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At least 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

An Integrated High-Speed Microstructural Characterization Method Using Simultaneous XRD, Stereo-DIC, and PCI

High-speed characterization of the deformation mechanisms in polycrystalline metals requires the quantification of full strain fields and local microstructural evolutions simultaneously. In this paper, we present a novel experimental method to integrate phase-contrast imaging (PCI), stereographic digital image correlation (stereo-DIC), and full-ring X-ray diffraction (XRD) to allow for the simultaneous characterization of polycrystalline metals at 1MHz or higher. A Kolsky bar was integrated into the synchrotron X-ray source in Sector 32 ID-B at the Advance Photon Source (APS) at Argonne National Laboratory. When the sample is dynamically loaded, the diagnostic methods of full-ring XRD, PCI, and stereo-DIC are properly synchronized to record the deformation behavior at both continuum and microstructural scales as a function of the loading history. An advanced high-strength steel (AHSS) is used as a model material to demonstrate the capabilities of this new experimental method.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Characterization of biological materials with soft X-ray scattering

The complex structure of biological assemblies is crucial for function yet challenging to discern given the chemical similarities between constituent components. Hard X-ray techniques, for example, rely on small density differences between domains that lead to modest scattering intensities. Resonant soft X-ray scattering (RSoXS) uses X-rays below 2 keV to access absorption edges of low-Z elements. In this way, RSoXS can enhance scattering contrast between domains of different chemical compositions or bonding motifs, thus providing structural information about specific chemical motifs. RSoXS is emerging as a technique applicable for biological systems, having been used to characterize protein structure in solution and polysaccharide organization in plant cell walls. Sample environment instrumentation, however, is challenging in the current state of the art, particularly with liquid samples. Here, this chapter contains a brief introduction to RSoXS and current beamline capabilities, and provides methods to prepare, store, and mount biological samples for RSoXS characterization. Furthermore, key details during RSoXS and X-ray absorption data acquisition are highlighted and some future opportunities in RSoXS instrumentation for biological systems are discussed.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Linear dichroism of DNA: Characterization of the orientation distribution function caused by hydrodynamic shear

Linear dichroism provides information on the orientation of chromophores part of, or bound to, an orientable molecule such as DNA. For molecular alignment induced by hydrodynamic shear, the principal axes orthogonal to the direction of alignment are not equivalent. Thus, the magnitude of the flow-induced change in absorption for light polarized parallel to the direction of flow can be more than a factor of two greater than the corresponding change for light polarized perpendicular to both that direction and the shear axis. The ratio of the two flow-induced changes in absorption, the dichroic increment ratio, is characterized using the orthogonal orientation model, which assumes that each absorbing unit is aligned parallel to one of the principal axes of the apparatus. The absorption of the alienable molecules is characterized by components parallel and perpendicular to the orientable axis of the molecule. The dichroic increment ratio indicates that for the alignment of DNA in rectangular flow cells, average alignment is not uniaxial, but for higher shear, as produced in a Couette cell, it can be. The results from the simple model are identical to tensor models for typical experimental configuration. Approaches for measuring the dichroic increment ratio with modern dichrometers are further discussed.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Single molecule characterization of anomalous transport in a thin, anisotropic film

Here, the diffusion of small, charged molecules incorporated in an anisotropic polyelectrolyte multilayers (PEMs) was tracked in three dimensions by combining single-molecule fluorescence localization (to characterize lateral diffusion) with Förster resonance energy transfer (FRET) between diffusing molecules and the supporting surface (to measure diffusion in the surface-normal direction). Analysis of the surface-normal diffusion required model-based statistical analysis to account for the inherently noisy FRET signal. Combining these distinct single-molecule methods, which are inherently sensitive to different length scales, permitted simultaneous characterization of severely anisotropic diffusion, which was more than three orders of magnitude slower in the surface-normal direction. We hypothesize that the anomalously slow surface-normal diffusion was related to the periodic distribution of charge in the PEM, which created electrostatic barriers. The motion was strongly subdiffusive, with anomalous temporal scaling exponents in lateral and normal directions, suggesting a connection to the transient, random fractal conformation of polymer chains in the film’s matrix.

