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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 595 records · Page 33

Preparation of transition metal nanoparticles and surfaces modified with (co)polymers synthesized by RAFT

A new, facile, general one-phase method of generating thiol-functionalized transition metal nanoparticles and surfaces modified by (co)polymers synthesized by the RAFT method is described. The method includes the steps of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a colloidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as functionalization with a variety of different chemical groups, expanding their utility and application.

36 MATERIALS SCIENCE↗

Occurrence and Stabilization of Colloidal and Nanoparticulate Mercury Sulfides (Final Technical Report)

Mercury contaminates the soils at several DOE sites, including facilities at Oak Ridge, Hanford, and the Savannah River site. This contamination poses a hazard to surrounding ecosystems because the metal continuously leaches to local streams and rivers and is converted to methylmercury, a neurotoxic and highly bioaccumulative form of mercury. Anaerobic microorganisms such as sulfate-reducing and iron-reducing bacteria are primarily responsible for methylmercury production in the environment. The remediation of mercury-contaminated ecosystems is difficult because we lack a poor understanding of the factors that control mercury mobilization and methylation in sediments. The objective of this project was to investigate the forms of mercury that are bioavailable to methylating bacteria. This project specifically focused on mercury-sulfide-organic matter geochemistry and the persistence of nanoparticulate HgS that are intermediates of metal sulfide precipitation reactions occurring in the presence of natural organic matter (NOM). This work involved two specific aims: 1) Investigate environmental processes that facilitate the occurrence and stabilization of nanoparticulate HgS and other metal sulfides; and (2) Investigate the occurrence of nanoparticulate HgS in sediments of the East Fork Poplar Creek, located in near a DOE facility in Oak Ridge, TN. For specific aim #1, laboratory experiments were performed to simulate metal sulfide precipitation processes in environmental systems. A key experimental variable was the type and concentration of NOM that was used in the experiments simulating metal sulfide precipitation. The characteristics of the metal sulfide nanoparticles were analyzed using a suite of analytical techniques that included X-ray based methods at DOE synchrotron facilities (National Synchrotron Light Source and Advanced Photon Source). Field sampling in Oak Ridge was performed in collaboration with colleague at the Oak Ridge National Laboratory. The experimental results demonstrated that a combination of photon scattering and spectroscopic tools can be used to characterize nanoscale structures that form during heterogeneous metal-sulfide-NOM precipitation. ZnS precipitation experiments with a low molecular weight thiol indicated the importance of specific metal-ligand binding for altering the kinetics of ZnS nanoparticle aggregation and monomer growth. However, NOM consists of macromolecular structures that may interact with nano-HgS in non-specific ways (e.g. electrosteric surface interactions. The methylation potential of nano-HgS in sediments may depend on size and crystallinity of nanoparticles and interactions with NOM. For specific aim #2, sediment core samples were collected in three separate locations along the East Fork Poplar Creek in Oak Ridge, TN in June 2011. Analysis of the sediment samples indicated that more than 90% of the Hg in the porewater is associated with colloidal material. These results highlight the importance of small particles for dominating Hg speciation in sediment porewater. Overall, this project highlights the importance of nanoscale phases for mercury speciation. Nanoparticulate HgS will be of particular importance in the anaerobic habitats of methylating microorganisms. In previous models for Hg bioavailability, nanoparticles of Hg are presumed to be unavailable for methylating bacteria. However, recent work shows that nanoparticles contribute to bioavailable Hg that greatly exceeds the contribution from larger HgS microparticles (Zhang et al., 2012). The work performed for this exploratory project lays the groundwork for further study on nanoscale mercury sulfide geochemistry and contributes to an improved understanding of Hg bioavailability and methylation potential.

