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Sample records for active grain density

  1. Oat Grain Density and the Physical Basis of Test Weight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Test weight or bulk density of oats (Avena sativa L.) has a major influence on the monetary value of oat grain. Test weight can be attributed to grain density and packing efficiency. We have measured oat grain volume and density by a sand displacement method and thus derived the packing factor for s...

  2. 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

  3. 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.

  4. 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

  5. Reducing the graphene grain density in three steps.

    PubMed

    Hsieh, Ya-Ping; Chu, Yi-Hung; Tsai, He-Guang; Hofmann, Mario

    2016-03-11

    The production of large-scale, single crystalline graphene is a requirement for enhancing its electronic, mechanical, and chemical properties. Chemical vapor deposition (CVD) has shown the potential to grow high quality graphene but the simultaneous nucleation of many grains limits their achievable domain size. We report here that ultralow nucleation densities can be achieved through multi-step optimization of the catalyst morphology. First, annealing in a hydrogen-free environment is required to retain a surface copper oxide which decreases the nucleation density. Second, CuO was found to be the relevant copper species for this process and air oxidation of the copper foil at 200 °C maximizes its concentration. Both pre-treatment steps were found to affect the morphology of the catalyst and a direct correlation between nucleation density and surface roughness was found which indicates that the primary role of the oxidation step is the decrease in catalyst roughness. To further enhance this determining parameter, confined CVD was carried out after sample oxidation and hydrogen-free annealing. Each of these three steps reduces the grain density by approximately one order of magnitude resulting in ultralow nucleation densities of 1.23 grains/mm(2) and high quality, single-crystalline graphene grains of several millimeter sizes were grown using this method. PMID:26861850

  6. Reducing the graphene grain density in three steps

    NASA Astrophysics Data System (ADS)

    Hsieh, Ya-Ping; Chu, Yi-Hung; Tsai, He-Guang; Hofmann, Mario

    2016-03-01

    The production of large-scale, single crystalline graphene is a requirement for enhancing its electronic, mechanical, and chemical properties. Chemical vapor deposition (CVD) has shown the potential to grow high quality graphene but the simultaneous nucleation of many grains limits their achievable domain size. We report here that ultralow nucleation densities can be achieved through multi-step optimization of the catalyst morphology. First, annealing in a hydrogen-free environment is required to retain a surface copper oxide which decreases the nucleation density. Second, CuO was found to be the relevant copper species for this process and air oxidation of the copper foil at 200 °C maximizes its concentration. Both pre-treatment steps were found to affect the morphology of the catalyst and a direct correlation between nucleation density and surface roughness was found which indicates that the primary role of the oxidation step is the decrease in catalyst roughness. To further enhance this determining parameter, confined CVD was carried out after sample oxidation and hydrogen-free annealing. Each of these three steps reduces the grain density by approximately one order of magnitude resulting in ultralow nucleation densities of 1.23 grains/mm2 and high quality, single-crystalline graphene grains of several millimeter sizes were grown using this method.

  7. Measuring track densities in lunar grains using image analysis

    NASA Technical Reports Server (NTRS)

    Blanford, G. E.; Mckay, D. S.; Bernhard, R. P.; Schulz, C. K.

    1994-01-01

    We have used digitized scanning electron micrographs and computer image analysis programs to measure track densities in lunar soil grains. Tracks were formed by highly ionizing solar energetic particles and cosmic rays. Back-scattered electron images produced suitable high contrast images for analysis. We used computer counting and measurement of area to obtain track densities. We found an excellent correlation with manual measurements for track densities below 1x10(exp 8) cm(exp -2). For track densities between 1x10(exp 8) to 1x10(exp 9) cm(exp -2) we found that a regression formula using the percentage area covered by tracks gave good agreement with manual measurements. Measurement of tract densities in lunar samples has been a very rewarding technique for measuring exposure ages and soil maturation processes. We have shown that we can reliably measure track densities in lunar grains using image analysis techniques. Automating track counting may allow application of this technique to important problems in regolith dynamics including the ratio of radiation exposure to reworking in various surface and core samples and in regolith breccias.

  8. Measuring track densities in lunar grains by image analysis

    NASA Technical Reports Server (NTRS)

    Blanford, George E.

    1993-01-01

    We have developed techniques to use digitized scanning electron micrographs and computer image analysis programs to measure track densities in lunar soil grains. Tracks were formed by highly ionizing solar energetic particles and cosmic rays during near surface exposure on the Moon. The track densities are related to the exposure conditions (depth and time). Distributions of the number of grains as a function of their track densities can reveal the modality of soil maturation. We used a sample that had already been etched in 6 N NaOH at 118 C for 15 h to reveal tracks. We determined that back-scattered electron images taken at 50 percent contrast and approximately 49.8 percent brightness produced suitable high contrast images for analysis. We ascertained gray-scale thresholds of interest: 0-230 for tracks, 231 for masked regions, and 232-255 for background. We found no need to set an upper size limit for distinguishing tracks. We did use lower limits to exclude noise: 16 pixels at 15000x, 4 pixels at 10000x, 2 pixels at 6800x, and 0 pixels at 4600x. We used computer counting and measurement of area to obtain track densities. We found an excellent correlation with manual measurements for track densities below 1x10(exp 8) sq cm. For track densities between 1x10(exp 8) sq cm to 1x10(exp 9) sq cm, we found that a regression formula using the percentage area covered by tracks gave good agreement with manual measurements. Finally we used these new techniques to obtain a track density distribution that gave more detail and was more rapidly obtained than using manual techniques 15 years ago.

  9. Modeling the effect of grain size and dislocation density on hysteretic magnetic properties in steels

    NASA Astrophysics Data System (ADS)

    Sablik, M. J.

    2001-05-01

    In this article, the Jiles-Atherton model is modified to elucidate the variation of magnetic properties with grain size and dislocation density. The modified model predicts generally that coercive field increases with increasing dislocation density and inverse grain size and that remanent flux density and permeability at the coercive field decrease with increasing dislocation density and inverse grain size. Using the same model, it should be possible to model the effects of grain size and dislocation density on other magnetic measurements such as nonlinear harmonics of the flux density or Barkhausen noise.

  10. Effects of grain size and grain boundary on critical current density of high T(sub c) superconducting oxides

    NASA Technical Reports Server (NTRS)

    Zhao, Y.; Zhang, Q. R.; Zhang, H.

    1990-01-01

    By means of adding impurity elements in high T sub c oxides, the effects were studied of grain size and grain boundary on the critical current density of the following systems: YBa2Cu3O(7-y) and Bi-Pr-Sr-Ca-Cu-O. In order to only change the microstructure instead of the superconductivity of the grains in the samples, the impurity elements were added into the systems in terms of the methods like this: (1) substituting Y with the lanthanide except Pr, Ce, and Tb in YBa2Cu3O(7-y) system to finning down grains in the samples, therefore, the effect can be investigated of the grain size on the critical current density of 1:2:3 compounds; (2) mixing the high T sub c oxides with the metal elements, such as Ag, according to the composition of (high T sub c oxide)1-xAgx to metallize the grain boundaries in the samples, studying the effect of the electric conductivity of the grain boundaries on the critical current density; (3) adding SiO2, PbO2, and SnO2 into the high T sub c oxide to form impurity phases in the grain boundaries, trying to find out the effects of the impurity phases or metalloid grain boundaries on the critical current density of the high T sub c superconductors. The experimental results indicate that in the case of of the presence of the metalloid grain boundaries finning down grains fails to enhance the j sub c, but restrains it strongly, the granular high T sub c superconductors with the small size grains coupled weakly is always the low j sub c system.

  11. Quantitative grain density autoradiography and the intraspecific distribution of primary productivity in phytoplankton

    SciTech Connect

    Davenport, J.B.; Maguire, B. Jr.

    1984-03-01

    Analysis of a method of grain density autoradiography demonstrates that reliable measurements of the primary productivity of individual phytoplankton species can be obtained with this technique. Grain density autoradiography is particularly useful for providing an estimate of the intraspecific distribution of primary productivity. As an example, the productivity distribution of the marine diatom Chaetoceros curvisetus became positively skewed during a period of population decline.

  12. Analysis of defect structure in silicon. Effect of grain boundary density on carrier mobility in UCP material

    NASA Technical Reports Server (NTRS)

    Dunn, J.; Stringfellow, G. B.; Natesh, R.

    1982-01-01

    The relationships between hole mobility and grain boundary density were studied. Mobility was measured using the van der Pauw technique, and grain boundary density was measured using a quantitative microscopy technique. Mobility was found to decrease with increasing grain boundary density.

  13. Modeling grain size and dislocation density effects on harmonics of the magnetic induction

    SciTech Connect

    Sablik, M. J.; Stegemann, D.; Krys, A.

    2001-06-01

    Microstructural attributes of steels affect hysteretic magnetic properties because the microstructure affects domain wall movement and pinning. Two important features are grain size and dislocation density. The consensus experimentally is that the coercivity tends to be linearly related to the inverse of the average grain diameter and to the square root of the dislocation density. In this article, these experimental tendencies are utilized in formulating the dependence of the hysteresis parameters of the Jiles{endash}Atherton model as a function of grain size and dislocation density. The results are then used in computing the first and third harmonics of the magnetic induction as a function of grain size and dislocation density. This is done via an adaptation of a hysteresis model formulated by Jiles for higher excitation frequencies. The results indicate that the harmonic amplitudes decrease monotonically with inverse grain size and the square root of dislocation density. Since increasing inverse grain size and dislocation density are correlated with increasing tensile strength, the results are consistent with experimental results for the decrease of the harmonic amplitudes with increasing tensile strength in automotive steels. Also, the harmonic amplitudes decrease with increasing excitation frequency, consistent with experiment. {copyright} 2001 American Institute of Physics.

  14. Modeling grain size and dislocation density effects on harmonics of the magnetic induction

    NASA Astrophysics Data System (ADS)

    Sablik, M. J.; Stegemann, D.; Krys, A.

    2001-06-01

    Microstructural attributes of steels affect hysteretic magnetic properties because the microstructure affects domain wall movement and pinning. Two important features are grain size and dislocation density. The consensus experimentally is that the coercivity tends to be linearly related to the inverse of the average grain diameter and to the square root of the dislocation density. In this article, these experimental tendencies are utilized in formulating the dependence of the hysteresis parameters of the Jiles-Atherton model as a function of grain size and dislocation density. The results are then used in computing the first and third harmonics of the magnetic induction as a function of grain size and dislocation density. This is done via an adaptation of a hysteresis model formulated by Jiles for higher excitation frequencies. The results indicate that the harmonic amplitudes decrease monotonically with inverse grain size and the square root of dislocation density. Since increasing inverse grain size and dislocation density are correlated with increasing tensile strength, the results are consistent with experimental results for the decrease of the harmonic amplitudes with increasing tensile strength in automotive steels. Also, the harmonic amplitudes decrease with increasing excitation frequency, consistent with experiment.

  15. High-Density Amorphous Ice, the Frost on Interstellar Grains

    NASA Technical Reports Server (NTRS)

    Jenniskens, P.; Blake, D. F.; Wilson, M. A.; Pohorille, A.

    1995-01-01

    Most water ice in the universe is in a form which does not occur naturally on Earth and of which only minimal amounts have been made in the laboratory. We have encountered this 'high-density amorphous ice' in electron diffraction experiments of low-temperature (T less than 30 K) vapor-deposited water and have subsequently modeled its structure using molecular dynamics simulations. The characteristic feature of high-density amorphous ice is the presence of 'interstitial' oxygen pair distances between 3 and 4 A. However, we find that the structure is best described as a collapsed lattice of the more familiar low-density amorphous form. These distortions are frozen in at temperatures below 38 K because, we propose, it requires the breaking of one hydrogen bond, on average, per molecule to relieve the strain and to restructure the lattice to that of low-density amorphous ice. Several features of astrophysical ice analogs studied in laboratory experiments are readily explained by the structural transition from high-density amorphous ice into low-density amorphous ice. Changes in the shape of the 3.07 gm water band, trapping efficiency of CO, CO loss, changes in the CO band structure, and the recombination of radicals induced by low-temperature UV photolysis all covary with structural changes that occur in the ice during this amorphous to amorphous transition. While the 3.07 micrometers ice band in various astronomical environments can be modeled with spectra of simple mixtures of amorphous and crystalline forms, the contribution of the high-density amorphous form nearly always dominates.

  16. Depairing current density through a low-angle grain boundary in a superconducting film

    NASA Astrophysics Data System (ADS)

    Xue, Feng; Zhang, Zhaoxia; Zeng, Jun; Gou, Xiaofan

    2016-05-01

    In this paper, the effect of a grain boundary (GB) on the depairing current density of a high-temperature superconducting film is investigated. The modified effective free energy is proposed by considering the interaction of the superconducting condensate with the deformation of the superconductor due to the dislocations which constitute a grain boundary. After the elastic strain field of the dislocation is obtained, we analyzed the depress effect of the GB on the depairing current density of a superconducting film. The results are qualitatively agreement with the classic exponential relationship with the misorientation angles of the critical current density of high-temperature superconductors.

  17. Murchison presolar carbon grains of different density fractions: A Raman spectroscopic perspective

    NASA Astrophysics Data System (ADS)

    Wopenka, B.; Xu, Y. C.; Zinner, E.; Amari, S.

    2013-04-01

    Raman analyses are reported of μm-sized areas of 103 individual carbonaceous presolar grains ("graphite grains") from three different density fractions of the Murchison meteorite. Few of the grains (2 or 3 of each density fraction) have Raman spectra typical for non-crystalline sp2-bonded carbon (i.e., "organic carbon") with extremely wide 1st-order and no (or very subdued) 2nd-order peaks, similar to the ones found for terrestrial kerogens. Based on depth profiles of isotopic ratios measured with the NanoSIMS, it is unlikely that such kerogen-type Raman signatures are caused by contamination of the presolar grains with insoluble organic material from the Murchison matrix that stuck to the surfaces of the grains. Rather, the kerogen-type grains are considered to be a new type of presolar carbon grains, which are made up of organic (PAH-like) sp2-bonded carbon. However, most of the other studied presolar carbon grains (95 of 103) have spectra with very narrow 1st-order peaks (called D and G peaks) and very strong 2nd-order peaks typical for inorganic sp2-bonded carbon. Based on their D/G intensity ratios, those grains were grouped into the following Raman types: (fairly well ordered) "graphite" (D/G < 0.5), "disordered graphite" (0.5 < D/G < 1.1), "glassy carbon" (D/G > 1.1), and "unusual sp2-bonded graphitic carbon" (with extremely intense 2nd-order peaks relative to the 1st-order peaks). Grains from the low-density fraction KFA1 (2.05-2.10 g/cm3) have predominantly "cauliflower" morphology and Raman spectra characteristic of either very disordered graphite or "glassy carbon" (i.e., the latter is amorphous from the Raman spectroscopic perspective), whereas most grains from the high-density fraction KFC1 (2.15-2.20 g/cm3) have "onion" morphology and Raman spectra characteristic of well-crystalline graphite. The KFB1 grains with intermediate density (2.10-2.15 g/cm3) are mixed, both in terms of their morphology and their Raman spectra but are closer to KFC1 than to

  18. C, N, AND O ISOTOPIC HETEROGENEITIES IN LOW-DENSITY SUPERNOVA GRAPHITE GRAINS FROM ORGUEIL

    SciTech Connect

    Groopman, Evan; Bernatowicz, Thomas; Zinner, Ernst

    2012-07-20

    We report on the results of NanoSIMS isotope imaging of low-density supernova graphite grains from the Orgueil meteorite. 70 nm thick microtomed sections of three supernova graphite grains were deposited on Si wafers and isotopically imaged in the NanoSIMS. These sections contain hotspots of excesses in {sup 18}O and {sup 15}N, which are spatially well correlated, and are likely carried by internal TiC subgrains. These hotspots are considerably more enriched in {sup 18}O and {sup 15}N than the host graphite grain. Correlations between {sup 18}O and {sup 15}N excesses indicate that the grains incorporated material from the He/C supernova zone. Isotope images of the surfaces of some grains show heterogeneities in their N and O isotope compositions, with extreme excesses in {sup 15}N and {sup 18}O. In the microtome sections, we also observe two types of heterogeneities in the grains' C isotopic compositions: smooth, radial gradients in {sup 12}C/{sup 13}C, with this ratio trending toward solar with increasing radius; and highly anomalous pockets up to 2 {mu}m in size with {sup 12}C/{sup 13}C >> solar that are located near the centers of the grain sections. Partial isotopic equilibration does not likely explain the C isotopic heterogeneities. These grains and their constituent parts probably formed in a stellar environment with changing isotopic composition.

  19. Estimating bulk density of compacted grains in storage bins and modifications of Janssen's load equations as affected by bulk density.

    PubMed

    Haque, Ekramul

    2013-03-01

    Janssen created a classical theory based on calculus to estimate static vertical and horizontal pressures within beds of bulk corn. Even today, his equations are widely used to calculate static loadings imposed by granular materials stored in bins. Many standards such as American Concrete Institute (ACI) 313, American Society of Agricultural and Biological Engineers EP 433, German DIN 1055, Canadian Farm Building Code (CFBC), European Code (ENV 1991-4), and Australian Code AS 3774 incorporated Janssen's equations as the standards for static load calculations on bins. One of the main drawbacks of Janssen's equations is the assumption that the bulk density of the stored product remains constant throughout the entire bin. While for all practical purposes, this is true for small bins; in modern commercial-size bins, bulk density of grains substantially increases due to compressive and hoop stresses. Over pressure factors are applied to Janssen loadings to satisfy practical situations such as dynamic loads due to bin filling and emptying, but there are limited theoretical methods available that include the effects of increased bulk density on the loadings of grain transmitted to the storage structures. This article develops a mathematical equation relating the specific weight as a function of location and other variables of materials and storage. It was found that the bulk density of stored granular materials increased with the depth according to a mathematical equation relating the two variables, and applying this bulk-density function, Janssen's equations for vertical and horizontal pressures were modified as presented in this article. The validity of this specific weight function was tested by using the principles of mathematics. As expected, calculations of loads based on the modified equations were consistently higher than the Janssen loadings based on noncompacted bulk densities for all grain depths and types accounting for the effects of increased bulk densities

  20. Sintering Trajectories: Description on How Density, Surface Area, and Grain Size Change

    NASA Astrophysics Data System (ADS)

    German, Randall M.

    2016-03-01

    Sintering is a mainstay production step in forming metal, ceramic, polymer, and composite components from particles. Since the 1940s, the sintering process is treated using a matrix of mathematical relationships that include at least seven atomic transport mechanisms, several options on powder characteristics, and three pore-grain morphology options. The interplay of these relationships is handled by numerical solutions to predict property development. An alternative approach is to track the sintering trajectory using relatively simple relationships based on bulk measures. Energy minimization dictates that initial stage sintering acts to reduce surface area. In late stage sintering, the energy minimization turns to grain boundary area reduction via grain growth. Accordingly, relationships result between density, surface area, and grain size, which largely ignore mechanistic details. These relationships are applicable to a wide variety of materials and consolidation conditions, including hot pressing, and spark sintering.

  1. Mechanical and thermal properties of high density polyethylene – dried distillers grains with solubles composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dried Distillers Grain with Solubles (DDGS) is evaluated as a bio-based fiber reinforcement. Injection molded composites of high density polyethylene (HDPE), 25% by weight of DDGS, and either 5% of 0% by weight of maleated polyethylene (MAPE) were produced by twin screw compounding and injection mo...

  2. Isotopic Anomalies Preserved Within Internal Grains in High-Density Presolar Graphites

    NASA Astrophysics Data System (ADS)

    Croat, T. K.; Bernatowicz, T. J.; Jadhav, M.

    2014-09-01

    NanoSIMS measurements of high-density (HD) Orgueil graphites are presented, concentrating on those contain carbide and rutile phases. We report a new internal SiC-C grain with 12C, 29Si and 30Si enrichments that likely originated in a massive star.

  3. Arena size, hole density, and capture of Oryzaephilus surinamensis (Coleoptera: Silvanidae) in grain probe traps.

    PubMed

    Epsky, Nancy D; Shuman, Dennis

    2004-02-01

    The relationship of size of test arena, number of holes in a grain probe trap body and capture of the sawtoothed grain beetle, Oryzaephilus surinamensis (L.), was determined in simulated field tests conducted in an outdoor screen enclosure exposed to natural temperature fluctuations. Polyvinylchloride (PVC) probe bodies were attached to electronic sensor heads, and insect captures were recorded electronically using an electronic grain probe insect counter (EGPIC) system. In comparisons among PVC probe trap bodies with 60, 132, 252, and 492 holes, tested at 18 insects per kilogram in 4.5, 17, and 40 kg of soft wheat in cylindrical arenas (10.2, 20.3, and 30.5 cm in diameter, respectively), number of holes in the probe trap body had no effect on insect capture, but percentage of insects recovered was indirectly related to size of the test arena. Periodicity of insect capture was determined using the time-stamp data that were recorded by the EGPIC system. Circadian rhythm was observed in the periodicity of the capture that corresponded to foraging activity peaks documented for sawtoothed grain beetles, with activity peaks occurring early in the scotophase. There were shifts in times of peak activity among the different test arena sizes that corresponded to differences in temperature in the grain mass. Increases in both temperature and contact between insects and grain probe in the smallest arenas resulted in higher capture of sawtoothed grain beetles. This research documents additional important factors when evaluating capture of sawtoothed grain beetles in grain probe traps. PMID:14998139

  4. Classical density functional theory & simulations on a coarse-grained model of aromatic ionic liquids.

    PubMed

    Turesson, Martin; Szparaga, Ryan; Ma, Ke; Woodward, Clifford E; Forsman, Jan

    2014-05-14

    A new classical density functional approach is developed to accurately treat a coarse-grained model of room temperature aromatic ionic liquids. Our major innovation is the introduction of charge-charge correlations, which are treated in a simple phenomenological way. We test this theory on a generic coarse-grained model for aromatic RTILs with oligomeric forms for both cations and anions, approximating 1-alkyl-3-methyl imidazoliums and BF₄⁻, respectively. We find that predictions by the new density functional theory for fluid structures at charged surfaces are very accurate, as compared with molecular dynamics simulations, across a range of surface charge densities and lengths of the alkyl chain. Predictions of interactions between charged surfaces are also presented. PMID:24718295

  5. Stochastic thermodynamics of fluctuating density fields: Non-equilibrium free energy differences under coarse-graining

    SciTech Connect

    Leonard, T.; Lander, B.; Seifert, U.; Speck, T.

    2013-11-28

    We discuss the stochastic thermodynamics of systems that are described by a time-dependent density field, for example, simple liquids and colloidal suspensions. For a time-dependent change of external parameters, we show that the Jarzynski relation connecting work with the change of free energy holds if the time evolution of the density follows the Kawasaki-Dean equation. Specifically, we study the work distributions for the compression and expansion of a two-dimensional colloidal model suspension implementing a practical coarse-graining scheme of the microscopic particle positions. We demonstrate that even if coarse-grained dynamics and density functional do not match, the fluctuation relations for the work still hold albeit for a different, apparent, change of free energy.

  6. Stochastic thermodynamics of fluctuating density fields: Non-equilibrium free energy differences under coarse-graining

    NASA Astrophysics Data System (ADS)

    Leonard, T.; Lander, B.; Seifert, U.; Speck, T.

    2013-11-01

    We discuss the stochastic thermodynamics of systems that are described by a time-dependent density field, for example, simple liquids and colloidal suspensions. For a time-dependent change of external parameters, we show that the Jarzynski relation connecting work with the change of free energy holds if the time evolution of the density follows the Kawasaki-Dean equation. Specifically, we study the work distributions for the compression and expansion of a two-dimensional colloidal model suspension implementing a practical coarse-graining scheme of the microscopic particle positions. We demonstrate that even if coarse-grained dynamics and density functional do not match, the fluctuation relations for the work still hold albeit for a different, apparent, change of free energy.

  7. Density and energy distribution of interface states in the grain boundaries of polysilicon nanowire.

    PubMed

    Amit, Iddo; Englander, Danny; Horvitz, Dror; Sasson, Yaniv; Rosenwaks, Yossi

    2014-11-12

    Wafer-scale fabrication of semiconductor nanowire devices is readily facilitated by lithography-based top-down fabrication of polysilicon nanowire (P-SiNW) arrays. However, free carrier trapping at the grain boundaries of polycrystalline materials drastically changes their properties. We present here transport measurements of P-SiNW array devices coupled with Kelvin probe force microscopy at different applied biases. By fitting the measured P-SiNW surface potential using electrostatic simulations, we extract the longitudinal dopant distribution along the nanowires as well as the density of grain boundaries interface states and their energy distribution within the band gap. PMID:25299928

  8. Processing Variables in Alumina Slips and Their Effects on the Density and Grain Size of the Sintered Sample

    SciTech Connect

    Rowley, R.; Lillo, Thomas Martin

    2002-01-01

    High densities and small grain size of alumina ceramic bodies provide high strength and better mechanical properties than lower density and larger grain size bodies. The final sintered density and grain size of slip-cast, alumina samples depends greatly on the processing of the slip and the alumina powder, as well as the sintering schedule. There were many different variables explored that include initial powder particle size, slurry solids percent, amount and type of dispersant used, amount and type of binder used, and sintering schedule. Although the experimentation is not complete, to this point the sample with the highest density and smallest grain size has been a SM8/Nano mixture with Darvan C as the dispersant and Polyvinyl Alcohol (PVA) as the binder, with a solids loading of 70 wt% and a 1500 °C for 2 hours sintering schedule. The resultant density was 98.81% of theoretical and the average grain size was approximately 2.5 µm.

  9. Processing Variables of Alumina Slips and Their Effects on the Density and Grain Size of the Sintered Sample

    SciTech Connect

    Rowley, R.; Chu, H.

    2002-01-01

    High densities and small grain size of alumina ceramic bodies provide high strength and better mechanical properties than lower density and larger grain size bodies. The final sintered density and grain size of slip-cast, alumina samples depends greatly on the processing of the slip and the alumina powder, as well as the sintering schedule. There were many different variables explored that include initial powder particle size, slurry solids percent, amount and type of dispersant used, amount and type of binder used, and sintering schedule. Although the experimentation is not complete, to this point the sample with the highest density and smallest grain size has been a SM8/Nano mixture with Darvan C as the dispersant and Polyvinyl Alcohol (PVA) as the binder, with a solids loading of 70 wt% and a 1500 C for 2 hours sintering schedule. The resultant density was 98.81% of theoretical and the average grain size was approximately 2.5 {micro}m.

  10. The influence of high grain boundary density on helium retention in tungsten

    NASA Astrophysics Data System (ADS)

    Valles, G.; González, C.; Martin-Bragado, I.; Iglesias, R.; Perlado, J. M.; Rivera, A.

    2015-02-01

    In order to study the influence of a high grain boundary density on the amount, size and distribution of defects produced by pulsed helium (625 keV) irradiation in tungsten, we have carried out Object Kinetic Monte Carlo (OKMC) simulations in both monocrystalline and nanocrystalline tungsten. The parameterization of the OKMC code (MMonCa) includes binding energies obtained with our in-house Density Functional Theory (DFT) calculations. In the interior of a grain in nanocrystalline tungsten the mixed HenVm clusters are larger and have a lower He/V ratio. Thus, they are less pressurized clusters. The total elastic strain energy remains almost constant with the increasing number of pulses, contrary to its increase in monocrystalline tungsten. A better response to helium irradiation is therefore expected in nanocrystalline tungsten, opening a new path to investigate these nanostructured materials for fusion purposes.

  11. Low-Density Graphite Grains and Mixing in Type II Supernovae

    NASA Astrophysics Data System (ADS)

    Travaglio, Claudia; Gallino, Roberto; Amari, Sachiko; Zinner, Ernst; Woosley, Stan; Lewis, Roy S.

    1999-01-01

    Primitive meteorites contain presolar grains that originated in stellar outflows and supernova ejecta. Low-density graphite grains from the Murchison carbonaceous meteorite were analyzed for the isotopic compositions of C, N, O, Mg, Si, K, Ca, and Ti by ion microprobe mass spectrometry. The grains are characterized by a large range of 12C/13C ratios (from 3.6 to 7200 compared to the solar ratio of 89), excesses in 15N (15N/14N up to 10 times solar) and 18O (18O/16O up to 185 times solar), large inferred 26Al/27Al ratios (from 26Mg excesses) ranging up to 0.15, a large range in Si isotopic ratios (from 50% deficits in 29Si and 30Si relative to 28Si up to more than 120% excesses), large excesses in 41K and 44Ca from the prior presence of now-extinct 41Ca (T1/2=105 yr) and 44Ti (T1/2=59 yr), respectively, and excesses in 42Ca, 43Ca relative to 40Ca, and 49Ti, and 50Ti relative to 48Ti. Several of these isotopic signatures indicate a supernova origin. In particular, the initial presence of 44Ti and excesses of 28Si as well as the size of the inferred 41Ca/40Ca ratios are proof that the carrier grains formed in supernova ejecta. We explored the possibility that the low-density graphite grains originated from C-rich ejecta of Type II supernovae. In such stars 44Ti and 28Si are produced in the inner layers and the presence of these two isotopes in carbonaceous grains is evidence for extensive mixing of different supernova layers in the explosion. We performed mixing calculations of different layers of the SN models by Woosley & Weaver under the imposed boundary condition that C>=O and compare the resulting isotopic ratios with the isotopic ratios measured in the meteoritic grains. The mixing model can explain the observed 12C/13C, 16O/18O, 30Si/28Si, and 44Ti and 41Ca fairly well as long as jets of material from the Si-rich zone, carrying 44Ti and pure 28Si, are assumed to penetrate the O-rich zone and are ejected into and mixed with the C-rich layers, where carbonaceous

  12. Internally oxidized Nb₃Sn strands with fine grain size and high critical current density.

    PubMed

    Xu, Xingchen; Sumption, Michael D; Peng, Xuan

    2015-02-25

    Nb3Sn strands fabricated using Nb-Zr alloy can be internally oxidized, provided that oxygen is properly supplied via an oxide powder. This allows the formation of fine intragranular and intergranular ZrO2 particles in a Nb3Sn matrix. These particles can refine the grain size by a factor of three and thereby greatly enhance the Nb3Sn critical current density. PMID:25582555

  13. Coarse-grained spin density-functional theory: Infinite-volume limit via the hyperfinite

    NASA Astrophysics Data System (ADS)

    Lammert, Paul E.

    2013-06-01

    Coarse-grained spin density functional theory (SDFT) is a version of SDFT which works with number/spin densities specified to a limited resolution — averages over cells of a regular spatial partition — and external potentials constant on the cells. This coarse-grained setting facilitates a rigorous investigation of the mathematical foundations which goes well beyond what is currently possible in the conventional formulation. Problems of existence, uniqueness, and regularity of representing potentials in the coarse-grained SDFT setting are here studied using techniques of (Robinsonian) nonstandard analysis. Every density which is nowhere spin-saturated is V-representable, and the set of representing potentials is the functional derivative, in an appropriate generalized sense, of the Lieb internal energy functional. Quasi-continuity and closure properties of the set-valued representing potentials map are also established. The extent of possible non-uniqueness is similar to that found in non-rigorous studies of the conventional theory, namely non-uniqueness can occur for states of collinear magnetization which are eigenstates of Sz.

  14. Fracture density and grain size controls on the relief structure of threshold landscapes

    NASA Astrophysics Data System (ADS)

    DiBiase, R.; Rossi, M. W.; Neely, A.

    2015-12-01

    A central goal in geomorphology is to untangle the competing controls of climate, tectonics, and rock strength on the topography and relief structure of mountain ranges. This is important for deciphering the history of climate and tectonics encoded in landscapes, predicting natural hazards, and quantifying critical zone processes. Incorporating rock strength into landscape evolution models has been a particularly challenging problem, because the factors that determine rock strength vary in importance depending on process. Here we propose a mechanism of hillslope-channel coupling by which tectonically-induced fracturing influences the relief structure of steep, rocky "threshold" landscapes by leading to A) increased fracture density in exposed bedrock outcrops, thereby limiting hillslope relief, and B) decreased grain size of channel bed material, thereby reducing the magnitude of fluvial incision thresholds and increasing the erosional efficiency of bedrock rivers. To test this hypothesis, we compare two contrasting landscapes in southern California—the eastern San Gabriel Mountains and the northern San Jacinto Mountains. The eastern San Gabriel Mountains rise 2 km in relief and exhibit high uplift and erosion rates due to active faulting along the Cucamonga thrust fault. Although bedrock on hillslopes is common, the exposed granitic and metamorphic basement rock is highly fractured at the decimeter or finer scale, and river channels are mantled with a thin layer of gravel-cobble alluvium. The northern San Jacinto Mountains, 80 km to the southeast, experience similar mean runoff and daily runoff variability, and are underlain by similar bedrock. Yet, despite an absence of active faulting, and erosion rates slower than the eastern San Gabriel Mountains by a factor of 5, the northern San Jacinto Mountains preserve one of the steepest escarpments in the contiguous US (2-3 km high), characterized by massive bedrock outcrops on hillslopes with meter-scale or larger

  15. A coarse-grain force field for RDX: Density dependent and energy conserving

    NASA Astrophysics Data System (ADS)

    Moore, Joshua D.; Barnes, Brian C.; Izvekov, Sergei; Lísal, Martin; Sellers, Michael S.; Taylor, DeCarlos E.; Brennan, John K.

    2016-03-01

    We describe the development of a density-dependent transferable coarse-grain model of crystalline hexahydro-1,3,5-trinitro-s-triazine (RDX) that can be used with the energy conserving dissipative particle dynamics method. The model is an extension of a recently reported one-site model of RDX that was developed by using a force-matching method. The density-dependent forces in that original model are provided through an interpolation scheme that poorly conserves energy. The development of the new model presented in this work first involved a multi-objective procedure to improve the structural and thermodynamic properties of the previous model, followed by the inclusion of the density dependency via a conservative form of the force field that conserves energy. The new model accurately predicts the density, structure, pressure-volume isotherm, bulk modulus, and elastic constants of the RDX crystal at ambient pressure and exhibits transferability to a liquid phase at melt conditions.

  16. Refractory Organic Compounds in Enceladus' Ice Grains and Hydrothermal Activity

    NASA Astrophysics Data System (ADS)

    Postberg, F.; Khawaja, N.; Hsu, H. W.; Sekine, Y.; Shibuya, T.

    2015-12-01

    Cassini's Cosmic Dust Analyzer (CDA) generates time-of-flight mass spectra of individual grains impinging on the instruments target-plate. Following the analysis of salt rich ice grains emitted by Enceladus that indicated a salt-water ocean in contact with the moon's rocky core [1,2] a recent CDA analysis of nano-phase silica particles pointed at hydrothermal activity at the moon's rock/water interface [3]. The results imply temperatures above 80 - 90°C and alkaline pH values around 10 reminiscent of alkaline hydrothermal vents on Earth like the Lost City Hydrothermal Field. In this context the compositional analysis of organic components in CDA mass spectra of the ejected ice grains is of particular relevance. A multitude of volatile organic species has already been identified in the gas component of the plume [4]. As expected, we find more complex organic molecules in ice grains than in the gas indicating aromatic species, amines, and carbonyl group species. The composition of organic-bearing ice grains displays a great diversity indicating a variety of different organic species in varying concentrations. Recent spatially resolved CDA in situ measurements inside Enceladus' plume indicate that these organic compounds are especially frequent in 'young' ice grains that have just been ejected by high velocity jets. We investigate the implications of our findings with respect to ice grain formation at the water surface and inside the icy vents. We constrain the generation of organic compounds at the rock/water interface in the light of hydrothermal activity and the potential for the formation of life precursor molecules in Enceladus' ocean. Ref:[1] Postberg et al., Nature 459, 1098-1101 (2009). [2] Postberg et al., Nature 474, 620-622 (2011). [3]. Hsu, Postberg, Sekine et al., Nature, 519, 207-210 (2015). [4] Waite et al., Nature 460, 487-490 (2009).

  17. Aspects of the density field in an active nematic

    PubMed Central

    Mishra, Shradha; Puri, Sanjay; Ramaswamy, Sriram

    2014-01-01

    Active nematics are conceptually the simplest orientationally ordered phase of self-driven particles, but have proved to be a perennial source of surprises. We show here through numerical solution of coarse-grained equations for the order parameter and density that the growth of the active nematic phase from the isotropic phase is necessarily accompanied by a clumping of the density. The growth kinetics of the density domains is shown to be faster than the law expected for variables governed by a conservation law. Other results presented include the suppression of density fluctuations in the stationary ordered nematic by the imposition of an orienting field. We close by posing some open questions. PMID:25332390

  18. Antioxidant activities of selective gluten free ancient grains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ancient grains were known for special nutritional values along with gluten free qualities. Amaranth, quinoa, teff, buckwheat flours were evaluated for pasting properties, water holding capacity, phenolic contents, and antioxidant activities (free and bound). They all had higher water holding capacit...

  19. Segregation of sedimenting grains of different densities in an oscillating velocity field of strongly nonlinear surface waves

    NASA Astrophysics Data System (ADS)

    Ezersky, A. B.; Marin, F.

    2008-08-01

    This paper reports the results of an experimental and theoretical study of the segregation of heavy (sand) and light [polyvinyl chloride (PVC)] grains under the action of intense nonlinear water waves, solitons. The tests are carried out with initially carefully mixed grains at the bottom of a wave flume used in resonant mode. Ripples form on the bed and the segregation process is considered after the stopping of the wave paddle. The waves are damped and the PVC grains concentrate in a narrow region close to the ripple crest. A theoretical model explaining this grain density segregation is developed.

  20. Segregation of sedimenting grains of different densities in an oscillating velocity field of strongly nonlinear surface waves.

    PubMed

    Ezersky, A B; Marin, F

    2008-08-01

    This paper reports the results of an experimental and theoretical study of the segregation of heavy (sand) and light [polyvinyl chloride (PVC)] grains under the action of intense nonlinear water waves, solitons. The tests are carried out with initially carefully mixed grains at the bottom of a wave flume used in resonant mode. Ripples form on the bed and the segregation process is considered after the stopping of the wave paddle. The waves are damped and the PVC grains concentrate in a narrow region close to the ripple crest. A theoretical model explaining this grain density segregation is developed. PMID:18850874

  1. A coarse-grain force field for RDX: Density dependent and energy conserving.

    PubMed

    Moore, Joshua D; Barnes, Brian C; Izvekov, Sergei; Lísal, Martin; Sellers, Michael S; Taylor, DeCarlos E; Brennan, John K

    2016-03-14

    We describe the development of a density-dependent transferable coarse-grain model of crystalline hexahydro-1,3,5-trinitro-s-triazine (RDX) that can be used with the energy conserving dissipative particle dynamics method. The model is an extension of a recently reported one-site model of RDX that was developed by using a force-matching method. The density-dependent forces in that original model are provided through an interpolation scheme that poorly conserves energy. The development of the new model presented in this work first involved a multi-objective procedure to improve the structural and thermodynamic properties of the previous model, followed by the inclusion of the density dependency via a conservative form of the force field that conserves energy. The new model accurately predicts the density, structure, pressure-volume isotherm, bulk modulus, and elastic constants of the RDX crystal at ambient pressure and exhibits transferability to a liquid phase at melt conditions. PMID:26979691

  2. DENSITY CURRENTS IN ACTIVATED SLUDGE SECONDARY CLARIFIERS

    EPA Science Inventory

    Density currents form in activated sludge secondary clarifiers because the mixed liquor has a density greater than the treated wastewater in the clarifier. This causes the mixed liquor to plunge to the bottom of the clarifier establishing relatively high velocity currents within ...

  3. Predicting Stored Grain Insect Population Densities Using an Electronic Probe Trap

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Manual sampling of insects in stored grain is a laborious and time consuming process. Automation of grain sampling should help to increase the adoption of stored-grain integrated pest management. A new commercial electronic grain probe trap (OPI Insector™) has recently been marketed. We field tested...

  4. Evidence of decreasing mineral density in wheat grain over the last 160 years.

    PubMed

    Fan, Ming-Sheng; Zhao, Fang-Jie; Fairweather-Tait, Susan J; Poulton, Paul R; Dunham, Sarah J; McGrath, Steve P

    2008-01-01

    Wheat is an important source of minerals such as iron, zinc, copper and magnesium in the UK diet. The dietary intake of these nutrients has fallen in recent years because of a combination of reduced energy requirements associated with sedentary lifestyles and changes in dietary patterns associated with lower micronutrient density in the diet. Recent publications using data from food composition tables indicate a downward trend in the mineral content of foods and it has been suggested that intensive farming practices may result in soil depletion of minerals. The aim of our study was to evaluate changes in the mineral concentration of wheat using a robust approach to establish whether trends are due to plant factors (e.g. cultivar, yield) or changes in soil nutrient concentration. The mineral concentration of archived wheat grain and soil samples from the Broadbalk Wheat Experiment (established in 1843 at Rothamsted, UK) was determined and trends over time examined in relation to cultivar, yield, and harvest index. The concentrations of zinc, iron, copper and magnesium remained stable between 1845 and the mid 1960s, but since then have decreased significantly, which coincided with the introduction of semi-dwarf, high-yielding cultivars. In comparison, the concentrations in soil have either increased or remained stable. Similarly decreasing trends were observed in different treatments receiving no fertilizers, inorganic fertilizers or organic manure. Multiple regression analysis showed that both increasing yield and harvest index were highly significant factors that explained the downward trend in grain mineral concentration. PMID:19013359

  5. Radon Emanation from Zircon as a Function of Grain Size, Temperature and Fission Track Density

    NASA Astrophysics Data System (ADS)

    Eakin, M.; Barbero, L.; Brownlee, S. J.; Baskaran, M. M.

    2012-12-01

    Radon emanation from rocks and minerals is ubiquitous. Quantification of radon emanation rates from zircon is critical to assess the reliability of U-Pb ages of zircon bearing rocks. The 238U decay chain includes 222Rn, a noble gas, which can readily escape the crystal structure if sufficient escape pathways in lattice structure exist, ultimately leading to a deficiency of 206Pb in the parent crystal. Few studies have directly investigated the link between track density and 222Rn emanation rates, and none have done this for zircon. In order to evaluate the factors affecting radon emanation from the mineral zircon under different conditions, a series of experiments were performed on a large, crushed Mud Tank zircon crystal. Five different grain sizes (500 μm, 250-500 μm, 125-250 μm, 63 - 125 μm, and < 63 μm) were separated and sealed in closed glass jars and radon emanation rates were measured at 25 C. These aliquots are then subjected to a range of temperatures (100 C, 200 C, 400 C, and 600 C) for six hours and the radon emanation rates are measured after each heating step. Fission track densities are measured after the same annealing temperature steps allowing quantification of 222Rn emanation rate as a function of fission track density. The concentration of 210Pb, 234Th, 212Pb, 226Ra and 228Ra in these fractions are also measured using gamma spectroscopy. The results of these experiments will have implications for U-Pb dating (i.e., explanation of discordant ages), and noble gas escape systematics in zircon (i.e., volume diffusion or fast pathway escape). The possibility also exists for using 222Rn, or other noble gasses, as a measure of defect density within crystals.

  6. Physical Activity and Bone Density in Women

    NASA Technical Reports Server (NTRS)

    Bowley, Susan M.; Whalen, R. T.

    2000-01-01

    A mathematical model of bone density regulation as a function of the daily tissue "effective" stress has been derived. Using the model, the influence of daily activity in the form of a daily loading history has been related to bone density of the calcaneus. The theory incorporates a stress exponent m to account for differences in the importance of magnitude and number of load cycles experienced during daily activity. We have derived a parameter from the model, the "Bone Density Index" (BDI). We have developed a method of collecting daily habitual loading histories using an insole force sensor interfaced to a portable digital data logger carried in a fanny pack. Our goal for this study was to determine a stress exponent, m, relating GRFz history to Calcaneal Bone Mineral Density (CBMD).

  7. 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

  8. 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

  9. Strain localization in ultramylonitic marbles by simultaneous activation of dislocation motion and grain boundary sliding (Syros, Greece)

    NASA Astrophysics Data System (ADS)

    Rogowitz, A.; White, J. C.; Grasemann, B.

    2015-09-01

    Extreme strain localization occurred in the center of the cross-cutting element of a flanking structure in almost pure calcite marbles from Syros, Greece. At the maximum displacement of 120 cm along the cross-cutting element evidence of grain size sensitive deformation mechanisms can be found in the ultramylonitic marbles, which are characterized by (1) an extremely small grain size (∼3 μm), (2) grain boundary triple junctions with nearly 120° angles, (3) a weak crystallographic preferred orientation with very low texture index (J=1.4), (4) a random misorientation angle distribution curve and (5) the presence of small cavities. Using transmission electron microscopy a deformation sequence is observed comprising, first recrystallization by bulging resulting in the development of the fine-grained ultramylonite followed by the evolution of a high dislocation density (∼1013 m-2) with ongoing deformation of the fine-grained ultramylonite. The arrangement of dislocations in the extremely fine grain sized calcite differs from microstructures created by classical dislocation creep mediated by combined glide and thermally activated climb. Instead, it exhibits extensive glide and dislocation networks characteristic of recovery accommodated by cross-slip and network-assisted dislocation movement without formation of idealized subgrain walls. The enabling of grain boundary sliding to dislocation activity is deemed central to initiating and sustaining strain softening and is argued to be an important strain localization process in calcite rocks, even at high strain rate (10-9 s-1) and low temperature (300 °C).

  10. Strain localization in ultramylonitic marbles by simultaneous activation of dislocation motion and grain boundary sliding (Syros, Greece)

    NASA Astrophysics Data System (ADS)

    Rogowitz, A.; White, J. C.; Grasemann, B.

    2016-03-01

    Extreme strain localization occurred in the centre of the cross-cutting element of a flanking structure in almost pure calcite marbles from Syros, Greece. At the maximum displacement of 120 cm along the cross-cutting element, evidence of grain size sensitive deformation mechanisms can be found in the ultramylonitic marbles, which are characterized by (1) an extremely small grain size ( ˜ 3 µm), (2) grain boundary triple junctions with nearly 120° angles, (3) a weak crystallographic preferred orientation with very low texture index (J = 1.4), (4) a random misorientation angle distribution curve and (5) the presence of small cavities. Using transmission electron microscopy, a deformation sequence is observed comprising recrystallization dominantly by bulging, resulting in the development of the fine-grained ultramylonite followed by the development of a high dislocation density ( ˜ 1013 m-2) with ongoing deformation of the fine-grained ultramylonite. The arrangement of dislocations in the extremely fine-grain-sized calcite differs from microstructures created by classical dislocation creep mediated by combined glide and thermally activated climb. Instead, it exhibits extensive glide and dislocation networks characteristic of recovery accommodated by cross-slip and network-assisted dislocation movement without formation of idealized subgrain walls. The enabling of grain boundary sliding to dislocation activity is deemed central to initiating and sustaining strain softening and is argued to be an important strain localization process in calcite rocks, even at a high strain rate ( ˜ 10-9 s-1) and low temperature (300 °C).

  11. Production and characterization of activated carbons from cereal grains

    SciTech Connect

    Venkatraman, A.; Walawender, S.P.; Fan, L.T.

    1996-10-01

    The kernels of grain such as corn and hard red winter wheat were subjected to a two-stage pyrolytic process to generate relatively high yields of charcoals. The process involved carbonization of the kernels at low temperatures (250-325{degrees}C) followed by complete devolatilization of the resultant charcoals at around 750{degrees}C. The charcoals were subsequently activated physically with CO{sub 2} at 800{degrees}C to yield activated carbons. The total pore volumes and surface areas of the activated carbons were determined at various degree of activation by physisorption methods. The surface areas from the nitrogen BET method ranged from 500 to 1750 m{sup 2}/g, while the total pore volumes obtained from the volumes at saturation were in the interval from 0.3 to 0.7 cm{sup 3}/g. The fractal nature of the pore interfaces as well as the existence of different types of pores were investigated through small-angle x-ray scattering.

  12. Grain boundary premelting and activated sintering in binary refractory alloys

    NASA Astrophysics Data System (ADS)

    Shi, Xiaomeng

    Quasi-liquid intergranular film (IGF) which has been widely observed in ceramic systems can persist into sub-solidus region whereby an analogy to Grain boundary (GB) premelting can be made. In this work, a grain boundary (GB) premelting/prewetting model in a metallic system was firstly built based on the Benedictus' model and computational thermodynamics, predicting that GB disordering can start at 60-85% of the bulk solidus temperatures in selected systems. This model quantitatively explains the long-standing mystery of subsolidus activated sintering in W-Pd, W-Ni, W-Co, W-Fe and W-Cu, and it has broad applications for understanding GB-controlled transport kinetics and physical properties. Furthermore, this study demonstrates the necessity of developing GB phase diagrams as a tool for materials design. Subsequently, Grain boundary (GB) wetting and prewetting in Ni-doped Mo are systematically evaluated via characterizing well-quenched specimens and thermodynamic modeling. In contrast to prior reports, the delta-NiMo phase does not wet Mo GBs in the solid state. In the solid-liquid two-phase region, the Ni-rich liquid wets Mo GBs completely. Furthermore, high-resolution transmission electron microscopy demonstrates that nanometer-thick quasi-liquid IGFs persist at GBs into the single-phase region where the bulk liquid phase is no longer stable; this is interpreted as a case of GB prewetting. An analytical thermodynamic model is developed and validated, and this model can be extended to other systems. Furthermore, the analytical model was refined based upon Beneditus' model with correction in determining interaction contribution of interfacial energy. A calculation-based GB phase diagram for Ni-Mo binary system was created and validated by comparing with GB diffusivities determined through a series of controlled sintering experiments. The dependence of GB diffusivity on doping level and temperature was examined and compared with model-predicted GB phase diagram. The

  13. Detection of powdery mildew in two winter wheat plant densities and prediction of grain yield using canopy hyperspectral reflectance.

    PubMed

    Cao, Xueren; Luo, Yong; Zhou, Yilin; Fan, Jieru; Xu, Xiangming; West, Jonathan S; Duan, Xiayu; Cheng, Dengfa

    2015-01-01

    To determine the influence of plant density and powdery mildew infection of winter wheat and to predict grain yield, hyperspectral canopy reflectance of winter wheat was measured for two plant densities at Feekes growth stage (GS) 10.5.3, 10.5.4, and 11.1 in the 2009-2010 and 2010-2011 seasons. Reflectance in near infrared (NIR) regions was significantly correlated with disease index at GS 10.5.3, 10.5.4, and 11.1 at two plant densities in both seasons. For the two plant densities, the area of the red edge peak (Σdr680-760 nm), difference vegetation index (DVI), and triangular vegetation index (TVI) were significantly correlated negatively with disease index at three GSs in two seasons. Compared with other parameters Σdr680-760 nm was the most sensitive parameter for detecting powdery mildew. Linear regression models relating mildew severity to Σdr680-760 nm were constructed at three GSs in two seasons for the two plant densities, demonstrating no significant difference in the slope estimates between the two plant densities at three GSs. Σdr680-760 nm was correlated with grain yield at three GSs in two seasons. The accuracies of partial least square regression (PLSR) models were consistently higher than those of models based on Σdr680760 nm for disease index and grain yield. PLSR can, therefore, provide more accurate estimation of disease index of wheat powdery mildew and grain yield using canopy reflectance. PMID:25815468

  14. Detection of Powdery Mildew in Two Winter Wheat Plant Densities and Prediction of Grain Yield Using Canopy Hyperspectral Reflectance

    PubMed Central

    Cao, Xueren; Luo, Yong; Zhou, Yilin; Fan, Jieru; Xu, Xiangming; West, Jonathan S.; Duan, Xiayu; Cheng, Dengfa

    2015-01-01

    To determine the influence of plant density and powdery mildew infection of winter wheat and to predict grain yield, hyperspectral canopy reflectance of winter wheat was measured for two plant densities at Feekes growth stage (GS) 10.5.3, 10.5.4, and 11.1 in the 2009–2010 and 2010–2011 seasons. Reflectance in near infrared (NIR) regions was significantly correlated with disease index at GS 10.5.3, 10.5.4, and 11.1 at two plant densities in both seasons. For the two plant densities, the area of the red edge peak (Σdr680–760 nm), difference vegetation index (DVI), and triangular vegetation index (TVI) were significantly correlated negatively with disease index at three GSs in two seasons. Compared with other parameters Σdr680–760 nm was the most sensitive parameter for detecting powdery mildew. Linear regression models relating mildew severity to Σdr680–760 nm were constructed at three GSs in two seasons for the two plant densities, demonstrating no significant difference in the slope estimates between the two plant densities at three GSs. Σdr680–760 nm was correlated with grain yield at three GSs in two seasons. The accuracies of partial least square regression (PLSR) models were consistently higher than those of models based on Σdr680760 nm for disease index and grain yield. PLSR can, therefore, provide more accurate estimation of disease index of wheat powdery mildew and grain yield using canopy reflectance. PMID:25815468

  15. 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...

  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. Study of the interaction of solutes with Σ5 (013) tilt grain boundaries in iron using density-functional theory

    SciTech Connect

    Jin, Hao; Militzer, Matthias; Elfimov, Ilya

    2014-03-07

    Substitutional alloying elements significantly affect the recrystallization and austenite-ferrite phase transformation rates in steels. The atomistic mechanisms of their interaction with the interfaces are still largely unexplored. Using density functional theory, we determine the segregation energies between commonly used alloying elements and the Σ5 (013) tilt grain boundary in bcc iron. We find a strong solute-grain boundary interaction for Nb, Mo, and Ti that is consistent with experimental observations of the effects of these alloying elements on delaying recrystallization and the austenite-to-ferrite transformation in low-carbon steels. In addition, we compute the solute-solute interactions as a function of solute pair distance in the grain boundary, which suggest co-segregation for these large solutes at intermediate distances in striking contrast to the bulk.

  18. An Unusual Low-Density Supernova Graphite Grain with a Nanocrystalline Core

    NASA Astrophysics Data System (ADS)

    Groopman, E.; Bernatowicz, T.; Zinner, E.

    2013-09-01

    We have discovered a unique supernova graphite grain containing a nanocrystalline core. Electron diffraction studies of the core show evidence for stacked graphene sheets, previously unobserved in other nanocrystalline cores.

  19. The Effect of Grain Size and Dislocation Density on the Tensile Properties of Ni-SiCNP Composites During Annealing

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Huang, Hefei; Thorogood, Gordon James; Jiang, Li; Ye, Xiangxi; Li, Zhijun; Zhou, Xingtai

    2016-03-01

    The grain size refinement, enhancement of mechanical properties, and static recrystallization behavior of metallic nickel-silicon carbide nano-particle (Ni-3wt.%SiCNP) composites, milled for times ranging from 8 to 48 h have been examined. One set of Ni-SiCNP composite samples were annealed at 300 °C for 250 h, while the other set of samples were maintained at room temperature for control purposes (reference). The electron backscatter diffraction results indicate that the grain size of the annealed Ni-SiCNP composite was refined due to grain restructuring during static recrystallization. The x-ray diffraction results indicate that low-temperature annealing effectively reduced the density of dislocations; this can be explained by the dislocation pile-up model. Additionally, the tensile tests indicated that the annealed Ni-SiCNP composite had a significant increase in strength due to an increase of the Hall-Petch strengthening effect with a slight increase in the total elongation. The decrease of dislocation pile-up in the grain interiors and the increase in grain boundary sliding are assumed to be the main mechanisms at play. The relationship between the microstructural evolution and the variation of tensile properties is examined in this study.

  20. A Direct Grain-Boundary-Activity Correlation for CO Electroreduction on Cu Nanoparticles

    PubMed Central

    2016-01-01

    Copper catalyzes the electrochemical reduction of CO to valuable C2+ products including ethanol, acetate, propanol, and ethylene. These reactions could be very useful for converting renewable energy into fuels and chemicals, but conventional Cu electrodes are energetically inefficient and have poor selectivity for CO vs H2O reduction. Efforts to design improved catalysts have been impeded by the lack of experimentally validated, quantitative structure–activity relationships. Here we show that CO reduction activity is directly correlated to the density of grain boundaries (GBs) in Cu nanoparticles (NPs). We prepared electrodes of Cu NPs on carbon nanotubes (Cu/CNT) with different average GB densities quantified by transmission electron microscopy. At potentials ranging from −0.3 V to −0.5 V vs the reversible hydrogen electrode, the specific activity for CO reduction to ethanol and acetate was linearly proportional to the fraction of NP surfaces comprised of GB surface terminations. Our results provide a design principle for CO reduction to ethanol and acetate on Cu. GB-rich Cu/CNT electrodes are the first NP catalysts with significant CO reduction activity at moderate overpotential, reaching a mass activity of up to ∼1.5 A per gram of Cu and a Faradaic efficiency >70% at −0.3 V. PMID:27163043

  1. A Direct Grain-Boundary-Activity Correlation for CO Electroreduction on Cu Nanoparticles.

    PubMed

    Feng, Xiaofeng; Jiang, Kaili; Fan, Shoushan; Kanan, Matthew W

    2016-03-23

    Copper catalyzes the electrochemical reduction of CO to valuable C2+ products including ethanol, acetate, propanol, and ethylene. These reactions could be very useful for converting renewable energy into fuels and chemicals, but conventional Cu electrodes are energetically inefficient and have poor selectivity for CO vs H2O reduction. Efforts to design improved catalysts have been impeded by the lack of experimentally validated, quantitative structure-activity relationships. Here we show that CO reduction activity is directly correlated to the density of grain boundaries (GBs) in Cu nanoparticles (NPs). We prepared electrodes of Cu NPs on carbon nanotubes (Cu/CNT) with different average GB densities quantified by transmission electron microscopy. At potentials ranging from -0.3 V to -0.5 V vs the reversible hydrogen electrode, the specific activity for CO reduction to ethanol and acetate was linearly proportional to the fraction of NP surfaces comprised of GB surface terminations. Our results provide a design principle for CO reduction to ethanol and acetate on Cu. GB-rich Cu/CNT electrodes are the first NP catalysts with significant CO reduction activity at moderate overpotential, reaching a mass activity of up to ∼1.5 A per gram of Cu and a Faradaic efficiency >70% at -0.3 V. PMID:27163043

  2. Coarse-grained models using local-density potentials optimized with the relative entropy: Application to implicit solvation

    NASA Astrophysics Data System (ADS)

    Sanyal, Tanmoy; Shell, M. Scott

    2016-07-01

    Bottom-up multiscale techniques are frequently used to develop coarse-grained (CG) models for simulations at extended length and time scales but are often limited by a compromise between computational efficiency and accuracy. The conventional approach to CG nonbonded interactions uses pair potentials which, while computationally efficient, can neglect the inherently multibody contributions of the local environment of a site to its energy, due to degrees of freedom that were coarse-grained out. This effect often causes the CG potential to depend strongly on the overall system density, composition, or other properties, which limits its transferability to states other than the one at which it was parameterized. Here, we propose to incorporate multibody effects into CG potentials through additional nonbonded terms, beyond pair interactions, that depend in a mean-field manner on local densities of different atomic species. This approach is analogous to embedded atom and bond-order models that seek to capture multibody electronic effects in metallic systems. We show that the relative entropy coarse-graining framework offers a systematic route to parameterizing such local density potentials. We then characterize this approach in the development of implicit solvation strategies for interactions between model hydrophobes in an aqueous environment.

  3. Coarse-grained models using local-density potentials optimized with the relative entropy: Application to implicit solvation.

    PubMed

    Sanyal, Tanmoy; Shell, M Scott

    2016-07-21

    Bottom-up multiscale techniques are frequently used to develop coarse-grained (CG) models for simulations at extended length and time scales but are often limited by a compromise between computational efficiency and accuracy. The conventional approach to CG nonbonded interactions uses pair potentials which, while computationally efficient, can neglect the inherently multibody contributions of the local environment of a site to its energy, due to degrees of freedom that were coarse-grained out. This effect often causes the CG potential to depend strongly on the overall system density, composition, or other properties, which limits its transferability to states other than the one at which it was parameterized. Here, we propose to incorporate multibody effects into CG potentials through additional nonbonded terms, beyond pair interactions, that depend in a mean-field manner on local densities of different atomic species. This approach is analogous to embedded atom and bond-order models that seek to capture multibody electronic effects in metallic systems. We show that the relative entropy coarse-graining framework offers a systematic route to parameterizing such local density potentials. We then characterize this approach in the development of implicit solvation strategies for interactions between model hydrophobes in an aqueous environment. PMID:27448876

  4. Grain structure and dislocation density measurements in a friction stir welded aluminum alloy using x-ray peak profile analysis

    SciTech Connect

    Woo, Wan Chuck; Balogh, Levente; Ungar, Prof Tomas; Choo, Hahn; Feng, Zhili

    2008-01-01

    The dislocation density and grain structure of a friction stir welded 6061-T6 aluminum alloy was determined as a function of distance from the weld centerline using high-resolution micro-beam x-ray diffraction. The results of the x-ray peak profile analysis show that the dislocation density is about 1.2 x 10^14 m-2 inside and 4.8 x 10^14 m-2 outside of the weld region. The average subgrain size is about 180 nm in both regions. Compared to the base material, the dislocation density was significantly decreased in the dynamic recrystallized zone of the friction stir welds, which is a good correlation with the TEM observations. The influence of the dislocation density on the strain hardening behavior during tensile deformation is also discussed.

  5. Coarse-grained density and compressibility of nonideal crystals: General theory and an application to cluster crystals

    NASA Astrophysics Data System (ADS)

    Häring, J. M.; Walz, C.; Szamel, G.; Fuchs, M.

    2015-11-01

    The isothermal compressibility of a general crystal is analyzed within classical density functional theory. Our approach can be used for homogeneous and unstrained crystals containing an arbitrarily high density of local defects. We start by coarse-graining the microscopic particle density and then obtain the long-wavelength limits of the correlation functions of elasticity theory and the thermodynamic derivatives. We explicitly show that the long-wavelength limit of the microscopic density correlation function differs from the isothermal compressibility. We apply our theory to crystals consisting of soft particles which can multiply occupy lattice sites ("cluster crystals"). The multiple occupancy results in a strong local disorder over an extended range of temperatures. We determine the cluster crystals' isothermal compressibility, the fluctuations of the lattice occupation numbers and their correlation functions, and the dispersion relations. We also discuss their low-temperature phase diagram.

  6. Removing grain boundaries from three-dimensional colloidal crystals using active dopants.

    PubMed

    van der Meer, B; Dijkstra, M; Filion, L

    2016-07-01

    Using computer simulations we explore how grain boundaries can be removed from three-dimensional colloidal crystals by doping with a small fraction of active colloids. We show that for sufficient self-propulsion, the system is driven into a crystal-fluid coexistence. In this phase separated regime, the active dopants become mobile and spontaneously gather at the grain boundaries. The resulting surface melting and recrystallization of domains result in the motion of the grain boundaries over time and lead to the formation of a large single crystal. However, when the self-propulsion is too low to cause a phase separation, we observe no significant enhancement of grain growth. PMID:27257054

  7. Grain and Seed Moisture and Density Measurement through Sensing of Dielectric Properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The importance of moisture measurement in grain and seed is discussed, and a brief history of the development of moisture sensing instruments, based on sensing of dielectric properties of these materials, is presented. Data are presented graphically on the permittivities or dielectric properties of...

  8. Measurement of Grain and Seed Moisture and Density Through Permittivity Relationships

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The importance of moisture measurement in grain and seed is discussed, and a brief history of the development of moisture sensing instruments, based on sensing of dielectric properties of these materials, is presented. Data are presented graphically on the permittivities or dielectric properties of...

  9. Measurement of grain and seed microwave permitivity for moisture and density determination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The importance of moisture measurement in grain and seed is discussed, and a brief history of the development of moisture sensing instruments, based on sensing of dielectric properties of these materials, is presented. Data are presented graphically on the permittivities or dielectric properties of ...

  10. Dependence of grain boundary chemistry on the irradiation dose in low activation ferritics

    NASA Astrophysics Data System (ADS)

    Kimura, A.; Charlot, L. A.; Gelles, D. S.; Jones, R. H.

    1994-09-01

    Grain boundary chemistries in low activation 9%Cr-2%Mn-1%W and 12%Cr-6%Mn-1%W steels were measured by means of Auger electron spectroscopy (AES) after irradiations in the FFTF/MOTA at 638 K up to doses of 10 and 25 dpa. In 12%Cr-6%Mn-1%W steel, grain boundary concentration of Si increased with an increase in the irradiation dose from 10 to 25 dpa. Segregation of Mn, however, appeared to saturate or even decreased with the increase. The average size of grain boundary precipitates was increased during the irradiation from 10 to 25 dpa. It is considered that beyond the 10 dpa irradiation, Mn-rich precipitates at grain boundaries absorb Mn atoms segregated at grain boundaries, resulting in the growth of grain boundary precipitates and the reduction of segregated Mn atoms in elemental form at grain boundaries. It is possible that Si atoms which may compete site with Mn atoms at grain boundaries begin to segregate at grain boundaries. In contrast, no significant change in grain boundary chemistry was recognized in 9%Cr-2%Mn-1%W alloy with the increase in irradiation dose from 10 to 25 dpa.

  11. Evaluation of a microwave resonator for predicting grain moisture independent of bulk density

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This work evaluated the ability of a planar whispering mode resonator to predict moisture considering moisture and densities expected in an on-harvester application. A calibration model was developed to accurately predict moisture over the moisture, density and temperature ranges evaluated. This mod...

  12. Atomic density effects on temperature characteristics and thermal transport at grain boundaries through a proper bin size selection

    NASA Astrophysics Data System (ADS)

    Vo, Truong Quoc; Barisik, Murat; Kim, BoHung

    2016-05-01

    This study focuses on the proper characterization of temperature profiles across grain boundaries (GBs) in order to calculate the correct interfacial thermal resistance (ITR) and reveal the influence of GB geometries onto thermal transport. The solid-solid interfaces resulting from the orientation difference between the (001), (011), and (111) copper surfaces were investigated. Temperature discontinuities were observed at the boundary of grains due to the phonon mismatch, phonon backscattering, and atomic forces between dissimilar structures at the GBs. We observed that the temperature decreases gradually in the GB area rather than a sharp drop at the interface. As a result, three distinct temperature gradients developed at the GB which were different than the one observed in the bulk solid. This behavior extends a couple molecular diameters into both sides of the interface where we defined a thickness at GB based on the measured temperature profiles for characterization. Results showed dependence on the selection of the bin size used to average the temperature data from the molecular dynamics system. The bin size on the order of the crystal layer spacing was found to present an accurate temperature profile through the GB. We further calculated the GB thickness of various cases by using potential energy (PE) distributions which showed agreement with direct measurements from the temperature profile and validated the proper binning. The variation of grain crystal orientation developed different molecular densities which were characterized by the average atomic surface density (ASD) definition. Our results revealed that the ASD is the primary factor affecting the structural disorders and heat transfer at the solid-solid interfaces. Using a system in which the planes are highly close-packed can enhance the probability of interactions and the degree of overlap between vibrational density of states (VDOS) of atoms forming at interfaces, leading to a reduced ITR. Thus, an

  13. Atomic density effects on temperature characteristics and thermal transport at grain boundaries through a proper bin size selection.

    PubMed

    Vo, Truong Quoc; Barisik, Murat; Kim, BoHung

    2016-05-21

    This study focuses on the proper characterization of temperature profiles across grain boundaries (GBs) in order to calculate the correct interfacial thermal resistance (ITR) and reveal the influence of GB geometries onto thermal transport. The solid-solid interfaces resulting from the orientation difference between the (001), (011), and (111) copper surfaces were investigated. Temperature discontinuities were observed at the boundary of grains due to the phonon mismatch, phonon backscattering, and atomic forces between dissimilar structures at the GBs. We observed that the temperature decreases gradually in the GB area rather than a sharp drop at the interface. As a result, three distinct temperature gradients developed at the GB which were different than the one observed in the bulk solid. This behavior extends a couple molecular diameters into both sides of the interface where we defined a thickness at GB based on the measured temperature profiles for characterization. Results showed dependence on the selection of the bin size used to average the temperature data from the molecular dynamics system. The bin size on the order of the crystal layer spacing was found to present an accurate temperature profile through the GB. We further calculated the GB thickness of various cases by using potential energy (PE) distributions which showed agreement with direct measurements from the temperature profile and validated the proper binning. The variation of grain crystal orientation developed different molecular densities which were characterized by the average atomic surface density (ASD) definition. Our results revealed that the ASD is the primary factor affecting the structural disorders and heat transfer at the solid-solid interfaces. Using a system in which the planes are highly close-packed can enhance the probability of interactions and the degree of overlap between vibrational density of states (VDOS) of atoms forming at interfaces, leading to a reduced ITR. Thus, an

  14. Microwave sensing of moisture content and bulk density in flowing grain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Moisture content and bulk density were determined from measurement of the dielectric properties of flowing wheat kernels at a single microwave frequency (5.8 GHz). The measuring system consisted of two high-gain microwave patch antennas mounted on opposite sides of rectangular chute and connected to...

