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Final Technical Report for Award DE-FG02-05ER41389 A New Electrostatically-Focused, UV HPD for Liquid Xenon: A Direct Comparison with APD, PMT, SiPM in an Integrated Database

Description: Within the scope of the project, a LXe detector and associated gas handling and purification system were set up to study the response of various photodetectors to the VUV Xe light. In particular we tested an Advanced Photonix Large Area Avalanche Photodiode (APD), Silicon Photomultipliers (SiPMs) from two different sources and an Hamamtsu Photonics APD. As part of the XENON Dark Matter project, sponsored by the National Science Foundation, we have accumulated independent knowledge of the response of compact metal channel photomultipliers. At this stage, we conclude that the last are far superior in terms of reliability and performance in a LXe detector environment. More studies are needed with APDs and SiPMs in LXe, taking advantage of the improved performance of these sensors with time. We could not test a hybrid PMT (HPD) since the only available unit on loan from one manufacturer lacked the mechanical stability and was packaged in a form not compatible with LXe purity requirements. Meanwhile, within the XENON collaboration, we are developing with Hamamatsu a hybrid PMT which is named QUPID (Quartz Photon Intensifying Detector) which promises to solve the problems of radioactivity and purity encountered with previous HPDs. We attach to this report two papers which summarize in detail the experimental st-ups, procedures and results obtained with different APDs and SiPMs operated in LXe. We continue our investigations of APDs in view of their potential appication in large arrays for LXe detectors. We intend to publish the results once we complete tests of newly acquired Hamamatsu APDs.
Date: August 25, 2009
Creator: Aprile, Elena
Partner: UNT Libraries Government Documents Department

MFISH Measurements of Chromosomal Aberrations Individuals Exposed in Utero to Gamma-ray Doses from 5 to 20 cGy

Description: Our plan was to identify and obtain blood from 36 individuals from the Mayak-in-utero exposed cohort who were exposed in utero only to gamma ray does doses fro 5 to 20 cGy. Our goal is to do mFISH and in a new development, single-arm mFISH on these samples to measure stable chromosome aberrations in these now adult individuals. The results were compared with matched control individuals (same age, same gender) available from the large control population which we are studying in the context of our plutonium worker study. The long term goal was to assess the results both in terms of the sensitivity of the developing embryo/fetus to low doses of ionizing radiation, and in terms of different potential mechanisms (expanded clonal origin vs. induced instability) for an increased risk.
Date: November 17, 2009
Creator: Brenner, David J.
Partner: UNT Libraries Government Documents Department

Recovery Act: Integrated DC-DC Conversion for Energy-Efficient Multicore Processors

Description: In this project, we have developed the use of thin-film magnetic materials to improve in energy efficiency of digital computing applications by enabling integrated dc-dc power conversion and management with on-chip power inductors. Integrated voltage regulators also enables fine-grained power management, by providing dynamic scaling of the supply voltage in concert with the clock frequency of synchronous logic to throttle power consumption at periods of low computational demand. The voltage converter generates lower output voltages during periods of low computational performance requirements and higher output voltages during periods of high computational performance requirements. Implementation of integrated power conversion requires high-capacity energy storage devices, which are generally not available in traditional semiconductor processes. We achieve this with integration of thin-film magnetic materials into a conventional complementary metal-oxide-semiconductor (CMOS) process for high-quality on-chip power inductors. This project includes a body of work conducted to develop integrated switch-mode voltage regulators with thin-film magnetic power inductors. Soft-magnetic materials and inductor topologies are selected and optimized, with intent to maximize efficiency and current density of the integrated regulators. A custom integrated circuit (IC) is designed and fabricated in 45-nm CMOS silicon-on-insulator (SOI) to provide the control system and power-train necessary to drive the power inductors, in addition to providing a digital load for the converter. A silicon interposer is designed and fabricated in collaboration with IBM Research to integrate custom power inductors by chip stacking with the 45-nm CMOS integrated circuit, enabling power conversion with current density greater than 10A/mm2. The concepts and designs developed from this work enable significant improvements in performance-per-watt of future microprocessors in servers, desktops, and mobile devices. These new approaches to scaled voltage regulation for computing devices also promise significant impact on electricity consumption in the United States and abroad by improving the efficiency of all computational platforms. In 2006, ...
Date: March 31, 2013
Creator: Shepard, Kenneth L
Partner: UNT Libraries Government Documents Department

