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NASA NTRS1982

Structural features of conducting quasi-one-dimensional organic halides and pseudohalides

The physical properties of quasi-one-dimensional conductors are profoundly influenced by slight changes in structure. The unusual structural features of this class of materials include only short range order of the anions and structure modulation. The nature of disorder and structure modulation can affect the character of the metal-to-insulator transition at low temperature, and may allow us to make some predictions of low temperature behavior based on room temperature structural properties.

Williams, R.↗

NASA NTRS2015

Experimentally Shocked and Altered Basalt: Laboratory Analogs for Calibration of Mars Remote Sensing and In Situ Data

Calcium phosphate (likely chloroapatite) is formed in the alteration experiments and is more abundant in the altered and shocked sample probably due to increased surface area exposed to alteration fluids resulting from shock damage in the form of both brittle and structural deformation to the starting material (Figs 1 & 3). Apatite forms in basic conditions so the closed system alteration experiment must be buffered by the basalt starting material to create a fluid chemistry environment evolving from neutral at the start to alkaline after 21 days at 160 degrees Centigrade. Plagioclase feldspar in the unshocked sample (Fig. 2) has undergone a solid-state transformation to maskelynite, a disordered phase that is not manifest in the X-ray diffraction pattern of the shocked sample (Fig.4). Olivine and ulvospinel that are present in the starting material can be detected by X-ray diffraction in the shocked and altered sample (Fig. 4). Tungsten from the sample holder used in the shock experiments dominates the X-ray diffraction pattern of the shocked and altered sample (Fig. 4). Samples were weighed after the alteration experiments to determine mass loss and predict the amount of material available for the planned analyses from the shock experiments. Within the constraints of these experiments, mass loss is negligible. The samples will next be characterized by Moessbauer and Vis-Near Infrared spectroscopy, the results of which will be compared to the Mars Exploration Rovers and Mars Reconnaissance Orbiter data sets respectively.

Bell, M. S.↗

NASA NTRS2010

Different Perspectives on Asthenia in Astronauts and Cosmonauts: International Research Literature

The Behavioral Health and Performance (BHP) Element is one of the six elements within the NASA Human Research Program (HRP) and is responsible for managing four risks: a) The Risk of Performance Decrements due to inadequate Cooperation, Coordination, Communication and Psychological Adaptation within a Team (Team), b) the Risk of Performance Errors due to Sleep Loss, Circadian De-synchronization, Fatigue and Work Overload (Sleep), c) Risk of Behavioral Conditions (BMed), and d) the Risk of Psychiatric Disorders (BMed). The aim of this report is to address some of the recommendations made by the recent NASA HRP Standing Review Panel for the Behavioral Medicine Risk of Psychiatric Disorders. Such recommendations included: a) the inclusion of important national and international literature in English and non-English language materials; including journals, books, magazines, conference reports and b) an extensive literature review of certain types of psychological states to predict, detect, and assess adverse mental states that may negatively affect the psychological well being of the astronauts, specifically asthenia. This report was a collaborative international work effort focused on the evaluation and determination of the importance of continuing research on asthenia as a possible psychological problem that might affect the optimal psychological functioning among crewmembers during long-duration space flight missions. Russian medical personnel (flight surgeons and psychologist) have observed symptoms of asthenia (weakness, increased fatigue, irritability, and attention and memory disorders) in cosmonauts after four months in space (Myasnikov& Zamaleddinov1996; Grigorieve, 1996 ) and believe that asthenia is one of the greater risks that will affect crews? optimal psychological functioning.

Sandoval, Luis↗

NASA NTRS1971

Cation disorder in shocked orthopyroxene.

The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

Dundon, R. W.↗

NASA NTRS1998

Summary of Research Report

Ten papers, published in various publications, on buckling, and the effects of imperfections on various structures are presented. These papers are: (1) Buckling mode localization in elastic plates due to misplacement in the stiffner location; (2) On vibrational imperfection sensitivity on Augusti's model structure in the vicinity of a non-linear static state; (3) Imperfection sensitivity due to elastic moduli in the Roorda Koiter frame; (4) Buckling mode localization in a multi-span periodic structure with a disorder in a single span; (5) Prediction of natural frequency and buckling load variability due to uncertainty in material properties by convex modeling; (6) Derivation of multi-dimensional ellipsoidal convex model for experimental data; (7) Passive control of buckling deformation via Anderson localization phenomenon; (8)Effect of the thickness and initial im perfection on buckling on composite cylindrical shells: asymptotic analysis and numerical results by BOSOR4 and PANDA2; (9) Worst case estimation of homology design by convex analysis; (10) Buckling of structures with uncertain imperfections - Personal perspective.

