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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

XPS and STEM Study of the Interface Formation between Ultra-Thin Ru and Ir OER Catalyst Layers and Perylene Red Support Whiskers

The interface formation between perylene red (PR) and ruthenium or iridium OER catalysts has been studied systematically by XPS and STEM. The OER catalyst over-layers with thicknesses ranging from ~0.1 to ~50 nm were vapor deposited onto PR ex-situ. As seen by STEM, Ru and Ir form into nanoparticles, which agglomerate with increased loading. XPS data show a strong interaction between Ru and PR. Ir also interacts with PR although not to the extent seen for Ru. At low coverages, the entire Ru deposit is in the reacted state while a small portion of the deposited Ir remains metallic. Ru and Ir bonding occur at the PR carbonyl sites as evidenced by the attenuation of carbonyl photoemission and the emergence of new peak assigned to C-O single bond. The curve fitting analysis and the derived stoichiometry indicates the formation of metallo-organic bonds. The co-existence of oxide bonds is also apparent.

Atanasoska, Liliana↗
DOE OSTI2018

Linguistic Privilege and Justice: What can we learn from STEM?

The linguistic privilege of native speakers in scientific communication, both oral and written, has been widely reported to influence researchers’ publications and careers in and beyond academia. I analyze social structure and communication in the STEM field through the example of big science and attempt to answer the question of why language injustice has a less significant effect on nonnative scientists and engineers than on humanity scholars, scrutinizing the role of signs and nonlinguistic boundary objects in STEM practice and written communication and how they mitigate the emphasis on linguistic eloquence. I suggest that although big science is relatively linguistically inclusive, for collaborative publications and presentations the rhetoric component requirements nevertheless remain at a level comparable to that of the humanities. I draw on the theory of justice to argue that to increase L2 speakers’ and writers’ satisfaction, language standards for international communication must be adjusted to a level convenient for an average L2.

Pronskikh, V.↗
DOE OSTI2019

ADVANCED-STEM-BASED DEEP LEARNING FOR SEMANTIC SEGMENTATION OF DEFECTS IN STEELS

In this work, we developed a novel deep convolutional neural network (DCNN) model, called DefectNet, for robust and automated semantic segmentation of three crystallographic defects including line dislocations, precipitates and voids commonly observed in structural metals and alloys. In previous work, we established an experimental protocol for a diffraction contrast imaging scanning transmission electron microscopy (DCI STEM) technique and tailored it specifically for imaging defects in popular iron-based structural alloy. Thus, the DefectNet was trained over a small but high-quality DCI STEM defect image sets of a HT-9 martensitic steel before and after neutron irradiation for 111.8 dpa at 412°C. For the defect quantification that typically takes at least half an hour even for an expert, with a good model the machine learning algorithm can produce more reproducible and reliable quantification in a few seconds. This work demonstrates the feasibility of using deep learning algorithms for fast and accurate defect quantitative analysis.

Machine Learning, Radiation effects, Image analysi↗
DOE OSTI2019

A Tool for Evaluating Youth Engagement in an Informal STEM Setting: The WGG Observation Protocol

This paper discusses findings from the use of the Wise Guys and Gals (WGG) Observation of WGG Youth Protocol in a blended learning environment. The protocol was used to assess youth engagement when completing blended engineering design challenges at two Boys and Girls Clubs. WGG is a project funded through a grant from the National Science Foundation and which brings blended learning design challenges to middle school aged learners in informal STEM (science, technology, engineering, and mathematics) settings. This paper explores the feasibility of using the observation protocol to collect data about youth engagement, and the potential use of the protocol in other informal STEM settings.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2024

WIP: Collaborating to Introduce Second-Life Battery Technology Research in an Informal STEM Learning Environment

This work in progress, innovative practice, paper outlines an interdisciplinary collaborative model utilized by a team of educational researchers, and engineers to design a series of community-centered, place-based learning activities suitable for a middle or high school informal STEM learning environment. Based on the potential applications and benefits of Second-Life Electric Vehicle Batteries, the activities connect cutting-edge STEM research with multidimensional real-world challenges within their communities related to climate change, renewable energy integration and storage, intelligent transportation systems, and optimized energy management, that empowers students to think critically about the role they can play in shaping a more resilient, environmentally sustainable community.

