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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Chemically Functionalized Plant Fibers and Carbon Nanotubes for High Compatibility and Reinforcement in Polylactic Acid (PLA) Composite

In this study, surface modification is used to improve the compatibility of Kenaf fibers (KFs) and multi-walled carbon nanotubes (MWCNTs) in a polylactic acid (PLA) matrix, as well as to enhance the mechanical properties. Through the use of a silane coupling agent, the KF is grafted with functional groups to generate a chemical bond with the PLA; the modified KF shows high compatibility in the PLA matrix. Compared to the bare PLA, the optimal KF/MWCNT/PLA composite (PC1F30-OX) shows increases of 58% in tensile strength, and 113% in impact strength. A small addition of MWCNTs (1 wt%) dramatically improves the antistatic ability by lowering the surface resistance to 3.47 GΩ. With the addition of hydrophilic KF into the PLA, the composite becomes much more environmentally friendly, and the biodegradation rate can be controlled by the amount of KF added. The addition of hydrophilic KF allowed the composite to accommodate more enzyme to hasten the biodegradation; almost complete decomposition occurred after 11 weeks.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2019

Bio-compatible and highly sensitive two-dimensional plasmonic sensor

We propose a novel bio-compatible two dimensional plasmonic sensor with array of ring and the hole structure on an optically thick gold film for biochemical sensing. We use finite-difference time-domain simulation for design and calculation of sensitivity in the near-infrared region. The bio-compatible and cheap plasmonic glycerol sensor with high sensitivity by interferometer style as a motif in the sensor’s structure. The proposed sensor can be applied as highly sensitivity sensor with a good linear response under different glycerol concentrations.

42 ENGINEERING↗
DOE OSTI2026

Enhancing mobility and interface state engineering via UV-ozone treatment in BEOL-compatible ultrathin TiO 2 transistors

It has emerged as a potential candidate to improve the performance of monolithic-three-dimensional (M3D) integration of fused logic and memories through low-temperature in situ synthesis of high-performance metal–oxide–semiconductor (MOS) transistors. Here, we report the demonstration of the BEOL-compatible low thermal budget (350 °C) fabrication process of ultrathin-TiO2 transistors by the combination of RTA and UV-ozone treatment (RTA-UVOz). UV–ozone (UVOz) treatment of TiO2 anatase films significantly enhances stability, boosting ION current and field effect mobility (μ FE ) by two times of magnitude in TiO2 TFTs. UV ozone treatment helps to eliminate pre-existing oxygen vacancies and carbon contamination on TiO2 channels even at low temperature (100 °C), resulting in high-quality channel/dielectric interfaces with low interface states (D it ). During UVOz treatment, oxygen species (O x ) passivate the oxygen vacancies ($V$$^{2+}_{o}$), and hence low concentration of $V$$^{2+}_{o}$ would be left for ionization/de-ionization under PBS/NBS, leading to improved bias stress stability. Furthermore, the TiO 2 TFTs with thin ZrO 2 gate dielectric exhibited excellent performance including a lower subthreshold swing (SS) of 98 mV/dec with high drive I ON current ∼ 4.5 μA/μm, a high I ON /I OFF > 10 9 , and mobility μFE of 7 cm 2 /V-s under a battery powered voltage of 1 V. UV–ozone treatment enables high-performance, CMOS-compatible TiO 2 transistors with a low thermal budget, ideal for next-generation flexible, energy-efficient electronics.

BEOL↗
DOE OSTI2021

Hydrogen-enhanced compatibility constraint for intergranular failure in FCC FeNiCoCrMn high-entropy alloy

The fundamental mechanism of hydrogen embrittlement was investigated in the high-entropy alloy FeNiCoCrMn using slow strain rate tensile tests with and without internal hydrogen. Hydrogen induced intergranular failure and reduced the average grain elongation parallel to the tensile axis, but also increased the local plasticity within grains. Here, the influence of hydrogen on plasticity establishes a compatibility constraint across grain boundaries, which results in failure along the hydrogen-weakened grain boundaries. This study is the first to directly confirm the presence of the hydrogen-enhanced compatibility constraint in a high-entropy alloy and highlights the importance of developing a physical understanding of grain-scale interactions.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Keras2c: A library for converting Keras neural networks to real-time compatible C