36 MATERIALS SCIENCE↗
DOE OSTI2019

X-ray characterization of the micromechanical response ahead of a propagating small fatigue crack in a Ni-based superalloy

The small fatigue crack (SFC) growth regime in polycrystalline alloys is complex due to the heterogeneity in the local micromechanical fields, which result in high variability in crack propagation directions and growth rates. Here in this study, we employ a suite of techniques, based on high-energy synchrotron-based X-ray experiments that allow us to track a nucleated crack, propagating through the bulk of a Ni-based superalloy specimen during cyclic loading. Absorption contrast tomography is used to resolve the intricate 3D crack morphology and spatial position of the crack front. Initial near-field high-energy X-ray diffraction microscopy (HEDM) is used for high-resolution characterization of the grain structure, elucidating grain orientations, shapes, and boundaries. Cyclic loading is periodically interrupted to conduct far-field HEDM to determine the centroid position, average orientation, and average lattice strain tensor for each grain within the volume of interest. Reciprocal space analysis is used to further examine the deformation state of grains that plasticize in the vicinity of the crack. Analysis of the local micromechanical state in the grains ahead of the crack front is used to rationalize the advancing small crack path and growth rate. Specifically, the most active slip system in a grain, determined by the maximum resolved shear stress, aligns with the crack growth direction; and the degree of microplasticity ahead of the crack tip helps to identify directions for potential occurrences of crack arrest or propagation. The findings suggest that both the slip system level stresses and microplasticity events within grains are necessary to get a complete description of the SFC progression. Further, this detailed dataset, produced by a suite of X-ray characterization techniques, can provide the necessary validation, at the appropriate length-scale, for SFC models.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Three-dimensional atomic scale characterization of {11$\overline{2}$2} twin boundaries in titanium

The {11$\overline{2}$2}<11$\overline{23}$> compression twin can accommodate a considerable amount of strain under c-axis compression in Ti. However, unlike the tensile twin, the structure of the {10$\overline{1}$2}$\langle$$\overline{1}$011$\rangle$ compressive twins has not been completely characterized. In this study, we apply a combined technique of HR-TEM characterization, topological analysis, and atomistic simulations to explore the facets that bound the {11$\overline{2}$2}<11$\overline{23}$> twin in Ti. In addition to the currently known facets (CTB and B-Py), six new facets are observed and categorized for the first time from atomic-scale TEM observations along five crystallographic directions. The six new facets are (11$\overline{2}$0)//(11$\overline{2}$6), PrPr1, PyPy1, (2$\overline{11}$1)//($\overline{1}$2$\overline{1}$2), (1$\overline{1}$04)//(01$\overline{11}$), and (01$\overline{1}$0)//(2$\overline{11}$4). Results from the topological and computational analysis are in reasonable agreement with and support the HRTEM observations. Specifically, (1) the observed facets align with low-index interfaces in both twin and matrix domains, (2) the facets with lower surface energies are found to form extended interfaces, and (3) high-surface-energy facets are found at the twin tip region and explained by the fact that the energy of the combined facet and facet junction configuration is energetically preferred in the twin tip region. These results not only provide a comprehensive understanding of the 3D structure of the {11$\overline{2}$2}<11$\overline{23}$> compressive twins in Ti, but also validate the MD procedure and the Ti interatomic potential employed. This is extremely important for future study of the {11$\overline{2}$2} twin mobility and interactions with other defects, both features that remain extremely challenging to capture in experiments.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Characterizing material transitions in large-scale Additive Manufacturing

