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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 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Reduction of front-metallization grid shading in concentrator cells through laser micro-grooved cover glass

Concentrator solar cell front-grid metallizations are designed so that the trade-off between series resistance and shading factor (SF) is optimized for a particular irradiance. High concentrator photovoltaics (CPV) typically requires a metallic electrode pattern that covers up to 10% of the cell surface. The shading effect produced by this front electrode results in a significant reduction in short-circuit current (I{sub SC}) and hence, in a significant efficiency loss. In this work we present a cover glass (originally meant to protect the cell surface) that is laser-grooved with a micrometric pattern that redirects the incident solar light towards interfinger regions and away from the metallic electrodes, where they would be wasted in terms of photovoltaic generation. Quantum efficiency (QE) and current (I)-voltage (V) characterization under concentration validate the proof-of-concept, showing great potential for CPV applications.

14 SOLAR ENERGY↗
DOE OSTI2016

Measurement of natural and {sup 137}Cs radioactivity concentrations at Izmit Bay (Marmara Sea), Turkey

In order to determine the radioactivity level at Izmit Bay Marmara Sea, marine sediment samples were collected from five different locations. The radioactivity concentrations of naturally occurring {sup 238}U, {sup 232}Th and {sup 40}K isotopes and also that of an artificial isotope {sup 137}Cs were measured by using gamma-ray spectroscopy. Preliminary results show that the radioactivity concentrations of {sup 238}U and {sup 232}Th isotopes are lower than the average worldwide values while the radioactivity concentrations of the {sup 40}K are higher than the average worldwide value. A small amount of {sup 137}Cs contamination, which might be caused by the Chernobyl accident, was also detected.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2016

Particle Number Concentrations for HI-SCALE Field Campaign Report

In support of the Holistic Interactions of Shallow Clouds, Aerosols, and Ecosystems (HI-SCALE) project to study new particle formation in the atmosphere, a pair of custom water condensation particle counters were provided to the second intensive field campaign, from mid-August through mid-September 2017, at the U.S. Department of Energy Southern Great Plains Atmospheric Radiation Measurement (ARM) Climate Research Facility observatory. These custom instruments were developed by Aerosol Dynamics, Inc. (Hering et al. 2017) to detect particles into the nanometer size range. Referred to as “versatile water condensation particle counter (vWCPC)”, they are water-based, laminar-flow condensational growth instruments whose lower particle size threshold can be set based on user-selected operating temperatures. For HI-SCALE, the vWCPCs were configured to measure airborne particle number concentrations in the size range from approximately 2nm to 2μm. Both were installed in the particle sizing system operated by Chongai Kuang of Brookhaven National Laboratory (BNL). One of these was operated in parallel to a TSI Model 3776, upstream of the mobility particle sizing system, to measure total ambient particle concentrations. The airborne particle concentration data from this “total particle number vWCPC” (Ntot-vWCPC) system has been reported to the ARM database. The data are reported with one-second resolution. The second vWCPC was operated in parallel with the BNL diethylene glycol instrument to count particles downstream of a separate differential mobility size analyzer. Data from this “DMA-vWCPC” system was logged by BNL, and will eventually be provided by that laboratory.

HI-SCALE, aerosol particle number concentration, v↗
DOE OSTI2019

Long-term Investigations of {sup 134}Cs and {sup 137}Cs Activity Concentrations in Honey from Croatia

This paper presents the results of long-term post-Chernobyl investigations of {sup 134}Cs and {sup 137}Cs activity concentrations in multifloral and chestnut honey sampled in northwest Croatia. For both radionuclides, the activity concentrations peaked in May 1986, decreasing exponentially until the mid-1990 s, when they fell under the detection limit for both radionuclides. After the Fukushima-Daiichi accident in 2011, the presence of both radionuclides in honey was detected once again. The ecological half-life was estimated to be 1.67 and 1.45 years for {sup 137}Cs and {sup 134}Cs, respectively. The correlation between {sup 134}Cs and {sup 137}Cs activity concentrations in fallout and honey was very good, indicating fallout to be the main source of honey contamination. The observed {sup 134}Cs/{sup 137}Cs activity ratio in honey was similar to the ratio found in other environmental samples. The estimated collective effective doses for the Croatian population incurred by honey consumption indicate that honey was not a critical pathway for the transfer of {sup 134}Cs and {sup 137}Cs from fallout to humans.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Effect of Varying Filler Concentration on Zinc Oxide Nanoparticle Embedded Chitosan Films as Potential Food Packaging Material