  15. Cellular activity of bioactive nanograined/ultrafine-grained materials.

    PubMed

    Misra, R D K; Thein-Han, W W; Mali, S A; Somani, M C; Karjalainen, L P

    2010-07-01

    Our recent electron microscopy study on biomimetic nanostructured coatings on nanograined/ultrafine-grained (NG/UFG) substrates [Mater Sci Eng C 2009;29:2417-27] indicated that electrocrystallized nanohydroxyapatite (nHA) on phase-reversion-induced NG/UFG substrates exhibited a vein-type interconnected and fibrillar structure that closely mimicked the hierarchical structure of bone. The fibrillar structure on NG/UFG substrate is expected to be more favorable for cellular response than a planar surface. In contrast, hydroxyapatite (HA) coating on coarse-grained (CG) substrate more closely resembled a film rather than a fibrillar structure. Inspired by the differences in the structure of HA coating, we describe here the cell-substrate interactions of pre-osteoblasts (MC 3T3-E1) on bioactive NG/UFG and CG austenitic stainless steel substrates. NG/UFG austenitic stainless steel was obtained by a novel controlled phase-reversion annealing of cold-deformed austenite. This example provides an illustration of how a combination of cellular and molecular biology, materials science and engineering can advance our understanding of cell-substrate interactions. Interestingly, the cellular response of nanohydroxyapatite (nHA)-coated NG/UFG substrate demonstrated superior cytocompatibility, improved initial cell attachment, higher viability and proliferation, and well-spread morphology in relation to HA-coated CG substrate and their respective uncoated (bare) counterparts as implied by fluorescence and electron microscopy and MTT assay. Similar conclusions were derived from an immunofluorescence study that involved examination of the expression levels of vinculin focal adhesion contacts associated with dense actin stress fibers and fibronectin, protein analysis through protein bands in SDS-PAGE, and quantitative total protein assay. The enhancement of cellular response followed the sequence: nHA-coated NG/UFG>nHA-coated CG>NG/UFG>CG substrates. The outcomes of the study are

  16. Grain sorting in the morphological active layer of a braided river physical model

    NASA Astrophysics Data System (ADS)

    Leduc, P.; Ashmore, P.; Gardner, J. T.

    2015-12-01

    A physical scale model of a gravel-bed braided river was used to measure vertical grain size sorting in the morphological active layer aggregated over the width of the river. This vertical sorting is important for analyzing braided river sedimentology, for numerical modeling of braided river morphodynamics, and for measuring and predicting bedload transport rate. We define the morphological active layer as the bed material between the maximum and minimum bed elevations at a point over extended time periods sufficient for braiding processes to rework the river bed. The vertical extent of the active layer was measured using 40 hourly high-resolution DEMs (digital elevation models) of the model river bed. An image texture algorithm was used to map bed material grain size of each DEM. Analysis of the 40 DEMs and texture maps provides data on the geometry of the morphological active layer and variation in grain size in three dimensions. By normalizing active layer thickness and dividing into 10 sublayers, we show that all grain sizes occur with almost equal frequency in all sublayers. Occurrence of patches and strings of coarser (or finer) material relates to preservation of particular morpho-textural features within the active layer. For numerical modeling and bedload prediction, a morphological active layer that is fully mixed with respect to grain size is a reliable approximation.

  17. Grain sorting in the morphological active layer of a braided river physical model

    NASA Astrophysics Data System (ADS)

    Leduc, P.; Ashmore, P.; Gardner, J. T.

    2015-07-01

    A physical scale model of a gravel-bed braided river was used to measure vertical grain size sorting in the morphological active layer aggregated over the width of the river. This vertical sorting is important for analyzing braided river sedimentology, for numerical modeling of braided river morpho-dynamics and for measuring and predicting bed load transport rate. We define the morphological active layer as the bed material between the maximum and minimum bed elevations at a point over extended time periods sufficient for braiding processes to re-work the river bed. The vertical extent of the active layer was measured using 40 hourly high-resolution DEMs of the model river bed. An image texture algorithm was used to map bed material grain size of each DEM. Analysis of the 40 DEMs and texture maps provides data on the geometry of the morphological active layer and variation in grain size in three-dimensions. Normalizing active layer thickness and dividing into 10 sub-layers we show that all grain sizes occur with almost equal frequency in all sub-layers. Occurrence of patches and strings of coarser (or finer) material relates to preservation of particular morpho-textural features within the active layer. For numerical modeling and bed load prediction a morphological active layer that is fully mixed with respect to grain size is a reliable approximation.

  18. Effect of texture and grain size on the magnetic flux density and core loss of cold-rolled high silicon steel sheets

    NASA Astrophysics Data System (ADS)

    Qin, Jing; Yang, Ping; Mao, Weimin; Ye, Feng

    2015-11-01

    The effects of texture and grain size on the magnetic flux density and core loss (50-20 kHz) of 0.23 mm-thick cold-rolled high silicon steel sheets are investigated by means of electron back-scattered diffraction (EBSD), loss separation, and anisotropy parameter (ε) calculation. A model of the hysteresis loss coefficient kh considering average grain size and ε is established. The magnetic flux density at 800 A/m (B8) is closely related to the volume fraction of η-fiber-oriented grains, while the magnetic flux density at 5000 A/m (B50) is closely related to the volume fractions of γ- and λ-fiber-oriented grains in high silicon steel. The hysteresis loss of high silicon steel can be greatly reduced by increasing the grain size and optimizing the texture of the sheets. Although increases in frequencies decrease the effect of texture on core loss, the effect cannot be ignored. As annealing temperature and time increase, the relative difference in core loss between the rolling direction (RD) and the transverse direction (TD) is maintained at higher frequencies because of increases in grain size, decreases in γ texture, and maintenance of a strong η texture. Texture and grain size jointly affect the high-frequency core loss of high silicon steel.

  19. Effects of reduced terrestrial LiDAR point density on high-resolution grain crop surface models in precision agriculture.

    PubMed

    Hämmerle, Martin; Höfle, Bernhard

    2014-01-01

    3D geodata play an increasingly important role in precision agriculture, e.g., for modeling in-field variations of grain crop features such as height or biomass. A common data capturing method is LiDAR, which often requires expensive equipment and produces large datasets. This study contributes to the improvement of 3D geodata capturing efficiency by assessing the effect of reduced scanning resolution on crop surface models (CSMs). The analysis is based on high-end LiDAR point clouds of grain crop fields of different varieties (rye and wheat) and nitrogen fertilization stages (100%, 50%, 10%). Lower scanning resolutions are simulated by keeping every n-th laser beam with increasing step widths n. For each iteration step, high-resolution CSMs (0.01 m2 cells) are derived and assessed regarding their coverage relative to a seamless CSM derived from the original point cloud, standard deviation of elevation and mean elevation. Reducing the resolution to, e.g., 25% still leads to a coverage of >90% and a mean CSM elevation of >96% of measured crop height. CSM types (maximum elevation or 90th-percentile elevation) react differently to reduced scanning resolutions in different crops (variety, density). The results can help to assess the trade-off between CSM quality and minimum requirements regarding equipment and capturing set-up. PMID:25521383

  20. Effects of Reduced Terrestrial LiDAR Point Density on High-Resolution Grain Crop Surface Models in Precision Agriculture

    PubMed Central

    Hämmerle, Martin; Höfle, Bernhard

    2014-01-01

    3D geodata play an increasingly important role in precision agriculture, e.g., for modeling in-field variations of grain crop features such as height or biomass. A common data capturing method is LiDAR, which often requires expensive equipment and produces large datasets. This study contributes to the improvement of 3D geodata capturing efficiency by assessing the effect of reduced scanning resolution on crop surface models (CSMs). The analysis is based on high-end LiDAR point clouds of grain crop fields of different varieties (rye and wheat) and nitrogen fertilization stages (100%, 50%, 10%). Lower scanning resolutions are simulated by keeping every n-th laser beam with increasing step widths n. For each iteration step, high-resolution CSMs (0.01 m2 cells) are derived and assessed regarding their coverage relative to a seamless CSM derived from the original point cloud, standard deviation of elevation and mean elevation. Reducing the resolution to, e.g., 25% still leads to a coverage of >90% and a mean CSM elevation of >96% of measured crop height. CSM types (maximum elevation or 90th-percentile elevation) react differently to reduced scanning resolutions in different crops (variety, density). The results can help to assess the trade-off between CSM quality and minimum requirements regarding equipment and capturing set-up. PMID:25521383

  1. Production of Cs and Fr isotopes from a high-density UC targets with different grain dimensions

    NASA Astrophysics Data System (ADS)

    Panteleev, V. N.; Alyakrinskiy, O.; Barbui, M.; Barzakh, A. E.; Fedorov, D. V.; Ivanov, V. S.; Lhersonneau, G.; Mezilev, K. A.; Molkanov, P. L.; Moroz, F. V.; Orlov, S. Yu.; Stroe, L.; Tecchio, L. B.; Tonezzer, M.; Volkov, Yu. M.

    2009-12-01

    A UC target material of 11.3±0.5 g/cm^3 uranium density with the grain size of 20 and 5μm manufactured in a form of pills by the method of powder metallurgy has been tested on-line within the temperature range of 1800-2100 ° C . The mass of uranium exposed to the beam was 4-7g. The yields and release rates of Cs and Fr isotopes produced by fission and spallation reactions of 238U by 1GeV protons have been measured. The yields of Cs and Fr isotopes obtained from the tested target materials have been compared, including yields of very short-lived Fr isotopes with half-lives down to 1ms. Temperature-resistant materials (porous graphite and tantalum foil) have been used for the internal-container construction, which holds the UC target pills inside a tungsten external container heated by the resistant heating. The fastest release and the highest efficiency for short-lived isotopes have been obtained for the targets with the internal container manufactured from the tantalum foil. Results of on-line tests of a big mass target (730g of 5μm grain UC target material) have been discussed.

  2. Changes in whole grain polyphenols and antioxidant activity of six sorghum genotypes under different irrigation treatments.

    PubMed

    Wu, Gangcheng; Johnson, Stuart K; Bornman, Janet F; Bennett, Sarita J; Fang, Zhongxiang

    2017-01-01

    Sorghum grain containing elevated polyphenolic antioxidant content may provide foods with benefits to human health. A study was undertaken to determine the potential role of irrigation on the content of polyphenols and antioxidant levels in sorghum grain. Bound, free and total polyphenols were investigated in six diverse sorghum genotypes grown under either full irrigation or a deficit irrigation regime. Results showed genotype, irrigation and their interaction had a significant effect on polyphenols and antioxidant activity (P⩽0.05). The deficit irrigation treatment significantly increased polyphenol content and antioxidant activity compared to the full irrigation treatment. Of the six genotypes Shawaya black short 1 and IS1311C (brown) showed the highest polyphenols levels and antioxidant activity. Therefore, both irrigation treatments and genotype need to be considered by sorghum breeders and farmers during sorghum production to produce grain with the required levels of polyphenolics and antioxidant activity for targeted end-use. PMID:27507466

  3. Evaluation of antioxidant activity of amaranth (Amaranthus cruentus) grain and by-products (flour, popping, cereal).

    PubMed

    Paśko, Paweł; Bartoń, Henryk; Fołta, Maria; Gwizdz, Jadwiga

    2007-01-01

    The objective of our study was evaluation antioxidant activity of Amaranthus cruentus grain and by-products (flour, cereals and popping). The evaluation was performed by FRAP, DPPH and ABTS methods. FRAP and ABTS assays gave comparable results, DPPH method gave lower values. Among by-products cereal had the highest activity as the least processed product. Additionally, antioxidant capacities of two cultivars of amaranth (varieties Aztek and Rawa) were compared and the influence of grain soaking on antioxidant properties was taken into account. It was found, that soaking decreased antioxidant activity of amaranth seed. PMID:17711088

  4. Pseudo-single-crystal electrochemistry on polycrystalline electrodes: visualizing activity at grains and grain boundaries on platinum for the Fe2+/Fe3+ redox reaction.

    PubMed

    Aaronson, Barak D B; Chen, Chang-Hui; Li, Hongjiao; Koper, Marc T M; Lai, Stanley C S; Unwin, Patrick R

    2013-03-13

    The influence of electrode surface structure on electrochemical reaction rates and mechanisms is a major theme in electrochemical research, especially as electrodes with inherent structural heterogeneities are used ubiquitously. Yet, probing local electrochemistry and surface structure at complex surfaces is challenging. In this paper, high spatial resolution scanning electrochemical cell microscopy (SECCM) complemented with electron backscatter diffraction (EBSD) is demonstrated as a means of performing 'pseudo-single-crystal' electrochemical measurements at individual grains of a polycrystalline platinum electrode, while also allowing grain boundaries to be probed. Using the Fe(2+/3+) couple as an illustrative case, a strong correlation is found between local surface structure and electrochemical activity. Variations in electrochemical activity for individual high index grains, visualized in a weakly adsorbing perchlorate medium, show that there is higher activity on grains with a significant (101) orientation contribution, compared to those with (001) and (111) contribution, consistent with findings on single-crystal electrodes. Interestingly, for Fe(2+) oxidation in a sulfate medium a different pattern of activity emerges. Here, SECCM reveals only minor variations in activity between individual grains, again consistent with single-crystal studies, with a greatly enhanced activity at grain boundaries. This suggests that these sites may contribute significantly to the overall electrochemical behavior measured on the macroscale. PMID:23405963

  5. Density, Grain-size, and Vesicle Analysis of Hawaiian Fountains During the 1969 Mauna Ulu Eruption at Kilauea

    NASA Astrophysics Data System (ADS)

    Parcheta, C. E.; Houghton, B. F.; Swanson, D.

    2011-12-01

    Fountains from the Mauna Ulu eruption in 1969 produced a tephra cone and blanket similar in size to that of Kilauea Iki a decade earlier. The 12 episodes from the eruption displayed a range of fountain behaviors, from low fissure fountains on May 24 (episode 1) to high paired and single circular-sourced fountains in episodes 2 through 12. The highest fountain from this eruption was during the 9-hr long episode 9 (Sep 6-7), and reached 540 m, the second highest fountain recorded at Kilauea. Differences in the vigor and eruption style of these Hawaiian fountains are broadly related to the gas content driving magma ascent through the plumbing system in the east rift zone and the rate and timing of exsolution of this gas. While the tephra cone is now buried under 70 m of a lava shield, and lava flows cover the eastern half of the tephra blanket, the western half of the tephra blanket is still exposed. The nearest possible sample location to the vent is 1.7 km SW of the summit of Mauna Ulu. Transects across (east to west) and down (north to south) the wind direction were made to obtain a partial data set for the Mauna Ulu tephra remaining on the surface. Density, grain-size, and vesicle analysis was performed for a complete stratigraphic column recreated with the crosswind transect data; maximum class dimensions were measured in downwind pits. Median density shifts and the occurrence of bimodal density samples suggest gradual outgassing of the whole system with at least one injection of gas-rich material coming into the system during the seven months of eruption in 1969. Median grain-size is consistent at -2.5 to -2.0 phi. Polished thin sections show microlites in some pyroclasts, which may indicate magma mixing (also suggested in Swanson et al., 1979) either with previously erupted and recycled material from the Mauna Ulu eruption or a second magma source stored in the easternmost portion of the Koa'e fault system. We present here new data on vesicle number density and

  6. Production and characterization of activated carbons from cereal grains

    SciTech Connect

    Venkatraman, A.; Walawender, W.P.; Fan, L.T.

    1996-12-31

    The term, activated carbon, is a generic name for a family of carbonaceous materials with well-developed porosities and consequently, large adsorptive capacities. Activated carbons are increasingly being consumed worldwide for environmental applications such as separation of volatiles from bulk gases and purification of water and waste-water streams. The global annual production is estimated to be around 300 million kilograms, with a rate of increase of 7% each year. Activated carbons can be prepared from a variety of raw materials. Approximately, 60% of the activated carbons generated in the United States is produced from coal; 20%, from coconut shells; and the remaining 20% from wood and other sources of biomass. The pore structure and properties of activated carbons are influenced by the nature of the starting material and the initial physical and chemical conditioning as well as the process conditions involved in its manufacture. The porous structures of charcoals and activated carbons obtained by the carbonization of kernels have been characterized.

  7. Total Phenolics and Antioxidant Activity of Extracts from Distillers' Dried Grains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn is an abundant source of phenolic acids; therefore, distillers’ dried grains (DDG), may exhibit important market value for its phenolic content and antioxidant activity. The purpose of this study was to determine the efficacy of extracting phenolic compounds with antioxidant activity from DDG ...

  8. Inheritance of grain polyphenol oxidase (PPO) activity in multiple wheat (Triticum aestivum L.) genetic backgrounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain polyphenol oxidase (PPO) activity can cause discoloration of wheat (Triticum aestivum L.) food products. Five crosses (PI 117635/Antelope; Fielder/NW03681; Fielder/Antelope; NW07OR1070/Antelope; NW07OR1066/OR2050272H) were selected to study the genetic inheritance of PPO activity. STS marker...

  9. A modified ferrous oxidation-xylenol orange assay for lipoxygenase activity in rice grains.

    PubMed

    Timabud, Tarinee; Sanitchon, Jirawat; Pongdontri, Paweena

    2013-12-01

    Ferrous oxidation-xylenol orange assay reagent was reformulated by using spectral analysis of ferric-xylenol orange complex to detect low concentrations of lipoxygenase rice grain products. Reducing the levels of ferrous sulphate and xylenol orange in the FOX reagent enabled the detection of low concentrations of hydroperoxy fatty acid derived from lipoxygenase activity in the range of 0.1-1.5 μM. Protein, substrate and time courses of the modified FOX assay were studied to determine lipoxygenase activity in rice grain. The assay was also applicable as a high throughput technique for comparisons of lipoxygenase activity from various rice varieties. This has important implications for rapid screening for low-lipoxygenase containing rice cultivars in rice breeding program and grain quality during storage. PMID:23870974

  10. Understanding diffusion and density anomaly in a coarse-grained model for water confined between hydrophobic walls.

    PubMed

    de los Santos, Francisco; Franzese, Giancarlo

    2011-12-01

    We study, by Monte Carlo simulations, a coarse-grained model of a water monolayer between hydrophobic walls at partial hydration, with a wall-to-wall distance of about 0.5 nm. We analyze how the diffusion constant parallel to the walls, D(∥), changes and correlates to the phase diagram of the system. We find a locus of D(∥) maxima and a locus of D(∥) minima along isotherms, with lines of constant D(∥) resembling the melting line of bulk water. The two loci of D(∥) extrema envelope the line of temperatures of density maxima at constant P. We show how these loci are related to the anomalous volume behavior due to the hydrogen bonds. At much lower T, confined water becomes subdiffusive, and we discuss how this behavior is a consequence of the increased correlations among water molecules when the hydrogen bond network develops. Within the subdiffusive region, although translations are largely hampered, we observe that the hydrogen bond network can equilibrate, and its rearrangement is responsible for the appearance of density minima along isobars. We clarify that the minima are not necessarily related to the saturation of the hydrogen bond network. PMID:22129131

  11. Seismic shaking effects on grain size and density sorting with implications for constraining lunar regolith bulk composition

    NASA Astrophysics Data System (ADS)

    Ostrach, L. R.; Robinson, M. S.

    2010-12-01

    Different remote sensing techniques measure different depths within the lunar regolith, and measurements of the optical surface may not accurately represent the regolith mixture beneath the surface, even at a few centimeters depth. For example, ilmenite (FeTiO3) is a high-density oxide that is sometimes abundant in lunar samples [1]. Compositional information derived from Clementine UVVIS spectral reflectance, which assumes that ilmenite is the dominant opaque in mare basalts and the primary carrier of titanium, uses ilmenite absorptions in the UV as a proxy for titanium abundance [e.g., 2]. The UVVIS titanium estimates do not match well with those measured by the Lunar Prospector neutron/gamma-ray spectrometers [3]; UVVIS reflectance is controlled by only the top few microns while the neutron spectrometer senses to a depth greater than 10 cm. The goal of this investigation is to determine whether the lunar regolith may exhibit compositional sorting at the optical surface (few 100 μm) compared to the subsurface (10 cm). Regolith samples from the Apollo missions reveal that relative concentrations of ferromagnesian minerals, such as ilmenite, decrease with decreasing grain size and different minerals are thought to comminute at different rates [4]. These observations suggest that ilmenite may persist in larger grain size fractions than other regolith components. We investigate the possibility of mechanical sorting of the topmost layer of regolith such that denser particles preferentially sink. Mechanical sorting of the regolith may occur in two different regimes: 1) during ejecta emplacement following an impact event of any size, and 2) as a result of seismic disturbance created by nearby impacts or moonquakes. We created an experimental procedure to mimic seismic shaking, which may be a primary process promoting density-driven mechanical sorting of particles within the regolith. We tested a vertical shaking regime and horizontal shaking tests are in progress

  12. Activated carbon from pyrolysis of brewer's spent grain: Production and adsorption properties.

    PubMed

    Vanreppelen, Kenny; Vanderheyden, Sara; Kuppens, Tom; Schreurs, Sonja; Yperman, Jan; Carleer, Robert

    2014-06-20

    Brewer's spent grain is a low cost residue generated by the brewing industry. Its chemical composition (high nitrogen content 4.35 wt.%, fibres, etc.) makes it very useful for the production of added value in situ nitrogenised activated carbon. The composition of brewer's spent grain revealed high amounts of cellulose (20.8 wt.%), hemicellulose (48.78 wt.%) and lignin (11.3 wt.%). The fat, ethanol extractives and ash accounted for 8.17 wt.%, 4.7 wt.% and 3.2 wt.%, respectively. Different activated carbons were produced in a lab-scale pyrolysis/activation reactor by applying several heat and steam activation profiles on brewer's spent grain. Activated carbon yields from 16.1 to 23.6 wt.% with high N-contents (> 2 wt.%) were obtained. The efficiency of the prepared activated carbons for phenol adsorption was studied as a function of different parameters: pH, contact time and carbon dosage relative to two commercial activated carbons. The equilibrium isotherms were described by the non-linear Langmuir and Freundlich models, and the kinetic results were fitted using the pseudo-first-order model and the pseudo-second-order model. The feasibility of an activated carbon production facility (onsite and offsite) that processes brewer's spent grain for different input feeds is evaluated based on a techno-economic model for estimating the net present value. Even though the model assumptions start from a rather pessimistic scenario, encouraging results for a profitable production of activated carbon using brewer's spent grain are obtained. PMID:25012859

  13. Stored-grain insect population commingling densities in wheat and corn from pilot-scale bucket elevator boots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain elevator boot and pit areas facilitate the commingling of insects with the grain moving through the elevator leg. A removable boot was developed to facilitate residual grain removal and preservation in the boot and to quantify the commingling magnitude as a function of stored-product insect de...

  14. Phenolic acids and antioxidant activity of distillers dried grains with solubles (DDGS) as compared with corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sample sets of ground corn and the corresponding distillers dried grains with solubles (DDGS) were collected from three commercial plants in Iowa. Phenolic acids were analyzed by high performance liquid chromatography coupled with diode array and/or mass spectrometry. The antioxidant activity was ...

  15. Irradiation-induced grain growth in nanocrystalline reduced activation ferrite/martensite steel

    SciTech Connect

    Liu, W. B.; Chen, L. Q.; Zhang, C. Yang, Z. G.; Ji, Y. Z.; Zang, H.; Shen, T. L.

    2014-09-22

    In this work, we investigate the microstructure evolution of surface-nanocrystallized reduced activation ferrite/martensite steels upon high-dose helium ion irradiation (24.3 dpa). We report a significant irradiation-induced grain growth in the irradiated buried layer at a depth of 300–500 nm, rather than at the peak damage region (at a depth of ∼840 nm). This phenomenon can be explained by the thermal spike model: minimization of the grain boundary (GB) curvature resulting from atomic diffusion in the cascade center near GBs.

  16. Stability and electronic structure of the low- Σ grain boundaries in CdTe: a density functional study

    DOE PAGESBeta

    Park, Ji-Sang; Kang, Joongoo; Yang, Ji-Hui; Metzger, Wyatt; Wei, Su-Huai

    2015-01-15

    Using first-principles density functional calculations, we investigate the relative stability and electronic structure of the grain boundaries (GBs) in zinc-blende CdTe. Among the low-Σ-value symmetric tilt Σ3 (111), Σ3 (112), Σ5 (120), and Σ5 (130) GBs, we show that the Σ3 (111)GB is always the most stable due to the absence of dangling bonds and wrong bonds. The Σ5 (120) GBs, however, are shown to be more stable than the Σ3 (112) GBs, even though the former has a higher Σ value, and the latter is often used as a model system to study GB effects in zinc-blende semiconductors. Furthermore,more » we find that although containing wrong bonds, the Σ5 (120) GBs are electrically benign due to the short wrong bond lengths, and thus are not as harmful as the Σ3 (112) GBs also having wrong bonds but with longer bond lengths.« less

  17. Significantly enhanced critical current density in nano-MgB2 grains rapidly formed at low temperature with homogeneous carbon doping

    NASA Astrophysics Data System (ADS)

    Liu, Yongchang; Lan, Feng; Ma, Zongqing; Chen, Ning; Li, Huijun; Barua, Shaon; Patel, Dipak; Shahriar, M.; Hossain, Al; Acar, S.; Kim, Jung Ho; Xue Dou, Shi

    2015-05-01

    High performance MgB2 bulks using carbon-coated amorphous boron as a boron precursor were fabricated by Cu-activated sintering at low temperature (600 °C, below the Mg melting point). Dense nano-MgB2 grains with a high level of homogeneous carbon doping were formed in these MgB2 samples. This type of microstructure can provide a stronger flux pinning force, together with depressed volatility and oxidation of Mg owing to the low-temperature Cu-activated sintering, leading to a significant improvement of critical current density (Jc) in the as-prepared samples. In particular, the value of Jc for the carbon-coated (Mg1.1B2)Cu0.05 sample prepared here is even above 1 × 105 A cm-2 at 20 K, 2 T. The results herein suggest that the combination of low-temperature Cu-activated sintering and employment of carbon-coated amorphous boron as a precursor could be a promising technique for the industrial production of practical MgB2 bulks or wires with excellent Jc, as the carbon-coated amorphous boron powder can be produced commercially at low cost, while the addition of Cu is very convenient and inexpensive.

  18. Study of a Coincidence Detector Using a Suspension of Superheated Superconducting Grains in a High Density Dielectric Matrix for Positron Emission Tomography and γ-γ Tagging

    NASA Astrophysics Data System (ADS)

    Bruère Dawson, R.; Maillard, J.; Maurel, G.; Parisi, J.; Silva, J.; Waysand, G.

    2006-01-01

    We demonstrate the feasibility of coincidence detectors based on superheated superconducting grains (SSG) in a high density dielectric matrix (HDDM) for two applications: 1) positron cameras for small animal imaging, where two diametrically opposite cells are simultaneously hit by 511 keV gammas; 2) tagging of γ-γ events in electron positron colliders.

  19. Effects of Density, Activity, and Personality on Environmental Preferences

    ERIC Educational Resources Information Center

    Cozby, Paul C.

    1973-01-01

    The effects of room density, type of ongoing activity (party vs studying), and a personality variable ( personal space'' or the distance which subjects place between themselves and others) on room liking were investigated. (Author)

  20. Antioxidant activity and total phenolics in selected cereal grains and their different morphological fractions.

    PubMed

    Zieliński, H; Kozłowska, H

    2000-06-01

    The purpose of this study was to examine the antioxidant properties of water and 80% methanolic extracts of cereal grains and their different morphological fractions. Wheat (Triticum aestivum L.) cv. Almari and cv. Henika, barley (Hordeum vulgare L.) cv. Gregor and cv. Mobek, rye (Secale cereale L.) cv. Dańkowskie Zlote, oat (Avena sativa L.) cv. Slawko and buckwheat (Fagopyrum esculentum Moench) cv. Kora were used. PC (L-alpha-phosphatidylcholine) liposome system and spectrophotometric assay of total antioxidant activity (TAA) were used to evaluate the antioxidative activity of extracts. Among the water extracts, only the one prepared from buckwheat exhibited antioxidant activity at the concentration analyzed. The following hierarchy of antioxidant activity was provided for 80% methanolic extracts originated from whole grain: buckwheat > barley > oat > wheat congruent with rye. The antioxidant activity was observed in extract prepared from separated parts of buckwheat and barley. In respect to hulls, the antioxidant hierarchy was as follows: buckwheat > oat > barley. The correlation coefficient between total phenolic compounds and total antioxidative activity of the extracts was -0.35 for water extracts and 0.96, 0.99, 0.80, and 0.99 for 80% methanolic extracts originated from whole grains, hulls, pericarb with testa fractions and endosperm with embryo fractions, respectively. PMID:10888490

  1. Evaluation of anti-inflammatory activity of Typha angustifolia pollen grains extracts in experimental animals

    PubMed Central

    Varpe, Saroj S.; Juvekar, Archana R.; Bidikar, Mukta P.; Juvekar, Parikshit R.

    2012-01-01

    Objective: This study was designed to evaluate the anti-inflammatory activity of aqueous and 70% methanolic extracts of pollen grains of Typha angustifolia. Materials and Methods: Female Sprague Dawley rats were used for the study. The acute anti-inflammatory activity of pollen grains of T. angustifolia was studied using the carrageenan as phlogistic agent, whereas its chronic anti-inflammatory effect was investigated by the percentage inhibition of cotton pellet-induced granuloma. Results: Both aqueous and 70% methanolic extracts of pollen grains of T. angustifolia showed significant dose-dependent inhibition of carrageenan-induced paw edema as compared to the control (P<0.001). It was observed that both the extracts at dose of 125 mg/kg inhibited the granuloma formation by 44.30% which is higher than at dose of 500, 250 mg/kg, thus causing a significant (P<0.001) non-dose-related inhibition of granuloma formation. Conclusion: The results of this study indicate that extracts of pollen grains of T. angustifolia are effective in the treatment of both acute and chronic inflammatory conditions and thus support its traditional utilization. PMID:23248413

  2. Changes in activity of lysine decarboxylase in winter triticale in response to grain aphid feeding.

    PubMed

    Sempruch, C; Leszczyński, B; Wójcicka, Agnieszka; Makosz, M; Matok, H; Chrzanowski, G

    2010-12-01

    Changes in lysine decarboxylase (LDC) activity caused by Sitobion avenae (F.) feeding on two winter triticale cultivars (cvs) were studied. The aphid fecundity and values of intrinsic rate of natural increase showed that cv Witon was less susceptible to S. avenae than cv Tornado. The grain aphid feeding on more susceptible triticale caused a decrease in the LDC activity, with exceptions of root tissues after two weeks of the feeding. In case of less susceptible cv Witon reduction of the LDC activity was observed only during initial period of S. avenae feeding. Later the aphid infestation induced activity of the LDC within tissues of cv Witon. PMID:21112841

  3. The interaction of hydrogen with the {010} surfaces of Mg and Fe olivine as models for interstellar dust grains: a density functional theory study

    PubMed Central

    Downing, C. A.; Ahmady, B.; Catlow, C. R. A.; de Leeuw, N. H.

    2013-01-01

    There is no consensus as yet to account for the significant presence of water on the terrestrial planets, but suggested sources include direct hydrogen adsorption from the parent molecular cloud after the planets’ formation, and delivery of hydrous material via comets or asteroids external to the zone of the terrestrial planets. Alternatively, a more recent idea is that water may have directly adsorbed onto the interstellar dust grains involved in planetary formation. In this work, we use electronic structure calculations based on the density functional theory to investigate and compare the bulk and {010} surface structures of the magnesium and iron end-members of the silicate mineral olivine, namely forsterite and fayalite, respectively. We also report our results on the adsorption of atomic hydrogen at the mineral surfaces, where our calculations show that there is no activation barrier to the adsorption of atomic hydrogen at these surfaces. Furthermore, different surface sites activate the atom to form either adsorbed hydride or proton species in the form of hydroxy groups on the same surface, which indicates that these mineral surfaces may have acted as catalytic sites in the immobilization and reaction of hydrogen atoms to form dihydrogen gas or water molecules. PMID:23734054

  4. The interaction of hydrogen with the {010} surfaces of Mg and Fe olivine as models for interstellar dust grains: a density functional theory study.

    PubMed

    Downing, C A; Ahmady, B; Catlow, C R A; de Leeuw, N H

    2013-07-13

    There is no consensus as yet to account for the significant presence of water on the terrestrial planets, but suggested sources include direct hydrogen adsorption from the parent molecular cloud after the planets' formation, and delivery of hydrous material via comets or asteroids external to the zone of the terrestrial planets. Alternatively, a more recent idea is that water may have directly adsorbed onto the interstellar dust grains involved in planetary formation. In this work, we use electronic structure calculations based on the density functional theory to investigate and compare the bulk and {010} surface structures of the magnesium and iron end-members of the silicate mineral olivine, namely forsterite and fayalite, respectively. We also report our results on the adsorption of atomic hydrogen at the mineral surfaces, where our calculations show that there is no activation barrier to the adsorption of atomic hydrogen at these surfaces. Furthermore, different surface sites activate the atom to form either adsorbed hydride or proton species in the form of hydroxy groups on the same surface, which indicates that these mineral surfaces may have acted as catalytic sites in the immobilization and reaction of hydrogen atoms to form dihydrogen gas or water molecules. PMID:23734054

  5. Ionospheric Electron Density during Magnetically Active Times over Istanbul

    NASA Astrophysics Data System (ADS)

    Naz Erbaş, Bute; Kaymaz, Zerefsan; Ceren Moral, Aysegul; Emine Ceren Kalafatoglu Eyiguler, R. A..

    2016-07-01

    In this study, we analyze electron density variations over Istanbul using Dynasonde observations during the magnetically active times. In order to perform statistical analyses, we first determined magnetic storms and magnetospheric substorm intervals from October 2012 to October 2015 using Kyoto's magnetic index data. Corresponding ionospheric parameters, such as critical frequency of F2 region (foF2), maximum electron density height (hmF2), total electron density (TEC) etc. were retrieved from Dynasonde data base at Istanbul Technical University's Space Weather Laboratory. To understand the behavior of electron density during the magnetically active times, we remove the background quiet time variations first and then quantify the anomalies. In this presentation, we will report results from our preliminary analyses from the selected cases corresponding to the strong magnetic storms. Initial results show lower electron densities at noon times and higher electron densities in the late afternoon toward sunset times when compared to the electron densities of magnetically quiet times. We also compare the results with IRI and TIEGCM ionospheric models in order to understand the physical and dynamical causes of these variations. During the presentation we will also discuss the role of these changes during the magnetically active times on the GPS communications through ionosphere.

  6. Using soft computing techniques to predict corrected air permeability using Thomeer parameters, air porosity and grain density

    NASA Astrophysics Data System (ADS)

    Nooruddin, Hasan A.; Anifowose, Fatai; Abdulraheem, Abdulazeez

    2014-03-01

    Soft computing techniques are recently becoming very popular in the oil industry. A number of computational intelligence-based predictive methods have been widely applied in the industry with high prediction capabilities. Some of the popular methods include feed-forward neural networks, radial basis function network, generalized regression neural network, functional networks, support vector regression and adaptive network fuzzy inference system. A comparative study among most popular soft computing techniques is presented using a large dataset published in literature describing multimodal pore systems in the Arab D formation. The inputs to the models are air porosity, grain density, and Thomeer parameters obtained using mercury injection capillary pressure profiles. Corrected air permeability is the target variable. Applying developed permeability models in recent reservoir characterization workflow ensures consistency between micro and macro scale information represented mainly by Thomeer parameters and absolute permeability. The dataset was divided into two parts with 80% of data used for training and 20% for testing. The target permeability variable was transformed to the logarithmic scale as a pre-processing step and to show better correlations with the input variables. Statistical and graphical analysis of the results including permeability cross-plots and detailed error measures were created. In general, the comparative study showed very close results among the developed models. The feed-forward neural network permeability model showed the lowest average relative error, average absolute relative error, standard deviations of error and root means squares making it the best model for such problems. Adaptive network fuzzy inference system also showed very good results.

  7. Increasing total and biologically active chromium in wheat grain and spinach by spraying with chromium salts

    SciTech Connect

    Vicini, F.A.; Ellis, B.G.

    1981-06-01

    Recently, chromium has been shown to be necessary for glucose metabolism in man. But most plant species greatly restrict the uptake of Cr. This study was conducted to determine if both total and biologically active Cr could be increased in wheat grain or spinach by spraying the plants with either Cr/sub 2/(SO/sub 4/)/sub 3/ or Cr-EDTA. Concentrations of Cr in wheat grain were about doubled in a greenhouse experiment by spraying with either Cr source. Biologically active Cr (estimated by extraction with ethanol or NH/sub 4/OH) was increased from about 40 to greater than 50% of total Cr when wheat was sprayed with Cr salts. Total Cr in spinach leaves was increased by as much as 10-fold by spraying, with the sulfate source being more effective than the EDTA.

  8. Characterization of mutagenic activity in grain-based coffee-substitute blends and instant coffees

    SciTech Connect

    Johansson, M.A.E.; Knize, M.G.; Felton, J.S.; Jagerstad, M.

    1994-06-01

    Several grain-based coffee-substitute blends and instant coffees showed a mutagenic response in the Ames/Salmonella test using TA98, YG1024 and YG1O29 with metabolic activation. The beverage powders contained 150 to 500 TA98 and 1150 to 4050 YG1024 revertant colonies/gram, respectively. The mutagenic activity in the beverage powders was shown to be stable to heat and the products varied in resistance to acid nitrite treatment. Characterization of the mutagenic activity, using HPLC-and the Ames test of the collected fractions, showed the coffee-substitutes and instant coffees contain several mutagenic compounds, which are most likely aromatic amines.

  9. Activity of carbon dioxide fixation by anthers and leaves of cereal grains

    SciTech Connect

    Kirichenko, E.B.; Chernyad'ev, I.I.; Doman, N.G.; Talibullina, K.K.; Voronkova, T.V.

    1986-05-01

    This paper gives a comparative evaluation of the photosynthetic activity of anthers and flag leaves in winter wheat, rye, and triticale. The content of chlorophylls in anthers and leaves was determined. The activity of /sup 14/CO/sub 2/ fixation by anthers and leaf disks was determined by the radiometric method in a chamber floating on mercury under standard exposure conditions (0.1% concentration of /sup 14/CO/sub 2/, illumination of 15,000 1x, temperature of 23 C). Analyses were conducted in three replications and the results of typical biological experiments are cited. Data show that chlorophyll is actively synthesized in the anthers of cereal grains.

  10. Study of the interaction of solutes with Σ5 (013) tilt grain boundaries in iron using density-functional theory

    NASA Astrophysics Data System (ADS)

    Jin, Hao; Elfimov, Ilya; Militzer, Matthias

    2014-03-01

    Substitutional alloying elements significantly affect the recrystallization and austenite-ferrite phase transformation rates in steels. The atomistic mechanisms of their interaction with the interfaces are still largely unexplored. Using density functional theory, we determine the segregation energies between commonly used alloying elements and the Σ5 (013) tilt grain boundary in bcc iron. We find a strong solute-grain boundary interaction for Nb, Mo, and Ti that is consistent with experimental observations of the effects of these alloying elements on delaying recrystallization and the austenite-to-ferrite transformation in low-carbon steels. In addition, we compute the solute-solute interactions as a function of solute pair distance in the grain boundary, which suggest co-segregation for these large solutes at intermediate distances in striking contrast to the bulk.

  11. The Dynamic Density Bottle: A Make-and-Take, Guided Inquiry Activity on Density

    ERIC Educational Resources Information Center

    Kuntzleman, Thomas S.

    2015-01-01

    An activity is described wherein students observe dynamic floating and sinking behavior of plastic pieces in various liquids. The liquids and solids are all contained within a plastic bottle; the entire assembly is called a "density bottle". After completing a series of experiments that guides students to think about the relative…

  12. A grain-fluid mixture model to characterize the dynamics of active landslides in fine-grained soils

    NASA Astrophysics Data System (ADS)

    Spickermann, Anke; Toussaint, Renaud; Travelletti, Julien; Malet, Jean-Philippe; van Asch, Theo

    2013-04-01

    Dynamic continuum modeling of slow-moving landslides in fine-grained material is generally performed by means of visco-plastic models applying the approach of one-phase material. Shortcomings of this approach are the uncertainty of using physical realistic material parameters and that solid and fluid stresses are not considered separately. The objective of this work is to overcome the problems of the one-phase material approach by adopting the theory of grain-fluid mixture. Applying a two-phase model approach enables to distinguish explicitly between 25 e.g. solid friction stress, fluid shear stress (viscous stress), buoyancy and momentum exchange between solid and fluid (seepage). The model is implemented in a GIS (Geographic Information System) scripting language, which facilitate the use of complex three-dimensional (3D) topographies. The model is applied to and tested on the well-documented Super-Sauze landslide developed in reworked clay-shales. It is shown that the temporal and spatial varying moving pattern of the landslide can be reproduced. The numerical analysis reveals that viscous stresses produced by the fluid are irrelevant. Movements are mainly controlled by buoyancy, related to the evolution of the ground water level within the landslide that comes from water infiltration, and is introduced as a boundary condition. It is concluded that a two-phase, grain-fluid mixture model is convenient when landslide motion in fine-grained material is mainly controlled by the hydrological conditions (i.e. changes in pore water pressures), as in this example. The material parameters, as viscosity, calibrated to reproduce such landslide motion in models using the one-phase material approach, would take unrealistic values.

  13. On the Active Region Bright Grains Observed in the Transition Region Imaging Channels of IRIS

    NASA Astrophysics Data System (ADS)

    Skogsrud, H.; Rouppe van der Voort, L.; De Pontieu, B.

    2016-02-01

    The Interface Region Imaging Spectrograph (IRIS) provides spectroscopy and narrow band slit-jaw (SJI) imaging of the solar chromosphere and transition region at unprecedented spatial and temporal resolutions. Combined with high-resolution context spectral imaging of the photosphere and chromosphere as provided by the Swedish 1 m Solar Telescope (SST), we can now effectively trace dynamic phenomena through large parts of the solar atmosphere in both space and time. IRIS SJI 1400 images from active regions, which primarily sample the transition region with the Si iv 1394 and 1403 Å lines, reveal ubiquitous bright “grains” which are short-lived (two to five minute) bright roundish small patches of sizes 0.″5-1.″7 that generally move limbward with velocities up to about 30 km s-1. In this paper, we show that many bright grains are the result of chromospheric shocks impacting the transition region. These shocks are associated with dynamic fibrils (DFs), most commonly observed in Hα. We find that the grains show the strongest emission in the ascending phase of the DF, that the emission is strongest toward the top of the DF, and that the grains correspond to a blueshift and broadening of the Si iv lines. We note that the SJI 1400 grains can also be observed in the SJI 1330 channel which is dominated by C ii lines. Our observations show that a significant part of the active region transition region dynamics is driven from the chromosphere below rather than from coronal activity above. We conclude that the shocks that drive DFs also play an important role in the heating of the upper chromosphere and lower transition region.

  14. Anti-inflammatory Activity of Grains of Paradise (Aframomum melegueta Schum) Extract

    PubMed Central

    2015-01-01

    The ethanolic extract of grains of paradise (Aframomum melegueta Schum, Zingiberaceae) has been evaluated for inhibitory activity on cyclooxygenase-2 (COX-2) enzyme, in vivo for the anti-inflammatory activity and expression of several pro-inflammatory genes. Bioactivity-guided fractionation showed that the most active COX-2 inhibitory compound in the extract was [6]-paradol. [6]-Shogaol, another compound from the extract, was the most active inhibitory compound in pro-inflammatory gene expression assays. In a rat paw edema model, the whole extract reduced inflammation by 49% at 1000 mg/kg. Major gingerols from the extract [6]-paradol, [6]-gingerol, and [6]-shogaol reduced inflammation by 20, 25 and 38%. respectively when administered individually at a dose of 150 mg/kg. [6]-Shogaol efficacy was at the level of aspirin, used as a positive control. Grains of paradise extract has demonstrated an anti-inflammatory activity, which is in part due to the inhibition of COX-2 enzyme activity and expression of pro-inflammatory genes. PMID:25293633

  15. Fall Growth, Nutritive Value, and Energy Density for Cereal-Grain Forages in the North-Central United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Throughout the Southern Great Plains, wheat is managed frequently as a dual-purpose crop, but this production paradigm is not necessarily applicable throughout other regions of the United States, and a wider array of management options can be considered for forage-only uses of cereal grains. Our obj...

  16. Flume Experiments on the Influence of Salmon Spawning Density on Grain Stability and Bedload Transport in Gravel-bed Streams

    NASA Astrophysics Data System (ADS)

    Buxton, T. H.

    2015-12-01

    Salmon spawning in streams involves the female salmon digging a pit in the bed where she deposits eggs for fertilization before covering them with gravel excavated from the next pit upstream. Sequences of pit excavation and filling winnow fines, loosen sediment, and move bed material into a tailspill mound resembling the shape of a dune. Research suggests salmonid nests (redds) destabilize streambeds by reducing friction between loosened grains and converging flow that elevates shear stress on redd topography. However, bed stability may be enhanced by form drag from redds in clusters that lower shear stress on the granular bed, but this effect will vary with the proportion of the bed surface that is occupied by redds (P). I used simulated redds and water-worked ("unspawned") beds in a laboratory flume to evaluate these competing influences on grain stability and bedload transport rates with P=0.12, 0.34, and 0.41. Results indicate that competence (largest-grain) and reference transport rate estimates of critical conditions for particle entrainment inversely relate to P. Bedload transport increased as exponential functions of P and excess boundary shear stress. Therefore, redd form drag did not overcome the destabilizing effects of spawning. Instead, grain mobility and bedload transport increased with P because larger areas of the bed were composed of relatively loose, unstable grains and redd topography that experienced elevated shear stress. Consequently, the presence of redds in fish-bearing streams likely reduces the effects of sedimentation from landscape disturbance on stream habitats that salmon use for reproduction.

  17. High density of (pseudo) periodic twin-grain boundaries in molecular beam epitaxy-grown van der Waals heterostructure: MoTe2/MoS2

    NASA Astrophysics Data System (ADS)

    Diaz, Horacio Coy; Ma, Yujing; Chaghi, Redhouane; Batzill, Matthias

    2016-05-01

    Growth of transition metal dichalcogenide heterostructures by molecular beam epitaxy (MBE) promises synthesis of artificial van der Waals materials with controllable layer compositions and separations. Here, we show that MBE growth of 2H-MoTe2 monolayers on MoS2 substrates results in a high density of mirror-twins within the films. The grain boundaries are tellurium deficient, suggesting that Te-deficiency during growth causes their formation. Scanning tunneling microscopy and spectroscopy reveal that the grain boundaries arrange in a pseudo periodic "wagon wheel" pattern with only ˜2.6 nm repetition length. Defect states from these domain boundaries fill the band gap and thus give the monolayer an almost metallic property. The band gap states pin the Fermi-level in MoTe2 and thus determine the band-alignment in the MoTe2/MoS2 interface.

  18. Enhancement of wheat grain antioxidant activity by solid state fermentation with Grifola spp.

    PubMed

    Postemsky, Pablo; Curvetto, Néstor

    2014-05-01

    Grifola frondosa, Grifola gargal, and Grifola sordulenta are edible and medicinal mushrooms with antioxidant properties. To obtain wheat flour (Wf ) with a higher antioxidant activity than the one exhibited by regular Wf, solid state fermentation (SSF) of wheat grains with mycelia of those Grifola spp. was used to obtain biotransformed wheat grain (BWG) flour. The methanolic extract of control Wf and BWG flour of G. gargal, G. sordulenta, and G. frondosa (GfWG, GgWG, and GsWG, respectively) were studied for their radical scavenging (RS) activity against 2,2-diphenyl-1-picrylhydracyl (DPPH) and their Fe(III) reducing power (RP). The values for RS-EC50 decreased in BWG flour, therefore presenting a higher antioxidant activity: GgWG (0.56 mg/mL), GfWG (0.81 mg/mL), and GsWG (5.80 mg/mL) in comparison to Wf (57.60 mg/mL). The antioxidant content for this RS activity in terms of ascorbic acid content (RS-EQAA) was highest in GfWG, followed by GgWG and GsWG (71.73, 14.46, and 3.02 mg/g, respectively) and lowest in Wf (0.25 mg/g). The RP-EC50 values in GgWG, GfWG, and GsWG were low (0.55, 0.64, and 4.20 mg/mL, respectively) with respect to Wf (55.00 mg/mL). Compared with Wf (0.56 mg/g), the RP capacity in terms of ascorbic acid content (RP-EQAA) was very high in GfWG (193.67 mg/g) followed by GgWG and GsWG (31.42 and 8.74 mg/g, respectively). The high content in gallic acid equivalents was consistent with RS-EQ(AA) and RP-EQ(AA) contents. TLC revealed that antioxidant activity in BWG could be related to the presence of phenolic compounds. Thus, a valuable food alternative can easily be obtained with wheat grains, that is, by markedly increasing their antioxidant value through SSF with Grifola spp. PMID:24552201

  19. Active minimization of energy density in three-dimensional enclosures

    NASA Technical Reports Server (NTRS)

    Sommerfeldt, Scott D.

    1996-01-01

    The objective of this study was to further investigate and develop a novel approach for actively controlling the sound field in enclosures that is based on the acoustic energy density. Typically the acoustic field in an enclosure has been controlled by minimizing the sum of the squared pressures from several microphones distributed throughout the enclosure. The approach investigated in this study involved minimizing the acoustic energy density at the sensor locations, rather than the squared pressure. Research previous to this study in a simple one-dimensional enclosure showed that improved global attenuation of the acoustic field is often obtained by minimizing the energy density, rather than the pressure. The current study built on the previous research by extending the method of controlling the acoustic energy density to three-dimensional enclosures. The study was intended to help establish if improved control can still be expected in a more general enclosure. The study was designed to be both analytical/numerical and experimental in nature.

  20. Characteristics of Zero-Emission Activities in the Grain Cleaning and Flour Milling Industry

    NASA Astrophysics Data System (ADS)

    Zhang, Shifeng; Yamamoto, Kayoko; Izumi, Jun

    The aim of this study is to clarify the characteristics of zero-emission activities in the grain cleaning and flour milling industry. The findings of this study are summarized in the following two points: (1) There are very few common features among factories in regards to zero-emission efforts. High processing cost, lack of manpower, recycling traders and space for wastes classification are pointed out as difficulties, and information gathering from the outside of each company is not widespread. (2) Zero-emission activities differ according to factory, and the number of recycling categories is less than the number of waste categories, even though wheat is the only raw material. Ten different kinds of waste were identified, and the lack of means to recycle this waste was identified as a significant hindrance to zero emissions.

  1. Abscisic acid and aldehyde oxidase activity in maize ear leaf and grain relative to post-flowering photosynthetic capacity and grain-filling rate under different water/nitrogen treatments.

    PubMed

    Qin, Shujun; Zhang, Zongzheng; Ning, Tangyuan; Ren, Shizhong; Su, Licheng; Li, Zengjia

    2013-09-01

    This study investigated changes in leaf abscisic acid (ABA) concentrations and grain ABA concentrations in two maize cultivars and analyzed the following relationships under different water/nitrogen treatments: leaf ABA concentrations and photosynthetic parameters; leaf ABA concentrations and grain ABA concentrations; leaf/grain ABA concentrations and grain-filling parameters; and aldehyde oxidase (AO, EC 1.2.3.1) activities and ABA concentrations. The ear leaf average AO activities and ABA concentrations were lower in the controlled release urea treatments compared with the conventional urea treatments. The average AO activities in the grains were higher in the controlled release urea treatments, and the ABA concentrations were significantly increased at 11-30 DAF. The Pn and ABA concentrations in ear leaves were negatively correlated. And the Gmean were positively correlated with the grain ABA concentrations at 11-30 DAF and negatively correlated with the leaf ABA concentrations at 20 and 40-50 DAF. The grain ABA concentrations and leaf ABA concentrations were positively correlated. Thus, the Gmean were closely related to the AO activities and to the ear leaf and grain ABA concentrations. As compared to other treatments, the subsoiling and controlled release urea treatment promoted the uptake of water and nitrogen by maize, increased the photosynthetic capacity of the ear leaves, increased the grain-filling rate, and improved the movement of photosynthetic assimilates toward the developing grains. In the cultivar Z958, higher ABA concentrations in grains at 11-30 DAF and lower ABA concentrations in ear leaves during the late grain-filling stage, resulted in higher grain-filling rate and increased accumulation of photosynthetic products (relative to the cultivar D3). PMID:23770596

  2. COMMUNICATION: Neuron network activity scales exponentially with synapse density

    NASA Astrophysics Data System (ADS)

    Brewer, G. J.; Boehler, M. D.; Pearson, R. A.; DeMaris, A. A.; Ide, A. N.; Wheeler, B. C.

    2009-02-01

    Neuronal network output in the cortex as a function of synapse density during development has not been explicitly determined. Synaptic scaling in cortical brain networks seems to alter excitatory and inhibitory synaptic inputs to produce a representative rate of synaptic output. Here, we cultured rat hippocampal neurons over a three-week period to correlate synapse density with the increase in spontaneous spiking activity. We followed the network development as synapse formation and spike rate in two serum-free media optimized for either (a) neuron survival (Neurobasal/B27) or (b) spike rate (NbActiv4). We found that while synaptophysin synapse density increased linearly with development, spike rates increased exponentially in developing neuronal networks. Synaptic receptor components NR1, GluR1 and GABA-A also increase linearly but with more excitatory receptors than inhibitory. These results suggest that the brain's information processing capability gains more from increasing connectivity of the processing units than increasing processing units, much as Internet information flow increases much faster than the linear number of nodes and connections.

  3. Thermally activated switching at long time scales in exchange-coupled magnetic grains

    NASA Astrophysics Data System (ADS)

    Almudallal, Ahmad M.; Mercer, J. I.; Whitehead, J. P.; Plumer, M. L.; van Ek, J.; Fal, T. J.

    2015-10-01

    Rate coefficients of the Arrhenius-Néel form are calculated for thermally activated magnetic moment reversal for dual layer exchange-coupled composite (ECC) media based on the Langer formalism and are applied to study the sweep rate dependence of M H hysteresis loops as a function of the exchange coupling I between the layers. The individual grains are modeled as two exchange-coupled Stoner-Wohlfarth particles from which the minimum energy paths connecting the minimum energy states are calculated using a variant of the string method and the energy barriers and attempt frequencies calculated as a function of the applied field. The resultant rate equations describing the evolution of an ensemble of noninteracting ECC grains are then integrated numerically in an applied field with constant sweep rate R =-d H /d t and the magnetization calculated as a function of the applied field H . M H hysteresis loops are presented for a range of values I for sweep rates 105Oe /s ≤R ≤1010Oe /s and a figure of merit that quantifies the advantages of ECC media is proposed. M H hysteresis loops are also calculated based on the stochastic Landau-Lifshitz-Gilbert equations for 108Oe /s ≤R ≤1010Oe /s and are shown to be in good agreement with those obtained from the direct integration of rate equations. The results are also used to examine the accuracy of certain approximate models that reduce the complexity associated with the Langer-based formalism and which provide some useful insight into the reversal process and its dependence on the coupling strength and sweep rate. Of particular interest is the clustering of minimum energy states that are separated by relatively low-energy barriers into "metastates." It is shown that while approximating the reversal process in terms of "metastates" results in little loss of accuracy, it can reduce the run time of a kinetic Monte Carlo (KMC) simulation of the magnetic decay of an ensemble of dual layer ECC media by 2 -3 orders of magnitude

  4. Iminosugar inhibitors of carbohydrate-active enzymes that underpin cereal grain germination and endosperm metabolism.

    PubMed

    Andriotis, Vasilios M E; Rejzek, Martin; Rugen, Michael D; Svensson, Birte; Smith, Alison M; Field, Robert A

    2016-02-01

    Starch is a major energy store in plants. It provides most of the calories in the human diet and, as a bulk commodity, it is used across broad industry sectors. Starch synthesis and degradation are not fully understood, owing to challenging biochemistry at the liquid/solid interface and relatively limited knowledge about the nature and control of starch degradation in plants. Increased societal and commercial demand for enhanced yield and quality in starch crops requires a better understanding of starch metabolism as a whole. Here we review recent advances in understanding the roles of carbohydrate-active enzymes in starch degradation in cereal grains through complementary chemical and molecular genetics. These approaches have allowed us to start dissecting aspects of starch degradation and the interplay with cell-wall polysaccharide hydrolysis during germination. With a view to improving and diversifying the properties and uses of cereal grains, it is possible that starch degradation may be amenable to manipulation through genetic or chemical intervention at the level of cell wall metabolism, rather than simply in the starch degradation pathway per se. PMID:26862201

  5. A coarse-grained model to study calcium activation of the cardiac thin filament

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Schwartz, Steven

    2015-03-01

    Familial hypertrophic cardiomyopathy (FHC) is one of the most common heart disease caused by genetic mutations. Cardiac muscle contraction and relaxation involve regulation of crossbridge binding to the cardiac thin filament, which regulates actomyosin interactions through calcium-dependent alterations in the dynamics of cardiac troponin (cTn) and tropomyosin (Tm). An atomistic model of cTn complex interacting with Tm has been studied by our group. A more realistic model requires the inclusion of the dynamics of actin filament, which is almost 6 times larger than cTn and Tm in terms of atom numbers, and extensive sampling of the model becomes very resource-demanding. By using physics-based protein united-residue force field, we introduce a coarse-grained model to study the calcium activation of the thin filament resulting from cTn's allosteric regulation of Tm dynamics on actin. The time scale is much longer than that of all-atom molecular dynamics simulation because of the reduction of the degrees of freedom. The coarse-grained model is a good template for studying cardiac thin filament mutations that cause FHC, and reduces the cost of computational resources.

  6. Iminosugar inhibitors of carbohydrate-active enzymes that underpin cereal grain germination and endosperm metabolism

    PubMed Central

    Andriotis, Vasilios M. E.; Rejzek, Martin; Rugen, Michael D.; Svensson, Birte; Smith, Alison M.; Field, Robert A.

    2016-01-01

    Starch is a major energy store in plants. It provides most of the calories in the human diet and, as a bulk commodity, it is used across broad industry sectors. Starch synthesis and degradation are not fully understood, owing to challenging biochemistry at the liquid/solid interface and relatively limited knowledge about the nature and control of starch degradation in plants. Increased societal and commercial demand for enhanced yield and quality in starch crops requires a better understanding of starch metabolism as a whole. Here we review recent advances in understanding the roles of carbohydrate-active enzymes in starch degradation in cereal grains through complementary chemical and molecular genetics. These approaches have allowed us to start dissecting aspects of starch degradation and the interplay with cell-wall polysaccharide hydrolysis during germination. With a view to improving and diversifying the properties and uses of cereal grains, it is possible that starch degradation may be amenable to manipulation through genetic or chemical intervention at the level of cell wall metabolism, rather than simply in the starch degradation pathway per se. PMID:26862201

  7. Active zones of mammalian neuromuscular junctions: formation, density, and aging

    PubMed Central

    Nishimune, Hiroshi

    2012-01-01

    Presynaptic active zones are synaptic vesicle release sites that playessential roles in the function and pathology of mammalian neuromuscular junctions (NMJs). The molecular mechanisms of active zone organization utilize presynaptic voltage-dependent calcium channels (VDCCs) in NMJs as scaffolding proteins. VDCCs interact extracellularly with the muscle-derived synapse organizer, laminin β2, and interact intracellularly with active zone-specific proteins, such as Bassoon, CAST/Erc2/ELKS2alpha, ELKS, Piccolo, and RIMs. These molecular mechanisms are supported by studies in P/Q- and N-type VDCCs double-knockout mice, and they are consistent with the pathological conditions of Lambert-Eaton myasthenic syndrome and Pierson syndrome, which are caused by autoantibodies against VDCCs or by a laminin β2 mutation. During normal postnatal maturation, NMJs maintain the density of active zones, while NMJs triple their size. However, active zones become impaired during aging. Propitiously, muscle exercise ameliorates the active zone impairment in aged NMJs, which suggests the potential for therapeutic strategies. PMID:23252894

  8. Fungi Isolated from Maize (Zea mays L.) Grains and Production of Associated Enzyme Activities

    PubMed Central

    Lumi Abe, Camila Agnes; Bertechini Faria, Carla; Fernandes de Castro, Fausto; de Souza, Sandra Regina; dos Santos, Fabiane Cristina; Novais da Silva, Cleiltan; Tessmann, Dauri José; Barbosa-Tessmann, Ione Parra

    2015-01-01

    Filamentous fungi produce a great variety of enzymes, and research on their biotechnological potential has recently intensified. The objective of this work was to identify, at the species level, using DNA barcoding, 46 fungal isolates obtained from maize grains with rot symptoms. We also analyzed the production of extracellular amylases, cellulases, proteases and lipases of 33 of those fungal isolates. The enzymatic activities were evaluated by the formation of a clear halo or a white precipitate around the colonies in defined substrate media. The found fungi belong to the genera Talaromyces, Stenocarpella, Penicillium, Phlebiopsis, Cladosporium, Hyphopichia, Epicoccum, Trichoderma, Aspergillus, Irpex, Fusarium, Microdochium, Mucor and Sarocladium. In the genus Fusarium, the species Fusarium verticillioides was predominant and this genus presented the highest diversity, followed by the genera Aspergillus. The best genera for lipase production were Cladosporium and Penicillium; while Cladosporium, Aspergillus and Penicillium were best for cellulase activity; Hyphopichia, Aspergillus and Irpex for amylase activity; and Cladosporium and Sarocladium for proteases activity. In conclusion, a collection of fungi from maize seeds presenting rotten symptoms were obtained, among which exist important producers of hydrolases. PMID:26198227

  9. Fungi Isolated from Maize (Zea mays L.) Grains and Production of Associated Enzyme Activities.

    PubMed

    Abe, Camila Agnes Lumi; Faria, Carla Bertechini; de Castro, Fausto Fernandes; de Souza, Sandra Regina; dos Santos, Fabiane Cristina; da Silva, Cleiltan Novais; Tessmann, Dauri José; Barbosa-Tessmann, Ione Parra

    2015-01-01

    Filamentous fungi produce a great variety of enzymes, and research on their biotechnological potential has recently intensified. The objective of this work was to identify, at the species level, using DNA barcoding, 46 fungal isolates obtained from maize grains with rot symptoms. We also analyzed the production of extracellular amylases, cellulases, proteases and lipases of 33 of those fungal isolates. The enzymatic activities were evaluated by the formation of a clear halo or a white precipitate around the colonies in defined substrate media. The found fungi belong to the genera Talaromyces, Stenocarpella, Penicillium, Phlebiopsis, Cladosporium, Hyphopichia, Epicoccum, Trichoderma, Aspergillus, Irpex, Fusarium, Microdochium, Mucor and Sarocladium. In the genus Fusarium, the species Fusarium verticillioides was predominant and this genus presented the highest diversity, followed by the genera Aspergillus. The best genera for lipase production were Cladosporium and Penicillium; while Cladosporium, Aspergillus and Penicillium were best for cellulase activity; Hyphopichia, Aspergillus and Irpex for amylase activity; and Cladosporium and Sarocladium for proteases activity. In conclusion, a collection of fungi from maize seeds presenting rotten symptoms were obtained, among which exist important producers of hydrolases. PMID:26198227

  10. Nutrient Densities, Carbon:Nitrogen Ratios, and Midday Differential Canopy Temperature Impact Grain Yield of Stressed Oat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant architecture components (i.e., leaf area per plant, leaf area index, number of leaves and number of tillers per plant), midday differential canopy temperature, nutrient densities and C:N ratio were assessed in oat (Avena sativa L.) plants subjected to biotic stresses caused by aphid feeding or...

  11. A Method to Increase Current Density in a Mono Element Internal Tin Processed Superconductor Utilizing Zr Oxide to Refine Grain Size

    SciTech Connect

    Bruce A. Zeitlin, Eric Gregory

    2008-04-07

    The effect of Oxygen on (Nb1Zr)3Sn multifilament conductors manufactured by the Mono Element Internal Tin (MEIT) process was explored to improve the current density by refining the grain size. This followed work first done by General Electric on the Nb3Sn tape process. Techniques to fabricate the more difficult Nb1Zr composites are described and allowed fabrication of long lengths of .254 mm diameter wire from an 88.9 mm diameter billet. Oxygen was incorporated through the use of SnO2 mixed with tin powder and incorporated into the core. These were compared to samples with Ti+Sn and Cu+Sn cores. Heat treatments covered the range of 700 C to 1000 C. Current density vs. H, grain size, and reaction percentages are provided for the materials tested. The Oxygen gave superior results in the temperature range of 815-1000 C. It also stabilized the filament geometry of the array in comparison to the other additions at the higher temperatures. At 815 C a peak in layer Jc yielded values of 2537 A/mm2 at 12 T and 1353 A/mm2 at 15T, 8-22% and 30-73% greater respectively than 700 C values. Results with Oxygen at high temperature show the possibility of high speed continuous reaction of the composite versus the current batch or react in place methods. In general the Ti additions gave superior results at the lower reaction temperature. Future work is suggested to determine if the 815 C reaction temperature can lead to higher current density in high tin (Nb1Zr+Ox)3Sn conductors. A second technique incorporated oxygen directly into the Nb1Zr rods through heat treatment with Nb2O5 at 1100 C for 100 hours in vacuum prior to extrusion. The majority of the filaments reduced properly in the composite but some local variations in hardness led to breakage at smaller diameters.

  12. OsMAPK6, a mitogen-activated protein kinase, influences rice grain size and biomass production.

    PubMed

    Liu, Shuying; Hua, Lei; Dong, Sujun; Chen, Hongqi; Zhu, Xudong; Jiang, Jun'e; Zhang, Fang; Li, Yunhai; Fang, Xiaohua; Chen, Fan

    2015-11-01

    Grain size is an important agronomic trait in determining grain yield. However, the molecular mechanisms that determine the final grain size are not well understood. Here, we report the functional analysis of a rice (Oryza sativa L.) mutant, dwarf and small grain1 (dsg1), which displays pleiotropic phenotypes, including small grains, dwarfism and erect leaves. Cytological observations revealed that the small grain and dwarfism of dsg1 were mainly caused by the inhibition of cell proliferation. Map-based cloning revealed that DSG1 encoded a mitogen-activated protein kinase (MAPK), OsMAPK6. OsMAPK6 was mainly located in the nucleus and cytoplasm, and was ubiquitously distributed in various organs, predominately in spikelets and spikelet hulls, consistent with its role in grain size and biomass production. As a functional kinase, OsMAPK6 interacts strongly with OsMKK4, indicating that OsMKK4 is likely to be the upstream MAPK kinase of OsMAPK6 in rice. In addition, hormone sensitivity tests indicated that the dsg1 mutant was less sensitive to brassinosteroids (BRs). The endogenous BR levels were reduced in dsg1, and the expression of several BR signaling pathway genes and feedback-inhibited genes was altered in the dsg1 mutant, with or without exogenous BRs, indicating that OsMAPK6 may contribute to influence BR homeostasis and signaling. Thus, OsMAPK6, a MAPK, plays a pivotal role in grain size in rice, via cell proliferation, and BR signaling and homeostasis. PMID:26366992

  13. Caspase-Like Activities Accompany Programmed Cell Death Events in Developing Barley Grains

    PubMed Central

    Tran, Van; Weier, Diana; Radchuk, Ruslana; Thiel, Johannes; Radchuk, Volodymyr

    2014-01-01

    Programmed cell death is essential part of development and cell homeostasis of any multicellular organism. We have analyzed programmed cell death in developing barley caryopsis at histological, biochemical and molecular level. Caspase-1, -3, -4, -6 and -8-like activities increased with aging of pericarp coinciding with abundance of TUNEL positive nuclei and expression of HvVPE4 and HvPhS2 genes in the tissue. TUNEL-positive nuclei were also detected in nucellus and nucellar projection as well as in embryo surrounding region during early caryopsis development. Quantitative RT-PCR analysis of micro-dissected grain tissues revealed the expression of HvVPE2a, HvVPE2b, HvVPE2d, HvPhS2 and HvPhS3 genes exclusively in the nucellus/nucellar projection. The first increase in cascade of caspase-1, -3, -4, -6 and -8-like activities in the endosperm fraction may be related to programmed cell death in the nucellus and nucellar projection. The second increase of all above caspase-like activities including of caspase-9-like was detected in the maturating endosperm and coincided with expression of HvVPE1 and HvPhS1 genes as well as with degeneration of nuclei in starchy endosperm and transfer cells. The distribution of the TUNEL-positive nuclei, tissues-specific expression of genes encoding proteases with potential caspase activities and cascades of caspase-like activities suggest that each seed tissue follows individual pattern of development and disintegration, which however harmonizes with growth of the other tissues in order to achieve proper caryopsis development. PMID:25286287

  14. 76 FR 32988 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Grain...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-07

    ... published in the Federal Register on February 22, 2011 (76 FR 9815). Interested parties are encouraged to...; Grain Handling Facilities ACTION: Notice. SUMMARY: The Department of Labor (DOL) is submitting the..., ``Grain Handling Facilities (29 CFR 1910.272),'' to the Office of Management and Budget (OMB) for...

  15. Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y-Ba-Cu-O superconductor

    NASA Astrophysics Data System (ADS)

    Philippe, M. P.; Ainslie, M. D.; Wéra, L.; Fagnard, J.-F.; Dennis, A. R.; Shi, Y.-H.; Cardwell, D. A.; Vanderheyden, B.; Vanderbemden, P.

