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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Excited and exotic charmonium, D s and D meson spectra for two light quark masses from lattice QCD

We present highly-excited charmonium, D s and D meson spectra from dynamical lattice QCD calculations with light quarks corresponding to M π ~ 240 MeV and compare these to previous results with M π ~ 400 MeV. Utilising the distillation framework, large bases of carefully constructed interpolating operators and a variational procedure, we extract and reliably identify the continuum spin of an extensive set of excited mesons. These include states with exotic quantum numbers which, along with a number with non-exotic quantum numbers, we identify as having excited gluonic degrees of freedom and interpret as hybrid mesons. Comparing the spectra at the two different M π , we find only a mild light-quark mass dependence and no change in the overall pattern of states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Ecological stoichiometry as a foundation for omics-enabled biogeochemical models of soil organic matter decomposition

Coupled biogeochemical cycles drive ecosystem ecology by influencing individual-to-community scale behaviors; yet the development of process-based models that accurately capture these dynamics remains elusive. Soil organic matter (SOM) decomposition in particular is influenced by resource stoichiometry that dictates microbial nutrient acquisition (‘ecological stoichiometry’). Despite its basis in biogeochemical modeling, ecological stoichiometry is only implicitly considered in high-resolution microbial investigations and the metabolic models they inform. State-of-science SOM decomposition models in both fields have advanced largely separately, but they agree on a need to move beyond seminal pool-based models. This presents an opportunity and a challenge to maximize the strengths of various models across different scales and environmental contexts. To address this challenge, we contend that ecological stoichiometry provides a framework for merging biogeochemical and microbiological models, as both explicitly consider substrate chemistries that are the basis of ecological stoichiometry as applied to SOM decomposition. We highlight two gaps that limit our understanding of SOM decomposition: (1) understanding how individual microorganisms alter metabolic strategies in response to substrate stoichiometry and (2) translating this knowledge to the scale of biogeochemical models. We suggest iterative information exchange to refine the objectives of high-resolution investigations and to specify limited dynamics for representation in large-scale models, resulting in a new class of omics-enabled biogeochemical models. Assimilating theoretical and modelling frameworks from different scientific domains is the next frontier in SOM decomposition modelling; advancing technologies in the context of stoichiometric theory provides a consistent framework for interpreting molecular data, and further distilling this information into tractable SOM decomposition models.

Carbon cycling↗
DOE OSTI2018

Effect of a Nitrogen Impurity on the Fundamental Raman Band of Diamond Single Crystals

The effect of nitrogen defects in natural and synthetic diamond single crystals on the position and half-width of the fundamental Raman band was investigated. Samples containing the main types of nitrogen lattice defects at impurity contents of 1–1500 ppm were studied. The parameters of the Stokes and anti-Stokes components in Raman spectra of crystals situated in a cell with distilled water to minimize the influence of heating by the exciting laser radiation were analyzed to determine the effect of a nitrogen impurity in the diamond crystal lattice. It was shown that an increase of impurity atoms in the crystals in the studied concentration range resulted in broadening of the Raman band from 1.61 to 2.85 cm{sup –1} and shifting of the maximum to lower frequency from 1332.65 to 1332.3 cm{sup –1}. The observed effect was directly proportional to the impurity concentration and depended on the form of the impurity incorporated into the diamond lattice. It was found that the changes in the position and half-width of the fundamental Raman band for diamond were consistent with the magnitude of crystal lattice distortions due to the presence of impurity defects and obeyed the Gruneisen law.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Hyperspectral Imaging and SPA–LDA Quantitative Analysis for Detection of Colon Cancer Tissue

Hyperspectral imaging (HSI) has been demonstrated to provide a rapid, precise, and noninvasive method for cancer detection. However, because HSI contains many data, quantitative analysis is often necessary to distill information useful for distinguishing cancerous from normal tissue. To demonstrate that HSI with our proposed algorithm can make this distinction, we built a Vis–NIR HSI setup and made many spectral images of colon tissues, and then used a successive projection algorithm (SPA) to analyze the hyperspectral image data of the tissues. This was used to build an identification model based on linear discrimination analysis (LDA) using the relative reflectance values of the effective wavelengths. Other tissues were used as a prediction set to verify the reliability of the identification model. The results suggest that Vis–NIR hyperspectral images, together with the spectroscopic classification method, provide a new approach for reliable and safe diagnosis of colon cancer and could lead to advances in cancer diagnosis generally.

