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At least 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Interfacial microstructure and mechanical properties of rotary inertia friction welded dissimilar 422 martensitic stainless steel to 4140 low alloy steel joints

In this work, dissimilar rotary inertia friction welds between 422 martensitic stainless steel and 4140 martensitic low-alloy steel were made to fabricate prototype heavy-duty diesel engine pistons. The influence of the inertia friction welding process and post weld heat treatment (PWHT) temperature on the interfacial microstructure evolutions and corresponding effects on mechanical properties of the 422/4140 welds were evaluated in detail. Carbon diffused from the 4140 side to the 422 side during PWHT at 650 °C for 1.5 h, causing the formation of a hard carbide-rich layer on the 422 side, and a softer but discontinuous C-depleted layer the 4140 side. PWHT at 700 °C for 1.5 h greatly accelerated C diffusion across the interface relative to 650 °C, resulting in a thicker hard carbide-rich layer and a relatively thick and continuous layer of coarse C-depleted grains (ferrite) on the 4140 side. In addition, the PWHT temperature greatly influenced the tensile properties and fracture behavior of the welds, with the 650 °C PWHT-ed samples failing predominately in a ductile manner in the 4140 heat affected zone during tensile testing. Conversely, the 700 °C PWHT specimens exhibited a strength reduction compared with the 650 °C PWHT specimens because of additional coarsening of the interfacial ferrite layer and softening of the base materials during PWHT, with brittle fracture between the hard and soft layers the predominate failure mechanism. Based on the findings, a reduced PWHT temperature and/or time, minimizing the hardness differential of the base metals, and pre-heating the 422 steel prior to welding are the potential pathways to achieve a more optimal balance between desirable tempering and stress relief of the weld microstructure and undesirable C migration across the weld interface, and to reduce the strength mismatch across the weld.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Investigating the effect of aluminum oxide fixed charge on Schottky barrier height in molybdenum oxide-based selective contacts

A tunneling atomic layer deposited (ALD) AlO x layer was inserted in a Si|SiO x |AlO x |MoO x |metal tunnel diode structure to investigate the impact of fixed interface charge on Schottky barrier height. ALD AlO x provides a synthesis-tunable fixed charge and can provide excellent field effect passivation at the SiO x |AlO x interface. A large (>1 × 10 12 q.cm –2 ) negative fixed charge density was expected to decrease Schottky barrier height on p-type silicon and increase Schottky barrier height on n-type silicon by up to 0.4 eV based on an electrostatic model. Fixed charge density and interface trap state density were measured using a thick layer of AlO x in metal oxide semiconductor capacitor structures (MOSCAPs); Schottky barrier height and specific contact resistivity were measured using a tunneling-active layer of AlO x in contacted structures with MoO x . In some samples, HfO x interface layers were inserted between AlO x and silicon to quench the fixed negative charge. The Schottky barrier height was found to vary with processing conditions but did not have a strong correlation with expected fixed charge density. Here, while fixed charge may play a role in determining the Schottky barrier height, other parameters also have significant affect. Further work is needed to minimize contact resistivity and elucidate other factors impacting the Schottky barrier height.

14 SOLAR ENERGY↗
DOE OSTI2021

AlCl 3 -Dosed Si(100)-2 × 1: Adsorbates, Chlorinated Al Chains, and Incorporated Al

The adsorption of AlCl 3 on Si(100) and the effect of annealing the AlCl 3 -dosed substrate were studied to reveal key surface processes for the development of atomic-precision, acceptor-doping techniques. This investigation was performed via scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. At room temperature, AlCl 3 readily adsorbed to the Si substrate dimers and dissociated to form a variety of species. Annealing the AlCl 3 -dosed substrate at temperatures below 450 °C produced unique chlorinated aluminum chains (CACs) elongated along the Si(100) dimer row direction. An atomic model for the chains is proposed with supporting DFT calculations. Al was incorporated into the Si substrate upon annealing at 450 °C and above, and Cl desorption was observed for temperatures beyond 450 °C. Al-incorporated samples were encapsulated in Si and characterized by secondary ion mass spectrometry (SIMS) depth profiling to quantify the Al atom concentration, which was found to be in excess of 10 20 cm –3 across a ~2.7 nm-thick δ-doped region. Here, the Al concentration achieved here and the processing parameters utilized promote AlCl 3 as a viable gaseous precursor for novel acceptor-doped Si materials and devices for quantum computing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Ferroelectric epitaxial Al(Sc/B)N/Mo/SiC heterostructures for high operating temperature devices