Elishakoff, Isaac↗

NASA NTRS2004

Transplanting Retinal Cells using Bucky Paper for Support

A novel treatment for retinal degenerative disorders involving transplantation of cells into the eye is currently under development at NASA Ames Research Center and Stanford University School of Medicine. The technique uses bucky paper as a support material for retinal pigment epithelial (RPE) cells, iris pigment epithelial (IPE) cells, and/or stem cells. This technology is envisioned as a treatment for age-related macular degeneration, which is the leading cause of blindness in persons over age 65 in Western nations. Additionally, patients with other retinal degenerative disorders, such as retinitis pigmentosa, may be treated by this strategy. Bucky paper is a mesh of carbon nanotubes (CNTs), as shown in Figure 1, that can be made from any of the commercial sources of CNTs. Bucky paper is biocompatible and capable of supporting the growth of biological cells. Because bucky paper is highly porous, nutrients, oxygen, carbon dioxide, and waste can readily diffuse through it. The thickness, density, and porosity of bucky paper can be tailored in manufacturing. For transplantation of cells into the retina, bucky paper serves simultaneously as a substrate for cell growth and as a barrier for new blood vessel formation, which can be a problem in the exudative type of macular degeneration. Bucky paper is easily handled during surgical implantation into the eye. Through appropriate choice of manufacturing processes, bucky paper can be made relatively rigid yet able to conform to the retina when the bucky paper is implanted. Bucky paper offers a distinct advantage over other materials that have been investigated for retinal cell transplantation - lens capsule and Descemet's membrane - which are difficult to handle during surgery because they are flimsy and do not stay flat.

Loftus, David J.↗

NASA NTRS1987

Hisingerite and iddingsite on Mars: Degradation of iron-rich basalts

Paragenetic evidence that indicates that hisingerite may have formed during the evolution of Martian regolith is summarized. Hisingerite was once regarded as poorly crystalline iron-rich smectite or nontronite. However, recent electron microscopy and X-ray studies have revealed hisingerite to have an amorphous or gel structure containing a disordered array of (FeO6) octahedra and (SiO4) tetrahedra. It is just this coordination environment and degree of crystallinity that matches materials simulating the spectral properties of the bright regions of Mars. Therefore, hisingerite and basic ferric sulfate minerals appear to be major contributers to remote sensed reflectance spectral profiles of Mars.

Burns, Roger G.↗

NASA NTRS1998

Noninvasive Medical Diagnostics & Treatment Using Ultrasonics

In parallel to the industrial application of NDE to flaw detection and material property determination, the medical community has succesfully adapted such methods to the noninvasaive diagnostics and treatment of many conditions and disorders of the human body.

NDE noninvasive diagnostics destruction of blood c↗

NASA NTRS2004

Disordered Zinc in Zn4Sb3 with Phonon-Glass and Electron-Crystal Thermoelectric Properties

By converting waste heat into electricity, thermoelectric generators could be an important part of the solution to today's energy challenges. The compound Zn4Sb3 is one of the most efficient thermoelectric materials known. Its high efficiency results from an extraordinarily low thermal conductivity in conjunction with the electronic structure of a heavily doped semiconductor. Previous structural studies have been unable to explain this unusual combination of properties. Here, we show through a comprehensive structural analysis using single-crystal X-ray and powder-synchrotron-radiation diffraction methods, that both the electronic and thermal properties of Zn4Sb3 can be understood in terms of unique structural features that have been previously overlooked. The identification of Sb3- ions and Sb-2(4-) dimers reveals that Zn4Sb3 is a valence semiconductor with the ideal stoichiometry Zn13Sb10. In addition, the structure contains significant disorder, with zinc atoms distributed over multiple positions. The discovery of glass-like interstitial sites uncovers a highly effective mechanism for reducing thermal conductivity. Thus Zn4Sb3 is in many ways an ideal 'phonon glass, electron crystal' thermoelectric material.

phases↗

NASA NTRS1999

Exploring the Effects of Dust Coatings and Shock Pressures on Thermal Infrared Spectra

Dust coatings on rocks obscured the underlying rock surfaces at the Mars Pathfinder landing site and made it difficult to obtain pristine visible/near-infrared reflectance spectra and chemical measurements. Such dust coatings also affect the ability of thermal infrared (TIR) spectra (such as that provided by TES and future lander (mini-TES) and orbiter multispectral imaging systems (THEMIS) to reveal accurately the mineralogy of rocks and soils. Similarly, high shock pressures from impact events cause crystalline disorder in important minerals such as pyroxene and feldspar that also affects their TIR spectra and complicates spectral interpretation of shocked impact materials. Additional information is contained in the original extended abstract.

