Direct-Cooled Power Electronics Substrate (open access)

Direct-Cooled Power Electronics Substrate

The goal of the Direct-Cooled Power Electronics Substrate project is to reduce the size and weight of the heat sink for power electronics used in hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). The concept proposed in this project was to develop an innovative power electronics mounting structure, model it, and perform both thermal and mechanical finite-element analysis (FEA). This concept involved integrating cooling channels within the direct-bonded copper (DBC) substrate and strategically locating these channels underneath the power electronic devices. This arrangement would then be directly cooled by water-ethylene glycol (WEG), essentially eliminating the conventional heat sink and associated heat flow path. The concept was evaluated to determine its manufacturability, its compatibility with WEG, and the potential to reduce size and weight while directly cooling the DBC and associated electronics with a coolant temperature of 105 C. This concept does not provide direct cooling to the electronics, only direct cooling inside the DBC substrate itself. These designs will take into account issues such as containment of the fluid (separation from the electronics) and synergy with the whole power inverter design architecture. In FY 2008, mechanical modeling of substrate and inverter core designs as well as thermal and …
Date: December 23, 2008
Creator: Wiles, R.; Ayers, C. & Wereszczak, A.
Object Type: Report
System: The UNT Digital Library
FINAL REPORT: A Study of the Abundance and 13C/12C Ratio of Atmospheric Carbon Dioxide to Advance the Scientific Understanding of Terrestrial Processes Regulating the GCC (open access)

FINAL REPORT: A Study of the Abundance and 13C/12C Ratio of Atmospheric Carbon Dioxide to Advance the Scientific Understanding of Terrestrial Processes Regulating the GCC

The main objective of this project was to continue research to develop carbon cycle relationships related to the land biosphere based on remote measurements of atmospheric CO2 concentration and its isotopic composition. The project continued time-series observations of atmospheric carbon dioxide and isotopic composition begun by Charles D. Keeling at remote sites, including Mauna Loa, the South Pole, and eight other sites. The program also included the development of methods for measuring radiocarbon content in the collected CO2 samples and carrying out radiocarbon measurements in collaboration with Tom Guilderson of Lawrence Berkeley National Laboratory (LLNL). The radiocarbon measurements can provide complementary information on carbon exchange rates with the land and oceans and emissions from fossil-fuel burning. Using models of varying complexity, the concentration and isotopic measurements were used to establish estimates of the spatial and temporal variations in the net CO2 exchange with the atmosphere, the storage of carbon in the land and oceans, and variable isotopic discrimination of land plants.
Date: December 23, 2008
Creator: Keeling, R. F. & Piper, S. C.
Object Type: Report
System: The UNT Digital Library
Physical limits for high ion charge states in pulsed discharges in vacuum (open access)

Physical limits for high ion charge states in pulsed discharges in vacuum

Short-pulse, high-current discharges in vacuum were investigated with the goal to maximize the ion charge state number. In a direct extension of previous work [Appl. Phys. Lett. 92, 041502 (2008)], the role of pulse length, rate of current rise, and current amplitude was studied. For all experimental conditions, the usable (extractable) mean ion charge state could not be pushed beyond 7+. Instead, a maximum of the mean ion charge state (about 6+ to 7+ for most cathode materials) was found for a power of 2-3 MW dissipated in the discharge gap. The maximum is the result of two opposing processes that occur when the power is increased: (i) the formation of higher ion charge states, and (ii) a greater production of neutrals (both metal and non-metal), which reduces the charge state via charge exchange collisions.
Date: December 23, 2008
Creator: Yushkov, Georgy & Anders, Andre
Object Type: Article
System: The UNT Digital Library
Post-Closure Report for Closed Resource Conservation and Recovery Act Corrective Action Units, Nevada Test Site, Nevada, For Fiscal Year 2008 (October 2007-September 2008) (open access)

Post-Closure Report for Closed Resource Conservation and Recovery Act Corrective Action Units, Nevada Test Site, Nevada, For Fiscal Year 2008 (October 2007-September 2008)

