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Sample records for grain eesti abistab

  1. Grain boundaries

    SciTech Connect

    Balluffi, R.W.; Bristowe, P.D.

    1991-01-01

    The present document is a progress report describing the work accomplished to date during the second year of our four-year grant (February 15, 1990--February 14, 1994) to study grain boundaries. The research was focused on the following three major efforts: Study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; study of short-circuit diffusion along grain boundaries; and development of a Thin-film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  2. Cometary grains

    NASA Technical Reports Server (NTRS)

    Baum, William A.; Kreidl, Tobias J.; Schleicher, David G.

    1992-01-01

    CCD observations of cometary comas in the spectral continuum are reported. Radial brightness profiles of 14 comets and isophotal maps of three are presented. For 10 of the 14, the azimuthally averaged brightness in the vicinity of the nucleus falls off faster than rho exp -1, where rho is the projected radial distance from the nucleus in the plane of the sky. Simple modeling is used to show that radiation pressure alone cannot account for the observed departures from rho exp -1; it is postulated that the grains fade, i.e., decrease in albedo or size, while they glow outward. For only three of the comets no evidence was found of any grain fading at all. Cases with the most rapid grain fading occurred at small heliocentric distances, but so did some of the cases with no fading, from which large intrinsic differences from comet to comet in the nature of the grain population are inferred.

  3. Interstellar grains

    NASA Technical Reports Server (NTRS)

    Snow, T. P.

    1986-01-01

    There are few aspects of interstellar grains that can be unambiguously defined. Very little can be said that is independent of models or presuppositions; hence issues are raised and questions categorized, rather than providing definitive answers. The questions are issues fall into three general areas; the general physical and chemical nature of the grains; the processes by which they are formed and destroyed; and future observational approaches.

  4. Interstellar grains within interstellar grains

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Amari, Sachiko; Zinner, Ernst K.; Lewis, Roy S.

    1991-01-01

    Five interstellar graphite spherules extracted from the Murchison carbonaceous meteorite are studied. The isotopic and elemental compositions of individual particles are investigated with the help of an ion microprobe, and this analysis is augmented with structural studies of ultrathin sections of the grain interiors by transmission electron microscopy. As a result, the following procedure for the formation of the interstellar graphite spherule bearing TiC crystals is inferred: (1) high-temperature nucleation and rapid growth of the graphitic carbon spherule in the atmosphere of a carbon-rich star, (2) nucleation and growth of TiC crystals during continued growth of the graphitic spherule and the accretion of TiC onto the spherule, (3) quenching of the graphite growth process by depletion of C or by isolation of the spherule before other grain types could condense.

  5. Whole Grains and Fiber

    MedlinePlus

    ... fiber. Some examples of refined grains are wheat flour, enriched bread and white rice. Most refined grains are enriched , which means that ... grains. Some examples of enriched grains are wheat flour, enriched bread and white rice. Eating whole grains provides important health benefits: Many ...

  6. Grain Handling and Storage.

    ERIC Educational Resources Information Center

    Harris, Troy G.; Minor, John

    This text for a secondary- or postecondary-level course in grain handling and storage contains ten chapters. Chapter titles are (1) Introduction to Grain Handling and Storage, (2) Elevator Safety, (3) Grain Grading and Seed Identification, (4) Moisture Control, (5) Insect and Rodent Control, (6) Grain Inventory Control, (7) Elevator Maintenance,…

  7. Grain Grading and Handling.

    ERIC Educational Resources Information Center

    Rendleman, Matt; Legacy, James

    This publication provides an introduction to grain grading and handling for adult students in vocational and technical education programs. Organized in five chapters, the booklet provides a brief overview of the jobs performed at a grain elevator and of the techniques used to grade grain. The first chapter introduces the grain industry and…

  8. Marketing Farm Grain Crops.

    ERIC Educational Resources Information Center

    Ridenour, Harlan E.

    This vocational agriculture curriculum on grain marketing contains three parts: teacher guide, student manual, and student workbook. All three are coordinated and cross-referenced. The course is designed to give students of grain marketing a thorough background in the subject and provide practical help in developing grain marketing strategies for…

  9. Origins of GEMS Grains

    NASA Technical Reports Server (NTRS)

    Messenger, S.; Walker, R. M.

    2012-01-01

    Interplanetary dust particles (IDPs) collected in the Earth s stratosphere contain high abundances of submicrometer amorphous silicates known as GEMS grains. From their birth as condensates in the outflows of oxygen-rich evolved stars, processing in interstellar space, and incorporation into disks around new stars, amorphous silicates predominate in most astrophysical environments. Amorphous silicates were a major building block of our Solar System and are prominent in infrared spectra of comets. Anhydrous interplanetary dust particles (IDPs) thought to derive from comets contain abundant amorphous silicates known as GEMS (glass with embedded metal and sulfides) grains. GEMS grains have been proposed to be isotopically and chemically homogenized interstellar amorphous silicate dust. We evaluated this hypothesis through coordinated chemical and isotopic analyses of GEMS grains in a suite of IDPs to constrain their origins. GEMS grains show order of magnitude variations in Mg, Fe, Ca, and S abundances. GEMS grains do not match the average element abundances inferred for ISM dust containing on average, too little Mg, Fe, and Ca, and too much S. GEMS grains have complementary compositions to the crystalline components in IDPs suggesting that they formed from the same reservoir. We did not observe any unequivocal microstructural or chemical evidence that GEMS grains experienced prolonged exposure to radiation. We identified four GEMS grains having O isotopic compositions that point to origins in red giant branch or asymptotic giant branch stars and supernovae. Based on their O isotopic compositions, we estimate that 1-6% of GEMS grains are surviving circumstellar grains. The remaining 94-99% of GEMS grains have O isotopic compositions that are indistinguishable from terrestrial materials and carbonaceous chondrites. These isotopically solar GEMS grains either formed in the Solar System or were completely homogenized in the interstellar medium (ISM). However, the

  10. Interstellar Dust Grain Alignment

    NASA Astrophysics Data System (ADS)

    Andersson, B.-G.; Lazarian, A.; Vaillancourt, John E.

    2015-08-01

    Interstellar polarization at optical-to-infrared wavelengths is known to arise from asymmetric dust grains aligned with the magnetic field. This effect provides a potentially powerful probe of magnetic field structure and strength if the details of the grain alignment can be reliably understood. Theory and observations have recently converged on a quantitative, predictive description of interstellar grain alignment based on radiative processes. The development of a general, analytical model for this radiative alignment torque (RAT) theory has allowed specific, testable predictions for realistic interstellar conditions. We outline the theoretical and observational arguments in favor of RAT alignment, as well as reasons the "classical" paramagnetic alignment mechanism is unlikely to work, except possibly for the very smallest grains. With further detailed characterization of the RAT mechanism, grain alignment and polarimetry promise to not only better constrain the interstellar magnetic field but also provide new information on the dust characteristics.

  11. Folding of Pollen Grains

    NASA Astrophysics Data System (ADS)

    Katifori, Eleni; Alben, Silas; Cerda, Enrique; Nelson, David; Dumais, Jacques

    2008-03-01

    At dehiscence, which occurs when the anther reaches maturity and opens, pollen grains dehydrate and their volume is reduced. The pollen wall deforms to accommodate the volume loss, and the deformation pathway depends on the initial turgid pollen grain geometry and the mechanical properties of the pollen wall. We demonstrate, using both experimental and theoretical approaches, that the design of the apertures (areas on the pollen wall where the stretching and the bending modulus are reduced) is critical for controlling the folding pattern, and ensures the pollen grain viability. An excellent fit to the experiments is obtained using a discretized version of the theory of thin elastic shells.

  12. Convection in grain refining

    NASA Technical Reports Server (NTRS)

    Flemings, M. C.; Szekely, J.

    1982-01-01

    The relationship between fluid flow phenomena, nucleation, and grain refinement in solidifying metals both in the presence and in the absence of a gravitational field was investigated. The reduction of grain size in hard-to-process melts; the effects of undercooling on structure in solidification processes, including rapid solidification processing; and control of this undercooling to improve structures of solidified melts are considered. Grain refining and supercooling thermal modeling of the solidification process, and heat and fluid flow phenomena in the levitated metal droplets are described.

  13. Kansas Agents Study Grain Marketing

    ERIC Educational Resources Information Center

    Schoeff, Robert W.

    1973-01-01

    Author is an extension specialist in feed and grain marketing for Kansas State University. He describes a tour set up to educate members of the Kansas Grain and Feed Dealers' Association in the area of grain marketing and exporting. (GB)

  14. Relict grains in chondrules

    NASA Technical Reports Server (NTRS)

    Rambaldi, E. R.

    1981-01-01

    Attention is given to the fact that a significant fraction of the chondrules from ordinary chondrites contain silicate grains that survived the chondrule formation process without melting. Typically, these grains consist of coarse olivine, rarely orthopyroxene, crystals located in the core of chondrules and displaying a zoning that is inconsistent with crystallization from a silicate melt. It is noted that the relict grains still preserve the imprint of processes that occurred in the solar nebula and, in some cases, may include the isotopic record of interstellar grains. Information is presented on the chondrule precursor materials and the process of chondrule formation which was acquired by a compositional and textural study of three of the most unequilibrated type 3 ordinary chondrites.

  15. Grains in galactic haloes.

    NASA Astrophysics Data System (ADS)

    Ferrara, A.; Barsella, B.; Ferrini, F.; Greenberg, J. M.; Aiello, S.

    1989-12-01

    The authors considered the effect of extensive forces on dust grains subjected to the light and matter distribution of the spiral galaxy NGC 3198. They have shown that the combined force on a small particle located above the plane of a galactic disk may be either attractive or repulsive depending on a variety of parameters. The authors present here the preliminary results of the study of the motion of a dust grain for NGC 3198.

  16. Fingering phenomena during grain-grain displacement

    NASA Astrophysics Data System (ADS)

    Mello, Nathália M. P.; Paiva, Humberto A.; Combe, G.; Atman, A. P. F.

    2016-05-01

    Spontaneous formation of fingered patterns during the displacement of dense granular assemblies was experimentally reported few years ago, in a radial Hele-Shaw cell. Here, by means of discrete element simulations, we have recovered the experimental findings and extended the original study to explore the control parameters space. In particular, using assemblies of grains with different geometries (monodisperse, bidisperse, or polydisperse), we measured the macroscopic stress tensor in the samples in order to confirm some conjectures proposed in analogy with Saffman-Taylor viscous fingering phenomena for immiscible fluids. Considering an axial setup which allows to control the discharge of grains and to follow the trajectory and the pressure gradient along the displacing interface, we have applied the Darcy law for laminar flow in fluids in order to measure an "effective viscosity" for each assembly combination, in an attempt to mimic variation of the viscosity ratio between the injected/displaced fluids in the Saffman-Taylor experiment. The results corroborate the analogy with the viscous fluids displacement, with the bidisperse assembly corresponding to the less viscous geometry. But, differently to fluid case, granular fingers only develop for a specific combination of displaced/injected geometries, and we have demonstrated that it is always related with the formation of a force chain network along the finger direction.

  17. Grains in galactic haloes

    NASA Technical Reports Server (NTRS)

    Ferrara, Andrea; Barsella, Bruno; Ferrini, F.; Greenberg, J. Mayo; Aiello, Santi

    1989-01-01

    Researchers considered the effect of extensive forces on dust grains subjected to the light and matter distribution of a spiral galaxy (Greenberg et al. (1987), Ferrini et al. (1987), Barsella et al (1988). Researchers showed that the combined force on a small particle located above the plane of a galactic disk may be either attractive or repulsive depending on a variety of parameters. They found, for example, that graphite grains from 20 nm to 250 nm radius are expelled from a typical galaxy, while silicates and other forms of dielectrics, after initial expulsion, may settle in potential minimum within the halo. They discuss only the statistical behavior of the forces for 17 galaxies whose luminosity and matter distribution in the disk, bulge and halo components are reasonably well known. The preliminary results of the study of the motion of a dust grain for NGC 3198 are given.

  18. Composite circumstellar dust grains

    NASA Astrophysics Data System (ADS)

    Gupta, Ranjan; Vaidya, Dipak B.; Dutta, Rajeshwari

    2016-10-01

    We calculate the absorption efficiencies of composite silicate grains with inclusions of graphite and silicon carbide in the spectral range 5-25 μm. We study the variation in absorption profiles with volume fractions of inclusions. In particular we study the variation in the wavelength of peak absorption at 10 and 18 μm. We also study the variation of the absorption of porous silicate grains. We use the absorption efficiencies to calculate the infrared flux at various dust temperatures and compare with the observed infrared emission flux from the circumstellar dust around some M-type and asymptotic giant branch stars obtained from IRAS and a few stars from Spitzer satellite. We interpret the observed data in terms of the circumstellar dust grain sizes, shape, composition and dust temperature.

  19. Grain quality inspection system

    NASA Technical Reports Server (NTRS)

    Flood, C. A., Jr.; Singletow, D. P.; James, S. N.

    1979-01-01

    A review of grain quality indicators and measurement methods was conducted in order to assess the feasibility of using remote sensing technology to develop a continuous monitoring system for use during grain transfer operations. Most detection methods were found to be too slow or too expensive to be incorporated into the normal inspection procedure of a grain elevator on a continuous basis. Two indicators, moisture content and broken corn and foreign material, show potential for automation and are of an economic value. A microprocessor based system which utilizes commercially available electronic moisture meter was developed and tested. A method for automating BCFM measurement is described. A complete system description is presented along with performance test results.

  20. Charging of interplanetary grains

    NASA Technical Reports Server (NTRS)

    Baragiola, R. A.; Johnson, R. E.; Newcomb, John L.

    1995-01-01

    The objective of this program is to quantify, by laboratory experiments, the charging of ices and other insulators subject to irradiation with electrons, ions and ultraviolet photons and to model special conditions based on the data. The system and conditions to be studied are those relevant for charging of dust in magnetospheric plasmas. The measurements are supplemented by computer simulations of charging or grains under a variety of conditions. Our work for this period involved experiments on water ice, improved models of charging of ice grains for Saturn's E-ring, and the construction of apparatus for electron impact studies and measurements of electron energy distributions.

  1. Radiative Grain Alignment

    NASA Astrophysics Data System (ADS)

    Andersson, B. G.

    2015-12-01

    Polarization due to aligned dust grains was discovered in the interstellar medium more than 60 years ago. A quantitative, observationally well tested theory of the phenomenon has finally emerged in the last decade, promising not only an improved understanding of interstellar magnetic fields, but new tools for studying the dust environments and grain characteristics. This Radiative Alignment Torque (RAT) theory also has many potential applications in solar system physics, including for comet dust characteristics. I will review the main aspects of the theory and the observational tests performed to date, as well as some of the new possibilities for using polarization as a tool to study dust and its environment, with RAT alignment.

  2. Grain optical properties

    NASA Technical Reports Server (NTRS)

    Hanner, Martha

    1988-01-01

    The optical properties of small grains provide the link between the infrared observations presented in Chapter 1 and the dust composition described in Chapter 3. In this session, the optical properties were discussed from the viewpoint of modeling the emission from the dust coma and the scattering in order to draw inference about the dust size distribution and composition. The optical properties are applied to the analysis of the infrared data in several ways, and these different uses should be kept in mind when judging the validity of the methods for applying optical constants to real grains.

  3. Grain boundary curvature and grain growth kinetics with particle pinning

    NASA Astrophysics Data System (ADS)

    Shahandeh, Sina; Militzer, Matthias

    2013-08-01

    Second-phase particles are used extensively in design of polycrystalline materials to control the grain size. According to Zener's theory, a distribution of particles creates a pinning pressure on a moving grain boundary. As a result, a limiting grain size is observed, but the effect of pinning on the detail of grain growth kinetics is less known. The influence of the particles on the microstructure occurs in multiple length scales, established by particle radius and the grain size. In this article, we use a meso-scale phase-field model that simulates grain growth in the presence of a uniform pinning pressure. The curvature of the grain boundary network is measured to determine the driving pressure of grain growth in 2D and 3D systems. It was observed that the grain growth continues, even under conditions where the average driving pressure is smaller than the pinning pressure. The limiting grain size is reached when the maximum of driving pressure distribution in the structure is equal to the pinning pressure. This results in a limiting grain size, larger than the one predicted by conventional models, and further analysis shows consistency with experimental observations. A physical model is proposed for the kinetics of grain growth using parameters based on the curvature analysis of the grain boundaries. This model can describe the simulated grain growth kinetics.

  4. Edible grain legumes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Edible grain legumes including dry bean, dry pea, chickpeas, and lentils, have served as important sources of protein for human diets for thousands of years. In the US, these crops are predominately produced for export markets. The objective of this study was to examine yield gains in these crops ov...

  5. Dust grain charging in a wake of other grains

    SciTech Connect

    Miloch, W. J.; Block, D.

    2012-12-15

    The charging of dust grain in the wake of another grains in sonic and supersonic collisionless plasma flows is studied by numerical simulations. We consider two grains aligned with the flow, as well as dust chains and multiple grain arrangements. It is found that the dust charge depends significantly on the flow speed, distance between the grains, and the grain arrangement. For two and three grains aligned, the charges on downstream grains depend linearly on the flow velocity and intergrain distance. The simulations are carried out with DiP3D, a three dimensional particle-in-cell code with both electrons and ions represented as numerical particles [W. J. Miloch et al., Phys. Plasmas 17, 103703 (2010)].

  6. Grain rotation mediated by grain boundary dislocations in nanocrystalline platinum

    PubMed Central

    Wang, Lihua; Teng, Jiao; Liu, Pan; Hirata, Akihiko; Ma, En; Zhang, Ze; Chen, Mingwei; Han, Xiaodong

    2014-01-01

    Grain rotation is a well-known phenomenon during high (homologous) temperature deformation and recrystallization of polycrystalline materials. In recent years, grain rotation has also been proposed as a plasticity mechanism at low temperatures (for example, room temperature for metals), especially for nanocrystalline grains with diameter d less than ~15 nm. Here, in tensile-loaded Pt thin films under a high-resolution transmission electron microscope, we show that the plasticity mechanism transitions from cross-grain dislocation glide in larger grains (d>6 nm) to a mode of coordinated rotation of multiple grains for grains with d<6 nm. The mechanism underlying the grain rotation is dislocation climb at the grain boundary, rather than grain boundary sliding or diffusional creep. Our atomic-scale images demonstrate directly that the evolution of the misorientation angle between neighbouring grains can be quantitatively accounted for by the change of the Frank–Bilby dislocation content in the grain boundary. PMID:25030380

  7. History of Presolar Grains

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.

    2005-01-01

    Papers on the History of Presolar Grains. This has been a very productive period in which much of the laboratory work conducted in the previous year and during this funding cycle were brought to completion. In the last year we have published or submitted for peer review 4 research papers, 4 review papers, and 11 abstracts in research areas supported under this grant. Brief synopses of the results of the research papers are presented, followed by short summaries of the topics discussed in the review papers. Several areas of research are of course being actively pursued, and the appended list of abstracts gives citations to this ongoing work. In a paper submitted to the Astrophysical Journal, the results of an investigation into the physical conditions in the mass outflows of asymptotic giant branch (AGB) carbon stars that are required for the formation of micron-sized presolar graphite grains, with and without previously formed internal crystals of titanium carbide (TIC) are reported.

  8. FINE GRAIN NUCLEAR EMULSION

    DOEpatents

    Oliver, A.J.

    1962-04-24

    A method of preparing nuclear track emulsions having mean grain sizes less than 0.1 microns is described. The method comprises adding silver nitrate to potassium bromide at a rate at which there is always a constant, critical excess of silver ions. For minimum size grains, the silver ion concentration is maintained at the critical level of about pAg 2.0 to 5.0 during prectpitation, pAg being defined as the negative logarithm of the silver ion concentration. It is preferred to eliminate the excess silver at the conclusion of the precipitation steps. The emulsion is processed by methods in all other respects generally similar to the methods of the prior art. (AEC)

  9. Isotropic Monte Carlo Grain Growth

    2013-04-25

    IMCGG performs Monte Carlo simulations of normal grain growth in metals on a hexagonal grid in two dimensions with periodic boundary conditions. This may be performed with either an isotropic or a misorientation - and incliantion-dependent grain boundary energy.

  10. Storing Peanuts in Grain Bags

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was executed to determine the potential of storing farmers stock peanuts and shelled peanuts for crushing in hermetically sealed grain bags. The objectives of the study were to evaluate equipment for loading and unloading the grain bags, the capacity of the grain bags, and the changes in qu...

  11. Grain-grain interaction in stationary dusty plasma

    SciTech Connect

    Lampe, Martin; Joyce, Glenn

    2015-02-15

    We present a particle-in-cell simulation study of the steady-state interaction between two stationary dust grains in uniform stationary plasma. Both the electrostatic force and the shadowing force on the grains are calculated explicitly. The electrostatic force is always repulsive. For two grains of the same size, the electrostatic force is very nearly equal to the shielded electric field due to a single isolated grain, acting on the charge of the other grain. For two grains of unequal size, the electrostatic force on the smaller grain is smaller than the isolated-grain field, and the force on the larger grain is larger than the isolated-grain field. In all cases, the attractive shadowing force exceeds the repulsive electrostatic force when the grain separation d is greater than an equilibrium separation d{sub 0}. d{sub 0} is found to be between 6λ{sub D} and 9λ{sub D} in all cases. The binding energy is estimated to be between 19 eV and 900 eV for various cases.

  12. Special Grain Boundaries in Ultrafine-Grained Tungsten.

    PubMed

    Dudka, O V; Ksenofontov, V A; Sadanov, E V; Starchenko, I V; Mazilova, T I; Mikhailovskij, I M

    2016-12-01

    Field ion microscopy and computer simulation were used for the study of an atomic structure high-angle grain boundary in hard-drawn ultrafine-grained tungsten wire. These boundaries with special misorientations are beyond the scope of the coincident site lattice model. It was demonstrated that the special non-coincident grain boundaries are the plane-matching boundaries, and rigid-body displacements of adjacent nanograins are normal to the <110> misorientation axis. The vectors of rigid-body translations of grains are described by broad asymmetric statistical distribution. Mathematical modeling showed that special incommensurate boundaries with one grain oriented along the {211} plane have comparatively high cohesive energies. The grain-boundary dislocations ½<110> were revealed and studied at the line of local mismatch of {110} atomic planes of adjacent grains. PMID:27416905

  13. Special Grain Boundaries in Ultrafine-Grained Tungsten

    NASA Astrophysics Data System (ADS)

    Dudka, O. V.; Ksenofontov, V. A.; Sadanov, E. V.; Starchenko, I. V.; Mazilova, T. I.; Mikhailovskij, I. M.

    2016-07-01

    Field ion microscopy and computer simulation were used for the study of an atomic structure high-angle grain boundary in hard-drawn ultrafine-grained tungsten wire. These boundaries with special misorientations are beyond the scope of the coincident site lattice model. It was demonstrated that the special non-coincident grain boundaries are the plane-matching boundaries, and rigid-body displacements of adjacent nanograins are normal to the <110> misorientation axis. The vectors of rigid-body translations of grains are described by broad asymmetric statistical distribution. Mathematical modeling showed that special incommensurate boundaries with one grain oriented along the {211} plane have comparatively high cohesive energies. The grain-boundary dislocations ½<110> were revealed and studied at the line of local mismatch of {110} atomic planes of adjacent grains.

  14. Swash mark and grain flow

    USGS Publications Warehouse

    Sallenger,, Asbury H.

    1981-01-01

    Swash marks composed entirely of coarse sand are commonly found on coarse-sand beaches. These swash marks are 10 to 30 centimeters in width and a few millimeters to one centimeter in height. Previous observations, mostly on finer-sand beaches, indicate swash marks are seldom over a few millimeters in height and are commonly composed of material readily floated by surface tension (e.g., mica flakes and shell fragments). Swash marks composed of coarse sand have both fining seaward and fining with depth trends in grain size. Apparently, the leading margin of a wave upwash drives a highly concentrated flow of grains in which both grain size and grain velocity decrease with depth. Therefore, large grains are transported at greater velocities than are smaller grains. Thus, at the maximum advance of an upwash, a swash mark is deposited which has the observed fining seaward and fining with depth trends in grain size.

  15. Lunar and Planetary Science XXXV: Presolar Grains

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Topics discussed include: Presolar Silicate Grains; Presolar Silicates from Primitivr Chondrites; Oxygen and Magnesium Isotopic Ratios of Presolar Spinel Grains; Study of Two New Presolar Grains from Bishunpur Ordinary Chondrite; Extinct Technetium in Presolar Grains; etc.

  16. Good Grains Gone Bad: How Grain to Grain Interactions Complicate the Onset of Motion

    NASA Astrophysics Data System (ADS)

    Yager, E.; Schmeeckle, M. W.

    2015-12-01

    Predictions of the onset of sediment motion are integral components of bed stability and bedload flux estimates. Mechanistic equations for initial motion employ a balance between driving and resisting forces. Driving forces are modeled as functions of the magnitude and duration of turbulence events whereas resisting forces are simply approximated by the grain weight and a static friction angle. Such resistance approximations do not include the effects of grain packing and dynamic interactions with surrounding sediment. To better understand and quantify grain resistance, we used a Discrete Element Method (DEM) model for a single test grain surrounded by a bed of smaller grains. We applied a constant external force on the test grain in each run and progressively increased the force between runs until the test grain moved out of its resting pocket. The DEM model calculated the test grain velocity, position and net force (sum of applied external force and forces from other grains) at time steps of 1×10-7 s. Despite applying a constant external force, the net force on the test grain fluctuated by three to six orders of magnitude, depending on the run. These fluctuations were driven by the creation and destruction of force chains, and the rearrangement of the positions of surrounding bed sediment. Stick-slip behavior, which has been observed in shear tests of granular material, occurred during test-grain motion. The frequency of stick-slip behavior generally declined with higher applied external forces. Therefore, the onset of grain motion was not continuous, as is often assumed even in the presence of fluctuating applied fluid forces. The duration and magnitude of turbulence fluctuations have received considerable attention but our results suggest that grain resistance oscillations are also important. Whether turbulence and resistance fluctuations are synchronous will likely dictate if grain movement occurs, and we are currently conducting model runs to better

  17. Dehumidification Grain Dryer

    SciTech Connect

    Lula, J.W.; Bohnert, G.W.

    1998-05-13

    A new technique developed during this project dries grain with mildly heated, dehumidified air in a closed-loop process. This proposed technique uses about one-tenth the energy and dries grain at a lower temperature, producing less damage to the kernels.Approximately 250 million automotive and truck tires are discarded each year in the U.S. The very properties that ensure a safe ride and long service life make the disposal of these scrap tires difficult. In spite of this, scrap tire recycling/reuse has rapidly grown from 10% in 1985 to over 90% today. The majority of scrap tires that are recycled/reused are burned for fuel in power plants and cement kilns. Since tires have somewhat higher heating value than coal, this would at first seem to be an acceptable option. But burning scrap tires recovers only 25% of the energy originally used to manufacture the rubber. An alternative is to use the scrap tires in the form of crumb rubber, by which 98% of the original energy is recovered. This project sought to explore potential formulations of crumb rubber with various thermoplastic binders, with one goal being developing a material for a low-cost, high-performance roofing composition. What was the state-of-the-art of the product/process prior to initiation of the project? Why was the project needed (e.g., performance, quality, cost, time to market)? Describe the strengths and interests of each party and how they are complementary with respect to the project. What KCP expertise was needed and how did it complement the partner's capabilities?

  18. Fuel requirements for grain shipments

    SciTech Connect

    Hurburgh, C.R.; Baumel, C.P.

    1985-01-01

    Fuel requirements to move grain from Iowa to export destinations were determined, based on actual fuel measurements and transportation company records. Tractor trailer trucks, barges, unit grain trains and ocean vessels were included. Generally the most fuel-efficient grain route to the Far East is through West Coast ports served by unit trains from Iowa. This route generates a 2-8 cent-per-bushel fuel cost savings from Central Iowa, relative to a routing through the Gulf of Mexico.

  19. Grain Flow at High Stresses

    NASA Astrophysics Data System (ADS)

    McSaveney, M. J.

    2015-12-01

    The transport mechanism of rapid long-runout rock avalanches was a hotly debated topic when I came on the scene in 1967. So how come it is still debated today? My explanation is that it is the expected outcome of peer review, poor comprehension, and technological advances outpacing intellectual advances. Why think about the problem when we can model it! So let us think about the problem. Shreve thought that rock avalanches fell upon and trapped a layer of air. What physics was he thinking about? It is how feathers and tissue papers fall. When my rock avalanches fly, they fly like unlubricated bricks using the physics of projectiles and ballistics. But the main transport mechanism is not flight. The dominant impression from watching a rock avalanche in motion is of fluid flow, as Heim described it in 1882. A rock avalanche is a very large grain flow. Bagnold studied dispersive grain flows, but why should one assume that rock avalanches are dispersive grain flows as many do. The more common grain flow type is a dense grain flow and rock avalanches are dense grain flows in which the weight can and does generate very high stresses at grain contacts. Brittle rock deforms elastically up to its compressive strength, whereupon it breaks, releasing elastic strain as transient elastic strain (seismic energy to a seismologist, acoustic energy to a physicist). Melosh and others have shown that acoustic energy can fluidize a grain mass. There is no exotic physics behind grain flow at high stress. When grains break, the released elastic strain has to go somewhere, and it goes somewhere principally by transmission though grain contacts. Depending on the state of stress at the grain contact, the contact will pass the stress or will slip at conventional values of Coulomb friction. Enough thinking! A physical model of the entire process is too big for any laboratory. So whose numerical model will do it?

  20. Grain refinement in undercooled metals

    SciTech Connect

    Xiao, J.Z.; Yang, H.; Kui, H.W.

    1998-12-31

    Recently, it was demonstrated that grain refinement in metals can take place through two mechanisms, namely, dynamic nucleation and remelting of initially formed dendrites. In this study, it was found that Ni{sub 99.45}B{sub 0.55} undergoes grain refinement, both by dynamic nucleation or by remelting, depending on the initial bulk undercooling just before crystallization. The nature of the grain refinement process is confirmed by microstructural analysis of the undercooled specimens.

  1. Grain dust and the lungs.

    PubMed Central

    Chan-Yeung, M.; Ashley, M. J.; Grzybowski, S.

    1978-01-01

    Grain dust is composed of a large number of materials, including various types of grain and their disintegration products, silica, fungi, insects and mites. The clinical syndromes described in relation to exposure to grain dust are chronic bronchitis, grain dust asthma, extrinsic allergic alveolitis, grain fever and silo-filler's lung. Rhinitis and conjunctivitis are also common in grain workers. While the concentration and the quality of dust influence the frequency and the type of clinical syndrome in grain workers, host factors are also important. Of the latter, smoking is the most important factor influencing the frequency of chronic bronchitis. The role of atopy and of bronchial hyperreactivity in grain dust asthma has yet to be assessed. Several well designed studies are currently being carried out in North America not only to delineate the frequency of the respiratory abnormalities, the pathogenetic mechanisms and the host factors, but also to establish a meaningful threshold limit concentration for grain dust. Images p1272-a PMID:348288

  2. Grain Size and Morphological Variability

    NASA Astrophysics Data System (ADS)

    Macmahan, J.; Gallagher, E.; Reniers, A.; Thornton, E.

    2008-12-01

    Grain size on natural beaches has traditionally been assumed to be uniform and modeling efforts assume a single mean grain size for an entire beach environment. Many recent studies contradict this assumption and suggest that sediment grain size on a beach is not homogeneous and that variations in sediment size and supply are important in sediment transport and morphodynamics at all scales. Unfortunately, measuring grain size is difficult, tedious and time consuming. Therefore, in spite of the evidence pointing to the importance of grain size in sediment transport and morphodynamics, many previous studies have been based on only a few field samples. Rubin (2004) introduced a technique for measuring surface grain size in situ in rivers and deeper coastal waters, using a digital camera and auto-correlation of digital images. Using this technique, information about the surface grain size distribution can be obtained quickly and inexpensively. Following Rubin (2004), we have developed a mobile digital imaging system (DIS) for surveying grain size on beaches. The DIS was used during two experiments: RCEX, a rip current experiment in Monterey, CA in April 2007 and Truc Vert '08, a multi-institutional, international experiment, on the Atlantic coast of France in March 2008. Preliminary results suggest that grain size varies spatially with the morphology of beach features and temporally with changes in tide level, wave energy, and morphodynamics. These data are being used to examine the relationship between morphological, sedimentological and hydrodynamic variability.

  3. Grain Size and Morphological Variability

    NASA Astrophysics Data System (ADS)

    Gallagher, E. L.; Reniers, A. J.; Macmahan, J. H.; Thornton, E. B.

    2009-12-01

    Grain size on natural beaches has traditionally been assumed to be uniform and modeling efforts assume a single mean grain size for an entire beach environment. Many recent studies contradict this assumption and suggest that sediment grain size on a beach is not homogeneous and that variations in sediment size and supply are important in sediment transport and morphodynamics at all scales. Unfortunately, measuring grain size is tedious and time consuming. Therefore, in spite of the evidence pointing to the importance of grain size in sediment transport and morphodynamics, many previous studies have been based on only a few field samples. Rubin (2004) introduced a technique for measuring surface grain size in situ in rivers and deeper coastal waters, using a digital camera and auto-correlation of digital images. Using this technique, information about the surface grain size distribution can be obtained quickly and inexpensively. Following Rubin (2004), we have developed a mobile digital imaging system (DIS) for surveying grain size on beaches. The DIS was used during three experiments: RCEX and REX, both rip current experiments in Monterey, CA (April 2007 and April 2009) and Truc Vert ’08, a multi-institutional, international experiment, on the Atlantic coast of France in March 2008. In 2007 and 2008 spatial surveys of surface grain size were completed every few days over large (~500x500m) intertidal areas. The 2009 experiment focused on twice-daily sampling of two cross shore lines to examine temporal grain size variability of the intertidal beach. Preliminary results suggest that grain size varies spatially with the morphology of beach features (eg, rip channels and shoals) and temporally with changes in tide level, wave energy, and morphodynamics. These data are being used to examine the relationship between morphological, sedimentological and hydrodynamic variability.

  4. Detrital Mineral Grains in Tektites.

    PubMed

    Bairnes, V E

    1963-12-27

    Abundant detrital crystalline mineral grains have been found in layered Muong Nong-type indochinite tektites from Nong Sapong, northeastern Thailand. These grains are an integral part of some tektite layers, and their presence furnishes strong presumptive evidence that indochinites, as well as other tektite groups in which layered specimens occur, formed from surficial earth materials.

  5. Grain alignment by ferromagnetic impurities

    NASA Technical Reports Server (NTRS)

    Mathis, J. S.

    1986-01-01

    The observed wavelength dependence of linear polarization, and its variation from region to region can be explained by the following assumptions. Interstellar grains resemble interplanetary grains, in that they are composed of collections of small particles coagulated together into elongated masses. A fraction of the small particles are ferromagnetic. Presumably these are either metallic Fe or magnetite, Fe3O4. If and only if a large grain contains one or more magnetic particles is the grain aligned in the galactic magnetic field. The magnetic particles stick only to silicate grains because of chemical similarities, or (equivalently) any pure carbon grains in the diffuse interstellar medium (ISM) are too spherical to produce polarization. Grains in dense regions, such as the outer parts of molecular clouds, are larger than those in the diffuse ISM because of coagulation of the grains rather than accretion of icy mantles. These regions are known to have larger than normal values of lambda (max), the wavelength of the maximum of linear polarization. The above assumptions are sufficient to allow the calculation of the wavelength dependence of the polarization.

  6. Detrital Mineral Grains in Tektites.

    PubMed

    Bairnes, V E

    1963-12-27

    Abundant detrital crystalline mineral grains have been found in layered Muong Nong-type indochinite tektites from Nong Sapong, northeastern Thailand. These grains are an integral part of some tektite layers, and their presence furnishes strong presumptive evidence that indochinites, as well as other tektite groups in which layered specimens occur, formed from surficial earth materials. PMID:17834370

  7. Grain and legume allergy.

    PubMed

    Ito, Komei

    2015-01-01

    Among grains and legumes, wheat and soybean are the most frequent and well-characterized allergenic foods. Wheat proteins are divided into water/salt-soluble and water/salt-insoluble (gluten) fractions. The most dominant allergen in the former is α-amylase/trypsin inhibitor, which acts as an inhaled allergen causing baker's asthma. Gluten allergens, including ω-5 gliadin and high- and low-molecular-weight glutenins, contribute to wheat-dependent exercise-induced anaphylaxis in adults and immediate-type wheat allergies, including anaphylaxis, in children. Recently, wheat allergies exclusively caused by hydrolyzed wheat proteins or deamidated glutens have been reported, and the presence of unique IgE-binding epitopes has been suggested. Soybean allergens contributing to immediate-type allergic reactions in children are present in seed storage proteins, namely Gly m 5, Gly m 6 and Gly m 8. However, pollen-related soybean allergy in adults is caused by the Bet v 1 homolog of soybeans, Gly m 4. Taken together, the varying clinical manifestations of wheat and soybean allergies are predominantly caused by their different allergen components.

  8. Autonomous grain combine control system

    DOEpatents

    Hoskinson, Reed L.; Kenney, Kevin L.; Lucas, James R.; Prickel, Marvin A.

    2013-06-25

    A system for controlling a grain combine having a rotor/cylinder, a sieve, a fan, a concave, a feeder, a header, an engine, and a control system. The feeder of the grain combine is engaged and the header is lowered. A separator loss target, engine load target, and a sieve loss target are selected. Grain is harvested with the lowered header passing the grain through the engaged feeder. Separator loss, sieve loss, engine load and ground speed of the grain combine are continuously monitored during the harvesting. If the monitored separator loss exceeds the selected separator loss target, the speed of the rotor/cylinder, the concave setting, the engine load target, or a combination thereof is adjusted. If the monitored sieve loss exceeds the selected sieve loss target, the speed of the fan, the size of the sieve openings, or the engine load target is adjusted.

  9. Prevalence of IgE antibodies to grain and grain dust in grain elevator workers

    SciTech Connect

    Lewis, D.M.; Romeo, P.A.; Olenchock, S.A.

    1986-04-01

    IgE-mediated allergic reactions have been postulated to contribute to respiratory reactions seen in workers exposed to grain dusts. In an attempt better to define the prevalence of IgE antibodies in workers exposed to grain dusts, we performed the radioallergosorbent test (RAST) on worker sera using both commercial allergens prepared from grain and worksite allergens prepared from grain dust samples collected at the worksite. We found that the two types of reagents identified different populations with respect to the specificity of IgE antibodies present. The RAST assay performed using worksite allergens correlated well with skin test procedures. These results may allow us to gain better understanding of allergy associated with grain dust exposure, and document the utility of the RAST assay in assessment of occupational allergies.

  10. Quantitative characterisation of sedimentary grains

    NASA Astrophysics Data System (ADS)

    Tunwal, Mohit; Mulchrone, Kieran F.; Meere, Patrick A.

    2016-04-01

    Analysis of sedimentary texture helps in determining the formation, transportation and deposition processes of sedimentary rocks. Grain size analysis is traditionally quantitative, whereas grain shape analysis is largely qualitative. A semi-automated approach to quantitatively analyse shape and size of sand sized sedimentary grains is presented. Grain boundaries are manually traced from thin section microphotographs in the case of lithified samples and are automatically identified in the case of loose sediments. Shape and size paramters can then be estimated using a software package written on the Mathematica platform. While automated methodology already exists for loose sediment analysis, the available techniques for the case of lithified samples are limited to cases of high definition thin section microphotographs showing clear contrast between framework grains and matrix. Along with the size of grain, shape parameters such as roundness, angularity, circularity, irregularity and fractal dimension are measured. A new grain shape parameter developed using Fourier descriptors has also been developed. To test this new approach theoretical examples were analysed and produce high quality results supporting the accuracy of the algorithm. Furthermore sandstone samples from known aeolian and fluvial environments from the Dingle Basin, County Kerry, Ireland were collected and analysed. Modern loose sediments from glacial till from County Cork, Ireland and aeolian sediments from Rajasthan, India have also been collected and analysed. A graphical summary of the data is presented and allows for quantitative distinction between samples extracted from different sedimentary environments.

  11. Fluctuation effects in grain growth

    NASA Astrophysics Data System (ADS)

    Kim, Seong Gyoon; Park, Yong Bum

    2016-08-01

    In this study, we attempted to clarify the roles of fluctuation effects in grain growth. To capture the persistent nature in both space and time of fluctuations due to variations in the local surroundings of individual grains, we developed a local mean-field model. The fluctuation strength in this model is arbitrarily controlled by employing an artificial number, n , of nearest neighbor grains. Large-scale numerical computations of the model for various n values and initial GSDs were carried out to follow transient behaviors and determine the steady states. This study reveals that, in the classical mean-field model with no fluctuation effects, the steady state is not unique but is strongly dependent upon the initial GSD. However, a small fluctuation drives the mean-field model to reach the Hillert solution, independent of the fluctuation strength and initial GSD, as long as the fluctuation strength is sufficiently small. On the other hand, when the fluctuation is sufficiently strong, the fluctuation pushes the steady state of the mean-field model out of the Hillert solution, and its strength determines a unique steady state independent of the initial GSD. The strong fluctuation makes the GSD more symmetric than the Hillert distribution. Computations designed to mimic actual 2 and 3D grain growth were carried out by taking the number of nearest neighbors of each grain as a function of the scaled grain size. The resultant GSDs in two and three dimensions were compared with the direct simulations of ideal grain growth.

  12. Grain mantles: The impact on grain evolution and selective extinction

    NASA Technical Reports Server (NTRS)

    Joseph, Charles L.

    1989-01-01

    Depletion studies are used to infer the presence of mantles and to constrain grain evolutionary models in the diffuse interstellar medium. The presence of these mantles appears to be important in the evolution of the grains inside diffuse as well as dense clouds. In dense clouds where the element-to-element abundances sometimes differ from those found in diffuse clouds, empirical relationships are starting to emerge between gas abundances and various types of peculiar selective extinction. These peculiar extinction curves may be the results of nonvolatile mantle formation on grain cores or may reflect chemical differences due to variations in the intrinsic metalicity from one cloud to another. A simple model of the time evolution of a parcel of gas and dust as observed by the depletion of two elements is presented. Different studies of grain evolution and selective extinction are discussed and compared.

  13. Why Is It Important to Eat Grains, Especially Whole Grains?

    MedlinePlus

    ... foods or supplements. This reduces the risk of neural tube defects, spina bifida, and anencephaly during fetal ... with folate before and during pregnancy helps prevent neural tube defects during fetal development. Grains All About ...

  14. Interstellar Grains: 50 Years On

    NASA Astrophysics Data System (ADS)

    Wickramasinghe, N. Chandra

    2011-12-01

    Our understanding of the nature of interstellar grains has evolved considerably over the past half century with the present author and Fred Hoyle being intimately involved at several key stages of progress. The currently fashionable graphite-silicate-organic grain model has all its essential aspects unequivocally traceable to original peer-reviewedpublicationsbytheauthorand/orFredHoyle. Theprevailingreluctancetoaccepttheseclear-cut priorities may be linked to our further work that argued for interstellar grains and organics to have a biological provenance - a position perceived as heretical. The biological model, however, continues to provide a powerful unifying hypothesis for a vast amount of otherwise disconnected and disparate astronomical data.

  15. Theory of grain alignment in molecular clouds

    NASA Technical Reports Server (NTRS)

    Roberge, Wayne G.

    1993-01-01

    Research accomplishments are presented and include the following: (1) mathematical theory of grain alignment; (2) super-paramagnetic alignment of molecular cloud grains; and (3) theory of grain alignment by ambipolar diffusion.

  16. Pichia anomala in grain biopreservation.

    PubMed

    Olstorpe, Matilda; Passoth, Volkmar

    2011-01-01

    Cereal grain is a major component of food and feed in large parts of the world. The microbial flora on cereal grains may interfere with hygiene and storage stability, palatability and bioavailability of minerals and proteins may depend on the composition of the microbial population. Therefore, it is of primary interest to control the microbial species present on cereal grain. Inoculation of the biocontrol yeast Pichia anomala to cereal feed grain improved feed hygiene by reduction of moulds and Enterobacteriaceae, and enhanced the nutritional value by increasing the protein content and reducing the concentration of the antinutritional compound phytate. P. anomala strains showed a high phytase activity, for some strains also considerable extracellular phytase activity was observed. A certain maximum in biomass concentration was never exceeded indicating cell density induced growth inhibition of P. anomala.

  17. Balancing green and grain trade

    NASA Astrophysics Data System (ADS)

    Chen, Yiping; Wang, Kaibo; Lin, Yishan; Shi, Weiyu; Song, Yi; He, Xinhua

    2015-10-01

    Since 1999, China's Grain for Green project has greatly increased the vegetation cover on the Loess Plateau. Now that erosion levels have returned to historic values, vegetation should be maintained but not expanded further as planned.

  18. All About the Grains Group

    MedlinePlus

    ... Tips to Help You Eat Vegetables Beans and Peas Are Unique Foods Food Gallery Grains All About ... Tips to Help You Eat Vegetables Beans and Peas Are Unique Foods Food Gallery Protein Foods All ...

  19. Spring Small Grains Area Estimation

    NASA Technical Reports Server (NTRS)

    Palmer, W. F.; Mohler, R. J.

    1986-01-01

    SSG3 automatically estimates acreage of spring small grains from Landsat data. Report describes development and testing of a computerized technique for using Landsat multispectral scanner (MSS) data to estimate acreage of spring small grains (wheat, barley, and oats). Application of technique to analysis of four years of data from United States and Canada yielded estimates of accuracy comparable to those obtained through procedures that rely on trained analysis.

  20. Dense, finely, grained composite materials

    DOEpatents

    Dunmead, Stephen D.; Holt, Joseph B.; Kingman, Donald D.; Munir, Zuhair A.

    1990-01-01

    Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected.

  1. Stability of grain boundary texture during isothermal grain growth in UO2 considering anisotropic grain boundary properties

    NASA Astrophysics Data System (ADS)

    Hallberg, Håkan; Zhu, Yaochan

    2015-10-01

    In the present study, mesoscale simulations of grain growth in UO2 are performed using a 2D level set representation of the polycrystal grain boundary network, employed in a finite element setting. Anisotropic grain boundary properties are considered by evaluating how grain boundary energy and mobility varies with local grain boundary character. This is achieved by considering different formulations of the anisotropy of grain boundary properties, for example in terms of coincidence site lattice (CSL) correspondence. Such modeling approaches allow tracing of the stability of a number of characteristic low-Σ boundaries in the material during grain growth. The present simulations indicate that anisotropic grain boundary properties have negligible influence on the grain growth rate. However, considering the evolution of grain boundary character distribution and the grain size distribution, it is found that neglecting anisotropic boundary properties will strongly bias predictions obtained from numerical simulations.

  2. 3D grain boundary migration

    NASA Astrophysics Data System (ADS)

    Becker, J. K.; Bons, P. D.

    2009-04-01

    Microstructures of rocks play an important role in determining rheological properties and help to reveal the processes that lead to their formation. Some of these processes change the microstructure significantly and may thus have the opposite effect in obliterating any fabrics indicative of the previous history of the rocks. One of these processes is grain boundary migration (GBM). During static recrystallisation, GBM may produce a foam texture that completely overprints a pre-existing grain boundary network and GBM actively influences the rheology of a rock, via its influence on grain size and lattice defect concentration. We here present a new numerical simulation software that is capable of simulating a whole range of processes on the grain scale (it is not limited to grain boundary migration). The software is polyhedron-based, meaning that each grain (or phase) is represented by a polyhedron that has discrete boundaries. The boundary (the shell) of the polyhedron is defined by a set of facets which in turn is defined by a set of vertices. Each structural entity (polyhedron, facets and vertices) can have an unlimited number of parameters (depending on the process to be modeled) such as surface energy, concentration, etc. which can be used to calculate changes of the microstructre. We use the processes of grain boundary migration of a "regular" and a partially molten rock to demonstrate the software. Since this software is 3D, the formation of melt networks in a partially molten rock can also be studied. The interconnected melt network is of fundamental importance for melt segregation and migration in the crust and mantle and can help to understand the core-mantle differentiation of large terrestrial planets.

  3. The History of Presolar Grains

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.

    2004-01-01

    Below we summarize the results of our investigations into the history of presolar grains that were conducted in the last year. During this time we have expended much of our effort in the development of experimental techniques and sample preparation methods that are needed to laboratory in December, 2000. Specific information on this instrument is contained in the Full Proposal of PI Ernst Zinner and will not be repeated here. Our general strategy in the past year has been in large measure to explore novel sample handling methods for the very small (sub-micron), but more representative, presolar grains that can now be characterized isotopically in the NanoSIMS. We have developed experimental techniques that will permit NanoSIMS analyses of the very same ultramicrotome sections studied in the TEM, and we have developed grain dispersion, handling and mounting techniques that permit NanoSIMS isotopic analysis as well as field emission SEM, high energy TEM, and atomic force microscopy of pristine presolar grains. Although much of this has been slow and very difficult work that has no immediate payoff in terms of publishable results, we considered it absolutely necessary groundwork for future discoveries, especially in the realm of individual presolar grains that have been inaccessible to past studies due to size constraints. As discussed below, we have been largely successful in these endeavors, and expect to reap the benefits of this work in the next year. We also report on our continued morphologic studies of pristine presolar grains, on our investigations of presolar graphite grains from supernovae as well as on rarer types of presotar SIC, on the search for presolar silicates, and on our efforts to obtain direct size-distribution information on presolar SiC through X-ray mapping techniques.

  4. Sculpting sandcastles grain by grain: Self-assembled sand towers

    NASA Astrophysics Data System (ADS)

    Pacheco-Vázquez, F.; Moreau, F.; Vandewalle, N.; Dorbolo, S.

    2012-11-01

    We study the spontaneous formation of granular towers produced when dry sand is poured on a wet sand bed. When the liquid content of the bed exceeds a threshold value W, the impacting grains have a nonzero probability to stick on the wet grains due to instantaneous liquid bridges created during the impact. The trapped grains become wet by the capillary ascension of water and the process continues, giving rise to stable narrow towers. The growth velocity is determined by the surface liquid content which decreases exponentially as the tower height augments. This self-assembly mechanism (only observed in the funicular and capillary regimes) could theoretically last while the capillary rise of water is possible; however, the structure collapses before reaching this limit. The collapse occurs when the weight of the tower surpasses the cohesive stress at its base. The cohesive stress increases as the liquid content of the bed is reduced. Consequently, the highest towers are found just above W.

  5. Simultaneous Grain Growth and Grain Refinement in Bulk Ultrafine-Grained Copper under Tensile Deformation at Room Temperature

    NASA Astrophysics Data System (ADS)

    Yu, Hailiang; Lu, Cheng; Tieu, Anh Kiet; Li, Huijun; Godbole, Ajit; Kong, Charlie; Zhao, Xing

    2016-08-01

    Grain growth and grain refinement behavior during deformation determine the strength and ductility of ultrafine-grained materials. We used asymmetric cryorolling to fabricate ultrafine-grained copper sheets with an average grain width of 230 nm and having a laminate structure. The sheets show a high-true failure strain of 1.5. Observation of the microstructure at the fracture surface reveals that ultrafine laminate-structured grains were simultaneously transformed into both equiaxed nanograins and coarse grains under tensile deformation at room temperature.

  6. [Cereal grain preference of rats].

    PubMed

    Wang, P Y

    1990-07-01

    Cereal grains are usually used as the main material for preparing rodenticide baits. However, the preferences for different grains varies according to species and habitats of rats, and locations. A formula accepted at one location may not be suitable in other places, where rats are accustomed to different types of food. It is therefore important to understand the feeding habits of local rat species before implementing a control program. Seven kinds of grains, including hulled rice, corn, barley, wheat, sorghum, pranuts, and sweet potatoes were tested to study the preferences of rats in the laboratory. The results revealed that Bandicota nemorivaga, Rattus losea and R. norvegicus prefer hulled rice; Apodemus agrarius and Mus musculus prefer peanuts, and R. rattus prefers corn. The influence of quality and nutrient contents of baits on the consumption of the rats is also discussed. PMID:2402029

  7. Fractal dust grains in plasma

    SciTech Connect

    Huang, F.; Peng, R. D.; Liu, Y. H.; Chen, Z. Y.; Ye, M. F.; Wang, L.

    2012-09-15

    Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.

  8. Interstellar Grains: 50 Years on

    NASA Astrophysics Data System (ADS)

    Wickramasinghe, N. C.

    Our understanding of the nature of interstellar grains has evolved considerably over the past half century with the present author and Fred Hoyle being intimately involved at several key stages of progress. The currently fashionable graphite-silicate-organic grain model has all its essential aspects unequivocally traceable to original peer-reviewed publications by the author and/or Fred Hoyle. The prevailing reluctance to accept these clear-cut priorities may be linked to our further work that argued for interstellar grains and organics to have a biological provenance -- a position perceived as heretical. The biological model, however, continues to provide a powerful unifying hypothesis for a vast amount of otherwise disconnected and disparate astronomical data.

  9. [Cereal grain preference of rats].

    PubMed

    Wang, P Y

    1990-07-01

    Cereal grains are usually used as the main material for preparing rodenticide baits. However, the preferences for different grains varies according to species and habitats of rats, and locations. A formula accepted at one location may not be suitable in other places, where rats are accustomed to different types of food. It is therefore important to understand the feeding habits of local rat species before implementing a control program. Seven kinds of grains, including hulled rice, corn, barley, wheat, sorghum, pranuts, and sweet potatoes were tested to study the preferences of rats in the laboratory. The results revealed that Bandicota nemorivaga, Rattus losea and R. norvegicus prefer hulled rice; Apodemus agrarius and Mus musculus prefer peanuts, and R. rattus prefers corn. The influence of quality and nutrient contents of baits on the consumption of the rats is also discussed.

  10. RSRM Propellant Grain Geometry Modification

    NASA Technical Reports Server (NTRS)

    Schorr, Andrew A.; Endicott, Joni B.; McCool, Alex (Technical Monitor)

    2000-01-01

    This document is composed of viewgraphs about the RSRM propellant grain geometry modification project, which hopes to improve personnel and system safety by modifying propellant grain geometry to improve structural factors of safety. Using techniques such as Finite Element Analysis to determine blend radii required to reduce localized stresses, and ballistic predictions to ensure that the ballistics, ignition transient and Block Model have not been adversely affected, the project hopes to build and test FSM-10 with a new design, and determine flight effectivity pending successful test evaluation.

  11. Choosing Whole-Grain Foods: 10 Tips for Purchasing and Storing Whole-Grain Foods

    MedlinePlus

    ... whole-grain ingredients include whole oats, whole-wheat flour, whole-grain corn, whole-grain brown rice, and whole rye. Foods that say “multi-grain,” “ ... the shelf life varies too. Most whole-grain flours keep well in the ... for 6 to 8 months. Cooked brown rice can be refrigerated 3 to 5 days and ...

  12. Grain production for alcohol fuels

    SciTech Connect

    Lockeretz, W.

    1980-05-01

    This report provides primarily an assessment of the resource base for producing alcohol fuel from grain. The effect of different levels of alcohol production are discussed with respect to farm income, land conservation practices, food prices, and exports. The economics of ethanol production from the standpoint of feedstock availability and price are comprehensively examined.

  13. Grain refinement in undercooled nickel

    SciTech Connect

    Leung, K.K.; Chiu, C.P.; Kui, H.W.

    1995-05-15

    In this paper, the microstructures of undercooled Ni that solidified at various initial bulk undercoolings are examined in detail in order to understand the mechanism of grain refinement in metallic systems. Molten Ni contracts on solidification. In the experiment, since it was covered by molten glass flux, upon crystallization cavities had to form to accommodate the rapid volume change if the undercooled specimen remained in contact with the glass flux, which could not flow so readily. The adhesiveness between Ni and glass flux was confirmed by removing them from a furnace after the whole system had been cooled down to room temperature. Furthermore, it was clear from the micrographs that after a cavity had formed, it did not collapse. It can therefore be concluded that smaller grains are found to concentrate near the void along the minor axis. At still higher undercoolings, the effect was so violent that the voids took irregular shapes. Again, the grains near the cavity are somewhat smaller than those further away. Accordingly, the authors conclude that grain refinement in undercooled Ni was brought about by dynamic nucleation as the cavities formed.

  14. 77 FR 76452 - Grain Inspection Advisory Committee Reestablishment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-28

    ... Grain Inspection, Packers and Stockyards Administration Grain Inspection Advisory Committee Reestablishment AGENCY: Grain Inspection, Packers and Stockyards Administration, USDA. ACTION: Notice to... Grain Inspection, Packers and Stockyards Administration (GIPSA) Grain Inspection Advisory...

  15. 75 FR 81965 - Grain Inspection Advisory Committee Reestablishment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-29

    ...; ] DEPARTMENT OF AGRICULTURE Grain Inspection, Packers and Stockyards Administration Grain Inspection Advisory Committee Reestablishment AGENCY: Grain Inspection, Packers and Stockyards Administration, USDA. ACTION... reestablished the Grain Inspection, Packers and Stockyards Administration (GIPSA) Grain Inspection...