    2015-09-01

    Bulk, high temperature superconductors have significant potential for use as powerful permanent magnets in a variety of practical applications due to their ability to trap record magnetic fields. In this paper, soft ferromagnetic sections are combined with a bulk, large grain Y-Ba-Cu-O high temperature superconductor to form superconductor/ferromagnet hybrid structures. We study how the ferromagnetic sections influence the shape of the profile of the trapped magnetic induction at the surface of each structure and report the surface magnetic flux density measured by Hall probe mapping. These configurations have been modelled using a 2D axisymmetric finite element method based on the H -formulation and the results show excellent qualitative and quantitative agreement with the experimental measurements. The model has also been used to study the magnetic flux distribution and predict the behaviour for other constitutive laws and geometries. The results show that the ferromagnetic material acts as a magnetic shield, but the flux density and its gradient are enhanced on the face opposite to the ferromagnet. The thickness and saturation magnetization of the ferromagnetic material are important and a characteristic ferromagnet thickness d* is derived: below d*, saturation of the ferromagnet occurs, and above d*, a weak thickness-dependence is observed. The influence of the ferromagnet is observed even if its saturation magnetization is lower than the trapped flux density of the superconductor. Conversely, thin ferromagnetic discs can be driven to full saturation even though the outer magnetic field is much smaller than their saturation magnetization.

  16. Variation in the interaction between alleles of HvAPETALA2 and microRNA172 determines the density of grains on the barley inflorescence

    PubMed Central

    Houston, Kelly; McKim, Sarah M.; Comadran, Jordi; Bonar, Nicola; Druka, Ilze; Uzrek, Nicola; Cirillo, Elisa; Guzy-Wrobelska, Justyna; Collins, Nicholas C.; Halpin, Claire; Hansson, Mats; Dockter, Christoph; Druka, Arnis; Waugh, Robbie

    2013-01-01

    Within the cereal grasses, variation in inflorescence architecture results in a conspicuous morphological diversity that in crop species influences the yield of cereal grains. Although significant progress has been made in identifying some of the genes underlying this variation in maize and rice, in the temperate cereals, a group that includes wheat, barley, and rye, only the dosage-dependent and highly pleiotropic Q locus in hexaploid wheat has been molecularly characterized. Here we show that the characteristic variation in the density of grains along the inflorescence, or spike, of modern cultivated barley (Hordeum vulgare) is largely the consequence of a perturbed interaction between microRNA172 and its corresponding binding site in the mRNA of an APELATA2 (AP2)-like transcription factor, HvAP2. We used genome-wide association and biparental mapping to identify HvAP2. By comparing inflorescence development and HvAP2 transcript abundance in an extreme dense-spike mutant and its nearly isogenic WT line, we show that HvAP2 turnover driven by microRNA 172 regulates the length of a critical developmental window that is required for elongation of the inflorescence internodes. Our data indicate that this heterochronic change, an altered timing of developmental events caused by specific temporal variation in the efficiency of HvAP2 turnover, leads to the striking differences in the size and shape of the barley spike. PMID:24065816

  17. Stability and electronic structure of the low- Σ grain boundaries in CdTe: a density functional study

    SciTech Connect

    Park, Ji-Sang; Kang, Joongoo; Yang, Ji-Hui; Metzger, Wyatt; Wei, Su-Huai

    2015-01-15

    Using first-principles density functional calculations, we investigate the relative stability and electronic structure of the grain boundaries (GBs) in zinc-blende CdTe. Among the low-Σ-value symmetric tilt Σ3 (111), Σ3 (112), Σ5 (120), and Σ5 (130) GBs, we show that the Σ3 (111)GB is always the most stable due to the absence of dangling bonds and wrong bonds. The Σ5 (120) GBs, however, are shown to be more stable than the Σ3 (112) GBs, even though the former has a higher Σ value, and the latter is often used as a model system to study GB effects in zinc-blende semiconductors. Furthermore, we find that although containing wrong bonds, the Σ5 (120) GBs are electrically benign due to the short wrong bond lengths, and thus are not as harmful as the Σ3 (112) GBs also having wrong bonds but with longer bond lengths.

  18. A comparison of the levels of oil, carotenoids, and lipolytic enzyme activities in modern lines and hybrids of grain sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thirteen modern commercial grain sorghum hybrids and five sorghum lines were extracted and the levels of oil and carotenoids were analyzed and compared. The same samples were also evaluated for lipolytic enzyme activity. The oil content in all eighteen samples ranged from 3.21 to 4.29 wt%. Beta c...

  19. Introduction to Agronomy, Grain Crops, Weeds and Controls. A Learning Activity Pac in Agricultural Education Courses in Wisconsin.

    ERIC Educational Resources Information Center

    Wisconsin State Dept. of Public Instruction, Madison. Div. of Instructional Services.

    This learning activity pac contains information to help the teachers of high school vocational agriculture in the instructional area of agronomy. Each of the two main sections, grain crops and weeds and controls, includes teacher and student units for the section lessons. Teacher units include special instructions--equipment needed (film…

  20. Pyroclastic Eruptions in a Mars Climate Model: The Effects of Grain Size, Plume Height, Density, Geographical Location, and Season on Ash Distribution

    NASA Astrophysics Data System (ADS)

    Kerber, L. A.; Head, J. W.; Madeleine, J.; Wilson, L.; Forget, F.

    2010-12-01

    Pyroclastic volcanism has played a major role in the geologic history of the planet Mars. In addition to several highland patera features interpreted to be composed of pyroclastic material, there are a number of vast, fine-grained, friable deposits which may have a volcanic origin. The physical processes involved in the explosive eruption of magma, including the nucleation of bubbles, the fragmentation of magma, the incorporation of atmospheric gases, the formation of a buoyant plume, and the fall-out of individual pyroclasts has been modeled extensively for martian conditions [Wilson, L., J.W. Head (2007), Explosive volcanic eruptions on Mars: Tephra and accretionary lapilli formation, dispersal and recognition in the geologic record, J. Volcanol. Geotherm. Res. 163, 83-97]. We have further developed and expanded this original model in order to take into account differing temperature, pressure, and wind regimes found at different altitudes, at different geographic locations, and during different martian seasons. Using a well-established Mars global circulation model [LMD-GCM, Forget, F., F. Hourdin, R. Fournier, C. Hourdin, O. Talagrand (1999), Improved general circulation models of the martian atmosphere from the surface to above 80 km, J. Geophys. Res. 104, 24,155-24,176] we are able to link the volcanic eruption model of Wilson and Head (2007) to the spatially and temporally dynamic GCM temperature, pressure, and wind profiles to create three-dimensional maps of expected ash deposition on the surface. Here we present results exploring the effects of grain-size distribution, plume height, density of ash, latitude, season, and atmospheric pressure on the areal extent and shape of the resulting ash distribution. Our results show that grain-size distribution and plume height most strongly effect the distance traveled by the pyroclasts from the vent, while latitude and season can have a large effect on the direction in which the pyroclasts travel and the final shape

  1. Neutron Activation Analysis of Single Grains Recovered by the Hayabusa Spacecraft

    NASA Technical Reports Server (NTRS)

    Ebihara, M.; Sekimoto, S.; Hamajima, Y.; Yamamoto, M.; Kumagai, K.; Oura, Y.; Shirai, N.; Ireland. T. R.; Kitajima, F.; Nagao, K.; Nakamura, T.; Naraoka, H.; Noguchi, T.; Okazaki, R.; Tsuchiyama, A.; Uesugi, M.; Yurimoto, H.; Zolensky, M. E.; Abe, M.; Fujimura, A.; Mukai, T.; Yada, T.

    2011-01-01

    The Hayabusa spacecraft was launched on May 9, 2003 and reached an asteroid Itokawa (25143 Itokawa) in September 2005. After accomplishing several scientific observations, the spacecraft tried to collect the surface material of Itokawa by touching down to the asteroid in November. The spacecraft was then navigated for the earth. In encountering several difficulties, Hayabusa finally returned to the earth on June 12, 2010 and the entry capsule was successfully recovered. Initially, a g-scale of solid material was aimed to be captured into the entry capsule. Although the sample collection was not perfectly performed, it was hoped that some extraterrestrial material was stored into the capsule. After careful and extensive examination, more than 1500 particles were recognized visibly by microscopes, most of which were eventually judged to be extraterrestrial, highly probably originated from Itokawa [1]. Several years before the launching of the Hayabusa spacecraft, the initial analysis team was officially formed under the selection panel at ISAS. As a member of this team, we have been preparing for the initial inspection of the returned material from many scientific viewpoints [2]. Once the recovered material had been confirmed to be much less than 1 g, a scheme for the initial analysis was updated accordingly [3]. In this study, we aim to analyze tiny single grains by instrumental neutron activation analysis (INAA). As the initial analysis is to be started in mid-January, 2011, some progress for the initial analysis using INAA is described here. Analytical procedure

  2. Effect of Grain Size on Bacterial Penetration, Reproduction, and Metabolic Activity in Porous Glass Bead Chambers

    PubMed Central

    Sharma, Pramod K.; McInerney, Michael J.

    1994-01-01

    We determined the effects of grain size and nutritional conditions on the penetration rate and metabolic activity of Escherichia coli strains in anaerobic, nutrient-saturated chambers packed with different sizes of glass beads (diameters, 116 to 767 μm) under static conditions. The chambers had nearly equal porosities (38%) but different calculated pore sizes (range, 10 to 65 μm). Motile strains always penetrated faster than nonmotile strains, and nutrient conditions that resulted in faster growth rates (fermentative conditions versus nitrate-respiring conditions) resulted in faster penetration rates for both motile and nonmotile strains for all of the bead sizes tested. The penetration rate of nonmotile strains increased linearly when bead size was increased, while the penetration rate of motile strains became independent of the bead size when beads having diameters of 398 μm or greater were used. The rate of H2 production and the final amount of H2 produced decreased when bead size was decreased. However, the final protein concentrations were similar in chambers packed with 116-, 192-, and 281-μm beads and were only slightly higher in chambers packed with 398- and 767-μm beads. Our data indicated that conditions that favored faster growth rates also resulted in faster penetration times and that the lower penetration rates observed in chambers packed with small beads were due to restriction of bacterial activity in the small pores. The large increases in the final amount of hydrogen produced without corresponding increases in the final amount of protein made indicated that metabolism became uncoupled from cell mass biosynthesis as bead size increased, suggesting that pore size influenced the efficiency of substrate utilization. PMID:16349250

  3. Application of a new xylanase activity from Bacillus amyloliquefaciens XR44A in brewer's spent grain saccharification

    PubMed Central

    Amore, Antonella; Parameswaran, Binod; Kumar, Ramesh; Birolo, Leila; Vinciguerra, Roberto; Marcolongo, Loredana; Ionata, Elena; La Cara, Francesco; Pandey, Ashok; Faraco, Vincenza

    2015-01-01

    Background Cellulases and xylanases are the key enzymes involved in the conversion of lignocelluloses into fermentable sugars. Western Ghat region (India) has been recognized as an active hot spot for the isolation of new microorganisms. The aim of this work was to isolate new microorganisms producing cellulases and xylanases to be applied in brewer's spent grain saccharification. Results 93 microorganisms were isolated from Western Ghat and screened for the production of cellulase and xylanase activities. Fourteen cellulolytic and seven xylanolytic microorganisms were further screened in liquid culture. Particular attention was focused on the new isolate Bacillus amyloliquefaciens XR44A, producing xylanase activity up to 10.5 U mL−1. A novel endo-1,4-beta xylanase was identified combining zymography and proteomics and recognized as the main enzyme responsible for B. amyloliquefaciens XR44A xylanase activity. The new xylanase activity was partially characterized and its application in saccharification of brewer's spent grain, pretreated by aqueous ammonia soaking, was investigated. Conclusion The culture supernatant of B. amyloliquefaciens XR44A with xylanase activity allowed a recovery of around 43% xylose during brewer's spent grain saccharification, similar to the value obtained with a commercial xylanase from Trichoderma viride, and a maximum arabinose yield of 92%, around 2-fold higher than that achieved with the commercial xylanase. © 2014 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:25866429

  4. Critical current density behaviors across a grain boundary inclined to current with different angles in YBa2Cu3O7‑δ bicrystal junctions

    NASA Astrophysics Data System (ADS)

    Tao, Hua; Wei-Wei, Xu; Zheng-Ming, Ji; Da-Yuan, Guo; Qing-Yun, Wang; Xiang-Rong, Ma; Rui-Yu, Liang

    2016-06-01

    The critical current density behaviors across a bicrystal grain boundary (GB) inclined to the current direction with different angles in YBa2Cu3O7‑δ bicrystal junctions in magnetic fields are investigated. There are two main reasons for the difference in critical current density in junctions at different GB inclined angles in the same magnetic field: (i) the GB plane area determines the current carrying cross section; (ii) the vortex motion dynamics at the GB affects the critical current value when the vortex starts to move along the GB by Lorentz force. Furthermore, the vortex motion in a bicrystal GB is studied by investigating transverse (Hall) and longitudinal current–voltage characteristics (I–V xx and I–V xy ). It is found that the I–V xx curve diverges from linearity at a high driving current, while the I–V xy curve keeps nearly linear, which indicates the vortices inside the GB break out of the GB by Lorentz force. Project supported by the National Natural Science Foundation of China (Grant Nos. 61501222, 61371036, and 61571219) and the School Scientific Research Fund of Nanjing Institute of Technology, China (Grant Nos. YKJ201418).

  5. Density functional theory study of the influence of segregation of S or Fe impurities on electromigration in nano-grained copper interconnects

    SciTech Connect

    Shabalin, M.; Fuks, D.

    2015-05-21

    The reliability of the circuits in the modern microelectronic devices remains, during last decades, one of the key topics in research and gains an attention for improving the promising candidates for conductors. Improvement of materials for such applications can be obtained by both electronic and compositional optimization. Ab initio calculations using full potential linearized augmented plane wave method in density functional theory are applied to explain the reduction in electromigration effect in the vicinity of grain boundaries (GB) in nano-structured Cu due to the segregation of some additives to the GB. Several possible mechanisms are considered. It is demonstrated that S atoms segregated to GB of nano-structured Cu lead to the growth of effective mass of the electrons. This decreases the mobility of electrons in external electric field, and, correspondingly, the momentum that they may transfer to atoms in collisions. Fe atoms segregated to GB of Cu create new empty states at the top of the valance band. These non-occupied states may stimulate the current of holes when external electric field is applied to the system, creating the “hole wind” in the direction opposite to the current of electrons. Such “hole wind” will compensate the forces generated by the electron current and therefore will reduce the total momentum transfer between charge carriers and atoms. The calculated electron density maps show that S and Fe segregating to Cu GB increases the strength of covalent bonds reducing the diffusion of Cu atoms in the vicinity of GB.

  6. Changes in phenolic acids and antioxidant activity in Thai rice husk at five growth stages during grain development.

    PubMed

    Butsat, Sunan; Weerapreeyakul, Natthida; Siriamornpun, Sirithon

    2009-06-10

    Soluble and bound phenolic acids were isolated from Thai rice husk samples at five growth stages during grain development, and their antioxidant activities were evaluated. The results showed that ferulic acid was the major soluble phenolic acid in husk at all stages, and its concentration decreased steadily during grain development. The ratio of ferulic to p-coumaric acid was approximately 2:1 at all stages. The most abundant bound phenolic acid in all extracts was p-coumaric acid, followed by ferulic acid along with traces of syringic, vanilic, and p-hydroxybenzoic acids. Most of the antioxidant activities of soluble and bound phenolic acids in husk extracts were found at flowering stage, and there were high correlations of antioxidant activity to levels of soluble ferulic, gallic, and p-coumaric acids. PMID:19432451

  7. Upper critical field, critical current density and thermally activated flux flow in CaFFe0.9Co0.1As superconductor

    NASA Astrophysics Data System (ADS)

    Shekhar, Chandra; Srivastava, Amit; Kumar, Pramod; Srivastava, Pankaj; Srivastava, O. N.

    2012-04-01

    In this paper, we report the synthesis, structure, transition temperature, upper critical field, critical current density and thermally activated flux flow in the CaFFe0.9Co0.1As superconductor. Superconductivity arises at 23 K by Co substitution at the site of Fe atoms and the upper critical field is estimated as 102 T using the Werthamer-Helfand-Hohenberg formula. The flux-flow activation energy (U0/kB) varies from 3230 K and 4190 K in a field of 9 T and 1 T, respectively. At 2 K, the Jc is found to be approximately 4 × 103 A cm-2 and 0.3 × 103 A cm-2 in zero and 6 T field, respectively. Transmission electron microscopy analysis shows an amorphous region surrounding most of the grains which is likely to be present in the form of amorphous and weak link grain boundaries in this compound. It seems that most of the current is hindered by mis-aligned grains, amorphous grain boundaries and impurities, which are invariably found between the grains. The presence of the weakly linked granules and their weakly pinned intergranular Josephson vortices are responsible for both low Jc and the Arrhenius temperature dependence of resistivity.

  8. AHA! A Cool Salt Water/Density Activity--The Joy of Designing a Simple Experiment.

    ERIC Educational Resources Information Center

    Carlson, Gaylen R.

    1998-01-01

    Describes two science activities concerning water density and shares an idea for combining these activities into a third, completely new activity. Demonstrates the joy of rekindling the spirit of scientific thinking in a typical classroom. (PVD)

  9. Density increase due to active feedback in mirror machine

    NASA Astrophysics Data System (ADS)

    Seemann, Omri; Be'Ery, Ilan

    2014-10-01

    Mirror machines are one of the schemes for future fusion systems. Its main drawbacks are the flute instability and being open ended which results in plasma losses. A feedback system is used to stabilize the flute instability in a table top mirror machine with a continuous plasma source and RF heating. Under certain source density and temperature conditions, although the plasma was stabilized, plasma density increase was not measured. After decreasing the source density and increasing the temperature, Plasma density increase was achieved. It is theorized that these results are due to transition of the plasma main loss mechanism from collision dominated to instability dominated. In the former, the main density loss is through diffusion and In the latter, it is through flute instability which drives the plasma to the edge of the vacuum chamber. Future research directions are discussed for a planned machine which should achieve higher temperatures and better diagnostic capabilities. The research will focus on magnetic actuators and passive RF stabilization.

  10. Effects of Storage Duration and Temperature on the Chemical Composition, Microorganism Density, and In vitro Rumen Fermentation of Wet Brewers Grains

    PubMed Central

    Wang, B.; Luo, Y.; Myung, K. H.; Liu, J. X.

    2014-01-01

    This study aimed to investigate the effects of storage duration and temperature on the characteristics of wet brewers grains (WBG) as feeds for ruminant animals. Four storage temperatures (5°C, 15°C, 25°C, and 35°C) and four durations (0, 1, 2, and 3 d) were arranged in a 4×4 factorial design. Surface spoilage, chemical composition and microorganism density were analyzed. An in vitro gas test was also conducted to determine the pH, ammonia-nitrogen and volatile fatty acid (VFA) concentrations after 24 h incubation. Surface spoilage was apparent at higher temperatures such as 25°C and 35°C. Nutrients contents decreased concomitantly with prolonged storage times (p<0.01) and increasing temperatures (p<0.01). The amount of yeast and mold increased (p<0.05) with increasing storage times and temperatures. As storage temperature increased, gas production, in vitro disappearance of organic matter, pH, ammonia nitrogen and total VFA from the WBG in the rumen decreased (p<0.01). Our results indicate that lower storage temperature promotes longer beneficial use period. However, when storage temperature exceeds 35°C, WBG should be used within a day to prevent impairment of rumen fermentation in the subtropics such as Southeast China, where the temperature is typically above 35°C during summer. PMID:25050021

  11. 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.

  12. Catalytic activities of platinum nanotubes: a density functional study

    NASA Astrophysics Data System (ADS)

    Mukherjee, Prajna; Gupta, Bikash C.; Jena, Puru

    2015-10-01

    In this work we investigate the catalytic properties of platinum nanotubes using density functional theory based calculations. In particular, we study the dissociation of hydrogen and oxygen molecules as well as oxidation of CO molecules. The results indicate that platinum nanotubes have good catalytic properties and can be effectively used in converting CO molecule to CO2.

  13. Implementing an Inexpensive and Accurate Introductory Gas Density Activity with High School Students

    ERIC Educational Resources Information Center

    Cunningham, W. Patrick; Joseph, Christopher; Morey, Samantha; Santos Romo, Ana; Shope, Cullen; Strang, Jonathan; Yang, Kevin

    2015-01-01

    A simplified activity examined gas density while employing cost-efficient syringes in place of traditional glass bulbs. The exercise measured the density of methane, with very good accuracy and precision, in both first-year high school and AP chemistry settings. The participating students were tasked with finding the density of a gas. The…

  14. Sintering process and critical current density of low activation Mg11B2 superconductors from low temperature to high temperature

    NASA Astrophysics Data System (ADS)

    Cheng, Fang; Liu, Yongchang; Ma, Zongqing; Shahriar Al Hossain, Md; Somer, M.

    2016-08-01

    As the "low activation" superconductor, Mg11B2 has a potential application in superconducting coils for fusion reactor. In present work, the sintering process and critical current density of low activation Mg11B2 superconductors were systemically studied from low temperature to high temperature. It was found that the Jc and Hirr values of Mg11B2 bulks in present work are both obviously higher than that of those samples prepared in previous studies. Furthermore, the low-temperature sintered samples exhibit better Jc performance at high fields than the high-temperature sintered samples, due to strong grain boundaries pinning. On the other hand, the high-temperature sintered samples have higher Jc at low fields compared to low-temperature sintered samples, mainly owing to their better crystallinity and grain connectivity. The highest Jc value (2.20 ×105 A cm-2 at 20 K, self-field) is obtained in the Mg11B2 sample sintered at 850 °C for 45 min.

  15. Grain size effect on activation energy in spinel CoFe2O4 ceramic

    NASA Astrophysics Data System (ADS)

    Supriya, Sweety; Kumar, Sunil; Kar, Manoranjan

    2016-05-01

    Cobalt ferrite of different average crystallites (from nanocrystallite to micro crystallites) has been prepared by the Sol-Gel Method. The X-ray diffraction (XRD) analysis confirms the cubic spinel phase with no trace of impurity phases. The effect of annealing temperature on micro structure and electric transport properties as a function of frequency and temperature has been studied. It is observed that the electric impedance and conductivity are strongly dependent on grain size. The impedance spectroscopic study is employed to understand the electrical transport properties of cobalt ferrite.

  16. High Fc Density Particles Result in Binary Complement Activation but Tunable Macrophage Phagocytosis

    NASA Astrophysics Data System (ADS)

    Sulchek, Todd; Pacheco, Patricia; White, David

    2014-03-01

    Macrophage phagocytosis and complement system activation represent two key components of the immune system and both can be activated through the presentation of multiple Fc domains of IgG antibodies. We have created functionalized micro- and nanoparticles with various densities of Fc domains to understand the modulation of the immune system for eventual use as a novel immunomodulation platform. Phagocytosis assays were carried out by adding functionalized particles to macrophage cells and quantitatively determined using fluorescent microscopy and flow cytometry. Complement system activation by the functionalized particles in human serum was quantified with an enzyme immunoassay. Our phagocytosis assay revealed a strong dependence on particle size and Fc density. For small particles, as the Fc density increased, the number of particles phagocytosed also increased. Large particles were phagocytosed at significantly lower levels and showed no dependency on Fc density. Complement was successfully activated at levels comparable to positive controls for small particles at high Fc densities. However at low Fc densities, there is a significant decrease in complement activation. This result suggests a binary response for complement system activation with a threshold density for successful activation. Therefore, varying the Fc density on micro/nanoparticles resulted in a tunable response in macrophage phagocytosis while a more binary response for complement activation.

  17. A combined coarse-grained and all-atom simulation of TRPV1 channel gating and heat activation

    PubMed Central

    Qin, Feng

    2015-01-01

    The transient receptor potential (TRP) channels act as key sensors of various chemical and physical stimuli in eukaryotic cells. Despite years of study, the molecular mechanisms of TRP channel activation remain unclear. To elucidate the structural, dynamic, and energetic basis of gating in TRPV1 (a founding member of the TRPV subfamily), we performed coarse-grained modeling and all-atom molecular dynamics (MD) simulation based on the recently solved high resolution structures of the open and closed form of TRPV1. Our coarse-grained normal mode analysis captures two key modes of collective motions involved in the TRPV1 gating transition, featuring a quaternary twist motion of the transmembrane domains (TMDs) relative to the intracellular domains (ICDs). Our transition pathway modeling predicts a sequence of structural movements that propagate from the ICDs to the TMDs via key interface domains (including the membrane proximal domain and the C-terminal domain), leading to sequential opening of the selectivity filter followed by the lower gate in the channel pore (confirmed by modeling conformational changes induced by the activation of ICDs). The above findings of coarse-grained modeling are robust to perturbation by lipids. Finally, our MD simulation of the ICD identifies key residues that contribute differently to the nonpolar energy of the open and closed state, and these residues are predicted to control the temperature sensitivity of TRPV1 gating. These computational predictions offer new insights to the mechanism for heat activation of TRPV1 gating, and will guide our future electrophysiology and mutagenesis studies. PMID:25918362

  18. A coarse-grained model of thermally activated damage in heterogeneous media: Time evolution of the creep rate

    NASA Astrophysics Data System (ADS)

    Baxevanis, Th.

    2008-08-01

    A coarse-grained mean-field model is proposed where the damage enhanced creep of heterogeneous materials is described by the theory of absolute reaction rates. The dynamics of the proposed model, below a critical load, is characterized by an intensive precursor activity in the form of avalanches of microscopic breaking events that leads to a final catastrophic cascade occurring at a finite strain. Above the critical load, failure is instantaneous. The critical load is the static (elastic) fracture strength; thus the model is consistent with its time-independent analogue. Finally, the proposed model reproduces the experimental observations on the time evolution of the creep rate.

  19. Changes in the activities of starch metabolism enzymes in rice grains in response to elevated CO2 concentration

    NASA Astrophysics Data System (ADS)

    Xie, Li-Yong; Lin, Er-Da; Zhao, Hong-Liang; Feng, Yong-Xiang

    2016-05-01

    The global atmospheric CO2 concentration is currently (2012) 393.1 μmol mol-1, an increase of approximately 42 % over pre-industrial levels. In order to understand the responses of metabolic enzymes to elevated CO2 concentrations, an experiment was conducted using the Free Air CO2 Enrichment (FACE )system. Two conventional japonica rice varieties ( Oryza sativa L. ssp. japonica) grown in North China, Songjing 9 and Daohuaxiang 2, were used in this study. The activities of ADPG pyrophosphorylase, soluble and granule-bound starch synthases, and soluble and granule-bound starch branching enzymes were measured in rice grains, and the effects of elevated CO2 on the amylose and protein contents of the grains were analyzed. The results showed that elevated CO2 levels significantly increased the activity of ADPG pyrophosphorylase at day 8, 24, and 40 after flower, with maximum increases of 56.67 % for Songjing 9 and 21.31 % for Daohuaxiang 2. Similarly, the activities of starch synthesis enzymes increased significantly from the day 24 after flower to the day 40 after flower, with maximum increases of 36.81 % for Songjing 9 and 66.67 % for Daohuaxiang 2 in soluble starch synthase (SSS), and 25.00 % for Songjing 9 and 36.44 % for Daohuaxiang 2 in granule-bound starch synthase (GBSS), respectively. The elevated CO2 concentration significantly increased the activity of soluble starch branching enzyme (SSBE) at day 16, 32, and 40 after flower, and also significantly increased the activity of granule-bound starch branching enzyme (GBSBE) at day 8, 32, and 40 after flower. The elevated CO2 concentration increased the peak values of enzyme activity, and the timing of the activity peaks for SSS and GBSBE were earlier in Songjing 9 than in Daohuaxiang 2. There were obvious differences in developmental stages between the two varieties of rice, which indicated that the elevated CO2 concentration increased enzyme activity expression and starch synthesis, affecting the final contents

  20. Changes in the activities of starch metabolism enzymes in rice grains in response to elevated CO2 concentration.

    PubMed

    Xie, Li-Yong; Lin, Er-Da; Zhao, Hong-Liang; Feng, Yong-Xiang

    2016-05-01

    The global atmospheric CO(2) concentration is currently (2012) 393.1 μmol mol(-1), an increase of approximately 42 % over pre-industrial levels. In order to understand the responses of metabolic enzymes to elevated CO(2) concentrations, an experiment was conducted using the Free Air CO(2) Enrichment (FACE )system. Two conventional japonica rice varieties (Oryza sativa L. ssp. japonica) grown in North China, Songjing 9 and Daohuaxiang 2, were used in this study. The activities of ADPG pyrophosphorylase, soluble and granule-bound starch synthases, and soluble and granule-bound starch branching enzymes were measured in rice grains, and the effects of elevated CO(2) on the amylose and protein contents of the grains were analyzed. The results showed that elevated CO(2) levels significantly increased the activity of ADPG pyrophosphorylase at day 8, 24, and 40 after flower, with maximum increases of 56.67 % for Songjing 9 and 21.31 % for Daohuaxiang 2. Similarly, the activities of starch synthesis enzymes increased significantly from the day 24 after flower to the day 40 after flower, with maximum increases of 36.81 % for Songjing 9 and 66.67 % for Daohuaxiang 2 in soluble starch synthase (SSS), and 25.00 % for Songjing 9 and 36.44 % for Daohuaxiang 2 in granule-bound starch synthase (GBSS), respectively. The elevated CO(2) concentration significantly increased the activity of soluble starch branching enzyme (SSBE) at day 16, 32, and 40 after flower, and also significantly increased the activity of granule-bound starch branching enzyme (GBSBE) at day 8, 32, and 40 after flower. The elevated CO(2) concentration increased the peak values of enzyme activity, and the timing of the activity peaks for SSS and GBSBE were earlier in Songjing 9 than in Daohuaxiang 2. There were obvious differences in developmental stages between the two varieties of rice, which indicated that the elevated CO(2) concentration increased enzyme activity expression and starch synthesis, affecting the

  1. Chemotaxis of artificial microswimmers in active density waves

    NASA Astrophysics Data System (ADS)

    Geiseler, Alexander; Hänggi, Peter; Marchesoni, Fabio; Mulhern, Colm; Savel'ev, Sergey

    2016-07-01

    Living microorganisms are capable of a tactic response to external stimuli by swimming toward or away from the stimulus source; they do so by adapting their tactic signal transduction pathways to the environment. Their self-motility thus allows them to swim against a traveling tactic wave, whereas a simple fore-rear asymmetry argument would suggest the opposite. Their biomimetic counterpart, the artificial microswimmers, also propel themselves by harvesting kinetic energy from an active medium, but, in contrast, lack the adaptive capacity. Here we investigate the transport of artificial swimmers subject to traveling active waves and show, by means of analytical and numerical methods, that self-propelled particles can actually diffuse in either direction with respect to the wave, depending on its speed and waveform. Moreover, chiral swimmers, which move along spiraling trajectories, may diffuse preferably in a direction perpendicular to the active wave. Such a variety of tactic responses is explained by the modulation of the swimmer's diffusion inside traveling active pulses.

  2. Chemotaxis of artificial microswimmers in active density waves.

    PubMed

    Geiseler, Alexander; Hänggi, Peter; Marchesoni, Fabio; Mulhern, Colm; Savel'ev, Sergey

    2016-07-01

    Living microorganisms are capable of a tactic response to external stimuli by swimming toward or away from the stimulus source; they do so by adapting their tactic signal transduction pathways to the environment. Their self-motility thus allows them to swim against a traveling tactic wave, whereas a simple fore-rear asymmetry argument would suggest the opposite. Their biomimetic counterpart, the artificial microswimmers, also propel themselves by harvesting kinetic energy from an active medium, but, in contrast, lack the adaptive capacity. Here we investigate the transport of artificial swimmers subject to traveling active waves and show, by means of analytical and numerical methods, that self-propelled particles can actually diffuse in either direction with respect to the wave, depending on its speed and waveform. Moreover, chiral swimmers, which move along spiraling trajectories, may diffuse preferably in a direction perpendicular to the active wave. Such a variety of tactic responses is explained by the modulation of the swimmer's diffusion inside traveling active pulses. PMID:27575185

  3. [Physical activity/sports and bone mineral density].

    PubMed

    Inomoto, Takeaki

    2008-09-01

    This study observed the amount of exercise of Japanese schoolchildren as recorded by pedometer. Schools are necessary venues to increase children's mobility, but home environments are hotbeds for lack of exercise on weekends and during holidays and vacations. This research measured the L(2 - 4)BMD of 185 male and female primary schoolchildren using a DEXA method. Results showed significant partial correlations for measurements of boys' grip strength, boys' standing broad jump, and girls' grip strength, indicating the influence of mechanical stress. In a parallel study, L(2 - 4)BMD measurements for high school athletic club members (14 and 10 sports for boys and girls respectively) were taken, and it was found that the L(2 - 4)BMD (60 kg/weight) values were significantly higher than the control values for boys' boxing and weightlifting but significantly lower for boys' sumo. No significance was found in L(2 - 4)BMD (50 kg/weight) among the different girls' sports. From both studies, it was concluded that with approximately 2 hours of moderate play and exercise daily, the bone density of children rises with increase of overall muscle quantity, resulting in higher athletic ability and overall physical strength. PMID:18758041

  4. Long term hemodialysis aggravates lipolytic activity reduction and very low density, low density lipoproteins composition in chronic renal failure patients

    PubMed Central

    Mekki, Khedidja; Prost, Josiane; Remaoun, Mustapha; Belleville, Jacques; Bouchenak, Malika

    2009-01-01

    Background Dyslipidemia, particularly hypertriglyceridemia is common in uremia, and represents an independent risk factor for atherosclerosis. Methods To investigate the effects of hemodialysis (HD) duration on very low density lipoprotein (VLDL) and low density lipoprotein (LDL) compositions and lipopolytic activities, 20 patients on 5 to 7 years hemodialysis were followed-up during 9 years. Blood samples were drawn at T0 (beginning of the study), T1 (3 years after initiating study), T2 (6 years after initiating study) and T3 (9 years after initiating study). T0 was taken as reference. Results Triacylglycerols (TG) values were correlated with HD duration (r = 0.70, P < 0.05). An increase of total cholesterol was noted at T2 and T3. Lowered activity was observed for lipoprotein lipase (LPL) (-44%) at T3 and hepatic lipase (HL) (-29%) at T1, (-64%) at T2 and (-73%) at T3. Inverse relationships were found between HD duration and LPL activity (r = -0.63, P < 0.05), and HL activity (r = -0.71, P < 0.01). At T1, T2 and T3, high VLDL-amounts and VLDL-TG and decreased VLDL-phospholipids values were noted. Increased LDL-cholesteryl esters values were noted at T1 and T2 and in LDL-unesterified cholesterol at T2 and T3. Conclusion Despite hemodialysis duration, VLDL-LDL metabolism alterations are aggravated submitting patients to a greater risk of atherosclerosis. PMID:19709414

  5. Additivity, density fluctuations, and nonequilibrium thermodynamics for active Brownian particles

    NASA Astrophysics Data System (ADS)

    Chakraborti, Subhadip; Mishra, Shradha; Pradhan, Punyabrata

    2016-05-01

    Using an additivity property, we study particle-number fluctuations in a system of interacting self-propelled particles, called active Brownian particles (ABPs), which consists of repulsive disks with random self-propulsion velocities. From a fluctuation-response relation, a direct consequence of additivity, we formulate a thermodynamic theory which captures the previously observed features of nonequilibrium phase transition in the ABPs from a homogeneous fluid phase to an inhomogeneous phase of coexisting gas and liquid. We substantiate the predictions of additivity by analytically calculating the subsystem particle-number distributions in the homogeneous fluid phase away from criticality where analytically obtained distributions are compatible with simulations in the ABPs.

  6. Correlation between YBa{sub 2}Cu{sub 3}O{sub 7} nuclei density and the grain orientation of the CeO{sub 2} buffered Ni-W template of the second-generation superconducting wire.

    SciTech Connect

    Solovyov, V. F.; Abraimov, D.; Miller, D.; Li, Q.; Wiesmann, H.; Materials Science Division; BNL; Florida State Univ.

    2009-06-01

    The prime goal of the second-generation superconducting wire technology is to grow high-quality epitaxial layers of YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) superconductor using high-rate deposition on low-cost, kilometer-long substrates. We analyze the influence of Ni-W RABiTS{trademark} substrate grain misalignment on nucleation of epitaxial YBCO during metal-organic ex situ processing. Electron backscatter diffraction orientation maps are correlated with YBCO nuclei density obtained from scanning-electron microscopy. A critical Ni-W grain tilt misorientation angle of 8.5{sup o} was identified above which the YBCO nuclei density was observed to be extremely low, approaching zero. A proposed model explains the reduction in nuclei density as being due to the absence of (001) substrate terraces wide enough to accommodate the critical size for YBCO nuclei. This study emphasizes the strong effect of the out-of-plane tilt of substrate grains on superconducting properties of YBCO layers produced by metal-organic deposition.

  7. Differential regulation of grain sucrose accumulation and metabolism in Coffea arabica (Arabica) and Coffea canephora (Robusta) revealed through gene expression and enzyme activity analysis.

    PubMed

    Privat, Isabelle; Foucrier, Séverine; Prins, Anneke; Epalle, Thibaut; Eychenne, Magali; Kandalaft, Laurianne; Caillet, Victoria; Lin, Chenwei; Tanksley, Steve; Foyer, Christine; McCarthy, James

    2008-01-01

    * Coffea arabica (Arabica) and Coffea canephora (Robusta) are the two main cultivated species used for coffee bean production. Arabica genotypes generally produce a higher coffee quality than Robusta genotypes. Understanding the genetic basis for sucrose accumulation during coffee grain maturation is an important goal because sucrose is an important coffee flavor precursor. * Nine new Coffea genes encoding sucrose metabolism enzymes have been identified: sucrose phosphate synthase (CcSPS1, CcSPS2), sucrose phosphate phosphatase (CcSP1), cytoplasmic (CaInv3) and cell wall (CcInv4) invertases and four invertase inhibitors (CcInvI1, 2, 3, 4). * Activities and mRNA abundance of the sucrose metabolism enzymes were compared at different developmental stages in Arabica and Robusta grains, characterized by different sucrose contents in mature grain. * It is concluded that Robusta accumulates less sucrose than Arabica for two reasons: Robusta has higher sucrose synthase and acid invertase activities early in grain development - the expression of CcSS1 and CcInv2 appears to be crucial at this stage and Robusta has a lower SPS activity and low CcSPS1 expression at the final stages of grain development and hence has less capacity for sucrose re-synthesis. Regulation of vacuolar invertase CcInv2 activity by invertase inhibitors CcInvI2 and/or CcInvI3 during Arabica grain development is considered. PMID:18384509

  8. Transport of metabolically active bacteria in porous media:the effect of substrate, age, and grain size

    NASA Astrophysics Data System (ADS)

    Araujo, J. B.; Bradford, S. A.; Simunek, J.; Vereecken, H.; Klumpp, E.

    2008-12-01

    In our studies we sought to understand the biological processes affecting the microbial transport and retention of metabolically active Pseudomonas putida. To study the role of the metabolic state of the bacteria, we conducted a series of column experiments, varying saturation, substrate concentration, and grain size to help elucidate mechanisms present. Results show a significant difference between the metabolic state in the effluent, under unsaturated conditions, offset by grain-size effects. The presence of substrate appears to influence the breakthrough behavior of these cells in the smaller sand grains. We have also observed that the hydrophobicity of cells change according to their life-cycle. In addition we conducted a simple micro-model experiment, to observe if the cells behavior could be affected by their own motility. The results show that the cells travel with solution, suggesting that the flagella does not significantly contribute to movement through the porous media under these conditions. Furthermore, we monitored the cells in fresh batch solution and filtered solution under the microscope. In this case, we confirmed that during the stationary phase, when the cells are older there is an increased presence of aggregates, contrasting to the cells in the log-phase. There are also very long rod-shaped cells, which appear to undergo a process of cell division. The spatial distribution of these cells was also analyzed. The results indicate there are various mechanisms influencing the retention mechanisms of Pseudomonas putida, which are directly dependent on the metabolic state, substrate presence, and saturation of the porous media. The experimental data were analyzed using a mathematical model under a modified HYDRUS1D.

  9. Effects of Whole Grain, Fish and Bilberries on Serum Metabolic Profile and Lipid Transfer Protein Activities: A Randomized Trial (Sysdimet)

    PubMed Central

    Lankinen, Maria; Kolehmainen, Marjukka; Jääskeläinen, Tiina; Paananen, Jussi; Joukamo, Laura; Kangas, Antti J.; Soininen, Pasi; Poutanen, Kaisa; Mykkänen, Hannu; Gylling, Helena; Orešič, Matej; Jauhiainen, Matti; Ala-Korpela, Mika; Uusitupa, Matti; Schwab, Ursula

    2014-01-01

    Objective We studied the combined effects of wholegrain, fish and bilberries on serum metabolic profile and lipid transfer protein activities in subjects with the metabolic syndrome. Methods Altogether 131 subjects (40–70 y, BMI 26–39 kg/m2) with impaired glucose metabolism and features of the metabolic syndrome were randomized into three groups with 12-week periods according to a parallel study design. They consumed either: a) wholegrain and low postprandial insulin response grain products, fatty fish 3 times a week, and bilberries 3 portions per day (HealthyDiet), b) wholegrain and low postprandial insulin response grain products (WGED), or c) refined wheat breads as cereal products (Control). Altogether 106 subjects completed the study. Serum metabolic profile was studied using an NMR-based platform providing information on lipoprotein subclasses and lipids as well as low-molecular-weight metabolites. Results There were no significant differences in clinical characteristics between the groups at baseline or at the end of the intervention. Mixed model analyses revealed significant changes in lipid metabolites in the HealthyDiet group during the intervention compared to the Control group. All changes reflected increased polyunsaturation in plasma fatty acids, especially in n-3 PUFAs, while n-6 and n-7 fatty acids decreased. According to tertiles of changes in fish intake, a greater increase of fish intake was associated with increased concentration of large HDL particles, larger average diameter of HDL particles, and increased concentrations of large HDL lipid components, even though total levels of HDL cholesterol remained stable. Conclusions The results suggest that consumption of diet rich in whole grain, bilberries and especially fatty fish causes changes in HDL particles shifting their subclass distribution toward larger particles. These changes may be related to known protective functions of HDL such as reverse cholesterol transport and could partly

  10. Long-time atomistic evolution of grain boundary in nickel using the kinetic activation-relaxation technique

    NASA Astrophysics Data System (ADS)

    Mahmoud, Sami; Trochet, Mickaël; Restrepo, Oscar; Mousseau, Normand

    The microscopic mechanisms associated with the evolution of metallic materials are still a matter of debate as both experimental and numerical approaches fail to provide a detailed atomic picture of their time evolution. Here, we use the kinetic activation-relaxation technique (k-ART), an unbiased off-lattice kinetic Monte Carlo method with on-the-fly catalog building to overcome these limitations and follow the atomistic evolution of a 10.000-atom grain boundary Ni system over macroscopic time scales. We first characterize the kinetic properties of four different empirical potentials, the embedded atom method (EAM), the first and second modified embedded atom method (MEAM1NN and MEAM2NN respectively) and the Reax force field (ReaxFF) potentials. Comparing the energetics, the elastic effects and the diffusion mechanisms for systems with one to three vacancies and one to three self-interstitials in nickel simulated over second time scale, we conclude that ReaxFF and EAM potentials are closest to experimental values. We then proceed to study the long-time evolution of a grain boundary with the Reax forcefield and to offer a detailed description of its energy landscape, including the exact description of short and long-range effects on self-diffusion along the interface

  11. Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts.

    PubMed

    Sahraie, Nastaran Ranjbar; Kramm, Ulrike I; Steinberg, Julian; Zhang, Yuanjian; Thomas, Arne; Reier, Tobias; Paraknowitsch, Jens-Peter; Strasser, Peter

    2015-01-01

    Carbon materials doped with transition metal and nitrogen are highly active, non-precious metal catalysts for the electrochemical conversion of molecular oxygen in fuel cells, metal air batteries, and electrolytic processes. However, accurate measurement of their intrinsic turn-over frequency and active-site density based on metal centres in bulk and surface has remained difficult to date, which has hampered a more rational catalyst design. Here we report a successful quantification of bulk and surface-based active-site density and associated turn-over frequency values of mono- and bimetallic Fe/N-doped carbons using a combination of chemisorption, desorption and (57)Fe Mössbauer spectroscopy techniques. Our general approach yields an experimental descriptor for the intrinsic activity and the active-site utilization, aiding in the catalyst development process and enabling a previously unachieved level of understanding of reactivity trends owing to a deconvolution of site density and intrinsic activity. PMID:26486465

  12. Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts

    NASA Astrophysics Data System (ADS)

    Sahraie, Nastaran Ranjbar; Kramm, Ulrike I.; Steinberg, Julian; Zhang, Yuanjian; Thomas, Arne; Reier, Tobias; Paraknowitsch, Jens-Peter; Strasser, Peter

    2015-10-01

    Carbon materials doped with transition metal and nitrogen are highly active, non-precious metal catalysts for the electrochemical conversion of molecular oxygen in fuel cells, metal air batteries, and electrolytic processes. However, accurate measurement of their intrinsic turn-over frequency and active-site density based on metal centres in bulk and surface has remained difficult to date, which has hampered a more rational catalyst design. Here we report a successful quantification of bulk and surface-based active-site density and associated turn-over frequency values of mono- and bimetallic Fe/N-doped carbons using a combination of chemisorption, desorption and 57Fe Mössbauer spectroscopy techniques. Our general approach yields an experimental descriptor for the intrinsic activity and the active-site utilization, aiding in the catalyst development process and enabling a previously unachieved level of understanding of reactivity trends owing to a deconvolution of site density and intrinsic activity.

  13. Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts

    PubMed Central

    Sahraie, Nastaran Ranjbar; Kramm, Ulrike I.; Steinberg, Julian; Zhang, Yuanjian; Thomas, Arne; Reier, Tobias; Paraknowitsch, Jens-Peter; Strasser, Peter

    2015-01-01

    Carbon materials doped with transition metal and nitrogen are highly active, non-precious metal catalysts for the electrochemical conversion of molecular oxygen in fuel cells, metal air batteries, and electrolytic processes. However, accurate measurement of their intrinsic turn-over frequency and active-site density based on metal centres in bulk and surface has remained difficult to date, which has hampered a more rational catalyst design. Here we report a successful quantification of bulk and surface-based active-site density and associated turn-over frequency values of mono- and bimetallic Fe/N-doped carbons using a combination of chemisorption, desorption and 57Fe Mössbauer spectroscopy techniques. Our general approach yields an experimental descriptor for the intrinsic activity and the active-site utilization, aiding in the catalyst development process and enabling a previously unachieved level of understanding of reactivity trends owing to a deconvolution of site density and intrinsic activity. PMID:26486465

  14. Coarse-grained simulations of the gating current in the voltage-activated Kv1.2 channel

    PubMed Central

    Kim, Ilsoo; Warshel, Arieh

    2014-01-01

    Quantitative structure-based modeling of voltage activation of ion channels is very challenging. For example, it is very hard to reach converging results, by microscopic simulations while macroscopic treatments involve major uncertainties regarding key features. The current work overcomes some of the above challenges by using our recently developed coarse-grained (CG) model in simulating the activation of the Kv1.2 channel. The CG model has allowed us to explore problems that cannot be fully addressed at present by microscopic simulations, while providing insights on some features that are not usually considered in continuum models, including the distribution of the electrolytes between the membrane and the electrodes during the activation process and thus the physical nature of the gating current. Here, we demonstrate that the CG model yields realistic gating charges and free energy landscapes that allow us to simulate the fluctuating gating current in the activation processes. Our ability to simulate the time dependence of the fast gating current allows us to reproduce the observed trend and provides a clear description of its relationship to the landscape involved in the activation process. PMID:24464485

  15. Nanoscale grains, high irreversibility field and large critical current density as a function of high-energy ball milling time in C-doped magnesium diboride

    NASA Astrophysics Data System (ADS)

    Senkowicz, B. J.; Mungall, R. J.; Zhu, Y.; Jiang, J.; Voyles, P. M.; Hellstrom, E. E.; Larbalestier, D. C.

    2008-03-01

    Magnesium diboride (MgB2) powder was mechanically alloyed by high-energy ball milling with C to a composition of Mg(B0.95C0.05)2 and then sintered at 1000 °C in a hot isostatic press. Milling times varied from 1 to 3000 min. Full C incorporation required only 30-60 min of milling. The grain size of sintered samples decreased with increased milling time to <30 nm for 20-50 h of milling. Milling had a weak detrimental effect on the connectivity. A strong irreversibility field (H*) increase (from 13.3 to 17.2 T at 4.2 K) due to increased milling time was observed and correlated linearly with inverse grain size (1/d). As a result, the high-field Jc benefited greatly from lengthy powder milling. Jc (8 T, 4.2 K) peaked at>80 000 A cm-2 with 1200 min of milling compared with only ~26 000 A cm-2 for 60 min of milling. This non-compositional performance increase is attributed to grain refinement of the unsintered powder by milling, and to the probable suppression of grain growth by milling-induced MgO nanodispersions.

  16. Coarse-grained simulations of an active filament propelled by a self-generated solute gradient

    NASA Astrophysics Data System (ADS)

    Sarkar, Debarati; Thakur, Snigdha

    2016-03-01

    A self-propelling semiflexible filament exhibits a variety of dynamical states depending on the flexibility and activity of the filament. Here we investigate the dynamics of such an active filament using a bead-spring model with the explicit hydrodynamic interactions. The activity in the filament is incorporated by inserting chemically active dimers at regular intervals along the chain. The chemical reactions at the catalytic bead of the dimer produces a self-generated concentration gradient and gives sufficient fuel to exhibit self-propulsion for the filament. Depending upon the rigidity and the configuration, the polymeric filament exhibits three distinct types of spontaneous motion, namely, rotational, snaking, and translational motion. The self-propulsion velocity of the filament for various rigidity and sizes has been calculated, and the factors affecting the propulsion are identified.

  17. Coarse-grained simulation of molecular mechanisms of recovery in thermally activated shape-memory polymers

    NASA Astrophysics Data System (ADS)

    Abberton, Brendan C.; Liu, Wing Kam; Keten, Sinan

    2013-12-01

    Thermally actuated shape-memory polymers (SMPs) are capable of being programmed into a temporary shape and then recovering their permanent reference shape upon exposure to heat, which facilitates a phase transition that allows dramatic increase in molecular mobility. Experimental, analytical, and computational studies have established empirical relations of the thermomechanical behavior of SMPs that have been instrumental in device design. However, the underlying mechanisms of the recovery behavior and dependence on polymer microstructure remain to be fully understood for copolymer systems. This presents an opportunity for bottom-up studies through molecular modeling; however, the limited time-scales of atomistic simulations prohibit the study of key performance metrics pertaining to recovery. In order to elucidate the effects of phase fraction, recovery temperature, and deformation temperature on shape recovery, here we investigate the shape-memory behavior in a copolymer model with coarse-grained potentials using a two-phase molecular model that reproduces physical crosslinking. Our simulation protocol allows observation of upwards of 90% strain recovery in some cases, at time-scales that are on the order of the timescale of the relevant relaxation mechanism (stress relaxation in the unentangled soft-phase). Partial disintegration of the glassy phase during mechanical deformation is found to contribute to irrecoverable strain. Temperature dependence of the recovery indicates nearly full elastic recovery above the trigger temperature, which is near the glass-transition temperature of the rubbery switching matrix. We find that the trigger temperature is also directly correlated with the deformation temperature, indicating that deformation temperature influences the recovery temperatures required to obtain a given amount of shape recovery, until the plateau regions overlap above the transition region. Increasing the fraction of glassy phase results in higher strain

  18. Micro-phase assembly of active sites in a coarse-grained model of chromatin by Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Heermann, Dieter; Farmer, Barry; Pandey, Ras

    2011-03-01

    A coarse-grained model is used to study the self-assembly of active sites in a DNA (chromatin) chain. The chromosome is described by a bond-fluctuating chain of two types of nodes A (interacting) and B (non-interacting), distributed randomly with concentration C and 1 - C respectively. Active nodes interact with a Lennard-Jones (LJ) potential and execute their stochastic motion with the Metropolis algorithm. The depth of the LJ potential (f) , a measure of interaction strength and the concentration (C) of the active sites are varied. A number of local and global physical quantities are studied such as mobility (Mn) profile of each node, their local structural profile, root mean square (RMS) displacement (R) , radius of gyration (Rg) , and structure factor S (q) . We find that the chain segments assemble into microphase of blobs which requires higher concentration of active sites at weaker interaction. These findings are consistent with that of a dynamic loop model of chromatin on global (large) scale but differ at small scales. This work is supported in part by the Alexander von Humboldt foundation and AFRL.

  19. Density-Dependent Spacing Behaviour and Activity Budget in Pregnant, Domestic Goats (Capra hircus)

    PubMed Central

    Vas, Judit; Andersen, Inger Lise

    2015-01-01

    Very little is known about the spacing behaviour in social groups of domestic goats (Capra hircus) in the farm environment. In this experiment, we studied interindividual distances, movement patterns and activity budgets in pregnant goats housed at three different densities. Norwegian dairy goats were kept in stable social groups of six animals throughout pregnancy at 1, 2 or 3 m2 per individual and their spacing behaviours (i.e. distance travelled, nearest and furthest neighbour distance) and activity budgets (e.g. resting, feeding, social activities) were monitored. Observations were made in the first, second and last thirds of pregnancy in the mornings, at noon and in the afternoons of each of these phases (4.5 hours per observation period). The findings show that goats held at animal densities of 2 and 3 m2 moved longer distances when they had more space per animal and kept larger nearest and furthest neighbour distances when compared to the 1 m2 per animal density. Less feeding activity was observed at the high animal density compared to the medium and low density treatments. The phase of gestation also had an impact on almost all behavioural variables. Closer to parturition, animals moved further distances and the increase in nearest and furthest neighbour distance was more pronounced at the lower animal densities. During the last period of gestation, goats spent less time feeding and more on resting, social behaviours and engaging in other various activities. Our data suggest that more space per goat is needed for goats closer to parturition than in the early gestation phase. We concluded that in goats spacing behaviour is density-dependent and changes with stages of pregnancy and activities. Finally, the lower density allowed animals to express individual preferences regarding spacing behaviour which is important in ensuring good welfare in a farming situation. PMID:26657240

  20. Heterogeneous plastic deformation and Bauschinger effect in ultrafine-grained metals: atomistic simulations

    NASA Astrophysics Data System (ADS)

    Tsuru, Tomohito; Aoyagi, Yoshiteru; Kaji, Yoshiyuki; Shimokawa, Tomotsugu

    2016-03-01

    The effect of the dislocation density on yield strength and subsequent plastic deformation of ultrafine-grained metals was investigated in large-scale atomistic simulations. Polycrystalline models were constructed and uniaxial tension and compression were applied to elucidate the heterogeneous plastic deformation and the Bauschinger effect. The initial yield becomes heterogeneous as the dislocation density decreases owing to a wide range of Schmid factors of activated slip systems in each grain. A different mechanism of the Bauschinger effect was proposed, where the Bauschinger effect of ultrafine-grained metals is caused by the change in dislocation density in the process of forward and backward loadings.

  1. Active site densities, oxygen activation and adsorbed reactive oxygen in alcohol activation on npAu catalysts.

    PubMed

    Wang, Lu-Cun; Friend, C M; Fushimi, Rebecca; Madix, Robert J

    2016-07-01

    The activation of molecular O2 as well as the reactivity of adsorbed oxygen species is of central importance in aerobic selective oxidation chemistry on Au-based catalysts. Herein, we address the issue of O2 activation on unsupported nanoporous gold (npAu) catalysts by applying a transient pressure technique, a temporal analysis of products (TAP) reactor, to measure the saturation coverage of atomic oxygen, its collisional dissociation probability, the activation barrier for O2 dissociation, and the facility with which adsorbed O species activate methanol, the initial step in the catalytic cycle of esterification. The results from these experiments indicate that molecular O2 dissociation is associated with surface silver, that the density of reactive sites is quite low, that adsorbed oxygen atoms do not spill over from the sites of activation onto the surrounding surface, and that methanol reacts quite facilely with the adsorbed oxygen atoms. In addition, the O species from O2 dissociation exhibits reactivity for the selective oxidation of methanol but not for CO. The TAP experiments also revealed that the surface of the npAu catalyst is saturated with adsorbed O under steady state reaction conditions, at least for the pulse reaction. PMID:27376884

  2. Structure-reactivity relationships between fluorescent chromophores and antioxidant activity of grain and sweet sorghum seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenolic structures, such as tannins, are the putative cause of a variety of seed functions including bird/insect resistance and antioxidant activity. Structure-reactivity relationships are necessary to understand the influence of polyphenolic chromophore structures on the tannin content and fr...

  3. Evaluating the B-cell density with various activation functions using White Noise Path Integral Approach

    NASA Astrophysics Data System (ADS)

    Aban, C. J. G.; Bacolod, R. O.; Confesor, M. N. P.

    2015-06-01

    A The White Noise Path Integral Approach is used in evaluating the B-cell density or the number of B-cell per unit volume for a basic type of immune system response based on the modeling done by Perelson and Wiegel. From the scaling principles of Perelson [1], the B- cell density is obtained where antigens and antibodies mutates and activation function f(|S-SA|) is defined describing the interaction between a specific antigen and a B-cell. If the activation function f(|S-SA|) is held constant, the major form of the B-cell density evaluated using white noise analysis is similar to the form of the B-cell density obtained by Perelson and Wiegel using a differential approach.A piecewise linear functionis also used to describe the activation f(|S-SA|). If f(|S-SA|) is zero, the density decreases exponentially. If f(|S-SA|) = S-SA-SB, the B- cell density increases exponentially until it reaches a certain maximum value. For f(|S-SA|) = 2SA-SB-S, the behavior of B-cell density is oscillating and remains to be in small values.

  4. Detection and Classification of Finer-Grained Human Activities Based on Stepped-Frequency Continuous-Wave Through-Wall Radar

    PubMed Central

    Qi, Fugui; Liang, Fulai; Lv, Hao; Li, Chuantao; Chen, Fuming; Wang, Jianqi

    2016-01-01

    The through-wall detection and classification of human activities are critical for anti-terrorism, security, and disaster rescue operations. An effective through-wall detection and classification technology is proposed for finer-grained human activities such as piaffe, picking up an object, waving, jumping, standing with random micro-shakes, and breathing while sitting. A stepped-frequency continuous wave (SFCW) bio-radar sensor is first used to conduct through-wall detection of finer-grained human activities; Then, a comprehensive range accumulation time-frequency transform (CRATFR) based on inverse weight coefficients is proposed, which aims to strengthen the micro-Doppler features of finer activity signals. Finally, in combination with the effective eigenvalues extracted from the CRATFR spectrum, an optimal self-adaption support vector machine (OS-SVM) based on prior human position information is introduced to classify different finer-grained activities. At a fixed position (3 m) behind a wall, the classification accuracies of six activities performed by eight individuals were 98.78% and 93.23%, respectively, for the two scenarios defined in this paper. In the position-changing experiment, an average classification accuracy of 86.67% was obtained for five finer-grained activities (excluding breathing) of eight individuals within 6 m behind the wall for the most practical scenario, a significant improvement over the 79% accuracy of the current method. PMID:27314362

  5. Detection and Classification of Finer-Grained Human Activities Based on Stepped-Frequency Continuous-Wave Through-Wall Radar.

    PubMed

    Qi, Fugui; Liang, Fulai; Lv, Hao; Li, Chuantao; Chen, Fuming; Wang, Jianqi

    2016-01-01

    The through-wall detection and classification of human activities are critical for anti-terrorism, security, and disaster rescue operations. An effective through-wall detection and classification technology is proposed for finer-grained human activities such as piaffe, picking up an object, waving, jumping, standing with random micro-shakes, and breathing while sitting. A stepped-frequency continuous wave (SFCW) bio-radar sensor is first used to conduct through-wall detection of finer-grained human activities; Then, a comprehensive range accumulation time-frequency transform (CRATFR) based on inverse weight coefficients is proposed, which aims to strengthen the micro-Doppler features of finer activity signals. Finally, in combination with the effective eigenvalues extracted from the CRATFR spectrum, an optimal self-adaption support vector machine (OS-SVM) based on prior human position information is introduced to classify different finer-grained activities. At a fixed position (3 m) behind a wall, the classification accuracies of six activities performed by eight individuals were 98.78% and 93.23%, respectively, for the two scenarios defined in this paper. In the position-changing experiment, an average classification accuracy of 86.67% was obtained for five finer-grained activities (excluding breathing) of eight individuals within 6 m behind the wall for the most practical scenario, a significant improvement over the 79% accuracy of the current method. PMID:27314362

  6. Studies of microstructure/critical current density relationships for grain boundaries in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} bicrystals

    SciTech Connect

    Babcock, S.E.; Cai, Xue-Yu; Larbalestier, D.C.; Shin, D.H.; Zhang, Na; Gao, Yufei; Merkle, K.L.; Kaiser, D.L.; Zhang, Hong

    1992-11-01

    Results of coupled electromagnetic and microstructural studies of bicrystalline YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} specimens are described from a microstructural perspective. High-spatial-resolution transmission electron microscopy techniques (imaging and energy dispersive x-ray microanalysis) are used to probe the structure and composition of the grain boundaries. All of the boundaries studied possess microstructural features that are consistent with their specific electromagnetic character.

  7. Quantifying Leisure Physical Activity and Its Relation to Bone Density and Strength

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Purpose: Compare three published methods of quantifying physical activity (total activity, peak strain, and bone loading exposure [BLE] scores) and identify their associations with areal bone mineral density (aBMD), volumetric BMD (vBMD), and bone strength. Methods: Postmenopausal women (N = 239; me...

  8. Diode laser threshold current density and lasing wavelength as functions of active region thickness

    SciTech Connect

    Streifer, W.; Scifres, D.R.; Burnham, R.D.

    1983-03-01

    Based on a simple model of the band-to-band absorption of a diode laser active region, we formulatean expression for modal gain as a function of pumping current. Using this result yields expressions for threshold current density and lasing photon energy which depend on device parameters including active region thickness, laser length, internal losses, facet reflectivity, etc.

  9. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction.

    PubMed

    Beguerisse-Díaz, Mariano; Desikan, Radhika; Barahona, Mauricio

    2016-08-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction. PMID:27581482

  10. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction

    PubMed Central

    Desikan, Radhika

    2016-01-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction. PMID:27581482

  11. Antagonistic activity of Ocimum sanctum L. essential oil on growth and zearalenone production by Fusarium graminearum in maize grains

    PubMed Central

    Kalagatur, Naveen K.; Mudili, Venkataramana; Siddaiah, Chandranayaka; Gupta, Vijai K.; Natarajan, Gopalan; Sreepathi, Murali H.; Vardhan, Batra H.; Putcha, Venkata L. R.

    2015-01-01

    The present study was aimed to establish the antagonistic effects of Ocimum sanctum L. essential oil (OSEO) on growth and zearalenone (ZEA) production of Fusarium graminearum. GC–MS chemical profiling of OSEO revealed the existence of 43 compounds and the major compound was found to be eugenol (34.7%). DPPH free radical scavenging activity (IC50) of OSEO was determined to be 8.5 μg/mL. Minimum inhibitory concentration and minimum fungicidal concentration of OSEO on F. graminearum were recorded as 1250 and 1800 μg/mL, respectively. Scanning electron microscope observations showed significant micro morphological damage in OSEO exposed mycelia and spores compared to untreated control culture. Quantitative UHPLC studies revealed that OSEO negatively effected the production of ZEA; the concentration of toxin production was observed to be insignificant at 1500 μg/mL concentration of OSEO. On other hand ZEA concentration was quantified as 3.23 μg/mL in OSEO untreated control culture. Reverse transcriptase qPCR analysis of ZEA metabolic pathway genes (PKS4 and PKS13) revealed that increase in OSEO concentration (250–1500 μg/mL) significantly downregulated the expression of PKS4 and PKS13. These results were in agreement with the artificially contaminated maize grains as well. In conlusion, the antifungal and antimycotoxic effects of OSEO on F. graminearum in the present study reiterated that, the essential oil of O. sanctum could be a promising herbal fungicide in food processing industries as well as grain storage centers. PMID:26388846

  12. Antagonistic activity of Ocimum sanctum L. essential oil on growth and zearalenone production by Fusarium graminearum in maize grains.

    PubMed

    Kalagatur, Naveen K; Mudili, Venkataramana; Siddaiah, Chandranayaka; Gupta, Vijai K; Natarajan, Gopalan; Sreepathi, Murali H; Vardhan, Batra H; Putcha, Venkata L R

    2015-01-01

    The present study was aimed to establish the antagonistic effects of Ocimum sanctum L. essential oil (OSEO) on growth and zearalenone (ZEA) production of Fusarium graminearum. GC-MS chemical profiling of OSEO revealed the existence of 43 compounds and the major compound was found to be eugenol (34.7%). DPPH free radical scavenging activity (IC50) of OSEO was determined to be 8.5 μg/mL. Minimum inhibitory concentration and minimum fungicidal concentration of OSEO on F. graminearum were recorded as 1250 and 1800 μg/mL, respectively. Scanning electron microscope observations showed significant micro morphological damage in OSEO exposed mycelia and spores compared to untreated control culture. Quantitative UHPLC studies revealed that OSEO negatively effected the production of ZEA; the concentration of toxin production was observed to be insignificant at 1500 μg/mL concentration of OSEO. On other hand ZEA concentration was quantified as 3.23 μg/mL in OSEO untreated control culture. Reverse transcriptase qPCR analysis of ZEA metabolic pathway genes (PKS4 and PKS13) revealed that increase in OSEO concentration (250-1500 μg/mL) significantly downregulated the expression of PKS4 and PKS13. These results were in agreement with the artificially contaminated maize grains as well. In conlusion, the antifungal and antimycotoxic effects of OSEO on F. graminearum in the present study reiterated that, the essential oil of O. sanctum could be a promising herbal fungicide in food processing industries as well as grain storage centers. PMID:26388846

  13. Effect of dislocation and grain boundary on deformation mechanism in ultrafine-grained interstitial-free steel

    NASA Astrophysics Data System (ADS)

    Nakazawa, K.; Itoh, S.; Matsunaga, T.; Matsukawa, Y.; Satoh, Y.; Murase, Y.; Abe, H.

    2014-08-01

    Ultrafine-grained interstitial-free steel fabricated by the accumulative roll-bonding method was subjected to tensile tests and analyses of AFM, TEM and XRD to identify the effects of interaction between dislocations and grain boundaries (GB) on the deformation mechanism. The AFM analyses indicated that the main deformation mechanism of this material changed from dislocation motion to grain boundary sliding (GBS) with decreasing strain rate. TEM observations and XRD analysis revealed showed that dislocations piled up at GB and the dislocation density decreased with increasing strain. Those suggest the dislocations are absorbed into GB during deformation, activating slip-induced GBS.

  14. 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.

  15. 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.

  16. MYCOTOXIN CONTROL DURING GRAIN PROCESSING.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlling mycotoxin formation by fungi growing in and on cereal grains involves a multifactorial approach for defining multiple variables. The scope includes varietial (maturity, date, GMO) selection, tillage (time, depth), planting (density, spacing), fertilizion (type, amount, timing), irrigati...

  17. Grain physics and infrared dust emission in active galactic nucleus environments

    SciTech Connect

    Hensley, Brandon S.; Ostriker, Jeremiah P.; Ciotti, Luca

    2014-07-01

    We study the effects of a detailed dust treatment on the properties and evolution of early-type galaxies containing central black holes, as determined by active galactic nucleus (AGN) feedback. We find that during cooling flow episodes, radiation pressure on the dust in and interior to infalling shells of cold gas can greatly impact the amount of gas able to be accreted and therefore the frequency of AGN bursts. However, the overall hydrodynamic evolution of all models, including mass budget, is relatively robust to the assumptions on dust. We find that IR re-emission from hot dust can dominate the bolometric luminosity of the galaxy during the early stages of an AGN burst, reaching values in excess of 10{sup 46} erg s{sup –1}. The AGN-emitted UV is largely absorbed, but the optical depth in the IR does not exceed unity, so the radiation momentum input never exceeds L {sub BH}/c. We constrain the viability of our models by comparing the AGN duty cycle, broadband luminosities, dust mass, black hole mass, and other model predictions to current observations. These constraints force us towards models wherein the dust to metals ratios are ≅ 1% of the Galactic value, and only models with a dynamic dust to gas ratio are able to produce both quiescent galaxies consistent with observations and high obscured fractions during AGN 'on' phases. During AGN outbursts, we predict that a large fraction of the FIR luminosity can be attributed to warm dust emission (≅ 100 K) from dense dusty gas within ≤1 kpc reradiating the AGN UV emission.

  18. The Effect Of Electronic Energy Loss On Irradiation-induced Grain Growth In Nanocrystalline Oxides

    SciTech Connect

    Zhang, Yanwen; Aidhy, Dilpuneet S.; Varga, Tamas; Moll, Sandra; Edmondson, Philip D.; Namavar, Fereydoon; Jin, Ke; Ostrouchov, Christopher N.; Weber, William J.