With the growth of machine learning models and neural networks in measurement and control systems comes the need to deploy these models in a way that is compatible with existing systems. Existing options for deploying neural networks either introduce very high latency, require expensive and time consuming work to integrate into existing code bases, or only support a very limited subset of model types. We have therefore developed a new method called Keras2c, which is a simple library for converting Keras/TensorFlow neural network models into real-time compatible C code. It supports a wide range of Keras layers and model types including multidimensional convolutions, recurrent layers, multi-input/output models, and shared layers. Keras2c re-implements the core components of Keras/TensorFlow required for predictive forward passes through neural networks in pure C, relying only on standard library functions considered safe for real-time use. The core functionality consists of ~ 1500 lines of code, making it lightweight and easy to integrate into existing codebases. Keras2c has been successfully tested in experiments and is currently in use on the plasma control system at the DIII-D National Fusion Facility at General Atomics in San Diego.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

H-Mat Hydrogen Compatibility of Polymers and Elastomers

The H2@Scale program of the U.S. Department of Energy (DOE) Fuel Cell Technologies Office is supporting work on the hydrogen compatibility of polymers to improve the durability and reliability of materials for hydrogen infrastructure. The hydrogen compatibility program (H-Mat) seeks “to address the challenges of hydrogen degradation by elucidating the mechanisms of hydrogen-materials interactions with the goal of providing science-based strategies to design materials, (micro)structures, and morphology with improved resistance to hydrogen degradation.” This research has observed interactions of hydrogen and pressure with model rubber-material compounds resulting in volume change and compression-set differences in the materials. The materials were investigated using helium-ion microscopy (HeIM), which revealed significant morphological changes in the plasticizer-incorporating compounds after exposure, as evidenced by time-of-flight secondary ion mass spectrometry. Additional studies using transmission electron microscopy and nuclear magnetic resonance were performed to correlate morphological change to potential chemical change in the materials.

08 HYDROGEN↗
DOE OSTI2020

Three-Dimensional Mass Spectrometric Imaging of Biological Structures Using a Vacuum-Compatible Microfluidic Device

Three-dimensional (3D) molecular imaging of biological structures is important for a wide range of research. In recent decades, secondary ion mass spectrometry (SIMS) has been recognized as a powerful technique for both two-dimensional (2D) and 3D molecular imaging. Sample fixations (e. g., chemical fixation and cryogenic fixation methods) are necessary to adapt biological samples to the vacuum condition in the SIMS chamber, which has been demonstrated to be non-trivial and less controllable, thus limiting the wider application of SIMS on 3D molecular analysis of biological samples. Our group recently developed in situ liquid SIMS that offers great opportunities for the molecular study of various liquids and liquid interfaces. In this work, we demonstrate that a further development of the vacuum-compatible microfluidic device used in in situ liquid SIMS provides a convenient freeze-fixation of biological samples and leads to more controllable and convenient 3D molecular imaging. The special design of this new vacuum-compatible liquid chamber allows an easy determination of sputter rates of ice, which is critical for calibrating the depth scale of frozen biological samples. Sputter yield of a 20 keV Ar 1800 + ion on ice has been determined as 1500 (± 8%) water molecules per Ar 1800 + ion, consistent with our results from molecular dynamics simulations. Moreover, using the information of ice sputter yield, we successfully conduct 3D molecular imaging of frozen homogenized milk and observe network structures of interesting organic and inorganic species. Finally, taken together, our results will significantly benefit various research fields relying on 3D molecular imaging of biological structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Stability, Combustion, and Compatibility of High-Viscosity Heavy Fuel Oil Blends with a Fast Pyrolysis Bio-Oil

Properties related to the combustion, stability, and compatibility of blends composed of high-viscosity heavy fuel oil (HFO) and highly acidic pyrolysis bio-oil were determined to assess the utility of bio-oil as a marine fuel. The addition of bio-oil was shown to be fully stable with HFO at blend levels up to 50 mass % for up to 2 weeks. Bio-oil concentrations as low as 5 mass % significantly reduced the viscosity of HFO at 25 and 50 °C. Aging studies at 50 and 90 °C showed that the HFO inhibited the polymerization of bio-oil. The heating value and lubricity showed a linear dependency with bio-oil content, and combustion quality was acceptable for blends containing up to 15% bio-oil. The highly acidic bio-oil was found to be corrosive to carbon steel, 2.25Cr-1Mo steel, and 409 stainless steels, but not 304L and 316L. When blended into HFO at levels less than 19 mass %, no measurable corrosion was observed on any of the steel materials, but a 50 mass % concentration produced low-to-moderate corrosion in the carbon steel, 2.25Cr-1Mo steel, and 409 stainless steel grades. The combination of good blend stability, polymerization inhibition, reduced viscosity, and acceptable compatibility for low blend levels suggests that bio-oils may be suitable for use as a marine fuel.