Single Molecule Spectroscopy of Electron Transfer

Description: The objectives of this research are threefold: (1) to develop methods for the study electron transfer processes at the single molecule level, (2) to develop a series of modifiable and structurally well defined molecular and nanoparticle systems suitable for detailed single molecule/particle and bulk spectroscopic investigation, (3) to relate experiment to theory in order to elucidate the dependence of electron transfer processes on molecular and electronic structure, coupling and reorganization energies. We have begun the systematic development of single molecule spectroscopy (SMS) of electron transfer and summaries of recent studies are shown. There is a tremendous need for experiments designed to probe the discrete electronic and molecular dynamic fluctuations of single molecules near electrodes and at nanoparticle surfaces. Single molecule spectroscopy (SMS) has emerged as a powerful method to measure properties of individual molecules which would normally be obscured in ensemble-averaged measurement. Fluctuations in the fluorescence time trajectories contain detailed molecular level statistical and dynamical information of the system. The full distribution of a molecular property is revealed in the stochastic fluctuations, giving information about the range of possible behaviors that lead to the ensemble average. In the case of electron transfer, this level of understanding is particularly important to the field of molecular and nanoscale electronics: from a device-design standpoint, understanding and controlling this picture of the overall range of possible behaviors will likely prove to be as important as designing ia the ideal behavior of any given molecule.
Date: October 20, 2009
Creator: Holman, Michael; Zang, Ling; Liu, Ruchuan & Adams, David M.
Partner: UNT Libraries Government Documents Department

A Validated High-Let Radiation Specific Biomarker in the Mayak Worker Cohort

Description: Our goal (see Project Objectives) is to deliver a dosimetry system which will enable both a Pu body burden of 0.3 kBq, and a 30 cGy {gamma} ray dose, to be separately estimated with a confidence limit of {+-}30%. In terms of the numbers analyzed and the data we have accrued, we have direct quantitative evidence that we are on track to providing such a comprehensive independent dosimetry system for Mayak workers. We had previously demonstrated that intra-chromosomal aberrations measured in peripheral blood lymphocytes can be used as a sensitive long-lived low-background quantitative biomarker of densely-ionizing radiation dose in individuals exposed many years ago. We propose to calibrate the system such that it can be used to estimate both the densely-ionizing internal plutonium exposure and the sparsely-ionizing external exposure in Mayak workers exposed to different combinations of these over a prolonged period, mostly many years ago. Our objective is to deliver a dosimetry system (set of calibration parameters) which will enable both a comparatively low Pu body burden of 0.3 kBq, and a comparatively low 30 cGy {gamma} ray dose (one of these or both of these) to be estimated with a confidence limit of {+-}30% (higher doses will of course be estimated with smaller confidence intervals and still lower doses with larger confidence intervals). (1) Draw blood, make metaphase slides and measure numbers of intra- and inter-chromosome aberrations (using the mBAND and mFISH techniques) in - (A) 255 healthy former Mayak workers who were exposed various combinations of internal and external exposures. The individuals were chosen from the data base of healthy former workers through computer simulation to optimize estimates of the dosimetry parameters. The individuals have both internal and external dose estimates from the SUBI Doses-99 system. (B) 85 healthy non-exposed controls with ages, gender, and smoking status, ...
Date: December 11, 2006
Creator: David J. Brenner, Ph.D., D.Sc. & Tamara Azizova, M.D.
Partner: UNT Libraries Government Documents Department

Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery

Description: Chemical EOR can be an effective method for increasing oil recovery and reducing the amount of produced water; however, reservoir fluids are chemically complex and may react adversely to the polymers and surfactants injected into the reservoir. While a major goal is to alter rock wettability and interfacial tension between oil and water, rock-fluid and fluid-fluid interactions must be understood and controlled to minimize reagent loss, maximize recovery and mitigate costly failures. The overall objective of this project was to elucidate the mechanisms of interactions between polymers/surfactants and the mineral surfaces responsible for determining the chemical loss due to adsorption and precipitation in EOR processes. The role of dissolved inorganic species that are dependent on the mineralogy is investigated with respect to their effects on adsorption. Adsorption, wettability and interfacial tension are studied with the aim to control chemical losses, the ultimate goal being to devise schemes to develop guidelines for surfactant and polymer selection in EOR. The adsorption behavior of mixed polymer/surfactant and surfactant/surfactant systems on typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) was correlated to their molecular structures, intermolecular interactions and the solution conditions such as pH and/or salinity. Predictive models as well as general guidelines for the use of polymer/surfactant surfactant/surfactant system in EOR have been developed The following tasks have been completed under the scope of the project: (1) Mineral characterization, in terms of SEM, BET, size, surface charge, and point zero charge. (2) Study of the interactions among typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) and surfactants and/or polymers in terms of adsorption properties that include both macroscopic (adsorption density, wettability) and microscopic (orientation/conformation of the adsorbed layers), as well as precipitation/abstraction characteristics. (3) Investigation of the role of dissolved species, especially multivalent ions, on interactions between ...
Date: September 20, 2008
Creator: Somasundaran, P.
Partner: UNT Libraries Government Documents Department