This report is the first combined annual report for post-closure activities for the following closed Corrective Action Units (CAUs): • CAU 90, Area 2 Bitcutter Containment • CAU 91, Area 3 U-3fi Injection Well • CAU 92, Area 6 Decon Pond Facility • CAU 110, Area 3 WMD U-3ax/bl Crater • CAU 112, Area 23 Hazardous Waste Trenches The locations of the sites are shown in Figure 1. This report covers fiscal year (FY) 2008 (October 2007–September 2008). Because this is the first combined annual report for these CAUs, this report only covers the period not covered in the previous annual report for each CAU. For example, the last report submitted for CAU 91 covered the period January 2007–December 2007; therefore, this report only covers the remainder of FY2008 (January 2008–September 2008) for CAU 91. The post-closure requirements for these sites are described in Resource Conservation and Recovery Act Permit Number NEV HW0021 and summarized in each CAU-specific section in Section 1.0 of this report. Site inspections are conducted semiannually at CAUs 90 and 91 and quarterly at CAUs 92, 110, and 112. Additional inspections are conducted at CAU 92 if precipitation occurs in excess of 0.50 inches in a …
Date: December 23, 2008
Creator: National Security Technologies, LLC
Object Type: Report
System: The UNT Digital Library
Report on the Depth Requirements for a Massive Detector at Homestake (open access)

Report on the Depth Requirements for a Massive Detector at Homestake

This report provides the technical justification for locating a large detector underground in a US based Deep Underground Science and Engineering Laboratory. A large detector with a fiducial mass greater than 100 kTon will most likely be a multipurpose facility. The main physics justification for such a device is detection of accelerator generated neutrinos, nucleon decay, and natural sources of neutrinos such as solar, atmospheric and supernova neutrinos. The requirement on the depth of this detector will be guided by the rate of signals from these sources and the rate of backgrounds from cosmic rays over a very wide range of energies (from solar neutrino energies of 5 MeV to high energies in the range of hundreds of GeV). For the present report, we have examined the depth requirement for a large water Cherenkov detector and a liquid argon time projection chamber. There has been extensive previous experience with underground water Cherenkov detectors such as IMB, Kamioka, and most recently, Super-Kamiokande which has a fiducial mass of 22 kTon and a total mass of 50 kTon at a depth of 2700 meters-water-equivalent in a mountain. Projections for signal and background capability for a larger and deeper(or shallower) detectors of this …
Date: December 23, 2008
Creator: Kadel, Richard W.; Bernstein, Adam; Blucher, Edward; Cline, David B.; Diwan, Milind V.; Fleming, Bonnie et al.
Object Type: Report
System: The UNT Digital Library
Tissue architecture and function: dynamic reciprocity via extra- and intra-cellular matrices (open access)

Tissue architecture and function: dynamic reciprocity via extra- and intra-cellular matrices

Mammary gland development, functional differentiation, and homeostasis are orchestrated and sustained by a balance of biochemical and biophysical cues from the organ's microenvironment. The three-dimensional microenvironment of the mammary gland, predominantly 'encoded' by a collaboration between the extracellular matrix (ECM), hormones, and growth factors, sends signals from ECM receptors through the cytoskeletal intracellular matrix to nuclear and chromatin structures resulting in gene expression; the ECM in turn is regulated and remodeled by signals from the nucleus. In this chapter, we discuss how coordinated ECM deposition and remodeling is necessary for mammary gland development, how the ECM provides structural and biochemical cues necessary for tissue-specific function, and the role of the cytoskeleton in mediating the extra - to intracellular dialogue occurring between the nucleus and the microenvironment. When operating normally, the cytoskeletal-mediated dynamic and reciprocal integration of tissue architecture and function directs mammary gland development, tissue polarity, and ultimately, tissue-specific gene expression. Cancer occurs when these dynamic interactions go awry for an extended time.
Date: December 23, 2008
Creator: Xu, Ren; Boudreau, Aaron & Bissell, Mina J
Object Type: Article
System: The UNT Digital Library
A comparative simulation study of coupled THM processes and their effect on fractured rock permeability around nuclear waste repositories (open access)

A comparative simulation study of coupled THM processes and their effect on fractured rock permeability around nuclear waste repositories

