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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Thermo-Chemical Decomposition Study of Polyurethane Elastomer Through Glycerolysis Route with Using Crude and Refined Glycerine as a Transesterification Agent

Due to the increasing amount of polyurethane waste, chemical recycling of these materials is a topic of growing interest for many researchers. The primary purpose of polyurethane feedstock recycling is to recover the starting polyol. In this study glycerolysis using glycerine from two sources and two purity grades is proposed as a method of chemical recycling. The main effort of this paper focuses on the employment of commercial glycerine of analytical grade and waste glycerine without purification derived from the biodiesel production, as a decomposing agent for polyurethane recycling. In this study, the influence of polyurethane to glycerine mass ratio (PU/GL) and the type of decomposing agent on the chemical structure by FTIR, {sup 1}H NMR and GPC was examined. FTIR analysis of the glycerolysates showed absorption peaks similar to the virgin polyol. Those results are in compliance with GPC chromatograms, which showed for all samples, well-defined peak at ca. 13 min of retention time. The molecular weight of glycerolysates was ranging from 800 to 1300 g mol{sup −1} depending on PU/GL mass ratio. The novel decomposition agent, namely waste glycerine derived from biodiesel production was successfully used in glycerolysis process.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Impedance Spectroscopy, Magnetic and Optical Analysis of Cadmium Tungstate Nanoparticles from Influence of Capping Agent Additives

Nano crystals of cadmium tungstate (CdWO{sub 4}) were obtained by facile precipitation route by using cadmium sulfate octahydrate and sodium tungstate dihydrate. These nanoparticles were then coated using different capping agents such as glucose, polyvinyl alcohol (PVA), and valine and their effects on the particle size, band gap, morphology, and magnetic character were investigated by powder X-ray diffraction, UV-Visible, FESEM, TEM, and VSM analysis. Capping agents are used in the synthesis of nanoparticles since they facilitate the growth and aggregation of particles in a precise manner, by usually acting as a physical barrier which controls the flow of free electron to the catalyst, so that they can be utilized by the catalyst and sensors of nanoparticle. Impedance spectroscopic technique was carried out, which was very useful in separating the grain boundary resistance and grain boundary capacitance contributions. We discuss the utilization of capping agents and their effects, including surface, optical and intergranular potential barriers in this work.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Evaluation of dried blood spot sampling for verification of exposure to chemical threat agents

Abstract Purpose Exposure to chemical threat agents (CTAs), including nerve agents, the vesicating agent sulfur mustard, and opioids, remains a significant threat to warfighter and civilian populations. Definitive analytical methods to verify exposure to CTAs require shipping refrigerated or frozen biomedical samples to reference laboratories for analysis. Logistical and financial burdens arise as the transport of biomedical samples is subject to strict restrictions and complex packaging, which, if done incorrectly, can lead to sample deterioration. The use of dried blood spot (DBS) sampling could provide operational improvements for collecting, storing, and shipping important forensic samples. Therefore, this effort focuses on developing DBS techniques with Mitra® 30-µL volumetric absorptive microsampling (VAMS®) devices for use in CTA exposure verification. Methods VAMS® devices were loaded and dried with human whole blood that was exposed to the metabolites pinacolyl methylphosphonic acid (PMPA), ethyl methylphosphonic acid (EMPA), 1,1’sulfonylbis[2-(methylsulfinyl)ethane] (SBMSE), norfentanyl, norcarfentanil, norsufentanil, and norlofentanil. Following extraction from the VAMS® devices, metabolites were detected using liquid chromatography-tandem mass spectrometry (LC–MS/MS). The methods were validated for performance by assessing sensitivity, precision, accuracy, and recovery. Results These methods were sensitive to 1 ng/mL for SBMSE, 0.5 ng/mL for PMPA, EMPA, and norfentanyl; 0.1 ng/mL for norlofentanil, and 0.05 ng/mL for norsufentanil and norcarfentanil. All methods met acceptable precision and accuracy criteria with favorable recovery. Conclusions These results demonstrated the utility of VAMS® in stabilizing human whole blood and show promise as an improved collection method for verification of exposure to various CTAs.