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

Effect of Hydrothermal Aging on Injection Molded Short Jute Fiber Reinforced Poly(Lactic Acid) (PLA) Composites

This work focused on the durability of short jute fiber reinforced poly(lactic acid) (PLA) composites in distilled water at different temperatures (23, 37.8 and 60 °C). Morphological, thermal and mechanical properties (tensile, flexural, and impact) of jute/PLA composites were investigated before and after aging. Different from traditional synthetic fiber reinforced polymer composites, the stability of jute/PLA composites in water was significantly influenced by hydrothermal temperature. The mechanical properties of the composites and molecular weight of PLA matrix declined quickly at 60 °C, however, this process was quite slower at temperatures of 23 and 37.8 °C. Impact properties of the composites were hardly decreased, but the tensile and flexural properties suffered a drop though to various degrees with three degradation stages at 23 and 37.8 °C. The poor interface of composites and the degradation of PLA matrix were the main damage mechanism induced by hydrothermal aging. Furthermore, considering the hydrolysis of PLA matrix, the cleavage of PLA molecular chain in different aging time was quantitatively investigated for the first time to illustrate hydrolysis degree of PLA matrix at different aging time.

36 MATERIALS SCIENCE↗
DOE OSTI2019

The Development of Eco-Friendly Dye Microcapsules for Wool Fabric Dyeing Application

There is an urgent need to reduce the environmental impacts of wool fabrics dyeing process while maintain its dyeing effects. Microcapsule technology is a potential option which could be used to move towards cleaner production process and to cope with ever-increasing demands for wool fiber dyeing efficiency. Reactive dyestuff microcapsules were prepared via reverse-phase evaporation methods and then auxiliary-free dye microcapsules were used to dye the wool fabrics. Transmission electron microscope images and fourier transform infrared showed that dye microcapsules possessed a spherical core–shell structure with a diameter of about 500 ± 5 nm. The processing factors were analyzed and optimized by using response surface methodology to improve the encapsulation rate. Higher fixation rate (80.13% vs. 72.03%) of dyed wool fabric, while lower absorbance of dyestuff (0.071 vs. 0.96), chemical oxygen demand (COD, 190 mg/L vs. 1395 mg/L) and biological oxygen demand (BOD{sub 5}, 83.5 mg/L vs. 649.3 mg/L) of residual wastewater were observed by using microcapsule dyeing, compared with conventional dyeing process. In addition, the results also demonstrated that the filtrated wastewater of microcapsule dyeing can be recycled as dyebath to replace distill water. Thus, we innovatively produced a novel dye microcapsule for wool fabric dyeing application, advancing greatly in reducing the discharge of contaminants to environment, but also in economizing water and energy resources.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Quantum Mappings and Characterization of Entangled Quantum States

We review quantum mappings used in problems of characterization of entanglement of two-part and multi-particle systems. Together with positive and n-tensorial constant positive mappings, we consider physical dynamical processes that lead to quantum channels that break entanglement, annihilate entanglement, dissociate entanglement of multi-particle states, and prohibit distillation of output states. We introduce a new class of absolutely disentangling channels that provide absolutely separable states at the output, and also characterize a new class of entanglement-imposing channels whose output states are entangled. We present states that are most resistant to loss of entanglement and prove that they may differ from maximally entangled states.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Simultaneous sub-picogram speciation of methylmercury and ethylmercury in caustic nuclear tank waste using direct aqueous propylation