    2014-03-03

    Grain growth of nanocrystalline materials is generally thermally activated, but can also be driven by irradiation at much lower temperature. In nanocrystalline ceria and zirconia, energetic ions deposit their energy to both atomic nuclei and electrons. Our experimental results have shown that irradiationinduced grain growth is dependent on the total energy deposited, where electronic energy loss and elastic collisions between atomic nuclei both contribute to the production of disorder and grain growth. Our atomistic simulations reveal that a high density of disorder near grain boundaries leads to locally rapid grain movement. The additive effect from both electronic excitation and atomic collision cascades on grain growth demonstrated in this work opens up new possibilities for controlling grain sizes to improve functionality of nanocrystalline materials.

  19. Ion density variation during seismic activity as measured by SROSS-C2 satellite

    NASA Astrophysics Data System (ADS)

    Bardhan, Ananna; Sharma, Dinesh Kumar; Kumar, Sarvesh

    ABSTRACT Ion density (O+ and H+) as a precursory parameter to seismic activity has been analysed from year 1995-1998, using RPA payload aboard SROSS-C2 satellite at an average altitude range of ~ 500 km over the Indian region. The details of seismic events during this period are downloaded from United State Geological Survey (USGS) website. Total of six events from the period of 1995-1998 are analyzed which are free from other perturbing phenomena like solar flares and thunderstorms/ lighting. It has been observed that there is considerable enhancement in average values of heavier ion - O+ density and decrease in lighter ion - H+ ion density during seismic affected time over the normal days. The increase in O+ ion density varies from 1.4 to 8.1 times and decrease in H+ ion density varies from 1.4 to 19.9 times compared to normal day's ion densities respectively. VLF emissions generated due to anomalous electric field during seimogenic activity could plausible candidature of change in ion concentration values during these events.

  20. Solid-substrate fermentation of wheat grains by mycelia of indigenous species of the genus Ganoderma (higher Basidiomycetes) to enhance the antioxidant activities.

    PubMed

    Subramaniam, Sarasvathy; Sabaratnam, Vikineswary; Kuppusamy, Umah Rani; Tan, Yee Shin

    2014-01-01

    Species of the genus Ganoderma are a cosmopolitan wood decaying white rot fungi, which has been used by the Asians for therapeutic purposes for centuries. In the present study, solid-substrate fermentation (SSF) of wheat grains (Triticum aestivum L.) was carried out with indigenous Ganoderma australe (KUM60813) and G. neo-japonicum (KUM61076) selected based on ethnomycological knowledge. G. lucidum (VITA GL) (a commercial strain) was also included in the study. Antioxidant activities of the crude ethanol and aqueous extracts of the fermented and unfermented wheat grains were investigated by ferric reducing antioxidant power (FRAP), Trolox equivalent antioxidant capacity (TEAC), diphenyl-1-picryl-hydrazyl (DPPH) free radical scavenging ability, and lipid peroxidation assay. Among the six mycelia extracts tested, the ethanol extract from wheat fermented with KUM61076 mycelia showed the most potent antioxidant activities, whereas the ethanol extract of wheat grains fermented with KUM60813 mycelia has a good potential in protecting frying oils against oxidation. Total phenolic content (TPC) in the ethanol extracts were higher than that in the aqueous extract. The wheat grains fermented with G. australe (KUM60813) and G. neo-japonicum KUM61076 have greater antioxidant potential compared to the commercially available G. lucidum (VITA GL). The antioxidant activities of the mycelia extracts had a positive correlation with their phenolic contents. Thus phenolic compounds may play a vital role in the antioxidant activities of the selected Ganoderma spp. PMID:24941167

  1. Multi-Cell High Latitude Density Structure Induced by Ion Drag during Active Periods

    NASA Astrophysics Data System (ADS)

    Walterscheid, R. L.; Crowley, G.

    2012-12-01

    During active periods two-cell convection patterns can produce four-cell density structure in the high-latitude thermosphere. During these periods density perturbations approaching 50% are possible. The occurrence of density structures that are more complex than the forcing itself suggests that the structure is caused by a profound change in the balance of forces. Using a General Circulation Model of the thermosphere, we compare the balance of forces in the upper and lower thermosphere during active and quiet times. We also examine the thermal structure caused by the dynamical adjustment to ion-drag forcing in relation to the other terms as a balanced state is approached. Simulations reveal that where ion drag is unable to accelerate the atmosphere into rapid motion (during quiet times or at low thermospheric altitudes) the Coriolis force is the dominant inertial term, and for fixed pressure levels centers of cyclonic motion are (per the usual meteorology relations) colder and denser than the surrounding air, while centers of anticyclonic motion are warmer and less dense. At fixed heights, densities are high in the evening anticyclonic gyre, and low in the dawn cyclonic gyre. However, this situation is radically changed during active periods when the atmosphere is spun up to rapid motion and the centrifugal force resulting from curved trajectories is the dominant inertial force. When this occurs, the high latitude anticyclones and cyclones both become centers of relatively cold high density air at fixed height. Cold low-density centers are found on both the dawn and dusk sides with a trough of low density air over the pole connecting them. This intrusion of low density splits the evening high density region that exists under quiet conditions giving the four cell pattern found by Crowley et al. [1989; 1996a, b]. Crowley, G., J. Schoendorf, R. G. Roble, F. A. Marcos (1996a). Cellular structures in the high latitude lower thermosphere, J. Geophys. Res. 101, 211

  2. Radiation activated CHK1/MEPE pathway may contribute to microgravity-induced bone density loss

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangming; Wang, Ping; Wang, Ya

    2015-11-01

    Bone density loss in astronauts on long-term space missions is a chief medical concern. Microgravity in space is the major cause of bone density loss (osteopenia), and it is believed that high linear energy transfer (LET) radiation in space exacerbates microgravity-induced bone density loss; however, the mechanism remains unclear. It is known that acidic serine- and aspartate-rich motif (ASARM) as a small peptide released by matrix extracellular phosphoglycoprotein (MEPE) promotes osteopenia. We previously discovered that MEPE interacted with checkpoint kinase 1 (CHK1) to protect CHK1 from ionizing radiation promoted degradation. In this study, we addressed whether the CHK1-MEPE pathway activated by radiation contributes to the effects of microgravity on bone density loss. We examined the CHK1, MEPE and secreted MEPE/ASARM levels in irradiated (1 Gy of X-ray) and rotated cultured human osteoblast cells. The results showed that radiation activated CHK1, decreased the levels of CHK1 and MEPE in human osteoblast cells and increased the release of MEPE/ASARM. These results suggest that the radiation-activated CHK1/MEPE pathway exacerbates the effects of microgravity on bone density loss, which may provide a novel targeting factor/pathway for a future countermeasure design that could contribute to reducing osteopenia in astronauts.

  3. Radiation activated CHK1/MEPE pathway may contribute to microgravity-induced bone density loss.

    PubMed

    Zhang, Xiangming; Wang, Ping; Wang, Ya

    2015-11-01

    Bone density loss in astronauts on long-term space missions is a chief medical concern. Microgravity in space is the major cause of bone density loss (osteopenia), and it is believed that high linear energy transfer (LET) radiation in space exacerbates microgravity-induced bone density loss; however, the mechanism remains unclear. It is known that acidic serine- and aspartate-rich motif (ASARM) as a small peptide released by matrix extracellular phosphoglycoprotein (MEPE) promotes osteopenia. We previously discovered that MEPE interacted with checkpoint kinase 1 (CHK1) to protect CHK1 from ionizing radiation promoted degradation. In this study, we addressed whether the CHK1-MEPE pathway activated by radiation contributes to the effects of microgravity on bone density loss. We examined the CHK1, MEPE and secreted MEPE/ASARM levels in irradiated (1 Gy of X-ray) and rotated cultured human osteoblast cells. The results showed that radiation activated CHK1, decreased the levels of CHK1 and MEPE in human osteoblast cells and increased the release of MEPE/ASARM. These results suggest that the radiation-activated CHK1/MEPE pathway exacerbates the effects of microgravity on bone density loss, which may provide a novel targeting factor/pathway for a future countermeasure design that could contribute to reducing osteopenia in astronauts. PMID:26553637

  4. Radiation activated CHK1/MEPE pathway may contribute to microgravity-induced bone density loss

    PubMed Central

    Zhang, Xiangming; Wang, Ping; Wang, Ya

    2016-01-01

    Bone density loss in astronauts on long-term space missions is a chief medical concern. Microgravity in space is the major cause of bone density loss (osteopenia), and it is believed that high linear energy transfer (LET) radiation in space exacerbates microgravity-induced bone density loss; however, the mechanism remains unclear. It is known that acidic serine- and aspartate-rich motif (ASARM) as a small peptide released by matrix extracellular phosphoglycoprotein (MEPE) promotes osteopenia. We previously discovered that MEPE interacted with checkpoint kinase 1 (CHK1) to protect CHK1 from ionizing radiation promoted degradation. In this study, we addressed whether the CHK1-MEPE pathway activated by radiation contributes to the effects of microgravity on bone density loss. We examined the CHK1, MEPE and secreted MEPE/ASARM levels in irradiated (1 Gy of X-ray) and rotated cultured human osteoblast cells. The results showed that radiation activated CHK1, decreased the levels of CHK1 and MEPE in human osteoblast cells and increased the release of MEPE/ASARM. These results suggest that the radiation-activated CHK1/MEPE pathway exacerbates the effects of microgravity on bone density loss, which may provide a novel targeting factor/pathway for a future countermeasure design that could contribute to reducing osteopenia in astronauts. PMID:26553637

  5. Correlation Between Low Bone Density and Disease Activity in Patients with Ulcerative Colitis

    PubMed Central

    Amiriani, Taghi; Besharat, Sima; Pourramezan, Zahra; Mirkarimi, Honey Sadat; Aghaei, Mehrdad; Joshaghani, Hamidreza; Roshandel, Gholamreza; Faghani, Maryam; Besharat, Mahsa

    2015-01-01

    BACKGROUND Different clinical and epidemiological studies using dual-energy X-ray absorptiometry have shown an increased prevalence of low bone mineral density in patients with inflammatory bowel diseases. The aim of this study was to assess the correlation between bone density and the disease activity in patients with ulcerative colitis. METHODS In this cross-sectional study, 52 patients with ulcerative colitis (duration of the disease less than 5 years) were invited to our research center, Golestan province, northeast of Iran, during February 2012 up to August 2012. A demographic checklist and Simple Clinical Colitis Activity Index was completed for each patients and 5 cc of blood sample was taken after obtaining the informed consent. We used colorimetry method for measuring serum calcium, UV method for serum phosphorus and ELISA for serum vitamin D. Dual-energy X-ray absorptiometry was done to evaluate the bone density. Data analysis was done using SPSS software version 16. Normality of data was assessed using Kolmogorov– Smirnov test. T and ANOVA tests were used if data had normal distribution. Mann-Whitney U or Kruskal-Wallis tests were used for the remaining data. Correlation between qualitative variables was evaluated by Chi-square test. RESULTS The mean (±SD) age and disease activity of the patients were 37.72 (±12.18) years and 4.78 (±1.98), respectively. There were no correlation between disease activity and mean age. Low bone density was seen in 30.8%, 11.5%, and 15.4% in spine, femur neck, and hip, respectively. There was no relationship between Z-score of total hip, spine, and femur neck with disease activity, age, and duration of disease (p>0.05). CONCLUSION Our results showed an acceptable rate of low bone density in patients with ulcerative colitis without any correlation with the disease activity index. PMID:25628850

  6. Correlation between low bone density and disease activity in patients with ulcerative colitis.

    PubMed

    Amiriani, Taghi; Besharat, Sima; Pourramezan, Zahra; Mirkarimi, Honey Sadat; Aghaei, Mehrdad; Joshaghani, Hamidreza; Roshandel, Gholamreza; Faghani, Maryam; Besharat, Mahsa

    2015-01-01

    BACKGROUND Different clinical and epidemiological studies using dual-energy X-ray absorptiometry have shown an increased prevalence of low bone mineral density in patients with inflammatory bowel diseases. The aim of this study was to assess the correlation between bone density and the disease activity in patients with ulcerative colitis. METHODS In this cross-sectional study, 52 patients with ulcerative colitis (duration of the disease less than 5 years) were invited to our research center, Golestan province, northeast of Iran, during February 2012 up to August 2012. A demographic checklist and Simple Clinical Colitis Activity Index was completed for each patients and 5 cc of blood sample was taken after obtaining the informed consent. We used colorimetry method for measuring serum calcium, UV method for serum phosphorus and ELISA for serum vitamin D. Dual-energy X-ray absorptiometry was done to evaluate the bone density. Data analysis was done using SPSS software version 16. Normality of data was assessed using Kolmogorov- Smirnov test. T and ANOVA tests were used if data had normal distribution. Mann-Whitney U or Kruskal-Wallis tests were used for the remaining data. Correlation between qualitative variables was evaluated by Chi-square test. RESULTS The mean (±SD) age and disease activity of the patients were 37.72 (±12.18) years and 4.78 (±1.98), respectively. There were no correlation between disease activity and mean age. Low bone density was seen in 30.8%, 11.5%, and 15.4% in spine, femur neck, and hip, respectively. There was no relationship between Z-score of total hip, spine, and femur neck with disease activity, age, and duration of disease (p>0.05). CONCLUSION Our results showed an acceptable rate of low bone density in patients with ulcerative colitis without any correlation with the disease activity index. PMID:25628850

  7. Roughness of Grain-scale Frictional Sliding Surfaces in the Actively Creeping Clay Gouge of the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Hadizadeh, J.; Candela, T.; Renard, F.; Williams, R.

    2011-12-01

    The gouge from 3197.2m measured depth within the active creep interval in the SAFOD borehole is unconsolidated and mainly composed of illite-smectite and Mg-rich-smectite clays interspersed with rounded lithic fragments and serpentinite porphyroclasts. We find evidence of deformation by frictional grain boundary sliding (FGBS) including a hierarchy of finely striated and slickenside surfaces. At the scale of the core sample, first order slip surfaces appear as mode II and III fractures cutting across a second set of slip surfaces that bound sliding grains in an anastomosing or lozenge-shape fabric. To characterize the different sliding orders and establish possible roughness scaling between the FGBS and outcrop-scale slip surfaces, we profiled the first and second order slip surfaces using white light interferometry (WLI) technique. Sample surfaces (10 samples; 20-140 mm2/sample) were differentiated on the basis of morphology and directly extracted from the core sample. Data was collected along 240 profiles using a Zygo NV7300 WLI scanning microscope at 1-2 points/micrometer distance. The 2-D roughness as represented by Hurst exponent (H) was determined via Fourier Power Spectrum, Root Mean Square and Wavelet methods for multiple profiles/surface, parallel (L) and perpendicular (A) to slip striations. The scanned surfaces were mostly strongly self-affine, definable by two Hurst exponents HL and HA. The difference in mean H values (HL-HA) for all measurements were 0.244 and 0.018 for the first and second order surfaces respectively suggesting that the first order surfaces were about 13 times more anisotropic than the second order surfaces. Based on this and previously published results we assume that the higher anisotropy of the first order surfaces is due to greater cumulative slip. The possible explanations are argued as follows. 1. The second order surfaces with larger total surface areas could be preferentially subject to resurfacing by processes such as

  8. Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography

    SciTech Connect

    Letellier, F.; Lardé, R.; Le Breton, J.-M.; Akmaldinov, K.; Auffret, S.; Dieny, B.; Baltz, V.

    2014-11-28

    Magnetic devices are often subject to thermal processing steps, such as field cooling to set exchange bias and annealing to crystallize amorphous magnetic electrodes. These processing steps may result in interdiffusion and the subsequent deterioration of magnetic properties. In this study, we investigated thermally-activated diffusion in Cu/Co/IrMn/Pt exchange biased polycrystalline thin-film structures using atom probe tomography. Images taken after annealing at 400 °C for 60 min revealed Mn diffusion into Co grains at the Co/IrMn interface and along Pt grain boundaries for the IrMn/Pt stack, i.e., a Harrison type C regime. Annealing at 500 °C showed further Mn diffusion into Co grains. At the IrMn/Pt interface, annealing at 500 °C led to a type B behavior since Mn diffusion was detected both along Pt grain boundaries and also into Pt grains. The deterioration of the films' exchange bias properties upon annealing was correlated to the observed diffusion. In particular, the topmost Pt capping layer thickness turned out to be crucial since a faster deterioration of the exchange bias properties for thicker caps was observed. This is consistent with the idea that Pt acts as a getter for Mn, drawing Mn out of the IrMn layer.

  9. Gene SGL, encoding a kinesin-like protein with transactivation activity, is involved in grain length and plant height in rice.

    PubMed

    Wu, Tao; Shen, Yingyue; Zheng, Ming; Yang, Chunyan; Chen, Yilin; Feng, Zhiming; Liu, Xi; Liu, Shijia; Chen, Zhijun; Lei, Cailin; Wang, Jiulin; Jiang, Ling; Wan, Jianmin

    2014-02-01

    Grain shape, a complex agronomic trait, plays an important role in determining yield and quality in rice. In the present study, a mutant named short grain length (sgl) was identified among explants of tissue cultured japonica variety Kita-ake. It exhibited reduced plant height (about 72 % of WT) and short grain length (about 80 % of WT). The reduced length was due to decreased cell elongation. The Short Grain Length (SGL) gene was isolated via map-based cloning and identified to encode a kinesin-like protein. SGL was expressed in the whole plant, especially in the stem and panicles. SGL was shown to have transcriptional activity. In onion epidermal cells, SGL protein was found mainly in the nucleus. Real-time PCR analyses showed that expression levels of genes involved in gibberellin metabolic pathways were affected in the sgl mutant. These data suggested that SGL protein may be involved in regulating GA synthesis and response genes, that in turn, regulates grain length and plant height. PMID:24170341

  10. Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography

    NASA Astrophysics Data System (ADS)

    Letellier, F.; Lechevallier, L.; Lardé, R.; Le Breton, J.-M.; Akmaldinov, K.; Auffret, S.; Dieny, B.; Baltz, V.

    2014-11-01

    Magnetic devices are often subject to thermal processing steps, such as field cooling to set exchange bias and annealing to crystallize amorphous magnetic electrodes. These processing steps may result in interdiffusion and the subsequent deterioration of magnetic properties. In this study, we investigated thermally-activated diffusion in Cu/Co/IrMn/Pt exchange biased polycrystalline thin-film structures using atom probe tomography. Images taken after annealing at 400 °C for 60 min revealed Mn diffusion into Co grains at the Co/IrMn interface and along Pt grain boundaries for the IrMn/Pt stack, i.e., a Harrison type C regime. Annealing at 500 °C showed further Mn diffusion into Co grains. At the IrMn/Pt interface, annealing at 500 °C led to a type B behavior since Mn diffusion was detected both along Pt grain boundaries and also into Pt grains. The deterioration of the films' exchange bias properties upon annealing was correlated to the observed diffusion. In particular, the topmost Pt capping layer thickness turned out to be crucial since a faster deterioration of the exchange bias properties for thicker caps was observed. This is consistent with the idea that Pt acts as a getter for Mn, drawing Mn out of the IrMn layer.

  11. Physical activity and lifestyle effects on bone mineral density among young adults: sociodemographic and biochemical analysis.

    PubMed

    Alghadir, Ahmad H; Gabr, Sami A; Al-Eisa, Einas

    2015-07-01

    [Purpose] The purpose of this study was to assess the possible role of physical activities, calcium consumption and lifestyle factors in both bone mineral density and bone metabolism indices in 350 young adult volunteers. [Subjects and Methods] All volunteers were recruited for the assessment of lifestyle behaviors and physical activity traits using validated questioners, and bone mineral density (BMD), serum osteocalcin (s-OC), bone-specific alkaline phosphatase (BAP), and calcium were estimated using dual-energy X-ray absorptiometry analysis, and immunoassay techniques. [Results] Male participants showed a significant increase in BMD along with an increase in bone metabolism markers compared with females in all groups. However, younger subjects showed a significant increase in BMD, OC, BAP, and calcium compared with older subjects. Osteoporosis was more common in older subjects linked with abnormal body mass index and waist circumference. Bone metabolism markers correlated positively with BMD, physically activity and negatively with osteoporosis in all stages. Also, moderate to higher calcium and milk intake correlated positively with higher BMD. However, low calcium and milk intake along with higher caffeine, and carbonated beverage consumption, and heavy cigarette smoking showed a negative effect on the status of bone mineral density. Stepwise regression analysis showed that life style factors including physical activity and demographic parameters explained around 58-69.8% of the bone mineral density variation in young adults especially females. [Conclusion] body mass index, physical activity, low calcium consumption, and abnormal lifestyle have role in bone mineral density and prognosis of osteoporosis in young adults. PMID:26311965

  12. Replacing with whole grains and legumes reduces Lp-PLA2 activities in plasma and PBMCs in patients with prediabetes or T2D1

    PubMed Central

    Kim, Minjoo; Jeung, Se Ri; Jeong, Tae-Sook; Lee, Sang-Hyun; Lee, Jong Ho

    2014-01-01

    To determine dietary effects on circulating lipoprotein-associated phospholipase A2 (Lp-PLA2) activity and enzyme activity in peripheral blood mononuclear cells (PBMCs), 99 patients with impaired fasting glucose, impaired glucose tolerance, or newly-diagnosed T2D were randomly assigned to either a control group (usual diet with refined rice) or the whole grain and legume group. Substitution of whole grains and legumes for refined rice was associated with the replacement of 7% of energy from carbohydrates with energy from protein (about 4%) and fat. After 12 weeks, the whole grain and legume group showed a significant decrease in fasting glucose, insulin, homeostasis model assessment-insulin resistance, hemoglobin A1c, malondialdehyde, plasma Lp-PLA2 activity, and oxidized LDL (ox-LDL), and an increase in LDL particle size. The changes (Δs) in these variables in the whole grain and legume group were significantly different from those in controls after adjustment for the baseline levels. When all subjects were considered, Δ plasma Lp-PLA2 positively correlated with Δ glucose, Δ PBMC Lp-PLA2, Δ ox-LDL, and Δ urinary 8-epi-prostaglandin F2α after being adjusted for confounding factors. The Δ PBMC Lp-PLA2 correlated positively with Δ glucose and Δ ox-LDL, and negatively with Δ LDL particle size and baseline PBMC Lp-PLA2. The substitution of whole grains and legumes for refined rice resulted in a reduction in Lp-PLA2 activities in plasma and PBMCs partly through improved glycemic control, increased consumption of protein relative to carbohydrate, and reduced lipid peroxides. PMID:24904022

  13. Acaricidal and Insecticidal Activities of Essential Oils against a Stored-Food Mite and Stored-Grain Insects.

    PubMed

    Song, Ja-Eun; Kim, Jeong-Moon; Lee, Na-Hyun; Yang, Ji-Yeon; Lee, Hoi-Seon

    2016-01-01

    Twenty plant-derived oils were evaluated for their acaricidal and insecticidal activities against Sitotroga cerealella, Sitophilus oryzae, Sitophilus zeamais, and Tyrophagus putrescentiae adults, by using the fumigant and filter paper diffusion methods. Responses varied with bioassay systems, insect or mite species, plant oils, and exposure time. Based on the 50% lethal dose (LD50) values against S. oryzae and S. zeamais in the fumigant bioassay, Anethum graveolens oil (4.12 and 1.12 μg/cm(3), respectively) induced the highest mortality, followed by Achillea millefolium (21.92 and 14.91 μg/cm(3)) and Eucalyptus dives (28.02 and 24.02 μg/cm(3)) oils, respectively. The most toxic oil based on the 50% lethal concentration values against T. putrescentiae was E. dives (3.13 μg/cm(3)), followed by Melaleuca leucadendron (3.93 μg/cm(3)) and Leptospermum pertersonii (4.41 μg/cm(3)). Neroli birgard oil (1.70 μg/cm(3)) was the most toxic based on the LD50 values against S. cerealella, followed by Citrus aurantium (1.80 μg/cm(3)) and Artemisia vulgaris (1.81 μg/cm(3)). The insecticidal and acaricidal activities of the plant oils in the filter paper diffusion bioassay were similar to those in the fumigant bioassay. In comparison, A. millefolium, A. graveolens, and E. dives oils were more effective against S. oryzae and S. zeamais in the fumigant bioassay than in the contact bioassay. These results indicate that the insecticidal activity of the three plant oils against S. oryzae and S. zeamais may be due to their fumigant action. Acaricidal activities of the A. millefolium, A. graveolens, and E. dives oils against T. putrescentiae were 2.62, 1.11, and 122 times higher than that of benzyl benzoate in the contact bioassay. These results indicate that A. millefolium, A. graveolens, and E. dives oils have potential for development as agents to control stored-grain insects and mites. PMID:26735047

  14. Communication: Active space decomposition with multiple sites: Density matrix renormalization group algorithm

    SciTech Connect

    Parker, Shane M.; Shiozaki, Toru

    2014-12-07

    We extend the active space decomposition method, recently developed by us, to more than two active sites using the density matrix renormalization group algorithm. The fragment wave functions are described by complete or restricted active-space wave functions. Numerical results are shown on a benzene pentamer and a perylene diimide trimer. It is found that the truncation errors in our method decrease almost exponentially with respect to the number of renormalization states M, allowing for numerically exact calculations (to a few μE{sub h} or less) with M = 128 in both cases. This rapid convergence is because the renormalization steps are used only for the interfragment electron correlation.

  15. Presolar Grains in Indarch

    NASA Astrophysics Data System (ADS)

    Gao, X.; Nittler, L. R.; Swan, P. D.; Walker, R. M.

    1995-09-01

    We report results for the EH(4) Indarch. Earlier work [1] found 20 micrometers clumps of sub-micron SiC whose presolar nature was inferred from step-wise combustion, noble gas [2], and ion probe isotopic measurements. Our results indicate that the clumps were an artifact of sample preparation. Our sample was first cleaned using 6N HCl, and water and isopropanol rinses, then powdered and reacted with HCl-HF/HCl, KOH, and H3BO3-HCl/HCl giving a C-rich residue 1.14 wt.% of the original. X-ray mapping showed SiC grains and 5x as many Si3N4 grains, but no fine-grained clumps. Large (6 micrometers to 20 micrometers) C-rich spheroids were also present. The sample was further treated with KOH/HNO3 and NH3H2O; attempts to do density-separates were unsuccessful. An aliquot was treated with perchloric acid and separated into <1 micrometers and >1 micrometer fractions. SEM-EDS measurements of 73 (<1 micrometer) grains showed 44 SiC, 19 Si3N4, 4 C only, and 6 C with minor Si (both the C and Si in these particles are isotopically normal). A similar distribution of species was found for 37 (>1 micrometer) grains with the addition of 2 spinel and one Al2O3 grains. The whole rock concentration of SiC was 5.8 ppm, higher than previous determinations [1,3,9]. Confirming earlier suggestions [1,2], we find that SiC in Indarch is much finer-grained than in Murchison; about 2/3 of the mass is in grains <=0.3 micrometers compared to only about 4% for Murchison. This may represent size-sorting in the nebula or selective destruction of fine-grained material. Ion probe measurements of 22 (1-3 micrometers) grains gave isotopic results in the range previously measured for Murchison SiCs [4]. Several normal Si3N4 grains (>1 micron) were measured; probably exsolution products similar to those in Qingzhen [7]. Ion mapping was used to search for presolar oxide grains using previously developed techniques [5]. Seven candidate grains out of ~1000 were found. Multiple imaging confirmed an ^(16)O/^(18

  16. Correlation Between the Extent of Catalytic Activity and Charge Density of Montmorillonites

    PubMed Central

    Steudel, Annett; Emmerich, Katja; Lagaly, Gerhard; Schuhmann, Rainer

    2010-01-01

    Abstract The clay mineral montmorillonite is a member of the phyllosilicate group of minerals, which has been detected on martian soil. Montmorillonite catalyzes the condensation of activated monomers to form RNA-like oligomers. Extent of catalysis, that is, the yield of oligomers, and the length of the longest oligomer formed in these reactions widely varies with the source of montmorillonite (i.e., the locality where the mineral is mined). This study was undertaken to establish whether there exists a correlation between the extent of catalytic property and the charge density of montmorillonites. Charge density was determined by saturating the montmorillonites with alkyl ammonium cations that contained increasing lengths of alkyl chains, [CH3-(CH2)n-NH3]+, where n = 3–16 and 18, and then measuring d(001), interlayer spacing of the resulting montmorillonite-alkyl ammonium-montmorillonite complex by X-ray diffractometry (XRD). Results demonstrate that catalytic activity of montmorillonites with lower charge density is superior to that of higher charge density montmorillonite. They produce longer oligomers that contain 9 to 10 monomer units, while montmorillonite with high charge density catalyzes the formation of oligomers that contain only 4 monomer units. The charge density of montmorillonites can also be calculated from the chemical composition if elemental analysis data of the pure mineral are available. In the next mission to Mars, CheMin (Chemistry and Mineralogy), a combined X-ray diffraction/X-ray fluorescence instrument, will provide information on the mineralogical and elemental analysis of the samples. Possible significance of these results for planning the future missions to Mars for the search of organic compounds and extinct or extant life is discussed. Key Words: Mars—Origin of life—Montmorillonite—Mineral catalysis—Layer charge density—X–ray diffractometry. Astrobiology 10, 743–749. PMID:20854214

  17. Correlation between the extent of catalytic activity and charge density of montmorillonites.

    PubMed

    Ertem, Gözen; Steudel, Annett; Emmerich, Katja; Lagaly, Gerhard; Schuhmann, Rainer

    2010-09-01

    The clay mineral montmorillonite is a member of the phyllosilicate group of minerals, which has been detected on martian soil. Montmorillonite catalyzes the condensation of activated monomers to form RNA-like oligomers. Extent of catalysis, that is, the yield of oligomers, and the length of the longest oligomer formed in these reactions widely varies with the source of montmorillonite (i.e., the locality where the mineral is mined). This study was undertaken to establish whether there exists a correlation between the extent of catalytic property and the charge density of montmorillonites. Charge density was determined by saturating the montmorillonites with alkyl ammonium cations that contained increasing lengths of alkyl chains, [CH₃-(CH₂)(n)-NH₃](+), where n = 3-16 and 18, and then measuring d(₀₀₁), interlayer spacing of the resulting montmorillonite-alkyl ammonium-montmorillonite complex by X-ray diffractometry (XRD). Results demonstrate that catalytic activity of montmorillonites with lower charge density is superior to that of higher charge density montmorillonite. They produce longer oligomers that contain 9 to 10 monomer units, while montmorillonite with high charge density catalyzes the formation of oligomers that contain only 4 monomer units. The charge density of montmorillonites can also be calculated from the chemical composition if elemental analysis data of the pure mineral are available. In the next mission to Mars, CheMin (Chemistry and Mineralogy), a combined X-ray diffraction/X-ray fluorescence instrument, will provide information on the mineralogical and elemental analysis of the samples. Possible significance of these results for planning the future missions to Mars for the search of organic compounds and extinct or extant life is discussed. PMID:20854214

  18. Minimizing antibody surface density on liposomes while sustaining cytokine-activated EC targeting.

    PubMed

    Almeda, Dariela; Wang, Biran; Auguste, Debra T

    2015-02-01

    Liposomes may be engineered to target inflamed endothelium by mimicking ligand-receptor interactions between leukocytes and cytokine-activated endothelial cells (ECs). The upregulation and assembly of vascular cell adhesion molecule-1 (VCAM1) and E-selectin on the cell membrane upon exposure to cytokines have shown potential for drug delivery vehicles to target sites of chronic endothelial inflammation, such as atherosclerosis and cancer. Herein, we characterized EC surfaces by measuring the E-selectin and VCAM1 surface densities and adhesion forces of aVCAM1 and aE-selectin to ECs. We quantified the antibody density, ratio, and diffusivity of liposomes to achieve significant binding and internalization. At 1 h, the 1:1 ratio of VCAM1:E-selectin antibodies was significantly higher than 1:0 and 0:1. Significant binding and uptake was achieved at aE-selectin densities as low as 400 molecules/μm(2). The highest levels of binding and uptake were achieved when using a 1:1 ratio of VCAM1:E-selectin antibodies at a density of 1000 molecules/μm(2); this density is 85% lower than previous reports. The binding and uptake of functionalized liposomes were reduced to levels comparable to IgG functionalized liposomes upon a 10-fold reduction in liposome membrane diffusivity. We conclude with a liposomal design that discriminates between healthy and inflamed endothelium while reducing antibody surface presentation. PMID:25522963

  19. Study on Na layer response to geomagnetic activities based on Odin/OSIRIS Na density data

    NASA Astrophysics Data System (ADS)

    Tsuda, Takuo; Nakamura, Takuji; Hedin, Jonas; Gumbel, Jorg; Hosokawa, Keisuke; Ejiri, Mitsumu K.; Nishiyama, Takanori; Takahashi, Toru

    2016-07-01

    The Na layer is normally distributed from 80 to 110 km, and the height range is corresponding to the ionospheric D and E region. In the polar region, the energetic particles precipitating from the magnetosphere can often penetrate into the E region and even into the D region. Thus, the influence of the energetic particles to the Na layer is one of interests in the aspect of the atmospheric composition change accompanied with the auroral activity. There are several previous studies in this issue. For example, recently, we have reported an initial result on a clear relationship between the electron density increase (due to the energetic particles) and the Na density decrease from observational data sets obtained by Na lidar, EISCAT VHF radar, and optical instruments at Tromsoe, Norway on 24-25 January 2012. However, all of the previous studies had been carried out based on case studies by ground-based lidar observations. In this study, we have performed, for the first time, statistical analysis using Na density data from 2004 to 2009 obtained with the Optical Spectrograph and InfraRed Imager System (OSIRIS) onboard Odin satellite. In the presentation, we will show relationship between the Na density and geomagnetic activities, and its latitudinal variation. Based on these results, the Na layer response to the energetic particles will be discussed.

  20. Photospheric Vertical Current Density and Overlying Atmospheric Activity in an Emerging Flux Region

    NASA Astrophysics Data System (ADS)

    Georgoulis, M. K.; Rust, D. M.; Bernasconi, P. N.; Schmieder, B.

    2002-05-01

    Using high-resolution vector magnetograms obtained by the balloon-borne Flare Genesis Experiment (FGE), we construct maps of the vertical current density in the emerging flux region NOAA 8844. The vertical current density has been decomposed into components that are field-aligned and perpendicular to the magnetic field, thus allowing a straightforward identification of force-free areas, as well as of areas where the force-free approximation breaks down. Small-scale chromospheric activity, such as H α Ellerman bombs and Ultraviolet bright points in 1600 Åshow a remarkable correlation with areas of strong current density. Simultaneous data of overlying coronal loops, observed by TRACE in the Extreme Ultraviolet (171 Åand 195 Å), have been carefully co-aligned with the FGE photospheric maps. We find that the footpoints of the TRACE loops always coincide with strong vertical currents and enhancements of the current helicity density. We also investigate whether the force-free approximation is valid on the photosphere during various evolutionary stages of the active region.

  1. Activated Microporous Carbon Derived from Almond Shells for High Energy Density Asymmetric Supercapacitors.

    PubMed

    Wu, Chun; Yang, Shaoran; Cai, Junjie; Zhang, Qiaobao; Zhu, Ying; Zhang, Kaili

    2016-06-22

    Via the activation treatment of carbonized almond shells with HNO3 and KOH, activated microporous carbon (AMC-3 and AMC-2) was successfully synthesized. These two AMC electrodes demonstrate remarkable electrochemical behaviors such as high rate capability, high specific capacitance, and excellent cycle stability when serving as electrodes for supercapacitors. More importantly, through the use of a Zn-Ni-Co ternary oxide (ZNCO) positive electrode and the AMC negative electrode, asymmetric supercapacitors (ASC) were assembled that deliver superior energy density (53.3 Wh kg(-1) at a power density of 1126.1 W kg(-1) for ASC-2 and 53.6 Wh kg(-1) at a power density of 1124.5 W kg(-1) for ASC-3) and excellent stability (82.7% and 83.4% specific capacitance retention for ZNCO//AMC ASC-2 and ZNCO//AMC ASC-3, respectively, after 5000 cycles). Through these two methods, low-cost, renewable, and environmentally friendly electrode materials can be provided for high energy density supercapacitors. PMID:27253880

  2. Relationship between the line of density anomaly and the lines of melting, crystallization, cavitation, and liquid spinodal in coarse-grained water models.

    PubMed

    Lu, Jibao; Chakravarty, Charusita; Molinero, Valeria

    2016-06-21

    Liquid water has several anomalous properties, including a non-monotonous dependence of density with temperature and an increase of thermodynamic response functions upon supercooling. Four thermodynamic scenarios have been proposed to explain the anomalies of water, but it is not yet possible to decide between them from experiments because of the crystallization and cavitation of metastable liquid water. Molecular simulations provide a versatile tool to study the anomalies and phase behavior of water, assess their agreement with the phenomenology of water under conditions accessible to experiments, and provide insight into the behavior of water in regions that are challenging to probe in the laboratory. Here we investigate the behavior of the computationally efficient monatomic water models mW and mTIP4P/2005(REM), with the aim of unraveling the relationships between the lines of density extrema in the p-T plane, and the lines of melting, liquid-vapor spinodal and non-equilibrium crystallization and cavitation. We focus particularly on the conditions for which the line of density maxima (LDM) in the liquid emerges and disappears as the pressure is increased. We find that these models present a retracing LDM, same as previously found for atomistic water models and models of other tetrahedral liquids. The low-pressure end of the LDM occurs near the pressure of maximum of the melting line, a feature that seems to be general to models that produce tetrahedrally coordinated crystals. We find that the mW water model qualitatively reproduces several key properties of real water: (i) the LDM is terminated by cavitation at low pressures and by crystallization of ice Ih at high pressures, (ii) the LDM meets the crystallization line close to the crossover in crystallization from ice Ih to a non-tetrahedral four-coordinated crystal, and (iii) the density of the liquid at the crossover in crystallization from ice Ih to a four-coordinated non-tetrahedral crystal coincides with

  3. Relationship between the line of density anomaly and the lines of melting, crystallization, cavitation, and liquid spinodal in coarse-grained water models

    NASA Astrophysics Data System (ADS)

    Lu, Jibao; Chakravarty, Charusita; Molinero, Valeria

    2016-06-01

    Liquid water has several anomalous properties, including a non-monotonous dependence of density with temperature and an increase of thermodynamic response functions upon supercooling. Four thermodynamic scenarios have been proposed to explain the anomalies of water, but it is not yet possible to decide between them from experiments because of the crystallization and cavitation of metastable liquid water. Molecular simulations provide a versatile tool to study the anomalies and phase behavior of water, assess their agreement with the phenomenology of water under conditions accessible to experiments, and provide insight into the behavior of water in regions that are challenging to probe in the laboratory. Here we investigate the behavior of the computationally efficient monatomic water models mW and mTIP4P/2005REM, with the aim of unraveling the relationships between the lines of density extrema in the p-T plane, and the lines of melting, liquid-vapor spinodal and non-equilibrium crystallization and cavitation. We focus particularly on the conditions for which the line of density maxima (LDM) in the liquid emerges and disappears as the pressure is increased. We find that these models present a retracing LDM, same as previously found for atomistic water models and models of other tetrahedral liquids. The low-pressure end of the LDM occurs near the pressure of maximum of the melting line, a feature that seems to be general to models that produce tetrahedrally coordinated crystals. We find that the mW water model qualitatively reproduces several key properties of real water: (i) the LDM is terminated by cavitation at low pressures and by crystallization of ice Ih at high pressures, (ii) the LDM meets the crystallization line close to the crossover in crystallization from ice Ih to a non-tetrahedral four-coordinated crystal, and (iii) the density of the liquid at the crossover in crystallization from ice Ih to a four-coordinated non-tetrahedral crystal coincides with the

  4. Effects of mine wastewater irrigation on activities of soil enzymes and physiological properties, heavy metal uptake and grain yield in winter wheat.

    PubMed

    Ma, Shou-Chen; Zhang, He-Bing; Ma, Shou-Tian; Wang, Rui; Wang, Gui-Xian; Shao, Yun; Li, Chun-Xi

    2015-03-01

    In China, coal-mining industries are mainly located in the water shortage areas including arid or semiarid areas. Mine wastewater is used for irrigation of agricultural land in these areas. However, few studies have been conducted to address ecological and food safety risks caused by mine wastewater irrigation. In this research, a pot experiment was performed to examine the effects of mine wastewater irrigation on soil enzymes, physiological properties of wheat and potential risks of heavy metal contamination to wheat crop. Plants were subjected to three mine wastewater irrigation treatments: leacheate of coal gangue (T1), coal-washing wastewater (T2) and precipitated coal-washing wastewater (T3). Plants irrigated with well water were taken as the control (CK). The results showed that mine wastewater irrigation caused adverse effects on soil enzymes, physiological properties and grain yield of winter wheat. At anthesis, T1, T2 and T3 treatments significantly reduced the activities of soil enzymes (urease, sucrase and catalase), root activity and net photosynthetic rate of wheat compared to CK. At maturity, grain yield was decreased by 17.8%, 15.4% and 9.8% by T1, T2 and T3, respectively, as compared to that of CK. Importantly, mine wastewater irrigation resulted in accumulation of heavy metals (Cr, Pb, Cu and Zn) in wheat grain. Contents of these heavy metals in grains of winter wheat subjected to mine wastewater irrigation were significantly higher than those in CK. The comprehensive contamination indexes of wheat grain in T1, T2 and T3 all reached high pollution level. Our results showed that mine wastewater irrigation significantly increased the pollution risk of heavy metals, thus unsuitable for crop irrigation. PMID:25562177

  5. Toxic and antifeedant activities of prenylated flavonoids isolated from Tephrosia apollinea L. against three major coleopteran pests of stored grains with reference to their structure-activity relationship.

    PubMed

    Nenaah, Gomah E

    2014-01-01

    Four prenylated flavonoids, isoglabratephrin, (+)-glabratephrin, tephroapollin-F and lanceolatin-A, were isolated from Tephrosia apollinea L. and tested against three stored grain insects. Using the filter paper bioassay, compounds showed adulticidal activity against Sitophilus oryzae (L), Rhyzopertha dominica (F) and Tribolium castaneum (Herbst) at concentrations of 0.875, 1.75 and 3.5 mg mL(- 1). At 3.5 mg mL(- 1), tephroapollin-F was the most toxic (78.6%, 64.6% and 60.7% mortality was recorded after 10 days exposure of S. oryzae, R. dominica and T. castaneum, respectively). The F1 progeny production of insects was affected after parental exposure to flavonoids, where S. oryzae was the most susceptible. A nutritional bioassay, employing a flour disc and test concentrations of 0.65, 1.3 and 2.6 mg g(- 1), revealed a significant reduction in the relative growth rate, relative consumption rate and efficiency of conversion of ingested food by all insects. The structure-activity relationship among the tested flavonoids was discussed. PMID:24980754

  6. Streaming of interstellar grains in the solar system

    NASA Technical Reports Server (NTRS)

    Gustafson, B. A. S.; Misconi, N. Y.

    1979-01-01

    Results of a theoretical study of the interactions between interstellar grains streaming through the solar system and the solar wind are presented. It is shown that although elongated core-mantle interstellar particles of a characteristic radius of about 0.12 microns are subject to a greater force due to radiation pressure than to gravitational attraction, they are still able to penetrate deep inside the solar system. Calculations of particle trajectories within the solar system indicate substantial effects of the solar activity cycle as reflected in the interplanetary magnetic field on the distribution of 0.12- and 0.0005-micron interstellar grains streaming through the solar system, leading to a 50-fold increase in interstellar grain densities 3 to 4 AU ahead of the sun during years 8 to 17 of the solar cycle. It is noted that during the Solar Polar Mission, concentrations are expected which will offer the opportunity of detecting interstellar grains in the solar system.

  7. Evidence for composition variations and impurity segregation at grain boundaries in high current-density polycrystalline K- and Co-doped BaFe{sub 2}As{sub 2} superconductors

    SciTech Connect

    Kim, Yoon-Jun; Weiss, Jeremy D.; Hellstrom, Eric E.; Larbalestier, David C.; Seidman, David N.

    2014-10-20

    Some polycrystalline forms of the K- and Co-doped BaFe{sub 2}As{sub 2} and SrFe{sub 2}As{sub 2} superconductors now have a critical current density (J{sub c}) within a factor of ∼5 of that required for real applications, even though it is known that some grain boundaries (GBs) block current, thus, raising the question of whether this blocking is intrinsic or extrinsically limited by artefacts amenable to improvement by better processing. Herein, we utilize atom-probe tomography (APT) to study the grain and GB composition in high J{sub c} K- and Co-doped BaFe{sub 2}As{sub 2} polycrystals. We find that all GBs studied show significant compositional variations on the scale of a few coherence lengths (ξ), as well as strong segregation of oxygen impurities, which we believe are largely introduced in the starting materials. Importantly, these findings demonstrate that APT enables quantitative analysis of the highest J{sub c} K-doped BaFe{sub 2}As{sub 2} samples, where analytical transmission electron microscopy (TEM) fails because of the great reactivity of thin TEM samples. The observations of major chemical perturbations at GBs make us cautiously optimistic that there is a large extrinsic component to the GB current blocking, which will be ameliorated by better processing, for which APT will likely be a crucial instrument.

  8. Density, distribution, and activity of the ocelot Leopardus pardalis (Carnivora: Felidae) in Southeast Mexican rainforests.

    PubMed

    Pérez-Irineo, Gabriela; Santos-Moreno, Antonio

    2014-12-01

    The ocelot Leopardus pardalis is of particular significance in terrestrial communities due to its ecological role within the group of small-sized felids and as a mesopredator. However, despite the reduction of ocelot habitat in Southeast Mexico, there are still very few ecological studies. This research aimed to contribute with some ecological aspects of the species in this region. For this, 29 camera trap stations were established in a rain forest in Los Chimalapas (an area of 22 km2) during a two years period (March 2011-June, 2013), in Oaxaca state, Southeast Mexico. Data allowed the estimation of the population density, activity pattern, sex ratio, residence time, and spatial distribution. Population density was calculated using Capture-Recapture Models for demographically open populations; besides, circular techniques were used to determine if nocturnal and diurnal activity varied significantly over the seasons, and Multiple Discriminant Analysis was used to determine which of the selected environmental variables best explained ocelot abundance in the region. A total of 103 ocelot records were obtained, with a total sampling effort of 8,529 trap-days. Density of 22-38 individuals/100 km2 was estimated. Ocelot population had a high proportion of transient individuals in the zone (55%), and the sex ratio was statistically equal to 1:1. Ocelot activity was more frequent at night (1:00-6:00h), but it also exhibited diurnal activity throughout the study period. Ocelot spatial distribution was positively affected by the proximity to the village as well as by the amount of prey. The ocelot population here appears to be stable, with a density similar to other regions in Central and South America, which could be attributed to the diversity of prey species and a low degree of disturbance in Los Chimalapas. PMID:25720177

  9. A complete active space SCF method (CASSCF) using a density matrix formulated super-CI approach

    NASA Astrophysics Data System (ADS)

    Roos, Björn O.; Taylor, Peter R.; Si≐gbahn, Per E. M.

    1980-05-01

    A density matrix formulation of the super-CI MCSCF method is presented. The MC expansion is assumed to be complete in an active subset of the orbital space, and the corresponding CI secular problem is solved by a direct scheme using the unitary group approach. With a density matrix formulation the orbital optimization step becomes independent of the size of the CI expansion. It is possible to formulate the super-CI in terms of density matrices defined only in the small active subspace; the doubly occupied orbitals (the inactive subspace) do not enter. Further, in the unitary group formalism it is straightforward and simple to obtain the necessary density matrices from the symbolic formula list. It then becomes possible to treat very long MC expansions, the largest so far comprising 726 configurations. The method is demonstrated in a calculation of the potential curves for the three lowest states ( 1Σ +g, 3Σ +u and 3Π g) of the N 2 molecule, using a medium-sized gaussian basis set. Seven active orbitals were used yielding the following results: De: 8.76 (9.90), 2.43 (3.68) and 3.39 (4.90) eV; re: 1.108 (1.098), 1.309 (1.287) and 1.230 (1.213) Å; ω e: 2333 (2359), 1385 (1461) and 1680 (1733) cm -1, for the three states (experimental values within parentheses). The results of these calculations indicate that it is important to consider not only the dissociation limit but also the united atom limit in partitioning the occupied orbital space into an active and an inactive part.

  10. Synthesis of Dense, Fine-Grained YIG Ceramics by Two-Step Sintering

    NASA Astrophysics Data System (ADS)

    Li, X. X.; Zhou, J. J.; Deng, J. X.; Zheng, H.; Zheng, L.; Zheng, P.; Qin, H. B.

    2016-06-01

    A two-step sintering (TSS) process has been used to fabricate yttrium iron garnet (YIG) ceramics with high density and fine grain size. The densification, microstructure, and magnetic properties were investigated. The sample prepared by the TSS process with first-step sintering temperature (T 1) of 1350°C, second-step sintering temperature (T 2) of 1300°C, and holding time of 18 h had density above 99% of theoretical and exhibited uniform microstructure with small average grain size (2.4 μm). The saturation magnetization (M S) of this sample reached 27.4 emu/g. These results indicate that the TSS process can effectively suppress grain-boundary migration while maintaining active grain-boundary diffusion to obtain dense, fine-grained YIG ceramics with appropriate magnetic properties.

  11. Grain Spectroscopy

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1992-01-01

    Our fundamental knowledge of interstellar grain composition has grown substantially during the past two decades thanks to significant advances in two areas: astronomical infrared spectroscopy and laboratory astrophysics. The opening of the mid-infrared, the spectral range from 4000-400 cm(sup -1) (2.5-25 microns), to spectroscopic study has been critical to this progress because spectroscopy in this region reveals more about a materials molecular composition and structure than any other physical property. Infrared spectra which are diagnostic of interstellar grain composition fall into two categories: absorption spectra of the dense and diffuse interstellar media, and emission spectra from UV-Vis rich dusty regions. The former will be presented in some detail, with the latter only very briefly mentioned. This paper summarized what we have learned from these spectra and presents 'doorway' references into the literature. Detailed reviews of many aspects of interstellar dust are given.

  12. Factors in Daily Physical Activity Related to Calcaneal Mineral Density in Men

    NASA Technical Reports Server (NTRS)

    Hutchinson, Teresa M.; Whalen, Robert T.; Cleek, Tammy M.; Vogel, John M.; Arnaud, Sara B.

    1995-01-01

    To determine the factors in daily physical activity that influence the mineral density of the calcaneus, we recorded walking steps and the type and duration of exercise in 43 healthy 26-to 51-yr-old men. Areal (g/sq cm) calcaneal bone mineral density (CBMD) was measured by single energy x-ray densitometry. Subjects walked a mean (+/- SD) of 7902(+/-2534) steps per day or approximately 3.9(+/-1.2) miles daily. Eight subjects reported no exercise activities. The remaining 35 subjects spent 143(2-772) (median and range) min/wk exercising. Twenty-eight men engaged in exercise activities that generate single leg peak vertical ground reaction forces (GRF(sub z)) of 2 or more body weights (high loaders, HL), and 15 reported exercise or daily activities that typically generate GRF(sub z) less than 1.5 body weights (low loaders, LL). CBMD was 12% higher in HL than LL (0.668 +/- 0.074 g/sq cm vs 0.597 +/- 0.062 g/sq cm, P less than 0.004). In the HL group, CBMD correlated to reported minutes of high load exercise (r = 0.41, P less than 0.03). CBMD was not related to the number of daily walking steps (N = 43, r = 0.03, NS). The results of this study support the concept that the dominant factor in daily physical activity relating to bone mineral density is the participation in site specific high loading activities, i.e., for the calcaneus, high calcaneal loads.

  13. Local and Landscape Correlates of Spider Activity Density and Species Richness in Urban Gardens.

    PubMed

    Otoshi, Michelle D; Bichier, Peter; Philpott, Stacy M

    2015-08-01

    Urbanization is a major threat to arthropod biodiversity and abundance due to reduction and loss of suitable natural habitat. Green spaces and small-scale agricultural areas may provide habitat and resources for arthropods within densely developed cities. We studied spider activity density (a measure of both abundance and degree of movement) and diversity in urban gardens in Santa Cruz, Santa Clara, and Monterey counties in central California, USA. We sampled for spiders with pitfall traps and sampled 38 local site characteristics for 5 mo in 19 garden sites to determine the relative importance of individual local factors. We also analyzed 16 landscape variables at 500-m and 1-km buffers surrounding each garden to determine the significance of landscape factors. We identified individuals from the most common families to species and identified individuals from other families to morphospecies. Species from the families Lycosidae and Gnaphosidae composed 81% of total adult spider individuals. Most of the significant factors that correlated with spider activity density and richness were local rather than landscape factors. Spider activity density and richness increased with mulch cover and flowering plant species, and decreased with bare soil. Thus, changes in local garden management have the potential to promote diversity of functionally important spiders in urban environments. PMID:26314049

  14. Anti-hierarchical evolution of the active galactic nucleus space density in a hierarchical universe

    SciTech Connect

    Enoki, Motohiro; Ishiyama, Tomoaki; Kobayashi, Masakazu A. R.; Nagashima, Masahiro

    2014-10-10

    Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combination of the cold gas depletion as a consequence of star formation, the gas cooling suppression in massive halos, and the AGN lifetime scaling with the dynamical timescale. We assume that a major merger of galaxies causes a starburst, spheroid formation, and cold gas accretion onto a supermassive black hole (SMBH). We also assume that this cold gas accretion triggers AGN activity. Since the cold gas is mainly depleted by star formation and gas cooling is suppressed in massive dark halos, the amount of cold gas accreted onto SMBHs decreases with cosmic time. Moreover, AGN lifetime increases with cosmic time. Thus, at low redshifts, major mergers do not always lead to luminous AGNs. Because the luminosity of AGNs is correlated with the mass of accreted gas onto SMBHs, the space density of luminous AGNs decreases more quickly than that of faint AGNs. We conclude that the anti-hierarchical evolution of the AGN space density is not contradictory to the hierarchical structure formation scenario.

  15. Anti-hierarchical Evolution of the Active Galactic Nucleus Space Density in a Hierarchical Universe

    NASA Astrophysics Data System (ADS)

    Enoki, Motohiro; Ishiyama, Tomoaki; Kobayashi, Masakazu A. R.; Nagashima, Masahiro

    2014-10-01

    Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combination of the cold gas depletion as a consequence of star formation, the gas cooling suppression in massive halos, and the AGN lifetime scaling with the dynamical timescale. We assume that a major merger of galaxies causes a starburst, spheroid formation, and cold gas accretion onto a supermassive black hole (SMBH). We also assume that this cold gas accretion triggers AGN activity. Since the cold gas is mainly depleted by star formation and gas cooling is suppressed in massive dark halos, the amount of cold gas accreted onto SMBHs decreases with cosmic time. Moreover, AGN lifetime increases with cosmic time. Thus, at low redshifts, major mergers do not always lead to luminous AGNs. Because the luminosity of AGNs is correlated with the mass of accreted gas onto SMBHs, the space density of luminous AGNs decreases more quickly than that of faint AGNs. We conclude that the anti-hierarchical evolution of the AGN space density is not contradictory to the hierarchical structure formation scenario.

  16. Magnetar activity via the density-shear instability in Hall-MHD

    NASA Astrophysics Data System (ADS)

    Gourgouliatos, Konstantinos N.; Kondić, Todor; Lyutikov, Maxim; Hollerbach, Rainer

    2015-10-01

    We investigate the density-shear instability in Hall-magnetohydrodynamics (Hall-MHD) via numerical simulation of the full non-linear problem in the context of magnetar activity. We confirm the development of the instability of a plane-parallel magnetic field with an appropriate intensity and electron density profile, in accordance with analytic theory. We find that the instability also appears for a monotonically decreasing electron number density and magnetic field, a plane-parallel analogue of an azimuthal or meridional magnetic field in the crust of a magnetar. The growth rate of the instability depends on the Hall properties of the field (magnetic field intensity, electron number density and the corresponding scaleheights), while being insensitive to weak resistivity. Since the Hall effect is the driving process for the evolution of the crustal magnetic field of magnetars, we argue that this instability is critical for systems containing strong meridional or azimuthal fields. We find that this process mediates the formation of localized structures with much stronger magnetic field than the average, which can lead to magnetar activity and accelerate the dissipation of the field and consequently the production of Ohmic heating. Assuming a 5 × 1014 G magnetic field at the base of crust, we anticipate that magnetic field as strong as 1015 G will easily develop in regions of typical size of a few hundred metres, containing magnetic energy of 1043 erg, sufficient to power magnetar bursts. These active regions are more likely to appear in the magnetic equator where the tangential magnetic field is stronger.

  17. Relationship between position of brain activity and change in optical density for NIR imaging

    NASA Astrophysics Data System (ADS)

    Kashio, Yoshihiko; Ono, Muneo; Firbank, Michael; Schweiger, Martin; Arridge, Simon R.; Okada, Eiji

    2000-11-01

    Multi-channel NIR system can obtain the topographic image of brain activity. Since the image is reconstructed from the change in optical density measured with the source-detector pairs, it is important to reveal the volume of tissue sampled by each source-detector pair. In this study, the light propagation in three-dimensional adult head model is calculated by hybrid radiosity-diffusion method. The model is a layered slab which mimics the extra cerebral tissue (skin, skull), CSF and brain. The change in optical density caused by the absorption change in a small cylindrical region of 10 mm in diameter at various positions in the brain is calculated. The greatest change in optical density can be observed when the absorber is located in the middle of the source and detector. When the absorber is located just below the source or detector, the change in optical density is almost half of that caused by the same absorber in the midpoint. The light propagation in the brain is strongly affected by the presence of non-scattering layer and consequently sensitive region is broadly distributed on the brain surface.

  18. 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.

  19. Weakened Flexural Strength of Nanocrystalline Nanoporous Gold by Grain Refinement.

    PubMed

    Gwak, Eun-Ji; Kim, Ju-Young

    2016-04-13

    High density of grain boundaries in solid materials generally leads to high strength because grain boundaries act as strong obstacles to dislocation activity. We find that the flexural strength of nanoporous gold of grain size 206 nm is 33.6% lower than that of grain size 238 μm. We prepared three gold-silver precursor alloys, well-annealed, prestrained, and high-energy ball-milled, from which nanoporous gold samples were obtained by the same free-corrosion dealloying process. Ligaments of the same size are formed regardless of precursor alloys, and microstructural aspects of precursor alloys such as crystallographic orientation and grain size is preserved in the dealloying process. While the nanoindentation hardness of three nanoporous golds is independent of microstructural variation, flexural strength of nanocrystalline nanoporous gold is significantly lower than that of nanoporous golds with much larger grain size. We investigate weakening mechanisms of grain boundaries in nanocrystalline nanoporous gold, leading to weakening of flexural strength. PMID:26982460

  20. A high-density genetic recombination map of sequence-tagged sites for sorghum, as a framework for comparative structural and evolutionary genomics of tropical grains and grasses.

    PubMed Central

    Bowers, John E; Abbey, Colette; Anderson, Sharon; Chang, Charlene; Draye, Xavier; Hoppe, Alison H; Jessup, Russell; Lemke, Cornelia; Lennington, Jennifer; Li, Zhikang; Lin, Yann-Rong; Liu, Sin-Chieh; Luo, Lijun; Marler, Barry S; Ming, Reiguang; Mitchell, Sharon E; Qiang, Dou; Reischmann, Kim; Schulze, Stefan R; Skinner, D Neil; Wang, Yue-Wen; Kresovich, Stephen; Schertz, Keith F; Paterson, Andrew H

    2003-01-01

    We report a genetic recombination map for Sorghum of 2512 loci spaced at average 0.4 cM ( approximately 300 kb) intervals based on 2050 RFLP probes, including 865 heterologous probes that foster comparative genomics of Saccharum (sugarcane), Zea (maize), Oryza (rice), Pennisetum (millet, buffelgrass), the Triticeae (wheat, barley, oat, rye), and Arabidopsis. Mapped loci identify 61.5% of the recombination events in this progeny set and reveal strong positive crossover interference acting across intervals of density are related to possible centromeric regions and to probable chromosome structural rearrangements between Sorghum bicolor and S. propinquum, but not to variation in levels of intraspecific allelic richness. While cDNA and genomic clones are similarly distributed across the genome, SSR-containing clones show different abundance patterns. Rapidly evolving hypomethylated DNA may contribute to intraspecific genomic differentiation. Nonrandom distribution patterns of multiple loci detected by 357 probes suggest ancient chromosomal duplication followed by extensive rearrangement and gene loss. Exemplifying the value of these data for comparative genomics, we support and extend prior findings regarding maize-sorghum synteny-in particular, 45% of comparative loci fall outside the inferred colinear/syntenic regions, suggesting that many small rearrangements have occurred since maize-sorghum divergence. These genetically anchored sequence-tagged sites will foster many structural, functional and evolutionary genomic studies in major food, feed, and biomass crops. PMID:14504243

  1. Improvement of spectral density-based activation detection of event-related fMRI data.

    PubMed

    Ngan, Shing-Chung; Hu, Xiaoping; Tan, Li-Hai; Khong, Pek-Lan

    2009-09-01

    For event-related data obtained from an experimental paradigm with a periodic design, spectral density at the fundamental frequency of the paradigm has been used as a template-free activation detection measure. In this article, we build and expand upon this detection measure to create an improved, integrated measure. Such an integrated measure linearly combines information contained in the spectral densities at the fundamental frequency as well as the harmonics of the paradigm and in a spatial correlation function characterizing the degree of co-activation among neighboring voxels. Several figures of merit are described and used to find appropriate values for the coefficients in the linear combination. Using receiver-operating characteristic analysis on simulated functional magnetic resonance imaging (fMRI) data sets, we quantify and validate the improved performance of the integrated measure over the spectral density measure based on the fundamental frequency as well as over some other popular template-free data analysis methods. We then demonstrate the application of the new method on an experimental fMRI data set. Finally, several extensions to this work are suggested. PMID:19535208

  2. Controlling activation site density by low-energy far-field stimulation in cardiac tissue

    NASA Astrophysics Data System (ADS)

    Hörning, Marcel; Takagi, Seiji; Yoshikawa, Kenichi

    2012-06-01

    Tachycardia and fibrillation are potentially fatal arrhythmias associated with the formation of rotating spiral waves in the heart. Presently, the termination of these types of arrhythmia is achieved by use of antitachycardia pacing or cardioversion. However, these techniques have serious drawbacks, in that they either have limited application or produce undesirable side effects. Low-energy far-field stimulation has recently been proposed as a superior therapy. This proposed therapeutic method would exploit the phenomenon in which the application of low-energy far-field shocks induces a large number of activation sites (“virtual electrodes”) in tissue. It has been found that the formation of such sites can lead to the termination of undesired states in the heart and the restoration of normal beating. In this study we investigate a particular aspect of this method. Here we seek to determine how the activation site density depends on the applied electric field through in vitro experiments carried out on neonatal rat cardiac tissue cultures. The results indicate that the activation site density increases exponentially as a function of the intracellular conductivity and the level of cell isotropy. Additionally, we report numerical results obtained from bidomain simulations of the Beeler-Reuter model that are quantitatively consistent with our experimental results. Also, we derive an intuitive analytical framework that describes the activation site density and provides useful information for determining the ratio of longitudinal to transverse conductivity in a cardiac tissue culture. The results obtained here should be useful in the development of an actual therapeutic method based on low-energy far-field pacing. In addition, they provide a deeper understanding of the intrinsic properties of cardiac cells.

  3. A High Power Density Single-Phase PWM Rectifier With Active Ripple Energy Storage

    SciTech Connect

    Wang, Ruxi; Wang, Fei; Boroyevich, Dushan; Burgos, Rolando; Lai, Rixin; Ning, Puqi; Rajashekara, Kaushik

    2011-01-01

    It is well known that single-phase pulse width modulation rectifiers have second-order harmonic currents and corresponding ripple voltages on the dc bus. The low-frequency harmonic current is normally filtered using a bulk capacitor in the bus, which results in low power density. However, pursuing high power density in converter design is a very important goal in the aerospace applications. This paper studies methods for reducing the energy storage capacitor for single-phase rectifiers. The minimum ripple energy storage requirement is derived independently of a specific topology. Based on theminimum ripple energy requirement, the feasibility of the active capacitor s reduction schemes is verified. Then, we propose a bidirectional buck boost converter as the ripple energy storage circuit, which can effectively reduce the energy storage capacitance. The analysis and design are validated by simulation and experimental results.

  4. An empirical model to estimate density of sodium hydroxide solution: An activator of geopolymer concretes

    NASA Astrophysics Data System (ADS)

    Rajamane, N. P.; Nataraja, M. C.; Jeyalakshmi, R.; Nithiyanantham, S.

    2016-02-01

    Geopolymer concrete is zero-Portland cement concrete containing alumino-silicate based inorganic polymer as binder. The polymer is obtained by chemical activation of alumina and silica bearing materials, blast furnace slag by highly alkaline solutions such as hydroxide and silicates of alkali metals. Sodium hydroxide solutions of different concentrations are commonly used in making GPC mixes. Often, it is seen that sodium hydroxide solution of very high concentration is diluted with water to obtain SHS of desired concentration. While doing so it was observed that the solute particles of NaOH in SHS tend to occupy lower volumes as the degree of dilution increases. This aspect is discussed in this paper. The observed phenomenon needs to be understood while formulating the GPC mixes since this influences considerably the relationship between concentration and density of SHS. This paper suggests an empirical formula to relate density of SHS directly to concentration expressed by w/w.

  5. Adolescent and Young Adult Exposure to Physical Activity and Breast Density

    PubMed Central

    Gabriel, Kelley Pettee; Klifa, Catherine; Pérez, Adriana; Kriska, Andrea M.; High, Robin R.; Snetselaar, Linda; Dorgan, Joanne F.

    2013-01-01

    Purpose To examine the role of early lifetime exposure to physical activity on magnetic resonance imaging (MRI) determined breast density measures. Methods Associations of adolescent [high school (ages 14–17 years) and early adulthood [post high school (ages 18–21 years) and past year] leisure-time physical activity, as well as a principal component score including all three estimates, were examined with percent dense breast volume (%DBV) and absolute dense breast volume (ADBV) in a cross-sectional analysis of 182 healthy women, aged 25–29 years enrolled in the Dietary Intervention Study in Children Follow-up Study (DISC06). Generalized linear mixed (GLM) models were used to examine associations after adjustment for relevant covariates for the entire analytic sample. Analyses were repeated in nulliparous women and hormonal contraceptive non-users. Results Physical activity during high school and post high school were not statistically significantly related to %DBV or ADBV in multivariable models. Past year physical activity was positively related to %DBV in the unadjusted and partially adjusted models (p<0.001 and p=0.01, respectively) that did not adjust for body mass index (BMI). After additional adjustment for childhood and early adulthood BMI, this association became non-statistically significant. The relation between past year physical activity and ADBV was not statistically significant. These findings were similar in non-users of hormonal contraceptives. No statistically significant relationships were found in nulliparous women or between the principal component score and %DBV or ADBV. Conclusion Results from this study are consistent with previous research suggesting that physical activity during adolescence and early adulthood is unrelated to breast density. PMID:23377838

  6. STORED GRAIN ADVISOR PRO: DECISION SUPPORT SYSTEM FOR INSECT MANAGEMENT IN COMMERCIAL GRAIN ELEVATORS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A decision support system, Stored Grain Advisor Pro (SGA Pro), was developed to provide insect pest management information for grain stored at commercial elevators. The program uses a model to predict future risk based on current insect density, grain temperature and moisture. A rule-based system wa...

