31P NMR Analysis of the Resistance of Tripoly- and Trimetaphosphate to Cation-accelerated Hydrolysis under Groundwater-compatible Conditions. BART BUTLER (Dartmouth College Hanover, NH 03755) DAWN WELLMAN (Pacific Northwest National Laboratory, Richland, WA, 99352)

Phosphate barriers have been proposed as durable and relatively inexpensive methods of subsurface uranium remediation. Metal orthophosphate compounds exhibit high stability and rapid precipitation kinetics which afford the potential for fouling the injection well for subsurface remediation. Therefore, identification of a time-released source of orthophosphate may facilitate subsurface remediation. Also, any components of the subsurface which catalyze this degradation must be identified. The degradation of sodium tripolyphosphate (Na5P3O10) and sodium trimetaphosphate (Na3P3O9) were systematically evaluated in under relevant environmental conditions to identify variables present within the subsurface which may catalyze the degradation condensed phosphates. Specific variables considered in this investigation consisted of common groundwater cations (Al3+, Fe3+, Ca2+, Mg2+, and Na+ and Hanford groundwater) and heterogeneous surfaces (FeOOH(s) and Hanford site sediment). A 0.2 M sample of each candidate phosphate compound was subjected to subsurface-relevant pH, temperature, and one of the listed potential catalysts for a period of 3 to 4 weeks. The percent degradation of each condensed phosphate and formation of orthophosphate was monitored at predetermined intervals using 31P nuclear magnetic resonance (NMR). Accelerated degradation of sodium tripolyphosphate was detected in the presence of FeOOH(s) and Hanford site sediment. FeOOH was also catalytic with respect to sodium trimetaphosphate degradation, but Hanford site sediment had no effect. All homogeneous potential catalysts (cations and groundwater) were also catalytically inert.

A Visual Survey of the Effects of Various Parameters on the Plating Rate and Quality of High Purity Electroformed Copper. TASHI PARSONS-MOSS (Mills College Oakland, CA 94613) ERIC HOPPE (Pacific Northwest National Laboratory, Richland, WA, 99352)

Copper of unprecedented purity is needed to serve as the building material for shields and cryostats of ultra-low background germanium spectrometers. High purity copper is electroformed in a Sulfuric Acid-Copper Sulfate plating bath using a reverse pulse plating (RPP) power supply. Structural integrity of copper is determined by the crystal structures formed and is important to the application described. Various changes in the plating conditions were tested and the products were visually assessed under a microscope. Changes in current density, RPP waveform, plating time, convection mechanism, and plating bath chemistry were tested. A conductivity probe and thermocouple were suspended in the plating bath and connected to a chart recorder to monitor the conductivity and temperature of the bath solution during plating. The average current was held constant during each plating session and average voltage was logged and allowed to fluctuate. Periodic samples of the bath solution were collected and tested for [CuSO4] using a spectrophotometer. Each electroformed copper sample lacked uniformity in crystal structure, thickness and surface texture due to variations in electric field and ion concentration gradients surrounding the cathode surface. No two copper deposits are exactly alike, even when similar conditions are applied. The effects of changing most parameters are dramatic, most obviously with current density. High current densities form rough and pitted copper with little structural integrity and may decrease purity by supporting a wide range of potentials. Poor structural qualities obtained by high current density were accentuated by higher acid concentration. There is some flexibility with forward-to-reverse pulse time ratio, but some off-time in between pulses is necessary for a smooth strong structure. Thiourea is an effective brightening agent but any additive potentially increases contamination in the product. Cupric sulfate concentration seems fairly unimportant as long as a sufficient amount for plating is present. It is very important that the solution be thoroughly mixed during plating, but it is not obvious whether or not it should be done by the common industrial method of air sparge. Various tests of structural strength and purity assays on the products formed remain to be administered. These further tests, as well as many more in-depth formation parameter studies will be needed to fully understand and optimize the process.