  16. What Controls Ooid Grain Size?

    NASA Astrophysics Data System (ADS)

    Trower, L.; Lamb, M. P.; Fischer, W. W.

    2015-12-01

    Ooids are subspherical chemical sand grains composed of concentric layers of CaCO₃ surrounding a central nucleus. These grains represent a common mode of carbonate sedimentation, making them potentially powerful proxies for paleoenvironmental conditions, provided a mechanistic understanding of the physical, chemical, and perhaps biological conditions necessary for their formation. At a basic level, growth of an ooid reflects that precipitation has outpaced abrasion over the ooid's lifetime. We can describe change in ooid size over time (net growth rate) mechanistically as the sum of a growth rate (the rate of carbonate precipitation on the ooid surface) and an abrasion rate (the rate of removal of material through grain-grain and grain-bed collisions). Previous studies have addressed the growth rate, investigating the extent to which microbial activity affects and/or controls carbonate precipitation on ooid surfaces, and the net growth rate, using stepwise acid digestion and radiocarbon dating to determine the ages of cortical layers. We focused on the abrasion rate and designed an experimental study to measure abrasion rates of ooids as a function of grain size and sediment transport stage. Preliminary experiments with medium-sand-sized ooids at a Rouse number of ~1.2 yielded an abrasion rate of 0.04 g/hr (or ~40 ng/ooid/hr), which is four orders of magnitude greater than the fastest net growth rates reported in the recent high resolution ooid cortex radiocarbon dating study by Beaupre et al. (2015). This result requires that either: 1) ooids are essentially not moving and therefore not being abraded or 2) precipitation rates are also much more rapid than the net growth rates estimated by incremental radiocarbon dating. The former constraint is inconsistent with field observations that most marine ooids occur in high energy shoal environments, both in modern examples and in the rock record. Precipitation rates must therefore also be relatively rapid compared

  17. Cereal grains, legumes and diabetes.

    PubMed

    Venn, B J; Mann, J I

    2004-11-01

    This review examines the evidence for the role of whole grain foods and legumes in the aetiology and management of diabetes. MedLine and SilverPlatter ('Nutrition' and 'Food Science FSTA') databases were searched to identify epidemiological and experimental studies relating to the effects of whole grain foods and legumes on indicators of carbohydrate metabolism. Epidemiological studies strongly support the suggestion that high intakes of whole grain foods protect against the development of type II diabetes mellitus (T2DM). People who consume approximately 3 servings per day of whole grain foods are less likely to develop T2DM than low consumers (<3 servings per week) with a risk reduction in the order of 20-30%. The role of legumes in the prevention of diabetes is less clear, possibly because of the relatively low intake of leguminous foods in the populations studied. However, legumes share several qualities with whole grains of potential benefit to glycaemic control including slow release carbohydrate and a high fibre content. A substantial increase in dietary intake of legumes as replacement food for more rapidly digested carbohydrate might therefore be expected to improve glycaemic control and thus reduce incident diabetes. This is consistent with the results of dietary intervention studies that have found improvements in glycaemic control after increasing the dietary intake of whole grain foods, legumes, vegetables and fruit. The benefit has been attributed to an increase in soluble fibre intake. However, prospective studies have found that soluble fibre intake is not associated with a lower incidence of T2DM. On the contrary, it is cereal fibre that is largely insoluble that is associated with a reduced risk of developing T2DM. Despite this, the addition of wheat bran to the diets of diabetic people has not improved indicators of glycaemic control. These apparently contradictory findings might be explained by metabolic studies that have indicated improvement

  18. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â...) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF... classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled...

  19. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â...) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF... classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled...

  20. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â...) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF... classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled...

  1. Impact fracture experiments simulating interstellar grain-grain collisions

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann; Chang, Sherwood; Dickinson, J. Thomas

    1990-01-01

    Oxide and silicate grains condensing during the early phases of the formation of the solar system or in the outflow of stars are exposed to high partial pressures of the low-z elements H, C, N and O and their simple gaseous compounds. Though refractory minerals are nominally anhydrous and non-carbonate, if they crystallize in the presence of H2O, N2 and CO or CO2 gases, they dissolve traces of the gaseous components. The question arises: How does the presence of dissolved gases or gas components manifest itself when grain-grain collisions occur. What are the gases emitted when grains are shattered during a collision event. Researchers report on fracture experiments in ultrahigh vacuum (UHV, approximately less than 10 to the -8th power mbar) designed to measure (by means of a quadrupole mass spectrometer, QMS, with microns to ms time resolution) the emission of gases and vapors during and after impact (up to 1.5 sec). Two terrestrial materials were chosen which represent structural and compositional extremes: olivine (San Carlos, AZ), a densely packed Mg-Fe(2+) silicate from the upper mantle, available as 6 to 12 mm single crystals, and obsidian (Oregon), a structurally open, alkaline-SiO2-rich volcanic glass. In the olivine crystals OH- groups have been identified spectroscopically, as well as H2 molecules. Obsidian is a water-rich glass containing OH- besides H2O molecules. Olivine from the mantle often contains CO2, either as CO2-rich fluid in fluid inclusions or structurally dissolved or both. By analogy to synthetic glasses CO2 in the obsidian may be present in form of CO2 molecules in voids of molecular dimensions, or as carbonate anions, CO3(2-). No organic molecules have been detected spectroscopically in either material. Results indicate that refractory oxide/silicates which contain dissolved traces of the H2O and CO/CO2 components but no spectroscopically detectable traces of organics may release complex H-C-O (possibly H-C-N-O) molecules upon fracture

  2. AGB stars and presolar grains

    SciTech Connect

    Busso, M.; Trippella, O.; Maiorca, E.; Palmerini, S.

    2014-05-09

    Among presolar materials recovered in meteorites, abundant SiC and Al{sub 2}O{sub 3} grains of AGB origins were found. They showed records of C, N, O, {sup 26}Al and s-element isotopic ratios that proved invaluable in constraining the nucleosynthesis models for AGB stars [1, 2]. In particular, when these ratios are measured in SiC grains, they clearly reveal their prevalent origin in cool AGB circumstellar envelopes and provide information on both the local physics and the conditions at the nucleosynthesis site (the H- and He-burning layers deep inside the structure). Among the properties ascertained for the main part of the SiC data (the so-called mainstream ones), we mention a large range of {sup 14}N/{sup 15}N ratios, extending below the solar value [3], and {sup 12}C/{sup 13}C ratios ≳ 30. Other classes of grains, instead, display low carbon isotopic ratios (≳ 10) and a huge dispersion for N isotopes, with cases of large {sup 15}N excess. In the same grains, isotopes currently feeded by slow neutron captures reveal the characteristic pattern expected from this process at an efficiency slightly lower than necessary to explain the solar main s-process component. Complementary constraints can be found in oxide grains, especially Al{sub 2}O{sub 3} crystals. Here, the oxygen isotopes and the content in {sup 26}Al are of a special importance for clarifying the partial mixing processes that are known to affect evolved low-mass stars. Successes in modeling the data, as well as problems in explaining some of the mentioned isotopic ratios through current nucleosynthesis models are briefly outlined.

  3. Grain Refinement of Deoxidized Copper

    NASA Astrophysics Data System (ADS)

    Balart, María José; Patel, Jayesh B.; Gao, Feng; Fan, Zhongyun

    2016-08-01

    This study reports the current status of grain refinement of copper accompanied in particular by a critical appraisal of grain refinement of phosphorus-deoxidized, high residual P (DHP) copper microalloyed with 150 ppm Ag. Some deviations exist in terms of the growth restriction factor (Q) framework, on the basis of empirical evidence reported in the literature for grain size measurements of copper with individual additions of 0.05, 0.1, and 0.5 wt pct of Mo, In, Sn, Bi, Sb, Pb, and Se, cast under a protective atmosphere of pure Ar and water quenching. The columnar-to-equiaxed transition (CET) has been observed in copper, with an individual addition of 0.4B and with combined additions of 0.4Zr-0.04P and 0.4Zr-0.04P-0.015Ag and, in a previous study, with combined additions of 0.1Ag-0.069P (in wt pct). CETs in these B- and Zr-treated casts have been ascribed to changes in the morphology and chemistry of particles, concurrently in association with free solute type and availability. No further grain-refining action was observed due to microalloying additions of B, Mg, Ca, Zr, Ti, Mn, In, Fe, and Zn (~0.1 wt pct) with respect to DHP-Cu microalloyed with Ag, and therefore are no longer relevant for the casting conditions studied. The critical microalloying element for grain size control in deoxidized copper and in particular DHP-Cu is Ag.

  4. Grain Refinement of Deoxidized Copper

    NASA Astrophysics Data System (ADS)

    Balart, María José; Patel, Jayesh B.; Gao, Feng; Fan, Zhongyun

    2016-10-01

    This study reports the current status of grain refinement of copper accompanied in particular by a critical appraisal of grain refinement of phosphorus-deoxidized, high residual P (DHP) copper microalloyed with 150 ppm Ag. Some deviations exist in terms of the growth restriction factor ( Q) framework, on the basis of empirical evidence reported in the literature for grain size measurements of copper with individual additions of 0.05, 0.1, and 0.5 wt pct of Mo, In, Sn, Bi, Sb, Pb, and Se, cast under a protective atmosphere of pure Ar and water quenching. The columnar-to-equiaxed transition (CET) has been observed in copper, with an individual addition of 0.4B and with combined additions of 0.4Zr-0.04P and 0.4Zr-0.04P-0.015Ag and, in a previous study, with combined additions of 0.1Ag-0.069P (in wt pct). CETs in these B- and Zr-treated casts have been ascribed to changes in the morphology and chemistry of particles, concurrently in association with free solute type and availability. No further grain-refining action was observed due to microalloying additions of B, Mg, Ca, Zr, Ti, Mn, In, Fe, and Zn (~0.1 wt pct) with respect to DHP-Cu microalloyed with Ag, and therefore are no longer relevant for the casting conditions studied. The critical microalloying element for grain size control in deoxidized copper and in particular DHP-Cu is Ag.

  5. Concepts on Low Temperature Mechanical Grain Growth

    SciTech Connect

    Sharon, John Anthony; Boyce, Brad Lee

    2013-11-01

    In metals, as grain size is reduced below 100nm, conventional dislocation plasticity is suppressed resulting in improvements in strength, hardness, and wears resistance. Existing and emerging components use fine grained metals for these beneficial attributes. However, these benefits can be lost in service if the grains undergo growth during the component’s lifespan. While grain growth is traditionally viewed as a purely thermal process that requires elevated temperature exposure, recent evidence shows that some metals, especially those with nanocrystalline grain structure, can undergo grain growth even at room temperature or below due to mechanical loading. This report has been assembled to survey the key concepts regarding how mechanical loads can drive grain coarsening at room temperature and below. Topics outlined include the atomic level mechanisms that facilitate grain growth, grain boundary mobility, and the impact of boundary structure, loading scheme, and temperature.

  6. Carpel size, grain filling, and morphology determine individual grain weight in wheat.

    PubMed

    Xie, Quan; Mayes, Sean; Sparkes, Debbie L

    2015-11-01

    Individual grain weight is a major yield component in wheat. To provide a comprehensive understanding of grain weight determination, the carpel size at anthesis, grain dry matter accumulation, grain water uptake and loss, grain morphological expansion, and final grain weight at different positions within spikelets were investigated in a recombinant inbred line mapping population of bread wheat (Triticum aestivum L.)×spelt (Triticum spelta L.). Carpel size, grain dry matter and water accumulation, and grain dimensions interacted strongly with each other. Furthermore, larger carpels, a faster grain filling rate, earlier and longer grain filling, more grain water, faster grain water absorption and loss rates, and larger grain dimensions were associated with higher grain weight. Frequent quantitative trait locus (QTL) coincidences between these traits were observed, particularly those on chromosomes 2A, 3B, 4A, 5A, 5DL, and 7B, each of which harboured 16-49 QTLs associated with >12 traits. Analysis of the allelic effects of coincident QTLs confirmed their physiological relationships, indicating that the complex but orderly grain filling processes result mainly from pleiotropy or the tight linkages of functionally related genes. After grain filling, distal grains within spikelets were smaller than basal grains, primarily due to later grain filling and a slower initial grain filling rate, followed by synchronous maturation among different grains. Distal grain weight was improved by increased assimilate availability from anthesis. These findings provide deeper insight into grain weight determination in wheat, and the high level of QTL coincidences allows simultaneous improvement of multiple grain filling traits in breeding.

  7. Carpel size, grain filling, and morphology determine individual grain weight in wheat

    PubMed Central

    Xie, Quan; Mayes, Sean; Sparkes, Debbie L.

    2015-01-01

    Individual grain weight is a major yield component in wheat. To provide a comprehensive understanding of grain weight determination, the carpel size at anthesis, grain dry matter accumulation, grain water uptake and loss, grain morphological expansion, and final grain weight at different positions within spikelets were investigated in a recombinant inbred line mapping population of bread wheat (Triticum aestivum L.)×spelt (Triticum spelta L.). Carpel size, grain dry matter and water accumulation, and grain dimensions interacted strongly with each other. Furthermore, larger carpels, a faster grain filling rate, earlier and longer grain filling, more grain water, faster grain water absorption and loss rates, and larger grain dimensions were associated with higher grain weight. Frequent quantitative trait locus (QTL) coincidences between these traits were observed, particularly those on chromosomes 2A, 3B, 4A, 5A, 5DL, and 7B, each of which harboured 16−49 QTLs associated with >12 traits. Analysis of the allelic effects of coincident QTLs confirmed their physiological relationships, indicating that the complex but orderly grain filling processes result mainly from pleiotropy or the tight linkages of functionally related genes. After grain filling, distal grains within spikelets were smaller than basal grains, primarily due to later grain filling and a slower initial grain filling rate, followed by synchronous maturation among different grains. Distal grain weight was improved by increased assimilate availability from anthesis. These findings provide deeper insight into grain weight determination in wheat, and the high level of QTL coincidences allows simultaneous improvement of multiple grain filling traits in breeding. PMID:26246614

  8. Sculpting sandcastles grain by grain: self-assembled sand towers.

    PubMed

    Pacheco-Vázquez, F; Moreau, F; Vandewalle, N; Dorbolo, S

    2012-11-01

    We study the spontaneous formation of granular towers produced when dry sand is poured on a wet sand bed. When the liquid content of the bed exceeds a threshold value W*, the impacting grains have a nonzero probability to stick on the wet grains due to instantaneous liquid bridges created during the impact. The trapped grains become wet by the capillary ascension of water and the process continues, giving rise to stable narrow towers. The growth velocity is determined by the surface liquid content which decreases exponentially as the tower height augments. This self-assembly mechanism (only observed in the funicular and capillary regimes) could theoretically last while the capillary rise of water is possible; however, the structure collapses before reaching this limit. The collapse occurs when the weight of the tower surpasses the cohesive stress at its base. The cohesive stress increases as the liquid content of the bed is reduced. Consequently, the highest towers are found just above W*. PMID:23214775

  9. Grain Growth in Cerium Metal

    NASA Astrophysics Data System (ADS)

    Cooley, Jason; Katz, Martha; Mielke, Charles; Montalvo, Joel

    We report on grain growth in forged and rolled cerium plate for temperatures from 350 to 700 degrees C and times from 30 to 120 minutes. The cerium was made by arc-melting into a 25 mm deep by 80 mm diameter copper mold. The resulting disk was forged at room temperature to a 25% reduction of thickness four times with a 350 degree C strain relief heat treatment for 60 minutes between forging steps. The resulting 8 mm thick plate was clock rolled at room temperature to a 25% reduction of thickness three times with a 350 C strain relief heat treatment between steps resulting in a plate approximately 3 mm thick. 5 x 10 mm coupons were cut from the plate for the grain growth study.

  10. Grain Alignment in Starless Cores

    NASA Astrophysics Data System (ADS)

    Jones, T. J.; Bagley, M.; Krejny, M.; Andersson, B.-G.; Bastien, P.

    2015-01-01

    We present near-IR polarimetry data of background stars shining through a selection of starless cores taken in the K band, probing visual extinctions up to {{A}V}˜ 48. We find that {{P}K}/{{τ }K} continues to decline with increasing AV with a power law slope of roughly -0.5. Examination of published submillimeter (submm) polarimetry of starless cores suggests that by {{A}V}≳ 20 the slope for P versus τ becomes ˜-1, indicating no grain alignment at greater optical depths. Combining these two data sets, we find good evidence that, in the absence of a central illuminating source, the dust grains in dense molecular cloud cores with no internal radiation source cease to become aligned with the local magnetic field at optical depths greater than {{A}V}˜ 20. A simple model relating the alignment efficiency to the optical depth into the cloud reproduces the observations well.

  11. Conducting Grains in Dusty Plasmas

    NASA Astrophysics Data System (ADS)

    Hyde, Truell; Matthews, Lorin; Carmona-Reyes, Jorge

    The existence of dusty plasma environments in space is common, with the dust originating from a variety of sources. Such environments include protostellar and protoplanetary systems during their formation and evolution. In addition, iron rich meteors, which contain remnants of primordial solar system material, are also a source for micron-sized metallic dust particles that interact with the surrounding plasma. Although research has been conducted on nonconducting grains within a complex plasma environment, very little experimental data exists on conducting grains within complex plasmas. This study will compare and contrast the dynamics of non-conducting (Melamine Formaldehyde) and conducting particles (Gold-coated Melamine Formaldehyde particles) immersed in a capacitively coupled RF plasma maintained within a GEC reference cell. The resulting experimental data will be related to the fundamental physics behind the charging mechanism for such micron-size particles.

  12. Positron trapping at grain boundaries

    SciTech Connect

    Dupasquier, A. ); Romero, R.; Somoza, A. )

    1993-10-01

    The standard positron trapping model has often been applied, as a simple approximation, to the interpretation of positron lifetime spectra in situations of diffusion-controlled trapping. This paper shows that this approximation is not sufficiently accurate, and presents a model based on the correct solution of the diffusion equation, in the version appropriate for studying positron trapping at grain boundaries. The model is used for the analysis of new experimental data on positron lifetime spectra in a fine-grained Al-Ca-Zn alloy. Previous results on similar systems are also discussed and reinterpreted. The analysis yields effective diffusion coefficients not far from the values known for the base metals of the alloys.

  13. Isotopic anomalies in extraterrestrial grains.

    PubMed

    Ireland, T R

    1996-03-01

    Isotopic compositions are referred to as anomalous if the isotopic ratios measured cannot be related to the terrestrial (solar) composition of a given element. While small effects close to the resolution of mass spectrometric techniques can have ambiguous origins, the discovery of large isotopic anomalies in inclusions and grains from primitive meteorites suggests that material from distinct sites of stellar nucleosynthesis has been preserved. Refractory inclusions, which are predominantly composed of the refractory oxides of Al, Ca, Ti, and Mg, in chondritic meteorites commonly have excesses in the heaviest isotopes of Ca, Ti, and Cr which are inferred to have been produced in a supernova. Refractory inclusions also contain excess 26Mg from short lived 26Al decay. However, despite the isotopic anomalies indicating the preservation of distinct nucleosynthetic sites, refractory inclusions have been processed in the solar system and are not interstellar grains. Carbon (graphite and diamond) and silicon carbide grains from the same meteorites also have large isotopic anomalies but these phases are not stable in the oxidized solar nebula which suggests that they are presolar and formed in the circumstellar atmospheres of carbon-rich stars. Diamond has a characteristic signature enriched in the lightest and heaviest isotopes of Xe, and graphite shows a wide range in C isotopic compositions. SiC commonly has C and N isotopic signatures which are characteristic of H-burning in the C-N-O cycle in low-mass stars. Heavier elements such as Si, Ti, Xe, Ba, and Nd, carry an isotopic signature of the s-process. A minor population of SiC (known as Grains X, ca. 1%) are distinct in having decay products of short lived isotopes 26Al (now 26Mg), 44Ti (now 44Ca), and 49V (now 49Ti), as well as 28Si excesses which are characteristic of supernova nucleosynthesis. The preservation of these isotopic anomalies allows the examination of detailed nucleosynthetic pathways in stars. PMID

  14. Isotopic anomalies in extraterrestrial grains.

    PubMed

    Ireland, T R

    1996-03-01

    Isotopic compositions are referred to as anomalous if the isotopic ratios measured cannot be related to the terrestrial (solar) composition of a given element. While small effects close to the resolution of mass spectrometric techniques can have ambiguous origins, the discovery of large isotopic anomalies in inclusions and grains from primitive meteorites suggests that material from distinct sites of stellar nucleosynthesis has been preserved. Refractory inclusions, which are predominantly composed of the refractory oxides of Al, Ca, Ti, and Mg, in chondritic meteorites commonly have excesses in the heaviest isotopes of Ca, Ti, and Cr which are inferred to have been produced in a supernova. Refractory inclusions also contain excess 26Mg from short lived 26Al decay. However, despite the isotopic anomalies indicating the preservation of distinct nucleosynthetic sites, refractory inclusions have been processed in the solar system and are not interstellar grains. Carbon (graphite and diamond) and silicon carbide grains from the same meteorites also have large isotopic anomalies but these phases are not stable in the oxidized solar nebula which suggests that they are presolar and formed in the circumstellar atmospheres of carbon-rich stars. Diamond has a characteristic signature enriched in the lightest and heaviest isotopes of Xe, and graphite shows a wide range in C isotopic compositions. SiC commonly has C and N isotopic signatures which are characteristic of H-burning in the C-N-O cycle in low-mass stars. Heavier elements such as Si, Ti, Xe, Ba, and Nd, carry an isotopic signature of the s-process. A minor population of SiC (known as Grains X, ca. 1%) are distinct in having decay products of short lived isotopes 26Al (now 26Mg), 44Ti (now 44Ca), and 49V (now 49Ti), as well as 28Si excesses which are characteristic of supernova nucleosynthesis. The preservation of these isotopic anomalies allows the examination of detailed nucleosynthetic pathways in stars.

  15. Lunar soils grain size catalog

    NASA Technical Reports Server (NTRS)

    Graf, John C.

    1993-01-01

    This catalog compiles every available grain size distribution for Apollo surface soils, trench samples, cores, and Luna 24 soils. Original laboratory data are tabled, and cumulative weight distribution curves and histograms are plotted. Standard statistical parameters are calculated using the method of moments. Photos and location comments describe the sample environment and geological setting. This catalog can help researchers describe the geotechnical conditions and site variability of the lunar surface essential to the design of a lunar base.

  16. Grain-Scale Supercharging on the Moon

    NASA Astrophysics Data System (ADS)

    Zimmerman, M. I.; Farrell, W. M.; Hartzell, C. M.; Wang, X.; Horanyi, M.; Hurley, D. M.; Hibbits, K.

    2016-11-01

    Under lunar solar wind bombardment and photoemission levels, accumulated electric charge can produce grain-to-grain electric field strengths exceeding the dielectric breakdown limit, even away from the cold, relatively non-conductive lunar poles.

  17. Mechanical Behavior of Grain Boundary Engineered Copper

    SciTech Connect

    Carter, S B; Hodge, A M

    2006-08-08

    A grain boundary engineered copper sample previously characterized by Electron Backscatter Diffraction (EBSD) has been selected for nanoindentation tests. Given the fact that grain boundaries have thicknesses in the order of 1 micron or less, it is essential to use nanomechanics to test the properties of individual grain boundaries. The Hysitron nanoindenter was selected over the MTS nanoindenter due to its superior optical capabilities that aid the selection and identification of the areas to be tested. An area of 2mm by 2mm with an average grain size of 50 microns has been selected for the study. Given the EBSD mapping, grains and grain boundaries with similar orientations are tested and the hardness and modulus are compared. These results will give a relationship between the mechanical properties and the engineered grain boundaries. This will provide for the first time a correlation between grain boundary orientation and the mechanical behavior of the sample at the nanoscale.

  18. Grain boundaries and surfaces in polycrystalline photovoltaics

    NASA Astrophysics Data System (ADS)

    Haney, Paul; Yoon, Heayoung; Zhitenev, Nikolai

    Despite the fact that polycrystalline photovoltaics materials such as CdTe and CIGS are an established commercial technology, the precise role of grain boundaries in their performance remains poorly understood. The high defect density at grain boundaries is generally detrimental to carrier lifetime, however the electric fields surrounding charged grain boundaries may separate electrons and holes, effectively passivating the grain boundary. One difficulty in ascertaining the properties of grain boundaries is that high spatial resolution experimental techniques needed to probe individual grain boundaries are generally surface sensitive. For this reason, extracting quantitative grain boundary and other material properties from this data requires a quantitatively accurate model of the exposed surface. Motivated by these considerations, we present a theoretical analysis of the response of a polycrystalline semiconductor to a localized excitation near a grain boundary, and near the surface. We use our analytical results to interpret electron beam induced current (EBIC) data on polycrystalline CdTe solar cells.

  19. Solid Propellant Grain Structural Integrity Analysis

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The structural properties of solid propellant rocket grains were studied to determine the propellant resistance to stresses. Grain geometry, thermal properties, mechanical properties, and failure modes are discussed along with design criteria and recommended practices.

  20. Phenomenology of Abnormal Grain Growth in Systems with Nonuniform Grain Boundary Mobility

    NASA Astrophysics Data System (ADS)

    DeCost, Brian L.; Holm, Elizabeth A.

    2016-07-01

    We have investigated the potential for nonuniform grain boundary mobility to act as a persistence mechanism for abnormal grain growth (AGG) using Monte Carlo Potts model simulations. The model system consists of a single initially large candidate grain embedded in a matrix of equiaxed grains, corresponding to the abnormal growth regime before impingement occurs. We assign a mobility advantage to grain boundaries between the candidate grain and a randomly selected subset of the matrix grains. We observe AGG in systems with physically reasonable fractions of fast boundaries; the probability of abnormal growth increases as the density of fast boundaries increases. This abnormal growth occurs by a series of fast, localized growth events that counteract the tendency of abnormally large grains to grow more slowly than the surrounding matrix grains. Resulting abnormal grains are morphologically similar to experimentally observed abnormal grains.

  1. Thermal properties of heterogeneous grains

    NASA Technical Reports Server (NTRS)

    Lien, David J.

    1988-01-01

    Cometary dust is not spherical nor homogeneous, yet these are the assumptions used to model its thermal, optical, and dynamical properties. To better understand the effects of heterogeneity on the thermal and optical properties of dust grains, the effective dielectric constant for an admixture of magnetite and a silicate were calculated using two different effective medium theories: the Maxwell-Garnett theory and the Bruggeman theory. In concept, the MG theory describes the effective dielectric constant of a matrix material into which is embedded a large number of very small inclusions of a second material. The Bruggeman theory describes the dielectric constant of a well mixed aggregate of two or more types of materials. Both theories assume that the individual particles are much smaller than the wavelength of the incident radiation. The refractivity for a heterogeneous grain using the MG theory is very similar to the refractivity of the matrix material, even for large volume fractions of the inclusion. The equilibrium grain temperature for spherical particles sized from .001 to 100 microns in radius at 1 astronomical unit from the sun was calculated. Further explanation is given.

  2. Grain boundary wetness of partially molten dunite

    NASA Astrophysics Data System (ADS)

    Mu, S.; Faul, U.

    2013-12-01

    The grain scale melt distribution plays a key role for physical properties of partially molten regions in Earth's upper mantle, but our current understanding of the distribution of basaltic melt at the grain scale is still incomplete. A recent experimental study shows that wetted two-grain boundaries are a common feature of partially molten dunite at small melt fractions (Garapic et al., G3, 2013). In early ideal models which assume isotropic surface energy, the grain scale melt distribution is uniquely determined by knowing the melt fraction and the dihedral angle between two crystalline grains and the melt (von Bargen and Waff, JGR, 1986). Olivine is anisotropic in surface energy, hence the grain scale melt distribution at given melt fraction cannot be characterized by the dihedral angle alone. The grain boundary wetness, which is defined as the ratio of solid-liquid boundary area over the total interfacial area (Takei, JGR, 1998), is a more objective measure of the grain scale melt distribution. The aim of this study is to quantify the relationship between grain size, melt fraction, temperature and grain boundary wetness of partially molten dunite under dry conditions. We annealed olivine-basalt aggregates with melt fractions from 0.03% to 6% at a range of temperatures and 1 GPa in a piston cylinder for 1 to 336 hours, with resulting mean grain sizes of 10 to 60 μm. The samples were sectioned, polished and imaged at high resolution by using a field emission SEM. Each image had a size of 2048 x 1536 pixels with a resolution of 0.014 to 0.029 μm/pixel, depending on magnification. For each sample, depending on grain sizes, we made mosaics of 3 x 3 or 6 x 6 overlapping images. Measurements of melt fraction, grain boundary wetness and grain size were carried out on these high resolution mosaics by using ImageJ software. Analyses of mosaics show that grain boundary wetness increases with increasing melt fraction at constant grain size to values well above those

  3. Ancient whole grain gluten-free flatbreads

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA food guide recommends that at least ½ of all the grains eaten should be whole grains. The FDA allows food Health Claim labels for food containing 51% whole gains and 11 g of dietary fiber. This is the only report demonstrating innovative ancient whole grain gluten-free (no yeast or chemical...

  4. Whole grain gluten-free flat breads

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA food guide recommends that at least ½ of all the grains eaten should be whole grains. The FDA allows food health claim labels for food containing 51% whole gains and 11 g of dietary fiber. This is the only report demonstrating innovative whole grain gluten free (without yeast or chemicals) ...

  5. Single grain heating due to inelasltic cotunneling.

    SciTech Connect

    Glatz, A.; Beloborodov, I. S.; Materials Science Division; Cal State Univ. at Northridge

    2010-01-25

    We study heating effects of a single metallic quantum dot weakly coupled to two leads. The dominant mechanism for heating at low temperatures is due to inelastic electron cotunneling processes. We calculate the grain temperature profile as a function of grain parameters, bias voltage, and time and show that for nanoscale size grains the heating effects are pronounced and easily measurable in experiments.

  6. Weighing in on whole grains: A review of evidence linking whole grains to body weight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    U.S. dietary guidelines support the consumption of whole grains in lieu of refined grains. On January 31, 2011, the 2010 Dietary Guidelines for Americans (DGA) were released and the recommendations with respect to grains were for individuals to “Consume at least half of all grains as whole grains” a...

  7. 75 FR 76254 - Official Performance and Procedural Requirements for Grain Weighing Equipment and Related Grain...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-08

    ... Grain Inspection, Packers and Stockyards Administration 7 CFR Part 802 RIN 0580-AB19 Official Performance and Procedural Requirements for Grain Weighing Equipment and Related Grain Handling Systems AGENCY: Grain Inspection, Packers and Stockyards Administration, USDA. ACTION: Direct final rule. SUMMARY:...

  8. Experimental Study of Dust Grain Charging

    NASA Technical Reports Server (NTRS)

    Spann, James F; Venturini, Catherine C.; Comfort, Richard H.; Mian, Abbas M.

    1999-01-01

    The results of an experimental study of the charging mechanisms of micron size dust grains are presented. Individual dust grains are electrodynamically suspended and exposed to an electron beam of known energy and flux, and to far ultraviolet radiation of known wavelength and intensity. Changes in the charge-to-mass ratio of the grain are directly measured as a function of incident beam (electron and/or photon), grain size and composition. Comparisons of our results to theoretical models that predict the grain response are presented.

  9. Mechanism for diffusion induced grain boundary migration

    SciTech Connect

    Balluffi, R.W.; Cahn, J.W.

    1980-08-01

    Grain boundaries are found to migrate under certain conditions when solute atoms are diffused along them. This phenomenon, termed diffusion induced grain boundary migration (DIGM), has now been found in six systems. The observed phenomenon and empirical data are used to discard certain concepts for the driving force and the mechanism. A mechanism is proposed in which differences in the diffusion coefficients of the diffusing species along the grain boundary cause a self-sustaining climb of grain boundary dislocations and motion of their associated grain boundary steps.

  10. Grain size control of rhenium strip

    NASA Technical Reports Server (NTRS)

    Schuster, Gary B.

    1991-01-01

    Ensuring the desired grain size in the pure Re strip employed by the SP-100 space nuclear reactor design entails the establishment of an initial grain size in the as-received strip and the avoidance of excessive grain growth during subsequent fabrication. Pure Re tapered tensile specimens have been fabricated and tested in order to quantify the effects of grain-boundary migration. Grain size could be rendered fine and uniform by means of a rolling procedure that uses rather large reductions between short intermediate anneals. The critical strain regime varies inversely with annealing temperature.

  11. Grain growth systematics for forsterite + enstatite aggregates

    NASA Astrophysics Data System (ADS)

    Hiraga, T.; Tachibana, C.; Ohashi, N.; Sano, S.

    2009-12-01

    Grain growth kinetics of forsterite (Fo) and enstatite (En) in fine grain aggregates of Fo + En are examined as a function of volume fraction of En (fEn = 0.00 to 0.42). Growth rates fit the equation, d^n-d0^n =k*(t-t0) (d: mean grain diameter; d0: initial grain diameter; n: grain growth exponent; k: growth constant; t: time), where n ~5 for both Fo and En grains, and a negative correlation between kFo and fEn can be expressed as kFo = 0.06*EXP(30*fEn*(fEn-1.1)). In addition, the ratio of dFo/dEn is almost constant during grain growth and its value becomes smaller with increasing fEn, such that, dFo/dEn =0.74/fEn^0.59. Based on our results and published diffusion kinetics for olivine, the rate-controlling process for grain growth is grain boundary diffusion of Si through grain boundaries of forsterite. Extrapolation of our results to the pressure and temperature conditions of the earth’s mantle allows us to determine the relative contribution of the various mineral phases to grain size sensitive creep mechanisms and the stability of localized shear zones.

  12. Spin-related magnetism of interstellar grains

    NASA Technical Reports Server (NTRS)

    Srnka, L. J.; De, B. R.

    1978-01-01

    The magnetic dipole moments and internal magnetic fields due to the spin of electrically charged elongated nonmagnetic interstellar grains in kinetic equilibrium with their surroundings are computed for the grain-size range from 0.01 to 1.0 micron. It is shown that the induced magnetic moments and internal magnetic fields of charged spinning nonmagnetic grains of arbitrary composition and prolate spheroidal shape can be appreciable, possibly even exceeding 0.01 emu/cu cm for 0.01-micron grains. The results indicate that virtually all grains smaller than 0.1 micron in mean diameter, and all elongated grains smaller than about 1 micron in length, are immersed in local magnetic fields due to spin that are much larger than the ambient galactic field. Some implications of this effect are discussed in relation to the polarization of starlight by aligned dust grains and the primordial remanent magnetization found in primitive carbonaceous chondrites.

  13. Effect of anisotropic interfacial energy on grain boundary distributions during grain growth

    SciTech Connect

    Gruber, J. A.; George, D. C.; Kuprat, A. P.; Rohrer, Gregory S.; Rollett, A. D.

    2004-01-01

    Through simulations with the moving finite element program GRAIN3D, we have studied the effect of anisotropic grain boundary energy on the distribution of boundary types in a polycrystal during normal grain growth. An energy function similar to that hypothesized for magnesia was used, and the simulated grain boundary distributions were found to agree well with measured distributions. The simulated results suggest that initially random microstructures develop nearly steady state grain boundary distributions that have local maxima and minima corresponding to local minima and maxima, respectively, of the energy function. It is well known that the properties and area fractions of various grain boundary types in polycrystals have a dramatic effect on macroscopic materials properties. The goal of the present study is to examine the quantitative relation between grain boundary energies and the distribution of grain boundary types that result from grain growth. In keeping with the prior work, we parameterize the five-dimensional space of grain boundary types using three parameters to describe the lattice misorientation and two parameters to describe the orientation of the grain boundary plane. Of particular interest is the observation that at fixed misorientations, there is significant texture in the distribution of the grain boundary planes and planes with low surface energies appear more frequently. Here we use simulation to test the idea that the observed distributions arise because of the grain boundary energy anisotropy. In comparison to the experiments, the simulations are advantageous because they make it possible to monitor the time evolution of the distribution and to independently determine the influence of different grain boundary properties on the development of the distribution. A moving finite element program, GRAIN3D, has been developed with the capability to incorporate anisotropic grain boundary energy and mobility functions into grain growth simulations

  14. Whole grains and health: from theory to practice--highlights of The Grains for Health Foundation's Whole Grains Summit 2012.

    PubMed

    McKeown, Nicola M; Jacques, Paul F; Seal, Chris J; de Vries, Jan; Jonnalagadda, Satya S; Clemens, Roger; Webb, Densie; Murphy, Lee Anne; van Klinken, Jan-Willem; Topping, David; Murray, Robyn; Degeneffe, Dennis; Marquart, Leonard F

    2013-05-01

    The Grains for Health Foundation's Whole Grains Summit, held May 19-22, 2012 in Minneapolis, was the first meeting of its kind to convene >300 scientists, educators, food technologists, grain breeders, food manufacturers, marketers, health professionals, and regulators from around the world. Its goals were to identify potential avenues for collaborative efforts and formulate new approaches to whole-grains research and health communications that support global public health and business. This paper summarizes some of the challenges and opportunities that researchers and nutrition educators face in expanding the knowledge base on whole grains and health and in translating and disseminating that knowledge to consumers. The consensus of the summit was that effective, long-term, public-private partnerships are needed to reach across the globe and galvanize the whole-grains community to collaborate effectively in translating whole-grains science into strategies that increase the availability and affordability of more healthful, grain-based food products. A prerequisite of that is the need to build trust among diverse multidisciplinary professionals involved in the growing, producing, marketing, and regulating of whole-grain products and between the grain and public health communities.

  15. Whole grains and health: from theory to practice--highlights of The Grains for Health Foundation's Whole Grains Summit 2012.

    PubMed

    McKeown, Nicola M; Jacques, Paul F; Seal, Chris J; de Vries, Jan; Jonnalagadda, Satya S; Clemens, Roger; Webb, Densie; Murphy, Lee Anne; van Klinken, Jan-Willem; Topping, David; Murray, Robyn; Degeneffe, Dennis; Marquart, Leonard F

    2013-05-01

    The Grains for Health Foundation's Whole Grains Summit, held May 19-22, 2012 in Minneapolis, was the first meeting of its kind to convene >300 scientists, educators, food technologists, grain breeders, food manufacturers, marketers, health professionals, and regulators from around the world. Its goals were to identify potential avenues for collaborative efforts and formulate new approaches to whole-grains research and health communications that support global public health and business. This paper summarizes some of the challenges and opportunities that researchers and nutrition educators face in expanding the knowledge base on whole grains and health and in translating and disseminating that knowledge to consumers. The consensus of the summit was that effective, long-term, public-private partnerships are needed to reach across the globe and galvanize the whole-grains community to collaborate effectively in translating whole-grains science into strategies that increase the availability and affordability of more healthful, grain-based food products. A prerequisite of that is the need to build trust among diverse multidisciplinary professionals involved in the growing, producing, marketing, and regulating of whole-grain products and between the grain and public health communities. PMID:23514771

  16. Grain alignment in starless cores

    SciTech Connect

    Jones, T. J.; Bagley, M.; Krejny, M.; Andersson, B.-G.; Bastien, P.

    2015-01-01

    We present near-IR polarimetry data of background stars shining through a selection of starless cores taken in the K band, probing visual extinctions up to A{sub V}∼48. We find that P{sub K}/τ{sub K} continues to decline with increasing A{sub V} with a power law slope of roughly −0.5. Examination of published submillimeter (submm) polarimetry of starless cores suggests that by A{sub V}≳20 the slope for P versus τ becomes ∼−1, indicating no grain alignment at greater optical depths. Combining these two data sets, we find good evidence that, in the absence of a central illuminating source, the dust grains in dense molecular cloud cores with no internal radiation source cease to become aligned with the local magnetic field at optical depths greater than A{sub V}∼20. A simple model relating the alignment efficiency to the optical depth into the cloud reproduces the observations well.

  17. Grain Growth in Collapsing Clouds

    NASA Astrophysics Data System (ADS)

    Rossi, S. C. F.; Benevides-Soares, P.; Barbuy, B.

    1990-11-01

    RESUMEN. Se ha considerado un proceso de coagulaci6n de granos en nubes colapsantes de diferentes metalicidades. Se aplicaron los calculos al intervalo de densidades n = lO to , forrespondiendo a la fase isotermica de contracci6n de nubes. A lo largo de esta fase en el colap- so, la temperatura es por lo tanto constante, en donde se alcanza T Q lOKpara nubes de metalicidad solar y T 100 K para nubes de baja metalicidad. El tamano final del grano es mayor para las mayores metali- cidades. ABSTRACT. A process of grain coagulation in collapsing clouds of different metallicities is considered. The calculations are applied to the density range n = 1O to , corresponding to the isothermal phase of cloud contraction. Along this phase in the collapse, the temperature is thus a constant, where T % 10 K for solar-metallicity clouds, and T % 100 K for low metallicity clouds is reached. The final grain size is larger for the higher metallicities. Keq : INTERSTELLAR-CLOUDS - INTERSTELLAR-CRAINS

  18. Triple junction motion and grain microstructure evolution

    SciTech Connect

    Gottstein, G. . E-mail: gottstein@imm.rwth-aachen.de; Ma, Y.; Shvindlerman, L.S.

    2005-03-01

    The classical concepts of grain growth in polycrystals are based on the dominant role of grain boundaries. This is reflected by the well known von Neumann-Mullins relation. According to this approach triple junctions do not affect grain boundary motion, and their role in grain growth is reduced to maintaining the thermodynamically prescribed equilibrium angles at the lines where boundaries meet. In the current study the experimental data of triple junction mobility are considered with respect to the process of grain growth in 2D systems, in particular with regard to the controlling kinetics. When boundary kinetics prevails grain growth in a polycrystal complies with the von Neumann-Mullins relation. When grain growth is governed by the mobility of triple junctions the kinetics change, and the von Neumann-Mullins relation does not hold anymore. This is the more pronounced the smaller the triple junction mobility. We present a generalized theory of 2D grain growth including a limited triple junction mobility. In this concept the criterion {lambda} plays a central role. It reflects the ratio of boundary to triple junction mobility but is proportional to the grain size as well. The generalized von Neumann-Mullins relation can be expressed in terms of {lambda}. For small values of {lambda}, conspicuous changes of microstructure evolution during grain growth and of microstructural stability are predicted. The theoretical predictions are compared to results of computer simulations by a virtual vertex model.

  19. Survival of carbon grains in shocks

    NASA Technical Reports Server (NTRS)

    Seab, C. Gregory

    1990-01-01

    Supernova shocks play a significant part in the life of an interstellar grain. In a typical 10 to the 9th power year lifetime, a grain will be hit by an average of 10 shocks of 100 km s(sup -1) or greater velocity, and even more shocks of lower velocity. Evaluation of the results of this frequent shock processing is complicated by a number of uncertainties, but seems to give about 10 percent destruction of silicate grains and about half that for graphite grains. Because of the frequency of shocking, the mineralogy and sizes of the grain population is predominately determined by shock processing effects, and not by the initial grain nucleation and growth environment. One consequence of the significant role played by interstellar shocks is that a certain fraction (up to 5 percent) of the carbon should be transformed into the diamond phase. Diamond transformation is observed in the laboratory at threshold shock pressures easily obtainable in grain-grain collisions in supernova shocks. Yields for transforming graphite, amorphous carbon, glassy carbon, and other nearly pure carbon solids into diamond are quite high. Impurities up to at least the 10 percent level (for oxygen) are tolerated in the process. The typical size diamond expected from shock transformation agrees well with the observed sizes in the Lewis et al. findings in meteoritic material. Isotropic anomalies already contained in the grain are likely to be retained through the conversion process, while others may be implanted by the shock if the grain is close to the supernova. The meteoritic diamonds are likely to be the results of transformation of carbon grains in grain-grain collisions in supernova shock waves.

  20. Interstellar Silicate Dust: Modeling and Grain Alignment

    NASA Astrophysics Data System (ADS)

    Das, Indrajit

    We examine some aspects of the alignment of silicate dust grains with respect to the interstellar magnetic field. First, we consider possible observational constraints on the magnetic properties of the grains. Second, we investigate the role of collisions with gas atoms and the production of H2 molecules on the grain surface in the alignment process when the grain is drifting in the gaseous medium. Paramagnetism associated with Fe content in the dust is thought to play a critical role in alignment. Min et al (2007) claimed that the Fe content of the silicate dust can be constrained by the shape of the 10 μm extinction feature. They found low Fe abundances, potentially posing problems for grain alignment theories. We revisit this analysis modeling the grains with irregularly shaped Gaussian Random Sphere (GRS). We give a comprehensive review of all the relevant constraints researchers apply and discuss their effects on the inferred mineralogy. Also, we extend this analysis to examine whether constraints can be placed on the presence of Fe-rich inclusions which could yield "super-paramagnetism". This possibility has long been speculated, but so far observational constraints are lacking. Every time a gas atom collides with a grain, the grain's angular momentum is slightly modified. Likewise when an H2 molecule forms on the surface and is ejected. Here also we model the grain with GRS shape and considered various scenarios about how the colliding gas particles depart the grain. We develop theoretical and computational tools to estimate the torques associated with these aforementioned events for a range of grain drift speeds---from low subsonic to high supersonic speeds. Code results were verified with spherical grain for which analytical results were available. Finally, the above torque results were used to study the grain rotational dynamics. Solving dynamical equations we examine how these torques influence the grain alignment process. Our analysis suggests that

  1. Grain boundary segregation and intergranular failure

    SciTech Connect

    White, C.L.

    1980-01-01

    Trace elements and impurities often segregate strongly to grain boundaries in metals and alloys. Concentrations of these elements at grain boundaries are often 10/sup 3/ to 10/sup 5/ times as great as their overall concentration in the alloy. Because of such segregation, certain trace elements can exert a disproportionate influence on material properties. One frequently observed consequence of trace element segregation to grain boundaries is the occurrence of grain boundary failure and low ductility. Less well known are incidences of improved ductility and inhibition of grain boundary fracture resulting from trace element segregation to grain boundaries in certain systems. An overview of trace element segregation and intergranular failure in a variety of alloy systems as well as preliminary results from studies on Al 3% Li will be presented.

  2. Whole grain for whom and why?

    PubMed Central

    Frølich, Wenche; Åman, Per

    2010-01-01

    A definition of whole grain is a critical first step in investigating health claims for whole grain and its products. Today, there is no internationally accepted definition of whole grain. Some existing definitions are broad and commodity-based, including grains with similar end uses, while others are more restricted. Scientific knowledge must be the basis for inclusion of certain grains. It is better to start with a restricted list of grains (a precautionary principle) and extend this as more knowledge becomes available. An exact definition of the raw materials (milled, cracked, crushed, rolled, or flaked) and knowledge of the components providing health effects would appear to be crucial issues for the European authorities when approving health claims. It is important that health claims are evidence-based, sustainable, and officially validated. PMID:20300475

  3. Jamming of Cylindrical Grains in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; Spier, Gregory; Barr, Nicholas; Steel, Fiona

    2012-02-01

    We study jamming of low aspect-ratio cylindrical Delrin grains in a vertical channel. These cylindrical grains resemble antacid tablets, poker chips, or coins since their height is less than their diameter. Grains are allowed to fall through a vertical channel with a square cross section where the channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. Within this channel, grains are sometimes observed to form jams, stable structures supported by the channel walls with no support beneath them. The probability of jam occurrence and the strength or robustness of a jam is effected by the grain dimensions and channel size. We will present experimental measurements of the jamming probability and jam strength in this system and discuss the relationship of these results to other experiments and theories.

  4. Direct observation of grain rotation-induced grain coalescence in two-dimensional colloidal crystals.

    PubMed

    Moore, Lee J; Dear, Richard D; Summers, Michael D; Dullens, Roel P A; Ritchie, Grant A D

    2010-10-13

    A spatially modulated laser is used to produce multiple localized thermal gradients in a colloidal sample placed above a gold surface. We use an optical microscope to observe real time dynamics of the resulting two-dimensional colloidal crystal grains and find that grain rotation-induced grain coalescence (GRIGC) occurs with the rotation of both grains before coalescence. Control over the grain size shows that the time scale for grain boundary annealing in our system is in good agreement with theoretical expressions formulated for nanocrystal growth.

  5. World grain takes a spill.

    PubMed

    Brown, L R

    1992-01-01

    World grain production decreased 5% in 1991, which combined with the 90 million in population increase resulted in a 6.4% decline/person. This is the largest drop ever recorded. Currently world production is off 9% from the all time high in 1984 of 757 pounds/person. There are many signs that this trend will continue. Soil erosion continues to decrease the amount of available farm land, irrigation water logs fields, deforestation and desertification, air pollution, acid rain and increased ultra violet light form depleting ozone are all adding to the problem. Currently in the US 28 million acres idle as part of commodity supply management and 34 million acres are designated threatened and are in Conservation Reserve. However, even with this area put into production, the total area worldwide is still smaller than it was in 1984.

  6. Perennial Grain and Oilseed Crops.

    PubMed

    Kantar, Michael B; Tyl, Catrin E; Dorn, Kevin M; Zhang, Xiaofei; Jungers, Jacob M; Kaser, Joe M; Schendel, Rachel R; Eckberg, James O; Runck, Bryan C; Bunzel, Mirko; Jordan, Nick R; Stupar, Robert M; Marks, M David; Anderson, James A; Johnson, Gregg A; Sheaffer, Craig C; Schoenfuss, Tonya C; Ismail, Baraem; Heimpel, George E; Wyse, Donald L

    2016-04-29

    Historically, agroecosystems have been designed to produce food. Modern societies now demand more from food systems-not only food, fuel, and fiber, but also a variety of ecosystem services. And although today's farming practices are producing unprecedented yields, they are also contributing to ecosystem problems such as soil erosion, greenhouse gas emissions, and water pollution. This review highlights the potential benefits of perennial grains and oilseeds and discusses recent progress in their development. Because of perennials' extended growing season and deep root systems, they may require less fertilizer, help prevent runoff, and be more drought tolerant than annuals. Their production is expected to reduce tillage, which could positively affect biodiversity. End-use possibilities involve food, feed, fuel, and nonfood bioproducts. Fostering multidisciplinary collaborations will be essential for the successful integration of perennials into commercial cropping and food-processing systems. PMID:26789233

  7. Grain boundary wetness of partially molten dunite

    NASA Astrophysics Data System (ADS)

    Mu, Shangshang; Faul, Ulrich H.

    2016-05-01

    Samples of Fo90 olivine and basaltic melt were annealed at a range of temperatures and a pressure of 1 GPa in a piston cylinder apparatus from 1 to 336 h. Post-run samples have melt contents from 0.3 to 6.8 % and mean grain sizes from 4.3 to 84.5 μm. Grain boundary wetness, a measure of the intergranular melt distribution, was determined by analyzing scanning electron microscope images with sufficiently high resolution to detect thin layers wetting grain boundaries, as well as small triple junctions. The measurements show that grain boundary wetness increases with increasing melt content to values well above those predicted by the idealized isotropic equilibrium model for a finite dihedral angle. Additionally, the melt geometry changes with grain size, with grain boundary wetness increasing with increasing grain size at fixed melt content. Grain boundary wetness and dihedral angle of samples annealed at a range of temperatures, but constant melt content does not depend on temperature. These observations emphasize that the dihedral angle alone is not adequate to characterize the melt distribution in partially molten rocks, as the idealized isotropic model does not account for the influence of grain growth. Diffusion creep viscosities calculated from the measured wetness reflect the grain size and melt content dependence. Accordingly, experimentally measured viscosities at small grain sizes underestimate the effect of melt to weaken partially molten rocks for coarser grain sizes. The presence of melt in the mantle may therefore enhance diffusion creep relative to dislocation creep.

  8. Ultrafine-grained titanium for medical implants

    DOEpatents

    Zhu, Yuntian T.; Lowe, Terry C.; Valiev, Ruslan Z.; Stolyarov, Vladimir V.; Latysh, Vladimir V.; Raab, Georgy J.

    2002-01-01

    We disclose ultrafine-grained titanium. A coarse-grained titanium billet is subjected to multiple extrusions through a preheated equal channel angular extrusion (ECAE) die, with billet rotation between subsequent extrusions. The resulting billet is cold processed by cold rolling and/or cold extrusion, with optional annealing. The resulting ultrafine-grained titanium has greatly improved mechanical properties and is used to make medical implants.

  9. The size distribution of interstellar grains

    NASA Technical Reports Server (NTRS)

    Witt, Adolf N.

    1987-01-01

    Three major areas involving interstellar grains were investigated. First, studies were performed of scattering in reflection nebulae with the goal of deriving scattering characteristics of dust grains such as the albedo and the phase function asymmetry throughout the visible and the ultraviolet. Secondly, studies were performed of the wavelength dependence of interstellar extinction designed to demonstrate the wide range of grain size distributions naturally occurring in individual clouds in different parts of the galaxy. And thirdly, studies were also performed of the ultraviolet powered emission of dust grains in the 0.5 to 1.0 micron wavelength range in reflection nebulae. Findings considered of major importance are highlighted.

  10. Global Goss grain growth and grain boundary characteristics in magnetostrictive Galfenol sheets

    NASA Astrophysics Data System (ADS)

    Na, S. M.; Flatau, A. B.

    2013-12-01

    Single Goss grains were globally grown in magnetostrictive Galfenol thin sheets via an abnormal grain growth (AGG) process. The sample behaves like single crystal Galfenol, exhibiting large magnetostriction along the <100> axes. Small variations in surface energy conditions, which were governed by different flow rates of 0.5% H2S gas in argon during annealing, had a significant impact of the development of AGG. AGG with a fully developed Goss (011) grain over 95% of the sample surface is very reproducible and feasible for a broad range of annealing conditions. In addition, the <100> orientation of the single-crystal-like Galfenol sheet aligns exactly with the rolling direction, and produces magnetostriction values of ˜300 ppm. AGG often produces isolated grains inside Goss grains due to anisotropic properties of grain boundaries. To better understand island formation mechanisms, grain orientation and grain boundary characteristics of island grains in Goss-oriented Galfenol thin sheets were also investigated. We examined samples annealed either under an argon atmosphere or under a sulfur atmosphere, and characterized the observed island grain boundaries in terms of grain misorientation angles. Trends in measured and simulated data on misorientation angles indicate that the presence of (001) island grain boundaries with angles higher than 45° can be explained by the high energy grain boundary (HEGB) model, whereas (111) boundaries with intermediate angles (20°-45°) cannot. The role of low energy coincident site lattice (CSL) boundaries on AGG in both annealing cases was found to be negligible.

  11. The Effects of Grain Size and Texture on Dynamic Abnormal Grain Growth in Mo

    NASA Astrophysics Data System (ADS)

    Noell, Philip J.; Taleff, Eric M.

    2016-10-01

    This is the first report of abnormal grain morphologies specific to a Mo sheet material produced from a commercial-purity arc-melted ingot. Abnormal grains initiated and grew during plastic deformation of this material at temperatures of 1793 K and 1813 K (1520 °C and 1540 °C). This abnormal grain growth during high-temperature plastic deformation is termed dynamic abnormal grain growth, DAGG. DAGG in this material readily consumes nearly all grains near the sheet center while leaving many grains near the sheet surface unconsumed. Crystallographic texture, grain size, and other microstructural features are characterized. After recrystallization, a significant through-thickness variation in crystallographic texture exists in this material but does not appear to directly influence DAGG propagation. Instead, dynamic normal grain growth, which may be influenced by texture, preferentially occurs near the sheet surface prior to DAGG. The large grains thus produced near the sheet surface inhibit the subsequent growth of the abnormal grains produced by DAGG, which preferentially consume the finer grains near the sheet center. This produces abnormal grains that span the sheet center but leave unconsumed polycrystalline microstructure near the sheet surface. Abnormal grains are preferentially oriented with the < 110rangle approximately along the tensile axis. These results provide additional new evidence that boundary curvature is the primary driving force for DAGG in Mo.

  12. The Effects of Grain Size and Texture on Dynamic Abnormal Grain Growth in Mo

    NASA Astrophysics Data System (ADS)

    Noell, Philip J.; Taleff, Eric M.

    2016-07-01

    This is the first report of abnormal grain morphologies specific to a Mo sheet material produced from a commercial-purity arc-melted ingot. Abnormal grains initiated and grew during plastic deformation of this material at temperatures of 1793 K and 1813 K (1520 °C and 1540 °C). This abnormal grain growth during high-temperature plastic deformation is termed dynamic abnormal grain growth, DAGG. DAGG in this material readily consumes nearly all grains near the sheet center while leaving many grains near the sheet surface unconsumed. Crystallographic texture, grain size, and other microstructural features are characterized. After recrystallization, a significant through-thickness variation in crystallographic texture exists in this material but does not appear to directly influence DAGG propagation. Instead, dynamic normal grain growth, which may be influenced by texture, preferentially occurs near the sheet surface prior to DAGG. The large grains thus produced near the sheet surface inhibit the subsequent growth of the abnormal grains produced by DAGG, which preferentially consume the finer grains near the sheet center. This produces abnormal grains that span the sheet center but leave unconsumed polycrystalline microstructure near the sheet surface. Abnormal grains are preferentially oriented with the < 110rangle approximately along the tensile axis. These results provide additional new evidence that boundary curvature is the primary driving force for DAGG in Mo.