Organomercury species are present at regulatory levels in the tanks at the Savannah River Site. Calibration of methylmercury and ethylmercury ranged three orders of magnitude, generating detection limits of 0.033 pg and 7.50 pg, respectively. Calibration verifications maintained 101 and 103% accuracy, respectively, with mean recovery from waste samples of 104%. Here, dilution volume was optimized to eliminate sample distillation, decreasing method runtime by 337% and reducing total instrumentation footprint by 60.4% compared with current standard methods. Finally, compared with standard methods, this work represents a significant improvement in safety, efficiency, and reproducibility of organomercury speciation, particularly for industrial and nuclear analysis.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Thermally induced dispersive optical bistability in silver nanosuspensions produced by pulsed laser ablation method

The thermally induced optical bistability in prepared silver (Ag) nanosuspensions have been studied experimentally, using Fabry–Perot and Mach–Zehnder interferometry methods. Two Ag nanosuspensions of different sizes were produced by different fluences of pulsed laser ablation method in distilled water. The pulsed Nd:YAG laser of 7 ns pulse width, 1064 nm wavelength and different fluences was employed to produce Ag nanosuspensions. Experimental observations were performed by an ultraviolet–visible–near infrared spectrophotometry. Structure and size of prepared Ag nanoparticles were diagnosed using transmission electron microscope images. Fabry–Perot and Mach–Zehnder interferometry methods were used to carry out the optical bistability process in prepared Ag nanosuspensions. In two considered interferometers, the obtained phase shifts of the hysteresis loops based on the optical bistability are inversely proportional to the nonlinear refractive index of samples and thickness of Ag nanosuspensions cells. Results indicate that the induced thermal effect of the optical bistability can be tuned by modifying parameters such as the nonlinear refractive index and applied interferometry methods. Hence, a desirable situation for the thermo-optical effects of the optical bistability can be easily realized in Ag nanosuspensions.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Effects of laser fluence on the Cd(OH){sub 2}/CdO nanostructures produced by pulsed laser ablation method

In this experimental study, Cd (OH){sub 2}/CdO nanostructures were produced by pulsed laser ablation method. The beam of a Q-switched Nd:YAG laser with wavelength of 1064 nm at different fluences was employed to irradiate the cadmium target in distilled water. The obtained products at different fluences of laser pulse were characterized by UV–Vis-NIR spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results show that both morphology and chemical bonds of produced Cd nanostructures were changed by increasing the laser fluence. The absorption spectra shows that the Cd(OH){sub 2} nanostructures could be transformed into CdO nanostructures with increasing the laser fluence. XRD analysis showed the presence of crystalline γ-Cd(OH){sub 2}, Cd(OH){sub 2} and CdO phases, in the monoclinic, hexagonal and cubic structure, respectively. Results revealed that obtained nanostructures are particle in lowest fluence, while wire shaped nanostructures were formed with increasing the laser fluence. An increase of the laser fluence induced the synthesis of higher aspect ratio nanowires with a smaller tendency of adhesion.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Phase state diagram of a poly(amic acid)–solvent–nonsolvent system

Phase behavior and structure formation was studied using optical interferometry, nephelometry, and refractometry in the polymer–solvent–nonsolvent system for DMF solutions of two poly(amic acids): based on 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride and meta-phenylenediamine (PAA-1) and pyromellitic acid dianhydride and 4,4′-oxydianiline (PAA-2). Distilled water and its mixtures with DMF were used as a nonsolvent. According to the results of the study, isothermal cross sections of the phase state diagram in the threecomponent system were plotted, the position of the critical point, the spinodal, and the conodes were determined, the movement of the figurative points in the system was traced depending on the nonsolvent composition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Formation Mechanisms and Leachability of Hexavalent Chromium in Cr{sub 2}O{sub 3}-Containing Refractory Castables of Electric Arc Furnace Cover

