Armored Enzyme Nanoparticles for Remediation of Subsurface

The remediation of subsurface contaminants is a critical problem for the Department of Energy, other government agencies, and our nation. Severe contamination of soil and groundwater exists at several DOE sites due to various methods of intentional and unintentional release. Given the difficulties involved in conventional removal or separation processes, it is vital to develop methods to transform contaminants and contaminated earth/water to reduce risks to human health and the environment. Transformation of the contaminants themselves may involve conversion to other immobile species that do not migrate into well water or surface waters, as is proposed for metals and radionuclides; or degradation to harmless molecules, as is desired for organic contaminants. Transformation of contaminated earth (as opposed to the contaminants themselves) may entail reductions in volume or release of bound contaminants for remediation

Investigating the Role of Non-Covalent Interactions in Conformation and Assembly of Triazine-Based Sequence-Defined Polymers

Grate and co-workers at Pacific Northwest National Laboratory recently developed high information content triazine-based sequence-defined polymers that are robust by not having hydrolyzable bonds and can encode structure and functionality by having various side chains. Through molecular dynamics (MD) simulations, the triazine polymers have been shown to form particular sequential stacks, have stable backbone-backbone interactions through hydrogen bonding and $\pi$-$\pi$ interactions, and conserve their \emph{cis/trans} conformations throughout the simulation. However, we do not know the effects of having different side chains and backbone structures on the entire conformation and whether the \emph{cis} or \emph{trans} conformation is more stable for the triazine polymers. For this reason, we investigate the role of non-covalent interactions for different side chains and backbone structures on the conformation and assembly of triazine polymers in MD simulations. Since there is a high energy barrier associated to the \emph{cis}-\emph{trans} isomerization, we use replica exchange molecular dynamics (REMD) to sample various conformations of triazine hexamers. To obtain rates and intermediate conformations, we use the recently developed concurrent adaptive sampling (CAS) algorithm for dimer of triazine trimers. We found that the hydrogen bonding ability of the backbone structure is critical for the triazine polymers to self-assemble into nanorod-like structures, rather than that of the side chains, which can help researchers design more robust materials

Radionuclide Sensors for Water Monitoring

Radionuclide contamination in the soil and groundwater at U.S. Department of Energy (DOE) sites is a severe problem that requires monitoring and remediation. Radionuclide measurement techniques are needed to monitor surface waters, groundwater, and process waters. Typically, water samples are collected and transported to an analytical laboratory, where costly radiochemical analyses are performed. To date, there has been very little development of selective radionuclide sensors for alpha- and beta-emitting radionuclides such as 90Sr, 99Tc, and various actinides of interest. The objective of this project is to investigate novel sensor concepts and materials for sensitive and selective determination of beta- and alpha-emitting radionuclide contaminants in water. To meet the requirements for low-level, isotope-specific detection, the proposed sensors are based on radiometric detection. As a means to address the fundamental challenge of the short ranges of beta and alpha particle s in water, our overall approach is based on localization of preconcentration/separation chemistries directly on or within the active area of a radioactivity detector. Automated microfluidics is used for sample manipulation and sensor regeneration or renewal. The outcome of these investigations will be the knowledge necessary to choose appropriate chemistries for selective preconcentration of radionuclides from environmental samples, new materials that combine chemical selectivity with scintillating properties, new materials that add chemical selectivity to solid-state diode detectors, new preconcentrating column sensors, and improved instrumentation and signal processing for selective radionuclide sensors. New knowledge will provide the basis for designing effective probes and instrumentation for field and in situ measurements

