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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Resonant ultrasound spectroscopy for materials with high damping and samples of arbitrary geometry

This paper describes resonant ultrasound spectroscopy (RUS) as a powerful and established technique for measuring elastic constants of a material with general anisotropy. The first step of this technique consists of extracting resonance frequencies and damping from the vibrational frequency spectrum measured on a sample with free boundary conditions. An inversion technique is then used to retrieve the elastic tensor from the measured resonance frequencies. As originally developed, RUS has been mostly applicable to (i) materials with small damping such that the resonances of the sample are well separated and (ii) samples with simple geometries for which analytical solutions exist. In this paper, these limitations are addressed with a new RUS approach adapted to materials with high damping and samples of arbitrary geometry. Resonances are extracted by fitting a sum of exponentially damped sinusoids to the measured frequency spectrum. The inversion of the elastic tensor is achieved with a genetic algorithm, which allows searching for a global minimum within a discrete and relatively wide solution space. First, the accuracy of the proposed approach is evaluated against numerical data simulated for samples with isotropic symmetry and transversely isotropic symmetry. Subsequently, the applicability of the approach is demonstrated using experimental data collected on a composite structure consisting of a cylindrical sample of Berea sandstone glued to a large piezoelectric disk. In the proposed experiments, RUS is further enhanced by the use of a 3-D laser vibrometer allowing the visualization of most of the modes in the frequency band studied.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Profiling of adrenocorticotropic hormone and arginine vasopressin in human pituitary gland and tumor thin tissue sections using droplet-based liquid-microjunction surface-sampling-HPLC–ESI-MS–MS

Described here are the results from the profiling of the proteins arginine vasopressin (AVP) and adrenocorticotropic hormone (ACTH) from normal human pituitary gland and pituitary adenoma tissue sections using a fully automated droplet-based liquid microjunction surface sampling-HPLC-ESI-MS/MS system for spatially resolved sampling, HPLC separation, and mass spectral detection. Excellent correlation was found between the protein distribution data obtained with this droplet-based liquid microjunction surface sampling-HPLC-ESI-MS/MS system and those data obtained with matrix assisted laser desorption ionization (MALDI) chemical imaging analyses of serial sections of the same tissue. The protein distributions correlated with the visible anatomic pattern of the pituitary gland. AVP was most abundant in the posterior pituitary gland region (neurohypophysis) and ATCH was dominant in the anterior pituitary gland region (adenohypophysis). The relative amounts of AVP and ACTH sampled from a series of ACTH secreting and non-secreting pituitary adenomas correlated with histopathological evaluation. ACTH was readily detected at significantly higher levels in regions of ACTH secreting adenomas and in normal anterior adenohypophysis compared to non-secreting adenoma and neurohypophysis. AVP was mostly detected in normal neurohypophysis as anticipated. This work demonstrates that a fully automated droplet-based liquid microjunction surface sampling system coupled to HPLC-ESI-MS/MS can be readily used for spatially resolved sampling, separation, detection, and semi-quantitation of physiologically-relevant peptide and protein hormones, such as AVP and ACTH, directly from human tissue. In addition, the relative simplicity, rapidity and specificity of the current methodology support the potential of this basic technology with further advancement for assisting surgical decision-making.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

IR Thermographic Analysis of 3D Printed CFRP Reference Samples with Back-Drilled and Embedded Defects

Carbon-fiber composite structures may demonstrate a defective behavior due to manufacturing induced anomalies (delamination, dis-bonds) or service related defectives (impact damage, water ingress). Thus, there is a need for a relatively fast and low cost non-intrusive testing schemes such as infrared thermography (IRT). Still, thermography testing requires calibrated samples and coupons to yield best results. The presented research demonstrates the novel use of 3D printing technology to generate IRT calibration samples. In this text, two carbon fiber reinforced polymer samples are 3D printed; the first mimics a 'back-drilled holes' type coupons, while the other is designed to embed air pockets similar to Teflon inserts. The generated samples are then tested using two IRT modalities; namely pulse thermography and lock-in thermography. Furthermore, the resulted thermograms are processed using a principle component analysis, to help highlight the variance of defectives in a consistent manner among the samples. This research findings offer insights on the variation of detectability between embedded and back-printed samples, which might be due to the inserts thickness.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Rapid method to determine 226Ra in steel samples