Prevailing scenario of non-biodegradable food packaging materials worldwide was the motivation for this research. More than half of the packaging materials used today are non-biodegradable and lack one or the other feature that keeps it from being an ideal food packaging material. Based on the current need of food grade packaging materials, the present study illustrates the amelioration of the properties of biodegradable chitosan films with the incorporation of zinc oxide (ZnO) nanoparticles in varying concentration. The ZnO nanoparticles (ZnONPs) used as fillers in the chitosan films were synthesized by supersaturation method. They were characterized using UV–visible spectrophotometry, X-ray diffraction and field emission scanning electron microscopy (FE-SEM). The particles were observed to be around 100–200 nm in size. The chitosan films with varying concentration of ZnONPs were synthesized and characterized using Fourier transform infrared spectroscopy and FE-SEM. The films were studied for their thermal stability, water vapor transmission rate (WVTR) and mechanical properties. The thermal stability, as determined by Thermo Gravimetric Analysis and Differential Scanning Calorimetry increased slightly with increasing percentage of embedded ZnONPs while a substantial decrease in WVTR was observed. Mechanical properties also showed improvements with 77% increment in tensile modulus and 67% increment in tensile strength. The antimicrobial activity of the films was also studied on gram positive bacterium Bacillus subtilis (B. subtilis) and gram negative bacterium Escherichia coli (E. coli) by serial dilution method. A twofold and 1.5-fold increment in the antimicrobial activity was observed for B. subtilis and E. coli, respectively, with increased ZnONPs concentration in the films from 0(w/w) to 2%(w/w). Films thus prepared can prove to be of immense potential in the near future for antimicrobial food packaging applications.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Giant Magnetoresistance in Electrochemical Deposited CoFe/Cu Multilayers Depending on Fe Concentration

Electrochemical deposition of CoFe/Cu multilayers were performed on Ti substrate from a single bath. 0.025, 0.05 and 0.1 M Fe concentration were used in electrolytes. The deposition potentials were selected − 1.5 V for magnetic layers and − 0.3 V for non-magnetic layers with respect to saturated calomel electrode. The current-time transients were obtained during the deposition process. The X-ray diffraction was used to define the structure of the multilayers. The multilayers were found to be face-centred cubic structure such as bulk Cu. Their lattice parameter and inter-planar distances values confirm this result. The magnetic measurements were performed at room temperature under 2 kOe external magnetic field. The results show that the saturation magnetization gradually increased from 27 to 50 emu/cm{sup 3} with increasing 0.025 to 0.05 M Fe concentration in electrolyte, and in the multilayer prepared from the electrolyte containing 0.1 M Fe concentration, this value drastically decreased to 18 emu/cm{sup 3}. The magnetoresistance measurements were carried out in magnetic fields in the range of ± 1.2 kOe. The high GMR value (18 %) and sensitivity (4.4 %/Oe) were obtained for this multilayer.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Magnetic Transition in Nonmetal N- and F-Doping g-ZnO Monolayer with Different Concentrations

In this paper, the geometrical, electronic, and magnetic properties of nonmetal (N, F) atom doping g-ZnO monolayer supercell forming 6.25, 12.5, and 25% concentrations have been investigated comprehensively using the first-principles method. The structural optimization implies that N or F atom doping g-ZnO monolayer causes the structural distortion around the doping atoms. Doping g-ZnO monolayer with one N atom is FM semiconductor, and the total magnetic moment is 0.651 μ{sub B}. The N–N-pair or two N–N-pair doping g-ZnO is AFM states. The total magnetic moments mainly originate from the spin polarization of the doping atom N, and the rest comes from the nearest Zn and O atoms. Doping g-ZnO with F atoms with the concentrations of 6.25, 12.5, and 25% all are nonmagnetic semiconductor. The F-doping can adjust energy band gap, which increases with the increase of F concentration.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Concentration-Dependent Transformation Plasticity Effect During Hydrogenation of Technically Pure Titanium Irradiated with an Electron Beam