  13. Effect of Grain Size and Grain Orientation on the Raman Spectra of Minerals

    NASA Technical Reports Server (NTRS)

    Sharma, S. K.; Chio, C. H.; Deb, P.; Lucey, P. G.; Domergue-Schmidt, N.; Horton, K. A.

    2000-01-01

    We have examined effects of grain size and grain orientation on the Raman spectra of quartz and olivine to evaluate the effect of these parameters on in situ and remote analysis of planetary surface rocks.

  14. The Role of Grain Boundary Energy on Grain Boundary Complexion Transitions

    SciTech Connect

    Bojarski, Stephanie A.; Rohrer, Gregory S.

    2014-09-01

    Grain boundary complexions are distinct equilibrium structures and compositions of a grain boundary and complexion transformations are transition from a metastable to an equilibrium complexion at a specific thermodynamic and geometric conditions. Previous work indicates that, in the case of doped alumina, a complexion transition that increased the mobility of transformed boundaries and resulted in abnormal grain growth also caused a decrease in the mean relative grain boundary energy as well as an increase in the anisotropy of the grain boundary character distribution (GBCD). The current work will investigate the hypothesis that the rates of complexion transitions that result in abnormal grain growth (AGG) depend on grain boundary character and energy. Furthermore, the current work expands upon this understanding and tests the hypothesis that it is possible to control when and where a complexion transition occurs by controlling the local grain boundary energy distribution.

  15. Grain Unloading of Arsenic Species in Rice

    SciTech Connect

    Carey, Anne-Marie; Scheckel, Kirk G.; Lombi, Enzo; Newville, Matt; Choi, Yongseong; Norton, Gareth J.; Charnock, John M.; Feldmann, Joerg; Price, Adam H.; Meharg, Andrew A.

    2010-01-11

    Rice (Oryza sativa) is the staple food for over half the world's population yet may represent a significant dietary source of inorganic arsenic (As), a nonthreshold, class 1 human carcinogen. Rice grain As is dominated by the inorganic species, and the organic species dimethylarsinic acid (DMA). To investigate how As species are unloaded into grain rice, panicles were excised during grain filling and hydroponically pulsed with arsenite, arsenate, glutathione-complexed As, or DMA. Total As concentrations in flag leaf, grain, and husk, were quantified by inductively coupled plasma mass spectroscopy and As speciation in the fresh grain was determined by x-ray absorption near-edge spectroscopy. The roles of phloem and xylem transport were investigated by applying a {+-} stem-girdling treatment to a second set of panicles, limiting phloem transport to the grain in panicles pulsed with arsenite or DMA. The results demonstrate that DMA is translocated to the rice grain with over an order magnitude greater efficiency than inorganic species and is more mobile than arsenite in both the phloem and the xylem. Phloem transport accounted for 90% of arsenite, and 55% of DMA, transport to the grain. Synchrotron x-ray fluorescence mapping and fluorescence microtomography revealed marked differences in the pattern of As unloading into the grain between DMA and arsenite-challenged grain. Arsenite was retained in the ovular vascular trace and DMA dispersed throughout the external grain parts and into the endosperm. This study also demonstrates that DMA speciation is altered in planta, potentially through complexation with thiols.

  16. O(minus 2) grain boundary diffusion and grain growth in pure dense MgO

    NASA Technical Reports Server (NTRS)

    Kapadia, C. M.; Leipold, M. H.

    1973-01-01

    Grain growth behavior in fully dense compacts of MgO of very high purity was studied, and the results compared with other similar behaving materials. The activation energy for the intrinsic self-diffusion of Mg(2minus) is discussed along with the grain boundary diffusion of O(2minus). Grain boundary diffusion of O(2minus) is proposed as the controlling mechanism for grain growth.

  17. Irradiation-induced grain growth and defect evolution in nanocrystalline zirconia with doped grain boundaries.

    PubMed

    Dey, Sanchita; Mardinly, John; Wang, Yongqiang; Valdez, James A; Holesinger, Terry G; Uberuaga, Blas P; Ditto, Jeff J; Drazin, John W; Castro, Ricardo H R

    2016-06-22

    Grain boundaries are effective sinks for radiation-induced defects, ultimately impacting the radiation tolerance of nanocrystalline materials (dense materials with nanosized grains) against net defect accumulation. However, irradiation-induced grain growth leads to grain boundary area decrease, shortening potential benefits of nanostructures. A possible approach to mitigate this is the introduction of dopants to target a decrease in grain boundary mobility or a reduction in grain boundary energy to eliminate driving forces for grain growth (using similar strategies as to control thermal growth). Here we tested this concept in nanocrystalline zirconia doped with lanthanum. Although the dopant is observed to segregate to the grain boundaries, causing grain boundary energy decrease and promoting dragging forces for thermally activated boundary movement, irradiation induced grain growth could not be avoided under heavy ion irradiation, suggesting a different growth mechanism as compared to thermal growth. Furthermore, it is apparent that reducing the grain boundary energy reduced the effectiveness of the grain boundary as sinks, and the number of defects in the doped material is higher than in undoped (La-free) YSZ. PMID:27282392

  18. 77 FR 74781 - Safety Zones; Columbia Grain and United Grain Corporation Facilities; Columbia and Willamette Rivers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-18

    ... Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking A... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zones; Columbia Grain and United Grain.... SUMMARY: The Coast Guard is establishing temporary safety zones around the Columbia Grain facility on...

  19. Phloem Transport Of Arsenic Species From Flag Leaf To Grain During Grain Filling

    EPA Science Inventory

    Strategies to reduce arsenic (As) in rice grain, below concentrations that represent a serious human health concern, require that the mechanisms of As accumulation within grain be established. Therefore, retranslocation of As species from flag leaves into filling rice grain was ...

  20. Small grains of truth. [solar system evolution

    NASA Technical Reports Server (NTRS)

    Nuth, Joe

    1991-01-01

    The evidence concerning the formation of the solar nebula from preexisting clouds found in the chemical composition of solar system grains is discussed. Evidence for sequential star formation in the grains is examined. It is argued that there is no model for the origin of the solar system which can account for the increasing complexity of the evidence.

  1. AN ATMOSPHERIC STRUCTURE EQUATION FOR GRAIN GROWTH

    SciTech Connect

    Ormel, C.W.

    2014-07-01

    We present a method to include the evolution of the grain size and grain opacity κ{sub gr} in the equations describing the structure of protoplanetary atmospheres. The key assumption of this method is that a single grain size dominates the grain size distribution at any height r. In addition to following grain growth, the method accounts for mass deposition by planetesimals and grain porosity. We illustrate this method by computation of a simplified atmosphere structure model. In agreement with previous works, grain coagulation is seen to be very efficient. The opacity drops to values much below the often-used ''interstellar medium opacities'' (∼1 cm{sup 2} g{sup –1}) and the atmosphere structure profiles for temperature and density resemble that of the grain-free case. Deposition of planetesimals in the radiative part of the atmosphere hardly influences this outcome as the added surface is quickly coagulated away. We observe a modest dependence on the internal structure (porosity), but show that filling factors cannot become too large because of compression by gas drag.

  2. Chemical composition of distillers grains, a review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In recent years, increasing demand for ethanol as a fuel additive and decreasing dependency on fossil fuels have resulted in a dramatic increase in the amount of grains used for ethanol production. Dry-grind is the major process, resulting in distillers dried grains with solubles (DDGS) as a major ...

  3. Grain transport mechanics in shallow flow

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A physical model based on continuum multiphase flow is described to represent saltating transport of grains in shallow overland flows. The two-phase continuum flow of water and sediment considers coupled St.Venant type equations. The interactive cumulative effect of grains is incorporated by a dispe...

  4. Grain transport mechanics in shallow overland flow

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A physical model based on continuum multiphase flow is described to represent saltating transport of grains in shallow overland flow. The two phase continuum flow of water and sediment considers coupled St.Venant type equations. The interactive cumulative effect of grains is incorporated by a disper...

  5. Analysis of grain quality at receival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With an emphasis on wheat and to a lesser extent, barley, we describe the series of post harvest transfer stages of grain between the first point of sale and the export terminal. At each transfer point, a document accompanies a grain consignment that pertains to its quality (class, purity, sanitatio...

  6. Potential bleaching techniques for corn distillers grains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ethanol industry is booming, and extensive research is now being pursued to develop alternative uses for distillers dried grains (DDG) and distillers dried grains with solubles (DDGS), coproducts of the ethanol production process. Currently, DDG and DDGS are used exclusively as livestock feed. P...

  7. Electronic properties of silicon grain boundaries

    SciTech Connect

    Pike, G.E.; Seager, C.H.

    1980-01-01

    Polycrystalline silicon is a clean and relatively simple prototype of electronic ceramics. The theory of the electrostatic barriers which form at silicon grain boundaries will be discussed. The use of experimental conductance and capacitance measurements to obtain the barrier height and energy density of grain boundary states will be illustrated.

  8. Coarse graining of polystyrene sulfonate

    NASA Astrophysics Data System (ADS)

    Perahia, Dvora; Agrawal, Anupriya; Grest, Gary S.

    2015-03-01

    Capturing large length scales in soft matter while retaining atomistic properties is imperative to computational studies. Here we develop a new coarse-grained model for polystyrene sulfonate (PSS) that often serves as a model system because of its narrow molecular weight distribution and defined degree of sulfonation. Four beads are used to represent polymer where the backbone, the phenyl group, and the sulfonated group are each represented by a different bead and the fourth one represents counterion, which is sodium in our case. Initial atomistic simulations of PSS melt with sulfonation levels of 2-10%, with a dielectric constant ɛ = 1 revealed a ``locked'' phase where motion of the polymer is limited. Dielectric constant of ɛ = 5 was used to accelerate the dynamics. Bonded interactions were obtained using Boltzmann inversion on the bonded distributions extracted from atomistic simulation. Non-bonded interaction of polystyrene monomer was taken from our previous work and potential of mean force was used as the initial guess for interaction of the ionic beads. This set of potential was subsequently iterated to get a good match with radial distribution functions. This potential and its transferability across dielectric constants and temperatures will be presented. Grant DE-SC007908.

  9. Pollen grains for oral vaccination.

    PubMed

    Atwe, Shashwati U; Ma, Yunzhe; Gill, Harvinder Singh

    2014-11-28

    Oral vaccination can offer a painless and convenient method of vaccination. Furthermore, in addition to systemic immunity it has potential to stimulate mucosal immunity through antigen-processing by the gut-associated lymphoid tissues. In this study we propose the concept that pollen grains can be engineered for use as a simple modular system for oral vaccination. We demonstrate feasibility of this concept by using spores of Lycopodium clavatum (clubmoss) (LSs). We show that LSs can be chemically cleaned to remove native proteins to create intact clean hollow LS shells. Empty pollen shells were successfully filled with molecules of different sizes demonstrating their potential to be broadly applicable as a vaccination system. Using ovalbumin (OVA) as a model antigen, LSs formulated with OVA were orally fed to mice. LSs stimulated significantly higher anti-OVA serum IgG and fecal IgA antibodies compared to those induced by use of cholera toxin as a positive-control adjuvant. The antibody response was not affected by pre-neutralization of the stomach acid, and persisted for up to 7 months. Confocal microscopy revealed that LSs can translocate into mouse intestinal wall. Overall, this study lays the foundation of using LSs as a novel approach for oral vaccination.

  10. CHARGING OF AGGREGATE GRAINS IN ASTROPHYSICAL ENVIRONMENTS

    SciTech Connect

    Ma, Qianyu; Matthews, Lorin S.; Hyde, Truell W.; Land, Victor

    2013-02-15

    The charging of dust grains in astrophysical environments has been investigated with the assumption that these grains are homogeneous spheres. However, there is evidence which suggests that many grains in astrophysical environments are irregularly shaped aggregates. Recent studies have shown that aggregates acquire higher charge-to-mass ratios due to their complex structures, which in turn may alter their subsequent dynamics and evolution. In this paper, the charging of aggregates is examined including secondary electron emission and photoemission in addition to primary plasma currents. The results show that the equilibrium charge on aggregates can differ markedly from spherical grains with the same mass, but that the charge can be estimated for a given environment based on structural characteristics of the grain. The 'small particle effect' due to secondary electron emission is also important for de terming the charge of micron-sized aggregates consisting of nano-sized particles.

  11. Recent Progress in Presolar Grain Studies.

    PubMed

    Amari, Sachiko

    2014-01-01

    Presolar grains are stardust that condensed in stellar outflows or stellar ejecta, and was incorporated in meteorites. They remain mostly intact throughout the journey from stars to the earth, keeping information of their birthplaces. Studies of presolar grains, which started in 1987, have produced a wealth of information about nucleosynthesis in stars, mixing in stellar ejecta, and temporal variations of isotopic and elemental abundances in the Galaxy. Recent instrumental advancements in secondary ion mass spectrometry (SIMS) brought about the identification of presolar silicate grains. Isotopic and mineralogical investigations of sub-μm grains have been performed using a combination of SIMS, transmission electron microscopy (TEM) and focused ion beam (FIB) techniques. Two instruments have been developed to study even smaller grains (∼50 nm) and measure isotopes and elements of lower abundances than those in previous studies.

  12. Recent Progress in Presolar Grain Studies.

    PubMed

    Amari, Sachiko

    2014-01-01

    Presolar grains are stardust that condensed in stellar outflows or stellar ejecta, and was incorporated in meteorites. They remain mostly intact throughout the journey from stars to the earth, keeping information of their birthplaces. Studies of presolar grains, which started in 1987, have produced a wealth of information about nucleosynthesis in stars, mixing in stellar ejecta, and temporal variations of isotopic and elemental abundances in the Galaxy. Recent instrumental advancements in secondary ion mass spectrometry (SIMS) brought about the identification of presolar silicate grains. Isotopic and mineralogical investigations of sub-μm grains have been performed using a combination of SIMS, transmission electron microscopy (TEM) and focused ion beam (FIB) techniques. Two instruments have been developed to study even smaller grains (∼50 nm) and measure isotopes and elements of lower abundances than those in previous studies. PMID:26819886

  13. Recent Progress in Presolar Grain Studies

    PubMed Central

    Amari, Sachiko

    2014-01-01

    Presolar grains are stardust that condensed in stellar outflows or stellar ejecta, and was incorporated in meteorites. They remain mostly intact throughout the journey from stars to the earth, keeping information of their birthplaces. Studies of presolar grains, which started in 1987, have produced a wealth of information about nucleosynthesis in stars, mixing in stellar ejecta, and temporal variations of isotopic and elemental abundances in the Galaxy. Recent instrumental advancements in secondary ion mass spectrometry (SIMS) brought about the identification of presolar silicate grains. Isotopic and mineralogical investigations of sub-μm grains have been performed using a combination of SIMS, transmission electron microscopy (TEM) and focused ion beam (FIB) techniques. Two instruments have been developed to study even smaller grains (∼50 nm) and measure isotopes and elements of lower abundances than those in previous studies. PMID:26819886

  14. ISOCHRONS IN PRESOLAR GRAPHITE GRAINS FROM ORGUEIL

    SciTech Connect

    Zinner, Ernst; Jadhav, Manavi

    2013-05-10

    Primitive meteorites contain tiny dust grains that condensed in stellar outflows and explosions. These stardust grains can be extracted from their host meteorites and studied in detail in the laboratory. We investigated depth profiles of the Al-Mg, Ca-K, and Ti-Ca isotopic systems obtained during NanoSIMS isotopic analysis of presolar graphite grains from the CI carbonaceous meteorite Orgueil. Large {sup 26}Al/{sup 27}Al, {sup 41}Ca/{sup 40}Ca, and {sup 44}Ti/{sup 48}Ti ratios, inferred from {sup 26}Mg, {sup 41}K, and {sup 44}Ca excesses from the decay of the short-lived radioisotopes {sup 26}Al, {sup 41}Ca, and {sup 44}Ti, indicate a supernova (SN) origin. From the depth distribution of the radiogenic isotopes and the stable isotopes of their parent elements we constructed isochron-type correlation plots. The plots indicate quantitative retention of radiogenic {sup 26}Mg, {sup 41}K, and {sup 44}Ca in most grains. Deviations from straight lines in the Al-Mg and Ca-K plots can be explained by contamination with {sup 27}Al and isotopically normal Ca, respectively. For the Ti-Ca system in some grains, the lack of parent-daughter correlation indicates either redistribution of radiogenic {sup 44}Ca or heterogeneity in the initial {sup 44}Ti/{sup 48}Ti ratio. We also obtained Si isotopic depth profiles in three graphite grains with large {sup 29}Si and {sup 30}Si excesses, for which a SN origin has been proposed. In two grains no Si-rich subgrains are observed; in the third grain with an apparent Si-rich subgrain the anomalous Si isotopic ratios in the subgrain are the same as in the rest of the graphite host. Our studies show that by measuring depth profiles, information on presolar grains can be obtained that cannot be obtained by whole-grain analysis.

  15. Grain Boundary Effects in Solid Oxide Electrolytes

    NASA Astrophysics Data System (ADS)

    Ng, Mai

    Ion conducting ceramics are essential in applications such as solid oxide fuel cells and oxygen sensors. Traditional 8 mol% yttria-stabilized zirconia (8YSZ) solid oxide electrolytes operate at high temperatures (850°C-1000°C) to achieve high ionic conductivity (> 0.1 Scm-1 at 1000°C) by oxygen ion diffusion via vacancies. Operation at such temperatures requires high temperature electrode materials and shortens device lifetime due to interdiffusion and reactions at electrode/electrolyte interfaces. These concerns drive research in current systems and alternative materials to improve ionic conductivity at reduced operating temperatures. This research considers how grain size and grain boundary phases affect three electrolyte materials with different ion diffusion mechanisms. First, the conductivity of ultra-fine grained two-step sintered and large grained conventional sintered 8YSZ are compared to determine if enhanced ionic conductivity occurs supporting the theory that ion blocking impurities in grain boundaries are diluted with decreasing grain size. Second, apatite-type lanthanide silicates (Ln9.33(SiO4)6O2) which exhibit anisotropic interstitial oxygen diffusion at intermediate temperatures (400°C-800°C) are studied to determine whether grain boundaries detrimentally affect conductivity. Lastly, proton conducting La-monazite (LaPO4) is evaluated to determine the role of Sr-doping (up to 10% substitution of La with Sr) on grain size and conductivity as well as the effect of sintering in air or water vapor on the formation of intergranular phases rich in Sr and P. This research investigates grain boundary effects in three solid oxide electrolyte materials with the goal of understanding how grain boundaries affect ionic conductivity and the atomistic behavior governing these different diffusion mechanisms.

  16. Plant Density Effect on Grain Number and Weight of Two Winter Wheat Cultivars at Different Spikelet and Grain Positions

    PubMed Central

    Ni, Yingli; Zheng, Mengjing; Yang, Dongqing; Jin, Min; Chen, Jin; Wang, Zhenlin; Yin, Yanping

    2016-01-01

    In winter wheat, grain development is asynchronous. The grain number and grain weight vary significantly at different spikelet and grain positions among wheat cultivars grown at different plant densities. In this study, two winter wheat (Triticum aestivum L.) cultivars, ‘Wennong6’ and ‘Jimai20’, were grown under four different plant densities for two seasons, in order to study the effect of plant density on the grain number and grain weight at different spikelet and grain positions. The results showed that the effects of spikelet and grain positions on grain weight varied with the grain number of spikelets. In both cultivars, the single-grain weight of the basal and middle two-grain spikelets was higher at the 2nd grain position than that at the 1st grain position, while the opposite occurred in the top two-grain spikelets. In the three-grain spikelets, the distribution of the single-grain weight was different between cultivars. In the four-grain spikelets of Wennong6, the single-grain weight was the highest at the 2nd grain position, followed by the 1st, 3rd, and 4th grain positions. Regardless of the spikelet and grain positions, the single-grain weight was the highest at the 1st and 2nd grain positions and the lowest at the 3rd and 4th grain positions. Overall, plant density affected the yield by controlling the seed-setting characteristics of the tiller spike. Therefore, wheat yield can be increased by decreasing the sterile basal and top spikelets and enhancing the grain weight at the 3rd and 4th grain positions, while maintaining it at the 1st and 2nd grain positions on the spikelet. PMID:27171343

  17. Abnormal grain growth in Ni-5at.%W

    NASA Astrophysics Data System (ADS)

    Witte, M.; Belde, M.; Barrales Mora, L.; de Boer, N.; Gilges, S.; Klöwer, J.; Gottstein, G.

    2012-12-01

    The growth of abnormally large grains in textured Ni-5at.%W substrates for high-temperature superconductors deteriorates the sharp texture of these materials and thus has to be avoided. Therefore the growth of abnormal grains is investigated and how it is influenced by the grain orientation and the annealing atmosphere. Texture measurements and grain growth simulations show that the grain orientation only matters so far that a high-angle grain boundary exists between an abnormally growing grain and the Cube-orientated matrix grains. The annealing atmosphere has a large influence on abnormal grain growth which is attributed to the differences in oxygen partial pressure.

  18. Phloem transport of arsenic species from flag leaf to grain during grain filling

    SciTech Connect

    Carey, Anne-Marie; Norton, Gareth J.; Deacon, Claire; Scheckel, Kirk G.; Lombi, Enzo; Punshon, Tracy; Guerinot, Mary Lou; Lanzirotti, Antonio; Newville, Matt; Choi, Yongseong; Price, Adam H.; Meharg, Andrew A.

    2011-09-20

    Strategies to reduce arsenic (As) in rice grain, below concentrations that represent a serious human health concern, require that the mechanisms of As accumulation within grain be established. Therefore, retranslocation of As species from flag leaves into filling rice grain was investigated. Arsenic species were delivered through cut flag leaves during grain fill. Spatial unloading within grains was investigated using synchrotron X-ray fluorescence (SXRF) microtomography. Additionally, the effect of germanic acid (a silicic acid analog) on grain As accumulation in arsenite-treated panicles was examined. Dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) were extremely efficiently retranslocated from flag leaves to rice grain; arsenate was poorly retranslocated, and was rapidly reduced to arsenite within flag leaves; arsenite displayed no retranslocation. Within grains, DMA rapidly dispersed while MMA and inorganic As remained close to the entry point. Germanic acid addition did not affect grain As in arsenite-treated panicles. Three-dimensional SXRF microtomography gave further information on arsenite localization in the ovular vascular trace (OVT) of rice grains. These results demonstrate that inorganic As is poorly remobilized, while organic species are readily remobilized, from leaves to grain. Stem translocation of inorganic As may not rely solely on silicic acid transporters.

  19. Phloem Transport of Arsenic Species from Flag Leaf to Grain During Grain Filling

    SciTech Connect

    A Carey; G Norton; C Deacon; K Scheckel; E Lombi; T Punshon; M Guerinot; A Lanzirotti; M Newville; et al.

    2011-12-31

    Strategies to reduce arsenic (As) in rice grain, below concentrations that represent a serious human health concern, require that the mechanisms of As accumulation within grain be established. Therefore, retranslocation of As species from flag leaves into filling rice grain was investigated. Arsenic species were delivered through cut flag leaves during grain fill. Spatial unloading within grains was investigated using synchrotron X-ray fluorescence (SXRF) microtomography. Additionally, the effect of germanic acid (a silicic acid analog) on grain As accumulation in arsenite-treated panicles was examined. Dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) were extremely efficiently retranslocated from flag leaves to rice grain; arsenate was poorly retranslocated, and was rapidly reduced to arsenite within flag leaves; arsenite displayed no retranslocation. Within grains, DMA rapidly dispersed while MMA and inorganic As remained close to the entry point. Germanic acid addition did not affect grain As in arsenite-treated panicles. Three-dimensional SXRF microtomography gave further information on arsenite localization in the ovular vascular trace (OVT) of rice grains. These results demonstrate that inorganic As is poorly remobilized, while organic species are readily remobilized, from leaves to grain. Stem translocation of inorganic As may not rely solely on silicic acid transporters.

  20. Phloem transport of arsenic species from flag leaf to grain during grain filling

    PubMed Central

    Carey, Anne-Marie; Norton, Gareth J.; Deacon, Claire; Scheckel, Kirk G.; Lombi, Enzo; Punshon, Tracy; Guerinot, Mary Lou; Lanzirotti, Antonio; Newville, Matt; Choi, Yongseong; Price, Adam H.; Meharg, Andrew A.

    2013-01-01

    Summary Strategies to reduce arsenic in rice grain, below levels that represent a serious human health concern, require that the mechanisms of arsenic accumulation within grain be established. Therefore, re-translocation of arsenic species from flag leaves into filling rice grain was investigated.Arsenic species were delivered through cut flag leaves during grain fill. Spatial unloading within grains was investigated using synchrotron X-ray fluorescence (SXRF) microtomography. Additionally, the effect of germanic acid (a silicic acid analogue) on grain arsenic accumulation in arsenite treated panicles was examined.Dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) were extremely efficiently re-translocated from flag leaves to rice grain; arsenate was poorly re-translocated, and was rapidly reduced to arsenite within flag leaves; arsenite displayed no re-translocation. Within grains, DMA rapidly dispersed while MMA and inorganic arsenic remained close to the entry point. Germanic acid addition did not affect grain arsenic in arsenite treated panicles. 3D SXRF microtomography gave further information on arsenite localization in the ovular vascular trace (OVT) of rice grains.These results demonstrate that inorganic arsenic is poorly re-mobilized, while organic species are readily re-mobilized, from leaves to grain. Stem translocation of inorganic arsenic may not rely solely on silicic acid transporters. PMID:21658183

  1. Photoluminescence Imaging of Large-Grain CdTe for Grain Boundary Characterization

    SciTech Connect

    Johnston, Steve; Allende Motz, Alyssa; Reese, Matthew O.; Burst, James M.; Metzger, Wyatt K.

    2015-06-14

    In this work, we use photoluminescence (PL) imaging to characterize CdTe grain boundary recombination. We use a silicon megapixel camera and green (532 nm) laser diodes for excitation. A microscope objective lens system is used for high spatial resolution and a field of view down to 190 um x 190 um. PL images of large-grain (5 to 50 um) CdTe samples show grain boundary and grain interior features that vary with processing conditions. PL images of samples in the as-deposited state show distinct dark grain boundaries that suggest high excess carrier recombination. A CdCl2 treatment leads to PL images with very little distinction at the grain boundaries, which illustrates the grain boundary passivation properties. Other process conditions are also shown, along with comparisons of PL images to high spatial resolution time-resolved PL carrier lifetime maps.

  2. Estimating snow grain size using AVIRIS data

    NASA Technical Reports Server (NTRS)

    Nolin, Anne W.; Dozier, Jeff

    1993-01-01

    Estimates of snow grain size for the near-surface snow layer were calculated for the Tioga Pass region and Mammoth Mountain in the Sierra Nevada, California, using an inversion technique and data collected by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The Tioga Pass and Mammoth Mountain single-band AVIRIS radiance images were atmospherically corrected to obtain surface reflectance. A discrete-ordinate model was used to calculate directional reflectance as a function of snowpack grain size for a wide range of snow grain radii. The resulting radius vs. reflectance curves were each fit using a nonlinear least squares technique which provided a means of transforming surface reflectance in each AVIRIS image to optically equivalent grain size on a per-pixel basis. The model results and grain size estimates derived from the AVIRIS data show that, for solar incidence angles between 0 and 30, the technique provides good estimates of grain size. This work provides the first quantitative estimates for grain size using data acquired from an airborne remote sensing instrument and is an important step in improving our ability to retrieve snow physical properties independent of field measurements.

  3. Quasiclassical coarse graining and thermodynamic entropy

    SciTech Connect

    Gell-Mann, Murray; Hartle, James B.

    2007-08-15

    Our everyday descriptions of the universe are highly coarse grained, following only a tiny fraction of the variables necessary for a perfectly fine-grained description. Coarse graining in classical physics is made natural by our limited powers of observation and computation. But in the modern quantum mechanics of closed systems, some measure of coarse graining is inescapable because there are no nontrivial, probabilistic, fine-grained descriptions. This essay explores the consequences of that fact. Quantum theory allows for various coarse-grained descriptions, some of which are mutually incompatible. For most purposes, however, we are interested in the small subset of 'quasiclassical descriptions' defined by ranges of values of averages over small volumes of densities of conserved quantities such as energy and momentum and approximately conserved quantities such as baryon number. The near-conservation of these quasiclassical quantities results in approximate decoherence, predictability, and local equilibrium, leading to closed sets of equations of motion. In any description, information is sacrificed through the coarse graining that yields decoherence and gives rise to probabilities for histories. In quasiclassical descriptions, further information is sacrificed in exhibiting the emergent regularities summarized by classical equations of motion. An appropriate entropy measures the loss of information. For a 'quasiclassical realm' this is connected with the usual thermodynamic entropy as obtained from statistical mechanics. It was low for the initial state of our universe and has been increasing since.

  4. Detection of solute segregation at grain boundaries

    SciTech Connect

    Briceno-Valero, J.; Gronsky, R.

    1980-03-01

    Studies of grain boundary segregation in metallurgical systems are traditionally based upon the premise that grain boundaries are more likely sites for solute atoms than their surrounding grains. This idea is manifested in experimental studies which distinguish the solute concentration at boundaries from that of grain interiors using various spectroscopic techniques, including more recently, energy dispersive x-ray analysis in TEM/STEM instruments. A typical study consists of spot or line scans across a grain boundary plane in order to detect concentration gradients at the boundary region. It has also been pointed out that there are rather severe problems in quantitatively determining the absolute solute concentration within the grain boundary, and data correction schemes for this situation have been proposed. The present paper is concerned with an alternative study of grain boundary segregation where the distribution of solute atoms along the boundary plane (as opposed to that across the boundary plane) is sought. The interest here is to establish whether or not a relationship exists between the structural defect configuration of the boundary plane and site preference for solute segregation.

  5. Interstellar chemical differentiation across grain sizes

    NASA Astrophysics Data System (ADS)

    Ge, J. X.; He, J. H.; Li, Aigen

    2016-07-01

    In this work, we investigate the effects of ion accretion and size-dependent dust temperatures on the abundances of both gas-phase and grain-surface species. While past work has assumed a constant areal density for icy species, we show that this assumption is invalid and the chemical differentiation over grain sizes is significant. We use a gas-grain chemical code to demonstrate this numerically for two typical interstellar conditions: a dark cloud (DC) and a cold neutral medium (CNM). It is shown that, although the grain-size distribution variation (but with the total grain surface area unchanged) has little effect on the gas-phase abundances, it can alter the abundances of some surface species by up to ∼2-4 orders of magnitude. The areal densities of ice species are larger on smaller grains in the DC model as a consequence of ion accretion. However, the surface areal density evolution tracks are more complex in the CNM model due to the combined effects of ion accretion and dust temperature variation. The surface areal density differences between the smallest ( ∼ 0.01 μm) and the biggest ( ∼ 0.2 μm) grains can reach ∼1 and ∼5 orders of magnitude in the DC and CNM models, respectively.

  6. The Search for Interstellar Sulfide Grains

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Messenger, Scott

    2010-01-01

    The lifecycle of sulfur in the galaxy is poorly understood. Fe-sulfide grains are abundant in early solar system materials (e.g. meteorites and comets) and S is highly depleted from the gas phase in cold, dense molecular cloud environments. In stark contrast, sulfur is essentially undepleted from the gas phase in the diffuse interstellar medium, indicating that little sulfur is incorporated into solid grains in this environment. It is widely believed that sulfur is not a component of interstellar dust grains. This is a rather puzzling observation unless Fe-sulfides are not produced in significant quantities in stellar outflows, or their lifetime in the ISM is very short due to rapid destruction. Fe sulfide grains are ubiquitous in cometary samples where they are the dominant host of sulfur. The Fe-sulfides (primarily pyrrhotite; Fe(1-x)S) are common, both as discrete 0.5-10 micron-sized grains and as fine (5-10 nm) nanophase inclusions within amorphous silicate grains. Cometary dust particles contain high abundances of well-preserved presolar silicates and organic matter and we have suggested that they should contain presolar sulfides as well. This hypothesis is supported by the observation of abundant Fe-sulfides grains in dust around pre- and post-main sequence stars inferred from astronomical spectra showing a broad 23 micron IR feature due to FeS. Fe-sulfide grains also occur as inclusions in bona fide circumstellar amorphous silicate grains and as inclusions within deuterium-rich organic matter in cometary dust samples. Our irradiation experiments show that FeS is far more resistant to radiation damage than silicates. Consequently, we expect that Fe sulfide stardust should be as abundant as silicate stardust in solar system materials.

  7. Grain refinement control in TIG arc welding

    NASA Technical Reports Server (NTRS)

    Iceland, W. F.; Whiffen, E. L. (Inventor)

    1975-01-01

    A method for controlling grain size and weld puddle agitation in a tungsten electrode inert gas welding system to produce fine, even grain size and distribution is disclosed. In the method the frequency of dc welding voltage pulses supplied to the welding electrode is varied over a preselected frequency range and the arc gas voltage is monitored. At some frequency in the preselected range the arc gas voltage will pass through a maximum. By maintaining the operating frequency of the system at this value, maximum weld puddle agitation and fine grain structure are produced.

  8. Summary of prior grain entrapment rescue strategies.

    PubMed

    Roberts, M J; Deboy, G R; Field, W E; Maier, D E

    2011-10-01

    Entrapment in flowable agricultural material continues to be a relevant problem facing both farmers and employees of commercial grain storage and handling operations. While considerable work has been done previously on the causes of entrapment in grain and possible preventative measures, there is little research on the efficacy of current first response or extrication techniques. With the recent introduction of new grain rescue equipment and training programs, it was determined that the need exists to document and summarize prior grain rescue strategies with a view to develop evidence-based recommendations that would enhance the efficacy of the techniques used and reduce the risks to both victims and first responders. Utilizing the Purdue University Agricultural Entrapment Database, all data were queried for information related to extrication of victims from grain entrapments documented over the period 1964-2006. Also analyzed were data from other sources, including public records related to entrapments and information from onsite investigations. Significant findings of this study include the following: (1) between 1964 and 2006, the number of entrapments averaged 16 per year, with the frequency increasing over the last decade; (2) of all cases documented, about 45% resulted in fatality; (3) no less than 44% of entrapments occurred in shelled corn; (4) fatality was the result in 82% of cases where victims were submerged beneath the grain surface, while fatality occurred in 10% of cases where victims were only partially engulfed; (5) the majority of rescues were reported to have been conducted by untrained personnel who were at the scene at the time of entrapment; and (6) in those cases where the rescue strategies were known, 56% involved cutting or punching holes in the side walls of the storage structure, 19% involved utilizing onsite fabricated grain retaining walls to extricate partially entrapped victims, and the use of grain vacuum machines as a rescue

  9. Strontium and Barium Isotopes in Type X Presolar Silicon Carbide Grains Analyzed with CHILI — Two Types of Supernova Grains

    NASA Astrophysics Data System (ADS)

    Stephan, T.; Trappitsch, R.; Davis, A. M.; Gyngard, F.; Hoppe, P.; Pellin, M. J.

    2016-08-01

    Using the Chicago Instrument for Laser Ionization, we have measured Sr and Ba isotopes in 10 presolar SiC grains, including 3 X grains. One grain is X1, the other two are X2 grains. Both X grain types show distinct properties in Sr and Ba isotopes.

  10. Parsing abnormal grain growth in specialty aluminas

    NASA Astrophysics Data System (ADS)

    Lawrence, Abigail Kremer

    Grain growth in alumina is strongly affected by the impurities present in the material. Certain impurity elements are known to have characteristic effects on abnormal grain growth in alumina. Specialty alumina powders contain multiple impurity species including MgO, CaO, SiO2, and Na 2O. In this work, sintered samples made from alumina powders containing various amounts of the impurities in question were characterized by their grain size and aspect ratio distributions. Multiple quantitative methods were used to characterize and classify samples with varying microstructures. The grain size distributions were used to partition the grain size population into subpopulations depending on the observed deviation from normal behavior. Using both grain size and aspect ratio a new visual representation for a microstructure was introduced called a morphology frequency map that gives a fingerprint for the material. The number of subpopulations within a sample and the shape of the distribution on the morphology map provided the basis for a classification scheme for different types of microstructures. Also using the two parameters a series of five metrics were calculated that describe the character of the abnormal grains in the sample, these were called abnormal character values. The abnormal character values describe the fraction of grains that are considered abnormal, the average magnitude of abnormality (including both grain size and aspect ratio), the average size, and variance in size. The final metric is the correlation between grain size and aspect ratio for the entire population of grains. The abnormal character values give a sense of how different from "normal" the sample is, given the assumption that a normal sample has a lognormal distribution of grain size and a Gaussian distribution of aspect ratios. In the second part of the work the quantified measures of abnormality were correlated with processing parameters such as composition and heat treatment conditions. A

  11. Optimization of strength and ductility in nanotwinned ultrafine grained Ag: twin density and grain orientations

    SciTech Connect

    Ott, R. T.; Geng, J.; Besser, M. F.; Kramer, M. J.; Wang, Y. M.; Park, E. S.; LeSar, R.; King, A. H.

    2015-06-27

    Nanotwinned ultrafine grained Ag thick films with different twin densities and orientations have been synthesized by magnetron sputtering with a wide-range of deposition rates. The twin boundary (TB) spacings and orientations as well as the grain size for the different deposition conditions have been characterized by both synchrotron X-ray scattering and transmission electron microscopy (TEM). Structural characterization combined with uniaxial tensile tests of the free-standing films reveals a large increase in the yield strength for films deposited at high deposition rates without any accompanying change in the TB spacing – a behavior that is in contrast with what has been reported in the literature. We find that films deposited at lower deposition rates exhibit more randomly oriented grains with a lower overall twin density (averaged over all the grains) than the more heavily twinned grains with strong <111> fiber texture in the films deposited at higher deposition rates. The TB spacing in the twinned grains, however, does not show any significant dependence on the deposition rate. The dependence of the strength and ductility on the twin density and orientations can be described by two different soft deformation modes: 1) untwinned grains and 2) nanowinned grains that are not oriented with <111> along the growth direction. The untwinned grains provide relatively low resistance to slip, and thus decreased strength, while the nanotwinned grains that are not oriented with <111> along the growth direction are softer than nanotwinned grains that are oriented with <111> along the growth direction. We reveal that an ultrafine-grained (150-200 nm) structure consisting of a mixture of nanotwinned (~ 8-12 nm spacing) and untwined grains yields the best combination of high strength and uniform tensile ductility.

  12. Optimization of strength and ductility in nanotwinned ultrafine grained Ag: twin density and grain orientations

    DOE PAGESBeta

    Ott, R. T.; Geng, J.; Besser, M. F.; Kramer, M. J.; Wang, Y. M.; Park, E. S.; LeSar, R.; King, A. H.

    2015-06-27

    Nanotwinned ultrafine grained Ag thick films with different twin densities and orientations have been synthesized by magnetron sputtering with a wide-range of deposition rates. The twin boundary (TB) spacings and orientations as well as the grain size for the different deposition conditions have been characterized by both synchrotron X-ray scattering and transmission electron microscopy (TEM). Structural characterization combined with uniaxial tensile tests of the free-standing films reveals a large increase in the yield strength for films deposited at high deposition rates without any accompanying change in the TB spacing – a behavior that is in contrast with what has beenmore » reported in the literature. We find that films deposited at lower deposition rates exhibit more randomly oriented grains with a lower overall twin density (averaged over all the grains) than the more heavily twinned grains with strong <111> fiber texture in the films deposited at higher deposition rates. The TB spacing in the twinned grains, however, does not show any significant dependence on the deposition rate. The dependence of the strength and ductility on the twin density and orientations can be described by two different soft deformation modes: 1) untwinned grains and 2) nanowinned grains that are not oriented with <111> along the growth direction. The untwinned grains provide relatively low resistance to slip, and thus decreased strength, while the nanotwinned grains that are not oriented with <111> along the growth direction are softer than nanotwinned grains that are oriented with <111> along the growth direction. We reveal that an ultrafine-grained (150-200 nm) structure consisting of a mixture of nanotwinned (~ 8-12 nm spacing) and untwined grains yields the best combination of high strength and uniform tensile ductility.« less

  13. Barium Isotopes in Single Presolar Grains

    NASA Technical Reports Server (NTRS)

    Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2001-01-01

    Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

  14. Large Grain Superconducting RF Cavities at DESY

    SciTech Connect

    Singer, W.; Brinkmann, A.; Ermakov, A.; Iversen, J.; Kreps, G.; Matheisen, A.; Proch, D.; Reschke, D.; Singer, X.; Spiwek, M.; Wen, H.; Brokmeier, H. G.

    2007-08-09

    The DESY R and D program on cavities fabricated from large grain niobium explores the potential of this material for the production of approx. 1000 nine-cell cavities for the European XFEL. The program investigates basic material properties, comparing large grain material to standard sheet niobium, as well as fabrication and preparation aspects. Several single-cell cavities of TESLA shape have been fabricated from large grain niobium. A gradient up to 41 MV/m at Q0 = 1.4{center_dot}1010 (TB = 2K) was measured after electropolishing. The first three large grain nine-cell cavities worldwide have been produced under contract of DESY with ACCEL Instruments Co. The first tests have shown that all three cavities reach an accelerating gradient up to 30 MV/m after BCP (Buffered Chemical Polishing) treatment, what exceeds the XFEL requirements for RF test in the vertical cryostat.

  15. Connectivity in Random Grain Boundary Networks

    SciTech Connect

    Kumar, M; Schuh, C A; King, W E

    2002-10-22

    Mechanical properties of FCC metals and alloys can be improved by exercising control over the population of grain boundary types in the microstructure. The existing studies also suggest that such properties tend to have percolative mechanisms that depend on the topology of the grain boundary network. With the emergence of SEM-based automated electron backscatter diffraction (EBSD), statistically significant datasets of interface crystallography can be analyzed in a routine manner, giving new insight into the topology and percolative properties of grain boundary networks. In this work, we review advanced analysis techniques for EBSD datasets to quantify microstructures in terms of grain boundary character and triple junction distributions, as well as detailed percolation-theory based cluster analysis.

  16. Shock Fabrics in Fine-Grained Micrometeorites

    NASA Astrophysics Data System (ADS)

    Suttle, M. D.; Genge, M. J.; Russell, S. S.

    2016-08-01

    Low grade (S1) shock fabrics are identified in unmelted fine-grained micrometeorites through the presence of aligned dehydration cracks. This study suggests hydrated micrometeorites originate predominantly from rubble-pile asteroids.

  17. Characterization of grain boundaries in silicon

    NASA Technical Reports Server (NTRS)

    Cheng, L. J.; Shyu, C. M.; Stika, K. M.; Daud, T.; Crotty, G. T.

    1983-01-01

    Zero-bias conductance and capacitance measurements at various temperatures were used to study trapped charges and potential barrier height at the boundaries. Deep-level transient spectroscopy (DLTS) was applied to measure the density of states at the boundary. A study of photoconductivity of grain boundaries in p-type silicon demonstrated the applicability of the technique in the measurement of minority carrier recombination velocity at the grain boundary. Enhanced diffusion of phosphorus at grain boundaries in three cast polycrystalline photovoltaic materials was studied. Enhancements for the three were the same, indicating that the properties of boundaries are similar, although grown by different techniques. Grain boundaries capable of enhancing the diffusion were found always to have strong recombination activities; the phenomena could be related to dangling bonds at the boundaries. Evidence that incoherent second-order twins of (111)/(115) type are diffusion-active is presented.

  18. Grain boundary engineering of highly deformable ceramics

    SciTech Connect

    Mecartney, M.L.

    2000-07-01

    Highly deformable ceramics can be created with the addition of intergranular silicate phases. These amorphous intergranular phases can assist in superplastic deformation by relieving stress concentrations and minimizing grain growth if the appropriate intergranular compositions are selected. Examples from 3Y-TZP and 8Y-CSZ ceramics are discussed. The grain boundary chemistry is analyzed by high resolution analytical TEM is found to have a strong influence on the cohesion of the grains both at high temperature and at room temperature. Intergranular phases with a high ionic character and containing large ions with a relatively weak bond strength appear to cause premature failure. In contrast, intergranular phases with a high degree of covalent character and similar or smaller ions than the ceramic and a high ionic bond strength are the best for grain boundary adhesion and prevention of both cavitation at high temperatures and intergranular fracture at room temperature.

  19. Fine-grained zirconium-base material

    DOEpatents

    Van Houten, G.R.

    1974-01-01

    A method is described for making zirconium with inhibited grain growth characteristics, by the process of vacuum melting the zirconium, adding 0.3 to 0.5% carbon, stirring, homogenizing, and cooling. (Official Gazette)

  20. Lifetime grain consumption and breast cancer risk.

    PubMed

    Farvid, Maryam S; Cho, Eunyoung; Eliassen, A Heather; Chen, Wendy Y; Willett, Walter C

    2016-09-01

    We evaluated individual grain-containing foods and whole and refined grain intake during adolescence, early adulthood, and premenopausal years in relation to breast cancer risk in the Nurses' Health Study II. Grain-containing food intakes were reported on a baseline dietary questionnaire (1991) and every 4 years thereafter. Among 90,516 premenopausal women aged 27-44 years, we prospectively identified 3235 invasive breast cancer cases during follow-up to 2013. 44,263 women reported their diet during high school, and from 1998 to 2013, 1347 breast cancer cases were identified among these women. Cox proportional hazards regression was used to estimate relative risks (RR) and 95 % confidence intervals (95 % CI) of breast cancer for individual, whole and refined grain foods. After adjusting for known breast cancer risk factors, adult intake of whole grain foods was associated with lower premenopausal breast cancer risk (highest vs. lowest quintile: RR 0.82; 95 % CI 0.70-0.97; P trend = 0.03), but not postmenopausal breast cancer. This association was no longer significant after further adjustment for fiber intake. The average of adolescent and early adulthood whole grain food intake was suggestively associated with lower premenopausal breast cancer risk (highest vs lowest quintile: RR 0.74; 95 % CI 0.56-0.99; P trend = 0.09). Total refined grain food intake was not associated with risk of breast cancer. Most individual grain-containing foods were not associated with breast cancer risk. The exceptions were adult brown rice which was associated with lower risk of overall and premenopausal breast cancer (for each 2 servings/week: RR 0.94; 95 % CI 0.89-0.99 and RR 0.91; 95 % CI 0.85-0.99, respectively) and adult white bread intake which was associated with increased overall breast cancer risk (for each 2 servings/week: RR 1.02; 95 % CI 1.01-1.04), as well as breast cancer before and after menopause. Further, pasta intake was inversely associated with

  1. Thermomagnetic Stability in Pseudo Single Domain Grains

    NASA Astrophysics Data System (ADS)

    Nagy, Lesleis; Williams, Wyn; Muxworthy, Adrian; Fabian, Karl; Conbhuí, Pádraig Ó.

    2016-04-01

    The reliability of paleomagnetic remanences are well understood for fine grains of magnetite that are single-domain (SD, uniformly magnetized). In particular Néel's theory [1] outlined the thermal energies required to block and unblock magnetic remanences. This lead to determination of thermal stability for magnetization in fine grains as outlined in Pullaiah et. al. [2] and a comprehensive understanding of SD paleomagnetic recordings. It has been known for some time that single domain magnetite is possible only in the grain size range 30 - 80nm, which may only account for a small fraction of the grain size distribution in any rock sample. Indeed rocks are often dominated by grains in the pseudo single domain (PSD) size range, at approximately 80 - 1000nm. Toward the top end of this range multi-domain features begin to dominate. In order to determine thermomagnetic stability in PSD grains we need to identify the energy barriers between all possible pairs of local energy minima (LEM) domain states as a function of both temperature and grain size. We have attempted to do this using the nudged elastic band (NEB) method [3] which searches for minimum energy paths between any given pair of LEM states. Using this technique we have determined, for the first time, complete thermomagnetic stability curves for PSD magnetite. The work presented is at a preliminary stage. However it can be shown that PSD grains of magnetite with simple geometries (e.g. cubes or cuboctahedra) have very few low energy transition paths and the stability is likely to be similar to that observed for SD grains (as expected form experimental observations). The results will provide a basis for a much more rigorous understanding of the fidelity of paleomagnetic signals in assemblages of PSD grains and their ability to retain ancient recordings of the geomagnetic field. References: [1] Néel, Louis. "Théorie du traînage magnétique des ferromagnétiques en grains fins avec applications aux terres

  2. Grain boundary engineering and superstrength of nanocrystals

    NASA Astrophysics Data System (ADS)

    Glezer, A. M.; Stolyarov, V. L.; Tomchuk, A. A.; Shurygina, N. A.

    2016-01-01

    A new paradigm of hardening of nanocrystals is proposed based on the competing influence of various mechanisms of plastic deformation, i.e., dislocation sliding and grain-boundary slip. It has been confirmed using the results of computer modeling and the experimental data that the use of grain boundary engineering on the basis of the proposed ideas makes it possible to enhance substantially the strength of titaniumbased materials up to ultimate (theoretical) values.

  3. Dynamic Abnormal Grain Growth in Molybdenum

    NASA Astrophysics Data System (ADS)

    Worthington, Daniel L.; Pedrazas, Nicholas A.; Noell, Philip J.; Taleff, Eric M.

    2013-11-01

    A new abnormal grain growth phenomenon that occurs only during continuous plastic straining, termed dynamic abnormal grain growth (DAGG), was observed in molybdenum (Mo) at elevated temperature. DAGG was produced in two commercial-purity molybdenum sheets and in a commercial-purity molybdenum wire. Single crystals, centimeters in length, were created in these materials through the DAGG process. DAGG was observed only at temperatures of 1713 K (1440 °C) and above and occurred across the range of strain rates investigated, ~10-5 to 10-4 s-1. DAGG initiates only after a critical plastic strain, which decreases with increasing temperature but is insensitive to strain rate. Following initiation of an abnormal grain, the rate of boundary migration during DAGG is on the order of 10 mm/min. This rapid growth provides a convenient means of producing large single crystals in the solid state. When significant normal grain growth occurs prior to DAGG, island grains result. DAGG was observed in sheet materials with two very different primary recrystallization textures. DAGG grains in Mo favor boundary growth along the tensile axis in a <110> direction, preferentially producing single crystals with orientations from an approximately <110> fiber family of orientations. A mechanism of boundary unpinning is proposed to explain the dependence of boundary migration on plastic straining during DAGG.

  4. Grain growth and experimental deformation of fine-grained ice aggregates

    NASA Astrophysics Data System (ADS)

    Diebold, Sabrina; de Bresser, Hans; Spiers, Chris; Durham, William B.; Stern, Laura

    2010-05-01

    Ice is one of the most abundant materials in our solar system. It is the principal constituent of most of the moons of the outer solar system. Thus, the flow behavior of ice is of great interest when studying geodynamic processes on icy moons. Grain growth is an elementary process that is assumed to be important in the ice sheet layering of planetary moons, where temperatures 100-273 K exist. We concentrate on the questions to what extent grain growth may influence the evolution of strength of deforming ice and if the grain growth process is independent or dependent of deformation. The answers to these questions will help us to quantitatively test the hypothesis that the progressive evolution of the grain (crystal) size distribution of deforming and recrystallizing ice directly affects its rheological behaviour in terms of composite grain-size-sensitive (GSS) and grain-size-insensitive (GSI) creep, and that this might, after time, result in a steady state balance between mechanisms of GSS and GSI creep. We performed static grain growth experiments at different temperatures and a pressure (P) of 1 atm, and deformation experiments at P = 30-100 MPa starting in the GSS-creep field. The starting material ice Ih has a grain size < 2 μm and was generated by a special pressure-release technique described by Stern et al. (1997) resulting in dense ice aggregates. The ice grains of the polycrystalline starting samples were randomly oriented and the material has a porosity of < 0.5%. For the grain growth tests a Hart Scientific temperature bath was filled with d-Limonene as cooling medium. The ice specimens were put into sealed alumina cylinders. For the grain growth tests, temperatures (T) between 213 K and 268 K were chosen. The durations of these tests varied between one day and two weeks. For the deformation experiments, temperatures of > 170 K and strain rates between 10-8 s-1 and 10-4 s-1 were chosen. Grain sizes, grain size distributions and grain topologies were

  5. BHQ revisited (1) - Looking at grain size

    NASA Astrophysics Data System (ADS)

    Heilbronner, Renée; Kilian, Rüdiger; Tullis, Jan

    2016-04-01

    Black Hills Quartzite (BHQ) has been used extensively in experimental rock deformation for numerous studies. Coaxial and general shear experiments have been carried out, for example, to define the dislocation creep regimes of quartz (Hirth & Tullis, 1992), to determine the effect of annealing (Heilbronner & Tullis, 2002) or to study the development of texture and microstructure with strain (Heilbronner & Tullis, 2006). BHQ was also used to determine the widely used quartz piezometer by Stipp & Tullis (2003). Among the microstructure analyses that were performed in those original papers, grain size was usually determined using CIP misorientation images. However, the CIP method (= computer-integrated polarization microscopy, details in Heilbronner and Barrett, 2014) is only capable of detecting the c-axis orientation of optically uniaxial materials and hence is only capable of detecting grain boundaries between grains that differ in c-axis orientation. One of the puzzling results we found (Heilbronner & Tullis, 2006) was that the recrystallized grain size seemed to depend on the crystallographic preferred orientation of the domain. In other words the grain size did not only depend on the flow stress but also on the orientation of the c-axis w/r to the shear direction. At the time, no EBSD analysis (electron back scatter diffraction) was carried out and hence the full crystallographic orientation was not known. In principle it is therefore possible that we missed some grain boundaries (between grains with parallel c-axes) and miscalculated our grain sizes. In the context of recent shear experiments on quartz gouge at the brittle-viscous transition (see Richter et al., this conference), where EBSD is used to measure the recrystallized grain size, we wanted to re-measure the CIP grain sizes of our 2006 samples (deformed in regime 1, 2 and 3 of dislocation) in exactly the same way. In two companion posters we use EBSD orientation imaging to repeat, refine and expand the

  6. Rescue of a patient out of a grain container: the quicksand effect of grain.

    PubMed

    Bahlmann, Ludger; Klaus, Stephan; Heringlake, Matthias; Baumeier, Wolfgang; Schmucker, Peter; Wagner, Klaus F

    2002-04-01

    Grain storage containers not only present inherent dangers to the operators, but also to the rescuers if someone falls in. Here we report the rescue of a patient from a grain container using a novel technique involving a cylinder placed around the patient. This allowed the grain to be sucked out from around the patient and enabled his rescue uninjured. The rescue action was complicated by acute chest pain in the patient while he was submerged in the grain, and a severe asthma attack in the emergency physician. The rescue and the dilemmas encountered are described together with a review of the relevant literature.

  7. A Rare Allele of GS2 Enhances Grain Size and Grain Yield in Rice.

    PubMed

    Hu, Jiang; Wang, Yuexing; Fang, Yunxia; Zeng, Longjun; Xu, Jie; Yu, Haiping; Shi, Zhenyuan; Pan, Jiangjie; Zhang, Dong; Kang, Shujing; Zhu, Li; Dong, Guojun; Guo, Longbiao; Zeng, Dali; Zhang, Guangheng; Xie, Lihong; Xiong, Guosheng; Li, Jiayang; Qian, Qian

    2015-10-01

    Grain size determines grain weight and affects grain quality. Several major quantitative trait loci (QTLs) regulating grain size have been cloned; however, our understanding of the underlying mechanism that regulates the size of rice grains remains fragmentary. Here, we report the cloning and characterization of a dominant QTL, grain size on chromosome 2 (GS2), which encodes Growth-Regulating Factor 4 (OsGRF4), a transcriptional regulator. GS2 localizes to the nucleus and may act as a transcription activator. A rare mutation of GS2 affecting the binding site of a microRNA, OsmiR396c, causes elevated expression of GS2/OsGRF4. The increase in GS2 expression leads to larger cells and increased numbers of cells, which thus enhances grain weight and yield. The introduction of this rare allele of GS2/OsGRF4 into rice cultivars could significantly enhance grain weight and increase grain yield, with possible applications in breeding high-yield rice varieties.

  8. Orientation influence on grain size-effects in ultrafine-grained magnesium

    SciTech Connect

    Fan, Haidong; Aubry, Sylvie; Arsenlis, A.; El-Awady, Jaafar

    2014-11-08

    The mechanical behavior of ultrafine-grained magnesium was studied by discrete dislocation dynamics (DDD) simulations. Our results show basal slip yields a strong size effect, while prismatic and pyramidal slips produce a weak one. We developed a new size-strength model that considers dislocation transmission across grain boundaries. Good agreement between this model, current DDD simulations and previous experiments is observed. These results reveal that the grain size effect depends on 3 factors: Peierls stress, dislocation source strength and grain boundary strength.