This paper presents an international, multiple-code, simulation study of coupled thermal, hydrological, and mechanical (THM) processes and their effect on permeability and fluid flow in fractured rock around heated underground nuclear waste emplacement drifts. Simulations were conducted considering two types of repository settings: (a) open emplacement drifts in relatively shallow unsaturated volcanic rock, and (b) backfilled emplacement drifts in deeper saturated crystalline rock. The results showed that for the two assumed repository settings, the dominant mechanism of changes in rock permeability was thermal-mechanically-induced closure (reduced aperture) of vertical fractures, caused by thermal stress resulting from repository-wide heating of the rock mass. The magnitude of thermal-mechanically-induced changes in permeability was more substantial in the case of an emplacement drift located in a relatively shallow, low-stress environment where the rock is more compliant, allowing more substantial fracture closure during thermal stressing. However, in both of the assumed repository settings in this study, the thermal-mechanically-induced changes in permeability caused relatively small changes in the flow field, with most changes occurring in the vicinity of the emplacement drifts.
Date: October 23, 2008
Creator: Rutqvist, Jonny; Barr, Deborah; Birkholzer, Jens T.; Fujisaki, Kiyoshi; Kolditz, Olf; Liu, Quan-Shen et al.
Object Type: Article
System: The UNT Digital Library
Extracellular matrix control of mammary gland morphogenesis and tumorigenesis: insights from imaging (open access)

Extracellular matrix control of mammary gland morphogenesis and tumorigenesis: insights from imaging

The extracellular matrix (ECM), once thought to solely provide physical support to a tissue, is a key component of a cell's microenvironment responsible for directing cell fate and maintaining tissue specificity. It stands to reason, then, that changes in the ECM itself or in how signals from the ECM are presented to or interpreted by cells can disrupt tissue organization; the latter is a necessary step for malignant progression. In this review, we elaborate on this concept using the mammary gland as an example. We describe how the ECM directs mammary gland formation and function, and discuss how a cell's inability to interpret these signals - whether as a result of genetic insults or physicochemical alterations in the ECM - disorganizes the gland and promotes malignancy. By restoring context and forcing cells to properly interpret these native signals, aberrant behavior can be quelled and organization re-established. Traditional imaging approaches have been a key complement to the standard biochemical, molecular, and cell biology approaches used in these studies. Utilizing imaging modalities with enhanced spatial resolution in live tissues may uncover additional means by which the ECM regulates tissue structure, on different length scales, through its pericellular organization (short-scale) and by biasing …
Date: October 23, 2008
Creator: Ghajar, Cyrus M & Bissell, Mina J
Object Type: Article
System: The UNT Digital Library
Large File System Backup: NERSC Global File System Experience (open access)

Large File System Backup: NERSC Global File System Experience

NERSC's Global File system (NGF), accessible from all compute systems at NERSC, holds files and data from many scientific projects. A full backup of this file system to our High Performance Storage System (HPSS) is performed periodically. Disk storage usage by projects at NERSC has grown seven fold over a two year period, from ~;;20TB in June 2006 to ~;;140 TB in June 2008. The latest full backup took about 13 days and more than 200 T10k tape cartridges (.5 TB capacity). Petabyte file systems are becoming a reality in the next few years and the existing utilities are already strained in handling backup tasks.
Date: October 23, 2008
Creator: Mokhtarani, Akbar; Andrews, Matthew; Hick, Jason & Kramer, William
Object Type: Report
System: The UNT Digital Library
MATRIX 2 RESULTS OF THE FY07 ENHANCED DOE HIGH-LEVEL WASTE MELTER THROUGHPUT STUDIES AT SRNL (open access)

MATRIX 2 RESULTS OF THE FY07 ENHANCED DOE HIGH-LEVEL WASTE MELTER THROUGHPUT STUDIES AT SRNL

High-level waste (HLW) throughput (i.e., the amount of waste processed per unit time) is a function of two critical parameters: waste loading (WL) and melt rate. For the Waste Treatment and Immobilization Plant (WTP) at the Hanford Site and the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS), increasing HLW throughput would significantly reduce the overall mission life cycle costs for the Department of Energy (DOE). The objective of this study was to generate supplemental validation data that could be used to determine the applicability of the current liquidus temperature (TL) model to expanded DWPF glass composition regions of interest based on higher WLs. Two specific flowsheets were used in this study to provide such insight: (1) Higher WL glasses (45 and 50%) based on future sludge batches that have (and have not) undergone the Al-dissolution process. (2) Coupled operations supported by the Salt Waste Processing Facility (SWPF), which increase the TiO{sub 2} concentration in glass to greater than 2 wt%. Glasses were also selected to address technical issues associated with Al{sub 2}O{sub 3} solubility, nepheline formation, and homogeneity issues for coupled operations. A test matrix of 28 glass compositions was developed to provide insight into these …
Date: October 23, 2008
Creator: Raszewski, F; Tommy Edwards, T & David Peeler, D
Object Type: Report
System: The UNT Digital Library
Multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories (open access)

Multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories

This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element, finite element, finite difference, particle mechanics, and elastoplastic cellular automata methods. The simulation results indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure and permeability changes during the first 100 years (i.e., after emplacement and drift closure). Moreover, the results indicate that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and thermal stress, whereas such time-dependency is insignificant after peak temperature, because decreasing thermal stress.
Date: October 23, 2008
Creator: Rutqvist, J.; Backstrom, A.; Chijimatsu, M.; Feng, X. T.; Pan, P. Z.; Hudson, J. et al.
Object Type: Article
System: The UNT Digital Library
National Energy Research Scientific Computing Center 2007 Annual Report (open access)

National Energy Research Scientific Computing Center 2007 Annual Report

This report presents highlights of the research conducted on NERSC computers in a variety of scientific disciplines during the year 2007. It also reports on changes and upgrades to NERSC's systems and services aswell as activities of NERSC staff.
Date: October 23, 2008
Creator: Hules, John A.; Bashor, Jon; Wang, Ucilia; Yarris, Lynn & Preuss, Paul
Object Type: Report
System: The UNT Digital Library
Alpha Channeling in a Rotating Plasma (open access)

Alpha Channeling in a Rotating Plasma

The wave-particle α-channeling effect is generalized to include rotating plasma. Specifically, radio frequency waves can resonate with α particles in a mirror machine with E × B rotation to diffuse the α particles along constrained paths in phase space. Of major interest is that the α-particle energy, in addition to amplifying the RF waves, can directly enhance the rotation energy which in turn provides additional plasma confinement in centrifugal fusion reactors. An ancillary benefit is the rapid removal of alpha particles, which increases the fusion reactivity.
Date: September 23, 2008
Creator: Fisch, Abraham J. Fetterman and Nathaniel J.
Object Type: Report
System: The UNT Digital Library
Coherent Control of Multiphoton Transitions in the Gas and Condensed Phases with Shaped Ultrashort Pulses (open access)

Coherent Control of Multiphoton Transitions in the Gas and Condensed Phases with Shaped Ultrashort Pulses

Controlling laser-molecule interactions has become an integral part of developing devices and applications in spectroscopy, microscopy, optical switching, micromachining and photochemistry. Coherent control of multiphoton transitions could bring a significant improvement of these methods. In microscopy, multi-photon transitions are used to activate different contrast agents and suppress background fluorescence; coherent control could generate selective probe excitation. In photochemistry, different dissociative states are accessed through two, three, or more photon transitions; coherent control could be used to select the reaction pathway and therefore the yield-specific products. For micromachining and processing a wide variety of materials, femtosecond lasers are now used routinely. Understanding the interactions between the intense femtosecond pulse and the material could lead to technologically important advances. Pulse shaping could then be used to optimize the desired outcome. The scope of our research program is to develop robust and efficient strategies to control nonlinear laser-matter interactions using ultrashort shaped pulses in gas and condensed phases. Our systematic research has led to significant developments in a number of areas relevant to the AMO Physics group at DOE, among them: generation of ultrashort phase shaped pulses, coherent control and manipulation of quantum mechanical states in gas and condensed phases, behavior of isolated …
Date: September 23, 2008
Creator: Dantus, Marcos
Object Type: Report
System: The UNT Digital Library
Exact solution of the envelope equations for a matched quadrupole-focused beam in the low space-charged limit (open access)

Exact solution of the envelope equations for a matched quadrupole-focused beam in the low space-charged limit