Toxicology↗
DOE OSTI2011

GTP depletion synergizes the anti-proliferative activity of chemotherapeutic agents in a cell type-dependent manner

Highlights: {yields} Strong synergy between mycophenolic acid (MPA) and 5-FU in MDA-MB-231 cells. {yields} Cell type-dependent synergy between MPA and anti-proliferative agents. {yields} The synergy of MPA on 5-FU is recapitulated by RNA polymerase-I inhibition. {yields} The synergy of MPA on 5-FU requires the expression of nucleostemin. -- Abstract: Mycophenolic acid (MPA) depletes intracellular GTP by blocking de novo guanine nucleotide synthesis. GTP is used ubiquitously for DNA/RNA synthesis and as a signaling molecule. Here, we made a surprising discovery that the anti-proliferative activity of MPA acts synergistically with specific chemotherapeutic agents in a cell type-dependent manner. In MDA-MB-231 cells, MPA shows an extremely potent synergy with 5-FU but not with doxorubicin or etoposide. The synergy between 5-FU and MPA works most effectively against the highly tumorigenic mammary tumor cells compared to the less tumorigenic ones, and does not work in the non-breast cancer cell types that we tested, with the exception of PC3 cells. On the contrary, MPA shows the highest synergy with paclitaxel but not with 5-FU in SCC-25 cells, derived from oral squamous cell carcinomas. Mechanistically, the synergistic effect of MPA on 5-FU in MDA-MB-231 cells can be recapitulated by inhibiting the RNA polymerase-I activity and requires the expression of nucleostemin. This work reveals that the synergy between MPA and anti-proliferative agents is determined by cell type-dependent factors.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Reactions of self-healing agents and the chemical binding of aggressive ions in sea water: Thermodynamics and kinetics

New self-healing agents that can chemically bind seawater ions invading cracked cementitious materials were proposed. The potential of self-healing and binding of seawater ions were investigated by thermodynamic modeling. It was found that CaO-NaAlO{sub 2} and CaO-metakaolin agents can have Cl{sup −}, SO{sub 4}{sup 2−} and Mg{sup 2+} chemically bound by reacting with sea water to form Friedel's salt, Kuzel's salt, ettringite and hydrotalcite. The removal of Cl{sup −} from seawater firstly increased and then decreased with the increase of Ca/Al molar ratio in both agents, while the removal of Mg{sup 2+} and SO{sub 4}{sup 2−} were hardly influenced and approximated 100%. Because NaAlO{sub 2} dissolves and releases Al(OH){sub 4}{sup −} rapidly, precipitates binding Cl{sup −}, SO{sub 4}{sup 2−} and Mg{sup 2+} were formed fast. In comparison, the reaction of metakaolin binding aggressive ions occurred after 3 days. Because of the faster reaction and the capacity to make [Cl{sup −}]/[OH{sup −}] lower in the solution, CaO-NaAlO{sub 2} would be more efficient for self-healing and mitigating reinforcement corrossion than CaO-metakaolin.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Targeting Phosphatidylinositol 4-Kinase IIIα for Radiosensitization: A Potential Model of Drug Repositioning Using an Anti-Hepatitis C Viral Agent