  9. Organic Wheat Farming Improves Grain Zinc Concentration.

    PubMed

    Helfenstein, Julian; Müller, Isabel; Grüter, Roman; Bhullar, Gurbir; Mandloi, Lokendra; Papritz, Andreas; Siegrist, Michael; Schulin, Rainer; Frossard, Emmanuel

    2016-01-01

    Zinc (Zn) nutrition is of key relevance in India, as a large fraction of the population suffers from Zn malnutrition and many soils contain little plant available Zn. In this study we compared organic and conventional wheat cropping systems with respect to DTPA (diethylene triamine pentaacetic acid)-extractable Zn as a proxy for plant available Zn, yield, and grain Zn concentration. We analyzed soil and wheat grain samples from 30 organic and 30 conventional farms in Madhya Pradesh (central India), and conducted farmer interviews to elucidate sociological and management variables. Total and DTPA-extractable soil Zn concentrations and grain yield (3400 kg ha-1) did not differ between the two farming systems, but with 32 and 28 mg kg-1 respectively, grain Zn concentrations were higher on organic than conventional farms (t = -2.2, p = 0.03). Furthermore, multiple linear regression analyses revealed that (a) total soil zinc and sulfur concentrations were the best predictors of DTPA-extractable soil Zn, (b) Olsen phosphate taken as a proxy for available soil phosphorus, exchangeable soil potassium, harvest date, training of farmers in nutrient management, and soil silt content were the best predictors of yield, and (c) yield, Olsen phosphate, grain nitrogen, farmyard manure availability, and the type of cropping system were the best predictors of grain Zn concentration. Results suggested that organic wheat contained more Zn despite same yield level due to higher nutrient efficiency. Higher nutrient efficiency was also seen in organic wheat for P, N and S. The study thus suggests that appropriate farm management can lead to competitive yield and improved Zn concentration in wheat grains on organic farms.

  10. Organic Wheat Farming Improves Grain Zinc Concentration

    PubMed Central

    Helfenstein, Julian; Müller, Isabel; Grüter, Roman; Bhullar, Gurbir; Mandloi, Lokendra; Papritz, Andreas; Siegrist, Michael; Schulin, Rainer; Frossard, Emmanuel

    2016-01-01

    Zinc (Zn) nutrition is of key relevance in India, as a large fraction of the population suffers from Zn malnutrition and many soils contain little plant available Zn. In this study we compared organic and conventional wheat cropping systems with respect to DTPA (diethylene triamine pentaacetic acid)-extractable Zn as a proxy for plant available Zn, yield, and grain Zn concentration. We analyzed soil and wheat grain samples from 30 organic and 30 conventional farms in Madhya Pradesh (central India), and conducted farmer interviews to elucidate sociological and management variables. Total and DTPA-extractable soil Zn concentrations and grain yield (3400 kg ha-1) did not differ between the two farming systems, but with 32 and 28 mg kg-1 respectively, grain Zn concentrations were higher on organic than conventional farms (t = -2.2, p = 0.03). Furthermore, multiple linear regression analyses revealed that (a) total soil zinc and sulfur concentrations were the best predictors of DTPA-extractable soil Zn, (b) Olsen phosphate taken as a proxy for available soil phosphorus, exchangeable soil potassium, harvest date, training of farmers in nutrient management, and soil silt content were the best predictors of yield, and (c) yield, Olsen phosphate, grain nitrogen, farmyard manure availability, and the type of cropping system were the best predictors of grain Zn concentration. Results suggested that organic wheat contained more Zn despite same yield level due to higher nutrient efficiency. Higher nutrient efficiency was also seen in organic wheat for P, N and S. The study thus suggests that appropriate farm management can lead to competitive yield and improved Zn concentration in wheat grains on organic farms. PMID:27537548

  11. The HEALTHGRAIN definition of 'whole grain'.

    PubMed

    van der Kamp, Jan Willem; Poutanen, Kaisa; Seal, Chris J; Richardson, David P

    2014-01-01

    Most cereal products, like white bread, pasta, and biscuits, are based on flour after removal of bran and germ, the two parts of grain kernels containing most of the dietary fibre and other bioactive components. In the past decade, consumers have been rediscovering whole grain-based products and the number of wholegrain products has increased rapidly. In most countries in Europe and worldwide, however, no legally endorsed definition of wholegrain flour and products exists. Current definitions are often incomplete, lacking descriptions of the included grains and the permitted flour manufacturing processes. The consortium of the HEALTHGRAIN EU project (FP6-514008, 2005-2010) identified the need for developing a definition of whole grain with the following scope: 1) more comprehensive than current definitions in most EU countries; 2) one definition for Europe - when possible equal to definitions outside Europe; 3) reflecting current industrial practices for production of flours and consumer products; 4) useful in the context of nutritional guidelines and for labelling purposes. The definition was developed in a range of discussion meetings and consultations and was launched in 2010 at the end of the HEALTHGRAIN project. The grains included are specified: a wide range of cereal grains from the Poaceae family, and the pseudo-cereals amaranth, buckwheat, quinoa, and wild rice. The definition also describes manufacturing processes allowed for producing wholegrain flours. This paper compares the HEALTHGRAIN definition with previous definitions, provides more comprehensive explanations than in the definition itself regarding the inclusion of specific grains, and sets out the permitted flour manufacturing processes.

  12. Organic Wheat Farming Improves Grain Zinc Concentration.

    PubMed

    Helfenstein, Julian; Müller, Isabel; Grüter, Roman; Bhullar, Gurbir; Mandloi, Lokendra; Papritz, Andreas; Siegrist, Michael; Schulin, Rainer; Frossard, Emmanuel

    2016-01-01

    Zinc (Zn) nutrition is of key relevance in India, as a large fraction of the population suffers from Zn malnutrition and many soils contain little plant available Zn. In this study we compared organic and conventional wheat cropping systems with respect to DTPA (diethylene triamine pentaacetic acid)-extractable Zn as a proxy for plant available Zn, yield, and grain Zn concentration. We analyzed soil and wheat grain samples from 30 organic and 30 conventional farms in Madhya Pradesh (central India), and conducted farmer interviews to elucidate sociological and management variables. Total and DTPA-extractable soil Zn concentrations and grain yield (3400 kg ha-1) did not differ between the two farming systems, but with 32 and 28 mg kg-1 respectively, grain Zn concentrations were higher on organic than conventional farms (t = -2.2, p = 0.03). Furthermore, multiple linear regression analyses revealed that (a) total soil zinc and sulfur concentrations were the best predictors of DTPA-extractable soil Zn, (b) Olsen phosphate taken as a proxy for available soil phosphorus, exchangeable soil potassium, harvest date, training of farmers in nutrient management, and soil silt content were the best predictors of yield, and (c) yield, Olsen phosphate, grain nitrogen, farmyard manure availability, and the type of cropping system were the best predictors of grain Zn concentration. Results suggested that organic wheat contained more Zn despite same yield level due to higher nutrient efficiency. Higher nutrient efficiency was also seen in organic wheat for P, N and S. The study thus suggests that appropriate farm management can lead to competitive yield and improved Zn concentration in wheat grains on organic farms. PMID:27537548

  13. Soil grain analyses at Meridiani Planum, Mars

    USGS Publications Warehouse

    Weitz, C.M.; Anderson, R.C.; Bell, J.F.; Farrand, W. H.; Herkenhoff, K. E.; Johnson, J. R.; Jolliff, B.L.; Morris, R.V.; Squyres, S. W.; Sullivan, R.J.

    2006-01-01

    Grain-size analyses of the soils at Meridiani Planum have been used to identify rock souces for the grains and provide information about depositional processes under past and current conditions. Basaltic sand, dust, millimeter-size hematite-rich spherules interpreted as concretions, spherule fragments, coated partially buried spherules, basalt fragments, sedimentary outcrop fragments, and centimeter-size cobbles are concentrated on the upper surfaces of the soils as a lag deposit, while finer basaltic sands and dust dominate the underlying soils. There is a bimodal distribution of soil grain sizes with one population representing grains <125 ??m and the other falling between 1-4.5 mm. Soils within craters like Eagle and Endurance show a much greater diversity of grain morphologies compared to the plains. The spherules found in the plains soils are approximately 1-2 mm smaller in size than those seen embedded in the outcrop rocks of Eagle and Endurance craters. The average major axis for all unfractured spherules measured in the soils and outcrop rocks is 2.87 ?? 1.18 mm, with a trend toward decreasing spherule sizes in both the soils and outcrop rocks as the rover drove southward. Wind ripples seen across the plains of Meridiani are dominated by similar size (1.3-1.7 mm) hematite-rich grains, and they match in size the larger grains on plains ripples at Gusev Crater. Larger clasts and centimeter-size cobbles that are scattered on the soils have several spectral and compositional types, reflecting multiple origins. The cobbles tend to concentrate within ripple troughs along the plains and in association with outcrop exposures. Copyright 2006 by the American Geophysical Union.

  14. The HEALTHGRAIN definition of 'whole grain'.

    PubMed

    van der Kamp, Jan Willem; Poutanen, Kaisa; Seal, Chris J; Richardson, David P

    2014-01-01

    Most cereal products, like white bread, pasta, and biscuits, are based on flour after removal of bran and germ, the two parts of grain kernels containing most of the dietary fibre and other bioactive components. In the past decade, consumers have been rediscovering whole grain-based products and the number of wholegrain products has increased rapidly. In most countries in Europe and worldwide, however, no legally endorsed definition of wholegrain flour and products exists. Current definitions are often incomplete, lacking descriptions of the included grains and the permitted flour manufacturing processes. The consortium of the HEALTHGRAIN EU project (FP6-514008, 2005-2010) identified the need for developing a definition of whole grain with the following scope: 1) more comprehensive than current definitions in most EU countries; 2) one definition for Europe - when possible equal to definitions outside Europe; 3) reflecting current industrial practices for production of flours and consumer products; 4) useful in the context of nutritional guidelines and for labelling purposes. The definition was developed in a range of discussion meetings and consultations and was launched in 2010 at the end of the HEALTHGRAIN project. The grains included are specified: a wide range of cereal grains from the Poaceae family, and the pseudo-cereals amaranth, buckwheat, quinoa, and wild rice. The definition also describes manufacturing processes allowed for producing wholegrain flours. This paper compares the HEALTHGRAIN definition with previous definitions, provides more comprehensive explanations than in the definition itself regarding the inclusion of specific grains, and sets out the permitted flour manufacturing processes. PMID:24505218

  15. Effect of grain colour gene (R) on grain dormancy and sensitivity of the embryo to abscisic acid (ABA) in wheat.

    PubMed

    Himi, Eiko; Mares, Daryl J; Yanagisawa, Akira; Noda, Kazuhiko

    2002-07-01

    The level of grain dormancy and sensitivity to ABA of the embryo, a key factor in grain dormancy, were examined in developing grains of a white-grained wheat line, Novosibirskaya 67 (NS-67), and its red-grained near-isogenic lines (ANK-1A to -1D); a red-grained line, AUS 1490, and its white-grained mutant line (EMS-AUS). ANK lines showed higher levels of grain dormancy than NS-67 at harvest maturity. AUS 1490 grain also showed higher dormancy than EMS-AUS grain. These results suggest that the R gene for grain colour can enhance grain dormancy. However, the dormancy effect conferred by the R gene was not large, suggesting that it plays a minor role in the development of grain dormancy. Water extracts of AUS 1490 and EMS-AUS bran contained germination inhibitors equivalent to 1-10 microM ABA, although there was no difference in the amount of inhibitors between AUS 1490 and EMS-AUS. Thus, the grain colour gene of AUS 1490 did not appear to enhance the level of grain dormancy by accumulating germination inhibitors in its bran. Sensitivity to ABA of embryos was higher in grains collected around harvest-maturity for ANK lines and AUS 1490, compared with NS-67 and EMS-AUS. The R gene might enhance grain dormancy by increasing the sensitivity of embryos to ABA.

  16. Interstellar grain chemistry and organic molecules

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Sandford, S. A.

    1990-01-01

    The detection of prominant infrared absorption bands at 3250, 2170, 2138, 1670 and 1470 cm(-1) (3.08, 4.61, 4.677, 5.99 and 6.80 micron m) associated with molecular clouds show that mixed molecular (icy) grain mantles are an important component of the interstellar dust in the dense interstellar medium. These ices, which contain many organic molecules, may also be the production site of the more complex organic grain mantles detected in the diffuse interstellar medium. Theoretical calculations employing gas phase as well as grain surface reactions predict that the ices should be dominated only by the simple molecules H2O, H2CO, N2, CO, O2, NH3, CH4, possibly CH3OH, and their deuterated counterparts. However, spectroscopic observations in the 2500 to 1250 cm(-1)(4 to 8 micron m) range show substantial variation from source reactions alone. By comparing these astronomical spectra with the spectra of laboratory-produced analogs of interstellar ices, one can determine the composition and abundance of the materials frozen on the grains in dense clouds. Experiments are described in which the chemical evolution of an interstellar ice analog is determined during irradiation and subsequent warm-up. Particular attention is paid to the types of moderately complex organic materials produced during these experiments which are likely to be present in interstellar grains and cometary ices.

  17. Colloidal crystal grain boundary formation and motion.

    PubMed

    Edwards, Tara D; Yang, Yuguang; Beltran-Villegas, Daniel J; Bevan, Michael A

    2014-01-01

    The ability to assemble nano- and micro- sized colloidal components into highly ordered configurations is often cited as the basis for developing advanced materials. However, the dynamics of stochastic grain boundary formation and motion have not been quantified, which limits the ability to control and anneal polycrystallinity in colloidal based materials. Here we use optical microscopy, Brownian Dynamic simulations, and a new dynamic analysis to study grain boundary motion in quasi-2D colloidal bicrystals formed within inhomogeneous AC electric fields. We introduce "low-dimensional" models using reaction coordinates for condensation and global order that capture first passage times between critical configurations at each applied voltage. The resulting models reveal that equal sized domains at a maximum misorientation angle show relaxation dominated by friction limited grain boundary diffusion; and in contrast, asymmetrically sized domains with less misorientation display much faster grain boundary migration due to significant thermodynamic driving forces. By quantifying such dynamics vs. compression (voltage), kinetic bottlenecks associated with slow grain boundary relaxation are understood, which can be used to guide the temporal assembly of defect-free single domain colloidal crystals.

  18. Advantageous grain boundaries in iron pnictide superconductors

    PubMed Central

    Katase, Takayoshi; Ishimaru, Yoshihiro; Tsukamoto, Akira; Hiramatsu, Hidenori; Kamiya, Toshio; Tanabe, Keiichi; Hosono, Hideo

    2011-01-01

    High critical temperature superconductors have zero power consumption and could be used to produce ideal electric power lines. The principal obstacle in fabricating superconducting wires and tapes is grain boundaries—the misalignment of crystalline orientations at grain boundaries, which is unavoidable for polycrystals, largely deteriorates critical current density. Here we report that high critical temperature iron pnictide superconductors have advantages over cuprates with respect to these grain boundary issues. The transport properties through well-defined bicrystal grain boundary junctions with various misorientation angles (θGB) were systematically investigated for cobalt-doped BaFe2As2 (BaFe2As2:Co) epitaxial films fabricated on bicrystal substrates. The critical current density through bicrystal grain boundary (JcBGB) remained high (>1 MA cm−2) and nearly constant up to a critical angle θc of ∼9°, which is substantially larger than the θc of ∼5° for YBa2Cu3O7–δ. Even at θGB>θc, the decay of JcBGB was much slower than that of YBa2Cu3O7–δ. PMID:21811238

  19. Mycological and mycotoxicological evaluation of grain.

    PubMed

    Baliukoniene, Violeta; Bakutis, Bronius; Stankevicius, Henrikas

    2003-01-01

    Grain storage conditions affect its quality. In Lithuania, different types of farms have various harvesting, processing and storing conditions. Grain samples were tested from agricultural granaries of 3 different types with different grain storage conditions in Lithuania. During March-April in 2001 the investigation on mycological and mycotoxicological state of stored grain from different types of agricultural granaries were performed. Wheat (Triticum aestivum L.) samples (n = 33) were tested from small, medium and large granaries. Barley (Hordeum distichon L.) (n = 22) was tested from small and medium granaries. Considering this issue, 31 species of micromycetes ascribed to 8 genera were isolated and identified. The results obtained indicate that highest levels of micromycetes contamination are found in small granaries with good storing and drying equipment. Micromycetes of some species belonging to the Penicillium Link, Aspergillus Mich. Ex Fr., Fusarium Link, and other genera, are able to produce secondary metabolites - mycotoxins of various compositions that are toxic to plants, animals, and humans. The levels of mycotoxins zearalenone and ochratoxin A were established. The highest concentration of zearalenone and ochratoxin A were found in grains from small farm granaries.

  20. The Theory of Ultra Coarse-graining

    NASA Astrophysics Data System (ADS)

    Voth, Gregory

    2013-03-01

    Coarse-grained (CG) models provide a computationally efficient means to study biomolecular and other soft matter processes involving large numbers of atoms correlated over distance scales of many covalent bond lengths and long time scales. Variational methods based on information from simulations of finer-grained (e.g., all-atom) models, for example the multiscale coarse-graining (MS-CG) and relative entropy minimization methods, provide attractive tools for the systematic development of CG models. However, these methods have important drawbacks when used in the ``ultra coarse-grained'' (UCG) regime, e.g., at a resolution level coarser or much coarser than one amino acid residue per effective CG particle in proteins. This is due to the possible existece of multiple metastable states ``within'' the CG sites for a given UCG model configuration. In this talk I will describe systematic variational UCG methods specifically designed to CG entire protein domains and subdomains into single effective CG particles. This is accomplished by augmenting existing effective particle CG schemes to allow for discrete state transitions and configuration-dependent resolution. Additionally, certain conclusions of this work connect back to single-state force matching and open up new avenues for method development in that area. These results provide a formal statistical mechanical basis for UCG methods related to force matching and relative entropy CG methods and suggest practical algorithms for constructing optimal approximate UCG models from fine-grained simulation data.

  1. Porphyrins in the interstellar medium (in grains)

    NASA Technical Reports Server (NTRS)

    Johnson, Fred M.

    1994-01-01

    Spectral sensitivity of the chromophores to their immediate chemical environment establishes some of the chemical constituents of the grains in which they reside. These are: (1) Paraffins, such as, octane, nonane, decane, and others...(needed for Shpolskii matrices and producing quasilines); and (2) Pyridine. The presence of pyridine is required not only to produce the spectral DIB matching, but also to produce the 36 cm(sup -1) crystal field splitting of the S(sub 1) electronic state. The presence of pyridine in the grains can be confirmed spectroscopically. Pyridine produces a transmission window at 2175 A, matching exactly the well known UV hump. On grain reflection, some of the incoming UV radiation is absorbed into the grain's outer layers. Spikes in the lab and in the astronomical data are due to vibronic transitions in pyridine. The lab spectroscopy reported here clearly establishes the presence of MgTBP, H2TPB, and pyridine in the interstellar grains. The high fluorescence efficiency of MgTBP (being optically pumped in the visible) apparently accounts for all the observed UIR emissions.

  2. Activation of Big Grain1 significantly improves grain size by regulating auxin transport in rice.

    PubMed

    Liu, Linchuan; Tong, Hongning; Xiao, Yunhua; Che, Ronghui; Xu, Fan; Hu, Bin; Liang, Chengzhen; Chu, Jinfang; Li, Jiayang; Chu, Chengcai

    2015-09-01

    Grain size is one of the key factors determining grain yield. However, it remains largely unknown how grain size is regulated by developmental signals. Here, we report the identification and characterization of a dominant mutant big grain1 (Bg1-D) that shows an extra-large grain phenotype from our rice T-DNA insertion population. Overexpression of BG1 leads to significantly increased grain size, and the severe lines exhibit obviously perturbed gravitropism. In addition, the mutant has increased sensitivities to both auxin and N-1-naphthylphthalamic acid, an auxin transport inhibitor, whereas knockdown of BG1 results in decreased sensitivities and smaller grains. Moreover, BG1 is specifically induced by auxin treatment, preferentially expresses in the vascular tissue of culms and young panicles, and encodes a novel membrane-localized protein, strongly suggesting its role in regulating auxin transport. Consistent with this finding, the mutant has increased auxin basipetal transport and altered auxin distribution, whereas the knockdown plants have decreased auxin transport. Manipulation of BG1 in both rice and Arabidopsis can enhance plant biomass, seed weight, and yield. Taking these data together, we identify a novel positive regulator of auxin response and transport in a crop plant and demonstrate its role in regulating grain size, thus illuminating a new strategy to improve plant productivity. PMID:26283354

  3. Reaction of sorghum hybrids to anthracnose, grain mold and grain weathering in Burleson County, Texas, 2007

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thirty commercial hybrids were evaluated for resistance against anthracnose, caused by Colletotrichum sublineolum and grain mold or grain weathering caused by a number of fungal species at the Texas A&M University Agricultural Experiment Station in College Station (Burleson County). Six hybrids wer...

  4. Activation of Big Grain1 significantly improves grain size by regulating auxin transport in rice.

    PubMed

    Liu, Linchuan; Tong, Hongning; Xiao, Yunhua; Che, Ronghui; Xu, Fan; Hu, Bin; Liang, Chengzhen; Chu, Jinfang; Li, Jiayang; Chu, Chengcai

    2015-09-01

    Grain size is one of the key factors determining grain yield. However, it remains largely unknown how grain size is regulated by developmental signals. Here, we report the identification and characterization of a dominant mutant big grain1 (Bg1-D) that shows an extra-large grain phenotype from our rice T-DNA insertion population. Overexpression of BG1 leads to significantly increased grain size, and the severe lines exhibit obviously perturbed gravitropism. In addition, the mutant has increased sensitivities to both auxin and N-1-naphthylphthalamic acid, an auxin transport inhibitor, whereas knockdown of BG1 results in decreased sensitivities and smaller grains. Moreover, BG1 is specifically induced by auxin treatment, preferentially expresses in the vascular tissue of culms and young panicles, and encodes a novel membrane-localized protein, strongly suggesting its role in regulating auxin transport. Consistent with this finding, the mutant has increased auxin basipetal transport and altered auxin distribution, whereas the knockdown plants have decreased auxin transport. Manipulation of BG1 in both rice and Arabidopsis can enhance plant biomass, seed weight, and yield. Taking these data together, we identify a novel positive regulator of auxin response and transport in a crop plant and demonstrate its role in regulating grain size, thus illuminating a new strategy to improve plant productivity.

  5. Activation of Big Grain1 significantly improves grain size by regulating auxin transport in rice

    PubMed Central

    Liu, Linchuan; Tong, Hongning; Xiao, Yunhua; Che, Ronghui; Xu, Fan; Hu, Bin; Liang, Chengzhen; Chu, Jinfang; Li, Jiayang; Chu, Chengcai

    2015-01-01

    Grain size is one of the key factors determining grain yield. However, it remains largely unknown how grain size is regulated by developmental signals. Here, we report the identification and characterization of a dominant mutant big grain1 (Bg1-D) that shows an extra-large grain phenotype from our rice T-DNA insertion population. Overexpression of BG1 leads to significantly increased grain size, and the severe lines exhibit obviously perturbed gravitropism. In addition, the mutant has increased sensitivities to both auxin and N-1-naphthylphthalamic acid, an auxin transport inhibitor, whereas knockdown of BG1 results in decreased sensitivities and smaller grains. Moreover, BG1 is specifically induced by auxin treatment, preferentially expresses in the vascular tissue of culms and young panicles, and encodes a novel membrane-localized protein, strongly suggesting its role in regulating auxin transport. Consistent with this finding, the mutant has increased auxin basipetal transport and altered auxin distribution, whereas the knockdown plants have decreased auxin transport. Manipulation of BG1 in both rice and Arabidopsis can enhance plant biomass, seed weight, and yield. Taking these data together, we identify a novel positive regulator of auxin response and transport in a crop plant and demonstrate its role in regulating grain size, thus illuminating a new strategy to improve plant productivity. PMID:26283354

  6. Whole grain gluten-free egg-free pasta

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA food guide recommends that at least ½ of all the grains eaten should be whole grains. The FDA allows food Health Claim labels for food containing 51% whole grains and 11 g of dietary fiber. This is the only report demonstrating innovative whole grain gluten free, egg free (no chemicals adde...

  7. Isotopic Composition of Presolar Silicon Carbide Grains Analyzed with CHILI

    NASA Astrophysics Data System (ADS)

    Stephan, T.; Trappitsch, R.; Davis, A. M.; Pellin, M. J.; Rost, D.; Savina, M. R.; Jadhav, M.; Kelly, C. H.

    2015-07-01

    Twenty-two presolar SiC grains were analyzed for Sr, Zr, and Ba isotopes with the Chicago Instrument for Laser Ionization. Most grains showed isotope patterns consistent with formation in AGB star like observed previously. One grain is a supernova grain.

  8. 12. VIEW OF GRAIN STORAGE PROCESS, SHOWING 'HEADHOUSE' (HIGHEST POINT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW OF GRAIN STORAGE PROCESS, SHOWING 'HEADHOUSE' (HIGHEST POINT OF ELEVATOR STRUCTURE) AND GRAIN DISCHARGE CHUTE, LOOKING EAST. ELEVATOR BUCKETS DISCHARGE GRAIN INTO THIS CHUTE, WHICH THEN DIRECTS THE GRAIN TO ANY ONE OF THE ELEVATOR'S FOURTEEN STORAGE CRIBS. - Western Elevator Company, 507 North Appleton Street, Appleton, Outagamie County, WI

  9. Evaluation of an in situ Grain Moisture Sensor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain storage managers could improve the quality of stored grain if they could directly monitor grain moisture content in storage bins, which is a key indicator of stored grain quality and an early indicator of deterioration. However, the necessary sensors are not commercially available. A new capa...

  10. Grain Boundary Character Distributions In Isostructural Materials

    NASA Astrophysics Data System (ADS)

    Ratanaphan, Sutatch

    Anisotropic grain boundary character distributions (GBCDs), which influence macroscopic materials properties, are thought to be controlled by the grain boundary energy anisotropy. Structurally, grain boundary could be viewed as two free surfaces joined together. Grain boundary energy could be simply defined by the total excess energy for creating two free surfaces minus the energy gained when new bonds are formed between these surfaces. This implies that different crystal structure should have different GBEDs and GBCDs. It was recently discovered that grain boundary energy distributions (GBED) in isostructural materials, a class of materials that share the same crystal structure, are directly related to one another. This suggests that GBCDs in isostructural materials might also be related in a similar way. To test this hypothesis, electron backscatter diffraction (EBSD) was used to map grain orientations in Ag, Au, Cu, Fe, and Mo. The GBCDs were determined from the stereological interpretation of EBSD maps containing on the order of 100,000 grains. It was found that the GBCDs of face-centered cubic (FCC) metals are statistically correlated, while the GBCDs of body-centered cubic (BCC) Fe and Mo are not correlated to the GBCD of FCC metals. The degree of the correlations among the FCC metals is weaker if there are significant differences in grain shape or texture. For example, Ag has the weakest correlation to the other FCC materials and also has quantitatively different grain shapes and texture. The relationship between the populations and energies of grain boundaries was also studied. By comparing the GBCDs of Al, Au, Cu, and Ni to the energies of 388 grain boundaries previously calculated by the Embedded Atom Method (EAM), we observed a moderately inverse correlation between the relative areas of grain boundaries and their energies. Interestingly, there are strong inverse correlations between the energies and populations of the most common grain boundaries (Sigma

  11. Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility.

    PubMed

    Wu, Xiaolei; Yang, Muxin; Yuan, Fuping; Wu, Guilin; Wei, Yujie; Huang, Xiaoxu; Zhu, Yuntian

    2015-11-24

    Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It also has higher strain hardening than coarse-grained Ti, which was hitherto believed impossible. The heterogeneous lamella structure is characterized with soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The unusual high strength is obtained with the assistance of high back stress developed from heterogeneous yielding, whereas the high ductility is attributed to back-stress hardening and dislocation hardening. The process discovered here is amenable to large-scale industrial production at low cost, and might be applicable to other metal systems. PMID:26554017

  12. Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility

    PubMed Central

    Wu, Xiaolei; Yang, Muxin; Yuan, Fuping; Wu, Guilin; Wei, Yujie; Huang, Xiaoxu; Zhu, Yuntian

    2015-01-01

    Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It also has higher strain hardening than coarse-grained Ti, which was hitherto believed impossible. The heterogeneous lamella structure is characterized with soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The unusual high strength is obtained with the assistance of high back stress developed from heterogeneous yielding, whereas the high ductility is attributed to back-stress hardening and dislocation hardening. The process discovered here is amenable to large-scale industrial production at low cost, and might be applicable to other metal systems. PMID:26554017

  13. Polarimetric imaging beyond the speckle grain scale.

    PubMed

    Pouget, Lucien; Fade, Julien; Hamel, Cyril; Alouini, Mehdi

    2012-10-20

    We address an experimental Stokes imaging setup allowing one to explore the polarimetric properties of a speckle light field with spatial resolution well beyond the speckle grain scale. We detail how the various experimental difficulties inherent to such measurements can be overcome with a dedicated measurement protocol involving a careful speckle registration step. The setup and protocol are then validated on a metallic reference sample, and used to measure the state of polarization (SOP) of light in each pixel of highly resolved speckle patterns (>2000 pixels per speckle grain) resulting from the scattering of an incident coherent beam on samples exhibiting different polarimetric properties. Evolution of the SOP with spatial averaging and across adjacent speckle grains is eventually addressed.

  14. Abnormal Grain Growth Suppression in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Hales, Stephen J. (Inventor); Claytor, Harold Dale (Inventor); Alexa, Joel A. (Inventor)

    2015-01-01

    The present invention provides a process for suppressing abnormal grain growth in friction stir welded aluminum alloys by inserting an intermediate annealing treatment ("IAT") after the welding step on the article. The IAT may be followed by a solution heat treatment (SHT) on the article under effectively high solution heat treatment conditions. In at least some embodiments, a deformation step is conducted on the article under effective spin-forming deformation conditions or under effective superplastic deformation conditions. The invention further provides a welded article having suppressed abnormal grain growth, prepared by the process above. Preferably the article is characterized with greater than about 90% reduction in area fraction abnormal grain growth in any friction-stir-welded nugget.

  15. Analyzing individual presolar grains with CHARISMA.

    SciTech Connect

    Savina, M. R.; Pellin, M. J.; Tripa, C. E.; Veryovkin, I. V.; Calaway, W. F.; Davis, A. M.; Univ. of Chicago

    2003-09-01

    Isotopic analysis of heavy elements in individual stardust grains is important in testing and constraining theories of stellar nucleosynthesis. These analyses are challenging in that the grains are very small, the largest being perhaps a few microns in diameter, and contain only trace concentrations of heavy elements, generally on the order of ppm. In addition, isotopic analysis requires the suppression of isobaric interferences. We describe a unique instrument, based on resonant ionization mass spectrometry, that has successfully characterized such grains for the past several years, and report on some recent upgrades that significantly enhance the instrumental capabilities. The fundamental principles and operational details are discussed, along with illustrative results and plans for future modifications.

  16. Structure of grain boundaries in iron

    SciTech Connect

    Harrison, R.J.; Spaepen, F.; Voter, A.F.; Chen, Shao-Ping

    1988-01-01

    The present research has been carried out as part of the Steel Research Group's program to improve the properties of ultra-high- strength steels. It is an investigation of the mechanism of cohesion at grain boundaries as a step toward the design of alloy steel with improved resistance against boundary decohesion under stress corrosion conditions. This research involves a theoretical study of grain boundaries in iron alloys, examining the mechanism of cohesion as affected by structure including imperfections, by the average alloy composition and by segregation at the boundaries. This paper summarizes what we have done to date in obtaining approximate grain boundary structures. We have tested the approximate interatomic potential for iron which we have obtained by using it to compute the interplanar spacings at the surface and then comparing the computed results with experimental observations. Results are discussed. 51 refs., 9 figs., 3 tabs.

  17. Dust Spectroscopy and the Nature of Grains

    NASA Technical Reports Server (NTRS)

    Tielens, A. G. G. M.

    2006-01-01

    Ground-based, air-borne and space-based, infrared spectra of a wide variety of objects have revealed prominent absorption and emission features due to large molecules and small dust grains. Analysis of this data reveals a highly diverse interstellar and circumstellar grain inventory, including both amorphous materials and highly crystalline compounds (silicates and carbon). This diversity points towards a wide range of physical and chemical birthsites as well as a complex processing of these grains in the interstellar medium. In this talk, I will review the dust inventory contrasting and comparing both the interstellar and circumstellar reservoirs. The focus will be on the processes that play a role in the lifecycle of dust in the interstellar medium.

  18. Ion implantation effects in 'cosmic' dust grains

    NASA Technical Reports Server (NTRS)

    Bibring, J. P.; Langevin, Y.; Maurette, M.; Meunier, R.; Jouffrey, B.; Jouret, C.

    1974-01-01

    Cosmic dust grains, whatever their origin may be, have probably suffered a complex sequence of events including exposure to high doses of low-energy nuclear particles and cycles of turbulent motions. High-voltage electron microscope observations of micron-sized grains either naturally exposed to space environmental parameters on the lunar surface or artificially subjected to space simulated conditions strongly suggest that such events could drastically modify the mineralogical composition of the grains and considerably ease their aggregation during collisions at low speeds. Furthermore, combined mass spectrometer and ionic analyzer studies show that small carbon compounds can be both synthesized during the implantation of a mixture of low-energy D, C, N ions in various solids and released in space by ion sputtering.

  19. An Optical Study of Ice Grain Boundaries

    NASA Astrophysics Data System (ADS)

    Thomson, Erik S.

    The equilibrium phase geometry and evolution of polycrystals underlies the nature of materials. In particular, grain boundaries dominate the total interfacial area within polycrystalline materials. Our experimental studies are motivated by the importance of the structure, evolution, and thermodynamic behavior of grain boundaries near bulk melting temperatures. Ice is singled out as a material of interest due to its geophysical importance and its advantageous optical properties. An experimental apparatus and light reflection technique is designed to measure grain boundary melting in ice bicrystals, in thermodynamic equilibrium The technique allows continuous monitoring of reflected light intensity from the grain boundary as the temperature and solutal composition are systematically varied. For each sample the individual crystal orientations are also measured. The type and concentration of impurity in the liquid is controlled and the temperature is continuously recorded and controlled over a range near the melting point. An optical model of the interface is developed in order to convert experimental reflection data into a physical measurement of the liquidity of the grain boundary. Solutions are found for reflection and transmission amplitude coefficients for waves propagating from an arbitrarily oriented uniaxial anisotropic material into an isotropic material. This general model is used to determine solutions for three layer, ice/water/ice, systems with crystals of arbitrary orientation, and is broadly applicable to layered materials. Experimental results show thicker grain boundary liquid layers than expected from classical colligative effects. A physically realistic model of intermolecular interactions succeeds in bounding the measurements. These measurements may have important implications for understanding a wide range of effects in polycrystalline materials. Likewise, the experimental techniques and optical theory may be applied to other systems of broad

  20. Optimal energy management in grain drying.

    PubMed

    Gunasekaran, S

    1986-01-01

    Grain drying is very specific to the geographic location, kind of drying system, and the type of grain. Under a given set of conditions, the optimal system can be selected based on careful evaluation. However, a good choice of drying systems, procedures, and management practices can be made from the information already available. The review of several grain-drying procedures has provided some insight in making a quick evaluation of the process and arriving at the most suitable system for a particular application. Despite extensive research efforts, the present knowledge of grain drying is yet insufficient to optimally design each drying process with respect to capacity, quality, and energy requirement. There is a need for incorporating grain and air parameters more accurately. It is also important to develop comprehensive drying simulation models to encompass agronomic practices, such as planting and harvesting. Recent efforts indicate a strong influence of planting and harvesting strategies on optimal drying and storage system selection. Results of the varietal trials at Ohio State University indicate that it is now possible to select midseason varieties, which dry down rapidly, without sacrificing yield. Also, low moisture at harvest is important to the energy management process because it affects total drying time and energy required. It is also important from a quality standpoint because kernel damage increases rapidly at harvesting moisture levels above 25%. The trend in grain-dryer design has shifted from focusing on drying capacity and operation reliability to energy consumption. The development in design of energy efficient continuous-flow dryers has been significant. Multistage concurrentflow dryers are excellent examples. Various aspects of dryer staging for efficient operation and control are yet to be determined. Recirculation of the exhaust air is a proven method of improving energy efficiency. Likewise, in batch-in-bin systems, stirring and

  1. Enhanced diffusion of phosphorus at grain boundaries

    NASA Technical Reports Server (NTRS)

    Cheng, L. J.; Shyu, C. M.; Stika, K. M.; Daud, T.; Crotty, G. T.

    1982-01-01

    Enhanced diffusion of phosphorus at grain boundaries in cast polycrystalline photovoltaic materials (Wacker, HEM, and Semix) was studied. It was found that the enhancements for the three materials were the same, indicating that the properties of boundaries are similar, even though they were grown by different techniques. In addition, it was observed that grain boundaries capable of enhancing the diffusion always have strong recombination activities. Both phenomena could be related to dangling bonds existing at the boundaries. The present study gives the first evidence that incoherent second order twins of 111/115-plane type are diffusion-active.

  2. The mechanism of grain growth in ceramics

    NASA Technical Reports Server (NTRS)

    Kapadia, C. M.; Leipold, M. H.

    1972-01-01

    The theory of grain boundary migration as a thermally activated process is reviewed, the basic mechanisms in ceramics being the same as in metals. However, porosity and non-stochiometry in ceramic materials give an added dimension to the theory and make quantitative treatment of real systems rather complex. Grain growth is a result of several simultaneous (and sometimes interacting) processes; these are most easily discussed separately, but the overall rate depends on their interaction. Sufficient insight into the nature of rate controlling diffusion mechanisms is necessary before a qualitative understanding of boundary mobility can be developed.

  3. Optimal energy management in grain drying.

    PubMed

    Gunasekaran, S

    1986-01-01

    Grain drying is very specific to the geographic location, kind of drying system, and the type of grain. Under a given set of conditions, the optimal system can be selected based on careful evaluation. However, a good choice of drying systems, procedures, and management practices can be made from the information already available. The review of several grain-drying procedures has provided some insight in making a quick evaluation of the process and arriving at the most suitable system for a particular application. Despite extensive research efforts, the present knowledge of grain drying is yet insufficient to optimally design each drying process with respect to capacity, quality, and energy requirement. There is a need for incorporating grain and air parameters more accurately. It is also important to develop comprehensive drying simulation models to encompass agronomic practices, such as planting and harvesting. Recent efforts indicate a strong influence of planting and harvesting strategies on optimal drying and storage system selection. Results of the varietal trials at Ohio State University indicate that it is now possible to select midseason varieties, which dry down rapidly, without sacrificing yield. Also, low moisture at harvest is important to the energy management process because it affects total drying time and energy required. It is also important from a quality standpoint because kernel damage increases rapidly at harvesting moisture levels above 25%. The trend in grain-dryer design has shifted from focusing on drying capacity and operation reliability to energy consumption. The development in design of energy efficient continuous-flow dryers has been significant. Multistage concurrentflow dryers are excellent examples. Various aspects of dryer staging for efficient operation and control are yet to be determined. Recirculation of the exhaust air is a proven method of improving energy efficiency. Likewise, in batch-in-bin systems, stirring and

  4. Gamma ray lines from interstellar grains

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1976-01-01

    The existence of very narrow (FWHM or approximately = 5 KeV) gamma ray line emission from interstellar grains is pointed out. The prime candidate for detection is the line at 6.129 Mev from O-16, but other very narrow lines could also be detected at 0.847, 1.369, 1.634, 1.779 and 2.313 Mev from Fe-56, Mg-24, Ne-20, Si-28 and N-14. Measurements of this line emission can provide information on the composition, size and spatial distribution of interstellar grains.

  5. Direct observation of deformation-induced grain growth during the nanoindentation of ultrafine-grained Al at room temperature

    SciTech Connect

    Jin, M.; Minor, A.M.; Stach, E.A.; Morris, J.W. . E-mail: jwmorris@berkeley.edu

    2004-10-18

    In situ nanoindentation within a transmission electron microscope is used to investigate the deformation mechanisms in ultrafine-grained Al films. Deformation-induced grain growth resulting from grain boundary migration, grain rotation and grain coalescence is commonly observed as the indentation proceeds. In situ studies of nanograined films suggest that the same mechanisms are operative, though the difficulty of imaging nanosized grains makes the evidence less clear. The results suggest that grain growth and coalescence are important modes of response in the deformation of ultrafine- and nanograined materials.

  6. Organic grain coatings in primitive interplanetary dust particles: Implications for grain sticking in the Solar Nebula

    NASA Astrophysics Data System (ADS)

    Flynn, George J.; Wirick, Sue; Keller, Lindsay P.

    2013-10-01

    The chondritic porous interplanetary dust particles (CP IDPs), fragments of asteroids and comets collected by NASA high-altitude research aircraft from the Earth's stratosphere, are recognized as the least altered samples of the original dust of the Solar Nebula available for laboratory examination. We performed high-resolution, ~25 nm/pixel, x-ray imaging and spectroscopy on ultramicrotome sections of CP IDPs, which are aggregates of >104 grains, and identified and characterized ~100 nm thick coatings of organic matter on the surfaces of the individual grains. We estimated the minimum tensile strength of this organic glue to be ~150 to 325 N/m2, comparable to the strength of the weakest cometary meteors, based on the observation that the individual grains of ~5 μm diameter aggregate CP IDPs are not ejected from the particle by electrostatic repulsion due to charging of these IDPs to 10 to 15 volts at 1 A.U. in space. Since organic coatings can increase the sticking coefficient over that of bare mineral grains, these organic grain coatings are likely to have been a significant aid in grain sticking in the Solar Nebula, allowing the first dust particles to aggregate over a much wider range of collision speeds than for bare mineral grains.

  7. Ochratoxin A in grain dust--estimated exposure and relations to agricultural practices in grain production.

    PubMed

    Halstensen, Anne Straumfors; Nordby, Karl-Christian; Elen, Oleif; Eduard, Wijnand

    2004-01-01

    Ochratoxin A (OTA) is a nephrotoxin frequently contaminating grains. OTA inhalation during grain handling may therefore represent a health risk to farmers, and was the subject of this study. Airborne and settled grain dust was collected during grain work on 84 Norwegian farms. Climate and agricultural practices on each farm were registered. Penicillium spp., Aspergillus spp. and OTA in settled dust were measured. Settled dust contained median 4 microg OTA/kg dust (range 2-128), correlating with Penicillium spp. (median 40 cfu/mg; range 0-32000, rs =0.33; p < 0.01). Similar levels were found across grain species, districts and agricultural practices. Penicillium levels, but not OTA levels, were higher in storage than in threshing dust (p=0.003), and increased with storage time (rs =0.51, p < 0.001). Farmers were exposed to median 1 mg/m3 (range 0.2-15) dust during threshing and median 7 mg/m3 (range 1-110) dust during storage work, equalling median 3.7 pg/m3 (range 0.6-200) and median 40 pg/m3 (range 2-14000) OTA, respectively (p < 0.001). Agricultural practices could not predict OTA, Penicillium or Aspergillus contamination. Compared to oral intake of OTA, the inhalant exposure during grain work was low, although varying by more than 1,000-fold. However, the farmers may occasionally be highly exposed, particularly during handling of stored grain.

  8. The Strength-Grain Size Relationship in Ultrafine-Grained Metals

    NASA Astrophysics Data System (ADS)

    Balasubramanian, N.; Langdon, Terence G.

    2016-04-01

    Metals processed by severe plastic deformation (SPD) techniques, such as equal-channel angular pressing (ECAP) and high-pressure torsion (HPT), generally have submicrometer grain sizes. Consequently, they exhibit high strength as expected on the basis of the Hall-Petch (H-P) relationship. Examples of this behavior are discussed using experimental data for Ti, Al, and Ni. These materials typically have grain sizes greater than ~50 nm where softening is not expected. An increase in strength is usually accompanied by a decrease in ductility. However, both high strength and high ductility may be achieved simultaneously by imposing high strain to obtain ultrafine-grain sizes and high fractions of high-angle grain boundaries. This facilitates grain boundary sliding, and an example is presented for a cast Al-7 pct Si alloy processed by HPT. In some materials, SPD may result in a weakening even with a very fine grain size, and this is due to microstructural changes during processing. Examples are presented for an Al-7034 alloy processed by ECAP and a Zn-22 pct Al alloy processed by HPT. In some SPD-processed materials, it is possible that grain boundary segregation and other features are present leading to higher strengths than predicted by the H-P relationship.

  9. Simulation of grain size effects in nanocrystalline shape memory alloys

    NASA Astrophysics Data System (ADS)

    Ahluwalia, Rajeev; Quek, Siu Sin; Wu, David T.

    2015-06-01

    Recently, it has been demonstrated that martensitic transformation in nanocrystalline shape memory alloys can be suppressed for small grain sizes. Motivated by these results, we study the grain size dependence of martensitic transformations and stress-strain response of nanocrystalline shape memory alloys within the framework of the Ginzburg-Landau (GL) theory. A GL model for a square to rectangle transformation in polycrystals is extended to account for grain boundary effects. We propose that an inhibition of the transformation in grain boundary regions can occur, if the grain boundary energy of the martensite is higher than that of the austenite phase. We show that this inhibition of transformation in grain boundary regions has a strong influence on domain patterns inside grains. Although the transformation is inhibited only at the grain boundaries, it leads to a suppression of the transformation even inside the grains as grain size is decreased. In fact, below a critical grain size, the transformation can be completely suppressed. We explain these results in terms of the extra strain gradient cost associated with grain boundaries, when the transformation is inhibited at grain boundaries. On the other hand, no significant size effects are observed when transformation is not inhibited at grain boundaries. We also study the grain size dependence of the stress strain curve. It is found that when the transformation is inhibited at grain boundaries, a significant reduction in the hysteresis associated with stress-strain curves during the loading-unloading cycles is observed. The hysteresis for this situation reduces even further as the grain size is reduced, which is consistent with recent experiments. The simulations also demonstrate that the mechanical behavior is influenced by inter-granular interactions and the local microstructural neighbourhood of a grain has a stronger influence than the orientation of the grain itself.

  10. The influence of grain boundary structure on the penetration of gallium into aluminum grain boundaries

    NASA Astrophysics Data System (ADS)

    Hugo, Richard Charles

    1998-12-01

    Liquid Metal Embrittlement is a form of environmental embrittlement that dramatically reduces the fracture toughness of many metals and alloys. It occurs when surfaces of certain solid metals are wet by certain liquid metals. The Al-Ga system provides a remarkable example of intergranular attack. The Al-Ga equilibrium phase diagram reveals no intermetallic compounds and very limited mutual solubilities, which implies that interactions between Al and Ga should be minimal. Yet when liquid Ga wets the surface of an unstressed Al specimen, the Ga will penetrate the Al grain boundaries, replacing each boundary with a liquid layer. The driving force is generally considered to be the reduction in energy when a grain boundary is replaced by two Ga-Al interfaces. Once an Al sample has been penetrated by Ga, it fails at almost no load. In this dissertation, in-situ Transmission Electron Microscope (TEM) studies are presented that elucidate the physical nature of the Ga penetration front. Although many of the TEM specimens were bicrystals, all but one of the grain boundaries studied were "general" boundaries; that is, they were low symmetry boundaries with high-index rotation axes, and no low-index planes common to both grains. Since the atomic structure of these grain boundaries cannot be resolved experimentally, atomistic computer models were constructed to assist in interpreting TEM results. TEM observations indicated that the penetration front is a line defect, possessing a stress field that interacts with lattice dislocations. The penetration front was also observed to interact with structural variations within the grain boundary. Interactions with lattice dislocations were used to estimate the penetration front thickness. Penetration speeds were not found to be determined by grain boundary energy or grain boundary excess volume. Penetration speeds were, however, found to depend qualitatively on the presence of penetration barriers in the grain boundary.

  11. Large grain cavities from pure niobium ingot

    SciTech Connect

    Myneni, Ganapati Rao; Kneisel, Peter; Cameiro, Tadeu

    2012-03-06

    Niobium cavities are fabricated by the drawing and ironing of as cast niobium ingot slices rather than from cold rolled niobium sheet. This method results in the production of niobium cavities having a minimum of grain boundaries at a significantly reduced cost as compared to the production of such structures from cold rolled sheet.

  12. Assessment of MARMOT Grain Growth Model

    SciTech Connect

    Fromm, B.; Zhang, Y.; Schwen, D.; Brown, D.; Pokharel, R.

    2015-12-01

    This report assesses the MARMOT grain growth model by comparing modeling predictions with experimental results from thermal annealing. The purpose here is threefold: (1) to demonstrate the validation approach of using thermal annealing experiments with non-destructive characterization, (2) to test the reconstruction capability and computation efficiency in MOOSE, and (3) to validate the grain growth model and the associated parameters that are implemented in MARMOT for UO2. To assure a rigorous comparison, the 2D and 3D initial experimental microstructures of UO2 samples were characterized using non-destructive Synchrotron x-ray. The same samples were then annealed at 2273K for grain growth, and their initial microstructures were used as initial conditions for simulated annealing at the same temperature using MARMOT. After annealing, the final experimental microstructures were characterized again to compare with the results from simulations. So far, comparison between modeling and experiments has been done for 2D microstructures, and 3D comparison is underway. The preliminary results demonstrated the usefulness of the non-destructive characterization method for MARMOT grain growth model validation. A detailed analysis of the 3D microstructures is in progress to fully validate the current model in MARMOT.

  13. Against the Grain: Teaching Historical Complexity

    ERIC Educational Resources Information Center

    Neumann, Dave

    2013-01-01

    Many teachers and scholars have written about the importance of inquiry in effective history instruction. At its core, inquiry involves student investigation of a significant historical problem. Experienced teachers, however, often reveal their skill in purposely teaching against the grain. Skilled teachers help students appreciate historical…

  14. Mineral Analysis of Whole Grain Total Cereal

    ERIC Educational Resources Information Center

    Hooker, Paul

    2005-01-01

    The quantitative analysis of elemental iron in Whole Grain Total Cereal using visible spectroscopy is suitable for a general chemistry course for science or nonscience majors. The more extensive mineral analysis, specifically for the elements iron, calcium and zinc, is suitable for an instrumental or quantitative analysis chemistry course.

  15. The initiation of grain movement by wind

    NASA Technical Reports Server (NTRS)

    Nickling, W. G.

    1986-01-01

    When air blows across the surface of dry, loose sand, a critical shear velocity must be achieved to inititate motion. Since most natural sediments consist of a range of grain sizes, fluid threshold for any sediment cannot really be defined by a finite value but should be viewed as a threshold range which is a function of the mean size, sorting, and packing of the sediment. In order to investigate the initiation of particle movement by wind, a series of wind tunnel tests were carried out on a range of screened sands and commercially available glass beads of differing sizes, sorting, and shape characteristics. In addition, individual samples of the glass beads were mixed to produce rather poorly sorted bimodal distributions. Test results suggest that when velocity is slowly increased over the sediment surface the smaller or more exposed grains are first entrained by the fluid drag of the air either in surface creep or in saltation. As velocity continues to rise, the larger more protected grains may also be moved by fluid drag. The data also indicate that predicted values based on the modified Bagnold equation fall within the range of threshold values defined by the transition section of the grain movement/shear velocity plots. Moreover, the predicted values are very similar to the threshold values derived for the point maximum inflection on the curves.

  16. The initiation of grain movement by wind

    NASA Technical Reports Server (NTRS)

    Nickling, William G.

    1987-01-01

    When air blows across the surface of dry, loose sand, a critical shear velocity must be achieved to initiate motion. Since most natural sediments consist of a range of grain sizes, fluid threshold for any sediment cannot really be defined by a finite value but should be viewed as a threshold range which is a function of the mean size, sorting, and packing of the sediment. In order to investigate the initiation of particle movement by wind, a series of wind tunnel tests were carried out on a range of screened sands and commercially available glass beads of differing size, sorting, and shape characteristics. In addition, individual samples of the glass beads were mixed to produce rather poorly sorted bimodal distributions. Test results suggest the when velocity is slowly increased over the sediment surface the smaller or more exposed grains are first engrained by the fluid drag of the air either in surface creep or in saltation. As velocity continues to rise, the larger more protected grains may also be moved by fluid drag. The data also indicate that predicted values based on the modified Bagnold equation fall within the range of threshold values defined by the transition section of the grain movement/shear velocity plots. Moreover, the predicted values are very similar to the threshold values derived for the point maximum inflection on the curves.

  17. The Grain Group. The Food Guide Pyramid.

    ERIC Educational Resources Information Center

    Frost, Helen

    This booklet for young children is part of a series that supports national science standards related to physical health and nutrition, describing and illustrating the importance of using the Food Guide Pyramid and eating sufficient servings of grains. Colorful photographs support early readers in understanding the text. The repetition of words and…

  18. Dynamic Abnormal Grain Growth in Refractory Metals

    NASA Astrophysics Data System (ADS)

    Noell, Philip J.; Taleff, Eric M.

    2015-11-01

    High-temperature plastic deformation of the body-centered cubic (BCC) refractory metals Mo and Ta can initiate and propagate abnormal grains at significantly lower temperatures and faster rates than is possible by static annealing alone. This discovery reveals a new and potentially important aspect of abnormal grain growth (AGG) phenomena. The process of AGG during plastic deformation at elevated temperatures, termed dynamic abnormal grain growth (DAGG), was observed at homologous temperatures between 0.52 and 0.72 in both Mo and Ta sheet materials; these temperatures are much lower than those for previous observations of AGG in these materials during static annealing. DAGG was used to repeatedly grow single crystals several centimeters in length. Investigations to date have produced a basic understanding of the conditions that lead to DAGG and how DAGG is affected by microstructure in BCC refractory metals. The current state of understanding for DAGG is reviewed in this paper. Attention is given to the roles of temperature, plastic strain, boundary mobility and preexisting microstructure. DAGG is considered for its potential useful applications in solid-state crystal growth and its possibly detrimental role in creating undesired abnormal grains during thermomechanical processing.

  19. Observational Evidence for Radiative Interstellar Grain Alignment

    NASA Astrophysics Data System (ADS)

    Andersson, B.; Potter, S. B.; Andersson, B.; Potter, S.

    2011-11-01

    The alignment mechanisms of interstellar dust grains is a long standing astrophysical problem. Interstellar polarization was first discovered in 1949 and soon thereafter attributed to dichroic extinction caused by asymmetric dust grains aligned with the magnetic field. For a long time the alignment mechanism was thought to involve paramagnetic relaxation in rapidly spinning dust grains. Modern theory indicates that the classical alignment mechanisms are likely not efficient, but rather favor alignment through direct radiative torques. We have used multi-band polarimetry towards stars probing six nearby clouds to show that the wavelength of maximum polarization is linearly correlated with the visual extinction (Andersson & Potter 2007; AP07; where further details can be found). We find a universal relation with a common positive slope between the clouds and a DC offset correlated with the average of the total-to-selective extinction < RV > . These results provide strong observational support for radiatively driven grain alignment. Recent observations of an additional set of ≍60 sightlines in the Taurus cloud confirm and strengthen these results.

  20. Grain legume genetic resources for allele mining

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sequencing capacities for higher throughput at significantly lower costs have enabled larger scale genotyping of plant genetic resources. One challenge to sequencing the USDA grain legume collections of pea, chickpea and lentil core accessions is the amount of heterogeneity in the landrace accessio...

  1. Grain Unloading Of Arsenic Species In Rice

    EPA Science Inventory

    Rice (Oryza sativa) is the staple food for over half the world's population yet may represent a significant dietary source of inorganic arsenic (As), a nonthreshold, class 1 human carcinogen. Rice grain As is dominated by the inorganic species, and the organic species dim...

  2. Women in Grains Research Project--Extract.

    ERIC Educational Resources Information Center

    Berrisford, Nickie

    Research aimed at recognizing, encouraging, enhancing, and harnessing the skills and contributions of women in the Australian grains industry involved a number of women in Victoria in focus groups, telephone interviews, and questionnaire surveys. Results indicate that women perceived themselves as providing guidance, operational assistance,…

  3. Fruit, vegetable, and grain processing wastes

    SciTech Connect

    Andrews, R.M.; Soderquist, M.R.

    1980-06-01

    This is a literature review of fruit, vegetable and grain processing wastes. The factors affecting water usage and methods of conservation were examined. Various processes were investigated which included the pulp recovery from caustic peeled tomato skin, the dewatering of citrus, washing leafy vegetables with recycled process water and the potato processing industry.

  4. New market opportunities for rice grains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Breeding efforts for rice have been focusing on increasing yield and improving quality (milling yield and grain quality), while maintaining cooked rice sensory properties to meet consumer preferences. These breeding targets will no doubt continue as the main foci for the rice industry. However, the ...

  5. Comparison of communities of stored product mites in grain mass and grain residues in the Czech Republic.

    PubMed

    Hubert, Jan; Munzbergová, Zuzana; Kucerová, Zuzana; Stejskal, Václav

    2006-01-01

    In storage facilities one can find grain either in stored grain mass or in grain residues in the store corners or machinery. Although it is claimed that grain residues are serious pest reservoirs since they harbor numbers of stored product arthropods and are connected via continuous emigration with grain mass, the documentation for this is not convincing. Therefore in 78 selected grain stores, we simultaneously sampled the grain mass and residues in order to compare concurrent mite communities in these two different habitats. We found 30 species in about 614,000 individuals in residues and 23 species in about 20 000 individuals in grain mass. Canonical correspondence analysis (CCA) of transformed abundance data showed differences in the communities of mites in grain mass and residues: (i) species associated to grain residues (e.g. Tyrophagus longior, Tydeus interruptus, Acarus farris and Cheyletus eruditus) and (ii) species associated to both grain mass and grain residues (e.g. Tarsonemus granarius, Acarus siro, Tyrophagus putrescentiae, Lepidoglyphus destructor and Cheyletus malaccensis). Although the residue samples had more mites and higher species diversity than the stored grain mass, no correlation in mite abundance and species numbers between samples from grain residues and grain mass was found, thereby indicating low connectivity of these two habitats.