Adsorption and Unfolding Kinetics of Ovalbumin on a Diethyl Aminoethyl Surface. ALISHA JOHNS (University of Washington Seattle, WA 98195) STEVEN GOHEEN (Pacific Northwest National Laboratory, Richland, WA, 99352)

Proteins that are soluble in aqueous media will frequently adsorb and unfold on solid surfaces. This process is responsible for many of the physiological properties of proteins including enzyme activity, their structural behavior in vivo, protein-protein interactions as in blood coagulation, transport processes, etc. In this study, ovalbumin was studied as for its adsorption, retention, and unfolding properties on the anionic surface of diethyl aminoethyl, DEAE. This investigation examined both the changes in retention and recovery of ovalbumin under gradient chromatographic conditions. Several soluble proteins have already been studied in this manner. The trend for three proteins has been to unfold more rapidly with the molecular weight of the protein. A linear relation was found between the logMW and unfolding kinetics. Ovalbumin was adsorbed at 27 degrees C and pH 7.4 while eluting with a linear salt gradient. Additional experiments involved retaining the protein on the surface for various periods of time using a dilute salt butter before they were allowed to elute. Such a process caused the quantity of the material eluted to change, but not elution pattern. To date, the Ovalbumin recovery data needs further evaluation. A calculation was performed to explain how logMW can correlate with unfolding kinetics. The calculation assumes rigid planar surfaces and spherical proteins. The calculation correlates with previous observations in which an increase in the logarithm of the molecular weight of the protein is proportional to the amount of time required for 50% of that protein to unfold.

Aggregation of Granular Glass Forming Chemicals in Pretreated Radioactive Tank Waste Simulant. CHRISTOPHER ESCOTT (Yakima Valley Community College Yakima, WA 98908) RICHARD DANIEL (Pacific Northwest National Laboratory, Richland, WA, 99352)

To vitrify the liquid fraction of radioactive tank waste, glass forming chemicals (GFC) composed primarily of ground silica glass and orthoboric acid must be added. When GFC are added to the high ionic strength, alkaline waste to make the melter feed material, the solution pH is lowered resulting in significant precipitation. While these precipitates are not a problem for the vitrification process during continuous operation, if given a chance to settle during an event such as prolonged maintenance, they may aggregate and become difficult to redisperse. The addition of polymers to the melter feed may provide steric stabilization to the solids, helping prevent strong aggregation. Here a physically adsorbed polymer layer repels close contact and interaction between adjacent particles. The degree of protection provided by the polymer depends on the amount adsorbed and its configuration at the particle-solution interface. While these are well characterized in low-ionic strength environments, few studies have examined conditions similar to the high ionic strength, alkaline Hanford tank waste. This study sought to characterize the effectiveness of polymers as stabilizers against aggregation in the waste. Using a non-radioactive simulant solution that mimics the chemical and physical properties of actual tank waste, samples were observed under various pH levels with varying concentrations of the polymers Poly(acrylic acid) (PAA), Polyacrylamide (PAM), and Poly(diallyl dimethyl ammonium chloride) (Cat-Floc). In these samples, the occurrences of precipitates and the rheology of the melter feed were characterized. As the pH was lowered, the samples were found to develop increasing amounts of precipitates, thought to be aluminum hydroxide. Flow curve and shear strength tests were then performed. The addition of polymers resulted in an unwanted increase in the viscosity of the mixed slurry and offered no steric stabilization in the melter feed material. These findings show that simple addition of polymers will not stabilize the solids against aggregation. Future studies of radioactive tank waste treatment will be required to determine how the vitrification process can recover from periods of downtime.