  7. Joint Associations of Residential Density and Neighborhood Involvement with Physical Activity among a Multiethnic Sample of Urban Adults

    ERIC Educational Resources Information Center

    Johnson-Lawrence, Vicki; Schulz, Amy J.; Zenk, Shannon N.; Israel, Barbara A.; Wineman, Jean; Marans, Robert W.; Rowe, Zachary

    2015-01-01

    Regular physical activity is associated with improvements in overall health. Although resident involvement in neighborhood social activities is positively associated with physical activity, neighborhood design features, including residential density, have varied associations with physical activity. Using data from a multiethnic sample of 696…

  8. Serum Paraoxonase 1 Activity Is Associated with Fatty Acid Composition of High Density Lipoprotein

    PubMed Central

    Boshtam, Maryam; Pourfarzam, Morteza; Ani, Mohsen; Naderi, Gholam Ali; Basati, Gholam; Mansourian, Marjan; Dinani, Narges Jafari; Asgary, Seddigheh; Abdi, Soheila

    2013-01-01

    Introduction. Cardioprotective effect of high density lipoprotein (HDL) is, in part, dependent on its related enzyme, paraoxonase 1 (PON1). Fatty acid composition of HDL could affect its size and structure. On the other hand, PON1 activity is directly related to the structure of HDL. This study was designed to investigate the association between serum PON1 activity and fatty acid composition of HDL in healthy men. Methods. One hundred and forty healthy men participated in this research. HDL was separated by sequential ultracentrifugation, and its fatty acid composition was analyzed by gas chromatography. PON1 activity was measured spectrophotometrically using paraxon as substrate. Results. Serum PON1 activity was directly correlated with the amount of stearic acid and dihomo-gamma-linolenic acid (DGLA). PON1/HDL-C was directly correlated with the amount of miristic acid, stearic acid, and DGLA and was inversely correlated with total amount of ω6 fatty acids of HDL. Conclusion. The fatty acid composition of HDL could affect the activity of its associated enzyme, PON1. As dietary fats are the major determinants of serum lipids and lipoprotein composition, consuming some special dietary fatty acids may improve the activity of PON1 and thereby have beneficial effects on health. PMID:24167374

  9. Association of sarcopenia and physical activity with femur bone mineral density in elderly women

    PubMed Central

    Lee, Inhwan; Ha, Changduk; Kang, Hyunsik

    2016-01-01

    [Purpose] This study examined the association of femur bone mineral density (BMD) with body composition and physical activity in elderly women. [Methods] This was a cross sectional study involving 119 women with mean age of 73.1±5.5 years. Body composition parameters including body mass index (BMI), percent of body fat (%BF), appendicular skeletal muscle mass (ASM) index and femur BMD was measured by dual-energy X-ray absorptiometry (DXA). Physical activity was assessed by the uniaxial accelerometer for 7 consecutive days including weekends. Based on femur BMD T-scores, subjects were classified as optimal group, osteopenia group, and osteoporosis group. Based on ASM index, subjects were classified as normal group and sarcopenia group. According to WHO recommendations of physical activity for elderly, the subjects were classified as active group or inactive group. Logistic regression analyses were used to determine the odds ratio (OR) for osteopenia and osteoporosis. [Results] There were linear decreases for body composition parameters including weight (P=.023), BMI (P=.039), lean mass (P=.032), ASM index (P=.007) and physical activity parameters including daily of step (P<.001), low intensity physical activity (P<.001), moderate intensity physical activity (P=.001) across femur BMD levels. Compared to the normal group (OR=1), the sarcopenia group had a significantly higher OR (OR=4.823; P=.042), and the inactive group had a significantly higher OR (OR=5.478; P=.005) having osteopenia and osteoporosis when compared to the active group (OR=1). [Conclusion] The findings of this study suggested that physical activity along with a healthy nutrition should be promoted as a preventive strategy against osteopenia and osteoporosis in elderly women. PMID:27298809

  10. Use of prediction methods to estimate true density of active pharmaceutical ingredients.

    PubMed

    Cao, Xiaoping; Leyva, Norma; Anderson, Stephen R; Hancock, Bruno C

    2008-05-01

    True density is a fundamental and important property of active pharmaceutical ingredients (APIs). Using prediction methods to estimate the API true density can be very beneficial in pharmaceutical research and development, especially when experimental measurements cannot be made due to lack of material or sample handling restrictions. In this paper, two empirical prediction methods developed by Girolami and Immirzi and Perini were used to estimate the true density of APIs, and the estimation results were compared with experimentally measured values by helium pycnometry. The Girolami method is simple and can be used for both liquids and solids. For the tested APIs, the Girolami method had a maximum error of -12.7% and an average percent error of -3.0% with a 95% CI of (-3.8, -2.3%). The Immirzi and Perini method is more involved and is mainly used for solid crystals. In general, it gives better predictions than the Girolami method. For the tested APIs, the Immirzi and Perini method had a maximum error of 9.6% and an average percent error of 0.9% with a 95% CI of (0.3, 1.6%). PMID:18242023

  11. Neonatal hemodynamic response to visual cortex activity: high-density near-infrared spectroscopy study

    NASA Astrophysics Data System (ADS)

    Liao, Steve M.; Gregg, Nick M.; White, Brian R.; Zeff, Benjamin W.; Bjerkaas, Katelin A.; Inder, Terrie E.; Culver, Joseph P.

    2010-03-01

    The neurodevelopmental outcome of neonatal intensive care unit (NICU) infants is a major clinical concern with many infants displaying neurobehavioral deficits in childhood. Functional neuroimaging may provide early recognition of neural deficits in high-risk infants. Near-infrared spectroscopy (NIRS) has the advantage of providing functional neuroimaging in infants at the bedside. However, limitations in traditional NIRS have included contamination from superficial vascular dynamics in the scalp. Furthermore, controversy exists over the nature of normal vascular, responses in infants. To address these issues, we extend the use of novel high-density NIRS arrays with multiple source-detector distances and a superficial signal regression technique to infants. Evaluations of healthy term-born infants within the first three days of life are performed without sedation using a visual stimulus. We find that the regression technique significantly improves brain activation signal quality. Furthermore, in six out of eight infants, both oxy- and total hemoglobin increases while deoxyhemoglobin decreases, suggesting that, at term, the neurovascular coupling in the visual cortex is similar to that found in healthy adults. These results demonstrate the feasibility of using high-density NIRS arrays in infants to improve signal quality through superficial signal regression, and provide a foundation for further development of high-density NIRS as a clinical tool.

  12. Extracting extensor digitorum communis activation patterns using high-density surface electromyography.

    PubMed

    Hu, Xiaogang; Suresh, Nina L; Xue, Cindy; Rymer, William Z

    2015-01-01

    The extensor digitorum communis muscle plays an important role in hand dexterity during object manipulations. This multi-tendinous muscle is believed to be controlled through separate motoneuron pools, thereby forming different compartments that control individual digits. However, due to the complex anatomical variations across individuals and the flexibility of neural control strategies, the spatial activation patterns of the extensor digitorum communis compartments during individual finger extension have not been fully tracked under different task conditions. The objective of this study was to quantify the global spatial activation patterns of the extensor digitorum communis using high-density (7 × 9) surface electromyogram (EMG) recordings. The muscle activation map (based on the root mean square of the EMG) was constructed when subjects performed individual four finger extensions at the metacarpophalangeal joint, at different effort levels and under different finger constraints (static and dynamic). Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance. The activation map was relatively consistent at different muscle contraction levels and for different finger constraint conditions. We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction. The global spatial activation map utilizing surface grid EMG of the extensor digitorum communis muscle provides information for localizing individual compartments of the extensor muscle during finger extensions. This is of potential value for identifying more selective control input for assistive devices. Such information can also provide a basis for understanding hand impairment in individuals with neural disorders. PMID:26500558

  13. Extracting extensor digitorum communis activation patterns using high-density surface electromyography

    PubMed Central

    Hu, Xiaogang; Suresh, Nina L.; Xue, Cindy; Rymer, William Z.

    2015-01-01

    The extensor digitorum communis muscle plays an important role in hand dexterity during object manipulations. This multi-tendinous muscle is believed to be controlled through separate motoneuron pools, thereby forming different compartments that control individual digits. However, due to the complex anatomical variations across individuals and the flexibility of neural control strategies, the spatial activation patterns of the extensor digitorum communis compartments during individual finger extension have not been fully tracked under different task conditions. The objective of this study was to quantify the global spatial activation patterns of the extensor digitorum communis using high-density (7 × 9) surface electromyogram (EMG) recordings. The muscle activation map (based on the root mean square of the EMG) was constructed when subjects performed individual four finger extensions at the metacarpophalangeal joint, at different effort levels and under different finger constraints (static and dynamic). Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance. The activation map was relatively consistent at different muscle contraction levels and for different finger constraint conditions. We also found that distinct activation patterns were more discernible in the proximal–distal direction than in the radial–ulnar direction. The global spatial activation map utilizing surface grid EMG of the extensor digitorum communis muscle provides information for localizing individual compartments of the extensor muscle during finger extensions. This is of potential value for identifying more selective control input for assistive devices. Such information can also provide a basis for understanding hand impairment in individuals with neural disorders. PMID:26500558

  14. Physical Activity Level of Post-menopausal Women with Low Bone Mineral Density.

    PubMed

    Dallanezi, Glauber; Freire, Beatriz Funayama Alvarenga; Nahás, Eliana Aguiar Petri; Nahás-Neto, Jorge; Corrente, José Eduardo; Mazeto, Gláucia Maria Ferreira da Silva

    2016-05-01

    Introduction Proper physical activity is related to the prevention and the treatment of osteoporosis. Purpose To assess the level of physical activity (PA) in post-menopausal women with low bone mineral density (BMD). Methods This cross-sectional clinical study included 123 post-menopausal women. The inclusion criteria were: age of ≥ 45 years with last menses at least 12 months prior to the initiation of the study, and bone density scan (BDS) values measured over the preceding 12 months. Women with severe osteoarthritis were excluded. Women were allocated into three groups, according to BMD measured by BDS [osteoporosis (OP; 54 women), osteopenia (35 women), and normal bone density (NBD; 35 women)], and compared for general, clinical, and anthropometric data, and for PA level. The latter was assessed using the International Physical Activity Questionnaire (IPAQ), in metabolic equivalent of task (MET) units. Participants were classified as sedentary, active or very active. Quantitative variables were compared using ANOVA followed by Tukey's test. Associations between qualitative variables were tested by Chi-square (χ2) or Fisher's exact test. In order to check for differences among groups and IPAQ domains, a generalized linear model with Gamma distribution was adjusted for values in METs. Results The OP group differed from the NBD group regarding age (61.8 ± 10.1 and 52.9 ± 5.4 years), percentage of participants with self-declared white ethnicity (43.9 and 28.0%), body mass index (BMI - 25.7 ± 5.4 and 30.9 ± 5.1 kg/m(2)), and time since menopause (15.5 ± 7.5 and 5.8 ± 4.5 years). Smoking rates were higher in the OP (55.6%) and NBD groups (33.3%) than in the osteopenia group (11.1%). Within the OP group, the rate of subjects with sedentary lifestyles was higher (42.6%), and time spent sitting was greater (344.3 ± 204.8 METs) than in the groups with osteopenia (20.0% and 300.9 ± 230.6 METs) and NBD (17.7% and 303

  15. Theoretical study on the adsorption of phenol on activated carbon using density functional theory.

    PubMed

    Cam, Le Minh; Van Khu, Le; Ha, Nguyen Ngoc

    2013-10-01

    Density functional theory (DFT) calculations performed at the PBE/DZP level using the DFT-D2 method were utilized to investigate the adsorption of phenol on pristine activated carbon (AC) and on activated carbon functionalized with OH, CHO, or COOH groups. Over the pristine AC, the phenol molecule undergoes weak physical adsorption due to van der Waals interactions between the aromatic part of the phenol and the basal planes of the AC. Among the three functional groups used to functionalize the AC, the carboxylic group was found to interact most strongly with the hydroxyl group of phenol. These results suggest that functionalized AC-COOH has great potential for use in environmental applications as an adsorbent of phenol molecules in aqueous phases. PMID:23918222

  16. Control of microbial activity by flow injection analysis during high cell density cultivation of Escherichia coli.

    PubMed

    Ding, T; Bilitewski, U; Schmid, R D; Korz, D J; Sanders, E A

    1993-01-01

    The application of an automated flow injection analysis (FIA) system for on-line determination of microbial activity, during high cell density cultivations of Escherichia coli is reported. Based on a bioelectrochemical principle, the FIA method used a redox mediator (potassium hexacyanoferrate(III)) to facilitate electron transfer from the microorganisms to an electrochemical detector. Assays were carried out using a new sampling device which provided aseptic operation by use of a valve and chemical sterilisation. No sample dilution or pretreatment was necessary for biomass concentrations up to approx. 40 g l-1. The sample volume was 0.5 ml and the overall analysis time was 5 min. FIA signals were found to correlate well with the oxygen uptake rate (OUR). Changes in metabolic activity due to low substrate levels or high inhibitor concentrations in the cultivation medium became obvious from the FIA signals. PMID:7763463

  17. Pharmacogenetics of paraoxonase activity: elucidating the role of high-density lipoprotein in disease

    PubMed Central

    Kim, Daniel Seung; Marsillach, Judit; Furlong, Clement E; Jarvik, Gail P

    2014-01-01

    PON1 is a key component of high-density lipoproteins (HDLs) and is at least partially responsible for HDL's antioxidant/atheroprotective properties. PON1 is also associated with numerous human diseases, including cardiovascular disease, Parkinson's disease and cancer. In addition, PON1 metabolizes a broad variety of substrates, including toxic organophosphorous compounds, statin adducts, glucocorticoids, the likely atherogenic l-homocysteine thiolactone and the quorum-sensing factor of Pseudomonas aeruginosa. Numerous cardiovascular and antidiabetic pharmacologic agents, dietary macronutrients, lifestyle factors and antioxidant supplements affect PON1 expression and enzyme activity levels. Owing to the importance of PON1 to HDL function and its individual association with diverse human diseases, pharmacogenomic interactions between PON1 and the various factors that alter its expression and activity may represent an important therapeutic target for future investigation. PMID:24024900

  18. A density functional theory model of mechanically activated silyl ester hydrolysis

    SciTech Connect

    Pill, Michael F.; Schmidt, Sebastian W.; Beyer, Martin K.; Clausen-Schaumann, Hauke; Kersch, Alfred

    2014-01-28

    To elucidate the mechanism of the mechanically activated dissociation of chemical bonds between carboxymethylated amylose (CMA) and silane functionalized silicon dioxide, we have investigated the dissociation kinetics of the bonds connecting CMA to silicon oxide surfaces with density functional calculations including the effects of force, solvent polarizability, and pH. We have determined the activation energies, the pre-exponential factors, and the reaction rate constants of candidate reactions. The weakest bond was found to be the silyl ester bond between the silicon and the alkoxy oxygen atom. Under acidic conditions, spontaneous proton addition occurs close to the silyl ester such that neutral reactions become insignificant. Upon proton addition at the most favored position, the activation energy for bond hydrolysis becomes 31 kJ mol{sup −1}, which agrees very well with experimental observation. Heterolytic bond scission in the protonated molecule has a much higher activation energy. The experimentally observed bi-exponential rupture kinetics can be explained by different side groups attached to the silicon atom of the silyl ester. The fact that different side groups lead to different dissociation kinetics provides an opportunity to deliberately modify and tune the kinetic parameters of mechanically activated bond dissociation of silyl esters.

  19. Deriving plasma densities in tenuous plasma regions, with the spacecraft potential under active control

    NASA Astrophysics Data System (ADS)

    Andriopoulou, M.; Nakamura, R.; Torkar, K.; Baumjohann, W.; Hoelzl, B.

    2015-11-01

    Variations of the floating potential on spacecraft are often used to derive plasma densities, complementing the plasma instrument measurements. All spacecraft of the Cluster mission are equipped with Active Spacecraft POtential Control (ASPOC) instruments that control the spacecraft potential. Although the ASPOC operation increases the accuracy of electric field and plasma measurements, it prevents a direct use of the spacecraft potential variations to derive plasma densities. In this work we develop a new reconstruction method of uncontrolled spacecraft potential from controlled spacecraft potential data and a derived photoelectron curve, using multispacecraft observations. We assume that the same curve governs the plasma environment for the spacecraft with ASPOC on and off. The current work focuses on reconstructions in the magnetotail region. The period that was more extensively studied was the one from August to October 2003, when the spacecraft were close to each other, while results from the periods of August-October 2001, 2002, and 2004, when the Cluster spacecraft had their apogee in the magnetotail region, are also presented. In this way, we investigate how the photoelectron curve varies at different time intervals and also how the reconstruction results are modified when the distance between the spacecraft is increasing. Finally, by using the reconstructed results, we proceed by estimating the plasma densities and we discuss the uncertainties of such estimations. While, on average, spacecraft potential measurements are successfully reconstructed, plasma and solar activity variations on short timescales seem to affect the reconstructions, requiring in some cases more detailed analysis in order to achieve results with higher accuracy. Moreover, there are some limitations while deriving results in very tenuous plasma regions due to increased uncertainties in some of the scientific measurements used there. The results and the methods developed for this work

  20. Mapping the polarity and stimulus density requirements for T-cell activation

    NASA Astrophysics Data System (ADS)

    Wei, Xunbin; Krasieva, Tatiana B.; Zhang, Zhanxiang; Negulescu, Paul A.; Sun, Chung-Ho; Berns, Michael W.; Cahalan, Michael D.; Tromberg, Bruce J.

    1998-08-01

    T-cell contact with antigen-presenting cells (APC) initiates an activation cascade which includes an increase in T-cell intracellular calcium [(Ca2+)i] and leads to T-cell proliferation and differentiation. Although T-cell/APC physical contact is required for an immune response, little is known about the patterns of cellular interaction and their relation to activation. We have combined fluorescence spectroscopy and imaging with optical manipulation to investigate the contact requirements for T-cell activation, using optical tweezers to control the orientation of T- cell/APC pairs and fluorescence microscopy to measure the subsequent (Ca2+)i response, detected as an emission shift from the combination of fura-red and oregon- green, two cytoplasmic (Ca2+) indicators. APCs or beads coated with antibodies to the T-cell receptor (TCR) are trapped with a near-infrared titanium-sapphire laser and placed at different locations along the T-cell, which has a polarized appearance defined by the shape and direction of crawling (2-5 micrometers /min). T cells contacted with antigen- presenting cells or antibody-coated beads entered a dynamic and reproducible program in the first 10 - 20 mins, including (Ca2+)i increase, changes in shape and motility, engulfment, and stable contact. T cells presented with antigen at the leading edge had a higher probability of responding (85%) and a shorter latency of response (50 secs) than those contacting APCs or beads with their trailing end (APCs: 30%, 150 secs; beads: 6%, 300 secs). Alterations in antibody density, quantified by FACS analysis, and bead size were used to determine the spatial requirements for T cell activation and the minimum number of receptors which must be engaged in order to transmit a positive signal. Preliminary data show that T cell responses [response percentage, latency and (Ca2+)i pattern] depend on both antibody density and bead size.

  1. ACTIVE CATHODES FOR SUPER-HIGH POWER DENSITY SOLID OXIDE FUEL CELLS THROUGH SPACE CHARGE EFFECTS

    SciTech Connect

    Anil V. Virkar

    2004-03-08

    This report summarizes the work done during the fifth quarter of the project. Effort was directed in two areas: (1) Further development of the model on the role of connectivity on ionic conductivity of porous bodies, including the role of grain boundaries and space charge region. (2) Fabrication of porous samaria-doped ceria (SDC) and investigation of the effect of thermal treatment on its conductivity. The model developed accounts for transport through three regions: (a) Transport through the bulk of the grain, RI, which includes parallel transport through space charge region. (b) Transport through the space charge region adjacent to the neck (grain boundary), RII. (c) Transport through the structural part of the neck (grain boundary), RIII. The work on the model development involves calculation RI, RII, RIII, and the sum of these three terms, which is the total resistance, as a function of the grain radius ranging between 0.5 and 5 microns and as a function of the relative neck size, described in terms of the angle theta, ranging between 5 and 45{sup o}. Three values of resistivity of the space charge region were chosen; space charge resistivity greater than grain resistivity, equal to grain resistivity, and lower than grain resistivity. Experimental work was conducted on samaria (Sm{sub 2}O{sub 3})-doped ceria (SDC) samples of differing porosity levels, before and after thermal treatment at 1200 C. The conductivity in the annealed samples was lower, consistent with enhanced Debye length. This shows the important role of space charge on ionic transport, and its implications concerning cathode polarization.

  2. Investigating concentration distributions of arsenic, gold and antimony in grain-size fractions of gold ore using instrumental neutron activation analysis.

    PubMed

    Nyarku, M; Nyarko, B J B; Serfor-Armah, Y; Osae, S

    2010-02-01

    Instrumental neutron activation analysis (INAA) has been used to quantify concentrations of arsenic (As), gold (Au) and antimony (Sb) in grain-size fractions of a gold ore. The ore, which was taken from the Ahafo project site of Newmont Ghana Gold Ltd., was fractionated into 14 grain-size fractions using state-of-the-art analytical sieve machine. The minimum sieve mesh size used was 36mum and grains >2000mum were not considered for analysis. Result of the sieving was analysed with easysieve(R) software. The<36mum subfraction was found to be the optimum, hosting bulk of all three elements. Arsenic was found to be highly concentrated in<36-100mum size fractions and erratically distributed in from 150mum fraction and above. For gold, with the exception of the subfraction <36mum which had exceptionally high concentration, the element was found to be approximately equally distributed in all the size fractions but slightly "played out" in 150-400mum size fractions. Antimony occurrence in the sample was relatively high in <36mum size fraction followed by 600, 800, 400 and 36mum size fractions in that order. Gold content in the sample was comparatively far greater than arsenic and antimony; this is indicative of level of gold mineralization in the concession where the sample ore was taken. The concentration of gold in the composite sample was in the range 564-8420ppm as compared to 14.33-186.92ppm for arsenic and 1.09-9.48ppm for antimony. Elemental concentrations were correlated with each other and with grain-size fractions and the relationships between these descriptive parameters were established. PMID:19896855

  3. Protective effect of high density lipoprotein associated paraoxonase. Inhibition of the biological activity of minimally oxidized low density lipoprotein.

    PubMed Central

    Watson, A D; Berliner, J A; Hama, S Y; La Du, B N; Faull, K F; Fogelman, A M; Navab, M

    1995-01-01

    Our group has previously demonstrated that oxidized phospholipids in mildly oxidized LDL (MM-LDL) produced by oxidation with lipoxygenase, iron, or cocultures of artery wall cells increase monocyte-endothelial interactions and this sequence of events is blocked by HDL. To obtain further insight into the mechanism by which HDL abolishes the activity of MM-LDL we investigated the effect of the HDL-associated ester hydrolase paraoxonase (PON). Treatment of MM-LDL with purified PON significantly reduced the ability of MM-LDL to induce monocyte-endothelial interactions. Inactivation of PON by pretreating HDL with heat or EDTA reduced the ability of HDL to inhibit LDL modification. HPLC analysis of phospholipids isolated from MM-LDL before and after treatment with purified PON showed that the 270 nm absorbance of phospholipids was decreased, while no effect was observed on 235 nm absorbance. Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (Ox-PAPC) and specific fractions of Ox-PAPC isolated by HPLC induced the same monocyte-endothelial interactions as did MM-LDL. Biologically active and inactive HPLC fractions of Ox-PAPC were compared by fast atom bombardment-mass spectrometry which revealed that active fractions possessed ions with a mass to charge [correction of change] ratio greater than native PAPC by multiples of 16 D suggesting the addition of 3 and 4 oxygen atoms to PAPC. Comparison of Ox-PAPC by fast atom bombardment-mass spectrometry before and after PON treatment showed that PON destroyed these multi-oxygenated molecules found in biologically active fractions of Ox-PAPC. These results suggest that PON in HDL may protect against the induction of inflammatory responses in artery wall cells by destroying biologically active lipids in mildly oxidized LDL. Images PMID:8675659

  4. The condensation and vaporization behavior of H2O:CO ices and implications for interstellar grains and cometary activity

    NASA Technical Reports Server (NTRS)

    Sandford, Scott A.; Allamandola, Louis J.

    1988-01-01

    IR spectroscopy has been used to ascertain several parameters associated with CO, H2O, and H2O:CO ices' physical behavior. Since CO is noted to be capable of condensing into H2O-rich ices at temperatures that are twice as high as those required for condensation in pure CO, CO is able to condense onto H2O-rich ice grains at temperatures of up to 50 K. CO's presence in H2O ice modestly enhances the effective volatility of the H2O. Attention is given to the implications of these results for cometary models generally and the question of cometary formation specifically.

  5. ACTIVE CATHODES FOR SUPER-HIGH POWER DENSITY SOLID OXIDE FUEL CELLS THROUGH SPACE CHARGE EFFECTS

    SciTech Connect

    Anil V. Virkar

    2003-12-12

    This report summarizes the work done during the fourth quarter of the project. Effort was directed in two areas, namely, continued further development of the model on the role of connectivity on ionic conductivity of porous bodies, including the role of grain boundaries and space charge, and its relationship to cathode polarization; and fabrication of samaria-doped ceria porous (SDC). The work on the model development involves calculation of the effect of space charge on transport through porous bodies. Three specific cases have been examined: (1) Space charge resistivity greater than the grain resistivity, (2) Space charge resistivity equal to the grain resistivity, and (3) Space charge resistivity lower than the grain resistivity. The model accounts for transport through three regions: the bulk of the grain, the space charge region, and the structural part of the grain boundary. The effect of neck size has been explicitly incorporated. In future work, the effective resistivity will be incorporated into the effective cathode polarization resistance. The results will then be compared with experiments.

  6. Colony density and activity times of the ant Camponotus semitestaceus (Hymenoptera: formicidae) in a shrub steppe community

    SciTech Connect

    Gano, K.A.; Rogers, L.E.

    1983-11-01

    Colony densities and above-ground activity periods were determined for Camponotus semitestaceus colonies within a shrub-steppe community. Colony densities (anti-x +/- SD) averaged 0.088 +/- 0.032 per m/sup 2/ and 0.048 +/- 0.028 per m/sup 2/ on two sagebrush-bunchgrass sites an

  7. Enhanced Sphingomyelinase Activity Contributes to the Apoptotic Capacity of Electronegative Low-Density Lipoprotein.

    PubMed

    Ke, Liang-Yin; Chan, Hua-Chen; Chen, Chih-Chieh; Lu, Jonathan; Marathe, Gopal K; Chu, Chih-Sheng; Chan, Hsiu-Chuan; Wang, Chung-Ya; Tung, Yi-Ching; McIntyre, Thomas M; Yen, Jeng-Hsien; Chen, Chu-Huang

    2016-02-11

    Sphingomyelinase (SMase) catalyzes the degradation of sphingomyelin to ceramide. In patients with metabolic syndrome or diabetes, circulating plasma ceramide levels are significantly higher than in normal individuals. Our data indicate that electronegative low-density lipoprotein (LDL) shows SMase activity, which leads to increased ceramide levels that can produce pro-inflammatory effects and susceptibility to aggregation. According to sequence alignment and protein structure predictions, the putative catalytic site of SMase activity is in the α2 region of apoB-100. To identify specific post-translational modifications of apoB100 near the catalytic region, we performed data-independent, parallel-fragmentation liquid chromatography/mass spectrometry (LC/MS(E)), followed by data analysis with ProteinLynx GlobalServer v2.4. Results showed that the serine of apoB100 in electronegative LDL was highly O-glycosylated, including S(1732), S(1959), S(2378), S(2408), and S(2429). These findings may support the changing of the α-helix/β-pleated sheets ratio in protein structure analysis. Further study is necessary to confirm the activation of SMase activity by electronegative LDL. PMID:26766134

  8. A Comparison of Bone Mineral Density in Amateur Male Boxers and Active Non-boxers.

    PubMed

    Bolam, K A; Skinner, T L; Sax, A T; Adlard, K N; Taaffe, D R

    2016-08-01

    To examine the site-specific osteogenic effect of upper limb impact-loading activity we compared the forearm and arm bone mineral density (BMD) of male boxers to that of active controls. A cross-sectional study was performed with 30 amateur male boxers (aged 18-44 years) and 32 age-matched, non-boxing, active controls. Participants had their regional and whole body BMD and bone mineral content (BMC) assessed by dual-energy X-ray absorptiometry. Hand grip strength, testosterone, oestradiol, sex hormone-binding globulin, vitamin D, lean and fat mass, and past and current physical activity were also assessed. Forearm and arm BMD were 1.5-2.2% higher in boxers than the control group although this was not statistically significant (p>0.05), with no significant difference for BMC (p>0.05). There were no differences between groups for spine, hip, or whole body BMD or BMC, or for body composition or hormone status. Within the arms, lean mass was associated with BMD and BMC in both boxers and the control group (BMD, r=0.60-0.76, p<0.001; BMC, r=0.67-0.82, p<0.001). There were no significant differences between amateur boxers and the control group for upper limb BMD and BMC. However, muscle mass appears to be particularly important to bone health of the upper limbs. PMID:27203576

  9. Fuzzy electron density fragments in macromolecular quantum chemistry, combinatorial quantum chemistry, functional group analysis, and shape-activity relations.

    PubMed

    Mezey, Paul G

    2014-09-16

    Conspectus Just as complete molecules have no boundaries and have "fuzzy" electron density clouds approaching zero density exponentially at large distances from the nearest nucleus, a physically justified choice for electron density fragments exhibits similar behavior. Whereas fuzzy electron densities, just as any fuzzy object, such as a thicker cloud on a foggy day, do not lend themselves to easy visualization, one may partially overcome this by using isocontours. Whereas a faithful representation of the complete fuzzy density would need infinitely many such isocontours, nevertheless, by choosing a selected few, one can still obtain a limited pictorial representation. Clearly, such images are of limited value, and one better relies on more complete mathematical representations, using, for example, density matrices of fuzzy fragment densities. A fuzzy density fragmentation can be obtained in an exactly additive way, using the output from any of the common quantum chemical computational techniques, such as Hartree-Fock, MP2, and various density functional approaches. Such "fuzzy" electron density fragments properly represented have proven to be useful in a rather wide range of applications, for example, (a) using them as additive building blocks leading to efficient linear scaling macromolecular quantum chemistry computational techniques, (b) the study of quantum chemical functional groups, (c) using approximate fuzzy fragment information as allowed by the holographic electron density theorem, (d) the study of correlations between local shape and activity, including through-bond and through-space components of interactions between parts of molecules and relations between local molecular shape and substituent effects, (e) using them as tools of density matrix extrapolation in conformational changes, (f) physically valid averaging and statistical distribution of several local electron densities of common stoichiometry, useful in electron density databank mining, for

  10. Cell growth density modulates cancer cell vascular invasion via Hippo pathway activity and CXCR2 signaling.

    PubMed

    Sharif, G M; Schmidt, M O; Yi, C; Hu, Z; Haddad, B R; Glasgow, E; Riegel, A T; Wellstein, A

    2015-11-26

    Metastasis of cancer cells involves multiple steps, including their dissociation from the primary tumor and invasion through the endothelial cell barrier to enter the circulation and finding their way to distant organ sites where they extravasate and establish metastatic lesions. Deficient contact inhibition is a hallmark of invasive cancer cells, yet surprisingly the vascular invasiveness of commonly studied cancer cell lines is regulated by the density at which cells are propagated in culture. Cells grown at high density were less effective at invading an endothelial monolayer than cells grown at low density. This phenotypic difference was also observed in a zebrafish model of vascular invasion of cancer cells after injection into the yolk sac and extravasation of cancer cells into tissues from the vasculature. The vascular invasive phenotypes were reversible. A kinome-wide RNA interference screen was used to identify drivers of vascular invasion by panning small hairpin RNA (shRNA) library-transduced noninvasive cancer cell populations on endothelial monolayers. The selection of invasive subpopulations showed enrichment of shRNAs targeting the large tumor suppressor 1 (LATS1) kinase that inhibits the activity of the transcriptional coactivator yes-associated protein (YAP) in the Hippo pathway. Depletion of LATS1 from noninvasive cancer cells restored the invasive phenotype. Complementary to this, inhibition or depletion of YAP inhibited invasion in vitro and in vivo. The vascular invasive phenotype was associated with a YAP-dependent upregulation of the cytokines IL6, IL8 and C-X-C motif ligand 1, 2 and 3. Antibody blockade of cytokine receptors inhibited invasion and confirmed that they are rate-limiting drivers that promote cancer cell vascular invasiveness and could provide therapeutic targets. PMID:25772246

  11. Antioxidant activities of distiller dried grains with solubles as protein films containing tea extracts and their application in the packaging of pork meat.

    PubMed

    Yang, Hyun-Ju; Lee, Ji-Hyeon; Won, Misun; Song, Kyung Bin

    2016-04-01

    Distiller dried grains with solubles (DDGS) as protein (DP) films were prepared. Additionally, to prepare anti-oxidant films, green tea extract (GTE), oolong tea extract (OTE), and black tea extract (BTE) were incorporated into the DP films. Consequently, the incorporation of the tea extracts did not alter the physical properties of the films much, whereas the antioxidant activities, such as ABTS and DPPH radical scavenging activities were observed. To apply the DP films containing tea extracts to food packaging, pork meat was wrapped with the films and stored at 4 °C for 10 d. During storage, the pork meat wrapped with the DP films containing GTE, OTE, and BTE had less lipid oxidation than did the control. Among the tea extracts, the DP film containing GTE had the greatest antioxidant activity. These results indicate that the DP films containing green tea extracts can be utilized as an anti-oxidative packaging material for pork meat. PMID:26593480

  12. JNK1 stress signaling is hyper-activated in high breast density and the tumor stroma

    PubMed Central

    Lisanti, Michael P; Tsirigos, Aristotelis; Pavlides, Stephanos; Reeves, Kimberley Jayne; Peiris-Pagès, Maria; Chadwick, Amy L; Sanchez-Alvarez, Rosa; Lamb, Rebecca; Howell, Anthony; Martinez-Outschoorn, Ubaldo E; Sotgia, Federica

    2014-01-01

    Mammography is an important screening modality for the early detection of DCIS and breast cancer lesions. More specifically, high mammographic density is associated with an increased risk of breast cancer. However, the biological processes underlying this phenomenon remain largely unknown. Here, we re-interrogated genome-wide transcriptional profiling data obtained from low-density (LD) mammary fibroblasts (n = 6 patients) and high-density (HD) mammary fibroblasts (n = 7 patients) derived from a series of 13 female patients. We used these raw data to generate a “breast density” gene signature consisting of >1250 transcripts that were significantly increased in HD fibroblasts, relative to LD fibroblasts. We then focused on the genes that were increased by ≥ 1.5-fold (P < 0.05) and performed gene set enrichment analysis (GSEA), using the molecular signatures database (MSigDB). Our results indicate that HD fibroblasts show the upregulation and/or hyper-activation of several key cellular processes, including the stress response, inflammation, stemness, and signal transduction. The transcriptional profiles of HD fibroblasts also showed striking similarities to human tumors, including head and neck, liver, thyroid, lung, and breast cancers. This may reflect functional similarities between cancer-associated fibroblasts (CAFs) and HD fibroblasts. This is consistent with the idea that the presence of HD fibroblasts may be a hallmark of a pre-cancerous phenotype. In these biological processes, GSEA predicts that several key signaling pathways may be involved, including JNK1, iNOS, Rho GTPase(s), FGF-R, EGF-R, and PDGF-R-mediated signal transduction, thereby creating a pro-inflammatory, pro-proliferative, cytokine, and chemokine-rich microenvironment. HD fibroblasts also showed significant overlap with gene profiles derived from smooth muscle cells under stress (JNK1) and activated/infected macrophages (iNOS). Thus, HD fibroblasts may behave like activated

  13. High mature grain phytase activity in the Triticeae has evolved by duplication followed by neofunctionalization of the purple acid phosphatase phytase (PAPhy) gene

    PubMed Central

    Brinch-Pedersen, Henrik

    2013-01-01

    The phytase activity in food and feedstuffs is an important nutritional parameter. Members of the Triticeae tribe accumulate purple acid phosphatase phytases (PAPhy) during grain filling. This accumulation elevates mature grain phytase activities (MGPA) up to levels between ~650 FTU/kg for barley and 6000 FTU/kg for rye. This is notably more than other cereals. For instance, rice, maize, and oat have MGPAs below 100 FTU/kg. The cloning and characterization of the PAPhy gene complement from wheat, barley, rye, einkorn, and Aegilops tauschii is reported here. The Triticeae PAPhy genes generally consist of a set of paralogues, PAPhy_a and PAPhy_b, and have been mapped to Triticeae chromosomes 5 and 3, respectively. The promoters share a conserved core but the PAPhy_a promoter have acquired a novel cis-acting regulatory element for expression during grain filling while the PAPhy_b promoter has maintained the archaic function and drives expression during germination. Brachypodium is the only sequenced Poaceae sharing the PAPhy duplication. As for the Triticeae, the duplication is reflected in a high MGPA of ~4200 FTU/kg in Brachypodium. The sequence conservation of the paralogous loci on Brachypodium chromosomes 1 and 2 does not extend beyond the PAPhy gene. The results indicate that a single-gene segmental duplication may have enabled the evolution of high MGPA by creating functional redundancy of the parent PAPhy gene. This implies that similar MGPA levels may be out of reach in breeding programs for some Poaceae, e.g. maize and rice, whereas Triticeae breeders should focus on PAPhy_a. PMID:23918958

  14. Ultrasound Current Source Density Imaging of the Cardiac Activation Wave Using a Clinical Cardiac Catheter

    PubMed Central

    Qin, Yexian; Li, Qian; Ingram, Pier; Barber, Christy; Liu, Zhonglin

    2015-01-01

    Ultrasound current source density imaging (UCSDI), based on the acoustoelectric (AE) effect, is a noninvasive method for mapping electrical current in 4-D (space + time). This technique potentially overcomes limitations with conventional electrical mapping procedures typically used during treatment of sustained arrhythmias. However, the weak AE signal associated with the electrocardiogram is a major challenge for advancing this technology. In this study, we examined the effects of the electrode configuration and ultrasound frequency on the magnitude of the AE signal and quality of UCSDI using a rabbit Langendorff heart preparation. The AE signal was much stronger at 0.5 MHz (2.99 μV/MPa) than 1.0 MHz (0.42 μV/MPa). Also, a clinical lasso catheter placed on the epicardium exhibited excellent sensitivity without penetrating the tissue. We also present, for the first time, 3-D cardiac activation maps of the live rabbit heart using only one pair of recording electrodes. Activation maps were used to calculate the cardiac conduction velocity for atrial (1.31 m/s) and apical (0.67 m/s) pacing. This study demonstrated that UCSDI is potentially capable of real-time 3-D cardiac activation wave mapping, which would greatly facilitate ablation procedures for treatment of arrhythmias. PMID:25122512

  15. Density Functional Theory Calculations of Activation Energies for Carrier Capture by Defects in Semiconductors

    NASA Astrophysics Data System (ADS)

    Modine, N. A.; Wright, A. F.; Lee, S. R.

    The rate of defect-induced carrier recombination is determined by both defect levels and carrier capture cross-sections. Density functional theory (DFT) has been widely and successfully used to predict defect levels, but only recently has work begun to focus on using DFT to determine carrier capture cross-sections. Lang and Henry developed the theory of carrier-capture by multiphonon emission in the 1970s and showed that carrier-capture cross-sections differ between defects primarily due to differences in their carrier capture activation energies. We present an approach to using DFT to calculate carrier capture activation energies that does not depend on an assumed configuration coordinate and that fully accounts for anharmonic effects, which can substantially modify carrier activation energies. We demonstrate our approach for intrinisic defects in GaAs and GaN and discuss how our results depend on the choice of exchange-correlation functional and the treatment of spin polarization. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  16. Enhanced photocurrent density in graphene/Si based solar cell (GSSC) by optimizing active layer thickness

    SciTech Connect

    Rosikhin, Ahmad Hidayat, Aulia Fikri; Syuhada, Ibnu; Winata, Toto

    2015-12-29

    Thickness dependent photocurrent density in active layer of graphene/Si based solar cell has been investigated via analytical – simulation study. This report is a preliminary comparison of experimental and analytical investigation of graphene/Si based solar cell. Graphene sheet was interfaced with Si thin film forming heterojunction solar cell that was treated as a device model for photocurrent generator. Such current can be enhanced by optimizing active layer thickness and involving metal oxide as supporting layer to shift photons absorption. In this case there are two type of devices model with and without TiO{sub 2} in which the silicon thickness varied at 20 – 100 nm. All of them have examined and also compared with each other to obtain an optimum value. From this calculation it found that generated currents almost linear with thickness but there are saturated conditions that no more enhancements will be achieved. Furthermore TiO{sub 2} layer is effectively increases photon absorption but reducing device stability, maximum current is fluctuates enough. This may caused by the disturbance of excitons diffusion and resistivity inside each layer. Finally by controlling active layer thickness, it is quite useful to estimate optimization in order to develop the next solar cell devices.

  17. Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum Nanotubes

    SciTech Connect

    Matanovic, Ivana; Kent, Paul; Garzon, Fernando; Henson, Neil J.

    2012-07-13

    The structure, stability, and catalytic activity of a number of single- and double-wall platinum (n,m) nanotubes ranging in diameter from 0.3 to 2.0 nm were studied using plane-wave based density functional theory in the gas phase and water environment. The change in the catalytic activity toward the oxygen reduction reaction (ORR) with the size and chirality of the nanotube was studied by calculating equilibrium adsorption potentials for ORR intermediates and by constructing free energy diagrams in the ORR dissociative mechanism network. In addition, the stability of the platinum nanotubes is investigated in terms of electrochemical dissolution potentials and by determining the most stable state of the material as a function of pH and potential, as represented in Pourbaix diagrams. Our results show that the catalytic activity and the stability toward electrochemical dissolution depend greatly on the diameter and chirality of the nanotube. On the basis of the estimated overpotentials for ORR, we conclude that smaller, approximately 0.5 nm in diameter single-wall platinum nanotubes consistently show a huge, up to 400 mV larger overpotential than platinum, indicating very poor catalytic activity toward ORR. This is the result of substantial structural changes induced by the adsorption of any chemical species on these tubes. Single-wall n = m platinum nanotubes with a diameter larger than 1 nm have smaller ORR overpotentials than bulk platinum for up to 180 mV and thus show improved catalytic activity relative to bulk. We also predict that these nanotubes can endure the highest cell potentials but dissolution potentials are still for 110 mV lower than for the bulk, indicating a possible corrosion problem.

  18. On the binding mode of urease active site inhibitors: A density functional study

    NASA Astrophysics Data System (ADS)

    Leopoldini, M.; Marino, T.; Russo, N.; Toscano, M.

    The way with which boric acid, a rapid reversible competitive inhibitor, binds the urease active site was explored at density functional B3LYP level of theory. The catalytic core of the enzyme was simulated by two models of different size. In both cases, amino acid residues belonging to the inner and to the outer coordination spheres of nickel ions were replaced by smaller molecular species. Contrary to the experimental indication that attributes the inhibitory ability of this acid to the lack of a nucleophilic attack by the enzyme to the boron atom, we instead found that another possibility exists based on the presence of a strong covalent sigma bond between boron and urease that we think can be hardly broken to allow any course of the reaction.

  19. Density functional theory study of C₂F₅I synthesis over activated carbon catalyst.

    PubMed

    Hu, Yingjie; Xue, Mengwei; Yang, Guangchen; Pan, Renming

    2015-09-01

    Quantum chemistry calculations based on the density functional theory (DFT) are carried out to investigate the reaction mechanism of C2F5I synthesis catalyzed by activated carbon. The possible adsorption configurations of fluorocarbon intermediates are analyzed carefully. Also, the related transition states and reaction pathway are analyzed. According to calculation, firstly, the dehydrofluorination of C2HF5, as the rate-determining step, is catalyzed by the carboxyl acid groups. Secondly, the tetrafluoroethylidene radicals disproportionate on graphite (001) surface instead of rearrangement or dimerization. Next, the fluorine abstractions between fluorocarbon intermediates over graphite (001) surfaces proceed successfully. Finally, the desorbed pentafluoroethyl abstracts iodine atom from molecular iodine spontaneously to afford C2F5I. In adition, our calculations reveal that the carbon deposit in experiment is caused by the fluorine abstraction from fluoroethinyl. The suggested mechanism corresponds with our calculations and available experiments. PMID:26276012

  20. Density-matrix renormalization-group study of current and activity fluctuations near nonequilibrium phase transitions.

    PubMed

    Gorissen, Mieke; Hooyberghs, Jef; Vanderzande, Carlo

    2009-02-01

    Cumulants of a fluctuating current can be obtained from a free-energy-like generating function, which for Markov processes equals the largest eigenvalue of a generalized generator. We determine this eigenvalue with the density-matrix renormalization group for stochastic systems. We calculate the variance of the current in the different phases, and at the phase transitions, of the totally asymmetric exclusion process. Our results can be described in the terms of a scaling ansatz that involves the dynamical exponent z . We also calculate the generating function of the dynamical activity (total number of configuration changes) near the absorbing-state transition of the contact process. Its scaling properties can be expressed in terms of known critical exponents. PMID:19391693

  1. The Effect of Eectronic Energy Loss on Irradiation-Induced Grain Growth in Nanocrystalline Oxides

    SciTech Connect

    Zhang, Yanwen; Aidhy, Dilpuneet S.; Varga, Tamas; Moll, Sandra; Edmondson, P. D.; Namavar, Fereydoon; Jin, Ke; Ostrouchov, Christopher N.; Weber, William J.

    2014-01-01

    Grain growth of nanocrystalline materials is generally thermally activated, but can also be driven by irradiation at much lower temperature. In nanocrystalline ceria and zirconia, contributions from both displacement damage and ionization to the grain growth are identified. Our atomistic simulations have revealed fast grain boundary (GB) movements due to the high density of disorder near GBs. Our experimental results have shown that irradiation-induced grain growth is a function of total energy deposited, where the excitation of target electrons and displacement of lattice atoms both contribute to the overall disorder and both play important roles in grain growth. The coupling of energy deposition to the electronic and lattice structures should both be taken into consideration when engineering nanostructural materials.

  2. Determinants of bone density among athletes engaged in weight-bearing and non-weight-bearing activity

    NASA Technical Reports Server (NTRS)

    Block, Jon E.; Friedlander, Anne L.; Brooks, George A.; Steiger, Peter; Stubbs, Harrison A.

    1989-01-01

    The effect of weight bearing activity on the bone density was investigated in athletes by comparing the measures of bone density of athletes engaged in weight-training programs with those of polo players and nonexercising subjects. All subjects had measurements of spinal trabecular and integral bone density by quantitative tomography, as well as determinations of hip bone density by dual photon absorptiometry. Results confirmed previous findings by Block et al. (1987) of significantly greater bone density among highly trained athletes compared with nonexercising subjects of similar age. Results also indicated that athletes engaged in non-weight-bearing forms of rigorous exercise had greater levels of bone density. However, as the participants in this study were exceptional athletes, engaged in a strenuous sport with both aerobic and heavy resistance components, a confirmation of these data is needed, using larger samples of individuals.

  3. 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 ...

  4. Critical current density, irreversibility line, and flux creep activation energy in silver-sheathed Bi[sub 2]Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub x] superconducting tapes

    SciTech Connect

    Shi, D.; Wang, Z.; Sengupta, S.; Smith, M. ); Goodrich, L.F. , Boulder, CO . Electromagnetic Technology Div.); Dou, S.X.; Liu, H.K.; Guo, Y.C. . School of Materials and Engineering)

    1992-08-01

    Transport data, magnetic hysteresis and flux creep activation energy experimental results are presented for silver-sheathed high-[Tc] Bi[sub 2]Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub x] superconducting tapes. The 110 K superconducting phase was formed by lead doping in a Bi-Sr-Ca-Cu-0 system. The transport critical current density was measured at 4.0 K to be 0.7 [times] 10[sup 5] A/cm[sup 2] (the corresponding critical current is 74 A) at zero field and 1.6 [times] 10[sup 4] A/cm[sup 2] at 12 T for H[parallel]ab. Excellent grain alignment in the a-b plane was achieved by a short-melting method, which considerably improved the critical current density and irreversibility line. Flux creep activation energy as a function of current is obtained based on the magnetic relaxation measurements.

  5. Critical current density, irreversibility line, and flux creep activation energy in silver-sheathed Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} superconducting tapes

    SciTech Connect

    Shi, D.; Wang, Z.; Sengupta, S.; Smith, M.; Goodrich, L.F.; Dou, S.X.; Liu, H.K.; Guo, Y.C.

    1992-08-01

    Transport data, magnetic hysteresis and flux creep activation energy experimental results are presented for silver-sheathed high-{Tc} Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} superconducting tapes. The 110 K superconducting phase was formed by lead doping in a Bi-Sr-Ca-Cu-0 system. The transport critical current density was measured at 4.0 K to be 0.7 {times} 10{sup 5} A/cm{sup 2} (the corresponding critical current is 74 A) at zero field and 1.6 {times} 10{sup 4} A/cm{sup 2} at 12 T for H{parallel}ab. Excellent grain alignment in the a-b plane was achieved by a short-melting method, which considerably improved the critical current density and irreversibility line. Flux creep activation energy as a function of current is obtained based on the magnetic relaxation measurements.

  6. ACTIVE CATHODES FOR SUPER-HIGH POWER DENSITY SOLID OXIDE FUEL CELLS THROUGH SPACE CHARGE EFFECTS

    SciTech Connect

    Anil V. Virkar

    2003-11-03

    This report summarizes the work done during the third quarter of the project. Effort was directed in two areas: (1) Further development of the model on the role of connectivity on ionic conductivity of porous bodies, including the role of grain boundaries, and its relationship to cathode polarization. Included indirectly through the grain boundary effect is the effect of space charge. (2) Synthesis of LSC + SDC composite cathode powders by combustion synthesis. (3) Fabrication and testing of anode-supported single cells made using synthesized LSC + ScDC composite cathodes.

  7. Transforming a Traditional Hands-On Activity into an Enquiry Activity to Foster More In-Depth Understanding of the Concept of Density

    ERIC Educational Resources Information Center

    Lee, Yeung Chung; Kwok, Ping Wai

    2010-01-01

    Traditional methods used to teach the concept of density that employ solid objects of different masses and volumes can be supplemented by enquiry activities in which students vary the mass-to-volume ratio of the same object to test ideas about density and flotation. A simple substance, Blu-Tack, is an ideal material to use in this case. The…

  8. Characterization of Ichthyocidal Activity of Pfiesteria piscicida: Dependence on the Dinospore Cell Density

    PubMed Central

    Drgon, Tomás; Saito, Keiko; Gillevet, Patrick M.; Sikaroodi, Masoumeh; Whitaker, Brent; Krupatkina, Danara N.; Argemi, Federico; Vasta, Gerardo R.

    2005-01-01

    The ichthyocidal activity of Pfiesteria piscicida dinospores was examined in an aquarium bioassay format by exposing fish to either Pfiesteria-containing environmental sediments or clonal P. piscicida. The presence of Pfiesteria spp. and the complexity of the microbial assemblage in the bioassay were assessed by molecular approaches. Cell-free water from bioassays that yielded significant fish mortality failed to show ichthyocidal activity. Histopathological examination of moribund and dead fish failed to reveal the skin lesions reported elsewhere. Fish larvae within “cages” of variable mesh sizes were killed in those where the pore size exceeded that of Pfiesteria dinospores. In vitro exposure of fish larvae to clonal P. piscicida indicated that fish mortality was directly proportional to the dinospore cell density. Dinospores clustered around the mouth, eyes, and operculi, suggesting that fish health may be affected by their direct interaction with skin, gill epithelia, or mucous surfaces. Molecular fingerprinting revealed the presence of a very diverse microbial community of bacteria, protists, and fungi within bioassay aquaria containing environmental sediments. Some components of the microbial community were identified as potential fish pathogens, preventing the rigorous identification of Pfiesteria spp. as the only cause of fish death. In summary, our results strongly suggest (i) that this aquarium bioassay format, which has been extensively reported in the literature, is unsuitable to accurately assess the ichthyocidal activity of Pfiesteria spp. and (ii) that the ichthyocidal activity of Pfiesteria spp. is mostly due to direct interactions of the zoospores with fish skin and gill epithelia rather than to soluble factors. PMID:15640229

  9. The independent prospective associations of activity intensity and dietary energy density with adiposity in young adolescents.

    PubMed

    van Sluijs, Esther M F; Sharp, Stephen J; Ambrosini, Gina L; Cassidy, Aedin; Griffin, Simon J; Ekelund, Ulf

    2016-03-14

    There is limited evidence on the prospective association of time spent in activity intensity (sedentary (SED), moderate (MPA) or vigorous (VPA) physical activity) and dietary intake with adiposity indicators in young people. This study aimed to assess associations between (1) baseline objectively measured activity intensity, dietary energy density (DED) and 4-year change in adiposity and (2) 4-year change in activity intensity/DED and adiposity at follow-up. We conducted cohort analyses including 367 participants (10 years at baseline, 14 years at follow-up) with valid data for objectively measured activity (Actigraph), DED (4-d food diary), anthropometry (waist circumference (WC), %body fat (%BF), fat mass index (FMI), weight status) and covariates. Linear and logistic regression models were fit, including adjustment for DED and moderate-to-vigorous physical activity. Results showed that baseline DED was associated with change in WC (β for 1kJ/g difference: 0·71; 95% CI 0·26, 1·17), particularly in boys (1·26; 95% CI 0·41, 2·16 v. girls: 0·26; 95% CI -0·34, 0·87), but not with %BF, FMI or weight status. In contrast, baseline SED, MPA or VPA were not associated with any of the outcomes. Change in DED was negatively associated with FMI (β for 1kJ/g increase: -0·86; 95% CI -1·59, -0·12) and %BF (-0·86; 95% CI -1·25, -0·11) but not WC (-0·27; 95% CI -1·02, 0·48). Change in SED, MPA and VPA did not predict adiposity at follow-up. In conclusion, activity intensity was not prospectively associated with adiposity, whereas the directions of associations with DED were inconsistent. To inform public health efforts, future studies should continue to analyse longitudinal data to further understand the independent role of different energy-balance behaviours in changes in adiposity in early adolescence. PMID:26758859

  10. Permeation of oxygen through high purity, large grain silver

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Peregoy, W. K.; Hoflund, Gar B.

    1987-01-01

    The permeation of high purity, large grain Ag membranes by oxygen has been studied over the temperature range 400 to 800 C. The permeability was found to be quite linear and repeatable, but the magnitude was 3.2 times smaller than that determined by past research. Since previous investigators studied substantially less pure Ag and conducted experiments within much poorer vacuum environments (which indicates that their grain boundary density was much greater), the data presented here suggest oxygen transport through the membrane is primarily by grain boundary diffusion. The diffusivity measurements were found to exhibit two distinct linear regions, one above and one below a critical temperature of 630 C. The high-temperature data have an activation energy (11.1 kcal/mole) similar to that reported by others, but the low-temperature data have a higher activation energy (15.3 kcal/mole), which can be explained by impurity trapping in the grain boundaries. Vacuum desorption of the oxygen-saturated Ag was found to occur at a threshold of 630 C, which is consistent with the onset of increased mobility within the grain boundaries.

  11. A new active Li-Mn-O compound for high energy density Li-ion batteries.

    PubMed

    Freire, M; Kosova, N V; Jordy, C; Chateigner, D; Lebedev, O I; Maignan, A; Pralong, V

    2016-02-01

    The search for new materials that could improve the energy density of Li-ion batteries is one of today's most challenging issues. Many families of transition metal oxides as well as transition metal polyanionic frameworks have been proposed during the past twenty years. Among them, manganese oxides, such as the LiMn2O4 spinel or the overlithiated oxide Li[Li1/3Mn2/3]O2, have been intensively studied owing to the low toxicity of manganese-based materials and the high redox potential of the Mn(3+)/Mn(4+) couple. In this work, we report on a new electrochemically active compound with the 'Li4Mn2O5' composition, prepared by direct mechanochemical synthesis at room temperature. This rock-salt-type nanostructured material shows a discharge capacity of 355 mAh g(-1), which is the highest yet reported among the known lithium manganese oxide electrode materials. According to the magnetic measurements, this exceptional capacity results from the electrochemical activity of the Mn(3+)/Mn(4+) and O(2-)/O(-) redox couples, and, importantly, of the Mn(4+)/Mn(5+) couple also. PMID:26595122

  12. A new active Li-Mn-O compound for high energy density Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Freire, M.; Kosova, N. V.; Jordy, C.; Chateigner, D.; Lebedev, O. I.; Maignan, A.; Pralong, V.

    2016-02-01

    The search for new materials that could improve the energy density of Li-ion batteries is one of today’s most challenging issues. Many families of transition metal oxides as well as transition metal polyanionic frameworks have been proposed during the past twenty years. Among them, manganese oxides, such as the LiMn2O4 spinel or the overlithiated oxide Li[Li1/3Mn2/3]O2, have been intensively studied owing to the low toxicity of manganese-based materials and the high redox potential of the Mn3+/Mn4+ couple. In this work, we report on a new electrochemically active compound with the `Li4Mn2O5’ composition, prepared by direct mechanochemical synthesis at room temperature. This rock-salt-type nanostructured material shows a discharge capacity of 355 mAh g-1, which is the highest yet reported among the known lithium manganese oxide electrode materials. According to the magnetic measurements, this exceptional capacity results from the electrochemical activity of the Mn3+/Mn4+ and O2-/O- redox couples, and, importantly, of the Mn4+/Mn5+ couple also.

  13. T-cell activation: A queuing theory analysis at low agonist density.

    PubMed

    Wedagedera, J R; Burroughs, N J

    2006-09-01

    We analyze a simple linear triggering model of the T-cell receptor (TCR) within the framework of queuing theory, in which TCRs enter the queue upon full activation and exit by downregulation. We fit our model to four experimentally characterized threshold activation criteria and analyze their specificity and sensitivity: the initial calcium spike, cytotoxicity, immunological synapse formation, and cytokine secretion. Specificity characteristics improve as the time window for detection increases, saturating for time periods on the timescale of downregulation; thus, the calcium spike (30 s) has low specificity but a sensitivity to single-peptide MHC ligands, while the cytokine threshold (1 h) can distinguish ligands with a 30% variation in the complex lifetime. However, a robustness analysis shows that these properties are degraded when the queue parameters are subject to variation-for example, under stochasticity in the ligand number in the cell-cell interface and population variation in the cellular threshold. A time integration of the queue over a period of hours is shown to be able to control parameter noise efficiently for realistic parameter values when integrated over sufficiently long time periods (hours), the discrimination characteristics being determined by the TCR signal cascade kinetics (a kinetic proofreading scheme). Therefore, through a combination of thresholds and signal integration, a T cell can be responsive to low ligand density and specific to agonist quality. We suggest that multiple threshold mechanisms are employed to establish the conditions for efficient signal integration, i.e., coordinate the formation of a stable contact interface. PMID:16766611

  14. Muscle mitochondrial density after exhaustive exercise in dogs - Prolonged restricted activity and retraining

    NASA Technical Reports Server (NTRS)

    Nazar, K.; Greenleaf, J. E.; Philpott, D.; Pohoska, E.; Olszewska, K.; Kaciuba-Uscilko, H.

    1993-01-01

    The effect of exhaustive treadmill exercise on mitochondrial density (MD) and ultrastructural changes in quadriceps femoris muscle was studied in 7 normal, healthy, male mongrel dogs before and after restricted activity (RA) and following a subsequent 2-month exercise retraining period. Mean time to exhaustion in the 2-month group decreased from 177 +/- 11 min before to 90 +/- 16 min after RA; retraining increased tolerance to 219 +/- 36 min above the pre-RA and 143 percent above the post-RA time. Post-RA exhaustion time in the 5-months group was 25 and 45 min. Muscle samples taken after RA showed abnormalities indicative of degeneration, which were reversed by retraining. Resting MD decreased from a control level of 27.8 percent to 14.7 percent and 16.3 percent, and was restored to 27.1 percent after retraining. Exhaustive exercise caused an increase in MD under control conditions and after RA, but not following retraining. Disruption of mitochondria after exercise was evident after 5-month confinement. Factors causing mitochondrial changes and eventually their disruption during exercise after restricted activity are not related as much to the state of fatigue as to the pre-exercise quality of the muscle modified by disease or training.

  15. T-Cell Activation: A Queuing Theory Analysis at Low Agonist Density

    PubMed Central

    Wedagedera, J. R.; Burroughs, N. J.

    2006-01-01

    We analyze a simple linear triggering model of the T-cell receptor (TCR) within the framework of queuing theory, in which TCRs enter the queue upon full activation and exit by downregulation. We fit our model to four experimentally characterized threshold activation criteria and analyze their specificity and sensitivity: the initial calcium spike, cytotoxicity, immunological synapse formation, and cytokine secretion. Specificity characteristics improve as the time window for detection increases, saturating for time periods on the timescale of downregulation; thus, the calcium spike (30 s) has low specificity but a sensitivity to single-peptide MHC ligands, while the cytokine threshold (1 h) can distinguish ligands with a 30% variation in the complex lifetime. However, a robustness analysis shows that these properties are degraded when the queue parameters are subject to variation—for example, under stochasticity in the ligand number in the cell-cell interface and population variation in the cellular threshold. A time integration of the queue over a period of hours is shown to be able to control parameter noise efficiently for realistic parameter values when integrated over sufficiently long time periods (hours), the discrimination characteristics being determined by the TCR signal cascade kinetics (a kinetic proofreading scheme). Therefore, through a combination of thresholds and signal integration, a T cell can be responsive to low ligand density and specific to agonist quality. We suggest that multiple threshold mechanisms are employed to establish the conditions for efficient signal integration, i.e., coordinate the formation of a stable contact interface. PMID:16766611

  16. Bone mineral density and body composition in a myelomeningocele children population: effects of walking ability and sport activity.

    PubMed

    Ausili, E; Focarelli, B; Tabacco, F; Fortunelli, G; Caradonna, P; Massimi, L; Sigismondi, M; Salvaggio, E; Rendeli, C

    2008-01-01

    Myelomeningocele causes serious locomotor disability, osteoporosis and pathologic fractures. The aim of this study was to investigate the relationship between body composition, bone mineral density, walking ability and sport activity in myelomeningocele children. 60 patients aged between 5 and 14 yrs with myelomeningocele (22 ambulatory and 38 non-ambulatory), were studied. Fat mass and fat-free-mass were calculated by anthropometry. The bone mineral density at lumbar and femoral neck were evaluated. Bone mineral density at the lumbar and femoral neck was lower than in the normal population. In the non-ambulaty group, bone mineral density was approximately 1 SD lower than in the ambulatory one (p < 0.01). Fat mass was greater than expected but without significantly differences between walking group (mean 26%) and wheel-chair users (25%). Patients practised sport activity had a better bone mineral density and body fat compared with other patients with the same disability. Patients with myelomeningocele have decreased bone mineral density and are at higher risk of pathologic bone fractures. All subjects showed an excess of fat as percentage of body weight and are shorter than normal children. The measurement of bone mineral density may help to identify those patients at greatest risk of suffering of multiple fractures. Walk ability and sport activity, associated with the development of muscle mass, are important factors in promoting bone and body growth, to reduce the risk of obesity and of pathological fractures. PMID:19146196

  17. 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.

  18. Strain localization in ultramylonitic calcite marbles by dislocation creep-accommodated grain boundary sliding

    NASA Astrophysics Data System (ADS)

    Rogowitz, Anna; Grasemann, Bernhard; Clancy White, Joseph

    2015-04-01

    Strain localization in monomineralic rocks is often associated with brittle precursors, resulting in stress and strain concentration, followed by grain size reduction and activation of grain-size-sensitive deformation mechanisms such as diffusion creep, grain boundary sliding and cataclastic flow. The aforementioned mechanisms typically tend to produce a random crystallographic orientation or a decrease in intensity of a pre-existing texture. However, reports of fine grained polycrystalline materials showing a preferred crystallographic orientation indicate a need for subsequent grain re-organization by either static annealing or the activation of additional deformation mechanisms in conjunction with grain boundary sliding. We present observations from an almost pure calcite marble layer from Syros Island (Cyclades, Greece) deformed in lower greenschist facies conditions. The presence of a crack (i.e. cross-cutting element) that rotated during shear resulted in the formation of a flanking structure. At the location of maximum displacement (120 cm) along the cross-cutting element, the marble is extremely fine grained (3 µm) leading to anticipation of deformation by grain-size-sensitive mechanisms. Detailed microstructural analysis of the highly strained (80 < gamma < 1000) calcite ultramylonite by optical microscopy, electron backscatter diffraction and scanning transmission electron microscopy show that recrystallization by bulging results in small, strain-free grains. The change in grain size appears to be concomitant with increased activity of independent grain boundary sliding as indicated by a random misorientation angle distribution. At the same time, dislocation multiplication through Frank-Read sources produces high mean dislocation density (~ 5x10^13 m^-2) as well as a weak primary CPO; the latter all argue that grain boundary sliding was accommodated by dislocation activity. Theoretical and experimental determined relationships (paleowattmeter

  19. Carbon dioxide activation and dissociation on ceria (110): A density functional theory study

    NASA Astrophysics Data System (ADS)

    Cheng, Zhuo; Sherman, Brent J.; Lo, Cynthia S.

    2013-01-01

    Ceria (CeO2) is a promising catalyst for the reduction of carbon dioxide (CO2) to liquid fuels and commodity chemicals, in part because of its high oxygen storage capacity, yet the fundamentals of CO2 adsorption, activation, and reduction on ceria surfaces remain largely unknown. We use density functional theory, corrected for onsite Coulombic interactions (GGA+U), to explore various adsorption sites and configurations for CO2 on stoichiometric and reduced ceria (110), the latter with either an in-plane oxygen vacancy or a split oxygen vacancy. We find that CO2 adsorption on both reduced ceria (110) surfaces is thermodynamically favored over the corresponding adsorption on stoichiometric ceria (110), but the most stable adsorption configuration consists of CO2 adsorbed parallel to the reduced ceria (110) surface at a split oxygen vacancy. Structural changes in the CO2 molecule are also observed upon adsorption. At the split vacancy, the molecule bends out of plane to form a unidentate carbonate with the remaining oxygen anion at the surface; this is in stark contrast to the bridged carbonate observed for CO2 adsorption at the in-plane vacancy. Also, we analyze the pathways for CO2 conversion to CO on reduced ceria (110). The subtle difference in the energies of activation for the elementary steps suggest that CO2 dissociation is favored on the split vacancy, while the reverse process of CO oxidation may favor the formation of the in-plane vacancy. We thus show how the structure and properties of the ceria catalyst govern the mechanism of CO2 activation and reduction.

  20. Physical Activity Benefits the Skeleton of Children Genetically Predisposed to Lower Bone Density in Adulthood.

    PubMed

    Mitchell, Jonathan A; Chesi, Alessandra; Elci, Okan; McCormack, Shana E; Roy, Sani M; Kalkwarf, Heidi J; Lappe, Joan M; Gilsanz, Vicente; Oberfield, Sharon E; Shepherd, John A; Kelly, Andrea; Grant, Struan Fa; Zemel, Babette S

    2016-08-01

    Both genetics and physical activity (PA) contribute to bone mineral density (BMD), but it is unknown if the benefits of physical activity on childhood bone accretion depend on genetic risk. We, therefore, aimed to determine if PA influenced the effect of bone fragility genetic variants on BMD in childhood. Our sample comprised US children of European ancestry enrolled in the Bone Mineral Density in Childhood Study (N = 918, aged 5 to 19 years, and 52.4% female). We used a questionnaire to estimate hours per day spent in total, high-, and low-impact PA. We calculated a BMD genetic score (% BMD lowering alleles) using adult genome-wide association study (GWAS)-implicated BMD variants. We used dual-energy X-ray absorptiometry to estimate femoral neck, total hip, and spine areal-BMD and total body less head (TBLH) bone mineral content (BMC) Z-scores. The BMD genetic score was negatively associated with each bone Z-score (eg, TBLH-BMC: estimate = -0.03, p = 1.3 × 10(-6) ). Total PA was positively associated with bone Z-scores; these associations were driven by time spent in high-impact PA (eg, TBLH-BMC: estimate = 0.05, p = 4.0 × 10(-10) ) and were observed even for children with lower than average bone Z-scores. We found no evidence of PA-adult genetic score interactions (p interaction > 0.05) at any skeletal site, and there was no evidence of PA-genetic score-Tanner stage interactions at any skeletal site (p interaction > 0.05). However, exploratory analyses at the individual variant level revealed that PA statistically interacted with rs2887571 (ERC1/WNT5B) to influence TBLH-BMC in males (p interaction = 7.1 × 10(-5) ), where PA was associated with higher TBLH-BMC Z-score among the BMD-lowering allele carriers (rs2887571 AA homozygotes: estimate = 0.08 [95% CI 0.06, 0.11], p = 2.7 × 10(-9) ). In conclusion, the beneficial effect of PA on bone, especially high-impact PA, applies to the average child and those

  1. Ca2+ influx into lily pollen grains through a hyperpolarization-activated Ca2+-permeable channel which can be regulated by extracellular CaM.

    PubMed

    Shang, Zhong-lin; Ma, Li-geng; Zhang, Hai-lin; He, Rui-rong; Wang, Xue-chen; Cui, Su-juan; Sun, Da-ye

    2005-04-01

    Confocal laser scanning microscopy (CLSM) and whole-cell patch-clamp were used to investigate the role of Ca2+ influx in maintaining the cytosolic Ca2+ concentration ([Ca2+]c) and the features of the Ca2+ influx pathway in germinating pollen grains of Lilium davidii D. [Ca2+]c decreased when Ca2+ influx was inhibited by EGTA or Ca2+ channel blockers. A hyperpolarization-activated Ca2+-permeable channel, which can be suppressed by trivalent cations, verapamil, nifedipine or diltiazem, was identified on the plasma membrane of pollen protoplasts with whole-cell patch-clamp recording. Calmodulin (CaM) antiserum and W7-agarose, both of which are cell-impermeable CaM antagonists, lead to a [Ca2+]c decrease, while exogenous purified CaM triggers a transient increase of [Ca2+]c and also remarkably activated the hyperpolarization-activated Ca2+ conductance on plasma membrane of pollen protoplasts in a dose-dependent manner. Both the increase of [Ca2+]c and the activation of Ca2+ conductance which were induced by exogenous CaM were inhibited by EGTA or Ca2+ channel blockers. This primary evidence showed the presence of a voltage-dependent Ca2+-permeable channel, whose activity may be regulated by extracellular CaM, in pollen cells. PMID:15695439

  2. Investigation of the density wave activity in the thermosphere above 220 KM

    NASA Astrophysics Data System (ADS)

    Illés-Almár, E.; Almár, I.; Bencze, P.

