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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

International Coordination and Cooperation on LunaNet Spectrum

LunaNet is planned to be the network of networks operated by a set of cooperating organizations to provide interoperable Communications, networking, Position, Navigation, and Timing (CPNT) services to users on and around the Moon based on a framework of mutually agreed-upon standards, protocols, frequency bands and interface requirements. LunaNet follows a service-oriented architecture that is agnostic about the types of organizations that provide services, e.g., government, industry, or academia. LunaNet is open, scalable, resilient, secure, and extensible. To achieve these goals, LunaNet Service Providers (LNSP) must coordinate with each other to define and develop the architecture, to plan initial and evolved capabilities, and to operate their networks. One of the central LunaNet tenets is the use of shared spectrum. For example, the Lunar Augmented Navigation Service (LANS) acts like a Global Navigation Satellite System (GNSS) such as the US Global Positioning System (GPS) or European Galileo but the LNSPs’ contributions to LunaNet must use the same frequency band (2483.5 MHz-2500.0 MHz) and transmit the same waveform synchronized by highly accurate clocks so that Users ‘see’ one virtual network and use the same multilateration algorithm to determine their positions. This necessitates a high degree of spectrum coordination. NASA’s Lunar and Human Spaceflight Spectrum Management Team has been actively supporting development of the LunaNet Interoperability Specification (LNIS), soliciting inputs from spectrum policy and planning experts across NASA, ESA and JAXA. Cislunar spectrum use considerations have been studied and adjudicated within the Space Frequency Coordination Group (SFCG) and inform the ongoing discussion of a lunar communication and navigation architecture within the existing radio regulatory framework of the International Telecommunication Union, leading to the 2027 World Radiocommunication Conference (WRC-27). The frequency plan contained in the publicly released draft of the LunaNet Interoperability Specification reflects the initial phase of exploration (roughly to 2030) defining an optimal set of radio frequencies in appropriately allocated services consistent with WRC-23 decisions for use by known or planned CPNT applications, while striving to maximize coexistence and compatibility amongst cislunar systems and other systems within the near-Earth regime (< 2 million km from Earth). Important considerations include: protection of extremely sensitive receive-only radio astronomy systems on the lunar far side, known as the Shielded Zone of the Moon (SZM); compatibility between Direct with Earth (DWE) communications links and links needed to support relay satellites in lunar orbit with their customer systems on orbit or on the lunar surface; compatibility between multiple lunar surface communications systems and capabilities over varied and challenging terrain and distances; as well as ensuring compatibility and interoperability between navigation systems which either leverage Earth-based or in-situ lunar systems. In addition, the lunar CPNT architecture is envisioned to be the basis – with adjustments – of the future Mars CPNT architecture as we expand into the solar system using Interplanetary Networking (IPN). The second phase of lunar spectrum definition will address planned international capabilities for the next decade that will require action at WRC-27 and beyond. This paper will discuss each of these considerations in more depth and how the current LunaNet frequency plan addresses them.

LunaNet↗
DOE OSTI2016

Science in 60 – Tabletop Fire Prediction

At the Interagency Fire Center at Los Alamos National Laboratory, experts rely on the state-of-the-art Simtable to help them predict the unpredictable. With algorithms that include camera-based object-tracking and projection developed by the Laboratory, the emergency operations team can simulate a wildland fire spreading across any terrain. The table system, developed and marketed by Simtable, a Santa Fe, N.M., company, takes into account weather, vegetation and fuel conditions. The project also received funding from the LANS Venture Acceleration Fund to improve the user interface.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Radiation Simulation using Wi-Fi Signal Strength and Frequency