Carbon Nanotube Modified Glassy Carbon Electrode for the Detection of Enzymatically-generated Thiocholine. SHAWN RIECHERS (Washington State University Pullman, WA 99163) YUEHE LIN (Pacific Northwest National Laboratory, Richland, WA, 99352)

A carbon nanotube glassy-carbon (CNT/GC) electrode was analyzed for increased sensitivity for the electrochemical detection of enzymatically generated thiocholine. This was accomplished by comparing the cyclic voltammetric and amperometric responses of the CNT/GC, glassy carbon (GC), carbon paste, and gold electrodes. The CNT/GC electrode was shown to give a signal many times greater than that of the GC, carbon paste, or gold electrodes. The added CNT layer lowered the oxidation overpotential (0.15 V) and provided increased sensitivity due to the electrocatalytic activity, rapid rate of electron transfer, and large surface area. Under optimized conditions a detection limit of 5 × 10 -6 mol/L was obtained with a residual error of 5.2% (n=10). The CNT/GC electrode was also used in conjunction with constant-potential flow injection analysis to obtain an improved detection limit of 0.3 × 10 -6 mol/L as well as an improvement in reproducibility. The increased sensitivity and ability to couple with flow injection analysis makes the CNT/GC electrode a promising platform for an automated biosensor in conjunction with acetylcholinesterase for the detection of organophosphate pesticides and nerve agents.

Characterizing Trypsin Behavior during Protein Digests in Mixed Organic Aqueous Solvent Systems Used for Automated High-Throughput Protein Mapping. JASON ASKEW (Arizona State University Tempe, WA 85281) DEANNA AUBERRY (Pacific Northwest National Laboratory, Richland, WA, 99352)

Our current understanding of trypsin behavior during protein digests is limited because there is no direct way to measure the activity under normal digest conditions. Our work focuses on characterizing trypsin activity in various mixed organic aqueous solvents. In order to measure this we used chromogenic and fluorogenic substrates that would change colors as trypsin digests them. These changes in color could be accurately measured using various spectroscopic detection methods. Our results suggest that solvent systems containing acetonitrile produce higher activity rates then methanol systems, but methanol systems are more stable over long periods of time. There was also evidence that large protein substrates stabilize trypsin from the denaturing effects of the solvents. The degree of this stabilization was dependent on the concentration of protein. Future work will focus on measuring the rate of protein denaturation in solvents, and testing mixed acetonitrile and methanol solvent solutions.

Determination of Diisopropyl Methylphosphonate and Dimethyl Methylphosphonate and Their Degradation Products in Complex Biological Matrices. RYAN CLARK (Washington State University Richland, WA 99352) ERIC HOPPE, JIM CAMPBELL (Pacific Northwest National Laboratory, Richland, WA, 99352)

national security and also play a role as environmental contaminants. Research on the degradation products and their toxicities in diverse matrices is needed. This study describes instrumental and sample preparation techniques used to identify and monitor these compounds and their degradation products in agar, saliva, serum, and aqueous media with the purpose of producing a degradation analysis model for analogous compounds of interest. Residue analysis using gas chromatography/mass spectrometry (GC/MS) and headspace sampling followed by GC/MS were the methods developed for analysis. DIMP and DMMP were successfully analyzed in agar, saliva, serum, and aqueous matrices. The methods were extended to analyze for DIMP and DMMP and their degradation products after fungal decontamination with Poria Cocos. This bioremediation technique could lay the groundwork for clean up of areas contaminated with these and similar compounds. The fungal-based technology will be potentially applicable to decontaminate personnel, equipment, structures, and wide-area sites without damage to items and/or individuals.