54 ENVIRONMENTAL SCIENCES↗

Unexpected effects of gene deletion on mercury interactions with the methylation-deficient mutant hgcAB

The hgcA and hgcB gene pair is essential for mercury (Hg) methylation by certain anaerobic bacteria,1 but little is known about how deletion of hgcAB affects cell surface interactions and intracellular uptake of Hg. Here, we compare hgcAB mutants with the wild-type (WT) strains of both Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132 and observe differences in Hg redox transformations, adsorption, and uptake in laboratory incubation studies. In both strains, deletion of hgcAB increased the reduction of Hg(II) but decreased the oxidation of Hg(0) under anaerobic conditions. The measured cellular thiol content in hgcAB mutants was lower than the WT, accounting for decreased adsorption and uptake of Hg. Despite the lack of methylation activity, Hg uptake by the hgcAB continued, albeit at a slower rate than the WT. These findings demonstrate that deletion of the hgcAB gene not only eliminates Hg methylation but also alters cell physiology, resulting in changes to Hg redox reactions, sorption, and uptake by cells.

Geobacter↗

Poly(hydroxyl urethane) compositions and methods of making and using the same

Methods and compositions relating to poly(hydroxyl urethane) compounds are described herein that are useful as, among other things, binders and adhesives. The cross-linked composition is achieved through the reaction of a cyclic carbonate, a compound having two or more thiol groups, and a compound having two or more amine functional groups. In addition, a method of adhesively binding two or more substrates using the cross-linked composition is provided.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Fluorescence dye tagging scheme for mercury quantification and speciation

A fluorescent dye or fluorophore capable of forming complexes with mercury comprises 6,8-difluoro-7-hydroxy-2-oxo-2H-chromene-3-carboxylate amide, wherein the amide is formed by reacting the succinimidyl ester (Pacific Blue.TM.) with an amino acid containing a thiol group, such as cysteine or glutathione. Mercury complexes of the fluorophore fluoresce when excited by a UV or violet laser diode, and the detected intensity can be calibrated to quantify the concentration of mercury in a sample reacted with the fluorophore.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Poly(hydroxyl urethane) compositions and methods of making and using the same

Methods and compositions relating to poly(hydroxyl urethane) compounds are described herein that are useful as, among other things, binders and adhesives. The cross-linked composition is achieved through the reaction of a cyclic carbonate, a compound having two or more thiol groups, and a compound having two or more amine functional groups. In addition, a method of adhesively binding two or more substrates using the cross-linked composition is provided.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Electrode stabilizing materials

An electrolyte includes a polar aprotic solvent; an alkali metal salt; and an electrode stabilizing compound that is a monomer, which when polymerized forms an electrically conductive polymer. The electrode stabilizing compound is a thiophene, a imidazole, a anilines, a benzene, a azulene, a carbazole, or a thiol. Electrochemical devices may incorporate such electrolytes.

36 MATERIALS SCIENCE↗

Self-repairing cement polymer composites and processes of making and using same

New cement-polymer composites and processes of making and using are detailed. One exemplary cement-polymer composite include a Portland cement, an epoxide polymer, a thiol-containing crosslinking agent, and an optional phase separation inhibitor. These composites are dynamically self-healing, mechanically robust, and thermally stable in high temperature environments and can be expected to increase service lifetimes in various applications including energy producing wellbores.

Fernandez, Carlos A.↗

Processable, tunable thio-ene crosslinked polyurethane shape memory polymers

An embodiment includes a platform shape memory polymer system. Such an embodiment exhibits a blend of tunable, high performance mechanical attributes in combination with advanced processing capabilities and good biocompatibility. A post-polymerization crosslinking synthetic approach is employed that combines polyurethane and thiol-ene synthetic processes. Other embodiments are described herein.

36 MATERIALS SCIENCE↗

Crosslinked functional binders and their use in silicon-containing anodes of lithium-ion batteries

A crosslinked polymer composition comprising: (i) a base polymer containing a multiplicity of at least one type of functional group selected from amino, amido, thiol, carboxylic acid, carboxylic acid ester, and epoxy groups; (ii) a multiplicity of hydroxylated benzene rings covalently linked to the base polymer, wherein each hydroxylated benzene ring contains at least two hydroxy groups, and with at least two of the hydroxy groups on said hydroxylated benzene rings being free as OH groups; and (iii) a multiplicity of crosslinking groups that crosslink at least two of said functional groups in the base polymer. The invention is also directed to lithium-ion batteries in which the above-described composition is incorporated in an electrode of the battery, and also directed to methods of operating a lithium-ion battery in which the above-described crosslinked polymer composition is incorporated in an electrode thereof.