Advances in wurtzite nitride ferroelectrics of Al 1-x M x N (⁠ M = Sc or B) have led to novel capabilities, which must be integrated into existing fabrication processes. In the case of electronics operating > 200°C, a movement toward SiC-based platforms enables better performance over conventional Si, primarily due to the higher bandgap and lower intrinsic carrier concentration of SiC. Hence, the challenge is to develop a deposition process to integrate Al 1-x M x M x N ferroelectrics with elevated temperature-compatible materials for high temperature electronics such as the non-volatile memory component. We demonstrate epitaxial Al M N/Mo/SiC heterostructures, which provides both the crystalline and surface features that promote high-quality ferroelectric nitride film growth. Omega scans of the Mo (110) reflection exhibit a full width at half max of < 0.02° (40 arc sec) and the (0002) peak of the subsequently grown nitride film had a value of 1.1° for 160 nm thick Al 0.7 Sc 0.3 N and 1.3° for 400 nm thick Al 0.94 B 0.06 N. The crystallographic relationships found between the Al M N, Mo, and SiC layers indicate an advancement in sputter deposition of epitaxial films. Ferroelectric switching is also shown at 400 °C in both samples via polarization-electric field hysteresis and pulsed measurements, which exhibited P r values >100 μC cm -2 and E c between 3 and 4 M V cm -1 ⁠, despite a large presence of oxygen in both Al M N films ranging between 4 and 5 at.%, revealed by compositional analysis. This study demonstrates the process for synthesizing high-crystal quality ferroelectric nitride films, which can be used in extremely high temperature applications.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Second-harmonic and linear spectroscopy of $\textit{α}$-In 2 Se 3

We report spectroscopic measurements of optical transmission, ellipsometry, and second-harmonic generation (SHG) from as-grown vapor-deposited $\textit{α}$-In 2 Se 3 nanoflakes ranging in thickness from a single quintuple layer (QL) to bulk material. In this work, we compare these measurements with ab initio calculations of structural and optical properties. Linear optical measurements yield thickness-dependent band gaps and dielectric functions, while SHG diagnoses microscopic film structure and ferroelectric polarization. The rotational anisotropy of SHG for s-polarized incident photons of energy 1.4 eV reveals crystalline symmetry and orientation of individual QLs. Peak SHG intensity increases from one to three QLs, then decreases for larger numbers, tracking thickness-dependent trends in the second-order susceptibility components $χ^{xxx}$ and $χ^{zxx}$. Comparison of measured and calculated SHG spectra for s-polarized photons of energies between 1.2 and 1.7 eV incident upon two QL samples discriminates among candidate stacking arrangements, and favors an arrangement with electric polarization vectors of the two QLs pointing outward in opposite directions.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Geochronology of Cambrian Sedimentary and Volcanic Rocks in the Illinois Basin: Defining the Illinois Aulacogen

The Wabash #1 well, drilled for the Wabash CarbonSAFE Project and located in Vigo County, Indiana, USA, was drilled in early 2020 as a stratigraphic test well to characterize and evaluate the basal Cambrian Mt. Simon Sandstone for carbon dioxide storage (TD=8750 ft; 2667 m). The Wabash #1 well is located along the eastern flank of a newly interpreted Cambrian aulacogen that occurs in western Indiana and eastern Illinois. Here we present 938 new detrital zircon U-Pb ages (LA-ICPMS) from early Cambrian sandstones sampled near the base of the well. A basalt lava flow was penetrated at ~8530 ft (2600 m) and has an 40 Ar/ 39 Ar age of 525.03 +/- 1.10 Ma, which represents the first known Cambrian crust in the Illinois Basin. The two sandstone samples from beneath the basalt are dominated by zircons derived from the Midcontinent Granite-Rhyolite terrane. The sandstone samples from above the basalt reflect a mixture of these locally derived Mazatzal and Granite-Rhyolite terrane zircons, but also distal Archean, Grenville, and Yavapai zircons. Each sample has small numbers of Cambrian zircons, which is consistent with those in basal Cambrian sandstones in other deep wells to the west. These early Cambrian detrital zircons and early Cambrian age of the basalt, combined with sediment thickness patterns permit the interpretation of the Illinois aulacogen, which formed during the final stage of Rodinian rifting.