Purpose: To investigate which isotype of phosphatidylinositol 4-kinase (PI4K) may affect radiosensitivity and examine whether anti–hepatitis C viral (HCV) agents, some of which have been shown to inhibit PI4K IIIα activity, could be repositioned as a radiosensitizer in human cancer cells. Methods and Materials: U251, BT474, and HepG2 cell lines and normal human astrocyte were used. Ribonucleic acid interference, clonogenic assays, Western blotting, immunofluorescence, annexin V assay, lysotracker staining, and β-galactosidase assay were performed. Results: Of the 4 PI4K isotypes, specific inhibition of IIIα increased radiosensitivity. For pharmacologic inhibition of PI4K IIIα, we screened 9 anti-HCV agents by half-maximal inhibitory concentration assay. Simeprevir was selected, and its inhibition of PI4K IIIα activity was confirmed. Combination of simeprevir treatment and radiation significantly attenuated expression of phospho-phospho-PKC and phospho-Akt and increased radiation-induced cell death in tested cell lines. Pretreatment with simeprevir prolonged γH2AX foci formation and down-regulation of phospho-DNA-PKcs, indicating impairment of nonhomologous end-joining repair. Cells pretreated with simeprevir exhibited mixed modes of cell death, including apoptosis and autophagy. Conclusion: These data demonstrate that targeting PI4K IIIα using an anti-HCV agent is a viable approach to enhance the therapeutic efficacy of radiation therapy in various human cancers, such as glioma, breast, and hepatocellular carcinoma.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Current Status of Targeted Radioprotection and Radiation Injury Mitigation and Treatment Agents: A Critical Review of the Literature

As more cancer patients survive their disease, concerns about radiation therapy–induced side effects have increased. The concept of radioprotection and radiation injury mitigation and treatment offers the possibility to enhance the therapeutic ratio of radiation therapy by limiting radiation therapy–induced normal tissue injury without compromising its antitumor effect. Advances in the understanding of the underlying mechanisms of radiation toxicity have stimulated radiation oncologists to target these pathways across different organ systems. These generalized radiation injury mechanisms include production of free radicals such as superoxides, activation of inflammatory pathways, and vascular endothelial dysfunction leading to tissue hypoxia. There is a significant body of literature evaluating the effectiveness of various treatments in preventing, mitigating, or treating radiation-induced normal tissue injury. Whereas some reviews have focused on a specific disease site or agent, this critical review focuses on a mechanistic classification of activity and assesses multiple agents across different disease sites. The classification of agents used herein further offers a useful framework to organize the multitude of treatments that have been studied. Many commonly available treatments have demonstrated benefit in prevention, mitigation, and/or treatment of radiation toxicity and warrant further investigation. These drug-based approaches to radioprotection and radiation injury mitigation and treatment represent an important method of making radiation therapy safer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Facile synthesis of α-Fe{sub 2}O{sub 3}@ porous hollow yeast-based carbonaceous microspheres for fluorescent whitening agent-VBL wastewater treatment

Porous hollow carbonaceous microspheres (PHCMs) fabricated from yeast cells by hydrothermal treatment have stimulated interest because of their outstanding chemical and physical properties. Herein, the functionalizations of PHCMs by further coating of α-Fe{sub 2}O{sub 3} nanoparticles onto the surface were carried out. The structure of resulted α-Fe{sub 2}O{sub 3}@PHCMs products were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and BET specific surface area measurements (BET), respectively. Its promising application was evaluated by the Fenton-like degradation of fluorescent whitening agent-VBL from aqueous solutions. - Graphical abstract: In this work, novel α-Fe{sub 2}O{sub 3}@porous hollow carbonaceous microspheres (α-Fe{sub 2}O{sub 3}@PHCMs) were synthesized through a combination of hydrothermal method and calcinations route and achieved excellent removal efficiency for fluorescent whitening Agent-VBL. - Highlights: • The hybrid α-Fe{sub 2}O{sub 3}@ porous hollow microspheres (PHCMs) were firstly fabricated. • The formation mechanism of α-Fe{sub 2}O{sub 3}@PHCMs microspheres was proposed and verified. • Dithizone played a key role in the synthesis of α-Fe{sub 2}O{sub 3}@PHCMs composites. • A favorable removal for the fluorescent whitening agent-VBL were achieved.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Sepsis reconsidered: Identifying novel metrics for behavioral landscape characterization with a high-performance computing implementation of an agent-based model