Determination of Diisopropyl Methylphosphonate and Dimethyl Methylphosphonate and Their Degradation Products in Complex Biological Matrices. ERIKA ZINK (Washington State University Richland, WA 99352) ERIC HOPPE, JIM CAMPBELL (Pacific Northwest National Laboratory, Richland, WA, 99352)

The organophosphorous compounds, diisopropyl methylphosphonate (DIMP) and dimethyl methylphosphonate (DMMP), are of interest to national security and also play a role as environmental contaminants. Research on the degradation products and their toxicities in diverse matrices is needed. This study describes instrumental and sample preparation techniques used to identify and monitor these compounds and their degradation products in agar, saliva, serum, and aqueous media with the purpose of producing a degradation analysis model for analogous compounds of interest. Residue analysis using gas chromatography/mass spectrometry (GC/MS) and headspace sampling followed by GC/MS were the methods developed for analysis. DIMP and DMMP were successfully analyzed in agar, saliva, serum, and aqueous matrices. The methods were extended to analyze for DIMP and DMMP and their degradation products after fungal decontamination with Poria Cocos. This bioremediation technique could lay the groundwork for clean up of areas contaminated with these and similar compounds. The fungal-based technology will be potentially applicable to decontaminate personnel, equipment, structures, and wide-area sites without damage to items and/or individuals.

Development of Sandwich Immunoassay for Use in the Detection of Biological Toxins by Flow Cytometry. ALLYSON FRY (Vanderbilt University Nashville, TN 37235) MARVIN WARNER (Pacific Northwest National Laboratory, Richland, WA, 99352)

An autonomous pathogen detection system (APDS) was developed at Lawrence Livermore National Laboratory which analyzes aerosol samples using a Luminex flow cytometer in order to detect biological toxins that might be present during a bioterrorism attempt.1 We are currently developing reagents that could be used in a flow cytometer like the one found in the APDS that targets botulinum toxin. These reagents consist of fluorophore (e.g. phycoerythrin (PE) or Alexa 633) labeled antibody and internally labeled fluorescent microspheres. Our approach to carrying out the immunoassay employed biotinylated antibodies that were combined with antibody-coupled microspheres. These antibodies were specifically engineered to have a high affinity toward botulinum toxin. A second approach was to develop a model system that consisted of a biotinylated monoclonal antibody specific to Dinitrophenyl (DNP), monoclonal antibody specific to keyhole limpet hemocyanin (KLH) coupled to microspheres, and dinitrophenyl keyhole limpet hemocyanin. Both sets of assays were created using a washed capture sandwich immunoassay procedure and fluorescently labeled using streptavidin phycoerythrin (SA-PE). Median fluorescence was measured using a flow cytometer to quantitate assay efficiency. Future work will focus on optimizing these reagents and applying them to systems designed to employ quantum dot labels, fluorescent semiconducting nanocrystals.

Effect of Microbial Activity on the In Situ Immobilization of Uranium via Phosphate Amendments. KATARINA MALATOVA (Rochester Institute of Technology Rochester, NY 14623) DAWN WELLMAN, PHD. (Pacific Northwest National Laboratory, Richland, WA, 99352)

Immobilization of subsurface uranium plumes via in-situ precipitation with phosphate has been proposed as an alternative remediation technology to standard pump-and-treat methods. Initial investigations regarding the immobilization of uranium via phosphate amendments have centered on inorganic reactions and show promise, but the impact of microbiologic activity on the proposed phosphate amendments and overall remediation strategy is unknown. Natural microorganisms obtained from sediments taken from the Hanford Site (southeastern Washington State) and a pure culture of Arthrobacter globiformis, the most occurring bacteria within the natural extract, were investigated for their effect on the degradation and utility of phosphate amendments for in situ remediation of uranium and on the long-term stability of target uranyl-phosphate minerals. A series of batch experiments were conducted under conditions representative of the Hanford subsurface environment, in the presence and absence of a minimum amount of carbon (0.1% yeast extract), T = 23 ⁰C and pH 8. Experiments were conducted in the absence of carbon to asses the effect of adding a source of phosphorus to a carbon limited environment, which is representative of the Hanford subsurface, on microbial growth. Preliminary results indicate that microbial activity is significantly greater in the presence of both uranyl-phosphate minerals and aqueous phosphate amendments; the presence of carbon appears to provide minimal contribution to the degree of microbial activity within the system.