    Based on CACTUS (Capteur Accélérométrique Capacitif Triaxial Ultra Sensible) microaccelerometer measurements it has been demonstrated that - after taking into account all effects included in the MSIS'86=CIRA'86 (COSPAR, 1988) model - there are residual fluctuations in the density of the upper atmosphere much larger than that the accuracy of the measurements can account for. These fluctuations are attributed to some kind of wave activity (Illés-Almár, 1993, Illés-Almár et al. 1996a). The average deviations from a model are considered as a measure of the amplitude of the waves in the atmosphere and are analysed as a function of geomagnetic coordinates, altitude and local solar time, in order to identify possible wave sources either in the lower lying atmosphere or in the thermosphere/ionosphere system. As a first step, the present investigation intends to make a map of the wave pattern by this method.

  3. THE FIRST HARD X-RAY POWER SPECTRAL DENSITY FUNCTIONS OF ACTIVE GALACTIC NUCLEUS

    SciTech Connect

    Shimizu, T. Taro; Mushotzky, Richard F.

    2013-06-10

    We present results of our power spectral density (PSD) analysis of 30 active galactic nuclei (AGNs) using the 58 month light curves from Swift's Burst Alert Telescope (BAT) in the 14-150 keV band. PSDs were fit using a Monte Carlo based algorithm to take into account windowing effects and measurement error. All but one source were found to be fit very well using an unbroken power law with a slope of {approx} - 1, consistent at low frequencies with previous studies in the 2-10 keV band, with no evidence of a break in the PSD. For five of the highest signal-to-noise ratio sources, we tested the energy dependence of the PSD and found no significant difference in the PSD at different energies. Unlike previous studies of X-ray variability in AGNs, we do not find any significant correlations between the hard X-ray variability and different properties of the AGN including luminosity and black hole mass. The lack of break frequencies and correlations seem to indicate that AGNs are similar to the high state of Galactic black holes.

  4. Study on flavonoid migration from active low-density polyethylene film into aqueous food simulants.

    PubMed

    Zhang, Shuangling; Zhao, Haiyan

    2014-08-15

    The migration of flavonoids from low-density polyethylene (LDPE) film (0.4%, w/w) to aqueous food simulants over 16 weeks at 0, 15, and 30 °C was investigated. The migration amount of total flavonoids was calculated based on the rutin contents determined by high-performance liquid chromatography (HPLC). Diffusion and partition coefficients, along with the activation energy (Ea) were calculated based on Fick's second law. The results showed that the migration of flavonoids was influenced by temperature, time and the simulants. The Ea values for flavonoid diffusion were 49.2, 55.9, and 25.8 kJ mol(-1) in distilled water, 4% acetic acid and 30% ethanol, respectively. This study indicated that the flavonoids in LDPE film easily migrated into food simulants; and this behaviour was related to the low Ea values of flavonoid diffusion, especially in ethanol at 0-30 °C, when the antioxidants were released from the film. PMID:24679750

  5. Impact Ignition of Low Density Mechanically Activated and Multilayer Foil Ni/Al

    NASA Astrophysics Data System (ADS)

    Beason, Matthew; Mason, B.; Son, Steven; Groven, Lori

    2013-06-01

    Mechanical activation (MA) via milling of reactive materials provides a means of lowering the ignition threshold of shock initiated reactions. This treatment provides a finely mixed microstructure with wide variation in the resulting scales of the intraparticle microstructure that makes model validation difficult. In this work we consider nanofoils produced through vapor deposition with well defined periodicity and a similar degree of fine scale mixing. This allows experiments that may be easier to compare with computational models. To achieve this, both equimolar Ni/Al powder that has undergone MA using high energy ball milling and nanofoils milled into a powder using low energy ball milling were used. The Asay Shear impact experiment was conducted on both MA Ni/Al and Ni/Al nanofoil-based powders at low densities (<60%) to examine their impact response and reaction behavior. Scanning electron microscopy and energy-dispersive x-ray spectroscopy were used to verify the microstructure of the materials. The materials' mechanical properties were evaluated using nano-indentation. Onset temperatures were evaluated using differential thermal analysis/differential scanning calorimetry. Impact ignition thresholds, burning rates, temperature field, and ignition delays are reported. Funding from the Defense Threat Reduction Agency (DTRA) Grant Number HDTRA1-10-1-0119. Counter-WMD basic research program, Dr. Suhithi M. Peiris, program director is gratefully acknowledged.

  6. 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…

  7. 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,…

  8. 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.

  9. 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.

  10. Evaluation of enzyme activity and fiber content of soybean cotyledon fiber and distiller's dried grains with solubles by solid state fermentation.

    PubMed

    Yang, Shengli; Lio, JunYi; Wang, Tong

    2012-05-01

    To increase the value of coproducts from corn ethanol fermentation and soybean aqueous processing, distiller's dried grains with solubles (DDGS) and soybean cotyledon fiber were used as the substrates for solid state fermentation (SSF) to improve feed digestibility. Aspergillus oryzae, Trichoderma reesei, and Phanerochaete chrysosporium were chosen as they produce desirable enzymes and are widely used in SSF for feed. The results showed that the cellulase and xylanase activities were significantly increased after 7 days of fermentation, and cellulose and hemicellulose degradation was also greatly increased. When soybean fiber was used as SSF substrate, the maximum activities of the cellulase and xylanase were 10.3 and 84.2 IU/g substrate (dry weight basis) after SSF treatment, respectively. However, the enzyme activities were relatively low in DDGS, and the growth of the three fungi was poor. The fungi grew better when soybean cotyledon fiber was added to DDGS, and cellulase and xylanase activity increased with the increase of soybean fiber content. Porosity was identified as an important factor for SSF because the addition of inert soybean hull alone improved the fungi growth significantly. These data suggest that the nutritional value of DDGS and soybean cotyledon fiber as monogastric animal feed could be greatly enhanced by SSF treatment. PMID:22528656

  11. Radical formation, chemical processing, and explosion of interstellar grains

    NASA Technical Reports Server (NTRS)

    Greenberg, J. M.

    1976-01-01

    The ultraviolet radiation in interstellar space is shown to create a sufficient steady-state density of free radicals in the grain mantle material consisting of oxygen, carbon, nitrogen, and hydrogen to satisfy the critical condition for initiation of chain reactions. The criterion for minimum critical particle size for maintaining the chain reaction is of the order of the larger grain sizes in a distribution satisfying the average extinction and polarization measures. The triggering of the explosion of interstellar grains leading to the ejection of complex interstellar molecules is shown to be most probable where the grains are largest and where radiation is suddenly introduced; i.e., in regions of new star formation. Similar conditions prevail at the boundaries between very dark clouds and H II regions. When the energy released by the chemical activity of the free radicals is inadequate to explode the grain, the resulting mantle material must consist of extremely large organic molecules which are much more resistant to the hostile environment of H II regions than the classical dirty-ice mantles made up of water, methane, and ammonia.

  12. Variation of D-region nitric-oxide density with solar activity and season at the dip equator

    NASA Technical Reports Server (NTRS)

    Chakrabarty, D. K.; Pakhomov, S. V.; Beig, G.

    1989-01-01

    To study the solar control on electron density (N sub e) in the equatorial D region, a program was initiated with Soviet collaboration in 1979. A total of 31 rockets were launched during the high solar activity period, and 47 rockets during the low solar activity period, from Thumba to measure the N sub e profiles. Analysis of the data shows that the average values of N sub e for the high solar activity period are higher by a factor of about 2 to 3 compared to the low solar activity values. It was found that a single nitric oxide density, (NO), profile cannot reproduce all the observed N sub e profiles. An attempt was made to reproduce theoretically the observed N sub e profiles by introducing variation in (NO) for the different solar activity periods and seasons.

  13. Declining densities and reproductive activities of the queen conch Strombus gigas (Mesogastropoda: Strombidae) in Banco Chinchorro, eastern Caribbean, Mexico.

    PubMed

    De Jesús-Navarrete, Alberto; Valencia-Hernández, Adriana

    2013-12-01

    Queen conch is a gastropod inhabiting the Caribbean Sea, it represents the second largest fishery after the spiny lobster, but it has been extensively captured in the area. In order to know its population status in Chinchorro Bank, we determined conch density changes and its effects on reproductive activities, between July and November 2009. For this, data on conch density, morphology and reproductive activities were obtained from 15 sites within three fishing zones, and compared with previously collected data (1990, 1992, 1994, and 1997). Data showed that adult density decreased with time, from 10,700 ind./ha in 1990, to 198 ind./h in 2009. Neither egg masses nor spawns were found and mating was only observed once in July 2009. In July, adult (lip>4 mm) density in the Southern zone was 23 ind./ha whereas in the Northern zone and Central zone densities were 15 and 9ind./ha respectively. In November, density was somewhat higher: Southern zone 96 ind./ha; Central zone 39 ind./ha and Northern zone had 38ind./ha. In July, mean shell length was 170.80 +/- 46.28 mm, with a higher median abundance at 180-189 mm. In November, higher frequency was 187.63 +/- 45.14 mm, maximumat 210-219 mm interval. For the last 10 years period, mean adult conch densities have diminished in each zone, which might be the main cause of decreased reproductive activities of the conch at Banco Chinchorro. It is therefore an immediate need to analyse the management plan for this species in this Reserve and perhaps to promote a re-population of queen conch and culture activities. PMID:24432527

  14. NUCLEOPHILIC ADDITION TO ACTIVATED DOUBLE BONDS: PREDICTION OF REACTIVITY FROM THE LAPLACIAN OF CHARGE DENSITY

    EPA Science Inventory

    The reactivities of a series of molecules in a Michael addition reaction are analyzed on the basis of properties expressed in the Laplacian of the charge density distribution. he charge densities of structurally optimized acrylic acid (AA), methacrylic acid (MAA), acrylonitrile (...

  15. 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.

  16. Evaluation of high density lipoprotein as a circulating biomarker of Gaucher disease activity

    PubMed Central

    Stein, Philip; Yang, Ruhua; Liu, Jun; Pastores, Gregory M.; Mistry, Pramod K.

    2011-01-01

    Circulating biomarkers are important surrogates for monitoring disease activity in type I Gaucher disease (GD1). We and others have reported low high-density lipoprotein (HDL) in GD1. We assessed HDL cholesterol as a biomarker of GD1, with respect to its correlation with indicators of disease severity and its response to imiglucerase enzyme replacement therapy (ERT). In 278 consecutively evaluated GD1 patients, we correlated HDL cholesterol, chitotriosidase, and angiotensin-converting enzyme (ACE) with indicators of disease severity. Additionally, we measured the response of these biomarkers to ERT. HDL cholesterol was negatively correlated with spleen volume, liver volume, and GD severity score index; the magnitude of this association of disease severity with HDL cholesterol was similar to that for ACE and for chitotriosidase. Within individual patients monitored over many years, there was a strikingly strong correlation of HDL with liver and spleen volumes; there was a similarly strong correlation of chitotriosidase and ACE with disease severity in individual patients monitored serially over many years (chitotriosidase r=0.96 to 0.98, ACE r =0.88 to 0.94, and HDL r=−0.84 to −0.94, p<0.001). ERT for 3 years resulted in a striking increase of HDL while serum levels of chitotriosidase and ACE decreased. Our results reveal markedly low HDL cholesterol in untreated GD1, a correlation with indicators of disease severity in GD1, and a rise towards normal after ERT. These findings suggest HDL cholesterol merits inclusion within the “biomarker basket” for monitoring of patients with GD1. PMID:21290183

  17. ACTIVE CATHODES FOR SUPER-HIGH POWER DENSITY SOLID OXIDE FUEL CELLS THROUGH SPACE CHARGE EFFECTS

    SciTech Connect

    Anil V. Virkar

    2004-05-17

    This report summarizes the work done during the sixth quarter of the project. Effort was directed in three areas: (1) Further development of the model on the role of connectivity on ionic conductivity of porous bodies, including the role of grain boundaries and space charge region. (2) Calculation of the effect of space charge and morphology of porous bodies on the effective charge transfer resistance of porous composite cathodes. (3) The investigation of the three electrode system for the measurement of cathodic polarization using amperometric sensors.

  18. Angiotensin I-Converting Enzyme inhibitory and antioxidant activities and surfactant properties of protein hydrolysates as obtained of Amaranthus hypochondriacus L. grain.

    PubMed

    Soriano-Santos, J; Escalona-Buendía, H

    2015-04-01

    Even though some research has been carried out on surfactant properties of amaranth protein hydrolysates, their bio-functionality has not been studied yet. In this work amaranth grain Alb 1 and Glob were hydrolyzed (Alb 1H, Glob H) and foams and emulsions at optimal conditions (t, E/S, pH5) were prepared in order to assess techno-functional properties such as foaming (F) and emulsifying (E) (capacity (C) and stability (S)). FC and EC were much better for Glob H than for Alb H. Angiotensin I-converting enzyme-inhibitory activity was higher for Alb 1H (roughly 50 %) than that of Glob H (roughly 30 %). Scavenging of radicals activity (DPPH· or ABTS· (+) ) of Alb 1H and Glob H, at 2 mg/mL, was similar (approx. 40 %), but lower than Alb 1 (approx. 70 %), which was the best antioxidant. The low reducing power showed that hydrolysates barely donate an electron or hydrogen. Chelating activity on Cu(2+) was lower than that exhibited by Fe(2+,) which was remarkable, approx. 80 % as long as DH% > 10 %, where hydrolysates displayed high solubility (Alb 1H = 85 %, Glob H = 70 %) because of occurrence of 1-10 kDa peptides. Amaranth foams and emulsions prepared with protein hydrolysates have a potential as a nutraceutical food. PMID:25829587

  19. Unidirectional transfer in vivo of high-density lipoprotein cholesteryl esters to lower-density lipoproteins in the pig, an animal species without plasma cholesteryl ester transfer activity.

    PubMed

    Terpstra, A H; Stucchi, A F; Foxall, T L; Shwaery, G T; Vespa, D B; Nicolosi, R J

    1993-12-01

    The metabolism of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesteryl esters (CE) was studied in the pig, an animal species without plasma cholesteryl ester transfer activity (CETA). In the first series of experiments, LDL and HDL from normocholesterolemic pigs were radiolabeled with cholesteryl (1-14C)oleate and intravenously administered to two groups of four normocholesterolemic pigs. Radioactive tracer in LDL remained associated with the LDL fraction, and there was no transfer of LDL-CE to HDL. The transport rate (which represents the production and disposal rate) of LDL-CE in normocholesterolemic pigs was 39 mumol CE/h/L. However, radiolabeled HDL-CE were transferred to LDL (25%), and 36% of the LDL-CE mass was derived from the HDL. The transport rate of HDL-CE was 54 mumol CE/h/L, and the flux of HDL-CE to LDL was 14 mumol CE/h/L. There was no accumulation of radiolabeled HDL-CE in very-low-density lipoprotein (VLDL), which suggests that there was no transfer to VLDL. However, this does not rule out the possibility that either the very low levels of VLDL-CE (< 0.09 mmol/L) or the rapid turnover rate of the VLDL pool might have prevented the accumulation of substantial amounts of tracer in VLDL. Therefore, in a second set of experiments, the kinetics of HDL-CE were studied in high-fat-and high-cholesterol-fed pigs with elevated VLDL-CE concentrations (1.92 mmol/L). Hypercholesterolemia was associated with increased transport rates of LDL-CE (165 mumol/h/L) and HDL-CE (78 mumol/h/L) and with an increased flux of HDL-CE to LDL (78 mumol/h/L).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8246765

  20. Tuning sensitivity of CAR to EGFR density limits recognition of normal tissue while maintaining potent anti-tumor activity

    PubMed Central

    Caruso, Hillary G.; Hurton, Lenka V.; Najjar, Amer; Rushworth, David; Ang, Sonny; Olivares, Simon; Mi, Tiejuan; Switzer, Kirsten; Singh, Harjeet; Huls, Helen; Lee, Dean A.; Heimberger, Amy B.; Champlin, Richard E.; Cooper, Laurence J. N.

    2015-01-01

    Many tumors over express tumor-associated antigens relative to normal tissue, such as epidermal growth factor receptor (EGFR). This limits targeting by human T cells modified to express chimeric antigen receptors (CARs) due to potential for deleterious recognition of normal cells. We sought to generate CAR+ T cells capable of distinguishing malignant from normal cells based on the disparate density of EGFR expression by generating two CARs from monoclonal antibodies which differ in affinity. T cells with low affinity Nimo-CAR selectively targeted cells over-expressing EGFR, but exhibited diminished effector function as the density of EGFR decreased. In contrast, the activation of T cells bearing high affinity Cetux-CAR was not impacted by the density of EGFR. In summary, we describe the generation of CARs able to tune T-cell activity to the level of EGFR expression in which a CAR with reduced affinity enabled T cells to distinguish malignant from non-malignant cells. PMID:26330164

  1. Beyond Density: An Inquiry-Based Activity Involving Students Searching for Relationships.

    ERIC Educational Resources Information Center

    DeMeo, Stephen

    2001-01-01

    Explains the limitations of a traditional density experiment and presents an inquiry-based laboratory experiment which allows students to develop an understanding on the relationship between the object's properties and the volume of water the object displaces. (YDS)

  2. Bone Mineral Density Changes after Physical Training and Calcium Intake in Students with Attention Deficit and Hyper Activity Disorders

    ERIC Educational Resources Information Center

    Arab ameri, Elahe; Dehkhoda, Mohammad Reza; Hemayattalab, Rasool

    2012-01-01

    In this study we investigate the effects of weight bearing exercise and calcium intake on bone mineral density (BMD) of students with attention deficit and hyper activity (ADHD) disorder. For this reason 54 male students with ADHD (age 8-12 years old) were assigned to four groups with no differences in age, BMD, calcium intake, and physical…

  3. EFFECT OF AN ACTIVATED SLUDGE WASTEWATER TREATMENT PLANT ON AMBIENT AIR DENSITIES OF AEROSOLS CONTAINING BACTERIA AND VIRUSES

    EPA Science Inventory

    Bacteria and virus-containing aerosols were studied during late summer and fall in a U.S. midwestern suburb before and during the start up and operation of an unenclosed activated sludge wastewater treatment plant. The air in this suburban area contained low-level densities of in...

  4. ERK1/2 Activation Is Necessary for BDNF to Increase Dendritic Spine Density in Hippocampal CA1 Pyramidal Neurons

    ERIC Educational Resources Information Center

    Alonso, Mariana; Medina, Jorge H.; Pozzo-Miller, Lucas

    2004-01-01

    Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling…

  5. Endothelial NOS-dependent activation of c-Jun NH(2)- terminal kinase by oxidized low-density lipoprotein

    NASA Technical Reports Server (NTRS)

    Go, Y. M.; Levonen, A. L.; Moellering, D.; Ramachandran, A.; Patel, R. P.; Jo, H.; Darley-Usmar, V. M.

    2001-01-01

    Oxidized low-density lipoprotein (oxLDL) is known to activate a number of signal transduction pathways in endothelial cells. Among these are the c-Jun NH(2)-terminal kinase (JNK), also known as stress-activated protein kinase, and extracellular signal-regulated kinase (ERK). These mitogen-activated protein kinases (MAP kinase) determine cell survival in response to environmental stress. Interestingly, JNK signaling involves redox-sensitive mechanisms and is activated by reactive oxygen and nitrogen species derived from both NADPH oxidases, nitric oxide synthases (NOS), peroxides, and oxidized low-density lipoprotein (oxLDL). The role of endothelial NOS (eNOS) in the activation of JNK in response to oxLDL has not been examined. Herein, we show that on exposure of endothelial cells to oxLDL, both ERK and JNK are activated through independent signal transduction pathways. A key role of eNOS activation through a phosphatidylinositol-3-kinase-dependent mechanism leading to phosphorylation of eNOS is demonstrated for oxLDL-dependent activation of JNK. Moreover, we show that activation of ERK by oxLDL is critical in protection against the cytotoxicity of oxLDL.

  6. Assessment of Toxicity, Antifeedant Activity, and Biochemical Responses in Stored-Grain Insects Exposed to Lethal and Sublethal Doses of Gaultheria procumbens L. Essential Oil.

    PubMed

    Kiran, S; Prakash, Bhanu

    2015-12-01

    The present study was undertaken to investigate the insecticidal activity of chemically characterized Gaultheria procumbens essential oil (EO) and its mode of action against the Coleopteran insects Sitophilus oryzae and Rhyzopertha dominica. Gas chromatography-mass spectrometry results depicted methyl salicylate (MS) as the major compound (96.61%) of EO. EO and its major compound methyl salicylate (MS) showed 100% mortality at 150 and 5.0 μL/L air against S. oryzae and R. dominica, respectively, on 24 h of exposure. The in vivo percent inhibition of AChE activity ranged between 6.12 and 27.50%. In addition, changes in the antioxidative defense system, superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and oxidized glutathione (GSSG), in test insects were estimated. A significant dose-dependent response in all test parameters was observed. The results demonstrated that G. procumbens EO could play a significant role in the formulation of EO-based insecticides for the management of stored-grain insects. PMID:26558484

  7. A Quantitative Study on Packing Density and Pozzolanic Activity of Cementitious Materials Based on the Compaction Packing Model

    NASA Astrophysics Data System (ADS)

    Gong, Jianqing; Chou, Kai; Huang, Zheng Yu; Zhao, Minghua

    2014-08-01

    A brief introduction to the theoretical basis of compaction packing model (CPM) and an over-view of the principle of the specific strength method provided the starting point of this study. Then, research on quantitative relations was carried out to find the correlation between the contribution rate of the pozzolanic activity and the contribution value of packing density when CPM was applied to fine powder mixture systems. The concept of the contribution value of the packing density being in direct correspondence with the contribution rate was proved by the compressive strength results and SEM images. The results indicated that the variation rule of the contribution rate of the pozzolanic activity is similar to that of the contribution value of packing density as calculated by CPM. This means the contribution value of the packing density could approximately simulate the change tendency of the contribution rate of the pozzolanic activity, which is of significant value for the future of mix designs for high and ultra-high performance concrete.

  8. Pore size analysis of activated carbons from argon and nitrogen porosimetry using density functional theory

    SciTech Connect

    Dombrowski, R.J.; Hyduke, D.R.; Lastoskie, C.M.

    2000-05-30

    The authors present isotherms calculated from density functional theory for the adsorption of argon in model slit-shaped carbon pores at 77 K. The model isotherms are used to interpret experimental argon uptake measurements and to obtain the pore size distributions of several porous carbons. A similar set of density measurements and to obtain the pore size distributions of several porous carbons. A similar set of density functional theory isotherms, previously reported for nitrogen adsorption on carbon slit pores at 77 K, are used to determine pore size distributions for the same set of carbons. The pore size distribution maxima, mean pore widths, and specific pore volumes measured using the two different probe gases are all found to agree to within approximately 8% on average. Some of the differences in the pore size distributions obtained from argon and nitrogen porosimetry may be attributable to quadrupolar interactions of the nitrogen molecules with functional groups on the carbon surface.

  9. Muscle activity, cross-sectional area, and density following passive standing and whole body vibration: A case series

    PubMed Central

    Masani, Kei; Alizadeh-Meghrazi, Milad; Sayenko, Dimitry G.; Zariffa, Jose; Moore, Cameron; Giangregorio, Lora; Popovic, Milos R.; Catharine Craven, B.

    2014-01-01

    Objective To investigate the effects of intermittent passive standing (PS) and whole body vibration (WBV) on the electromyography (EMG) activity, cross-sectional area, and density of lower extremity muscles in individuals with chronic motor complete spinal cord injury (SCI). Design Case series. Methods Seven adult men with chronic (≥2 years), thoracic motor complete (AIS A–B) SCI completed a 40-week course of thrice-weekly intermittent PS-WBV therapy, in a flexed knee posture (160°), for 45 minutes per session at a frequency of 45 Hz and 0.6–0.7 mm displacement using the WAVE® Pro Plate, with an integrated EasyStand™ standing frame. EMG was measured in major lower extremity muscles to represent muscle activity during PS-WBV. The cross-sectional area and density of the calf muscles were measured using peripheral quantitative computed tomography at the widest calf cross-section (66% of the tibia length) at pre- and post-intervention. All measured variables were compared between the pre- and post-intervention measurements to assess change after the PS-WBV intervention. Results PS-WBV acutely induced EMG activity in lower extremity muscles of SCI subjects. No significant changes in lower extremity EMG activity, muscle cross-sectional area, or density were observed following the 40-week intervention. Conclusions Although acute exposure to PS-WBV can induce electrophysiological activity of lower extremity muscles during PS in men with motor complete SCI, the PS-WBV intervention for 40 weeks was not sufficient to result in enhanced muscle activity, or to increase calf muscle cross-sectional area or density. PMID:25059652

  10. THE EFFECTS OF GRAIN SIZE AND GRAIN GROWTH ON THE CHEMICAL EVOLUTION OF COLD DENSE CLOUDS

    SciTech Connect

    Acharyya, Kinsuk; Hassel, George E.; Herbst, Eric

    2011-05-10

    We investigate the formation of molecules during the chemical evolution of a cold dense interstellar cloud using a gas-grain numerical code in order to study the effects of grain-size distribution and grain growth on molecular abundances. Three initial size distributions have been used, based on earlier models. To incorporate different granular sizes, we divided the distribution of sizes utilized into five logarithmically equally spaced ranges, integrated over each range to find its total granular number density, and assigned that number density to an average size in that range. We utilized rate coefficients for surface reactions, accretion, and desorption as functions of grain size. We then followed the chemical evolution of the surface populations of the five average-sized grains along with the gas-phase chemistry. We find that the total effective granular surface area of a distribution is an important parameter in the determination of surface abundances, with and without grain growth. The effect on gas-phase abundances can also be sizable. Grain growth with time increases the rate of depletion of molecules, such as CO, produced in the gas phase. Use of a size distribution for grains in gas-grain models does not improve the agreement of calculated and observed abundances, in the gas or on grains, as compared with models containing 'classical' grains of a fixed radius of 0.1 {mu}m. This result helps to verify the quality of the classical grain approximation for cold cloud models. Further, it provides an important basis for future gas-grain models.

  11. 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…

  12. Grain structure and composition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chapter 4 covers general information about structure and composition of cereal grains as well as the unique features of each cereal grain. Cereal grains are the fruits of cultivated grasses and members of Gramineae family. The fruit of a cereal is botanically known as caryopsis, featured by fusion...

  13. Effects of forage particle size and grain fermentability in midlactation cows. II. Ruminal pH and chewing activity.

    PubMed

    Krause, K M; Combs, D K; Beauchemin, K A

    2002-08-01

    Our study investigated the effects of, and interactions between, level of dietary ruminally fermentable carbohydrate (RFC) and forage particle size on rumen pH and chewing activity for dairy cows fed one level of dietary NDF. Also, correlations between intake, production, chewing, and ruminal pH parameters were investigated. Eight cows (61 days in milk) were assigned to four treatments in a double 4 x 4 Latin square. Treatments were arranged in a 2 x 2 factorial design; finely chopped alfalfa silage (FS) and coarse alfalfa silage (CS) were combined with concentrates based on either dry, cracked-shelled corn (DC; low RFC) or ground, high-moisture corn (HMC; high RFC). Diets were fed ad libitum as a total mixed rations with a concentrate:forage ratio of 60:40. Diets averaged 18.7% crude protein, 24.0% neutral detergent fiber, 18.3% , acid detergent fiber and 27.4% starch on a DM basis. Mean particle size of the four diets were 6.3, 2.8, 6.0, and 3.0 mm for DCCS, DCFS, HMCCS, and HMCFS, respectively. Decreasing forage particle size decreased ruminal pH from 6.02 to 5.81, and increasing level of RFC decreased pH from 5.99 to 5.85. Minimum daily ruminal pH decreased from 5.66 to 5.47 when level of RFC was increased, and decreased from 5.65 to 5.48 when forage particle size decreased. Time below pH 5.8 per day increased from 7.4 h to 10.8 h when level of RFC increased, and increased from 6.4 h to 11.8 h when forage particle size was decreased. Area below 5.8 showed the same relationship with RFC and forage particle size. Also, forage particle size affected the postprandial pH pattern. Cows spent more time eating when fed CS compared with FS (274 vs. 237 min/d), and time spent eating decreased when level of RFC was increased (271 vs. 241 min/d). Decreasing forage particle size decreased time spent ruminating (485 vs. 320 min/d), rumination periods (15.3 vs. 11.7), and duration of rumination periods (29 vs. 26 min). Increasing level of RFC increased time spent ruminating

  14. Effects of grain source and marginal change in lucerne hay particle size on feed sorting, eating behaviour, chewing activity, and milk production in mid-lactation Holstein dairy cows.

    PubMed

    Nasrollahi, S M; Ghorbani, G R; Khorvash, M; Yang, W Z

    2014-12-01

    This study investigated the effects of grain source and lucerne hay (LH) particle length on eating behaviour, chewing activity, and milk production of lactating dairy cows. Eight Holstein dairy cows (175 ± 21 days in milk) were used in a replicated 4 × 4 Latin square design with four 21-days periods. The experiment was a 2 × 2 factorial arrangement of treatments with barley grain alone or equal blend of barley and maize grains combined with short (15 mm) and long (30 mm) LH. Diets were fed ad libitum as total mixed ration with a concentrate to forage ratio of 60:40. Interactions between grain source and LH particle length on feed particle distributions, sorting index, chewing activity, and milk production were minimal. Partially replacing barley grain with maize in the diet overall did not change diurnal distributions of particles retained on the sieves of Penn State Particle Separator but reduced the proportion of particles on 1.18-sieve and increased that of particles on pan (p < 0.05). Grain source did not affect sorting index and chewing activity. However, feeding long LH increased (p < 0.01) intakes of long particles retained on 19- and 8-mm of sieve, prolonged (p < 0.05) eating time, and lowered eating rate (p < 0.05). Interestingly, cows fed with long LH ate more coarse particle during critical-early time post feeding (i. e. 1.5 h), where eating time increased and eating rate decreased (p < 0.05). Increasing particle length of dietary LH tended to increase milk fat-to-protein ratio (p = 0.08). The results suggested that the increased eating time and decreased eating rate as a result of marginally increasing LH particle length would be beneficial to alleviate reduction of ruminal pH and milk fat percentage following the ingestion of highly fermentable diets. PMID:24661569

  15. The role of a-axis grains in the transition to the normal state of YBa{sub 2}Cu{sub 3}O{sub 7−δ} films and of 2G-coated conductors when induced by high electrical current densities

    SciTech Connect

    Bernstein, P. Harnois, C.; Mc Loughlin, C.; Noudem, J.; Thimont, Y.; Ferro, G.; Osorio, M. R.; Veira, J. A.; Vidal, D.; Vidal, F.

    2014-02-07

    The influence of surface defects, in particular of a-axis grains, on the transition to the normal state induced by high current densities in YBa{sub 2}Cu{sub 3}O{sub 7−δ} (YBCO) thin films and in a commercial 2G-coated conductor is investigated. For that purpose, the surface of the samples is observed by scanning electron microscopy and isothermal current-voltage curves are measured at different temperatures with pulsed currents up to the quenching value I*. The results show that the ratio of I* to the critical current is large if a-axis grains are not visible at the surface of the YBCO films, while it is much lower if the surface includes a-axis grains as this is the case for the coated conductor. The connection between the transition onset and the vortex dynamics, as well as the role of the a-axis grains in this process are discussed. The relation between the I* values obtained from thermal calculations and those resulting from vortex dynamics considerations is also discussed, as well as the possible consequences suggested by this work for the different applications of the coated conductors.

  16. Effect of an activated sludge wastewater treatment plant on ambient air densities of aerosols containing bacteria and viruses.

    PubMed

    Fannin, K F; Vana, S C; Jakubowski, W

    1985-05-01

    Bacteria- and virus-containing aerosols were studied during the late summer and fall seasons in a midwestern suburb of the United States before and during the start-up and operation of an unenclosed activated sludge wastewater treatment plant. The study showed that the air in this suburban area contained low-level densities of indicator microorganisms. After the plant began operating, the densities of total aerobic bacteria-containing particles, standard plate count bacteria, total coliforms, fecal coliforms, fecal streptococci, and coliphages increased significantly in the air within the perimeter of the plant. Before plant operations, bacteria were detected from five genera, Klebsiella, Enterobacter, Serratia, Salmonella, and Aeromonas. During plant operations, the number of genera identified increased to 11. In addition to those genera found before plant operations, Escherichia, Providencia, Citrobacter, Acinetobacter, Pasteurella, and Proteus, were also identified. Enteric viruses were detected in low densities from the air emissions of this plant. Only standard plate count bacteria remained at significantly higher than base-line densities beyond 250 m downwind from the center of the aeration tanks. Fecal streptococci and coliphages appeared to be more stable in aerosols than the other indicator microorganisms studied. In general, the densities of microorganism-containing aerosols were higher at night than during the day. The techniques used in this study may be employed to establish microorganism-containing aerosol exposure during epidemiological investigations. PMID:2988442

  17. Effects of watershed densities of animal feeding operations on nutrient concentrations and estrogenic activity in agricultural streams.

    PubMed

    Ciparis, Serena; Iwanowicz, Luke R; Voshell, J Reese

    2012-01-01

    Application of manures from animal feeding operations (AFOs) as fertilizer on agricultural land can introduce nutrients and hormones (e.g. estrogens) to streams. A landscape-scale study was conducted in the Shenandoah River watershed (Virginia, USA) in order to assess the relationship between densities of AFOs in watersheds of agricultural streams and in-stream nutrient concentrations and estrogenic activity. The effect of wastewater treatment plants (WWTPs) on nutrients and estrogenic activity was also evaluated. During periods of high and low flow, dissolved inorganic nitrogen (DIN) and orthophosphate (PO(4)-P) concentrations were analyzed and estrogens/estrogenic compounds were extracted and quantified as17β-estradiol equivalents (E2Eq) using a bioluminescent yeast estrogen screen. Estrogenic activity was measurable in the majority of collected samples, and 20% had E2Eq concentrations >1 ng/L. Relatively high concentrations of DIN (>1000 μg/L) were also frequently detected. During all sampling periods, there were strong relationships between watershed densities of AFOs and in-stream concentrations of DIN (R(2) = 0.56-0.81) and E2Eq (R(2) = 0.39-0.75). Relationships between watershed densities of AFOs and PO(4)-P were weaker, but were also significant (R(2) = 0.27-0.57). When combined with the effect of watershed AFO density, streams receiving WWTP effluent had higher concentrations of PO(4)-P than streams without WWTP discharges, and PO(4)-P was the only analyte with a consistent relationship to WWTPs. The results of this study suggest that as the watershed density of AFOs increases, there is a proportional increase in the potential for nonpoint source pollution of agricultural streams and their receiving waters by nutrients, particularly DIN, and compounds that can cause endocrine disruption in aquatic organisms. PMID:22088420

  18. Effects of watershed densities of animal feeding operations on nutrient concentrations and estrogenic activity in agricultural streams

    USGS Publications Warehouse

    Ciparis, S.; Iwanowicz, L.R.; Voshell, J.R.

    2012-01-01

    Application of manures from animal feeding operations (AFOs) as fertilizer on agricultural land can introduce nutrients and hormones (e.g. estrogens) to streams. A landscape-scale study was conducted in the Shenandoah River watershed (Virginia, USA) in order to assess the relationship between densities of AFOs in watersheds of agricultural streams and in-stream nutrient concentrations and estrogenic activity. The effect of wastewater treatment plants (WWTPs) on nutrients and estrogenic activity was also evaluated. During periods of high and low flow, dissolved inorganic nitrogen (DIN) and orthophosphate (PO 4-P) concentrations were analyzed and estrogens/estrogenic compounds were extracted and quantified as17??-estradiol equivalents (E2Eq) using a bioluminescent yeast estrogen screen. Estrogenic activity was measurable in the majority of collected samples, and 20% had E2Eq concentrations >1ng/L. Relatively high concentrations of DIN (>1000??g/L) were also frequently detected. During all sampling periods, there were strong relationships between watershed densities of AFOs and in-stream concentrations of DIN (R 2=0.56-0.81) and E2Eq (R 2=0.39-0.75). Relationships between watershed densities of AFOs and PO 4-P were weaker, but were also significant (R 2=0.27-0.57). When combined with the effect of watershed AFO density, streams receiving WWTP effluent had higher concentrations of PO 4-P than streams without WWTP discharges, and PO 4-P was the only analyte with a consistent relationship to WWTPs. The results of this study suggest that as the watershed density of AFOs increases, there is a proportional increase in the potential for nonpoint source pollution of agricultural streams and their receiving waters by nutrients, particularly DIN, and compounds that can cause endocrine disruption in aquatic organisms. ?? 2011 Elsevier B.V.

  19. Effects of watershed densities of animal feeding operations on nutrient concentrations and estrogenic activity in agricultural streams

    USGS Publications Warehouse

    Ciparis, Serena; Iwanowicz, Luke R.; Voshell, J. Reese

    2012-01-01

    Application of manures from animal feeding operations (AFOs) as fertilizer on agricultural land can introduce nutrients and hormones (e.g. estrogens) to streams. A landscape-scale study was conducted in the Shenandoah River watershed (Virginia, USA) in order to assess the relationship between densities of AFOs in watersheds of agricultural streams and in-stream nutrient concentrations and estrogenic activity. The effect of wastewater treatment plants (WWTPs) on nutrients and estrogenic activity was also evaluated. During periods of high and low flow, dissolved inorganic nitrogen (DIN) and orthophosphate (PO4-P) concentrations were analyzed and estrogens/estrogenic compounds were extracted and quantified as17β-estradiol equivalents (E2Eq) using a bioluminescent yeast estrogen screen. Estrogenic activity was measurable in the majority of collected samples, and 20% had E2Eq concentrations > 1 ng/L. Relatively high concentrations of DIN (> 1000 μg/L) were also frequently detected. During all sampling periods, there were strong relationships between watershed densities of AFOs and in-stream concentrations of DIN (R2 = 0.56–0.81) and E2Eq (R2 = 0.39–0.75). Relationships between watershed densities of AFOs and PO4-P were weaker, but were also significant (R2 = 0.27–0.57). When combined with the effect of watershed AFO density, streams receiving WWTP effluent had higher concentrations of PO4-P than streams without WWTP discharges, and PO4-P was the only analyte with a consistent relationship to WWTPs. The results of this study suggest that as the watershed density of AFOs increases, there is a proportional increase in the potential for nonpoint source pollution of agricultural streams and their receiving waters by nutrients, particularly DIN, and compounds that can cause endocrine disruption in aquatic organisms.

  20. Fine-grained clay fraction (,0.2 {mu}m): An interesting tool to approach the present thermal and permeability state in active geothermal systems

    SciTech Connect

    Patrier, P.; Papapanagiotou, P.; Beaufort, D.; Traineau, H.; Bril, H.

    1992-01-01

    We have investigated by X-ray diffraction the very fine grained secondary minerals (< 0.2 {micro}m) developed in geothermal systems, in relation with their present thermal and permeability state. Because the smallest particles are the most reactive part of a rock, they are the youngest mineral phases of the geothermal fields. This study has been performed on two active geothermal fields: Milos field, Greece (130 < T < 320 C) and Chipilapa field, Salvador (90 < T < 215 C). In the Milos field, the mineralogical composition of the < 0.2 {micro}m clay fraction observed in the reservoir strongly differs from the overlying altered metamorphic schists in the presence of abundant quantities of saponite and talc/saponite interstratified minerals at unusually high temperature. These phases are considered to be kinetically control-led ''metastable'' minerals which rapidly evolve towards actinolite and talc for present temperatures higher than 300 C. Their occurrence is a good indicator of discharge in highly permeable zones. In the geothermal field of Chipilapa, the mineralogical composition of the < 0.2 {micro}m clay fractions fairly agrees with the temperatures presently measured in the wells, whereas several discrepancies may be pointed out from the compositions of coarser clay fractions (< 5 {micro}m) which contain minerals inherited from higher temperature stages. Permeable zones may be evidenced from an increase of expandable components in the interstratified minerals and a decrease of the coherent domain of the unexpandable clay particles (chlorite).

  1. 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

  2. Redox-Active Molecular Nanowire Flash Memory for High-Endurance and High-Density Nonvolatile Memory Applications.

    PubMed

    Zhu, Hao; Pookpanratana, Sujitra J; Bonevich, John E; Natoli, Sean N; Hacker, Christina A; Ren, Tong; Suehle, John S; Richter, Curt A; Li, Qiliang

    2015-12-16

    In this work, high-performance top-gated nanowire molecular flash memory has been fabricated with redox-active molecules. Different molecules with one and two redox centers have been tested. The flash memory has clean solid/molecule and dielectric interfaces, due to the pristine molecular self-assembly and the nanowire device self-alignment fabrication process. The memory cells exhibit discrete charged states at small gate voltages. Such multi-bit memory in one cell is favorable for high-density storage. These memory devices exhibit fast speed, low power, long memory retention, and exceptionally good endurance (>10(9) cycles). The excellent characteristics are derived from the intrinsic charge-storage properties of the protected redox-active molecules. Such multi-bit molecular flash memory is very attractive for high-endurance and high-density on-chip memory applications in future portable electronics. PMID:26600234

  3. Activated carbons derived from coconut shells as high energy density cathode material for Li-ion capacitors.

    PubMed

    Jain, Akshay; Aravindan, Vanchiappan; Jayaraman, Sundaramurthy; Kumar, Palaniswamy Suresh; Balasubramanian, Rajasekhar; Ramakrishna, Seeram; Madhavi, Srinivasan; Srinivasan, M P

    2013-01-01

    In this manuscript, a dramatic increase in the energy density of ~ 69 Wh kg⁻¹ and an extraordinary cycleability ~ 2000 cycles of the Li-ion hybrid electrochemical capacitors (Li-HEC) is achieved by employing tailored activated carbon (AC) of ~ 60% mesoporosity derived from coconut shells (CS). The AC is obtained by both physical and chemical hydrothermal carbonization activation process, and compared to the commercial AC powders (CAC) in terms of the supercapacitance performance in single electrode configuration vs. Li. The Li-HEC is fabricated with commercially available Li₄Ti₅O₁₂ anode and the coconut shell derived AC as cathode in non-aqueous medium. The present research provides a new routine for the development of high energy density Li-HEC that employs a mesoporous carbonaceous electrode derived from bio-mass precursors. PMID:24141527

  4. Activated carbons derived from coconut shells as high energy density cathode material for Li-ion capacitors

    PubMed Central

    Jain, Akshay; Aravindan, Vanchiappan; Jayaraman, Sundaramurthy; Kumar, Palaniswamy Suresh; Balasubramanian, Rajasekhar; Ramakrishna, Seeram; Madhavi, Srinivasan; Srinivasan, M. P.

    2013-01-01

    In this manuscript, a dramatic increase in the energy density of ~ 69 Wh kg−1 and an extraordinary cycleability ~ 2000 cycles of the Li-ion hybrid electrochemical capacitors (Li-HEC) is achieved by employing tailored activated carbon (AC) of ~ 60% mesoporosity derived from coconut shells (CS). The AC is obtained by both physical and chemical hydrothermal carbonization activation process, and compared to the commercial AC powders (CAC) in terms of the supercapacitance performance in single electrode configuration vs. Li. The Li-HEC is fabricated with commercially available Li4Ti5O12 anode and the coconut shell derived AC as cathode in non-aqueous medium. The present research provides a new routine for the development of high energy density Li-HEC that employs a mesoporous carbonaceous electrode derived from bio-mass precursors. PMID:24141527

  5. Activated carbons derived from coconut shells as high energy density cathode material for Li-ion capacitors

    NASA Astrophysics Data System (ADS)

    Jain, Akshay; Aravindan, Vanchiappan; Jayaraman, Sundaramurthy; Kumar, Palaniswamy Suresh; Balasubramanian, Rajasekhar; Ramakrishna, Seeram; Madhavi, Srinivasan; Srinivasan, M. P.

    2013-10-01

    In this manuscript, a dramatic increase in the energy density of ~ 69 Wh kg-1 and an extraordinary cycleability ~ 2000 cycles of the Li-ion hybrid electrochemical capacitors (Li-HEC) is achieved by employing tailored activated carbon (AC) of ~ 60% mesoporosity derived from coconut shells (CS). The AC is obtained by both physical and chemical hydrothermal carbonization activation process, and compared to the commercial AC powders (CAC) in terms of the supercapacitance performance in single electrode configuration vs. Li. The Li-HEC is fabricated with commercially available Li4Ti5O12 anode and the coconut shell derived AC as cathode in non-aqueous medium. The present research provides a new routine for the development of high energy density Li-HEC that employs a mesoporous carbonaceous electrode derived from bio-mass precursors.

  6. Density Functional Study of the Structure, Stability and Oxygen Reduction Activity of Ultrathin Platinum Nanowires

    SciTech Connect

    Matanovic, Ivana; Kent, Paul; Garzon, Fernando; Henson, Neil J.

    2013-03-14

    We used density functional theory to study the difference in the structure, stability and catalytic reactivity between ultrathin, 0.5–1.0 nm diameter, platinum nanotubes and nanowires. Model nanowires were formed by inserting an inner chain of platinum atoms in small diameter nanotubes. In this way more stable, non-hollow structures were formed. The difference in the electronic structure of platinum nanotubes and nanowires was examined by inspecting the density of surface states and band structure. Furthermore, reactivity toward the oxygen reduction reaction of platinum nanowires was assessed by studying the change in the chemisorption energies of oxygen, hydroxyl, and hydroperoxyl groups, induced by converting the nanotube models to nanowires. Both ultrathin platinum nanotubes and nanowires show distinct properties compared to bulk platinum. Single-wall nanotubes and platinum nanowires with diameters larger than 1 nm show promise for use as oxygen reduction catalysts.

  7. Thermally activated flux creep and critical current densities in high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Matsushita, Teruo

    The effect of flux creep is discussed for projected strongly pinned oxide superconductors. It is determined, that if a superconducting wire with a critical current density higher than 10-billion A/sq m at 77 K and 5 T can be produced, the wire will be able to be applied to equipment at high fields; nonzero critical density will be obtained even at 77 K and high fields. The decay of persistent current is expected to be noticeable even in such strongly pinned superconductors, when those are used at 77 K. Although this will be managed in power equipment by lowering the operating current; variation in the magnetic field due to the variation in the current distribution inside superconducting wires appears to be unavoidable. It is suggested that an effort should be made to reduce the variation by reducing the diameter of the superconducting filaments.

  8. Abnormal grain growth in TD-nickel.

    NASA Technical Reports Server (NTRS)

    Petrovic, J. J.; Ebert, L. J.

    1972-01-01

    Characteristics of the coarse grain transformation occurring in TD-nickel 1 in. bar under certain conditions of deformation and annealing were examined. The transformation exhibits Avrami-type kinetics, with an activation energy of 250 kcal per mole. Characteristics of untransformed regions are like those of the as-received state. The transformed grain size increases with increasing deformation and decreasing annealing temperature. The coarse grain transformation is significantly different from primary recrystallization in pure nickel. Its characteristics cannot be rationalized in terms of primary recrystallization concepts, but may be explained in terms of an abnormal grain growth description. The coarse grain transformation in TD-nickel is abnormal grain growth rather than primary recrystallization. The analysis suggests an explanation for the effect of thermomechanical history on the deformation and annealing behavior of TD-nickel.

  9. Detecting grain rotation at the nanoscale

    PubMed Central

    Chen, Bin; Lutker, Katie; Lei, Jialin; Yan, Jinyuan; Yang, Shizhong; Mao, Ho-kwang

    2014-01-01

    It is well-believed that below a certain particle size, grain boundary-mediated plastic deformation (e.g., grain rotation, grain boundary sliding and diffusion) substitutes for conventional dislocation nucleation and motion as the dominant deformation mechanism. However, in situ probing of grain boundary processes of ultrafine nanocrystals during plastic deformation has not been feasible, precluding the direct exploration of the nanomechanics. Here we present the in situ texturing observation of bulk-sized platinum in a nickel pressure medium of various particle sizes from 500 nm down to 3 nm. Surprisingly, the texture strength of the same-sized platinum drops rapidly with decreasing grain size of the nickel medium, indicating that more active grain rotation occurs in the smaller nickel nanocrystals. Insight into these processes provides a better understanding of the plastic deformation of nanomaterials in a few-nanometer length scale. PMID:24550455

  10. USING A DIFFERENTIAL EMISSION MEASURE AND DENSITY MEASUREMENTS IN AN ACTIVE REGION CORE TO TEST A STEADY HEATING MODEL

    SciTech Connect

    Winebarger, Amy R.; Schmelz, Joan T.; Warren, Harry P.; Saar, Steve H.; Kashyap, Vinay L.

    2011-10-10

    The frequency of heating events in the corona is an important constraint on the coronal heating mechanisms. Observations indicate that the intensities and velocities measured in active region cores are effectively steady, suggesting that heating events occur rapidly enough to keep high-temperature active region loops close to equilibrium. In this paper, we couple observations of active region (AR) 10955 made with the X-Ray Telescope and the EUV Imaging Spectrometer on board Hinode to test a simple steady heating model. First we calculate the differential emission measure (DEM) of the apex region of the loops in the active region core. We find the DEM to be broad and peaked around 3 MK. We then determine the densities in the corresponding footpoint regions. Using potential field extrapolations to approximate the loop lengths and the density-sensitive line ratios to infer the magnitude of the heating, we build a steady heating model for the active region core and find that we can match the general properties of the observed DEM for the temperature range of 6.3 < log T < 6.7. This model, for the first time, accounts for the base pressure, loop length, and distribution of apex temperatures of the core loops. We find that the density-sensitive spectral line intensities and the bulk of the hot emission in the active region core are consistent with steady heating. We also find, however, that the steady heating model cannot address the emission observed at lower temperatures. This emission may be due to foreground or background structures, or may indicate that the heating in the core is more complicated. Different heating scenarios must be tested to determine if they have the same level of agreement.

  11. 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

  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. Noncovalent intermolecular interactions between dehydroepiandrosterone and the active site of human dehydroepiandrosterone sulphotransferase: A density functional theory based treatment

    NASA Astrophysics Data System (ADS)

    Astani, Elahe; Heshmati, Emran; Chen, Chun-Jung; Hadipour, Nasser L.; Shekarsaraei, Setareh

    2016-04-01

    A theoretical study was performed to characterize noncovalent intermolecular interactions, especially hydrogen bond (HB), in the active site of enzyme human dehydroepiandrosterone sulphotransferase (SULT2A1/DHEA) using the local (M06-L) and hybrid (M06, M06-2X) meta-GGA functionals of density functional theory (DFT). Results revealed that DHEA is able to form HBs with residues His99, Tyr231, Met137 and Met16 in the active site of the SULT2A1/DHEA. It was found that DHEA interacts with the other residues through electrostatic and Van der Waals interactions.

  14. 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.

  15. Grain growth of gold nanowires through laser zone annealing and rapid thermal annealing

    NASA Astrophysics Data System (ADS)

    Kim, Jung Yun

    The grain boundary density in metals plays an increasingly important role as structures are shrinking down to dimensions comparable to the electronic mean free path. Metal nanowires prepared through electron beam lithography, electrodeposition and many other methods are nanocrystalline with an average grain diameter in the range of 2--50 nm. For these nanocrystalline metal nanowires with a lateral dimensions larger than the mean grain diameter, the electrical resistance is dominated by electron scattering at the grain boundaries as opposed to the external surfaces and the background. The deleterious effect of grain boundaries on the electrical properties provides strong motivation to develop post-processing methods for increasing the mean grain diameter. Thermal annealing has typically been used to induce grain growth. However, for metal nanowires patterned on a planar surface, a classic Rayleigh instability is observed resulting in decomposition of the nanowire to a periodic series of nanoparticles. In principle, grain growth requires short range motion of atoms while shape change requires mass displacement across large distances. Laser zone annealing was used to test whether the latter could be suppressed by rapidly heating a highly localized section of the wire followed by rapidly cooling. A piezoelectric motor was used to translate the wire at nanoscale steps over a 532 nm confocal laser source at range of power levels (2.5--10 mW) and translation rates (7--128 nm/s). Annealing at a laser power of 10 mW resulted in grain growth of nearly 300% from 27 nm to 85 nm. A second approach to inhibit shape change while allowing for grain growth was to encapsulate the nanowire with an alumina layer to constrict large scale atomic diffusion during isothermal annealing. The alumina coating maintained the shape of the nanowire up to a temperature of ˜669 K and grain growth approaching the limiting size was observed. To study the grain growth kinetics, in situ electrical

  16. Colony density and activity times of the ant Camponotus semitestaceus (hymenoptera: Formicidae) in a shrub steppe community

    SciTech Connect

    Gano, K.A.; Rogers, L.E.

    1983-11-01

    Colony densities and above-ground activity periods were determined for Camponotus semitestaceus colonies within a shrub-steppe community. Colony densities (anti x=/- SD) averaged 0.088 +/- 0.032 per m/sup 2/ and 0.048 +/- 0.028 per m/sup 2/ on two sagebrush-bunchgrass sites and 0.028 +/- 0.028 per m/sup 2/ on a burned site. Seventy-five percent of the nest entrances were located alongside the stems of sagebrush, indicating a preference for these microhabitats as nest locations. Above-ground activity times were determined by using time lapse photography. Activity commenced shortly after sunset, when light intensities dropped to 2.5 to 1.0 foot-candles (ca. 27 to 11 lux) and terminated just before sunrise. Light intensity appears to be the primary cue for controlling above-ground activity periods of this species, but temperature also appears to be an important factor. When soil surface temperatures drop to 1.7 to 3.9/sup 0/C, all above-ground activity ceases, irrespective of light intensity.

  17. Colony density and activity times of the ant Camponotus semitestaceus (hymenoptera:formicidae) in a shrub steppe community

    SciTech Connect

    Gano, K.A.; Rogers, L.E.

    1983-11-01

    Colony densities and above-ground activity periods were determined for Camponotus semitestaceus colonies within a shrub-steppe community. Colony densities (x +/- SD) averaged 0.088 +/- 0.032 per m/sup 2/ and 0.048 +/- 0.028 per m/sup 2/ on two sagebrush-bunchgrass sites and 0.028 +/- 0.028 per m/sup 2/ on a burned site. Seventy-five percent of the nest entrances were located alongside the stems of sagebrush, indicating a preference for these microhabitats as nest locations. Above-ground activity times were determined by using time lapse photography. Activity commenced shortly after sunset, when light intensities dropped to 2.5 to 1.0 foot-candles (ca. 27 to 11 lux) and terminated just before sunrise. Light intensity appears to be the primary cue for controlling above-ground activity periods of this species, but temperature also appears to be an important factor. When soil surface temperatures drop to 1.7 to 3.9/sup 0/C, all above-ground activity ceases, irrespective of light intensity. 19 references, 3 figures, 2 tables.

  18. A Simple Activity to Facilitate Proportional Reasoning in the Contexts of Density, Dissolving, and Nanoparticles

    ERIC Educational Resources Information Center

    Hamed, Kastro

    2008-01-01

    To address the confusion resulting from difficulties with proportional reasoning among preservice physical science students, a cube-assembly activity was used to bring a sense of concreteness to abstract ideas. The activity took students from the concrete step of assembling cubes of various sizes and directly measuring their properties to slightly…

  19. Conformable actively multiplexed high-density surface electrode array for brain interfacing

    DOEpatents

    Rogers, John; Kim, Dae-Hyeong; Litt, Brian; Viventi, Jonathan

    2015-01-13

    Provided are methods and devices for interfacing with brain tissue, specifically for monitoring and/or actuation of spatio-temporal electrical waveforms. The device is conformable having a high electrode density and high spatial and temporal resolution. A conformable substrate supports a conformable electronic circuit and a barrier layer. Electrodes are positioned to provide electrical contact with a brain tissue. A controller monitors or actuates the electrodes, thereby interfacing with the brain tissue. In an aspect, methods are provided to monitor or actuate spatio-temporal electrical waveform over large brain surface areas by any of the devices disclosed herein.

  20. Granular L1{sub 0} FePt-X (X=C, TiO{sub 2}, Ta{sub 2}O{sub 5}) (001) nanocomposite films with small grain size for high density magnetic recording

    SciTech Connect

    Chen, J. S.; Chow, G. M.; Lim, B. C.; Ding, Y. F.; Hu, J. F.; Ju, G.

    2009-04-01

    FePt-X (X=C, TiO{sub 2}, Ta{sub 2}O{sub 5}) nanocomposite films were deposited on MgO/CrRu/glass substrates at 350 deg. C by magnetron cosputtering. The comparison investigations on the magnetic properties and microstructure of FePt-X films with various dopants were conducted. All FePt-X films showed (001) preferred orientation and oxide dopants promoted the formation of magnetically soft fcc FePt phase. With 15 vol % C doping, FePt-C film with columnar grains of 7.5 nm was obtained and the out-of-plane coercivity measured at room temperature was as high as 14.4 kOe. The increase in carbon volume fraction to 20% caused the formation of two-layer structure, whereas for the 20 vol % TiO{sub 2} and Ta{sub 2}O{sub 5} doping, the columnar structure of the FePt films remained and the corresponding grain sizes were 5 and 10 nm, respectively. Ta{sub 2}O{sub 5} doping showed better grain isolation than the others. The out-of-plane coercivities of FePt-TiO{sub 2} and FePt-Ta{sub 2}O{sub 5} films were 7.5 and 8.8 kOe, respectively.

  1. Generalized acoustic energy density based active noise control in single frequency diffuse sound fields.

    PubMed

    Xu, Buye; Sommerfeldt, Scott D

    2014-09-01

    In a diffuse sound field, prior research has established that a secondary source can theoretically achieve perfect cancellation at an error microphone in the far field of the secondary source. However, the sound pressure level is generally only reduced in a small zone around the error sensor, and at a distance half of a wavelength away from the error sensor, the averaged sound pressure level will be increased by more than 10 dB. Recently an acoustic energy quantity, referred to as the generalized acoustic energy density (GED), has been introduced. The GED is obtained by using a weighting factor in the formulation of total acoustic energy density. Different values of the weighting factor can be chosen for different applications. When minimizing the GED at the error sensor, one can adjust the weighting factor to increase the spatial extent of the "quiet zone" and to achieve a desired balance between the degree of attenuation in the quiet zone and the total energy added into the sound field. PMID:25190386

  2. Grain-growth law during Stage 1 sintering of materials

    NASA Astrophysics Data System (ADS)

    He, Zeming; Ma, J.

    2002-09-01

    This work investigates the grain-growth behaviour of powder compact during Stage 1 sintering (<90{%} theoretical density). It is widely accepted that grain size is an important state variable in the constitutive modelling in material sintering. However, it is noted that all the existing grain-growth laws proposed in the literature do not incorporate the effect of externally applied stress independently. In this work, a grain-growth law with externally applied stress as a variable was proposed. Alumina powders were forge-sintered at different applied stresses to examine the proposed grain-growth relationship. The proposed grain-growth law was then applied to model the grain-growth process on the sinter forging of tool steel. It is shown that the present proposed grain-growth law provides a good description on the experimental results.

  3. [Density, size structure and reproductive activity of the pink conch Eustrombus gigas (Mesogastropoda: Strombidae) in Banco Chinchorro, Mexico].

    PubMed

    Cala, Yuself R; Navarrete, Alberto de Jesús; Ocaña, Frank A; Rivera, José Oliva

    2013-12-01

    The pink conch Eustrombus gigas is an important fisheries resource. At the regional level in the Caribbean, over-exploitation and habitat destruction have caused a decrease in the abundance of this resource. In order to provide necessary information for the species management in Mexico, this work aimed to analyze the total density, adult density, size structure and reproductive behavior of pink conch population at Banco Chinchorro during 2009-2010. Data from three seasons were obtained (rainy, dry and cold fronts periods) in three areas: Norte (North), Centro (Center) and Sur (South). The organisms were separated into two groups: (a) the criteria based upon legal harvest in Mexico: legal size conchs (siphonal length > 200 mm) and illegal size conchs (siphonal length < 200 mm), and (b) the criteria based upon sexual maturity using the 15 mm lip thickness standard: lip < 15 mm as juvenile conch and lip > or = 15 mm as adult conch. Copulation, spawning, egg masses and aggregations were evaluated as reproductive evidences. The highest total density was observed during the dry season with 384ind./ha, and the lowest during the rainy season with 127ind./ha. The highest density was reported at Sur (385ind./ha) and the lowest at Norte (198ind./ ha). The highest adult density was observed during the rainy season (8.33ind./ha), and the lowest occurred in the dry season (6.1 ind./ha). Adult density values were 5.55, 7.05 and 8.33ind./ha for Centro, Sur and Norte areas, respectively. Adult densities were lower than the threshold needed for reproduction, and 42% of the population may be vulnerable to fishing, as they had the minimum size for catch (Lsi 200 mm). Furthermore, only 2.2% of the population reached a Gl > 15 mm as sexual maturity indicator. During the study period, only six evidences of reproductive activity were observed. The smaller densities reported at Banco Chinchorro may cause reproduction events to be almost absent which in turn is sufficient evidence to show

  4. TEM Analyses of Itokawa Regolith Grains and Lunar Soil Grains to Directly Determine Space Weathering Rates on Airless Bodies

    NASA Technical Reports Server (NTRS)

    Berger, Eve L.; Keller, Lindsay P.; Christoffersen, Roy

    2016-01-01

    Samples returned from the moon and Asteroid Itokawa by NASA's Apollo Missions and JAXA's Hayabusa Mission, respectively, provide a unique record of their interaction with the space environment. Space weathering effects result from micrometeorite impact activity and interactions with the solar wind. While the effects of solar wind interactions, ion implantation and solar flare particle track accumulation, have been studied extensively, the rate at which these effects accumulate in samples on airless bodies has not been conclusively determined. Results of numerical modeling and experimental simulations do not converge with observations from natural samples. We measured track densities and rim thicknesses of three olivine grains from Itokawa and multiple olivine and anorthite grains from lunar soils of varying exposure ages. Samples were prepared for analysis using a Leica EM UC6 ultramicrotome and an FEI Quanta 3D dual beam focused ion beam scanning electron microscope (FIB-SEM). Transmission electron microscope (TEM) analyses were performed on the JEOL 2500SE 200kV field emission STEM. The solar wind damaged rims on lunar anorthite grains are amorphous, lack inclusions, and are compositionally similar to the host grain. The rim width increases as a smooth function of exposure age until it levels off at approximately 180 nm after approximately 20 My (Fig. 1). While solar wind ion damage can only accumulate while the grain is in a direct line of sight to the Sun, solar flare particles can penetrate to mm-depths. To assess whether the track density accurately predicts surface exposure, we measured the rim width and track density in olivine and anorthite from the surface of rock 64455, which was never buried and has a surface exposure age of 2 My based on isotopic measurements. The rim width from 64455 (60-70nm) plots within error of the well-defined trend for solar wind amorphized rims in Fig. 1. Measured solar flare track densities are accurately reflecting the

  5. Association of differentially expressed genes with activation of mouse hepatic stellate cells by high-density cDNA mircoarray

    PubMed Central

    Liu, Xiao-Jing; Yang, Li; Luo, Feng-Ming; Wu, Hong-Bin; Qu-Qiang

    2004-01-01

    AIM: To characterize the gene expression profiles associated with activation of mouse hepatic stellate cell (HSC) and provide novel insights into the pathogenesis of hepatic fibrosis. METHODS: Mice HSCs were isolated from BALB/c mice by in situ perfusion of collagenase and pronase and single-step density Nycodenz gradient. Total RNA and mRNA of quiescent HSC and culture-activated HSC were extracted, quantified and reversely transcripted into cDNA. cDNAs from activated HSC were labeled with Cy5 and cDNAs from the quiescent HSC were labeled with Cy3, which were mixed with equal quantity, then hybridized with cDNA chips containing 4000 genes. Chips were washed, scanned and analyzed. Increased expression of 4 genes and decreased expression of one gene in activated HSC were confirmed by reverse transcription- polymerase chain reaction (RT-PCR). RESULTS: A total of 835 differentially expressed genes were identified by cDNA chip between activated and quiescent HSC, and 465 genes were highly expressed in activated HSC. The differentially expressed genes included those involved in protein synthesis, cell-cycle regulation, apoptosis, and DNA damage response. CONCLUSION: Many genes implicated in intrahepatic inflammation, fibrosis and proliferation were up-regulated in activated HSC. cDNA microarray is an effective technique in screening for differentially expressed genes between two different situations of the HSC. Further analysis of the obtained genes will help understand the molecular mechanism of activation of HSC and hepatic fibrosis. PMID:15162533

  6. Active mammalian replication origins are associated with a high-density cluster of mCpG dinucleotides.

    PubMed Central

    Rein, T; Zorbas, H; DePamphilis, M L

    1997-01-01

    ori-beta is a well-characterized origin of bidirectional replication (OBR) located approximately 17 kb downstream of the dihydrofolate reductase gene in hamster cell chromosomes. The approximately 2-kb region of ori-beta that exhibits greatest replication initiation activity also contains 12 potential methylation sites in the form of CpG dinucleotides. To ascertain whether DNA methylation might play a role at mammalian replication origins, the methylation status of these sites was examined with bisulfite to chemically distinguish cytosine (C) from 5-methylcytosine (mC). All of the CpGs were methylated, and nine of them were located within 356 bp flanking the minimal OBR, creating a high-density cluster of mCpGs that was approximately 10 times greater than average for human DNA. However, the previously reported densely methylated island in which all cytosines were methylated regardless of their dinucleotide composition was not detected and appeared to be an experimental artifact. A second OBR, located at the 5' end of the RPS14 gene, exhibited a strikingly similar methylation pattern, and the organization of CpG dinucleotides at other mammalian origins revealed the potential for high-density CpG methylation. Moreover, analysis of bromodeoxyuridine-labeled nascent DNA confirmed that active replication origins were methylated. These results suggest that a high-density cluster of mCpG dinucleotides may play a role in either the establishment or the regulation of mammalian replication origins. PMID:8972222

  7. Neighbourhood food and physical activity environments in England, UK: does ethnic density matter?

    PubMed Central

    2012-01-01

    Background In England, obesity is more common in some ethnic minority groups than in Whites. This study examines the relationship between ethnic concentration and access to fast food outlets, supermarkets and physical activity facilities. Methods Data on ethnic concentration, fast food outlets, supermarkets and physical activity facilities were obtained at the lower super output area (LSOA) (population average of 1500). Poisson multilevel modelling was used to examine the association between own ethnic concentration and facilities, adjusted for area deprivation, urbanicity, population size and clustering of LSOAs within local authority areas. Results There was a higher proportion of ethnic minorities residing in areas classified as most deprived. Fast food outlets and supermarkets were more common and outdoor physical activity facilities were less common in most than least deprived areas. A gradient was not observed for the relationship between indoor physical activity facilities and area deprivation quintiles. In contrast to White British, increasing ethnic minority concentration was associated with increasing rates of fast food outlets. Rate ratios comparing rates of fast food outlets in high with those in low level of ethnic concentration ranged between 1.28, 95% confidence interval 1.06-1.55 (Bangladeshi) and 2.62, 1.46-4.70 (Chinese). Similar to White British, however, increasing ethnic minority concentration was associated with increasing rate of supermarkets and indoor physical activity facilities. Outdoor physical activity facilities were less likely to be in high than low ethnic concentration areas for some minority groups. Conclusions Overall, ethnic minority concentration was associated with a mixture of both advantages and disadvantages in the provision of food outlets and physical activity facilities. These issues might contribute to ethnic differences in food choices and engagement in physical activity. PMID:22709527

  8. Large-Scale Variational Two-Electron Reduced-Density-Matrix-Driven Complete Active Space Self-Consistent Field Methods.

    PubMed

    Fosso-Tande, Jacob; Nguyen, Truong-Son; Gidofalvi, Gergely; DePrince, A Eugene

    2016-05-10

    A large-scale implementation of the complete active space self-consistent field (CASSCF) method is presented. The active space is described using the variational two-electron reduced-density-matrix (v2RDM) approach, and the algorithm is applicable to much larger active spaces than can be treated using configuration-interaction-driven methods. Density fitting or Cholesky decomposition approximations to the electron repulsion integral tensor allow for the simultaneous optimization of large numbers of external orbitals. We have tested the implementation by evaluating singlet-triplet energy gaps in the linear polyacene series and two dinitrene biradical compounds. For the acene series, we report computations that involve active spaces consisting of as many as 50 electrons in 50 orbitals and the simultaneous optimization of 1892 orbitals. For the dinitrene compounds, we find that the singlet-triplet gaps obtained from v2RDM-driven CASSCF with partial three-electron N-representability conditions agree with those obtained from configuration-interaction-driven approaches to within one-third of 1 kcal mol(-1). When enforcing only the two-electron N-representability conditions, v2RDM-driven CASSCF yields less accurate singlet-triplet energy gaps in these systems, but the quality of the results is still far superior to those obtained from standard single-reference approaches. PMID:27065086

  9. Cell Density Sensing Alters TGF-β Signaling in a Cell-Type-Specific Manner, Independent from Hippo Pathway Activation

    PubMed Central

    Nallet-Staub, Flore; Yin, Xueqian; Gilbert, Cristèle; Marsaud, Véronique; Ben Mimoun, Saber; Javelaud, Delphine; Leof, Edward B.; Mauviel, Alain

    2015-01-01

    SUMMARY Cell-cell contacts inhibit cell growth and proliferation in part by activating the Hippo pathway that drives the phosphorylation and nuclear exclusion of the transcriptional coactivators YAP and TAZ. Cell density and Hippo signaling have also been reported to block transforming growth factor β (TGF-β) responses, based on the ability of phospho-YAP/TAZ to sequester TGF-β-activated SMAD complexes in the cytoplasm. Herein, we provide evidence that epithelial cell polarization interferes with TGF-β signaling well upstream and independent of cytoplasmic YAP/TAZ. Rather, polarized basolateral presentation of TGF-β receptors I and II deprives apically delivered TGF-β of access to its receptors. Basolateral ligand delivery nonetheless remains entirely effective to induce TGF-β responses. These data demonstrate that cell-type-specific inhibition of TGF-β signaling by cell density is restricted to polarized epithelial cells and reflects the polarized distribution of TGF-β receptors, which thus affects SMAD activation irrespective of Hippo pathway activation. PMID:25758862

  10. Grain boundary diffusion in olivine (Invited)

    NASA Astrophysics Data System (ADS)

    Marquardt, K.; Dohmen, R.