Cr (III)-containing refractories are widely used as electric-arc furnace cover because of their excellent corrosion resistance properties. However, the formation of hexavalent chromium [Cr(VI)] remains a matter of concern during the service and subsequent disposal of the spent refractories. Moreover, the Cr(VI) formation mechanism and total amount of Cr(VI) generated are not clearly understood. In this study, samples from different parts of a spent electric arc furnace cover were collected from a local integrated steel plant. The phase composition, microstructure, formation and leachability of Cr(VI) were investigated using X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and TRGS 613 leaching test (Technische Regeln für Gefahrstoffe-TRGS 613-October 2002)/multiple leaching tests. A Cr(VI)-containing phase namely CaCrO{sub 4} existed in the sample at a medium temperature range, while another Cr(VI)-containing phase namely hauyne (Ca{sub 4}Al{sub 6}CrO{sub 16}) and a Cr(III)-containing phase (Al{sub 2}O{sub 3}–Cr{sub 2}O{sub 3} solid solution) formed in the high temperature region. Concentrations of Cr(VI) in the leachates (as in the TRGS 613 procedure) exceeded the European permissible limit. During the leaching tests in an acid condition, Cr(VI) was reduced by Fe{sup 2+}, which was primarily derived from the dissolution of FeO in the samples, while more Cr(VI) leached out with distilled water. Formation of an Al{sub 2}O{sub 3}–Cr{sub 2}O{sub 3} solid solution can inhibit Cr(VI) generation.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Slow Strain Rate Testing for Hydrogen Embrittlement Susceptibility of Alloy 718 in Substitute Ocean Water

The hydrogen embrittlement susceptibility of near-peak-aged UNS N07718 (Alloy 718) was evaluated by performing slow strain rate tests at room temperature in air and substitute ocean water. Tests in substitute ocean water were accomplished in an environmental cell that enabled in situ cathodic charging under an applied potential of −1.1 V versus SCE. Some specimens were cathodically precharged for 4 or 16 weeks at the same potential in a 3.5 wt.% NaCl-distilled water solution at 50 °C. Unprecharged specimens tested in substitute ocean water exhibited only moderate embrittlement with plastic strain to failure decreasing by about 20% compared to unprecharged specimens tested in air. However, precharged specimens exhibited significant embrittlement with plastic strain to failure decreasing by about 70%. Test environment (air or substitute ocean water with in situ charging) and precharge time (4 or 16 weeks) had little effect on the results of the precharged specimens. Fracture surfaces of precharged specimens were typical of hydrogen embrittlement and consisted of an outer brittle ring related to the region in which hydrogen infused during precharging, a finely dimpled transition zone probably related to the region where hydrogen was drawn in by dislocation transport, and a central highly dimpled ductile region. Fracture surfaces of unprecharged specimens tested in substitute ocean water consisted of a finely dimpled outer ring and heavily dimpled central region typical of ductile fracture.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Friction and Wear Properties of CrSiCN/SiC Tribopairs in Water Lubrication

CrSiCN coatings (3.4 at.% Si) were prepared on 316L stainless steels using unbalanced magnetron sputtering. According to the analysis results of x-ray diffractometer and x-ray photoelectrons spectroscopy, silicon in CrSiCN coatings mainly presented in the amorphous forms of a-SiN, a-SiCN and a-SiC. The hardness and Young’s modulus of CrSiN coatings were 19.4 ± 0.6 and 306.1 ± 5.9 GPa, respectively. In addition, the ball-on-disk sliding tests of CrSiCN/SiC tribopairs were performed in distilled water at varying velocities (0.1-0.5 m/s) and loads (2-12 N). The friction coefficient of tribopairs presented a decreasing trend with respect to velocity at low applied loads (≤ 4 N). To be specific, the low friction coefficient of 0.05-0.14 accompanied with polished wear scar was obtained at high velocities and low loads. Finally, the wear mechanism map of CrSiCN/SiC tribopairs was proposed based on a combination of friction coefficient, wear scar morphology and wear rates of tribopairs.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Computation of Effective Radiative Properties of Powders for Selective Laser Sintering Simulations

Selective laser sintering (SLS) is an additive manufacturing technique for rapidly creating parts directly from a computer-aided design (CAD) model by using a laser to fuse successive layers of powder. However, better understanding of the effect of particle-level variations on the overall build quality is needed. In this work, we investigated these effects computationally by considering the role of the particle size distribution and variations in the powder bed depth to mimic the part complexity found in overhangs and protrusions. In addition, the results from these studies can be distilled to obtain better effective material properties such as laser absorptivity and laser extinction coefficient that are needed for continuum models of the process. We implement a Monte Carlo ray-tracing algorithm within the discrete element model in the open-source simulation software MFiX. Random, loose-packed, particle bed structures are generated, and effective absorptivity and extinction coefficients are calculated. Results are compared against previous computational and experimental measurements for free, monodisperse, and deep powder beds, with good agreement being obtained. Correlations along with uncertainties are developed to allow the effective absorptivity and extinction coefficient as a function of various particle and operational parameters to be accurately set in SLS macroscale models.

