Library
Development of the Table of Initial Isolation Distances and Protective Action Distances for the 2004 Emergency Response Guidebook. (open access)

Development of the Table of Initial Isolation Distances and Protective Action Distances for the 2004 Emergency Response Guidebook.

This report provides technical documentation for values in the Table of Initial Isolation and Protective Action Distances (PADs) in the 2004 Emergency Response Guidebook (ERG2004). The objective for choosing the PADs specified in the ERG2004 is to balance the need to adequately protect the public from exposure to potentially harmful substances against the risks and expenses that could result from overreacting to a spill. To quantify this balance, a statistical approach is adopted, whereby the best available information is used to conduct an accident scenario analysis and develop a set of up to 1,000,000 hypothetical incidents. The set accounts for differences in containers types, incident types, accident severity (i.e., amounts released), locations, times of day, times of year, and meteorological conditions. Each scenario is analyzed using detailed emission rate and atmospheric dispersion models to calculate the downwind chemical concentrations from which a 'safe distance' is determined. The safe distance is defined as the distance downwind from the source at which the chemical concentration falls below health protection criteria. The American Industrial Hygiene Association's Emergency Response Planning Guideline Level 2 (ERPG-2) or equivalent is the health criteria used. The statistical sample of safe distance values for all incidents considered in the …
Date: September 23, 2005
Creator: Brown, D. F.; Freeman, W. A.; Carhart, R. A.; Krumpolc, M.; Sciences, Decision and Information & Chicago, Univ. of Illinois at
Object Type: Report
System: The UNT Digital Library
National Register Eligibility Evaluation of the East Area, Argonne National Laaboratory-East Dupage County, Illinois. (open access)

National Register Eligibility Evaluation of the East Area, Argonne National Laaboratory-East Dupage County, Illinois.

Pursuant to Sections 106 and 110 of the National Historic Preservation Act Argonne National Laboratory-East (ANL-E) has completed an evaluation of buildings located within the East Area to determine whether any of these buildings meet the eligibility criteria for listing on the National Register of Historic Places (NRHP). Several buildings within the East Area are scheduled for demolition during fiscal years 1999-2000 (Buildings 4, 5, and 6 and possibly Buildings 26, 27, and 28).
Date: September 23, 2005
Creator: Wescott, K. L.; O'Rourke, D. J. & Assessment, Environmental
Object Type: Report
System: The UNT Digital Library
FROM THE ISR TO RHIC - MEASUREMENTS OF HARD-SCATTERING AND JETS USING INCLUSIVE SINGLE PARTICLE PRODUCTION AND 2-PARTICLE CORRELATIONS. (open access)

FROM THE ISR TO RHIC - MEASUREMENTS OF HARD-SCATTERING AND JETS USING INCLUSIVE SINGLE PARTICLE PRODUCTION AND 2-PARTICLE CORRELATIONS.

Hard scattering in p-p collisions, discovered at the CERN ISR in 1972 by the method of leading particles, proved that the partons of Deeply Inelastic Scattering strongly interacted with each other. Further ISR measurements utilizing inclusive single or pairs of hadrons established that high p{sub T} particles are produced from states with two roughly back-to-back jets which are the result of scattering of constituents of the nucleons as described by Quantum Chromodynamics (QCD), which was developed during the course of these measurements. These techniques, which are the only practical method to study hard-scattering and jet phenomena in Au+Au central collisions at RHIC energies, are reviewed, as an introduction to present RHIC measurements.
Date: April 23, 2005
Creator: Tannenbaum, M. J.
Object Type: Article
System: The UNT Digital Library
Foaming of E-Glass II (Report for G Plus Project for PPG) (open access)

Foaming of E-Glass II (Report for G Plus Project for PPG)

In a previous study, the effect of the furnace atmosphere on E glass foaming was investigated with the specific goal to understand the impact of increased water content on foaming in oxy-fired furnaces. The present study extended the previous study and focused on the effect of glass batch chemical composition on E-glass foaming. The present study also included reruns of foam tests performed in a previous study, which resulted in the same trend: the foaming extent increased nearly linearly with the heating rate and no foam was produced when CO2 + 55% H2O atmosphere was introduced at 300°C. It was shown that the lack of foaming in the test with CO2 + 55% H2O atmosphere introduced at 300°C was caused by a loss of sulfate at T <1250°C because of higher water content at the early stages of melting. The tests with new batches in the present study showed that replacing quicklime with limestone tend to decrease foaming, possibly caused by increased sulfate loss during early stages of melting in the batch with limestone. The batches where Na2SO4 was replaced with NaNO3, NaNO3 + CeO2, or CeO2, produced only very limited foaming regardless of the replacing components. As expected, the …
Date: September 23, 2005
Creator: Kim, Dong-Sang; Portch, Matthew P.; Matyas, Josef; Hrma, Pavel R. & Pilon, Laurent
Object Type: Report
System: The UNT Digital Library
Exploratory Simulation Studies of Caprock Alteration Induced byStorage of CO2 in Depleted Gas Reservoirs (open access)

