Application of a CdTe gamma-ray spectrometer to remote characterization of high-level radioactive waste tanks

Small, shielded cadmium telluride (CdTe) semiconductor gamma-ray detectors have been used for in situ radiological characterization of underground high-level radioactive waste tanks. Remote measurements up to 700 R/h have been made in gamma radiation fields. Spectral data have been used to generate qualitative and quantitative radionuclide profiles of high-level radioactive waste tanks. Two electronic spectral enhancement techniques (pulse risetime discrimination and pulse risetime compensation) have been used in order to measure trace isotopes in the presence of large amounts of {sup 137}Cs. Spectral resolution better than 1.5% FWHM for the {sup 137}Cs 662 keV photopeak has been obtained. 4 refs., 7 figs

Remote nuclear screening system for hostile environments

A remote measurement system has been constructed for in situ gamma and beta isotopic characterization of highly radioactive nuclear material in hostile environments. A small collimated, planar CdZnTe detector is used for gamma-ray spectroscopy. Spectral resolution of 2% full width at half maximum at 662 kiloelectronvolts has been obtained remotely using rise time compensation and limited pulse shape discrimination, Isotopc measurement of high-energy beta emitters was accomplished with a ruggedized, deeply depleted, surface barrier silicon dictator. The primary function of the remote nuclear screening system is to provide fast qualitative and quantitative isotopic assessment of high-level radioactive material

Selective Media for Actinide Collection and Pre-Concentration: Results of FY 2006 Studies

In this work, we have investigated new materials for potential use in automated radiochemical separations. The work can be divided into three primary tasks: (1) synthesis of new ligands with high affinity for actinide ions, (2) evaluation of new materials for actinide ion affinity, and (3) computational design of advanced ligand architectures for highly selective binding of actinide ions. Ligand Synthesis Work was conducted on synthesizing Kl?ui ligand derivatives containing functionalized pendant groups on the cyclopentadienyl ring. The functionalized pendent groups would allow these ligands to be attached to organic and inorganic solid supports. This work focused on synthesizing the compound Na[Cp?Co(PO(OC2H5)2)3], where Cp?= C5H4C(O)OCH3. Synthesizing this compound is feasible, but the method used in FY 2006 produced an impure material. A modified synthetic scheme has been developed and will be pursued in FY 2007. Work was also initiated on synthesizing bicyclic diamides functionalized for binding to polymeric resins or other surfaces. Researchers at the University of Oregon are collaborators in this work. To date, this effort has focused on synthesizing and characterizing a symmetrically substituted bicyclic diamide ligand with the ?COOH functionality. Again, this synthetic effort will continue into FY 2007. Separations Material Evaluation Work was conducted in FY 2006 to provide a more extensive set of data on the selectivity and affinity of extraction chromatography resins prepared by sorption of Kl?ui ligand onto an inert macroreticular polymeric support. Consistent with previous observations, it was found that these materials strongly bind tetravalent actinides. These materials also adsorb trivalent actinides at low nitric acid concentrations, but the affinity for the trivalent actinides decreases with increasing nitric acid concentration. These materials have relatively low affinity for U(VI), but they do sorb U(VI) to a greater extent than Am(III) at [HNO3] > 0.3 M. Preliminary results suggest that the Kl?ui resins can separate Pu(IV) from sample solutions containing high concentrations of competing ions. Conceptual protocols for recovery of the Pu from the resin for subsequent analysis have been proposed, but further work is needed to perfect these techniques. Work on this subject will be continued in FY 2007. Automated laboratory equipment (in conjunction with Task 3 of the NA-22 Automation Project) will be used in FY 2007 to improve the efficiency of these experiments. The sorption of actinide ions on self-assembled monolayer on mesoporous supports materials containing diphosphonate groups was also investigated. These materials also showed a very high affinity for tetravalent actinides, and they also sorbed U(VI) fairly strongly. Computational Ligand Design An extended MM3 molecular mechanics model was developed for calculating the structures of Kl?ui ligand complexes. This laid the groundwork necessary to perform the computer-aided design of bis-Kl?ui architectures tailored for Pu(IV) complexation. Calculated structures of the Kl?ui ligand complexes [Pu(Kl?ui)2(OH2)2]2+ and [Fe(Kl?ui)2]+ indicate a ''bent'' sandwich arrangement of the Kl?ui ligands in the Pu(IV) complex, whereas the Fe(III) complex prefers a ''linear'' octahedral arrangement of the two Kl?ui ligands. This offers the possibility that two Kl?ui ligands can be tethered together to form a material with very high binding affinity for Pu(IV) over Fe(III). The next step in the design process is to use de novo molecule building software (HostDesigner) to identify potential candidate architectures

Author Correction: Expanded encyclopaedias of DNA elements in the human and mouse genomes