For routine radiological operations, lost radioactive sources, decommissioning and cleanup of nuclear facilities, and radiological terrorist events such as Radioactive Dispersive Devices (RDDs) or Radiological Exposure Devices (REDs), individuals are tasked with accurately locating both point and distributed sources of radiation. Radiation workers must often practice these tasks, whether part of initial training or periodically as part of formal or informal exercises or drills. In such circumstances, it is desirable to have an accurate recreation of a radioactive source, including a method of detecting it, which does not include dangerous amounts of radiation. The goal of this research was to develop a radiation simulation technology that uses IEEE 802.11x W-LAN protocol, i.e. Wi-Fi sources and detectors for these, as an inexpensive, precise and accurate method of replicating sources of gamma radiation. For this work, existing 802.11x sources were used. Software was developed for use with an Android smartphone to detect the presence of these sources. The measurements followed the expected behavior as a function of distance from the sources, mimicking that of gamma radiation, thus demonstrating the fundamental principle of operation. The ultimate system will be used in an outreach program to interest students in the radiation protection field.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2017

Dexterity and Worker Comfort in an Ergonomically Designed Glovebox Glove

Gloveboxes are prolifically used in nuclear facilities as the primary means of separation between the hazardous material and operators. Due to extended duration and high repetition of hand tasks in glovebox gloves, improperly fitting gloves can be uncomfortable and increase injury risks. Poor fit can increase time necessary to perform work tasks and stress the glove itself. The Plutonium Facility has the largest inventory of glovebox gloves at Los Alamos National Laboratory (LANL) with approximately 6000 gloves installed. The current glove mold dates back to the 1960's and is not based on the true anatomy of the hand. Design flaws (poor anatomical fit and biomechanics) are directly related to injuries of the elbow (lateral epicondylitis) and thumb (DeQuervain's tenosynovitis) injuries. The current design also contributes to 30% of unplanned glove openings. A new glovebox glove was developed and manufactured, incorporating over forty dimensions to produce the most comprehensive ergonomically sound design. The new design received a LANL patent (patent attorney docket No: LANS 36USD1 'Protective Glove'), one of 20 highest patents awarded by the Richard P. Feynman Center for Innovation. A SolidWorks model was given to the manufacturer for production of the glove mold.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2015

Experimental study of the proposed super-thermal-conductor: BAs

Recent calculations predict a super-thermal-conductivity of ~2000 Wm -1 K -1 , comparable to that of diamond, in cubic boron arsenide (BAs) crystals, which may offer inexpensive insulators with super-thermal-conductivity for microelectronic device applications. We have synthesized and characterized here single crystals of BAs with a zinc blende cubic structure and lattice parameters of a = 4.7830(7) Å. A relatively high thermal conductivity of ~200 Wm -1 K -1 is obtained, close to those of best non-carbon crystal insulators, such as SiC, although still an order of magnitude smaller than the value predicted. Based on our XPS, X-ray single crystal diffraction, and Raman scattering results, steps to achieve the predicted super-thermal conductivity in BAs are proposed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Direct Optical Patterning of Quantum Dot Light-Emitting Diodes via In Situ Ligand Exchange

Precise patterning of quantum dot (QD) layers is an important prerequisite for fabricating QD light-emitting diode (QLED) displays and other optoelectronic devices. However, conventional patterning methods cannot simultaneously meet the stringent requirements of resolution, throughput, and uniformity of the pattern profile while maintaining a high photoluminescence quantum yield (PLQY) of the patterned QD layers. Here, a specially designed nanocrystal ink is introduced, "photopatternable emissive nanocrystals" (PENs), which satisfies these requirements. Photoacid generators in the PEN inks allow photoresist-free, high-resolution optical patterning of QDs through photochemical reactions and in situ ligand exchange in QD films. Various fluorescence and electroluminescence patterns with a feature size down to approximate to 1.5 mu m are demonstrated using red, green, and blue PEN inks. The patterned QD films maintain approximate to 75% of original PLQY and the electroluminescence characteristics of the patterned QLEDs are comparable to thopse of non-patterned control devices. The patterning mechanism is elucidated by in-depth investigation of the photochemical transformations of the photoacid generators and changes in the optical properties of the QDs at each patterning step. This advanced patterning method provides a new way for additive manufacturing of integrated optoelectronic devices using colloidal QDs.