Using the methods of X-ray diffraction analysis, the concentration-dependent transformation plasticity effect +TPE) is investigated during hydrogenation of the technically pure titanium (VT1-0) irradiated on one side with a low-energy high-current electron beam in a SOLO facility using three 50 μs pulses at the pulse repetition frequency 0.3 s{sup –1} and the beam energy density W = 18 J/cm{sup 2}. Its irradiation is performed in an argon atmosphere at the residual pressure 0.02 Pa. It is found out that the concentration-dependent TPE in the course of hydrogenation is due to the low stability state of the α-Ti crystal lattice formed in the specimen surface layer upon its e-beam irradiation. Relaxation of the elastic plane macrostresses occurs as a result of the development of concentration inhomogeneity of hydrogen or formation of α″-Ti and ω-Ti martensitic phases.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Machine learning applied to retrieval of temperature and concentration distributions from infrared emission measurements

Inversion of temperature and species concentration distributions from radiometric measurements involves solving nonlinear, ill-posed and high-dimensional problems. Machine Learning methods offer solving such highly nonlinear problems, offering an alternative way to deal with complex and dynamic systems with good flexibility. Here, we present a machine learning approach for retrieving temperatures and species concentrations from spectral infrared emission measurements in combustion systems. The training spectra for the machine learning model were synthesized through calculations from HITEMP 2010 for gas mixtures of CO 2 , H 2 O, and CO. The method was tested for different line-of-sight temperature and concentration distributions, different gas path lengths and different spectral intervals. Experimental validation was carried out by measuring spectral emission from a Hencken flat flame burner with a Fourier-transform infrared spectrometer with different spectral resolutions. The temperature fields above the burner for combustion with equivalence ratios of 𝜙 = 1, 𝜙 = 0.8, and 𝜙 = 1.4 were retrieved and were in excellent agreement with temperatures deduced from Rayleigh scattering thermometry.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Temporal performance indicators for an integrated pilot-scale membrane distillation-concentrated solar power/photovoltaic system

Management of concentrate streams in inland applications has uncertain long-term environmental impacts. This study investigates an intensified solar-energy capture desalination system that integrates membrane distillation (MD) with a hybrid concentrated solar power (CSP)/photovoltaic (PV) collector to realize self-sustained zero-waste discharge for effective management of concentrate streams in inland and off-grid applications. The demonstration-scale CSP/PV system can produce up to 178 kWh of thermal energy and 4 kWh of electrical energy per day. The thermal and electrical energy from the CSP/PV system is directly supplied to the air gap MD (AGMD) pilot-scale system producing up to 288 L of distilled water per day. Experiments were performed on the hybrid AGMD-CSP/PV system to evaluate system performance under various operating conditions including AGMD and CSP flow rates, CSP system pre-heating, and AGMD vacuum pressure. Experimental results indicate that doubling the AGMD flow rate results in a 119% increase in thermal energy utilization and a 71% increase in distillate production. Compared to the winter months, operating the system in summer months when direct normal irradiance (DNI) is highest results in nearly double the distillate production (88 L in winter and 168 L in summer) and nearly three times the amount of thermal energy consumption (15 kWh in winter and 43 kWh in summer). Operating with vacuum resulted in a 34% increase in distillate production and allowing the thermal storage reservoir to preheat in the winter resulted in a 61% increase in distillate production. Altogether, experimental results highlight the tradeoff between distillate production and thermal and electrical energy production and consumption under various environmental conditions and the potential for AGMD-CSP/PV to be a stand-alone desalination system.

14 SOLAR ENERGY↗
DOE OSTI2019

Calculation of supersaturation maximum and droplet concentration at cloud boundaries

Most parameterizations of droplet concentration at cloud base in cloud models are derived under the assumption that all droplets at the cloud base form by nucleation of dry CCN crossing the lifting condensation level in updraft. In this study, a novel method of calculation of the supersaturation maximum and droplet concentration at cloud base is described that takes into account the existence of liquid at the level of droplet nucleation. Liquid exists in haze particles, as well as in the form of cloud droplets and raindrops. It is shown that the presence of liquid water inside non-activated CCN, as well as of cloud droplets and raindrops substantially decreases supersaturation maximum in case of high aerosol concentration. The possible effect of the supersaturation maximum decrease on formation of DSD in clouds is discussed. The method can be also applied to calculation of supersaturation and droplet nucleation at cloud edges.