Integrating Multiple Materials (MM) into large-scale Additive Manufacturing (AM) is a key for various industrial applications wishing to incorporate site-specific properties into geometrically complex designs that are difficult to manufacture with traditional techniques. Printing with multiple materials is typically accomplished by using layers as natural material boundaries, but having the capability to switch between materials within a single layer without pausing would further expand MM possibilities. This study used Cincinnati Incorporated’s Big Area Additive Manufacturing (BAAM) system to explore material transitions with a novel dual-hopper that enables in-situ material blending of a pelletized feedstock. Constructing MM and functionally graded material (FGM) structures requires depositing a specific material composition at a specific geometric location to achieve a desired performance. Furthermore, accurately implementing this with the BAAM’s blended extrusion system requires a thorough understanding of the transition between distinct material compositions. This study characterizes a step-change transition between neat acrylonitrile butadiene styrene (ABS) and carbon fiber-reinforced ABS. Three distinct techniques were compared for analyzing the fiber content, and the transition zone between materials was characterized as a function of transition direction. The transition process was consistent to within 0.7 wt% carbon fiber variation between different layers and prints. The transition between materials was found to be directionally dependent, with ABS to CF/ABS having a transition length of 3.5 m compared to 3.2 m for CF/ABS to ABS. Furthermore, the transition from Material A to Material B was found to be repeatable with a possible variance in transition length of 0.3 m.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Characterization of immiscible fluid displacement processes with various capillary numbers and viscosity ratios in 3D natural sandstone

We characterize the influence of reservoir conditions upon multiphase flow, we calculated fluid displacements (drainage processes) in 3D pore spaces of Berea sandstone using two-phase lattice Boltzmann (LB) simulations. The results of simulations under various conditions were used to classify the resulting two-phase flow behavior into three typical fluid displacement patterns on the diagram of capillary number (Ca) and viscosity ratio of the two fluids (M). In addition, the saturation of the nonwetting phase was calculated and mapped on the Ca–M diagram. We then characterized dynamic pore-filling events (i.e., Haines jumps) from the pressure variation of the nonwetting phase, and linked this behavior to the occurrence of capillary fingering. The results revealed the onset of capillary fingering in 3D natural rock at a higher Ca than in 2D homogeneous granular models, with the crossover region between typical displacement patterns broader than in the homogeneous granular model. Furthermore, saturation of the nonwetting phase mapped on the Ca–M diagram significantly depends on the rock models. These important differences between two-phase flow in 3D natural rock and in 2D homogeneous models could be due to the heterogeneity of pore geometry in the natural rock and differences in pore connectivity. By quantifying two-phase fluid behavior in the target reservoir rock under various conditions (e.g., saturation mapping on the Ca–M diagram), our approach could provide useful information for investigating suitable reservoir conditions for geo-fluid management (e.g., high CO 2 saturation in CO 2 storage).

58 GEOSCIENCES↗
DOE OSTI2018

Genomic characterization reveals significant divergence within Chlorella sorokiniana (Chlorellales, Trebouxiophyceae)

Selection of highly productive algal strains is crucial for establishing economically viable biomass and bioproduct cultivation systems. Characterization of algal genomes, including understanding strain-specific differences in genome content and architecture is a critical step in this process. Using genomic analyses, we demonstrate significant differences between three strains of Chlorella sorokiniana (strain 1228, UTEX 1230, and DOE1412). We found that unique, strain-specific genes comprise a substantial proportion of each genome, and genomic regions with >80% local nucleotide identity constitute <15% of each genome among the strains, indicating substantial strain specific evolution. Furthermore, cataloging of meiosis and other sex-related genes in C. sorokiniana strains suggests strategic breeding could be utilized to improve biomass and bioproduct yields if a sexual cycle can be characterized. Finally, preliminary investigation of epigenetic machinery suggests the presence of potentially unique transcriptional regulation in each strain. Our data demonstrate that these three C. sorokiniana strains represent significantly different genomic content. Based on these findings, we propose individualized assessment of each strain for potential performance in cultivation systems.