Exploratory Simulation Studies of Caprock Alteration Induced byStorage of CO2 in Depleted Gas Reservoirs

This report presents numerical simulations of isothermalreactive flows which might be induced in the caprock of an Italiandepleted gas reservoir by the geological sequestration of carbon dioxide.Our objective is to verify that CO2 geological disposal activitiesalready planned for the study area are safe and do not induce anyundesired environmental impact.Gas-water-rock interactions have beenmodelled under two different intial conditions, i.e., assuming that i)caprock is perfectly sealed, or ii) partially fractured. Field conditionsare better approximated in terms of the "sealed caprock model". Thefractured caprock model has been implemented because it permits toexplore the geochemical beahvior of the system under particularly severeconditions which are not currently encountered in the field, and then todelineate a sort of hypothetical maximum risk scenario.Major evidencessupporting the assumption of a sealed caprock stem from the fact that nogas leakages have been detected during the exploitation phase, subsequentreservoir repressurization due to the ingression of a lateral aquifer,and during several cycles of gas storage in the latest life of reservoirmanagement.An extensive program of multidisciplinary laboratory tests onrock properties, geochemical and microseismic monitoring, and reservoirsimulation studies is underway to better characterize the reservoir andcap-rock behavior before the performance of a planned CO2 sequestrationpilot test.In our models, fluid flow and mineral alteration …
Date: November 23, 2005
Creator: Gherardi, Fabrizio; Xu, Tianfu & Pruess, Karsten
Object Type: Report
System: The UNT Digital Library
Contaminant Uptake and Demography of the Loggerhead Shrike (Lanius ludovicianus) at the Lawrence Livermore National Laboratory, Site 300 (open access)

Contaminant Uptake and Demography of the Loggerhead Shrike (Lanius ludovicianus) at the Lawrence Livermore National Laboratory, Site 300

Concentrations of eleven potential environmental contaminants (metals) in the blood and retrice feathers of fledged-Hatch Year and adult loggerhead shrikes (Lanius ludovicianus) were examined at Lawrence Livermore National Laboratory's Site 300 and a control site, in San Joaquin and Contra Costa Counties, California. The purpose of this pilot study was to determine, through non-lethal means, if loggerhead shrikes are exposed to metals at Site 300 and whether specific demographic variables (i.e., clutch size, fledgling success, etc.) are affected. Loggerhead shrikes at Site 300 had higher blood concentrations of metals, especially birds on the west side of the site, when compared to control site birds. Metal concentrations in the feathers of control site birds tended to be higher than Site 300 shrikes. Blood concentrations of metals in loggerhead shrikes from both Site 300 and the control site were well below the Most Tolerant Dietary Level (MTDL) for domestic birds for all metals except selenium. Clutch size was similar to other populations but one deformed embryo was discovered in a failed egg. The results of this pilot study suggest further work is needed to understand possible synergistic effects related to other contaminants of concern found at Site 300 and overall population variability.
Date: February 23, 2005
Creator: van Hattem, M G & Santolo, G
Object Type: Report
System: The UNT Digital Library
Young organic matter as a source of carbon dioxide outgassing from Amazonian rivers (open access)

Young organic matter as a source of carbon dioxide outgassing from Amazonian rivers