Objectives: Sepsis affects nearly 1 million people in the United States per year, has a mortality rate of 28–50% and requires more than $20 billion a year in hospital costs. Over a quarter century of research has not yielded a single reliable diagnostic test or a directed therapeutic agent for sepsis. Central to this insufficiency is the fact that sepsis remains a clinical/physiological diagnosis representing a multitude of molecularly heterogeneous pathological trajectories. Advances in computational capabilities offered by High Peformance Computing (HPC) platforms call for an evolution in the investigation of sepsis to attempt to define the boundaries of traditional research (bench, clinical and computational) through the use of computational proxy models. We present a novel investigatory and analytical approach, derived from how HPC resources and simulation are used in the physical sciences, to identify the epistemic boundary con- ditions of the study of clinical sepsis via the use of a proxy agent-based model of systemic inflammation. Design: Current predictive models for sepsis use correlative methods that are limited by patient heterogeneity and data sparseness. We address this issue by using an HPC version of a system-level validated agent-based model of sepsis, the Innate Immune Response ABM (IIRBM), as a proxy system in order to identify boundary conditions for the possible behavioral space for sepsis. We then apply advanced analysis derived from the study of Random Dynamical Systems (RDS) to identify novel means for characterizing system behavior and providing insight into the tractability of traditional investigatory methods. Results: The behavior space of the IIRABM was examined by simulating over 70 million sepsis patients for up to 90 days in a sweep across the following parameters: cardio-respiratory-metabolic resilience; microbial invasiveness; microbial toxigenesis; and degree of nosocomial exposure. In addition to using established methods for describing parameter space, we developed two novel methods for characterizing the behavior of a RDS: Probabilistic Basins of Attraction (PBoA) and Stochastic Trajectory Analysis (STA). Computationally generated behavioral landscapes demonstrated attractor structures around stochastic re- gions of behavior that could be described in a complementary fashion through use of PBoA and STA. The stochasticity of the boundaries of the attractors highlights the challenge for correlative attempts to characterize and classify clinical sepsis. Conclusions: HPC simulations of models like the IIRABM can be used to generate approximations of the behavior space of sepsis to both establish “boundaries of futility” with respect to existing investi- gatory approaches and apply system engineering principles to investigate the general dynamic properties of sepsis to provide a pathway for developing control strategies. Here, the issues that bedevil the study and treatment of sepsis, namely clinical data sparseness and inadequate experimental sampling of system behavior space, are fundamental to nearly all biomedical research, manifesting in the “Crisis of Reproducibility” at all levels. HPC-augmented simulation-based research offers an investigatory strategy more consistent with that seen in the physical sciences (which combine experiment, theory and simulation), and an opportunity to utilize the leading advances in HPC, namely deep machine learning and evolutionary computing, to form the basis of an iterative scientific process to meet the full promise of Precision Medicine (right drug, right patient, right time).

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

Preparation and characterization of nanocrystalline CuO powders with the different surfactants and complexing agent mediated precipitation method

Highlights: • CuO nanostructures by surfactants mediated method. • Structural and optical properties of CuO nanostructures changes under the effect of surface modifier. • Citric acid assisted is the best, in terms of size, morphology and optical properties than that of CTAB, SDS and PEG-400. - Abstract: Nanostructures of copper oxide (CuO) was synthesized into crystallite sized ranging from 20 to 50 nm in the presence of different surfactants, and complex agent such as cityl tri methyl ammonium bromide (CTAB), sodium do decyl sulfate (SDS), poly ethylene glycol (PEG-400) and citric acid via a precipitation route. Variations in several parameters and their effects on the structural and optical properties of CuO nanostructures (crystallite size, morphology and band gap) were investigated by XRD, FTIR, SEM and UV analysis. The UV–visible absorption spectra of the different surfactants and complexing agent assisted CuO nanostructures indicates that the estimated optical band gap energy value (1.94–1.98 eV) is higher than that of the bulk CuO value (1.4 eV), which is attributed to the quantum confinement effect. The formation mechanism of different surfactants and complexing agent assisted CuO nanostructures is also proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Protective effects of antioxidants and anti-inflammatory agents against manganese-induced oxidative damage and neuronal injury