Cho, Himchan↗
DOE OSTI2016

High-Performance Polymer Solar Cells Based on a Wide-Bandgap Polymer Containing Pyrrolo[3,4- f ]benzotriazole-5,7-dione with a Power Conversion Efficiency of 8.63%

A novel donor–acceptor type conjugated polymer based on a building block of 4,8-di(thien-2-yl)-6-octyl-2-octyl-5H-pyrrolo[3,4-f]benzotriazole-5,7(6H)-dione (TZBI) as the acceptor unit and 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)­benzo­[1,2-b:4,5-b']dithiophene as the donor unit, named as PTZBIBDT, is developed and used as an electron-donating material in bulk-heterojunction polymer solar cells. The resulting copolymer exhibits a wide bandgap of 1.81 eV along with relatively deep highest occupied molecular orbital energy level of -5.34 eV. Based on the optimized processing conditions, including thermal annealing, and the use of a water/alcohol cathode interlayer, the single-junction polymer solar cell based on PTZBIBDT:PC71BM ([6,6]-phenyl-C71-butyric acid methyl ester) blend film affords a power conversion efficiency of 8.63% with an open-circuit voltage of 0.87 V, a short circuit current of 13.50 mA cm -2 , and a fill factor of 73.95%, which is among the highest values reported for wide-bandgap polymers-based single-junction organic solar cells. The morphology studies on the PTZBIBDT:PC71BM blend film indicate that a fibrillar network can be formed and the extent of phase separation can be mani­pulated by thermal annealing. These results indicate that the TZBI unit is a very promising building block for the synthesis of wide-bandgap polymers for high-performance single-junction and tandem (or multijunction) organic solar cells.

Lan, Liuyuan↗
DOE OSTI2014

Enhanced Thermal Stability of W-Ni-Al 2 O 3 Cermet-Based Spectrally Selective Solar Absorbers with Tungsten Infrared Reflectors

Solar thermal technologies such as solar hot water and concentrated solar power trough systems rely on spectrally selective solar absorbers. These solar absorbers are designed to efficiently absorb the sunlight while suppressing re-emission of infrared radiation at elevated temperatures. Efforts for the development of such solar absorbers must not only be devoted to their spectral selectivity but also to their thermal stability for high temperature applications. In this work, selective solar absorbers based on two cermet layers are fabricated on mechanically polished stainless steel substrates using a magnetron sputtering technique. The targeted operating temperature is 500–600 °C. A detrimental change in the morphology, phase, and optical properties is observed if the cermet layers are deposited on a stainless steel substrate with a thin nickel adhesion layer, which is due to the diffusion of iron atoms from the stainless steel into the cermet layer forming a FeWO 4 phase. In order to improve thermal stability and reduce the infrared emittance, tungsten is found to be a good candidate for the infrared reflector layer due to its excellent thermal stability and low infrared emittance. Lastly, a stable solar absorptance of ≈0.90 is demonstrated, with a total hemispherical emittance of 0.15 at 500 °C.

14 SOLAR ENERGY↗
DOE OSTI2019

Crystal and solution structures of human oncoprotein Musashi‐2 N‐terminal RNA recognition motif 1

