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Potential microbial impact on transuranic wastes under conditions expected in the Waste Isolation Pilot Plant (WIPP). Annual report, October 1, 1978-September 30, 1979

Description: Previous results were confirmed showing elevated frequencies of radiation-resistant bacteria in microorganisms isolated from shallow transuranic (TRU) burial soil that exhibits nanocurie levels of beta and gamma radioactivity. Research to determine whether plutonium could be methylated by the microbially produced methyl donor, methylcobalamine, was terminated when literature and consulting radiochemists confirmed that other alkylated transuranic elements are extremely short-lived in the presence of oxygen. Emphasis was placed on investigation of the dissolution of plutonium dioxide by complex formation between plutonium and a polyhydroxamate chelate similar to that produced by microorganisms. New chromatographic and spectrophotometric evidence supports previous results showing enhanced dissolution of alpha radioactivity when /sup 239/Pu dioxide was mixed with the chelate Desferol. Microbial degradation studies of citrate, ethylenediamine tetraacetate (EDTA), and nitrilo triacetate (NTA) chelates of europium are in progress. Current results are summarized. All of the chelates were found to degrade. The average half-life for citrate, NTA, and EDTA was 3.2, 8.0, and 28 years, respectively. Microbial CO/sub 2/ generation is also in progress in 72 tests on several waste matrices under potential WIPP isolation conditions. The mean rate of gas generation was 5.97 ..mu..g CO/sub 2//g waste/day. Increasing temperature increased rates of microbial gas generation across treatments of brine, varying water content, nutrient additions, and anaerobic conditions. No microbial growth was detected in experiments to enumerate and identify the microorganisms in rocksalt cores from the proposed WIPP site. This report contains the year's research results and recommendations derived for the design of safe storage of TRU wastes under geologic repository conditions.
Date: July 1, 1980
Creator: Barnhart, B.J.; Campbell, E.W.; Martinez, E.; Caldwell, D.E. & Hallett, R.
Partner: UNT Libraries Government Documents Department

Detection of early malignant changes in tissue cultured cells using a novel tumorigenicity assay in nude mice

Description: Cultured cells were tested for tumorigenicity in nude mice using a new test involving implantation of cells grown on small gelatin sponges. The test was applied to mouse, hamster, and human cells, and the results were compared to a conventional tumorigenicity assay (injection of cell suspensions). The sponge assay was at least as sensitive as the conventional assay in all cases tested so far. In several instances the sponge assay could detect events not seen in the standard assay. Use of the sponge assay has led to interesting possibilities for studying in vitro and early in vivo cellular changes that may be associated with the ability to form tumors. In studies with two human squamous cell carcinoma cell lines, the two assays yielded comparable results. Such cell lines might provide a system in which the lack of terminal differentiation within a cell population could be examined as a parameter of neoplastic change.
Date: January 1, 1979
Creator: Wells, R.S.; Campbell, E.W.; Holland, L.M.; Schwartzendruber, D.E. & Kraemer, P.M.
Partner: UNT Libraries Government Documents Department

High-accuracy calibration of an adaptive optics system using a phase shifting diffraction interferometer

Description: A phase-shifting diffraction interferometer (PSDI) has been integrated into an adaptive optics (AO) system developed by LLNL for use on the three meter Shane telescope at Lick Observatory. The interferometer is an all fiber optic design, which is extremely compact. It is useful for calibrating the control sensors, measuring the aberrations of the entire AO optical train, and measuring the influence functions of the individual actuators on the deformable mirror. The PSDI is particularly well suited for this application because it measures converging, quasi-spherical wavefronts, such as are produced by an AO imaging system. Thus, a PSDI can be used to measure the aberrations of the entire AO system, in-situ and without errors introduced by auxiliary optics. This provides an extremely accurate measurement ({approximately} 5 nm RMS) of the optical properties of the AO system.
Date: June 23, 1999
Creator: Bauman, B J; Campbell, E W; Olivier, S S & Sweider, D R
Partner: UNT Libraries Government Documents Department

Sub-nanometer interferometry for aspheric mirror fabrication

Description: Aspheric mirrors for extreme ultraviolet lithography (EUVL) at a wavelength of 13nm require surface figure accuracy approaching 0.10 nm rms. A new type of interferometry, based on the fundamental process of diffraction, is described that has the intrinsically ability to achieve this accuracy on aspherical surfaces. However, care must be taken in the design and implementation of the optical system that images the aspheric mirror onto the CCD camera. Non-common paths of the measurement and reference wavefronts within the optical system, as well as distortion of the image of aspheric mirror on the CCD, must be addressed in order to realize sub-nanometer accuracy. The phase shifting diffraction interferometer and the mitigation of potential imaging errors are described for measuring the surface figure on aspheric mirrors.
Date: June 29, 1999
Creator: Campbell, E. W.; Phillion, D. W. & Sommargren, G. E.
Partner: UNT Libraries Government Documents Department

Improved performance of the laser guide star adaptive optics system at Lick Observatory

Description: Results of experiments with the laser guide star adaptive optics system on the 3-meter Shane telescope at Lick Observatory have demonstrated a factor of 4 performance improvement over previous results. Stellar images recorded at a wavelength of 2 {micro}m were corrected to over 40% of the theoretical diffraction-limited peak intensity. For the previous two years, this sodium-layer laser guide star system has corrected stellar images at this wavelength to {approx}10% of the theoretical peak intensity limit. After a campaign to improve the beam quality of the laser system, and to improve calibration accuracy and stability of the adaptive optics system using new techniques for phase retrieval and phase-shifting diffraction interferometry, the system performance has been substantially increased. The next step will be to use the Lick system for astronomical science observations, and to demonstrate this level of performance with the new system being installed on the 10-meter Keck II telescope.
Date: July 20, 1999
Creator: An, J R; Avicola, K; Bauman, B J; Brase, J M; Campbell, E W; Carrano, C et al.
Partner: UNT Libraries Government Documents Department

The sequence and analysis of duplication rich human chromosome 16

Description: Human chromosome 16 features one of the highest levels of segmentally duplicated sequence among the human autosomes. We report here the 78,884,754 base pairs of finished chromosome 16 sequence, representing over 99.9% of its euchromatin. Manual annotation revealed 880 protein-coding genes confirmed by 1,637 aligned transcripts, 19 tRNA genes, 341 pseudogenes, and 3 RNA pseudogenes. These genes include metallothionein, cadherin, and iroquois gene families, as well as the disease genes for polycystic kidney disease and acute myelomonocytic leukemia. Several large-scale structural polymorphisms spanning hundreds of kilobase pairs were identified and result in gene content differences among humans. While the segmental duplications of chromosome 16 are enriched in the relatively gene poor pericentromere of the p-arm, some are involved in recent gene duplication and conversion events likely to have had an impact on the evolution of primates and human disease susceptibility.
Date: April 6, 2005
Creator: Martin, J; Han, C; Gordon, L A; Terry, A; Prabhakar, S; She, X et al.
Partner: UNT Libraries Government Documents Department