09 BIOMASS FUELS↗
DOE OSTI2019

Functional and phenotypic flow cytometry characterization of Picochlorum soloecismus

Multiple physiological traits essential for efficient cellular function are important when considering the selection and engineering of algal species for biofuel and bioproduct generation. Bioengineering methods have become more ubiquitous producing several novel algal lines with potentially enhanced traits. Complex metabolic interactions, however, require greater depth in characterizing cellular responses to delineate mechanistic understanding. Here, we have developed fluorescence-based high-throughput flow cytometry protocols to facilitate characterization of cell morphology, membrane permeability, metabolic activity, cell viability, intracellular pH, and reactive oxygen species in isolates derived from the species Picochlorum soloecismus. Flow cytometry parameters were optimized for each assay. This suite of molecular flow cytometry probes and procedures can be utilized for rapid screening of optimal phenotypes in microalgae under various environmental conditions as new technical strategies for improving algae strain productivity are established.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Characterization of the quantumness of unsteerable tripartite correlations

Quantumness for a bipartite unsteerable quantum correlation is operationally characterized by the notion of super-unsteerability. Super-unsteerability refers to the requirement of a larger dimension of the random variable that the steering party has to preshare with the party to be steered in the classical simulation protocol to generate an unsteerable correlation than the local Hilbert space dimension of the quantum states (reproducing the given unsteerable correlation) at the steering party’s side. In the present study, this concept of super-unsteerability is generalized by defining the notion of super-bi-unsteerability for tripartite correlations, which is unsteerable across a bipartite cut. Genuine super-bi-unsteerability is defined as the occurrence of super-bi-unsteerability across all possible bipartite cuts. Specific example of genuine super-bi-unsteerability for tripartite correlations has been presented. This study provides a tool to characterize the genuine quantumness of tripartite quantum correlations which are unsteerable across every bipartite cut.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Wave energy resource characterization employing joint distributions in frequency-direction-time domain

Joint and marginal distributions in the frequency, direction, and time domain are employed to demonstrate their value for wave energy resource characterization when full spectra are available. Insights gained through analysis of these distributions support wave energy converter concept design, operation and maintenance. Spatial trends in the wave energy resource and contributing wave energy systems along the continental shelf of the West Coast of the United States are investigated using the most recent two-dimensional wave spectra measurements at four buoys over an eleven year period (2008 to 2018). Resource hot spots and dominant resolved energy resource bands in the frequency-direction-time domain are delineated. Resource attributes, including frequency and directional spreading, and seasonal variability, are characterized using joint distributions and marginal distributions of wave power spectra. North Pacific westerly swells in the winter season, augmented by Aleutian low-pressure southwesterly swells, are the principal suppliers of the dominant resource and main drivers influencing resource attributes. In conclusion, the modification of these systems southward, especially the North Pacific westerly swells, explains the observed spatial resource trends. The dominant resource wave period shifts two seconds to higher wave periods, thirty degrees in the dominant direction band to a more northward orientation, and forward by one month.

16 TIDAL AND WAVE POWER↗
DOE OSTI2021

Characterization of Two Extraordinary AmLi Neutron Sources

Two legacy AmLi sources, MRC-101 and MRC-103, are routinely used for neutron detector characterization and testing campaigns that Pacific Northwest National Laboratory manages for the Defense Threat Reduction Agency within the U.S. Department of Defense. However, applicability of source measurement data has been substantially limited due to the lack of original manufacturer documentation and cross comparison to other sources. This paper summarizes results of the measurement campaign conducted to better quantify source radionuclide content, neutron energy spectrum and emission rate of the AmLi sources. The source characterization study consisted of three major consecutive measurement exercises. First, gamma spectrometry measurements using a high purity germanium detector were used to estimate the radionuclide content and potential impurities of the AmLi sources. Then neutron spectral measurements were taken to determine the unique neutron energy distribution. Finally, assessments of the total neutron yields of the sources were made with measurements in a neutron well counter. The neutron detection efficiency for these measurements was determined via detailed Monte Carlo modeling based on the neutron energy distribution measured with the rotating neutron spectrometer. The most exciting and unexpected finding of the study was a significant contamination of the source material with beryllium, contributing up to 17% to the total neutron emission rate and correspondingly changing the neutron energy spectrum. Also, the obtained lithium-only portion of the measured energy distribution of the sources was compared against several AmLi spectra previously reported by different researchers.

