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Results for “RE”
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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Re-envisioning laser sources and alloys for metal Additive Manufacturing
Not Available
Re-directing mixed-feed deconstruction products to hybrid polyesters: Tolerance windows for commodity plastics reconstruction
Solvolysis is a promising strategy for mixed-feed polyester recycling, but little attention has been given to downstream product separations or the impact of using imperfectly separated monomer mixtures in recycled polymer reconstruction. Here, we challenge the traditional need for high-purity monomers in polycondensation synthesis of engineering thermoplastics. Monomer mixtures are derived from catalyzed methanolysis of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polybutylene adipate-co-terephthalate (PBAT), with separation scenarios ranging from high (99:1) to low (90:10) purity. We focus on challenging-to-separate products like ethylene glycol and 1,4-butanediol and evaluate tolerance for comonomer incorporation in recycled hybrid polyesters: polybutylene-co-ethylene terephthalate (PBET) and polybutylene ethylene adipate-co-terephthalate (PBEAT). Evaluations are made between “contaminant” monomer incorporation, and the resulting materials’ thermal properties, crystalline structure, tensile toughness, and rheology. Ultimately, we highlight that despite incorporation of contaminant monomer, high-performance hybrid polyesters of PET, PBT, and PBAT are obtained while reducing the strain of high-throughput separations.
A microgrid control scheme for islanded operation and re-synchronization utilizing Model Predictive Control
Not provided.
Fabric characteristics and processes influencing the liquefaction and re-liquefaction of sand
Although the density of sand has long been considered to be the predominant factor for liquefaction resistance, observations during earthquake sequences and laboratory tests have suggested that other factors may also cause significant anomalies in the relationship between density and liquefaction resistance. This study pinpoints the fabric characteristics and processes influencing the liquefaction resistance of sand. Numerical DEM tests on 2D polydispersed circular granular material are conducted on specimens with various stress-strain and liquefaction histories, showing that changes in micromechanical fabric characteristics of sand can indeed influence its liquefaction resistance, even overpowering the influence of overall density under certain conditions. The liquefaction resistance of initially isotropic sand is strongly correlated with the amount of increase in mean neighboring particle distance needed for it to reach liquefaction (ΔMNPD liq ). Smaller ΔMNPD liq results in weaker liquefaction resistance. Furthermore, fabric anisotropy also significantly affects the liquefaction resistance of sand, due to its influence on dilatancy. Greater fabric anisotropy intensity results in smaller liquefaction resistance. The findings in this study enhances the understanding of liquefaction behavior of sand by establishing a link between the changes in quantifiable fabric states and liquefaction resistance.
Re-thinking incentives and penalties: Economic aspects of waste management in Italy
Highlights: • We focused on the dynamics the formation of operational costs of waste management. • We provide the basic elements to compose a picture of economic management. • We present a reflection on the last hidden costs associated with the consumption of goods and packaging. • Reduction of waste production. - Abstract: This paper focuses on the dynamics the formation of operational costs of waste management in Italy and the effect of economic measures. Currently incentives and penalties have been internalized by the system no differently from other cost items and revenues. This has greatly influenced the system directing it towards solutions that are often distant from the real environmental objectives. Based on an analysis of disaggregated costs of collection treatment and recovery, we provide the basic elements to compose a picture of economic management in various technical–organizational scenarios. In the light of the considerations contained in the paper it is proposed, e.g. for controlled landfills, that the ecotax, currently based on weight, could be replaced by one based on the volume consumption. Likewise, for tax reduction on disposal system, instead a pre-treatment might ask an environmental balance of the overall system. The article presents a reflection on the last hidden costs associated with the consumption of goods and packaging, and how to reduce waste production is the necessary path to be followed in ecological and economic perspectives.
