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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 1,351 records · Page 75
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Optical properties and zero photoelastic constant of ns{sup 2}-type metal cation containing oxide glasses

Zero photoelasticity and the relevant optical properties in binary RO–SiO{sub 2} (R = Sn, Pb) and R′{sub 2}O{sub 3}–SiO{sub 2} (R′ = Sb, Bi) and ternary Bi{sub 2}O{sub 3}–B{sub 2}O{sub 3}–SiO{sub 2} glasses were systematically studied. The zero photoelastic silicate glass leads to zero stress-induced birefringence, providing application to an optical lens, a filter, a beam splitter, and a fiber optic sensor without stress-induced birefringence. In this study, a variety of zero photoelastic binary silicate and ternary borosilicate glasses with optical bandgaps of 3.1–3.9 eV containing highly polarized ns{sup 2}-type cations are reported.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2025

Characterization of SiO 2 Thermally Grown Oxide Stress Evolution of EBCs with Al-Containing Dopants

SiC/SiC ceramic matrix composites (CMCs) are desired for use in combustion environments to achieve higher turbine operating temperatures. However, CMCs require environmental barrier coatings (EBCs) for protection from the gas environment. EBC systems are known to primarily fail through coating delamination via growth of a thermally grown oxide (TGO) at the EBC—silicon bond coating interface when exposed to steam, which accelerates the TGO growth rate. The TGO undergoes a phase transformation during thermal cycling, which results in stresses that may encourage EBC spallation. Yb-silicate EBCs with mullite and yttrium aluminum garnet (YAG) dopant additions were deposited on SiC substrates with a Si intermediate bond coating and exposed to thermal cycling in steam at 1350 °C. The impact of Al dopant additions on the TGO growth rate and the SiO 2 phase transformation was assessed. Photo-stimulated luminescence spectroscopy (PSLS) was used to characterize the Al-containing phases and to measure stress evolution in the EBC following exposure using the stress-induced peak shift of the R-lines of mullite. Raman microscopy was used to map the stresses in the Si bond coating following exposure. It was found that the TGO phase transformation upon cooling increased compressive stress in the Si bond coating within 15 µm of the TGO.

Building Materials↗
DOE OSTI2017

Synthesis of thioether-containing carbosilane dendrimers with sterically shielded sulfur atoms

Carbosilane thiols were synthesized as the first- and second-generation (in silicon) dendrons. It was demonstrated that the resulting bulky thiols successfully undergo the thiol—ene addition to third-generation polyallyl carbosilane dendrimer as a photoinitiated radical reaction to give the corresponding thioether-containing derivatives with sterically shielded sulfur atoms.

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

New indoline spiropyrans containing azomethine fragment

The new spiropyran systems with an azomethine bridge were synthesized from a spiropyran containing aminogroup at 6′ position of the benzopyran fragment and substituted aromatic aldehydes. The chemical structure of compounds is confirmed by elemental analysis data, NMR ({sup 1}H and {sup 13}C) and IR spectroscopy. Photochemical studies revealed the presence of photochromic properties at room temperature for one of the obtained spiropyrans.

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

Fe-containing nanocomposites based on a biocompatible copolymer 1-vinyl-1,2,4-triazole with N-vinylpyrrolidone

New polymer nanocomposites containing iron oxide nanoparticles stabilized with a biocompatible copolymer of 1-vinyl-1,2,4-triazole with N-vinylpyrrolidone were produced. The synthesis was conducted using the method of chemical reduction of iron ions with hydrazine hydrate in an aqueous medium in the presence of a polymer matrix. The ESR spectroscopy data showed that the core—shell type nanoparticles were obtained. The core generally consistsed of zero-valence iron coated with an oxide shell. According to the data of transmission electron microscopy, the obtained polymer nanocomposites consisted of nanoparticles of mainly spherical shape with a diameter from 1 to 14 nm. Aggregates formed from individual stabilized nanoparticles of up to 75 nm in size (in most cases) were also observed. These aggregated particles were found to self-organize and form branched chains. Nanocomposites were characterized by a different particle-size distribution, which was determined by the initial ratio of the copolymer and the precursor of iron nanoparticles.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Synthesis and structural features of new pentacoordinated monofluorosilanes containing C,O-chelate ligands based on 2-amino acid N-methylamides

Pentacoordinated monofluorosilanes R{sup 1}SO{sub 2}NHCHR{sub 2}C(O)N(Me)CH{sub 2}SiMe{sub 2}F containing moieties of N′-methyl-N-(organosulfonyl)-2-amino acid amides of glycine, alanine, and leucine as C,O-chelating ligands were synthesized via the reaction of corresponding disiloxanes with BF{sub 3}•Et{sub 2}O. The structures of obtained compounds were investigated by single-crystal X-ray diffraction analysis.