Saito, Tsuguyuki↗

Adsorption cooling system using metal organic frameworks

A highly adsorptive structure, includes: a substrate; and a metal-organic framework (MOF) comprising a plurality of metal atoms coordinated to a plurality of organic spacer molecules; wherein the MOF is coupled to at least one surface of the substrate, wherein the MOF is adapted for adsorbing and desorbing a refrigerant under predetermined thermodynamic conditions. The refrigerant includes one or more materials selected from the group consisting of: acid halides, alcohols, aldehydes, amines, chlorofluorocarbons, esters, ethers, fluorocarbons, perfluorocarbons, halocarbons, halogenated aldehydes, halogenated amines, halogenated hydrocarbons, halomethanes, hydrocarbons, hydrochlorofluorocarbons, hydrofluoroethers, hydrofluoroolefins, inorganic gases, ketones, nitrocarbon compounds, noble gases, organochlorine compounds, organofluorine compounds, organophosphorous compounds, organosilicon compounds, oxide gases, refrigerant blends and thiols.

Baumann, Theodore F.↗

Adsorption cooling system using carbon aerogel

A highly adsorptive structure includes: a substrate; and a carbon aerogel adhered to the substrate, wherein the carbon aerogel is characterized by having physical characteristics of in-situ formation on the substrate, and wherein the carbon aerogel is configured to selectively adsorb and desorb one or more refrigerants selected from the group consisting of: acid halides, alcohols, aldehydes, amines, chlorofluorocarbons, esters, ethers, fluorocarbons, perfluorocarbons, halocarbons, halogenated aldehydes, halogenated amines, halogenated hydrocarbons, halomethanes, hydrocarbons, hydrochlorofluorocarbons, hydrofluoroethers, hydrofluoroolefins, inorganic gases, ketones, nitrocarbon compounds, noble gases, organochlorine compounds, organofluorine compounds, organophosphorous compounds, organosilicon compounds, oxide gases, refrigerant blends and thiols.

Baumann, Theodore F.↗

Photocatalyst-free, light-induced carbon-sulfur cross-coupling methods

In one aspect, the invention provides a method of promoting a carbon-sulfur bond forming reaction. In certain embodiments, the reaction comprises cross-coupling of a(n) (hetero)aryl halide with a thiol to form the carbon-sulfur bond, wherein the method is promoted by light irradiation in the absence of a photocatalyst. In other embodiments, the cross-coupling reaction can be promoted through visible light irradiation, including sunlight.

Miyake, Garret↗

Adsorption cooling system using metal organic frameworks

A highly adsorptive structure includes: a substrate; and a metal-organic framework (MOF) comprising a plurality of metal atoms coordinated to a plurality of organic spacer molecules; wherein the MOF is coupled to at least one surface of the substrate, wherein the MOF is configured to adsorb and desorb a refrigerant under predetermined thermodynamic conditions. The refrigerant includes one or more materials selected from the group consisting of: acid halides, alcohols, aldehydes, amines, chlorofluorocarbons, esters, ethers, fluorocarbons, perfluorocarbons, halocarbons, halogenated aldehydes, halogenated amines, halogenated hydrocarbons, halomethanes, hydrocarbons, hydrochlorofluorocarbons, hydrofluoroethers, hydrofluoroolefins, inorganic gases, ketones, nitrocarbon compounds, noble gases, organochlorine compounds, organofluorine compounds, organophosphorous compounds, organosilicon compounds, oxide gases, refrigerant blends and thiols.

Baumann, Theodore F.↗

Crosslinked polyphosphazene blends for gas separation membranes

The disclosed invention relates to a composition comprising a crosslinked blend of polyphosphazene polymers. The composition comprises a first polyphosphazene and a second polyphosphazene, where the first polyphosphazene and the second polyphosphazene being bound by a thiol bearing crosslinking agent. Such compositions are useful as a membrane material for the separation of gasses in a gaseous mixture.