Whiteside, Hope↗
DOE OSTI2023

Adult dental epithelial stem cell-derived organoids deposit hydroxylapatite biomineral

Ameloblasts are specialized cells derived from the dental epithelium that produce enamel, a hierarchically structured tissue comprised of highly elongated hydroxylapatite (OHAp) crystallites. The unique function of the epithelial cells synthesizing crystallites and assembling them in a mechanically robust structure is not fully elucidated yet, partly due to limitations with in vitro experimental models. Herein, we demonstrate the ability to generate mineralizing dental epithelial organoids (DEOs) from adult dental epithelial stem cells (aDESCs) isolated from mouse incisor tissues. DEOs expressed ameloblast markers, could be maintained for more than five months (11 passages) in vitro in media containing modulators of Wnt, Egf, Bmp, Fgf and Notch signaling pathways, and were amenable to cryostorage. When transplanted underneath murine kidney capsules, organoids produced OHAp crystallites similar in composition, size, and shape to mineralized dental tissues, including some enamel-like elongated crystals. DEOs are thus a powerful in vitro model to study mineralization process by dental epithelium, which can pave the way to understanding amelogenesis and developing regenerative therapy of enamel.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2013

Targeting of Herpes Simplex Virus 1 Thymidine Kinase Gene Sequences into the OCT4 Locus of Human Induced Pluripotent Stem Cells

The in vitro differentiation of human induced pluripotent stem cells (hiPSC) to generate specific types of cells is inefficient, and the remaining undifferentiated cells may form teratomas. This raises safety concerns for clinical applications of hiPSC-derived cellular products. To improve the safety of hiPSC, we attempted to site-specifically insert a herpes simplex virus 1 thymidine kinase (HSV1-TK) suicide gene at the endogenous OCT4 (POU5F1) locus of hiPSC. Since the endogenous OCT4 promoter is active in undifferentiated cells only, we speculated that the HSV1-TK suicide gene will be transcribed in undifferentiated cells only and that the remaining undifferentiated cells can be depleted by treating them with the prodrug ganciclovir (GCV) prior to transplantation. To insert the HSV1-TK gene at the OCT4 locus, we cotransfected hiPSC with a pair of plasmids encoding an OCT4-specific zinc finger nuclease (ZFN) and a donor plasmid harboring a promoter-less transgene cassette consisting of HSV1-TK and puromycin resistance gene sequences, flanked by OCT4 gene sequences. Puromycin resistant clones were established and characterized regarding their sensitivity to GCV and the site of integration of the HSV1-TK/puromycin resistance gene cassette. Of the nine puromycin-resistant iPSC clones analyzed, three contained the HSV1-TK transgene at the OCT4 locus, but they were not sensitive to GCV. The other six clones were GCV-sensitive, but the TK gene was located at off-target sites. These TK-expressing hiPSC clones remained GCV sensitive for up to 90 days, indicating that TK transgene expression was stable. Possible reasons for our failed attempt to selectively target the OCT4 locus are discussed.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Girls in STEM: Year 1

This presentation describes the current status of girls in STEM courses and fields, why intervention in the early middle years, and the hypothesis set forth by the study.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2024

Optimize Electron Beam Energy toward In Situ Imaging of Thick Frozen Bio-Samples with Nanometer Resolution Using MeV-STEM

To optimize electron energy for in situ imaging of large biological samples up to 10 μm in thickness with nanoscale resolutions, we implemented an analytical model based on elastic and inelastic characteristic angles. This model has been benchmarked by Monte Carlo simulations and can be used to predict the transverse beam size broadening as a function of electron energy while the probe beam traverses through the sample. As a result, the optimal choice of the electron beam energy can be realized. In addition, the impact of the dose-limited resolution was analysed. While the sample thickness is less than 10 μm, there exists an optimal electron beam energy below 10 MeV regarding a specific sample thickness. However, for samples thicker than 10 μm, the optimal beam energy is 10 MeV or higher depending on the sample thickness, and the ultimate resolution could become worse with the increase in the sample thickness. Moreover, a MeV-STEM column based on a two-stage lens system can be applied to reduce the beam size from one micron at aperture to one nanometre at the sample with the energy tuning range from 3 to 10 MeV. In conjunction with the state-of-the-art ultralow emittance electron source that we recently implemented, the maximum size of an electron beam when it traverses through an up to 10 μm thick bio-sample can be kept less than 10 nm . This is a critical step toward the in situ imaging of large, thick biological samples with nanometer resolution.