AWCC, AmLi, beryllium contamination, neutron spect↗
DOE OSTI2015

Characterization of the fusion core in zebrafish endogenous retroviral envelope protein

Zebrafish endogenous retrovirus (ZFERV) is the unique endogenous retrovirus in zebrafish, as yet, containing intact open reading frames of its envelope protein gene in zebrafish genome. Similarly, several envelope proteins of endogenous retroviruses in human and other mammalian animal genomes (such as syncytin-1 and 2 in human, syncytin-A and B in mouse) were identified and shown to be functional in induction of cell–cell fusion involved in placental development. ZFERV envelope protein (Env) gene appears to be also functional in vivo because it is expressible. After sequence alignment, we found ZFERV Env shares similar structural profiles with syncytin and other type I viral envelopes, especially in the regions of N- and C-terminal heptad repeats (NHR and CHR) which were crucial for membrane fusion. We expressed the regions of N + C protein in the ZFERV Env (residues 459–567, including predicted NHR and CHR) to characterize the fusion core structure. We found N + C protein could form a stable coiled-coil trimer that consists of three helical NHR regions forming a central trimeric core, and three helical CHR regions packing into the grooves on the surface of the central core. The structural characterization of the fusion core revealed the possible mechanism of fusion mediated by ZFERV Env. These results gave comprehensive explanation of how the ancient virus infects the zebrafish and integrates into the genome million years ago, and showed a rational clue for discovery of physiological significance (e.g., medicate cell–cell fusion). - Highlights: • ZFERV Env shares similar structural profiles with syncytin and other type I viral envelopes. • The fusion core of ZFERV Env forms stable coiled-coil trimer including three NHRs and three CHRs. • The structural mechanism of viral entry mediated by ZFERV Env is disclosed. • The results are helpful for further discovery of physiological function of ZFERV Env in zebrafish.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

In vivo and in vitro characterization of site-specific recombination of a novel serine integrase from the temperate phage EFC-1

EFC-1 integrase is a site-specific recombinase that belongs to the large family of serine recombinase. In previously study, we isolated the temperate phage EFC-1, and characterized its genomic sequence. Within its genome, Orf28 was predicted encode a 464 amino acid of a putative integrase gene. In this study, EFC-1 integrase was characterized in vitro and in vivo. In vitro assay was performed using purified His-tag fusion integrase. Also, to identify which serine is involved in the catalytic domain, we used site-directed mutagenesis and analyzed by a recombination assay in vitro. In vivo assay involved PCR and confocal microscopy in HEK293 cells, and determined the minimal lengths of attP and attB sites. According to our results, the EFC-1 integrase-mediated recombination was site-specific and unidirectional system in vitro and in vivo. Serine 21 of EFC-1 integrase plays a major role in the catalytic domain, and minimal sizes of attB and attP was defined 48 and 54 bp. Our finding may help develop a useful tool for gene therapy and gene delivery system. - Highlights: • EFC-1 integrase-mediated recombination was site-specific and unidirectional system. • Serine 21 of EFC-1 integrase plays a major role in the catalytic domain. • The functional minimal sizes of attB and attP was defined 48 and 54 bp.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Cloning and functional characterization of a phenolic acid decarboxylase from the liverwort Conocephalum japonicum