Johnson, J. R.↗

NASA NTRS1988

Ballistic transport in II-VI semiconductor compounds and alloys

Realistic band structures are used in calculating the group velocity and scattering rates for electrons with injection energies up to 1 eV in ZnTe, CdTe, and the low-effective-mass alloy Hg(0.7)Cd(0.3)Te. Scattering from longitudinal optical phonons, ionized impurities, and alloy disorder have been included in the full band-structure calculation, which automatically includes both intra- and intervalley scattering. Of the II-VI materials considered, at 77 K HgCdTe is superior for low injection energies (up to 0.25 eV) while CdTe is superior at higher injection energies (1 eV) at room temperature. The attainable mean free paths (equal to or greater than 1000 A) and group velocities (equal to or greater than 10 to the 8th cm/s) for both systems are comparable to values found in III-V systems.

Berding, M. A.↗

NASA NTRS1990

Cell Model Of A Disordered Solid

Elastic properties predicted from first principles. Paper discusses generalization of cell theory of disordered (non-crystaline) solid to include anisotropic stresses. Study part of continuing effort to understand macroscopic stress-and-strain properties of solid materials in terms of microscopic physical phenomena. Emphasis on derivation, from first principles, of bulk, shear, and Young's moduli of glassy material at zero absolute temperature.

Peng, Steven T. J.↗

NASA NTRS1993

Alkaline Earth Core Level Photoemission Spectroscopy of High-Temperature Superconductors

This paper examines photoemission measurements of the alkaline Earth core levels of high-temperature superconductors and related materials, models that seek to explain the large negative shifts observed relative to the corresponding alkaline Earth metals, and the effect of lattice site disorder on the core level spectra and the presence or absence of intrinsic surface peaks.

superconductors Earth core photoemission↗

NASA NTRS2004

Open-Source Software for Modeling of Nanoelectronic Devices

The Nanoelectronic Modeling 3-D (NEMO 3-D) computer program has been upgraded to open-source status through elimination of license-restricted components. The present version functions equivalently to the version reported in "Software for Numerical Modeling of Nanoelectronic Devices" (NPO-30520), NASA Tech Briefs, Vol. 27, No. 11 (November 2003), page 37. To recapitulate: NEMO 3-D performs numerical modeling of the electronic transport and structural properties of a semiconductor device that has overall dimensions of the order of tens of nanometers. The underlying mathematical model represents the quantum-mechanical behavior of the device resolved to the atomistic level of granularity. NEMO 3-D solves the applicable quantum matrix equation on a Beowulf-class cluster computer by use of a parallel-processing matrix vector multiplication algorithm coupled to a Lanczos and/or Rayleigh-Ritz algorithm that solves for eigenvalues. A prior upgrade of NEMO 3-D incorporated a capability for a strain treatment, parameterized for bulk material properties of GaAs and InAs, for two tight-binding submodels. NEMO 3-D has been demonstrated in atomistic analyses of effects of disorder in alloys and, in particular, in bulk In(x)Ga(1-x)As and in In(0.6)Ga(0.4)As quantum dots.

Oyafuso, Fabiano↗

NASA NTRS2015

Microstructural Influence on Deformation and Fatigue Life of Composites Using the Generalized Method of Cells

A fully coupled deformation and damage approach to modeling the response of composite materials and composite laminates is presented. It is based on the semi-‐analytical generalized method of cells (GMC) micromechanics model as well as its higher fidelity counterpart, HFGMC, both of which provide closed-form constitutive equations for composite materials as well as the micro scale stress and strain fields in the composite phases. The provided constitutive equations allow GMC and HFGMC to function within a higher scale structural analysis (e.g., finite element analysis or lamination theory) to represent a composite material point, while the availability of the micro fields allow the incorporation of lower scale sub‐models to represent local phenomena in the fiber and matrix. Further, GMC's formulation performs averaging when applying certain governing equations such that some degree of microscale field accuracy is surrendered in favor of extreme computational efficiency, rendering the method quite attractive as the centerpiece in a integrated computational material engineering (ICME) structural analysis; whereas HFGMC retains this microscale field accuracy, but at the price of significantly slower computational speed. Herein, the sensitivity of deformation and the fatigue life of graphite/epoxy PMC composites, with both ordered and disordered microstructures, has been investigated using this coupled deformation and damage micromechanics based approach. The local effects of fiber breakage and fatigue damage are included as sub‐models that operate on the microscale for the individual composite phases. For analysis of laminates, classical lamination theory is employed as the global or structural scale model, while GMC/HFGMC is embedded to operate on the microscale to simulate the behavior of the composite material within each laminate layer. A key outcome of this study is the statistical influence of microstructure and micromechanics idealization (GMC or HFGMC) on the overall accuracy of unidirectional and laminated composite deformation and fatigue response.

