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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Synthesis and pharmacological activity of a silicon—zinc—boron-containing glycerohydrogel

A new pharmacologically active nanostructured silicon—zinc—boron-containing glycerohydrogel was synthesized by the sol—gel method using silicon, zinc, and boron glycerolates as biocompatible precursors. The hydrogel composition and structural features were investigated by transmission electron microscopy, powder X-ray diffraction, IR spectroscopy, atomic emission spectrometry, and elemental analysis; a structural model was proposed. It was found that the 3D framework of the gel is formed by the products of hydrolysis and subsequent (co)condensation of silicon- and boron-containing precursors. Meanwhile, the major part of zinc monoglycerolate does not undergo hydrolytic transformations during gelation, being present in the 3D framework cells as amorphous nano-sized particles. The dispersion medium of the gel is an aqueous glycerol solution of silicon and boron glycerolates, products of their hydrolytic transformations, and water-soluble products of hydrolytic transformations of zinc monoglycerolate. The silicon—zinc—boron gel is nontoxic and possesses wound-healing and antimicrobial activities; it can be considered as a nanostructured dispersed system promising for biomedical applications, which is prepared in a simple and cost-effective way without using catalysts or toxic organic solvents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Close structural relationship of the O-antigens of various Cronobacter species containing 3-deoxy-D-manno-oct-2-ulosonic acid

Some O-polysaccharides (O-antigens) of the lipopolysaccharides of bacteria of the genus Cronobacter contain 3-deoxy-D-manno-oct-2-ulosonic acid. O-Polysaccharides of Cronobacter turicensis G3874 and Cronobacter muytjensii G3886 containing this unit were found to be structurally related to each other and to those of Cronobacter dublinensis HPB 3169 and Cronobacter sakazakii G2706 (serotype O5) studied earlier. The O-polysaccharides differ in the N-acyl group on a 3-amino-3,6-dideoxy-D-glucose residue [(R)-3-hydroxybutanoyl vs. acetyl] or in the presence or absence of the O-acetyl group on an L-rhamnose residue only. Structures of the new O-antigens were established by chemical methods and by 1D and 2D {sup 1}H and {sup 13}C NMR spectroscopy applied to polysaccharides and pentasaccharides obtained by mild alkaline O-deacylation and mild acid hydrolysis of the isolated lipopolysaccharides, respectively.

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

Optimization of Mold Flux for the Continuous Casting of Cr-Contained Steels

To compensate the negative effect caused by the absorption of chromium oxide inclusions during the casting process of Cr-contained steels, a new mold flux system has been designed and investigated. The melting temperature range of the newly designed mold flux system is from [1124 K to 1395 K (851 °C to 1122 °C)]. The viscosity at 1573 K (1300 °C) and the break temperature increase with the addition of MnO and Cr{sub 2}O{sub 3} but decrease with the addition of B{sub 2}O{sub 3}. The crystalline fraction of mold flux decreases from 81 to 42.1 pct with the addition of MnO and Cr{sub 2}O{sub 3}, and then further decreases to 25.3 pct with the addition of B{sub 2}O{sub 3}; however, it improves from 54.4 to 81.5 pct when the basicity increases. Besides, the heat-transfer ability of mold flux is inverse to the crystallization ratio of the slag. The comprehensive study of the properties for the four designed mold fluxes suggests that the mold flux with 1.15 basicity-3.01 pct B{sub 2}O{sub 3}-1.10 pct MnO-2.10 pct Cr{sub 2}O{sub 3} shows the best properties for the continuous casting of Cr-contained steels.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Interaction Between Liquid Steel and AlN Substrate Containing Al-Y-Oxides

Reactions between molten iron, molten silicon steel, and ceramic materials are of great importance from the perspective of the corrosion of refractory material in the steelmaking and continuous casting processes. Reactions between liquid steel and aluminum nitride (AlN) substrate containing Al-Y-oxides were investigated using the sessile drop method at 1833 K (1560 °C). The liquid–substrate interface was observed with the increasing holding time, and the reaction mechanism was studied. In the case of the liquid iron and the silicon steel on the AlN substrate containing Al-Y-oxides, the reaction products on the steel side of the interface between the steel and the substrate were Al-rich Al-Y-oxides and Al{sub 2}O{sub 3} particles. For silicon steel and pure AlN substrate, Al{sub 2}O{sub 3} particles were the main products. Contact angles were lower for liquid iron than for silicon steel due to the higher oxygen content in iron. In addition, the solid–liquid interfacial tension and the work of adhesion between AlN and steel were measured.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Tribological Performance of Ni{sub 3}Al Matrix Self-Lubricating Composites Containing Multilayer Graphene Prepared by Additive Manufacturing