Exposure to excessive manganese (Mn) levels leads to neurotoxicity, referred to as manganism, which resembles Parkinson's disease (PD). Manganism is caused by neuronal injury in both cortical and subcortical regions, particularly in the basal ganglia. The basis for the selective neurotoxicity of Mn is not yet fully understood. However, several studies suggest that oxidative damage and inflammatory processes play prominent roles in the degeneration of dopamine-containing neurons. In the present study, we assessed the effects of Mn on reactive oxygen species (ROS) formation, changes in high-energy phosphates and associated neuronal dysfunctions both in vitro and in vivo. Results from our in vitro study showed a significant (p < 0.01) increase in biomarkers of oxidative damage, F{sub 2}-isoprostanes (F{sub 2}-IsoPs), as well as the depletion of ATP in primary rat cortical neurons following exposure to Mn (500 {mu}M) for 2 h. These effects were protected when neurons were pretreated for 30 min with 100 of an antioxidant, the hydrophilic vitamin E analog, trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), or an anti-inflammatory agent, indomethacin. Results from our in vivo study confirmed a significant increase in F{sub 2}-IsoPs levels in conjunction with the progressive spine degeneration and dendritic damage of the striatal medium spiny neurons (MSNs) of mice exposed to Mn (100 mg/kg, s.c.) 24 h. Additionally, pretreatment with vitamin E (100 mg/kg, i.p.) or ibuprofen (140 {mu}g/ml in the drinking water for two weeks) attenuated the Mn-induced increase in cerebral F{sub 2}-IsoPs? and protected the MSNs from dendritic atrophy and dendritic spine loss. Our findings suggest that the mediation of oxidative stress/mitochondrial dysfunction and the control of alterations in biomarkers of oxidative injury, neuroinflammation and synaptodendritic degeneration may provide an effective, multi-pronged therapeutic strategy for protecting dysfunctional dopaminergic transmission and slowing of the progression of Mn-induced neurodegenerative processes. -- Research highlights: Black-Right-Pointing-Pointer Mn exposure leads to neurotoxicity in vitro and in vivo. Black-Right-Pointing-Pointer Antioxidants and anti-inflammatory agents attenuate Mn-induced oxidative injury. Black-Right-Pointing-Pointer These agents also protect the striatal neurons from dendritic atrophy and spine loss. Black-Right-Pointing-Pointer These prophylactic strategies may be effective against Mn neurotoxicity.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Topical efficacy of dimercapto-chelating agents against lewisite-induced skin lesions in SKH-1 hairless mice

Lewisite is a potent chemical warfare arsenical vesicant that can cause severe skin lesions. Today, lewisite exposure remains possible during demilitarization of old ammunitions and as a result of deliberate use. Although its cutaneous toxicity is not fully elucidated, a specific antidote exists, the British anti-lewisite (BAL, dimercaprol) but it is not without untoward effects. Analogs of BAL, less toxic, have been developed such as meso-2,3-dimercaptosuccinic acid (DMSA) and have been employed for the treatment of heavy metal poisoning. However, efficacy of DMSA against lewisite-induced skin lesions remains to be determined in comparison with BAL. We have thus evaluated in this study the therapeutic efficacy of BAL and DMSA in two administration modes against skin lesions induced by lewisite vapor on SKH-1 hairless mice. Our data demonstrate a strong protective efficacy of topical application of dimercapto-chelating agents in contrast to a subcutaneous administration 1 h after lewisite exposure, with attenuation of wound size, necrosis and impairment of skin barrier function. The histological evaluation also confirms the efficacy of topical application by showing that treatments were effective in reversing lewisite-induced neutrophil infiltration. This protective effect was associated with an epidermal hyperplasia. However, for all the parameters studied, BAL was more effective than DMSA in reducing lewisite-induced skin injury. Together, these findings support the use of a topical form of dimercaprol-chelating agent against lewisite-induced skin lesion within the first hour after exposure to increase the therapeutic management and that BAL, despite its side-effects, should not be abandoned. - Highlights: • Topically applied dimercapto-chelating agents reduce lewisite-induced skin damage. • One topical application of BAL or DMSA is sufficient to reverse lewisite effects. • Topical BAL is more effective than DMSA to counteract lewisite-induced skin damage.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Integrated Lateral Flow Test Strip with Electrochemical Sensor for Quantification of Phosphorylated Cholinesterase: Biomarker of Exposure to Organophosphorus Agents