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

Vibrational spectra and electronic structure of 11-vertex boron-containing clusters: a comparative study of [B{sub 11}H{sub 11}]{sup 2–}, [CB{sub 10}H{sub 11}]{sup –}, and C{sub 2}B{sub 9}H{sub 11}

Vibrational spectroscopy studies of 11-vertex boron-containing clusters [B{sub 11}H{sub 11}]{sup 2–}(1), [2-CB{sub 10}H{sub 11}]{sup –} (2), and 2,3-C{sub 2}B{sub 9}H{sub 11} (3) revealed two low-frequency large-amplitude modes in their spectra and, therefore, structural nonrigidity of these polyhedra in contrast to related 12-, 10-, and 6-vertex closo-clusters. The nonrigidity originates from specific features of the electron density distribution. According to calculations within the framework of the 'Atoms in Molecule' (AIM) theory, these polyhedra are characterized by the lack of many bond paths localized on corresponding edges, in particular, between boron atoms with coordination numbers of 6 and 5 (6k and 5k). Consequently, these polyhedra are composed of not only trigonal faces, i.e., formally do not have the closo-structure that was traditionally ascribed to them based on formal count of (2n + 2) valence electrons. According to calculations of three-center delocalization indices, the absence of bond paths is not equivalent to the lack of interaction between corresponding atoms since this interaction occurs through open three-center bonds. The mechanism and reasons for signal averaging observed in {sup 11}B NMR spectra of compounds 1 and 2 in contrast to 3 are analyzed.

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

Novel diphenylsulfimide antioxidants containing 2,6-di-tert-butylphenol moieties

New diphenylsulfimide derivatives containing substituents with the 2,6-di-tert-butylphenol moiety at the nitrogen atom were synthesized. Their molecular structures were established by X-ray diffraction. Antioxidant activity was experimentally evaluated by spectrophotometry based on hydrogen transfer to the stable radicals, namely, 2,2-diphenyl-1-picrylhydrazyl and the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS{sup ·+}), and using in vitro lipid peroxidation in rat brain and liver homogenates. The presence of phenol and diphenylsulfimide moieties in one molecule leads to a significant enhancement of antioxidant activity. The new compounds exhibit moderate inhibitory activity against enzymes involved in carbohydrate and lipid metabolism. The evaluation of antiglycation activity showed that the new sulfimides taken at a concentration of 100 μmol L{sup –1} have activity comparable with that of aminoguanidine.

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

Methyl esters of 2-aminotetrahydrobenzothiophene-3-carboxylic acids decorated with trifluoromethyl-containing heterocycles

Methyl 2-aminothiophene-3-carboxylates were modified with trifluoromethyl-containing five-membered heterocycles by cyclocondensation of methyl trifluoropyruvate N-thiophen-2-ylimines with 1,3-N,N-binucleophiles (2-aminothiazoline and benzamidines) to obtain the corresponding 5-oxo-6-trifluoromethyl-2,3,5,6-tetrahydroimidazoles and 5-oxo-2-phenyl-4-trifluoromethyl-4,5-dihydro-1H-imidazoles. Radioligand binding was used to study the in fluence of the synthesized compounds on the neuronal NMDA receptors.

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

The K5 capsular polysaccharide of the bacterium Acinetobacter baumannii SDF with the same K unit containing Leg5Ac7Ac as the K7 capsular polysaccharide but a different linkage between the K units

The K5 capsular polysaccharide (CPS) was isolated from the bacterium Acinetobacter baumannii (A. baumannii) SDF and studied by 1D and 2D {sup 1}H and {sup 13}C NMR spectroscopy before and after O-deacetylation and partial acid hydrolysis. The CPS was found to be composed of branched tetrasaccharide repeats (K units) containing 5,7-diacetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto-non-2-ulosonic acid (Leg5Ac7Ac). The KL5 capsule biosynthesis gene cluster at the K locus is consistent with the composition and structure of the CPS. KL5 is almost identical to the KL7 gene ulosonic acid (Leg5Ac7Ac A. baumannii LUH5533 that has been characterized earlier, and differs only in the gene for Wzy polymerase that is responsible for the formation of the linkage between the K units. The K5 CPS from strain SDF and the K7 CPS from strain LUH5533 have the same K-unit structure but a different linkage between the K units, which is formed by distinct Wzy polymerases. As opposite to Leg5Ac7Ac in the K7 CPS, this monosaccharide is O-acetylated at position 4 in the K5 CPS. No acetyltransferase for this modification of the K5 CPS is present in the KL5 gene cluster, and hence it is encoded by a gene located elsewhere in the genome.