In order to improve tribological performance of Ni{sub 3}Al-based alloy, Ni{sub 3}Al matrix composites containing 1.5 wt.% multilayer graphene (MLG) are prepared through additive manufacturing (AM) and spark plasma sintering (SPS), which are denoted as NMAM and NMSPS, respectively. Tribological behaviors of NMAM and NMSPS against Si{sub 3}N{sub 4} balls are researched under constant speed (0.2 m/s) and varied loads (from 4 to 16 N) for evaluating the tribological properties of NMAM and NMSPS. The results present that NMAM exhibits the excellent tribological properties [low friction coefficients (0.26-0.40) and considerable wear resistance (2.8-4.6 × 10{sup −5} mm{sup 3} N{sup −1} m{sup −1})] as compared to NMSPS, which attributes to the uniform enrichment of MLG with properties of high tensile strength and being easily sheared off on the worn surfaces. Owing to the use of spherical prealloyed powder containing multilayer graphene and the characteristics of layer by layer depositing in the AM process, NMAM has a more compact and uniform substrate, which persistently provides a source of the formation of continuous and stable frictional layer. Due to the characteristics of AM rapid solidification, NMAM has the small grain size and well-compacted microstructure, which can effectively reduce the probability of spalling wear and lead to the increase in wear resistance of materials. The research can offer the reference for self-lubricating materials prepared by AM technology.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Enhanced Strength of 304 SS-Ti6Al4V Laser-Welded Joints Containing Composite Interlayers

This paper investigates the microstructural characterization of the fracture propagation edge during laser beam welding of Ti6Al4V and 304 stainless steel using Cu, V, and Ni interlayers as a single Cu interlayer and composite interlayer structures with different Cu interlayer thicknesses. This study attempts to increase the Ti-SS joint strength through the use of the composite interlayers. X-ray diffraction characterization based on a 0.5-mm-thick Cu interlayer showed that the SS/Cu/Ti joint contained considerable brittle IMCs; however, the fracture surface of the SS/Cu-V/Ti composite interlayer sample did not contain any Fe-Ti IMCs or Cr{sub 2}Ti. EBSD observation indicated that the crack propagated transgranularly from solidified CuTi in the interdendritic regions of the FeTi compounds in the composite interlayer sample; however, the crack propagated intergranularly along Fe{sub 2}Ti grain boundaries in the single interlayer sample. The investigation based on a 1-mm-thick Cu interlayer showed that the SS/Ni-Cu1/Ti sample was stronger than the SS/Cu1/Ti sample due to a lack of CuTi at 3.5 kW. The tensile strength of the SS/Cu1-V/Ti joint was greater than that of the SS/Ni-Cu1/Ti joint due to the formation of ductile NiTi instead of brittle NiTi{sub 2}. The microstructures of the fracture edges after tensile testing illustrated that the eutectic CuTi + CuTi{sub 2} fractured at the SS/Cu1/Ti joint after tensile testing, while CuTi{sub 2} and eutectoid αTi + CuTi{sub 2} compounds fractured during the tensile experiment at the SS/Ni-Cu1/Ti and SS/Cu1-V/Ti joints, respectively. Investigations based on both the 0.5- and 1-mm-thick Cu interlayers showed that the tensile strength and elongation of the composite interlayer joints at a laser power of 3.5 kW were greater than those of the single interlayer joints.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Improved High-Temperature Aluminum Alloys Containing Cerium

A common rare earth (cerium) when added to aluminum in compositions up to the eutectic compositions of around 10 wt.% improves the high-temperature performance of aluminum alloys. In the early 1980s, some promising research and development efforts focused on powder metallurgy revealed that aluminum alloys containing 4 wt.% cerium exhibit high-temperature mechanical properties exceeding those of the best commercial aluminum casting alloys then in production. Those compositions, which also included high levels of iron, were difficult to process. Recently, magnesium replaces iron to reduce density and improve processing. Cerium oxide is an abundant rare earth oxide that is often discarded during the refining of more valuable rare earths such as Nd and Dy. Therefore, the economics are compelling for cerium as an alloy additive. In this review, we report results obtained during an investigation of the processing and properties of aluminum-cerium alloys produced via casting, extrusion and additive manufacturing. The results show mechanical properties are retained at higher temperatures than other aluminum alloys and show complete recovery of mechanical properties at room temperature when exposed to elevated temperatures as high as 500 °C for 1000 h. Alloys containing cerium also have superior corrosion properties when compared to most aluminum alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Gold(I) Cationization Promotes Ring Opening in Lysine-Containing Cyclic Peptides