The Kapchinskij-Vladimirskij equations are widely used to study the evolution of the beam envelopes in a periodic system of quadrupole focusing cells. In this paper, we analyze the case of a matched beam. Our model is analogous to that used by Courant and Snyder [E.D. Courant and H.S. Snyder, Ann. Phys. 3, 1 (1958)]in obtaining a first-order approximate solution for a synchrotron. Here, we treat a linear machine and obtain an exact solution. The model uses a full occupancy, piecewise-constant focusing function and neglects space charge. There are solutions in an infinite number of bands as the focus strength is increased. We show that all these bands are stable. Our explicit results for the phase advance sigma and the envelope a(z) are exact for all phase advances except multiples of 180o, where the behavior is singular. We find that the peak envelope size is minimized at sigma = 90o. Actual operation in the higher bands would require very large, very accurate field strengths and would produce significantly larger envelope excursions.
Date: September 23, 2008
Creator: Anderson, O. A. & LoDestro, L. L.
Object Type: Article
System: The UNT Digital Library
INTERNATIONAL STUDY OF ALUMINUM IMPACTS ON CRYSTALLIZATION IN U.S. HIGH LEVEL WASTE GLASS (open access)

INTERNATIONAL STUDY OF ALUMINUM IMPACTS ON CRYSTALLIZATION IN U.S. HIGH LEVEL WASTE GLASS

The objective of this task was to develop glass formulations for (Department of Energy) DOE waste streams with high aluminum concentrations to avoid nepheline formation while maintaining or meeting waste loading and/or waste throughput expectations as well as satisfying critical process and product performance related constraints. Liquidus temperatures and crystallization behavior were carefully characterized to support model development for higher waste loading glasses. The experimental work, characterization, and data interpretation necessary to meet these objectives were performed among three partnering laboratories: the V.G. Khlopin Radium Institute (KRI), Pacific Northwest National Laboratory (PNNL) and Savannah River National Laboratory (SRNL). Projected glass compositional regions that bound anticipated Defense Waste Processing Facility (DWPF) and Hanford high level waste (HLW) glass regions of interest were developed and used to generate glass compositions of interest for meeting the objectives of this study. A thorough statistical analysis was employed to allow for a wide range of waste glass compositions to be examined while minimizing the number of glasses that had to be fabricated and characterized in the laboratory. The glass compositions were divided into two sets, with 45 in the test matrix investigated by the U.S. laboratories and 30 in the test matrix investigated by KRI. …
Date: September 23, 2008
Creator: Fox, K; David Peeler, D; Tommy Edwards, T; David Best, D; Irene Reamer, I; Phyllis Workman, P et al.
Object Type: Report
System: The UNT Digital Library
The John Deere E diesel Test & Research Project (open access)

The John Deere E diesel Test & Research Project

Three non-road Tier II emissions compliant diesel engines manufactured by John Deere were placed on a durability test plan of 2000 hours each at full load, rated speed (FLRS). The fuel was a blend of 10% fuel ethanol and 90% low sulfur #2 diesel fuel. Seven operational failures involving twenty seven fuel system components occurred prior to completion of the intended test plan. Regulated emissions measured prior to component failure indicated compliance to Tier II certification goals for the observed test experience. The program plan included operating three non-road Tier II diesel engines for 2000 hours each monitoring the regulated emissions at 500 hour intervals for changes/deterioration. The program was stopped prematurely due to number and frequency of injection system failures. The failures and weaknesses observed involved injector seat and valve wear, control solenoid material incompatibility, injector valve deposits and injector high pressure seal cavitation erosion. Future work should target an E diesel fuel standard that emphasizes minimum water content, stability, lubricity, cetane neutrality and oxidation resistance. Standards for fuel ethanol need to require water content no greater than the base diesel fuel standard. Lubricity bench test standards may need new development for E diesel.
Date: September 23, 2008
Creator: Fields, Nathan & Mitchell, William E.
Object Type: Report
System: The UNT Digital Library
MATRIX 1 RESULTS OF THE FY07 ENHANCED DOE HIGH-LEVEL WASTE MELTER THROUGHPUT STUDIES AT SRNL (open access)

