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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 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Mathematical modeling of a moving bed reactor for post-combustion CO 2 capture

A mathematical model for a moving bed reactor with embedded heat exchanger has been developed for application to solid sorbent-based capture of carbon dioxide from flue gas emitted by coal-fired power plants. The reactor model is one-dimensional, non-isothermal, and pressure-driven. The two-phase (gas and solids) model includes rigorous kinetics and heat and mass transfer between the two phases. Flow characteristics of the gas and solids in the moving bed are obtained by analogy with correlations for fixed and fluidized bed systems. From the steady-state perspective, this work presents the impact of key design variables that can be used for optimization. From the dynamic perspective, the article shows transient profiles of key outputs that should be taken into account while designing an effective control system. Additionally, the article also presents performance of a model predictive controller for the moving bed regenerator under process constraints.

42 ENGINEERING↗
DOE OSTI2015

Post‐Assembly Stabilization of Rationally Designed DNA Crystals

Abstract This manuscript reports an effort to stabilize self‐assembled DNA crystals. Owing to their weak inter‐unit cohesion, self‐assembled DNA crystals are fragile, which limits the potential applications of such crystals. To overcome this problem, another molecule was introduced, which binds to the cohesive sites and stabilizes the inter‐unit interactions. The extra interactions greatly improve the stability of the DNA crystals. The original DNA crystals are only stable in solutions of high ionic strength (e.g., ≥1.2 M (NH 4 ) 2 SO 4 ); in contrast, the stabilized crystals can be stable at ionic strengths as low as that of a 0.02 M solution of (NH 4 ) 2 SO 4 . The current strategy is expected to represent a general approach for increasing the stability of self‐assembled DNA nanostructures for potential applications, for example, as structural scaffolds and molecular sieves.

Zhao, Jiemin↗
DOE OSTI2015

Post‐Assembly Stabilization of Rationally Designed DNA Crystals

Abstract This manuscript reports an effort to stabilize self‐assembled DNA crystals. Owing to their weak inter‐unit cohesion, self‐assembled DNA crystals are fragile, which limits the potential applications of such crystals. To overcome this problem, another molecule was introduced, which binds to the cohesive sites and stabilizes the inter‐unit interactions. The extra interactions greatly improve the stability of the DNA crystals. The original DNA crystals are only stable in solutions of high ionic strength (e.g., ≥1.2 M (NH 4 ) 2 SO 4 ); in contrast, the stabilized crystals can be stable at ionic strengths as low as that of a 0.02 M solution of (NH 4 ) 2 SO 4 . The current strategy is expected to represent a general approach for increasing the stability of self‐assembled DNA nanostructures for potential applications, for example, as structural scaffolds and molecular sieves.

Zhao, Jiemin↗
DOE OSTI2021

In-situ observation of pre-, co- and post-seismic shear slip at 1.5 km depth

Understanding the initiation and arrest of earthquakes is one of the long-standing challenges of seismology. Here we report on direct observations of borehole displacement by a meter-sized shear rupture induced by pressurization of metamorphic rock at 1.5 km depth. We observed the acceleration of sliding, followed by fast co-seismic slip and transient afterslip. Total displacements were about 7, 5.5 and 9.5 micrometers, respectively for the observed pre-slip, co-seismic slip and afterslip. The observed pre-slip lasted about 0.4 seconds. Co-seismic slip was recorded by the 1 kHz displacement recording and a 12-component array of 3-C accelerometers sampled at 100 kHz. The observed afterslip is consistent with analytical models of arrest in a velocity-strengthening region and subsequent stress relaxation. < p >The observed slip vector agrees with the activation of a bedding plane within the phyllite, which is corroborated by relocated seismic events that were observed during the later stages of the injection experiment.