58 GEOSCIENCES↗
NASA NTRSDate not supplied

Eruption Characterisitics of Lunar Localized Pyroclastic Deposits Based on Water Content, Mineralogy, Regolith Properties

Lunar pyroclastic deposits are low albedo deposits present throughout the lunar surface including both maria and highlands, nearside and farside, and high latitudes and equatorial regions [e.g., 1]. There are two main types of pyroclastic deposits based upon size: localized (<2500 km2) and regional pyroclastic deposits (>2500 km2) [1]. In this study, we focus on the smaller localized pyroclastic deposits. The first and most detailed study of localized pyroclastic deposits are the deposits in Alphonsus crater [2]. This study included examining the radar and volumetric properties of these deposits. They found that vulcanian-like eruptions are most consistent with their observations. They imagined that a dike intrudes into the crust and creates a cooled basaltic cap. With increasing pressure under the basaltic cap, the pressure eventually overwhelms the surrounding rocks and results in explosive decompression. Later studies examined several pyroclastic deposits across the lunar surface using radar [2–4], digital terrain models (DTMs) [2,4], visible and near-infrared spectrometers [1,4–7], and a radiometer [4] to determine the mineralogy (e.g., olivine, glass, clinopyroxene, orthopyroxene, and plagioclase), deposit thickness and volume, proportion of juvenile material, radar backscatter, surface rock abundance, and regolith density. These various properties were examined against one another to better group localized pyroclastic deposits and understand how they relate to one another [4]. One of the studies divided pyroclastic deposits into three groups based upon the shape of the 1-μm absorption feature. The three Groups could be interpretated as having highlands and pyroclastic material (Group I), mare and pyroclastic material (Group II), and glass and orthopyroxene material (Group III) [5]. Building on that foundation, another study divided the pyroclastic deposits into four groups based upon their surface rock abundance and glass abundance [4], where deposits are classified based upon low surface rock abundance and high glass abundance (Glassy deposits); high rock abundance, high glass abundance (Blocky deposits); moderate rock abundance and low glass abundance (Crystalline deposits); and high rock abundance and low glass abundance (Indistinct Group). In addition to these studies, we can now look at their water contents using the new Effective Single Particle Absorption Thickness (ESPAT) parameter map [8]. The ESPAT map measures the strength of the 3-μm absorption feature in single scattering albedo space. The strength of this feature and its relationship to water content has been calibrated to returned samples, which allows for water content to be derived from remote spectral data (i.e., Moon Mineralogy Mapper). The goal of this study is to examine how water content in the pyroclastic deposits varies with respect to the geometric, mineralogic, and physical properties of the localized pyroclastic deposits as measured by a previous study [i.e., 4]. A more complete version of this work is found in [9].

D Trang↗
NASA NTRSDate not supplied

rHealth One Demonstration Aboard ISS: A Microfluidic Bioanalyzer Based on Sheath/Hydrodynamic Focusing Flow Cytometry