MATRIX 1 RESULTS OF THE FY07 ENHANCED DOE HIGH-LEVEL WASTE MELTER THROUGHPUT STUDIES AT SRNL

High-level waste (HLW) throughput (i.e., the amount of waste processed per unit time) is a function of two critical parameters: waste loading (WL) and melt rate. For the Waste Treatment and Immobilization Plant (WTP) at the Hanford Site and the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS), increasing HLW throughput would significantly reduce the overall mission life cycle costs for the Department of Energy (DOE). It has been proposed that a team of glass formulation and processing experts at the Pacific Northwest National Laboratory (PNNL), Savannah River National Laboratory (SRNL), and Vitreous State Laboratory (VSL) at Catholic University of America develop a systematic approach to increase HLW throughput (by increasing WL with minimal or positive impacts on melt rate). Programmatically, this task is aimed at proof-of-principle testing and the development of tools to improve waste loading and melt rate, which will lead to higher waste throughput. The following four specific tasks have been proposed to meet this programmatic objective: (1) Integration and Oversight, (2) Crystal Accumulation Modeling (led by PNNL)/Higher Waste Loading Glasses (led by SRNL), (3) Melt Rate Evaluation and Modeling, and (4) Melter Scale Demonstrations. The details of these tasks can be found in …
Date: September 23, 2008
Creator: Raszewski, F; Tommy Edwards, T & David Peeler, D
Object Type: Report
System: The UNT Digital Library
Proceedings of the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring (open access)

Proceedings of the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring

These proceedings contain papers prepared for the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 23-25 September, 2008 in Portsmouth, Virginia. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States’ capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.
Date: September 23, 2008
Creator: Wetovsky, Marv A; Aguilar-chang, Julio; Arrowsmith, Marie; Arrowsmith, Stephen; Baker, Diane; Begnaud, Michael et al.
Object Type: Article
System: The UNT Digital Library
Reactive Distillation for Esterification of Bio-based Organic Acids (open access)

Reactive Distillation for Esterification of Bio-based Organic Acids

The following is the final report of the three year research program to convert organic acids to their ethyl esters using reactive distillation. This report details the complete technical activities of research completed at Michigan State University for the period of October 1, 2003 to September 30, 2006, covering both reactive distillation research and development and the underlying thermodynamic and kinetic data required for successful and rigorous design of reactive distillation esterification processes. Specifically, this project has led to the development of economical, technically viable processes for ethyl lactate, triethyl citrate and diethyl succinate production, and on a larger scale has added to the overall body of knowledge on applying fermentation based organic acids as platform chemicals in the emerging biorefinery. Organic acid esters constitute an attractive class of biorenewable chemicals that are made from corn or other renewable biomass carbohydrate feedstocks and replace analogous petroleum-based compounds, thus lessening U.S. dependence on foreign petroleum and enhancing overall biorefinery viability through production of value-added chemicals in parallel with biofuels production. Further, many of these ester products are candidates for fuel (particularly biodiesel) components, and thus will serve dual roles as both industrial chemicals and fuel enhancers in the emerging bioeconomy. The …
Date: September 23, 2008
Creator: Fields, Nathan; Miller, Dennis J.; Asthana, Navinchandra S.; Kolah, Aspi K.; Vu, Dung & Lira, Carl T.
Object Type: Report
System: The UNT Digital Library
Remaining Sites Verification Package for the 100-F-44:4, Discovery Pipeline in Silica Gel Pit, Waste Site Reclassification Form 2008-030 (open access)

Remaining Sites Verification Package for the 100-F-44:4, Discovery Pipeline in Silica Gel Pit, Waste Site Reclassification Form 2008-030

The 100-F-44:4, Discovery Pipeline in Silica Gel Pit subsite is located in the 100-FR-1 Operable Unit of the Hanford Site, near the location of the former 110-F Gas Storage Tanks structure. The 100-F-44:4 subsite is a steel pipe discovered October 17, 2004, during trenching to locate the 118-F-4 Silica Gel Pit. Based on visual inspection and confirmatory investigation sampling data, the 100-F-44:4 subsite is a piece of non-hazardous electrical conduit debris. The 100-F-44:4 subsite supports unrestricted future use of shallow zone soil and is protective of groundwater and the Columbia River. No residual contamination exists within the deep zone. Therefore, no deep zone institutional controls are required.
Date: September 23, 2008
Creator: Capron, J. M.
Object Type: Report
System: The UNT Digital Library
The Role of Multiple Transcription Factors In Archaeal Gene Expression (open access)