Genetic Control of the Trigger for the G2/M Checkpoint

Description: The work undertaken in this project addressed two seminal areas of low dose radiation biology that are poorly understood and controversial. These areas are the challenge to the linear-no-threshold (LNT) paradigm at low doses of radiation and, the fundamental elements of radiation bystander effect biology Genetic contributions to low dose checkpoint engagement: The LNT paradigm is an extrapolation of known, measured cancer induction endpoints. Importantly, data for lower doses is often not available. Debatably, radiation protection standards have been introduced which are prudently contingent on the adherence of cancer risk to the established trend seen at higher doses. Intriguing findings from other labs have hinted at separate DNA damage response programs that engage at low or high levels of radiation. Individual radiation sensitivity commensurate with hemizygosity for a radiation sensitivity gene has been estimated at 1-2% in the U.S.. Careful interrogation of the DNA damage response at low doses of radiation became important and served as the basis for this grant. Several genes were tested in combinations to determine if combined haploinsufficiency for multiple radiosensitizing genes could render a cell more sensitive to lower levels of acute radiation exposure. We measured a classical radiation response endpoint, cell cycle arrest prior to mitosis. Mouse embryo fibroblasts were used and provided a uniform, rapidly dividing and genetically manipulable population of study. Our system did not report checkpoint engagement at acute doses of gamma rays below 100 mGy. The system did report checkpoint engagement reproducibly at 500 mGy establishing a threshold for activation between 100 and 500 mGy. Engagement of the checkpoint was ablated in cells nullizygous for ATM but was otherwise unperturbed in cells combinatorially haploinsufficient for ATM and Rad9, ATM and PTEN or PTEN and Rad9. Taken together, these experiments tell us that, in a sensitive fibroblast culture system, the engagement ...
Date: October 1, 2013
Creator: Hall, Eric J.; Smilenov, Lubomir B. & Young, Erik F.
Partner: UNT Libraries Government Documents Department

Human Genetic Marker for Resistance to Radiation and Chemicals

Description: TO characterize the human HRDAD9 gene and evaluate its potential as a biomarker to predict susceptibility to the deleterious health effects potentially caused by exposure to radiations or chemicals present at DOE hazardous waste cleanup sites. HRAD9 is a human gene that is highly conserved throughout evolution. Related genes have been isolated from yeasts and mice, underscoring its biological significance. Most of our previous work involved characterization of the yeast gene cognate, wherein it was determined that the corresponding protein plays a significant role in promoting resistance of cells to radiations and chemicals, and in particular, controlling cell growth in response to DNA damage.
Date: May 11, 2001
Creator: Lieberman, DR. Howard B.
Partner: UNT Libraries Government Documents Department

Workshops on Enhancing the Impact of University Research on Critical Technologies. Final report

Description: This proposal was designed to initiate a series of workshops in which participants from universities, government and industry would look strategically at selected areas of technological and societal importance. One of these workshops, dedicated to the discussion of how materials modeling can solve critical problems in industry, held at the Institute for Theoretical Physics, University of California Santa Barbara, January 7 through 11, 1996. ''Modeling of Industrial Materials: Connecting Atomistic and Continuum Scales'' was the first of a coordinated series of workshops, spanning over two years, being organized by a group of academic scientists at UCSB, MIT, and the Swiss Federal Institute of Technology Zurich (ETH). On the premise that materials research focused on technology also presents fundamental scientific challenges, the Workshop sought to identify specific areas of industrial needs and opportunities for materials modeling, interpreted as theory and simulation across all the relevant length scales, and to stimulate meaningful university-industry partnerships.
Date: December 1, 1998
Creator: Eisenberger, Peter M.
Partner: UNT Libraries Government Documents Department

Kernel Principle Component Analysis of Microarray Data. Final Report

Description: Given the limitations in the quantity and quality of gene expression array data, the focus of the research was shifted to development of statistical and computational tools for evaluation and detection of disease susceptibility mutations within a large set of individuals or even an entire population. The diseases that are of particular interest are those with complex etiology, involving interaction of multiple genes and/or environmental factors.
Date: November 6, 2003
Creator: Haghighi, F.
Partner: UNT Libraries Government Documents Department

Final Technical Report "Energy Partitioning in Elementary Chemical Reactions"

Description: This is the final technical report of the subject grant. It describes the scientific results obtained during the reporting period. These results are focused on the reactions of atomic oxygen with terminal alkenes. We have studied the production of vinoxy in these reactions. We have characterized the energy disposal in the reactions and have elaborated the reaction mechanism.
Date: October 3, 2005
Creator: Bersohn, Richard & Valentini, James J.
Partner: UNT Libraries Government Documents Department