Examination of the Hydrogenation of Aqueous 1,4-Pentadien-3-ol on Pd-black Using Cavitating Ultrasound Verses the Traditional Stirring Process. KELLY BOYLES (Columbia Basin College Pasco, WA 99301) ROBERT S. DISSELKAMP (Pacific Northwest National Laboratory, Richland, WA, 99352)

This study explores the effects of cavitating ultrasound and silent stirred processing on hydrogenation of the five carbon alcohol 1,4-pentadien-3-ol on the catalyst Pd-Black in water (H₂O) or deuterium oxide (D₂O) using H₂ or D₂ gas. In separate hydrogenation experiments, the methods of silent stirring or cavitating ultrasound at 20 kHz and 270W sonifier output power with 60psig H₂ or D₂ were applied to the substrate in a batch reactor at 298K. The scientific phenomena of hydrogen addition/elimination/isomerization were observed to take place during these hydrogenations. In all experiments the intermediate species of 1-penten-3-ol and 1-penten-3-one were observed to rise to a summed maximum of less than 53% then fall back to zero, at the same time the products 3-pentanol and 3-pentanone continued to rise in abundance throughout the experiment. The final ratio of the products formed is the subject of interest in these experiments. Hydrogenation of the 1,4-pentadien-3-ol species involves fairly complicated multiple reaction paths leading to two possible products. Hydrogen addition yields 3-pentanol and hydrogen elimination, through an enol intermediate, yields 3-pentanone. Cavitating ultrasound is believed to promote the pathway to the 3-pentanol product (e.g., enhanced hydrogenation) and these experiments appear to support that hypothesis. This investigation of fundamental aspects of hydrogenation of this 5 carbon species continues to be encouraging with the anticipated result of using these methods to selectively partially hydrogenate, while minimizing isomerization in non-hydrogenated olefins, 18 carbon species (i.e., seed oils) used in the commercial production of food products. By controlling the conditions that alter selectivity, it is hoped that unwanted trans-fats can be reduced, helping our diets to become healthier. This investigation is just beginning the work needed to reach the 18 carbon seed oil species. If these methods are going to yield the desired reduction of trans-fats in commercial food products, then further exploration will need to be performed on progressively longer carbon chain species until we reach the seed oil systems.

Functionalized Mesoporous Silica Modified Disposable Screen Printed Electrodes for Detection of Metal Ions. LISA DEIBLER (Washington State University Pullman, WA 99163) WASSANA YANTASEE (Pacific Northwest National Laboratory, Richland, WA, 99352)

We have developed the self assembled monolayers on mesoporous silica (SAMMS) modified screen printed carbon electrode (SPCE) which has advantages of being mercury-free, reusable, and low cost, yet as sensitive as Hg based SPCEs. The self-assembled monolayer chemistry of SAMMS allows easy installation of a wide variety of functional interfaces on mesoporous MCM-41 silica, leading to excellent specificity and selectivity for many desired metal ions when the materials are used as modifiers in electrochemical sensors. The voltammetric detection procedure consisted of preconcentration by utilizing the affinity of the functional group to the target metal ions, cathodic electrolysis at -1 V, and stripping steps by scanning from -0.7 V to -0.49 V. After optimization of this procedure, a low detection limit of 0.91 ppb Pb2+ was achieved and preliminary work on Cd detection in urine was completed. The SAMMS modification can be done during the manufacturing process which will increase the measurement precision and reproducibility from one sensor to another. The strong covalent bonding between the functional group and the mesoporous silica on SAMMS resulted in reusability of sensors for tens of measurements, making the establishment of the calibration curve easier (e.g., from 2.5 ppb to 100 ppb Pb2+ after 5 minutes of preconcentration) and the costs more competitive compared to single-use electrodes.