Rivers are generally supersaturated with respect to carbon dioxide, resulting in large gas evasion fluxes that can be a significant component of regional net carbon budgets. Amazonian rivers were recently shown to outgas more than ten times the amount of carbon exported to the ocean in the form of total organic carbon or dissolved inorganic carbon. High carbon dioxide concentrations in rivers originate largely from in situ respiration of organic carbon, but little agreement exists about the sources or turnover times of this carbon. Here we present results of an extensive survey of the carbon isotope composition ({sup 13}C and {sup 14}C) of dissolved inorganic carbon and three size-fractions of organic carbon across the Amazonian river system. We find that respiration of contemporary organic matter (less than 5 years old) originating on land and near rivers is the dominant source of excess carbon dioxide that drives outgassing in mid-size to large rivers, although we find that bulk organic carbon fractions transported by these rivers range from tens to thousands of years in age. We therefore suggest that a small, rapidly cycling pool of organic carbon is responsible for the large carbon fluxes from land to water to atmosphere in the …
Date: June 23, 2005
Creator: Mayorga, E; Aufdenkampe, A K; Masiello, C A; Krusche, A V; Hedges, J I; Quay, P D et al.
Object Type: Article
System: The UNT Digital Library
Neutrino Factory Accelerator R&D: Status and Priorities (open access)

Neutrino Factory Accelerator R&D: Status and Priorities

This paper summarizes the status of worldwide Neutrino Factory R&amp;D efforts. Activities are categorized as simulations, component development, and system tests. An indication of R&amp;D tasks that remain to be accomplished is also given.
Date: August 23, 2005
Creator: Zisman, Michael S.
Object Type: Article
System: The UNT Digital Library
OpWise: Operons aid the identification of differentially expressedgenes in bacterial microarray experiments (open access)

OpWise: Operons aid the identification of differentially expressedgenes in bacterial microarray experiments

Differentially expressed genes are typically identified by analyzing the variation between replicate measurements. These procedures implicitly assume that there are no systematic errors in the data even though several sources of systematic error are known. Results-OpWise estimates the amount of systematic error in bacterial microarray data by assuming that genes in the same operon have matching expression patterns. OpWise then performs a Bayesian analysis of a linear model to estimate significance. In simulations, OpWise corrects for systematic error and is robust to deviations from its assumptions. In several bacterial data sets, significant amounts of systematic error are present, and replicate-based approaches overstate the confidence of the changers dramatically, while OpWise does not. Finally, OpWise can identify additional changers by assigning genes higher confidence if they are consistent with other genes in the same operon. Although microarray data can contain large amounts of systematic error, operons provide an external standard and allow for reasonable estimates of significance. OpWise is available at http://microbesonline.org/OpWise.
Date: November 23, 2005
Creator: Price, Morgan N.; Arkin, Adam P. & Alm, Eric J.
Object Type: Article
System: The UNT Digital Library
Aging and Phase Stability of Alloy 22 Welds FY05 SUMMARY REPORT (open access)

Aging and Phase Stability of Alloy 22 Welds FY05 SUMMARY REPORT

Evaluation of the fabrication processes involved in the manufacture of waste containers is important as these processes can have an effect on the metallurgical structure of an alloy. Since material properties such as strength, toughness, aging kinetics and corrosion resistance are all dependent on the microstructure, it is important that prototypes be built and evaluated for processing effects on the performance of the material. Of particular importance are welds, which have an as-cast microstructure with chemical segregation and precipitation of complex phases resulting from the welding process. The work presented in this report focuses on the effects of processes such as solution annealing, stress mitigation, and welding on the kinetics of precipitation and corrosion properties. For a waste package lifetime of thousands of years, it is impossible to test directly in the laboratory the behavior of Alloy 22 under expected repository conditions. The changes that may occur in these materials must be accelerated. For phase-stability studies this is achieved by accelerating the phase transformations by increasing test temperatures above those anticipated in the proposed repository. For these reasons, Alloy 22 characterization specimens are currently being aged at Lawrence Livermore National Laboratory (LLNL) Aging Facilities for times from 1 hour to …
Date: November 23, 2005
Creator: Torres, S G; El-Dasher, B; McGregor, M; Etien, R; Edgecumbe, T S; Gdowski, G et al.
Object Type: Report
System: The UNT Digital Library
Monitored Energy Performance of Electrochromic Windows Controlledfor Daylight and Visual Comfort (open access)

Monitored Energy Performance of Electrochromic Windows Controlledfor Daylight and Visual Comfort