The Role of Multiple Transcription Factors In Archaeal Gene Expression

Since the inception of this research program, the project has focused on two central questions: What is the relationship between the 'eukaryal-like' transcription machinery of archaeal cells and its counterparts in eukaryal cells? And, how does the archaeal cell control gene expression using its mosaic of eukaryal core transcription machinery and its bacterial-like transcription regulatory proteins? During the grant period we have addressed these questions using a variety of in vivo approaches and have sought to specifically define the roles of the multiple TATA binding protein (TBP) and TFIIB-like (TFB) proteins in controlling gene expression in Haloferax volcanii. H. volcanii was initially chosen as a model for the Archaea based on the availability of suitable genetic tools; however, later studies showed that all haloarchaea possessed multiple tbp and tfb genes, which led to the proposal that multiple TBP and TFB proteins may function in a manner similar to alternative sigma factors in bacterial cells. In vivo transcription and promoter analysis established a clear relationship between the promoter requirements of haloarchaeal genes and those of the eukaryal RNA polymerase II promoter. Studies on heat shock gene promoters, and the demonstration that specific tfb genes were induced by heat shock, provided the …
Date: September 23, 2008
Creator: Daniels, Charles J.
Object Type: Report
System: The UNT Digital Library
Search for B to rho/omega gamma decays at BaBar (open access)

Search for B to rho/omega gamma decays at BaBar

The authors present the results of the search for the decays B{sup 0/{+-}} {yields} {rho}{sup 0/{+-}}{gamma} (previously observed) and B{sup 0} {yields} {omega}{gamma} (for which currently only an upper limit exists). Together with B {yields} K*{gamma} decays, B {yields} ({rho}/{omega}){gamma} allow us to measure the ratio of CKM-matrix elements |V{sub td}/V{sub ts}|. The analysis is based on the full BABAR dataset of 424.35 fb{sup -1} corresponding to 465 million B{bar B} pairs, and makes heavy use of multivariate classification techniques based on decision trees. They find {Beta}(B{sup {+-}} {yields} {rho}{sup {+-}}{gamma}) = (1.20{sub -0.38}{sup +0.42} {+-} 0.20) x 10{sup -6}, {Beta}(B{sup 0} {yields} {rho}{sup 0}{gamma}) = (0.95{sub -0.21}{sup +0.23} {+-} 0.06) x 10{sup -6}, {Beta}(B{sup 0} {yields} {omega}{gamma}) = (0.51{sub -0.24}{sup +0.27} {+-} 0.10) x 10{sup -6}, where the first error is statistical and the second is systematic. They do not observe a statistically significant signal in the latter channel and set an upper limit at {Beta}(B{sup 0} {yields} {omega}{gamma}) < 0.9 x 10{sup -6} (90% C.L.). They also measure the isospin and SU(3){sub F} violating quantities {Lambda}(B{sup +} {yields} {rho}{sup +}{gamma})/2{Lambda}(B{sup 0} {yields} {rho}{sup 0}{gamma})-1 = -0.43{sub -0.22}{sup +0.25} {+-} 0.10 and {Lambda}(B{sup 0} {yields} {omega}{gamma})/{Lambda}(B{sup 0} {yields} {rho}{sup …
Date: September 23, 2008
Creator: Piatenko, Timofei & /SLAC, /Caltech
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Temperature effect on low-k dielectric thin films studied by ERDA (open access)

Temperature effect on low-k dielectric thin films studied by ERDA

Low-k dielectric materials are becoming increasingly interesting as alternative to SiO2 with device geometries shrinking beyond the 65 nm technology node. At elevated temperatures hydrogen migration becomes an important degradation mechanism for conductivity breakdown in semiconductor devices. The possibility of hydrogen release during the fabrication process is, therefore, of great interest in the understanding of device reliability. In this study, various low-k dielectric films were subjected to thermal annealing at temperatures that are generally used for device fabrication. Elastic recoil detection analysis (ERDA) was used to investigate compositional changes and hydrogen redistribution in thin films of plasma-enhanced tetraethylortho-silicate (PETEOS), phosphorus doped silicon glass (PSG), silicon nitride (SiN) and silicon oxynitride (SiON). Except for an initial hydrogen release from the surface region in films of PETEOS and PSG, the results indicate that the elemental composition of the films was stable for at least 2 hours at 450◦C.
Date: September 23, 2008
Creator: Jensen, Jens; Possnert, Göran & Zhang, Yanwen
Object Type: Article
System: The UNT Digital Library