Abstract Musashi‐2 (MSI2) belongs to Musashi family of RNA binding proteins (RBP). Like Musashi‐1 (MSI1), it is overexpressed in a variety of cancers and is a promising therapeutic target. Both MSI proteins contain two N‐terminal RNA recognition motifs and play roles in posttranscriptional regulation of target mRNAs. Previously, we have identified several inhibitors of MSI1, all of which bind to MSI2 as well. In order to design MSI2‐specific inhibitors and compare the differences of binding mode of the inhibitors, we set out to solve the structure of MSI2‐RRM1, the key motif that is responsible for the binding. Here, we report the crystal structure and the first NMR solution structure of MSI2‐RRM1, and compare these to the structures of MSI1‐RBD1 and other RBPs. A high degree of structural similarity was observed between the crystal and solution NMR structures. MSI2‐RRM1 shows a highly similar overall folding topology to MSI1‐RBD1 and other RBPs. The structural information of MSI2‐RRM1 will be helpful for understanding MSI2‐RNA interaction and for guiding rational drug design of MSI2‐specific inhibitors.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Relativistic Effects From Coupled-Cluster Theory

We discuss the theory and computational challenges of the relativistic coupled-cluster methods. Example calculations of heavy-atom-containing molecules are then presented to demonstrate the importance of scalar-relativistic, spin-orbit coupling, and electron-correlation effects on molecular properties as well as the applicability and usefulness of relativistic coupled-cluster methods in calculations aiming at high-accuracy results. Here, a unique applicability of the spinor-based relativistic coupled-cluster methods is also highlighted using the calculations of open shell actinide-containing small molecules. As a result, a summary is given together with an outlook into future developments.

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

HDAC11 deletion reduces fructose-induced cardiac dyslipidemia, apoptosis and inflammation by attenuating oxidative stress injury

Highlights: • HDAC11-knockout improves dyslipidemia in heart of Fru-induced mice. • HDAC11-deficiency reduces apoptosis, oxidative stress and inflammation in heart of mice fed with Fru. • HDAC11-suppression suppresses oxidative stress to reduce apoptosis and inflammation in Fru-treated primary cardiomyocytes. Diabetes mellitus (DM) is a risk factor for abnormal heart development, but the molecular mechanism remains obscure. Histone deacetylase 11 (HDAC11), the most recently identified histone deacetylase, is the sole member of class IV HDACs. However, its role in diabetic cardiac injury is still poorly understood. In the present study, we attempted to explore the effects of HDAC11 on fructose (Fru)-induced cardiac injury using the wild type (HDAC11{sup +/+}) and knockout (HDAC11{sup −/−}) mice. The results indicated that HDAC11 was significantly expressed in human and mouse diabetic heart failure (DHF) hearts. HDAC11{sup −/−} reduced the body weight, inguinal fat-pad mass, and elevated blood pressure in Fru-fed mice. Compared to HDAC11{sup +/+}/Fru group, cardiac function was significantly improved in HDAC11{sup −/−}/Fru mice. HDAC11{sup −/−}/Fru mice exhibited reduced cardiac triacylglycerol (TG), total cholesterol (TC) and free fatty acid (FFA) levels, along with decreased mRNA levels of lipid synthesis-, lipid storage- and lipid oxidation-associated genes. In addition, HDAC11{sup −/−} attenuated apoptosis, oxidative stress and inflammation in the heart of Fru-fed mice, as evidenced by the reduced cleavage of Caspase-3, nicotinamide adenine dinucleotide phosphate (NADPH), and xanthine oxidase (XOD) activity, enhanced superoxide dismutase (SOD) activity, as well as the decreased interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α) levels, which was accompanied with down-regulated p-NF-κB. The results above were verified in Fru-treated primary cardiomyocytes isolated from HDAC11{sup +/+} or HDAC11{sup −/−} mice. Intriguingly, suppressing the expressions of anti-oxidants using zinc protoporphyrin (ZnPP) or siNrf-2 siRNA markedly abolished the results that HDAC11 suppression-induced reduction of apoptosis, reactive oxygen species (ROS) production, inflammation, as well as the improvement of dyslipidemia in Fru-incubated primary cardiomyocytes. Thus, ROS production was responsible for HDAC11-modulated diabetic heart injury. These findings suggested that suppressing HDAC11 has therapeutic potential for treating diabetes mellitus-associated cardiac injury.

60 APPLIED LIFE SCIENCES↗