    2013-12-01

    Olivine is the main constituent of Earth's upper mantle. The individual mineral grains are separated by grain boundaries that have very distinct properties compared to those of single crystals and strongly affect large-scale physical and chemical properties of rocks, e.g. viscosity, electrical conductivity and diffusivity. Knowledge on the grain boundary physical and chemical properties, their population and distribution in polycrystalline materials [1] is a prerequisite to understand and model bulk (rock) properties, including their role as pathways for element transport [2] and the potential of grain boundaries as storage sites for incompatible elements [3]. Studies on selected and well characterized single grain boundaries are needed for a detailed understanding of the influence of varying grain boundaries. For instance, the dependence of diffusion on the grain boundary structure (defined by the lattice misfit) and width in silicates is unknown [2, 4], but limited experimental studies in material sciences indicate major effects of grain boundary orientation on diffusion rates. We characterized the effect of grain boundary orientation and temperature on element diffusion in forsterite grain boundaries by transmission electron microscopy (TEM).The site specific TEM-foils were cut using the focused ion beam technique (FIB). To study diffusion we prepared amorphous thin-films of Ni2SiO4 composition perpendicular to the grain boundary using pulsed laser deposition. Annealing (800-1450°C) leads to crystallization of the thin-film and Ni-Mg inter-diffuse into the crystal volume and along the grain boundary. The inter-diffusion profiles were measured using energy dispersive x-ray spectrometry in the TEM, standardized using the Cliff-Lorimer equation and EMPA measurements. We obtain volume diffusion coefficients that are comparable to Ni-Mg inter-diffusion rates in forsterite determined in previous studies at comparable temperatures, with similar activation energies

  11. Oxidized Low-Density Lipoprotein Contributes to Atherogenesis via Co-activation of Macrophages and Mast Cells

    PubMed Central

    Chen, Chong; Khismatullin, Damir B.

    2015-01-01

    Oxidized low-density lipoprotein (OxLDL) is a risk factor for atherosclerosis, due to its role in endothelial dysfunction and foam cell formation. Tissue-resident cells such as macrophages and mast cells release inflammatory mediators upon activation that in turn cause endothelial activation and monocyte adhesion. Two of these mediators are tumor necrosis factor (TNF)-α, produced by macrophages, and histamine, produced by mast cells. Static and microfluidic flow experiments were conducted to determine the number of adherent monocytes on vascular endothelium activated by supernatants of oxLDL-treated macrophages and mast cells or directly by oxLDL. The expression of adhesion molecules on activated endothelial cells and the concentration of TNF-α and histamine in the supernatants were measured by flow cytometry and enzyme-linked immunosorbent assay, respectively. A low dose of oxLDL (8 μg/ml), below the threshold for the clinical presentation of coronary artery disease, was sufficient to activate both macrophages and mast cells and synergistically increase monocyte-endothelium adhesion via released TNF-α and histamine. The direct exposure of endothelial cells to a much higher dose of oxLDL (80 μg/ml) had less effect on monocyte adhesion than the indirect activation via oxLDL-treated macrophages and mast cells. The results of this work indicate that the co-activation of macrophages and mast cells by oxLDL is an important mechanism for the endothelial dysfunction and atherogenesis. The observed synergistic effect suggests that both macrophages and mast cells play a significant role in early stages of atherosclerosis. Allergic patients with a lipid-rich diet may be at high risk for cardiovascular events due to high concentration of low-density lipoprotein and histamine in arterial vessel walls. PMID:25811595

  12. Antioxidative Activity after Rosuvastatin Treatment in Patients with Stable Ischemic Heart Disease and Decreased High Density Lipoprotein Cholesterol

    PubMed Central

    Park, Do-Sim; Park, Hyun Young; Rhee, Sang Jae; Kim, Nam-Ho; Oh, Seok Kyu; Jeong, Jin-Won

    2016-01-01

    Background and Objectives The clinical significance of statin-induced high-density lipoprotein cholesterol (HDL-C) changes is not well known. We investigated whether rosuvastatin-induced HDL-C changes can influence the anti-oxidative action of high-density lipoprotein particle. Subjects and Methods A total of 240 patients with stable ischemic heart disease were studied. Anti-oxidative property was assessed by paraoxonase 1 (PON1) activity. We compared the lipid profile and PON1 activity at baseline and at 8 weeks after rosuvastatin 10 mg treatment. Results Rosuvastatin treatment increased the mean HDL-C concentration by 1.9±9.2 mg/dL (6.4±21.4%). HDL-C increased in 138 patients (57.5%), but decreased in 102 patients (42.5%) after statin treatment. PON1 activity increased to 19.1% in all patients. In both, the patients with increased HDL-C and with decreased HDL-C, PON1 activity significantly increased after rosuvastatin treatment (+19.3% in increased HDL-C responder; p=0.018, +18.8% in decreased HDL-C responder; p=0.045 by paired t-test). Baseline PON1 activity modestly correlated with HDL-C levels (r=0.248, p=0.009); however, the PON1 activity evaluated during the course of the treatment did not correlate with HDL-C levels (r=0.153, p=0.075). Conclusion Rosuvastatin treatment improved the anti-oxidative properties as assessed by PON1 activity, regardless of on-treatment HDL-C levels, in patients with stable ischemic heart disease. PMID:27275167

  13. 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.

  14. Activation of intestinal peroxisome proliferator-activated receptor-α increases high-density lipoprotein production

    PubMed Central

    Colin, Sophie; Briand, Olivier; Touche, Véronique; Wouters, Kristiaan; Baron, Morgane; Pattou, François; Hanf, Rémy; Tailleux, Anne; Chinetti, Giulia; Staels, Bart; Lestavel, Sophie

    2013-01-01

    Aims Peroxisome Proliferator-Activated Receptor (PPAR) α is a transcription factor controlling lipid metabolism in liver, heart, muscle and macrophages. PPARα-activation increases plasma HDL-cholesterol and exerts hypotriglyceridemic actions via the liver. However, the intestine expresses PPARα, produces HDL and chylomicrons and is exposed to diet-derived PPARα ligands. Therefore, we examined the effects of PPARα-activation on intestinal lipid and lipoprotein metabolism. Methods and Results The impact of PPARα-activation was evaluated in term of HDL-related gene expression in mice, ex-vivo in human jejunal biopsies and in Caco-2/TC7 cells. ApoAI/HDL secretion, cholesterol esterification and trafficking were also studied in-vitro. In parallel to improving plasma lipid profiles and increasing liver and intestinal expression of fatty-acid-oxidation genes, treatment with the dual PPARα/δ-ligand GFT505 resulted in a more pronounced increase of plasma HDL compared to fenofibrate in mice. GFT505, but not fenofibrate, increased the expression of HDL-production genes such as apolipoprotein-AI and ATP-Binding-Cassette-A1 transporter in murine intestines. A similar increase was observed upon PPARα-activation of human biopsies and Caco-2/TC7 cells. Additionally, HDL secretion by Caco-2/TC7 cells increased. Moreover, PPARα-activation decreased the cholesterol-esterification capacity of Caco-2/TC7 cells, modified cholesterol trafficking and reduced apolipoprotein-B secretion. Conclusions PPARα-activation reduces cholesterol esterification, suppresses chylomicron- and increases HDL-secretion by enterocytes. These results identify the intestine as a target organ of PPARα-ligands with entero-hepatic tropism to reduce atherogenic dyslipidemia. PMID:22843443

  15. Spatial and Statistical Evolution of Electrical Current Density in Active Region 12158 Producing an X-class Flare

    NASA Astrophysics Data System (ADS)

    Kang, Jihye; Magara, Tetsuya; Inoue, Satoshi; Kubo, Yuki; Nishizuka, Naoto

    2016-05-01

    The formation of a current sheet in the solar corona where an intense electric current flows is one of the important processes leading to the onset of a solar flare. In this work, we investigate the temporal development of the distribution of electric current density derived from a time series of nonlinear force-free (NLFF) fields in active region 12158 (AR12158) which produces an X-class flare on 2014 September 10. A preflare NLFF field, where an intense electric current flows, reproduces an observed inverse-S shaped sigmoidal structure. The statistical distribution of electric current density has a double power-law profile during the evolution of AR12158. We discuss several key parameters of the double power-law profile and the time variations in them, which might be used as a quantitative indicator of flare onset.

  16. Zinc cysteine active sites of metalloproteins: A density functional theory and x-ray absorption fine structure study

    NASA Astrophysics Data System (ADS)

    Dimakis, Nicholas; Farooqi, Mohammed Junaid; Garza, Emily Sofia; Bunker, Grant

    2008-03-01

    Density functional theory (DFT) and x-ray absorption fine structure (XAFS) spectroscopy are complementary tools for the biophysical study of active sites in metalloproteins. DFT is used to compute XAFS multiple scattering Debye Waller factors, which are then employed in genetic algorithm-based fitting process to obtain a global fit to the XAFS in the space of fitting parameters. Zn-Cys sites, which serve important functions as transcriptional switches in Zn finger proteins and matrix metalloproteinases, previously have proven intractable by this method; here these limitations are removed. In this work we evaluate optimal DFT nonlocal functionals and basis sets for determining optimal geometries and vibrational densities of states of mixed ligation Zn(His)4-n(Cys)n sites. Theoretical results are compared to experimental XAFS measurements and Raman spectra from the literature and tabulated for use.

  17. 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.

  18. Differential influence of physical activity on lumbar spine and femoral neck bone mineral density in the elderly population.

    PubMed

    Vuillemin, A; Guillemin, F; Jouanny, P; Denis, G; Jeandel, C

    2001-06-01

    This study investigates the relationship between lifetime physical activity and bone mineral density (BMD) at various sites in 129 healthy men and women aged 72.1 +/- 6.5 years. BMD was measured by dual energy x-ray absorptiometry, and physical activity was assessed by using the QUANTAP system (Quantification de l'Activité Physique), a standardized and structured computer-assisted interview tool designed to assess lifetime physical activity. Linear regression models controlling for age, gender, height, body mass, lean mass, and smoking habits were performed. Higher levels of sporting activity during youth were associated with greater lumbar spine BMD ( p < .001). Similarly, femoral neck BMD was greatest in subjects who reported regularly taking part in sports over the previous 20 years ( p <. 05) and during their whole lifetime ( p < 0.05). Sporting activity at the time of bone mass development increases subsequent lumbar spine BMD, and more recent sporting activity contributes to the preservation of femoral neck BMD. These results suggest that physical activity has a differential influence on BMD at different sites and at different ages, possibly related to the processes of bone construction and bone aging taking place at the time. PMID:11382786

  19. The inhibiting activity of areca inflorescence extracts on human low density lipoprotein oxidation induced by cupric ion.

    PubMed

    Chen, Weijun; Zhang, Chunmei; Huang, Yulin; Cheng, Fangfang; Shen, Yan; Wang, Rencai; Tang, Minmin; Zheng, Yajun; Zhao, Songlin

    2012-03-01

    The oxidative modification of human low density lipoprotein (LDL) plays a significant role in atherosclerosis. In this study, the inhibiting activity of areca inflorescence extracts (AIEs) on LDL oxidation was investigated by an in vitro study with Trolox as the standard antioxidant. The kinetics of LDL oxidation, thiobarbituric acid reactive substances assay, ferric-reducing antioxidant power assay and copper chelation assay were also evaluated to assess the antioxidant activities of AIEs, and the results revealed that AIEs could delay the lag time and inhibit the formation of malondialdehyde in the process of LDL peroxidation induced by Cu(2+). The boiled water extract displayed the highest antioxidant activity compared with the ambient water extract and ethanol extract. The total phenolic contents and phenolic components of AIEs were also measured by high performance liquid chromatography method. Epicatechin, gallic acid and coumalic acid were the primary phenolic acids in AIEs. PMID:21942744

  20. Active tuning of mid-infrared metamaterials by electrical control of carrier densities.

    PubMed

    Jun, Young Chul; Gonzales, Edward; Reno, John L; Shaner, Eric A; Gabbay, Alon; Brener, Igal

    2012-01-16

    We demonstrate electrically-controlled active tuning of mid-infrared metamaterial resonances using depletion-type devices. The depletion width in an n-doped GaAs epilayer changes with an electric bias, inducing a change of the permittivity of the substrate and leading to frequency tuning of the resonance. We first present our detailed theoretical analysis and then explain experimental data of bias-dependent metamaterial transmission spectra. This electrical tuning is generally applicable to a variety of infrared metamaterials and plasmonic structures, which can find novel applications in chip-scale active infrared devices. PMID:22274535

  1. The Use of Kernel Density Estimation to Examine Associations between Neighborhood Destination Intensity and Walking and Physical Activity

    PubMed Central

    King, Tania L.; Thornton, Lukar E.; Bentley, Rebecca J.; Kavanagh, Anne M.

    2015-01-01

    Background Local destinations have previously been shown to be associated with higher levels of both physical activity and walking, but little is known about how the distribution of destinations is related to activity. Kernel density estimation is a spatial analysis technique that accounts for the location of features relative to each other. Using kernel density estimation, this study sought to investigate whether individuals who live near destinations (shops and service facilities) that are more intensely distributed rather than dispersed: 1) have higher odds of being sufficiently active; 2) engage in more frequent walking for transport and recreation. Methods The sample consisted of 2349 residents of 50 urban areas in metropolitan Melbourne, Australia. Destinations within these areas were geocoded and kernel density estimates of destination intensity were created using kernels of 400m (meters), 800m and 1200m. Using multilevel logistic regression, the association between destination intensity (classified in quintiles Q1(least)—Q5(most)) and likelihood of: 1) being sufficiently active (compared to insufficiently active); 2) walking≥4/week (at least 4 times per week, compared to walking less), was estimated in models that were adjusted for potential confounders. Results For all kernel distances, there was a significantly greater likelihood of walking≥4/week, among respondents living in areas of greatest destinations intensity compared to areas with least destination intensity: 400m (Q4 OR 1.41 95%CI 1.02–1.96; Q5 OR 1.49 95%CI 1.06–2.09), 800m (Q4 OR 1.55, 95%CI 1.09–2.21; Q5, OR 1.71, 95%CI 1.18–2.48) and 1200m (Q4, OR 1.7, 95%CI 1.18–2.45; Q5, OR 1.86 95%CI 1.28–2.71). There was also evidence of associations between destination intensity and sufficient physical activity, however these associations were markedly attenuated when walking was included in the models. Conclusions This study, conducted within urban Melbourne, found that those who lived

  2. 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

  3. Volcanic activity and its link to glaciation cycles: Single-grain age and geochemistry of Early to Middle Miocene volcanic glass from ANDRILL AND-2A core, Antarctica

    NASA Astrophysics Data System (ADS)

    Nyland, R. E.; Panter, K. S.; Rocchi, S.; Di Vincenzo, G.; Del Carlo, P.; Tiepolo, M.; Field, B.; Gorsevski, P.

    2013-01-01

    In the frame of the ANtarctic DRILLing Program, volcanic glass fragments were collected from the AND-2A core between ~ 354 and 765 m below sea floor (mbsf) as accumulations (5-70 vol.%) within sediments. Here, we present the physical characteristics, age and geochemistry of the glass, which enable us to reconstruct Early to Middle Miocene volcanic activity in southern McMurdo Sound and, for the first time, document the response of volcanism to climate change in Antarctica. Glass-rich sediments include muddy-to-fine sandstone and stratified diamictite. Glass varies in color, size, vesicularity, crystal content, angularity, and degree of alteration. The mostly fresh glass exhibits delicate cuspate forms indicating deposition as primary ash fall. 40Ar-39Ar age determinations on individual glass grains are in good agreement with the depositional age model of the sediments (ca. 15.6 to 18.6 Ma), supporting for most of them a primary origin, however, some samples do contain older fragments that indicate glass recycling during times of enhanced glacial erosion. Most glasses are mafic (MgO = 3 to 9 wt.%) and vary from hypersthene to nepheline normative with a restricted range in SiO2 (45.2 ± 0.8 wt.%, 1σ) and trace element concentrations typical of the rift-related alkaline rocks in the Erebus Volcanic Province. The glass extends known composition of early phase Mount Morning activity (ca. 11-19 Ma), the only known Early to Middle Miocene source, to a more mafic end, revealing a previously unknown explosive, strongly alkaline, basaltic phase and the most primitive forms of both strongly alkaline (basanite to phonolite) and moderately alkaline (alkali basalt to trachyte) magma associations. The glass-rich sediments occur in glacimarine sequences that record 56 cycles of glacial advance and retreat. Volcanic response to glacial cyclicity is observed both physically and geochemically in AND-2A glass. Higher glass volumes in sediments correlate with ice minimum conditions

  4. Current Activities Assessing Butt Fusion Joint Integrity in High Density Polyethylene Piping

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Doctor, Steven R.; Denslow, Kayte M.

    2012-09-01

    The Pacific Northwest National Laboratory (PNNL) in Richland, Washington, conducted initial studies to evaluate the effectiveness of nondestructive examinations (NDE) coupled with mechanical testing for assessing butt fusion joint integrity in high density polyethylene (HDPE) pipe. The work provided insightful information to the United States Nuclear Regulatory Commission (NRC) on the effectiveness of volumetric inspection techniques for detecting lack of fusion (LOF) conditions in the fusion joints. HDPE has been installed on a limited basis in American Society of Mechanical Engineers (ASME) Class 3, buried piping systems at several operating U.S. nuclear power plants and has been proposed for use in new construction. A comparison was made between the results from ultrasonic and microwave nondestructive examinations and the results from mechanical destructive evaluations, specifically the high-speed tensile test and the side-bend test, for determining joint integrity. The data comparison revealed that none of the NDE techniques detected all of the lack-of-fusion conditions that were revealed by the destructive tests. Follow-on work has recently been initiated at PNNL to accurately characterize the NDE responses from machined flaws of varying size and location in PE 4710 materials as well as the LOF condition. This effort is directed at quantifying the ability of volumetric NDE techniques to detect flaws in relation to the critical flaw size associated with joint integrity. A status of these latest investigations is presented.

  5. Source segregation and food waste prevention activities in high-density households in a deprived urban area

    SciTech Connect

    Rispo, A.; Williams, I.D. Shaw, P.J.

    2015-10-15

    Highlights: • Study of waste management in economically and socially deprived high-density housing. • Food waste segregation, prevention and recycling activities investigated. • Study involved a waste audit and household survey of 1034 households. • Populations in such areas are “hard-to-reach”. • Exceptional efforts and additional resources are required to improve performance. - Abstract: A waste audit and a household questionnaire survey were conducted in high-density housing estates in one of the most economically and socially deprived areas of England (Haringey, London). Such areas are under-represented in published research. The study examined source segregation, potential participation in a food waste segregation scheme, and food waste prevention activities in five estates (1034 households). The results showed that: contamination of recyclables containers was low; ca. 28% of the mixed residual waste’s weight was recyclable; food waste comprised a small proportion of the waste from these residents, probably because of their relatively disadvantaged economic circumstances; and the recycling profile reflected an intermittent pattern of behaviour. Although the majority of respondents reported that they would participate in a food waste separation scheme, the response rate was low and many responses of “don’t know” were recorded. Municipalities committed to foster improved diversion from landfill need to recognise that there is no “quick and easy fix”, regardless of local or national aspirations. Lasting and sustained behaviour change requires time and the quality of service provision and associated infrastructure play a fundamental role in facilitating residents to participate effectively in waste management activities that maximise capture of source-segregated materials. Populations in deprived areas that reside in high-rise, high-density dwellings are “hard-to-reach” in terms of participation in recycling schemes and exceptional

  6. Dislocation Content Measured Via 3D HR-EBSD Near a Grain Boundary in an AlCu Oligocrystal

    NASA Technical Reports Server (NTRS)

    Ruggles, Timothy; Hochhalter, Jacob; Homer, Eric

    2016-01-01

    Interactions between dislocations and grain boundaries are poorly understood and crucial to mesoscale plasticity modeling. Much of our understanding of dislocation-grain boundary interaction comes from atomistic simulations and TEM studies, both of which are extremely limited in scale. High angular resolution EBSD-based continuum dislocation microscopy provides a way of measuring dislocation activity at length scales and accuracies relevant to crystal plasticity, but it is limited as a two-dimensional technique, meaning the character of the grain boundary and the complete dislocation activity is difficult to recover. However, the commercialization of plasma FIB dual-beam microscopes have made 3D EBSD studies all the more feasible. The objective of this work is to apply high angular resolution cross correlation EBSD to a 3D EBSD data set collected by serial sectioning in a FIB to characterize dislocation interaction with a grain boundary. Three dimensional high angular resolution cross correlation EBSD analysis was applied to an AlCu oligocrystal to measure dislocation densities around a grain boundary. Distortion derivatives associated with the plasma FIB serial sectioning were higher than expected, possibly due to geometric uncertainty between layers. Future work will focus on mitigating the geometric uncertainty and examining more regions of interest along the grain boundary to glean information on dislocation-grain boundary interaction.

  7. Tai Chi Chuan exercises in enhancing bone mineral density in active seniors.

    PubMed

    Lui, Pauline Po Yee; Qin, Ling; Chan, Kai Ming

    2008-01-01

    Osteoporosis is a silent, systemic, chronic disease characterized by low bone mass and structural deterioration of bone tissue. Its clinical and public health implications are substantial because of the mortality, morbidity, and medical care cost associated with osteoporotic fractures. Although estrogen-replacement therapy or anti-bone resorptive drugs can prevent postmenopausal bone loss, they also show side effects. Physical activity is an nonpharmacological approach for prevention of osteoporosis. Among different types of physical activities, Tai Chi Chuan (TCC) is a low- to moderate-intensity exercise particularly suitable for the elderly, and has been practiced by Chinese for centuries. This article reviews the benefits of TCC for the prevention of osteoporosis and falls by retarding bone loss, improving neuromuscular coordination, and promoting general health. PMID:18206569

  8. 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.

  9. [THE EFFECT OF SATINS: ACTIVATION OF LIPOLYSIS AND ABSORPTION BY INSULIN-DEPENDED CELLS LIPOPROTEINS OF VERY LOW DENSITY, INCREASING OF BIO-AVAILABILITY OF POLYENOIC FATTY ACIDS AND DECREASING OF CHOLESTEROL OF LIPOPROTEINS OF LOW DENSITY].

    PubMed

    Titov, V N; Malyshev, P P; Amelyushkina, V A; Aripovsky, A V; Smirnov, G P; Polevaya, T Yu; Kabo, S I; Kukhartchuk, V V

    2015-10-01

    The Russian cardiologic R&D production complex of Minzdrav of Russia, 121552 Moscow, Russia The statins are synthetic xenobiotics alien to animal cells. They are unlikely capable to manifest pleiotropic effect. It is feasible to evaluate effect of statins by stages: a) initially a specific inhibition of synthesis of cholesterol alcohol; b) further indirect activation of hydrolysis of triglycerides in lipoproteins of very low density; c) nonspecific activation of cells' receptor absorption of palmitic and oleic lipoproteins of very low density and then d) linoleic and linolenic lipoproteins of low density with all polyenoic fatty acids. On balance, statins activate absorption ofpolyenoic fatty acids by cells. Just they manifest physiological, specific pleiotropic effect. The statins inhibit synthesis of pool of cholesterol alcohol-lipoproteins of very low density condensed between phosphatidylcholines in polar mono-layer phosphatidylcholines+cholesterol alcohol on surface oftriglycerides. The low permeability of mono-layer separates substrate-triglycerides in lipoproteins of very low density and post-heparin lipoprotein lipase in hydrophilic blood plasma. The higher is ratio cholesterol alcohol/phosphatidylcholines in mono-layer of lipoproteins of very low density the slower is lipolysis, formation of ligand lipoproteins of very low density and their absorption by cells under apoB-100-endocytosis. The statins normalize hyperlipemia by force of a) activation of absorption oflipoproteins of very low density by insulin-depended cells and b) activation of absorption of lipoproteins of low density by all cells, increasing of bio-availability of polyenoic fatty acids, activation of apoB-100-endocytosis. The limitation in food of content of palmitic saturated fatty acid and increasing of content of ω-3 polyenoic fatty acids improve "bio-availability" of polyenoic fatty acids and their absorption by cells and also decreases cholesterol alcohol/phosphatidylcholines and

  10. High-density active optical cable: from a new concept to a prototype

    NASA Astrophysics Data System (ADS)

    Wohlfeld, Denis; Lemke, Frank; Froening, Holger; Schenk, Sven; Bruening, Ulrich

    2011-01-01

    Evolution in high performance computing (HPC) leads to increasing demands on bandwidth, connectivity and flexibility. Active optical cables (AOC) are of special interest, combining the benefits of electrical connectors and optical transmission. Optimization and development of AOC solutions requires enhancements concerning different technology barriers. Area and volume occupied by connectors is of special interest within HPC networks. This led to the development of a 12x AOC for the mini-HT connector creating the densest AOC available. In order to integrate electrical optical conversion into a module not higher than 3 mm, a new concept of coupling fibers to VCSELs or photodiodes had to be developed. This unique concept is based on a direct replication process of an integrated fiber coupler consisting of a 90° light deflecting and focusing mirror, a fiber guiding structure, and a fiber funnel. The integrated fiber coupler is directly replicated on top of active components, reducing the distance between active components and fibers to a minimum, thus providing a highly efficient light coupling. As AOC prototype, multi-chipmodules (MCM) including the complete electrical to optical conversion for send and receive connected by two 12x fiber ribbons have been developed. The paper presents the integrated fiber coupling technique and also design and measurement data of the prototype.

  11. Dietary saturated triacylglycerols suppress hepatic low density lipoprotein receptor activity in the hamster.

    PubMed Central

    Spady, D K; Dietschy, J M

    1985-01-01

    The liver plays a key role in the regulation of circulating levels of low density lipoproteins (LDL) because it is both the site for the production of and the major organ for the degradation of this class of lipoproteins. In this study, the effects of feeding polyunsaturated or saturated triacylglycerols on receptor-dependent and receptor-independent hepatic LDL uptake were measured in vivo in the hamster. In control animals, receptor-dependent LDL transport manifested an apparent Km value of 85 mg/dl (plasma LDL-cholesterol concentration) and reached a maximum transport velocity of 131 micrograms of LDL-cholesterol/hr per g, whereas receptor-independent uptake increased as a linear function of plasma LDL levels. Thus, at normal plasma LDL-cholesterol concentrations, the hepatic clearance rate of LDL equaled 120 and 9 microliter/hr per g by receptor-dependent and receptor-independent mechanisms, respectively. As the plasma LDL-cholesterol was increased, the receptor-dependent (but not the receptor-independent) component declined. When cholesterol (0.12%) alone or in combination with polyunsaturated triacylglycerols was fed for 30 days, receptor-dependent clearance was reduced to 36-42 microliter/hr per g, whereas feeding of cholesterol plus saturated triacylglycerols essentially abolished receptor-dependent LDL uptake (5 microliter/hr per g). When compared to the appropriate kinetic curves, these findings indicated that receptor-mediated LDL transport was suppressed approximately equal to 30% by cholesterol feeding alone and this was unaffected by the addition of polyunsaturated triacylglycerols to the diet. In contrast, receptor-dependent uptake was suppressed approximately equal to 90% by the intake of saturated triacylglycerols. As compared to polyunsaturated triacylglycerols, the intake of saturated lipids was also associated with significantly higher plasma LDL-cholesterol concentrations and lower levels of cholesteryl esters in the liver. Images PMID:2989830

  12. Cosmic ray density gradient and its dependence on the north-south asymmetry in solar activity

    NASA Technical Reports Server (NTRS)

    BADRUDDIN; Yadav, R. S.; Yadav, N. R.

    1985-01-01

    An analysis of the diurnal anisotropy on geomagnetically quiet days was performed using neutron monitor data at Deep River, Leeds, Rome and Tokyo, well distributed in latitude and longitude for the period 1964-79. The days were separated according to the polarity of IMF on that day. A significant difference in the amplitude and phase was found on towards and away polarity days, particularly during the years of high solar activity and large north-south asymmetry. These results (particularly time of maximum) on geomagnetically quiet days show some better relationship to the expected results as compared to the results obtained using all the days in a year.

  13. Para-aminobenzamidine linked regenerated cellulose membranes for plasminogen activator purification: Effect of spacer arm length and ligand density

    PubMed Central

    Fasoli, Ezio; Reyes, Yiaslin Ruiz; Guzman, Osiris Martinez; Rosado, Alexandra; Cruz, Vivian Rodriguez; Borges, Amaris; Martinez, Edmarie; Bansal, Vibha

    2013-01-01

    Despite membrane-based separations offering superior alternative to packed bed chromatographic processes, there has been a substantial lacuna in their actual application to separation processes. One of the major reasons behind this is the lack of availability of appropriately modified or end-group modifiable membranes. In this paper, an affinity membrane was developed using a commercially available serine protease inhibitor, para-aminobenzamidine (pABA). The membrane modification was optimized for protein binding capacity by varying: i) the length of the spacer arm (SA; 5-atoms, 7-atoms, and 14-atoms) linking the ligand to membrane surface; ii) the affinity ligand (pABA) density on membrane surface (5–25 nmoles per cm2). Resulting membranes were tested for their ability to bind plasminogen activators (PAs) from mono- and multi- component systems in batch mode. The membrane containing pABA linked through 7-atoms SA but similar ligand density as in the case of 5- or 14- atoms long SA was found to bind up to 1.6-times higher amounts of PA per nmole of immobilized ligand from conditioned HeLa cell culture media. However, membranes with similar ligand densities but different lengths of SA, showed comparable binding capacities in monocomponent system. In addition, the length of SA did not affect the selectivity of the ligand for PA. A clear inverse linear correlation was observed between ligand density and binding capacity until the point of PA binding optima was reached (11±1.0 nmoles per cm2) in mono- and multi- component systems for 7- as well as 14- atoms SA. Up to 200-fold purification was achieved in a single step separation of PA from HeLa conditioned media using these affinity membranes. The issues of ligand leaching and reuse of the membranes were also investigated. An extensive regeneration procedure allowed the preservation of approximately 95% of the PA binding capacity of the membranes even after five cycles of use. PMID:23703544

  14. Decreased shoot stature and grain alpha-amylase activity following ectopic expression of a gibberellin 2-oxidase gene in transgenic wheat.

    PubMed

    Appleford, Nigel E J; Wilkinson, Mark D; Ma, Qian; Evans, Daniel J; Stone, Marlon C; Pearce, Stephen P; Powers, Stephen J; Thomas, Stephen G; Jones, Huw D; Phillips, Andrew L; Hedden, Peter; Lenton, John R

    2007-01-01

    Ectopic expression of a gibberellin 2-oxidase gene (PcGA2ox1) decreased the content of bioactive gibberellins (GAs) in transgenic wheat, producing a range of dwarf plants with different degrees of severity. In at least one case, a single transformation event gave rise to T(1) plants with different degrees of dwarfism, the phenotypes being stably inherited over at least four generations. The dwarf phenotype, which included dark-green leaves, increased tillering and, in severe cases, a prostrate growth habit, was replicated by the application of a GA biosynthesis inhibitor to the wild type. Ear rachis length, grain set, and grain size were also decreased in the wheat transformants, compared with an azygous (null) line. The extent of post-germination alpha-amylase production in grains reflected the severity of the shoot phenotype of the transformants and both developmental processes were restored to normal by the application of gibberellic acid (GA(3)). Expression of two GA biosynthesis genes (TaGA20ox1 and TaGA3ox2) was up-regulated, and that of two alpha-amylase gene families (alpha-Amy1 and alpha-Amy2) down regulated, in scutella of semi-dwarf lines, compared with controls. The marked decline in transcript abundance of both alpha-amylase gene families in aleurone was associated with a decreased content of bioactive GAs in grains of the semi-dwarf lines. PMID:17916639

  15. Catalytic activity of bimetallic nickel alloys for solid-oxide fuel cell anode reactions from density-functional theory

    NASA Astrophysics Data System (ADS)

    An, Wei; Gatewood, Daniel; Dunlap, Brett; Turner, C. Heath

    2011-05-01

    We present density-functional theory calculations of the chemisorption of atomic species O, S, C, H and reaction intermediates OH, SH, and CHn (n = 1, 2, and 3) on M/Ni alloy model catalysts (M = Bi, Mo, Fe, Co, and Cu). The activity of the Ni alloy catalysts for solid-oxide fuel cell (SOFC) anode oxidation reactions is predicted, based on a simple descriptor, i.e., the binding energy of oxygen. First, we find that the binding of undesirable intermediates, such as C and S, can be inhibited and the catalytic activity of planar Ni-based anodes can be tuned towards oxidation by selectively forming a bimetallic surface alloy. In particular, Cu/Ni, Fe/Ni, and Co/Ni anode catalysts are found to be most active towards anode oxidation. On the other hand, the Mo/Ni alloy surface is predicted to be the most effective catalyst in terms of inhibiting the deposition of C and S (while still preserving relatively high catalytic activity). The formation of a surface alloy, which has the alloy element enriched on the topmost surface, was found to be critical to the activity of the Ni alloy catalysts.

  16. Effect of pen size, group size, and stocking density on activity in freestall-housed dairy cows.

    PubMed

    Telezhenko, E; von Keyserlingk, M A G; Talebi, A; Weary, D M

    2012-06-01

    The purpose was to determine the effects of the physical dimensions of the pen and group size and stocking density on cow activity. Cows (randomly assigned to 4 groups of 6 animals each) were tested in pens with 24 or 12 lying places and in groups with 12 or 6 cows. All groups were tested in each of the 4 treatments with treatment order allocated using a 4 × 4 Latin square. The distance moved and the number of movements were calculated using 5-min scan sampling of video recordings over a 48-h period. Time spent lying down, number of lying bouts, and the duration of each lying bout were recorded using activity sensors. Displacements at the feed bunk were assessed by continuous analysis of video for 3h after the delivery of the fresh feed in the afternoon. Cows moved greater distances when kept in a large versus small pens (330.2 vs. 270.1 ± 11.6 m/d; mean ± SE), irrespective of group size. Cows moved more often when kept in the larger pen (21.3 vs. 19.2 ± 0.63% of scans). The time spent lying down decreased when density increased (59.1 vs. 55.8 ± 2.3% of scans at 25% and 100% stocking, respectively). Treatment had no effect on the number of displacements at the feed bunk. Physical dimensions of the pen play an important role in how much cows move, and stocking density affects lying time. PMID:22612942

  17. Add-on rosiglitazone therapy improves plasminogen activity and high-density lipoprotein cholesterol in type 2 diabetes mellitus.

    PubMed

    Mustaffa, Nazri; Ibrahim, Suhairi; Abdullah, Wan Zaidah; Yusof, Zurkurnai

    2011-09-01

    Rosiglitazone is an oral hypoglycaemic agent of the thiazolidinedione group. This study aimed to assess changes in the diabetic prothrombotic state via plasminogen activity and changes in surrogate markers of atherosclerotic burden via ankle-brachial pressure index (ABPI) measurements after rosiglitazone was added to a pre-existing type 2 diabetes mellitus treatment regime. A nonblinded interventional study was designed. Fifty-nine patients were enrolled. Rosiglitazone-naïve patients were prescribed oral rosiglitazone 4 mg daily for 10 weeks. ABPI, plasminogen activity, glycosylated haemoglobin (HbA1c) and fasting lipid profile were measured pretreatment and post-treatment. Forty-eight patients completed the study. At the end of this study, mean plasminogen activity improvement was nearly 16% (P<0.05), mean ABPI improvement was 0.01 (P=0.439), mean HbA1c reduction was 0.51% (P<0.05), mean total cholesterol (TC) increase was 0.36 mmol/l (P<0.05), mean high-density lipoprotein cholesterol (HDL-C) increase was 0.15 mmol/l (P<0.05) and mean low-density lipoprotein cholesterol increased by 0.19 mmol/l (P=0.098). Rosiglitazone significantly improved plasminogen activity. There was also significant HbA1c reduction, and rise in both TC and HDL-C. Thus, rosiglitazone potentially improves the atherosclerotic burden and prothrombotic state. In future, more studies are needed to confirm the relationship between rosiglitazone, fibrinolytic system and atheromatous reduction in type 2 diabetes mellitus. PMID:21537159

  18. Metal-Organic Frameworks as Highly Active Electrocatalysts for High-Energy Density, Aqueous Zinc-Polyiodide Redox Flow Batteries.

    PubMed

    Li, Bin; Liu, Jian; Nie, Zimin; Wang, Wei; Reed, David; Liu, Jun; McGrail, Pete; Sprenkle, Vincent

    2016-07-13

    The new aqueous zinc-polyiodide redox flow battery (RFB) system with highly soluble active materials as well as ambipolar and bifunctional designs demonstrated significantly enhanced energy density, which shows great potential to reduce RFB cost. However, the poor kinetic reversibility and electrochemical activity of the redox reaction of I3(-)/I(-) couples on graphite felts (GFs) electrode can result in low energy efficiency. Two nanoporous metal-organic frameworks (MOFs), MIL-125-NH2 and UiO-66-CH3, that have high surface areas when introduced to GF surfaces accelerated the I3(-)/I(-) redox reaction. The flow cell with MOF-modified GFs serving as a positive electrode showed higher energy efficiency than the pristine GFs; increases of about 6.4% and 2.7% occurred at the current density of 30 mA/cm(2) for MIL-125-NH2 and UiO-66-CH3, respectively. Moreover, UiO-66-CH3 is more promising due to its excellent chemical stability in the weakly acidic electrolyte. This letter highlights a way for MOFs to be used in the field of RFBs. PMID:27267589

  19. Source segregation and food waste prevention activities in high-density households in a deprived urban area.

    PubMed

    Rispo, A; Williams, I D; Shaw, P J

    2015-10-01

    A waste audit and a household questionnaire survey were conducted in high-density housing estates in one of the most economically and socially deprived areas of England (Haringey, London). Such areas are under-represented in published research. The study examined source segregation, potential participation in a food waste segregation scheme, and food waste prevention activities in five estates (1034 households). The results showed that: contamination of recyclables containers was low; ca. 28% of the mixed residual waste's weight was recyclable; food waste comprised a small proportion of the waste from these residents, probably because of their relatively disadvantaged economic circumstances; and the recycling profile reflected an intermittent pattern of behaviour. Although the majority of respondents reported that they would participate in a food waste separation scheme, the response rate was low and many responses of "don't know" were recorded. Municipalities committed to foster improved diversion from landfill need to recognise that there is no "quick and easy fix", regardless of local or national aspirations. Lasting and sustained behaviour change requires time and the quality of service provision and associated infrastructure play a fundamental role in facilitating residents to participate effectively in waste management activities that maximise capture of source-segregated materials. Populations in deprived areas that reside in high-rise, high-density dwellings are "hard-to-reach" in terms of participation in recycling schemes and exceptional efforts and additional resources are usually required to improve performance. PMID:26233881

  20. The mechanism of small-gas detonation in mechanically activated low-density powder mixtures

    NASA Astrophysics Data System (ADS)

    Rashkovskii, S. A.; Dolgoborodov, A. Yu.

    2015-06-01

    A mechanism of supersonic propagation of the energy-release wave in mechanically activated small-gas explosive powder mixtures is proposed. It is shown that, under certain conditions, this process exhibits all the signs of detonation and should be recognized as a kind of thereof. On the other hand, this kind of detonation is fundamentally different from classical detonation, e.g., in gases. Instead of a shock wave, the powder mixture features propagation of a compression wave, in which the powder exhibits densification due to the mutual displacement of particles rather than contraction of the particle material. A chemical reaction is initiated by the mutual friction of particles in the compression wave.

  1. Assessment of strontium oxide functionalized graphene nanoflakes for enhanced photocatalytic activity: A density functional theory approach

    NASA Astrophysics Data System (ADS)

    Divya, A.; Mathavan, T.; Asath, R. Mohamed; Archana, J.; Hayakawa, Y.; Benial, A. Milton Franklin

    2016-05-01

    A series of strontium oxide functionalized graphene nanoflakes were designed and their optoelectronic properties were studied for enhanced photocatalytic activity. The efficiency of designed molecules was studied using various parameters such as HOMO-LUMO energy gap, light harvesting efficiency and exciton binding energy. The computed results show that by increasing the degree of functionalization of strontium oxide leads to lowering the band gap of hydrogen terminated graphene nanoflakes. Furthermore, the study explores the role of strontium oxide functionalization in Frontier Molecular Orbitals, ionization potential, electron affinity, exciton binding energy and light harvesting efficiency of designed molecules. The infrared and Raman spectra were simulated for pure and SrO functionalized graphene nanoflakes. The electron rich and electron deficient regions which are favorable for electrophilic and nucleophilic attacks respectively were analyzed using molecular electrostatic potential surface analysis.

  2. Detection of insects in grain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Detecting insects hidden inside kernels of grain is important to grain buyers because internal infestations can result in insect fragments in products made from the grain, or, if the grain is stored before use, the insect population can increase and damage the grain further. In a study in the Unite...

  3. Electronic Structure of a Disordered Grain Boundary in Graphene

    NASA Astrophysics Data System (ADS)

    Lambin, Ph.; Vancso, P.; Nemes-Incze, P.; Mark, G.; Biró, L. P.

    2013-05-01

    Grain boundaries are constitutional elements of graphene grown on a solid metallic surface by CVD. The electronic properties of computer models of grain boundaries in graphene have been investigated by tight-binding calculations and compared with available ab initio data and with recent experimental scanning tunneling spectroscopic measurements. It is shown that twofold coordinated atoms and non-hexagonal rings, both present in grain boundaries, give rise to specific features in the local density of states.

  4. Microstructure stability of ultra-fine grained magnesium alloy AZ31 processed by extrusion and equal-channel angular pressing (EX–ECAP)

    SciTech Connect

    Stráská, Jitka; Janeček, Miloš; Čížek, Jakub; Stráský, Josef; Hadzima, Branislav

    2014-08-15

    Thermal stability of the ultra-fine grained (UFG) microstructure of magnesium AZ31 alloy was investigated. UFG microstructure was achieved by a combined two-step severe plastic deformation process: the extrusion (EX) and subsequent equal-channel angular pressing (ECAP). This combined process leads to refined microstructure and enhanced microhardness. Specimens with UFG microstructure were annealed isochronally at temperatures 150–500 °C for 1 h. The evolution of microstructure, mechanical properties and dislocation density was studied by electron backscatter diffraction (EBSD), microhardness measurements and positron annihilation spectroscopy (PAS). The coarsening of the fine-grained structure at higher temperatures was accompanied by a gradual decrease of the microhardness and decrease of dislocation density. Mechanism of grain growth was studied by general equation for grain growth and Arrhenius equation. Activation energies for grain growth were calculated to be 115, 33 and 164 kJ/mol in temperature ranges of 170–210 °C, 210–400 °C and 400–500 °C (443–483 K, 483–673 K and 673–773 K), respectively. - Highlights: • Microhardness of UFG AZ31 alloy decreases with increasing annealing temperature. • This fact has two reasons: dislocation annihilations and/or grain growth. • The activation energies for grain growth were calculated for all temperature ranges.

  5. High Levels of Serum DPP-4 Activity Are Associated with Low Bone Mineral Density in Obese Postmenopausal Women

    PubMed Central

    2016-01-01

    Background Dipeptidyl peptidase 4/CD26 (DPP-4) is a widely expressed cell surface serine protease. DPP-4 inhibitors, one of common anti-diabetic agents play a protective role in bone metabolism in recent studies. A soluble form of DPP-4 is found in serum, and exhibits DPP-4 enzymatic activity. However, the physiological role of serum or soluble DPP-4 and its relationship with DPP-4 enzymatic function remain poorly understood. The aims of current study were to determine the association between serum DPP-4 activity and bone mineral density (BMD) in postmenopausal women. Methods We recruited data and serum samples from 124 consecutive healthy postmenopausal women aged >50 years. We divided study subjects into obese (body mass index [BMI] ≥25 kg/m2) and non-obese (BMI <25 kg/m2) postmenopausal women and examined the correlation between serum DPP-4 activity and clinical variables in each groups. Results A total of 124 postmenopausal women was enrolled, with a mean age of 59.9±7.1 years. The mean BMI of the study patients was 24.4±2.8 kg/m2. Regarding bone turnover markers, serum DPP-4 activity was positively correlated with serum calcium concentrations, intact parathyroid hormone, and serum C-telopeptide levels in all of the study subjects. However, there was no association between serum DPP-4 activity and BMD in the spine or femoral neck in all of the study subjects. Serum DPP-4 activity was negatively correlated (R=−0.288, P=0.038) with BMD of the spine in obese postmenopausal women. Conclusion This study demonstrated for the first time that serum soluble DPP-4 activity was negatively correlated with BMD in obese postmenopausal women. PMID:26676330

  6. Screening of catalytic oxygen reduction reaction activity of metal-doped graphene by density functional theory

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Chen, Shuangjing; Wang, Jinyu

    2016-08-01

    Graphene doping is a promising direction for developing effective oxygen reduction reaction (ORR) catalysts. In this paper, we computationally investigated the ORR performance of 10 kinds of metal-doped graphene (M-G) catalysts, namely, Al-, Si-, Mn-, Fe-, Co-, Ni-, Pd-, Ag-, Pt-, and Au-G. The results shown that the binding energies of the metal atoms incorporated into the graphene vacancy are higher than their bulk cohesive energies, indicating the formed M-G catalysts are even more stable than the corresponding bulk metal surfaces, and thus avoid the metals dissolution in the reaction environment. We demonstrated that the linear relation among the binding energies of the ORR intermediates that found on metal-based materials does not hold for the M-G catalysts, therefore a single binding energy of intermediate alone is not sufficient to evaluate the ORR activity of an arbitrary catalyst. By analysis of the detailed ORR processes, we predicted that the Au-, Co-, and Ag-G materials can be used as the ORR catalysts.

  7. The effect of grain size on aluminum anodes for Al-air batteries in alkaline electrolytes

    NASA Astrophysics Data System (ADS)

    Fan, Liang; Lu, Huimin

    2015-06-01

    Aluminum is an ideal material for metallic fuel cells. In this research, different grain sizes of aluminum anodes are prepared by equal channel angular pressing (ECAP) at room temperature. Microstructure of the anodes is examined by electron backscatter diffraction (EBSD) in scanning electron microscope (SEM). Hydrogen corrosion rates of the Al anodes in 4 mol L-1 NaOH are determined by hydrogen collection method. The electrochemical properties of the aluminum anodes are investigated in the same electrolyte using electrochemical impedance spectroscopy (EIS) and polarization curves. Battery performance is also tested by constant current discharge at different current densities. Results confirm that the electrochemical properties of the aluminum anodes are related to grain size. Finer grain size anode restrains hydrogen evolution, improves electrochemical activity and increases anodic utilization rate. The proposed method is shown to effectively improve the performance of Al-air batteries.

  8. Grain-boundary-enhanced carrier collection in CdTe solar cells.

    PubMed

    Li, Chen; Wu, Yelong; Poplawsky, Jonathan; Pennycook, Timothy J; Paudel, Naba; Yin, Wanjian; Haigh, Sarah J; Oxley, Mark P; Lupini, Andrew R; Al-Jassim, Mowafak; Pennycook, Stephen J; Yan, Yanfa

    2014-04-18

    When CdTe solar cells are doped with Cl, the grain boundaries no longer act as recombination centers but actively contribute to carrier collection efficiency. The physical origin of this remarkable effect has been determined through a combination of aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and first-principles theory. Cl substitutes for a large proportion of the Te atoms within a few unit cells of the grain boundaries. Density functional calculations reveal the mechanism, and further indicate the grain boundaries are inverted to n type, establishing local p-n junctions which assist electron-hole pair separation. The mechanism is electrostatic, and hence independent of the geometry of the boundary, thereby explaining the universally high collection efficiency of Cl-doped CdTe solar cells. PMID:24785058

  9. Kaempferol stimulates gene expression of low-density lipoprotein receptor through activation of Sp1 in cultured hepatocytes

    PubMed Central

    Ochiai, Ayasa; Miyata, Shingo; Iwase, Masamori; Shimizu, Makoto; Inoue, Jun; Sato, Ryuichiro

    2016-01-01

    A high level of plasma low-density lipoprotein (LDL) cholesterol is considered a risk factor for atherosclerosis. Because the hepatic LDL receptor (LDLR) is essential for clearing plasma LDL cholesterol, activation of LDLR is a promising therapeutic target for patients with atherosclerotic disease. Here we demonstrated how the flavonoid kaempferol stimulated the gene expression and activity of LDLR in HepG2 cells. The kaempferol-mediated stimulation of LDLR gene expression was completely inhibited by knockdown of Sp1 gene expression. Treatment of HepG2 cells with kaempferol stimulated the recruitment of Sp1 to the promoter region of the LDLR gene, as well as the phosphorylation of Sp1 on Thr-453 and Thr-739. Moreover, these kaempferol-mediated processes were inhibited in the presence of U0126, an ERK pathway inhibitor. These results suggest that kaempferol may increase the activity of Sp1 through stimulation of Sp1 phosphorylation by ERK1/2 and subsequent induction of LDLR expression and activity. PMID:27109240

  10. Recording extracellular neural activity in the behaving monkey using a semichronic and high-density electrode system.

    PubMed

    Mendoza, Germán; Peyrache, Adrien; Gámez, Jorge; Prado, Luis; Buzsáki, György; Merchant, Hugo

    2016-08-01

    We describe a technique to semichronically record the cortical extracellular neural activity in the behaving monkey employing commercial high-density electrodes. After the design and construction of low cost microdrives that allow varying the depth of the recording locations after the implantation surgery, we recorded the extracellular unit activity from pools of neurons at different depths in the presupplementary motor cortex (pre-SMA) of a rhesus monkey trained in a tapping task. The collected data were processed to classify cells as putative pyramidal cells or interneurons on the basis of their waveform features. We also demonstrate that short time cross-correlogram occasionally yields unit pairs with high short latency (<5 ms), narrow bin (<3 ms) peaks, indicative of monosynaptic spike transmission from pre- to postsynaptic neurons. These methods have been verified extensively in rodents. Finally, we observed that the pattern of population activity was repetitive over distinct trials of the tapping task. These results show that the semichronic technique is a viable option for the large-scale parallel recording of local circuit activity at different depths in the cortex of the macaque monkey and other large species. PMID:27169505

  11. Piperine Induces Hepatic Low-Density Lipoprotein Receptor Expression through Proteolytic Activation of Sterol Regulatory Element-Binding Proteins

    PubMed Central

    Ochiai, Ayasa; Miyata, Shingo; Shimizu, Makoto; Inoue, Jun; Sato, Ryuichiro

    2015-01-01

    Elevated plasma low-density lipoprotein (LDL) cholesterol is considered as a risk factor for atherosclerosis. Because the hepatic LDL receptor (LDLR) uptakes plasma lipoproteins and lowers plasma LDL cholesterol, the activation of LDLR is a promising drug target for atherosclerosis. In the present study, we identified the naturally occurring alkaloid piperine, as an inducer of LDLR gene expression by screening the effectors of human LDLR promoter. The treatment of HepG2 cells with piperine increased LDLR expression at mRNA and protein levels and stimulated LDL uptake. Subsequent luciferase reporter gene assays revealed that the mutation of sterol regulatory element-binding protein (SREBP)-binding element abolished the piperine-mediated induction of LDLR promoter activity. Further, piperine treatments increased mRNA levels of several SREBP targets and mature forms of SREBPs. However, the piperine-mediated induction of the mature forms of SREBPs was not observed in SRD–15 cells, which lack insulin-induced gene–1 (Insig–1) and Insig–2. Finally, the knockdown of SREBPs completely abolished the piperine-meditated induction of LDLR gene expression in HepG2 cells, indicating that piperine stimulates the proteolytic activation of SREBP and subsequent induction of LDLR expression and activity. PMID:26431033

  12. The influence of vortex pinning and grain boundary structure on critical currents across grain boundaries in YBa{sub 2}Cu{sub 3}O{sub x}.

    SciTech Connect

    Miller, D. J.

    1998-10-27

    We have used studies of single grain boundaries in YBCO thin films and bulk bicrystals to study the influence of vortex pinning along a grain boundary on dissipation. The critical current density for transport across grain boundaries in thin films is typically more than an order of magnitude larger than that measured for transport across grain boundaries in bulk samples. For low disorientation angles, the difference in critical current density within the grains that form the boundary can contribute to the substantial differences in current density measured across the boundary. However, substantial differences exist in the critical current density across boundaries in thin film compared to bulk bicrystals even in the higher angle regime in which grain boundary dissipation dominates. The differences in critical current density in this regime can be understood on the basis of vortex pinning along the boundary.

  13. 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...

  14. The electronic structure of grain boundaries in Nb

    SciTech Connect

    Sowa, E.C.; Gonis, A. ); Zhang, X.G. )

    1990-11-01

    We present first-principles calculations of the electronic structure of Nb grain boundaries. These are the first such calculations for a bcc metal using the real-space multiple-scattering theory (RSMST). Local densities of states near a {Sigma}5 twist grain boundary are compared to those for bulk Nb. 5 refs., 1 fig.

  15. Charging time for dust grain on surface exposed to plasma

    NASA Astrophysics Data System (ADS)

    Sheridan, T. E.

    2013-04-01

    We consider the charging of a dust grain sitting on a surface exposed to plasma. The stochastic model of Sheridan and Hayes [Appl. Phys. Lett. 98, 091501 (2011)] is solved analytically for the charging time, which is found to be directly proportional to the square root of the electron temperature and inversely proportional to both the grain radius and plasma density.

  16. Determination of Secondary Follicle Characteristics, Density, Activity, and Hoxc13 Expression Pattern of Hexi Cashmere Goats Breed.

    PubMed

    He, Yanyu; Luo, Yuzhu; Cheng, Lixiang; Wang, Jiqing; Liu, Xiu; Shao, Bin; Cui, Yan

    2015-10-01

    This experiment was conducted to identify some aspects of secondary follicle (SF) characteristics of Hexi cashmere goats at five different growing stages in one year in order and discover the expression pattern of Hoxc13 in a SF cycling to provide morphological basis for studying the growth of cashmere. Ten cashmere goats of one-year old (5 males, 5 females) were included in this study. The density and activity of SF were observed and measured by making paraffin sections, the ultra-structural features of SF were studied under transmission electron microscopy (TEM) by making ultra-thin sections, and the expression of Hoxc13 was investigated through the immunohistochemistry method. The average diameter of SF had the smallest value in the anagen stage, and significant difference (P < 0.05) was found between the anagen stage and other stages. The density of SF increased gradually through the different growing stages, and significant difference was found between the anagen and procatagen stages (P < 0.05). With an increase in time (months), the percentage of SF activity increased, and significant difference in the percentage of SF activity was found between the telogen and anagen stages (P < 0.05). At the telogen stage, the layers of connective tissue sheath (CTS) of SF were unclear, hemidesmosomes between the outer root sheath (ORS) and basement membrane disappeared, and dead cells were found at the top of the SF. The rudiments of new SF were found in the proanagen stage, CTS was thickened, and the cells of ORS were stretched out like fingers. At the anagen stage, the structure of SF was integral, and the inner root sheath (IRS) consisted of three concentric layers (Helen, Huxley, and Cuticle layers). The cells of Huxley's layer degenerated gradually, and pseudopodia were formed on the cells of ORS in the procatagen stage. At the catagen stage, the ORS was separated from the IRS, and IRS disappeared. Huxley's layer was absent in the inactive SF while, the

  17. Temporal patterns of deer-vehicle collisions consistent with deer activity pattern and density increase but not general accident risk.

    PubMed

    Hothorn, Torsten; Müller, Jörg; Held, Leonhard; Möst, Lisa; Mysterud, Atle

    2015-08-01

    The increasing number of deer-vehicle collisions (DVCs) across Europe during recent decades poses a serious threat to human health and animal welfare and increasing costs for society. DVCs are triggered by both a human-related and a deer-related component. Mitigation requires an understanding of the processes driving temporal and spatial collision patterns. Separating human-related from deer-related processes is important for identifying potentially effective countermeasures, but this has rarely been done. We analysed two time series of 341,655 DVCs involving roe deer and 854,659 non-deer-related accidents (non-DVCs) documented between 2002 and 2011. Nonparametric smoothing and temporal parametric modelling were used to estimate annual, seasonal, weekly and diurnal patterns in DVCs, non-DVCs and adjusted DVCs. As we had access to data on both DVCs and non-DVCs, we were able to disentangle the relative role of human-related and deer-related processes contributing to the overall temporal DVC pattern. We found clear evidence that variation in DVCs was mostly driven by deer-related and not human-related activity on annual, seasonal, weekly and diurnal scales. A very clear crepuscular activity pattern with high activity after sunset and around sunrise throughout the year was identified. Early spring and the mating season between mid-July and mid-August are typically periods of high roe deer activity, and as expected we found a high number of DVC during these periods, although these patterns differed tremendously during different phases of a day. The role of human activity was mainly reflected in fewer DVCs on weekends than on weekdays. Over the ten-year study period, we estimated that DVCs increased by 25%, whereas the number of non-DVCs decreased by 10%. Increasing deer densities are the most likely driver behind this rise in DVCs. Precise estimates of DVC patterns and their relationship to deer and human activity patterns allow implementation of specific mitigation

  18. Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation

    NASA Astrophysics Data System (ADS)

    Chang, Yongqin; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

    2014-12-01

    This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects.

  19. All About the Grains Group

    MedlinePlus

    ... the Grains Group? Any food made from wheat, rice, oats, cornmeal, barley or another cereal grain is ... bulgur (cracked wheat), oatmeal, whole cornmeal, and brown rice. Refined grains have been milled, a process that ...

  20. The low density lipoprotein receptor-related protein/alpha2-macroglobulin receptor regulates cell surface plasminogen activator activity on human trophoblast cells.

    PubMed

    Zhang, J C; Sakthivel, R; Kniss, D; Graham, C H; Strickland, D K; McCrae, K R

    1998-11-27

    The low density lipoprotein receptor-related protein/alpha2-macroglobulin receptor (LRP/alpha2MR) mediates the internalization of numerous ligands, including prourokinase (pro-UK) and complexes between two-chain urokinase (tc-u-PA) and plasminogen activator inhibitor type-1 (PAI-1). It has been suggested that through its ability to internalize these ligands, LRP/alpha2MR may regulate the expression of plasminogen activator activity on cell surfaces; this hypothesis, however, has not been experimentally confirmed. To address this issue, we assessed the ability of LRP/alpha2MR to regulate plasminogen activator activity on human trophoblast cells, which express both LRP/alpha2MR and the urokinase receptor (uPAR). Trophoblasts internalized and degraded exogenous 125I-pro-UK (primarily following its conversion to tc-u-PA and incorporation into tc-u-PA.PAI complexes) in an LRP/alpha2MR-dependent manner, which was inhibited by the LRP/alpha2MR receptor-associated protein. Receptor-associated protein also caused a approximately 50% reduction in cell surface plasminogen activator activity and delayed the regeneration of unoccupied uPAR by cells on which uPAR were initially saturated with pro-UK. Identical effects were caused by anti-LRP/alpha2MR antibodies. These results demonstrate that LRP/alpha2MR promotes the expression of cell surface plasminogen activator activity on trophoblasts by facilitating the clearance of tc-u-PA.PAI complexes and regeneration of unoccupied cell surface uPAR. PMID:9822706

  1. Densities of stratospheric micrometeorites

    NASA Technical Reports Server (NTRS)

    Love, Stanley G.; Joswiak, David J.; Brownlee, Donald E.

    1994-01-01

    We have measured the densities of roughly 150 5- to 15-microns interplanetary dust particles (IDPs) harvested in the stratosphere. Care was taken to minimize selection bias in the sample population. Masses were determined using an absolute X-ray analysis technique with a transmission electron microscope, and volumes were found using scanning electron microscope imagery. Unmelted chondritic particles have densities ranging between 0.3 and 6.2 g/cu cm, averaging 2.0 g/cu cm. The low medium densities indicates appreciable porosity, suggesting primitive, uncompacted parent bodies for these particles. Porosities greater than 70% are rare. IDPs with densities above 3.5 g/cu cm usually contain large sulfide grains. We find no evidence of bimodality in the unmelted particle density distribution. Chondritic spherules (melted particles) have densities near 3.4 g/cu cm, consistent with previous results for stony spheurles culled from deep-sea sediments.

  2. [THE BECOMING IN PHYLOGENESIS OF TRANSFER IN INTERCELLULAR MEDIUM AND ACTIVE ABSORPTION OF POLYENOIC FATTY ACIDS BY CELLS SEQUENTIALLY OF HIGH DENSITY LIPOPROTEINS, LOW DENSITY LIPOPROTEINS AND HIGH DENSITY APOE-LIPOPROTEINS].

    PubMed

    Titov, V N

    2015-06-01

    After more than half-century of different conceptions, the theory of general pathology was used to substantiate that all lipoproteins are bi-layer:lipid by their structure. The main function of high density lipoproteins as of all lipoproteins is transfer of fatty acids to cells and only in second turn taking away of spirit cholesterol from cells. At the stages of phylogenesis high density lipoproteins, low density lipoproteins and very low density lipoproteins began to function in a subsequent way. The fatty acids were transferred by low density lipoproteins in polar lipids at passive absorption by cells. Later on, lipoproteins transfer fatty acids in non-polar ethers with spirits glycerin and spirit cholesterol. The cells absorb them by receptor endocytosis. The hepatocytes secret in blood palmitic, oleic, linoleic and linoleic very low density lipoproteins. The palmitic and oleic very low density lipoproteins absorb physiologically insulin-dependent cells apoE/B-100 = endocytosis. The linoleic and linoleic very low density lipoproteins after transition of polyethers cholesterol from high density lipoproteins turn into low density lipoproteins. The cells absorb them by apoB-100 = endocytosis. The formation of chylomicrons occurs in blood and hepatocytes absorb them by the way of apoB/E-48 = endocytosis. The absorption of poly-unsaturated fatty acids by cells with apoB-100 = endocytosis form sensitivity of animals to exogenous hyper spirit cholesterol and absorption of poly-unsaturated fatty acids by apoE/A-I = receptors form corresponding resistance. The ApoE in lipoproteins form cooperative ligands--apoE/B-48 for chylomicrons, apoE/B-100 for very low density lipoproteins and apoE/A-I for high density lipoproteins. The chylomicrons in blood form apoB-48 from complexes of triglycerides secreted by enterocytes. These views change conceptions of pathogenesis and prevention of atherosclerosis, metabolic syndrome and resistance to insulin whose pathogenesis is unified

  3. Circumstellar grain formation

    NASA Technical Reports Server (NTRS)

    Draine, B. T.

    1986-01-01

    Dust formation around cool giant and supergiant stars is examined in terms of grain formulation. Optical properties of small clusters, molecular physics of cluster nucleation and growth, circumstellar mass flows, and their application to alpha Ori are discussed.

  4. 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

  5. Desorption from interstellar grains

    NASA Technical Reports Server (NTRS)

    Leger, A.; Jura, M.; Omont, A.

    1985-01-01

    Different desorption mechanisms from interstellar grains are considered to resolve the conflict between the observed presence of gaseous species in molecular clouds and their expected depletion onto grains. The physics of desorption is discussed with particular reference to the process of grain heating and the specific heat of the dust material. Impulsive heating by X-rays and cosmic rays is addressed. Spot heating of the grains by cosmic rays and how this can lead to desorption of mantles from very large grains is considered. It is concluded that CO depletion on grains will be small in regions with A(V) less than five from the cloud surface and n(H) less than 10,000, in agreement with observations and in contrast to expectations from pure thermal equilibrium. Even in very dense and obscured regions and in the absence of internal ultraviolet sources, the classical evaporation of CO or N2 and O2-rich mantles by cosmic rays is important.

  6. Effects of season and host physiological state on the diversity, density, and activity of the arctic ground squirrel cecal microbiota.

    PubMed

    Stevenson, Timothy J; Duddleston, Khrystyne N; Buck, C Loren

    2014-09-01

    We examined the seasonal changes of the cecal microbiota of captive arctic ground squirrels (Urocitellus parryii) by measuring microbial diversity and composition, total bacterial density and viability, and short-chain fatty acid concentrations at four sample periods (summer, torpor, interbout arousal, and posthibernation). Abundance of Firmicutes was lower, whereas abundances of Bacteroidetes, Verrucomicrobia, and Proteobacteria were higher during torpor and interbout arousal than in summer. Bacterial densities and percentages of live bacteria were significantly higher in summer than during torpor and interbout arousal. Likewise, total short-chain fatty acid concentrations were significantly greater during summer than during torpor and interbout arousal. Concentrations of individual short-chain fatty acids varied across sample periods, with butyrate concentrations higher and acetate concentrations lower during summer than at all other sample periods. Characteristics of the gut community posthibernation were more similar to those during torpor and interbout arousal than to those during summer. However, higher abundances of the genera Bacteroides and Akkermansia occurred during posthibernation than during interbout arousal and torpor. Collectively, our results clearly demonstrate that seasonal changes in physiology associated with hibernation and activity affect the gut microbial community in the arctic ground squirrel. Importantly, similarities between the gut microbiota of arctic ground squirrels and thirteen-lined ground squirrels suggest the potential for a core microbiota during hibernation. PMID:25002417

  7. Prenatal immune activation in mice blocks the effects of environmental enrichment on exploratory behavior and microglia density.

    PubMed

    Buschert, Jens; Sakalem, Marna E; Saffari, Roja; Hohoff, Christa; Rothermundt, Matthias; Arolt, Volker; Zhang, Weiqi; Ambrée, Oliver

    2016-06-01

    Adverse environmental factors including prenatal maternal infection are capable of inducing long-lasting behavioral and neural alterations which can enhance the risk to develop schizophrenia. It is so far not clear whether supportive postnatal environments are able to modify such prenatally-induced alterations. In rodent models, environmental enrichment influences behavior and cognition, for instance by affecting endocrinologic, immunologic, and neuroplastic parameters. The current study was designed to elucidate the influence of postnatal environmental enrichment on schizophrenia-like behavioral alterations induced by prenatal polyI:C immune stimulation at gestational day 9 in mice. Adult offspring were tested for amphetamine-induced locomotion, social interaction, and problem-solving behavior as well as expression of dopamine D1 and D2 receptors and associated molecules, microglia density and adult neurogenesis. Prenatal polyI:C treatment resulted in increased dopamine sensitivity and dopamine D2 receptor expression in adult offspring which was not reversed by environmental enrichment. Prenatal immune activation prevented the effects of environmental enrichment which increased exploratory behavior and microglia density in NaCl treated mice. Problem-solving behavior as well as the number of immature neurons was affected by neither prenatal immune stimulation nor postnatal environmental enrichment. The behavioral and neural alterations that persist into adulthood could not generally be modified by environmental enrichment. This might be due to early neurodevelopmental disturbances which could not be rescued or compensated for at a later developmental stage. PMID:26776071

  8. High capacitance of coarse-grained carbide derived carbon electrodes

    NASA Astrophysics Data System (ADS)

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-02-01

    We report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. Using a titanium carbide (TiC) precursor, we synthesized 70-250 μm sized particles with high surface area and a narrow pore size distribution. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. The material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250-1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

  9. High capacitance of coarse-grained carbide derived carbon electrodes

    DOE PAGESBeta

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-01-01

    Here, we report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. We synthesized 70–250 μm sized particles with high surface area and a narrow pore size distribution, using a titanium carbide (TiC) precursor. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. Moreover, the material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250–1000 micron thick dense CDC films withmore » up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.« less

  10. High capacitance of coarse-grained carbide derived carbon electrodes

    SciTech Connect

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-01-01

    Here, we report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. We synthesized 70–250 μm sized particles with high surface area and a narrow pore size distribution, using a titanium carbide (TiC) precursor. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. Moreover, the material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250–1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

  11. CYLD, a deubiquitinase specific for lysine63-linked polyubiquitins, accumulates at the postsynaptic density in an activity-dependent manner

    SciTech Connect

    Dosemeci, Ayse; Thein, Soe; Yang, Yijung; Reese, Thomas S.; Tao-Cheng, Jung-Hwa

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer CYLD is a deubiquitinase specific for lysine63-linked polyubiquitins. Black-Right-Pointing-Pointer Presence of CYLD in PSDs is established by biochemistry and immunoEM. Black-Right-Pointing-Pointer CYLD accumulates on PSDs upon depolarization of neurons. Black-Right-Pointing-Pointer Accumulation of CYLD at PSDs may regulate trafficking/degradation of synaptic proteins. -- Abstract: Polyubiquitin chains on proteins flag them for distinct fates depending on the type of polyubiquitin linkage. While lysine48-linked polyubiquitination directs proteins to proteasomal degradation, lysine63-linked polyubiquitination promotes different protein trafficking and is involved in autophagy. Here we show that postsynaptic density (PSD) fractions from adult rat brain contain deubiquitinase activity that targets both lysine48 and lysine63-linked polyubiquitins. Comparison of PSD fractions with parent subcellular fractions by Western immunoblotting reveals that CYLD, a deubiquitinase specific for lysine63-linked polyubiquitins, is highly enriched in the PSD fraction. Electron microscopic examination of hippocampal neurons in culture under basal conditions shows immunogold label for CYLD at the PSD complex in approximately one in four synapses. Following depolarization by exposure to high K+, the proportion of CYLD-labeled PSDs as well as the labeling intensity of CYLD at the PSD increased by more than eighty percent, indicating that neuronal activity promotes accumulation of CYLD at the PSD. An increase in postsynaptic CYLD following activity would promote removal of lysine63-polyubiquitins from PSD proteins and thus could regulate their trafficking and prevent their autophagic degradation.