The Exploration Medical Capability (ExMC) element aims to provide astronauts with the means for their own health monitoring, diagnosis, and treatment during exploration missions. As space flight ventures further from earth, the need for autonomous medical care increases under greater constraints on size, mass, and resources. One pillar for diagnosis that crew would be separated from is laboratory analysis. Even now on ISS, blood samples must be collected and returned to earth for testing. In response, ExMC is assessing how assays for hematology, bone health, radiation exposure etc. could be addressed through commercial-off-the-shelf (COTS) and Small Business Innovation Research (SBIR) funded bioanalyzers that are miniaturizing lab technology. Since missions will reach distances where there are no timely replacements, validation on the International Space Station (ISS) is a necessary part of that assessment. In partnership with NASA Johnson Space Center (JSC) Immunology Lab and the Research Operations and Integration (ROI) element, ExMC conducted a technology demonstration on ISS of the rHEALTH ONE, a flow cytometry based bioanalyzer, to assess future devices based on this design. In flow cytometry, there are predominantly three ways to focus the cells (or particles) into a single file stream: hydrodynamic focusing, microcapillary, and acoustic focusing. The rHEALTH ONE utilizes the commercial standard, sheath-based hydrodynamic focusing. rHEALTH itself represents both a company and a suite of medical tools NASA has funded through SBIR grants towards the development of a promising diagnosis instrument for exploration missions. rHEALTH ONE is the interim version of the technology, functional as a benchtop analyzer and test bed for the next generation of rHEALTH in development. Several modifications were made to the rHEALTH ONE analyzer for operation in microgravity. For function, fluid management was key. A sheath-based analyzer uses sheath fluid to flow the sample, cleaning fluid to prevent biological contamination, and a reservoir to collect the liquid waste. The rHEALTH ONE analyzer uses bottles dependent on gravity to separate the air and liquid pathways and keep the liquids contained. It uses only 1 psig of air pressure to directly push the liquid through the device, requiring little-to-no resistance at inlet and outlet. A microtubing assembly with self-sealing luer connectors was designed – featuring 0.014 mm thick durable medical balloons to hold water inside the supply bottles – to create safe containment and easy access for the crew while maintaining the analyzer’s function. For safety, copper tape was added to the interior of the plastic housing to reduce electromagnetic interference, fluid and electrical connections were secured against vibration and leaks, and gaps were further sealed to ensure containment of the optical block and lasers. Water as the sheath and cleaning fluid and TOX 0 samples were used to reduce the biohazard risk to the crew. In May 2022, European Space Agency astronaut Samantha Cristoforetti demonstrated the rHEALTH ONE aboard ISS for its sample loading, flow cytometry, and data collection capability in microgravity. The JSC Immunology Lab provided flow cytometry expertise, designed the sample test protocol, and manufactured and benchmarked the flight samples on a ‘gold-standard’ flow cytometer. The analyzer was primed with water, purged of air, and four calibration solutions of polystyrene microparticles were tested to characterize its performance. Tightly controlled procedures and excellent execution prevented air bubble interference during air/water separation, fluid transfer, sample mixing and loading. Data showed a slight increase in signal noise on 3 of 5 channels and an anomaly of fluorophores migrating in one sample (confirmed by JSC post-flight). Flight results correctly detected the change in sample, matched the analyzer’s ground performance, and were consistent with the gold-standard’s ground results. Although areas were noted for improvement, these outcomes signified complete mission success.

R. S. Miller↗
NASA NTRS2015

Exploration Architecture with Quantum Inertial Gravimetry and In-Situ ChipSat Sensors

The Dual Exploration Architecture is a mission concept that combines remote sensing and in-situ observations into a single mission to answer planetary science questions that can only be answered with both types of data. Adoption of dual exploration architectures may short circuit the long, slow cycle of missions to inaccessible bodies by eliminating the need for separate precursor and follow-up missions. Additionally, the dual architecture possesses inherent flexibility that enables the design of adaptive, event-driven missions that are very different from traditional, largely pre-planned missions. Five key observations about the state and trends of planetary science exploration lead us to the dual architecture: increasing complexity of observations; scarcity of future mission opportunities; desire to capture transitory events; continued miniaturization of spacecraft components; and the Mars exploration cycle. Our goal in this study is to explore missions that can only happen using the dual architecture concept and find technology development needs that must be filled for those missions to compete. A survey of historical and current missions finds that opportunities for exploration are becoming less frequent, causing the flexibility and dual-nature elements of each mission to become more common. The dual exploration architecture takes these trends to their far conclusion, attempting to eliminate precursor and follow-up missions while still returning more scientific payoff. A study of the future of planetary science goals through the decadal survey reveals broad applicability of dual missions to solve mysteries that cannot be answered with a traditional mission architecture. These missions fall into three broad classes: choosing a local target from a global survey; dynamic/reactive science; and global in-situ networks. Two example missions of each class are notionally described. A deeper look at these dual architecture classes reveals four technology development needs that must be addressed for wide adoption of dual missions: passive landers; guided atmospheric probes; robust sensing packages; and small, precise orbital instruments. This study pursues a specific focus on two examples of such enabling technologies: the ChipSat and cold atom gravimetry. The ChipSat is a fully functional spacecraft-on-a-chip system that has broad versatility in the dual architecture mission space. Initial studies show that ChipSats could survive as passive impactor landers on bodies up to the size of Europa. Furthermore, COTS (Commercial Off-The-Shelf) components could provide an in-situ sensor suite that readily answers a number of pressing planetary science questions. Cold atom gravimetry uses inertial sensors based on light-pulse atom interferometry in a small form factor to map the gravity field of a body to precision equaling what would normally require two full spacecraft to achieve. The cold atom gravimeter provides an example of how advanced remote sensing capability can enable dual missions by providing greater returns in a significantly smaller package. Using the above two technologies, we study an example dual-architecture mission to both characterize and sample the subsurface oceans at Europa. The greatest scientific return in terms of detecting extraterrestrial life is in those regions where Europa’s ice crust is thin. The identification of regions with thin ice should therefore precede the selection of surface targets and dispatch of probes to those targets. This two-step process, if accomplished by separate flagship-scale missions, might take decades. As a result, a combined mission to both identify thin areas of Europa’s ice and follow up with surface observations at those regions is a good candidate for the dual-exploration architecture. This example mission consists of an orbiter spacecraft carrying a cold atom gravimeter capable of sensing or inferring the ice thickness on regional to local scales, along with a number of ChipSat probes capable of landing on the moon. The small size and weight of the ChipSats allows large numbers of them to be carried, ensuring that enough can be dropped to ensure survival of a minimum number of probes and potentially allowing for the in-situ sampling of multiple locations on the moon. The example missions and Europa case study show that amazing scientific return can obtained from dual-exploration architecture missions with a single launch by breaking the long timescales of planetary exploration and providing the flexibility to capturing transitory events and collect data across the local, regional, and global scales.