  6. Grain growth and grain boundary segregation in binary alloys: A Monte-Carlo simulation

    SciTech Connect

    Liu, J.M. |; Wu, Z.C.

    1997-08-15

    The authors have presented a Monte-Carlo simulation of grain growth and solute segregation on the grain boundaries (GBs) in binary alloys. A thermodynamic approach of the simulation algorithm has been given. The preliminary simulation of a simplified binary system indicates that pronounced solute segregation on the GBs is achieved, characterized by linearly increasing solute concentration on the GBs and significant spatial correlation of the solute distribution. The authors observe the normal grain growth in the present system by demonstrating the scaling behavior of its size distribution although the kinetics is seriously slowed down, exhibiting an exponent much lower than the 1/2 law.

  7. Analysis of Grain Boundary Character in a Fine-Grained Nickel-Based Superalloy 718

    NASA Astrophysics Data System (ADS)

    Araujo, L. S.; dos Santos, D. S.; Godet, S.; Dille, J.; Pinto, A. L.; de Almeida, L. H.

    2014-11-01

    In the current work, sheets of superalloy 718 were processed via thermomechanical route by hot and cold rolling, followed by annealing below the δ phase solvus temperature and precipitation hardening to optimum strength. Grain boundary character distribution throughout the processing was mapped via EBSD and its evolution discussed. The results show that it is possible to process the alloy to a fine grain size obtaining concomitantly a considerably high proportion of special boundaries Σ3, Σ9, and Σ27. The precipitation of δ phase presented a strong grain refining role, without significantly impairing the twinning mechanism and, consequently, the Σ3, Σ9, and Σ27 boundary formations.

  8. Geometry and crystallographic configuration of grain boundaries

    NASA Astrophysics Data System (ADS)

    Eichler, Jan; Weikusat, Ilka; Kipfstuhl, Sepp; Binder, Tobias

    2015-04-01

    Ice cores provide a unique opportunity to study fundamental mechanisms which control the internal flow of ice sheets. Different kinds of deformation processes acting on the micro-scale are responsible for the viscoplastic behavior on large scale. Careful interpretation of microstructural features such as grain size, shape, lattice orientation and the occurrence of subgrain boundaries can help us to follow these processes and to improve our understanding of ice rheology. Polarized light microscopy experienced a quick development in the last decade. A new generation of automatic fabric analyzers enables to measure c-axis orientations in µm-resolution. This high amount and quality of fabric data motivates to apply digital-image-processing routines (DIP) for the recognition and quantification of microstructural patterns. Here we present a study on grain boundaries based on the acquisition of more than 700 fabric images recorded along the NEEM ice core (Greenland). Geometrical characteristics of grain boundaries are studied as well as their cross-sectional orientations in relation to the c-axis orientations of the corresponding adjacent grains. We could follow the evolution from the initial N-type and P-type low-angle boundaries (Weikusat et al., 2011) to high angle boundaries during rotation recrystallization. In agreement with some previous studies we confirm that the established three-stage-recrystallization model may be an oversimplification. According to our results, rotation recrystallization as well as grain boundary migration are actually present in all depths with varying intensities at NEEM. I. Weikusat, A. Miyamoto, S. H. Faria, S. Kipfstuhl, N. Azuma, and T. Hondoh: Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction. J. Glaciol., 57(201):85-94, 2011. doi: 10013/epic.36402.

  9. Worker hazards associated with the use of grain vacuum systems.

    PubMed

    Field, W E; Heber, D J; Riedel, S M; Wettschurack, S W; Roberts, M J; Grafft, L J

    2014-07-01

    Over the past two decades, there has been more widespread use of pneumatic handling of grain at commercial grain storage facilities and on farms as these operations have increased grain storage capacity and handle larger volumes of grain and feed In some cases, manufacturers have suggested that the use of these systems is a safer alternative to removing residual grain manually in conjunction with the use of sweep augers. The use of grain vacuum systems has also been increasingly documented as a strategy in responding to grain storage fires and human entrapment and engulfment in flowing grain. With greater utilization of these machines have come reports of entrapments and engulfments. This article summarizes 27 such documented incidents, including 21 fatalities, that resulted from the use of portable grain vacuum systems. It includes specific recommendations for engineering, educational, and regulatory strategies to reduce the risks associated with the use of these systems.

  10. Paleowattmeters: A scaling relation for dynamically recrystallized grain size

    NASA Astrophysics Data System (ADS)

    Austin, Nicholas J.; Evans, Brian

    2007-04-01

    During dislocation creep, mineral grains often evolve to a stable size, dictated by the deformation conditions. We suggest that grain-size evolution during deformation is determined by the rate of mechanical work. Provided that other elements of microstructure have achieved steady state and that the dissipation rate is roughly constant, then changes in internal energy will be proportional to changes in grain-boundary area. If normal grain-growth and dynamic grain-size reduction occur simultaneously, then the steady-state grain size is determined by the balance of those rates. A scaling model using these assumptions and published grain-growth and mechanical relations matches stress grain-size relations for quartz and olivine rocks with no fitting. For marbles, the model also explains scatter not rationalized by assuming that recrystallized grain size is a function of stress alone. When extrapolated to conditions typical for natural mylonites, the model is consistent with field constraints on stresses and strain rates.

  11. A continuum theory of grain size evolution and damage

    NASA Astrophysics Data System (ADS)

    Ricard, Y.; Bercovici, D.

    2009-01-01

    Lithospheric shear localization, as occurs in the formation of tectonic plate boundaries, is often associated with diminished grain size (e.g., mylonites). Grain size reduction is typically attributed to dynamic recrystallization; however, theoretical models of shear localization arising from this hypothesis are problematic because (1) they require the simultaneous action of two creep mechanisms (diffusion and dislocation creep) that occur in different deformation regimes (i.e., in grain size stress space) and (2) the grain growth ("healing") laws employed by these models are derived from normal grain growth or coarsening theory, which are valid in the absence of deformation, although the shear localization setting itself requires deformation. Here we present a new first principles grained-continuum theory, which accounts for both coarsening and damage-induced grain size reduction in a monomineralic assemblage undergoing irrecoverable deformation. Damage per se is the generic process for generation of microcracks, defects, dislocations (including recrystallization), subgrains, nuclei, and cataclastic breakdown of grains. The theory contains coupled macroscopic continuum mechanical and grain-scale statistical components. The continuum level of the theory considers standard mass, momentum, and energy conservation, as well as entropy production, on a statistically averaged grained continuum. The grain-scale element of the theory describes both the evolution of the grain size distribution and mechanisms for both continuous grain growth and discontinuous grain fracture and coalescence. The continuous and discontinuous processes of grain size variation are prescribed by nonequilibrium thermodynamics (in particular, the treatment of entropy production provides the phenomenological laws for grain growth and reduction); grain size evolution thus incorporates the free energy differences between grains, including both grain boundary surface energy (which controls coarsening

  12. On the interaction of solutes with grain boundaries

    SciTech Connect

    Dingreville, Remi Philippe Michel; Berbenni, Stephane

    2015-11-01

    Solute segregation to grain boundaries is considered by modeling solute atoms as misfitting inclusions within a disclination structural unit model describing the grain boundary structure and its intrinsic stress field. The solute distribution around grain boundaries is described through Fermi–Dirac statistics of site occupancy. The susceptibility of hydrogen segregation to symmetric tilt grain boundaries is discussed in terms of the misorientation angle, the defect type characteristics at the grain boundary, temperature, and the prescribed bulk hydrogen fraction of occupied sites. Through this formalism, it is found that hydrogen trapping on grain boundaries clearly correlates with the grain boundary structure (i.e. type of structural unit composing the grain boundary), and the associated grain boundary misorientation. Specifically, for symmetric tilt grain boundaries about the [001] axis, grain boundaries composed of both B and C structural units show a lower segregation susceptibility than other grain boundaries. A direct correlation between the segregation susceptibility and the intrinsic net defect density is provided through the Frank–Bilby formalism. Moreover, the present formulation could prove to be a simple and useful model to identify classes of grain boundaries relevant to grain boundary engineering.

  13. On the interaction of solutes with grain boundaries

    DOE PAGESBeta

    Dingreville, Remi Philippe Michel; Berbenni, Stephane

    2015-11-01

    Solute segregation to grain boundaries is considered by modeling solute atoms as misfitting inclusions within a disclination structural unit model describing the grain boundary structure and its intrinsic stress field. The solute distribution around grain boundaries is described through Fermi–Dirac statistics of site occupancy. The susceptibility of hydrogen segregation to symmetric tilt grain boundaries is discussed in terms of the misorientation angle, the defect type characteristics at the grain boundary, temperature, and the prescribed bulk hydrogen fraction of occupied sites. Through this formalism, it is found that hydrogen trapping on grain boundaries clearly correlates with the grain boundary structure (i.e.more » type of structural unit composing the grain boundary), and the associated grain boundary misorientation. Specifically, for symmetric tilt grain boundaries about the [001] axis, grain boundaries composed of both B and C structural units show a lower segregation susceptibility than other grain boundaries. A direct correlation between the segregation susceptibility and the intrinsic net defect density is provided through the Frank–Bilby formalism. Moreover, the present formulation could prove to be a simple and useful model to identify classes of grain boundaries relevant to grain boundary engineering.« less

  14. Five-parameter grain boundary analysis of a grain boundary-engineered austenitic stainless steel.

    PubMed

    Jones, R; Randle, V; Engelberg, D; Marrow, T J

    2009-03-01

    Two different grain boundary engineering processing routes for type 304 austenitic stainless steel have been compared. The processing routes involve the application of a small level of strain (5%) through either cold rolling or uni-axial tensile straining followed by high-temperature annealing. Electron backscatter diffraction and orientation mapping have been used to measure the proportions of Sigma3(n) boundary types (in coincidence site lattice notation) and degree of random boundary break-up, in order to gain a measure of the success of the two types of grain boundary engineering treatments. The distribution of grain boundary plane crystallography has also been measured and analyzed in detail using the five-parameter stereological method. There were significant differences between the grain boundary population profiles depending on the type of deformation applied. PMID:19250462

  15. Self-adaptive grain recognition of diamond grinding wheel and its grains assessment

    NASA Astrophysics Data System (ADS)

    Cui, Changcai; Zhou, Lijun; Yu, Qing; Huang, Hui; Ye, Ruifang

    2013-10-01

    An improved Canny operator based on the method of Maximum Classes Square Error is adopted to get a self-adaptive threshold for grain recognition. First, a grinding wheel surface was measured by using a vertical scanning white light interferometric (WLI) system and reconstructed with an improved centroid algorithm; then the grains were extracted using the proposed method based on the fact that the peak intensity difference (ΔI) between maximum and minimum intensities on interferometric curve from diamond is larger than that from bond due to different reflective characteristics of different materials; third the grain protrusion parameters are investigated for grinding performance analysis. The experiments proved that the proposed grain recognition method is effective and assessment parameters are useful for understanding grinding performance.

  16. On the theory of dynamics of dust grain in plasma

    SciTech Connect

    Stepanenko, A. A.; Krasheninnikov, S. I.

    2013-03-15

    The dynamics of rotationally symmetric dust grains in plasma embedded in a magnetic field are of concern. The general expressions for forces and torques acting on dust are found. It is shown that dust spinning is determined by torques related to both the Lorentz force (dominant for relatively small grains) and the gyro-motion of plasma particles impinging the grain (which prevails for large grains). The stability of grain spinning is analyzed and it is shown that, for some cases (e.g., oblate spheroid), there is no stable dynamic equilibrium of grain spinning.

  17. Development of quick cooking multi-grain dalia utilizing sprouted grains.

    PubMed

    Mridula, D; Sharma, Monika; Gupta, R K

    2015-09-01

    Multi-grain dalia (MGD) formulations were prepared utilizing sprouted wheat and mixer of other three grains (barley, sorghum and pearl millet) in the ratio of 100:0 (MGD-A), 75:25 (MGD-B), 50:50 (MGD-C), 25:75 (MGD-D) and 0:100 (MGD-E), respectively. The mixer of barley, sorghum and pearl millet was prepared using 50, 25, 25 parts of these grains, respectively. The recovery of grits/ dalia (particle size 1.41 to 2 mm) from sprouted wheat and barley was 74.56 and 69.77 %, respectively while sorghum and pearl millet yield 47.94 and 49.39 % (particle size 0.954 to 1.41 mm), respectively. Sprouting brought a reduction of cooking time by about 50 % as compared to un-sprouted studied grains. Cooking time for different MGD formulations ranged from 3.91 to 4.42 min, which was slightly increased with increasing proportion of mixer of barley, sorghum and pearl millet (p > 0.05). Rehydration ratio of MGD samples varied from 3.12 to 3.45 with minimum in MGD-E sample. Though protein content was decreased with increasing proportion of mixer of three grains in MGD samples but in vitro protein digestibility (58.68 to 62.75 %) was similar (p > 0.05). The mean overall sensory acceptability scores for MGD samples ranged from 7.50 to 8.49 with ≥8.0 in samples having up to 75 % grits of mixer of three grains. In view of very good overall sensory acceptability, rich in crude fibre, calcium and iron content and low cooking time, 25:75 parts of sprouted wheat and mixer of studied three grains, respectively may be considered for preparation of acceptable quality quick cooking multi-grain dalia.

  18. Increasing abscisic acid levels by immunomodulation in barley grains induces precocious maturation without changing grain composition.

    PubMed

    Staroske, Nicole; Conrad, Udo; Kumlehn, Jochen; Hensel, Götz; Radchuk, Ruslana; Erban, Alexander; Kopka, Joachim; Weschke, Winfriede; Weber, Hans

    2016-04-01

    Abscisic acid (ABA) accumulates in seeds during the transition to the seed filling phase. ABA triggers seed maturation, storage activity, and stress signalling and tolerance. Immunomodulation was used to alter the ABA status in barley grains, with the resulting transgenic caryopses responding to the anti-ABA antibody gene expression with increased accumulation of ABA. Calculation of free versus antibody-bound ABA reveals large excess of free ABA, increasing signficantly in caryopses from 10 days after fertilization. Metabolite and transcript profiling in anti-ABA grains expose triggered and enhanced ABA-functions such as transcriptional up-regulation of sucrose-to-starch metabolism, storage protein synthesis and ABA-related signal transduction. Thus, enhanced ABA during transition phases induces precocious maturation but negatively interferes with growth and development. Anti-ABA grains display broad constitutive gene induction related to biotic and abiotic stresses. Most of these genes are ABA- and/or stress-inducible, including alcohol and aldehyde dehydrogenases, peroxidases, chaperones, glutathione-S-transferase, drought- and salt-inducible proteins. Conclusively, ABA immunomodulation results in precocious ABA accumulation that generates an integrated response of stress and maturation. Repression of ABA signalling, occurring in anti-ABA grains, potentially antagonizes effects caused by overshooting production. Finally, mature grain weight and composition are unchanged in anti-ABA plants, although germination is somewhat delayed. This indicates that anti-ABA caryopses induce specific mechanisms to desensitize ABA signalling efficiently, which finally yields mature grains with nearly unchanged dry weight and composition. Such compensation implicates the enormous physiological and metabolic flexibilities of barley grains to adjust effects of unnaturally high ABA amounts in order to ensure and maintain proper grain development.

  19. Increasing abscisic acid levels by immunomodulation in barley grains induces precocious maturation without changing grain composition

    PubMed Central

    Staroske, Nicole; Conrad, Udo; Kumlehn, Jochen; Hensel, Götz; Radchuk, Ruslana; Erban, Alexander; Kopka, Joachim; Weschke, Winfriede; Weber, Hans

    2016-01-01

    Abscisic acid (ABA) accumulates in seeds during the transition to the seed filling phase. ABA triggers seed maturation, storage activity, and stress signalling and tolerance. Immunomodulation was used to alter the ABA status in barley grains, with the resulting transgenic caryopses responding to the anti-ABA antibody gene expression with increased accumulation of ABA. Calculation of free versus antibody-bound ABA reveals large excess of free ABA, increasing signficantly in caryopses from 10 days after fertilization. Metabolite and transcript profiling in anti-ABA grains expose triggered and enhanced ABA-functions such as transcriptional up-regulation of sucrose-to-starch metabolism, storage protein synthesis and ABA-related signal transduction. Thus, enhanced ABA during transition phases induces precocious maturation but negatively interferes with growth and development. Anti-ABA grains display broad constitutive gene induction related to biotic and abiotic stresses. Most of these genes are ABA- and/or stress-inducible, including alcohol and aldehyde dehydrogenases, peroxidases, chaperones, glutathione-S-transferase, drought- and salt-inducible proteins. Conclusively, ABA immunomodulation results in precocious ABA accumulation that generates an integrated response of stress and maturation. Repression of ABA signalling, occurring in anti-ABA grains, potentially antagonizes effects caused by overshooting production. Finally, mature grain weight and composition are unchanged in anti-ABA plants, although germination is somewhat delayed. This indicates that anti-ABA caryopses induce specific mechanisms to desensitize ABA signalling efficiently, which finally yields mature grains with nearly unchanged dry weight and composition. Such compensation implicates the enormous physiological and metabolic flexibilities of barley grains to adjust effects of unnaturally high ABA amounts in order to ensure and maintain proper grain development. PMID:26951372

  20. Increasing abscisic acid levels by immunomodulation in barley grains induces precocious maturation without changing grain composition.

    PubMed

    Staroske, Nicole; Conrad, Udo; Kumlehn, Jochen; Hensel, Götz; Radchuk, Ruslana; Erban, Alexander; Kopka, Joachim; Weschke, Winfriede; Weber, Hans

    2016-04-01

    Abscisic acid (ABA) accumulates in seeds during the transition to the seed filling phase. ABA triggers seed maturation, storage activity, and stress signalling and tolerance. Immunomodulation was used to alter the ABA status in barley grains, with the resulting transgenic caryopses responding to the anti-ABA antibody gene expression with increased accumulation of ABA. Calculation of free versus antibody-bound ABA reveals large excess of free ABA, increasing signficantly in caryopses from 10 days after fertilization. Metabolite and transcript profiling in anti-ABA grains expose triggered and enhanced ABA-functions such as transcriptional up-regulation of sucrose-to-starch metabolism, storage protein synthesis and ABA-related signal transduction. Thus, enhanced ABA during transition phases induces precocious maturation but negatively interferes with growth and development. Anti-ABA grains display broad constitutive gene induction related to biotic and abiotic stresses. Most of these genes are ABA- and/or stress-inducible, including alcohol and aldehyde dehydrogenases, peroxidases, chaperones, glutathione-S-transferase, drought- and salt-inducible proteins. Conclusively, ABA immunomodulation results in precocious ABA accumulation that generates an integrated response of stress and maturation. Repression of ABA signalling, occurring in anti-ABA grains, potentially antagonizes effects caused by overshooting production. Finally, mature grain weight and composition are unchanged in anti-ABA plants, although germination is somewhat delayed. This indicates that anti-ABA caryopses induce specific mechanisms to desensitize ABA signalling efficiently, which finally yields mature grains with nearly unchanged dry weight and composition. Such compensation implicates the enormous physiological and metabolic flexibilities of barley grains to adjust effects of unnaturally high ABA amounts in order to ensure and maintain proper grain development. PMID:26951372

  1. Genetic Dissection of Grain Size and Grain Number Trade-Offs in CIMMYT Wheat Germplasm

    PubMed Central

    Griffiths, Simon; Wingen, Luzie; Pietragalla, Julian; Garcia, Guillermo; Hasan, Ahmed; Miralles, Daniel; Calderini, Daniel F.; Ankleshwaria, Jignaben Bipinchandra; Waite, Michelle Leverington; Simmonds, James; Snape, John; Reynolds, Matthew

    2015-01-01

    Grain weight (GW) and number per unit area of land (GN) are the primary components of grain yield in wheat. In segregating populations both yield components often show a negative correlation among themselves. Here we use a recombinant doubled haploid population of 105 individuals developed from the CIMMYT varieties Weebill and Bacanora to understand the relative contribution of these components to grain yield and their interaction with each other. Weebill was chosen for its high GW and Bacanora for high GN. The population was phenotyped in Mexico, Argentina, Chile and the UK. Two loci influencing grain yield were indicated on 1B and 7B after QTL analysis. Weebill contributed the increasing alleles. The 1B effect, which is probably caused by to the 1BL.1RS rye introgression in Bacanora, was a result of increased GN, whereas, the 7B QTL controls GW. We concluded that increased in GW from Weebill 7B allele is not accompanied by a significant reduction in grain number. The extent of the GW and GN trade-off is reduced. This makes this locus an attractive target for marker assisted selection to develop high yielding bold grain varieties like Weebill. AMMI analysis was used to show that the 7B Weebill allele appears to contribute to yield stability. PMID:25775191

  2. Grain-boundary structures in hexagonal materials: Coincident and near coincident grain boundaries

    NASA Astrophysics Data System (ADS)

    Farkas, Diana

    1994-07-01

    Embedded atom method (EAM) simulations of the structure of grain boundaries in hexagonal metals are presented. The simulations use recently developed interatomic potentials for Ti and Co. Structures were calculated for various symmetrical tilt boundaries with the [1¯100] tilt axis. The structures obtained for both metals are very similar. The energies for the Co boundaries are higher than those for Ti by a factor of 2. The structural unit model was applied to the computed grain-boundary structures in these hexagonal materials. As in cubic materials, the structural unit model can describe a series of symmetrical tilt coincident boundaries. In addition, when the coincidence ratio in the grain-boundary plane varies with the c/a ratio, a structural unit-type model can describe the variation of grain-boundary structure with c/a ratio. This model is adequate for describing series of symmetrical tilt boundaries with the grain-boundary plane oriented perpendicular to a fixed crystallographic direction and varying c/a ratios. For the structures of the so-called near coincident boundaries that appear in these materials, it was concluded that near coincident boundaries behave similarly to exact coincidence boundaries if there is a coincident periodic structure in the grain-boundary plane. This may occur even without a three-dimensional (3-D) coincident site lattice.

  3. The effects of grain size and grain boundary characteristics on the thermal conductivity of nanocrystalline diamond

    NASA Astrophysics Data System (ADS)

    Spiteri, David; Anaya, Julian; Kuball, Martin

    2016-02-01

    Molecular dynamics simulation was used to study the effects of each grain dimension and of grain boundary characteristics on the inter-grain thermal boundary resistance (TBR) and intragrain thermal conductivity of nanocrystalline diamond. The effect of the grain boundaries perpendicular to the heat flow was studied using a multiple slab configuration, which greatly reduced the artifacts associated with the heat source/sink. The TBR between the slabs was found to be more sensitive to the atomic arrangement at the boundary than to the tilt angle between the slabs. When the atomic arrangement at the interface was altered from the minimum energy configuration, the TBR increased by a factor of three, suggesting that a sub-optimal interface quality between the grains could play a large role in reducing the thermal conductivity of nanocrystalline diamond. The thermal conductivity between the boundaries was found to be similar to the bulk value, even when the boundaries were only 25 nm apart. The effect of grain boundaries parallel to the heat flow was found to have a large dependence on the microstructural details. Parallel boundaries which were 2 nm apart reduced the thermal conductivity of defect-free diamond by between one third and a factor of ten.

  4. Abnormal grain growth in AISI 304L stainless steel

    SciTech Connect

    Shirdel, M.; Mirzadeh, H.; Parsa, M.H.

    2014-11-15

    The microstructural evolution during abnormal grain growth (secondary recrystallization) in 304L stainless steel was studied in a wide range of annealing temperatures and times. At relatively low temperatures, the grain growth mode was identified as normal. However, at homologous temperatures between 0.65 (850 °C) and 0.7 (900 °C), the observed transition in grain growth mode from normal to abnormal, which was also evident from the bimodality in grain size distribution histograms, was detected to be caused by the dissolution/coarsening of carbides. The microstructural features such as dispersed carbides were characterized by optical metallography, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and microhardness. Continued annealing to a long time led to the completion of secondary recrystallization and the subsequent reappearance of normal growth mode. Another instance of abnormal grain growth was observed at homologous temperatures higher than 0.8, which may be attributed to the grain boundary faceting/defaceting phenomenon. It was also found that when the size of abnormal grains reached a critical value, their size will not change too much and the grain growth behavior becomes practically stagnant. - Highlights: • Abnormal grain growth (secondary recrystallization) in AISI 304L stainless steel • Exaggerated grain growth due to dissolution/coarsening of carbides • The enrichment of carbide particles by titanium • Abnormal grain growth due to grain boundary faceting at very high temperatures • The stagnancy of abnormal grain growth by annealing beyond a critical time.

  5. GROWTH OF GRAINS IN BROWN DWARF DISKS

    SciTech Connect

    Meru, Farzana; Galvagni, Marina; Olczak, Christoph

    2013-09-01

    We perform coagulation and fragmentation simulations using the new physically motivated model by Garaud et al. to determine growth locally in brown dwarf disks. We show that large grains can grow and that if brown dwarf disks are scaled-down versions of T Tauri disks (in terms of stellar mass, disk mass, and disk radius) growth at an equivalent location with respect to the disk truncation radius can occur to the same size in both disks. We show that similar growth occurs because the collisional timescales in the two disks are comparable. Our model may therefore potentially explain the recent observations of grain growth to millimeter sizes in brown dwarf disks, as seen in T Tauri disks.

  6. Sublimating grains model of cometary coma.

    NASA Astrophysics Data System (ADS)

    Faggi, S.; Tozzi, G. P.; Brucato, J. R.

    Billion years of space weathering produces a crust of organic matter (see e.g. Kanuchova et al. 2012) that will be released when a comet enter for the first time in the inner Solar System. New comets, coming form the Oort Colud at their first passage close to the Sun, are particularly important because they are not differentiated by the Solar radiation and they are supposed to have a large quantity of ice organic matter close to the surface. When a comet approach to the Sun, its activity is driven by the sublimation of these nucleus ices: if the heliocentric distances, R_H , is greater than 3 AU the sublimation of CO and CO_2 ices is the main source of comet activity, otherwise at shorter distances, the sublimation of water become the most important mechanism of activity. These gases, escaping from the nucleus, drag in the coma grains that can be refractory dust (silicates, carbon), water ice and/or organic ices. Oort comets at their first passage in the inner Solar System, should produce an halo of organic or water icy particles. Our group has been monitoring new, inbound, bright Oort comets (C/2011 F1, C/2012 S1, C/2012 K1, C/2013 V5, C/2012 F3, C/2013 US10, C/2013 X1) to search for these icy grains. The method consists in detecting the cloud of sublimating grains in the inner coma by using the Sigma Af function (Tozzi et al. 2007) directly from images. However this over-population of grains, beside the sublimation, can be also due to short time activity (outburst) or too big grains expanding at very slow velocity, as it has been found in comet 67P/C-G (Tozzi eta al, 2011, A&A, 531, 54). To disentangle between the phenomena it is necessary to monitor the comet both at short timescale, for the outbursts (by repeating the observations after few nights), and at long term (weeks-months). If the cloud does not expand with the decreasing of the heliocentric distance there is high probability that we are in presence of organic and/or water ice grains. We can disentangle

  7. The Energy of Olivine Grain Boundaries Deduced from Grain Boundary Frequency Analyses

    NASA Astrophysics Data System (ADS)

    Marquardt, K.; Rohrer, G. S.

    2015-12-01

    The properties of grain boundaries strongly differ from those of the crystal lattice, and there is growing evidence that the presence of grain boundaries influence detected geophysical signals such as electrical conductivity and seismic velocities especially in aggregates with a LPO that favours the alignment of specific grain boundaries. However, neither the anisotropic frequency or energy distribution of grain boundary networks are understood in olivine dominated aggregates, neither with nor without LPO. We used electron backscatter diffraction, EBSD to detect the orientations of over 1.4x104 grains corresponding to roughly 5000mm length of grain boundary separating them. Subsequently we used a stereological approach to determine the grain boundary character distribution, GBCD, defined as the relative areas of grain boundaries of different types, distinguished by their five degrees of freedom (Rohrer, 2007). The grain boundary planes showed a preference for low index planes, which is in agreement with recent findings on other materials (e.g. MgO, TiO2, SrTiO3, MgAl2O4). However, our inferred surface energies are controversial with respect to previously simulated surface energies (Watson et al., 1997; de Leeuw et al., 2000; Gurmani et al., 2011). We find that the principal crystallographic planes have the lowest energies and that at 60° misorientation specific grain boundaries with common [100] axis of misorientation are favored compared to 60° misorientations about random axis of rotation. This seems to support the results of (Faul and Fitz Gerald, 1999), even though our data imply that 90°/[001] (100)(010) should be even less favorable for the propagation of melt films. These differences and similarities will be discussed with respect to the different methods and their limitations. References: Faul U. H. and Fitz Gerald J. D. (1999) Phys. Chem. Miner. 26, 187-197. Gurmani S. F. et al. (2011). J. Geophys. Res. 116, B12209. De Leeuw N. H. et al. (2000) Phys

  8. Measuring Crack Length in Coarse Grain Ceramics

    NASA Technical Reports Server (NTRS)

    Salem, Jonathan A.; Ghosn, Louis J.

    2010-01-01

    Due to a coarse grain structure, crack lengths in precracked spinel specimens could not be measured optically, so the crack lengths and fracture toughness were estimated by strain gage measurements. An expression was developed via finite element analysis to correlate the measured strain with crack length in four-point flexure. The fracture toughness estimated by the strain gaged samples and another standardized method were in agreement.

  9. Genetic engineering for high methionine grain legumes.

    PubMed

    Müntz, K; Christov, V; Saalbach, G; Saalbach, I; Waddell, D; Pickardt, T; Schieder, O; Wüstenhagen, T

    1998-08-01

    Methionine (Met) is the primary limiting essential amino acid in grain legumes. The imbalance in amino acid composition restricts their biological value (BV) to 55 to 75% of that of animal protein. So far improvement of the BV could not be achieved by conventional breeding. Therefore, genetic engineering was employed by several laboratories to resolve the problem. Three strategies have been followed. A) Engineering for increased free Met levels; B) engineering of endogenous storage proteins with increased numbers of Met residues; C) transfer of foreign genes encoding Met-rich proteins, e.g. the Brazil nut 2S albumin (BNA) and its homologue from sunflower, into grain legumes. The latter strategy turned out to be most promising. In all cases the gene was put under the control of a developmentally regulated seed specific promoter and transferred into grain legumes using the bacterial Agrobacterium tumefaciens-system. Integration into and copy numbers in the plant genome as well as Mendelian inheritance and gene dosage effects were verified. After correct precursor processing the mature 2S albumin was intracellularly deposited in protein bodies which are part of the vacuolar compartment. The foreign protein amounted to 5 to 10% of the total seed protein in the best transgenic lines of narbon bean (Vicia narbonensis L., used in the authors' laboratories), lupins (Lupinus angustifolius L., used in CSIRO, Australia), and soybean (Glycine max (L.) Merr., used by Pioneer Hi-Bred, Inc., USA). In the narbon bean the increase of Met was directly related to the amount of 2S albumin in the transgenic seeds, but in soybean it remained below the theoretically expected value. Nevertheless, trangenic soybean reached 100%, whereas narbon bean and lupins reached approximately 80% of the FAO-standard for nutritionally balanced food proteins. These results document that the Met problem of grain legumes can be resolved by genetic engineering.

  10. Regulation of aleurone development in cereal grains.

    PubMed

    Becraft, Philip W; Yi, Gibum

    2011-03-01

    The aleurone layer of cereal grains is important biologically as well as nutritionally and economically. Here, current knowledge on the regulation of aleurone development is reviewed. Recent reports suggest that the control of aleurone development is more complex than earlier models portrayed. Multiple levels of genetic regulation control aleurone cell fate, differentiation, and organization. The hormones auxin and cytokinin can also influence aleurone development. New technical advances promise to facilitate future progress.

  11. Exposure to grain dust in Great Britain.

    PubMed

    Spankie, Sally; Cherrie, John W

    2012-01-01

    Airborne grain dust is a complex mixture of fragments of organic material from grain, plus mineral matter from soil, and possible insect, fungal, or bacterial contamination or their toxic products, such as endotoxin. In the 1990s, grain workers in Britain were frequently exposed to inhalable dust >10 mg.m(-3) (8 h), with particularly high exposures being found at terminals where grain was imported or exported and in drying operations (personal exposure typically approximately 20 mg.m(-3)). Since then, the industry has made substantial progress in improving the control of airborne dust through better-designed processes, increased automation, and an improved focus on product quality. We have used information from the published scientific literature and a small survey of industry representatives to estimate current exposure levels. These data suggest that current long-term exposure to inhalable dust for most workers is on average less than approximately 3 mg.m(-3), with perhaps 15-20% of individual personal exposures being >10 mg.m(-3). There are no published data from Britain on short-term exposure during cleaning and other tasks. We have estimated average levels for a range of tasks and judge that the highest levels, for example during some cleaning activities and certain process tasks such as loading and packing, are probably approximately10 mg.m(-3). Endotoxin levels were judged likely to be <10⁴ EU m(-3) throughout the industry provided inhalable dust levels are <10 mg.m(-3). There are no published exposure data on mycotoxin, respirable crystalline silica, and mite contamination but these are not considered to present widespread problems in the British industry. Further research should be carried out to confirm these findings.

  12. Grain Boundaries In Thin Film Organic Semiconductors

    NASA Astrophysics Data System (ADS)

    Bougher, Cortney; Huston, Shawn; Lees, Eitan; Ward, Jeremy; Obaid, Abdul; Loth, Marsha; Anthony, John; Jurchescu, Oana; Conrad, Brad

    2012-02-01

    We utilize conductive atomic force microscopy (C-AFM) and tunneling atomic force microscopy (TUNA) to characterize dynamics of electronic transport across fluorinated triethylsilylethynyl anthradithiophene (diF-TES ADT) grain boundaries. The crystallization of diF-TES ADT grown on SiO2 will be discussed and related to comparable molecules. The resulting voltage drop between individual crystals as a function of dopants will be discussed in terms of charge transport models and compared to current device work.

  13. Synthesis of fine-grained TATB

    DOEpatents

    Lee, Kien-Yin; Kennedy, James E.

    2003-04-15

    A method for producing fine-grained triamino-trinitrobenzene (TATB) powders having improved detonation-spreading performance and hence increased shock sensitivity when compared with that for ultrafine TATB is described. A single-step, sonochemical amination of trichloro-trinitrobenzene using ammonium hydroxide solution in a sealed vessel yields TATB having approximately 6 .mu.m median particle diameter and increased shock sensitivity.

  14. Grain-scale Dynamics in Explosives

    SciTech Connect

    Reaugh, J E

    2002-09-30

    High explosives can have reactions to external stimuli that range from mild pressure bursts to full detonation. The ability to predict these responses is important for understanding the performance as well as the safety and reliability of these important materials. At present, we have only relatively simple phenomenological computational models for the behavior of high explosives under these conditions. These models are limited by the assumption that the explosive can be treated as homogeneous. In reality the explosive is a highly heterogeneous composite of irregular crystallites and plastic binder. The heterogeneous nature of explosives is responsible for many of their unique mechanical and chemical properties. We use computational models to simulate the response of explosives to external mechanical stimuli at the grain-scale level. The ultimate goal of this work is to understand the detailed processes involved with the material response, so that we can develop realistic material models, which can be used in a hydrodynamics/multi-physics code to model real systems. The new material models will provide a more realistic description of the explosive system during the most critical period of ignition and initiation. The focus of this work is to use the results of grain-scale simulations to develop an advanced macroscopic reactive flow model that is consistent with our understanding of the grain-scale details, and that can incorporate such information quantitatively. The objective is to connect changes to observed properties of the explosive (grain size distribution, binder thickness distribution, void shape, size, and separation distribution, binder mechanical properties, etc.) with predictions of the resulting sensitivity and performance.

  15. Grain boundary and triple junction diffusion in nanocrystalline copper

    SciTech Connect

    Wegner, M. Leuthold, J.; Peterlechner, M.; Divinski, S. V.; Song, X.; Wilde, G.

    2014-09-07

    Grain boundary and triple junction diffusion in nanocrystalline Cu samples with grain sizes, 〈d〉, of ∼35 and ∼44 nm produced by spark plasma sintering were investigated by the radiotracer method using the {sup 63}Ni isotope. The measured diffusivities, D{sub eff}, are comparable with those determined previously for Ni grain boundary diffusion in well-annealed, high purity, coarse grained, polycrystalline copper, substantiating the absence of a grain size effect on the kinetic properties of grain boundaries in a nanocrystalline material at grain sizes d ≥ 35 nm. Simultaneously, the analysis predicts that if triple junction diffusion of Ni in Cu is enhanced with respect to the corresponding grain boundary diffusion rate, it is still less than 500⋅D{sub gb} within the temperature interval from 420 K to 470 K.

  16. 19. MOTOR FLOOR PLAN, GRAIN ELEVATOR. Plan No. 18069, 1904 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. MOTOR FLOOR PLAN, GRAIN ELEVATOR. Plan No. 18069, 1904 Conrail Microfilm MF004866 - West Shore Railroad, Pier 7 Grain Elevator, Hudson River & Pershing Road vicinity, West New York, Hudson County, NJ

  17. Loading spout and wheel for 1913 power grain shovel inside ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Loading spout and wheel for 1913 power grain shovel inside covered hopper loading dock at railroad level looking west - Stewart Company Grain Elevator, 16 West Carson Street, Pittsburgh, Allegheny County, PA

  18. 12. VIEW LOOKING SOUTHEAST, CHUTE TO RECEIVING HOPPER AND GRAIN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW LOOKING SOUTHEAST, CHUTE TO RECEIVING HOPPER AND GRAIN LEG REMAINS ON TRACK DECK - West Shore Railroad, Pier 7 Grain Elevator, Hudson River & Pershing Road vicinity, West New York, Hudson County, NJ

  19. 14. VIEW LOOKING WEST, GRAIN LEG REMAINS AND CHUTE OPENING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. VIEW LOOKING WEST, GRAIN LEG REMAINS AND CHUTE OPENING OVER RECEIVING HOPPER, ON TRACK DECK - West Shore Railroad, Pier 7 Grain Elevator, Hudson River & Pershing Road vicinity, West New York, Hudson County, NJ

  20. Effect of grain strength distribution on rock fracture

    SciTech Connect

    Woffington, Austin

    1996-05-01

    This report discloses my contributions to the study of grain strength distribution and its effects in computer modeled rock lattices. Frackrock v35.15 developed by Blair and Cook, was used to model bimodal grain strength distribution and test the lattices under stress. New data was gathered by running trials with a standardized weak grain strength and compared to the original data with a mean weak grain strength. The new data set shows lattice failure to be less predictable with a higher percentage of weak sites. Strain on the lattice is affected by the wide distribution of grain strengths: the closer the grain strengths are to each other, the more predictable they get. Further testing needs to be done on larger lattices, boundary less lattices, and multiple grain strength distributions. This will show the effects of size and stress on the grain distribution strength and will add to advancing our knowledge of how rocks crack and break under stressful conditions.

  1. Advanced Biorefinery of Distriller's Grain and Corn Stover Blends

    SciTech Connect

    2006-04-01

    Fuel ethanol can be produced via the dry milling process, which converts corn grain to ethanol. The co-product, distiller’s grain (DG), is sold as a low-cost, high-protein feed source for livestock.

  2. Grain Refinement of Permanent Mold Cast Copper Base Alloys

    SciTech Connect

    M.Sadayappan; J.P.Thomson; M.Elboujdaini; G.Ping Gu; M. Sahoo

    2005-04-01

    Grain refinement is a well established process for many cast and wrought alloys. The mechanical properties of various alloys could be enhanced by reducing the grain size. Refinement is also known to improve casting characteristics such as fluidity and hot tearing. Grain refinement of copper-base alloys is not widely used, especially in sand casting process. However, in permanent mold casting of copper alloys it is now common to use grain refinement to counteract the problem of severe hot tearing which also improves the pressure tightness of plumbing components. The mechanism of grain refinement in copper-base alloys is not well understood. The issues to be studied include the effect of minor alloy additions on the microstructure, their interaction with the grain refiner, effect of cooling rate, and loss of grain refinement (fading). In this investigation, efforts were made to explore and understand grain refinement of copper alloys, especially in permanent mold casting conditions.

  3. Communication Optimizations for Fine-Grained UPCApplications

    SciTech Connect

    Chen, Wei-Yu; Iancu, Costin; Yelick, Katherine

    2005-07-08

    Global address space languages like UPC exhibit high performance and portability on a broad class of shared and distributed memory parallel architectures. The most scalable applications use bulk memory copies rather than individual reads and writes to the shared space, but finer-grained sharing can be useful for scenarios such as dynamic load balancing, event signaling, and distributed hash tables. In this paper we present three optimization techniques for global address space programs with fine-grained communication: redundancy elimination, use of split-phase communication, and communication coalescing. Parallel UPC programs are analyzed using static single assignment form and a data flow graph, which are extended to handle the various shared and private pointer types that are available in UPC. The optimizations also take advantage of UPC's relaxed memory consistency model, which reduces the need for cross thread analysis. We demonstrate the effectiveness of the analysis and optimizations using several benchmarks, which were chosen to reflect the kinds of fine-grained, communication-intensive phases that exist in some larger applications. The optimizations show speedups of up to 70 percent on three parallel systems, which represent three different types of cluster network technologies.

  4. Process for producing large grain cadmium telluride

    DOEpatents

    Hasoon, F.S.; Nelson, A.J.

    1996-01-16

    A process is described for producing a cadmium telluride polycrystalline film having grain sizes greater than about 20 {micro}m. The process comprises providing a substrate upon which cadmium telluride can be deposited and placing that substrate within a vacuum chamber containing a cadmium telluride effusion cell. A polycrystalline film is then deposited on the substrate through the steps of evacuating the vacuum chamber to a pressure of at least 10{sup {minus}6} torr.; heating the effusion cell to a temperature whereat the cell releases stoichiometric amounts of cadmium telluride usable as a molecular beam source for growth of grains on the substrate; heating the substrate to a temperature whereat a stoichiometric film of cadmium telluride can be deposited; and releasing cadmium telluride from the effusion cell for deposition as a film on the substrate. The substrate then is placed in a furnace having an inert gas atmosphere and heated for a sufficient period of time at an annealing temperature whereat cadmium telluride grains on the substrate grow to sizes greater than about 20 {micro}m.

  5. Process for producing large grain cadmium telluride

    DOEpatents

    Hasoon, Falah S.; Nelson, Art J.

    1996-01-01

    A process for producing a cadmium telluride polycrystalline film having grain sizes greater than about 20 .mu.m. The process comprises providing a substrate upon which cadmium telluride can be deposited and placing that substrate within a vacuum chamber containing a cadmium telluride effusion cell. A polycrystalline film is then deposited on the substrate through the steps of evacuating the vacuum chamber to a pressure of at least 10.sup.-6 torr.; heating the effusion cell to a temperature whereat the cell releases stoichiometric amounts of cadmium telluride usable as a molecular beam source for growth of grains on the substrate; heating the substrate to a temperature whereat a stoichiometric film of cadmium telluride can be deposited; and releasing cadmium telluride from the effusion cell for deposition as a film on the substrate. The substrate then is placed in a furnace having an inert gas atmosphere and heated for a sufficient period of time at an annealing temperature whereat cadmium telluride grains on the substrate grow to sizes greater than about 20 .mu.m.

  6. Formation of water on warm dust grains

    NASA Astrophysics Data System (ADS)

    Vidali, Gianfranco; He, Jiao; Shi, Jianming; Hopkins, Tyler; Kaufman, Michael

    2015-08-01

    The early stage of water formation on dust grains in the ISM depends on sticking and retention of atoms and molecules on surfaces of grains. We investigated the interaction of oxygen with amorphous silicates. We find that atomic oxygen is retained on an amorphous silicate surface with a much higher binding energy (1850K ± 90K) than previously estimated (800K). We then used such value in the simulation of the chemical evolution of an interstellar environment - a molecular cloud edge in star-forming regions in Orion exposed to FUV illumination, and found that OH and H2O formation on grains is considerably enhanced while O2 formation is suppressed because of the higher O binding energy. These effects are especially important in dense gas exposed to high FUV fields because of the wider temperature range in which oxygen can reside. Because of the higher binding energy, photodesorption controls the gas phase chemistry. Consequences of this discovery for observations will be discussed.This work is supported by the NSF Astronomy and Astrophysics Division (Grant No.1311958 to GV) and by NASA support for US research with the Herschel Space Observatory (RSA No. 1427170 to MJK).

  7. Thermal motion of athermal driven grains

    NASA Astrophysics Data System (ADS)

    Ojha, Rajesh; Durian, D. J.; Dixon, P. K.

    2001-03-01

    The uniform upward gas flow in a gas-fluidized bed provides a homogeneous driving force. This allows a controlled study of the transition of a granular material from a static to a fluid-like state. Macroscopic properties of gas-fluidized beds, such as bed height, volume fraction, and gas pressure drop have been well-studied. However, experimental research on the dynamics of individual grains is lacking. Here, we use a scaled-up fluidized bed to observe grain motion. Our bed consists of a monolayer of ping-pong balls fluidized with air. High-speed photography allows us to track ball motions with high temporal resolution. From the images, we extract ball positions, velocities, and net forces due to the air turbulence. In the case of a lone ball, we find that a simple statistical mechanics model accurately describes its position, velocity, and energy distributions. Namely, it behaves exactly like a thermally-excited particle in a harmonic potential well. If such behavior holds for multiple balls, we will be able to develop a statistical mechanics description of grain interactions in an athermal driven system.

  8. Multiple age components in individual molybdenite grains

    USGS Publications Warehouse

    Aleinikoff, John N.; Creaser, Robert A.; Lowers, Heather; Magee, Charles W.; Grauch, Richard I.

    2012-01-01

    Re–Os geochronology of fractions composed of unsized, coarse, and fine molybdenite from a pod of unusual monazite–xenotime gneiss within a granulite facies paragneiss, Hudson Highlands, NY, yielded dates of 950.5 ± 2.5, 953.8 ± 2.6, and 941.2 ± 2.6 Ma, respectively. These dates are not recorded by co-existing zircon, monazite, or xenotime. SEM–BSE imagery of thin sections and separated grains reveals that most molybdenite grains are composed of core and rim plates that are approximately perpendicular. Rim material invaded cores, forming irregular contacts, probably reflecting dissolution/reprecipitation. EPMA and LA-ICP-MS analyses show that cores and rims have different trace element concentrations (for example, cores are relatively enriched in W). On the basis of inclusions of zircon with metamorphic overgrowths, we conclude that molybdenite cores and rims formed after high-grade regional metamorphism. The discovery of cores and rims in individual molybdenite grains is analogous to multi-component U-Pb geochronometers such as zircon, monazite, and titanite; thus, molybdenite should be carefully examined before dating to ensure that the requirement of age homogeneity is fulfilled.

  9. ACCELERATION OF SMALL ASTROPHYSICAL GRAINS DUE TO CHARGE FLUCTUATIONS

    SciTech Connect

    Ivlev, A. V.; Morfill, G. E.; Lazarian, A.; Hoang, Thiem; Tsytovich, V. N.; De Angelis, U.

    2010-11-01

    We discuss a novel mechanism of dust acceleration which may dominate for particles smaller than {approx}0.1 {mu}m. The acceleration is caused by their direct electrostatic interactions arising from fluctuations of grain charges. The energy sources for the acceleration are the irreversible plasma processes occurring on the grain surfaces. We show that this mechanism of charge-fluctuation-induced acceleration likely affects the rate of grain coagulation and shattering of the population of small grains.

  10. A Novel Method to Achieve Grain Refinement in Aluminum

    NASA Astrophysics Data System (ADS)

    Wang, Kui; Jiang, Haiyan; Wang, QuDong; Ye, Bing; Ding, Wenjiang

    2016-10-01

    A significant grain refinement of pure aluminum is achieved upon addition of TiCN nanoparticles (NPs). Unlike the conventional inoculation, NPs can induce the physical growth restriction through the formation of NP layer on the growing grain surface. An analytical model is developed to quantitatively account for the NP effects on grain growth. The NP-induced growth control can overcome the inherent limitations of inoculation and shed light on a potential method to achieve grain refinement.

  11. Observational support for dust grain emission by electrostatic forces

    NASA Astrophysics Data System (ADS)

    Silen, Johan; Hilchenbach, Martin; Hornung, Klaus; Merouane, Sihane; Schulz, Rita

    2015-04-01

    Dust collected close to the comet 67P by the COSIMA instrument, indicates that fluffy grains up to sizes of several 100 um are lifted off the comet surface and transported to the instrument substrate several tens of kilometers away. The temperature of the surface and the detected gas densities are too low to properly explain lifting grains from the cometary surface. We investigate grain dynamics using electrostatic forces. Comet surface lighting conditions create small scale multi pole electric fields by photons. These fields create forces on both charged and neutral dust grains and may serve as "active regions". The forces acting on the grain, scale as D3 with grain size and therefore large grains are proportionally simpler to elevate, provided the mass is not increasing at the same rate. The fluffy structure of the grains seem to fulfill this requirement. The limiting factor of this mechanism is set by the tensile strength of the grains. If the electrostatic force created exceeds the tensile strength, the grain will disintegrate through Coulomb explosion. The mechanism would favor lifting large fluffy grains off the surface because they have a capability of most easily creating mobile charges which interact in a favorable manner with the multi pole fields. Because of the conglomerate nature of the grains, a splitting of a grain may trigger a Coulomb explosion setting free the bulk dust distribution of small grains detected. The measured elongated impacts also suggest that disintegration is taking place close to the spacecraft. This would also be supported by the proposed model as the space craft charging represents a small scale field anomaly where grain splitting could become enhanced. The observed grains seem to fulfill all requirements of this tentative model.

  12. Ancient whole grain gluten-free egg-free Pasta

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA food guide recommends that at least ½ of all the grains eaten should be whole grains. The FDA allows food Health Claim labels for food containing 51% whole gains and 11 g of dietary fiber per serving. This is the only report demonstrating innovative ancient whole grain, gluten-free, egg-fre...

  13. Grain size dependence of silicon solar cell parameters

    NASA Technical Reports Server (NTRS)

    Koliwad, K. M.; Daud, T.

    1980-01-01

    Measurements of the non-uniform diffusion length of the minority carriers near grain boundaries in polycrystalline silicon have been used to develop an analytical model for the calculation of solar cell output as a function of grain size. Experimental results are presented which verify the theoretical analysis. Variation of open circuit voltage and fill factor with grain size is discussed.

  14. Experimental studies of the structure of grain boundaries

    SciTech Connect

    Sass, S.L.

    1993-04-01

    Goals are to understand factors affecting structure of grain boundaries in intermetallic compounds, understand how solute segregation affects grain boundary structure and causes embrittlement in Fe-base alloys, and explore control of grain boundary properties. Fe and boron-doped Ni[sub 3]Al and NiAl were studied. 7 figs, 1 tab, 18 refs.

  15. 7 CFR 800.16 - Certification requirements for export grain.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Certification requirements for export grain. 800.16 Section 800.16 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE...

  16. 7 CFR 800.98 - Weighing grain in combined lots.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Weighing grain in combined lots. 800.98 Section 800.98 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  17. 7 CFR 810.801 - Definition of mixed grain.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 7 2013-01-01 2013-01-01 false Definition of mixed grain. 810.801 Section 810.801 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL UNITED STATES STANDARDS...

  18. 7 CFR 810.801 - Definition of mixed grain.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Definition of mixed grain. 810.801 Section 810.801 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL UNITED STATES STANDARDS...

  19. 7 CFR 800.16 - Certification requirements for export grain.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Certification requirements for export grain. 800.16 Section 800.16 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE...

  20. 7 CFR 810.801 - Definition of mixed grain.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Definition of mixed grain. 810.801 Section 810.801 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL UNITED STATES STANDARDS...

  1. 7 CFR 800.30 - Foreign commerce grain business.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Foreign commerce grain business. 800.30 Section 800.30 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  2. 7 CFR 810.801 - Definition of mixed grain.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Definition of mixed grain. 810.801 Section 810.801 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL UNITED STATES STANDARDS...

  3. 7 CFR 800.98 - Weighing grain in combined lots.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Weighing grain in combined lots. 800.98 Section 800.98 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  4. 7 CFR 800.99 - Checkweighing sacked grain.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Checkweighing sacked grain. 800.99 Section 800.99 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  5. 7 CFR 800.16 - Certification requirements for export grain.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 7 2013-01-01 2013-01-01 false Certification requirements for export grain. 800.16 Section 800.16 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE...

  6. 7 CFR 75.21 - Grain sample inspection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Grain sample inspection. 75.21 Section 75.21... AND CERTIFICATION OF QUALITY OF AGRICULTURAL AND VEGETABLE SEEDS Inspection § 75.21 Grain sample inspection. A sample inspection shall be performed by examining official grain samples received from FGIS...

  7. 7 CFR 800.30 - Foreign commerce grain business.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Foreign commerce grain business. 800.30 Section 800.30 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  8. 7 CFR 810.801 - Definition of mixed grain.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 7 2012-01-01 2012-01-01 false Definition of mixed grain. 810.801 Section 810.801 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL UNITED STATES STANDARDS...

  9. 7 CFR 800.16 - Certification requirements for export grain.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 7 2012-01-01 2012-01-01 false Certification requirements for export grain. 800.16 Section 800.16 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE...

  10. 7 CFR 75.21 - Grain sample inspection.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Grain sample inspection. 75.21 Section 75.21... AND CERTIFICATION OF QUALITY OF AGRICULTURAL AND VEGETABLE SEEDS Inspection § 75.21 Grain sample inspection. A sample inspection shall be performed by examining official grain samples received from FGIS...

  11. 7 CFR 800.30 - Foreign commerce grain business.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 7 2013-01-01 2013-01-01 false Foreign commerce grain business. 800.30 Section 800.30 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  12. 7 CFR 800.99 - Checkweighing sacked grain.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Checkweighing sacked grain. 800.99 Section 800.99 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  13. 7 CFR 75.21 - Grain sample inspection.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Grain sample inspection. 75.21 Section 75.21... AND CERTIFICATION OF QUALITY OF AGRICULTURAL AND VEGETABLE SEEDS Inspection § 75.21 Grain sample inspection. A sample inspection shall be performed by examining official grain samples received from FGIS...

  14. 7 CFR 800.30 - Foreign commerce grain business.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Foreign commerce grain business. 800.30 Section 800.30 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  15. 7 CFR 800.16 - Certification requirements for export grain.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Certification requirements for export grain. 800.16 Section 800.16 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE...

  16. 7 CFR 800.30 - Foreign commerce grain business.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 7 2012-01-01 2012-01-01 false Foreign commerce grain business. 800.30 Section 800.30 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  17. 7 CFR 800.98 - Weighing grain in combined lots.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Weighing grain in combined lots. 800.98 Section 800.98 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  18. 7 CFR 800.99 - Checkweighing sacked grain.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 7 2013-01-01 2013-01-01 false Checkweighing sacked grain. 800.99 Section 800.99 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  19. 7 CFR 75.21 - Grain sample inspection.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Grain sample inspection. 75.21 Section 75.21... AND CERTIFICATION OF QUALITY OF AGRICULTURAL AND VEGETABLE SEEDS Inspection § 75.21 Grain sample inspection. A sample inspection shall be performed by examining official grain samples received from FGIS...

  20. 7 CFR 75.21 - Grain sample inspection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Grain sample inspection. 75.21 Section 75.21... AND CERTIFICATION OF QUALITY OF AGRICULTURAL AND VEGETABLE SEEDS Inspection § 75.21 Grain sample inspection. A sample inspection shall be performed by examining official grain samples received from FGIS...

  1. 7 CFR 800.98 - Weighing grain in combined lots.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 7 2012-01-01 2012-01-01 false Weighing grain in combined lots. 800.98 Section 800.98 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  2. 7 CFR 800.99 - Checkweighing sacked grain.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 7 2012-01-01 2012-01-01 false Checkweighing sacked grain. 800.99 Section 800.99 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  3. 7 CFR 800.98 - Weighing grain in combined lots.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 7 2013-01-01 2013-01-01 false Weighing grain in combined lots. 800.98 Section 800.98 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  4. 7 CFR 800.99 - Checkweighing sacked grain.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Checkweighing sacked grain. 800.99 Section 800.99 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS...

  5. Laboratory milling method for whole grain soft wheat flour evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole grain wheat products are a growing portion of the foods marked in North America, yet few standard methods exist to evaluate whole grain wheat flour. This study evaluated two flour milling systems to produce whole grain soft wheat flour for a standard soft wheat product, a wire-cut cookie. A...