Moser, Daniel↗
DOE OSTI2019

A Comparative Study of the Efficacy of Local/Global and Parametric/Nonparametric Machine Learning Methods for Establishing Structure–Property Linkages in High-Contrast 3D Elastic Composites

Reduced-order structure–property (S-P) linkages play a pivotal role in the tailored design of materials for advanced engineering components. There is a critical need to distill these from the simulation datasets aggregated using sophisticated, computationally expensive, physics-based numerical tools (e.g., finite element methods). The recent emergence of materials data science approaches has opened new avenues for addressing this challenge. In this paper, we critically compare the relative merits of the application of four distinct machine learning approaches for their efficacy in extracting microstructure-property linkages from the finite element simulation data aggregated on high-contrast elastic composites with different microstructures. The machine learning approaches selected for the study have included different combinations of local/global and parametric/nonparametric approaches. Furthermore, the nonparametric approaches selected for this study are based on Gaussian Process (GP) models that allow for a formal treatment of uncertainty quantification in the predicted values. The predictive performances of these different approaches have been compared against each other using rigorous cross-validation error metrics. Furthermore, their sensitivity to both the dataset size and dimensionality has been investigated.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Towards a systematic framework for the synthesis of operable process intensification systems

In this work we present an integrated framework to derive intensified designs with guaranteed safety and operability performance. A step-by-step procedure is described featuring: (i) superstructure-based process synthesis using Generalized Modular Representation Framework, (ii) development of advanced multi-parametric control strategies following the PAROC framework and software platform, and (iii) inherent safety analysis at early design stage utilizing quantitative risk assessment. Here, two case studies with increasing intensification complexity, namely heat exchanger network synthesis and reactive distillation column design, are investigated to demonstrate the capabilities of the proposed framework.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Evaluating agricultural trade-offs in the age of sustainable development

Here, a vibrant, resilient and productive agricultural sector is fundamental to achieving the Sustainable Development Goals. Bringing about such a transformation requires optimizing a range of agronomic, environmental and socioeconomic outcomes from agricultural systems – from crop yields, to biodiversity, to human nutrition. However, these outcomes are not independent of each other – they interact in both positive and negative ways, creating the potential for synergies and trade-offs. Consequently, transforming the agricultural sector for the age of sustainable development requires tracking these interactions, assessing if objectives are being achieved and allowing for adaptive management within the diverse agricultural systems that make up global agriculture. This paper reviews the field of agricultural trade-off analysis, which has emerged to better understand these interactions – from field to farm, region to continent. Taking a “cradle-to-grave” approach, we distill agricultural trade-off analysis into four steps: characterizing the decision setting and identifying the context-specific indicators needed to assess agricultural sustainability, selecting the methods for generating indicator values across different scales, deciding on the means of evaluating and communicating the trade-off options with stakeholders and decision-makers, and improving uptake of trade-off analysis outputs by decision-makers. Given the breadth of the Sustainable Development Goals and the importance of agriculture to many of them, we assess notions of human well-being beyond income or direct health concerns (e.g. related to gender, equality, nutrition), as well as diverse environmental indicators ranging from soil health to biodiversity to climate forcing. Looking forward, areas of future work include integrating the four steps into a single modeling platform and connecting tools across scales and disciplines to facilitate trade-off analysis. Likewise, enhancing the policy relevance of agricultural trade-off analysis requires improving scientist-stakeholder engagement in the research process. Only then can this field proactively address trade-off issues that are integral to sustainably intensifying local and global agriculture – a critical step toward successfully implementing the Sustainable Development Goals.

54 ENVIRONMENTAL SCIENCES↗