Online Correction for: https://doi.org/10.1038/s41586-020-2493-4 | Erratum for https://bura.brunel.ac.uk/handle/2438/21299In the version of this article initially published, two members of the ENCODE Project Consortium were missing from the author list. Rizi Ai (Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA) and Shantao Li (Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT, USA) are now included in the author list. These errors have been corrected in the online version of the article : 'Expanded encyclopaedias of DNA elements in the human and mouse genomes'.https://www.nature.com/articles/s41586-021-04226-3https://www.nature.com/articles/s41586-021-04226-

A stochastic multidimensional scaling vector threshold model for the spatial representation of “pick any/ n ” data

This paper presents a new stochastic multidimensional scaling vector threshold model designed to analyze “pick any/ n ” choice data (e.g., consumers rendering buy/no buy decisions concerning a number of actual products). A maximum likelihood procedure is formulated to estimate a joint space of both individuals (represented as vectors) and stimuli (represented as points). The relevant psychometric literature concerning the spatial treatment of such binary choice data is reviewed. The nonlinear probit type model is described, as well as the conjugate gradient procedure used to estimate parameters. Results of Monte Carlo analyses investigating the performance of this methodology with synthetic choice data sets are presented. An application concerning consumer choices for eleven competitive brands of soft drinks is discussed. Finally, directions for future research are presented in terms of further applications and generalizing the model to accommodate three-way choice data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45743/1/11336_2005_Article_BF02294452.pd

Perspectives on ENCODE

Supplementary information is available for this paper at https://doi.org/10.1038/s41586-020- 2449-8.© 2020, The Author(s). The Encylopedia of DNA Elements (ENCODE) Project launched in 2003 with the long-term goal of developing a comprehensive map of functional elements in the human genome. These included genes, biochemical regions associated with gene regulation (for example, transcription factor binding sites, open chromatin, and histone marks) and transcript isoforms. The marks serve as sites for candidate cis-regulatory elements (cCREs) that may serve functional roles in regulating gene expression1. The project has been extended to model organisms, particularly the mouse. In the third phase of ENCODE, nearly a million and more than 300,000 cCRE annotations have been generated for human and mouse, respectively, and these have provided a valuable resource for the scientific community.NIH grants: U01HG007019, U01HG007033, U01HG007036, U01HG007037, U41HG006992, U41HG006993, U41HG006994, U41HG006995, U41HG006996, U41HG006997, U41HG006998, U41HG006999, U41HG007000, U41HG007001, U41HG007002, U41HG007003, U41HG007234, U54HG006991, U54HG006997, U54HG006998, U54HG007004, U54HG007005, U54HG007010 and UM1HG009442

A method to improve spectral resolution in planar semiconductor gamma-ray detectors

This paper describes an empirically derived algorithm to compensate for charge trapping in CdTe, CdZnTe, and other planar semiconductor detectors. The method is demonstrated to be an improvement over available systems and application to experimental data is shown

Application of a CdTe gamma-ray spectrometer to remote characterization of high-level radioactive waste tanks

Small, shielded cadmium telluride (CdTe) semiconductor gamma-ray detectors have been used for in situ radiological characterization of underground high-level radioactive waste tanks. Remote measurements have been made in gamma radiation fields up to 700 R/h. Spectral data have been used to generate qualitative and quantitative radionuclide profiles of high-level radioactive waste tanks. Two electronic spectral enhancement techniques (pulse risetime discrimination and pulse risetime compensation) have been used in order to measure trace isotopes with photopeak energies greater than 662keV in the presence of large amounts of {sup 137}Cs. Spectral resolution of 1.5% for the {sup 137}Cs 662 keV photopeak has been obtained

Hot cell remote nuclear scanning of tank core samples

A Westinghouse Hanford Company (WHC)-designed remote measurement system has been constructed for gamma and beta isotopic characterization of Hanford Site high-level waste tank core sample materials in a hot cell. A small, collimated, planar CdZnTe detector is used for gamma-ray spectroscopy. Spectral resolution of 2% full-width-at-maximum at 662 kiloelectronvolts (keV) has been obtained remotely using risetime compensation and limited pulse shape discrimination (PSD). Isotopic measurement of high-energy beta emitters was accomplished with a ruggedly made, deeply depleted, surface barrier silicon detector. The primary function of the remote nuclear screening system is to provide a fast, qualitative stratigraphic assessment (with isotopic information) of high-level radioactive material. Both gamma spectroscopy and beta measurements have been performed on actual core segments. Differences in radionuclide content, which correspond with color or texture variations, have been seen in constant cross section core samples, although for many samples the activity variation can be ascribed to geometry and/or mass factors. Discussion of the design, implementation, results and potential benefits will be presented