Schoenball, Martin↗
DOE OSTI2018

An Efficient Post-Polymerization Modification of Poly(Styrene- co -Maleic Anhydride) for Thermally Reversible Nanocomposites

A copolymer of maleic anhydride and styrene is functionalized with Diels–Alder (DA) capable pendant groups to enable the study of this material with different crosslink densities. This constituent is synthesized using commercially available starting materials and relatively simple and uncomplicated chemistries which open the possibility for its use in large-scale applications. The 10%, 25%, 50%, and 100% DA nominal crosslinking based on available pendant furan groups on the polymeric component is investigated. The reaction kinetics are monitored using infrared spectroscopy and rheology. Based on the rheological results, carbon nanotube (CNT) incorporation into the DA matrix is explored in order to determine its effects on the complex modulus of the material. This work done in this report is meant as a proof of concept for this DA material with the possibility of its incorporation into other commonly used bulk materials and/or adhesives to allow for an easily reversible product formulation.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Visualization of Hemispherical Post‐Detonation Fireball Internal Structures

Hemispherical charges are initiated above a transparent plate in a half‐plane configuration, allowing optical access to the internal regions of the luminous fireball. High‐speed visualization enables characterization of the internal luminous structure, showing clearly the bright shell and dark core regions. Spectroscopic and pyrometric diagnostics are applied to these flows, generating quantitative information on the spatial distribution of temperature inside the fireball. Both cased and uncased charges can be examined using this methodology, and several different high explosives are tested. This approach can be useful in validation of detailed explosive fireball models. Initial comparisons with such models are presented.

detonation↗
DOE OSTI2017

Target highlights from the first post-PSI CASP experiment (CASP12, May–August 2016)

In this paper, the functional and biological significance of the selected CASP12 targets are described by the authors of the structures. Finally, the crystallographers discuss the most interesting structural features of the target proteins and assess whether these features were correctly reproduced in the predictions submitted to the CASP12 experiment.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Computational Nuclear Physics and Post Hartree-Fock Methods

We present a computational approach to infinite nuclear matter employing Hartree-Fock theory, many-body perturbation theory and coupled cluster theory. These lectures are closely linked with those of chapters 9, 10 and 11 and serve as input for the correlation functions employed in Monte Carlo calculations in chapter 9, the in-medium similarity renormalization group theory of dense fermionic systems of chapter 10 and the Green's function approach in chapter 11. We provide extensive code examples and benchmark calculations, allowing thereby an eventual reader to start writing her/his own codes. We start with an object-oriented serial code and end with discussions on strategies for porting the code to present and planned high-performance computing facilities.

Lietz, Justin↗
DOE OSTI2014

Microbial taxonomy in the post-genomic era: Rebuilding from scratch?

Microbial taxonomy should provide adequate descriptions of bacterial, archaeal, and eukaryotic microbial diversity in ecological, clinical, and industrial environments. We re-evaluated the prokaryote species twice. It is time to revisit polyphasic taxonomy, its principles, and its practice, including its underlying pragmatic species concept. We will be able to realize an old dream of our predecessor taxonomists and build a genomic-based microbial taxonomy, using standardized and automated curation of high-quality complete genome sequences as the new gold standard.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Type 2 Endoleaks Post-EVAR: Current Evidence for Rupture Risk, Intervention and Outcomes of Treatment

Type 2 endoleaks (EL2) are the most commonly encountered endoleaks following EVAR. Despite two decades of experience, there remains considerable variation in the management of EL2 with controversies ranging from if to treat, when to treat and how to treat. Here, we summarise the available evidence, describe the treatment techniques available and offer guidelines for management.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Embolisation of a Proximal Type I Endoleak Post-Nellix Aortic Aneurysm Repair Complicated by Reflux of Onyx into the Nellix Endograft Limb

We report the first case of intervention for a proximal type 1 endoleak following Nellix endovascular aneurysm sealing repair of an aortic aneurysm. This was complicated by migration of Onyx into one of the Nellix graft limbs causing significant stenosis. Subsequent placement of a covered stent to affix the Onyx between the stent and the wall of the Nellix endograft successfully restored stent patency.

62 RADIOLOGY AND NUCLEAR MEDICINE↗