Parameterizing Potential-Derived Charge-Dependent Cavity Radii for Continuum Solvation Models: Aqueous Solutes with Oxo, Hydroxo, Amino, and Methyl Functionalities. CHRISTINE SCHWERDTFEGER (University of Illinois at Urbana Champaign Urbana, IL 61801) DONALD CAMAIONI (Pacific Northwest National Laboratory, Richland, WA, 99352)

Continuum solvation models are economical to run, and, with advances that allow for molecule-shaped cavities, they have the potential to accurately simulate equilibrium properties of solutes. However, benchmark tests show that existing schemes for defining cavities are unable to consistently and accurately predict consistently and accurately the effects of solvation on many neutrals and ions, especially anions. This paper reports on the development of a new protocol for defining the cavities of aqueous solutes. The cavity is defined as interlocking spheres around atoms or groups of atoms in the solute. The sphere radii are determined by simple empirically-based expressions involving the effective atomic charges of the solute atoms (derived from molecular electrostatic potential) that fit the solute molecular electrostatic potential and a base radius. Both of these terms arethat is optimized for the different types of atoms/functional groups in a training set of neutral and charged solutes withthat include. oxo, hydroxo, amino, and methyl functionalities. Parameters in the expressions for the radii were fitted by minimizing residuals between calculated and measured standard free energies of solvation ( _sG*), weighted by the uncertainty in the measured value. The calculations were performed using Density Functional Theory with the B3LYP functional and 6-311+G** basis set in the Gaussian98 package of programs. The optimized radii definitions reproduce _sG* of neutrals and singly-charged ions in training set to within experimental uncertainty and accurately predict _sG* of some compounds outside the training set. The mean unsigned error for training set, which is comprised of 11 neutral compounds, 4 cations and 3 anions, is 0.18 kcal/mol. Inherent to this work's approach, the cavity definitions reflect the strength of specific solute-water interactions. We surmise that this feature underlies the success of the approach. The findings offer encouragement for extending to other functional groups to increase the applicability of the scheme and so obtain greater accuracy in using continuum solvation models to predict equilibrium properties of aqueous solutes.

Probing the H/D Isotope Effect for Hydrogenation using H2/D2 in H2O/D2O of 3-Buten-2-ol on Pd-Black Catalyst. SARAH CHAJKOWKI (Waynesburg College Waynesburg, PA 15370) ROBERT DISSELKAMP (Pacific Northwest National Laboratory, Richland, WA, 99352)

Partial hydrogenation is a process used for manufacturing seed oils, which are comprised of multiple cis-olefins. A large percentage of the residual (non-hydrogenated) cis-olefins during traditional heterogeneous catalytic processing are inevitably isomerized to their trans forms. This study was undertaken to examine the isotope effect of H₂ versus D₂ addition to aqueous 3-buten-2-ol on Pd-black by using the process of cavitating ultrasound compared to stirred/silent methods. Both selectivity and activity measurements were made. The effects of the cavitating ultrasound at 20 kHz and 280 W were investigated. The products formed were 2-butanone and 2-butanol. Comparing the ultrasound assisted to blank (stirred) experiments revealed an enhanced selectivity of the alcohol product formed.For the different combinations of gases and solvents employed, the final ratios of 2-butanol to 2-butanone were: H₂/H₂O 5.67 (cavitated) and 1.44 (stirred), H₂/D₂O 5.25 (cavitated) and 1.86 (stirred), and D₂/H₂O 10.11 (cavitated) and 2.125 (stirred).The hydrogenation employing D₂ did not show a decrease in the yield of 2-butanol product formed. It is anticipated that this information will yield insight into hydrogenation in general, and about cavitating ultrasound processing in particular. For example, it may be possible to quantify the enhancement in the hydrogenation rate caused by cavitating ultrasound.