The rapid measurement of 226 Ra in steel samples is very important in the event of a radiological emergency. 226 Ra (T 1/2 = 1600 y) is a natural radionuclide present in the environment and a highly toxic alpha-emitter. Due to its long life and tendency to concentrate in bones, 226 Ra ingestion or inhalation can lead to significant committed dose to individuals. A new method for the determination of 226 Ra in steel samples has been developed at the Savannah River Environmental Laboratory. The new method employs a rugged acid digestion method that includes hydrofluoric acid, followed by a single precipitation step to rapidly preconcentrate the radium and remove most of the dissolved steel sample matrix. Radium is then separated using a combination of cation exchange and extraction chromatography, and 226 Ra is measured by alpha spectrometry. This approach has a sample preparation time of ~ 8 h for steel samples, has a very high tracer yield (> 88%), and removes interferences effectively. A 133 Ba yield tracer is used so that samples can be counted immediately following the separation method, avoiding lengthy ingrowth times that are required in other methods.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

The distinct conditions of atmospheric and underground nuclear tests revealed by Zn isotopic compositions of nuclear debris samples

We analyzed the Zn isotopic compositions of nuclear debris samples from atmospheric and underground nuclear tests. Samples from the site of atmospheric tests exhibit a range of Zn isotopic fractionation (δ 66 Zn JMC-Lyon = 0.23–0.86 ‰) while samples from underground tests exhibit Zn isotopic compositions with minimal variation among samples and from terrestrial igneous rock standards (δ 66 ZnJMC-Lyon = 0.28–0.39 ‰). In conclusion, the larger range of δ 66 Zn JMC-Lyon observed in atmospheric test samples relative to underground test samples is likely the result of the open system characteristics of atmospheric nuclear tests and the closed system characteristics of underground nuclear tests.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Design and Evaluation of an Experimental Technique for Mechanical and Fatigue Testing of Sub-Sized Samples

Some recently developed processing techniques allow fabrication of small specimens. The fatigue behavior of these small samples cannot be characterised according to the existing standards due to size limitations. The main objective of the present work is to develop an original technique for both mechanical and fatigue testing of sub-sized specimens produced by a high pressure torsion (HPT) method. The fatigue behavior of the sub-sized Ti-6Al-4 V samples, made from HPT-processed disks, is compared with that of the standard samples prepared according to the ASTM standards. Finite element method (FEM) analysis of the stress distribution under applied static load, for both sub-sized specimens and grips designed for their testing, is performed. Good agreement between the outcomes of tensile testing of the standard ASTM samples and sub-sized samples is observed. Fatigue data, represented by Wöhler curves for both types of samples, showed significant divergence of high cycle fatigue properties caused by incompliance of specimen geometries and surface/defect size ratio. The obtained results can be used to scale up the fatigue behavior from sub-sized specimens to the standard ones, as well as to predict the fatigue behavior of the bulk nanostructured metals and alloys produced by HPT.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Reduced alkali-silica reaction damage in recycled glass mortar samples with supplementary cementitious materials

Recycling waste glass aggregate into concrete can reduce environmental impacts but also may lead to serious alkali silica reaction (ASR) damage. This study aims to characterize ASR damage development in the mortar samples containing reactive glass aggregates and investigate the damage reduction effect of the waste supplementary cementitious materials (SCMs), including recycled glass powders and fly ash. The recycled glass aggregate mortar samples with/without SCMs were prepared in this study. The length change tests were first conducted with the prepared mortar samples based on the ASTM C1260 standard. The results demonstrated the added SCMs can largely decrease early-age ASR expansion rate. The optical microscope and Scanning Electron Microscope (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) were further conducted to characterize the ASR damage in mortar samples and investigate the damage mitigation mechanism with added SCMs. The combined SEM imaging and chemical analysis indicated added SCMs can decrease both the alkali and calcium content of the generated ASR gel. In addition, the ASR damage development inside mortar samples were monitored with dynamic micron X-ray CT (μCT) over a reaction period of 63 hour at the temperature of 80°C. The scanning patterns demonstrated the ASR damage can be easily developed from the area with initial cracks and sharp corners. In conclusion, the images of glass power and fly ash samples showed significantly reduced ASR damage. This study showed that adding of SCMs can largely reduce ASR deterioration and thus facilitate the recycling glass particles into concrete.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

Efficient Bayesian inference with latent Hamiltonian neural networks in No-U-Turn Sampling