Hopkinson, David↗

Structures of Arg- and Gln-type bacterial cysteine dioxygenase homologs: Arg- and Gln-type Bacterial CDO Homologs

In some bacteria, cysteine is converted to cysteine sulfinic acid by cysteine dioxygenases (CDO) that are only ~15–30% identical in sequence to mammalian CDOs. Among bacterial proteins having this range of sequence similarity to mammalian CDO are some that conserve an active site Arg residue (“Arg-type” enzymes) and some having a Gln substituted for this Arg (“Gln-type” enzymes). Here, we describe a structure from each of these enzyme types by analyzing structures originally solved by structural genomics groups but not published: a Bacillus subtilis “Arg-type” enzyme that has cysteine dioxygenase activity (BsCDO), and a Ralstonia eutropha “Gln-type” CDO homolog of uncharacterized activity (ReCDOhom). The BsCDO active site is well conserved with mammalian CDO, and a cysteine complex captured in the active site confirms that the cysteine binding mode is also similar. The ReCDOhom structure reveals a new active site Arg residue that is hydrogen bonding to an iron-bound diatomic molecule we have interpreted as dioxygen. Notably, the Arg position is not compatible with the mode of Cys binding seen in both rat CDO and BsCDO. As sequence alignments show that this newly discovered active site Arg is well conserved among “Gln-type” CDO enzymes, we conclude that the “Gln-type” CDO homologs are not authentic CDOs but will have substrate specificity more similar to 3-mercaptopropionate dioxygenases.

3-mercaptopropionate dioxygenase↗

Mass spectrometry-based proteomics for system-level characterization of biological responses to engineered nanomaterials

The widespread applications of engineered nanomaterials or nanotechnology make the characterization of biological responses to nanomaterials as an important area of research. The applications of omics-based approaches such as mass spectrometry-based proteomics have revealed new insights into the cellular responses upon exposure to nanomaterials, including how nanomaterials interact and alter cellular pathways. For instance, a redox-dependent response is often associated with exposure of nanomaterials, which leads to the generation of reactive oxygen species. In this review, we discuss the general quantitative proteomics approaches, with an emphasis on redox proteomics and their applications for characterizing the biological responses to nanomaterials.

Zhang, Tong↗

Preparation and application of L-cysteine-doped Keggin polyoxometalate microtubes

L-cysteine-doped tungstosilicate (Lcys-SiW{sub 12}) microtubes are prepared, and the amount of L-cysteine doped in the microtubes can be tuned to some extent. The as-prepared Lcys-SiW{sub 12} microtubes are sensitive to ammonia gas exhibited through the distinct color change of the microtubes from light purple to dark blue after exposing to ammonia gas. A possible mechanism of the coloration is that the adsorbed ammonia molecules increase the basicity of the Lcys-SiW{sub 12} microtubes and promote the redox reaction between L-cysteine and polyoxometalate. This is a pH-dependent solid-solid redox reaction, which is triggered by proton capture agent. The Lcys-SiW{sub 12} microtubes show application in chemical sensors for alkaline gases. - Graphical abstract: The Lcys-SiW{sub 12} microtubes were formed during transformation of the monolacunary Keggin-type [{alpha}-SiW{sub 11}O{sub 39}]{sup 8-} to the saturated Keggin-type [{alpha}-SiW{sub 12}O{sub 40}]{sup 4-}, meanwhile L-cysteine molecules were doped during the growth of the microtubes. Highlights: Black-Right-Pointing-Pointer L-cysteine-doped polyoxometalate microtubes are prepared. Black-Right-Pointing-Pointer Amount of L-cysteine doped in the microtubes can be tuned to some extent. Black-Right-Pointing-Pointer Lcys-SiW{sub 12} microtubes can be applied as a sensor for detecting alkaline gases. Black-Right-Pointing-Pointer This is a proton capture agent-triggered solid-solid redox reaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