Protein Adsorption and its Role in Smart Bandage Design. NATHAN CASTRO (El Paso Community College El Paso, TX 79915) STEVE GOHEEN (Pacific Northwest National Laboratory, Richland, WA, 99352)

Protein adsorption can be characterized as the extemporaneous adhesion of protein to a surface. Although extensive research and investigations have been undertaken, a comprehensive biomechanistic understanding of protein adsorption remains quite ubiquitous. This is due to the diverse interactions resulting from the presence of amphoteric and amphiphilic moieties on both the protein and surface. The adsorption isotherm is a common first-step towards quantifying and understanding the adsorption of proteins. A comparative examination of two methods, the classical- and chromatographic, commonly used to study adsorption isotherms is presented. Both methods were used to study the solid/liquid interface of two different derivatives of cotton fiber and bovine serum albumin (BSA). Albumin is the most prominent globular protein in blood plasma and cotton fiber is the most utilized material for the treatment of wounds. Cotton is composed of nearly pure cellulose. The two derivatives under investigation are an untreated cotton sample and a carboxymethylcellulose (CMC) cotton sample. Protein adsorption of collected samples was studied utilizing a colorimetric protein assay coupled with spectrophotometric measurements of absorbance at 595 nm. Applicability of smart bandage design to acute wounds also merits investigation.

Surface Studies of Cesium Absorbed on Aluminum and Paving Brick. MICHELLE MALONE (University of the Virgin Islands St. Thomas, VI 00801) GREGG LUMETTA (Pacific Northwest National Laboratory, Richland, WA, 99352)

Ever since September 11, 2001, terrorist attacks using Radioactive Dispersive Devices (RDD) has been a major concern. RDDs are weapons that combine conventional explosives with radioactive materials. Cesium-137 is one possible radioisotope that might be encountered in an RDD. Understanding how cesium (and other radionuclides) interacts with urban surfaces is needed to provide the scientific basis for developing strategies for responding to and recovering from RDD attacks. In this work, cesium hydroxide (CsOH) was used as the source of cesium contaminant. The two urban surfaces that were investigated were aluminum and paving brick. CsOH was placed on samples of both materials. The samples were dried in an oven and then were placed inside the high vacuum chamber of a combined X-Ray Photoelectron/Auger Spectrometer. Control samples of aluminum and paving brick without added Cs were also placed inside the vacuum chamber in order to obtain reference spectra. The samples were then analyzed to determine surface composition. After comparison with reference spectra, Cs peaks were detected on the aluminum surface and one of the paving brick samples (# 2). On the aluminum spectra, peaks of Cs were detected at 75 eV and 724 eV. Aluminum and oxygen peaks were also detected. On the paving brick sample # 2, Cs peaks were observed at 75 eV and 724 eV. Other peaks that were observed are calcium, silicon, sodium, and oxygen.

Surface Studies of Cesium Absorbed on Aluminum and Paving Brick. GAVIN-AJANI NAVARRO (University of the Virgin Islands St. Thomas, VI 00801) GREGG LUMETTA (Pacific Northwest National Laboratory, Richland, WA, 99352)

Ever since September 11, 2001, terrorist attacks using Radioactive Dispersive Devices (RDD) has been a major concern. RDDs are weapons that combine conventional explosives with radioactive materials. Cesium-137 is one possible radioisotope that might be encountered in an RDD. Understanding how cesium (and other radionuclides) interacts with urban surfaces is needed to provide the scientific basis for developing strategies for responding to and recovering from RDD attacks. In this work, cesium hydroxide (CsOH) was used as the source of cesium contaminant. The two urban surfaces that were investigated were aluminum and paving brick. CsOH was placed on samples of both materials. The samples were dried in an oven and then were placed inside the high vacuum chamber of a combined X-Ray Photoelectron/Auger Spectrometer. Control samples of aluminum and paving brick without added Cs were also placed inside the vacuum chamber in order to obtain reference spectra. The samples were then analyzed to determine surface composition. After comparison with reference spectra, Cs peaks were detected on the aluminum surface and one of the paving brick samples (# 2). On the aluminum spectra, peaks of Cs were detected at 75 eV and 724 eV. Aluminum and oxygen peaks were also detected. On the paving brick sample # 2, Cs peaks were observed at 75 eV and 724 eV. Other peaks that were observed are calcium, silicon, sodium, and oxygen.