When sampling for Bayesian inference, one popular approach in the computational field is to use Hamiltonian Monte Carlo (HMC) and specifically the No-U-Turn Sampler (NUTS), which automatically decides the end time of the Hamiltonian trajectory. However, HMC and NUTS can require numerous numerical gradients of the target density and can prove slow in practice when relying on computationally expensive forward models. We propose Latent Hamiltonian neural networks (L-HNNs) with HMC and NUTS for solving Bayesian inference problems. Once trained, L-HNNs do not require numerical gradients of the target density during sampling, and hence numerous evaluations of the forward computational model. Moreover, L-HNNs satisfy important properties such as perfect time reversibility and Hamiltonian conservation, making them well-suited for use within HMC and NUTS because stationarity can be shown. We also propose the integration of L-HNNs in an online error monitoring scheme, in which numerical gradients of the target density are used for a few samples whenever the L-HNNs prediction errors are large. This online error monitor scheme prevents sample degeneracy in regions of low probability density and ensures robust uncertainty quantification. We demonstrate L-HNNs in NUTS with online error monitoring on several analytical examples involving complex, heavy-tailed, and high-local-curvature probability densities. We then demonstrate the applicability of L-HNNs in NUTS to two computational case studies, namely the Allen-Cahn stochastic partial differential equation and an elliptic partial differential equation with 25 and 50 inference parameters, respectively. Overall, the L-HNNs in NUTS with online error monitoring satisfactorily inferred these probability densities. In conclusion, compared to traditional NUTS, L-HNNs in NUTS with online error monitoring required 1–2 orders of magnitude fewer numerical gradients of the target density and improved the effective sample size (ESS) per gradient (which is a measure of both the sampling quality and the computational expense) by an order of magnitude.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

An organogel library for solution NMR analysis of nanoparticle suspensions in non-aqueous samples

Surface contrast solution NMR methods (scNMR) are emerging as powerful tools to investigate the adsorption of small molecule ligands to the surface of nanoparticles (NP), returning fundamental insight into the kinetics and thermodynamics of sorption, as well as structural information on the adsorbed species. A prerequisite for the acquisition of high quality solution NMR data is the preparation of homogeneous and stable samples that return consistent NMR spectra and allow extensive signal averaging. Unfortunately, this condition does not apply to NMR samples containing NPs that often show a tendency to sediment and accumulate at the bottom of the NMR tube over the course of the experiment. We have recently shown that preparing NMR samples in an agarose gel matrix inhibits sedimentation and allows the characterization of small molecule-NP interactions by scNMR. Unfortunately, as the agarose gel only forms in aqueous solution, this sample preparation method cannot be used to stabilize NP suspensions in a non-aqueous environment. In this work, we introduce a library of 48 organogels, based on low molecular-mass organic gelators (LMOGs), to prepare NMR samples of small molecule/NP systems in a wide range of organic solvents. In addition, we present a simple method that takes advantage of 1H transverse relaxation (1H-R2) measurements to screen the library and identify the best gelator to characterize the small molecule-NP interaction of interest in the solvent of choice. We expect the results of this study will enable the preparation of homogeneous and stable samples of NPs in non-aqueous environments, therefore dramatically increasing the applicability of scNMR to the characterization of heterogeneous interactions and to the investigation of the role played by solvent molecules in regulating the kinetics and thermodynamics of sorption.

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

Comparative SEM and TEM analyses of apatite phases prepared by a multi-sample loading device

Highlights: • A multi-sample loading device which ultrasonically disperses samples was developed. • Comparative EM analyses on various apatite phases were efficiently carried out. • SEM-EDS data revealed distinctive values of O/P and Ca/P intensity ratios. • TEM-SAED data presented characteristic structural features of apatite phases. • Lattice parameters of bone and fossil apatite were affected by CO{sub 3} content. - Abstract: Comparative chemical and structural characterization of various apatite phases from both synthetic and natural sources were carried out by utilizing a multi-sample loading device developed for scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. The device is capable of spraying nanoparticles via ultrasonication, and four separate samples were loaded on a single TEM grid by a masking tool to characterize different apatite phases in consistent instrumental and analytical conditions. SEM energy dispersive spectroscopy (EDS) analysis of the apatite samples revealed distinctive values of O/P and Ca/P intensity ratios except for the fossil apatite due to its high proportion of externally originating phases. Selected area electron diffraction (SAED) pattern analysis presented the characteristic lattice parameters of the apatite phases, especially the bone and fossil apatite which had CO{sub 3}in their chemistry. Analyzing distinctive chemical and structural features among varied apatite phases can be efficiently carried out through electron microscopy with multiple samples on a single TEM grid, and such methods can be employed for characterizing a wider range of materials.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Trace Actinide Signatures of a Bulk Neptunium Sample