Some commercially important vinyl derivatives are produced by the decarboxylation of phenolic acids. Enzymatically, this process can be achieved by phenolic acid decarboxylases (PADs), which are able to act on phenolic acid substrates such as ferulic and p-coumaric acid. Although many microbial PADs have been characterized, little is known regarding their plant homologs. Transcriptome sequencing in the liverworts has identified seven putative PADs, which share a measure of sequence identity with microbial PADs, but are typically much longer proteins. Here, a PAD-encoding gene was isolated from the liverwort species Conocephalum japonicum. The 1197 nt CjPAD cDNA sequence was predicted to be translated into a 398 residue protein. When the gene was heterologously expressed in Escherichia coli, its product exhibited a high level of PAD activity when provided with either p-coumaric or ferulic acid as substrate, along with the conversion of caffeic acid and sinapic acid to their corresponding decarboxylated products. Both N- and C-terminal truncation derivatives were non-functional. The transient expression in tobacco of a GFP/CjPAD fusion gene demonstrated that the CjPAD protein is expressed in the cytoplasm. It is first time a PAD was characterized from plants and the present investigation provided a candidate gene for catalyzing the formation of volatile phenols.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Expression and characterization of the Plasmodium translocon of the exported proteins component EXP2

The malaria parasite Plasmodium falciparum requires the Plasmodium translocon of exported proteins (PTEX) to proliferate in human red blood cells. During the blood stages of malaria, several hundred parasite-encoded proteins are exported from the parasite into the cytosol of red blood cells. PTEX is the translocon for protein export and comprises 5 proteins: EXP2, PTEX150, PTEX88, Hsp101 and TRX2. Among them, EXP2 is thought to constitute the transmembrane pore, whereas the other components seem to play a role in unfolding the luggage proteins or providing a driving force. However, detailed functional and structural characterizations of PTEX proteins have not been performed. In this study, we expressed and characterized the membrane-associated component EXP2. Because expression of EXP2 is lethal to E. coli, EXP2 was expressed as a fusion protein with GST, and the recombinant EXP2 was obtained by protease digestion. The recombinant EXP2 formed pores in bilayer lipid membranes. The inner diameter of the pore was estimated to be approximately 3.5 nm based on electron microscopy images and channel currents. From this size and the molecular mass as determined by size exclusion chromatography and blue native polyacrylamide gel electrophoresis, we determined that the pore comprises approximately 10–12 EXP2 subunits. However, there is a possibility that the pore structure is different in the PTEX complex. These results provide important insights in the protein transport mechanism of PTEX, which will aid in developing new drugs targeting PTEX.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Pharmacological characterization of synthetic serine palmitoyltransferase inhibitors by biochemical and cellular analyses

Highlights: • Tetrahydropyrazolopyridine derivatives were characterized as SPT inhibitors. • The SPT inhibitors exhibited dual inhibitory activities against SPT2 and SPT3. • A SPT inhibitor bound to the SPT2 or SPT3 subunit in SPT enzyme complexes. • One of the SPT inhibitors exhibited a significantly slow dissociation from SPT. • The SPT inhibitors suppressed ceramide content in a non-small-cell lung cancer cell line. Human serine palmitoyltransferase (SPT) is a PLP-dependent enzyme residing in the endoplasmic reticulum. It catalyzes the synthesis of 3-ketodihydrosphingosine (3-KDS) from the substrates palmitoyl-CoA and l-serine. It is a rate-limiting enzyme for sphingolipid synthesis in cells. In the present study, we characterized and pharmacologically profiled a series of tetrahydropyrazolopyridine derivatives that potently inhibit human SPT enzymatic activity, including two cell-active derivatives and one fluorescent-labelled derivative. These SPT inhibitors exhibited dual inhibitory activities against SPT2 and SPT3. We used a fluorescent-labelled probe to molecularly assess the inhibitory mechanism and revealed its binding to the SPT2 or SPT3 subunit in the small subunit (ss) SPTa/SPT1/SPT2/or ssSPTa/SPT1/SPT3 functional complexes. One of the SPT inhibitors exhibited a significantly slow dissociation from the SPT complex. We confirmed that our SPT inhibitors suppressed ceramide content in non-small-cell lung cancer cell line, HCC4006, by performing a target engagement analysis. The potency of ceramide reduction correlated to that observed in a recombinant SPT2 enzyme assay. We thus elucidated and provided a fundamental understanding of the molecular mode of action of SPT inhibitors and developed potent, cell-active SPT inhibitors that can be used to clarify the biological function of SPT.

60 APPLIED LIFE SCIENCES↗