A 20-month field study was conducted to measure the energy performance of south-facing large-area tungsten-oxide absorptive electrochromic (EC) windows with a broad switching range in a private office setting. The EC windows were controlled by a variety of means to bring in daylight while minimizing window glare. For some cases, a Venetian blind was coupled with the EC window to block direct sun. Some tests also involved dividing the EC window wall into zones where the upper EC zone was controlled to admit daylight while the lower zone was controlled to prevent glare yet permit view. If visual comfort requirements are addressed by EC control and Venetian blinds, a 2-zone EC window configuration provided average daily lighting energy savings of 10 {+-} 15% compared to the reference case with fully lowered Venetian blinds. Cooling load reductions were 0 {+-} 3%. If the reference case assumes no daylighting controls, lighting energy savings would be 44 {+-} 11%. Peak demand reductions due to window cooling load, given a critical demand-response mode, were 19-26% maximum on clear sunny days. Peak demand reductions in lighting energy use were 0% or 72-100% compared to a reference case with and without daylighting controls, respectively. Lighting energy …
Date: September 23, 2005
Creator: Lee, Eleanor S.; DiBartolomeo, Dennis L.; Klems, Joseph; Yazdanian, Mehry & Selkowitz, Stephen E.
Object Type: Article
System: The UNT Digital Library
Evidence for the Spectroscopic Signature of Aging in (delta)-Pu(Ga) (open access)

Evidence for the Spectroscopic Signature of Aging in (delta)-Pu(Ga)

Plutonium, because of its radioactive nature, ages from the 'inside out' by means of self-irradiation damage and thus produces nanoscale internal defects. The self-irradiation induced defects come in the form of Frenkel-type defects (vacancies and self-interstitial atoms), helium in-growth, and defect clusters. At present there are neither experimental nor theoretical models describing the changes in the electronic structure caused by the aging in Pu. This fact appears to be associated primarily with the absence of reasonably convincing spectroscopic evidence of the changes. This paper demonstrates that Resonant Photoemission, a variant of Photoelectron Spectroscopy, has strong sensitivity to aging of Pu samples. The spectroscopic results are correlated with an extra-atomic screening model [1], and are shown to be the fingerprint of mesoscopic or nanoscale internal damage in the Pu physical structure. This means that a spectroscopic signature of internal damage due to aging in Pu has been established.
Date: November 23, 2005
Creator: Chung, B. W.; Schwartz, A. J.; Ebbinghaus, B. B.; Fluss, M. J.; Haslam, J. J.; Blobaum, K. M. et al.
Object Type: Article
System: The UNT Digital Library
Reference Material for Radionuclides in Sediment, IAEA-384 (Fangataufa Lagoon Sediment) (open access)

Reference Material for Radionuclides in Sediment, IAEA-384 (Fangataufa Lagoon Sediment)

The IAEA Marine Environment Laboratory (IAEA-MEL) in Monaco has conducted intercomparison exercises on radionuclides in marine samples for many years as part of its contribution to the IAEA's program of Analytical Quality Control Services (AQCS). An important part of the AQCS program has been a production of Reference Materials (RMs) and their provision to radioanalytical laboratories. The RMs have been developed for different marine matrices (sediment, water, biota), with accuracy and precision required for the present state of the art of radiometrics and mass spectrometry methods. The RMs have been produced as the final products of world-wide intercomparison exercises organized during last 30 years. A total of 44 intercomparison exercises were undertaken and 39 RMs were produced for radionuclides in the marine environment. All required matrices (seawater, biota, sediment) have been covered with radionuclide concentrations ranging from typical environmental levels to elevated levels affected by discharges from nuclear reprocessing plants. The long-term availability of RMs (over 10 years) requires the use of very specific techniques to collect and pretreat large quantities of material (e.g., in excess of 100 kg) in order to ensure sample stability and homogenization of any analytes of interest. The production of a RM is therefore a …
Date: September 23, 2005
Creator: Povinec, P. P.; Pham, M. K.; Barci-Funel, G.; Bojanawski, R.; Boshkova, T.; Burnett, W. et al.
Object Type: Article
System: The UNT Digital Library
Results of a Si/Cdte Compton Telescope (open access)

Results of a Si/Cdte Compton Telescope

We have been developing a semiconductor Compton telescope to explore the universe in the energy band from several tens of keV to a few MeV. We use a Si strip and CdTe pixel detector for the Compton telescope to cover an energy range from 60 keV. For energies above several hundred keV, the higher efficiency of CdTe semiconductor in comparison with Si is expected to play an important role as an absorber and a scatterer. In order to demonstrate the spectral and imaging capability of a CdTe-based Compton Telescope, we have developed a Compton telescope consisting of a stack of CdTe pixel detectors as a small scale prototype. With this prototype, we succeeded in reconstructing images and spectra by solving the Compton equation from 122 keV to 662 keV. The energy resolution (FWHM) of reconstructed spectra is 7.3 keV at 511 keV and 3.1 keV at 122 keV, respectively. The angular resolution obtained at 511 keV is measured to be 12.2{sup o}(FWHM).
Date: September 23, 2005
Creator: Oonuki, Kousuke; Tanaka, Takaaki; Watanabe, Shin; Takeda, Shin'ichiro; Nakazawa, Kazuhiro; Mitani, Takefumi et al.
Object Type: Article
System: The UNT Digital Library
Isotopic Generation and Confirmation of the PWR Application Model (open access)