In nuclear forensic analyses, measurements of actinide elements in a sample can assist with identifying interdicted or unknown materials. While these radiochemical signatures have been extensively investigated in uranium materials, less is known about bulk neptunium samples. This paper describes the measurement of trace actinide concentrations and isotopic profiles in a 237 Np oxide sample. Uranium, plutonium, americium, and curium concentrations and isotopic profiles in the sample were determined and deemed potentially useful for distinguishing different sources of 237 Np. Furthermore, several different potential radiochronometry systems were also investigated; discordant results indicate that the Np sample was never completely purified of other actinide elements, or that subsequent contamination of the sample occurred. Few prior studies of neptunium materials have been reported, and these data suggest that trace actinide constituents could provide unique signatures to identify material out of regulatory control.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Automated Nanoflow Two-Dimensional Reversed-Phase Liquid Chromatography System Enables In-Depth Proteome and Phosphoproteome Profiling of Nanoscale Samples

Two-dimensional reversed-phase liquid chromatography (2D RPLC) separations have enabled near-comprehensive proteome profiling of biological systems. However, large samples containing milligram amounts of protein are usually required due to the significant sample losses incurred during offline fractionation. The large sample requirements preclude the application of 2D RPLC to biological systems having sample availability in the nanogram to low-microgram range. To achieve in-depth proteomic studies of trace samples, we have developed an automated nanoflow 2D RPLC platform in which the first dimension high-pH fractionation was performed at 300 nL/min on a 75-µm i.d. capillary column.Each fraction was then fully transferred to a second-dimension nanoLC separation using an autosampler equipped with a custom-machined syringe. In addition to optimizing fractionation conditions, we found that the use of a plastic 96-well plate as collection device and the adding of n-Dodecyl ß-D-Maltoside (0.01%) in the collection buffer can significantly improve sample recovery. We have demonstrated the nanoflow 2D RPLC platform can achieve confident identifications of ~37,000–69,000 unique peptides, corresponding to ~5300–6900 protein groups using only 100 to 1000 ng of HeLa tryptic digest. Furthermore, by integrating phosphopeptide enrichment, the platform can identify as many as ~20,000 phosphopeptides from 100 µg of MCF7 protein digest. Because this platform is assembled from commercially available components, our approach can be readily adapted in other proteomics laboratories.

Mass spectrometry, multidimensional separations, n↗
DOE OSTI2015

Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling

Cloud water and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry with nanospray desorption electrospray ionization and direct infusion electrospray ionization were utilized to compare the organic composition of the particle and cloud water samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloud water, showing the significant influence of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloud water samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloud water when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2017

High-throughput automated microfluidic sample preparation for accurate microbial genomics

Low-cost shotgun DNA sequencing is transforming the microbial sciences. Sequencing instruments are so effective that sample preparation is now the key limiting factor. Here, we introduce a microfluidic sample preparation platform that integrates the key steps in cells to sequence library sample preparation for up to 96 samples and reduces DNA input requirements 100-fold while maintaining or improving data quality. The general-purpose microarchitecture we demonstrate supports workflows with arbitrary numbers of reaction and clean-up or capture steps. By reducing the sample quantity requirements, we enabled low-input (B10,000 cells) whole-genome shotgun (WGS) sequencing of Mycobacterium tuberculosis and soil micro-colonies with superior results. We also leveraged the enhanced throughput to sequence B400 clinical Pseudomonas aeruginosa libraries and demonstrate excellent single-nucleotide polymorphism detection performance that explained phenotypically observed antibiotic resistance. Fully-integrated lab-on-chip sample preparation overcomes technical barriers to enable broader deployment of genomics across many basic research and translational applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

PySAGES: flexible, advanced sampling methods accelerated with GPUs

Abstract Molecular simulations are an important tool for research in physics, chemistry, and biology. The capabilities of simulations can be greatly expanded by providing access to advanced sampling methods and techniques that permit calculation of the relevant underlying free energy landscapes. In this sense, software that can be seamlessly adapted to a broad range of complex systems is essential. Building on past efforts to provide open-source community-supported software for advanced sampling, we introduce PySAGES, a Python implementation of the Software Suite for Advanced General Ensemble Simulations (SSAGES) that provides full GPU support for massively parallel applications of enhanced sampling methods such as adaptive biasing forces, harmonic bias, or forward flux sampling in the context of molecular dynamics simulations. By providing an intuitive interface that facilitates the management of a system’s configuration, the inclusion of new collective variables, and the implementation of sophisticated free energy-based sampling methods, the PySAGES library serves as a general platform for the development and implementation of emerging simulation techniques. The capabilities, core features, and computational performance of this tool are demonstrated with clear and concise examples pertaining to different classes of molecular systems. We anticipate that PySAGES will provide the scientific community with a robust and easily accessible platform to accelerate simulations, improve sampling, and enable facile estimation of free energies for a wide range of materials and processes.