09 BIOMASS FUELS↗
DOE OSTI2026

Direct Air Capture-Compatible Azolate and Amino Acid Ionic Liquids for Electrochemical CO 2 Reduction to CO on a Silver Cathode

Direct air capture (DAC) compatible ionic liquids (ILs) are attractive for integrating CO 2 capture and conversion due to their high CO 2 solubility at low partial pressures, tunable chemisorption mechanisms, low volatility, and wide electrochemical windows. However, very few ILs have high CO 2 uptake at DAC conditions (420 ppm CO 2 ), and even fewer have been evaluated for chemical compatibility and mechanistic continuity for combined capture and electrochemical CO 2 reduction (eCO 2 RR). We demonstrate that two representative DAC-capable ILs, [P 4444 ][Val] (amino acid-based) and [P 66614 ][5-Me-Imd] (azolate-based), exhibit favorable electrochemical reduction behavior. CO and H 2 were the dominant gas-phase products by GC, while 1 H and 13 C NMR confirmed negligible liquid-phase HCOOH. Chronoamperometry at moderate applied potentials (−2.0 to −2.5 V vs Ag/AgCl) in a two-compartment H-cell with a Ag coated carbon paper as the working electrode yielded steady-state current densities of ∼10 mA cm −2 with CO FE of 96% for [P 4444 ][Val] and 95% for [P 66614 ][5-Me-Imd], highlighting the role of viscosity and chemically absorbed CO 2 -IL species to provide highly selective CO formation while suppressing H 2 evolution.

amino acid ionic liquid↗
DOE OSTI2025

Investigating Fast Scanning Calorimetry and Differential Scanning Calorimetry as Screening Tools for Thermoset Polymer Material Compatibility with Laser-Based Powder Bed Fusion

As additive manufacturing (AM) technology has developed and progressed, a constant topic of research in the area is expanding the library of materials to be used with these techniques. Among AM methods that utilize polymers, laser-based powder bed fusion (PBF-LB) has preferentially used thermoplastic polymers as its starting materials, but the deposition and material joining method employed in PBF-LB may also be compatible with powdered thermoset polymer precursors as feedstocks. To assess the compatibility of candidate thermosetting polymers and PBF-LB, characterization techniques and protocols that link fundamental material behavior to material behavior in the processing environment are needed. Therefore, the objectives of this work are to compare the curing behavior measured with two different calorimetry techniques that can operate in different heating rate regimes, differential scanning calorimetry (DSC) and fast scanning calorimetry (FSC), and to assess the capabilities of these techniques to act as materials screening tools for PBF-LB. A commercial polyester powder coating is used as a model material to evaluate the potential of obtaining complimentary information for material screening through a combination of calorimetry methods, and its non-isothermal curing behavior is measured at heating rates between 5 °C/min and 7500 °C/min. Curing exotherms are observed with both calorimetry techniques, and comparing the enthalpy associated with curing shows that incomplete curing occurs at higher heating rates, with relative conversion values of approximately 30%. The curing data are fit with two isoconversional models, Friedman and Starink, which show a reduced activation energy at higher heating rates as well, signifying a lower barrier to curing at the conditions used in the FSC experiments. Overall, the results of this work indicate that using these two calorimetry techniques as tiered screening tools can provide valuable information about how curing may proceed in PBF-LB and inform materials selection and design activities for additive manufacturing.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Nanoalloy Printed and Pulse-Laser Sintered Flexible Sensor Devices with Enhanced Stability and Materials Compatibility

While conformal and wearable devices have become one of the most desired formats for printable electronics, it is challenging to establish a scalable process that produces stable conductive patterns but also uses substrates compatible with widely available wearable materials. Here, we describe findings of an investigation of a nanoalloy ink printed and pulsed laser sintered conductive patterns as flexible functional devices with enhanced stability and materials compatibility. While nanoparticle inks are desired for printable electronics, almost all existing nanoparticle inks are based on single-metal component, which, as an electronic element, is limited by its inherent stabilities of the metal such as propensity of metal oxidation and mobility of metal ions, especially in sintering processes. The work here has demonstrated the first example in exploiting plasmonic coupling of nanoalloys and pulsed-laser energy with controllable thermal penetration. The experimental and theoretical results have revealed clear correlation between the pulsed laser parameters and the nanoalloy structural characteristics. The superior performance of the resulting flexible sensor device, upon imparting nanostructured sensing materials, for detecting volatile organic compounds has significant implications to developing stable and wearable sensors for monitoring environmental pollutants and breath biomarkers. This simple “nanoalloy printing 'laser sintering' nanostructure printing” process is entirely general to many different sensor devices and nanostructured sensing materials, enabling the ability to easily construct sophisticated sensor array.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2016