An integrated lateral flow test strip with electrochemical sensor (LFTSES) device with rapid, selective and sensitive response for quantification of exposure to organophosphorus (OP) pesticides and nerve agents has been developed. The principle of this approach is based on parallel measurements of post-exposure and baseline acetylcholinesterase (AChE) enzyme activity, where reactivation of the phosphorylated AChE is exploited to enable measurement of total amount of AChE (including inhibited and active) which is used as a baseline for calculation of AChE inhibition. Quantitative measurement of phosphorylated adduct (OP-AChE) was realized by subtracting the active AChE from the total amount of AChE. The proposed LFTSES device integrates immunochromatographic test strip technology with electrochemical measurement using a disposable screen printed electrode which is located under the test zone. It shows linear response between AChE enzyme activity and enzyme concentration from 0.05 to 10 nM, with detection limit of 0.02 nM. Based on this reactivation approach, the LFTSES device has been successfully applied for in vitro red blood cells inhibition studies using chlorpyrifos oxon as a model OP agent. This approach not only eliminates the difficulty in screening of low-dose OP exposure because of individual variation of normal AChE values, but also avoids the problem in overlapping substrate specificity with cholinesterases and avoids potential interference from other electroactive species in biological samples. It is baseline free and thus provides a rapid, sensitive, selective and inexpensive tool for in-field and point-of-care assessment of exposures to OP pesticides and nerve agents.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Grafting-To and From for Multiplexed Chemical-Warfare-Agent Responsive Polymer Brushes

Surface-tethered polymers have important applications in functional polymer coatings, particularly for the development of chemically responsive surfaces. Here, we combined the traditional grafting-to and grafting-from methods to create a new surface grafting strategy, termed grafting-to and from, using surface-initiated ring-opening metathesis polymerization (SI-ROMP). In this method, poly(pentafluorophenyl methacrylate) is grafted to an amine terminated surface. Surplus reactive esters after reaction with surface amines render this polymer a connecting or tie layer that can be further reacted to provide dense ROMP initiation sites. This amplification of grafting sites results in thick and environmentally stable polymer brushes upon SI-ROMP. With the goal of developing polymer-grafted breathable membranes that autonomously react to multiple chemical warfare agents (CWAs), we demonstrate the benefit of this method by employing amine reactive monomers in the grafting-from step. This enables diverse postsynthetic functionalization for the facile screening of chemical motifs to enhance response capabilities to mustard blister agents. Surface-tethered triarylmethanol-containing polymers with four distinct functional groups are prepared and challenged with the vapor of 2-chloroethyl ethyl sulfide (CEES), a simulant of mustard agent, in humid air. Importantly, hydroxyl groups effectively improve CWA response and the resulting polymer brushes show chain collapse after both CEES and diethylchlorophosphate (DCP) treatment. Our results illustrate that the grafting-to and from method can be used to grow functional and robust polymer coatings for various applications.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Spectroscopic and Computational Investigation of Room-Temperature Decomposition of a Chemical Warfare Agent Simulant on Polycrystalline Cupric Oxide