Chemistry↗
DOE OSTI2017

Improved spatial resolution for spot sampling in thermal desorption atomic force microscopy – mass spectrometry via rapid heating functions

The key to advancing materials is to understand and control their structure and chemistry. However, thorough chemical characterization is challenging since existing techniques characterize only a few properties of the specimen, thereby necessitating multiple measurement platforms to acquire the necessary information. The multimodal combination of atomic force microscopy (AFM) and mass spectrometry (MS) transcends existing analytical capabilities for nanometer scale spatially resolved correlation of the chemical and physical properties of a sample surface. One such hybrid system employs heated AFM cantilevers for thermal desorption (TD) sampling of molecules from a surface and subsequent gas phase ionization and detection of the liberated species by MS. Here in this paper, we report on the use of voltage pulse trains to tailor cantilever heating such that spot sampling size was reduced and mass spectral signal was improved compared to constant voltage, static heating of the cantilever. Desorption efficiency (DE), defined as the quotient of the mass spectral signal intensity and the volume of the desorption crater, was used to judge the effectiveness of a particular tailored heating function. To guide the development and optimization of the heating functions and aid in interpreting experimental results, a 1D finite element model was developed that predicted the cantilever response to different heating functions. Three tailored heating functions that used different combinations, magnitudes, and durations of rectangular voltage pulses, were used for surface spot sampling. The resultant sampling spot size and DE were compared to the same metrics obtained with the conventional method that uses a single voltage pulse. Using a model system composed of a thin film of ink containing pigment yellow 74 as a model system, desorption craters shrunk from 2 μm, using the conventional approach, to 310 nm using the optimum tailored heating function. This same pulsed heating function produced a 381× improvement in the DE and an 8× improvement in spatial resolution compared to the conventional heating approach showing that signal/amount of material sampled was improved significantly by this new cantilever heating strategy.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Toward high-resolution NMR spectroscopy of microscopic liquid samples

A longstanding limitation of high-resolution NMR spectroscopy is the requirement for samples to have macroscopic dimensions. Commercial probes, for example, are designed for volumes of at least 5 mL, in spite of decades of work directed toward the goal of miniaturization. Progress in miniaturizing inductive detectors has been limited by a perceived need to meet two technical requirements: (1) minimal separation between the sample and the detector, which is essential for sensitivity, and (2) near-perfect magnetic-field homogeneity at the sample, which is typically needed for spectral resolution. The first of these requirements is real, but the second can be relaxed, as we demonstrate here. By using pulse sequences that yield high-resolution spectra in an inhomogeneous field, we eliminate the need for near-perfect field homogeneity and the accompanying requirement for susceptibility matching of microfabricated detector components. With this requirement removed, typical imperfections in microfabricated components can be tolerated, and detector dimensions can be matched to those of the sample, even for samples of volume << 5 uL. Pulse sequences that are robust to field inhomogeneity thus enable small-volume detection with optimal sensitivity. We illustrate the potential of this approach to miniaturization by presenting spectra acquired with a flat-wire detector that can easily be scaled to subnanoliter volumes. In particular, we report high-resolution NMR spectroscopy of an alanine sample of volume 500 pL.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Measuring Signatures of Fuel Irradiation in Large Particle Samples

Understanding the operating history of a nuclear facility is one of the key goals in nuclear safeguards, enabling the verification of declared activities. This is accomplished via a number of mechanisms, including the analysis of samples collected at the facility. The best metrics for understanding and verifying the history of nuclear fuel are (1) actinide isotopic content and (2) actinide inter-element ratios. While techniques have long existed for measuring these values with high accuracy and precision in bulk samples, as samples become smaller – such as may be collected in environmental collection – new methods are required both for clean processing of pure samples, and for analysis of these small samples. This study describes a new extraction chromatography technique for recovering U, Pu, and Am from single small aliquots, and advanced mass spectrometry methods for high-precision and high-accuracy analysis of trace and ultra-trace levels of actinides. These techniques are applied to particle samples cut from fuel from a historic nuclear reactor. Ages calculated from Pu–Am chronometry of particles are in excellent agreement with the known operating history of the reactor.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