  6. On the origins of GEMS grains: A reply

    NASA Astrophysics Data System (ADS)

    Keller, Lindsay P.; Messenger, Scott

    2013-04-01

    The Comment by Bradley challenges our chemical and isotopic measurements of GEMS grains, arguing that pervasive infiltration of silicone oil and sample heating undermine our comparisons with equally uncertain interstellar grain compositions. However, we have already shown that such effects are negligible and cannot account for the extraordinary chemical variability of GEMS grains. Our data are also in excellent agreement with previous GEMS grain chemical analyses, and with GEMS grains in micrometeorites and within IDPs recently collected without the use of silicone oil. The order of magnitude variations in element abundances displayed by GEMS grains rule out a common origin by the extensive chemical and isotopic homogenization of circumstellar grains, as proposed by Bradley. The vast majority of GEMS grains also do not have radial compositional gradients, crystalline "relict" cores, or rims of condensed materials indicative of radiation exposure. The average element abundances of GEMS grains differ significantly and systematically from solar abundances and from those inferred for interstellar silicates based on element depletion patterns. A few GEMS grains have highly anomalous O isotopic compositions consistent with a condensation origin in evolved O-rich stellar envelopes and supernovae. Yet, on average, GEMS grains have O isotopic compositions very near to terrestrial and meteoritic values. These and other observations discussed in our paper place a strict upper limit on the number of GEMS grains that have preserved presolar origins.

  7. 77 FR 50763 - Notice of National Grain Car Council Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... Surface Transportation Board Notice of National Grain Car Council Meeting AGENCY: Surface Transportation Board, DOT. ACTION: Notice of National Grain Car Council meeting. SUMMARY: Notice is hereby given of a meeting of the National Grain Car Council (NGCC), pursuant to section 10(a)(2) of the Federal...

  8. 75 FR 53736 - Notice of National Grain Car Council Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-01

    ... Surface Transportation Board Notice of National Grain Car Council Meeting AGENCY: Surface Transportation Board, DOT. ACTION: Notice of National Grain Car Council meeting. SUMMARY: Notice is hereby given of a meeting of the National Grain Car Council (NGCC), pursuant to section 10(a)(2) of the Federal...

  9. 78 FR 52606 - Notice of National Grain Car Council Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-23

    ... Surface Transportation Board Notice of National Grain Car Council Meeting AGENCY: Surface Transportation Board, DOT. ACTION: Notice of National Grain Car Council meeting. SUMMARY: Notice is hereby given of a meeting of the National Grain Car Council (NGCC), pursuant to the Federal Advisory Committee Act, 5...

  10. 76 FR 53717 - Notice of National Grain Car Council Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-29

    ... Surface Transportation Board Notice of National Grain Car Council Meeting AGENCY: Surface Transportation Board. ACTION: Notice of National Grain Car Council meeting. SUMMARY: Notice is hereby given of a meeting of the National Grain Car Council (NGCC), pursuant to section 10(a)(2) of the Federal...

  11. Crop water production functions for grain sorghum and winter wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Productivity of water-limited cropping systems can be reduced by untimely distribution of water as well as cold and heat stress. The objective was to develop relationships among weather parameters, water use, and grain productivity to produce functions forecasting grain yields of grain sorghum and w...

  12. Whole grain foods and health - a Scandinavian perspective.

    PubMed

    Frølich, Wenche; Aman, Per; Tetens, Inge

    2013-01-01

    The food-based dietary guidelines in the Scandinavian countries that recommend an intake of minimum 75 g whole grain per 10 MJ (2,388 kcal) per day are mainly derived from prospective cohort studies where quantitative but little qualitative details are available on whole grain products. The objective of the current paper is to clarify possible differences in nutritional and health effects of the types of whole grain grown and consumed in the Scandinavian countries. A further objective is to substantiate how processing may influence the nutritional value and potential health effects of different whole grains and whole grain foods. The most commonly consumed whole grain cereals in the Scandinavian countries are wheat, rye, and oats with a considerable inter-country variation in the consumption patterns and with barley constituting only a minor role. The chemical composition of these different whole grains and thus the whole grain products consumed vary considerably with regard to the content of macro- and micronutrients and bioactive components. A considerable amount of scientific substantiation shows that processing methods of the whole grains are important for the physiological and health effects of the final whole grain products. Future research should consider the specific properties of each cereal and its processing methods to further identify the uniqueness and health potentials of whole grain products. This would enable the authorities to provide more specific food-based dietary guidelines in relation to whole grain to the benefit of both the food industry and the consumer. PMID:23411562

  13. Whole grain foods and health – a Scandinavian perspective

    PubMed Central

    Frølich, Wenche; Åman, Per; Tetens, Inge

    2013-01-01

    The food-based dietary guidelines in the Scandinavian countries that recommend an intake of minimum 75 g whole grain per 10 MJ (2,388 kcal) per day are mainly derived from prospective cohort studies where quantitative but little qualitative details are available on whole grain products. The objective of the current paper is to clarify possible differences in nutritional and health effects of the types of whole grain grown and consumed in the Scandinavian countries. A further objective is to substantiate how processing may influence the nutritional value and potential health effects of different whole grains and whole grain foods. The most commonly consumed whole grain cereals in the Scandinavian countries are wheat, rye, and oats with a considerable inter-country variation in the consumption patterns and with barley constituting only a minor role. The chemical composition of these different whole grains and thus the whole grain products consumed vary considerably with regard to the content of macro- and micronutrients and bioactive components. A considerable amount of scientific substantiation shows that processing methods of the whole grains are important for the physiological and health effects of the final whole grain products. Future research should consider the specific properties of each cereal and its processing methods to further identify the uniqueness and health potentials of whole grain products. This would enable the authorities to provide more specific food-based dietary guidelines in relation to whole grain to the benefit of both the food industry and the consumer. PMID:23411562

  14. Cool Bottom Processing on the AGB and Presolar Grain Compositions

    NASA Technical Reports Server (NTRS)

    Nollett, Kenneth M.; Busso, M.; Wasserburg, G. J.

    2002-01-01

    We describe results from a model of cool bottom processing (CBP) in AGB (asymptotic giant branch) stars. We predict O, Al, C and N isotopic compositions of circumstellar grains. Measured compositions of mainstream SiC grains and many oxide grains are consistent with CBP. Additional information is contained in the original extended abstract.

  15. Computer simulation of grain boundaries in Ni/sub 3/Al: The effect of grain boundary composition

    SciTech Connect

    Chen, S.P.; Voter, A.F.; Srolovitz, D.J.

    1986-01-01

    The authors have performed atomistic simulations on three (001) symmetric tilt grain boundaries: 5(210), (310), and 13(320). Depending on which sub-lattice in each of the two grains is occupied by Al, the grain boundary may have different stoichiometries. All of the simulations show that the Al-rich grain boundaries have the highest grain boundary energies. Thus Al-rich grain boundaries are more likely to fail than those which have the bulk stoichiometry or are Ni-rich. This conclusion is consistent with the observed stoichiometry dependence of the beneficial boron effect. The similarity between the grain boundary energies (cohesive energies) of Ni/sub 3/Al and Ni and the much higher yield stress of Ni/sub 3/Al provides a justification for the ''inherent'' brittleness of Ni/sub 3/Al grain boundaries.

  16. Supplying materials needed for grain growth characterizations of nano-grained UO2

    SciTech Connect

    Mo, Kun; Miao, Yinbin; Yun, Di; Jamison, Laura M.; Lian, Jie; Yao, Tiankei

    2015-09-30

    This activity is supported by the US Nuclear Energy Advanced Modeling and Simulation (NEAMS) Fuels Product Line (FPL) and aims at providing experimental data for the validation of the mesoscale simulation code MARMOT. MARMOT is a mesoscale multiphysics code that predicts the coevolution of microstructure and properties within reactor fuel during its lifetime in the reactor. It is an important component of the Moose-Bison-Marmot (MBM) code suite that has been developed by Idaho National Laboratory (INL) to enable next generation fuel performance modeling capability as part of the NEAMS Program FPL. In order to ensure the accuracy of the microstructure based materials models being developed within the MARMOT code, extensive validation efforts must be carried out. In this report, we summarize our preliminary synchrotron radiation experiments at APS to determine the grain size of nanograin UO2. The methodology and experimental setup developed in this experiment can directly apply to the proposed in-situ grain growth measurements. The investigation of the grain growth kinetics was conducted based on isothermal annealing and grain growth characterization as functions of duration and temperature. The kinetic parameters such as activation energy for grain growth for UO2 with different stoichiometry are obtained and compared with molecular dynamics (MD) simulations.

  17. Grain-to-Grain Compositional Variations and Phase Segregation in Copper-Zinc-Tin-Sulfide Films.

    PubMed

    Alvarez Barragan, Alejandro; Malekpour, Hoda; Exarhos, Stephen; Balandin, Alexander A; Mangolini, Lorenzo

    2016-09-01

    We have performed a rigorous investigation of the structure and composition of individual grains in copper-zinc-tin-sulfide (CZTS) films realized by sulfurization of a sputtered metal stack. Although on average close to the ideal CZTS stoichiometry, elemental analysis shows significant grain-to-grain variations in composition. High-resolution Raman spectroscopy indicates that this is accompanied by grain-to-grain structural variations as well. The intensity from the 337 cm(-1) Raman peak, generally assigned to the kesterite phase of CZTS, remains constant over a large area of the sample. On the other hand, signals from secondary phases at 376 cm(-1) (copper-tin-sulfide) and 351 cm(-1) (zinc-sulfide) show significant variation over the same area. These results confirm the great complexity inherent to this material system. Moreover, structural and compositional variations are recognized in the literature as a factor limiting the efficiency of CZTS photovoltaic devices. This study demonstrates how a seemingly homogeneous CZTS thin film can actually have considerable structural and compositional variations at the microscale, and highlights the need for routine microscale characterization in this material system. PMID:27538122

  18. Ultrafast analysis of individual grain behavior during grain growth by parallel computing

    NASA Astrophysics Data System (ADS)

    Kühbach, M.; Barrales-Mora, L. A.; Mießen, C.; Gottstein, G.

    2015-08-01

    The possibility to characterize in an automatized way the spatial-temporal evolution of individual grains and their properties is essential to the understanding of annealing phenomena. The development of advanced experimental techniques, computational models and tools helps the acquisition of real time and real space-resolved datasets. Whereas the reconstruction of 3D grain representatives from serial-sectioning or tomography datasets becomes more common and microstructure simulations on parallel computers become ever larger and longer lasting, few efforts have materialized in the development of tools that allow the continuous tracking of properties at the grain scale. In fact, such analyses are often left neglected in practice due to the large size of the datasets that exceed the available physical memory of a computer or the shared-memory cluster. We identified the key tasks that have to be solved in order to define suitable and lean data structures and computational methods to evaluate spatio-temporal grain property datasets by working with parallel computer architectures. This is exemplified with data from grain growth simulations.

  19. Comparison of microstructure of superplastically deformed synthetic materials and ultramylonite: Coalescence of secondary mineral grains via grain boundary sliding

    NASA Astrophysics Data System (ADS)

    Hiraga, T.; Miyazaki, T.; Tasaka, M.; Yoshida, H.

    2011-12-01

    Using very fine-grained aggregates of forsterite containing ~10vol% secondary mineral phase such as periclase and enstatite, we have been able to demonstrate their superplascity, that is, achievement of more than a few 100 % tensile strain (Hiraga et al. 2010). Superplastic deformation is commonly considered to proceed via grain boundary sliding (GBS) which results in grain switching in the samples. Hiraga et al. (2010) succeeded in detecting the operation of GBS from observing the coalescence of grains of secondary phase in superplastically deformed samples. The secondary phase pins the motion of grain boundaries of the primary phase; however, the reduction of the number of the grains of secondary phase due to their coalescence allows grain growth of the primary phase. We analyzed the relationships between grain size of the primary and secondary phases, between strain and grain size, and between strain and the number of coalesced grains in the superplastically deformed samples. The results supports participation of all the grains of the primary phase in grain switching process indicating that the grain boundary sliding accommodates almost entire strain during the deformation. Mechanical properties of these materials such as their stress and grain size exponents of 1-2 do not conflict this conclusion. We applied the relationships obtained from analyzing superplastic materials to the microstructure of the natural samples, which has been considered to have deformed via grain boundary sliding, that is, ultramylonite. The microstructure of greenschist-grade ultramylonite reported by Fliervoet et al. (1997) was analyzed. Distributions of the mineral phases (i.e., quartz, plagioclase, K-feldspar and biotite) show distinct coalescence of the same mineral phases in the direction almost perpendicular to the foliation of the rock. The number of coalesced grains indicates that the strain that rock experienced is > 2. [reference] Hiraga et al. (2010) Nature 468, 1091

  20. Grain Boundary Traction Signatures: Quantitative Predictors of Dislocation Emission

    NASA Astrophysics Data System (ADS)

    Li, Ruizhi; Chew, Huck Beng

    2016-08-01

    We introduce the notion of continuum-equivalent traction fields as local quantitative descriptors of the grain boundary interface. These traction-based descriptors are capable of predicting the critical stresses to trigger dislocation emissions from ductile ⟨110 ⟩ symmetrical-tilt nickel grain boundaries. We show that Shockley partials are emitted when the grain boundary tractions, in combination with external tensile loading, generate a resolved shear stress to cause dislocation slip. The relationship between the local grain boundary tractions and the grain boundary energy is established.

  1. Grain Boundary Traction Signatures: Quantitative Predictors of Dislocation Emission.

    PubMed

    Li, Ruizhi; Chew, Huck Beng

    2016-08-19

    We introduce the notion of continuum-equivalent traction fields as local quantitative descriptors of the grain boundary interface. These traction-based descriptors are capable of predicting the critical stresses to trigger dislocation emissions from ductile ⟨110⟩ symmetrical-tilt nickel grain boundaries. We show that Shockley partials are emitted when the grain boundary tractions, in combination with external tensile loading, generate a resolved shear stress to cause dislocation slip. The relationship between the local grain boundary tractions and the grain boundary energy is established. PMID:27588865

  2. The Grain Structure of Castings: Some Aspects of Modelling

    NASA Technical Reports Server (NTRS)

    Hellawell, A.

    1995-01-01

    The efficacy of the modelling of the solidification of castings is typically tested against observed cooling curves and the final grain structures and sizes. Without thermo solutal convection, equiaxed grain formation is promoted by introduction of heterogeneous substrates into the melt, as grain refiners. With efficient thermo solutal convection, dendrite fragments from the mushy zone can act as an intrinsic source of equiaxed grains and resort to grain refining additions is unnecessary. The mechanisms of dendrite fragmentation and transport of these fragments are briefly considered.

  3. Grain orientations and grain boundaries in tungsten nonotendril fuzz grown under divertor-like conditions

    DOE PAGESBeta

    Parish, Chad M.; Wang, Kun; Doerner, Russel P.; Baldwin, Matthew J.

    2016-09-19

    We grew nanotendril “fuzz” on tungsten via plasma exposure and performed transmission Kikuchi diffraction (tKD) in scanning electron microscopy of isolated nanotendrils. 900 °C, 1023 He/m2sec, 4 × 1026 He/m2 exposure of tungsten produced a deep and fully developed nanotendril mat. tKD of isolated nanotendrils indicated that there was no preferred crystallographic direction oriented along the long axes of the tendrils, and the grain boundary character showed slightly preferential orientations. In conclusion, tendril growth is sufficiently non-equilibrium to prevent any preference of growth direction to manifest measurably, and that new high-angle boundaries (with new grains and grain-growth axes) nucleate randomlymore » along the tendrils during growth.« less

  4. Kinetic Modeling of Sunflower Grain Filling and Fatty Acid Biosynthesis.

    PubMed

    Durruty, Ignacio; Aguirrezábal, Luis A N; Echarte, María M

    2016-01-01

    Grain growth and oil biosynthesis are complex processes that involve various enzymes placed in different sub-cellular compartments of the grain. In order to understand the mechanisms controlling grain weight and composition, we need mathematical models capable of simulating the dynamic behavior of the main components of the grain during the grain filling stage. In this paper, we present a non-structured mechanistic kinetic model developed for sunflower grains. The model was first calibrated for sunflower hybrid ACA855. The calibrated model was able to predict the theoretical amount of carbohydrate equivalents allocated to the grain, grain growth and the dynamics of the oil and non-oil fraction, while considering maintenance requirements and leaf senescence. Incorporating into the model the serial-parallel nature of fatty acid biosynthesis permitted a good representation of the kinetics of palmitic, stearic, oleic, and linoleic acids production. A sensitivity analysis showed that the relative influence of input parameters changed along grain development. Grain growth was mostly affected by the specific growth parameter (μ') while fatty acid composition strongly depended on their own maximum specific rate parameters. The model was successfully applied to two additional hybrids (MG2 and DK3820). The proposed model can be the first building block toward the development of a more sophisticated model, capable of predicting the effects of environmental conditions on grain weight and composition, in a comprehensive and quantitative way.

  5. Grain size evolution and convection regimes of the terrestrial planets

    NASA Astrophysics Data System (ADS)

    Rozel, A.; Golabek, G. J.; Boutonnet, E.

    2011-12-01

    A new model of grain size evolution has recently been proposed in Rozel et al. 2010. This new approach stipulates that the grain size dynamics is governed by two additive and simultaneous processes: grain growth and dynamic recrystallization. We use the usual normal grain growth laws for the growth part. For dynamic recrystallization, reducing the mean grain size increases the total area of grain boundaries. Grain boundaries carry some surface tension, so some energy is required to decrease the mean grain size. We consider that this energy is available during mechanical work. It is usually considered to produce some heat via viscous dissipation. A partitioning parameter f is then required to know what amount of energy is dissipated and what part is converted in surface tension. This study gives a new calibration of the partitioning parameter on major Earth materials involved in the dynamic of the terrestrial planets. Our calibration is in adequation with the published piezometric relations available in the literature (equilibrium grain size versus shear stress). We test this new model of grain size evolution in a set of numerical computations of the dynamics of the Earth using stagYY. We show that the grain size evolution has a major effect on the convection regimes of terrestrial planets.

  6. The Search for Supernova Grains in an Ice Core

    NASA Astrophysics Data System (ADS)

    Cole, A. L.; Boyd, R. N.; Davis, M. E.; Thompson, L. G.; Davis, A. M.; Lewis, R. S.; Zinner, E.

    2006-12-01

    A search was conducted for grains of the potential core-collapse supernova (SN) condensate minerals corundum (Al2O3), hibonite (CaAl12O19), and spinel (MgAl2O4) among grains filtered from the 308.6 m Guliya ice core recovered from the Qinghai-Tibetan plateau in China. Simple models are developed and calculations are presented to estimate the number of Al2O3 grains that would be deposited per cm2 on the Earth by a nearby core-collapse SN and to estimate the number of presolar oxide grains that could be contained in micrometeorite (MM) grains that are accreted by the Earth. A total of 698 candidate SN condensate grains were identified in six Guliya ice core grain samples from the following time periods: ~2-10, ~25-27, ~34-36, ~53-57, ~59-62, and ~68-72 kyr. A procedure developed at the University of Chicago to identify presolar grains in meteoric samples was used to find these candidate grains. Nanometer-scale secondary ion mass spectrometry (NanoSIMS) analysis, performed at Washington University on 37 grains from the ~34-36, ~53-57, and ~59-62 kyr samples, indicated that none possessed the extreme oxygen-16 enhancements expected from a SN source. However, nine of the 37 grains did possess the oxygen-16 enhancements consistent with calcium-aluminum-rich inclusions (CAIs).

  7. Radiation Pressure on Fluffy Submicron-sized Grains

    NASA Astrophysics Data System (ADS)

    Silsbee, Kedron; Draine, Bruce T.

    2016-02-01

    We investigate the claim that the ratio β of radiation pressure force to gravitational force on a dust grain in our solar system can substantially exceed unity for some grain sizes, provided that grain porosity is high enough. For model grains consisting of random aggregates of silicate spherules, we find that the maximum value of β is almost independent of grain porosity, but for small (\\lt 0.3 μ {{m}}) grains, β actually decreases with increasing porosity. We also investigate the effect of metallic iron and amorphous carbon inclusions in the dust grains and find that while these inclusions do increase the radiation pressure cross-section, β remains below unity for grains with 3 pg of silicate material. These results affect the interpretation of the grain trajectories estimated from the Stardust mission, which were modeled assuming β values exceeding one. We find that radiation pressure effects are not large enough for particles Orion and Hylabrook captured by Stardust to be of interstellar origin given their reported impact velocities. We also consider the effects of solar radiation on transverse velocities and grain spin, and show that radiation pressure introduces both transverse velocities and equatorial spin velocities of several hundred meters per second for incoming interstellar grains at 2 au. These transverse velocities are not important for modeling trajectories, but such spin rates may result in centrifugal disruption of aggregates.

  8. Rate of H2 formation on amorphous grains

    NASA Technical Reports Server (NTRS)

    Smoluchowski, R.

    1981-01-01

    The rate of formation of molecular hydrogen from hydrogen atoms adsorbed on amorphous grains taken to represent interstellar dust grains is analyzed. Following a brief review of the structure and thermodynamics of amorphous grains and the evidence that interstellar grains are indeed amorphous, consideration is given to the mechanism of formation of H2 molecules by the impact of H atoms on grains with adsorbed H atoms, and it is concluded that on amorphous grains, molecule formation will only occur if H atoms are adsorbed within a distance on the order of 10 A of each other. Rates of H2 formation on single crystal and polycrystalline grains are then calculated and compared with those for amorphous grains, and it is shown that, except for certain temperatures and high H atom densities, the rates of H2 formation on polycrystalline and amorphous grains are up to a few orders of magnitude lower than on single crystals. The results suggest that amorphous grains will lead to H2 clouds with irregular and sharply delineated features in contrast to the more uniform clouds formed on crystalline grains.

  9. Kinetic Modeling of Sunflower Grain Filling and Fatty Acid Biosynthesis

    PubMed Central

    Durruty, Ignacio; Aguirrezábal, Luis A. N.; Echarte, María M.

    2016-01-01

    Grain growth and oil biosynthesis are complex processes that involve various enzymes placed in different sub-cellular compartments of the grain. In order to understand the mechanisms controlling grain weight and composition, we need mathematical models capable of simulating the dynamic behavior of the main components of the grain during the grain filling stage. In this paper, we present a non-structured mechanistic kinetic model developed for sunflower grains. The model was first calibrated for sunflower hybrid ACA855. The calibrated model was able to predict the theoretical amount of carbohydrate equivalents allocated to the grain, grain growth and the dynamics of the oil and non-oil fraction, while considering maintenance requirements and leaf senescence. Incorporating into the model the serial-parallel nature of fatty acid biosynthesis permitted a good representation of the kinetics of palmitic, stearic, oleic, and linoleic acids production. A sensitivity analysis showed that the relative influence of input parameters changed along grain development. Grain growth was mostly affected by the specific growth parameter (μ′) while fatty acid composition strongly depended on their own maximum specific rate parameters. The model was successfully applied to two additional hybrids (MG2 and DK3820). The proposed model can be the first building block toward the development of a more sophisticated model, capable of predicting the effects of environmental conditions on grain weight and composition, in a comprehensive and quantitative way. PMID:27242809

  10. Jamming of Cylindrical Grains in Featureless Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; Barr, Nicholas; Weible, Seth; Friedl, Nicholas

    2013-03-01

    We study jamming of low aspect-ratio cylindrical Delrin grains falling through a featureless vertical channel. With a grain height less than the grain diameter, these grains resemble aspirin tablets, poker chips, or coins. Unidisperse grains are allowed to fall under the influence of gravity through a uniform channel of square cross-section where the channel width is greater than the grain size and constant along the length of the channel. Channel widths are chosen so that no combination of grain heights and diameters is equal to the channel width. Collections of grains sometimes form jams, stable structures in which the grains are supported by the channel walls and not by grains or walls beneath them. The probability of a jam occurring and the jam's strength are influenced by the grain dimensions and channel width. We will present experimental measurements of the jamming probability and jam strength and discuss the relationship of these results to other experiments and theories. Supported by an Undergraduate Research Grant from Penn State Erie, The Behrend College

  11. Sodium Salts in Ice Grains from Enceladus

    NASA Astrophysics Data System (ADS)

    Postberg, F.; Kempf, S.; Schmidt, J.; Brillantov, N.; Abel, B.; Beinsen, A.; Buck, U.; Srama, R.

    2009-04-01

    One key requirement for the formation of life precursors on Enceladus, is liquid water below its icy surface. Although measurements and model calculations for Enceladus plume source suggest temperatures close to the melting point, direct evidence for liquid water has not been produced so far. We present compositional measurements by Cassini's dust detector of ice particles emitted from Saturn's cryo-volcanic moon Enceladus into the E ring. Since sodium is considered as crucial indicator for an Enceladus ocean, our detection of sodium salts within the grains provide the first evidence for mineral enriched liquid water below the moon's icy surface. In nearly all particles detected in situ by the Cosmic Dust Analyser (CDA) aboard the Cassini spacecraft, we found sodium (Na) in varying concentrations. Most spectra also show potassium (K) in lower abundance. In mass spectra that are particularly sodium rich, sodium salts (like NaCl and NaHCO3) are identified as Na bearing components. This is only possible if the plume source is liquid water that is or has been in contact with the rocky material of Enceladus' core. The abundance of minerals as well as the inferred basic pH value of those grains exhibit a compelling similarity with the predicted composition of an Enceladus ocean. The Na-rich ice particles likely are frozen ocean droplets expelled through the plumes into the E ring. From the compositional analysis, models for grain production and ejection can be derived which give new insights in plume dynamics and subsurface processes. They also allow the refinement of models for a water-rock-interaction at the bottom of the liquid layer.

  12. Towards the limit of ferroelectric nanosized grains

    NASA Astrophysics Data System (ADS)

    Roelofs, A.; Schneller, T.; Szot, K.; Waser, R.

    2003-02-01

    Ferroelectric random access memories are non-volatile, low voltage, high read/write speed devices which have been introduced into the market in recent years and which show the clear potential of future gigabit scale universal non-volatile memories. The ultimate limit of this concept will depend on the ferroelectric limit (synonymous superparaelectric limit), i.e. the size limit below which the ferroelectricity is quenched. While there are clear indications that 2D ferroelectric oxide films may sustain their ferroelectric polarization below 4 nm in thickness (Tybell T, Ahn C H and Triscone J M 1999 Appl. Phys. Lett. 75 856), the limit will be quite different for isolated 3D nanostructures (nanograins, nanoclusters). To investigate scaling effects of ferroelectric nanograins on Si wafers, we studied PbTiO3 (PTO) and Pb(ZrxTi1-x)O3 grown by a self-assembly chemical solution deposition method. Preparing highly diluted precursor solutions we achieved single separated ferroelectric grains with grain sizes ranging from 200 nm down to less than 20 nm. For grains smaller than 20 nm, no piezoresponse was observed and we suppose this could be due to the transition from the ferroelectric to the paraelectric phase which has no spontaneous polarization. Recent calculations (Zhong W L, Wang Y G, Zhang P L and Qu B D 1994 Phys. Rev. B 50 698) and experiments (Jiang B, Peng J L, Zhong W L and Bursill L A 2000 J. Appl. Phys. 87 3462) showed that the ferroelectricity of fine ferroelectric particles decrease with decreasing particle size. From these experiments the extrapolated critical size of PTO particles was found to be around 4.2-20 nm.

  13. Atomistic simulations of dislocation pileup: Grain boundaries interaction

    DOE PAGESBeta

    Wang, Jian

    2015-05-27

    Here, using molecular dynamics (MD) simulations, we studied the dislocation pileup–grain boundary (GB) interactions. Two Σ11 asymmetrical tilt grain boundaries in Al are studied to explore the influence of orientation relationship and interface structure on dislocation activities at grain boundaries. To mimic the reality of a dislocation pileup in a coarse-grained polycrystalline, we optimized the dislocation population in MD simulations and developed a predict-correct method to create a dislocation pileup in MD simulations. MD simulations explored several kinetic processes of dislocations–GB reactions: grain boundary sliding, grain boundary migration, slip transmission, dislocation reflection, reconstruction of grain boundary, and the correlation ofmore » these kinetic processes with the available slip systems across the GB and atomic structures of the GB.« less

  14. The effect of triple-junction drag on grain growth

    SciTech Connect

    Gottstein, G.; King, A.H.; Shvindlerman, L.S.

    2000-01-24

    Current theories of grain growth presume that grain boundary migration is the rate-limiting step, and either explicitly or implicitly assume that triple junctions can always move with sufficient speed to accommodate the changing positions of the grain boundaries. Following from some recent observations of triple-junction drag effects in tricrystals of zinc and in molecular dynamics models, an analytical theory is developed to explore the effects of triple-junction drag upon grain growth, for a two-dimensional solid. The theory is developed in the framework of the Von Neumann-Mullins formulation, and demonstrates that drag effects operating exclusively at the triple junctions result in a retardation of grain growth. The stability of six-sided grains in the isotropic, drag-free case of the Von Neumann-Mullins analysis is successively extended to grains of 6 {+-} N sides, where N increases with the strength of the triple-junction drag.

  15. Comments on 'Extinct radioactivities: Trapped residuals of presolar grains'

    NASA Technical Reports Server (NTRS)

    Trivedi, B. M. P.

    1977-01-01

    It has recently been suggested that extinct I-129 and Pu-244 were trapped in primitive-solar-nebula ('presolar') grains and decayed into radiogenic Xe-129 and fission Xe before the grains were incorporated into meteorite bodies. This idea is reconsidered in light of the thermal and metamorphic history of meteorites. The criteria that parent and daughter species should never separate and that minerals or grains containing the anomalous xenon should not be subjected to temperatures exceeding 500 C are applied to iron meteorites, achondrites, and chondrites to determine whether presolar grains could be the carriers of rare-gas anomalies to meteorites. The results strongly indicate that the xenon anomaly could not have originated in presolar grains. Other difficulties with the presolar-grain model are discussed, including insufficiently small grain sizes, large variations in Xe-129/I-127 ratios in various meteorites, and apparently unrealistic meteorite formation times and locations.

  16. Relict grains in chondrules: Evidence for chondrule recycling

    NASA Technical Reports Server (NTRS)

    Jones, R. H.

    1994-01-01

    The presence of relict grains in chondrules, which offers some insight into the degree to which chondrule material was recycled in the chondrule-forming region, is discussed in this report. Relics are grains that clearly did not crystallize in situ in the host chondrule. They represent coarse-grained precursor material that did not melt during chondrule formation, and provide the only tangible record of chondrule precursor grains. Relics are commonly identified by a large difference in size, textural differences, and/or significant compositional differences compared with normal grains in the host chondrule. Two important types of relics are: (1) 'dusty,' metal-bearing grains of olivine and pyroxene; and (2) forsterite (Mg-rich olivine) grains present in FeO-rich chondrules.

  17. Atomistic simulations of dislocation pileup: Grain boundaries interaction

    SciTech Connect

    Wang, Jian

    2015-05-27

    Here, using molecular dynamics (MD) simulations, we studied the dislocation pileup–grain boundary (GB) interactions. Two Σ11 asymmetrical tilt grain boundaries in Al are studied to explore the influence of orientation relationship and interface structure on dislocation activities at grain boundaries. To mimic the reality of a dislocation pileup in a coarse-grained polycrystalline, we optimized the dislocation population in MD simulations and developed a predict-correct method to create a dislocation pileup in MD simulations. MD simulations explored several kinetic processes of dislocations–GB reactions: grain boundary sliding, grain boundary migration, slip transmission, dislocation reflection, reconstruction of grain boundary, and the correlation of these kinetic processes with the available slip systems across the GB and atomic structures of the GB.

  18. Aeolian Grain Evolution on Mars: Implications for Regolith Origins

    NASA Astrophysics Data System (ADS)

    Sullivan, R. J.; Cabrol, N. A.; Golombek, M.; Herkenhoff, K. E.; Landis, G.; Mer Athena Science Team

    2010-12-01

    Early wind tunnel experiments and the Viking Lander experience led to concepts of grain evolution and regolith development on Mars. Wind tunnel experiments showed that 100-150 μm grains are easiest to entrain on Mars, but at 10 times higher wind speeds than on Earth. Even if trajectory speeds of martian saltating grains achieve smaller fractions of entraining wind speeds than on Earth, kinetic energies of these grains would be much higher, with greater potential for damage to the grains during return collisions with the particle bed. On this basis Sagan et al. [1977] JGR 82, 28, 4430 proposed that aeolian grain evolution on Mars followed a “kamikaze” pattern in which an initially coarse grain, entrained only relatively rarely by the strongest winds, would be abraded by high kinetic energy impacts and migrate through successively smaller size-frequencies at an ever-increasing rate (as entrainment became easier and thus more likely) until the grain was essentially turned to dust. On this basis it was proposed that sand-sized grains might be relatively short-lived and perhaps rare on Mars. MER observations motivate adjustments to these concepts, with implications for origins of martian regolith reworked by wind. Along both MER traverses, on opposite sides of the planet, regolith is volumetrically dominated by very fine sand mixed with unresolved finer grains. Sorting probably is poor, based on weakly cohesive remolding by rover wheel cleats. The size-frequency of this material, even if not precisely known, is consistent with grains that have evolved by attrition to sizes smaller than the most easily-moved 100-150 μm interval, to where entrainment becomes more difficult due to the increasing relative importance of inter-particle surface forces. At these smaller sizes also, kinetic energies have been reduced proportionally by the cube of the particle radius, so grain-to-grain attrition is less effective for further evolution to even smaller grain sizes

  19. Development of quick cooking multi-grain dalia utilizing sprouted grains.

    PubMed

    Mridula, D; Sharma, Monika; Gupta, R K

    2015-09-01

    Multi-grain dalia (MGD) formulations were prepared utilizing sprouted wheat and mixer of other three grains (barley, sorghum and pearl millet) in the ratio of 100:0 (MGD-A), 75:25 (MGD-B), 50:50 (MGD-C), 25:75 (MGD-D) and 0:100 (MGD-E), respectively. The mixer of barley, sorghum and pearl millet was prepared using 50, 25, 25 parts of these grains, respectively. The recovery of grits/ dalia (particle size 1.41 to 2 mm) from sprouted wheat and barley was 74.56 and 69.77 %, respectively while sorghum and pearl millet yield 47.94 and 49.39 % (particle size 0.954 to 1.41 mm), respectively. Sprouting brought a reduction of cooking time by about 50 % as compared to un-sprouted studied grains. Cooking time for different MGD formulations ranged from 3.91 to 4.42 min, which was slightly increased with increasing proportion of mixer of barley, sorghum and pearl millet (p > 0.05). Rehydration ratio of MGD samples varied from 3.12 to 3.45 with minimum in MGD-E sample. Though protein content was decreased with increasing proportion of mixer of three grains in MGD samples but in vitro protein digestibility (58.68 to 62.75 %) was similar (p > 0.05). The mean overall sensory acceptability scores for MGD samples ranged from 7.50 to 8.49 with ≥8.0 in samples having up to 75 % grits of mixer of three grains. In view of very good overall sensory acceptability, rich in crude fibre, calcium and iron content and low cooking time, 25:75 parts of sprouted wheat and mixer of studied three grains, respectively may be considered for preparation of acceptable quality quick cooking multi-grain dalia. PMID:26344997

  20. Metal precipitation at grain boundaries in silicon: Dependence on grain boundary character and dislocation decoration

    SciTech Connect

    Buonassisi, T.; Istratov, A. A.; Pickett, M. D.; Marcus, M. A.; Ciszek, T. F.; Weber, E. R.

    2006-07-24

    Synchrotron-based analytical microprobe techniques, electron backscatter diffraction, and defect etching are combined to determine the dependence of metal silicide precipitate formation on grain boundary character and microstructure in multicrystalline silicon (mc-Si). Metal silicide precipitate decoration is observed to increase with decreasing atomic coincidence within the grain boundary plane (increasing {sigma} values). A few low-{sigma} boundaries contain anomalously high metal precipitate concentrations, concomitant with heavy dislocation decoration. These results provide direct experimental evidence that the degree of interaction between metals and structural defects in mc-Si can vary as a function of microstructure, with implications for mc-Si device performance and processing.

  1. Microstructural changes in Beta-silicon nitride grains upon crystallizing the grain-boundary glass

    NASA Technical Reports Server (NTRS)

    Lee, William E.; Hilmas, Gregory E.; Lange, F. F. (Editor)

    1991-01-01

    Crystallizing the grain boundary glass of a liquid phase sintered Si3N4 ceramic for 2 h or less at 1500 C led to formation of gamma Y2Si2O7. After 5 h at 1500 C, the gamma Y2Si2O7 had transformed to beta Y2Si2O7 with a concurrent dramatic increase in dislocation density within beta Si3N4 grains. Reasons for the increased dislocation density is discussed. Annealing for 20 h at 1500 C reduced dislocation densities to the levels found in as-sintered materials.

  2. Grain size segregation in debris discs

    NASA Astrophysics Data System (ADS)

    Thebault, P.; Kral, Q.; Augereau, J.-C.

    2014-01-01

    Context. In most debris discs, dust grain dynamics is strongly affected by stellar radiation pressure. Because this mechanism is size-dependent, we expect dust grains to be spatially segregated according to their sizes. However, because of the complex interplay between radiation pressure, grain processing by collisions, and dynamical perturbations, this spatial segregation of the particle size distribution (PSD) has proven difficult to investigate and quantify with numerical models. Aims: We propose to thoroughly investigate this problem by using a new-generation code that can handle some of the complex coupling between dynamical and collisional effects. We intend to explore how PSDs behave in both unperturbed discs at rest and in discs pertubed by planetary objects. Methods: We used the DyCoSS code to investigate the coupled effect of collisions, radiation pressure, and dynamical perturbations in systems that have reached a steady-state. We considered two setups: a narrow ring perturbed by an exterior planet, and an extended disc into which a planet is embedded. For both setups we considered an additional unperturbed case without a planet. We also investigated the effect of possible spatial size segregation on disc images at different wavelengths. Results: We find that PSDs are always spatially segregated. The only case for which the PSD follows a standard dn ∝ s-3.5ds law is for an unperturbed narrow ring, but only within the parent-body ring itself. For all other configurations, the size distributions can strongly depart from such power laws and have steep spatial gradients. As an example, the geometrical cross-section of the disc is very rarely dominated by the smallest grains on bound orbits, as it is expected to be in standard PSDs in sq with q ≤ -3. Although the exact profiles and spatial variations of PSDs are a complex function of the set-up that is considered, we are still able to derive some reliable results that will be useful for image or SED

  3. GRAIN BOUNDARY STRENGTHENING PROPERTIES OF TUNGSTEN ALLOYS

    SciTech Connect

    Setyawan, Wahyu; Kurtz, Richard J.

    2012-10-10

    Density functional theory was employed to investigate grain boundary (GB) properties of W alloys. A range of substitutional solutes across the Periodic Table was investigated to understand the behavior of different electronic orbitals in changing the GB cleavage energy in the Σ27a[110]{525} GB. A number of transition metals were predicted to enhance the GB cohesion. This includes Ru, Re, Os, Ir, V, Cr, Mn, Fe, Co, Ti, Hf, Ta and Nb. While lanthanides, s and p elements were tended to cause GB embrittlement.

  4. Scattering by anisotropic grains in beryllium mirrors

    SciTech Connect

    Church, E.L. ); Takacs, P.Z. ); Stover, J.C. )

    1990-08-01

    Scattering from mirror surfaces arises from topographic and non-topographic sources. This paper considers the nontopographic scattering of beryllium mirrors modelled as a collection of randomly oriented bireflective grains. Simple scattering theory shows that this type of scatting scales as {lambda}{sup {minus}2}, rather than as {lambda}{sup {minus}4} for topographic scattering, which means that it is relatively more important at long radiation wavelengths. Estimates of the intensity based an available short-wavelength values of the anisotropic optical constants of beryllium indicate that this type of scattering could dominate the topographic scattering from smooth surfaces at CO{sub 2} wavelengths. 10 refs., 2 figs.

  5. Electronic and molecular structure of carbon grains

    NASA Technical Reports Server (NTRS)

    Almloef, Jan; Luethi, Hans-Peter

    1990-01-01

    Clusters of carbon atoms have been studied with large-scale ab initio calculations. Planar, single-sheet graphite fragments with 6 to 54 atoms were investigated, as well as the spherical C(sub 60) Buckminsterfullerene molecule. Polycyclic aromatic hydrocarbons (PAHs) have also been considered. Thermodynamic differences between diamond- and graphite-like grains have been studied in particular. Saturation of the peripheral bonds with hydrogen is found to provide a smooth and uniform convergence of the properties with increasing cluster size. For the graphite-like clusters the convergence to bulk values is much slower than for the three-dimensional complexes.

  6. Electronic phenomena near semiconductor grain boundaries

    NASA Astrophysics Data System (ADS)

    Pike, G. E.

    Various electronic phenomena which are generally associated with grain boundaries in semiconductors are reviewed. At equilibrium majority carriers are trapped at the boundaries, and a corresponding space charge layer of ionized dopant forms on both sides of the boundary. This creates a potential barrier to free carriers. An applied dc voltage causes the barrier to lower and change shape in an asymmetric way. At high voltages hot majority carriers can produce impact ionized minority carriers which further reduce the barrier height. Small ac voltages cause anomalous apparent capacitances which are either positive or negative.

  7. Chondrule synthesis using fine-grained precursors

    NASA Astrophysics Data System (ADS)

    Fox, George Ernest

    2002-11-01

    High temperature petrologic experiments have been used in order to reproduce the textures of chondrules, which are rounded to irregularly shaped ferromagnesion silicate objects. Such experiments shed light on the conditions that existed and mechanisms that operated in the early solar nebula, as natural chondrules are believed to have formed there due to some type of heating event. The exact nature of this heating event and the conditions that existed at the time of the formation of the solar nebula are not completely understood. Chondrules, which are believed to be composed of some of the oldest remnants of the solar system, nebular condensates, are the basic components of chondrites. Chondrites comprise ˜82% of all meteorites. Despite years of petrographic examination and experimental petrology, the thermal history of chondrules still remains uncertain. Natural chondrules exhibit a variety of different textures ranging from glassy, barred, porphyritic, microporphyritc to protoporphyritc. Petrologic experiments in a muffle tube furnace under controlled fugacity conditions using type IAB bulk composition analogs have been successful in reproducing each of these textures in the laboratory. Charges are prepared, heated, water quenched, mounted, polished and photographed using back-scattered electron imagery. Subsequent analysis provides numerical data, which can then be used to calculate the nominal grain size of the olivine crystals in each charge. Porphyritic chondrules are the most abundant in nature by far and any model for chondrule formation must be capable of producing porphyritic textures. To reproduce this texture in the laboratory, however, seems to require a very narrow range of maximum temperature and soak time parameters even when using a variety of different types of fine-grained and agglomerated olivine precursor material. Experiments undertaken in this study bring into question some of the basic assumptions of various classical models of chondrule

  8. Influence of anisotropic grain boundary properties on the evolution of grain boundary character distribution during grain growth—a 2D level set study

    NASA Astrophysics Data System (ADS)

    Hallberg, Håkan

    2014-12-01

    The present study elaborates on a 2D level set model of polycrystal microstructures that was recently established by adding the influence of anisotropic grain boundary energy and mobility on microstructure evolution. The new model is used to trace the evolution of grain boundary character distribution during grain growth. The employed level set formulation conveniently allows the grain boundary characteristics to be quantified in terms of coincidence site lattice (CSL) type per unit of grain boundary length, providing a measure of the distribution of such boundaries. In the model, both the mobility and energy of the grain boundaries are allowed to vary with misorientation. In addition, the influence of initial polycrystal texture is studied by comparing results obtained from a polycrystal with random initial texture against results from a polycrystal that initially has a cube texture. It is shown that the proposed level set formulation can readily incorporate anisotropic grain boundary properties and the simulation results further show that anisotropic grain boundary properties only have a minor influence on the evolution of CSL boundary distribution during grain growth. As anisotropic boundary properties are considered, the most prominent changes in the CSL distributions are an increase of general low-angle Σ1 boundaries as well as a more stable presence of Σ3 boundaries. The observations also hold for the case of an initially cube-textured polycrystal. The presence of this kind of texture has little influence over the evolution of the CSL distribution. Taking into consideration the anisotropy of grain boundary properties, grain growth alone does not seem to be sufficient to promote any significantly increased overall presence of CSL boundaries.

  9. Mechanical Spectroscopy of Grain Boundaries: Insights into Grain and Phase Boundary Sliding (Invited)

    NASA Astrophysics Data System (ADS)

    Sundberg, M.

    2010-12-01

    Grain boundary sliding has been identified as an important contributor to plastic deformation of polycrystalline rocks. Grain boundary sliding commonly acts in kinetic series with some other, usually rate-limiting, step such as grain boundary diffusion or dislocation propagation. Consequently, the mechanical properties of grain and phase boundaries are not typically measurable during steady-state creep tests. In contrast, measurements of the intrinsic shear attenuation (QG-1 ) of a polycrystalline rock as a function of frequency and temperature hold the potential to provide direct measurements of the grain boundary viscosity. Reciprocating torsion tests can be complemented by small-strain transient creep tests that monitor the short-time transient mechanical response of a polycrystalline solid to an instantaneous increase in stress. To develop and test a viscoelastic model that can describe both time- and frequency-domain mechanical behavior and thus allow extrapolation of experimental results to natural conditions, we have conducted an experimental study of low-frequency (10-2.25grained (d~5μm) aggregates of olivine and orthopyroxene ranging in composition from 6-75 vol % opx. The attenuation spectra reveal “high-temperature background” behavior at low to moderate frequencies. At higher frequencies (f>10-0.5 Hz) the attenuation spectra reveal the onset of an apparent Debye peak in the attenuation spectra, likely due to elastically-accommodated grain boundary sliding. A modified Andrade viscoelastic model that incorporates both the high-temperature background and the Debye

  10. Strength of Rocks Affected by Deformation Enhanced Grain Growth

    NASA Astrophysics Data System (ADS)

    Kellermann Slotemaker, A.; de Bresser, H.; Spiers, C.

    2005-12-01

    One way of looking into the possibility of long-term strength changes in the lithosphere is to study transient effects resulting from modifications of the microstructure of rocks. It is generally accepted that mechanical weakening may occur due to progressive grain size refinement resulting from dynamic recrystallization. A decrease in grain size may induce a switch from creep controlled by grain size insensitive dislocation mechanisms to creep governed by grain size sensitive (GSS) mechanisms involving diffusion and grain boundary sliding processes. This switch forms a well-known scenario to explain localization in the lithosphere. However, fine-grained rocks in localized deformation zones are prone to grain coarsening due to surface energy driven grain boundary migration (SED-GBM). This might harden the rock, affecting its role in localizing strain in the long term. The question has arisen if grain growth by SED-GBM in a rock deforming in the GSS creep field can be significantly affected by strain. The broad aim of this study is to shed more light onto this. We have experimentally investigated the microstructural and strength evolution of fine-grained (~0.6 μm) synthetic forsterite and Fe-bearing olivine aggregates that coarsen in grain size while deforming by GSS creep at elevated pressure (600 MPa) and temperature (850-1000 °C). The materials were prepared by `sol-gel' method and contained 0.3-0.5 wt% water and 5-10 vol% enstatite. We performed i) static heat treatment tests of various time durations involving hot isostatic pressing (HIP), and ii) heat treatment tests starting with HIP and continuing with deformation up to 45% axial strain at strain rates in the range 4x10-7 - 1x10-4 s-1. Microstructures were characterized by analyzing full grain size distributions and textures using SEM/EBSD. In addition to the experiments, we studied microstructural evolution in simple two-dimensional numerical models, combining deformation and SED-GBM by means of the

  11. [5-n-alkylresorcinols of whole grain cereals and whole grain cereal products as biomarkers of healthy food].

    PubMed

    Kulawinek, Mariola; Kozubek, Arkadiusz

    2007-01-01

    Epidemiological studies suggest that consumption of whole grain cereals and whole grain cereal products have many benefical health effects, including reducing risk of diabetes, obesity, coronary heart diseases, stroke and even some cancers. Precise knowledge protective compounds present in cereal grains can be achieved only when specific biomarkers (biological marker, indicator), that could provide estimation of grain cereals absorption and intake, are established and determined. 5-n-alkylresorcinols (main fraction of phenolic compounds in cereals), because of their specific occurrence only in bran fraction, obtained in refining of milling fractions process, could be a very good candidate to play the role of biomarker of whole grain intake. They are absorbed by animals and humans, present in human plasma and as metabolites in urine. Because composition of saturated homologues of 5-n-alkylresorcinols is different in rye and wheat grains, they could be used as an indicator of the intake of the specific type of cereals and whole grain cereal products.

  12. Equilibrium behavior of coarse-grained chaos

    NASA Astrophysics Data System (ADS)

    Egolf, David A.; Ballard, Christopher C.; Esty, C. Clark

    2015-03-01

    A wide variety of systems exhibiting spatiotemporal chaos have been shown to be extensive, in that their fractal dimensions grow linearly with volume. Ruelle argued that this extensivity is evidence that these systems can be viewed as a gas of weakly-interacting regions. We have tested this idea by performing large-scale computational studies of spatiotemporal chaos in the 1D complex Ginzburg-Landau equation, and we have found that aspects of the coarse-grained system are well-described not only as a gas, but as an equilibrium gas -- in particular, a Tonks gas (and variants) in the grand canonical ensemble. Furthermore, for small system sizes, the average number of particles in the corresponding Tonks gas exhibits oscillatory, decaying deviations from extensivity in agreement with deviations in the fractal dimension found by Fishman and Egolf. This result not only supports Ruelle's picture but also suggests that the coarse-grained behavior of this far-from-equilibrium system might be understood using equilibrium statistical mechanics.

  13. Coarse-Grain Modeling of Energetic Materials

    NASA Astrophysics Data System (ADS)

    Brennan, John

    2015-06-01

    Mechanical and thermal loading of energetic materials can incite responses over a wide range of spatial and temporal scales due to inherent nano- and microscale features. Many energy transfer processes within these materials are atomistically governed, yet the material response is manifested at the micro- and mesoscale. The existing state-of-the-art computational methods include continuum level approaches that rely on idealized field-based formulations that are empirically based. Our goal is to bridge the spatial and temporal modeling regimes while ensuring multiscale consistency. However, significant technical challenges exist, including that the multiscale methods linking the atomistic and microscales for molecular crystals are immature or nonexistent. To begin addressing these challenges, we have implemented a bottom-up approach for deriving microscale coarse-grain models directly from quantum mechanics-derived atomistic models. In this talk, a suite of computational tools is described for particle-based microscale simulations of the nonequilibrium response of energetic solids. Our approach builds upon recent advances both in generating coarse-grain models under high strains and in developing a variant of dissipative particle dynamics that includes chemical reactions.

  14. A coarse-grained spectral signature generator

    NASA Astrophysics Data System (ADS)

    Lam, K. P.; Austin, J. C.; Day, C. R.

    2007-01-01

    This paper investigates the method for object fingerprinting in the context of element specific x-ray imaging. In particular, the use of spectral descriptors that are illumination invariant and viewpoint independent for pattern identification was examined in some detail. To improve generating the relevant "signature", the spectral descriptor constructed is enhanced with a differentiator which has built-in noise filtration capability and good localisation properties, thus facilitating the extraction of element specific features at a coarse-grained level. In addition to the demonstrable efficacy in identifying significant image intensity transitions that are associated with the underlying physical process of interest, the method has the distinct advantage of being conceptually simple and computationally efficient. These latter properties allow the descriptor to be further utilised by an intelligent system capable of performing a fine-grained analysis of the extracted pattern signatures. The performance of the spectral descriptor has been studied in terms of the quality of the signature vectors that it generated, quantitatively based on the established framework of Spectral Information Measure (SIM). Early results suggested that such a multiscale approach of image sequence analysis offers a considerable potential for real-time applications.

  15. Mesoscopic superconductivity in ultrasmall metallic grains

    SciTech Connect

    Alhassid, Y.; Nesterov, K. N.

    2014-10-15

    A nano-scale metallic grain (nanoparticle) with irregular boundaries in which the single-particle dynamics are chaotic is a zero-dimensional system described by the so-called universal Hamiltonian in the limit of a large number of electrons. The interaction part of this Hamiltonian includes a superconducting pairing term and a ferromagnetic exchange term. Spin-orbit scattering breaks spin symmetry and suppresses the exchange interaction term. Of particular interest is the fluctuation-dominated regime, typical of the smallest grains in the experiments, in which the bulk pairing gap is comparable to or smaller than the single-particle mean-level spacing, and the Bardeen-Cooper-Schrieffer (BCS) mean-field theory of superconductivity is no longer valid. Here we study the crossover between the BCS and fluctuation-dominated regimes in two limits. In the absence of spin-orbit scattering, the pairing and exchange interaction terms compete with each other. We describe the signatures of this competition in thermodynamic observables, the heat capacity and spin susceptibility. In the presence of strong spin-orbit scattering, the exchange interaction term can be ignored. We discuss how the magnetic-field response of discrete energy levels in such a nanoparticle is affected by pairing correlations. We identify signatures of pairing correlations in this response, which are detectable even in the fluctuation-dominated regime.

  16. Deuterium enrichment of the interstellar grain mantle

    NASA Astrophysics Data System (ADS)

    Das, Ankan; Sahu, Dipen; Majumdar, Liton; Chakrabarti, Sandip K.

    2016-01-01

    We carry out Monte Carlo simulation to study deuterium enrichments of interstellar grain mantles under various physical conditions. Based on the physical properties, various types of clouds are considered. We find that in diffuse cloud regions, very strong radiation fields persists and hardly a few layers of surface species are formed. In translucent cloud regions with a moderate radiation field, significant number of layers would be produced and surface coverage is mainly dominated by photo-dissociation products such as, C, CH3, CH2D, OH and OD. In the intermediate dense cloud regions (having number density of total hydrogen nuclei in all forms ˜2 × 104 cm-3), water and methanol along with their deuterated derivatives are efficiently formed. For much higher density regions (˜106 cm-3), water and methanol productions are suppressed but surface coverages of CO, CO2, O2 and O3 are dramatically increased. We find a very high degree of fractionation of water and methanol. Observational results support a high fractionation of methanol but surprisingly water fractionation is found to be low. This is in contradiction with our model results indicating alternative routes for de-fractionation of water. Effects of various types of energy barriers are also studied. Moreover, we allow grain mantles to interact with various charged particles (such as H+, Fe+, S+ and C+) to study the stopping power and projected range of these charged particles on various target ices.

  17. Solid-State Spectroscopy: Silicates & Carbonaceous Grains

    NASA Astrophysics Data System (ADS)

    Jager, C.; Mutschke, H.; Henning, T.; Huisken, F.

    2011-05-01

    Cosmic dust grains prove their existence by interstellar extinction curves, IR spectra, and elemental depletion patterns. They influence the heating rate of the gas via the photo-electric effect and the formation rate of molecular hydrogen as well as other more complex organic molecules being formed on their surfaces. Dust grains, well mixed with gas, absorb and scatter stellar light and reemit the absorbed energy at infrared and millimeter wavelengths. For the interpretation of these data, the spectral properties of cosmic dust in a broad wavelength range are required. These spectral data can be obtained by measurements of dust analogs prepared in the laboratory. The application of formation techniques that come close to astrophysical formation conditions such as gas-phase condensations and the study of dust processing by energy-rich irradiation are necessary to produce astrophysically realistic cosmic dust analogs. A detailed characterization of the physical and chemical structure of the laboratory produced materials has to precede the measurements of the spectral properties. The qualitative improvement of the spectral data measured in the laboratory including spectroscopic measurements at low temperatures and absorption spectroscopy of aerosol particles helps to improve the interpretation of dust observations in various astrophysical environments and to gain more information on astrophysical processes such as star and planet formation.

  18. 77 FR 65855 - Cancellation of Indianapolis Grain Inspection & Weighing Service, Inc. Designation; Selection of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-31

    ... Grain Inspection, Packers and Stockyards Administration Cancellation of Indianapolis Grain Inspection... Indianapolis, IN Area AGENCY: Grain Inspection, Packers and Stockyards Administration, USDA. ACTION: Notice. SUMMARY: Indianapolis Grain Inspection & Weighing Service, Inc. (Indianapolis) is designated to...

  19. 76 FR 317 - Cancellation of Lewiston Grain Inspection Service, Inc. Designation; Opportunity for Designation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-04

    ... Grain Inspection, Packers and Stockyards Administration Cancellation of Lewiston Grain Inspection Service, Inc. Designation; Opportunity for Designation in the Lewiston, ID Area AGENCY: Grain Inspection, Packers and Stockyards Administration, USDA. ACTION: Notice. SUMMARY: Lewiston Grain Inspection...

  20. Transmission Electron Microscopy of Itokawa Regolith Grains

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Berger, E. L.