A strategy to sequence lysine-containing cyclic peptides by MS{sup n} is presented. Doubly protonated cyclic peptides ions are transformed into gold (I) cationized peptide ions via cation switching ion/ion reaction. Gold(I) cationization facilitates the oxidation of neutral lysine residues in the gas phase, weakening the adjacent amide bond. Upon activation, facile cleavage N-terminal to the oxidized lysine residue provides a site-specific ring opening pathway that converts cyclic peptides into acyclic analogs. The ensuing ion contains a cyclic imine as the new N-terminus and an oxazolone, or structural equivalent, as the new C-terminus. Product ions are formed from subsequent fragmentation events of the linearized peptide ion. Such an approach simplifies MS/MS data interpretation as a series of fragment ions with common N- and C-termini are generated. Results are presented for two cyclic peptides, sunflower trypsin inhibitor and the model cyclic peptide, β-Loop. The power of this strategy lies in the ability to generate the oxidized peptide, which is easily identified via the loss of HAuNH{sub 3} from [M + Au]{sup +}. While some competitive processes are observed, the site of ring opening can be pinpointed to the lysine residue upon MS{sup 4} enabling the unambiguous sequencing of cyclic peptides. .

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2013

Intracellular segment between transmembrane helices S0 and S1 of BK channel α subunit contains two amphipathic helices connected by a flexible loop

Highlights: •The loop between S0 and S1 of BK channel was overexpressed and purified in DPC. •NMR studies indicated BK-IS1 contained two helices connected by a flexible loop. •Mg{sup 2+} titration of BK-IS1 indicated two possible binding sites of divalent ions. -- Abstract: The BK channel, a tetrameric potassium channel with very high conductance, has a central role in numerous physiological functions. The BK channel can be activated by intracellular Ca{sup 2+} and Mg{sup 2+}, as well as by membrane depolarization. Unlike other tetrameric potassium channels, the BK channel has seven transmembrane helices (S0–S6) including an extra helix S0. The intracellular segment between S0 and S1 (BK-IS1) is essential to BK channel functions and Asp99 in BK-IS1 is reported to be responsible for Mg{sup 2+} coordination. In this study, BK-IS1 (44–113) was over-expressed using a bacterial system and purified in the presence of detergent micelles for multidimensional heteronuclear nuclear magnetic resonance (NMR) structural studies. Backbone resonance assignment and secondary structure analysis showed that BK-IS1 contains two amphipathic helices connected by a 36-residue loop. Amide {sup 1}H–{sup 15}N heteronuclear NOE analysis indicated that the loop is very flexible, while the two amphipathic helices are possibly stabilized through interaction with the membrane. A solution NMR-based titration assay of BK-IS1 was performed with various concentrations of Mg{sup 2+}. Two residues (Thr45 and Leu46) with chemical shift changes were observed but no, or very minor, chemical shift difference was observed for Asp99, indicating a possible site for binding divalent ions or other modulation partners.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Structural elucidation and immuno-stimulatory activity of a novel polysaccharide containing glucuronic acid from the fungus Echinodontium tinctorium

An immuno-stimulatory polysaccharide (EtISPFa) was purified from water extract of the fungus Echinodontium tinctorium. EtISPFa has an estimated weight average molecular weight (M w ) of 1354 kDa and is composed of glucose (66.2 %), glucuronic acid (10.1 %), mannose (6.7 %), galactose (6.4 %), xylose (5.6 %), rhamnose (3.1 %), fucose (1.8 %), and arabinose (0.2 %). It has multiple glycosidic linkages, with 3-Glcp (19.8 %), 4-GlcpA (10.8 %), 6-Glcp (10.7 %), and 3,6-Glcp (8.7 %) being the most prominent. NMR analysis showed that EtISPFa has a backbone containing mostly of 3-substituted β-glucopyranose with 4-substituted glucopyranosyluronic acid. Short side chains consisting of an average of two β-glycopyranose residues, connected through 1→6 linkages, are attached to the 6-position of about every 4th or 5th backbone glucose residue. EtISPFa is a novel glucuronic acid-containing β-glucan capable of significantly inducing the production of cytokines IL-17, IL-16, MIP-2, G-CSF,GM-CSF, LIF, MIP-1α, MIP-1β, and RANTES in vitro. EtISPFa should be further explored for its immuno-stimulatory activity in vivo.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Simultaneously improved J sc and V oc achieving 19.15% efficiency in ternary blend polymer solar cell containing a Y-type acceptor with thiophene based end groups