Isotopic Generation and Confirmation of the PWR Application Model

None
Date: May 23, 2005
Creator: Radulesa, H.R.
Object Type: Report
System: The UNT Digital Library
Last Annotation of Fugu rubripes at JGI (open access)

Last Annotation of Fugu rubripes at JGI

None
Date: November 23, 2005
Creator: Salamov, A.; Putnam, N.; Terry, A.; Grigoriev, I.; Rokhsar, D.; Loh, E. et al.
Object Type: Article
System: The UNT Digital Library
Mechanical Assessment of the Waste Package Subject to Vibtatory Ground Motion (open access)

Mechanical Assessment of the Waste Package Subject to Vibtatory Ground Motion

None
Date: August 23, 2005
Creator: Lin, M.; Gerhard, M.; Damjanac, B.; Mullin, M. & Gross, M.
Object Type: Report
System: The UNT Digital Library
Development of an Explosive Bonding Process for Producing High Strength Bonds between Niobium and 6061-T651 Aluminum (open access)

Development of an Explosive Bonding Process for Producing High Strength Bonds between Niobium and 6061-T651 Aluminum

An explosive bonding procedure for joining 9.5 mm thick niobium plate to 203 mm thick 6061-T651 Al plate has been developed in order to maximize the bond tensile and impact strengths and the amount of bonded material across the surface of the plate. This procedure improves upon previous efforts, in which the 9.5 mm thick niobium plate is bonded directly to 6061-T4 Al plate. In this improved procedure, thin Nb and Al interlayers are explosively clad between the thicker niobium and aluminum plates. Bonds produced using these optimized parameters display a tensile strength of approximately 255 MPa and an impact strength per unit area of approximately 0.148 J/mm{sup 2}. Specialized mechanical testing geometries and procedures are required to measure these bond properties because of the unique bond geometry. In order to ensure that differences in the thermal expansion coefficients of aluminum and niobium do not adversely affect the bond strength, the effects of thermal cycling at temperatures between -22 C and 45 C on the mechanical properties of these bonds have also been investigated by testing samples in both the as-received and thermal cycled conditions. Based on the results obtained from this series of mechanical tests, thermal cycling is shown …
Date: September 23, 2005
Creator: Palmer, T A; Elmer, J W; Brasher, D; Butler, D & Riddle, R
Object Type: Article
System: The UNT Digital Library
CO2 Sequestration and Recycle by Photosynthesis (open access)

CO2 Sequestration and Recycle by Photosynthesis

Hydrocarbon synthesis from photocatalytic reactions of CO{sub 2} and H{sub 2}O over various catalysts has been studied by UV-visible light. The quantum efficiencies suggest that Pd/TiO{sub 2} sol gel exhibits the highest activity for hydrocarbon synthesis from photocatalytic reactions. The in situ IR was able to monitor the adsorbed hydrocarbon species. The UV-visible, IR spectroscopy and XRD techniques were used to characterize the catalysts to obtain the information of properties of the process and catalyst before/after reaction. The UV-visible spectroscopy provides the information about the surface band gap energy of each catalyst. In situ UV-visible studies reveals that TiO{sub 2}-supported catalysts require the higher energy (i.e. shorter wavelength) to pass through the water-thin film deposited on the surface to activate the photocatalytic reaction. XRD data show there is changes in the crystal structure of TiO{sub 2} sol gel from photon energy during photo reaction. Studies on photocatalytic oxidation of methylene blue show that the photocatalytic oxidation rate is significantly higher than the photocatalytic reduction rate on TiO{sub 2} based catalysts. The information from this study can lead to a better understanding of the nature of the catalysts and photoreaction processes, which might provide the information to develop better catalysts and …
Date: September 23, 2005
Creator: Chuang, Steven
Object Type: Report
System: The UNT Digital Library