Radioanalytical Chemistry for Automated Nuclear Waste Process Monitoring

This research program is directed toward rapid, sensitive, and selective determination of beta and alpha-emitting radionuclides such as 99Tc, 90Sr, and trans-uranium (TRU) elements in low activity waste (LAW) processing streams. The overall technical approach is based on automated radiochemical measurement principles. Nuclear waste process streams are particularly challenging for rapid analytical methods due to the complex, high- ionic-strength, caustic brine sample matrix, the presence of interfering radionuclides, and the variable and uncertain speciation of the radionuclides of interest. As a result, matrix modification, speciation control, and separation chemistries are required for use in automated process analyzers. Significant knowledge gaps exist relative to the design of chemistries for such analyzers so that radionuclides can be quantitatively and rapidly separated and analyzed in solutions derived from low-activity waste processing operations. This research is addressing these knowledge gaps in the area of separation science, nuclear detection, and analytical chemistry and instrumentation. The outcome of these investigations will be the knowledge necessary to choose appropriate chemistries for sample matrix modification and analyte speciation control and chemistries for rapid and selective separation and preconcentration of target radionuclides from complex sample matrices. In addition, new approaches for quantification of alpha emitters in solution using solid state diode detectors, as well as improved instrumentation and signal processing techniques for use with solid-state and scintillation detectors, will be developed. New knowledge of the performance of separation materials, matrix modification and speciation control chemistries, instrument configurations, and quantitative analytical approaches will provide the basis for designing effective instrumentation for radioanalytical process monitoring. Specific analytical targets include 99 Tc, 90Sr and TRU actinides

Science To Support DOE Site Cleanup: The Pacific Northwest National Laboratory Environmental Management Science Program Awards

Pacific Northwest National Laboratory (PNNL) was awarded ten Environmental Management Science Program (EMSP) research grants in fiscal year 1996, six in fiscal year 1997, nine in fiscal year 1998, seven in fiscal year 1999, and five in fiscal year 2000. All of the fiscal year 1996 award projects have published final reports. The 1997 and 1998 award projects have been completed or are nearing completion. Final reports for these awards will be published, so their annual updates will not be included in this document. This section summarizes how each of the 1999 and 2000 grants address significant U.S. Department of Energy (DOE) cleanup issues, including those at the Hanford Site. The technical progress made to date in each of these research projects is addressed in more detail in the individual progress reports contained in this document. The 1999 and 2000 EMSP awards at PNNL are focused primarily in two areas: Tank Waste Remediation, and Soil and Groundwater Cleanup

EMSL Geochemistry, Biogeochemistry and Subsurface Science-Science Theme Advisory Panel Meeting

This report covers the topics of discussion and the recommendations of the panel members. On December 8 and 9, 2010, the Geochemistry, Biogeochemistry, and Subsurface Science (GBSS) Science Theme Advisory Panel (STAP) convened for a more in-depth exploration of the five Science Theme focus areas developed at a similar meeting held in 2009. The goal for the fiscal year (FY) 2011 meeting was to identify potential topical areas for science campaigns, necessary experimental development needs, and scientific members for potential research teams. After a review of the current science in each of the five focus areas, the 2010 STAP discussions successfully led to the identification of one well focused campaign idea in pore-scale modeling and five longer-term potential research campaign ideas that would likely require additional workshops to identify specific research thrusts. These five campaign areas can be grouped into two categories: (1) the application of advanced high-resolution, high mass accuracy experimental techniques to elucidate the interplay between geochemistry and microbial communities in terrestrial ecosystems and (2) coupled computation/experimental investigations of the electron transfer reactions either between mineral surfaces and outer membranes of microbial cells or between the outer and inner membranes of microbial cells

Interfacial Chemistry and Engineering Annual Report 2000

This annual report describes the research and staff accomplishments in 2000 for the EMSL Interfacial Chemistry and Engineering Directorate

Chemometric Classification of Unknown Vapors by Conversion of Sensor Array Pattern Vectors to Vapor Descriptors: Extension from Mass-Transducing Sensors To Volume-Transducing Sensors

A new chemometric method was recently described for classifying unknowns by transforming the vector containing the responses from a multivariate detector to a vector containing descriptors of the detected analyte (Grate et al. 1999). This approach was derived for sensor arrays where each sensor's signal is proportional to the amount of vapor sorbed by a polymer on the sensor surface. In this case, the response is proportional to the partition coefficient, K, and the concentration of the vapor in the gas phase, Cv, where K is the ratio of the concentration of vapor in the sorbent polymer phase, Cs, to Cv