Simultaneously enhancing the short-circuit current density (J sc ) and open-circuit voltage (V oc ) of current state-of-the-art polymer solar cells (PSCs) containing wide bandgap polymers as donors and Y6 derivatives as acceptors is of great challenge but essential for further improvement of the photovoltaic performances. Here, in this work, two Y-type non-fullerene acceptors of BTP-T and BTP-TCl were designed and successfully synthesized with relatively weak electron-accepting thiophene based end groups, where blue-shifted absorption and upshifted LUMO energy levels were achieved to fill the well-known absorption gap at 700 nm of typical binary devices based Y-type molecules and rise the output voltage, respectively. Simultaneously increased J sc and V oc were achieved in ternary blend devices containing D18:BTP-eC9:BTP-TCl with a significantly improved PCE up to 19.15 %, which is over 7 % increase compared to the binary device. Our results illustrated the great potential of rational design of Y6 derivatives for constructing ternary PSCs to improve their performances.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Predicting effective thermal and elastic properties of cementitious composites containing polydispersed hollow and core-shell micro-particles

Micro- and nano-sized hollow and core-shell particles (CSPs) have attracted tremendous interests in developing functional cementitious composites and concretes. In this paper, a general method is developed to predict the thermal and elastic properties of cementitious composites containing core-shell and hollow micro-particles. The model follows a two-stage homogenization process – CSP inclusions together with their surrounding interfacial transition zone (ITZ) are first treated as equivalent solid particles, and then the homogenized properties of the composite system are obtained using numerical (i.e., finite element) or analytical (Mori-Tanaka) approaches. Compared with other homogenization methods, the proposed model is easy-to-use and versatile. The numerical model, validated by experimental results, is then used to guide the design of functional cementitious composites. The results show that CSP particle size (or relative shell thickness), volume fraction, shell property, and the size of the ITZ have significant impacts on the effective thermal and elastic properties of cementitious composites; whereas the particle size distribution pattern has relatively minor influence. In addition, the effective property of the composite is more sensitive to the particle property change when CSP inclusions are much stiffer or more thermally conductive than the matrix. Lastly, a scoping study is conducted to elucidate the relationship between the effective thermal conductivity and effective elastic moduli for cementitious composites containing CSP additives with different shell materials, particle sizes, and volume concentrations etc.

36 MATERIALS SCIENCE↗
DOE OSTI2014

A modified ASTM C1012 procedure for qualifying blended cements containing limestone and SCMs for use in sulfate-rich environments

Blended Portland cements containing up to 15% limestone have recently been introduced into Canada and the USA. These cements were initially not allowed for use in sulfate environments but this restriction has been lifted in the Canadian cement specification, provided that the “limestone cement” includes sufficient SCM and that it passes a modified version of the CSA A3004-C8 (equivalent to ASTM C1012) test procedure run at a low temperature (5 °C). This new procedure is proposed as a means of predicting the risk of the thaumasite form of sulfate attack in concretes containing limestone cements. The goal of the present study was to better understand how this approach works both in practice and in theory. Results from three different laboratories utilizing the CSA A3004-C8 test procedure are compared and analyzed, while also taking into account the results of thermodynamic modeling and of thaumasite formation experiments conducted in dilute suspensions.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Influence of calcium and magnesium carbonates on hydration kinetics, hydrate assemblage and microstructural development of metakaolin containing composite cements

The hydration of metakaolin composite cements containing quartz, natural limestone and dolomite rock is studied using a multi-method approach and modelling. The study demonstrates that the calcite present in limestone and dolomite rock is very reactive. Contrary, dolomite does not dissolve. Additionally to the previously reported stabilization of ettringite, the reaction of calcite introduces several changes to the mechanism of metakaolin pozzolanic reaction. Namely, the silicate and aluminate distribution among the hydrates is different. In carbonate containing samples, experimental results supported by the thermodynamic modelling suggest that the silicate mainly precipitates as low Ca/Si C-S-H and additionally the ettringite content is higher. In the case of quartz analogue, the silicates precipitate as strätlingite and C-S-H of higher Ca/Si. These changes cause lower porosity as observed by SEM-BSE and higher strength. High metakaolin reactivity results in a very dense matrix that in turn enables co-existence of phases that are thermodynamically non-compatible.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Rheology of fresh cement pastes containing polymer nanoparticles