Augmenting drug–carrier compatibility improves tumour nanotherapy efficacy

A major goal of cancer nanotherapy is to use nanoparticles as carriers for targeted delivery of anti-tumour agents. The drug–carrier association after intravenous administration is essential for efficient drug delivery to the tumour. However, a large number of currently available nanocarriers are self-assembled nanoparticles whose drug-loading stability is critically affected by the in vivo environment. Here we used in vivo FRET imaging to systematically investigate how drug–carrier compatibility affects drug release in a tumour mouse model. We found the drug’s hydrophobicity and miscibility with the nanoparticles are two independent key parameters that determine its accumulation in the tumour. Next, we applied these findings to improve chemotherapeutic delivery by augmenting the parent drug’s compatibility; as a result, we achieved better antitumour efficacy. Lastly, our results help elucidate nanomedicines’ in vivo fate and provide guidelines for efficient drug delivery.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Foundry-compatible high-resolution patterning of vertically phase-separated semiconducting films for ultraflexible organic electronics

Solution processability of polymer semiconductors becomes an unfavorable factor during the fabrication of pixelated films since the underlying layer is vulnerable to subsequent solvent exposure. A foundry-compatible patterning process must meet requirements including high-throughput and high-resolution patternability, broad generality, ambient processability, environmentally benign solvents, and, minimal device performance degradation. However, known methodologies can only meet very few of these requirements. Here, a facile photolithographic approach is demonstrated for foundry-compatible high-resolution patterning of known p- and n-type semiconducting polymers. This process involves crosslinking a vertically phase-separated blend of the semiconducting polymer and a UV photocurable additive, and enables ambient processable photopatterning at resolutions as high as 0.5 μm in only three steps with environmentally benign solvents. The patterned semiconducting films can be integrated into thin-film transistors having excellent transport characteristics, low off-currents, and high thermal (up to 175 °C) and chemical (24 h immersion in chloroform) stability. Moreover, these patterned organic structures can also be integrated on 1.5 μm-thick parylene substrates to yield highly flexible (1 mm radius) and mechanically robust (5,000 bending cycles) thin-film transistors.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Compatibility of ethylene vinyl acetate (EVA)/ethylene vinyl alcohol (EVOH)/EVA films with gamma, electron-beam, and X-ray irradiation

Many polymer-based medical devices are sterilized by gamma irradiation. To reduce the use of cobalt-60 gamma-ray sources, transition from gamma ray to alternative irradiation technologies was proposed, namely electron beam (e-beam) and X-ray. A major impediment for such a transition is the knowledge gap in material compatibility with the different radiation sources. In this study, multi-layer films consisting of ethylene vinyl acetate (EVA) and ethylene vinyl alcohol (EVOH) components were irradiated to target doses of 30, 45, and 60 kGy by gamma-ray, e-beam, and X-ray sources. Effects of irradiation were evaluated on 12 material properties, and statistical comparisons between gamma irradiation and alternative technologies were conducted using the two one-sided t-test (or “equivalence test”) and classic t-test. Melting temperature and UV absorbance below 300 nm showed dose dependencies, while other investigated properties such as discoloration and mechanical durability did not change with dose up to 60 kGy. Based on these results, there is no material compatibility issue associated with the transition from gamma to e-beam or to X-ray as source of sterilization radiation of the studied multi-layer film.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Investigating dry room compatibility of sulfide solid-state electrolytes for scalable manufacturing

All-solid-state batteries (ASSBs) are viewed as promising next-generation energy storage devices, due to their enhanced safety by replacing organic liquid electrolytes with non-flammable solid-state electrolytes (SSEs). The high ionic conductivity and low Young's modulus of sulfide SSEs make them suitable candidates for commercial ASSBs. Nevertheless, sulfide SSEs are generally reported to be unstable in ambient air. Moreover, instead of gloveboxes used for laboratory scale studies, large scale production of batteries is usually conducted in dry rooms. Thus, this study aims to elucidate the chemical evolution of a sulfide electrolyte, Li 6 PS 5 Cl (LPSCl), during air exposure and to evaluate its dry room compatibility. When LPSCl is exposed to ambient air, hydrolysis, hydration, and carbonate formation can occur. Moreover, hydrolysis can lead to irreversible sulfur loss and therefore LPSCl cannot be fully recovered in the subsequent heat treatment. During heat treatment, exposed LPSCl undergoes dehydration, decomposition of carbonate species, and reformation of the LPSCl phase. Lastly, LPSCl was found to exhibit good stability in a dry room environment and was subject to only minor conductivity loss due to carbonate formation. The dry room exposed LPSCl sample was tested in a LiNi 0.8 Co 0.1 Mn 0.1 O 2 |LiIn half-cell, exhibiting no significant loss of electrochemical performance compared with the pristine LPSCl, proving it to be compatible with dry room manufacturing processes.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Design and realization of one-dimensional double hetero-structure photonic crystals for infrared-radar stealth-compatible materials applications