Wnt inhibition is dysregulated in gliomas and its re-establishment inhibits proliferation and tumor sphere formation
Evidence indicates that the growth of glioblastoma (GBM), the most common and malignant primary brain cancer, is driven by glioma stem cells (GSCs) resistant to current treatment. As Wnt-signaling is pivotal in stem cell maintenance, we wanted to explore its role in GSCs with the objective of finding distinct signaling mechanisms that could serve as potential therapeutic targets. We compared gene expression in GSCs (n=9) and neural stem cells from the adult human brain (ahNSC; n=3) to identify dysregulated genes in the Wnt signaling pathway. This identified a six-gene Wnt signature present in all nine primary GSC cultures, and the combined expression of three of these genes (SFRP1, SFRP4 and FZD7) reduced median survival of glioma patients from 38 to 17 months. Treatment with recombinant SFRP1 protein in primary cell cultures downregulated nuclear β-catenin and decreased in vitro proliferation and sphere formation in a dose-dependent manner. Furthermore, expressional and functional analysis of SFRP1-treated GSCs revealed that SFRP1 halts cell cycling and induces apoptosis. These observations demonstrate that Wnt signaling is dysregulated in GSC, and that inhibition of the Wnt pathway could serve as a therapeutic strategy in the treatment of GBM. - Highlights: • A comparison of GSCs to ahNSCs reveals Wnt-pathway dysregulation. • A signature of six Wnt-genes is present in all nine primary tumors. • The expression of three Wnt-genes reduces median survival from 38 to 17 months. • Treatment with SFRP1 decreases in vitro proliferation and sphere formation. • SFRP1 regulates GSC tumorigenicity through regulation of cell cycle and apoptosis.
Understanding the Role of Inter- and Intramolecular Promoters in Electro- and Photochemical CO 2 Reduction Using Mn, Re, and Ru Catalysts
Not Available
Rotational Disorder in Scheelite-Type NaRE(MO4)2 (RE = Rare-Earth, Y; M = Mo, W)
Abstract not provided
Bi 13 S 18 I 2 : (Re)discovery of a Subvalent Bismuth Compound Featuring [Bi 2 ] 4+ Dimers Grown in Sulfur/Iodine Flux Mixtures
Abstract not provided
Molecular Catalysts with Intramolecular Re–O Bond for Electrochemical Reduction of Carbon Dioxide
Not Available
A Note to Reviewers Suggesting Post-reaction Catalyst Characterization: Know What You’re Asking For
Here, we highlight examples of post-reaction characterization in thermo- and electrocatalysis to present the challenges in obtaining reliable data to answer specific questions about the true identity of the active site and/or catalyst deactivation/degradation. We use this editorial to suggest to reviewers that, when formulating comments to authors that involve materials characterization after reaction testing, they should consider what specific, meaningful information can be attained or what targeted question can be answered that adds value to the individual paper and to the field in general, and how to reasonably obtain that data. In contrast, reviewers should avoid vague, open-ended comments that suggest unguided post-reaction characterization that would not add significant value to the report and, similarly, avoid comments that are substantial enough that they could form the basis of an entirely separate report.
Structural Investigation of Six Quinary Sulfides Synthesized via the Flux-Assisted Boron-Chalcogen Mixture (BCM) Method: Eu 2+ Containing Members of the RE 3 MTQ 7 (M and T = Transition or Main Group Metals, Q = Chalcogens) Family
For this work, a series of six quinary rare-earth sulfides Ce 4+ 1.85 Eu 2+ 1.15 Na 0.30 SiS 7 , Ce 4+ 1.91 Eu 2+ 1.09 K 0.18 SiS 7 , Ce 4+ 1.96 Eu 2+ 1.04 Rb 0.08 SiS 7 , Ce 4+ 1.98 Eu 2+ 1.02 Cs 0.05 SiS 7 , Ce 4+ 1.97 Eu 2+ 1.03 Ag 0.06 SiS 7 , and Ce 4+ 1.50 Eu 2+ 1.50 CuSiS 7 were obtained in an alkali iodide flux using the boron-chalcogen mixture (BCM) method. Single crystal X-ray diffraction was used to determine the structures of the high quality single crystals that were grown; their elemental compositions were confirmed by energy-dispersive spectroscopy (EDS). The compounds crystallize in the hexagonal crystal system in the noncentrosymmetric space group P63. The crystal structure consists of a three-dimensional network composed of mixed cerium and europium bicapped trigonal prisms, isolated SiS4 tetrahedra, and monovalent metals (Na, K, Rb, Cs, Ag, and Cu) located in cavities created by linked Ce/EuS 8 polyhedra. The structures are charge-balanced when Ce and Eu are in their +4 and +2 oxidation states, respectively. The effective magnetic moment of Ce 1.50 4+ Eu 1.50 2+ CuSiS 7 determined from the temperature dependence of the magnetic susceptibility data is consistent with the presence of Ce 4+ and Eu 2+ . Clear correlations between the alkali ion site occupancy, the ionic radius of the alkali cations, and the average bond length of Ce 4+ /Eu 2+ –S, were established. UV–vis diffuse reflectance data were collected for Ce 1.50 4+ Eu 1.50 2+ CuSiS 7 and a band gap of 1.9(1) eV was established.