Influences of polymer nanoparticles (PNPs) with varied charge densities on the rheological behaviors of fresh cement pastes (fcps) without and with polycarboxylate superplasticizer (PCE) were studied. In the blank fcp, the addition of PCE and highly anionically charged PNPs greatly decreases the yield stress and the plastic viscosity due to their large adsorption on cement that produces electrostatic repulsion and steric hindrance between cement grains. However, the non-adsorbing nonionic PNPs show a slightly opposite effect. In the PCE-containing fcp, both the anionic and nonionic PNPs become non-adsorbing on cement due to the stronger affinity of PCE to cement surface. In this way, the addition of the PNPs in the PCE-containing fcp slightly increases the yield stress and the plastic viscosity, but significantly decreases the pseudoplastic index, which is believed to result from the generation of the so-called depletion attractive force between cement grains induced by the non-adsorbing polymers.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Autogenous shrinkage and hydration property of alkali activated slag pastes containing superabsorbent polymer

In this paper, the superabsorbent polymer (SAP) was applied as internal curing agent to study its effect on the autogenous shrinkage and hydration property of alkali activated slag (AAS) pastes. Liquid absorption and release processes of SAP in AAS pastes were characterized by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR). Moreover, the microstructure and mechanical strength of AAS pastes containing SAP were also revealed. The results showed that the autogenous shrinkage of AAS pastes containing SAP was reduced by about 80.6%, 72.1% and 72.6%, respectively as the silicate modulus (Ms) increased from 0.8 to 1.4. The addition of SAP delayed the second exothermic peak, but increased the cumulative heat of AAS pastes. In addition, internal curing by SAP could promote the generation of C-A-S-H gels and hydrotalcite-like phases and increase the reaction degree of slag, particularly for AAS pastes with higher Ms, being attributed to the continuous release of entrained water and alkali activator solutions in SAP with the increase of hydration time. Furthermore, the addition of SAP would increase capillary pore size and pore volume of AAS pastes, and thus lead to the decrease of compressive strength.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Polymeric ionic liquids containing copper(I) and copper(II) ions as gas chromatographic stationary phases for olefin separations

Copper(I) ions (Cu + ) are used in olefin separations due to their olefin complexing ability and low cost, but their instability in the presence of water and gases limits their widespread use. Ionic liquids (ILs) have emerged as stabilizers of Cu + ions and prevent their degradation, providing high olefin separation efficiency. There is limited understanding into the role that polymeric ionic liquids (PILs), which possess similar structural characteristics to ILs, have on Cu + ion-olefin interactions. Moreover, copper ions with diverse oxidation states, including Cu + and Cu 2+ ions, have been rarely employed for olefin separations. In this study, gas chromatography (GC) is used to investigate the interaction strength of olefins to stationary phases composed of the 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C 6 MIM + ][NTf 2 – ]) IL and the poly(1-hexyl-3-vinylimidazolium [NTf 2 – ]) (poly([C 6 VIM + ][NTf 2 – ])) PIL containing monovalent and divalent copper salts (i.e., [Cu + ][NTf 2 – ] and [Cu 2+ ]2[NTf 2 – ]). The chromatographic retention of alkenes, alkynes, dienes, and aromatic compounds was examined. Incorporation of the [Cu 2+ ]2[NTf 2 – ] salt into a stationary phase comprised of poly(dimethylsiloxane) resulted in strong retention of olefins, while its addition to the [C 6 MIM + ][NTf 2 – ] IL and poly([C 6 VIM + ][NTf 2 – ]) PIL allowed for the interaction strength to be modulated. Olefins exhibited greater affinities toward IL and PIL stationary phases containing the [Cu 2+ ]2[NTf 2 – ] salt compared to those with the [Cu + ][NTf 2 – ] salt. Elimination of water from both copper salts was observed to be an important factor in promoting olefin interactions, as evidenced by increased olefin retention upon exposure of the stationary phases to high temperatures. Furthermore, to evaluate the long-term thermal stability of the stationary phase, chromatographic retention of probes was measured on the [Cu 2+ ]2[NTf 2 – ]/[C 6 MIM + ][NTf 2 – ] IL stationary phase after its exposure to helium at a temperature of 110°C.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Enhanced crevice corrosion of stainless steel 316 by degradation of Cr-containing hollandite crevice former

This study explores the corrosion interactions between stainless steel 316 (SS316), a candidate nuclear waste canister material, and Cr-containing hollandite (Ba 1.15 Cr 2.3 Ti 5.7 O 16 ), a model ceramic nuclear waste form. The two materials were corroded in close proximity in 0.6 M NaCl solution at 90 °C for 28 days. Severe crevice corrosion was observed on the stainless steel surface after the corrosion experiment, which is likely associated with the rapid accumulation of Cr 3+ cations originating from both SS316 and the Cr-containing hollandite. Furthermore, the enhanced corrosion of SS316 by the corrosion products of hollandite is quantitatively explained using a classical crevice corrosion model.

36 MATERIALS SCIENCE↗