In this paper, a new type one-dimensional (1D) double hetero-structure composite photonic crystal (CPC) for infrared-radar stealth-compatible materials applications was proposed and studied numerically and experimentally. First, based on transfer matrix method of thin-film optical theory, the propagation characteristics of the proposed structure comprising a stack of different alternating micrometer-thick layers of germanium and zinc sulfide were investigated numerically. Calculation results exhibit that this 1D single hetero-structure PC could achieve a flat high reflectivity gradually with increasing the number of the alternating media layers in a single broadband range. Then, based on principles of distributed Bragg reflector micro-cavity, a 1D double hetero-structure CPC comprising four PCs with thickness of 0.797 μm, 0.592 μm, 1.480 μm, and 2.114 μm, respectively, was proposed. Calculation results exhibit that this CPC could achieve a high reflectance of greater than 0.99 in the wavelength ranges of 3–5 μm and 8–14 μm and agreed well with experiment. Further experiments exhibit that the infrared emissivity of the proposed CPC is as low as 0.073 and 0.042 in the wavelength ranges of 3–5 μm and 8–12 μm, respectively. In addition, the proposed CPC can be used to construct infrared-radar stealth-compatible materials due to its high transmittance in radar wave band.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Bias-free terahertz generation from a silicon-compatible photoconductive emitter operating at telecommunication wavelengths

Here, we present a telecommunication-compatible bias-free photoconductive terahertz emitter composed of a bilayer InAs structure directly grown on a high-resistivity silicon substrate. The bilayer InAs structure includes p + -doped and undoped InAs layers, inducing a strong built-in electric field that enables terahertz generation without requiring any external bias voltage. A large-area plasmonic nanoantenna array is used to enhance and confine optical generation inside the photoconductive region with the highest built-in electric field, leading to the generation of a strong ultrafast photocurrent and broadband terahertz radiation. Thanks to a higher terahertz transmission through the silicon substrate and a shorter carrier lifetime in the InAs layers grown on silicon, higher signal-to-noise ratios are achieved at high terahertz frequencies compared with previously demonstrated bias-free terahertz emitters realized on GaAs. In addition to compatibility with silicon integrated optoelectronic platforms, the presented bias-free photoconductive emitter provides more than a 6 THz radiation bandwidth with more than 100 dB dynamic range when used in a terahertz time-domain spectroscopy system.

42 ENGINEERING↗
DOE OSTI2018

A Weighted Least-Squares Transport Equation Compatible with Source Iteration and Voids

We present that second-order forms of the transport equation allow the use of continuous finite elements (CFEMs). This can be desired in multiphysics calculations where other physics require CFEM discretizations. Second-order transport operators are generally self-adjoint, yielding symmetric positive-definite (SPD) matrices, which allow the use of efficient linear algebra solvers with an enormous advantage in memory usage. Least-squares (LS) forms of the transport equation can circumvent the void problems of other second-order forms but are almost always nonconservative. Additionally, the standard LS form is not compatible with discrete ordinates method (SN) iterative solution techniques such as source iteration. A new form of the LS transport equation has recently been developed that is compatible with voids and standard SN iterative solution techniques. Performing nonlinear diffusion acceleration (NDA) using an independently differenced low-order equation enforces conservation for the whole system and makes this equation suitable for reactor physics calculations. In this context, “independent” means that both the transport and low-order solutions converge to the same scalar flux and current as the spatial mesh is refined, but for a given mesh, the solutions are not necessarily equal. In this paper we show that introducing a weight function into this LS equation improves issues with causality and can render our equation equal to the self-adjoint angular flux (SAAF) equation. Causality is a principle of the transport equation that states that information travels only downstream along characteristics. This principle can be violated numerically. We show how to limit the weight function in voids and demonstrate the effect of this limit on accuracy. Using the C5G7 benchmark, we compare our method to the SAAF formulation with a void treatment (SAAFτ) that is not self-adjoint and has a nonsymmetric coefficient matrix. Finallyl, we show that the weighted LS equation with NDA gives acceptable accuracy relative to the SAAFτ equation while maintaining a SPD system matrix.

97 MATHEMATICS AND COMPUTING↗