Synthesis and Characterization of Novel Nanoporous Metal Thiophosphates. JULIA GLOVACK (SUNY Fredonia Fredonia, NY 14063) DAWN WELLMAN (Pacific Northwest National Laboratory, Richland, WA, 99352)

The first organically templated tin (II) thiophosphates have been synthesized using cetyltrimethylammonium chloride as the surfactant. The synthetic materials were characterized by X-ray diffraction, HR-TEM, and ICP-OES. Chemical analysis confirmed the material was composed of tin, phosphorus, sulfur, and oxygen, with sulfur being a minor constituent. The nanoporous tin (II) thiophosphate was found to be an effective adsorbent for Hg (14.03 mg-15.05 mg/g adsorbent).

The Use of Carbon Nanotube Modified Electrodes as a Method to Detect Organophosphates. MARIA MELLEN (Orange Coast College Costa Mesa, CA 92627) DR. YUEHE LIN (Pacific Northwest National Laboratory, Richland, WA, 99352)

Organophosphates (OPs) are neurotoxins found in pesticides and chemical warfare agents that have the potential to be introduced into water supplies. Recent studies have shown that carbon nanotubes (CNTs), in conjunction with amperometric techniques, can be utilized to make a highly sensitive OP biosensor. This would significantly improve upon current methods to detect OPs, which include gas and liquid chromatography; these techniques are more time-consuming, and cannot be performed on-site. Because OPs work by inhibiting the ability of the enzyme acetylcholinesterase (AChE) to break down the neurotransmitter acetylthiocholine (ATCh), both AChE and ATCh have been considered as a means to indirectly detect the presence of OP compounds. Using CNTs, we have been able to immobilize AChE onto a working electrode which can be used in conjunction with a potentiostat. The potentiostat applies voltage to the aqueous sample then measures the produced current. When the enzyme-modified electrode is introduced to ATCh, an increase in current is observed as the substrate is broken down into acetate and thiocholine (TCh). However, when the electrode is incubated in a sample containing OP, then retested with ATCh, the current does not reach the same levels as previous, signifying inhibition of AChE, and therefore, OP presence. Although this method for detecting OPs shows great potential, additional research is necessary. In the future, it should be possible to use this method alongside a fluid injection system, making the process more automated and reproducible. The data could then be extrapolated to make accurate predictions of OP concentrations in unknown samples.

Unsaturated Release and Migration of Uranium from 300-Area Contaminated Sediments. CARMEN GARBERG (Columbia Basin College Pasco, WA 99301) DAWN M. WELLMAN (Pacific Northwest National Laboratory, Richland, WA, 99352)

The Hanford Site in southeastern Washington State is among the most contaminated facility within the Department of Energy (DOE) complex due to operations related to nuclear energy and weapons production. Remediation at DOE facilities is a top priority due to the potential risks and hazards associated with groundwater. The objective of this investigation is to quantify the release of uranium from contaminated sediments under hydraulically unsaturated conditions. Experiments were conducted on two disturbed sediments from beneath the North Process Pond on the Hanford site, southeastern Washington State, at 20% saturation. These experiments were accomplished using centrifugation techniques to achieve steady-state, hydraulically unsaturated conditions. Results suggest that occasional spikes in uranium concentration may exceed EPA drinking water limits. However, the total amount of uranium released from either sediment does not exceed 5% of the total available amount. This indicates that under unsaturated conditions the migration of uranium from sediments beneath the North Process Pond may be controlled by the interplay of desorption and adsorption/desorption on uncontaminated sediments at the leading edge of the plume. Moreover the sediments may function as a partial barrier for the future migration of uranium within the vadose zone.