36 MATERIALS SCIENCE↗
NASA NTRS2015

NASA Mission: Encouraging the Pursuit of STEM Excellence

In this presentation, Dr. Maricela Lizcano will discuss her academic career path at UTPA that directed her to earn a PhD in Mechanical Engineering. Dr. Lizcano will also discuss her research area at NASA Glenn Research Center (NASA-GRC) and the various educational and career opportunities available at NASA. Her experiences, challenges, and goals will serve to both advise and encourage UTRGV students to pursue a STEM career.

STEM↗
DOE OSTI2025

In Situ 4D‐STEM Imaging of the Orientation of Lamellar Clusters in Polymer Crystallization

In semi‐crystalline polymeric materials, the initial stages of nucleation and the growth path of crystalline domains can determine the final performance. Here, in this work, we used four‐dimensional scanning transmission electron microscopy (4D‐STEM) imaging to analyze the changes in lamellar orientation in high‐density polyethylene (HDPE) during heating and cooling. This method allowed us to quantitatively detect the formation of lamellae clusters with different in‐plane orientations, which are not visible with traditional methods. Our analysis provided detailed insights into the orientation and size changes of crystalline domains. Additionally, this technique enabled direct observation of lattice structures in hierarchical lamellae and the growth of crystals, confirming the local variability in lamellar orientation. This innovative approach significantly improves our understanding of polymer crystallization, linking changes in morphology and lattice structures at different length scales.

4D-STEM↗
DOE OSTI2017

Portal Vein Embolization with Contralateral Application of Stem Cells Facilitates Increase of Future Liver Remnant Volume in Patients with Liver Metastases

ObjectivesThis study aimed to evaluate the progress of future liver remnant volume (FLRV) in patients with liver metastases after portal vein embolization (PVE) with the application of hematopoietic stem cells (HSCs) and compare it with a patients control group after PVE only.MethodsTwenty patients (group 1) underwent PVE with contralateral HSC application. Subsequently, CT volumetry with the determination of FLRV was performed at weekly intervals, in total three weeks. A sample of twenty patients (group 2) who underwent PVE without HSC application was used as a control group.ResultsThe mean of FLRV increased by 173.2 mL during three weeks after the PVE/HSC procedure, whereas by 98.9 mL after PVE only (p = 0.015). Furthermore, the mean daily growth of FLRV by 7.6 mL in group 1 was significantly higher in comparison with 4.1 mL in group 2 (p = 0.007).ConclusionsPVE with the application of HSC significantly facilitates growth of FLRV in comparison with PVE only. This method could be one of the new suitable approaches to increase the resectability of liver tumours.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Comparative Analysis of the Formation of γH2AX Foci in Human Mesenchymal Stem Cells Exposed to {sup 3}H-Thymidine, Tritium Oxide, and X-Rays Irradiation

We performed a comparative study of the formation of γН2АХ foci (a marker of DNA doublestrand breaks) in human bone marrow mesenchymal stem cells after 24-h incubation with {sup 3}Н-thimidin and tritium oxide with low specific activities (50-800 MBq/liter). The dependence of the number of γH2AX foci on specific activity of 3H-thymidine was described by a linear equation y=2.21+43.45x (R{sup 2}=0.96), where y is the number of γH2AX foci per nucleus and x is specific activity in 1000 MBq/liter. For tritium oxide, the relationship was described by a linear equation y=2.52+6.70x (R{sup 2}=0.97). Thus, the yield of DNA double-strand breaks after exposure to {sup 3}H-thymidine was 6.5-fold higher than after exposure to tritium oxide. Comparison of the effects of tritium oxide and X-ray radiation on the yield of DNA double-strand breaks showed that the relative biological efficiency of tritium oxide in a dose range of 3.78-60.26 mGy was 1.6-fold higher than that of X-ray radiation. Improvement of the methods of analysis of DNA double-strand breaks repair foci is highly promising in the context of creation of highly sensitive biodosimetry technologies for tritium compounds in humans.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Apela Promotes Cardiomyocyte Differentiation from Transgenic Human Embryonic Stem Cell Lines