Microscale Models↗

NASA NTRS2016

Levitation Technology in International Space Station Research

The International Space Station (ISS) is a unique multidisciplinary orbiting laboratory for science and technology research, enabling discoveries that benefit life on Earth and exploration of the universe. ISS facilities for containerless sample processing in Materials Science experiments include levitation devices with specimen positioning control while reducing containment vessel contamination. For example, ESA's EML (ElectroMagnetic Levitator), is used for melting and solidification of conductive metals, alloys, or semiconductors in ultra-high vacuum, or in high-purity gaseous atmospheres. Sample heating and positioning are accomplished through electromagnetic fields generated by a coil system. EML applications cover investigation of solidification and microstructural formation, evaluation of thermophysical properties of highly reactive metals (whose properties can be very sensitive to contamination), and examination of undercooled liquid metals to understand metastable phase convection and influence convection on structural changes. MSL utilization includes development of novel light-weight, high-performance materials. Another facility, JAXA's ELF (Electrostatic Levitation Furnace), is used to perform high temperature melting while avoiding chemical reactions with crucibles by levitating a sample through Coulomb force. ELF is capable of measuring density, surface tension, and viscosity of samples at high temperatures. One of the initial ELF investigations, Interfacial Energy-1, is aimed at clarification of interfacial phenomena between molten steels and oxide melts with industrial applications in control processes for liquid mixing. In addition to these Materials Science facilities, other ISS investigations that involve levitation employ it for biological research. For example, NASA's "Magnetic 3D Culturing and Bioprinting" investigation uses magnetic levitation for three-dimensional culturing and positioning of magnetized cells to generate spheroid assemblies for biomedical applications. Levitation is also used as a modeled microgravity ground analog in the NASA OsteoOmics ISS investigation, which tests whether magnetic levitation accurately simulates microgravity conditions by studying gravitational regulation of osteoblast and osteoclast genomics and metabolism. Elucidating the cellular mechanisms of bone loss in microgravity contributes to the understanding of bone loss in medical disorders on Earth, which may lead to development of preventive or therapeutic countermeasures. Thus, the ISS state-of-the-art laboratory offers various levitation capability platforms with applications for innovative research in Materials and Life Sciences disciplines, with benefits for humanity.

Guinart-Ramirez, Y.↗

NASA NTRS1980

Physical characteristics of cometary dust from optical studies

Observations of the sunlight scattered and thermal emission from cometary dust, which may be used to infer the physical properties of the dust grains, are reviewed. Consideration is given to the observed wavelength dependence of the scattered light from cometary coma and tails, the average scattering function of the dust grains, the average grain Bond albedo, the polarization of the scattered light, and grain temperatures deduced from thermal infrared emission. The thermal properties of dust grains are illustrated for models based on magnetite or olivine grain materials, with consideration given to the variation of thermal properties with particle radius and heliocentric distance. Comparison of the models with observations indicates that a disordered or amorphous olivine composition can give a reasonable fit to the data for appropriate grain sizes and temperatures. The observations acquired are noted to indicate an optically important particle size of 1 micron, with silicate particles not larger than a few microns usually present although pure silicate grains can not be responsible for the thermal emission, and the cometary dust grains are most likely not spherical. Further observations needed in the infrared are indicated.

Hanner, M. S.↗

NASA NTRS2004

Lunar and Planetary Science XXXV: Meteorites: Experiments and Spectroscopy

The session "Meteorites: Experiments and Spectroscopy" included the following reports:The Suitability of Laser Induced Breakdown Spectroscopy for Determining the Compositions of Extraterrestrial Material; Deconvolving Terrestrial Alteration Mineral Spectral Signatures from Meteorite Reflectance Measurements; Impacts of Ions and Micrometeorites on Mineral Surfaces: Reflectance and Chemical Changes Found in Ordinary Chondrites; FT-IR Micro-spectroscopy of Fine-grained Planetary Materials: Further Results; Effusion Cell Measurements of the Vapor Pressure of Cobalt at Temperatures up to 2000K: Comparisons with Iron and Nickel; Kinetics of Fe2+-Mg Order-Disorder in P21/c Pigeonite: Implications for Cooling Rates Calculations; Compressional and Shear Wave Velocities in Meteorites; Chemical and Mineralogical Size Segregation in the Impact Disruption of Anhydrous Stone Meteorites; and Shock Pressures of Impacts vs. Crystallization Pressures of Shock-induced Melt Veins of the chondrites.

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