Exploration↗
DOE OSTI2022

Controlling magnetic configuration in soft–hard bilayers probed by polarized neutron reflectometry

Hard/soft magnetic bilayer thin films have been widely used in data storage technologies and permanent magnet applications. The magnetic configuration and response to temperatures and magnetic fields in these heterostructures are considered to be highly dependent on the interfacial coupling. However, the intrinsic properties of each of the layers, such as the saturation magnetization and layer thickness, also strongly influence the magnetic configuration. Changing these parameters provides an effective method to tailor magnetic properties in composite magnets. Here, we use polarized neutron reflectometry (PNR) to experimentally probe the interfacial magnetic configurations in the hard/soft bilayer thin films: L1 0 -FePt/A1-FePt, [Co/Pd]/CoPd, [Co/Pt]/FeNi, and L1 0 -FePt/Fe, all of which have a perpendicular magnetic anisotropy in the hard layer. These films were designed with different soft and hard layer thicknesses (t soft and t hard ) and saturation magnetization (M$_s^{soft}$ and M$_s^{hard}$). The influences of an in-plane magnetic field (H ip ) and temperature (T) are also studied using a L1 0 -FePt/A1-FePt bilayer sample. Comparing the PNR results to the micromagnetic simulations reveals that the interfacial magnetic configuration is highly dependent on t soft , M$_s^{soft}, and the external factors (H ip and T) and has a relatively weak dependence on t hard and M$_s^{hard}$. Key among these results, for thin t soft , the hard and soft layers are rigidly coupled in the out-of-plane direction and then undergo a transition to relax in-plane. This transition can be delayed to larger t soft by decreasing M$_s^{soft}$. Understanding the influence of these parameters on the magnetic configuration is critical to designing functional composite magnets for applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Development of Fast Decay-Energy Spectroscopy With Magnetic Microcalorimeters

Decay energy spectroscopy (DES) is an increasingly important radiometric technique arising from the unique thermal detection physics and the precision of low-temperature microcalorimetry. DES can enable high-precision analysis of very small amounts of radioactive material with simple and rapid sample preparation, making it a key new tool for nuclear safeguards, nuclear forensics, the improvement of nuclear data, measurements of absolute activity, and other applications. For problems in nuclear safeguards and nuclear forensics it is highly desirable to increase the count rates achievable in DES, while maintaining simple and rapid sample preparation. Here, in this report, we describe progress in a new project to achieve high count rates in DES by taking advantage of the physics of magnetic microcalorimetry. We describe the results of initial modeling and experiment to validate the idea, a sample fabrication technique suitable for nuclear materials laboratories, the preparation and initial tests of paramagnetic Au-Er alloy in thin foil form, and the development of a sensing coil geometry that will perform well with the increased-thickness sensor used in the new technique.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1975