Although embryonic stem (ES) cells (ESCs) may be a promising donor source for the repair of infarcted or ischemic heart tissues, their successful application in regenerative medicine has been hampered by difficulties in enriching, identifying, and selecting cardiomyocytes from the differentiating cells. We established transgenic human ES cell lines by transcriptional control of the α-cardiac myosin heavy chain (α-MHC) promoter driving green fluorescent protein (GFP) expression. Differentiated GFP-expressing cells display the characteristics of cardiomyocytes (CMs). Apela, a recently identified short peptide, up-regulated the expression of the cardiac-restricted transcription factors Tbx5 and GATA4 as well as differentiated the cardiomyocyte markers α-MHC and β-MHC. Flow cytometric analysis showed that apela increased the percentage of GFP-expressing cells in the beating foci of the embryoid bodies. The percentage of cardiac troponin T (TNT)-positive cells and the protein expression of TNT were increased in the ES cell-derived CMs with apela treatment. Functionally, the contractile frequency of the ES-derived CMs responded appropriately to the vasoactive drugs isoprenaline and carbachol. Our work presented a protocol for specially labelling and enriching CMs by combining transgenic human ES cell lines and exogenous growth factor treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Splenic irradiation before allogeneic stem cell transplantation for myelofibrosis

Splenectomy before allogeneic stem cell transplantation (ASCT) for patients with myelofibrosis (MF) remains a matter of debate, and conflicting results have been reported to date. The procedure seems to fasten post-transplant hematological recovery, but it does not have an impact on survival. The role of pre-transplant splenic irradiation (SI) is much more difficult to evaluate. Forty-four patients (25 males and 19 females) with MF at median age of 49 years at diagnosis (range 14–67) underwent ASCT. The post-transplant outcome was compared between irradiated and non-irradiated patients. Eleven patients received irradiation before transplantation. Median dose of radiation was 1000 cGy (range 600–2400). There was no difference in median time to engraftment between patients with and without previous radiotherapy. Acute and chronic graft versus host disease (GVHD) occurred in 47% and 36% of patients, respectively. There was no difference in GVHD incidence between groups. Eight patients relapsed/progressed in irradiated group versus 17 in non-irradiated (70% vs. 51%; p = 0.3). Transformation to acute myeloid leukemia was observed in 3 patients: 2 in irradiated and 1 in non-irradiated group. In total, 22 patients died with no statistical difference in death rate between irradiated and non-irradiated subjects. The probability of overall survival after transplant for the entire cohort at 2 years was 54% (72% for irradiated and 48% for non-irradiated patients; p = 0.25). Splenic irradiation prior to ASCT for myelofibrosis has not beneficial effect on post-transplant outcome.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

Nanoscale mapping of point defect concentrations with $\mathrm{4D-STEM}$

Vacancies are missing atoms in a crystalline material, and occur both at equilibrium (varying with temperature) and out of equilibrium such as when crystalline materials are damaged with radiation or corrosion. While we know of their importance, particularly regarding diffusive mechanisms, it is not straightforward to experimentally measure their concentration or to visualize them directly. Traditionally, measurements such as positron annihilation spectroscopy and to some degree X-ray diffraction can measure average concentrations, but generally lack the ability to visualize or quantify a heterogenous concentration of vacancies that can occur at the level of individual defects and microstructural features. Here, we present a method to map vacancy concentrations and their distribution using local lattice parameter measurements with a high-resolution electron microscope. Our method utilizes a Au thin film as a model to demonstrate the method via four-dimensional scanning transmission electron microscopy (4D-STEM) by correlating the differences between changes in lattice parameter and the volumetric thermal expansion during in situ heating experiments. The vacancy mapping methodology is also applied to non-equilibrium defects accumulated in pure Al via knock-on electron beam irradiation. Our method demonstrates the ability to map point defect concentrations in heterogeneous systems in situ with nanometer spatial resolution. The result is a technique that can provide direct measurements of vacancy concentrations at the level of individual defects in studies of materials in and out of equilibrium.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Effects of strontium on proliferation and differentiation of rat bone marrow mesenchymal stem cells