Certain organophosphorus molecules are infamous due to their use as highly toxic nerve agents. The filtration materials currently in common use for protection against chemical warfare agents were designed before organophosphorus compounds were used as chemical weapons. A better understanding of the surface chemistry between simulant molecules and the individual filtration-material components is a critical precursor to the development of more effective materials for filtration, destruction, decontamination, and/or sensing of nerve agents. Here in this paper, we report on the surface adsorption and reactions of a sarin simulant molecule, dimethyl methylphosphonate (DMMP), with cupric oxide surfaces. In situ ambient pressure X-ray photoelectron and infrared spectroscopies are coupled with density functional calculations to propose mechanisms for DMMP decomposition on CuO. We find extensive room temperature decomposition of DMMP on CuO, with the majority of decomposition fragments bound to the CuO surface. We observe breaking of PO-CH 3 , P-OCH 3 , and P-CH 3 bonds at room temperature. On the basis of these results, we identify specific DMMP decomposition mechanisms not seen on other metal oxides. Participation of lattice oxygen in the decomposition mechanism leads to significant changes in chemical and electronic surface environment, which are manifest in the spectroscopic and computational data. This study establishes a computational baseline for the study of highly toxic organophosphorous compounds on metal oxide surfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Correlated Multimodal Approach Reveals Key Details of Nerve-Agent Decomposition by Single-Site Zr-Based Polyoxometalates

Development of technologies for protection against chemical warfare agents (CWAs) is critically important. Recently, polyoxometalates have attracted attention as potential catalysts for nerve-agent decomposition. Improvement of their effectiveness in real operating conditions requires an atomic-level understanding of CWA decomposition at the gas–solid interface. We investigated decomposition of the nerve agent Sarin and its simulant, dimethyl chlorophosphate (DMCP), by zirconium polytungstate. Using a multimodal approach, we showed that upon DMCP and Sarin exposure the dimeric tungstate undergoes monomerization, making coordinatively unsaturated Zr(IV) centers available, which activate nucleophilic hydrolysis. Furthermore, DMCP is shown to be a good model system of reduced toxicity for studies of CWA deactivation at the gas–solid interface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Benzoin Radicals as Reducing Agent for Synthesizing Ultrathin Copper Nanowires

Here, we report a new, general synthetic approach that uses heat driven benzoin radicals to grow ultrathin copper nanowires with tunable diameters. This is the first time carbon organic radicals have been used as a reducing agent in metal nanowire synthesis. In-situ temperature dependent electron paramagnetic resonance (EPR) spectroscopic studies show that the active reducing agent is the free radicals produced by benzoins under elevated temperature. Furthermore, the reducing power of benzoin can be readily tuned by symmetrically decorating functional groups on the two benzene rings. When the aromatic rings are modified with electron donating (withdrawing) groups, the reducing power is promoted (suppressed). The controllable reactivity gives the carbon organic radical great potential as a versatile reducing agent that can be generalized in other metallic nanowire syntheses.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Evaluating the potential of chelation therapy to prevent and treat gadolinium deposition from MRI contrast agents

Several MRI contrast agent clinical formulations are now known to leave deposits of the heavy metal gadolinium in the brain, bones, and other organs of patients. This persistent biological accumulation of gadolinium has been recently recognized as a deleterious outcome in patients administered Gd-based contrast agents (GBCAs) for MRI, prompting the European Medicines Agency to recommend discontinuing the use of over half of the GBCAs currently approved for clinical applications. Here, to address this problem, we find that the orally-available metal decorporation agent 3,4,3-LI(1,2-HOPO) demonstrates superior efficacy at chelating and removing Gd from the body compared to diethylenetriaminepentaacetic acid, a ligand commonly used in the United States in the GBCA Gadopentetate (Magnevist). Using the radiotracer 153 Gd to obtain precise biodistribution data, the results herein, supported by speciation simulations, suggest that the prophylactic or post-hoc therapeutic use of 3,4,3-LI(1,2-HOPO) may provide a means to mitigate Gd retention in patients requiring contrast-enhanced MRI.

59 BASIC BIOLOGICAL SCIENCES↗