58 GEOSCIENCES↗
DOE OSTI2013

Vasopressin activates Akt/mTOR pathway in smooth muscle cells cultured in high glucose concentration

Highlights: •AVP induces mTOR phosphorylation in A-10 cells cultured in high glucose concentration. •The mTOR phosphorylation is mediated by the PI3K/Akt pathway activation. •The AVP-induced mTOR phosphorylation inhibited autophagy and stimulated cell proliferation. -- Abstract: Mammalian target of rapamycin (mTOR) complex is a key regulator of autophagy, cell growth and proliferation. Here, we studied the effects of arginine vasopressin (AVP) on mTOR activation in vascular smooth muscle cells cultured in high glucose concentration. AVP induced the mTOR phosphorylation in A-10 cells grown in high glucose, in contrast to cells cultured in normal glucose; wherein, only basal phosphorylation was observed. The AVP-induced mTOR phosphorylation was inhibited by a PI3K inhibitor. Moreover, the AVP-induced mTOR activation inhibited autophagy and increased thymidine incorporation in cells grown in high glucose. This increase was abolished by rapamycin which inhibits the mTORC1 complex formation. Our results suggest that AVP stimulates mTOR phosphorylation by activating the PI3K/Akt signaling pathway and, subsequently, inhibits autophagy and raises cell proliferation in A-10 cells maintained in high glucose concentration.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Cooperative Effects Associated with High Electrolyte Concentrations in Driving the Conversion of CO2 to C2H4 on Copper

Compared to a conventional electrolyte concentration of 1 M HCOOK, the use of a highly concentrated 7.1 M HCOOK electrolyte increases the Faradaic efficiency (FE) ratio of C2H4/CO from 2.2 +- 0.3 to 18.3 +- 4.8 at -1.08 V vs. reversible hydrogen electrode (RHE) on a Cu gas-diffusion electrode. Based on electrochemical analysis and ab initio molecular dynamics (AIMD) simulation, the identity and concentration of the cation and anion play more important roles in controlling the CO2R reaction pathway than the bulk CO2 solubility and the bulk pH of electrolytes. In situ attenuated reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) suggests that, unlike 1 M HCOOK, the *CO-bridge-binding mode on Cu is dominant in 7.1 M HCOOK electrolyte, which potentially results in less CO release and higher yield of C2H4. This study demonstrates that although we can tailor the electrolyte composition to shift product selectivity, the factors that control the product selectivity are numerous and cannot be distilled down into one correlated property-reactivity relationship.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

An extrapolation method to remove spurious stress concentration in micromechanical analyses of composites using pixel-based meshes

It is easier to generate a finite element mesh of complicated geometries with voxel-based meshes compared to conformal meshes. However, the local stresses in voxel-based meshes are higher owing to artificial stress concentration caused due to jagged lines that approximate a curve. Here, we propose a method that accounts for this anomaly which would lead to accurate prediction of maximum von Mises stress in voxel-based meshes. The method is based on the variation of reciprocal of stresses and associated numerical gradient. The prediction of the proposed method is compared against the results of a conformal mesh by considering four two-dimensional example problems. The accuracy of the proposed method is verified using different mesh densities, material properties, and integration schemes. The proposed method was also implemented on a conformal mesh to verify that it filters out just the spurious stress concentration and not the realistic stress concentration.

36 MATERIALS SCIENCE↗
DOE OSTI2023

VTAnDeM: A python toolkit for simultaneously visualizing phase stability, defect energetics, and carrier concentrations of materials

Phase stability, defect formation energies, and carrier concentrations are closely interrelated features of semiconductors. Due to their joint dependence on the multidimensional chemical potential space, it is challenging to quantitatively establish patterns between these quantities in a given semiconductor, especially when the semiconductor is comprised of multiple elements. To enable synchronous visualization and analysis of these complementary material properties and their interdependence, we developed the Visualization Toolkit for Analyzing Defects in Materials (VTAnDeM). This python-based toolkit allows users to interactively explore how defect formation energies and carrier concentrations vary across the composition and chemical potential spaces of multicomponent semiconductors. Here, we illustrate the computational workflow that employs VTAnDeM as a post-processing tool for first-principles calculations and describe the data organization and theory underlying the visualization scheme. Furthermore, we believe that this software will serve as a useful tool for simultaneously visualizing the often complex and non-intuitive chemical potential – defect – carrier concentration phase space of semiconductors.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Self-reported sunscreen use and urinary benzophenone-3 concentrations in the United States: NHANES 2003–2006 and 2009–2012