Photoconductivity of high voltage space insulating materials: Measurements with metal electrodes

The electrical conductivities of high voltage insulating materials were measured in the dark and under various intensities of illumination. The materials investigated included FEP Teflon, Kapton-H, fused quartz, and parylene. Conductivities were determined as functions of temperature between 22 and 100 C and light intensity between 0 and 2.5 kW/m2. The thickness dependence of the conductivity was determined for Teflon and Kapton, and the influence of spectral wavelengths on the conductivity was determined in several cases. All measurements were made in a vacuum to simulate a space environment, and all samples had metallic electrodes. The conductivity of Kapton was permanently increased by exposure to light; changes as great as five orders of magnitude were observed after six hours of illumination.

Coffey, H. T.↗
NASA NTRS1990

Geometry of premixed flames in three-dimensional turbulence

Constant density premixed flame propagation in three dimensional Navier-Stokes turbulence has been simulated. The zero-thickness flame model of Kerstein has been used. There are two aspects to this study: (1) adjustment of the large-scale strain rate in order to achieve a constant energy system; and (2) determination of flame curvature. The sampled distribution of curvature indicates that in most cases the flame has a cylindrical shape, with one curvature at least three times larger than the other. This implies that realistic chemical reactions in a flame-vortex interaction may be simulated in two dimensions.

Ashurst, William T.↗
NASA NTRS2005

Global Retrieval of Aerosol Properties over Desert and Semi-Desert Regions from SeaWiFS and MODIS

Mineral aerosols (dust) play an important role in both climate forcing and oceanic productivity throughout the entire year. Due to the relatively short lifetime (a few hours to about a week), the distributions of these airborne dust particles vary extensively in both space and time. Consequently, satellite observations are needed over both source and sink regions for continuous temporal and spatial sampling of dust properties. However, despite their importance, the high spatial resolution satellite measurements of dust near its source have been lacking. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol optical thickness and single scattering albedo over bright-reflecting surfaces such as urban areas and deserts. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. The new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as SeaWiFS and MODIS to infer the properties of aerosols, sinre the stirfare reflectance nver land in the blue part of the spectrum is much lower than for longer wavelength channels. We have validated the satellite retrieved aerosol optical thickness with data from AERONET sunphotometers over desert and semi-desert regions. The comparisons show reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from SeaWiFS and MODIS-like instruments.

Hsu, Nai-Yung↗
NASA NTRS2007

Three Way Comparison between Two OMI/Aura and One POLDER/PARASOL Cloud Pressure Products

The cloud pressures determined by three different algorithms, operating on reflectances measured by two space-borne instruments in the "A" train, are compared with each other. The retrieval algorithms are based on absorption in the oxygen A-band near 760 nm, absorption by a collision induced absorption in oxygen near 477nm, and the filling in of Fraunhofer lines by rotational Raman scattering. The first algorithm operates on data collected by the POLDER instrument on board PARASOL, while the latter two operate on data from the OMI instrument on board Aura. The satellites sample the same air mass within about 15 minutes. Using one month of data, the cloud pressures from the three algorithms are found to show a similar behavior, with correlation coefficients larger than 0.85 between the data sets for thick clouds. The average differences in the cloud pressure are also small, between 2 and 45 hPa, for the whole data set. For optically thin to medium thick clouds, the cloud pressure the distribution found by POLDER is very similar to that found by OMI using the O2 - O2 absorption. Somewhat larger differences are found for very thick clouds, and we hypothesise that the strong absorption in the oxygen A-band causes the POLDER instrument to retrieve lower pressures for those scenes.