Highlights: Black-Right-Pointing-Pointer Strontium ranelate (SrR) inhibits proliferation of BMMSCs. Black-Right-Pointing-Pointer SrR increases osteoblastic but decreases adipocytic differentiation of BMMSCs. Black-Right-Pointing-Pointer SrR increases expression of Runx2, BSP and OCN by BMMSCs in osteogenic medium. Black-Right-Pointing-Pointer SrR decreases expression of PPAR{gamma}, aP2/ALBP and LPL by BMMSCs in adipogenic medium. -- Abstract: Strontium ranelate (SrR) was an effective anti-osteoporotic drug to increase bone formation and decrease bone resorption. However, reports about the effect of SR on osteoblastic and adipocytic differentiation from bone marrow mesenchymal stem cells (BMMSCs) are limited. The purpose of this study is to evaluate whether SrR affects the ability of BMMSCs to differentiate into osteoblasts or adipocytes. Rat BMMSCs were identified by flow cytometry and exposed to SR (0.1 and 1.0 mM Sr{sup 2+}) under osteogenic or adipogenic medium for 1 and 2 weeks. The proliferation and differentiation of BMMSCs were analyzed by MTT, alkaline phosphatase (ALP), Oil red O staining, quantitative real-time RT-PCR and Western blot assays. SrR significantly inhibited the proliferation, increased osteoblastic but decreased adipocytic differentiation of rat BMMSCs dose-dependently. In osteogenic medium, SrR increased the expression of ALP, the mRNA levels of Cbfa1/Runx2, bone sialoprotein, and osteocalcin by RT-PCR, and the protein levels of Cbfa1/Runx2 by Western blot. In adipogenic medium, SrR decreased the mRNA levels of PPAR{gamma}2, adipocyte lipid-binding protein 2 (aP2/ALBP), and lipoprotein lipase (LPL) by RT-PCR, and the protein expression of PPAR{gamma} in Western blot analysis. These results indicated that the effects of SrR to promote osteoblastic but inhibit adipocytic differentiation of BMMSCs might contribute to its effect on osteoporosis treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Characterization of cancer stem cell properties of CD24 and CD26-positive human malignant mesothelioma cells

Highlights: Black-Right-Pointing-Pointer We focused on CD24 and CD26 for further analysis of CSC properties in MM. Black-Right-Pointing-Pointer Their expressions were correlated with chemoresistance, cell growth, and invasion. Black-Right-Pointing-Pointer Their expressions were also correlated with several cancer related genes. Black-Right-Pointing-Pointer The expression of each marker was correlated with different CSC property in Meso1. Black-Right-Pointing-Pointer Phosphorylation of ERK by EGF was regulated by expression of CD26, but not CD24. -- Abstract: Malignant mesothelioma (MM) is an asbestos-related malignancy characterized by rapid growth and poor prognosis. In our previous study, we have demonstrated that several cancer stem cell (CSC) markers correlated with CSC properties in MM cells. Among these markers, we focused on two: CD24, the common CSC marker, and CD26, the additional CSC marker. We further analyzed the CSC properties of CD24 and CD26-positve MM cells. We established RNAi-knockdown cells and found that these markers were significantly correlated with chemoresistance, proliferation, and invasion potentials in vitro. Interestingly, while Meso-1 cells expressed both CD24 and CD26, the presence of each of these two markers was correlated with different CSC property. In addition, downstream signaling of these markers was explored by microarray analysis, which revealed that their expressions were correlated with several cancer-related genes. Furthermore, phosphorylation of ERK by EGF stimulation was significantly affected by the expression of CD26, but not CD24. These results suggest that CD24 and CD26 differentially regulate the CSC potentials of MM and could be promising targets for CSC-oriented therapy.

60 APPLIED LIFE SCIENCES↗