Background: Sunscreens protect against skin cancer and other harmful effects of solar ultraviolet radiation (UVR). Epidemiologic and public health surveys often rely on self-reported sunscreen use to estimate sun exposure and avoidance, but questions remain about the validity of self-reports. Benzophenone-3 (BP-3), a common sunscreen ingredient, can be detected in the urine. Prior studies suggest that BP-3 concentrations increase after application of sunscreen. Objectives: The goal of this study was to assess the validity of self-reported frequency of sunscreen use in relation to urinary BP-3 concentrations in a representative sample of the general US population, including in sub-groups defined by age, sex and race/ethnicity. Methods: To assess the relationship between categorical self-reported sunscreen use and creatinine-corrected urinary BP-3 concentrations, we conducted a linear regression adjusted for age, sex, race/ethnicity, six-month time period, body mass index, education, and sun avoidance behaviors. We tested for effect modification by age, sex, ethnicity and time period of measurement using multiplicative interaction terms and a F test. Results: BP-3 was positively associated with self-reported frequency of sunscreen use across all ages, sexes, race/ethnicities, and time periods. Crude and multivariate adjusted models were all statistically significant. R-square was relatively low for all models, ranging from 0.15 to 0.43. Conclusions: Urinary BP-3 is positively associated with self-reported frequency of sunscreen use in the general US population, even in groups with overall low sunscreen use. These results suggest that self-report is a valid, although weak, way of assessing relative frequencies of sunscreen usage in a population-based study. - Highlights: • Urinary benzophenone-3 (BP-3) is a metabolite of a common sunscreen ingredient. • We modeled urinary BP-3 against self-reported sunscreen usage. • We observed a positive association between sunscreen use and urinary BP-3. • R{sup 2} was low, suggesting self-report is a valid but weak way to assess sunscreen use.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Concentrations of arsenic and lead in residential garden soil from four Johannesburg neighborhoods

The 2017 Lancet Commission on Pollution and Health identified soil as an important, daily route of public exposure to a variety of pollutants. Lead and arsenic are two potential soil contaminants associated with serious health effects including reductions in intelligence, behavioral effects and aggressive or violent behavior (lead), as well as skin changes, cancer of the skin, bladder, liver and lungs and developmental delays (arsenic). In this study soil samples were collected, using US EPA methods, from gardens in four Johannesburg neighborhoods, and analyzed for lead and arsenic content using a portable X-ray fluorescence spectrometer. The results showed widely varied concentrations of arsenic and lead in soil collected across the four neighborhoods. Concentrations of lead (range: 0.1–2141.0 mg/kg; mean: 241.7 mg/kg (SD 282.8); median 158.1 mg/kg) exceeding local and international reference levels were found in an inner city suburb, while raised arsenic concentrations (range: 0.1–65.3 mg/kg; mean: 18.3 mg/kg (SD 11.7); median: 19.1) were found in the gardens of a suburb located very close to a mine tailings facility. This study confirms the potential for high levels of exposure to toxic metals in residential gardens in an urban African setting. There is a pressing need for scaled up attention to the public health implications of exposure to soil pollution in developing countries.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Low concentration electrolyte: A new approach for achieving high performance lithium batteries

The conventional perspective suggests that low-concentration electrolytes (LCEs) face challenges in achieving stable charge/discharge properties due to the decreased ionic conductivity resulting from lower Li + concentrations. However, the successful utilization of LCEs in lithium/sodium-ion batteries has brought them into the forefront of consideration for high performance battery systems. It is possible to achieve improved interface stability and ion transport performance for LCEs through adjusting electrolyte components, such as salts, solvents, and additives. This review provides timely update of the recent research progress, design strategies and remaining challenges of LCEs to answer several questions: i) What is the key factor for designing LCEs? ii) How to balance the low salt concentration and good ionic conductivity? iii) What is the interphasial mechanism of anode/cathode in LCEs? Firstly, the development of LCEs is discussed with typical examples. Subsequently, effectiveness of solvents on overall performances of LCEs is comprehensively summarized in detail. Finally, the challenges and possible research direction of LCEs are discussed. This review provides critical guidance for designing novel electrolytes for secondary batteries.

25 ENERGY STORAGE↗