  12. Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model

    SciTech Connect

    Fitzgerald, J.E.; Robinson, R.L.; Gasem, K.A.M.

    2006-11-07

    The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO{sub 2} sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and three water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO{sub 2} on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO{sub 2} on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties.

  13. Density-functional calculations of prefactors and activation energies for H diffusion in BaZrO3

    NASA Astrophysics Data System (ADS)

    Sundell, Per G.; Björketun, Mårten E.; Wahnström, Göran

    2007-09-01

    Density-functional calculations are used to investigate hydrogen diffusion in the solid-state proton conductor BaZrO3 . Activation energies and prefactors for the rate of proton transfer and reorientation are evaluated for a defect-free region of this simple cubic perovskite-structured oxide. Both semiclassical over-barrier jumps and phonon-assisted tunneling transitions between sites are considered. It is found that the classical barriers for the elementary transfer and reorientation steps are both of the order of 0.2eV . The quantum-mechanical zero-point motion effects are found to be sizable, to effectively reduce the barrier heights, and to make the prefactors similar for the transfer and reorientation steps. The Flynn-Stoneham model [Phys. Rev. B 1, 3966 (1970)] of phonon-assisted tunneling yields an activation energy of around 0.2eV and a very small prefactor for proton transfer, whereas the corresponding adiabatic model gives a similar activation energy but a much larger prefactor. It is suggested that the effect of other defects such as dopants has to be included for a proper description of hydrogen diffusion in this material.

  14. Increased expression of low density granulocytes in juvenile-onset systemic lupus erythematosus patients correlates with disease activity.

    PubMed

    Midgley, A; Beresford, M W

    2016-04-01

    Neutrophils are implicated in a wide range of non-infectious inflammatory conditions. A subset of neutrophils in the peripheral circulation of systemic lupus erythematosus (SLE) patients has been described and termed low density granulocytes (LDGs). This study investigates the expression of LDG in juvenile-onset SLE (JSLE) patients compared to controls, and any correlations with disease activity.Neutrophils and LDGs were isolated from JSLE (n = 13) and paediatric non-inflammatory control patients (n = 12). Cell populations were assessed and compared using flow cytometry and morphological analysis. Standard clinical data, which included disease activity markers/scores, were collected for each patient.Significantly increased LDG expression (%mean ± SEM, range) was observed in JSLE patients (10.4 ± 3.26, 3.41-36.3) compared to controls (2.4 ± 0.44, 0.36-5.27; p = 0.005). A statistically significant positive correlation was observed between LDG expression and the British Isles Lupus Activity Group (correlation coefficient 0.685; p = 0.010) and SLE Disease Activity Index (correlation coefficient 0.567; p = 0.043) and the biomarker of dsDNA-antibodies (correlation coefficient 0.590; p = 0.043).Here we observe increased expression in LDGs in JSLE patients, which correlate with dsDNA antibody concentration and scores of disease activity. These correlations indicate that the increased LDG expression observed in this study may have a potential role in the pathogenesis of JSLE, and may be a useful biomarker. PMID:26453665

  15. Synthesis, Density Functional Theory (DFT), Urease Inhibition and Antimicrobial Activities of 5-Aryl Thiophenes Bearing Sulphonylacetamide Moieties.

    PubMed

    Noreen, Mnaza; Rasool, Nasir; Gull, Yasmeen; Zubair, Muhammad; Mahmood, Tariq; Ayub, Khurshid; Nasim, Faiz-Ul-Hassan; Yaqoob, Asma; Zia-Ul-Haq, Muhammad; de Feo, Vincenzo

    2015-01-01

    A variety of novel 5-aryl thiophenes 4a-g containing sulphonylacetamide (sulfacetamide) groups were synthesized in appreciable yields via Pd[0] Suzuki cross coupling reactions. The structures of these newly synthesized compounds were determined using spectral data and elemental analysis. Density functional theory (DFT) studies were performed using the B3LYP/6-31G (d, p) basis set to gain insight into their structural properties. Frontier molecular orbital (FMOs) analysis of all compounds 4a-g was computed at the same level of theory to get an idea about their kinetic stability. The molecular electrostatic potential (MEP) mapping over the entire stabilized geometries of the molecules indicated the reactive sites. First hyperpolarizability analysis (nonlinear optical response) were simulated at the B3LYP/6-31G (d, p) level of theory as well. The compounds were further evaluated for their promising antibacterial and anti-urease activities. In this case, the antibacterial activities were estimated by the agar well diffusion method, whereas the anti-urease activities of these compounds were determined using the indophenol method by quantifying the evolved ammonia produced. The results revealed that all the sulfacetamide derivatives displayed antibacterial activity against Bacillus subtiles, Escherichia coli, Staphylococcus aureus, Shigella dysenteriae, Salmonella typhae, Pseudomonas aeruginosa at various concentrations. Furthermore, the compound 4g N-((5-(4-chlorophenyl)thiophen-2-yl)sulfonyl) acetamide showed excellent urease inhibition with percentage inhibition activity ~46.23 ± 0.11 at 15 µg/mL with IC50 17.1 µg/mL. Moreover, some other compounds 4a-f also exhibited very good inhibition against urease enzyme. PMID:26556326

  16. Oxidized High-Density Lipoprotein Impairs Endothelial Progenitor Cells' Function by Activation of CD36-MAPK-TSP-1 Pathways

    PubMed Central

    Wu, Jianxiang; He, Zhiqing; Gao, Xiang; Wu, Feng; Ding, Ru; Ren, Yusheng; Jiang, Qijun; Fan, Min

    2015-01-01

    Abstract Aims: High-density lipoprotein (HDL) levels inversely correlate with cardiovascular events due to the protective effects on vascular wall and stem cells, which are susceptible to oxidative modifications and then lead to potential pro-atherosclerotic effects. We proposed that oxidized HDL (ox-HDL) might lead to endothelial progenitor cells (EPCs) dysfunction and investigated underlying mechanisms. Results: ox-HDL was shown to increase apoptosis and intracellular reactive oxygen species levels, but to reduce migration, angiogenesis, and cholesterol efflux of EPCs in a dose-dependent manner. p38 mitogen-activated protein kinase (MAPK) and NF-κB were activated after ox-HDL stimulation, which also upregulated thrombospondin-1 (TSP-1) expression without affecting vascular endothelial growth factor. Effects caused by ox-HDL could be significantly attenuated by pretreatment with short hairpin RNA-mediated CD36 knockdown or probucol. Data of in vivo experiments and the inverse correlation of ox-HDL and circulating EPC numbers among patients with coronary artery diseases (CAD) or CAD and type 2 diabetes also supported it. Meanwhile, HDL separated from such patients could significantly increase cultured EPC's caspase 3 activity, further supporting our proposal. Innovation: This is the most complete study to date of how ox-HDL would impair EPCs function, which was involved with activation of CD36-p38 MAPK-TSP-1 pathways and proved by not only the inverse relationship between ox-HDL and circulating EPCs in clinic but also pro-apoptotic effects of HDL separated from patients' serum. Conclusion: Activation of CD36-p38 MAPK-TSP-1 pathways contributes to the pathological effects of ox-HDL on EPCs' dysfunction, which might be one of the potential etiological factors responsible for the disturbed neovascularization in chronic ischemic disease. Antioxid. Redox Signal. 22, 308–324. PMID:25313537

  17. A Pilot Study: Dietary Energy Density is Similar between Active Women with and without Exercise-Associated Menstrual Dysfunction

    PubMed Central

    Hand, Taryn M.; Howe, Stephanie; Cialdella-Kam, Lynn; Hoffman, Charlotte P. Guebels; Manore, Melinda

    2016-01-01

    Low energy availability (EA) (e.g., insufficient energy intake (EI) to match energy needs, including exercise energy expenditure) has been identified as a primary contributor to exercise-associated menstrual dysfunction (ExMD) in active women. For health reasons, active women may self-select diets lower in energy density (ED, kcal/g), which can inadvertently contribute to inadequate EI. Using data from two studies, we compared the ED of active women with ExMD (n = 9; 24 ± 6 years) to eumenorrheic (EU) active controls (EU: n = 18, 27 ± 6 years). ED was calculated from 6 to 7 days weighted food records using two methods: with/without beverages. ANOVA and Wilcoxon Rank-Sum were used to test group differences. ED was not different between groups, but there was a trend toward a lower median ED (10%) (p = 0.049 unadjusted; p = 0.098 adjusted) in the ExMD-group (Method 1—all beverages: ExMD = 1.01 kcal/g (range = 0.52–1.41), EU = 1.22 kcal/g (range = 0.72–1.72); Method 2—without beverages: ExMD = 1.51 kcal/g (range = 1.26–2.06), EU = 1.69 kcal/g (range = 1.42–2.54)). This lower ED represents a 9% decrease (~219 kcal/day) in EI (ExMD = 2237 ± 378 kcal/day; EU = 2456 ± 470 kcal/day; p > 0.05). EI and macro/micronutrient intakes were similar for groups. In the ExMD-group, low ED could contribute to lower EI and EA. Future research should examine the interaction of ED and exercise on appetite, EI, and EA in active women, especially those with ExMD. PMID:27104560

  18. Can we define an asymptotic value for the ice active surface site density for heterogeneous ice nucleation?

    NASA Astrophysics Data System (ADS)

    Niedermeier, Dennis; Augustin-Bauditz, Stefanie; Hartmann, Susan; Wex, Heike; Ignatius, Karoliina; Stratmann, Frank

    2015-05-01

    The immersion freezing behavior of droplets containing size-segregated, monodisperse feldspar particles was investigated. For all particle sizes investigated, a leveling off of the frozen droplet fraction was observed reaching a plateau within the heterogeneous freezing temperature regime (T >- 38°C). The frozen fraction in the plateau region was proportional to the particle surface area. Based on these findings, an asymptotic value for ice active surface site density ns, which we named ns⋆, could be determined for the investigated feldspar sample. The comparison of these results with those of other studies not only elucidates the general feasibility of determining such an asymptotic value but also shows that the value of ns⋆ strongly depends on the method of the particle surface area determination. However, such an asymptotic value might be an important input parameter for atmospheric modeling applications. At least it shows that care should be taken when ns is extrapolated to lower or higher temperature.

  19. The activation energy of oxidative thermal degradation of radiation- and peroxide-crosslinked low-density polyethylene

    SciTech Connect

    Matusevich, Yu.I.; Butovskaya, G.V.; Krul, L.P.

    1994-11-01

    The parameters of thermal degradation (kinetic order of the reaction, preexponential factor logA, and activation energy E{sub d}) of low-density polyethylene crosslinked by radiation or by dicumyl peroxide were determined from thermogravimetric data processed using the complementarity-based method of {open_quotes}supercorrelations.{close_quotes} The degradation of the polymer was found to obey a first-order rate equation. At mass losses of 10-20%, the parameters logA and E{sub d} were shown to decrease with an increasing degree of crosslinking because of the evolution of low-molecular radiolysis products and the low probability of chain radical processes. In the region of more intense destruction, E{sub d} (as well as logA) increases because the degradation of crosslinked polymer macromolecules requires greater energy consumption.

  20. Analytical gradients of the state-average complete active space self-consistent field method with density fitting

    NASA Astrophysics Data System (ADS)

    Delcey, Mickaël G.; Pedersen, Thomas Bondo; Aquilante, Francesco; Lindh, Roland

    2015-07-01

    An efficient implementation of the state-averaged complete active space self-consistent field (SA-CASSCF) gradients employing density fitting (DF) is presented. The DF allows a reduction both in scaling and prefactors of the different steps involved. The performance of the algorithm is demonstrated on a set of molecules ranging up to an iron-Heme b complex which with its 79 atoms and 811 basis functions is to our knowledge the largest SA-CASSCF gradient computed. For smaller systems where the conventional code could still be used as a reference, both the linear response calculation and the gradient formation showed a clear timing reduction and the overall cost of a geometry optimization is typically reduced by more than one order of magnitude while the accuracy loss is negligible.

  1. Analytical gradients of the state-average complete active space self-consistent field method with density fitting

    SciTech Connect

    Delcey, Mickaël G.; Pedersen, Thomas Bondo; Aquilante, Francesco; Lindh, Roland

    2015-07-28

    An efficient implementation of the state-averaged complete active space self-consistent field (SA-CASSCF) gradients employing density fitting (DF) is presented. The DF allows a reduction both in scaling and prefactors of the different steps involved. The performance of the algorithm is demonstrated on a set of molecules ranging up to an iron-Heme b complex which with its 79 atoms and 811 basis functions is to our knowledge the largest SA-CASSCF gradient computed. For smaller systems where the conventional code could still be used as a reference, both the linear response calculation and the gradient formation showed a clear timing reduction and the overall cost of a geometry optimization is typically reduced by more than one order of magnitude while the accuracy loss is negligible.

  2. Elevated hepatic lipase activity and low levels of high density lipoprotein in a normotriglyceridemic, nonobese Turkish population.

    PubMed

    Bersot, T P; Vega, G L; Grundy, S M; Palaoglu, K E; Atagündüz, P; Ozbayrakçi, S; Gökdemir, O; Mahley, R W

    1999-03-01

    Low levels of high density lipoprotein cholesterol (HDL-C) are associated with increased risk of coronary heart disease and, in the United States, are often associated with hypertriglyceridemia and obesity. In Turkey, low HDL-C levels are highly prevalent, 53% of men and 26% of women having HDL-C levels <35 mg/dl, in the absence of hypertriglyceridemia and obesity. In this study to investigate the cause of low HDL-C levels in Turks, various factors affecting HDL metabolism were assessed in normotriglyceridemic Turkish men and women living in Istanbul and in non-Turkish men and women living in San Francisco. Turkish men and women had significantly lower HDL-C levels than the San Francisco men and women, as well as markedly lower apolipoprotein A-I levels (25 and 39 mg/dl lower, respectively). In both Turkish and non-Turkish subjects, the mean body mass index was <27 kg/m2, the mean triglyceride level was <120 mg/dl, and the mean total cholesterol was 170-180 mg/dl. The mean hepatic triglyceride lipase activity was 21% and 31% higher in Turkish men and women, respectively, than in non-Turkish men and women, and remained higher even after subjects with a body mass index >50th percentile for men and women in the United States were excluded from the analysis. As no dietary or behavioral factors have been identified in the Turkish population that account for increased hepatic triglyceride lipase activity, the elevation most likely has a genetic basis. high density lipoprotein in a normotriglyceridemic, nonobese Turkish population. PMID:10064731

  3. Rates of Space Weathering in Lunar Regolith Grains

    NASA Technical Reports Server (NTRS)

    Zhang, S.; Keller, L. P.

    2012-01-01

    While the processes and products of lunar space weathering are reasonably well-studied, their accumulation rates in lunar soils are poorly constrained. Previously, we showed that the thickness of solar wind irradiated rims on soil grains is a smooth function of their solar flare particle track density, whereas the thickness of vapor-deposited rims was largely independent of track density [1]. Here, we have extended these preliminary results with data on additional grains from other mature soils.

  4. A QSAR study of radical scavenging antioxidant activity of a series of flavonoids using DFT based quantum chemical descriptors--the importance of group frontier electron density.

    PubMed

    Sarkar, Ananda; Middya, Tapas Ranjan; Jana, Atish Dipnakar

    2012-06-01

    In a pursuit of electronic level understanding of the antioxidant activity of a series of flavonoids, quantitative structure-activity relationship (QSAR) studies have been carried out using density functional theory (DFT) based quantum chemical descriptors. The best QSAR model have been selected for which the computed square correlation coefficient r(2) = 0.937 and cross-validated squared correlation coefficient q(2) =0.916. The QSAR model indicates that hardness (η), group electrophilic frontier electron density (F(E)(A)) and group philicity (ω(B)(+)) of individual molecules are responsible for in vitro biological activity. To the best our knowledge, the group electrophilic frontier electron density (F(E)(A)) has been used for the first time to explain the radical scavenging activity (RSA) of flavonoids. The excellent correlation between the RSA and the above mentioned DFT based descriptors lead us to predict new antioxidants having very good antioxidant activity. PMID:22080306

  5. 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

    measured by cryogenic SEM and image analysis techniques. We found clear evidence of grain growth and a significantly T-dependent variation of grain size distributions. The observations allow us to calibrate values for the grain size exponent n and the activation energy Q as used in conventional grain growth laws. We simulated grain growth of ice based on the microphysical model of Kellermann Slotemaker (2006). This model takes into account full grain size distributions and allows grain boundary migration driven by different acting forces. We will show the importance of these driving forces for grain growth and deformation in polycrystalline ice aggregates. References Kellermann Slotemaker, A., 2006. Dynamic recrystallization and grain growth in olivine rocks. PhD Thesis, Utrecht University, Utrecht, 187 pp. Stern, L., 1997. Grain-size-inducedweakening of H2O ices I and II and associated anisotropic recrystallization. Journal of Geophysical Research, 102 (B3): 5313-5325.

  6. MODELING NANOCRYSTALLINE GRAIN GROWTH DURING THE PULSED ELECTRODEPOSITION OF GOLD-COPPER

    SciTech Connect

    Jankowski, A F

    2005-10-27

    The process parameters of current density, pulse duration, and cell potential affect both the structure and composition of electrodeposits. The mechanism for nucleation and growth as determined from current transients yield relationships for nucleus density and nucleation rate. To develop an understanding of the role of the process parameters on grain size, as a design structural parameter to control strength for example, a formulation is presented to model the affects of the deposition energy on grain size and morphology. An activation energy for the deposition process is modeled that reveals different growth mechanisms, wherein nucleation and diffusion effects are each dominant as dependent upon pulse duration. A diffusion coefficient common for each of the pulsed growth modes demarcates an observed transition in growth from smooth to rough surfaces.

  7. 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.

  8. Elucidating the mechanism and active site of the cyclohexanol dehydrogenation on copper-based catalysts: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Wang, Ziyun; Liu, Xinyi; Rooney, D. W.; Hu, P.

    2015-10-01

    The dehydrogenation of cyclohexanol to cyclohexanone is very important in the manufacture of nylon. Copper-based catalysts are the most popular catalysts for this reaction, and on these catalysts the reaction mechanism and active site are in debate. In order to elucidate the mechanism and active site of the cyclohexanol dehydrogenation on copper-based catalysts, density functional theory with dispersion corrections were performed on up to six facets of copper in two different oxidation states: monovalent copper and metallic copper. By calculating the surface energies of these facets, Cu(111) and Cu2O(111) were found to be the most stable facets for metallic copper and for monovalent copper, respectively. On these two facets, all the possible elementary steps in the dehydrogenation pathway of cyclohexanol were calculated, including the adsorption, dehydrogenation, hydrogen coupling and desorption. Two different reaction pathways for dehydrogenation were considered on both surfaces. It was revealed that the dehydrogenation mechanisms are different on these two surfaces: on Cu(111) the hydrogen belonging to the hydroxyl is removed first, then the hydrogen belonging to the carbon is subtracted, while on Cu2O(111) the hydrogen belonging to the carbon is removed followed by the subtraction of the hydrogen in the hydroxyl group. Furthermore, by comparing the energy profiles of these two surfaces, Cu2O(111) was found to be more active for cyclohexanol dehydrogenation than Cu(111). In addition, we found that the coordinatively unsaturated copper sites on Cu2O(111) are the reaction sites for all the steps. Therefore, the coordinatively unsaturated copper site on Cu2O(111) is likely to be the active site for cyclohexanol dehydrogenation on the copper-based catalysts.

  9. Film grain synthesis and its application to re-graining

    NASA Astrophysics Data System (ADS)

    Schallauer, Peter; Mörzinger, Roland

    2006-01-01

    Digital film restoration and special effects compositing require more and more automatic procedures for movie regraining. Missing or inhomogeneous grain decreases perceived quality. For the purpose of grain synthesis an existing texture synthesis algorithm has been evaluated and optimized. We show that this algorithm can produce synthetic grain which is perceptually similar to a given grain template, which has high spatial and temporal variation and which can be applied to multi-spectral images. Furthermore a re-grain application framework is proposed, which synthesises based on an input grain template artificial grain and composites this together with the original image content. Due to its modular approach this framework supports manual as well as automatic re-graining applications. Two example applications are presented, one for re-graining an entire movie and one for fully automatic re-graining of image regions produced by restoration algorithms. Low computational cost of the proposed algorithms allows application in industrial grade software.

  10. 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.

  11. Microwave sintering of nanophase ceramics without concomitant grain growth

    DOEpatents

    Eastman, Jeffrey A.; Sickafus, Kurt E.; Katz, Joel D.

    1993-01-01

    A method of sintering nanocrystalline material is disclosed wherein the nanocrystalline material is microwaved to heat the material to a temperature less than about 70% of the melting point of the nanocrystalline material expressed in degrees K. This method produces sintered nanocrystalline material having a density greater than about 95% of theoretical and an average grain size not more than about 3 times the average grain size of the nanocrystalline material before sintering. Rutile TiO.sub.2 as well as various other ceramics have been prepared. Grain growth of as little as 1.67 times has resulted with densities of about 90% of theoretical.

  12. A New Route of Fucoidan Immobilization on Low Density Polyethylene and Its Blood Compatibility and Anticoagulation Activity

    PubMed Central

    Ozaltin, Kadir; Lehocký, Marián; Humpolíček, Petr; Pelková, Jana; Sáha, Petr

    2016-01-01

    Beside biomaterials’ bulk properties, their surface properties are equally important to control interfacial biocompatibility. However, due to the inadequate interaction with tissue, they may cause foreign body reaction. Moreover, surface induced thrombosis can occur when biomaterials are used for blood containing applications. Surface modification of the biomaterials can bring enhanced surface properties in biomedical applications. Sulfated polysaccharide coatings can be used to avoid surface induced thrombosis which may cause vascular occlusion (blocking the blood flow by blood clot), which results in serious health problems. Naturally occurring heparin is one of the sulfated polysaccharides most commonly used as an anticoagulant, but its long term usage causes hemorrhage. Marine sourced sulfated polysaccharide fucoidan is an alternative anticoagulant without the hemorrhage drawback. Heparin and fucoidan immobilization onto a low density polyethylene surface after functionalization by plasma has been studied. Surface energy was demonstrated by water contact angle test and chemical characterizations were carried out by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Surface morphology was monitored by scanning electron microscope and atomic force microscope. Finally, their anticoagulation activity was examined for prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin time (TT). PMID:27294915

  13. A New Route of Fucoidan Immobilization on Low Density Polyethylene and Its Blood Compatibility and Anticoagulation Activity.

    PubMed

    Ozaltin, Kadir; Lehocký, Marián; Humpolíček, Petr; Pelková, Jana; Sáha, Petr

    2016-01-01

    Beside biomaterials' bulk properties, their surface properties are equally important to control interfacial biocompatibility. However, due to the inadequate interaction with tissue, they may cause foreign body reaction. Moreover, surface induced thrombosis can occur when biomaterials are used for blood containing applications. Surface modification of the biomaterials can bring enhanced surface properties in biomedical applications. Sulfated polysaccharide coatings can be used to avoid surface induced thrombosis which may cause vascular occlusion (blocking the blood flow by blood clot), which results in serious health problems. Naturally occurring heparin is one of the sulfated polysaccharides most commonly used as an anticoagulant, but its long term usage causes hemorrhage. Marine sourced sulfated polysaccharide fucoidan is an alternative anticoagulant without the hemorrhage drawback. Heparin and fucoidan immobilization onto a low density polyethylene surface after functionalization by plasma has been studied. Surface energy was demonstrated by water contact angle test and chemical characterizations were carried out by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Surface morphology was monitored by scanning electron microscope and atomic force microscope. Finally, their anticoagulation activity was examined for prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin time (TT). PMID:27294915

  14. Low density lipoprotein for cytotoxic drug targeting: improved activity of elliptinium derivative against B16 melanoma in mice.

    PubMed Central

    Samadi-Baboli, M.; Favre, G.; Canal, P.; Soula, G.

    1993-01-01

    Significant low density lipoprotein (LDL) uptake by tumour cells led to the use of LDL as a discriminatory vehicle for the delivery of cytotoxic drugs. In the current study, the lipophilic elliptinium derivative, elliptinium-oleate (OL-NME), was incorporated into LDL to reach an incorporation level of 400 molecules per LDL particle. The OL-NME-LDL complex showed cytotoxic effects on normal human fibroblasts while the cytotoxicity was not observed on receptor-defective human fibroblasts, indicating the ability of the complex to be preferentially metabolised by the LDL receptor. In vivo metabolism of the complex was related to the LDL receptor pathway. The metabolic clearance was the same for native LDL (17.1 ml h-1) and OL-NME-LDL complex (16.2 ml h-1). LDL incorporated OL-NME enhanced the anti-tumour activity against murine B16 melanoma model; this resulted from increased efficacy for OL-NME-LDL at doses equal to free 9-OH-NME (157 vs 76 of Increase Life Span (ILS) (%) values after intraperitoneal (i.p.) drug injection on i.p. implanted tumour model and 45 vs -2 ILS (%) values after intravenous drug injection on subcutaneous implanted tumour model). These data suggest that LDL improves the potency of lipophilic cytotoxic drugs against tumours that express LDL receptor activity. PMID:8347487

  15. Amodal brain activation and functional connectivity in response to high energy-density food cues in obesity

    PubMed Central

    Carnell, Susan; Benson, Leora; Pantazatos, Spiro P.; Hirsch, Joy; Geliebter, Allan

    2014-01-01

    Objective The obesogenic environment is pervasive, yet only some people become obese. We aimed to investigate whether obese individuals show differential neural responses to visual and auditory food cues, independent of cue modality. Design and Methods Obese (BMI 29;-41, n=10) and lean (BMI 20-24, n=10) females underwent fMRI scanning during presentation of auditory (spoken word) and visual (photograph) cues representing high energy-density [ED] and low-ED foods. We examined the effect of obesity on whole brain activation, and on functional connectivity with the midbrain/VTA. Results Obese compared with lean women showed greater modality-independent activation of the midbrain/VTA and putamen in response to high-ED (vs. low-ED) cues, as well as relatively greater functional connectivity between the midbrain/VTA and cerebellum (p<0.05 corrected). Conclusions Heightened modality-independent responses to food cues within the midbrain/VTA and putamen, and altered functional connectivity between the midbrain/VTA and cerebellum, could contribute to excessive food intake in obese individuals. PMID:25098957

  16. Magnetospheric Consequences of Charged Ice Grains from the Enceladus Plume

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Hill, T. W.

    2014-12-01

    Based on Cassini's multiple instrument observations, we have studied the size distributions, densities, dynamics and currents of the ice grains from the Enceladus plume (Dong et al., 2014, submitted to JGR). Due to the charged grains' large gyroradii (>> RE), they carry most of the negative charge away from the picked-up ion flow, which leads to a current system different from the ion pick-up and Birkeland current system. We will study the grain and ion currents based on their motion, develop a self-consistent current system near Enceladus, and estimate the consequent electromagnetic perturbations. Comparing the modeled magnetic perturbations with the MAG data may determine the magnitude of the total grain current, which in turn will give constraints on the grain charge density to compare with RPWS-LP plasma data in the plume.

  17. Can we define an asymptotic value for the ice active surface site density for heterogeneous ice nucleation?

    NASA Astrophysics Data System (ADS)

    Niedermeier, Dennis; Augustin-Bauditz, Stefanie; Hartmann, Susan; Wex, Heike; Ignatius, Karoliina; Stratmann, Frank

    2015-04-01

    The formation of ice in atmospheric clouds has a substantial influence on the radiative properties of clouds as well as on the formation of precipitation. Therefore much effort has been made to understand and quantify the major ice formation processes in clouds. Immersion freezing has been suggested to be a dominant primary ice formation process in low and mid-level clouds (mixed-phase cloud conditions). It also has been shown that mineral dust particles are the most abundant ice nucleating particles in the atmosphere and thus may play an important role for atmospheric ice nucleation (Murray et al., 2012). Additionally, biological particles like bacteria and pollen are suggested to be potentially involved in atmospheric ice formation, at least on a regional scale (Murray et al., 2012). In recent studies for biological particles (SNOMAX and birch pollen), it has been demonstrated that freezing is induced by ice nucleating macromolecules and that an asymptotic value for the mass density of these ice nucleating macromolecules can be determined (Hartmann et al., 2013; Augustin et al., 2013, Wex et al., 2014). The question arises whether such an asymptotic value can also be determined for the ice active surface site density ns, a parameter which is commonly used to describe the ice nucleation activity of e.g., mineral dust. Such an asymptotic value for ns could be an important input parameter for atmospheric modeling applications. In the presented study, we therefore investigated the immersion freezing behavior of droplets containing size-segregated, monodisperse feldspar particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). For all particle sizes considered in the experiments, we observed a leveling off of the frozen droplet fraction reaching a plateau within the heterogeneous freezing temperature regime (T > -38°C) which was proportional to the particle surface area. Based on these findings, we could determine an asymptotic value for the ice

  18. 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

  19. Grain nucleation and growth during phase transformations.

    PubMed

    Offerman, S E; van Dijk, N H; Sietsma, J; Grigull, S; Lauridsen, E M; Margulies, L; Poulsen, H F; Rekveldt, M Th; van der Zwaag, S

    2002-11-01

    The mechanical properties of polycrystalline materials are largely determined by the kinetics of the phase transformations during the production process. Progress in x-ray diffraction instrumentation at synchrotron sources has created an opportunity to study the transformation kinetics at the level of individual grains. Our measurements show that the activation energy for grain nucleation is at least two orders of magnitude smaller than that predicted by thermodynamic models. The observed growth curves of the newly formed grains confirm the parabolic growth model but also show three fundamentally different types of growth. Insight into the grain nucleation and growth mechanisms during phase transformations contributes to the development of materials with optimal mechanical properties. PMID:12411699

  20. 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.

  1. 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.

  2. [Effects of cultivation patterns on the radiation use and grain yield of winter wheat].

    PubMed

    Wang, Yue-chao; Li, Chuan-xing; Dai, Xing-long; Zhou, Xiao-yan; Zhang, Yu; Li, Hua-ying; He, Ming-rong

    2015-09-01

    Taking winter wheat cultivar 'Tainong 18' as test material, this paper set three treatments, local farmer's traditional cultivation pattern (FP), super high yield pattern (SH) and high yield high efficiency pattern ( HH) to investigate the effects of cultivation patterns on the intercepted photosynthetically active radiation (IPAR), PAR use efficiency (RUE), dry matter (DM) accumulation, harvest index (HI), grain yield and fertilizers' partial factor productivity (PFP) in 2012-2013. The results showed that IPAR, RUE and DM accumulation of the total growth stage and grain yield under SH pattern were significantly higher than those under FP pattern. IPAR of the total growth stage under HH pattern was lower than that under FP pattern, but RUE, DM accumulation and HI were significantly higher than that under FP pattern, so grain yield was higher than that under FP pattern. The grain yields under HH pattern were respectively decreased by 3.8% and 2.8% under high and low fertility levels compared that under SH pattern, while the PFP of N, P and K under HH pattern were averagely 26.4%, 68.5% and 92.6% higher than those under SH pattern, respectively. In conclusion, HH pattern, with the characteristics of 'reducing fertilizer', 'increasing planting density' and 'delaying sowing date', was the recommended cultivation pattern under the condition similar to this experiment balancing the grain yield, radiation use and fertilizer use. PMID:26785552

  3. The Short-term Relationship of Ionospheric Electron Density With Solar Irradiance and Geomagnetic Activity in Daily Observations

    NASA Astrophysics Data System (ADS)

    Wang, X.; Sun, Q.; Eastes, R.; Bailey, S.; Reinisch, B.; Valladares, C.; Woods, T.

    2006-12-01

    The short-term relationship (~ 27-day and less) between equatorial ionospheric electron density, solar irradiance and geomagnetic activity in daily observations has been studied. Hourly averages of the Total Electron Content (TEC) and foF2 are used as measures of electron content at local times of 700-800 LT, 1200- 1300 LT and 1700-1800 LT from 1998 to 1999. Hourly measurements of Dst and daily measurements (6-19 nm) of the solar soft X-ray irradiances from the SNOE satellite provide the geomagnetic activity and solar irradiance information. These data are decomposed into components at ~3-day, ~9-day and ~27-day scales using a 3-band wavelet. This 3-band wavelet allows better isolation of the 27 day variations than the 2-band wavelets available in commercial software packages. At each scale, correlations of ionospheric electron content with solar irradiance and Dst are calculated. The ionosphere has the highest correlation with solar irradiance at the~27-day scales, where the correlation with TEC is 0.8. At ~3-day and ~9-day scales, the ionosphere has a more significant correlation with geomagnetic activity than with solar irradiance. At ~3-day scales, TEC has a correlation of 0.4 with Dst. With both solar irradiances and Dst, and at all three time scales, TEC has higher correlations than foF2. The correlations also change with local time. The correlations with TEC increase from morning to afternoon, when either using solar irradiances or Dst, while the correlations with foF2 do not change significantly or even decrease from morning to afternoon.

  4. Nanoscale abnormal grain growth in (001) epitaxial ceria

    SciTech Connect

    Solovyov, Vyacheslav F.; Develos-Bagarinao, Katherine; Nykypanchuk, Dmytro

    2009-09-01

    X-ray reciprocal-space mapping and atomic force microscopy (AFM) are used to study kinetics and mechanisms of lateral grain growth in epitaxial (001) ceria (CeO{sub 2}) deposited by pulsed laser deposition on (001) yttria-stabilized zirconia (YSZ) and (12 lowbar 10) (r-cut) sapphire. Rate and character of the grain growth during postannealing at 1050 deg. C are found to be strongly dependent on the type of the epitaxial substrate. Films deposited on YSZ exhibit signatures of normal grain growth, which stagnated after the lateral grain size reaches 40 nm, consistent with the grain-boundary pinning by the thermal grooving. In contrast, when r-cut sapphire substrate was used, abnormal (secondary) grain growth is observed. A small population of grains grow to well over 100 nm consuming smaller, <10 nm, grains, thus forming well-defined >100 nm large (001) terminations and rendering the sample single-crystalline quality. The grain growth is accompanied by reduction in lateral rms strain, resulting in a universal grain size--rms strain dependence. Analysis of the AFM and x-ray diffraction data leads to the conclusion that bimodal initial grain population consisting of grains with very different sizes is responsible for initiation of the abnormal growth in (001) CeO{sub 2} films on r-cut sapphire. Due to different surface chemistry, when a YSZ substrate is used, the initial grain distribution is monomodal, therefore only normal growth is active. We demonstrate that a 2.2 deg. miscut of the sapphire substrate eliminates the large-grain population, thus suppressing abnormal grain growth. It is concluded that utilization of abnormal grain growth is a promising way for synthesis of large (001) ceria terminations.

  5. 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.

  6. 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.

  7. A Dastardly Density Deed.

    ERIC Educational Resources Information Center

    Shaw, Mike

    2003-01-01

    Integrates story telling into a science activity on the density of liquids in order to increase student interest. Shows the relationship between mass and volume ratio and how they determine density. Includes teacher notes. (YDS)

  8. Effect of Heating Rate on Densification and Grain Growth During Spark Plasma Sintering of 93W-5.6Ni-1.4Fe Heavy Alloys

    NASA Astrophysics Data System (ADS)

    Hu, Ke; Li, Xiaoqiang; Qu, Shengguan; Li, Yuanyuan

    2013-09-01

    Blended 93W-5.6Ni-1.4Fe powders were sintered via the spark plasma sintering (SPS) technique using heating rates from 10 K min-1 to 380 K min-1 (10 °C min-1 to 380 °C min-1). The kinetics of densification and grain growth were analyzed to identify heating rate effects during the SPS of 93W-5.6Ni-1.4Fe powders. The activation energies for densification were calculated and compared with the experimental values for diffusion and other mass transport phenomena. The results show that for the slowly heated specimens [heating rate <100 K min-1 (100 °C min-1)], densification occurs mainly through dissolution-precipitation of W through the matrix phase and W grain boundary diffusion. The concurrent grain growth is dominated by surface diffusion at a low sintering temperature and by solution-reprecipitation and Ni-enhanced W grain boundary diffusion at a higher temperature. For the specimens sintered with heating rates higher than 100 K min-1 (100 °C min-1), the apparent activation energy value for the mechanism controlling densification is a strong function of the relative density, and fast densification controlled by multiple diffusion mechanisms and intensive viscous flow dominates over the grain growth. High SPS heating rate is favorable to obtain high density and fine-grained tungsten heavy alloys.

  9. 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.

  10. Crystal structure instability of FeSe grains: Formation of non-superconducting phase at the grain surface

    NASA Astrophysics Data System (ADS)

    Izawa, Hiroki; Tanaka, Yuji; Mizuguchi, Yoshikazu; Miura, Osuke

    2016-05-01

    We investigated the magnetization and crystal structure of FeSe polycrystalline samples with various grain sizes. For the samples with large grains, a large magnetic critical current density J c was observed. For the samples with small grains, superconductivity signals were not observed; instead, magnetization hysteresis, which is not a result of superconductivity, was observed. In the X-ray diffraction pattern for the samples with small grains, broad additional peaks were observed, corresponding to the formation of the non-superconducting (monoclinic) Fe–Se phase at the FeSe grain surface. The crystal structure instability at the grain surface would be the reason for the low superconducting properties of the Fe-chalcogenide polycrystalline wires investigated thus far.

  11. 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...

  12. Interstellar Grain Surface Chemistry

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M.; Cuzzi, Jeffrey N. (Technical Monitor)

    1995-01-01

    Chemistry on grain surfaces plays an Important role in the formation of interstellar Ices, It can also influence the composition of the gas phase through outgassing near luminous, newly formed stars. This paper reviews the chemical processes taking place on Interstellar grain surfaces with the emphasis on those transforming CO into other hydrocarbons. At low, molecular cloud temperatures (approximately equal to 10K), physisorption processes dominate interstellar grain surface chemistry and GO is largely hydrogenated through reactions with atomic H and oxidized through reactions with atomic O. The former will lead to the formation of H2CO and CH3OH ices, while the latter results in CO2 ice. The observational evidence for these ices in molecular clouds will be discussed. Very close to protostars, the gas and grain temperatures are much higher (approximately equal to 500K) and chemisorption processes, including catalytic surface reactions, becomes important. This will be illustrated based upon our studies of the Fischer-Tropsch Synthesis of CH4 from CO on metallic surfaces. Likely, this process has played an important role in the early solar nebula. Observational consequences will be pointed out.

  13. A systematic investigation of acetylene activation and hydracyanation of the activated acetylene on Aun (n = 3-10) clusters via density functional theory.

    PubMed

    Gautam, Seema; Sarkar, Abir De

    2016-05-18

    A systematic investigation of the selective catalytic conversion of poisonous HCN gas through hydracyanation of C2H2 activated on Au clusters, presented here for the first time, is of paramount importance from both scientific and technological perspectives. Hydracyanation of activated acetylene on an Au-cluster based catalyst leads to vinyl isocyanide (H2C[double bond, length as m-dash]CHNC) formation, a versatile chemical intermediate. Using density functional theory, bond activation of acetylene and selective catalytic hydracyanation of activated acetylene on small gold clusters Aun (n = 3-10) have been studied through a detailed analysis of the geometric and electronic structures. Different possible complexes of Aun-CHCH have been studied and two possible modes of adsorption of acetylene over the gold clusters, namely, the π- and di-σ modes, have been observed. The hydracyanation of the acetylene molecule is found to occur via the cleavage of one of acetylene triple bonds at the cost of formation of two Au-C bonds followed by the binding of HCN to the activated C[double bond, length as m-dash]C bond via nitrogen's lone pair. Preferential binding sites for HCN and C2H2 are analyzed through Fukui function calculations, frontier molecular orbital analysis and natural population charge distribution analysis. Based on adsorption energies, odd-sized Aun clusters are found to be significantly more favorable for C2H2 adsorption with the C-C bond stretching up to 1.31 Å with respect to the C-C triple bond length of 1.21 Å in the gas phase. The stretching frequency of adsorbed complexes, C2H2/Aun, (3460 cm(-1)), decreases notably relative to the frequency of the free acetylene molecule (7948 cm(-1)), which is a signature of the bond activation of the acetylene molecule over the Au clusters. The high adsorption energy of HCN on the Au9-C2H2 complex implies the considerable binding strength and activation of C2H2 and HCN on the Au9 clusters. Due to the importance of

  14. NADPH oxidase activation contributes to native low-density lipoprotein-induced proliferation of human aortic smooth muscle cells

    PubMed Central

    Park, Il Hwan; Hwang, Hye Mi; Jeon, Byeong Hwa; Kwon, Hyung-Joo; Hoe, Kwang Lae; Kim, Young Myeong; Ryoo, Sungwoo

    2015-01-01

    Elevated plasma concentration of native low-density lipoprotein (nLDL) is associated with vascular smooth muscle cell (VSMC) activation and cardiovascular disease. We investigated the mechanisms of superoxide generation and its contribution to pathophysiological cell proliferation in response to nLDL stimulation. Lucigenin-induced chemiluminescence was used to measure nLDL-induced superoxide production in human aortic smooth muscle cells (hAoSMCs). Superoxide production was increased by nicotinamide adenine dinucleotide phosphate (NADPH) and decreased by NADPH oxidase inhibitors in nLDL-stimulated hAoSMC and hAoSMC homogenates, as well as in prepared membrane fractions. Extracellular signal-regulated kinase 1/2 (Erk1/2), protein kinase C-θ (PKCθ) and protein kinase C-β (PKCβ) were phosphorylated and maximally activated within 3 min of nLDL stimulation. Phosphorylated Erk1/2 mitogen-activated protein kinase, PKCθ and PKCβ stimulated interactions between p47phox and p22phox; these interactions were prevented by MEK and PKC inhibitors (PD98059 and calphostin C, respectively). These inhibitors decreased nLDL-dependent superoxide production and blocked translocation of p47phox to the membrane, as shown by epifluorescence imaging and cellular fractionation experiments. Proliferation assays showed that a small interfering RNA against p47phox, as well as superoxide scavenger and NADPH oxidase inhibitors, blocked nLDL-induced hAoSMC proliferation. The nLDL stimulation in deendothelialized aortic rings from C57BL/6J mice increased dihydroethidine fluorescence and induced p47phox translocation that was blocked by PD98059 or calphostin C. Isolated aortic SMCs from p47phox−/− mice (mAoSMCs) did not respond to nLDL stimulation. Furthermore, NADPH oxidase 1 (Nox1) was responsible for superoxide generation and cell proliferation in nLDL-stimulated hAoSMCs. These data demonstrated that NADPH oxidase activation contributed to cell proliferation in nLDL-stimulated h

  15. 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.

  16. 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

  17. Effect of chronic activity-based therapy on bone mineral density and bone turnover in persons with spinal cord injury

    PubMed Central

    Harness, Eric T.; Witzke, Kara A.

    2014-01-01

    Purpose Osteoporosis is a severe complication of spinal cord injury (SCI). Many exercise modalities are used to slow bone loss, yet their efficacy is equivocal. This study examined the effect of activity-based therapy (ABT) targeting the lower extremities on bone health in individuals with SCI. Methods Thirteen men and women with SCI (age and injury duration = 29.7 ± 7.8 and 1.9 ± 2.7 years) underwent 6 months of ABT. At baseline and after 3 and 6 months of training, blood samples were obtained to assess bone formation (serum procollagen type 1 N propeptide (PINP) and bone resorption (serum C-terminal telopeptide of type I collagen (CTX), and participants underwent dual-energy X-ray absorptiometry scans to obtain total body and regional estimates of bone mineral density (BMD). Results Results demonstrated significant increases (p < 0.05) in spine BMD (+4.8 %; 1.27 ± 0.22–1.33 ± 0.24 g/cm2) and decreases (p < 0.01) in total hip BMD (−6.1 %; 0.98 ± 0.18–0.91 ± 0.16 g/cm2) from 0 to 6 months of training. BMD at the bilateral distal femur (−7.5 to −11.0 %) and proximal tibia (− 8.0 to −11.2 %) declined but was not different (p > 0.05) versus baseline. Neither PINP nor CTX was altered (p> 0.05) with training. Conclusions Chronic activity-based therapy did not reverse bone loss typically observed soon after injury, yet reductions in BMD were less than the expected magnitude of decline in lower extremity BMD in persons with recent SCI. PMID:24097172

  18. Genetic variation in peroxisome proliferator-activated receptor gamma, soy, and mammographic density in Singapore Chinese women

    PubMed Central

    Lee, Eunjung; Hsu, Chris; Van den Berg, David; Ursin, Giske; Koh, Woon-Puay; Yuan, Jian-Min; Stram, Daniel O.; Yu, Mimi C.; Wu, Anna H.

    2012-01-01

    Background Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor important for adipogenesis and adipocyte differentiation. Data from animal studies suggest that PPARγ may be involved in breast tumorigenesis, but results from epidemiologic studies on the association between PPARγ variation and breast cancer risk have been mixed. Recent data suggest that soy isoflavones can activate PPARγ. We investigated the inter-relations of soy, PPARγ, and mammographic density (MD), a biomarker of breast cancer risk in a cross-sectional study of 2,038 women who were members of the population-based Singapore Chinese Health Study Cohort. Methods We assessed MD using a computer-assisted method. We used linear regression to examine the association between 26 tagging SNPs of PPARγ and their interaction with soy intake and MD. To correct for multiple testing, we calculated P-values adjusted for multiple correlated tests (PACT). Results Out of the 26 tested SNPs in the PPARγ, 6 SNPs were individually shown to be statistically significantly associated with MD (PACT=0.004∼0.049). A stepwise regression procedure identified that only rs880663 was independently associated with MD which decreased by 1.89% per minor allele (PACT=0.008).This association was significantly stronger in high soy consumers as MD decreased by 3.97% per minor allele of rs880663 in high soy consumers (PACT=0.006; P for interaction with lower soy intake=0.017). Conclusions Our data support that PPARγ genetic variation may be important in determining MD, particularly in high soy consumers. Impact Our findings may help to identify molecular targets and lifestyle intervention for future prevention research. PMID:22301832

  19. Effects of tryptophan supplementation on growth performance, antioxidative activity, and meat quality of ducks under high stocking density.

    PubMed

    Liu, Y; Yuan, J M; Zhang, L S; Zhang, Y R; Cai, S M; Yu, J H; Xia, Z F

    2015-08-01

    High stocking density (STD) could affect duck welfare and production. The objective of our study was to investigate whether dietary tryptophan (TRP) supplementation could alleviate the detrimental effects of high STD on ducks. White Pekin ducks at 4 to 6 wk of age were raised at 11 birds/m(2) and fed diets containing 0.18, 0.48, 0.78, or 1.08% TRP for 21 d. Growth performance, concentrations of TRP and metabolites in the blood and hypothalamus, antioxidative activities in serum and tissue, meat quality, serum uric acid, and urea nitrogen were measured. Weight gain and feed efficiency were significantly improved by TRP supplementation at ≥ 0.48 and ≥ 0.78% (P < 0.05 and P < 0.001, respectively). Serum TRP, hypothalamic TRP, 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacitic acid (5-HIAA), and 5-HIAA/5-HT were also increased significantly (P < 0.01). These increases plateaued at 0.48% TRP, and no further improvement was obtained by adding more TRP to the diet. Dietary TRP supplementation significantly increased levels of total antioxidant capacity, glutathione peroxidase (GSH-Px), and catalase (CAT) in serum; GSH-Px in liver; and GSH-Px and CAT in breast muscle (P < 0.05). Malondialdehyde levels in breast muscle decreased (P < 0.001). Drip loss of breast muscle and pH decline at 45 min postmortem were reduced by TRP supplementation (P < 0.01 and P < 0.05, respectively). Meat color was similar among different treatments (P > 0.05). Breast muscle shear force was increased significantly when dietary TRP level increased to 1.08% (P < 0.01). For ducks raised at 11 birds/m², dietary TRP supplementation could alleviate stress and improve growth performance, antioxidative activity, and meat quality. PMID:26089478

  20. Effect of High Impact or Non-impact Loading Activity on Bone Bending Stiffness and Mineral Density

    NASA Technical Reports Server (NTRS)

    Liang, Michael T. C.; Arnnud, Sara B.; Steele, Charles R.; Moreno, Alexjandro

    2003-01-01

    Material properties of conical bone, including mineral density (BMD) and its geometry is closely related to its load-carrying capacity. These two primary components determine the strength of conical bone. High impact loading involving acceleration and deceleration movements used in gymnastics induce higher BMD of the affected bone compared to the non-impact acceleration and deceleration movements used in swimming. Study of these two groups of athletes on bone bending stiffness has not been reported. The purpose of this study was to compare differences in bone bending stiffness and BMD between competitive female synchronized swimmers and female gymnasts. Thirteen world class female synchronized swimmers (SYN) and 8 female gymnasts (GYM), mean age 21 +/- 2.9 yr. were recruited for this study. We used a mechanical response tissue analyzer (Gaitscan, NJ) to calculate EI, where E is Young's modulus of elasticity and I is the cross-sectional moment of inertia. EI was obtained from tissue response to a vibration probe placed directly on the skin of the mid-region of tibia and ulna. BMD of the heel and wrist were measured with a probe densitometer (PIXI, Lunor, WI). The SYN were taller than (p < 0.05) the GYM but weighed the same as the GYM. EI obtained from tibia and ulna of the SYN (291 +/- 159 and 41 +/- 19.4, respectively) were not significantly different from thc GYM (285 +/- 140 and 44 +/- 18.3, respectively). BMD of the heel and wrist in GYM were higher than in SYN (p < 0.001). High impact weight-bearing activities promote similar bone strength but greater BMD response than non-impact activities performed in a buoyant environment.

  1. Circulating oxidized low-density lipoproteins and arterial elasticity: comparison between men with metabolic syndrome and physically active counterparts

    PubMed Central

    2010-01-01

    Background Accumulation of oxidized low-density lipoproteins in the intimae of arteries and endothelial dysfunction are key events in the development of atherosclerosis. Patients with metabolic syndrome are at high risk for cardiovascular diseases but the linkage between metabolic syndrome and atherosclerosis is incompletely understood. We studied whether the levels of oxidized LDL and arterial elasticity differ between metabolic syndrome patients and physically active controls. Methods 40 men with metabolic syndrome and 40 physically active controls participated in this cross-sectional study. None of the study subjects had been diagnosed with cardiovascular disease. Levels of oxidized LDL were assessed by a two-site ELISA immunoassay. Arterial elasticity was assessed non-invasively by the HDI/PulseWave™ CR-2000 arterial tonometer. Results Levels of oxidized LDL were 89.6 ± 33.1 U/L for metabolic syndrome subjects and 68.5 ± 23.6 U/L for controls (p = 0.007). The difference remained significant after adjustment for LDL cholesterol. Large artery elasticity index (C1) was 16.2 ± 4.1 mL/mmHgx10 for metabolic syndrome subjects and 19.4 ± 3.7 mL/mmHgx10 for controls (p = 0.001), small artery indices (C2) were 7.0 ± 3.2 mL/mmHgx100 and 6.5 ± 2.9 mL/mmHgx100 (NS), respectively. Conclusions Subjects with metabolic syndrome had elevated levels of oxidized LDL and reduced large arterial elasticity compared to controls. This finding may partly explain the increased risk for cardiovascular diseases among metabolic syndrome patients. Trial registration ClinicalTrials.gov NCT01114763 PMID:20727144

  2. High density active-site MnO{sub 2} nanofibers for energy storage and conversion applications

    SciTech Connect

    Xiao, T.D.; Reisner, D.E.; Strutt, P.R.

    1998-07-01

    This investigation involves the synthesis of MnO{sub 2} nanofibrous materials, via an aqueous chemical synthesis route. A critical step in the synthesis is the extended period of the refluxing of the reactive constituents, which enables the gradual transformation of the initial amorphous nanoparticles into a random-weave nanofibrous structure, in the form of a bird's nest superstructure. The bird's nest has a diameter of approximately 10 {micro}m, which is an assemblage of many individual nanofibers with a diameter of about 15 nm, and a length up to 1 {micro}m. Partial transformation of the nanostructured MnO{sub 2} realizes a novel bimodal morphology, which combines a high density of chemically active sites with an enhanced percolation rate. Characterization of these nanofibers include SEM, TEM, surface area, and chemical analysis. High resolution TEM observations reveals that the as-synthesized MnO{sub 2} nanofibers contain lattice defects, including molecular pores, meso- and micro-pores.

  3. Density functional theory based calculations of the transfer integral in a redox-active single-molecule junction

    NASA Astrophysics Data System (ADS)

    Kastlunger, Georg; Stadler, Robert

    2014-03-01

    There are various quantum chemical approaches for an ab initio description of transfer integrals within the framework of Marcus theory in the context of electron transfer reactions. In our paper, we aim to calculate transfer integrals in redox-active single molecule junctions, where we focus on the coherent tunneling limit with the metal leads taking the position of donor and acceptor and the molecule acting as a transport mediating bridge. This setup allows us to derive a conductance, which can be directly compared with recent results from a nonequilibrium Green's function approach. Compared with purely molecular systems we face additional challenges due to the metallic nature of the leads, which rules out some of the common techniques, and due to their periodicity, which requires k-space integration. We present three different methods, all based on density functional theory, for calculating the transfer integral under these constraints, which we benchmark on molecular test systems from the relevant literature. We also discuss many-body effects and apply all three techniques to a junction with a Ruthenium complex in different oxidation states.

  4. Normal human IgG prevents endothelial cell activation induced by TNFα and oxidized low-density lipoprotein atherogenic stimuli

    PubMed Central

    RONDA, N; BERNINI, F; GIACOSA, R; GATTI, R; BALDINI, N; BUZIO, C; ORLANDINI, G

    2003-01-01

    Normal human immunoglobulin G (IgG) has anti-inflammatory and immuno-regulatory properties, which are exploited in the therapy of selected diseases. A putative mechanisms of action is the direct regulation of endothelial cell function by natural antiendothelial cell antibodies. Endothelium activation is a critical event in atherosclerosis. We have verified the ability of normal human IgG to modulate endothelial responses to the atherogenic stimuli tumour necrosis factor-α (TNFα) and oxidized low-density lipoproteins (oxLDL) in vitro. Confocal microscopy was used to visualize vascular cell adhesion molecule-1 (CD106) expression on endothelial cells, cytoplasmic free calcium ([Ca++]i) modifications and fluorescein-coupled oxLDL internalization. Cytokine secretion was measured by ELISA on cell supernatants. IgG prevented TNFα induced CD106 membrane expression and an increase in [Ca++]i, and inhibited the secretion of interleukin-6 (IL-6) and macrophage-colony-stimulating factor (M-CSF). IgG also inhibited CD106 expression induced by oxLDL and one pathway of their internalization, but were ineffective on oxLDL induced [Ca++]i rise and apoptosis. F(ab)′2 fragments from IgG, but not monoclonal IgG, reproduce IgG effects. These findings point to a regulatory role for specific antibodies included in circulating normal IgG towards proinflammatory responses of endothelial cells in atherogenesis and suggest possible development of new therapeutic strategies. PMID:12869027

  5. Higher Media Multi-Tasking Activity Is Associated with Smaller Gray-Matter Density in the Anterior Cingulate Cortex

    PubMed Central

    Loh, Kep Kee; Kanai, Ryota

    2014-01-01

    Media multitasking, or the concurrent consumption of multiple media forms, is increasingly prevalent in today’s society and has been associated with negative psychosocial and cognitive impacts. Individuals who engage in heavier media-multitasking are found to perform worse on cognitive control tasks and exhibit more socio-emotional difficulties. However, the neural processes associated with media multi-tasking remain unexplored. The present study investigated relationships between media multitasking activity and brain structure. Research has demonstrated that brain structure can be altered upon prolonged exposure to novel environments and experience. Thus, we expected differential engagements in media multitasking to correlate with brain structure variability. This was confirmed via Voxel-Based Morphometry (VBM) analyses: Individuals with higher Media Multitasking Index (MMI) scores had smaller gray matter density in the anterior cingulate cortex (ACC). Functional connectivity between this ACC region and the precuneus was negatively associated with MMI. Our findings suggest a possible structural correlate for the observed decreased cognitive control performance and socio-emotional regulation in heavy media-multitaskers. While the cross-sectional nature of our study does not allow us to specify the direction of causality, our results brought to light novel associations between individual media multitasking behaviors and ACC structure differences. PMID:25250778

  6. 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.

  7. The effect of grain size on the biocompatibility, cell-materials interface, and mechanical properties of microwave-sintered bioceramics.

    PubMed

    Veljović, Djordje; Colić, Miodrag; Kojić, Vesna; Bogdanović, Gordana; Kojić, Zvezdana; Banjac, Andrijana; Palcevskis, Eriks; Petrović, Rada; Janaćković, Djordje

    2012-11-01

    The effect of decreasing the grain size on the biocompatibility, cell-material interface, and mechanical properties of microwave-sintered monophase hydroxyapatite bioceramics was investigated in this study. A nanosized stoichiometric hydroxyapatite powder was isostatically pressed at high pressure and sintered in a microwave furnace in order to obtain fine grained dense bioceramics. The samples sintered at 1200°C, with a density near the theoretical one, were composed of micron-sized grains, while the grain size decreased to 130 nm on decreasing the sintering temperature to 900°C. This decrease in the grain size certainly led to increases in the fracture toughness by much as 54%. An in vitro investigation of biocompatibility with L929 and human MRC-5 fibroblast cells showed noncytotoxic effects for both types of bioceramics, while the relative cell proliferation rate, cell attachment and metabolic activity of the fibroblasts were improved with decreasing of grain size. An initial in vivo investigation of biocompatibility by the primary cutaneous irritation test showed that both materials exhibited no irritation properties. PMID:22733649

  8. Unfolding grain size effects in barium titanate ferroelectric ceramics

    PubMed Central

    Tan, Yongqiang; Zhang, Jialiang; Wu, Yanqing; Wang, Chunlei; Koval, Vladimir; Shi, Baogui; Ye, Haitao; McKinnon, Ruth; Viola, Giuseppe; Yan, Haixue

    2015-01-01

    Grain size effects on the physical properties of polycrystalline ferroelectrics have been extensively studied for decades; however there are still major controversies regarding the dependence of the piezoelectric and ferroelectric properties on the grain size. Dense BaTiO3 ceramics with different grain sizes were fabricated by either conventional sintering or spark plasma sintering using micro- and nano-sized powders. The results show that the grain size effect on the dielectric permittivity is nearly independent of the sintering method and starting powder used. A peak in the permittivity is observed in all the ceramics with a grain size near 1 μm and can be attributed to a maximum domain wall density and mobility. The piezoelectric coefficient d33 and remnant polarization Pr show diverse grain size effects depending on the particle size of the starting powder and sintering temperature. This suggests that besides domain wall density, other factors such as back fields and point defects, which influence the domain wall mobility, could be responsible for the different grain size dependence observed in the dielectric and piezoelectric/ferroelectric properties. In cases where point defects are not the dominant contributor, the piezoelectric constant d33 and the remnant polarization Pr increase with increasing grain size. PMID:25951408

  9. The Relationship of Physical Activity and Anthropometric and Physiological Characteristics to Bone Mineral Density in Postmenopausal Women.

    PubMed

    Arazi, Hamid; Eghbali, Ehsan; Saeedi, Tahmineh; Moghadam, Roya

    2016-01-01

    The aim of this study is to investigate the relationship of physical activity and anthropometric and physiological characteristics to bone mineral density (BMD) in postmenopausal women. Ninety-seven postmenopausal women with an average age of 50.71 ± 6.86 yr were selected to participate in this study. After completing consent forms and the questionnaire on physical activity, the amounts of calcium and 25-hydroxyvitamin D levels in participants' blood were measured by blood tests. The BMDs of the subjects in the lumbar spine (L2-L4) and hip were measured by dual-energy X-ray absorptiometry device and the results were recorded. Also, anthropometric characteristics including height, weight, body fat percentage, body mass index, waist-to-hip ratio (WHR), digit ratio (2D:4D), skeletal muscle mass index, hand and calf circumferences and physiological parameters, including handgrip strength, quadriceps isotonic extension strength and balance of the subjects, were measured. The results showed that the 2D:4D ratio and skeletal muscle mass index had a significantly positive relationship with BMD of the lumbar spine (p ≤ 0.05) and the hip (p ≤ 0.05). Also, there was a negative relationship between the BMD of lumbar spine and hip and WHR (p ≤ 0.05). Moreover, there was a positive relationship between the calf circumferences and lumbar spine BMD (p ≤ 0.05). Contrary to this, there was no significant relationship between the calf circumference and the hip BMD, and between hand circumference with lumbar spine and hip BMD (p > 0.05). Results of physiological indices showed a significant positive relationship between physical activity, handgrip strength, quadriceps isotonic extension strength, standing on 1 foot with the lumbar spine and hip BMD (p ≤ 0.05). But the relationship was not observed between BMD and the ability to squat down on the floor (p > 0.05). Based on these results, it seemed that we can use some physiological and

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

    MedlinePlus

    ... B vitamins (thiamin, riboflavin, niacin, and folate), and minerals ( iron , magnesium , and selenium). Dietary fiber from whole grains or other foods, ... diets. Whole grains are sources of magnesium and selenium. Magnesium is a mineral used in building bones ...

  11. 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)].

  12. Dislocation density evolution during high pressure torsion of a nanocrystalline Ni-Fe alloy

    SciTech Connect

    Li, Hongqi; Wang, Y B; Ho, J C; Cao, Y; Liao, X Z; Ringer, S P; Zhu, Y T; Zhao, Y H; Lavernia, E J

    2009-01-01

    High-pressure torsion (HPT) induced dislocation density evolution in a nanocrystalline Ni-20wt.%Fe alloy was investigated using X-ray diffraction and transmission electron microscopy. Results suggest that the dislocation density evolution is different from that in coarse-grained materials. An HPT process first reduces the dislocation density within nanocrystalline grains and produces a large number of dislocations located at small-angle sub grain boundaries that are formed via grain rotation and coalescence. Continuing the deformation process eliminates the sub grain boundaries but significantly increases the dislocation density in grains. This phenomenon provides an explanation of the mechanical behavior of some nanostructured materials.

  13. Crossover Fields in Grain-Boundary Flux Pinning in Magnesium Diboride Films with Columnar Grains

    NASA Astrophysics Data System (ADS)

    Kim, D. H.; Hwang, T. J.; Seong, W. K.; Kang, W. N.

    We studied temperature and magnetic-field dependence of grain boundary pinning effect in MgB2 films with columnar grains by measuring the angular dependence of the resistivity and the critical current density (Jc). MgB2 films grown by using a hybrid physical chemical vapor deposition method under appropriate conditions exhibit a peculiar columnar growth with their columns oriented along the c axis. The pinning effect by grain boundaries was manifested in the comparable or even higher Jc for magnetic fields (H) parallel to the c axis (H‖c) than that for fields parallel to the ab plane (H‖ab) below certain temperature-dependent crossover fields. The crossover field, Bcr, was around 1.6 T at 5 K and decreased to around 0.9 T at 30 K depending weakly on the sample characters, and Bcr lay well below the upper critical fields in the phase diagram. Above Bcr, Jc for H‖c decreased very rapidly. The vortex spacing at Bcr was closely correlated with the temperature dependence of the penetration depth, indicating that the degree of the vortex-vortex overlap is an important parameter to determine the number of vortices allowed per unit length of grain boundaries. Thus, Bcr was thought to demarcate the accommodation capability of flux lines by the grain boundaries, and a rapid decrease of Jc above Bcr was ascribed to flux motion of the less strongly pinned vortices located away from the grain boundaries.

  14. Grain Development Mutants of Barley ([alpha]-Amylase Production during Grain Maturation and Its Relation to Endogenous Gibberellic Acid Content).

    PubMed Central

    Green, L. S.; Faergestad, E. M.; Poole, A.; Chandler, P. M.

    1997-01-01

    Barley (Hordeum vulgare L. Himalaya) mutants with altered grain morphology were isolated to investigate whether defects in grain development, possibly involving gibberellins (GAs) and abscisic acid, would lead to altered patterns of [alpha]-amylase gene expression. Following treatment with sodium azide, 75 mutants, typically showing grain shriveling, were identified. At grain maturity 15 of the 75 mutants had higher [alpha]-amylase activities in shriveled grains compared with either phenotypically normal grains that developed on the same heterozygous plant or with grains of cv Himalaya. Studies of four of these mutants demonstrated increased levels of both high- and low-isoelectric point [alpha]-amylase isozymes midway through grain development. This category of mutant has been designated pga, for premature grain [alpha]-amylase. One such mutant (M326) showed an endosperm-determined inheritance pattern. When crossed into a (GA-deficient) dwarfing background there was a 10- to 20-fold reduction in [alpha]-amylase activity, suggesting a requirement for GA biosynthesis. Endogenous GAs and abscisic acid were quantified by combined gas chromatography-specific ion monitoring in normal and mutant grains of heterozygous M326 plants during the period of [alpha]-amylase accumulation. Mutant grains had significantly higher (5.8-fold) levels of the bioactive GA1 compared with normal grains but much lower (approximately 10-fold) levels of the 2[beta]-hydroxylated ("inactive") GAs, typical of developing barley grains (e.g. GA8, GA34, GA48). We propose that a reduced extent of 2[beta]-hydroxylation in the mutant grains results in an increased level of GA1, which is responsible for premature [alpha]-amylase gene expression. PMID:12223700

  15. Spatial correlation of high-energy grain boundaries in two-dimensional simulated polycrystals

    SciTech Connect

    Clinton DeW. Van Siclen

    2007-02-01

    A polycrystal undergoes microstructural changes to reach a lower energy state. In particular, the system evolves so as to reduce the total grain boundary energy. A simple two-dimensional model of a polycrystal comprised of randomly oriented crystalline grains suggests that energy minimization reduces or eliminates any spatial correlation among high-energy grain boundaries. Thus grain boundary engineering not only reduces the density of high-energy boundaries, but it prevents their organization into a coarse, albeit discontinuous, network.

  16. Potential barrier height at the grain boundaries of a poly-silicon nanowire.

    PubMed

    Shamir, Assaf; Amit, Iddo; Englander, Danny; Horvitz, Dror; Rosenwaks, Yossi

    2015-09-01

    We present measurements of the potential barrier height and its dependence on grain size in poly-silicon nanowire (P-SiNW) arrays. Measurements conducted using Kelvin probe force microscopy coupled with electrostatic simulations, enabled us also to extract the density of the grain boundary interface states and their energy distribution. In addition it was shown that the barrier height scales with the grain size as the square of the grain radius. PMID:26245190

  17. 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.

  18. 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.

  19. Opposite Effects of mGluR1a and mGluR5 Activation on Nucleus Accumbens Medium Spiny Neuron Dendritic Spine Density.

    PubMed

    Gross, Kellie S; Brandner, Dieter D; Martinez, Luis A; Olive, M Foster; Meisel, Robert L; Mermelstein, Paul G

    2016-01-01

    The group I metabotropic glutamate receptors (mGluR1a and mGluR5) are important modulators of neuronal structure and function. Although these receptors share common signaling pathways, they are capable of having distinct effects on cellular plasticity. We investigated the individual effects of mGluR1a or mGluR5 activation on dendritic spine density in medium spiny neurons in the nucleus accumbens (NAc), which has become relevant with the potential use of group I mGluR based therapeutics in the treatment of drug addiction. We found that systemic administration of mGluR subtype-specific positive allosteric modulators had opposite effects on dendritic spine densities. Specifically, mGluR5 positive modulation decreased dendritic spine densities in the NAc shell and core, but was without effect in the dorsal striatum, whereas increased spine densities in the NAc were observed with mGluR1a positive modulation. Additionally, direct activation of mGluR5 via CHPG administration into the NAc also decreased the density of dendritic spines. These data provide insight on the ability of group I mGluRs to induce structural plasticity in the NAc and demonstrate that the group I mGluRs are capable of producing not just distinct, but opposing, effects on dendritic spine density. PMID:27618534

  20. COMMINGLING EFFECTS AND RESIDUAL GRAIN DURING GRAIN RECEIVING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concern about the possible effects of genetically modified crops has increased the demand for segregating grains during handling and processing operations. Research on the amount of commingling of different grains in an elevator is limited. This study evaluated the level of commingling at a grain ...