    2013-01-01

    Introduction: In a remarkable engineering achievement, the JAXA space agency successfully recovered the Hayabusa space-craft in June 2010, following a non-optimal encounter and sur-face sampling mission to asteroid 25143 Itokawa. These are the first direct samples ever obtained and returned from the surface of an asteroid. The Hayabusa samples thus present a special op-portunity to directly investigate the evolution of asteroidal sur-faces, from the development of the regolith to the study of the effects of space weathering. Here we report on our preliminary TEM measurements on two Itokawa samples. Methods: We were allocated particles RA-QD02-0125 and RA-QD02-0211. Both particles were embedded in low viscosity epoxy and thin sections were prepared using ultramicrotomy. High resolution images and electron diffraction data were ob-tained using a JEOL 2500SE 200 kV field-emission scanning-transmission electron microscope. Quantitative maps and anal-yses were obtained using a Thermo thin-window energy-dispersive x-ray (EDX) spectrometer. Results: Both particles are olivine-rich (Fo70) with µm-sized inclusions of FeS and have microstructurally complex rims. Par-ticle RA-QD02-0125 is rounded and has numerous sub-µm grains attached to its surface including FeS, albite, olivine, and rare melt droplets. Solar flare tracks have not been observed, but the particle is surrounded by a continuous 50 nm thick, stuctur-ally disordered rim that is compositionally similar to the core of the grain. One of the surface adhering grains is pyrrhotite show-ing a S-depleted rim (8-10 nm thick) with nanophase Fe metal grains (<5 nm) decorating the outermost surface. The pyrrhotite displays a complex superstructure in its core that is absent in the S-depleted rim. Particle RA-QD02-0211 contains solar flare particle tracks (2x109 cm-2) and shows a structurally disordered rim 100 nm thick. The track density corresponds to a surface exposure of 103-104 years based on the track production rate

  1. Awns reduce grain number to increase grain size and harvestable yield in irrigated and rainfed spring wheat

    PubMed Central

    Rebetzke, G. J.; Bonnett, D. G.; Reynolds, M. P.

    2016-01-01

    Genotypic variation in ear morphology is linked to differences in photosynthetic potential to influence grain yield in winter cereals. Awns contribute to photosynthesis, particularly under water-limited conditions when canopy assimilation is restricted. We assessed performance of up to 45 backcross-derived, awned–awnletted NILs representing four diverse genetic backgrounds in 25 irrigated or rainfed, and droughted environments in Australia and Mexico. Mean environment grain yields were wide-ranging (1.38–7.93 t ha−1) with vegetative and maturity biomass, plant height, anthesis date, spike number, and harvest index all similar (P >0.05) for awned and awnletted NILs. Overall, grain yields of awned–awnletted sister-NILs were equivalent, irrespective of yield potential and genetic background. Awnletted wheats produced significantly more grains per unit area (+4%) and per spike (+5%) reflecting more fertile spikelets and grains in tertiary florets. Increases in grain number were compensated for by significant reductions in grain size (–5%) and increased frequency (+0.8%) of small, shrivelled grains (‘screenings’) to reduce seed-lot quality of awnletted NILs. Post-anthesis canopies of awnletted NILs were marginally warmer over all environments (+0.27 °C) but were not different and were sometimes cooler than awned NILs at cooler air temperatures. Awns develop early and represented up to 40% of total spikelet biomass prior to ear emergence. We hypothesize that the allocation of assimilate to large and rapidly developing awns decreases spikelet number and floret fertility to reduce grain number, particularly in distal florets. Individual grain size is increased to reduce screenings and to increase test weight and milling quality, particularly in droughted environments. Despite the average reduction in grain size, awnless lines could be identified that combined higher grain yield with larger grain size, increased grain protein concentration, and reduced

  2. Activities of key enzymes in sucrose-to-starch conversion in wheat grains subjected to water deficit during grain filling.

    PubMed

    Yang, Jianchang; Zhang, Jianhua; Wang, Zhiqing; Xu, Guowei; Zhu, Qingsen

    2004-07-01

    This study tested the hypothesis that a controlled water deficit during grain filling of wheat (Triticum aestivum) could accelerate grain-filling rate through regulating the key enzymes involved in Suc-to-starch pathway in the grains. Two high lodging-resistant wheat cultivars were field grown. Well-watered and water-deficit (WD) treatments were imposed from 9 DPA until maturity. The WD promoted the reallocation of prefixed 14C from the stems to grains, shortened the grain-filling period, and increased grain-filling rate or starch accumulation rate (SAR) in the grains. Activities of Suc synthase (SuSase), soluble starch synthase (SSS), and starch branching enzyme (SBE) in the grains were substantially enhanced by WD and positively correlated with the SAR. ADP Glc pyrophosphorylase activity was also enhanced in WD grains initially and correlated with SAR with a smaller coefficient. Activities of granule-bound starch synthase and soluble and insoluble acid invertase in the grains were less affected by WD. Abscisic acid (ABA) content in the grains was remarkably enhanced by WD and very significantly correlated with activities of SuSase, SSS, and SBE. Application of ABA on well-watered plants showed similar results as those by WD. Spraying with fluridone, an ABA synthesis inhibitor, had the opposite effect. The results suggest that increased grain-filling rate is mainly attributed to the enhanced sink activity by regulating key enzymes involved in Suc-to-starch conversion, especially SuSase, SSS, and SBE, in wheat grains when subjected to a mild water deficit during grain filling, and ABA plays a vital role in the regulation of this process.

  3. Utilization of wet distillers grains in high-energy beef cattle diets based on processed grain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Distiller's grains (DG) are used extensively by beef cattle feeding operations in the United States, including the Southern Great Plains. Our regional research consortium has been conducting research focused on utilization of wet DG in feedlot diets based on steam-flaked corn (SFC). Effects of DG on...

  4. Identifying whole grain foods: a comparison of different approaches for selecting more healthful whole grain products

    PubMed Central

    Mozaffarian, Rebecca S; Lee, Rebekka M; Kennedy, Mary A; Ludwig, David S; Mozaffarian, Dariush; Gortmaker, Steven L

    2015-01-01

    Objective Eating whole grains (WG) is recommended for health, but multiple conflicting definitions exist for identifying whole grain (WG) products, limiting the ability of consumers and organizations to select such products. We investigated how five recommended WG criteria relate to healthfulness and price of grain products. Design We categorized grain products by different WG criteria including: the industry-sponsored Whole Grain stamp (WG-Stamp); WG as the first ingredient (WG-first); WG as the first ingredient without added sugars (WG-first-no-added-sugars); the word ‘whole’ before any grain in the ingredients (‘whole’-anywhere); and a content of total carbohydrate to fibre of ≤10:1 (10:1-ratio). We investigated associations of each criterion with health-related characteristics including fibre, sugars, sodium, energy, trans-fats and price. Setting Two major grocery store chains. Subjects Five hundred and forty-five grain products. Results Each WG criterion identified products with higher fibre than products considered non-WG; the 10:1-ratio exhibited the largest differences (+3.15 g/serving, P<0.0001). Products achieving the 10:1-ratio also contained lower sugar (−1.28 g/serving, P=0.01), sodium (−15.4 mg/serving, P=0.04) and likelihood of trans-fats (OR=0.14, P<0.0001), without energy differences. WG-first-no-added-sugars performed similarly, but identified many fewer products as WG and also not a lower likelihood of containing trans-fats. The WG-Stamp, WG-first and ‘whole’-anywhere criteria identified products with a lower likelihood of trans-fats, but also significantly more sugars and energy (P<0.05 each). Products meeting the WG-Stamp or 10:1-ratio criterion were more expensive than products that did not (+$US 0.04/serving, P=0.009 and +$US 0.05/serving, P=0.003, respectively). Conclusions Among proposed WG criteria, the 10:1-ratio identified the most healthful WG products. Other criteria performed less well, including the industry

  5. Reducing arsenic accumulation in rice grain through iron oxide amendment.

    PubMed

    Farrow, Eric M; Wang, Jianmin; Burken, Joel G; Shi, Honglan; Yan, Wengui; Yang, John; Hua, Bin; Deng, Baolin

    2015-08-01

    Effects of soil-arsenic (As), phosphorus and iron oxide on As accumulation in rice grain were investigated. Cultivars that have significantly different sensitivity to As, straighthead-resistant Zhe 733 and straighthead-susceptible Cocodrie, were used to represent different cultivar varieties. The grain accumulation of other elements of concern, selenium (Se), molybdenum (Mo), and cadmium (Cd) was also monitored. Results demonstrated that high soil-As not only resulted in high grain-As, but could also result in high grain-Se, and Zhe 733 had significantly less grain-As than Cocodrie did. However, soil-As did not impact grain-Mo and Cd. Among all elements monitored, iron oxide amendment significantly reduced grain-As for both cultivars, while the phosphate application only reduced grain-Se for Zhe 733. Results also indicated that cultivar type significantly impacted grain accumulation of all monitored trace elements. Therefore, applying iron oxide to As-contaminated land, in addition to choosing appropriate rice cultivar, can effectively reduce the grain accumulation of As. PMID:25910688

  6. Trace element depth profiles in presolar silicon carbide grains

    NASA Astrophysics Data System (ADS)

    King, Ashley J.; Henkel, Torsten; Rost, Detlef; Lyon, Ian C.

    2012-10-01

    We have analyzed eleven presolar SiC grains from the Murchison meteorite using time-of-flight secondary ion mass spectrometry. The Si isotopic compositions of the grains indicate that they are probably of an AGB star origin. The average abundances of Mg, Fe, Ca, Al, Ti, and V are strongly influenced by their condensation behavior into SiC in circumstellar environments. Depth profiles of Li, B, Mg, Al, K, Ca, Ti, V, Cr, and Fe in the SiC grains show that trace elements are not always homogenously distributed. In approximately half of the SiC grains studied here, the trace element distributions can be explained by condensation processes around the grains' parent stars. These grains appear to have experienced only minimal processing before their arrival in the presolar molecular cloud, possibly due to short residence times in the interstellar medium. The remaining SiC grains contained elevated abundances of several elements within their outer 200 nm, which is attributed to the implantation of energetic ions accelerated by shockwaves in the interstellar medium. These grains may have spent a longer period of time in this region, hence increasing the probability of them passing through a shockfront. Distinct groups of presolar SiC grains whose residence times in the interstellar medium differ are consistent with previous findings based on noble gas studies, although some grains may also have been shielded from secondary alteration by protective outer mantles.

  7. Marketing whole grain breads in Canada via food labels.

    PubMed

    Sumanac, Dunja; Mendelson, Rena; Tarasuk, Valerie

    2013-03-01

    A recommendation for increased whole grain consumption was released in Canada in 2007 to promote adequate intakes of fibre and magnesium. Since then, a proliferation of 'whole grain' claims on food packaging has been observed, but whole grain labelling is voluntary and unregulated in Canada. Through a detailed survey of bread sold in three supermarkets, this study examined how the presence of front-of-package reference to whole grain relates to (i) the presence and nature of whole grain ingredients, (ii) nutrient content, and (iii) price of the product. Twenty-one percent of breads bore a reference to whole grain on the front-of-package and the front-of-package reference to whole grain was a better predictor of fibre content than any information that could be gleaned from the ingredient list. On average, breads with a whole grain reference were higher in fibre and magnesium and lower in sodium. Mean price did not differ by presence of a whole grain reference, but breads with whole grain labelling were less likely to be low in price. Voluntary nutrition labelling may be targeting a discrete market of health-conscious consumers who are willing to pay premium prices for more healthful options. PMID:23178749

  8. Grain Accumulation of Selenium Species in Rice (Oryza sativa L.)

    SciTech Connect

    Carey, Anne-Marie; Scheckel, Kirk G.; Lombi, Enzo; Newville, Matt; Choi, Yongseong; Norton, Gareth J.; Price, Adam H.; Meharg, Andrew A.

    2012-09-05

    Efficient Se biofortification programs require a thorough understanding of the accumulation and distribution of Se species within the rice grain. Therefore, the translocation of Se species to the filling grain and their spatial unloading were investigated. Se species were supplied via cut flag leaves of intact plants and excised panicle stems subjected to a {+-} stem-girdling treatment during grain fill. Total Se concentrations in the flag leaves and grain were quantified by inductively coupled plasma mass spectrometry. Spatial accumulation was investigated using synchrotron X-ray fluorescence microtomography. Selenomethionine (SeMet) and selenomethylcysteine (SeMeSeCys) were transported to the grain more efficiently than selenite and selenate. SeMet and SeMeSeCys were translocated exclusively via the phloem, while inorganic Se was transported via both the phloem and xylem. For SeMet- and SeMeSeCys-fed grain, Se dispersed throughout the external grain layers and into the endosperm and, for SeMeSeCys, into the embryo. Selenite was retained at the point of grain entry. These results demonstrate that the organic Se species SeMet and SeMeSeCys are rapidly loaded into the phloem and transported to the grain far more efficiently than inorganic species. Organic Se species are distributed more readily, and extensively, throughout the grain than selenite.

  9. Quantifying grain boundary damage tolerance with atomistic simulations

    NASA Astrophysics Data System (ADS)

    Foley, Daniel; Tucker, Garritt J.

    2016-10-01

    Grain boundaries play a pivotal role in defect evolution and accommodation within materials. Irradiated metals have been observed to form defect denuded zones in the vicinity of grain boundaries. This is especially apparent in nanocrystalline metals, which have an increased grain boundary concentration, as compared to their polycrystalline counterparts. Importantly, the effect of individual grain boundaries on microstructural damage tolerance is related to the character or structural state of the grain boundary. In this work, the damage accommodation behavior of a variety of copper grain boundaries is studied using atomistic simulations. Damage accumulation behavior is found to reach a saturation point where both the free volume and energy of a grain boundary fluctuate within an elliptical manifold, which varies in size for different boundary characters. Analysis of the grain boundaries shows that extrinsic damage accommodation occurs due to localized atomic shuffling accompanied by free volume rearrangement within the boundary. Continuous damage accumulation leads to altered atomic structural states that oscillate around a mean non-equilibrium state, that is energetically metastable. Our results suggest that variation of grain boundary behavior, both from equilibrium and under saturation, is directly related to grain boundary equilibrium energy and some boundaries have a greater propensity to continually accommodate damage, as compared to others.

  10. Quartz grain assessment for reconstructing the coastal palaeoenvironment

    NASA Astrophysics Data System (ADS)

    Vieira Machado, Giseli Modolo; Albino, Jacqueline; Leal, Arthur Pereira; Bastos, Alex Cardoso

    2016-10-01

    This study proposes a combination of sedimentological techniques as a tool to understand depositional palaeoenvironments. Grain size, mineralogy, compositional data, stratigraphic framework, degree of rounding, optical appearance and microtextures of quartz grains were analyzed; sub-surface sediments were collected from 4 boreholes spaced across coastal settings, from the beach towards the continent, from locations on the south-central coast of the state of Espírito Santo, southeast Brazil. Five palaeoenvironments were identified: fluvial (characterized by gravelly sand facies, composed predominantly of sub-angular and sub-rounded dirty quartz grains with microtexures caused by sudden impact and grain surfaces modified by chemical action, as well as other non-quartz terrigenous minerals); continental deposit with marine influence, such as an estuary (characterized by muddy sand facies, composed of immature grains with natural glow and non-abraded grains with a "fresh" clean surface, little to no chemical change, a few bioclastic fragments, carbonate nodules and grains embedded with carbonate); modern estuary (characterized by sandy mud facies, composed of mixed mature and immature quartz grains, chemically frosted, bioclastic fragments, carbonate nodules, and high organic matter content); bay (characterized by sandy mud and mud facies, composed predominantly of mature grains, highly chemically frosted, with microtextures clearly associated with post-depositional alteration, many bioclastic fragments, and organic matter); and beach (characterized by gravelly sand facies, composed predominantly of sub-rounded dirty grains, followed by shiny grains, with smooth edges, signs of former impact, little chemical dissolution on the quartz grain, and bioclastic fragments). The association between the degree of rounding, optical aspect and microtextures of quartz grains was essential to estimate the extent and strength of seawater intrusion in filling of the sedimentation

  11. PRAM C:a new programming environment for fine-grain and coarse-grain parallelism.

    SciTech Connect

    Brown, Jonathan Leighton; Wen, Zhaofang.

    2004-11-01

    In the search for ''good'' parallel programming environments for Sandia's current and future parallel architectures, they revisit a long-standing open question. Can the PRAM parallel algorithms designed by theoretical computer scientists over the last two decades be implemented efficiently? This open question has co-existed with ongoing efforts in the HPC community to develop practical parallel programming models that can simultaneously provide ease of use, expressiveness, performance, and scalability. Unfortunately, no single model has met all these competing requirements. Here they propose a parallel programming environment, PRAM C, to bridge the gap between theory and practice. This is an attempt to provide an affirmative answer to the PRAM question, and to satisfy these competing practical requirements. This environment consists of a new thin runtime layer and an ANSI C extension. The C extension has two control constructs and one additional data type concept, ''shared''. This C extension should enable easy translation from PRAM algorithms to real parallel programs, much like the translation from sequential algorithms to C programs. The thin runtime layer bundles fine-grained communication requests into coarse-grained communication to be served by message-passing. Although the PRAM represents SIMD-style fine-grained parallelism, a stand-alone PRAM C environment can support both fine-grained and coarse-grained parallel programming in either a MIMD or SPMD style, interoperate with existing MPI libraries, and use existing hardware. The PRAM C model can also be integrated easily with existing models. Unlike related efforts proposing innovative hardware with the goal to realize the PRAM, ours can be a pure software solution with the purpose to provide a practical programming environment for existing parallel machines; it also has the potential to perform well on future parallel architectures.

  12. Chemically anomalous, pre-accretionally irradiated grains in interplanetary dust -- interstellar grains?. [Abstract only

    NASA Technical Reports Server (NTRS)

    Bradley, J. P.

    1994-01-01

    Ultrafine-grained matrix is a unique and fundamental building block of chondritic porous (CP) interplanetary dust particles. Most IDPs so far determined to be of cometary origin belong to the CP class. The matrix in CP IDPs is not homogeneous but rather a loose mixture of discrete single crystals (e.g., olivine, pyroxene, Fe sulfides) and polyphase grains. The petrographic diversity observed among the polyphase grains suggest that they were formed under variable physiochemical conditions. One particular class of polyphase grains are a dominant component in cometary IDPs. Although their occurrence is well documented, the terminology used to describe them is confused. They have been called many names. Here they are simply called GEMS (Glass with Embedded Metal and Sulfides). The bulk compositions of GEMS are within a factor of 3 chondritic (solar) for all major elements except C. Quantitative thin-film X-ray (EDS) analyses have shown that GEMS are systematically depleted in Mg and Si, enriched in S, Fe, and Ni, and stoichiometrically enriched in O. Electron energy-loss spectroscopy (EELS) suggests that the excess O is present as hydroxyl (-OH) groups. These same chemical 'anomalies' were observed in solar-wind-irradiated amorphous rims on the surfaces of IDPs, suggesting that the compositions of GEMS reflect prior exposure to ionizing radiation. In order to test this hypothesis, a sample of Allende (CV3) matrix was exposed to proton flux. Radiation-damaged amorphous rims on olivine and pyroxene crystals in the Allende sample were found to be depleted in Mg and Ca, enriched in S, Fe, and Ni, and stoichiometrically enriched in O. Thus, the compositions of GEMS are indeed consistent with exposure to ionizing radiation. This study suggests that chemical as well as isotopic anomalies may be used to identify presolar interstellar grains in primitive meteoritic materials.

  13. Influence of mineral fraction on the rheological properties of forsterite + enstatite during grain-size-sensitive creep: 1. Grain size and grain growth laws

    NASA Astrophysics Data System (ADS)

    Tasaka, Miki; Hiraga, Takehiko

    2013-08-01

    conducted grain growth and creep experiments on forsterite (Fo) plus enstatite (En) aggregates at 1 atmosphere pressure and temperatures of 1260 - 1360°C, with variable volumetric fractions of the two minerals, forsterite and enstatite (Fo1.00 to Fo0.03 En0.97). The grain size ratios of forsterite and enstatite in annealed (reference) and deformed samples follow the Zener relationship of dI/dII = β/fIIz, where d is the grain size, and the subscripts I and II indicate the primary and secondary phases, respectively. When fEn < 0.5, I is forsterite, II is enstatite, then β = 0.67, and z = 0.52; for samples where fEn > 0.5, I is enstatite, II is forsterite, then β = 0.73, and z = 0.53. Grain growth in reference samples conforms to the relationship ds4 - d04 = kt, where ds is the grain size under static conditions, d0 is the initial grain size, k is the grain growth coefficient, and t is time. The observed growth coefficient for the primary phase (kI) becomes smaller with increasing fII, which is consistent with the theoretical prediction. Overall, our results are consistent with previously proposed grain growth models for static conditions that use mineral physical parameters such as diffusivity (DiGB) and interfacial energy (γ). We discuss grain size variations in the mantle, with compositions ranging from dunite to pyroxenite, and we go on to present a method that predicts the grain sizes of different mantle lithologies, provided that the diffusivity and interfacial energy of the constituent minerals are known.

  14. Grain formation around carbon stars. 1: Stationary outflow models

    NASA Technical Reports Server (NTRS)

    Egan, Michael P.; Leung, Chun Ming

    1995-01-01

    Asymptotic giant branch (AGB) stars are known to be sites of dust formation and undergo significant mass loss. The outflow is believed to be driven by radiation pressure on grains and momentum coupling between the grains and gas. While the physics of shell dynamics and grain formation are closely coupled, most previous models of circumstellar shells have treated the problem separately. Studies of shell dynamics typically assume the existence of grains needed to drive the outflow, while most grain formation models assume a constant veolcity wind in which grains form. Furthermore, models of grain formation have relied primarily on classical nucleation theory instead of using a more realistic approach based on chemical kinetics. To model grain formation in carbon-rich AGB stars, we have coupled the kinetic equations governing small cluster growth to moment equations which determine the growth of large particles. Phenomenological models assuming stationary outflow are presented to demonstrate the differences between the classical nucleation approach and the kinetic equation method. It is found that classical nucleation theory predicts nucleation at a lower supersaturation ratio than is predicted by the kinetic equations, resulting in significant differences in grain properties. Coagulation of clusters larger than monomers is unimportant for grain formation in high mass-loss models but becomes more important to grain growth in low mass-loss situations. The properties of the dust grains are altered considerably if differential drift velocities are ignored in modeling grain formation. The effect of stellar temperature, stellar luminosity, and different outflow velocities are investigated. The models indicate that changing the stellar temperature while keeping the stellar luminosity constant has little effect on the physical parameters of the dust shell formed. Increasing the stellar luminosity while keeping the stellar temperature constant results in large differences in

  15. Vortices of self-gravitating grains in dusty plasmas

    SciTech Connect

    Nebbat, E.; Annou, R.

    2012-09-15

    Vortices are an attractive expression of the non-linear dynamics of fluids along with plasmas. In complex plasmas, Nebbat and Annou [Phys. Plasmas 17, 093702 (2010)] proposed a time dependent non-linear model that considers vortices as a consequence of an instability. The model is augmented hereafter by incorporating the gravitational grain-grain attraction, particle drift due to self-gravity field, self-consistent inter-particle distance, the permeability of grains along with the grain charge excess due to the non-linear dependence of the grain capacitance on its size. Effects of the latter parameters as well as the effect of grain mass to charge ratio on the characteristics of the vortex such as density are investigated.

  16. Atomically ordered solute segregation behaviour in an oxide grain boundary

    NASA Astrophysics Data System (ADS)

    Feng, Bin; Yokoi, Tatsuya; Kumamoto, Akihito; Yoshiya, Masato; Ikuhara, Yuichi; Shibata, Naoya

    2016-03-01

    Grain boundary segregation is a critical issue in materials science because it determines the properties of individual grain boundaries and thus governs the macroscopic properties of materials. Recent progress in electron microscopy has greatly improved our understanding of grain boundary segregation phenomena down to atomistic dimensions, but solute segregation is still extremely challenging to experimentally identify at the atomic scale. Here, we report direct observations of atomic-scale yttrium solute segregation behaviours in an yttria-stabilized-zirconia grain boundary using atomic-resolution energy-dispersive X-ray spectroscopy analysis. We found that yttrium solute atoms preferentially segregate to specific atomic sites at the core of the grain boundary, forming a unique chemically-ordered structure across the grain boundary.

  17. Grain size distribution of the matrix in the Allende chondrite

    NASA Astrophysics Data System (ADS)

    Toriumi, M.

    1989-03-01

    Results are presented from analytical TEM, high-resolution TEM, and SEM studies of the Allende chondrite, showing that the matrix consists of very fine-grained Fe-rich olivine, Ca-poor and Fe-rich clinopyroxene, Fe-rich spinel, and Ni-bearing troilite. Slightly sintered and non-sintered very fine-grained aggregates are observed. The results suggest that the coarse-grained olivine aggregates experienced a heating event, whereas the ultrafine-grained aggregates did not. The size and frequency distributions of matrix grains are measured. The frequency distribution displays a long-term tail with power law and a log-normal pattern with a peak at 5 nm in the range from 1 to 10 nm. This suggests that the fine-grained matrix was probably formed at conditions far from equilibrium in the protosolar cloud.

  18. Overview on superplasticity research on small-grained materials

    SciTech Connect

    Sherby, O.D.; Nieh, T.G.; Wadsworth, J.

    1994-07-01

    Superplasticity is generally associated with fine grains, grain boundary sliding, and high tensile ductility at elevated temperature. This paper reviews some of the recent important findings in fine-grained superplasticity, including the areas of superplastic ceramics and bf-high-strain-rate superplasticity (HSRS). Deformation mechanism maps are shown to be powerful tools for predicting the conditions where HSRS can be expected. Ultrafine grained materials, processed economically, remain an important objective in achieving HSRS. Threshold stresses, observed in fine-grained superplastic materials, are shown to be functions of temperature and grain size but their origin, however, remains obscure. Quasi-superplastic materials, with a strain-rate-sensitivity exponent of m = 0.33, are shown to have high elongations, and have considerable promise for netshape isothermal forming of sheet and bulk components.

  19. Computer simulation of grain growth kinetics with solute drag

    SciTech Connect

    Fan, D.; Chen, S.P.; Chen, L.

    1999-03-01

    The effects of solute drag on the grain growth kinetics were studied in two-dimensional (2D) computer simulations by using a diffuse-interface field model. It is shown that, in the low velocity/low driving force regime, the velocity of a grain boundary motion departs from a linear relation with driving force (curvature) with solute drag. The nonlinear relation of migration velocity and driving force comes from the dependence of grain boundary energy and width on the curvature. The growth exponent {ital m} of power growth law for a polycrystalline system is affected by the segregation of solutes to grain boundaries. With the solute drag, the growth exponent {ital m} can take any value between 2 and 3, depending on the ratio of lattice diffusion to grain boundary mobility. The grain size and topological distributions are unaffected by solute drag, which are the same as those in a pure system. {copyright} {ital 1999 Materials Research Society.}

  20. Atomically ordered solute segregation behaviour in an oxide grain boundary.

    PubMed

    Feng, Bin; Yokoi, Tatsuya; Kumamoto, Akihito; Yoshiya, Masato; Ikuhara, Yuichi; Shibata, Naoya

    2016-01-01

    Grain boundary segregation is a critical issue in materials science because it determines the properties of individual grain boundaries and thus governs the macroscopic properties of materials. Recent progress in electron microscopy has greatly improved our understanding of grain boundary segregation phenomena down to atomistic dimensions, but solute segregation is still extremely challenging to experimentally identify at the atomic scale. Here, we report direct observations of atomic-scale yttrium solute segregation behaviours in an yttria-stabilized-zirconia grain boundary using atomic-resolution energy-dispersive X-ray spectroscopy analysis. We found that yttrium solute atoms preferentially segregate to specific atomic sites at the core of the grain boundary, forming a unique chemically-ordered structure across the grain boundary. PMID:27004614

  1. Interpretation of far infra-red emission from interstellar grains

    NASA Technical Reports Server (NTRS)

    Caroff, L. J.; Salpeter, E. E.; Wagoner, R. V.; Werner, M. W.; Petrosian, V.

    1973-01-01

    Application of the Kramers-Kronig relations to grains in the interstellar medium. It is found that the recent UV, visual, and infrared extinction curves provide marginal evidence against silicates as the major cause of this extinction. In the far infrared, grains contribute little to the extinction, but can be observed in thermal emission. It is shown that the far infrared emission from grains in a given bandwidth sets a lower limit to the grain temperature. From observed intensities from the galactic plane at 100 microns and from Orion at 350 microns, minimum grain temperatures are found which are larger than the observed brightness temperature. The emission and extinction data can be used together to constrain the allowable range of parameters for the grains.

  2. The bio refinery; producing feed and fuel from grain.

    PubMed

    Scholey, D V; Burton, E J; Williams, P E V

    2016-04-15

    It is both possible and practicable to produce feed and fuel from grain. Using the value of grain to produce renewable energy for transport, while using the remaining protein content of the grain as a valuable protein source for livestock and for fish, can be seen as a complimentary and optimal use of all the grain constituents. Consideration must be given to maximise the value of the yeast components, as substantial yeast is generated during the fermentation of the grain starch to produce ethanol. Yeast is a nutritionally rich feed ingredient, with potential for use both as feed protein and as a feed supplement with possible immunity and gut health enhancing properties. Bioprocessing, with the consequent economies of scale, is a process whereby the value of grain can be optimised in a way that is traditional, natural and sustainable for primarily producing protein and oil for feed with a co-product ethanol as a renewable fuel. PMID:26617037

  3. OBSERVATIONS OF ENHANCED RADIATIVE GRAIN ALIGNMENT NEAR HD 97300

    SciTech Connect

    Andersson, B-G; Potter, S. B. E-mail: sbp@saao.ac.z

    2010-09-10

    We have obtained optical multi-band polarimetry toward sightlines through the Chamaeleon I cloud, particularly in the vicinity of the young B9/A0 star HD 97300. We show, in agreement with earlier studies, that the radiation field impinging on the cloud in the projected vicinity of the star is dominated by the flux from the star, as evidenced by a local enhancement in the grain heating. By comparing the differential grain heating with the differential change in the location of the peak of the polarization curve, we show that the grain alignment is enhanced by the increase in the radiation field. We also find a weak, but measurable, variation in the grain alignment with the relative angle between the radiation field anisotropy and the magnetic field direction. Such an anisotropy in the grain alignment is consistent with a unique prediction of modern radiative alignment torque theory and provides direct support for radiatively driven grain alignment.

  4. Computer Simulation of Grain Growth Kinetics with Solute Drag

    SciTech Connect

    Chen, L.; Chen, S.P.; Fan, D.

    1998-12-23

    The effects of solute dragon grain growth kinetics were studied in two dimensional (2-D) computer simulations by using a diffuse-interface field model. It is shown that, in the low velocity / low driving force regime, the velocity of a grain boundary motion departs from a linear relation with driving force (curvature) with solute drag. The nonlinear relation of migration velocity and driving force comes from the dependence of grain boundary energy and width on the curvature. The growth exponent m of power growth law for a polycrystalline system is affected by the segregation of solutes to grain boundaries. With the solute drag, the growth exponent m can take any value between 2 and 3 depending on the ratio of lattice diffusion to grain boundary mobility. The grain size and topological distributions are unaffected by solute drag, which are the same as those in a pure system.

  5. Activation Energy for Grain Growth in Aluminum Coatings

    SciTech Connect

    Jankowski, A F; Ferreira, J L; Hayes, J P

    2004-10-14

    To produce a specific grain size in metallic coatings requires precise control of the time at temperature during the deposition process. Aluminum coatings are deposited using electron-beam evaporation onto heated substrate surfaces. The grain size of the coating is determined upon examination of the microstructure in plan view and cross-section. Ideal grain growth is observed over the entire experimental range of temperature examined from 413 to 843 K. A transition in the activation energy for grain growth from 0.7 to 3.8 eV {center_dot} atom{sup -1} is observed as the temperature increases from <526 K to >588 K. The transition is indicative of the dominant mechanism for grain growth shifting with increasing temperature from grain boundary to lattice diffusion.

  6. Atomically ordered solute segregation behaviour in an oxide grain boundary

    PubMed Central

    Feng, Bin; Yokoi, Tatsuya; Kumamoto, Akihito; Yoshiya, Masato; Ikuhara, Yuichi; Shibata, Naoya

    2016-01-01

    Grain boundary segregation is a critical issue in materials science because it determines the properties of individual grain boundaries and thus governs the macroscopic properties of materials. Recent progress in electron microscopy has greatly improved our understanding of grain boundary segregation phenomena down to atomistic dimensions, but solute segregation is still extremely challenging to experimentally identify at the atomic scale. Here, we report direct observations of atomic-scale yttrium solute segregation behaviours in an yttria-stabilized-zirconia grain boundary using atomic-resolution energy-dispersive X-ray spectroscopy analysis. We found that yttrium solute atoms preferentially segregate to specific atomic sites at the core of the grain boundary, forming a unique chemically-ordered structure across the grain boundary. PMID:27004614

  7. The bio refinery; producing feed and fuel from grain.

    PubMed

    Scholey, D V; Burton, E J; Williams, P E V

    2016-04-15

    It is both possible and practicable to produce feed and fuel from grain. Using the value of grain to produce renewable energy for transport, while using the remaining protein content of the grain as a valuable protein source for livestock and for fish, can be seen as a complimentary and optimal use of all the grain constituents. Consideration must be given to maximise the value of the yeast components, as substantial yeast is generated during the fermentation of the grain starch to produce ethanol. Yeast is a nutritionally rich feed ingredient, with potential for use both as feed protein and as a feed supplement with possible immunity and gut health enhancing properties. Bioprocessing, with the consequent economies of scale, is a process whereby the value of grain can be optimised in a way that is traditional, natural and sustainable for primarily producing protein and oil for feed with a co-product ethanol as a renewable fuel.

  8. Grain growth and structural relaxation of nanocrystalline Bi₂Te₃

    SciTech Connect

    Humphry-Baker, Samuel A.; Schuh, Christopher A.

    2014-10-21

    Recovery and grain growth behavior is investigated systematically for the nanocrystalline thermoelectric compound bismuth telluride, synthesized by mechanical alloying. During annealing treatments at elevated temperatures, structural evolution is tracked using x-ray diffraction, electron microscopy and calorimetry. Below a homologous temperature of about 0.6T{sub m}, grain growth occurs slowly with an activation energy of 89 kJ/mol. However above this temperature grain growth becomes more rampant with an activation energy of 242 kJ/mol. The transition is attributed to a shift from a relaxation or recovery process that includes some reordering of the grain boundary structure, to a more conventional diffusionally-limited grain growth process. By extrapolating the measured grain growth and microstrain evolution kinetics, a thermal budget map is constructed, permitting recommendations for improving the thermoelectric properties of nanocrystalline materials processed via a powder route.

  9. Modeling the secondary emission yield of salty ice dust grains

    NASA Astrophysics Data System (ADS)

    Richterová, I.; Němeček, Z.; Pavlů, J.; Beránek, M.; Šafránková, J.

    2011-03-01

    Secondary emission is one of important processes leading to dust grain charging in many plasma environments. The secondary yield varies with the grain material, shape, and size. Several experiments confirmed that the yield of small grains differs from that of planar samples. Among other materials, ices of different compositions can be frequently found in the interplanetary space and/or planetary magnetospheres. However, the admixtures can significantly influence the inner structure of such materials and thus may change their yield. We present numerical simulations that provide a realistic description of the secondary emission process from water ice grains. The simulations reveal that the secondary emission yield increases as the grain dimension decreases to tens of nanometers. The yield of backscattered primary electrons approaches unity and the grain can be charged to high positive potentials under these conditions. We found that any reasonable admixture of NaCl does not alter secondary electron emission properties significantly.

  10. Kinetic constants of abnormal grain growth in nanocrystalline nickel

    NASA Astrophysics Data System (ADS)

    Aleshin, A. N.

    2016-02-01

    The grain growth in nanocrystalline nickel with a purity of 99.5 at % during non-isothermal annealing was experimentally investigated using differential scanning calorimetry and transmission electron microscopy. Nanocrystalline nickel was prepared by electrodeposition and had an average grain size of approximately 20 nm. It was shown that, at a temperature corresponding to the calorimetric signal peak, abnormal grain growth occurs with the formation of a bimodal grain microstructure. Calorimeters signals were processed within the Johnson-Mehl-Avrami formalism. This made it possible to determine the exponent of the corresponding equation, the frequency factor, and the activation energy of the grain growth, which was found to be equal to the activation energy of the vacancy migration. The reasons for the abnormal grain growth in nanocrystalline nickel were discussed.

  11. Gas-Grain Simulation Facility (GGSF)

    NASA Technical Reports Server (NTRS)

    Greenwald, Ken

    1992-01-01

    The goal of the Gas-Grain Simulation Facility project is to provide a microgravity laboratory to facilitate research relevant to exobiology (the study of the origin and evolution of life in the universe). Such a facility will also be useful in other areas of study important to NASA including planetary science, biology, atmospheric science, astrophysics, chemistry, and physics. To achieve this goal, the project will develop and support the GGSF, a modular facility-class payload planned for inclusion on Space Station Freedom. The GGSF will consist of the following: an experiment chamber(s) supported by subsystems that provide chamber environment regulation and monitoring capabilities; sample generation, injection, positioning, and retrieval capabilities; and computer control, data acquisition, and housekeeping capabilities. The facility will also provide analytical tools such as light-scattering measurement systems, aerosol size-spectrum measurement devices, and optical imaging systems.

  12. Method of making fine-grained triaminotrinitrobenzene

    DOEpatents

    Benziger, T.M.

    1983-07-26

    A method is given for forming a fine-grained species of the insensitive high explosive sym-triaminotrinitrobenzene (TATB) without grinding. In accordance with the method, 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) is aminated by reaction with gaseous ammonia in an emulsion of toluene in water. The ratio of water to toluene in the emulsion is selected so that toluene is the dispersed phase in the emulsion. The size of the dispersed TCTNB-containing toluene droplets determines the particle size of the resulting TATB. The emulsion is preferably formed with an emulsifier such as ammonium oleate, which may be generated in situ from oleic acid, and stabilized with a protective colloid such as polyvinyl alcohol.

  13. Method of making fine-grained triaminotrinitrobenzene

    DOEpatents

    Benziger, Theodore M.

    1984-01-01

    A method of forming a fine-grained species of the insensitive high explosive sym-triaminotrinitrobenzene (TATB) without grinding. In accordance with the method, 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) is aminated by reaction with gaseous ammonia in an emulsion of toluene in water. The ratio of water to toluene in the emulsion is selected so that toluene is the dispersed phase in the emulsion. The size of the dispersed TCTNB-containing toluene droplets determines the particle size of the resulting TATB. The emulsion is preferably formed with an emulsifier such as ammonium oleate, which may be generated in situ from oleic acid, and stabilized with a protective colloid such as polyvinyl alcohol.

  14. Toxigenicity of fungi from grain sorghum.

    PubMed

    Diener, U L; Morgan-Jones, G; Wagener, R E; Davis, N D

    1981-07-10

    The mycoflora of nine varieties of grain sorghum was determined by plating serial dilutions of ground samples on rose bengal-streptomycin agar. Seventeen species of fungi representing 10 genera were identified. Curvularia, Penicillium, Mucor, and Aspergillus were dominant genera. Extracts of P. herquei were highly toxic to brine shrimp, while those of C. clavata, C. lunata, and Mucor mucedo showed low to moderate toxicity. Extracts of C. clavata, C. lunata, and M. mucedo were highly toxic to chicken embryos; those of six other species showed low to moderate toxicity. Extracts of C. clavata, C. lunata, M. mucedo, Fusarium moniliforme, Alternaria tenuissima. P. herquei, and P. steckii showed varying degrees of toxicity to day-old cockerels.

  15. The fine grained detector readout electronics

    NASA Astrophysics Data System (ADS)

    Retière, F.; T2K/FGD Collaboration

    2010-11-01

    The Fine Grained Detector (FGD) readout electronics was designed to record a snapshot of the detector activity before, during and after the neutrino beam spill produced by the J-PARC accelerator complex in Tokai, Japan. The FGD is a key element of T2K near detector currently being constructed. It will act as an active target detecting charged particles produced within its scintillator bars. The original feature of the FGD electronics is to readout Multi-Pixel Photon Counters by recording waveforms using Switch Capacitor Array chips (AFTER ASIC) designed for T2K Time Projection Chamber. In these proceedings, we describe the architecture of the FGD electronics. Beam results show that the physics requirements are met or exceeded. The relatively slow sampling frequency of the AFTER ASIC does not impair the timing resolution significantly. In addition, the very good efficiency of the system for detecting Michel electrons produced by pions or muons decay has been demonstrated.

  16. Detection of organic matter in interstellar grains.

    PubMed

    Pendleton, Y J

    1997-06-01

    Star formation and the subsequent evolution of planetary systems occurs in dense molecular clouds, which are comprised, in part, of interstellar dust grains gathered from the diffuse interstellar medium (DISM). Radio observations of the interstellar medium reveal the presence of organic molecules in the gas phase and infrared observational studies provide details concerning the solid-state features in dust grains. In particular, a series of absorption bands have been observed near 3.4 microns (approximately 2940 cm-1) towards bright infrared objects which are seen through large column densities of interstellar dust. Comparisons of organic residues, produced under a variety of laboratory conditions, to the diffuse interstellar medium observations have shown that aliphatic hydrocarbon grains are responsible for the spectral absorption features observed near 3.4 microns (approximately 2940 cm-1). These hydrocarbons appear to carry the -CH2- and -CH3 functional groups in the abundance ratio CH2/CH3 approximately 2.5, and the amount of carbon tied up in this component is greater than 4% of the cosmic carbon available. On a galactic scale, the strength of the 3.4 microns band does not scale linearly with visual extinction, but instead increases more rapidly for objects near the Galactic Center. A similar trend is noted in the strength of the Si-O absorption band near 9.7 microns. The similar behavior of the C-H and Si-O stretching bands suggests that these two components may be coupled, perhaps in the form of grains with silicate cores and refractory organic mantles. The ubiquity of the hydrocarbon features seen in the near infrared near 3.4 microns throughout out Galaxy and in other galaxies demonstrates the widespread availability of such material for incorporation into the many newly forming planetary systems. The similarity of the 3.4 microns features in any organic material with aliphatic hydrocarbons underscores the need for complete astronomical observational

  17. Dust grains from the heart of supernovae

    NASA Astrophysics Data System (ADS)

    Bocchio, M.; Marassi, S.; Schneider, R.; Bianchi, S.; Limongi, M.; Chieffi, A.

    2016-03-01

    Dust grains are classically thought to form in the winds of asymptotic giant branch (AGB) stars. However, there is increasing evidence today for dust formation in supernovae (SNe). To establish the relative importance of these two classes of stellar sources of dust, it is important to know the fraction of freshly formed dust in SN ejecta that is able to survive the passage of the reverse shock and be injected in the interstellar medium. With this aim, we have developed a new code, GRASH_Rev, that allows following the dynamics of dust grains in the shocked SN ejecta and computing the time evolution of the mass, composition, and size distribution of the grains. We considered four well-studied SNe in the Milky Way and Large Magellanic Cloud: SN 1987A, CasA, the Crab nebula, and N49. These sources have been observed with both Spitzer and Herschel, and the multiwavelength data allow a better assessment the mass of warm and cold dust associated with the ejecta. For each SN, we first identified the best explosion model, using the mass and metallicity of the progenitor star, the mass of 56Ni, the explosion energy, and the circumstellar medium density inferred from the data. We then ran a recently developed dust formation model to compute the properties of freshly formed dust. Starting from these input models, GRASH_Rev self-consistently follows the dynamics of the grains, considering the effects of the forward and reverse shock, and allows predicting the time evolution of the dust mass, composition, and size distribution in the shocked and unshocked regions of the ejecta. All the simulated models aagree well with observations. Our study suggests that SN 1987A is too young for the reverse shock to have affected the dust mass. Hence the observed dust mass of 0.7-0.9 M⊙ in this source can be safely considered as indicative of the mass of freshly formed dust in SN ejecta. Conversely, in the other three SNe, the reverse shock has already destroyed between 10-40% of the

  18. A generic fine-grained parallel C

    NASA Technical Reports Server (NTRS)

    Hamet, L.; Dorband, John E.

    1988-01-01

    With the present availability of parallel processors of vastly different architectures, there is a need for a common language interface to multiple types of machines. The parallel C compiler, currently under development, is intended to be such a language. This language is based on the belief that an algorithm designed around fine-grained parallelism can be mapped relatively easily to different parallel architectures, since a large percentage of the parallelism has been identified. The compiler generates a FORTH-like machine-independent intermediate code. A machine-dependent translator will reside on each machine to generate the appropriate executable code, taking advantage of the particular architectures. The goal of this project is to allow a user to run the same program on such machines as the Massively Parallel Processor, the CRAY, the Connection Machine, and the CYBER 205 as well as serial machines such as VAXes, Macintoshes and Sun workstations.

  19. Coarse-grained modeling of DNA curvature

    NASA Astrophysics Data System (ADS)

    Freeman, Gordon S.; Hinckley, Daniel M.; Lequieu, Joshua P.; Whitmer, Jonathan K.; de Pablo, Juan J.

    2014-10-01

    The interaction of DNA with proteins occurs over a wide range of length scales, and depends critically on its local structure. In particular, recent experimental work suggests that the intrinsic curvature of DNA plays a significant role on its protein-binding properties. In this work, we present a coarse grained model of DNA that is capable of describing base-pairing, hybridization, major and minor groove widths, and local curvature. The model represents an extension of the recently proposed 3SPN.2 description of DNA [D. M. Hinckley, G. S. Freeman, J. K. Whitmer, and J. J. de Pablo, J. Chem. Phys. 139, 144903 (2013)], into which sequence-dependent shape and mechanical properties are incorporated. The proposed model is validated against experimental data including melting temperatures, local flexibilities, dsDNA persistence lengths, and minor groove width profiles.

  20. Coarse-grained model of glycosaminoglycans.

    PubMed

    Samsonov, Sergey A; Bichmann, Leon; Pisabarro, M Teresa

    2015-01-26

    Glycosaminoglycans (GAGs) represent a class of anionic periodic linear polysaccharides, which mediate cell communication processes by interactions with their protein targets in the extracellular matrix. Due to their high flexibility, charged nature, periodicity, and polymeric nature, GAGs are challenging systems for computational approaches. To deal with the length challenge, coarse-grained (CG) modeling could be a promising approach. In this work, we develop AMBER-compatible CG parameters for GAGs using all-atomic (AA) molecular dynamics (MD) simulations in explicit solvent and the Boltzmann conversion approach. We compare both global and local properties of GAGs obtained in the simulations with AA and CG approaches, and we conclude that our CG model is appropriate for the MD approach of long GAG molecules at long time scales.

  1. Soil Sampling Techniques For Alabama Grain Fields

    NASA Technical Reports Server (NTRS)

    Thompson, A. N.; Shaw, J. N.; Mask, P. L.; Touchton, J. T.; Rickman, D.

    2003-01-01

    Characterizing the spatial variability of nutrients facilitates precision soil sampling. Questions exist regarding the best technique for directed soil sampling based on a priori knowledge of soil and crop patterns. The objective of this study was to evaluate zone delineation techniques for Alabama grain fields to determine which method best minimized the soil test variability. Site one (25.8 ha) and site three (20.0 ha) were located in the Tennessee Valley region, and site two (24.2 ha) was located in the Coastal Plain region of Alabama. Tennessee Valley soils ranged from well drained Rhodic and Typic Paleudults to somewhat poorly drained Aquic Paleudults and Fluventic Dystrudepts. Coastal Plain s o i l s ranged from coarse-loamy Rhodic Kandiudults to loamy Arenic Kandiudults. Soils were sampled by grid soil sampling methods (grid sizes of 0.40 ha and 1 ha) consisting of: 1) twenty composited cores collected randomly throughout each grid (grid-cell sampling) and, 2) six composited cores collected randomly from a -3x3 m area at the center of each grid (grid-point sampling). Zones were established from 1) an Order 1 Soil Survey, 2) corn (Zea mays L.) yield maps, and 3) airborne remote sensing images. All soil properties were moderately to strongly spatially dependent as per semivariogram analyses. Differences in grid-point and grid-cell soil test values suggested grid-point sampling does not accurately represent grid values. Zones created by soil survey, yield data, and remote sensing images displayed lower coefficient of variations (8CV) for soil test values than overall field values, suggesting these techniques group soil test variability. However, few differences were observed between the three zone delineation techniques. Results suggest directed sampling using zone delineation techniques outlined in this paper would result in more efficient soil sampling for these Alabama grain fields.

  2. Glasses in coarse-grained micrometeorites

    NASA Astrophysics Data System (ADS)

    Varela, M. E.; Kurat, G.

    2009-06-01

    Micrometeorites (MMs, interplanetary dust particles with 25 - 500 μm diameters) carry the main mass of extraterrestrial matter that is captured by Earth. The coarse-grained MMs mainly consist of olivine aggregates, which - as their counterparts in CC chondrites - also contain pyroxenes and glass. We studied clear glasses in four coarse-grained crystalline MMs (10M12, M92-6b, AM9, and Mc7-10), which were collected from the ice at Cap Prudhomme, Antarctica. Previous studies of glasses (e.g., glass inclusions trapped in olivine and clear mesostasis glass) in carbonaceous and ordinary chondrites showed that these phases could keep memory of the physical-chemical conditions to which extraterrestrial matter was exposed. Here we compare the chemical compositions of MM glasses and glasses from CM chondrites with that in experimentally heated objects from the Allende CV chondrite and with glasses from cometary particles. Our results show that MMs were heated to variable degrees (during entry through the terrestrial atmosphere), which caused a range from very little chemical modification of the glass to total melting of the precursor object. Such modifications include dissolution of minerals in the melted glass precursor and some loss of volatile alkali elements. The chemical composition of all precursor glasses in the MMs investigated is not primitive such as glasses in CM and CR chondrite objects. It shows signs of pre-terrestrial chemical modification, e.g., metasomatic enrichments in Na and Fe 2+ presumably in the solar nebula. Glasses of MMs heated to very low degree have a chemical composition indistinguishable from that of glasses in comet Wild 2 particles; giving additional evidence that interplanetary dust (e.g., Antarctic MMs) possibly represents samples from comets.

  3. Ceres Revealed in a Grain of Salt

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Bodnar, R. J.; Fries, M.; Chan, Q. H.-S.; Kebukawa, Y.; Mikouchi, T.; Hagiya, K.; Komatsu, M.; Ohsumi, K.; Steele, A.

    2016-01-01

    Introduction: Zag and Monahans (1998) are H chondrite regolith breccias containing 4.5 giga-year-old halite crystals which contain abundant inclusions of aqueous fluids, solids and organics. These all originated on a cryo-volcanically-active C class asteroid, probably 1 Ceres; the halite was transported to the regolith of the H chondrite parent asteroid, potentially 6 Hebe. Detailed analysis of these solids will thus potentially reveal the mineralogy of Ceres. Mineralogy of solids in the Monahans Halite Solid grains are present in the halites, which were entrained within the mother brines during eruption, including material from the interior and surface of the erupting body. The solids include abundant, widely variable organics that could not have been significantly heated (which would have resulted in the loss of fluids from the halite). Our analyses by Raman microprobe, SEM/EDX, synchrotron X-ray diffraction, UPLC-FD/QToF-MS, C-XANES and TEM reveal that these trapped grains include macromolecular carbon (MMC) similar in structure to CV3 chondrite matrix carbon, aliphatic carbon compounds, olivine (Fo99-59), high- and low-Ca pyroxene, feldspars, phyllosilicates, magnetite, sulfides, metal, lepidocrocite, carbonates, diamond, apatite and zeolites. Conclusions: The halite in Monahans and Zag derive from a water and carbon-rich object that was cryo-volcanically active in the early solar system, probably Ceres. The Dawn spacecraft found that Ceres includes C chondrite materials. Our samples include both protolith and aqueously-altered samples of the body, permitting understanding of alteration conditions. Whatever the halite parent body, it was rich in a wide variety of organics and warm, liquid water at the solar system's dawn.

  4. Grain boundary hardening and triple junction hardening in polycrystalline molybdenum

    SciTech Connect

    Kobayashi, Shigeaki . E-mail: skoba@ashitech.ac.jp; Tsurekawa, Sadahiro; Watanabe, Tadao

    2005-02-01

    The grain boundary and triple junction hardenings in molybdenum with different carbon content were studied in connection with the character and the connectivity of grain boundaries at triple junctions by the micro-indentation test. The triple junction hardening is smaller at the junctions composed of low-angle and {sigma} boundaries than at the junctions composed of random boundaries. This difference in the hardening depending on the grain boundary connectivity becomes more significant with a decrease in carbon content in molybdenum.

  5. The scaling state in two-dimensional grain growth

    SciTech Connect

    Mulheran, P.A. . Dept. of Physics)

    1994-11-01

    A new model of normal grain growth in two-dimensional systems is derived from considerations of Potts model simulations. This Randomly Connected Bubble model is based on Hillert's theory and combines the essential topological features of the grain boundary network with the action of capillarity. It successfully predicts what the scaling state of the network should be and explains why the system evolves into this state. The implications for grain growth in real materials are also discussed.

  6. Potts-model grain growth simulations: Parallel algorithms and applications

    SciTech Connect

    Wright, S.A.; Plimpton, S.J.; Swiler, T.P.

    1997-08-01

    Microstructural morphology and grain boundary properties often control the service properties of engineered materials. This report uses the Potts-model to simulate the development of microstructures in realistic materials. Three areas of microstructural morphology simulations were studied. They include the development of massively parallel algorithms for Potts-model grain grow simulations, modeling of mass transport via diffusion in these simulated microstructures, and the development of a gradient-dependent Hamiltonian to simulate columnar grain growth. Potts grain growth models for massively parallel supercomputers were developed for the conventional Potts-model in both two and three dimensions. Simulations using these parallel codes showed self similar grain growth and no finite size effects for previously unapproachable large scale problems. In addition, new enhancements to the conventional Metropolis algorithm used in the Potts-model were developed to accelerate the calculations. These techniques enable both the sequential and parallel algorithms to run faster and use essentially an infinite number of grain orientation values to avoid non-physical grain coalescence events. Mass transport phenomena in polycrystalline materials were studied in two dimensions using numerical diffusion techniques on microstructures generated using the Potts-model. The results of the mass transport modeling showed excellent quantitative agreement with one dimensional diffusion problems, however the results also suggest that transient multi-dimension diffusion effects cannot be parameterized as the product of the grain boundary diffusion coefficient and the grain boundary width. Instead, both properties are required. Gradient-dependent grain growth mechanisms were included in the Potts-model by adding an extra term to the Hamiltonian. Under normal grain growth, the primary driving term is the curvature of the grain boundary, which is included in the standard Potts-model Hamiltonian.

  7. Peculiarities of the Field Electron Emission from Dust Grains

    SciTech Connect

    Richterova, I.; Beranek, M.; Pavlu, J.; Nemecek, Z.; Safrankova, J.

    2008-09-07

    The goal of the paper is investigation of the electron field emission that limits the attainable grain charge and can prevent electrostatic fragmentation of loosely bounded aggregates of dust grains. We have found that the effective work function of the spherical amorphous carbon grains does not depend on the relative beam energy. Preliminary results on an influence of the ion treatment/cleaning using the simultaneous electron and ion bombardments are discussed.

  8. Climate and the Soviet Grain Crisis of 1928

    NASA Astrophysics Data System (ADS)

    Welker, Jean Edward

    1995-01-01

    This dissertation tests the premise that peasant hoarding of surplus grain supplies and the refusal of the rural Soviet peasants to sell grain to state procurement apparatus during the late New Economic Policy period, caused the Grain Crisis of 1928. The peasants' reluctance to sell grain and claims of peasant hoarding could only occur if sufficient grain surpluses existed during this period. The existence of these assumed grain surpluses is shown to be highly improbable. First, the large but inconsistent body of 1920s grain statistics was evaluated per se and related to two periods of pre-WWI data, the Witte and Stolypin years, on a practical comparison whenever possible. For both these pre-World War I periods, intensive links between rapid industrialization and agriculture had been established similar to the conditions of the 1920s. The climatic conditions of the two imperial and one Soviet period in the 1920s, especially drought in 1927, was analyzed, and its impact on grain production estimated and interpreted. The conclusion was reached that the cause of drop in grain production in 1927 was due to a long-term and persistent trend of regional drought affecting spring wheat yields, especially in the areas of the Middle Volga and Kazakhstan. Second, the resultant conclusion was reached that there was insufficient bread grain on a national basis in 1927 to meet the essential needs of the rural peasants, much less the increasing demands of the government procurements. Third, the government's 1927 policy of monopolizing all available "surpluses" on the grain market under the false assumption that these surpluses were abundant, demonstrated either naivete and incompetence, or political expediency. This monopolization contributed to a breakdown in the marketing distribution of available grain, and generally exacerbated the poor procurement situation which was publically and incorrectly blamed on the peasants' hoarding.

  9. Landau-Lifshitz-Bloch equation for exchange-coupled grains

    NASA Astrophysics Data System (ADS)

    Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter

    2014-12-01

    Heat-assisted recording is a promising technique to further increase the storage density in hard disks. Multilayer recording grains with graded Curie temperature is discussed to further assist the write process. Describing the correct magnetization dynamics of these grains, from room temperature to far above the Curie point, during a write process is required for the calculation of bit error rates. We present a coarse-grained approach based on the Landau-Lifshitz-Bloch (LLB) equation to model exchange-coupled grains with low computational effort. The required temperature-dependent material properties such as the zero-field equilibrium magnetization as well as the parallel and normal susceptibilities are obtained by atomistic Landau-Lifshitz-Gilbert simulations. Each grain is described with one magnetization vector. In order to mimic the atomistic exchange interaction between the grains a special treatment of the exchange field in the coarse-grained approach is presented. With the coarse-grained LLB model the switching probability of a recording grain consisting of two layers with graded Curie temperature is investigated in detail by calculating phase diagrams for different applied heat pulses and external magnetic fields.