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

Equilibrium, kinetic, and thermodynamic studies on the sorption of some heavy metal ions by the phosphorus-containing polymer sorbent

The sorption of Cu+{sup 2}, Ni+{sup 2}, Co+{sup 2}, and Zn+{sup 2} ions onto the phosphorus-containing sorbent were studied as a function of the contact time, temperature, and concentration of the initial metal ions. The equilibrium studies are presented by the Langmuir, Freundlich, and Temkin isotherm models. The sorption data are well described by the Langmuir isotherm model, and they also can be simulated by the Freundlich isotherm model. The pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were applied to test the experimental data of the kinetic studies. The pseudo-second-order kinetic model provided the best correlation of the experimental data compared to the other kinetic models. The sorption capacity of the metal ions increased with temperature increasing. The positive value of enthalpy (ΔH°) and the negative value of Gibbs free energy (ΔG°) indicated that the sorption process was endothermic and spontaneous.

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

Synthesis and structure of lithium 3-trifluoromethyl-1,3-diketonates containing pyridyl substituents

Lithium 3-trifluoromethyl-1,3-diketonates containing pyridyl substituents were synthesized. The specific features of the crystal structures of lithium (Z)-1,1,1-trifluoro-4-oxo-4-(pyridin-3-yl)- and (Z)-1,1,1-trifluoro-4-oxo-4-(pyridin-4-yl)but-2-en-2-olates were revealed by X-ray diffraction. These compounds have a polymeric structure with lithium cations in different coordination modes. The 1,3-diketonate group is involved in chelation and formation of oxygen bridges, thereby linking two types of lithium atoms.

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

Synthesis and biological activity of new polymeric silver-containing nanocomposites

The formation of new polymeric nanocomposites with silver nanoparticles incorporated into the matrix of 1-vinyl-1,2,4-triazole copolymers with vinyl acetate was studied. Water-soluble nanocomposites containing different amounts of silver nanoparticles with an average size of 6–13 nm were synthesized varying the reaction conditions. The physicochemical, optical, thermal, and structural properties of the nanocomposites were studied by IR and UV spectroscopy, transmission electron microscopy, X-ray diffraction and atomic absorption analyses, and thermogravimetry. The antimicrobial activity of the initial copolymers and related nanocomposites was evaluated with respect to test microorganisms.

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

Dephosphorization Kinetics between Bloated Metal Droplets and Slag Containing FeO: The Influence of CO Bubbles on the Mass Transfer of Phosphorus in the Metal

Dephosphorization kinetics of bloated metal droplets was investigated in the temperature range from 1813 K to 1913 K (1540 °C to 1640 °C). The experimental results showed that the overall mass transfer coefficient, k{sub o}, decreased with increasing temperature because of decreasing phosphorus partition ratio, L P . It was also found that the mass transfer coefficient for phosphorus in the metal, k m , had the highest value at the lowest temperature [i.e., 1813 K (1540 °C)] because the formation of smaller CO bubbles increased the rate of surface renewal, leading to faster mass transport. Meanwhile, metal droplets without carbon were also employed to study the effect of decarburization on dephosphorization. The results show that although decarburization lowers the driving force significantly, k{sub m} (6.2 × 10 -2 cm/s) for a carbon containing droplet is two orders of magnitude higher than that for carbon free droplets (5.3 × 10 -4 cm/s) because of the stirring effect provided by CO bubbles. This stirring offers a faster surface renewal rate, which surpasses the loss of driving force and then leads to a faster dephosphorization rate.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Be Modification on the Oxide Bifilms and Tensile Strength Reliability of Al-Si-Mg Alloys Containing Excess Fe

The effect of oxide bifilms and Be modification (0.2 wt pct) on the tensile strength reliability of the as-cast and T{sub 6} heat-treated Al-9Si-0.35Mg-1.5Fe alloy was investigated using Weibull analysis. For this purpose, the density of oxide bifilms in the molten alloy was intentionally increased by surface agitation. According to the results, Be modifies the β-Al{sub 5}FeSi particles to the less harmful α-Fe compounds and substantially decreases the bifilm density in the castings leading to improved tensile properties and higher reliability. Moreover, the beneficial effect of Be was found to be more in the samples containing higher amounts of bifilms. For instance, in the heat-treated condition, Be increased the Weibull modulus of the non-agitated and surface-agitated samples by 4 and 94 pct, respectively. This improvement can be attributed to the strengthening effect of Be on the young surface oxides so that they resist more against rupture when melt is subjected to the surface turbulence. The reduced pressure test and fractography investigations also confirmed the reduction of bifilm density and bifilm-related defects in Be-modified samples.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Development of Kinetic Model for Reactions Between Cu-Containing Multicomponent Slag and Liquid Sulfide Using Coupled Reaction Model