Sneep, M.↗
NASA NTRS2006

NASA Tech Briefs, August 2006

Topics covered include: Measurement and Controls Data Acquisition System IMU/GPS System Provides Position and Attitude Data Using Artificial Intelligence to Inform Pilots of Weather Fast Lossless Compression of Multispectral-Image Data Developing Signal-Pattern-Recognition Programs Implementing Access to Data Distributed on Many Processors Compact, Efficient Drive Circuit for a Piezoelectric Pump; Dual Common Planes for Time Multiplexing of Dual-Color QWIPs; MMIC Power Amplifier Puts Out 40 mW From 75 to 110 GHz; 2D/3D Visual Tracker for Rover Mast; Adding Hierarchical Objects to Relational Database General-Purpose XML-Based Information Managements; Vaporizable Scaffolds for Fabricating Thermoelectric Modules; Producing Quantum Dots by Spray Pyrolysis; Mobile Robot for Exploring Cold Liquid/Solid Environments; System Would Acquire Core and Powder Samples of Rocks; Improved Fabrication of Lithium Films Having Micron Features; Manufacture of Regularly Shaped Sol-Gel Pellets; Regulating Glucose and pH, and Monitoring Oxygen in a Bioreactor; Satellite Multiangle Spectropolarimetric Imaging of Aerosols; Interferometric System for Measuring Thickness of Sea Ice; Microscale Regenerative Heat Exchanger Protocols for Handling Messages Between Simulation Computers Statistical Detection of Atypical Aircraft Flights NASA's Aviation Safety and Modeling Project Multimode-Guided-Wave Ultrasonic Scanning of Materials Algorithms for Maneuvering Spacecraft Around Small Bodies Improved Solar-Radiation-Pressure Models for GPS Satellites Measuring Attitude of a Large, Flexible, Orbiting Structure

Source record↗
NASA NTRS2012

Three Dimensionally Interlinked, Dense, Solid Form of Single-Walled CNT Ropes

A 3D networked, dense form of single-walled carbon nanotubes (SWNT) has been made through isotropic shrinking of a gel-like SWNT-water paste by very slow evaporation. Approximately 35 g of Raw HiPco nanotubes were cleaned by the method of soft baking (250 C for 15 hours in air saturated with water vapor) in a glass beaker followed by leaching with concentrated hydrochloric acid. Typically, one liter of concentrated hydrochloric acid was added to the soft-baked voluminous mass in the same large beaker, and allowed to digest at room temperature with stirring overnight. The acid-digested SWNT slurry was filtered through a large porcelain Buchner funnel under atmospheric pressure. The slurry was continuously flushed, while still in the funnel, with a very slow but steady stream of deionized water employing a peristaltic pump. This process, referred to as gwashing, h continued until the filtrate water dripping from the Buchner funnel was clear, colorless, and neutral to a pH paper. This took about 15 liters of water to flow through the slurry over a day. At this point, the water pump was stopped and the SWNT-water slurry was allowed to drain the excess water for about 10 hours. The resulting thick paste of SWNT-neutral water was transferred to a beaker. The beaker was covered with aluminum foil with few holes and allowed to dry very slowly in a hood at room temperature. In about eight weeks, the sample gradually dried isotropically to a cylindrical dense mass referred to as a carbon nanotube block (CNB). There was no carbonaceous matter sticking to any of the glass surface where the SWNT-water paste made contact. The approximate dimensions of the cylindrical SWNT block that weighed 28 g were 1.5 in. (.3.8 cm) in diameter and 1.25 in. (.3.2 cm) in height. The bottom portion of the cylinder that was in contact with the beaker surface was slightly wider, indicating some resistance to shrinking. The cylindrical mass also consisted of several pores. The cylindrical mass was very tough and could not be broken with a small hammer using considerable force. The mass of the solid could be polished over a fine grain emery paper or even a smooth, stainless steel surface indicative of alignment at finer levels.

Smalley, Richard E.↗
DOE OSTI2024

Investigation of properties of CdSeTe/Sb and Sb/CdSeTe stacks

The effect of Sb inclusion in CdSeTe thin films was examined. CdSeTe alloys were grown by co-evaporation, either on 5 nm thick electron-beam evaporated Sb layers (Sb/CdSeTe) or coated with Sb post-deposition (CdSeTe/Sb). Sb inclusion improved CdSeTe grain structure, a critical factor for device performance, with average grain size increasing from 0.6 to 1.5 μm. All samples crystallized on annealing to the cubic structure, with a change in film orientation from (111) to random or (220). The presence of Sb in CdSeTe/Sb or Sb/CdSeTe samples, however, had a limited effect on the carrier concentration compared to Sb-free samples. Time resolved photoluminescence showed Sb inclusion increased decay lifetimes, with τ1 = 0.8 ns for and τ2 = 6.9 ns for the Sb/CdSeTe sample.

14 SOLAR ENERGY↗