  10. New Process for Grain Refinement of Aluminum. Final Report

    SciTech Connect

    Dr. Joseph A. Megy

    2000-09-22

    A new method of grain refining aluminum involving in-situ formation of boride nuclei in molten aluminum just prior to casting has been developed in the subject DOE program over the last thirty months by a team consisting of JDC, Inc., Alcoa Technical Center, GRAS, Inc., Touchstone Labs, and GKS Engineering Services. The Manufacturing process to make boron trichloride for grain refining is much simpler than preparing conventional grain refiners, with attendant environmental, capital, and energy savings. The manufacture of boride grain refining nuclei using the fy-Gem process avoids clusters, salt and oxide inclusions that cause quality problems in aluminum today.

  11. Tribocharging and charged interaction in same-material, microscopic grains

    NASA Astrophysics Data System (ADS)

    Waitukaitis, S.; Lee, V.; Jaeger, H.

    2015-10-01

    We experimentally address the causes and consequences of charging between same-material, microscopic grains. We confirm quantitatively that differences in grain size alone drive charging. By comparing our data to independent thermoluminescence measurements, we show that trapped electrons are not the charged species being transferred. We observe and quantify a zoology of interactions between grains, including attractive orbits and repulsive slingshot events, cluster growth and annihilation via collisions, and granular molecule formation. Our results highlight the important role played by grain polarizability in aggregation and have implications for the dynamics of dust particles in protoplanetary disks.

  12. Stability of Small Grains in HII Regions and Reflection Nebulae

    NASA Technical Reports Server (NTRS)

    Werner, M. W.; Gauthier, T. N., III; Cawlfield, T.

    1993-01-01

    We have analyzed IRAS data to assess the relative amounts of small and large grains in HII regions and reflection nebulae. Our most important finding is that no evidence for small grain destruction is seen in reflection nebulae, even for [high] values of the radiation energy density at which significant grain destruction apparently occurs in HII regions. This suggests that it is not only the total radiant energy density but also the energy per photon which determines the stability of small grains in astrophysical environments.

  13. Grain metamorphism in polar nitrogen ice on Triton

    NASA Technical Reports Server (NTRS)

    Zent, Aaron P.; Mckay, Christopher P.; Pollack, James B.; Cruikshank, Dale P.

    1989-01-01

    The rate of nitrogen grain growth on putative N2-rich polar caps on Triton is calculated. For most plausible assumptions of independent variables, mean grain sizes in polar N2 are meter-scale. Triton's polar caps should constitute the definitive solar-system test bed for the process of ice grain metamorphism. Interpretation of data already in hand may require long path length through condensed N2, possibly due to grain growth. Upcoming Voyager data may clarify the situation, although possible complications in detecting a glaze of N2 ice exist.

  14. Production and Recoil Loss of Cosmogenic Nuclides in Presolar Grains

    NASA Astrophysics Data System (ADS)

    Trappitsch, Reto; Leya, Ingo

    2016-05-01

    Presolar grains are small particles that condensed in the vicinity of dying stars. Some of these grains survived the voyage through the interstellar medium (ISM) and were incorporated into meteorite parent bodies at the formation of the Solar System. An important question is when these stellar processes happened, i.e., how long presolar grains were drifting through the ISM. While conventional radiometric dating of such small grains is very difficult, presolar grains are irradiated with galactic cosmic rays (GCRs) in the ISM, which induce the production of cosmogenic nuclides. This opens the possibility to determine cosmic-ray exposure (CRE) ages, i.e., how long presolar grains were irradiated in the ISM. Here, we present a new model for the production and loss of cosmogenic 3He, 6,7Li, and 21,22Ne in presolar SiC grains. The cosmogenic production rates are calculated using a state-of-the-art nuclear cross-section database and a GCR spectrum in the ISM consistent with recent Voyager data. Our findings are that previously measured 3He and 21Ne CRE ages agree within the (sometimes large) 2σ uncertainties and that the CRE ages for most presolar grains are smaller than the predicted survival times. The obtained results are relatively robust since interferences from implanted low-energy GCRs into the presolar SiC grains and/or from cosmogenic production within the meteoroid can be neglected.

  15. Computer simulation of grain growth with mobile particles

    SciTech Connect

    Hassold, G.N.; Srolovitz, D.J.

    1995-05-15

    The authors have studied the influence of mobile particles on grain growth kinetics. Three time regimes are evident in the observed coarsening. Initially, most grains grow unhindered by particles, with a growth exponent close to 1/2. As with static impurities, once the mean grain size approaches the average inter-particle separation the microstructure becomes effectively pinned. With mobile impurities, however, the loaded grain boundaries eventually resume their motion. The depinning time is observed to be independent of particle concentration. The observed kinetic behavior, growth exponents, and depinning time are in agreement with a simple theoretical model with different mobilities for boundaries with and without attached particles.

  16. Influence of point defects on grain boundary diffusion in oxides

    SciTech Connect

    Stubican, V.S.

    1991-03-15

    The influence of point defects on grain boundary diffusion of Co ions in NiO was studied using polycrystalline films and bicrystals. Grain boundary diffusion was studied at 750 C at oxygen partial pressure. Two diffusion regions were found. At low oxygen pressures, extrinsic diffusion was observed. Above oxygen pressure of 10{sup {minus}7}, influence of intrinsic point defects was detected. It was determined that grain boundary diffusion was > 3 orders of magnitude faster than volume diffusion. However, it seems that grain boundary diffusion is influenced by the point defects in a similar way as the volume diffusion. 4 figs.

  17. Magnetoresistance of polycrystalline gadolinium with varying grain size

    SciTech Connect

    Chakravorty, Manotosh Raychaudhuri, A. K.

    2015-01-21

    In this paper, we report a study of evolution of low field magnetoresistance (MR) of Gadolinium as the grain size in the sample is changed from few microns (∼4 μm) to the nanoscopic regime (∼35 nm). The low field MR has a clear effect on varying grain size. In large grain sample (few μm), the magnetic domains are controlled by local anisotropy field determined mainly by the magnetocrystalline anisotropy. The low field MR clearly reflects the temperature dependence of the magnetocrystalline anisotropy. For decreasing gain size, the contribution of spin disorder at the grain boundary increases and enhances the local anisotropy field.

  18. Grain metamorphism in polar nitrogen ice on triton

    SciTech Connect

    Zent, A.P.; McKay, C.P.; Pollack, J.B.; Cruikshank, D.P. )

    1989-08-01

    The authors calculate the rate of nitrogen grain growth on putative N{sub 2}-rich polar caps on Triton. For most plausible assumptions of independent variables, mean grain sizes in polar N{sub 2} are meter-scale. Triton's polar caps should constitute the definitive solar-system test bed for the process of ice grain metamorphism. Interpretation of data already in hand many require long path length through condensed N{sub 2}, possibly due to grain growth. Upcoming Voyager data may clarify the situation, although possible complications in detecting a glaze of N{sub 2} ice exist.

  19. Phase field modeling of grain growth in porous polycrystalline solids

    NASA Astrophysics Data System (ADS)

    Ahmed, Karim E.

    The concurrent evolution of grain size and porosity in porous polycrystalline solids is a technically important problem. All the physical properties of such materials depend strongly on pore fraction and pore and grain sizes and distributions. Theoretical models for the pore-grain boundary interactions during grain growth usually employ restrictive, unrealistic assumptions on the pore and grain shapes and motions to render the problem tractable. However, these assumptions limit the models to be only of qualitative nature and hence cannot be used for predictions. This has motivated us to develop a novel phase field model to investigate the process of grain growth in porous polycrystalline solids. Based on a dynamical system of coupled Cahn-Hilliard and All en-Cahn equations, the model couples the curvature-driven grain boundary motion and the migration of pores via surface diffusion. As such, the model accounts for all possible interactions between the pore and grain boundary, which highly influence the grain growth kinetics. Through a formal asymptotic analysis, the current work demonstrates that the phase field model recovers the corresponding sharp-interface dynamics of the co-evolution of grain boundaries and pores; this analysis also fixes the model kinetic parameters in terms of real materials properties. The model was used to investigate the effect of porosity on the kinetics of grain growth in UO2 and CeO2 in 2D and 3D. It is shown that the model captures the phenomenon of pore breakaway often observed in experiments. Pores on three- and four- grain junctions were found to transform to edge pores (pores on two-grain junction) before complete separation. The simulations demonstrated that inhomogeneous distribution of pores and pore breakaway lead to abnormal grain growth. The simulations also showed that grain growth kinetics in these materials changes from boundary-controlled to pore-controlled as the amount of porosity increases. The kinetic growth

  20. Abnormal Grain Growth in M-252 and S-816 Alloys

    NASA Technical Reports Server (NTRS)

    Decker, R F; Rush, A I; Dano, A G; Freeman, J W

    1957-01-01

    An experimental investigation was carried out on air- and vacuum-melted M-252 and S-816 alloys to find conditions of heating and hot-working which resulted in abnormal grain growth. The experiments were mainly limited to normal conditions of heating for hot-working and heat treatment and normal temperatures of solution treatment were used to allow grain growth after susceptibility to abnormal grain growth was developed by various experimental conditions. Results indicated that small reductions of essentially strain-free metal were the basic cause of such grain growth.

  1. Jamming of Monodisperse Cylindrical Grains in Featureless Vertical Channels

    NASA Astrophysics Data System (ADS)

    Friedl, Nicholas; Baxter, G. William

    2014-03-01

    We study jamming of low aspect-ratio cylindrical Delrin grains falling through a featureless vertical channel under the influence of gravity. These grains have an aspect-ratio less than two (H/D < 2) and resemble aspirin tablets, 35mm film canisters, poker chips, or coins. Monodisperse grains are allowed to fall under the influence of gravity through a uniform channel of square cross-section where the channel width is greater than the grain size and constant along the length of the channel. No combination of grain heights and diameters is equal to the channel width. Collections of grains sometimes form jams, stable structures in which the grains are supported by the channel walls and not by grains or walls beneath them. The probability of a jam occurring and the jam's strength are influenced by the grain dimensions and channel width. We will present experimental measurements of the jamming probability and jam strength and discuss the relationship of these results to other experiments and theories. Supported by an Undergraduate Research Grant from Penn State Erie, The Behrend College.

  2. Research on electronic states at silicon grain boundaries

    NASA Astrophysics Data System (ADS)

    Werner, J. H.

    1983-02-01

    Electronic states at grain boundaries in artificially grown, boron-doped silicon bicrystals are investigated. The dependence of conductivity and capacitance on temperature, photon energy and density, and frequency of the applied alternating voltage are discussed and quantitatively analyzed. The measurements show that the current transport though the grain boundary is controlled by thermal emission from holes over the grain boundary potential barrier. A formal expression is given for the occupation of interface states in stationary disequilibrium. Measurements of the photoconductivity and photocapacity as a function of light wavelength and intensity are analyzed, and a new spectroscopic method for determining the state density at the grain boundary is developed.

  3. Effects of climate change on US grain transport

    NASA Astrophysics Data System (ADS)

    Attavanich, Witsanu; McCarl, Bruce A.; Ahmedov, Zafarbek; Fuller, Stephen W.; Vedenov, Dmitry V.

    2013-07-01

    The United States is a global grain supplier. Agriculture uses 22% of all US transported tonnage with grain being the largest component. Crop mix shifts are an often cited consequence of climate change and such shifts may change the demands grain places on the transport system. Studies also find that climate change could decrease Great Lakes water levels, shorten the duration of ice cover in the winter and alter grain supplies in grain-exporting countries. This study investigates the effects of such phenomena on US grain transportation movements both in volumes and modes. Specifically we examine the effects of possible shifts in: crop production patterns; Great Lakes water levels; winter navigation possibilities; and foreign grain production. We find that crop mix shifts reduce the importance of Lower Mississippi River ports, but increase the role of Pacific Northwest ports, Great Lakes ports and Atlantic ports. We also find a shift from barge to rail and truck transport. Conversely, a longer navigation season or a reduction in Great Lake water levels increases grain shipments to the ports in the Lower Mississippi River. Higher use of Great Lakes ports occurs under a reduction of grain production in European exporting countries that compete with Great Lakes ports.

  4. In situ studies of grain growth in thin metal films

    SciTech Connect

    Nichols, C.S.; Mansuri, C.M. . Dept. of Materials Science and Engineering); Townsend, S.J. . Dept. of Physics); Smith, D.A. . T.J. Watson Research Center)

    1993-06-01

    Grain growth in thin films of aluminum has been studied using in situ transmission electron microscopy and a heating stage. Videotapes taken during grain growth were analyzed with the intent of searching for the predominant local rearrangement processes responsible for growth. Evolution of a soap froth can be decomposed into only two elementary local topology rearranging events. The authors have found numerous exceptions to prevailing theories that compare grain growth in thin films to the evolution of such froths. These observations suggest that a more complete picture of grain growth is necessary and that such a theory must include more complex local rearrangement processes.

  5. The grain size distribution and the detection of abnormal grain growth of austenite in an eutectoid steel containing niobium

    SciTech Connect

    Bruno, J.C. . Dept. de Engenharia Mecanica e de Materiais); Rios, P.R. . Dept. de Ciencia dos Materiais e Metalurgia)

    1995-02-15

    The abnormal grain growth of austenite was studied in a commercial steel of composition (wt%): 0.70 C, 1.36 Mn, 0.72 Si, 0.015 P, 0.027 S and 0.03 Nb. Specimens were thermocycled at various conditions and then grain size distribution determined. The grain size distribution shape did not change during normal grain growth but this distribution widened and flattened during the abnormal grain growth. The initial smaller mean size of carbonitrides and/or the highest homogeneity of niobium carbonitride size distribution of the samples submitted to thermal cycles, in comparison with the normalized samples, increased the abnormal grain growth temperature from 1,373 K to 1,473 K.

  6. Effects of grain, grain boundary, and dc electric field on giant dielectric response in high purity CuO ceramics

    NASA Astrophysics Data System (ADS)

    Thongbai, Prasit; Maensiri, Santi; Yamwong, Teerapon

    2008-08-01

    Giant dielectric constant ɛ' of ˜(2.8-3.7)×104 was observed in high purity CuO (99.999%) ceramics with grain sizes of 4.57±1.71 and 9.57±3.01 μm. The ɛ' and Ea increase with an increase in grain size due to the different electrical properties in the grains. The high dielectric response observed in the CuO ceramics can be described by the internal barrier layer capacitance model. The resistance of grain boundaries (Rgb) and the dielectric constant of the CuO samples decrease with increasing dc bias due to the decrease in grain boundaries capacitance, whereas the resistance of grains (Rg) remains constant.

  7. Method of aeration disinfecting and drying grain in bulk and pretreating seeds and a transverse blow silo grain dryer therefor

    DOEpatents

    Danchenko, Vitaliy G.; Noyes, Ronald T.; Potapovych, Larysa P.

    2012-02-28

    Aeration drying and disinfecting grain crops in bulk and pretreating seeds includes passing through a bulk of grain crops and seeds disinfecting and drying agents including an ozone and air mixture and surrounding air, subdividing the disinfecting and drying agents into a plurality of streams spaced from one another in a vertical direction, and passing the streams at different heights through levels located at corresponding heights of the bulk of grain crops and seeds transversely in a substantially horizontal direction.

  8. The effects of grain size composition on the efficiency of fine-grained coal separation

    SciTech Connect

    Blahova, O.; Rezek, K.; Novacek, J.

    1994-12-31

    One factor that favorably affects the economics of exploitation and preparation of coal is reducing the loss of coal matter in the tailings from washeries. Thus, it is necessary to modify existing technologies for the preparation of coking coal. This study of the effects of grain size composition for run-of-mine coal on the efficiency of coal separation, as well as on the quality of the products, was performed on the following equipment used for fine-grained coal separation: fine coal jigs (0.5 to 10/15 mm); jigs (0.5 to 40 mm); heavy medium cyclones (0.5 to 10 mm); slurry hydrocyclones (0.0 to 0.5 mm); HIRST hydrocyclones (0.0 to 0.5 mm); and spiral concentrators (0.0 to 3.0 mm). The results of the study lead to the following conclusions. (1) It is impossible to attain efficient separation in a wide range of fine grain sizes processed simultaneously in a single piece of equipment. (2) Among the equipment available for separation, one type can be found with the highest efficiency for a given grain size of fine coal. (3) The newly introduced spiral concentrators have attained such an efficiency of separation and are so economical that they could be included with advantage between the jigs and the lotion process. This would favorably affect the output and the efficiency of separation of all the equipment involved in the process. (4) All measures to be taken in the flow sheet of coal preparation plants and designed to increase the efficiency of separation should be documented with data that show the expected economic benefits of any change for both the mine and the preparation plant.

  9. High night temperatures during grain number determination reduce wheat and barley grain yield: a field study.

    PubMed

    García, Guillermo A; Dreccer, M Fernanda; Miralles, Daniel J; Serrago, Román A

    2015-11-01

    Warm nights are a widespread predicted feature of climate change. This study investigated the impact of high night temperatures during the critical period for grain yield determination in wheat and barley crops under field conditions, assessing the effects on development, growth and partitioning crop-level processes driving grain number per unit area (GN). Experiments combined: (i) two contrasting radiation and temperature environments: late sowing in 2011 and early sowing in 2013, (ii) two well-adapted crops with similar phenology: bread wheat and two-row malting barley and (iii) two temperature regimes: ambient and high night temperatures. The night temperature increase (ca. 3.9 °C in both crops and growing seasons) was achieved using purpose-built heating chambers placed on the crop at 19:000 hours and removed at 7:00 hours every day from the third detectable stem node to 10 days post-flowering. Across growing seasons and crops, the average minimum temperature during the critical period ranged from 11.2 to 17.2 °C. Wheat and barley grain yield were similarly reduced under warm nights (ca. 7% °C(-1) ), due to GN reductions (ca. 6% °C(-1) ) linked to a lower number of spikes per m(2) . An accelerated development under high night temperatures led to a shorter critical period duration, reducing solar radiation capture with negative consequences for biomass production, GN and therefore, grain yield. The information generated could be used as a starting point to design management and/or breeding strategies to improve crop adaptation facing climate change.

  10. High night temperatures during grain number determination reduce wheat and barley grain yield: a field study.

    PubMed

    García, Guillermo A; Dreccer, M Fernanda; Miralles, Daniel J; Serrago, Román A

    2015-11-01

    Warm nights are a widespread predicted feature of climate change. This study investigated the impact of high night temperatures during the critical period for grain yield determination in wheat and barley crops under field conditions, assessing the effects on development, growth and partitioning crop-level processes driving grain number per unit area (GN). Experiments combined: (i) two contrasting radiation and temperature environments: late sowing in 2011 and early sowing in 2013, (ii) two well-adapted crops with similar phenology: bread wheat and two-row malting barley and (iii) two temperature regimes: ambient and high night temperatures. The night temperature increase (ca. 3.9 °C in both crops and growing seasons) was achieved using purpose-built heating chambers placed on the crop at 19:000 hours and removed at 7:00 hours every day from the third detectable stem node to 10 days post-flowering. Across growing seasons and crops, the average minimum temperature during the critical period ranged from 11.2 to 17.2 °C. Wheat and barley grain yield were similarly reduced under warm nights (ca. 7% °C(-1) ), due to GN reductions (ca. 6% °C(-1) ) linked to a lower number of spikes per m(2) . An accelerated development under high night temperatures led to a shorter critical period duration, reducing solar radiation capture with negative consequences for biomass production, GN and therefore, grain yield. The information generated could be used as a starting point to design management and/or breeding strategies to improve crop adaptation facing climate change. PMID:26111197

  11. S–Te Interdiffusion within Grains and Grain Boundaries in CdTe Solar Cells

    SciTech Connect

    Li, C.; Poplawsky, J.; Paudel, N.; Pennycook, T. J.; Haigh, S. J.; Al-Jassim, M. M.; Yan, Y.; Pennycook, S. J.

    2014-09-19

    At the CdTe/CdS interface, a significant Te-S interdiffusion has been found a few nanometers into the grain interiors with scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). S substitution at Te sites has been directly resolved in CdTe with STEM Z-contrast images. Moreover, when enough S substitutes for Te, a structural transformation from zinc-blende to wurtzite has been observed. Cl segregation has also been found at the interface. STEM electron-beam-induced current (EBIC) shows that the p-n junction occurs a few nm into the CdTe grains, which is consistent with the S diffusion range we observe. The shift of the p-n junction suggests a buried homo-junction which would help reduce non-radiative recombination at the junction. Meanwhile, long-range S diffusion in CdTe grain boundaries (GBs) has been detected, as well as Te and Cl diffusion in CdS GBs.

  12. S–Te Interdiffusion within Grains and Grain Boundaries in CdTe Solar Cells

    DOE PAGESBeta

    Li, C.; Poplawsky, J.; Paudel, N.; Pennycook, T. J.; Haigh, S. J.; Al-Jassim, M. M.; Yan, Y.; Pennycook, S. J.

    2014-09-19

    At the CdTe/CdS interface, a significant Te-S interdiffusion has been found a few nanometers into the grain interiors with scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). S substitution at Te sites has been directly resolved in CdTe with STEM Z-contrast images. Moreover, when enough S substitutes for Te, a structural transformation from zinc-blende to wurtzite has been observed. Cl segregation has also been found at the interface. STEM electron-beam-induced current (EBIC) shows that the p-n junction occurs a few nm into the CdTe grains, which is consistent with the S diffusion range we observe. The shiftmore » of the p-n junction suggests a buried homo-junction which would help reduce non-radiative recombination at the junction. Meanwhile, long-range S diffusion in CdTe grain boundaries (GBs) has been detected, as well as Te and Cl diffusion in CdS GBs.« less

  13. 3D reconstruction of grains in polycrystalline materials using a tessellation model with curved grain boundaries

    NASA Astrophysics Data System (ADS)

    Šedivý, Ondřej; Brereton, Tim; Westhoff, Daniel; Polívka, Leoš; Beneš, Viktor; Schmidt, Volker; Jäger, Aleš

    2016-06-01

    A compact and tractable representation of the grain structure of a material is an extremely valuable tool when carrying out an empirical analysis of the material's microstructure. Tessellations have proven to be very good choices for such representations. Most widely used tessellation models have convex cells with planar boundaries. Recently, however, a new tessellation model - called the generalised balanced power diagram (GBPD) - has been developed that is very flexible and can incorporate features such as curved boundaries and non-convexity of cells. In order to use a GBPD to describe the grain structure observed in empirical image data, the parameters of the model must be chosen appropriately. This typically involves solving a difficult optimisation problem. In this paper, we describe a method for fitting GBPDs to tomographic image data. This method uses simulated annealing to solve a suitably chosen optimisation problem. We then apply this method to both artificial data and experimental 3D electron backscatter diffraction (3D EBSD) data obtained in order to study the properties of fine-grained materials with superplastic behaviour. The 3D EBSD data required new alignment and segmentation procedures, which we also briefly describe. Our numerical experiments demonstrate the effectiveness of the simulated annealing approach (compared to heuristic fitting methods) and show that GBPDs are able to describe the structures of polycrystalline materials very well.

  14. Ensembles of gliding grain boundary dislocations in ultrafine grained materials produced by severe plastic deformation

    SciTech Connect

    Nazarov, A.A.

    1997-10-15

    Severe plastic deformation which is now widely used to produce an ultrafine grained (UFG) structure in metals and alloys necessarily leads to the accumulation of interfacial dislocations which arise due to the incompatibilities of strains of neighbor misorientated areas. The most important result of the dislocation storage at grain boundaries (GBs) and associated internal stresses is the fragmentation which at extremely large strains is usually followed by the formation of a very fine highly misorientated granular structure. After deformation the UFG structure must preserve residual dislocation arrays in GBs, since recovery at room temperature is not enough to provide their annihilation. Recently, a hypothesis has been put forward that the internal stresses induced by these arrays are the origin of a number of fundamental properties of UFG materials different from those of coarse grained ones. The author suggested that, in addition, the nonequilibrium dislocation ensembles in GBs were characterized by disordered distribution of dislocations. Thus, three main sources of internal stresses can exist in UFG materials prepared by severe plastic deformation: (1) disordered sessile EGBD arrays, (2) excess density of sessile EGBDs, that is junction disclinations, and (3) arrays of tangential EGBDs. Each of these components can contribute to the experimentally observed elastic strain, excess GB energy and volume expansion in UFG materials.

  15. Grain-damage hysteresis and plate tectonic states

    NASA Astrophysics Data System (ADS)

    Bercovici, David; Ricard, Yanick

    2016-04-01

    Shear localization in the lithosphere is an essential ingredient for understanding how and why plate tectonics is generated from mantle convection on terrestrial planets. The theoretical model for grain-damage and pinning in two-phase polycrystalline rocks provides a frame-work for understanding lithospheric shear weakening and plate-generation, and is consistent with laboratory and field observations of mylonites. Grain size evolves through the competition between coarsening, which drives grain-growth, and damage, which drives grain reduction. The interface between crystalline phases controls Zener pinning, which impedes grain growth. Damage to the interface enhances the Zener pinning effect, which then reduces grain-size, forcing the rheology into the grain-size-dependent diffusion creep regime. This process thus allows damage and rheological weakening to co-exist, providing a necessary positive self-weakening feedback. Moreover, because pinning inhibits grain-growth it promotes shear-zone longevity and plate-boundary inheritance. However, the suppression of interface damage at low interface curvature (wherein inter-grain mixing is inefficient and other energy sinks of deformational work are potentially more facile) causes a hysteresis effect, in which three possible equilibrium grain-sizes for a given stress coexist: (1) a stable, large-grain, weakly-deforming state, (2) a stable, small-grain, rapidly-deforming state analogous to ultramylonites, and (3) an unstable, intermediate grain-size state perhaps comparable to protomylonites. A comparison of the model to field data suggests that shear-localized zones of small-grain mylonites and ultra-mylonites exist at a lower stress than the co-existing large-grain porphyroclasts, rather than, as predicted by paleopiezometers or paleowattmeters, at a much higher stress; this interpretation of field data thus allows localization to relieve instead of accumulate stress. The model also predicts that a lithosphere that

  16. Creep of quartz by dislocation and grain boundary processes

    NASA Astrophysics Data System (ADS)

    Fukuda, J. I.; Holyoke, C. W., III; Kronenberg, A. K.

    2015-12-01

    Wet polycrystalline quartz aggregates deformed at temperatures T of 600°-900°C and strain rates of 10-4-10-6 s-1 at a confining pressure Pc of 1.5 GPa exhibit plasticity at low T, governed by dislocation glide and limited recovery, and grain size-sensitive creep at high T, governed by diffusion and sliding at grain boundaries. Quartz aggregates were HIP-synthesized, subjecting natural milky quartz powder to T=900°C and Pc=1.5 GPa, and grain sizes (2 to 25 mm) were varied by annealing at these conditions for up to 10 days. Infrared absorption spectra exhibit a broad OH band at 3400 cm-1 due to molecular water inclusions with a calculated OH content (~4000 ppm, H/106Si) that is unchanged by deformation. Rate-stepping experiments reveal different stress-strain rate functions at different temperatures and grain sizes, which correspond to differing stress-temperature sensitivities. At 600-700°C and grain sizes of 5-10 mm, flow law parameters compare favorably with those for basal plasticity and dislocation creep of wet quartzites (effective stress exponents n of 3 to 6 and activation enthalpy H* ~150 kJ/mol). Deformed samples show undulatory extinction, limited recrystallization, and c-axis maxima parallel to the shortening direction. Similarly fine-grained samples deformed at 800°-900°C exhibit flow parameters n=1.3-2.0 and H*=135-200 kJ/mol corresponding to grain size-sensitive Newtonian creep. Deformed samples show some undulatory extinction and grain sizes change by recrystallization; however, grain boundary deformation processes are indicated by the low value of n. Our experimental results for grain size-sensitive creep can be compared with models of grain boundary diffusion and grain boundary sliding using measured rates of silicon grain boundary diffusion. While many quartz mylonites show microstructural and textural evidence for dislocation creep, results for grain size-sensitive creep may apply to very fine-grained (<10 mm) quartz mylonites.

  17. Processing of magnesium alloys with ultrafine grain structure

    NASA Astrophysics Data System (ADS)

    Figueiredo, Roberto Braga

    The relationship between processing, structure and properties is analyzed in magnesium alloys subjected to equal-channel angular pressing. Finite element modeling is used to show that the flow softening behavior associated with grain refinement might cause shear localization and billet failure in magnesium alloys processed by ECAP. It also shows that increasing the angle between the channels of the die reduces the accumulated damage in the billets and increasing the material strain rate sensitivity reduces the tendency for shear localization. Both procedures reduce the tendency for billet cracking. The mechanism of grain refinement in magnesium alloys deformed at moderate temperatures differs from that observed in other metals such as copper and aluminum. Fine grains nucleate along pre-existing grain boundaries in a necklace pattern in coarse-grained magnesium while homogeneous nucleation of fine grains is observed in fine-grained. A bimodal grain size distribution is observed after processing alloys from an initial coarse structure and a homogeneous distribution of ultrafine grains is the outcome of a starting fine one. Experiments and simulations are used to analyze the evolution of texture. It is shown that different components are formed depending on the activity ratio of non-basal slip and processing route. The measured pole figures exhibit features characteristic of high activity of non-basal slip. It is also shown that the development of some texture components and their orientation depends on the initial texture and the die angle which provide the basis for future texture engineering. Excellent superplastic properties, including a record elongation for a magnesium alloy, were observed after ECAP. Systematic research showed that the structure characteristics prior and after ECAP play significant role on these properties. Grain growth during superplastic deformation causes a strain hardening effect. The experimental results showed good agreement with the

  18. Grain Unloading of Arsenic Species in Rice1[W

    PubMed Central

    Carey, Anne-Marie; Scheckel, Kirk G.; Lombi, Enzo; Newville, Matt; Choi, Yongseong; Norton, Gareth J.; Charnock, John M.; Feldmann, Joerg; Price, Adam H.; Meharg, Andrew A.

    2010-01-01

    Rice (Oryza sativa) is the staple food for over half the world's population yet may represent a significant dietary source of inorganic arsenic (As), a nonthreshold, class 1 human carcinogen. Rice grain As is dominated by the inorganic species, and the organic species dimethylarsinic acid (DMA). To investigate how As species are unloaded into grain rice, panicles were excised during grain filling and hydroponically pulsed with arsenite, arsenate, glutathione-complexed As, or DMA. Total As concentrations in flag leaf, grain, and husk, were quantified by inductively coupled plasma mass spectroscopy and As speciation in the fresh grain was determined by x-ray absorption near-edge spectroscopy. The roles of phloem and xylem transport were investigated by applying a ± stem-girdling treatment to a second set of panicles, limiting phloem transport to the grain in panicles pulsed with arsenite or DMA. The results demonstrate that DMA is translocated to the rice grain with over an order magnitude greater efficiency than inorganic species and is more mobile than arsenite in both the phloem and the xylem. Phloem transport accounted for 90% of arsenite, and 55% of DMA, transport to the grain. Synchrotron x-ray fluorescence mapping and fluorescence microtomography revealed marked differences in the pattern of As unloading into the grain between DMA and arsenite-challenged grain. Arsenite was retained in the ovular vascular trace and DMA dispersed throughout the external grain parts and into the endosperm. This study also demonstrates that DMA speciation is altered in planta, potentially through complexation with thiols. PMID:19880610

  19. Euhedral metallic-Fe-Ni grains in extraterrestrial samples

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1993-01-01

    Metallic Fe-Ni is rare in terrestrial rocks, being largely restricted to serpentinized peridotites and volcanic rocks that assimilated carbonaceous material. In contrast, metallic Fe-Ni is nearly ubiquitous among extraterrestrial samples (i.e., meteorites, lunar rocks, and interplanetary dust particles). Anhedral grains are common. For example, in eucrites and lunar basalts, most of the metallic Fe-Ni occurs interstitially between silicate grains and thus tends to have irregular morphologies. In many porphyritic chondrules, metallic Fe-Ni and troilite form rounded blebs in the mesostasis because their precursors were immiscible droplets. In metamorphosed ordinary chondrites, metallic Fe-Ni and troilite form coarse anhedral grains. Some of the metallic Fe-Ni and troilite grains has also been mobilized and injected into fractures in adjacent silicate grains where local shock-reheating temperatures reached the Fe-FeS eutectic (988 C). In interplanetary dust particles metallic Fe-Ni most commonly occurs along with sulfide as spheroids and fragments. Euhedral metallic Fe-Ni grains are extremely rare. Several conditions must be met before such grains can form: (1) grain growth must occur at free surfaces, restricting euhedral metallic Fe-Ni grains to systems that are igneous or undergoing vapor-deposition; (2) the metal (+/-) sulfide assemblage must have an appropriate bulk composition so that taenite is the liquidus phase in igneous systems or the stable condensate phase in vapor-deposition systems; and (3) metallic Fe-Ni grains must remain underformed during subsequent compaction, thermal metamorphism, and shock. Because of these restrictions, the occurrence of euhedral metallic Fe-Ni grains in an object can potentially provide important petrogenetic information. Despite its rarity, euhedral metallic Fe-Ni occurs in a wide variety of extraterrestrial materials. Some of these materials formed in the solar nebula; others formed on parent body surfaces by meteoroid

  20. Laboratory Studies Of Circumstellar Carbonaceous Grain Formation

    NASA Astrophysics Data System (ADS)

    Contreras, Cesar; Sciamma-O'Brien, Ella; Salama, Farid

    2014-06-01

    The study of the formation processes of dust is essential to understand the budget of extraterrestrial organic molecules. Although dust with all its components plays an important role in the evolution of interstellar (IS) chemistry and in the formation of organic molecules, little is known on the formation processes of carbonaceous dust. We report the progress that was recently achieved in this domain using NASA Ames’ COSmIC facility (Contreras & Salama 2013, ApJS, 208, 6). PAHs are important chemical building blocks of IS dust. They are detected in IDPs and in meteoritic samples. Additionally, observational, laboratory, and theoretical studies have shown that PAHs are an important, ubiquitous component of the ISM. The formation of PAHs from smaller molecules has not been extensively studied. Therefore, we have performed laboratory experiments to study the dynamic processes of carbon grain formation, starting from the smallest hydrocarbon molecules into the formation of larger PAH and further into nanograins. Studies of IS dust analogs formed from a variety of PAH and hydrocarbon precursors as well as species that include the atoms O, N, and S, have recently been performed in our laboratory using the COSmIC facility to provide conditions that simulate IS and circumstellar environments. The species formed in the COSmiC chamber through a pulsed discharge nozzle plasma source are detected and characterized with a cavity ringdown spectrometer coupled to a time-of-flight mass spectrometer, thus providing both spectroscopic and ion mass information in-situ. Analysis of solid soot particles was also conducted using scanning electron microscopy at the UCSC/NASA Ames’ MACS facility. The SEM analysis of the deposition of soot from methane and acetylene precursors seeded in argon plasmas provide examples on the types of nanoparticles and micrograins that are produced in these gas mixtures under our experimental conditions. From these measurements, we derive information on

  1. Ultrastructural Study of Some Pollen Grains of Prairie Flowers

    ERIC Educational Resources Information Center

    Kozar, Frank

    1973-01-01

    Discusses the importance of the electron microscope, and in particular the scanning electron microscope, in studying the surface topography, sectional substructures, and patterns of development of pollen grains. The production, dispersal methods, and structure of pollen grains are described and illustrated with numerous electron micrographs. (JR)

  2. Dust Coagulation in Infalling Protostellar Envelopes I. Compact Grains

    NASA Technical Reports Server (NTRS)

    Yorke, H.; Suttner, G.; Lin, D.

    1999-01-01

    Dust plays a key role in the optical, thermodynamic and gas dynamical behavior of collapsing molecular cores. Because of relative velocities of the individual dust grains, coagulation and shattering can modify the grain size distribution and due to corresponding changes in the medium's opacity significantly influence the evolution during early phase of star formation.

  3. Dust Coagulation in Infalling Protostellar Envelopes I. Compact Grains

    NASA Technical Reports Server (NTRS)

    Yorke, H.; Lin, D.; Suttner, G.

    1999-01-01

    Dust plays a key role in the optical, thermodynamic and gas dynamical behavior of collapsing molecular cores. Because of relative velocities of the individual dust grains, coagulation and shattering can modify the grain size distribution and -- due to corresponding changes in the medium's opacity significantly -- influence the evolution during early phases of star formation.

  4. 13. Interior view, grain tanks (bins). Barrel view of overhead ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. Interior view, grain tanks (bins). Barrel view of overhead (fill) conveyor gallery bridge extending through tops of tanks just below roofs. Grain tripper straddles belt conveyor at mid-view. - Saint Anthony Elevator No. 3, 620 Malcom Avenue, Southeast, Minneapolis, Hennepin County, MN

  5. 13. TWOSHOT PANORAMIC VIEW OF EAST TERMINAL PIER, GRAIN ELEVATOR, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. TWO-SHOT PANORAMIC VIEW OF EAST TERMINAL PIER, GRAIN ELEVATOR, AND GRAIN GALLERIES AT OFFICIAL OPENING OF TERMINAL, September l, 1922 (Original negative destroyed; print in Barge Canal Construction Photographs, Box 12, Series 501, Accession No. 336-85) - New York Barge Canal, Gowanus Bay Terminal Pier, East of bulkhead supporting Columbia Street, Brooklyn, Kings County, NY

  6. 26. GRAINELEVATOR SECTION, SECOND FLOOR, INTERIOR, DETAIL OF GRAIN CRIB ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. GRAIN-ELEVATOR SECTION, SECOND FLOOR, INTERIOR, DETAIL OF GRAIN CRIB FRAMING; ELECTRICAL EQUIPMENT IS MOUNTED ON WHAT WAS ONCE THE INTERIOR OF BIN NUMBER NINE; LOOKING SOUTHEAST - Standard Mill, 116-118 Portland Avenue South, Minneapolis, Hennepin County, MN

  7. Exploring the Use of Whole Grain Pasta in School Lunches

    ERIC Educational Resources Information Center

    Rosen, Renee A.; Hauge, Denise A.; Arndt, Elizabeth A.; Veal, Mike; Marquart, Len

    2011-01-01

    Pasta is a popular grain food served as an entree or side dish in both home and away-from-home settings. In schools, pasta is served less frequently than other entrees. Pasta, especially whole-grain pasta, offers an opportunity to incorporate less expensive, nutritious, and versatile dishes into school meals. A need exists to develop whole-grain…

  8. 13. INTERIOR VIEW, FIRST FLOOR SHOWING THE ELEVATORS FEEDING GRAIN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. INTERIOR VIEW, FIRST FLOOR SHOWING THE ELEVATORS FEEDING GRAIN FROM THE SECOND FLOOR TO THE GRINDING STONES, WITH GRAIN ELEVATORS IN BACKGROUND (NOTE OUTLINE ON THE FLOOR WHERE ROLLER MILLS WERE ORIGINALLY PLACED) - Schech's Mill, Beaver Creek State Park, La Crescent, Houston County, MN

  9. Modeling the flow properties of distillers dried grains with solubles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Distillers dried grains with solubles (DDGS) are an excellent source of energy, minerals, and bypass protein for ruminants, and are also used in monogastric rations as well. With the remarkable growth of the US fuel ethanol industry in the past decade, large quantities of distillers grains are now b...

  10. Isotopic Composition of Barium in Single Presolar Silicon Carbide Grains

    NASA Technical Reports Server (NTRS)

    Savina, M. R.; Tripa, C. E.; Pellin, M. J.; Davis, A. M.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2002-01-01

    We have measured Ba isotope distributions in individual presolar SiC grains. We find that the Ba isotopic composition in mainstream SiC grains is consistent with models of nucleosynthesis in low to intermediate mass asymptotic giant branch (AGB) stars. Additional information is contained in the original extended abstract.

  11. Modelling grain growth in the framework of Rational Extended Thermodynamics

    NASA Astrophysics Data System (ADS)

    Kertsch, Lukas; Helm, Dirk

    2016-05-01

    Grain growth is a significant phenomenon for the thermomechanical processing of metals. Since the mobility of the grain boundaries is thermally activated and energy stored in the grain boundaries is released during their motion, a mutual interaction with the process conditions occurs. To model such phenomena, a thermodynamic framework for the representation of thermomechanical coupling phenomena in metals including a microstructure description is required. For this purpose, Rational Extended Thermodynamics appears to be a useful tool. We apply an entropy principle to derive a thermodynamically consistent model for grain coarsening due to the growth and shrinkage of individual grains. Despite the rather different approaches applied, we obtain a grain growth model which is similar to existing ones and can be regarded as a thermodynamic extension of that by Hillert (1965) to more general systems. To demonstrate the applicability of the model, we compare our simulation results to grain growth experiments in pure copper by different authors, which we are able to reproduce very accurately. Finally, we study the implications of the energy release due to grain growth on the energy balance. The present unified approach combining a microstructure description and continuum mechanics is ready to be further used to develop more elaborate material models for complex thermo-chemo-mechanical coupling phenomena.

  12. GrainGenes: Changing Times, Changing Databases, Digital Evolution.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The GrainGenes database is one of few agricultural databases that had an early start on the Internet and that has changed with the times. Initial goals were to collect a wide range of data relating to the developing maps and attributes of small grains crops, and to make them easily accessible. The ...

  13. 12. From here grain goes to the top of the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. From here grain goes to the top of the tower from rail cars down below. From here grain flows by gravity through different processes ending up as beer in the basement. - Tivoli-Union Brewery, 1320-1348 Tenth Street, Denver, Denver County, CO

  14. 14. Interior view, grain tanks (bins). Barrel view of tunnel ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Interior view, grain tanks (bins). Barrel view of tunnel for load-out belt conveyor system located below tanks. Square, numbered spouts gravity-feed grain from overhead bins onto belt. - Saint Anthony Elevator No. 3, 620 Malcom Avenue, Southeast, Minneapolis, Hennepin County, MN

  15. Field measurements for food grain packing factors in US

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain is commonly stored in tall bins, often exceeding 30 m deep, in commercial storage facilities. Grain can support the large overbearing pressure without crushing; however, it yields somewhat to compaction due to the overbearing pressure leading to an increase in bulk density and change in volume...

  16. Antioxidant Activity of Phytochemicals from Dried Distillers Grain Oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A distillate was obtained by molecular distillation of oil extracted from distiller’s dried grains (DDG). The dried distiller’s grains distillate (DDGD) contained phytosterols, steryl ferulates, tocopherols, tocotrienols, and carotenoids. DDGD was tested for its impact on the oxidative stability i...

  17. Antioxidant activity of phytochemicals from dried distillers grain oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A distillate was obtained by molecular distillation of oil extracted from distiller’s dried grains (DDG). The dried distiller’s grains distillate (DDGD) contained phytosterols, steryl ferulates, tocopherols, tocotrienols, and carotenoids. DDGD was tested for its impact on the oxidative stability in...

  18. Polyphenols and antioxidant capacity: Rice versus other common cereal grains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The consumption of whole cereal grains has been strongly recommended by many governmental and non-profit health organizations based on epidemiological studies associating whole-grain consumption with reduced incidences of chronic diseases. Bioactive phytochemicals, such as polyphenolic compounds, ri...

  19. Energy regimes for aeolian sand grain surface textures

    NASA Astrophysics Data System (ADS)

    Marshall, J. R.; Bull, P. A.; Morgan, R. M.

    2012-05-01

    An experimental study of aeolian sand grain surface texture development was undertaken with an air-driven grain-recirculating desktop apparatus. Scanning electron microscope analysis of resulting textures indicated that different texture types can be associated with distinct zones in a grain-shape/grain speed matrix. In particular, for subrounded and rounded grains, low and high energy transport can be unequivocally distinguished by the occurrence of upturned plates and Hertzian frustra respectively. Textural development does not have a simple relationship to grain velocity, but appears to relate to the energy expended per unit area within the contact zone generated by elastic deformation during impact. Hertzian theory was adapted to irregular sand grain shapes and close agreement was found between experimental results and theoretical predictions for textural development. Results of this study improve our ability to reconstruct palaeoaeolian environments and therefore our ability to determine grain provenance; in particular, the latter is shown to have direct relevance to forensic inquiries and terrorism investigations.

  20. 78 FR 58383 - Renewal of National Grain Car Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-23

    ... Surface Transportation Board Renewal of National Grain Car Council AGENCY: Surface Transportation Board... Board intends to renew the charter of the National Grain Car Council (NGCC). ADDRESSES: A copy of the... 14 members from the Class I railroads (one marketing and one car management representative from...

  1. 76 FR 59186 - Renewal of National Grain Car Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-23

    ... Surface Transportation Board Renewal of National Grain Car Council AGENCY: Surface Transportation Board... Board intends to renew the charter of the National Grain Car Council (NGCC). ADDRESSES: A copy of the... marketing and one car management representative from each Class I), 7 representatives from Class II and...

  2. Genetic Potential of Winter Wheat Grain Quality in Central Asia

    ERIC Educational Resources Information Center

    Abugaliyeva, Aigul I.; Morgounov, Alexey I.

    2016-01-01

    The grain quality of winter wheat varies significantly by cultivars and growing region, not previously differentiated by end-use (baking, confectionery, etc.) in the national breeding programs. In these conditions it is advisable to determine the genetic potential and analyze the actual grain quality. Determining the genetic potential requires the…

  3. Investigation of light scattering on a single dust grain

    NASA Astrophysics Data System (ADS)

    Pavlu, Jiri; Nemecek, Zdenek; Safrankova, Jana; Barton, Petr

    2016-07-01

    Complex phenomenon of light scattering by dust grains plays an important role in all dust--light interactions, especially in space, e.g., light passing through dense dusty clouds in the space as well as in the upper atmosphere, dust charging by photoemission, etc. When the wavelength of the incident light is about the size of the grain, the Mie theory is often used to characterize the scattering process. Unfortunately, we have only very limited knowledge of necessary material constants for most of the space-related materials and also the solution of Mie equations for general grain shapes is difficult or unknown. We develop an apparatus for observations of light scattering on small (micrometer-sized) arbitrary shaped dust grains. We directly measure the scattering by levitating grains in the field created by the standing-wave ultrasonic trap, where we can study single grains or small grain clusters. The experiment is performed at atmospheric air --- unlike other experiments, where grains were measured in water or other liquids. Therefore, the background effects are significantly reduced. Currently, the trap is under development and first tests are carried out. Besides initial results, we focus on theoretical computations of the ultrasonic field of the selected trap.

  4. GRAIN SORTING IN COMETARY DUST FROM THE OUTER SOLAR NEBULA

    SciTech Connect

    Wozniakiewicz, P. J.; Bradley, J. P.; Ishii, H. A.; Brownlee, D. E.; Kearsley, A. T.; Burchell, M. J.; Price, M. C.

    2012-12-01

    Most young stars are surrounded by a disk of gas and dust. Close to the hot stars, amorphous dust grains from the parent molecular cloud are reprocessed into crystals that are then distributed throughout the accretion disk. In some disks, there is a reduction in crystalline grain size with heliocentric distance from the star. We investigated crystalline grain size distributions in chondritic porous (CP) interplanetary dust particles (IDPs) believed to be from small, icy bodies that accreted in outer regions of the solar nebula. The grains are Mg-rich silicates and Fe-rich sulfides, the two most abundant minerals in CP IDPs. We find that they are predominantly <0.25 {mu}m in radius with a mean grain size that varies from one CP IDP to another. We report a size-density relationship between the silicates and sulfides. A similar size-density relationship between much larger silicate and sulfide grains in meteorites from the asteroid belt is ascribed to aerodynamic sorting. Since the silicate and sulfide grains in CP IDPs are theoretically too small for aerodynamic sorting, their size-density relationship may be due to another process capable of sorting small grains.

  5. Economic Perspectives on Organic Grains: Past, Present, and Future

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The organic food industry has seen tremendous growth over the past decade. This growth has led to an increase in demand for organic grains, and has been accompanied by an increase in the number of organic farms and an expansion in organic grain acreage in the U.S. Through this period, price premium...

  6. Presolar grains in the CM2 chondrite Sutter's Mill

    NASA Astrophysics Data System (ADS)

    Zhao, Xuchao; Lin, Yangting; Yin, Qing-Zhu; Zhang, Jianchao; Hao, Jialong; Zolensky, Michael; Jenniskens, Peter

    2014-11-01

    The Sutter's Mill (SM) carbonaceous chondrite is a regolith breccia, composed predominantly of CM2 clasts with varying degrees of aqueous alteration and thermal metamorphism. An investigation of presolar grains in four Sutter's Mill sections, SM43, SM51, SM2-4, and SM18, was carried out using NanoSIMS ion mapping technique. A total of 37 C-anomalous grains and one O-anomalous grain have been identified, indicating an abundance of 63 ppm for presolar C-anomalous grains and 2 ppm for presolar oxides. Thirty-one silicon carbide (SiC), five carbonaceous grains, and one Al-oxide (Al2O3) were confirmed based on their elemental compositions determined by C-N-Si and O-Si-Mg-Al isotopic measurements. The overall abundance of SiC grains in Sutter's Mill (55 ppm) is consistent with those in other CM chondrites. The absence of presolar silicates in Sutter's Mill suggests that they were destroyed by aqueous alteration on the parent asteroid. Furthermore, SM2-4 shows heterogeneous distributions of presolar SiC grains (12-54 ppm) in different matrix areas, indicating that the fine-grained matrix clasts come from different sources, with various thermal histories, in the solar nebula.

  7. A meteorologically driven grain sorghum stress indicator model

    NASA Technical Reports Server (NTRS)

    Taylor, T. W.; Ravet, F. W. (Principal Investigator)

    1981-01-01

    A grain sorghum soil moisture and temperature stress model is described. It was developed to serve as a meteorological data filter to alert commodity analysts to potential stress conditions and crop phenology in selected grain sorghum production areas. The model also identifies optimum conditions on a daily basis and planting/harvest problems associated with poor tractability.

  8. Selecting soft wheat genotypes for whole grain cookies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved nutrition and reduction in obesity for North American populations require increasing the dietary use of whole grain cereal products. In most snack foods, whole grain products are difficult to manufacture because the presence of bran increases the water absorption and decreases the baking q...

  9. Enhancing the health-beneficial qualities of whole grain rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Various pre- and post-harvest approaches (i.e. pre-germination of whole grains and reduced milling degree) to enhancing the health beneficial compounds of whole grain and milled rice have been reported. A discussion of the results from our pre-harvest efforts is as follows. The majority of rice cons...

  10. Estimating the effect of fermentation yeast on distillers grains protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Distillers dried grains with solubles (DDGS) is the key co-product of bio-ethanol production from grains. Major factors affecting its quality and market values include protein quantity (concentration) and quality (amino acid composition). Yet, the effect of fermentation yeast on DDGS quality has no...

  11. Whole grain gluten-free pastas and flatbreads

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole grain gluten-free products were formulated and evaluated for acceptance by volunteer tasters. The tastes judged acceptance of whole grain, gluten-free, egg-free pastas for corn 83%, sorghum 79%, brown rice 77% and millet 50%. The acceptance for similar high protein pasta was corn-garbanzo 70...

  12. Pack Factor Measurementss for Corn in Grain Storage Bins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain is commonly stored commercially in tall bins, which often are as deep as 35 m (114.8 ft) for tall and narrow concrete bins and about 32 m (105 ft) in diameter for large corrugated steel bins. Grain can support the great pressure without crushing, but it yields somewhat to compaction under its ...

  13. Managing grain protein content by remote sensing in winter wheat

    NASA Astrophysics Data System (ADS)

    Huang, Wenjiang; Wang, Jihua; Song, Xiaoyu; Zhao, Chunjiang; Liu, Liangyun

    2007-10-01

    Advanced site-specific determination of grain protein content by remote sensing can provide opportunities to optimize the strategies for purchasing and pricing grain, and to maximize the grain output by adjusting field inputs. Field experiments were performed to study the relationship between grain quality indicators and foliar nitrogen concentration. Foliar nitrogen concentration at the anthesis stage is suggested to be significantly correlated with grain protein content, while spectral vegetation index is significantly correlated to foliar nitrogen concentration around the anthesis stage. Based on the relationships among nitrogen reflectance index (NRI), foliar nitrogen concentration, and grain protein content, a statistical evaluation model of grain protein content was developed. NRI proved to be able to evaluate foliar nitrogen concentration with a coefficient of determination of R2= 0.7302 in year 2002. The relationship between measured and remote sensing derived foliar nitrogen concentration had a coefficient of determination of R2=0.7279 in year 2003. The results mentioned above indicate that the inversion of foliar nitrogen concentration and the evaluation of grain protein content by NRI are surprisingly good.

  14. Grain and Flour Characterization of Four Different Sorghum Varieties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With an increasing number of people with celiac disease, the need for gluten-free products is on the rise. Sorghum is a grain tolerated by celiac patients which can be used in gluten-free foods. The grain and flour of four sorghum varieties were characterized through physical and chemical means. ...

  15. A Madurella mycetomatis Grain Model in Galleria mellonella Larvae

    PubMed Central

    Kloezen, Wendy; van Helvert-van Poppel, Marilyn; Fahal, Ahmed H.; van de Sande, Wendy W. J.

    2015-01-01

    Eumycetoma is a chronic granulomatous subcutaneous infectious disease, endemic in tropical and subtropical regions and most commonly caused by the fungus Madurella mycetomatis. Interestingly, although grain formation is key in mycetoma, its formation process and its susceptibility towards antifungal agents are not well understood. This is because grain formation cannot be induced in vitro; a mammalian host is necessary to induce its formation. Until now, invertebrate hosts were never used to study grain formation in M. mycetomatis. In this study we determined if larvae of the greater wax moth Galleria mellonella could be used to induce grain formation when infected with M. mycetomatis. Three different M. mycetomatis strains were selected and three different inocula for each strain were used to infect G. mellonella larvae, ranging from 0.04 mg/larvae to 4 mg/larvae. Larvae were monitored for 10 days. It appeared that most larvae survived the lowest inoculum, but at the highest inoculum all larvae died within the 10 day observation period. At all inocula tested, grains were formed within 4 hours after infection. The grains produced in the larvae resembled those formed in human and in mammalian hosts. In conclusion, the M. mycetomatis grain model in G. mellonella larvae described here could serve as a useful model to study the grain formation and therapeutic responses towards antifungal agents in the future. PMID:26173126

  16. Strategic Regulation of Grain Size in Memory Reporting over Time

    ERIC Educational Resources Information Center

    Goldsmith, M.; Koriat, A.; Pansky, A.

    2005-01-01

    As time passes, people often remember the gist of an event though they cannot remember its details. Can rememberers exploit this difference by strategically regulating the ''grain size'' of their answers over time, to avoid reporting wrong information? A metacognitive model of the control of grain size in memory reporting was examined in two…

  17. Use of distiller's dried grains with solubles in tilapia diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Distiller’s dried grains with solubles (DDGS) are currently readily available and less expensive than other conventional protein sources. However, its nutrient content and nutritional value vary with the source and quality of grain, fermentation and drying processes and the quantity of distiller’s s...

  18. Fall Growth Potential of Cereal Grain Forages in Northern Arkansas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Arkansas, producers utilizing cereal grains as fall forage for weaned calves usually do not harvest a grain crop the following summer. This contrasts sharply from practices observed commonly in neighboring Oklahoma, and allows for much wider latitude with respect to management strategies, especia...

  19. Fall Growth Potential of Cereal-Grain Forages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Arkansas, producers utilizing cereal grains as fall forage for weaned calves usually do not produce a grain crop the following summer. Our objectives were to evaluate eight diverse varieties of wheat (Triticum aestivum L.), oat (Avena sativa L.), rye (Secale cereale L.), and triticale (X Triticos...

  20. Does Whole Grain Consumption Alter Gut Microbiota and Satiety?

    PubMed Central

    Cooper, Danielle N.; Martin, Roy J.; Keim, Nancy L.

    2015-01-01

    This review summarizes recent studies examining whole grain consumption and its effect on gut microbiota and satiety in healthy humans. Studies comparing whole grains to their refined grain counterparts were considered, as were studies comparing different grain types. Possible mechanisms linking microbial metabolism and satiety are described. Clinical trials show that whole grain wheat, maize, and barley alter the human gut microbiota, but these findings are based on a few studies that do not include satiety components, so no functional claims between microbiota and satiety can be made. Ten satiety trials were evaluated and provide evidence that whole oats, barley, and rye can increase satiety, whereas the evidence for whole wheat and maize is not compelling. There are many gaps in the literature; no one clinical trial has examined the effects of whole grains on satiety and gut microbiota together. Once understanding the impact of whole grains on satiety and microbiota is more developed, then particular grains might be used for better appetite control. With this information at hand, healthcare professionals could make individual dietary recommendations that promote satiety and contribute to weight control. PMID:27417768