Copper smelting slag contains less than 2 mass pct of Cu oxide and 30–50 mass pct of Fe{sub x}O. Each year, the grade of copper ore decreases, while the amount of slag generated in the copper smelting process increases. In this study, a coupled reaction model to simulate the reaction between multicomponent slag and FeS-based matte was developed using reported thermodynamic data and double-film theory for the recycling of copper smelting slag. The activity coefficients of oxides in the multicomponent slag were calculated using a regular solution. The activity coefficients of Cu{sub 2}O in the slag and those of FeS, Cu{sub 2}S, and CaS in the FeS-based matte used previously reported data. The behaviors of Cu in slag and matte were confirmed by comparing the simulated results and the reported solubility of Cu in the slag in the temperatures ranging from 1473 K to 1573 K. In addition, the effect of the input amount of FeS on the copper content of the slag was verified by comparing the results of reaction model to experimental results. Using the reaction model, the influences of the initial ratio of FeO/SiO{sub 2} of the slag, temperature, and matte composition on the behaviors of Cu in the slag and matte were investigated.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Mechanism of Low-Temperature Reduction Degradation of Alumina-Containing Hematite Solid Solution Below 550 °C

Low-temperature reduction degradation (LTRD) of sinter has an adverse effect on blast furnace permeability, and it is mainly caused by the stress produced in the reduction process of hematite. This stress is strongly influenced by alumina dissolved in hematite crystal lattice. In this work, the experiments were conducted to investigate the effect of alumina dissolved in hematite solid solution (H{sub ss}) on LTRD by reducing H{sub ss} below 550 °C. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and optical microscope have been used to characterize the mass change and mineral change of samples, respectively. Jade software has been used to calculate the micro strain in magnetite for quantitatively studying the change of strain in reducing process. The results show that alumina was unfavorable to the reduction of H{sub ss} on thermodynamics, and the starting reduction temperature of H{sub ss} containing 6.0 mol pct alumina was 28 °C higher than that of pure hematite. According to the calculation on kinetics, the generation rate of stress was accelerated by dissolving alumina into hematite crystal lattice. The apparent activation energy of reduction reaction lowered from 47.89 to 28.07 kJ/mol with the increase of alumina content from 0.0 to 6.0 mol pct. The addition of alumina also increased the stress in the reduction products, and this stress was released in the form of LTRD.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Formation Mechanism of Al{sub 2}O{sub 3}-Containing Inclusions in Al-Deoxidized Spring Steel

The source, characteristics, and mechanism of Al{sub 2}O{sub 3}-containing inclusions in Al-deoxidized spring steel were investigated using electron-probe X-ray microanalysis (EPMA). Spring samples were collected during vacuum degassing (VD) refining, in a tundish ladle, and after hot rolling, respectively. Based on primary inclusion components, seven types of inclusions were observed through the manufacturing process: Al{sub 2}O{sub 3}, Al{sub 2}O{sub 3}-SiO{sub 2}, Al{sub 2}O{sub 3}-CaO, Al{sub 2}O{sub 3}-MgO, Al{sub 2}O{sub 3}-MgO-CaO, Al{sub 2}O{sub 3}-SiO{sub 2}-MnO, and Al{sub 2}O{sub 3}-SiO{sub 2}-CaO. The Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-SiO{sub 2} inclusions were mainly attributed to deoxidization products, less than 15 μm in diameter and with liquidus temperatures exceeding 1600 °C. For Al{sub 2}O{sub 3}-CaO inclusions, which were considered to be formed by the reduction of entrapped slag by Al dissolved in the steel, the Al{sub 2}O{sub 3}/CaO ratio obviously decreased with the increase of inclusion sizes. Most Al{sub 2}O{sub 3}-SiO{sub 2}-CaO inclusions were less than 15 μm in diameter, with their composition close to that of the refining slag and a liquidus temperature near 1500 °C. The Al{sub 2}O{sub 3}-MgO and Al{sub 2}O{sub 3}-SiO{sub 2}-MnO inclusions originated from inherent reactions between dissolved [Al], [Si], [Mn], [Mg], and [O] in the steel. Al{sub 2}O{sub 3}-MgO-CaO inclusions resulted from coalescence between Al{sub 2}O{sub 3}-MgO and Al{sub 2}O{sub 3}-CaO inclusions.

36 MATERIALS SCIENCE↗